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Luo Y, Yamada M, N’Tumba-Byn T, Asif H, Gao M, Hu Y, Marangoni P, Liu Y, Evans T, Rafii S, Klein OD, Voss HU, Hadjantonakis AK, Elemento O, Martin LA, Seandel M. SPRY4-dependent ERK negative feedback demarcates functional adult stem cells in the male mouse germline†. Biol Reprod 2023; 109:533-551. [PMID: 37552049 PMCID: PMC10577279 DOI: 10.1093/biolre/ioad089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 06/28/2023] [Accepted: 08/05/2023] [Indexed: 08/09/2023] Open
Abstract
Niche-derived growth factors support self-renewal of mouse spermatogonial stem and progenitor cells through ERK MAPK signaling and other pathways. At the same time, dysregulated growth factor-dependent signaling has been associated with loss of stem cell activity and aberrant differentiation. We hypothesized that growth factor signaling through the ERK MAPK pathway in spermatogonial stem cells is tightly regulated within a narrow range through distinct intracellular negative feedback regulators. Evaluation of candidate extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK)-responsive genes known to dampen downstream signaling revealed robust induction of specific negative feedback regulators, including Spry4, in cultured mouse spermatogonial stem cells in response to glial cell line-derived neurotrophic factor or fibroblast growth factor 2. Undifferentiated spermatogonia in vivo exhibited high levels of Spry4 mRNA. Quantitative single-cell analysis of ERK MAPK signaling in spermatogonial stem cell cultures revealed both dynamic signaling patterns in response to growth factors and disruption of such effects when Spry4 was ablated, due to dysregulation of ERK MAPK downstream of RAS. Whereas negative feedback regulator expression decreased during differentiation, loss of Spry4 shifted cell fate toward early differentiation with concomitant loss of stem cell activity. Finally, a mouse Spry4 reporter line revealed that the adult spermatogonial stem cell population in vivo is demarcated by strong Spry4 promoter activity. Collectively, our data suggest that negative feedback-dependent regulation of ERK MAPK is critical for preservation of spermatogonial stem cell fate within the mammalian testis.
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Affiliation(s)
- Yanyun Luo
- Department of Surgery, Weill Cornell Medicine, New York, NY, USA
| | - Makiko Yamada
- Department of Surgery, Weill Cornell Medicine, New York, NY, USA
| | | | - Hana Asif
- Department of Surgery, Weill Cornell Medicine, New York, NY, USA
| | - Meng Gao
- Department of Surgery, Weill Cornell Medicine, New York, NY, USA
| | - Yang Hu
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Pauline Marangoni
- Program in Craniofacial Biology, Department of Orofacial Sciences, University of California, San Francisco, CA, USA
- Department of Pediatrics and Institute for Human Genetics, University of California, San Francisco, CA, USA
| | - Ying Liu
- Division of Regenerative Medicine, Department of Medicine, Hartman Institute for Therapeutic Organ Regeneration, Ansary Stem Cell Institute, Weill Cornell Medicine, New York, NY, USA
| | - Todd Evans
- Department of Surgery, Weill Cornell Medicine, New York, NY, USA
| | - Shahin Rafii
- Division of Regenerative Medicine, Department of Medicine, Hartman Institute for Therapeutic Organ Regeneration, Ansary Stem Cell Institute, Weill Cornell Medicine, New York, NY, USA
| | - Ophir D Klein
- Program in Craniofacial Biology, Department of Orofacial Sciences, University of California, San Francisco, CA, USA
- Department of Pediatrics and Institute for Human Genetics, University of California, San Francisco, CA, USA
| | - Henning U Voss
- College of Human Ecology, Cornell University, Ithaca, NY, USA
| | - Anna-Katerina Hadjantonakis
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Olivier Elemento
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
- Department of Physiology and Biophysics, Caryl and Israel Englander Institute for Precision Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Laura A Martin
- The New York Stem Cell Foundation Research Institute, New York, NY, USA
| | - Marco Seandel
- Department of Surgery, Weill Cornell Medicine, New York, NY, USA
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Seewald M, Harris LH, Martin LA, Simon A. POSTER ABSTRACTS. Contraception 2021. [DOI: 10.1016/j.contraception.2021.07.094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Yamada M, Cai W, Martin LA, N’Tumba-Byn T, Seandel M. Functional robustness of adult spermatogonial stem cells after induction of hyperactive Hras. PLoS Genet 2019; 15:e1008139. [PMID: 31050682 PMCID: PMC6519842 DOI: 10.1371/journal.pgen.1008139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 05/15/2019] [Accepted: 04/15/2019] [Indexed: 01/07/2023] Open
Abstract
Accumulating evidence indicates that paternal age correlates with disease risk in children. De novo gain-of-function mutations in the FGF-RAS-MAPK signaling pathway are known to cause a subset of genetic diseases associated with advanced paternal age, such as Apert syndrome, achondroplasia, Noonan syndrome, and Costello syndrome. It has been hypothesized that adult spermatogonial stem cells with pathogenic mutations are clonally expanded over time and propagate the mutations to offspring. However, no model system exists to interrogate mammalian germline stem cell competition in vivo. In this study, we created a lineage tracing system, which enabled undifferentiated spermatogonia with endogenous expression of HrasG12V, a known pathogenic gain-of-function mutation in RAS-MAPK signaling, to compete with their wild-type counterparts in the mouse testis. Over a year of fate analysis, neither HrasG12V-positive germ cells nor sperm exhibited a significant expansion compared to wild-type neighbors. Short-term stem cell capacity as measured by transplantation analysis was also comparable between wild-type and mutant groups. Furthermore, although constitutively active HRAS was detectable in the mutant cell lines, they did not exhibit a proliferative advantage or an enhanced response to agonist-evoked pERK signaling. These in vivo and in vitro results suggest that mouse spermatogonial stem cells are functionally resistant to a heterozygous HrasG12V mutation in the endogenous locus and that mechanisms could exist to prevent such harmful mutations from being expanded and transmitted to the next generation. Recent research has found that advanced paternal age is associated with increased risk in children to develop a subset of congenital anomalies, such as Apert syndrome, achondroplasia, Noonan syndrome, and Costello syndrome. The causative genetic errors (mutations) in these disorders have been identified to originate from the fathers’ testicles and their numbers increase with fathers’ age. It has been hypothesized that the germline stem cells that continuously self-renew and differentiate to supply sperm (referred as spermatogonial stem cells [SSCs]) carry these mutations and have the ability to expand preferentially as compared to normal SSCs with advancing age of the father, thereby increasing the likelihood of transmission of mutant sperm to the next generation. To test this hypothesis, we created a mouse model, in which a mutation known to enhance cell proliferation is induced in a subset of SSCs, and these cells compete with the neighboring normal (i.e., wild-type) stem cells. However, surprisingly, the germline cell population carrying the mutation in the testis was stable over a year of observation, suggesting that mechanisms could exist to prevent such harmful mutations from being expanded and transmitted to the next generation.
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Affiliation(s)
- Makiko Yamada
- Department of Surgery, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail: (MY); (MS)
| | - Winson Cai
- Department of Surgery, Weill Cornell Medical College, New York, New York, United States of America
| | - Laura A. Martin
- Department of Surgery, Weill Cornell Medical College, New York, New York, United States of America
| | - Thierry N’Tumba-Byn
- Department of Surgery, Weill Cornell Medical College, New York, New York, United States of America
| | - Marco Seandel
- Department of Surgery, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail: (MY); (MS)
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Robinson CL, Chong ACN, Ashbrook AW, Jeng G, Jin J, Chen H, Tang EI, Martin LA, Kim RS, Kenyon RM, Do E, Luna JM, Saeed M, Zeltser L, Ralph H, Dudley VL, Goldstein M, Rice CM, Cheng CY, Seandel M, Chen S. Male germ cells support long-term propagation of Zika virus. Nat Commun 2018; 9:2090. [PMID: 29844387 PMCID: PMC5974187 DOI: 10.1038/s41467-018-04444-w] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 04/26/2018] [Indexed: 01/22/2023] Open
Abstract
Evidence of male-to-female sexual transmission of Zika virus (ZIKV) and viral RNA in semen and sperm months after infection supports a potential role for testicular cells in ZIKV propagation. Here, we demonstrate that germ cells (GCs) are most susceptible to ZIKV. We found that only GCs infected by ZIKV, but not those infected by dengue virus and yellow fever virus, produce high levels of infectious virus. This observation coincides with decreased expression of interferon-stimulated gene Ifi44l in ZIKV-infected GCs, and overexpression of Ifi44l results in reduced ZIKV production. Using primary human testicular tissue, we demonstrate that human GCs are also permissive for ZIKV infection and production. Finally, we identified berberine chloride as a potent inhibitor of ZIKV infection in both murine and human testes. Together, these studies identify a potential cellular source for propagation of ZIKV in testes and a candidate drug for preventing sexual transmission of ZIKV.
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Affiliation(s)
- Christopher L Robinson
- Department of Surgery, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA
| | - Angie C N Chong
- Department of Surgery, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA
| | - Alison W Ashbrook
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY, 10065, USA
| | - Ginnie Jeng
- Department of Surgery, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA
| | - Julia Jin
- Department of Surgery, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA
| | - Haiqi Chen
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Avenue, New York, NY, 10065, USA
| | - Elizabeth I Tang
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Avenue, New York, NY, 10065, USA
| | - Laura A Martin
- Department of Surgery, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA
| | - Rosa S Kim
- Penn State College of Medicine, Hershey, PA, 17033, USA
| | - Reyn M Kenyon
- Department of Surgery, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA
| | - Eileen Do
- Department of Surgery, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA
| | - Joseph M Luna
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY, 10065, USA
| | - Mohsan Saeed
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY, 10065, USA
| | - Lori Zeltser
- Naomi Berrie Diabetes Center, Columbia University, New York, NY, 10032, USA.,Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA
| | - Harold Ralph
- Weill Cornell Medical College-Microscopy and Image Analysis Core Facility, 1300 York Avenue, New York, NY, 10065, USA
| | - Vanessa L Dudley
- Institute of Reproductive Medicine at Weill Cornell Medicine, Weill Cornell Medicine-New York Presbyterian Hospital, New York, NY, 10065, USA
| | - Marc Goldstein
- Department of Urology and Institute for Reproductive Medicine, Weill Cornell Medical College of Cornell University, New York, NY, 10065, USA
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY, 10065, USA
| | - C Yan Cheng
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, 1230 York Avenue, New York, NY, 10065, USA.
| | - Marco Seandel
- Department of Surgery, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA.
| | - Shuibing Chen
- Department of Surgery, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA. .,Department of Biochemistry, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA.
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Martin LA, Janzen R, Wong F, Doris P. Abstract P3-10-10: Planning and implementation of two regional one-stop breast health centres within a large geographic health authority: Outcomes and quality improvements in health service delivery. Cancer Res 2017. [DOI: 10.1158/1538-7445.sabcs16-p3-10-10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Interrogative examination of wait times for the pathway steps leading to diagnosis, surgical treatment, and oncology consultation for breast cancer within a geographically dispersed publically funded health authority led to advocacy for and establishment of two large one-stop Breast Health Centres (BHCs) within the largest urban cities. One year after publication of the 2000 EUSOMA guidelines for breast cancer diagnosis and treatment, regional breast cancer pathways and wait times did not meet guidelines. Population median wait time from date of first investigation to tissue diagnosis was 2.7 or 5.9 weeks (for clinical presentation or screen presentation respectively), 6.0/7.0 weeks to definitive surgical intervention, and 14.3/11.7 weeks to oncology consultation. Only 39 % of patients were diagnosed initially via core needle biopsy. 5 % of patients underwent immediate reconstructive surgery. Due to wait times for initial imaging (mammogram, ultrasound) at hospital facilities, baseline imaging was often performed at private imaging labs without needle diagnostic capability, and repeated again with a series of wait times at the hospitals - as the initial community images were not accessible to the hospital interventional radiologists. Smaller communities and their hospitals maintained shorter wait times in comparison to the large urban centres. Repeat population based measurement in 2009 indicated wait times were unchanged, and MRI guided biopsy was still not available within the region. Nursing support and patient education re breast cancer prognosis and treatment was not available until the time of oncology consultation.
BHCs were planned, funded by the Ministry of Health, established in physical conjunction with the breast screening programs, and became operational as of early 2012. During the first year of BHC operation, population median wait time from date of first investigation was 2.0 weeks for tissue diagnosis, 6.4 weeks for final definitive surgical intervention, and 9.4 weeks for oncology consultation. 90 % of patients were initially diagnosed via initial core needle biopsy with IHC staining for ER, PR, and HER2. Patients served by the BHCs had nurse navigator support and education from time of presentation. The surgical team overcame regional surgical wait time barriers such as available admission beds by establishing the first comprehensive population-based outpatient mastectomy and reconstruction program in Canada with over 1200 performed to date. These wait times have been maintained in spite of increase in the HA population from 1.2 million to 1.6 million during the project timeline.
Citation Format: Martin LA, Janzen R, Wong F, Doris P. Planning and implementation of two regional one-stop breast health centres within a large geographic health authority: Outcomes and quality improvements in health service delivery [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-10-10.
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Affiliation(s)
- LA Martin
- British Columbia Cancer Agency, Surrey, BC, Canada; Fraser Health Authority, Surrey, BC, Canada
| | - R Janzen
- British Columbia Cancer Agency, Surrey, BC, Canada; Fraser Health Authority, Surrey, BC, Canada
| | - F Wong
- British Columbia Cancer Agency, Surrey, BC, Canada; Fraser Health Authority, Surrey, BC, Canada
| | - P Doris
- British Columbia Cancer Agency, Surrey, BC, Canada; Fraser Health Authority, Surrey, BC, Canada
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Bennett AH, Seewald M, Hassinger JA, Harris LH, Martin LA, Gold M. “You can’t give this job away”: being a leader in abortion care. Contraception 2016. [DOI: 10.1016/j.contraception.2016.07.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Elustondo P, Martin LA, Karten B. Mitochondrial cholesterol import. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:90-101. [PMID: 27565112 DOI: 10.1016/j.bbalip.2016.08.012] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/15/2016] [Accepted: 08/19/2016] [Indexed: 02/06/2023]
Abstract
All animal subcellular membranes require cholesterol, which influences membrane fluidity and permeability, fission and fusion processes, and membrane protein function. The distribution of cholesterol among subcellular membranes is highly heterogeneous and the cholesterol content of each membrane must be carefully regulated. Compared to other subcellular membranes, mitochondrial membranes are cholesterol-poor, particularly the inner mitochondrial membrane (IMM). As a result, steroidogenesis can be controlled through the delivery of cholesterol to the IMM, where it is converted to pregnenolone. The low basal levels of cholesterol also make mitochondria sensitive to changes in cholesterol content, which can have a relatively large impact on the biophysical and functional characteristics of mitochondrial membranes. Increased mitochondrial cholesterol levels have been observed in diverse pathological conditions including cancer, steatohepatitis, Alzheimer disease and Niemann-Pick Type C1-deficiency, and are associated with increased oxidative stress, impaired oxidative phosphorylation, and changes in the susceptibility to apoptosis, among other alterations in mitochondrial function. Mitochondria are not included in the vesicular trafficking network; therefore, cholesterol transport to mitochondria is mostly achieved through the activity of lipid transfer proteins at membrane contact sites or by cytosolic, diffusible lipid transfer proteins. Here we will give an overview of the main mechanisms involved in mitochondrial cholesterol import, focusing on the steroidogenic acute regulatory protein StAR/STARD1 and other members of the StAR-related lipid transfer (START) domain protein family, and we will discuss how changes in mitochondrial cholesterol levels can arise and affect mitochondrial function. This article is part of a Special Issue entitled: Lipids of Mitochondria edited by Guenther Daum.
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Affiliation(s)
- Pia Elustondo
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Laura A Martin
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Barbara Karten
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada.
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Assefa Y, Conlong DE, Van Den Berg J, Martin LA. Ecological Genetics and Host Range Expansion by Busseola fusca (Lepidoptera: Noctuidae). Environ Entomol 2015; 44:1265-1274. [PMID: 26314073 DOI: 10.1093/ee/nvv079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 04/23/2015] [Indexed: 06/04/2023]
Abstract
The host plant range of pests can have important consequences for its evolution, and plays a critical role in the emergence and spread of a new pest outbreak. This study addresses the ecological genetics of the indigenous African maize stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae), in an attempt to investigate the evolutionary forces that may be involved in the recent host range expansion and establishment of this species in Ethiopian and southern African sugarcane. We used populations from Ethiopia, Zimbabwe, and South Africa to examine whether the host range expansion patterns shared by the Ethiopian and the southern African populations of B. fusca have evolved independently. Base-pair differences in the cytochrome oxidase I (COI) gene were used to characterize haplotype diversity and phylogenetic relationships. There were seven haplotypes among the 30 sequenced individuals collected on four host plant species from 17 localities in the four countries. Of the seven COI haplotypes identified, the two major ones occurred in both sugarcane and maize. Genetic analyses revealed no detectable genetic differentiation between southern African B. fusca populations from maize and sugarcane (FST = 0.019; P = 0.24). However, there was strong evidence of variation in genetic composition between populations of the pest from different geographic regions (FST = 0.948; P < 0.001). The main implication of these findings is that the B. fusca populations in maize in southern Africa are more likely to shift to sugarcane, suggesting that ecological opportunity is an important factor in host plant range expansion by a pest.
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Affiliation(s)
- Y Assefa
- Department of Zoology and Entomology, University of Fort Hare, Faculty of Science and Agriculture, Private Bag X1314, Alice 5700, South Africa.
| | - D E Conlong
- South African Sugarcane Research Institute, Private Bag X02, Mount Edgecombe, 4300, South Africa. School of Life Sciences, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg, Scottsville 3209, South Africa
| | - J Van Den Berg
- Unit of Environmental Sciences and Development, North-West University, Potchefstroom 2520, South Africa
| | - L A Martin
- South African Sugarcane Research Institute, Private Bag X02, Mount Edgecombe, 4300, South Africa
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Ghai M, Singh V, Martin LA, McFarlane SA, van Antwerpen T, Rutherford RS. A rapid and visual loop-mediated isothermal amplification assay to detect Leifsonia xyli subsp. xyli targeting a transposase gene. Lett Appl Microbiol 2014; 59:648-57. [PMID: 25201631 DOI: 10.1111/lam.12327] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 08/12/2014] [Accepted: 09/04/2014] [Indexed: 11/28/2022]
Abstract
UNLABELLED Leifsonia xyli subsp. xyli (Lxx), causal organism of ratoon stunt (RSD), does not produce any reliable internal or external symptoms on sugarcane. Its detection on a large scale is solely based on microscopic and serological methods. These methods require well-equipped laboratories, are time consuming and are not feasible for near-field detection of Lxx. In this study, we developed a loop-mediated isothermal amplification (LAMP) assay for rapid and sensitive detection of Lxx without the use of sophisticated equipment. To the best of our knowledge, this is the first report on the detection of Lxx in 30 min via an isothermal amplification method at 65°C. A transposase gene, ISLxx5, was used to design a set of six primers specifically targeting eight genomic sequences. The xylem sap was used as template, thus circumventing the need to isolate pure genomic DNA. The positive reactions were visually detected through a colour change of hydroxynaphthol blue (HNB) from violet to light blue, thus, eliminating the need for gel electrophoresis. The LAMP method was 10 times more sensitive than serological detection and as sensitive as immunofluorescence microscopy (IFM). The simplicity and sensitivity of the ISLxx5 LAMP assay makes it suitable for near-field diagnosis of RSD. SIGNIFICANCE AND IMPACT OF THE STUDY Detection of Leifsonia xyli subsp. xyli (Lxx) on a large scale is based on serological assays such as evaporative-binding enzyme-linked immunoassay (EB-EIA). These methods are time consuming and require well-equipped laboratories. This study presents the development of a loop-mediated isothermal amplification (LAMP) assay which allows detection of Lxx in 30 min at 65°C, using xylem sap as the template. The assay requires minimal laboratory equipment and could be used at near farm conditions, thus saving time and money required to transfer samples from remote areas to diagnostic laboratories. The LAMP method shows potential as an alternative detection method for RSD.
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Affiliation(s)
- M Ghai
- School of Life Sciences, University of KwaZulu-Natal, Private Bag X54001, Durban, 4000, South Africa
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Martin LA, Assif N, Gilbert M, Wijewarnasuriya D, Seandel M. Enhanced fitness of adult spermatogonial stem cells bearing a paternal age-associated FGFR2 mutation. Stem Cell Reports 2014; 3:219-26. [PMID: 25254335 PMCID: PMC4176532 DOI: 10.1016/j.stemcr.2014.06.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 06/18/2014] [Accepted: 06/20/2014] [Indexed: 12/22/2022] Open
Abstract
Pathogenic de novo mutations increase with fathers’ age and could be amplified through competition between genetically distinct subpopulations of spermatogonial stem cells (SSCs). Here, we tested the fitness of SSCs bearing wild-type human FGFR2 or an Apert syndrome mutant, FGFR2 (S252W), to provide experimental evidence for SSC competition. The S252W allele conferred enhanced FGFR2-mediated signaling, particularly at very low concentrations of ligand, and also subtle changes in gene expression. Mutant SSCs exhibited improved competitiveness in vitro and increased stem cell activity in vivo upon transplantation. The fitness advantage in vitro only occurred in low concentrations of fibroblast growth factor (FGF), was independent of FGF-driven proliferation, and was accompanied by increased response to glial cell line-derived neurotrophic factor (GDNF). Our studies provide experimental evidence of enhanced stem cell fitness in SSCs bearing a paternal age-associated mutation. Our model will be useful for interrogating other candidate mutations in the future to reveal mechanisms of disease risk. FGFR2-mediated signaling regulates SSC self-renewal Age-associated Apert syndrome FGFR2 mutation confers a fitness advantage to SSCs Mutant FGFR2 enables SSCs to withstand limiting GDNF Excessive growth factor exposure impairs SSC self-renewal signals
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Affiliation(s)
- Laura A Martin
- Department of Surgery, Weill Cornell Medical College, New York, NY 10065, USA
| | - Nicholas Assif
- Department of Surgery, Weill Cornell Medical College, New York, NY 10065, USA
| | - Moses Gilbert
- Department of Surgery, Weill Cornell Medical College, New York, NY 10065, USA
| | | | - Marco Seandel
- Department of Surgery, Weill Cornell Medical College, New York, NY 10065, USA.
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Martin LA, Seandel M. Serial enrichment of spermatogonial stem and progenitor cells (SSCs) in culture for derivation of long-term adult mouse SSC lines. J Vis Exp 2013:e50017. [PMID: 23462452 DOI: 10.3791/50017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Spermatogonial stem and progenitor cells (SSCs) of the testis represent a classic example of adult mammalian stem cells and preserve fertility for nearly the lifetime of the animal. While the precise mechanisms that govern self-renewal and differentiation in vivo are challenging to study, various systems have been developed previously to propagate murine SSCs in vitro using a combination of specialized culture media and feeder cells(1-3). Most in vitro forays into the biology of SSCs have derived cell lines from neonates, possibly due to the difficulty in obtaining adult cell lines(4). However, the testis continues to mature up until ~5 weeks of age in most mouse strains. In the early post-natal period, dramatic changes occur in the architecture of the testis and in the biology of both somatic and spermatogenic cells, including alterations in expression levels of numerous stem cell-related genes. Therefore, neonatally-derived SSC lines may not fully recapitulate the biology of adult SSCs that persist after the adult testis has reached a steady state. Several factors have hindered the production of adult SSC lines historically. First, the proportion of functional stem cells may decrease during adulthood, either due to intrinsic or extrinsic factors(5,6). Furthermore, as with other adult stem cells, it has been difficult to enrich SSCs sufficiently from total adult testicular cells without using a combination of immunoselection or other sorting strategies(7). Commonly employed strategies include the use of cryptorchid mice as a source of donor cells due to a higher ratio of stem cells to other cell types(8). Based on the hypothesis that removal of somatic cells from the initial culture disrupts interactions with the stem cell niche that are essential for SSC survival, we previously developed methods to derive adult lines that do not require immunoselection or cryptorchid donors but rather employ serial enrichment of SSCs in culture, referred to hereafter as SESC(2,3). The method described below entails a simple procedure for deriving adult SSC lines by dissociating adult donor seminiferous tubules, followed by plating of cells on feeders comprised of a testicular stromal cell line (JK1)(3). Through serial passaging, strongly adherent, contaminating non-germ cells are depleted from the culture with concomitant enrichment of SSCs. Cultures produced in this manner contain a mixture of spermatogonia at different stages of differentiation, which contain SSCs, based on long-term self renewal capability. The crux of the SESC method is that it enables SSCs to make the difficult transition from self-renewal in vivo to long-term self-renewal in vitro in a radically different microenvironment, produces long-term SSC lines, free of contaminating somatic cells, and thereby enables subsequent experimental manipulation of SSCs.
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Affiliation(s)
- Laura A Martin
- Department of Surgery, Weill Cornell Medical College, NY, USA
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Weigel MT, Banerjee S, Arnedos M, Salter J, A'Hern R, Dowsett M, Martin LA. Enhanced expression of the PDGFR/Abl signaling pathway in aromatase inhibitor-resistant breast cancer. Ann Oncol 2012; 24:126-33. [PMID: 22865780 DOI: 10.1093/annonc/mds240] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND We have found that the platelet-derived growth factor receptor (PDGFR)/Abl signaling pathway is up-regulated as a determinant of the acquisition of resistance to estrogen deprivation in vitro. We aimed to determine its clinical relevance in aromatase inhibitor (AI)-resistant breast cancer. PATIENTS AND METHODS We identified a cohort of 45 patients with estrogen receptor-positive breast cancer who had been treated with an AI, subsequently relapsed and had biopsy material available from both the presentation and post-AI recurrent lesion. PDGFRα, PDGFRβ and Abl expression was assessed in formalin-fixed paraffin-embedded sections. RESULTS Tumor protein expression of PDGFRα (1.39-fold, P=0.0065), PDGFRβ (4.32-fold, P=0.006) and Abl (1.8-fold, P=0.001) was increased at the point of relapse. Tumor and stromal expression of PDGFRα as well as PDGFRβ was significantly correlated in pre-treatment and relapse samples. High post-treatment tumor and stromal PDGFRβ levels were associated with a short time to treatment failure (TTF). Expression of PDGFRα in relapsing tumor specimens was correlated with Abl expression and Ki67 levels. Furthermore, changes in Abl correlated significantly with changes in ER expression. CONCLUSIONS These clinical data support a role for enhanced PDGF/Abl signaling in AI-resistant disease and provide a rationale for targeting the pathway in endocrine-resistant breast cancer.
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Affiliation(s)
- M T Weigel
- The Breakthrough Breast Cancer Research Centre, Institute of Cancer Research, London, UK
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Martin LA, Wilson DT, Reuhl KR, Gallo MA, Klaassen CD. Polychlorinated biphenyl congeners that increase the glucuronidation and biliary excretion of thyroxine are distinct from the congeners that enhance the serum disappearance of thyroxine. Drug Metab Dispos 2011; 40:588-95. [PMID: 22187485 DOI: 10.1124/dmd.111.042796] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Polychlorinated biphenyl (PCB) congeners differentially reduce serum thyroxine (T(4)) in rats, but little is known about their ability to affect biliary excretion of T(4). Thus, male Sprague-Dawley rats were orally administered Aroclor-1254, Aroclor-1242 (32 mg/kg per day), PCB-95, PCB-99, PCB-118 (16 mg/kg per day), PCB-126 (40 μg/kg per day), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (3.9 μg/kg per day), or corn oil for 7 days. Twenty-four hours after the last dose, [(125)I]T(4) was administered intravenously, and blood, bile, and urine samples were collected for quantifying [(125)I]T(4) and in bile [(125)I]T(4) metabolites. Serum T(4) concentrations were reduced by all treatments, but dramatic reductions occurred in response to Aroclor-1254, PCB-99 [phenobarbital (PB)-type congener], and PCB-118 (mixed-type congener). None of the treatments increased urinary excretion of [(125)I]T(4). Aroclor-1254, PCB-118, TCDD, and PCB-126 (TCDD-type congener) increased biliary excretion of T(4)-glucuronide by 850, 756, 710, and 573%, respectively, corresponding to marked induction of hepatic UDP-glucuronosyltransferase (UGT) activity toward T(4). PCB-95 and PCB-99 did not induce UGT activity; therefore, the increased biliary excretion of T(4)-glucuronide was related to the affinity of congeners for the aryl hydrocarbon receptor. The disappearance of [(125)I]T(4) from serum was rapid (within 15-min) and was increased by Aroclor-1254, PCB-99 and PCB-118. Thus, reductions in serum T(4) in response to PCBs did not always correspond with UGT activity toward T(4) or with increased biliary excretion of T(4)-glucuronide. The rapid disappearance of [(125)I]T(4) from the serum of rats treated with PB-like PCBs suggests that increased tissue uptake of T(4) is an additional mechanism by which PCBs may reduce serum T(4).
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Affiliation(s)
- L A Martin
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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Martin LA, Escher T, Goldowitz D, Mittleman G. A relationship between cerebellar Purkinje cells and spatial working memory demonstrated in a lurcher/chimera mouse model system. Genes Brain Behav 2004; 3:158-66. [PMID: 15140011 DOI: 10.1111/j.1601-183x.2004.00067.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
New emphasis has been placed upon cerebellar research because of recent reports demonstrating involvement of the cerebellum in non-motor cognitive behaviors. Included in the growing list of cognitive functions associated with cerebellar activation is working memory. In this study, we explore the potential role of the cerebellum in spatial working memory using a mouse model of Purkinje cell loss. Specifically, we make aggregation chimeras between heterozygous lurcher (Lc/+) mutant embryos and +/+ (wildtype) embryos and tested them in the delayed matching-to-position (DMTP) task. Lc/+ mice lose 100% of their Purkinje cells postnatally due to a cell-intrinsic gain-of-function mutation. Lc/+<->+/+ chimeras therefore have Purkinje cells ranging from 0 to normal numbers. Through histological examination of chimeric mice and observations of motor ability, we showed that ataxia is dependent upon both the number and distribution of Purkinje cells in the cerebellum. In addition, we found that Lc/+ mice, with a complete loss of Purkinje cells, have a generalized deficit in DMTP performance that is probably associated with their motor impairment. Finally, we found that Lc/+<->+/+ chimeric mice, as a group, did not differ from control mice in this task. Rather, surprisingly, analysis of their total Purkinje cells and performance in the DMTP task revealed a significant negative relationship between these two variables. Together, these findings indicate that the cerebellum plays a minor or indirect role in spatial working memory.
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Affiliation(s)
- L A Martin
- Department of Psychiatry and Behavioral Sciences, The M.I.N.D. Institute, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
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15
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Davies G, Martin LA, Sacks N, Dowsett M. Cyclooxygenase-2 (COX-2), aromatase and breast cancer: a possible role for COX-2 inhibitors in breast cancer chemoprevention. Ann Oncol 2002; 13:669-78. [PMID: 12075734 DOI: 10.1093/annonc/mdf125] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Interest in chemoprevention in oncology using suppressants of prostaglandin (PG) synthesis has been stimulated by epidemiological observations that the use of aspirin and other non-steroidal inflammatory drugs (NSAIDs) is associated with reduced incidence of some cancers, including cancer of the breast. The main target of NSAID activity is the cyclooxygenase (COX) enzyme. Two isoforms of COX have been identified: COX-1, the constitutive isoform; and COX-2. the inducible form of the enzyme. COX-2 can undergo rapid induction in response to many factors such as bacterial lipopolysaccharides, growth factors, cytokines and phorbol esters. COX-2 is overexpressed in some malignancies including carcinoma of the breast. It has been suggested that such enhanced expression may lead to increased angiogenesis such that the inhibition of COX-2 might have a general anticancer effect via decreased blood vessel formation. In addition, an association between COX-2, its main product PGE2 and aromatase activity in human breast cancer suggests that such inhibitors might have an additional, specific prophylactic mechanism for this tumour. New COX-2 inhibitors are already licensed for use in the treatment of arthritis and are well tolerated. Their potential role in chemoprevention of mammary carcinogenesis in rats has already been investigated. What remains to be seen is if these findings can be extrapolated to human studies.
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Affiliation(s)
- G Davies
- Academic Department of Biochemistry, Royal Marsden Hospital, London, UK.
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16
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McPherson GL, Martin LA. EPR spectra of an exchange-coupled gadolinium(III)-ruthenium(III) pair: a novel heterogeneous magnetic dimer. J Am Chem Soc 2002. [DOI: 10.1021/ja00335a002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Steady-state gradients of NO within tissues and cells are controlled by rates of NO synthesis, diffusion, and decomposition. Mammalian cells and tissues actively decompose NO. Of several cell lines examined, the human colon CaCo-2 cell produces the most robust NO consumption activity. Cellular NO metabolism is mostly O2-dependent, produces near stoichiometric NO3-, and is inhibited by the heme poisons CN-, CO (K(I) approximately 3 microM), phenylhydrazine, and NO and the flavoenzyme inhibitor diphenylene iodonium. NO consumption is saturable by O2 and NO and shows apparent K(M) values for O2 and NO of 17 and 0.2 microM, respectively. Mitochondrial respiration, O2*-, and H2O2 are neither sufficient nor necessary for O2-dependent NO metabolism by cells. The existence of an efficient mammalian heme and flavin-dependent NO dioxygenase is suggested. NO dioxygenation protects the NO-sensitive aconitases, cytochrome c oxidase, and cellular respiration from inhibition, and may serve a dual function in cells by limiting NO toxicity and by spatially coupling NO and O2 gradients.
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Affiliation(s)
- P R Gardner
- Division of Critical Care Medicine, Children's Hospital Medical Center, Cincinnati, OH, USA.
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18
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Martin LA, Wei DS, Alger BE. Heterogeneous susceptibility of GABA(A) receptor-mediated IPSCs to depolarization-induced suppression of inhibition in rat hippocampus. J Physiol 2001; 532:685-700. [PMID: 11313439 PMCID: PMC2278572 DOI: 10.1111/j.1469-7793.2001.0685e.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Depolarization-induced suppression of inhibition (DSI) in central neurons is mediated by a transient reduction of [gamma]-aminobutyric acid (GABA) release from interneurons. DSI is induced by a retrograde signal emitted from principal cells. We used electrophysiological recordings from CA1 neurons of the rat hippocampal slice to test the hypothesis that only certain classes of interneurons are susceptible to DSI. DSI of action potential-dependent, spontaneous, inhibitory postsynaptic currents (sIPSCs) in hippocampus is facilitated by carbachol (3 microM), which increases the occurrence of large sIPSCs. Besides carbachol, noradrenaline (norepinephrine; 10 microM), or elevated extracellular potassium (8 mM), could abruptly increase the occurrence of large sIPSCs and DSI in many cases. DSI appeared and disappeared concomitantly with the onset and offset of these large sIPSCs. In contrast, application of AP-5 and CNQX often markedly increased baseline sIPSC activity without enhancing DSI. A brief train of extracellular electrical stimulation could trigger the onset of prolonged, repetitive IPSC activity that was susceptible to DSI. The magnitude of DSI of single evoked IPSCs (eIPSCs) in a given pyramidal cell could be altered by changes in stimulus strength, but there was no simple relationship between stimulus strength and DSI. Baclofen (0.5-5 microM) eliminated the increase in sIPSC activity and DSI induced by carbachol. A GABA(B)receptor antagonist, CGP 35348, reversed the effects of baclofen. Carbachol-induced sIPSCs had relatively rapid rise and decay phases. There was no marked distinction between DSI-susceptible and non-susceptible sIPSCs. Nevertheless, two kinetically distinct components of the eIPSC could be distinguished by their decay times. DSI reduced GABA(A),(fast) without affecting GABA(A),(slow). Furosemide (frusemide), which blocks only GABA(A),(fast), reduced the eIPSC and occluded DSI. The data suggest that, with respect to DSI, there are at least three functionally distinct types of IPSCs. Two types (one susceptible to DSI and one not) have relatively rapid kinetics are probably made by perisomatic synapses. A third, slow IPSC, which is insensitive to DSI, may be produced by distal dendritic synapses.
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Affiliation(s)
- L A Martin
- Department of Physiology, University of Maryland School of Medicine, 655 West Baltimore Street, Baltimore, MD 21201, USA
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Abstract
The TTX-sensitive Ca(2+) current [I(Ca(TTX))] observed in cardiac myocytes under Na(+)-free conditions was investigated using patch-clamp and Ca(2+)-imaging methods. Cs(+) and Ca(2+) were found to contribute to I(Ca(TTX)), but TEA(+) and N-methyl-D-glucamine (NMDG(+)) did not. HEK-293 cells transfected with cardiac Na(+) channels exhibited a current that resembled I(Ca(TTX)) in cardiac myocytes with regard to voltage dependence, inactivation kinetics, and ion selectivity, suggesting that the cardiac Na(+) channel itself gives rise to I(Ca(TTX)). Furthermore, repeated activation of I(Ca(TTX)) led to a 60% increase in intracellular Ca(2+) concentration, confirming Ca(2+) entry through this current. Ba(2+) permeation of I(Ca(TTX)), reported by others, did not occur in rat myocytes or in HEK-293 cells expressing cardiac Na(+) channels under our experimental conditions. The report of block of I(Ca(TTX)) in guinea pig heart by mibefradil (10 microM) was supported in transfected HEK-293 cells, but Na(+) current was also blocked (half-block at 0.45 microM). We conclude that I(Ca(TTX)) reflects current through cardiac Na(+) channels in Na(+)-free (or "null") conditions. We suggest that the current be renamed I(Na(null)) to more accurately reflect the molecular identity of the channel and the conditions needed for its activation. The relationship between I(Na(null)) and Ca(2+) flux through slip-mode conductance of cardiac Na(+) channels is discussed in the context of ion channel biophysics and "permeation plasticity."
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Affiliation(s)
- S Guatimosim
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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20
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Abstract
The identification of scrotal disease on a bone scan is reportedly rare. Most previous reports involve abnormally increased accumulation of radioisotope in the scrotal region. This article includes a compilation of three cases of incidental scrotal photopenic defects on bone scintigraphy and a brief review of the literature.
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Affiliation(s)
- L A Martin
- Saint Louis University Hospital, Missouri, USA.
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21
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Gardner PR, Gardner AM, Martin LA, Dou Y, Li T, Olson JS, Zhu H, Riggs AF. Nitric-oxide dioxygenase activity and function of flavohemoglobins. sensitivity to nitric oxide and carbon monoxide inhibition. J Biol Chem 2000; 275:31581-7. [PMID: 10922365 DOI: 10.1074/jbc.m004141200] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Widely distributed flavohemoglobins (flavoHbs) function as NO dioxygenases and confer upon cells a resistance to NO toxicity. FlavoHbs from Saccharomyces cerevisiae, Alcaligenes eutrophus, and Escherichia coli share similar spectra, O(2), NO, and CO binding kinetics, and steady-state NO dioxygenation kinetics. Turnover numbers (V(max)) for S. cerevisiae, A. eutrophus, and E. coli flavoHbs are 112, 290, and 365 NO heme(-1) s(-1), respectively, at 37 degrees C with 200 microm O(2). The K(M) values for NO are low and range from 0.1 to 0.25 microm. V(max)/K(M)(NO) ratios of 900-2900 microm(-1) s(-1) indicate an extremely efficient dioxygenation mechanism. Approximate K(M) values for O(2) range from 60 to 90 microm. NO inhibits the dioxygenases at NO:O(2) ratios of > or =1:100 and makes true K(M)(O(2)) values difficult to determine. High and roughly equal second order rate constants for O(2) and NO association with the reduced flavoHbs (17-50 microm(-1) s(-1)) and small NO dissociation rate constants suggest that NO inhibits the dioxygenase reaction by forming inactive flavoHbNO complexes. Carbon monoxide also binds reduced flavoHbs with high affinity and competitively inhibits NO dioxygenases with respect to O(2) (K(I)(CO) = approximately 1 microm). These results suggest that flavoHbs and related hemoglobins evolved as NO detoxifying components of nitrogen metabolism capable of discriminating O(2) from inhibitory NO and CO.
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Affiliation(s)
- P R Gardner
- Division of Critical Care Medicine, Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA.
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Pandha HS, Martin LA, Rigg AS, Ross P, Dalgleish AG. Oncological applications of gene therapy. Curr Opin Investig Drugs 2000; 1:122-34. [PMID: 11249588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Despite the rapid technological advances that continue to sustain the field of cancer gene therapy, few individual patients have benefited from the revolution so far. The plethora of clinical trials described confirms that each malignancy will have its own ideal strategy based on the associated molecular defects, and there has been rapid progress from this viewpoint. At the same time, there has been a renewed appreciation for the limitations to gene therapy, which include low efficiency of gene transfer, poor specificity of response and methods to accurately evaluate responses, and lack of truly tumor-specific targets at which to aim. As with all new therapies, we are climbing a steep learning curve in terms encountering treatment-related toxicities, as well as profound ethical and regulatory issues.
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Affiliation(s)
- H S Pandha
- Department of Medical Oncology, St George's Hospital Medical School, Cranmer Terrace, London, SW17 ORE, UK.
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Pandha HS, Martin LA, Rigg AS, Ross P, Dalgleish AG. Gene therapy: recent progress in the clinical oncology arena. Curr Opin Mol Ther 2000; 2:362-75. [PMID: 11249766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Despite the rapid technological advances that continue to sustain the field of cancer gene therapy, few individual patients have benefited from the revolution so far. The plethora of clinical trials described confirms that each malignancy will have its own ideal strategy based on the associated molecular defects, and there has been rapid progress from this viewpoint. At the same time, there has been a renewed appreciation for the limitations to gene therapy, which include low efficiency of gene transfer, poor specificity of response and methods to accurately evaluate responses, and lack of truly tumor-specific targets at which to aim. As with all new therapies, we are climbing a steep learning curve in terms encountering treatment-related toxicities, as well as profound ethical and regulatory issues.
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Affiliation(s)
- H S Pandha
- Department of Medical Oncology, St George's Hospital Medical School, Cranmer Terrace, London, SW17 ORE, UK.
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Gardner AM, Martin LA, Gardner PR, Dou Y, Olson JS. Steady-state and transient kinetics of Escherichia coli nitric-oxide dioxygenase (flavohemoglobin). The B10 tyrosine hydroxyl is essential for dioxygen binding and catalysis. J Biol Chem 2000; 275:12581-9. [PMID: 10777548 DOI: 10.1074/jbc.275.17.12581] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli expresses an inducible flavohemoglobin possessing robust NO dioxygenase activity. At 37 degrees C, the enzyme shows a maximal turnover number (V(max)) of 670 s(-1) and K(m) values for NADH, NO, and O(2) equal to 4.8, 0.28, and approximately 100 microM, respectively. Individual reduction, ligand binding, and NO dioxygenation reactions were examined at 20 degrees C, where V(max) is approximately 94 s(-1). Reduction by NADH occurs in two steps. NADH reduces bound FAD with a rate constant of approximately 15 microM(-1) s(-1), and heme iron is reduced by FADH(2) with a rate constant of 150 s(-1). Dioxygen binds tightly to reduced flavohemoglobin, with association and dissociation rate constants equal to 38 microM(-1) s(-1) and 0.44 s(-1), respectively, and the oxygenated flavohemoglobin dioxygenates NO to form nitrate. NO also binds reversibly to reduced flavohemoglobin in competition with O(2), dissociates slowly, and inhibits NO dioxygenase activity at [NO]/[O(2)] ratios of 1:100. Replacement of the heme pocket B10 tyrosine with phenylalanine increases the O(2) dissociation rate constant approximately 80-fold and reduces NO dioxygenase activity approximately 30-fold, demonstrating the importance of the tyrosine hydroxyl for O(2) affinity and NO scavenging activity. At 37 degrees C, V(max)/K(m)(NO) is 2,400 microM(-1) s(-1), demonstrating that the enzyme is extremely efficient at converting toxic NO into nitrate under physiological conditions.
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Affiliation(s)
- A M Gardner
- Division of Critical Care Medicine, Children's Hospital Medical Center, Cincinnati, Ohio 45229, USA.
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Lemaire JB, Schaefer JP, Martin LA, Faris P, Ainslie MD, Hull RD. Effectiveness of the Quick Medical Reference as a diagnostic tool. CMAJ 1999; 161:725-8. [PMID: 10513280 PMCID: PMC1230623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
A number of computer-based systems with diagnostic capabilities have been developed for internal medicine. Quick Medical Reference (QMR) is one such program. The authors describe key features of QMR and report on their study of its effectiveness as a diagnostic tool. They investigated how frequently the correct diagnosis would appear among the 5 highest ranked diagnoses generated by QMR. The charts of 1144 consecutive patients admitted to a teaching unit were retrospectively screened. Eligible cases included those referred for investigation of an undiagnosed illness with an objectively proven final diagnosis (n = 154). Two physicians familiar with, but not experts in, the use of QMR entered clinical information abstracted from the patients' charts into the program. Physician A obtained the correct diagnosis in 62 (40%) of the 154 cases, and physician B was successful in 56 (36%) of the cases. The authors use study cases to illustrate QMR's strengths and weaknesses.
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Affiliation(s)
- J B Lemaire
- Department of Medicine, University of Calgary, Alta.
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Abstract
Depolarization-induced suppression of inhibition is a transient decrease in GABAergic input to a hippocampal pyramidal cell following a brief depolarization of that cell. When recorded under whole-cell voltage clamp, monosynaptic, bicuculline-sensitive, GABA(A)-mediated currents are suppressed for a period lasting up to 1 min in response to a retrograde signal released by the pyramidal cell. The depolarization-induced suppression of inhibition process affects spontaneous, action-potential-dependent inhibitory postsynaptic currents, but suppression of these currents is seldom observed in the absence of carbachol, a cholinergic agonist. Because of the central roles played by cholinergic and GABAergic transmission in the regulation of hippocampal rhythmic activity, it will be important to understand the mechanism by which carbachol facilitates the appearance of depolarization-induced suppression of inhibition. As preliminary steps in the investigation of cholinergic actions on depolarization-induced suppression of inhibition, it is necessary to determine which cholinergic receptors are involved and the degree to which activation of these receptors is required for depolarization-induced suppression of inhibition. Nicotine did not mimic the effects of carbachol, and mecamylamine, a nicotinic receptor antagonist, did not block them. In contrast, the actions of carbachol were abolished by atropine and other muscarinic receptor antagonists. The actions of antagonists with relative selectivities for various subtypes of muscarinic receptors [4-diphenylacetoxy-N-methylpiperidine methiodide, pirenzepine, 11-([2-1-piperidinyl]acetyl)-5,11-dihydro-6H-pyrido[2,3-b][1,4]benzod iaz epine-6-one] suggested that cholinergic facilitation of the occurrence of depolarization-induced suppression of inhibition is likely to be mediated through muscarinic receptors of the M1 or M3 rather than M2 subtype. Despite its potent facilitation of the occurrence of depolarization-induced suppression of inhibition, muscarinic stimulation was not required for expression of depolarization-induced suppression of inhibition. Occasionally, depolarization-induced suppression of inhibition of spontaneous inhibitory postsynaptic currents occurred in the absence of carbachol and could not be blocked by atropine, and hence was not likely to be mediated by endogenous acetylcholine. Also, depolarization-induced suppression of inhibition of monosynaptically evoked inhibitory postsynaptic currents occurred without carbachol perfusion, and this was also insensitive to atropine. Therefore, the mechanism of depolarization-induced suppression of inhibition is not dependent on muscarinic receptor activation. Nevertheless, in vivo, septal cholinergic input to the hippocampus may provide the necessary activation of interneurons to allow depolarization-induced suppression of inhibition to occur.
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Affiliation(s)
- L A Martin
- Department of Physiology, University of Maryland School of Medicine, Baltimore 21201, USA
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Pandha HS, Martin LA, Rigg A, Hurst HC, Stamp GW, Sikora K, Lemoine NR. Genetic prodrug activation therapy for breast cancer: A phase I clinical trial of erbB-2-directed suicide gene expression. J Clin Oncol 1999; 17:2180-9. [PMID: 10561274 DOI: 10.1200/jco.1999.17.7.2180] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE This trial was designed to test the safety and efficacy of a tumor-specific genetic prodrug activation therapy targeted by use of the human erbB-2 gene promoter. The erbB-2 oncogene is overexpressed in approximately 20% of cases of breast cancer and is associated with poor prognosis. PATIENTS AND METHODS Twelve breast cancer patients received transcriptionally targeted gene therapy in a phase I clinical trial using direct intratumoral injection of plasmid construct combined with systemic administration of prodrug. The genetic prodrug activation therapy is specifically targeted to erbB-2-overexpressing breast cancer cells by use of a therapeutic cassette that contains the Escherichia coli cytosine deaminase gene driven by the tumor-specific erbB-2 promoter, thus allowing activation of fluorocytosine to the active cytotoxic fluorouracil only within tumor cells that express the oncogene. RESULTS The approach was shown to be safe and to result in targeted gene expression in up to 90% of cases. Using a number of different assays, we demonstrated that significant levels of expression of the suicide gene were specifically restricted to erbB-2-positive tumor cells, confirming the selectivity of the approach. CONCLUSION The results of this study, the first targeted gene therapy for breast cancer and the first to use the cytosine deaminase system in human subjects, are encouraging for the development of genetic prodrug activation therapies that exploit the transcriptional profile of cancer cells.
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Affiliation(s)
- H S Pandha
- Imperial Cancer Research Fund Molecular Oncology Unit and Departments of Cancer Medicine and Histopathology, Imperial College School of Medicine, Hammersmith Campus, London, United Kingdom
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28
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Abstract
Medical Dosimetrists are commonly called upon to participate in the design of radiation oncology treatment records. The Medical Dosimetrist is uniquely qualified to provide input in the areas of treatment planning, simulation and delivery documentation. An idealized chart can facilitate the planning and delivery of quality patient care and lead the user to document such care. This publication outlines the essential minimum requirements for inclusion in a radiation oncology treatment chart. Conventional treatment record keeping has been by hard-copy documentation. Paperless treatment record models are presently being tested for efficacy. Either approach should seek to: maintain quality of patient care, enhance communication, and provide integrity in documentation.
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Affiliation(s)
- L A Martin
- Radiation Oncology Quality Assurance Center, Tampa, Florida 33612, USA
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Abstract
In this first part of a two-part investigation, the intravenous dose proportionality of dolasetron mesylate, a 5-HT3 receptor antagonist, and the absolute bioavailability of oral dolasetron mesylate were investigated. In an open-label, randomized, four-way crossover design, 24 healthy men between the ages of 19 and 45 years received the following doses: 50, 100, or 200 mg dolasetron mesylate administered by 10-min intravenous infusion or 200 mg dolasetron mesylate solution administered orally. Serial blood and urine samples were collected for 48 h after dosing. Following intravenous administration, dolasetron was rapidly eliminated from plasma, with a mean elimination half-life (t1/2) of less than 10 min. Dolasetron was rarely detected in plasma after oral administration of the 200 mg dose. Hydrodolasetron, the active primary metabolite of dolasetron, appeared rapidly in plasma following both oral and intravenous administration of dolasetron mesylate, with a mean time to maximum concentration (t(max)) of less than 1 h. The mean t1/2 of hydrodolasetron ranged from 6.6-8.8 h. The plasma area under the concentration-time curve (AUC0-infinity)) for both dolasetron and hydrodolasetron increased proportionally with dose over the intravenous dose range of 50-200 mg dolasetron mesylate. Approximately 29-33%) and 22% of the dose was excreted in urine as hydrodolasetron following intravenous and oral administration of dolasetron, respectively. For dolasetron as well as hydrodolasetron, mean systemic clearance (C1), volume of distribution (Vd), and t1/2 were similar at each dolasetron dose. The mean 'apparent' bioavailability of dolasetron calculated using plasma concentrations of hydrodolasetron was 76%. The R(+) enantiomer of hydrodolasetron represented the majority of drug in plasma (> 75%) and urine (> 86%). Dolasetron was well tolerated following both oral and intravenous administration.
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Affiliation(s)
- D C Dimmitt
- North American Pharmacokinetics, Hoechst Marion Roussel, Inc., Kansas City, MO 64134, USA.
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Dimmitt DC, Choo YS, Martin LA, Arumugham T, Hahne WF, Weir SJ. Single- and multiple-dose pharmacokinetics of oral dolasetron and its active metabolites in healthy volunteers: part 2. Biopharm Drug Dispos 1999; 20:41-8. [PMID: 10086836 DOI: 10.1002/(sici)1099-081x(199901)20:1<41::aid-bdd150>3.0.co;2-g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The single- and multiple-dose pharmacokinetics and dose-proportionality of oral dolasetron and its active metabolites over the therapeutic dose range was investigated in 18 healthy men. In an open-label, randomized, complete three-way crossover design, each subject received three separate doses: 50, 100, and 200 mg doses of dolasetron mesylate solution given orally. Each dose was administered on the morning of Days 1 and 3-7 during each of the three treatment periods. Serial blood and urine samples were collected for 48 h after the first and last doses. Blood was analysed for dolasetron and hydrodolasetron concentrations; urine was analysed for dolasetron, the R(+) and S(-)-enantiomers of hydrodolasetron, and the 5'-hydroxy and 6'-hydroxy metabolites of hydrodolasetron. Dolasetron was rarely detected in plasma. Hydrodolasetron was formed rapidly, with a time to maximum concentration (t(max)) of less than 1 h. Steady-state conditions for hydrodolasetron were reached 2-3 days after starting once-daily dosing. Although statistical significance was found for hydrodolasetron AUC(0->infinity) and C(max) between dose groups after both single and multiple doses of dolasetron, the differences were small and unlikely to be of clinical significance. About 17-22% of the dose was excreted in urine as hydrodolasetron, with the majority (> 83%) as the R(+) enantiomer.
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Affiliation(s)
- D C Dimmitt
- North American Pharmacokinetics, Hoechst Marion Roussel, Inc., Kansas City, MO 64134, USA.
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O'Hara RS, Meyer AJ, Burroughs JN, Pullen L, Martin LA, Mertens PP. Development of a mouse model system, coding assignments and identification of the genome segments controlling virulence of African horse sickness virus serotypes 3 and 8. Arch Virol Suppl 1998; 14:259-79. [PMID: 9785512 DOI: 10.1007/978-3-7091-6823-3_23] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Attenuated (att) and wild type (wt) strains of the nine AHSV serotypes were evaluated for virulence in adult Balb C mice. Although most were avirulent in this system, isolates of AHSV 1att, 3wt, 3att, 4wt, 5att, 7att and 8att caused some mortality when administered via an intranasal route. After plaque cloning, only the attenuated vaccine strain of AHSV 7att caused any mortality via an intravenous route. AHSV 3att and AHSV 8wt were virulent (V) and avirulent (AV) (respectively) in the mouse model and were selected as parental strains for production of genome segment reassortants. These progeny virus strains were plaque cloned, then characterised to identify the genome segments that influence virulence of AHSV in the mouse model. Three virulence phenotypes were observed: fully virulent (V); fully avirulent (A); and a novel intermediate virulence (N) not expressed by either parental strain. Genome segment 2 (encoding outer capsid protein VP2) from the avirulent parent appeared to have a controlling influence in production of the A phenotype. Reassortants with the V phenotype all contained segment 2 from the virulent parent, however in each case they also contained genome segments 5 and 10, also from AHSV 3 (V). Genome segments 5 and 10 encode the smaller outer capsid protein VP5 and the non structural proteins NS3/NS3a, respectively. A combination of genome segments 2, 5 and 6 from the avirulent parent and segment 10 from the virulent parent were found in each of the virus strains with the N phenotype. However, comparison of two reassortants (A79 and A790), which differ only in a single segment, showed that replacement of genome segment 10 from the avirulent parent with that from the virulent parent, conferred the N phenotype on A790.
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Affiliation(s)
- R S O'Hara
- Institute for Animal Health, Pirbright Laboratory, Woking, U.K
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Martin LA, Meyer AJ, O'Hara RS, Fu H, Mellor PS, Knowles NJ, Mertens PP. Phylogenetic analysis of African horse sickness virus segment 10: sequence variation, virulence characteristics and cell exit. Arch Virol Suppl 1998; 14:281-93. [PMID: 9785513 DOI: 10.1007/978-3-7091-6823-3_24] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
African horse sickness virus (AHSV) genome segment 10 encodes the non-structural proteins NS3/NS3a, which is involved in release of virus from cells. Full length segment 10 cDNAs were amplified by reverse transcription-polymerase chain reaction, from isolates of AHSV serotypes 2, 3, 4, 5, 7, 8 and 9. These cDNAs were cloned, sequenced and their phylogenetic relationships analysed. High levels of sequence homology were detected in segment 10 from some isolates of different serotypes, confirming that they could be grouped on this basis (serotypes 4, 5, 6 and 9 (group alpha); serotypes 3 and 7 (group beta); serotypes 1, 2, and 8 (group gamma). However, data from bluetongue virus (the prototype orbivirus) indicate that the AHSV serotype is determined exclusively by the structural outer coat proteins VP2 and VP5, encoded by genome segments 2 and 5 respectively. Therefore, as a direct consequence of genome segment reassortment between AHSV strains from different serotypes, the differences observed in segment 10 do not give a reliable indication of virus serotype. Segment 10 of AHSV 3 (virulent) and AHSV 3att (attenuated) were also analysed. These strains, together with AHSV 8, have been used to study of the genetic basis of virulence using reassortment (O'Hara et al., this publication). Virus release studies, using Culicoides cell cultures, indicate that differences in segment 10 of AHSV 3att and 8 can influence the timing of virus release from the infected cell.
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Affiliation(s)
- L A Martin
- Institute for Animal Health, Pirbright Laboratory, Woking, Surrey, U.K
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Gardner PR, Gardner AM, Martin LA, Salzman AL. Nitric oxide dioxygenase: an enzymic function for flavohemoglobin. Proc Natl Acad Sci U S A 1998; 95:10378-83. [PMID: 9724711 PMCID: PMC27902 DOI: 10.1073/pnas.95.18.10378] [Citation(s) in RCA: 469] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/1998] [Accepted: 07/07/1998] [Indexed: 11/18/2022] Open
Abstract
Nitric oxide (NO*) is a toxin, and various life forms appear to have evolved strategies for its detoxification. NO*-resistant mutants of Escherichia coli were isolated that rapidly consumed NO*. An NO*-converting activity was reconstituted in extracts that required NADPH, FAD, and O2, was cyanide-sensitive, and produced NO3-. This nitric oxide dioxygenase (NOD) contained 19 of 20 N-terminal amino acids identical to those of the E. coli flavohemoglobin. Furthermore, NOD activity was produced by the flavohemoglobin gene and was inducible by NO*. Flavohemoglobin/NOD-deficient mutants were also sensitive to growth inhibition by gaseous NO*. The results identify a function for the evolutionarily conserved flavohemoglobins and, moreover, suggest that NO* detoxification may be a more ancient function for the widely distributed hemoglobins, and associated methemoglobin reductases, than dioxygen transport and storage.
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Affiliation(s)
- P R Gardner
- Division of Critical Care Medicine, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
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Martin LA, Mertens PP. Purification and characterization of viral dsRNA genome profiles by crosshybridization. Methods Mol Biol 1998; 86:249-260. [PMID: 9664476 DOI: 10.1385/0-89603-494-1:249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- L A Martin
- ICRF Oncology, Royal Postgraduate Medical School, Surrey, UK
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Affiliation(s)
- L A Martin
- Imperial Cancer Research Fund, Imperial College School of Medicine, Hammersmith Hospital, London, UK
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Ring CJ, Blouin P, Martin LA, Hurst HC, Lemoine NR. Use of transcriptional regulatory elements of the MUC1 and ERBB2 genes to drive tumour-selective expression of a prodrug activating enzyme. Gene Ther 1997; 4:1045-52. [PMID: 9415310 DOI: 10.1038/sj.gt.3300510] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In order to exploit differences in gene expression between normal and malignant cells for genetic prodrug-activation therapy, we have generated recombinant retroviruses containing the herpes simplex virus thymidine kinase coding region cloned downstream of sequences derived from the 5'-flanking regions of the MUC1 and ERBB2 genes. Transduction with retroviruses containing MUC1 promoters resulted in an increase in GCV sensitivity in MUC1 positive cells. A further increase in GCV sensitivity was achieved when MUC1-positive cells were transduced with retroviruses containing chimeric-MUC1/ERBB2 promoters. No significant sensitization to GCV was observed when MUC1-negative cells were transduced with these recombinant retroviruses. These results suggest that one may be able to develop a tumour-selective therapy by utilizing the transcriptional regulatory regions of the MUC1 and ERBB2 genes to drive the expression of suicide genes.
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Affiliation(s)
- C J Ring
- Imperial Cancer Research Fund Molecular Oncology Unit, Imperial College School of Medicine at Hammersmith, Hammersmith Hospital, London, UK
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Stubbs K, Martin LA, Dimmitt DC, Pready N, Hahne WF. Pharmacokinetics of dolasetron after oral and intravenous administration of dolasetron mesylate in healthy volunteers and patients with hepatic dysfunction. J Clin Pharmacol 1997; 37:926-36. [PMID: 9505984 DOI: 10.1002/j.1552-4604.1997.tb04267.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In previous studies, dolasetron was shown to have both renal and hepatic elimination mechanisms. This study was conducted to determine the impact of varying degrees of hepatic dysfunction on the pharmacokinetics and safety of dolasetron and its reduced metabolites. Seventeen adults were studied: six healthy volunteers (group I), seven patients with mild hepatic impairment (Child-Pugh class A; group II), and four patients with moderate to severe hepatic impairment (Child-Pugh class B or C1; group III). Single 150-mg doses of dolasetron mesylate were administered intravenously and orally, with a 7-day washout period separating treatments. After intravenous administration, no differences were observed between healthy volunteers and patients with hepatic impairment in maximum plasma concentration (Cmax), areas under the plasma concentration-time curve (AUC), or elimination half-life (t1/2) of intact dolasetron. No significant differences were found in Cmax, AUC, or apparent clearance (C(lapp)) of hydrodolasetron, the primary metabolite of dolasetron. The mean t1/2 increased from 6.87 hours in group I to 11.69 hours in group III. After oral administration, C(lapp) of hydrodolasetron decreased by 42%, and Cmax increased by 18% in patients with moderate to severe hepatic impairment. There were less changes in patients with mildly hepatic impairment. Total percentage of dose excreted as metabolites was similar for healthy volunteers and patients with hepatic impairment, although urinary metabolite profiles differed slightly. Dolasetron was well tolerated and there were no apparent differences in adverse effects between groups or treatments. Because hepatic impairment did not influence Cl(app) of hydrodolasetron after intravenous administration, and the range of plasma concentrations of hydrodolasetron after oral administration was not different from those observed in healthy volunteers, dosage adjustments are not recommended for patients with hepatic disease and normal renal function.
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Affiliation(s)
- K Stubbs
- Hoechst Marion Roussel, Kansas City, Missouri 64134, USA
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Abstract
The identification of a neuropathic pain syndrome in a cancer patient requires a focused clinical evaluation based on knowledge of common neuropathic pain syndromes. If a tumor is directly involved in the etiology of the pain, oncologic treatment is an initial consideration and may include surgery, radiation, or chemotherapy. There is no single accepted algorithm for the analgesic treatment of neuropathic pain and a systematic approach utilizing therapeutic trials of specific agents at gradually increasing doses is warranted. A trial of opioids, perhaps in combination with an NSAID, is warranted. If the pain is relatively unresponsive to an opioid, a trial with an adjuvant analgesic is reasonable. For example, a tricyclic antidepressant might be selected early for patients with continuous dysesthesia, and early treatment with an anticonvulsant might be used if the pain is predominantly lancinating or paroxysmal. Other adjuvant analgesics can be selected if there is insufficient response to these agents. A trial of sympathetic blockade, pharmacologic, anesthetic or surgical, should be considered in patients with evidence of causalgia or reflex sympathetic dystrophy. Physiatric modalities such as massage, heat, or cold; counterstimulation or transcutaneous electrical nerve stimulation (TENS), and orthopedic interventions, such as braces and splints may be useful. Epidural injections or neurostimulation of the spinal cord or brain can be considered in selected cases where appropriate expertise is available. Treatment of neuropathic pain remains a challenge for both clinicians and patients. The complexity of syndromes and underlying etiologic mechanisms warrants further clinical trials to determine the best treatment modalities for individual pain syndromes.
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Affiliation(s)
- L A Martin
- Department of Oncology, University of Calgary, Alberta, Canada
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Morishita W, Kirov SA, Pitler TA, Martin LA, Lenz RA, Alger BE. N-ethylmaleimide blocks depolarization-induced suppression of inhibition and enhances GABA release in the rat hippocampal slice in vitro. J Neurosci 1997; 17:941-50. [PMID: 8994049 PMCID: PMC6573169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Regulation of synaptic, GABAA receptor-mediated inhibition is a process of critical importance to normal brain function. Recently, we have described a phenomenon in hippocampus of a transient, yet marked, decrease in spontaneous, GABAA receptor-mediated IPSCs after depolarization activated Ca2+ influx into a pyramidal cell. This process, depolarization-induced suppression of inhibition (DSI), is absent in hippocampal cells that previously had been exposed to pertussis toxin in vivo, implicating a G-protein in the DSI process. To circumvent the problem that a single cell cannot be studied before and after G-protein block using the pertussis toxin pretreatment method, we have used the sulfhydryl alkylating agent N-ethylmaleimide (NEM), which blocks pertussis toxin-sensitive G-proteins, to determine whether acute inhibition of G-proteins can eliminate DSI of spontaneous IPSCs (sIPSCs). In whole-cell recordings from CA1 pyramidal cells that were first determined to express DSI, we have found that NEM does block DSI of sIPSCs. We also report that DSI of monosynaptic, evoked IPSCs is blocked by NEM, suggesting that a similar mechanism underlies both forms of DSI. It was of interest that DSI was abolished at a time when NEM had increased, not decreased, GABA transmission. Indeed, NEM greatly increased quantal GABA release by a Ca(2+)-independent mechanism, an observation with potentially important implications for understanding synaptic GABA release.
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Affiliation(s)
- W Morishita
- Department of Physiology, University of Maryland School of Medicine, Baltimore 21201, USA
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Alger BE, Pitler TA, Wagner JJ, Martin LA, Morishita W, Kirov SA, Lenz RA. Retrograde signalling in depolarization-induced suppression of inhibition in rat hippocampal CA1 cells. J Physiol 1996; 496 ( Pt 1):197-209. [PMID: 8910208 PMCID: PMC1160836 DOI: 10.1113/jphysiol.1996.sp021677] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
1. We have investigated the phenomenon of 'depolarization-induced suppression of inhibition' (DSI) using whole-cell voltage-clamp techniques in Ca1 pyramidal cells of rat hippocampal slices. DSI was induced by eliciting voltage-dependent calcium (Ca2+) currents with 1 s voltage steps of +60 to +90 mV from the holding potential. DSI was apparent as a reduction in synaptic GABAA responses for a period of about 1 min following the voltage step. 2. TTX-sensitive spontaneous IPSCs (sIPSCs) were susceptible to DSI, while TTX-resistant miniature inhibitory postsynaptic current (mIPSCs) were not. Miniature IPSCs are ordinarily infrequent and independent of external Ca2+ in the CA1 region. To increase the frequency of mIPSCs and to induce a population of Ca(2+)-sensitive mIPSCs, we increased the bath K+ concentration to 15 mM. The increased mIPSCs were also insensitive to DSI, however. 3. T whole-cell pipette-filling solution contained 5 mM 2(triethylamino-N-(2,6-dimethyl-phenyl)acetamide (QX-314) to block voltage-dependent Na+ currents and caesium to block K+ currents. Nevertheless, bath application of 50 microM 4-aminopyridine (4-AP) or 250 nM veratridine both clearly reduced DSI, evidently by acting at presynaptic sites. 4. The amplitudes of monosynaptically evoked IPSCs (elicited in the presence of 10 microM 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and 50 microM 2-amino-5-phosphonovaleric acid (APV)) were dramatically reduced during the DSI period. Weak stimulation produced small IPSCs and occasional 'failures' of transmission during the control period. The percentage of failures increased markedly during the DSI period. Moderate-intensity stimulation produced larger IPSCs that were often composed of distinguishable multiquantal components. All-or-none failures of multiquantal IPSC components also occurred during DSI. 5. The degree of paired-pulse IPSC depression did not change during DSI, whereas it was decreased, as expected, by baclofen. 6. We conclude that the data represent novel evidence that DSI is mediated by a retrograde signalling process possibly involving presynaptic axonal conduction block.
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Affiliation(s)
- B E Alger
- Department of Physiology, University of Maryland School of Medicine, Baltimore 21201, USA
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Abstract
Cell death can be induced by genetic intervention in a variety of ways. We review genetic prodrug activation therapies using both mammalian and non-mammalian enzyme systems as well as the expression of toxin genes and apoptotic triggers. Targeting of the genetic intervention using both transductional restriction and transcriptional control elements is examined in both in vitro and in vivo systems, and the present state of clinical trials is reviewed.
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Affiliation(s)
- L A Martin
- ICRF Oncology Unit, Royal Postgraduate Medical School, Hammersmith Hospital, London, UK
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Goldrick MM, Kimball GR, Liu Q, Martin LA, Sommer SS, Tseng JY. NIRCA: a rapid robust method for screening for unknown point mutations. Biotechniques 1996; 21:106-12. [PMID: 8816244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We describe a method for screening for dispersed point mutations, based on the observation that RNase frequently cleaves both strands of base pair mismatches in duplex RNA targets. The mismatched substrates are generated by in vitro transcription of wild-type and mutant templates amplified by the PCR or reverse transcription (RT)-PCR; bacteriophage promoters are incorporated into the PCR primers to permit both strands of the products to be transcribed into RNA. Complementary wild-type and mutant transcripts are hybridized and treated with RNase, and the cleavage products are separated on agarose gels and detected by visualization of the ethidium-stained sample under UV light. The method is thus non-isotopic, and since the cleavage products remain double-stranded during analysis, the labor-intensive RNase inactivation steps required in the original procedure can be eliminated. Also, nonspecific background cleavage is reduced so that longer target regions (1 kb) can be screened in a single step. The Non-Isotopic RNase Cleavage Assay (NIRCA) achieved a detection rate of 88%-90% in blind studies in a Factor IX model system, and it was also used to detect unknown p53 mutations in breast tumor samples. NIRCA provides a rapid method for sensitive, non-isotopic, high-throughput genetic screening.
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Newman RA, Fan D, Munson HR, Martin LA, Ahmed NK. MDL 201,307: a novel benzothiazepine modulator of multiple drug resistance. J Exp Ther Oncol 1996; 1:109-18. [PMID: 9414394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A series of novel benzothiazepine derivatives were evaluated for their relative potential to reverse multiple drug resistance (MDR) phenotype in vitro as well as for their relative cardiovascular activity and neurotoxicity. Compounds were evaluated for antiMDR activity using Chinese hamster ovary cells with derived resistance to either vincristine or doxorubicin, or a human lymphoblastic leukemia line with resistance to vinblastine. Lead compounds with good antiMDR activity were further evaluated for their relative potential to exhibit cardiovascular and neurological pharmacodynamic activity. A single compound, MDL 201,307 with good antiMDR activity and low cardiovascular and neurologic activity was chosen for further study. In contrast to (R)-verapamil, MDL 201,307 showed only a weak potential to block calcium channels. Using a series of related murine fibrosarcoma cell lines (UV-2237M) with varying levels of resistance to doxorubicin, it was shown that MDL 201,307 augmented inhibition of growth due to doxorubicin. The antiMDR compound was also effective in enhancing the cytotoxicity of actinomycin-D and vinblastine although it was ineffective in increasing cytotoxicity of the nonMDR compound, 5FU. MDL 201,307 increased uptake and decreased efflux of doxorubicin suggesting that MDL 201,307 blocks the GP170-mediated efflux pump mechanism. MDL 201,307 represents a novel antiMDR agent with diminished potential for cardiovascular activity and neurologic interactions which presently limit many of the currently available first and second generations of antiMDR compounds.
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Affiliation(s)
- R A Newman
- Department of Clinical Investigation, University of Texas M.D. Anderson Cancer Center, Houston 77030, USA
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Hesketh PJ, Gandara DR, Hesketh AM, Facada A, Perez EA, Webber LM, Martin LA, Cramer MB, Hahne WF. Dose-ranging evaluation of the antiemetic efficacy of intravenous dolasetron in patients receiving chemotherapy with doxorubicin or cyclophosphamide. Support Care Cancer 1996; 4:141-6. [PMID: 8673351 DOI: 10.1007/bf01845763] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Selective 5-HT3 antagonists have proven to be safe and effective for the prevention of chemotherapy-induced nausea and vomiting. Dolasetron is a new highly selective addition to this class of antiemetics that has been shown to have significant antiemetic activity in patients receiving cisplatin-containing regimens. This pilot study was designed to evaluate the antiemetic efficacy of dolasetron in cancer patients receiving doxorubicin and/or cyclophosphamide. This study used an open-label, non-randomized design to evaluate the efficacy and safety of intravenous dolasetron in the prevention of emesis in patients receiving doxorubicin (25-75 mg/m2) and/or cyclophosphamide (400-1200 mg/m2). Sixty-nine patients received a single, intravenous dose of dolasetron over 15-20 min beginning 30 min prior to the start of chemotherapy. Dose levels of dolasetron studied were: 0.3, 0.6, 1.2, 1.8 and 2.4 mg/kg. Patients were monitored for emesis, nausea and adverse events for 24h after the start of chemotherapy. Overall, 61% of patients experienced complete control of emesis. No significant trend towards increased antiemetic efficacy (P = 0.076) or nausea control with increasing dolasetron dose was noted, although the power to detect significant differences was limited by the small number of patients on the 0.3-mg/kg and 2.4-mg/kg dose levels. Age, gender, and type of chemotherapy were significant predictors of complete antiemetic control. Adverse events were generally mild and included headache, chills, lightheadedness, fever, diarrhea, dizziness, and asymptomatic prolongation of ECG intervals. Intravenous dolasetron is safe and effective in the prevention of emesis induced by doxorubicin and/or cyclophosphamide.
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Affiliation(s)
- P J Hesketh
- Section of Medical Oncology, St. Elizabeth's Medical Center, Boston, MA 02135, USA
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Martin LA, Connor FL. Your PC can enhance staff and patient education. Pediatr Nurs 1996; 22:76-9. [PMID: 8700630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Obtaining education materials for both staff and patients can be expensive. Tracking staff certification requirements and available references for individual units can be time consuming and awkward. Using a regular home personal computer and inexpensive software applications, the staff nurse, educator, and manager can produce quality education products, maintain records, and graph representation of administrative trends.
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Martin LA, Krall JM, Curran WJ, Leibel SA, Cox JD. Influence of a sampling review process for radiation oncology quality assurance in cooperative group clinical trials--results of the Radiation Therapy Oncology Group (RTOG) analysis. Radiother Oncol 1995; 36:9-14. [PMID: 8525028 DOI: 10.1016/0167-8140(95)01533-m] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The Radiation Therapy Oncology Group (RTOG) designed a random sampling process and observed its influence upon radiotherapy review mechanisms in cooperative group clinical trials. The method of sampling cases for review was modeled from sampling techniques commonly used in pharmaceutical quality assurance programs, and applied to the initial (on-study) review of protocol cases. 'In control' (IC) status is defined for a given facility as the ability to meet minimum compliance standards. Upon achieving IC status, activation of the sampling process was linked to the rate of continued patient accrual for each participating institution in a given protocol. The sampling design specified that > or = 30% cases not in compliance would be detected with 80% power. A total of 458 cases was analyzed for initial review findings in four RTOG Phase III protocols. Initial review findings were compared with retrospective (final) review results. Of the 458 cases analyzed, 370 underwent initial review at on-study, while 88 did not require review as they were enrolled from institutions that had demonstrated protocol compliance. In the group that had both initial and final review, 345/370 (93%) were found to have followed the protocol or had a minor variation. Of the exempted cases, 79/88 (90%) were found to be per protocol or a minor variant. The sampling process proved itself to be cost-effective and resulted in a noticeable reduction in the workload, thus providing an improved approach to resource allocation for the group. Continued evaluation of the sampling mechanism is appropriate as study designs and participants vary over time, and as more data become available to study.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- L A Martin
- Radiation Therapy Oncology Group, Philadelphia, PA 19107, USA
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Bergeron C, Le Moine P, Le Berre C, Bansard JY, Martin LA, Goasguen J, Quemener V, Moulinoux JP, Le Gall E. Erythrocyte polyamine levels: an indication of successful engraftment of bone marrow in children. Bone Marrow Transplant 1995; 16:27-30. [PMID: 7581126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We studied the evolution of erythrocyte polyamine levels after 17 autologous bone marrow transplants (BMT) in 16 children with malignant diseases. We found that the time to the end of aplasia (0.5 x 10(9) granulocytes per liter) could be divided into 2 distinct periods. The first is characterized by low erythrocyte spermidine (Spd) and spermine (Spm) levels; the second is characterized by normal levels of polyamines. Spd and Spm levels were correlated (r = 0.74) during the second period, but not during the first period or in the control group. Furthermore, the time when Spd concentration was > or = 7 nmol/8 x 10(9) erythrocytes (19 +/- 7) was correlated (r = 0.64) with the advent of end of aplasia (30 +/- 10). We found no correlation between the numbers of CFU-GM and duration of aplasia levels or the duration of period A. The establishment of normal erythrocyte spermidine levels is the earliest index of successful marrow engraftment.
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Affiliation(s)
- C Bergeron
- Groupe de Recherche en Thérapeutique Anticancéreuse, URA CNRS 1529, Centre Hospitalo-Universitaire de Rennes, France
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Abstract
Persistent foot-and-mouth disease (FMD) infection of cattle was established by exposure to infected pigs. Oesophageal-pharyngeal fluid samples collected ante-mortem and tissue samples obtained post-mortem were tested for virus by conventional means and for viral RNA by the polymerase chain reaction (PCR). The results showed that the PCR was superior for detecting the carrier state in tissue samples. A high neutralising activity in tissues probably influenced the yields of virus obtained by infectivity assay.
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Affiliation(s)
- A Donn
- AFRC Institute for Animal Health, Pirbright Laboratory, Woking, Surrey, UK
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Conti LH, Costello DG, Martin LA, White MF, Abreu ME. Mouse strain differences in the behavioral effects of corticotropin-releasing factor (CRF) and the CRF antagonist alpha-helical CRF9-41. Pharmacol Biochem Behav 1994; 48:497-503. [PMID: 8090821 DOI: 10.1016/0091-3057(94)90559-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effect of the corticotropin-releasing factor (CRF) antagonist alpha-helical CRF9-41 (alpha H CRF9-41; 25 and 50 micrograms) was examined in four strains of mice (BALB/C, NIH Swiss, CF-1, and CD) in the elevated plus-maze anxiolytic test and found to significantly increase percent open arm activity in only the BALB/C mice. A marginal anxiolytic response was obtained in NIH Swiss, while no effect of the antagonist was noted in CF-1 or CD mice in this test. Diazepam (1-4 mg/kg IP) significantly increased percent open arm activity in all four mouse strains. Thus, all strains were sensitive to the effects of a known anxiolytic in this test. The locomotor-suppressing effect of the agonist CRF was assessed in the four strains of mice. While CRF suppressed locomotor activity in each of the strains, the peptide was more efficacious and more potent in the BALB/C strain than in any of the other three strains. The behavioral differences in responsiveness to CRF and the antagonist alpha H CRF9-41 could not be explained on the basis of differential binding of CRF to forebrain membranes in the four mouse strains. These data suggest that the BALB/C mouse is more sensitive to the behavioral effects of CRF and its antagonist than other strains and may be a useful strain for examining the effects of CRF and/or stress.
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Affiliation(s)
- L H Conti
- Nova Pharmaceutical Corporation, Baltimore, MD 21224
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Martin LA, McNemar A, O'Brien EL. Menkes kinky hair disease. MCN Am J Matern Child Nurs 1994; 19:162-4. [PMID: 8028455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- L A Martin
- National Naval Medical Center, Bethesda, Maryland
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