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Christensen JD, Kohlenberg JD, Kudva YC. 46-Year-Old Woman With Type 2 Diabetes Mellitus and Obesity. Mayo Clin Proc 2023; 98:181-186. [PMID: 36603946 DOI: 10.1016/j.mayocp.2022.05.024] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 04/21/2022] [Accepted: 05/03/2022] [Indexed: 01/04/2023]
Affiliation(s)
- John D Christensen
- Resident in Internal Medicine, Mayo Clinic School of Graduate Medical Education, Rochester, MN
| | - Jacob D Kohlenberg
- Fellow in Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic School of Graduate Medical Education, Rochester, MN
| | - Yogish C Kudva
- Advisor to resident and fellow and Consultant in Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN.
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Stark E, Christensen JD, Schmalz NA, Uijtdehaage S. Evaluation of a Curricular Addition to Assist Medical Students in Specialty Selection. J Med Educ Curric Dev 2018; 5:2382120518788867. [PMID: 30083614 PMCID: PMC6066807 DOI: 10.1177/2382120518788867] [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] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 06/21/2018] [Indexed: 05/18/2023]
Abstract
Early hands-on experience with surgical procedures may help medical students make better-informed choices if considering a surgical specialty. Here, we evaluate a curricular addition in surgical anatomy, formally exposing second-year students to different surgical subspecialties. Students met with surgeons for 7 weeks (one afternoon per week) and practiced surgical procedures on human cadavers with supervision. About a quarter of the participants reported a change in their top choice of specialty upon completing the course, and about half of the students reported changes in their second and third choices. At the time of graduation, 85% of those surveyed reported participation in the course impacted their final choice of specialty. These results demonstrate such a course helped medical students select a specialty during early training.
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Affiliation(s)
- Elena Stark
- Department of Pathology and Laboratory
Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
- Elena Stark, Department of Pathology, School
of Medicine at UCLA, 10833 Le Conte Ave. CHS 50-060, Los Angeles CA 90095, USA.
| | - John D Christensen
- Department of Pathology and Laboratory
Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA
| | - Naomi A Schmalz
- Department of Anatomy and Cell Biology,
School of Medicine, Indiana University, Indianapolis, IN, USA
| | - Sebastian Uijtdehaage
- Department of Medicine, Uniformed
Services University of the Health Sciences, Bethesda, MD, USA
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Christensen JD, Lungu AO, Cochran E, Collins MT, Gafni RI, Reynolds JC, Rother KI, Gorden P, Brown RJ. Bone mineral content in patients with congenital generalized lipodystrophy is unaffected by metreleptin replacement therapy. J Clin Endocrinol Metab 2014; 99:E1493-500. [PMID: 25070319 PMCID: PMC4121033 DOI: 10.1210/jc.2014-1353] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Leptin alters bone and mineral metabolism in rodents, but this has not been verified in humans. PATIENTS with congenital generalized lipodystrophy (CGL) have low leptin due to deficient adipose mass and serve as models of leptin deficiency and replacement. OBJECTIVE To study the effects of recombinant human methionyl leptin (metreleptin) on bone mineral content (BMC) and mineral metabolism. DESIGN AND SETTING An open-label nonrandomized study at the National Institutes of Health. PATIENTS Thirty-one patients with CGL (ages 4.3 to 46.7 y). INTERVENTION Metreleptin (0.06 to 0.24 mg/kg/d) for 6 months to 11 years. OUTCOME MEASURES BMC was assessed by dual-energy x-ray absorptiometry. SD scores (SDS) for BMC were calculated based on height, race, sex, and age using population normative data. Calcium, phosphorus, PTH, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were measured at baseline and follow-up. RESULTS At baseline, patients demonstrated significantly increased total body less head BMC (mean SDS, 1.8 ± 0.7), height (mean SDS, 1.3 ± 1.3), and lean mass index, defined as lean body mass per height squared (mean SDS, 1.5 ± 0.83), vs population normative data. No change in total body less head BMC was observed after metreleptin. Lean mass index decreased with metreleptin. Serum calcium decreased with metreleptin, but remained within normal limits. No changes were seen in phosphorus, PTH, or vitamin D. CONCLUSIONS In contrast to rodent models, CGL patients have increased BMC in the leptin-deficient state, which does not change with leptin replacement. The high BMC in these patients is partially explained by high lean mass and tall stature.
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Affiliation(s)
- John D Christensen
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases (J.D.C., E.C., P.G., K.I.R., R.J.B.), National Institute of Dental and Craniofacial Research (M.T.C., R.I.G.), Nuclear Medicine Department, Clinical Center (J.C.R.), National Institutes of Health, Bethesda, Maryland 20892; and Joslin Diabetes Center (A.O.L.), Brookline, Massachusetts 02215
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Maruya KA, Dodder NG, Schaffner RA, Weisberg SB, Gregorio D, Klosterhaus S, Alvarez DA, Furlong ET, Kimbrough KL, Lauenstein GG, Christensen JD. Refocusing Mussel Watch on contaminants of emerging concern (CECs): the California pilot study (2009-10). Mar Pollut Bull 2014; 81:334-339. [PMID: 23886247 DOI: 10.1016/j.marpolbul.2013.04.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [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: 12/02/2012] [Revised: 04/11/2013] [Accepted: 04/23/2013] [Indexed: 06/02/2023]
Abstract
To expand the utility of the Mussel Watch Program, local, regional and state agencies in California partnered with NOAA to design a pilot study that targeted contaminants of emerging concern (CECs). Native mussels (Mytilus spp.) from 68 stations, stratified by land use and discharge scenario, were collected in 2009-10 and analyzed for 167 individual pharmaceuticals, industrial and commercial chemicals and current use pesticides. Passive sampling devices (PSDs) and caged Mytilus were co-deployed to expand the list of CECs, and to assess the ability of PSDs to mimic bioaccumulation by Mytilus. A performance-based quality assurance/quality control (QA/QC) approach was developed to ensure a high degree of data quality, consistency and comparability. Data management and analysis were streamlined and standardized using automated software tools. This pioneering study will help shape future monitoring efforts in California's coastal ecosystems, while serving as a model for monitoring CECs within the region and across the nation.
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Affiliation(s)
- Keith A Maruya
- Southern California Coastal Water Research Project Authority, 3535 Harbor Boulevard Suite 110, Costa Mesa, CA 92626, USA.
| | - Nathan G Dodder
- Southern California Coastal Water Research Project Authority, 3535 Harbor Boulevard Suite 110, Costa Mesa, CA 92626, USA
| | - Rebecca A Schaffner
- Southern California Coastal Water Research Project Authority, 3535 Harbor Boulevard Suite 110, Costa Mesa, CA 92626, USA
| | - Stephen B Weisberg
- Southern California Coastal Water Research Project Authority, 3535 Harbor Boulevard Suite 110, Costa Mesa, CA 92626, USA
| | - Dominic Gregorio
- California State Water Resources Control Board, 1001 I Street, Sacramento, CA 95814, USA
| | - Susan Klosterhaus
- San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804, USA
| | - David A Alvarez
- U.S. Geological Survey, 4200 New Haven Road, Columbia, MO 65201, USA
| | - Edward T Furlong
- U.S. Geological Survey, Denver Federal Center, Denver, CO 80225, USA
| | - Kimani L Kimbrough
- National Oceanic and Atmospheric Administration, 1305 East West Highway, Silver Spring, MD 20910, USA
| | - Gunnar G Lauenstein
- National Oceanic and Atmospheric Administration, 1305 East West Highway, Silver Spring, MD 20910, USA.
| | - John D Christensen
- National Oceanic and Atmospheric Administration, 1305 East West Highway, Silver Spring, MD 20910, USA
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Fingas CD, Mertens JC, Razumilava N, Sydor S, Bronk SF, Christensen JD, Rizvi SH, Canbay A, Treckmann JW, Paul A, Sirica AE, Gores GJ. Polo-like kinase 2 is a mediator of hedgehog survival signaling in cholangiocarcinoma. Hepatology 2013; 58:1362-74. [PMID: 23703673 PMCID: PMC3811036 DOI: 10.1002/hep.26484] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Accepted: 04/16/2013] [Indexed: 12/11/2022]
Abstract
UNLABELLED Cholangiocarcinoma (CCA) cells paradoxically express the death ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and thus rely on potent survival signals to circumvent cell death by TRAIL. Hedgehog (Hh) signaling is an important survival pathway in CCA. Herein, we further examine the mechanisms whereby Hh signaling mediates apoptosis resistance in CCA, revealing a pivotal role for the cell division regulating serine/threonine kinase polo-like kinase 2 (PLK2). We employed 50 human CCA samples (25 intrahepatic and 25 extrahepatic CCA) as well as human KMCH-1, Mz-CHA-1, and HUCCT-1 CCA cells for these studies. In vivo experiments were conducted using a syngeneic rat orthotopic CCA model. In human samples, polo-like kinase (PLK)1/2/3-immunoreactive cancer cells were present in the preponderance of intra- and extrahepatic CCA specimens. Inhibition of Hh signaling by cyclopamine reduced PLK2, but not PLK1 or PLK3, messenger RNA and protein expression in vehicle-treated and sonic Hh-treated CCA cells, confirming our previous microarray study. PLK2 regulation by Hh signaling appears to be direct, because the Hh transcription factors, glioma-associated oncogene 1 and 2, bind to the PLK2 promotor. Moreover, inhibition of PLK2 by the PLK inhibitor, BI 6727 (volasertib), or PLK2 knockdown was proapoptotic in CCA cells. BI 6727 administration or PLK2 knockdown decreased cellular protein levels of antiapoptotic myeloid cell leukemia 1 (Mcl-1), an effect reversed by the proteasome inhibitor, MG-132. Finally, BI 6727 administration reduced Mcl-1 protein expression in CCA cells, resulting in CCA cell apoptosis and tumor suppression in vivo. CONCLUSION PLK2 appears to be an important mediator of Hh survival signaling. These results suggest PLK inhibitors to be of therapeutic value for treatment of human CCA.
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Affiliation(s)
- Christian D. Fingas
- Department of General, Visceral, and Transplantation Surgery, University Hospital Essen, Essen, Germany
| | - Joachim C. Mertens
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN,Division of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Nataliya Razumilava
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN
| | - Svenja Sydor
- Department of Gastroenterology and Hepatology, University Hospital Essen, Essen, Germany
| | - Steven F. Bronk
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN
| | - John D. Christensen
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN
| | - Sumera H. Rizvi
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN
| | - Ali Canbay
- Department of Gastroenterology and Hepatology, University Hospital Essen, Essen, Germany
| | - Jürgen W. Treckmann
- Department of General, Visceral, and Transplantation Surgery, University Hospital Essen, Essen, Germany
| | - Andreas Paul
- Department of General, Visceral, and Transplantation Surgery, University Hospital Essen, Essen, Germany
| | - Alphonse E. Sirica
- Division of Cellular and Molecular Pathogenesis, Department of Pathology, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Gregory J. Gores
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN
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Mertens JC, Fingas CD, Christensen JD, Smoot RL, Bronk SF, Werneburg NW, Gustafson MP, Dietz AB, Roberts LR, Sirica AE, Gores GJ. Therapeutic effects of deleting cancer-associated fibroblasts in cholangiocarcinoma. Cancer Res 2012; 73:897-907. [PMID: 23221385 DOI: 10.1158/0008-5472.can-12-2130] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Cancer-associated fibroblasts (CAF) are abundant in the stroma of desmoplastic cancers where they promote tumor progression. CAFs are "activated" and as such may be uniquely susceptible to apoptosis. Using cholangiocarcinoma as a desmoplastic tumor model, we investigated the sensitivity of liver CAFs to the cytotoxic drug navitoclax, a BH3 mimetic. Navitoclax induced apoptosis in CAF and in myofibroblastic human hepatic stellate cells but lacked similar effects in quiescent fibroblasts or cholangiocarcinoma cells. Unlike cholangiocarcinoma cells, neither CAF nor quiescent fibroblasts expressed Mcl-1, a known resistance factor for navitoclax cytotoxicity. Explaining this paradox, we found that mitochondria isolated from CAFs or cells treated with navitoclax both released the apoptogenic factors Smac and cytochrome c, suggesting that they are primed for cell death. Such death priming in CAFs appeared to be due, in part, to upregulation of the proapoptotic protein Bax. Short hairpin RNA-mediated attenuation of Bax repressed navitoclax-mediated mitochondrial dysfunction, release of apoptogenic factors, and apoptotic cell death. In a syngeneic rat model of cholangiocarcinoma, navitoclax treatment triggered CAF apoptosis, diminishing expression of the desmoplastic extracellular matrix protein tenascin C, suppressing tumor outgrowth, and improving host survival. Together, our findings argue that navitoclax may be useful for destroying CAFs in the tumor microenvironment as a general strategy to attack solid tumors.
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Affiliation(s)
- Joachim C Mertens
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota 55905, USA
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Pait AS, Whitall DR, Dieppa A, Newton SE, Brune L, Caldow C, Mason AL, Apeti DA, Christensen JD. Characterization of organic chemical contaminants in sediments from Jobos Bay, Puerto Rico. Environ Monit Assess 2012; 184:5065-5075. [PMID: 21956337 DOI: 10.1007/s10661-011-2322-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 08/29/2011] [Indexed: 05/31/2023]
Abstract
Jobos Bay, located on the southeastern coast of Puerto Rico, contains a variety of habitats including mangroves, seagrass meadows, and coral reefs. The watershed surrounding the bay includes a number of towns, agricultural areas, and the Jobos Bay National Estuarine Research Reserve (NERR). Jobos Bay and the surrounding watershed are part of a Conservation Effects Assessment Project (CEAP), involving the Jobos Bay NERR, the US Department of Agriculture, and the National Oceanic and Atmospheric Administration (NOAA) to assess the benefits of agricultural best management practices (BMPs) on the terrestrial and marine environments. As part of the Jobos Bay CEAP, NOAA collected sediment samples in May 2008 to characterize over 130 organic chemical contaminants. This paper presents the results of the organic contaminant analysis. The organic contaminants detected in the sediments included polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and the pesticide DDT. PAHs at one site in the inner bay near a boat yard were significantly elevated; however, all organic contaminant classes measured were below NOAA sediment quality guidelines that would have indicated that impacts were likely. The results of this work provide an important baseline assessment of the marine environment that will assist in understanding the benefits of implementing BMPs on water quality in Jobos Bay.
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Affiliation(s)
- Anthony S Pait
- NOAA/NOS/NCCOS Center for Coastal Monitoring and Assessment, 1305 East/West Highway, Silver Spring, MD 20910, USA.
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Apeti DA, Lauenstein GG, Christensen JD, Johnson EW, Mason A. Assessment of coastal storm impacts on contaminant body burdens of oysters collected from the Gulf of Mexico. Environ Monit Assess 2011; 181:399-418. [PMID: 21193956 DOI: 10.1007/s10661-010-1837-1] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Accepted: 12/05/2010] [Indexed: 05/30/2023]
Abstract
This study evaluated changes in oyster tissue contaminant levels following North Atlantic tropical cyclones to determine if changes in contaminant concentrations were predictable. The basis for this study was analysis of coastal chemical contaminant data from the National Oceanic and Atmospheric Administration's (NOAA) National Status and Trends Mussel Watch Program and NOAA's National Weather Service storm track data. The tendency for contaminant (metals and organic compounds) body burdens to increase or decrease in oyster tissue after a storm was assessed using contingency and correspondence analyses. Post-storm contaminant levels in oysters revealed a consistent pattern of distribution, which could be described as follows: (1) most of the organic contaminants stay within their long-term concentration ranges, (2) very few organic contaminants decreased, and (3) metals overwhelmingly tend to increase.
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Affiliation(s)
- Dennis A Apeti
- National Oceanic and Atmospheric Administration, Silver Spring, MD, USA.
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Wynne TT, Stumpf RP, Tomlinson MC, Schwab DJ, Watabayashi GY, Christensen JD. Estimating cyanobacterial bloom transport by coupling remotely sensed imagery and a hydrodynamic model. Ecol Appl 2011; 21:2709-21. [PMID: 22073654 DOI: 10.1890/10-1454.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The ability to forecast the transport of harmful cyanobacterial blooms in the Laurentian Great Lakes is beneficial to natural resource managers concerned with public health. This manuscript describes a method that improves the prediction of cyanobacterial bloom transport with the use of a preoperational hydrodynamic model and high temporal resolution satellite imagery. Two scenarios were examined from separate cyanobacterial blooms in western Lake Erie, USA. The first scenario modeled bloom position and extent over the span of 13 days. A geographic center, or centroid, was calculated and assigned to the bloom from observed satellite imagery. The bloom centroid was projected forward in time, and the projected position was compared to the final observed bloom centroid. Image pixels flagged as cyanobacterial bloom were compared between the initial image and the final image, and this was assumed as persistence. The second bloom scenario was modeled for a period of 12 days, and the results were framed in an ecological context in an effort to gain further understanding of cyanobacterial bloom dynamics. These modeling techniques can be incorporated into an operational forecasting system.
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Affiliation(s)
- Timothy T Wynne
- NOAA, Center for Coastal Monitoring and Assessment, 1305 East-West Highway, Silver Spring, Maryland 20910, USA.
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Christensen JD, Kirichenko A, Gayou O. TH-E-220-08: Flattening Filter Removal for Improved Megavoltage Imaging of Fiducial Markers. Med Phys 2011. [DOI: 10.1118/1.3613615] [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: 11/07/2022] Open
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Apeti DA, Lauenstein GG, Christensen JD, Kimbrough K, Johnson WE, Kennedy M, Grant KG. A historical assessment of coastal contamination in Birch Harbor, Maine based on the analysis of mussels collected in the 1940s and the Mussel Watch Program. Mar Pollut Bull 2010; 60:732-742. [PMID: 20097385 DOI: 10.1016/j.marpolbul.2009.11.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 11/24/2009] [Accepted: 11/29/2009] [Indexed: 05/28/2023]
Abstract
Coastal contamination in the 1940s was assessed based on analysis of canned blue mussels presumably collected from Birch Harbor, Maine, USA. Analytical results on legacy organic contaminants were compared to long-term National Oceanic and Atmospheric Administration (NOAA) Mussel Watch (MW) monitoring data to estimate the degree of coastal contamination before World War II (WWII) when many synthetic organic compounds were first introduced into the environment. While dieldrin and chlordane were not detected in the canned mussels, dichloro-diphenyl-trichloroethane (DDT) and hexachlorocyclohexanes (HCHs) were present at lower concentrations relative to the more recent MW data. Polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were detected, and the later were significantly higher in canned mussels relative to the MW data (p<0.05). Furthermore, moving average analysis applied to the MW data depicted three-phased temporal trend patterns (increase-decrease-steady state) for virtually all contaminants indicating an overall increased coastal contamination in post WWII era.
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Affiliation(s)
- D A Apeti
- National Oceanic and Atmospheric Administration, National Center for Coastal Ocean Sciences, Silver Spring, MD 20910, USA.
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Christensen JD. Tolerance development with chlordiazepoxide in relation to the plasma levels of the parent compound and its main metabolites in mice. Acta Pharmacol Toxicol (Copenh) 2009; 33:262-72. [PMID: 4800672 DOI: 10.1111/j.1600-0773.1973.tb01526.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Pait AS, Jeffrey CFG, Caldow C, Whitall DR, Hartwell SI, Mason AL, Christensen JD. Chemical contamination in southwest Puerto Rico: A survey of contaminants in the coralPorites astreoides. CARIBB J SCI 2009. [DOI: 10.18475/cjos.v45i2.a7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Pait AS, Whitall DR, Jeffrey CFG, Caldow C, Mason AL, Lauenstein GG, Christensen JD. Chemical contamination in southwest Puerto Rico: an assessment of trace and major elements in nearshore sediments. Mar Pollut Bull 2008; 56:1953-1956. [PMID: 18845309 DOI: 10.1016/j.marpolbul.2008.06.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 06/04/2008] [Accepted: 06/05/2008] [Indexed: 05/26/2023]
Affiliation(s)
- Anthony S Pait
- NOAA/NOS/NCCOS Center for Coastal Monitoring and Assessment, 1305 East/West Highway, Silver Spring, MD 20910, United States.
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Pait AS, Whitall DR, Jeffrey CFG, Caldow C, Mason AL, Lauenstein GG, Christensen JD. Chemical contamination in southwest Puerto Rico: an assessment of organic contaminants in nearshore sediments. Mar Pollut Bull 2008; 56:580-587. [PMID: 18191953 DOI: 10.1016/j.marpolbul.2007.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 11/09/2007] [Accepted: 11/13/2007] [Indexed: 05/25/2023]
Affiliation(s)
- Anthony S Pait
- NOAA/NOS/NCCOS Center for Coastal Monitoring and Assessment, 1305 East/West Highway, Silver Spring, MD 20910, United States.
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Abstract
This study investigated whether pituicytes were able to produce and release nitric oxide (NO), and which type of nitric oxide synthase (NOS) would be responsible for this phenomenon. Lipopolysaccharide (LPS) 1 micro g/ml was used as inflammatory mediator. Because pituicytes are known to secrete interleukin (IL)-6 upon stimulation with LPS, this parameter was also investigated. Cultured pituicytes, from 4-week-old male mice, were stimulated with LPS for 6 h or 24 h. At 24 h, there was a significant increase in accumulated nitrite indicating NO formation. In contrast, IL-6 release was already significantly higher 6 h after stimulation and further increased at 24 h. The correlation between accumulated nitrite and secreted IL-6 was 0.84 after 24 h of incubation with LPS. The expression of inducible NOS (iNOS) mRNA in the pituicytes was significantly higher than the control level after 6 h and 24 h of exposure to LPS, with levels at 6 h being significantly higher than those at 24 h. There was no detected expression of endothelial NOS or neuronal NOS mRNA. Cultured pituicytes were also subjected to immunocytochemistry for iNOS protein at 6, 12, and 24 h after stimulation with LPS. Most cells were positive for iNOS, but there were no observable differences with the time points that we used. Collectively, these results show that pituicytes are able to produce NO, and that the inducible form of NOS is responsible for this production. Furthermore, there is a weak correlation between NO and IL-6 released from pituicytes after 24 h of stimulation with LPS.
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Affiliation(s)
- T H Kjeldsen
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute, La Jolla, CA, USA.
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Abstract
BACKGROUND Antipsychotic response after the initiation of neuroleptic treatment shows wide variation in schizophrenic patient populations. In this overview, the authors suggest that the variance in antipsychotic drug response within schizophrenia can be reduced by resolving the schizophrenias into several discrete "endophenotypes," each with different etiologic underpinnings. METHOD Studies relating differences in the relative speed or completeness of antipsychotic response to differences in distribution of 2 biological markers with possible etiologic significance are reviewed. Such studies had assessed recently hospitalized, neuroleptic-free patients undergoing exacerbation of nonaffective psychotic disorders. Prior to initiation of neuroleptic, the cohort of patients had been assessed for the quantity of the dopamine metabolite homovanillic acid in plasma (pHVA) and had undergone the first of 2 magnetic resonance imaging (MRI) studies for analyses of ventricle volumes. A second MRI was subsequently performed during a period of (partial) remission to determine within-patient stability of ventricular volumes. These selected studies assessed the distribution of pHVA and distribution of rates of ventricular change, with non-normal distributions resolved by K-means clustering. The speed and completeness of neuroleptic-induced antipsychotic response were related to 3 clusters of patients delineated by modal distributions of pHVA and of apparent rates of ventricular change. RESULTS At least 3 unique "endophenotypes" of the "group of the schizophrenias" can be defined with respect to speed and completeness of antipsychotic response. Each endophenotype appears to show at least one unique biological feature that differentiates it from a normal comparison group. A rapidly responsive psychosis was associated with excessive production of dopamine, as identifiable by elevation of pHVA and a "good-prognosis" course. A delayed-response psychosis had low-to-normal pHVA, clinically demonstrated persistent negative symptoms, and was associated with an excessive rate of change in ventricle volume between exacerbations of psychosis and (partial) remissions. Finally, a nonresponsive psychosis could be characterized as having both low-to-normal pHVA and rate of change of ventricle volumes similar to that of controls. Additional studies revealed that each of the endophenotypes had high rates of the psychoses in family members. The good-prognosis course of the rapidly responsive group of studied patients was also found in their family members who had psychotic disorders. Similarly, the prominent negative symptoms of the delayed-response probands were reflected as a prominent trait in their family members also afflicted with psychosis. The endophenotypes tended to "breed true" in terms of prognosis and negative symptoms. CONCLUSION Major differences in antipsychotic response patterns appear to be associated with patient and family characteristics that may be related to differences in the etiology and consequent pathophysiology of illness.
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Affiliation(s)
- D L Garver
- Department of Psychiatry and Behavioral Sciences, and the Louisville Veterans Affairs Medical Center, University of Louisville School of Medicine, KY 40202, USA
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Ramsey JJ, Colman RJ, Binkley NC, Christensen JD, Gresl TA, Kemnitz JW, Weindruch R. Dietary restriction and aging in rhesus monkeys: the University of Wisconsin study. Exp Gerontol 2000; 35:1131-49. [PMID: 11113597 DOI: 10.1016/s0531-5565(00)00166-2] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.2] [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: 11/28/2022]
Abstract
Dietary restriction (DR) retards aging and extends the maximum lifespan of laboratory mice and rats. To determine whether DR has similar actions in a primate species, we initiated a study in 1989 to investigate the effects of a 30% DR in 30 adult male rhesus monkeys. In 1994, an additional 30 females and 16 males were added to the study. Although the animals are still middle-aged, a few differences have developed between the control and DR animals suggesting that DR may induce physiologic changes in the rhesus monkey similar to those observed in rodents. Fasting basal insulin and glucose concentrations are lower in DR compared to control animals while insulin sensitivity is higher in the restricted animals. DR has also altered circulating LDL in a manner that may inhibit atherogenesis. These results suggest that DR may be slowing some age-related physiologic changes. In addition to measures of glucose and lipid metabolism, the animals are evaluated annually for body composition, energy expenditure, physical activity, hematologic indices, and blood or urinary hormone concentrations. In the next few years, the first animals will reach the average lifespan ( approximately 26 years) of captive rhesus monkeys and it will become possible to determine if DR retards the aging process and extends the lifespan in a primate species.
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Affiliation(s)
- J J Ramsey
- Wisconsin Regional Primate Research Center, University of Wisconsin, Madison, WI, USA
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Christensen JD, Kaufman MJ, Frederick B, Rose SL, Moore CM, Lukas SE, Mendelson JH, Cohen BM, Renshaw PF. Proton magnetic resonance spectroscopy of human basal ganglia: response to cocaine administration. Biol Psychiatry 2000; 48:685-92. [PMID: 11032980 DOI: 10.1016/s0006-3223(00)00897-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Proton magnetic resonance spectroscopy was used to determine the effects of intravenous cocaine or placebo administration on human basal ganglia water and metabolite resonances. METHODS Long echo time, proton magnetic resonance spectra of water and intracellular metabolites were continuously acquired from an 8-cm(3) voxel centered on the left caudate and putamen nuclei before, during, and after the intravenous administration of cocaine or a placebo in a double-blind manner. RESULTS Cocaine, at both 0.2 and 0.4 mg/kg, did not alter the peak area for water. Cocaine at 0.2 mg/kg induced small and reversible increases in choline-containing compounds and N-acetylaspartate peak areas. Cocaine at 0.4 mg/kg induced larger and more sustained increases in choline-containing compounds and N-acetylaspartate peak areas. No changes in either water or metabolite resonances were noted following placebo administration. CONCLUSIONS These increases in choline-containing compounds and N-acetylaspartate peak areas may reflect increases in metabolite T2 relaxation times secondary to osmotic stress and/or increased phospholipid signaling within the basal ganglia following cocaine administration. This is the first report of acute, drug-induced changes in the intensity of human brain proton magnetic resonance spectroscopy resonance areas.
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Affiliation(s)
- J D Christensen
- Brain Imaging Center, McLean Hospital, Belmont, Massachusetts 02478-9106, USA
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Abstract
BACKGROUND Pharmaceutical products containing proteins cause problems in testing for endotoxin and pyrogens. Many proteins interfere with the LAL test and the proteins are immunogenic in rabbits. The monocytic cell line Mono Mac 6 is an alternative assay for detection of endotoxin and other pyrogens. OBJECTIVE To evaluate the use of the Mono Mac 6 assay for quantitative detection of endotoxin in proteins. METHOD The quantitative detection of endotoxin in the three pharmaceutical products human albumin, gamma-globulin and somatropin was evaluated. RESULTS For the three proteins the detection limit of the Mono Mac 6 assay was far below the threshold endotoxin limit described by the European Pharmacopoeia. Interference of two of the proteins with the Mono Mac 6 assay was observed, but the problems could be overcome either by dilution of the product or by comparison of the test with an endotoxin standard curve prepared in a solution of the respective pyrogen-free protein. CONCLUSION The Mono Mac 6 assay is a reliable method for quantitative detection of endotoxin in proteins.
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Affiliation(s)
- L Moesby
- Department of Pharmacology, The Royal Danish School of Pharmacy, 2 Universitetsparken, 2100 Copenhagen, Denmark.
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Abstract
Recent reports from serial brain scans suggest that the rate of ventricular expansion and/or brain atrophy may be accelerated in at least some schizophrenics. The authors assessed the effect of state changes upon such findings.Within-subject 3D MRIs were assessed for ventricular and brain volumes during periods of [partial] remission and of exacerbation of psychosis. Additional scans at comparable within-subject SAPS were used to assess rates of change in volumes that were independent of SAPS changes. Correlations of changes of ventricle and brain volumes vs. change of SAPS cores between scans revealed that ventricle volumes decreased during a period of psychotic exacerbation and increased at a time of [partial] remission (r(p)=-0.666; P<0.0005); conversely, brain volumes increased during psychotic exacerbation and decreased at [partial] remission (r(p)=+0.448; P=0.032). Scans at comparable SAPS scores suggested that the majority of patients had rates of ventricular expansion comparable to controls (0.9+/-0.6 cc/year), though two patients appeared to have rates of ventricular increase of 4.5+/-2. 1 cc/year (Lilliefores P=0.036; K-means clustering F=17.75). Exacerbation of psychosis in schizophrenia is accompanied by evidence of brain swelling, especially of periventricular brain, with encroachment of brain substance upon ventricular volumes. Controlled for state changes, the majority of schizophrenics show rates of ventricular expansion or brain atrophy indistinguishable from controls.
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Affiliation(s)
- D L Garver
- University of Louisville School of Medicine, Department of Psychiatry and Behavioral Sciences, Louisville, KY 40222, USA.
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Abstract
The monocytic cell line Mono Mac 6 is sensitive to pyrogens. When exposed to pyrogens secretion of interleukin-6 is induced. However, some eukaryotic pyrogenic microorganisms are not detectable. The aim of this study is to introduce a pretreatment of samples to expand the detection range of the assay. The interleukin-6 inducing capacity of a broad spectrum of UV-killed and ultrasonicated microorganisms is examined in Mono Mac 6 cells. The interleukin-6 secretion is determined in a sandwich immunoassay (DELFIA). The Mono Mac 6 assay is able to detect UV-killed Bacillus subtilis, Staphylococcus aureus and Salmonella typhimurium, but neither Candida albicans nor Aspergillus niger. After ultrasonication of the microorganisms it is possible to detect C. albicans and A. niger. The interleukin-6 inducing ability of the examined microorganisms is in no case reduced after ultrasonic treatment. However, ultrasonication of S. aureus results in a 100-fold increase in the interleukin-6 response. Even after ultrasonication Streptococcus faecalis can not be detected. Ultrasonication is an easy and simple method for expanding the detection range in the Mono Mac 6 assay.
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Affiliation(s)
- L Moesby
- The Royal Danish School of Pharmacy, Department of Pharmacology, Denmark.
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Roscoe AK, Christensen JD, Lynch C. Isoflurane, but not halothane, induces protection of human myocardium via adenosine A1 receptors and adenosine triphosphate-sensitive potassium channels. Anesthesiology 2000; 92:1692-701. [PMID: 10839921 DOI: 10.1097/00000542-200006000-00029] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [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: 11/26/2022]
Abstract
BACKGROUND Volatile anesthetics produce differing degrees of myocardial protection in animal models of ischemia. The purpose of the current investigation was to determine the influence of isoflurane and halothane on myocardial protection in a human model of simulated ischemia and the role of adenosine A1 receptors and adenosine triphosphate-sensitive potassium (KATP) channels in the anesthetic pathway. METHODS Human atrial trabecular muscles were superfused with oxygenated Krebs-Henseleit buffer and stimulated at 1 Hz, with recording of maximum contractile force. Fifteen minutes before a 30-min anoxic insult, muscles were pretreated for 5 min with either anoxia, the A1 agonist N6-cyclohexyladenosine, 1% halothane or 1.2% isoflurane. These treatments were also performed in the presence of either the KATP channel antagonist glibenclamide or the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). Anesthetic effects were also determined on KATP currents in isolated whole cell voltage-clamped human atrial myocytes. RESULTS Recovery of force (recorded 60 min after anoxia) in isoflurane-pretreated muscles was reduced from 76.6 +/- 7.5% of baseline to 43.7 +/- 7.1% by pretreatment with glibenclamide, and to 52.5 +/- 6.2% by pretreatment with DPCPX. Halothane treatment provided no cardioprotection and seemed to inhibit protection by anoxic preconditioning. Halothane decreased whole cell KATP currents in atrial myocytes, whereas isoflurane had no effects. CONCLUSIONS This study demonstrates the cardioprotective effects of isoflurane in contrast to the effects of halothane. Furthermore, A1 receptors and KATP channels seem to mediate the beneficial effects of anoxia and isoflurane in human myocardium.
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Affiliation(s)
- A K Roscoe
- Department of Anesthesiology, University of Virginia, Charlottesville, Virginia 22906-0010, USA
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Moesby L, Jensen S, Hansen EW, Christensen JD. A comparative study of Mono Mac 6 cells, isolated mononuclear cells and Limulus amoebocyte lysate assay in pyrogen testing. Int J Pharm 1999; 191:141-9. [PMID: 10564840 DOI: 10.1016/s0378-5173(99)00294-x] [Citation(s) in RCA: 36] [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: 10/18/2022]
Abstract
Pyrogen induced secretion of interleukin 6 (IL-6) in Mono Mac 6 (MM6) cells was measured. The ability of the MM6 cell culture to detect pyrogens was compared to the Limulus amoebocyte lysate (LAL) test and isolated mononuclear cells (MNC). The detection limit of MM6 for lipopolysaccharide (LPS) and Staphylococcus aureus was comparable to that of MNC. Aspergillus niger and Candida albicans induced IL-6 in isolated MNC, but not in MM6. The detection limit for Salmonella typhimurium in the MM6 assay was comparable to that of the LAL assay. As expected, S. aureus and C. albicans did not show any LAL activity. A. niger and Influenza virus showed some activity in the LAL test, but could not be detected by MM6 cells. In conclusion, the MM6 assay is a good supplement to the current pyrogen assays for detection of LPS, S. aureus and S. typhimurium, but the MM6 assay could not detect A. niger, C. albicans and Influenza virus.
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Affiliation(s)
- L Moesby
- The Royal Danish School of Pharmacy, Department of Pharmacology, 2 Universitetsparken, 2100, Copenhagen, Denmark.
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Abstract
Electrical stimulation of the cerebellar fastigial nucleus (FN) in spontaneously hypertensive (SHR), Wistar-Kyoto (WKY) and Fisher rats reduced, by approximately 50%, the infarctions produced by occlusion of the middle cerebral artery. Blockade of ATP-dependent potassium (K-ATP) channels with glibenclamide (i.c.v.) abolished salvage only in the SHR rat. While blockade of K-ATP channels failed to abolish salvage in WKY and Fisher rats, participation of potassium channels in neurogenic neuroprotection cannot be excluded.
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Affiliation(s)
- E V Golanov
- Department of Neurology and Neuroscience, Weill Medical College of Cornell University, 411 East 69th Street, KB410, New York, NY 10021, USA.
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Hansen EW, Malling D, Christensen JD. Endotoxin-stimulated release of cytokines by cultured cells from the murine neurohypophysis: role of dexamethasone and indomethacin. Neuroimmunomodulation 1999; 6:330-5. [PMID: 10474051 DOI: 10.1159/000026392] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [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: 11/19/2022] Open
Abstract
It is well established that many cell types produce inflammatory cytokines and we were interested to see whether cells in the neurohypophysis had this ability. This study examines the effect of lipopolysaccharide (LPS) on cytokine production in cultured murine neural lobe (NL) cells. Cells were cultured from the neurohypophysis of mice not older than 5 days and the experiments were performed after 12 days in culture. The majority of cells in culture were immunoreactive for glial fibrillary acidic protein, indicating that the cells were pituicytes. Cytokines were measured in 24-hour samples using commercial ELISA kits. Cells growing in a medium free of endotoxin released 94.3 +/- 6.6 pg IL-6/NL/24 h (mean +/- SEM, n = 21). The release of interleukin-6 (IL-6) was reversible and increased concentration dependently with LPS in the concentration range of 0.1-1 ng/ml. The addition of 1 ng/ml LPS increased the IL-6 release 12-fold to a maximum value of 1,134 +/- 85.5 pg IL-6/NL/24 h (mean +/- SEM, n = 6). No trace of interleukin-1beta (IL-1beta) (<3 pg/NL/24 h) or tumor necrosis factor-alpha (<10 pg/NL/24 h) was detected after LPS stimulation. We examined the effect of dexamethasone (10(-6) M) and indomethacin (10(-4) M) on the release of IL-6 in submaximally stimulated cells. Dexamethasone inhibited the unstimulated and the LPS-stimulated release of IL-6 by 70 and 81%, respectively. Indomethacin had no influence on the release, and it is concluded that cyclooxygenase is not involved in the response. A close association exists between the membrane of the neurosecretory endings and the pituicytes in the neurohypophysis. This naturally raises the question as to whether IL-6 might reflect a physiological connection between the two cell types.
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Affiliation(s)
- E W Hansen
- Department of Pharmacology, The Royal Danish School of Pharmacy, Copenhagen, Denmark.
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Christensen JD, Hansen EW, Frederiksen C, Mølris M, Moesby L. Adrenaline influences the release of interleukin-6 from murine pituicytes: role of beta2-adrenoceptors. Eur J Pharmacol 1999; 378:143-8. [PMID: 10478575 DOI: 10.1016/s0014-2999(99)00448-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [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: 01/18/2023]
Abstract
In this study, we examined the effect of adrenaline and interleukin-1beta on interleukin-6 secretion from cultured murine neurohypophyseal cells. Cells were cultured from neurohypophyses of 3- to 5-week-old mice and experiments were performed after 13 days in culture. Interleukin-6 was measured in 24-h samples using a sandwich fluoroimmunoassay. Unstimulated cells released 19+/-3 fmol interleukin-6/neurohypophysis/24 h (mean +/- S.E.M., n = 42). Adrenaline and interleukin-1beta increased the release of interleukin-6 from the cells in a concentration-dependent manner. Incubation with adrenaline (10(-6) M) or interleukin-1beta (11 pM) induced maximal secretion of interleukin-6, resulting in a 2.2-fold and 19.8-fold increase, respectively (P<0.01). The action of adrenaline (10(-6) M) and interleukin-1beta (1.1 pM) was examined separately and together. The sum of the effect of the two compounds given alone was significantly less (P<0.05) than the effect when adrenaline and interleukin-1beta were given together. We examined the effect of the beta-adrenoceptor antagonist propranolol (3.4x10(-6) M), the beta2-adrenoceptor antagonist (+/-)-1-[2,3-(Dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methyl-eth yl)amino]-2-butanol (ICI 118551) (10(-7) M) and the beta1-adrenoceptor antagonist atenolol (10(-7) M and 10(-6) M) on the adrenaline-stimulated release of interleukin-6. Propranolol and ICI 118551 completely blocked the action of adrenaline, whereas atenolol was inactive. It is concluded that the stimulatory effect of adrenaline is mediated via beta2-adrenoceptors.
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Affiliation(s)
- J D Christensen
- Department of Pharmacology, The Royal Danish School of Pharmacy, Copenhagen, Denmark.
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Christensen JD, Yurgelun-Todd DA, Babb SM, Gruber SA, Cohen BM, Renshaw PF. Measurement of human brain dexfenfluramine concentration by 19F magnetic resonance spectroscopy. Brain Res 1999; 834:1-5. [PMID: 10407087 DOI: 10.1016/s0006-8993(99)01441-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [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: 11/25/2022]
Abstract
OBJECTIVE The goals of this study were to quantitate the brain concentration of the anorectic drug dexfenfluramine (DF) in human subjects receiving clinical doses of DF and to determine whether human brain DF concentrations approach those reported to cause irreversible neurochemical changes in animals. Each subject's brain DF concentration was measured several times over an extended period of DF treatment to determine whether drug accumulation in the brain would plateau or continue to increase throughout the treatment period. DESIGN Fluorine magnetic resonance spectroscopy (19F-MRS) was used to directly detect and quantitate brain levels of the fluorinated drug dexfenfluramine and its active metabolite dex-norfenfluramine (dNF). Patients received 15 mg dexfenfluramine BID for 90 days. 19F-MRS measurements were performed at baseline and at three times during the treatment period. PARTICIPANTS Twelve women (age 38-54 years) who were obese, with body mass indices of 28. 4-37.4, but otherwise healthy. RESULTS The combined concentration of DF and nDF reached steady-state in the human brain after approximately 10 days of treatment. The steady-state brain concentration averaged approximately 4 microM and did not tend to increase significantly during the 90 day treatment period. CONCLUSIONS These results demonstrate that fluorinated drugs can be quantified using 19F MRS at concentrations below 10 microM in the human brain. The time-course data suggest that brain DF concentrations parallel DF plasma pharmacokinetics in humans. Measured brain dexfenfluramine/nor-dexfenfluramine concentrations were well below levels previously found to cause irreversible brain alterations in animals.
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Affiliation(s)
- J D Christensen
- Brain Imaging Center, McLean Hospital, 115 Mill Street, Belmont, MA 02478, USA
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Garver DL, Nair TR, Christensen JD, Holcomb J, Ramberg J, Kingsbury S. Atrophic and static (neurodevelopmental) schizophrenic psychoses: premorbid functioning, symptoms and neuroleptic response. Neuropsychopharmacology 1999; 21:82-92. [PMID: 10379522 DOI: 10.1016/s0893-133x(98)00138-9] [Citation(s) in RCA: 23] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The question of whether schizophrenic-like disorders are neurodevelopmental or degenerative in origin has been argued since the time of Kraepelin. The authors provide evidence for the existence of two etiologically distinct endophenotypes of the psychoses contained within the rubric of familial non-affective psychosis (schizophrenia), one atrophic and the other neurodevelopmental. The atrophic psychosis, identified by progressive ventricular enlargement throughout adult illness, evidences progressive impairment of interests, relationships, and withdrawal from latency through adolescence, with emergence of trait-like negative symptoms which are only marginally responsive to conventional neuroleptics. This psychosis also exhibits delayed response of positive symptoms during neuroleptic treatment, and may also proceed to a praecox dementia in later life. In contrast, a putative neurodevelopmental psychosis, associated with static ventricles during the course of adult illness, also demonstrates preadolescent impairments, but impairments which do not progress to marked negative symptoms. Conventional neuroleptics appear to have little effect (except sedation) on positive symptoms, but appear to induce negative symptomatology and partial disengagement from the burden of persistent psychotic thought processes in such static ventricle psychoses. Thus, separate patterns of illnesses with different prodromal features, different treatment response patterns, and different patterns of residual (negative) symptoms appear to characterize patients with psychosis who have expanding as opposed to stable cerebral-ventricles at doses of neuroleptic at 10 mg haloperidol equivalents/day.
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Affiliation(s)
- D L Garver
- Department of Psychiatry, Southwestern Medical Center of the University of Texas, Dallas, USA
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Filbey FM, Holcomb J, Nair TR, Christensen JD, Garver DL. Negative symptoms of familial schizophrenia breed true in unstable (vs. stable) cerebral-ventricle pedigrees. Schizophr Res 1999; 35:15-23. [PMID: 9988837 DOI: 10.1016/s0920-9964(98)00107-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [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: 11/24/2022]
Abstract
A pattern of negative symptoms associated with a high rate of ongoing brain and ventricular instability has been described in a cohort of schizophrenia spectrum probands (patients with schizophrenia, schizoaffective disorder depressed and bipolar, and psychosis NOS) (Garver, D.L., Nair, T.R., Christensen, J.D., Holcomb, J., Ramberg, J., Kingsbury, S., 1999. Differential patterns of premorbid functioning, symptoms and neuroleptic response in stable and unstable ventricular-volume schizophrenia. Neuropsychopharmacology 20, in press). The present study contrasts the prevalence of negative symptoms in first- and second-degree relatives of probands with unstable ventricle volume (UnsVV) and stable ventricle volume (SVV). One hundred and sixteen first- and second-degree relatives of 10 probands were interviewed using the SANS, the 'Characterization of Course: "Pattern of Symptoms"' [from Comprehensive Assessment of Symptoms and History (CASH)], SCID and SCID-II by interviewers blind to the status of the proband. Thirty-five of the 116 family members met DSM-IV criteria for schizophrenia, SA depressed, 'Cluster A' of the SCID-II (paranoid, schizotypal, schizoid personality disorder), psychosis NOS, or psychotic affective disorder. These 35 family members were defined as falling within a 'schizophrenia spectrum' as described by Farmer, A.E., McGuffin, P., Gottesman, I.I., 1987. Arch. Gen. Psychiatry 44, 634-641, but with the addition of DSM-IV affective psychosis. On that basis, the 35 members were considered 'affected family members' (AFMs). The remaining 81 family members were considered unaffected. The 'predominant symptoms of illness' (during the past 2-3 years) for 25 of the 35 AFMs could be characterized according to the 'Patterns of Symptoms' derived from the CASH. Twenty-five of the 35 AFMs were found to maintain a predominant symptom pattern during the course of illness, which could be characterized according to the 'Pattern of Symptoms' as 'predominantly positive' or 'predominantly negative'. Three of the probands had UnsVV; seven had SVV. Of the 35 AFMs, 11 were related to the UnsVV probands, and 24 were relatives of the SVV probands. The nine rated AFMs of the UnsVV probands showed a trend toward higher SANS scores (7.3 +/- 5.1) (mean +/- s.d.) than the 20 rated AFMs of SVV probands (4.3 +/- 5.1) (p = 0.08) at the time of the interview. Eighty-three per cent (eight of 10) of rated affected pedigree members of the pedigrees delineated by probands with UnsVV probands had a predominantly negative symptom course of illness, and 96% (23 of 24) of rated affected pedigree members of the pedigrees with SVV probands had a predominantly positive symptom course of illness during the preceding 2-3 years (p = 0.002). None of the 12 rated affected pedigree members within pedigrees having UnsVV probands were married at the time of the interview; 45% (14 of 31) of affected pedigree members having SVV probands were married (p = 0.004). A psychiatric disorder, characterized by unstable cerebral ventricles and predominant negative symptoms (including avoidance/failure of marital relationships) appears symptomatically to breed true in pedigrees containing schizophrenia-like illnesses.
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Abstract
Reliable interpretation of the MR signal intensity over the FOV of an image must consider the spatial heterogeneity of instrumental sensitivity. A major source of such variation is the nonuniformity of the B1 magnetic field of the radiofrequency coil. This heterogeneity can be minimized by coil design but is exaggerated by surface coils, which are used to maximize the signal-to-noise ratio for some applications. This paper describes a rapid method for mapping the B1 field over the sample of interest, using 1H echo-planar imaging, to correct for B1 distortions. The method applies to 1H imaging and has been extended to non-1H imaging by using dual-frequency coils in which the B1 distributions are matched for the 1H frequency and the frequency of interest. The approach is demonstrated in phantoms, animals, and humans and for sodium imaging.
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Affiliation(s)
- K R Thulborn
- MR Research Center, Department of Radiology, University of Pittsburgh Medical Center, Pennsylvania, USA
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Christensen JD, Babb SM, Cohen BM, Renshaw PF. Quantitation of dexfenfluramine/d-norfenfluramine concentration in primate brain using 19F NMR spectroscopy. Magn Reson Med 1998; 39:149-54. [PMID: 9438448 DOI: 10.1002/mrm.1910390121] [Citation(s) in RCA: 12] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Fluorine (19F) magnetic resonance spectroscopy (MRS) was used to quantify the combined concentration of the anorectic drug dexfenfluramine (DF) and its active metabolite d-norfenfluramine (dNF) in rhesus monkey brain. The accuracy of the MRS technique was assessed by comparison with gas chromatography. Brain 19F MRS signals were converted to brain DF + dNF concentrations after correction for signal relaxation losses and drug distribution in nonbrain tissue. Gas chromatography (GC) was used to assay brain DF and dNF concentrations following MRS evaluation. DF + dNF concentrations measured by 19F MRS averaged 104 +/- 36 microM (mean +/- SD) and GC measurements averaged 71 +/- 12 microM. Correction for the distribution of DF and its metabolites in nonbrain tissue yielded a DF + metabolite brain concentration that was within one standard deviation of the GC-derived value. The concentration of DF plus dNF measured by 19F MRS was similar to or greater than the value obtained by GC, which indicates that DF and its active metabolite dNF are fully detected by 19F MRS in primate brain in vivo. The application of these techniques to human subjects should enable the measurement of low micromolar-range brain concentrations of DF and other fluorinated drugs.
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Affiliation(s)
- J D Christensen
- Brain Imaging Center, McLean Hospital, Belmont, Massachusetts, USA
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Abstract
Several anatomic abnormalities in the brains of schizophrenics have frequently been reported. However, it remains unresolved whether such neuropathology is fully expressed and static at the onset of psychosis or whether further deterioration evolves during the course of illness. To address this important question, we obtained serial volumetric magnetic resonance images (MRI) of the cerebral ventricles of 18 patients with schizophrenic symptoms. Repeated blind measurements of total ventricular volume (TVV) revealed < 2% error of the segmentation method. Over a 2-3 year period, the rate of ventricular expansion (RVE) was 2.2 +/- 1.6 cm3/year in the patients and 0.7 +/- 0.6 cm3/year in controls. The RVE in the patients was not normally distributed, but clustered into two groups: a group similar to controls (n = 10; RVE, 0.9 +/- 0.5 cm3/year) and a group with a significantly greater rate of expansion (n = 8; RVE, 3.9 +/- 0.7 cm3/year) (P < 0.001). These results suggest that there are at least two subpopulations within the schizophrenias: one with relatively static ventricles and another with progressively enlarging ventricles. At least two distinct etiologic processes may thus underlie the clinical presentation of schizophrenic symptoms. Factors which might influence ventricular expansion (neuroleptic compliance, alcohol and recreational drug abuse, and some clinical correlates) could not account for differences between groups.
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Affiliation(s)
- T R Nair
- Department of Psychiatry, Dallas Veterans Administration Medical Centre, TX 75216, USA
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Renshaw PF, Lafer B, Babb SM, Fava M, Stoll AL, Christensen JD, Moore CM, Yurgelun-Todd DA, Bonello CM, Pillay SS, Rothschild AJ, Nierenberg AA, Rosenbaum JF, Cohen BM. Basal ganglia choline levels in depression and response to fluoxetine treatment: an in vivo proton magnetic resonance spectroscopy study. Biol Psychiatry 1997; 41:837-43. [PMID: 9099409 DOI: 10.1016/s0006-3223(96)00256-9] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have investigated proton magnetic resonance spectra of the basal ganglia in 41 medication-free outpatients with major depression, prior to starting an 8-week standardized trial of open-label fluoxetine, and 22 matched comparison subjects. Upon completing the trial, depressed subjects were classified as treatment responders (n = 18) or nonresponders (n = 23), based on changes in the Hamilton Depression Rating Scale. Depressed subjects had a lower area ratio of the choline resonance to the creatine resonance (Cho/Cr) than comparison subjects. This statistically significant difference between the depressed subjects and comparison subjects was more pronounced in the treatment responders than in the nonresponders. There were no differences in the relative volumes of gray matter or white matter in the voxel used for proton spectroscopy in depressed subjects relative to comparison subjects. These results are consistent with an alteration in the metabolism of cytosolic choline compounds in the basal ganglia of depressed subjects and, in particular, those who are responsive to fluoxetine.
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Affiliation(s)
- P F Renshaw
- Brain Imaging Center, McLean Hospital, Belmont, Massachusetts 02178, USA
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38
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Abstract
This study demonstrates a sampling scheme for three-dimensional projection imaging with half the number of projections. The angular distribution of projections is designed so that the oversampling of the low spatial frequencies, in tandem with a partial Fourier algorithm, can be used to recreate purposely missing projections. The performance of the sampling scheme and its associated reconstruction algorithm are illustrated with computer-simulated as well as experimental data sets. We find that this technique produces images of comparable quality to the conventional projection imaging scheme. Although a 30% loss of signal-to-noise ratio (SNR) results from its use, the algorithm should prove useful for applications where robustness against motion artifacts and reduced T2* signal loss are desired.
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Affiliation(s)
- F E Boada
- Magnetic Resonance Research Center, University of Pittsburgh Medical Center, Pennsylvania 15213, USA
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39
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Moore CM, Christensen JD, Lafer B, Fava M, Renshaw PF. Lower levels of nucleoside triphosphate in the basal ganglia of depressed subjects: a phosphorous-31 magnetic resonance spectroscopy study. Am J Psychiatry 1997; 154:116-8. [PMID: 8988971 DOI: 10.1176/ajp.154.1.116] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.0] [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: 02/03/2023]
Abstract
OBJECTIVE The purpose of this study was to evaluate whether the concentration of beta-nucleoside triphosphate is lower in the basal ganglia of depressed subjects. METHOD In vivo 31P magnetic resonance spectra were acquired from a 45-cm3 region surrounding the basal ganglia of 35 unmedicated depressed subjects and 18 comparison subjects. RESULTS beta-Nucleoside triphosphate, which arises primarily from beta-ATP, was 16% lower in the depressed subjects than in the comparison subjects. CONCLUSIONS The low level of beta-nucleoside triphosphate is consistent with an abnormality of high-energy phosphate metabolism in the basal ganglia of subjects with major depression.
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Affiliation(s)
- C M Moore
- Brain Imaging Center, McLean Hospital, Belmont, MA 02178, USA
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40
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Rossi MA, Chan CK, Christensen JD, DeGuzman EJ, Durieux ME. Interactions between propofol and lipid mediator receptors: inhibition of lysophosphatidate signaling. Anesth Analg 1996; 83:1090-6. [PMID: 8895292 DOI: 10.1097/00000539-199611000-00034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [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: 02/02/2023]
Abstract
As a highly lipophilic drug, propofol may interact with lipophilic domains in addition to its likely primary site of action on the gamma-aminobutyrateA) (GABA(A)) receptor. Likely candidates for such interaction are the G protein-coupled membrane receptors for lipid intercellular mediators. The phospholipid lysophosphatidate (LP) has attracted attention as such a signaling molecule. It has a variety of biological actions, including vasoconstriction. We therefore studied the interaction between propofol and the LP receptor. Intracellular Ca2+ release in response to LP was assessed by measuring C1- flux through Ca(2+)-activated C1- channels in Xenopus oocytes. The average charge movement in response to LP 10(-7)M was 2.0 +/- 0.2 microCoulombs. Propofol in Intralipid (0.01%) dose-dependently inhibited LP signaling (50% inhibitory concentration [IC50] 5.38 microM). Propofol 28 microM inhibited LP signaling by 81%. Intralipid (0.01%) was without effect. To ascertain that intracellular signaling pathways and the Ca(2+)-activated C1- channel were not affected by propofol, we tested the effects of propofol (5.6 microM) on currents induced by methylcholine (10(-7)M) in oocytes expressing the m1 muscarinic acetylcholine receptor. No inhibition was observed. As both receptors share the same intracellular signaling pathway, we conclude that clinically relevant concentrations of propofol most likely inhibit the LP receptor or its G protein. Inhibition of LP signaling may explain some of propofol's vasodilating actions.
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Affiliation(s)
- M A Rossi
- Department of Anesthesiology, University of Virginia Health Sciences Center, Charlottesville 22908, USA
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41
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Keltner JR, Wald LL, Christensen JD, Maas LC, Moore CM, Cohen BM, Renshaw PF. A technique for detecting GABA in the human brain with PRESS localization and optimized refocusing spectral editing radiofrequency pulses. Magn Reson Med 1996; 36:458-61. [PMID: 8875418 DOI: 10.1002/mrm.1910360319] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [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: 02/02/2023]
Abstract
A proton magnetic resonance spectral editing technique is presented that uses PRESS excitation to achieve spatially localized measurements of brain gamma-aminobutyric acid (GABA). The homonuclear difference spectroscopy technique employs a frequency selective inversion pulse to suppress the creatine resonance at 3.0 ppm. The timing of this pulse is optimized to maximize the suppression of creatine by minimizing the effect of the editing pulse on the 3.0 ppm resonances. The PRESS excitation achieves three dimensional spatial localization in a single acquisition making it less sensitive to patient motion than multiple acquisition techniques. The performance and utility of this technique were evaluated by phantom experiments and by in vivo measurements of brain GABA concentration in 10 normal subjects.
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Affiliation(s)
- J R Keltner
- Brain Imaging Center, McLean Hospital Belmont, Cambridge, Massachusetts, USA
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42
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Stoll AL, Sachs GS, Cohen BM, Lafer B, Christensen JD, Renshaw PF. Choline in the treatment of rapid-cycling bipolar disorder: clinical and neurochemical findings in lithium-treated patients. Biol Psychiatry 1996; 40:382-8. [PMID: 8874839 DOI: 10.1016/0006-3223(95)00423-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [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: 02/02/2023]
Abstract
This study examined choline augmentation of lithium for rapid-cycling bipolar disorder. Choline bitartrate was given openly to 6 consecutive lithium-treated outpatients with rapid-cycling bipolar disorder. Five patients also underwent brain proton magnetic resonance spectroscopy. Five of 6 rapid-cycling patients had a substantial reduction in manic symptoms, and 4 patients had a marked reduction in all mood symptoms during choline therapy. The patients who responded to choline all exhibited a substantial rise in the basal ganglia concentration of choline-containing compounds. Choline was well tolerated in all cases. Choline, in the presence of lithium, was a safe and effective treatment for 4 of 6 rapid-cycling patients in our series. A hypothesis is suggested to explain both lithium refractoriness in patients with bipolar disorder and the action of choline in mania, which involves the interaction between phosphatidylinositol and phosphatidylcholine second-messenger systems.
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Affiliation(s)
- A L Stoll
- Psychopharmacology Unit, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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43
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Abstract
A quantitative in vivo method for obtaining maps of tissue sodium concentration (TSC) by MRI is compared to the invasive, global 22Na radionuclide dilutional technique in the normal rat brain. The MR method uses a three-dimensional projectional acquisition scheme to minimize signal losses from transverse relaxation. Internal calibration standards are used to convert the signal intensity into TSC after correction for B1 inhomogeneities by using the ratio of 23Na and 1H images obtained with identical B1 distributions and sensitivities at the two frequencies. Over the biological range of concentrations, the TSC, measured as the ratio of MR signals of 23Na and 1H, gives a linear response with concentration. In the normal rat brain, the mean TSC measured using the MRI method (TSC = 45 +/- 4 mM, animals = 5) is not significantly different from the global 22Na radionuclide method (TSC = 49 +/- 6 mM, animals = 7).
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Affiliation(s)
- J D Christensen
- Massachusetts General Hospital NMR Center, Dept. of Radiology, Charlestown, USA
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44
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Christensen JD, Kaufman MJ, Levin JM, Mendelson JH, Holman BL, Cohen BM, Renshaw PF. Abnormal cerebral metabolism in polydrug abusers during early withdrawal: a 31P MR spectroscopy study. Magn Reson Med 1996; 35:658-63. [PMID: 8722816 DOI: 10.1002/mrm.1910350506] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [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: 02/01/2023]
Abstract
Phosphorus magnetic resonance spectroscopy (31P MRS) at 1.5 T was performed on nine polysubstance abusing men. All nine patients met DSM-III-R criteria for concurrent cocaine and heroin dependence, were neurologically normal, were negative for the human immunodeficiency virus, and had normal clinical brain MRI scans. Patients were scanned 2-7 days after admission to a drug treatment unit. Eleven age-matched control subjects also were studied. The ISIS localized phosphorus spectra were obtained from a 5-cm thick axial brain slice and a 100-cc white matter volume. In the brain slice, the phosphorus metabolite signal expressed as a percentage of total phosphorus signal was 15% higher for phosphomonoesters, 10% lower for nucleotide triphosphates (beta-NTP), and 7% lower for total nucleotide phosphates in polydrug abusers compared with those in controls. Phosphodiesters, inorganic phosphate, phosphocreatine, total phosphorus, pH, and free magnesium concentration were unchanged. None of these parameters correlated with the methadone dose or the number of days abstinence. Single photon emission computed tomographic imaging of a subgroup of the patients revealed abnormal cerebral perfusion in 80% of the patients scanned. These data suggest that cerebral high energy phosphate and phospholipid metabolite changes result from long term drug abuse and/or withdrawal and that these changes can be detected and studied by 31P MRS.
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Affiliation(s)
- J D Christensen
- Brain Imaging Center, McLean Hospital, Belmont, Massachusetts, USA
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45
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Pedersen MR, Jensen S, Christensen JD, Hansen EW. Lipopolysaccharide in concentrations above 40 ng/ml stimulates proliferation of the IL-6-dependent B9 cell line. J Immunol Methods 1995; 180:159-63. [PMID: 7714331 DOI: 10.1016/0022-1759(94)00311-j] [Citation(s) in RCA: 8] [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: 01/26/2023]
Abstract
The B9 assay is known to be a specific and sensitive assay for the estimation of interleukin-6 activity. This assay was found to be compromised by lipopolysaccharide in concentrations > or = 40 ng lipopolysaccharide per ml. The lipopolysaccharide stimulates proliferation of the B9 cell line in a dose-dependent manner both when measuring the proliferation by thymidine incorporation and when using the MTT assay. However the LPS dose-response curve is different compared to the dose-response curve for IL-6. A sample containing 100 ng LPS/ml but no IL-6 would be estimated erroneously to contain 12 pg IL-6. The interference of lipopolysaccharide is totally abolished by the addition of polymyxin B to the samples but the addition has no effect on the IL-6 induced proliferation.
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Affiliation(s)
- M R Pedersen
- Royal Danish School of Pharmacy, Department of Biological Sciences, Copenhagen, Denmark
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46
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Boada FE, Christensen JD, Huang-Hellinger FR, Reese TG, Thulborn KR. Quantitative in vivo tissue sodium concentration maps: the effects of biexponential relaxation. Magn Reson Med 1994; 32:219-23. [PMID: 7968444 DOI: 10.1002/mrm.1910320210] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.0] [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: 01/28/2023]
Abstract
The biexponential relaxation behavior of the sodium nucleus affects the accuracy of quantitative measurement of in vivo tissue sodium concentration (TSC). Theoretical analysis and in vivo experimental results are used to demonstrate the extent of the large bias in the measured TSC that arises when the relaxation behavior in vivo differs significantly from that of the calibration standards which is when a significant fraction of the total sodium signal decays with a relaxation time much shorter than the echo time (TE) used for imaging. This bias can be as large as 20% for measurements of TSC in a normal rat brain with TE = 2 ms. Our findings indicate that shortening the echo time (TE < 0.5 ms) by projection imaging is a reliable means of obtaining accurate in vivo estimates for TSC using MR.
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Affiliation(s)
- F E Boada
- Massachusetts General Hospital NMR Center, Charlestown
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47
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Jørgensen A, Fjalland B, Christensen JD, Treiman M. Dihydropyridine ligands influence the evoked release of oxytocin and vasopressin dependent on stimulation conditions. Eur J Pharmacol 1994; 259:157-63. [PMID: 7957609 DOI: 10.1016/0014-2999(94)90505-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [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: 01/28/2023]
Abstract
The effects of dihydropyridine ligands on the electrically evoked release of neurohypophysial hormones from isolated, rat neurointermediate lobes were investigated as a function of all combinations of two pulse widths (0.2 and 2 ms) and three stimulation frequencies (6.5, 13 and 30 Hz). The dihydropyridine agonist (S)-(+)-202-791 potentiated concentration dependently the release of both oxytocin and vasopressin at a pulse width of 2 ms and a frequency of 6.5 Hz. This effect of (S)-(+)-202-791 was abolished by the antagonist (-)-nitrendipine and stereospecifically by (R)-(-)-202-791 (only vasopressin). The antagonist (R)-(-)-202-791 alone inhibited the release of oxytocin at 13 Hz and 2 ms. The results presented show that the effects of the dihydropyridine ligands are dependent on the stimulation conditions, and thus demonstrate that the entry of Ca2+ through the dihydropyridine sensitive L-type Ca2+ channel is associated with electrically evoked release of neurohypophysial hormones under certain conditions.
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Affiliation(s)
- A Jørgensen
- Department of Biological Sciences, Royal Danish School of Pharmacy, Copenhagen
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48
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Pedersen MR, Hansen EW, Christensen JD. Detection of lipopolysaccharide in the picogram range of tissue culture media by a kinetic chromogenic Limulus amebocyte lysate assay. J Clin Pharm Ther 1994; 19:189-94. [PMID: 7962222 DOI: 10.1111/j.1365-2710.1994.tb00671.x] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A kinetic chromogenic Limulus amebocyte lysate assay for detection of lipopolysaccharide in the picogram range is described. The kinetic Limulus assay was used to detect lipopolysaccharide in a tissue culture media containing interfering low-molecular-weight substances. The interfering substances were removed by ultrafiltration. The recovery of lipopolysaccharide from the ultrafiltrated tissue culture media was 61.6 +/- 21.4%. The kinetic Limulus assay was compared with the traditional end-point chromogenic Limulus assay. The results in the two assays showed a good correlation. The detection limit was 1 pg/ml in the chromogenic assay and 0.25 pg/ml in the kinetic assay.
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Affiliation(s)
- M R Pedersen
- Royal Danish School of Pharmacy, Department of Biological Sciences, Copenhagen
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49
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Affiliation(s)
- A Jørgensen
- Department of Biology, Royal Danish School of Pharmacy, Copenhagen
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50
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Affiliation(s)
- E W Hansen
- Department of Biological Sciences, Royal Danish School of Pharmacy, Copenhagen
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