1
|
Cross TJ, Isautier JMJ, Kelley EF, Hubbard CD, Morris SJ, Smith JR, Duke JW. A Systematic Review of Methods Used to Determine the Work of Breathing during Exercise. Med Sci Sports Exerc 2023; 55:1672-1682. [PMID: 37126027 DOI: 10.1249/mss.0000000000003187] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
INTRODUCTION Measurement of the work of breathing (Wb) during exercise provides useful insights into the energetics and mechanics of the respiratory muscles across a wide range of minute ventilations. The methods and analytical procedures used to calculate the Wb during exercise have yet to be critically appraised in the literature. PURPOSE The aim of this systematic review was to evaluate the quality of methods used to measure the Wb during exercise in the available literature. METHODS We conducted an extensive search of three databases for studies that measured the Wb during exercise in adult humans. Data were extracted on participant characteristics, flow/volume and pressure devices, esophageal pressure (P oes ) catheters, and methods of Wb analysis. RESULTS A total of 120 articles were included. Flow/volume sensors used were primarily pneumotachographs ( n = 85, 70.8%), whereas the most common pressure transducer was of the variable reluctance type ( n = 63, 52.5%). Esophageal pressure was frequently obtained via balloon-tipped catheters ( n = 114, 95.0%). Few studies mentioned calibration, frequency responses, and dynamic compensation of their measurement devices. The most popular method of measuring the Wb was pressure-volume integration ( n = 51, 42.5%), followed by the modified Campbell ( n = 28, 23.3%) and Dean & Visscher diagrams ( n = 26, 21.7%). Over one-third of studies did not report the methods used to process their pressure-volume data, and the majority (60.8%) of studies used the incorrect Wb units and/or failed to discuss the limitations of their Wb measurements. CONCLUSIONS The findings of this systematic review highlight the need for the development of a standardized approach for measuring Wb, which is informative, practical, and accessible for future researchers.
Collapse
Affiliation(s)
- Troy J Cross
- Faculty of Medicine and Health, University of Sydney, NSW, AUSTRALIA
| | | | - Eli F Kelley
- Air Force Research Laboratory, 711HPW/RHBFP, Wright-Patterson Air Force Base, OH
| | - Colin D Hubbard
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ
| | - Sarah J Morris
- Faculty of Medicine and Health, University of Sydney, NSW, AUSTRALIA
| | - Joshua R Smith
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | - Joseph W Duke
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ
| |
Collapse
|
2
|
Morris SJ, Hubbard CD, Erram JS, Smith J, Kelley E, Duke JW, Cross TJ. Methodological Quality Of The Work Of Breathing During Exercise: A Systematic Review. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000878508.61830.21] [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: 11/21/2022]
|
3
|
Cross TJ, Isautier JMJ, Morris SJ, Johnson BD, Wheatley-Guy CM, Taylor BJ. The Influence of Social Distancing Behaviors and Psychosocial Factors on Physical Activity During the COVID-19 Pandemic: Cross-sectional Survey Study. JMIR Public Health Surveill 2021; 7:e31278. [PMID: 34509976 PMCID: PMC8477911 DOI: 10.2196/31278] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 08/16/2021] [Accepted: 08/16/2021] [Indexed: 12/26/2022] Open
Abstract
Background The COVID-19 pandemic has arguably facilitated a shift toward increased sedentariness and reduced physical activity. Moreover, there is mounting evidence that mental health has also declined during the pandemic. However, it remains unknown to what extent social distancing (SD) behaviors and mental health have affected the physical activity levels of the general population. Objective The purpose of this study was to determine the influence of SD behaviors and prevailing mental health on the odds of being physically active during the early COVID-19 pandemic response. Methods A total of 4819 adults (2474/4819, 51.3%, female) from the US population with a median age of 46 (IQR 35-59) completed an online survey during the early pandemic response (April-June 2020). The survey included questions on adherence to 11 SD behaviors, and validated questionnaires which assessed self-reported physical activity, depression, anxiety, and mental well-being. Respondents were categorized into 2 physical activity groups: inactive (0-599 metabolic equivalent of task [MET]-minutes/week) and active (≥600 MET-minutes/week). A logistic generalized additive model (GAM) was used to determine which SD factors and mental health outcomes were associated with physical activity level. Results The GAM analysis revealed that wearing a facemask in public (odds ratio [OR] 1.46, 95% CI 1.14-1.79; P=.003), limiting the use of public transport (OR 1.47, 95% CI 1.19-1.83; P=.001), and restricting travel outside the house (OR 1.56, 95% CI 1.19-2.05; P=.002) were SD behaviors associated with higher odds of being more physically active. Conversely, avoiding physical activity outside the house was associated with higher odds of being inactive (OR 0.52, 95% CI 0.46-0.63; P<.001). Leaving the house more frequently, and a higher mental well-being were associated with increasing odds of being physically active (P<.001). Engaging with a moderate number of SD behaviors (3-7 total) was positively associated with physical activity, whereas a very high SD vigilance (ie, engaging with ≥10 total behaviors) decreased the odds of being active during the early pandemic response. Conclusions Based on the findings of our study, we suggest that future public health messaging of SD guidelines should include (1) a clear portrayal of the benefits of regular exercise on mental health; and (2) a specific focus on how to be physically active outdoors in a COVID-safe manner.
Collapse
Affiliation(s)
- Troy J Cross
- Sydney School of Health Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, Australia.,Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States
| | - Jennifer M J Isautier
- Sydney School of Health Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, Australia.,Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States
| | - Sarah J Morris
- Sydney School of Health Sciences, Faculty of Medicine and Health, The University of Sydney, Camperdown, Australia
| | - Bruce D Johnson
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, United States
| | | | - Bryan J Taylor
- Department of Cardiovascular Diseases, Mayo Clinic, Jacksonville, FL, United States
| |
Collapse
|
4
|
Cross TJ, Gideon EA, Morris SJ, Coriell CL, Hubbard CD, Duke JW. A comparison of methods used to quantify the work of breathing during exercise. J Appl Physiol (1985) 2021; 131:1123-1133. [PMID: 34410846 DOI: 10.1152/japplphysiol.00411.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mechanical work of breathing (Wb) is an insightful tool used to assess respiratory mechanics during exercise. There are several different methods used to calculate the Wb, however, each approach having its own distinct advantages/disadvantages. To date, a comprehensive assessment of the differences in the components of Wb between these methods is lacking. We therefore sought to compare the values of Wb during graded exercise as determined via the four most popular methods: 1) pressure-volume integration; 2) the Hedstrand diagram; 3) the Otis diagram; and the 4) modified Campbell diagram. Forty-two participants (30 ± 15 yr; 16 women) performed graded cycling to volitional exhaustion. Esophageal pressure-volume loops were obtained throughout exercise. These data were used to calculate the total Wb and, where possible, its subcomponents of inspiratory and expiratory, resistive and elastic Wb, using each of the four methods. Our results demonstrate that the components of Wb were indeed different between methods across the minute ventilations engendered by graded exercise. Importantly, however, no systematic pattern in these differences could be observed. Our findings indicate that the values of Wb obtained during exercise are uniquely determined by the specific method chosen to compute its value-no two methods yield identical results. Because there is currently no "gold-standard" for measuring the Wb, it is emphasized that future investigators be cognizant of the limitations incurred by their chosen method, such that observations made by others may be interpreted with greater context, and transparency.NEW & NOTEWORTHY The measurement of the work of breathing (Wb) during exercise provides us with deep insights into respiratory (patho)physiology, and sheds light on the putative factors which lead to respiratory muscle fatigue. There are 4 popular methods available to determine the Wb. Our study demonstrates that no two of these methods produce identical values of Wb during exercise. This paper also discusses the practical and theoretical limitations of each method.
Collapse
Affiliation(s)
- Troy J Cross
- Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia.,Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
| | - Elizabeth A Gideon
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
| | - Sarah J Morris
- Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
| | - Catherine L Coriell
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
| | - Colin D Hubbard
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
| | - Joseph W Duke
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
| |
Collapse
|
5
|
Cross TJ, Isautier JMJ, Ziegler BL, Morris SJ, Johnson BD, Wheatley C, Taylor BJ. The Paws Project: The Impact Of Social Distancing On Physical Activity During The COVID-19 Pandemic. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000761284.70164.d8] [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: 11/21/2022]
|
6
|
Cross TJ, Isautier JMJ, Ziegler BL, Morris SJ, Johnson BD, Taylor BJ, Wheatley C. The Paws Project: Changes In Physical Activity And Mental Health During The COVID-19 Pandemic. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000761280.27443.1b] [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: 11/21/2022]
|
7
|
Chapple KS, Morris SJ. Sacral nerve stimulation in patients with slow transit constipation. Tech Coloproctol 2019; 23:1181-1182. [PMID: 31728783 DOI: 10.1007/s10151-019-02117-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 11/02/2019] [Indexed: 12/01/2022]
Affiliation(s)
- K S Chapple
- Colorectal Surgical Unit, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK.
| | - S J Morris
- Colorectal Surgical Unit, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| |
Collapse
|
8
|
Hainsworth AJ, Solanki D, Hamad A, Morris SJ, Schizas AMP, Williams AB. Integrated total pelvic floor ultrasound in pelvic floor defaecatory dysfunction. Colorectal Dis 2017; 19:O54-O65. [PMID: 27886434 DOI: 10.1111/codi.13568] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 09/30/2016] [Indexed: 02/08/2023]
Abstract
AIM Imaging for pelvic floor defaecatory dysfunction includes defaecation proctography. Integrated total pelvic floor ultrasound (transvaginal, transperineal, endoanal) may be an alternative. This study assesses ultrasound accuracy for the detection of rectocele, intussusception, enterocele and dyssynergy compared with defaecation proctography, and determines if ultrasound can predict symptoms and findings on proctography. Treatment is examined. METHOD Images of 323 women who underwent integrated total pelvic floor ultrasound and defaecation proctography between 2011 and 2014 were blindly reviewed. The size and grade of rectocele, enterocele, intussusception and dyssynergy were noted on both, using proctography as the gold standard. Barium trapping in a rectocele or a functionally significant enterocele was noted on proctography. Demographics and Obstructive Defaecation Symptom scores were collated. RESULTS The positive predictive value of ultrasound was 73% for rectocele, 79% for intussusception and 91% for enterocele. The negative predictive value for dyssynergy was 99%. Agreement was moderate for rectocele and intussusception, good for enterocele and fair for dyssynergy. The majority of rectoceles that required surgery (59/61) and caused barium trapping (85/89) were detected on ultrasound. A rectocele seen on both transvaginal and transperineal scanning was more likely to require surgery than if seen with only one mode (P = 0.0001). If there was intussusception on ultrasound the patient was more likely to have surgery (P = 0.03). An enterocele visualized on ultrasound was likely to be functionally significant on proctography (P = 0.02). There was, however, no association between findings on imaging and symptoms. CONCLUSION Integrated total pelvic floor ultrasound provides a useful screening tool for women with defaecatory dysfunction such that defaecatory imaging can avoided in some.
Collapse
Affiliation(s)
- A J Hainsworth
- The Pelvic Floor Unit, Guy's and St Thomas' Hospital, London, UK
| | - D Solanki
- The Pelvic Floor Unit, Guy's and St Thomas' Hospital, London, UK
| | - A Hamad
- The Pelvic Floor Unit, Guy's and St Thomas' Hospital, London, UK
| | - S J Morris
- The Pelvic Floor Unit, Guy's and St Thomas' Hospital, London, UK
| | - A M P Schizas
- The Pelvic Floor Unit, Guy's and St Thomas' Hospital, London, UK
| | - A B Williams
- The Pelvic Floor Unit, Guy's and St Thomas' Hospital, London, UK
| |
Collapse
|
9
|
Deng ZD, Lu J, Myjak MJ, Martinez JJ, Tian C, Morris SJ, Carlson TJ, Zhou D, Hou H. Design and implementation of a new autonomous sensor fish to support advanced hydropower development. Rev Sci Instrum 2014; 85:115001. [PMID: 25430138 DOI: 10.1063/1.4900543] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Acceleration in development of additional conventional hydropower requires tools and methods to perform laboratory and in-field validation of turbine performance and fish passage claims. The new-generation Sensor Fish has been developed with more capabilities to accommodate a wider range of users over a broader range of turbine designs and operating environments. It provides in situ measurements of three-dimensional (3D) linear accelerations, 3D rotational velocities, 3D orientation, pressure, and temperature at a sampling frequency of 2048 Hz. It also has an automatic floatation system and built-in radio-frequency transmitter for recovery. The relative errors of the pressure, acceleration, and rotational velocity were within ±2%, ±5%, and ±5%, respectively. The accuracy of orientation was within ±4° and accuracy of temperature was ±2 °C. The new-generation Sensor Fish is becoming a major technology and being deployed for evaluating the conditions for fish passage of turbines or other hydraulic structures in both the United States and several other countries.
Collapse
Affiliation(s)
- Z D Deng
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99332, USA
| | - J Lu
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99332, USA
| | - M J Myjak
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99332, USA
| | - J J Martinez
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99332, USA
| | - C Tian
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99332, USA
| | - S J Morris
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99332, USA
| | - T J Carlson
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99332, USA
| | - D Zhou
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99332, USA
| | - H Hou
- Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99332, USA
| |
Collapse
|
10
|
Turns BA, Morris SJ, Lentz NA. The Self of the Christian Therapist Doing Sex Therapy: A Model for Training Christian Sex Therapists. Sexual and Relationship Therapy 2013. [DOI: 10.1080/14681994.2013.765557] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
11
|
Thompson AS, Morris SJ, Thurston DE. Synthesis of Tomanthramycin, A Novel Pyrrolo {2,1-C}{1,4}Benzo Diazepine Hybrid of Anthramycin and Tomaymycin. J Pharm Pharmacol 2011. [DOI: 10.1111/j.2042-7158.1990.tb14417.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- AS Thompson
- School of Pharmacy, Portsmouth Polytechnic PO1 2DZ
| | - SJ Morris
- School of Pharmacy, Portsmouth Polytechnic PO1 2DZ
| | - DE Thurston
- School of Pharmacy, Portsmouth Polytechnic PO1 2DZ
| |
Collapse
|
12
|
Morris SJ, Ali I, Turner CH, Thurston DE. An Investigation of the Possible Mode of Action of Neothramycin, A Pyrrolo {2,1-C}{1,4}Benzodiazepine Antitumour Agent. J Pharm Pharmacol 2011. [DOI: 10.1111/j.2042-7158.1990.tb14416.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- SJ Morris
- School of Pharmacy, Portsmouth polytechnic, PO1 2DZ
| | - I Ali
- School of Pharmacy, Portsmouth polytechnic, PO1 2DZ
| | - CH Turner
- School of Pharmacy, Portsmouth polytechnic, PO1 2DZ
| | - DE Thurston
- School of Pharmacy, Portsmouth polytechnic, PO1 2DZ
| |
Collapse
|
13
|
Morris SJ, Südhof TC, Haynes DH. Lipid and protein interactions in ca-promoted aggregation and fusion of chromaffin granule membranes. Biophys J 2010; 37:117-8. [PMID: 19431433 DOI: 10.1016/s0006-3495(82)84629-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
14
|
de la Fuente AJM, Tucker AW, Navas J, Blanco M, Morris SJ, Gutiérrez-Martín CB. Antimicrobial susceptibility patterns of Haemophilus parasuis from pigs in the United Kingdom and Spain. Vet Microbiol 2007; 120:184-91. [PMID: 17110059 DOI: 10.1016/j.vetmic.2006.10.014] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 10/02/2006] [Accepted: 10/10/2006] [Indexed: 11/25/2022]
Abstract
A total of 30 British and 30 Spanish Haemophilus parasuis isolates were tested for their susceptibility to 19 of the antimicrobials currently used in swine practice with a broth microdilution method in order to know the emergence of resistance against these compounds in this porcine pathogen. All the British isolates were susceptible to penicillin, ceftiofur, erythromycin, tilmicosin, enrofloxacin, and florfenicol, and most of them were susceptible to the remaining antimicrobials (the highest resistance rate found was of 20% to neomycin). In contrast, all the Spanish isolates were susceptible exclusively to florfenicol, and high proportions of resistance were encountered for penicillin, ampicillin, oxytetracycline, erythromycin, tilmicosin, tiamulin and trimethoprim+sulphamethoxazole; in addition, a bimodal or multimodal distribution, or tailing of Spanish isolates over the MIC range was observed for clindamycin, sulphonamides and tylosine tartrate, suggesting the development of acquired resistance. In addition, several multiresistance patterns were found among the Spanish isolates, 23.3% of them being resistant to at least eight antimicrobials, the same rate as that encountered for those being susceptible to all antimicrobials tested. This study showed that in general British H. parasuis isolates are susceptible to antimicrobial agents routinely used for treatment of porcine respiratory diseases; however, the Spanish isolates need a more continuous surveillance of their susceptibility patterns.
Collapse
Affiliation(s)
- A J Martín de la Fuente
- Departamento de Sanidad Animal, Unidad de Microbiología e Inmunología, Facultad de Veterinaria, Universidad de León, 24007 León, Spain
| | | | | | | | | | | |
Collapse
|
15
|
Nussey DH, Coltman DW, Coulson T, Kruuk LEB, Donald A, Morris SJ, Clutton-Brock TH, Pemberton J. Rapidly declining fine-scale spatial genetic structure in female red deer. Mol Ecol 2005; 14:3395-405. [PMID: 16156811 DOI: 10.1111/j.1365-294x.2005.02692.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [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: 11/30/2022]
Abstract
A growing literature now documents the presence of fine-scale genetic structure in wild vertebrate populations. Breeding population size, levels of dispersal and polygyny--all hypothesized to affect population genetic structure--are known to be influenced by ecological conditions experienced by populations. However the possibility of temporal or spatial variation in fine-scale genetic structure as a result of ecological change is rarely considered or explored. Here we investigate temporal variation in fine-scale genetic structure in a red deer population on the Isle or Rum, Scotland. We document extremely fine-scale spatial genetic structure (< 100 m) amongst females but not males across a 24-year study period during which resource competition has intensified and the population has reached habitat carrying capacity. Based on census data, adult deer were allocated to one of three subpopulations in each year of the study. Global F(ST) estimates for females generated using these subpopulations decreased over the study period, indicating a rapid decline in fine-scale genetic structure of the population. Global F(ST) estimates for males were not different from zero across the study period. Using census and genetic data, we illustrate that, as a consequence of a release from culling early in the study period, the number of breeding females has increased while levels of polygyny have decreased in this population. We found little evidence for increasing dispersal between subpopulations over time in either sex. We argue that both increasing female population size and decreasing polygyny could explain the decline in female population genetic structure.
Collapse
Affiliation(s)
- D H Nussey
- Institute of Evolutionary Biology, University of Edinburgh, EH9 3JT, UK.
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Abstract
BACKGROUND The aim of this study was to assess whether a noninvasive imaging technique such as ultrasound could visualize an epidural catheter in the epidural space in children. METHODS Following local ethics committee approval and informed parental consent a pilot study of 12 cases was performed. Children undergoing major surgery requiring epidural analgesia were recruited. All catheters were introduced via the lumbar region. All children were scanned within 24 h of epidural insertion by consultant paediatric radiologists. If the catheter was identified in the epidural space then an attempt was made to visualize the entire length of the catheter. RESULTS The epidural catheter was detected in nine of 12 patients. All of these were less than 6 months old. The entire length of the catheter was visualized in five of the nine patients. It was possible to estimate the most cephalad level of the catheter in seven of the nine patients. This was in the thoracic region in all cases and an appropriate level for the intended surgical procedure. It was not possible to precisely identify the tip of the catheter as a distinct entity using ultrasound. CONCLUSION This study shows that it is possible to visualize an epidural catheter in the epidural space in children under 6 months of age using ultrasound.
Collapse
Affiliation(s)
- M S Chawathe
- Department of Anaesthesia, University Hospital of Wales, Heath Park, Cardiff, UK.
| | | | | | | | | | | |
Collapse
|
17
|
Abstract
We compared the outcome of children with empyema managed either through thoracotomy with pleural debridment, conventional stiff chest drain, or pigtail chest drain. Compared to conventional drain, children who received either thoracotomy or pigtail catheters had a significantly decreased period of drain in situ, were afebrile earlier, were clinically improved earlier, and were discharged earlier.
Collapse
Affiliation(s)
- M J Pierrepoint
- Cystic Fibrosis/Respiratory Unit, Department of Child Health, University Hospital of Wales, Cardiff, UK
| | | | | | | | | |
Collapse
|
18
|
Morris SJ, Smith H, Sweet C. Exploitation of the Herpes simplex virus translocating protein VP22 to carry influenza virus proteins into cells for studies of apoptosis: direct confirmation that neuraminidase induces apoptosis and indications that other proteins may have a role. Arch Virol 2002; 147:961-79. [PMID: 12021867 DOI: 10.1007/s00705-001-0779-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [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: 11/25/2022]
Abstract
Previously, we have shown that apoptosis induced by influenza virus was inhibited by an anti-neuraminidase compound [4-guanidino-2, 3-dehydro-N-acetylneuraminic acid (GG167; Relenza; Zanamivir)], which does not enter cells, and acts at the attachment/entry phase of virus replication. Furthermore, a virulent virus, clone 7a, induced greater levels of apoptosis than the attenuated A/Fiji and had greater neuraminidase (NA) activity. To confirm more directly that NA induces apoptosis, the NA of clone 7a and A/Fiji was expressed fused to the Herpes simplex virus tegument coat protein VP22, transfected into HeLa cells and the level of apoptosis determined. VP22 translocates between cells via the medium thus allowing expressed proteins to transfer to a larger number of cells than those originally transfected. Clone 7a NA fused to VP22 induced a significant level of apoptosis whereas A/Fiji NA/VP22 did not, confirming that NA activity is an important determinant of apoptosis acting during fusion protein translocation between cells. Furthermore, the induction of apoptosis was abrogated by antibody to transforming growth factor-beta, which is activated by NA. This approach also showed that VP22/NS1 proteins of both clone 7a and A/Fiji induced apoptosis when expressed alone but inhibited double stranded RNA-induced apoptosis suggesting that this protein may have a dual mode of action. Also, the M1 and M2 proteins of both viruses induced apoptosis but their NP proteins did not.
Collapse
Affiliation(s)
- S J Morris
- School of Biosciences, The University of Birmingham, Edgbaston, Birmingham, UK
| | | | | |
Collapse
|
19
|
|
20
|
Abstract
Primary malignant rhabdoid tumour of the central nervous system is a rare neoplasm affecting children. We present a pathologically proven case, which was initially referred to the paediatric surgeons as a sebaceous cyst, and highlights the importance of imaging prior to surgery of potentially innocuous scalp lesions. Imaging features on CT and MRI are presented, which show bony involvement not previously reported in the literature.
Collapse
Affiliation(s)
- A Evans
- Department of Radiology, University Hospital of Wales, Heath, Cardiff CFI4 4XN, UK
| | | | | |
Collapse
|
21
|
Bertrand S, Ng GY, Purisai MG, Wolfe SE, Severidt MW, Nouel D, Robitaille R, Low MJ, O'Neill GP, Metters K, Lacaille JC, Chronwall BM, Morris SJ. The anticonvulsant, antihyperalgesic agent gabapentin is an agonist at brain gamma-aminobutyric acid type B receptors negatively coupled to voltage-dependent calcium channels. J Pharmacol Exp Ther 2001; 298:15-24. [PMID: 11408520] [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: 02/20/2023] Open
Abstract
Gabapentin (Neurontin, Pfizer Global R & D) is a novel anticonvulsant, antihyperalgesic, and antinociceptive agent with a poorly understood mechanism of action. In this study, we show that gabapentin (EC50 2 microM) inhibited up to 70 to 80% of the total K+-evoked Ca2+ influx via voltage-dependent calcium channels (VD-CCs) in a mouse pituitary intermediate melanotrope clonal mIL-tsA58 (mIL) cell line. mIL cells endogenously express only gamma-aminobutyric acid type B (GABA(B)) gb1a-gb2 receptors. Moreover, activity of the agonist gabapentin was dose dependently and completely blocked with the GABA(B) antagonist CGP55845 and was nearly identical to the prototypic GABA(B) agonist baclofen in both extent and potency. Antisense knockdown of gb1a also completely blocked gabapentin activity, while gb1b antisense and control oligonucleotides had no effect, indicating that gabapentin inhibition of membrane Ca2+ mobilization in mIL cells was dependent on a functional GABA(B) (gb1a-gb2) heterodimer receptor. In addition, during combined whole cell recording and multiphoton Ca2+ imaging in hippocampal neurons in situ, gabapentin significantly inhibited in a dose-dependent manner subthreshold soma depolarizations and Ca2+ responses evoked by somatic current injection. Furthermore, gabapentin almost completely blocked Ca2+ action potentials and Ca2+ responses elicited by suprathreshold current injection. However, larger current injection overcame this inhibition of Ca2+ action potentials suggesting that gabapentin did not predominantly affect L-type Ca2+ channels. The depressant effect of gabapentin on Ca2+ responses was coupled to the activation of neuronal GABA(B) receptors since they were blocked by CGP55845, and baclofen produced similar effects. Thus gabapentin activation of neuronal GABA(B) gb1a-gb2 receptors negatively coupled to VD-CCs can be a potentially important therapeutic mechanism of action of gabapentin that may be linked to inhibition of neurotransmitter release in some systems.
Collapse
Affiliation(s)
- S Bertrand
- Centre de Recherche en Sciences Neurologiques et Département de Physiologie, Université de Montréal, Montréal, Province of Québec, Canada
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Chronwall BM, Davis TD, Severidt MW, Wolfe SE, McCarson KE, Beatty DM, Low MJ, Morris SJ, Enna SJ. Constitutive expression of functional GABA(B) receptors in mIL-tsA58 cells requires both GABA(B(1)) and GABA(B(2)) genes. J Neurochem 2001; 77:1237-47. [PMID: 11389174 DOI: 10.1046/j.1471-4159.2001.00323.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [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: 11/20/2022]
Abstract
Studies of gamma-aminobutyric acid (GABA)(B) receptor function in heterologous cell systems have suggested that expression of two distinct seven transmembrane G-protein coupled receptor subunits is necessary for receptor activation and signal transduction. Some results suggest that both receptor proteins must be inserted into the plasma membrane to create heterodimers; however, it is possible that subunit monomers or homodimers are functional in cells which constitutively express GABA(B) receptors. A new pituitary intermediate lobe melanotrope cell clone (mIL tsA58) has been isolated which constitutively expresses GABA(B), D(2) and corticotrophin releasing factor receptors. Here, we report on characterization of the GABA(B) receptors. Solution hybridization-nuclease protection assays reveal the presence of GABA(B(1)) and GABA(B(2)) transcripts. Western blots show GABA(B(1a)) and one of two GABA(B(2)) proteins. Addition of the GABA(B) agonist baclofen to cultured mIL-tsA58 (mIL) cells inhibits high voltage activated Ca(2+) channels, as measured by agonist-induced inhibition of the K(+)-depolarization-stimulated increase in Ca(2+) influx. CGP55845, a GABA(B) antagonist, blocks the response to baclofen. Knockdown of either GABA(B(1)) or GABA(B(2)) subunits with selective antisense oligodeoxynucleotides reduced GABA(B) protein levels and completely abolished the GABA(B) receptor response in the mIL cells. Taken together, these results indicate that functionally active GABA(B) receptors in mIL cells require the constitutive expression of both GABA(B) genes. This is a physiologic validation of results from recombinant overexpression in naive cells and shows that the mIL cell line is a useful model for studying GABA(B) receptor expression, regulation and function.
Collapse
Affiliation(s)
- B M Chronwall
- School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 64110, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Mowla SJ, Farhadi HF, Pareek S, Atwal JK, Morris SJ, Seidah NG, Murphy RA. Biosynthesis and post-translational processing of the precursor to brain-derived neurotrophic factor. J Biol Chem 2001; 276:12660-6. [PMID: 11152678 DOI: 10.1074/jbc.m008104200] [Citation(s) in RCA: 402] [Impact Index Per Article: 17.5] [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: 12/25/2022] Open
Abstract
We examined the biosynthesis and post-translational processing of the brain-derived neurotrophic factor precursor (pro-BDNF) in cells infected with a pro-BDNF-encoding vaccinia virus. Metabolic labeling, immunoprecipitation, and SDS-polyacrylamide gel electrophoresis reveal that pro-BDNF is generated as a 32-kDa precursor that is N-glycosylated and glycosulfated on a site, within the pro-domain. Some pro-BDNF is released extracellularly and is biologically active as demonstrated by its ability to mediate TrkB phosphorylation. The precursor undergoes N-terminal cleavage within the trans-Golgi network and/or immature secretory vesicles to generate mature BDNF (14 kDa). Small amounts of a 28-kDa protein that is immunoprecipitated with BDNF antibodies is also evident. This protein is generated in the endoplasmic reticulum through N-terminal cleavage of pro-BDNF at the Arg-Gly-Leu-Thr(57)- downward arrow-Ser-Leu site. Cleavage is abolished when Arg(54) is changed to Ala (R54A) by in vitro mutagenesis. Blocking generation of 28-kDa BDNF has no effect on the level of mature BDNF and blocking generation of mature BDNF with alpha(1)-PDX, an inhibitor of furin-like enzymes, does not lead to accumulation of the 28-kDa form. These data suggest that 28-kDa pro-BDNF is not an obligatory intermediate in the formation of the 14-kDa form in the constitutive secretory pathway.
Collapse
Affiliation(s)
- S J Mowla
- Salk Institute, La Jolla, California 92037-1099, USA
| | | | | | | | | | | | | |
Collapse
|
24
|
Farhadi HF, Mowla SJ, Petrecca K, Morris SJ, Seidah NG, Murphy RA. Neurotrophin-3 sorts to the constitutive secretory pathway of hippocampal neurons and is diverted to the regulated secretory pathway by coexpression with brain-derived neurotrophic factor. J Neurosci 2000; 20:4059-68. [PMID: 10818141 PMCID: PMC6772649] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
Hippocampal neurons release nerve growth factor (NGF) through the constitutive secretory pathway, thus allowing the protein to be continuously available for promoting nerve cell survival. In contrast, hippocampal neurons use the regulated secretory pathway to process brain-derived neurotrophic factor (BDNF), which alters synaptic activity when released acutely from dense-core vesicles. Thus, understanding how neurons sort and deliver neurotrophins may provide clues to their functions in brain. In this study, we monitored the processing and delivery of neurotrophin-3 (NT-3). Pulse-chase studies, immunocytochemistry, and secretagogue-induced release experiments were performed on cultured hippocampal neurons and AtT-20 cells infected with vaccinia viruses encoding the NT-3 precursor (pro-NT-3). Results show that most newly synthesized NT-3 is released through the constitutive secretory pathway as a result of furin-mediated endoproteolytic cleavage of pro-NT-3 in the trans-Golgi network. Pro-NT-3 can also be diverted into the regulated secretory pathway when cells are treated with alpha1-PDX, a selective inhibitor of furin-like enzymes, or when pro-NT-3 expression is increased by transient transfection methods. In cells coinfected with viruses coding for pro-NT-3 and pro-BDNF, NT-3 is sorted into the regulated pathway, stored in secretory granules, and released in response to extracellular cues together with BDNF, apparently as a result of heterodimerization, as suggested by coimmunoprecipitation data. Taken together, these data show that sorting of the NT-3 precursor can occur in both the constitutive and regulated secretory pathways, which is consistent with NT-3 having both survival-promoting and synapse-altering functions.
Collapse
Affiliation(s)
- H F Farhadi
- Center for Neuronal Survival, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada H3A 2B4
| | | | | | | | | | | |
Collapse
|
25
|
Fawcett JP, Alonso-Vanegas MA, Morris SJ, Miller FD, Sadikot AF, Murphy RA. Evidence that brain-derived neurotrophic factor from presynaptic nerve terminals regulates the phenotype of calbindin-containing neurons in the lateral septum. J Neurosci 2000; 20:274-82. [PMID: 10627605 PMCID: PMC6774122] [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: 02/15/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF) is transported anterogradely in neurons of the CNS and can be released by activity-dependent mechanisms to regulate synaptic plasticity. However, few neural networks have been identified in which the production, transport, and effects of BDNF on postsynaptic neurons can be analyzed in detail. In this study, we have identified such a network. BDNF has been colocalized by immunocytochemistry with tyrosine hydroxylase (TH) in nerve fibers and nerve terminals within the lateral septum of rats. BDNF-containing nerve fibers terminate on a population of calbindin-containing neurons in lateral septum that contain TrkB, the high-affinity receptor for BDNF. Overexpression of BDNF in noradrenergic neurons increased levels of calbindin in septum, as well as in whole-brain lysates. Septal levels of calbindin and BDNF partially decreased after unilateral lesions of the medial forebrain bundle (MFB), induced with 6-hydroxydopamine, a treatment that abolished TH staining. These data suggest that BDNF is anterogradely transported within the MFB in catecholaminergic neurons arising from brainstem nuclei. To determine whether BDNF affects the production of calbindin in lateral septal neurons directly, we tested the effects of BDNF on cultures of septal neurons from embryonic day 16-17 rats. BDNF promoted the expression of calbindin, as well as the arborization of calbindin-containing neurons, but BDNF had no effect on cell division or survival. Together, these results suggest that BDNF, anterogradely transported in catecholaminergic neurons, regulates calbindin expression within the lateral septum.
Collapse
Affiliation(s)
- J P Fawcett
- Center for Neuronal Survival and Division of Neurosurgery, and Montreal Neurological Institute and the Department of Neurology and Neurosurgery, McGill University, Montreal, Quebec, Canada H3A 2B4
| | | | | | | | | | | |
Collapse
|
26
|
Wolfe SE, Morris SJ. Dopamine D2 receptor isoforms expressed in AtT20 cells differentially couple to G proteins to acutely inhibit high voltage-activated calcium channels. J Neurochem 1999; 73:2375-82. [PMID: 10582596 DOI: 10.1046/j.1471-4159.1999.0732375.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The dopamine D2 receptor belongs to the serpentine superfamily of receptors, which have seven transmembrane segments and activate G proteins. D2 receptors are known to be linked, through Galpha(o)- and Galpha(i)-containing G proteins, to several signaling pathways in neuronal and secretory cells, including inhibition of adenylyl cyclase and high voltage-activated Ca2+ channels (HVA-CCs). The dopamine D2 receptor exists in two alternatively spliced isoforms, "long" and "short" (D2L, and D2S, respectively), which have identical ligand binding sites but differ by 29 amino acids in the third intracellular loop, the proposed site for G protein interaction. This has led to the speculation that the two isoforms may interact with different G proteins. We have transfected the AtT20 cell line with either D2L (KCL line) or D2S (KCS line) to facilitate experimentation on the individual isoforms. Both lines show dopamine agonist-dependent inhibition of Q-type HVA-CCs. We combined G protein antisense knock-down studies with multiwavelength fluorescence video microscopy to measure changes in HVA-CC inhibition to investigate the possibility of differential G protein coupling to this inhibition. The initial, rapid, K+ depolarization-induced increase in intracellular Ca2+ concentration is due to influx through HVA-CCs. Our studies reveal that both D2 isoforms couple to Galpha(o) to partially inhibit this influx. However, D2L also couples to Galpha(i)3, whereas D2S couples to Galpha(i)2. These data support the hypothesis of differential coupling of D2 receptor isoforms to G proteins.
Collapse
Affiliation(s)
- S E Wolfe
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, 64110-2499, USA
| | | |
Collapse
|
27
|
Mowla SJ, Pareek S, Farhadi HF, Petrecca K, Fawcett JP, Seidah NG, Morris SJ, Sossin WS, Murphy RA. Differential sorting of nerve growth factor and brain-derived neurotrophic factor in hippocampal neurons. J Neurosci 1999; 19:2069-80. [PMID: 10066260 PMCID: PMC6782557] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Abstract
Nerve growth factor (NGF) is released through the constitutive secretory pathway from cells in peripheral tissues and nerves where it can act as a target-derived survival factor. In contrast, brain-derived neurotrophic factor (BDNF) appears to be processed in the regulated secretory pathway of brain neurons and secreted in an activity-dependent manner to play a role in synaptic plasticity. To determine whether sorting differences are intrinsic to the neurotrophins or reflect differences between cell types, we compared NGF and BDNF processing in cultured hippocampal neurons using a Vaccinia virus expression system. Three independent criteria (retention or release from cells after pulse-chase labeling, depolarization-dependent release, and immunocytochemical localization) suggest that the bulk of newly synthesized NGF is sorted into the constitutive pathway, whereas BDNF is primarily sorted into the regulated secretory pathway. Similar results occurred with AtT 20 cells, including those transfected with cDNAs encoding neurotrophin precursor-green fluorescent protein fusions. The NGF precursor, but not the BDNF precursor, is efficiently cleaved by the endoprotease furin in the trans-Golgi network (TGN). Blocking furin activity in AtT 20 cells with alpha1-PDX as well as increasing the expression of NGF precursor partially directed NGF into the regulated secretory pathway. Therefore, neurotrophins can be sorted into either the constitutive or regulated secretory pathways, and sorting may be regulated by the efficiency of furin cleavage in the TGN. This mechanism may explain how neuron-generated neurotrophins can act both as survival factors and as neuropeptides.
Collapse
Affiliation(s)
- S J Mowla
- Centre for Neuronal Survival, McGill University, Montreal, Quebec, Canada H3A 2B4
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Wolfe SE, Howard DE, Schetz JA, Cheng CJ, Webber R, Beatty DM, Chronwall BM, Morris SJ. Dopamine D2-receptor isoforms expressed in AtT20 cells inhibit Q-type high-voltage-activated Ca2+ channels via a membrane-delimited pathway. J Neurochem 1999; 72:479-90. [PMID: 9930719 DOI: 10.1046/j.1471-4159.1999.0720479.x] [Citation(s) in RCA: 11] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dopamine D2 receptors both acutely and chronically inhibit high-voltage-activated Ca2+ channels (HVA-CCs). Two alternatively spliced isoforms, D2L (long) and D2S (short), are expressed at high levels in rat pituitary intermediate lobe melanotropes but are lacking in anterior lobe corticotropes. We stably transfected D2L and D2S into corticotrope-derived AtT20 cells. Both isoforms coupled to inhibition of Q-type calcium channels through pertussis toxin-sensitive G proteins. Thus, we have created a model system in which to study the kinetics of D2-receptor regulation of Ca2+ channels. Rapid inhibition of HVA-CCs was characterized using a novel fluorescence video imaging technique for the measurement of millisecond kinetic events. We measured the time elapsed (lag time) between the arrival of depolarizing isotonic 66 mM K+, sensed by fluorescence from included carboxy-X-rhodamine (CXR), and the beginning of increased intracellular Ca2+ levels (sensed by changes in indo 1 fluorescence ratio). The lag time averaged 350-550 ms, with no significant differences among cell types. Addition of the D2-agonist quinpirole (250 microM) to the K+/CXR solution significantly increased the lag times for D2-expressing cells but did not alter the lag time for AtT20 controls. The increased lag times for D2L- and D2S-transfected cells suggest that at least a fraction of the Ca2+ channels was inhibited within the initial 350-550 ms. As this inhibition time is too fast for a multistep second messenger pathway, we conclude that inhibition occurs via a membrane-delimited diffusion mechanism.
Collapse
MESH Headings
- Animals
- Binding, Competitive/physiology
- Calcium/metabolism
- Calcium Channel Blockers/pharmacology
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Calcium Channels, N-Type
- Dopamine Antagonists/pharmacology
- Dose-Response Relationship, Drug
- Electric Conductivity
- Gene Expression/physiology
- Ion Channel Gating/physiology
- Isomerism
- Male
- Melanocytes/chemistry
- Melanocytes/physiology
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Microscopy, Fluorescence
- Microscopy, Video/instrumentation
- Microscopy, Video/methods
- Nifedipine/pharmacology
- Pituitary Gland/cytology
- Potassium/pharmacology
- Rats
- Rats, Sprague-Dawley
- Reaction Time/physiology
- Receptors, Dopamine D2/chemistry
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
- Signal Transduction/physiology
- Spiperone/pharmacology
- Transfection
- Tritium
Collapse
Affiliation(s)
- S E Wolfe
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, 64110-2499, USA
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Abstract
To define the stages in influenza haemagglutinin (HA)-mediated fusion the kinetics of fusion between cell pairs consisting of single influenza HA-expressing cells and single erythrocytes (RBC) which had been labelled with both a fluorescent lipid (Dil) in the membrane and a fluorescent solute (calcein) in the aqueous space have been monitored. It is shown that release of solute from the target cell occurs, following the formation of the hemi-fusion diaphragm. These results are discussed in terms of a model in which fusion peptide insertion into the target membrane induces lipid stalks, which results in the formation of a hemifusion diaphragm and a fusion pore. Bilayer expansion due to overproduction of these stalks can give rise to collateral damage of target membranes.
Collapse
Affiliation(s)
- R Blumenthal
- Laboratory of Experimental and Computational Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | | |
Collapse
|
30
|
Abstract
The virulent influenza virus clone 7a produced a greater level of apoptosis in MDCK cells compared with the attenuated strain A/Fiji. In both cases, apoptosis could be partially blocked by treatment with three anti-neuraminidase compounds [4-amino-(GR121158A) and 4-guanidino- (GG167; Zanamivir) 2,3-dehydro-N-acetylneuraminic acid and 2,3-dehydro-2-deoxy-N-acetylneuraminic acid (DANA)] when they were given to cells during the virus attachment/entry phase, but not subsequent to this phase. In contrast, GG167, which does not enter cells, did not affect the numbers of infected cells and, in addition, acted late in the infection cycle to inhibit virus yields. Clone 7a neuraminidase was more active than A/Fiji neuraminidase when fetuin was used as the substrate. Similar differences in activity between the two viruses were seen when alpha-2,6 sialyl lactose was used as a substrate, but not with alpha-2,3 sialyl lactose. No sequence differences in the enzyme active site of the two neuraminidases were observed, indicating that differences in neuraminidase specificity and activity may be dictated by other residues. These results suggest that neuraminidase plays some role in the induction of apoptosis and that it acts prior to or during virus entry. However, apoptosis was considerably reduced when UV-irradiated virus, which retains >75% of its neuraminidase activity, was used. In addition, ammonium chloride, used to prevent virus entry, reduced virus-induced apoptosis. Amantadine, which inhibits virus uncoating, also inhibited apoptosis induced by the amantadine-sensitive strain A/Udorn/307/72 (H3N2), but not the amantadine-resistant clone 7a. Hence, one or more intracellular processes are also involved in influenza virus-induced apoptosis.
Collapse
|
31
|
Albert PR, Morris SJ, Ghahremani MH, Storring JM, Lembo PM. A putative alpha-helical G beta gamma-coupling domain in the second intracellular loop of the 5-HT1A receptor. Ann N Y Acad Sci 1998; 861:146-61. [PMID: 9928252 DOI: 10.1111/j.1749-6632.1998.tb10186.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [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: 11/30/2022]
Abstract
We have identified a conserved threonine residue in the second intracellular (i2) loop of the 5-HT1A receptor that when mutated to alanine prevents coupling to G beta gamma-mediated signaling, while preserving G alpha i-induced actions. In this review, we investigate the characteristics and potential role of the i2 domain in the coupling of the 5-HT1A receptor and other receptors to G proteins. The i2 domain, as well as portions of the i3 domain, is predicted to form an amphipathic alpha-helix with a positively charged face and a hydrophobic face. Mutagenesis experiments support a model in which the hydrophobic faces of these alpha-helical domains form an intracellular binding "pocket" for interaction with G proteins. Embedded in the hydrophobic face, Thr 149 is crucial for signaling through G beta gamma subunits, perhaps via interaction with its hydroxyl side-chain. Mutation of other residues of the i2 domain of Gi-coupled receptors is required to substantiate the importance of the alpha-helical i2 domain in receptor-G beta gamma signaling. If confirmed in other receptors, these results support a general model in which activated receptor and G beta gamma subunits remain associated to interact with effectors in a receptor-specific manner.
Collapse
Affiliation(s)
- P R Albert
- Department of Medicine, University of Ottawa, Canada.
| | | | | | | | | |
Collapse
|
32
|
Saucier C, Morris SJ, Albert PR. Endogenous serotonin-2A and -2C receptors in Balb/c-3T3 cells revealed in serotonin-free medium: desensitization and down-regulation by serotonin. Biochem Pharmacol 1998; 56:1347-57. [PMID: 9825734 DOI: 10.1016/s0006-2952(98)00244-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [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: 10/16/2022]
Abstract
We studied the endogenous expression of the serotonin-2A (5-hydroxytryptamine2A, 5-HT2A) 5-HT2C, and a splice-variant of the 5-HT2C receptor in murine Balb/c-3T3 fibroblast cells that is revealed when these cells are maintained in medium containing 5-HT-free serum. RNA editing of the 5-HT2C receptor was exclusively at a single brain-specific site. Addition of 5-HT (EC50 = 23 +/- 2.9 nM) induced an immediate release of calcium from an ionomycin-sensitive intracellular store by coupling to a pertussis toxin-insensitive pathway. The 5-HT-induced calcium mobilization displayed a 5-HT-2-like pharmacology, and ligand binding analyses indicated the presence of specific binding sites (27.5 +/- 2 fmol/mg protein) with a 5-HT2A-like pharmacology. Although the 5-HT2A receptor site was predominant, the smaller component of 5-HT2C receptors alone was sufficient to mediate a maximal calcium response. The 5-HT-induced increase in [Ca2+]i was reversibly inhibited by >75% following a 12-hr pretreatment (T1/2 = 2 hr) with 5-HT (EC50 = 400 nM). Extended treatment (24-96 hr) with 5-HT induced a complete functional desensitization that was associated with a partial (60%) reduction in 5-HT2 receptor number, implicating both receptor down-regulation and post-receptor mechanisms in 5-HT-induced desensitization. Long-term (hours to days) treatment with 5-HT did not modulate DNA synthesis, cell proliferation, or transformation in Balb/c-3T3 cells. These results demonstrate that Balb/c-3T3 cells express endogenous 5-HT2 receptors that are desensitized by the 5-HT present in normal serum, illustrating the importance of growth conditions in the identification of receptor responsiveness. The lack of proliferative response to 5-HT in Balb/c-3T3 suggests a putative role of desensitization as a "safety valve" to prevent abnormal cell growth during sustained 5-HT2 receptor activation.
Collapse
Affiliation(s)
- C Saucier
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | | | | |
Collapse
|
33
|
Morris SJ, Beatty DM, Chronwall BM. GABA(B)R1a/R1b-type receptor antisense deoxynucleotide treatment of melanotropes blocks chronic GABA(B) receptor inhibition of high voltage-activated Ca2+ channels. J Neurochem 1998; 71:1329-32. [PMID: 9721761 DOI: 10.1046/j.1471-4159.1998.71031329.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: 11/20/2022]
Abstract
GABA(B) and dopamine D2 receptors, both of which acutely inhibit adenylyl cyclase and high voltage-activated Ca2+ channels (HVA-CCs), are found in high levels in the melanotrope cells of the pituitary intermediate lobe. Chronic D2 receptor agonist application in vitro has been reported to result in inhibition of HVA-CC activity by down-regulation. Here we report that chronic GABA(B), but not GABA(A), agonist treatment also resulted in HVA-CC inhibition. Two GABA(B) receptor variants have been cloned and shown to inhibit adenylyl cyclase in HEK-293 cells. We have constructed an antisense deoxynucleotide knockdown-type probe that is complementary to 18 bp from the point at which the two sequences first become homologous. Chronic coincubation with baclofen and GABA(B) antisense nucleotide completely eliminated the inhibition of the channels by baclofen alone but had no reversing effect on HVA-CC inhibition by the D2 agonist quinpirole. A scrambled, missense nucleotide also had no reversing effect. Incubation with a D2 antisense knockdown probe eliminated the ability of a D2 agonist to inhibit the channels but had no effect on baclofen blockade. These results show the existence an R1a/R1b type of GABA(B) receptor, which, like the D2 receptor, is coupled to chronic HVA-CC inhibition in melanotropes.
Collapse
Affiliation(s)
- S J Morris
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, 64110-2499, USA
| | | | | |
Collapse
|
34
|
Yoshizawa K, Willett WC, Morris SJ, Stampfer MJ, Spiegelman D, Rimm EB, Giovannucci E. Study of prediagnostic selenium level in toenails and the risk of advanced prostate cancer. J Natl Cancer Inst 1998; 90:1219-24. [PMID: 9719083 DOI: 10.1093/jnci/90.16.1219] [Citation(s) in RCA: 399] [Impact Index Per Article: 15.3] [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: 11/13/2022] Open
Abstract
BACKGROUND In a recent randomized intervention trial, the risk of prostate cancer for men receiving a daily supplement of 200 microg selenium was one third of that for men receiving placebo. By use of a nested case-control design within a prospective study, i.e., the Health Professionals Follow-Up Study, we investigated the association between risk of prostate cancer and prediagnostic level of selenium in toenails, a measure of long-term selenium intake. METHODS In 1986, 51,529 male health professionals aged 40-75 years responded to a mailed questionnaire to form the prospective study. In 1987, 33,737 cohort members provided toenail clippings. In 1988, 1990, 1992, and 1994, follow-up questionnaires were mailed. From 1989 through 1994, 181 new cases of advanced prostate cancer were reported. Case and control subjects were matched by age, smoking status, and month of toenail return. Selenium levels were determined by neutron activation. All P values are two-sided. RESULTS The selenium level in toenails varied substantially among men, with quintile medians ranging from 0.66 to 1.14 microg/g for control subjects. When matched case-control data were analyzed, higher selenium levels were associated with a reduced risk of advanced prostate cancer (odds ratio [OR] for comparison of highest to lowest quintile = 0.49; 95% confidence interval [CI] = 0.25-0.96; P for trend = .11). After additionally controlling for family history of prostate cancer, body mass index, calcium intake, lycopene intake, saturated fat intake, vasectomy, and geographical region, the OR was 0.35 (95% CI = 0.16-0.78; P for trend = .03). CONCLUSIONS Our results support earlier findings that higher selenium intakes may reduce the risk of prostate cancer. Further prospective studies and randomized trials of this relationship should be conducted.
Collapse
Affiliation(s)
- K Yoshizawa
- Department of Nutrition, Harvard School of Public Health, Boston, MA, USA
| | | | | | | | | | | | | |
Collapse
|
35
|
Albert PR, Morris SJ. Selective antagonism of receptor signaling using antisense RNA to deplete G-protein subunits. Methods Mol Biol 1998; 84:107-22. [PMID: 9666444 DOI: 10.1385/0-89603-488-7:107] [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: 02/08/2023]
Affiliation(s)
- P R Albert
- Neuroscience Research Institute, University of Ottawa, Canada
| | | |
Collapse
|
36
|
Abstract
Insoluble aggregates of the amyloid beta-peptide (A beta) is a major constituent of senile plaques found in brains of Alzheimer disease (AD) patients. The detrimental effects of aggregated A beta is associated with an increased intracellular Ca2+ concentration ([Ca2+]i). We examined the effects of A beta(25-35) on [Ca2+]i and intracellular H+ concentration ([H+]i) in single hippocampal neurons by real time fluorescence imaging using the Ca(2+)- and H(+)-specific ratio dyes, indo-1 and SNARF-1. Incubation of these cultures with A beta(25-35) for 3-12 days in vitro increased [Ca2+]i and [H+]i in large, NMDA-responsive neurons.
Collapse
Affiliation(s)
- H S Mogensen
- Department of Pharmacology, University of Copenhagen, Denmark
| | | | | | | |
Collapse
|
37
|
Chronwall BM, Sands SA, Cummings KC, Hagler KE, Norberg M, Morris SJ, Gary KA. Differential innervation of individual melanotropes suggests a role for nonsynaptic inhibitory regulation of the developing and adult rat pituitary intermediate lobe. Synapse 1998; 28:227-43. [PMID: 9488508 DOI: 10.1002/(sici)1098-2396(199803)28:3<227::aid-syn6>3.0.co;2-c] [Citation(s) in RCA: 9] [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: 02/06/2023]
Abstract
Dopamine and GABA were detected in intermediate lobe axons around birth, and early axons were closely apposed to glial cells and processes, possibly using them for guidance. In the adult, axons containing colocalized dopamine and GABA were distributed in a distinct pattern within the lobe, with plexuses located dorsally and ventrally. Axons preferentially followed glial processes in interlobular septa, yet were also interspersed between melanotropes. Individual melanotropes were contacted by varying numbers of axon terminals, with some devoid of contacts. Boutons contained both small clear vesicles and large dense-cored vesicles; membrane specializations were not well-developed. From these findings we concluded that in addition to direct synaptic inhibition, dopamine and GABA could stimulate their receptors by mechanisms similar to "parasynaptic" [Schmitt (1984) Neuroscience, 13:991-1001] or "volume" [Agnati et al. (1995) Neuroscience, 69:711-726] transmission as proposed for the CNS. Humoral agents passing into the intermediate lobe from portal vessels, thus acting as classical hormones, further regulate the melanotropes. Moreover, approximately 50% of the axonal elements were closely apposed to glia, suggesting that glia could have regulatory roles. Previous studies from our laboratory [Chronwall et al. (1987) Endocrinology, 120:1201-1211; Chronwall et al. (1988) Endocrinology, 123:1992:1202] demonstrated heterogeneity in proopiomelanocortin (POMC) biosynthesis among individual melanotropes, prompting the hypothesis that the degree of innervation could govern the expression of certain molecules. We combined immunohistochemistry and in situ hybridization histochemistry to evaluate whether melanotrope molecular heterogenity is spatially correlated with axons and terminals. Tentatively, melanotropes expressing low levels of POMC and alpha1A subunit P/Q type Ca2+ channel mRNAs often were apposed to axons, whereas those with low levels of D2L receptor mRNA rarely were contacted by axons, suggesting that innervation could be one of the factors inducing and maintaining heterogeneity.
Collapse
Affiliation(s)
- B M Chronwall
- School of Biological Sciences, University of Missouri-Kansas City 64108, USA.
| | | | | | | | | | | | | |
Collapse
|
38
|
Abstract
The biosynthetic activity of rat intermediate lobe melanotropes in vivo is inhibited by stimulation of dopamine D2 receptors. Individual melanotropes are innervated differentially by dopaminergic axons and vary in their levels of pro-opiomelanocortin (POMC) mRNA. We tested the hypothesis that placement of the lobe in primary culture, which removes the inhibitory innervation, would increase POMC mRNA levels and abolish the heterogeneity in POMC expression. POMC mRNA levels increased successively in untreated melanotropes when tested on culture Days 10, 16, and 20; however, some heterogeneity in POMC expression persisted. If treated with a D2 receptor agonist (1 microM bromocriptine) from culture Day 1, POMC mRNA levels were decreased significantly throughout the testing period when compared to untreated cells with the same time in culture. Although some melanotropes still expressed high POMC levels, preparations appeared more homogeneous by Day 20. Melanotrope responses were reversible, since POMC mRNA levels were down-regulated by application and up-regulated by withdrawal of a D2 receptor agonist. A short agonist treatment resulted in subpopulations that responded differently to the agonist, possibly representing a mechanism for fine-tuning peptide hormone release.
Collapse
Affiliation(s)
- D M Beatty
- Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City 64113-2499, USA
| | | | | |
Collapse
|
39
|
Aru GM, Davis CR, Elliott NL, Morris SJ. Endoscopic retrograde cholangiopancreatography in the treatment of bile leaks and bile duct strictures after laparoscopic cholecystectomy. South Med J 1997; 90:705-8. [PMID: 9225893 DOI: 10.1097/00007611-199707000-00011] [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: 02/04/2023]
Abstract
We reviewed our experience over 3 years with 11 patients who had bile leaks (Group 1) and 8 patients who had bile duct strictures after laparoscopic cholecystectomy (LC) and were treated with endoscopic retrograde cholangiopancreatography (ERCP) (Group 2). In Group 1, bile leaks were at the level of the cystic duct in 10 patients and from a duct of Luschka in 1 patient; 10 patients had sphincterotomy and 11 patients received barbed stents. All patients had resolution of bile leak and stents were removed after an average of 5 weeks. In Group 2, stenoses were at the level of the common bile duct (CBD) in 7 patients and of the CBD-common hepatic duct in 1 patient. Six patients had a sphincterotomy and 7 patients were successfully treated with pneumatic polyethylene balloon dilatation and stent placement. One patient had unsatisfactory dilatation and was referred to surgery. Two patients had permanent resolution of stenosis at 3 and 4 years of follow-up, 5 patients had recurrence, and a total of 6 patients eventually needed surgery. We conclude that ERCP is effective in resolving isolated bile leaks, but iatrogenic strictures after LC more often require surgical treatment after ERCP.
Collapse
Affiliation(s)
- G M Aru
- Davis Memorial Gastrointestinal Diagnostic Laboratory, Crawford Long Hospital, Emory University, Atlanta, Ga, USA
| | | | | | | |
Collapse
|
40
|
Lembo PM, Ghahremani MH, Morris SJ, Albert PR. A conserved threonine residue in the second intracellular loop of the 5-hydroxytryptamine 1A receptor directs signaling specificity. Mol Pharmacol 1997; 52:164-71. [PMID: 9224826 DOI: 10.1124/mol.52.1.164] [Citation(s) in RCA: 39] [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: 02/04/2023] Open
Abstract
Productive interaction between receptors and G proteins involves multiple intracellular receptor domains, but the role of individual receptor amino acids in directing the selection of specific signaling pathways has not yet been identified. Sequence alignment of several G protein-coupled receptors identified a highly conserved threonine residue in the i2 loop of the 5-hydroxytryptamine 1A (5-HT1A) receptor that is a putative protein kinase C phosphorylation consensus site and is located in a predicted amphipathic alpha-helical domain. To examine the role of this conserved threonine residue in 5-HT1A receptor coupling to Gi/Go proteins, this residue was mutated to alanine (T149A mutant). Wild-type and mutant 5-HT1A receptors were stably transfected into both Ltk- and GH4C1 cells to investigate receptor coupling to multiple signaling pathways. In both cell lines, the T149A mutant displayed similar agonist affinities as the wild-type receptor. In Ltk- cells, the T149A 5-HT1A receptor inhibited cAMP accumulation by 30% compared with wild-type (83%). A 2.6-fold increase in intracellular calcium (due to phospholipase C-mediated calcium mobilization) was observed for the wild-type receptor upon the addition of 100 nM 5-HT; whereas the T149A 5-HT1A receptor failed to mediate a calcium mobilization response at equivalent receptor levels to wild-type. When transfected in GH4C1 cells, the T149A receptor mutant fully inhibited basal cAMP and partially inhibited Gs-stimulated cAMP accumulation compared with wild-type receptor (57 +/- 14% versus 86 +/- 2%). In contrast, the T149A 5-HT1A receptor mutant failed to block the influx of calcium induced by calcium channel agonist (+/-)-Bay K8644, whereas the wild-type 5-HT1A receptor inhibited the calcium influx by 40%. Thus, the Thr149 residue is directly involved in G protein coupling to calcium mobilization (mediated by betagamma subunits of Gi2) and to inhibition of calcium channel activation (mediated by betagamma subunits of Go) but plays a minor role in coupling to alpha1-mediated inhibition of cAMP accumulation. The conserved i2 loop threonine may serve as a G protein contact site to direct the signaling specificity of multiple receptors.
Collapse
Affiliation(s)
- P M Lembo
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
| | | | | | | |
Collapse
|
41
|
Abstract
Stimulation of dopamine D2 receptors inhibits melanotrope pro-opiomelanocortin (POMC) biosynthesis and alpha-melanocyte-stimulating hormone (MSH) secretion. These effects are mediated by G-protein alpha i- and alpha o-subunits and are reversed by stimulating receptors linked to activation of G alpha s protein. Melanotrope activity is increased by haloperidol, a D2 receptor antagonist, and decreased by bromocriptine, a D2 receptor agonist. Both the short and long isoforms of the D2 receptor mRNA and protein increase following chronic haloperidol treatment. After chronic bromocriptine treatment the short isoform is downregulated, whereas the long isoform is upregulated. Our hypothesis is that specific G protein alpha- subunits alter in pattern of expression similarly to the receptor isoforms. Using immunohistochemistry and in situ hybridization, this study examined changes in G alpha i, G alpha o, and G alpha s protein and mRNA expression following chronic treatments with bromocriptine or haloperidol. G alpha i3 and G alpha o immunoreactivities increased following bromocriptine treatment, whereas G alpha s and G alpha i1/2 did not change. Gs immunoreactivity increased after haloperidol treatment, whereas G alpha i1/2, G alpha i3, and G alpha o did not change. G alpha i and G alpha o mRNA increased following bromocriptine and decreased following haloperidol treatments, whereas the inverse results were observed with G alpha s mRNA. These results suggest D2 receptor activation can specifically increase G alpha i3 and G alpha o expression, and D2 receptor blockade increases G alpha s expression.
Collapse
Affiliation(s)
- S A Sands
- School of Biological Sciences, University of Missouri-Kansas City 64110, USA
| | | | | | | |
Collapse
|
42
|
Abstract
1. The mechanisms involved in the human skin blood flow responses to iontophoretic application of acetylcholine (ACH; delivered using an anodal charge) or sodium nitroprusside (SNP; administered with a cathodal charge) are unclear. The aims of this study were to investigate possible contributions of prostaglandin production to the increase in skin blood flow induced following the iontophoresis of ACh and to investigate possible contributions from local sensory nerves to the perfusion responses induced by ACh, SNP and their vehicles. 2. The contribution of prostaglandins to the ACh response was determined in a randomized double-blind study of eight healthy subjects, who were studied on two occasions. Basal responses to ACh were measured before the oral administration of 600 mg soluble aspirin in diluted orange juice (1 occasion or orange juice (1 occasion) and again 30 min after the drink. The contribution of local sensory nerve activation to the responses to ACh and ACh vehicle (8 subjects) and to SNP and SNP vehicle (7 subjects) was assessed. EMLA (5%) (a eutectic mixture of lignocaine and prilocaine) and placebo cream were applied to two separate areas on the forearm in a double-blind randomized manner 2 h before drug responses were measured. In all studies the skin microcirculation responses to iontophoretically applied drug vehicle (1 site) and drug (2 sites) were recorded by laser Doppler perfusion imaging. 3. The increase in forearm skin perfusion (P < 0.001) in response to the iontophoresis of ACh minus the response to ACh vehicle was not significantly different following placebo or aspirin administration. The increase in forearm skin red blood cell flux (P < 0.001) in response to the iontophoresis of ACh minus the response to ACh vehicle was not significantly different at the placebo-compared with the EMLA-treated site. THe small increase in perfusion (P < 0.001) in response to the iontophoresis of ACh vehicle was significantly inhibited at the EMLA-compared with the placebo-treated site (P < 0.05). The marked increase in perfusion (P < 0.001) in response to the iontophoresis of SNP vehicle was significantly inhibited at the EMLA-compared with the placebo-treated site (P < 0.01). 4. These data suggest that in healthy volunteers: (1) mechanisms other than prostaglandin production and local sensory nerve activation may be involved in the increase in skin perfusion observed following the iontophoretic application of ACh; and (2) stimulation of local sensory nerves may be responsible for the increase in tissue perfusion observed following the iontophoretic application of either ACh vehicle or SNP vehicle.
Collapse
Affiliation(s)
- S J Morris
- Department of Vascular Medicine, Diabetes Research, Postgraduate Medical School Exeter, UK
| | | |
Collapse
|
43
|
Blumenthal R, Sarkar DP, Durell S, Howard DE, Morris SJ. Dilation of the influenza hemagglutinin fusion pore revealed by the kinetics of individual cell-cell fusion events. J Biophys Biochem Cytol 1996; 135:63-71. [PMID: 8858163 PMCID: PMC2121025 DOI: 10.1083/jcb.135.1.63] [Citation(s) in RCA: 181] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We have monitored kinetics of fusion between cell pairs consisting of a single influenza hemaglutinin (HA)-expressing cell and a single erythrocyte (RBC) that had been labeled with both a fluorescent lipid (Dil) in the membrane and a fluorescent solute (calcein) in the aqueous space. Initial fusion pore opening between the RBC and HA-expressing cell produced a change in RBC membrane potential (delta psi) that was monitored by a decrease in Dil fluorescence. This event was followed by two distinct stages of fusion pore dilation: the flux of fluorescent lipid (phi L) and the flux of a large aqueous fluorescent dye (phi s). We have analyzed the kinetics of events that occur as a result of transitions between a fusion pore (FP) and a solute permissive fusion pore (FPs). Our data are consistent with a fusion pore comprising six HA trimers.
Collapse
Affiliation(s)
- R Blumenthal
- Section on Membrane Structure and Function, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
| | | | | | | | | |
Collapse
|
44
|
Beatty DM, Sands SA, Morris SJ, Chronwall BM. Types and activities of voltage-operated calcium channels change during development of rat pituitary neurointermediate lobe. Int J Dev Neurosci 1996; 14:597-612. [PMID: 8930691] [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: 02/03/2023] Open
Abstract
Cultures of pituitary neurointermediate lobe cells were established from rats aged 1, 12, and 42 days to identify the types and assess the activities of Ca2+ channels present in melanotropes, glial-like cells, and fibroblasts during development. Day 12 represents the time at which dopaminergic axons have become distributed throughout the lobe, glial cells begin to lose their radial orientation, and melanotropes robustly express the short isoform of the dopamine D2 receptor. Thus, we studied Ca2+ channels in relation to the event of innervation of melanotropes. Real-time fluorescence video microscopy, in the presence of pharmacological agents, which block L-, N-, P-, and T-type channels, was used as an indirect measurement of channel activity. Assessment of cell type was verified by triple-label fluorescence immunohistochemistry. In melanotropes, extracellular Ca2+ addition caused Ca2+ influx through omega-conotoxin GVIA-sensitive, N-type channels on days 1 and 12 but not on day 42. The K+ depolarization induced an increase in intracellular Ca2+ concentration in all age-groups. This effect was decreased by nifedipine, an L-type channel blocker, at all ages, and by omega-agatoxin IVa, a P-type blocker, only on day 42. These results demonstrate that the predominance of N- or P-type channels on melanotropes is age-dependent and can be correlated with other developmental changes. The T-type blocker, NiSO4, had no effect. In glial-like cells of all ages, extracellular Ca2+ addition resulted in an increase in intracellular Ca2+ concentration, which was inhibited only by NiSO4. The percentage of responsive glial-like cells was equally high in days 1 and 12 cultures, then declined by day 42. The K+ depolarization had no effect on glial-like cells. Fibroblasts did not respond significantly to extracellular Ca2+ or K+ depolarization, indicating little detectable activity by this methodology from functional voltage-operated Ca2+ channels.
Collapse
Affiliation(s)
- D M Beatty
- School of Biological Sciences, University of Missouri-Kansas City 64108, USA
| | | | | | | |
Collapse
|
45
|
Abstract
1. Constitutive nitric oxide (NO) synthase has been demonstrated in human skin microvascular endothelial cells; however, the physiological significance of this finding is not known. The aim of this study was to investigate the effects of acetylcholine (ACh), which stimulates the release of NO from endothelial cells, on skin capillary pressure, capillary pulse pressure amplitude (CPPA) and capillary red blood cell velocity (CBV) in healthy volunteers. 2. Finger nailfold capillary pressure was measured in five healthy volunteers. CBV was measured in capillaries of the dorsal middle phalangeal area of the finger in six subjects using a recently developed capillary anemometer. In each case the responses to ionophoretically applied ACh and vehicle were measured on two separate fingers on the left hand. 3. Application of vehicle did not significantly change either capillary pressure, CPPA or CBV. ACh significantly increased capillary pressure (from 15.8 +/- 2.2 mmHg under basal conditions to 27.7 +/- 3.8 mmHg at the plateau of the ACh response; P < 0.008), CPPA (from 2.4 +/- 2.4 mmHg at baseline to 8.4 +/- 2.4 mmHg at the plateau of the drug response; P < 0.013) and CBV (from 0.54 +/- 0.22 mm s-1 at baseline to 2.46 +/- 1.12 mm s-1 after ACh; P < 0.008). 4. The increases in capillary pressure, CPPA and CBV following the application of ACh suggest that the overall effect of ACh was to induce a reduction in the pre- to postcapillary resistance ratio.
Collapse
Affiliation(s)
- S J Morris
- Department of Vascular Medicine, Postgraduate Medical School, University of Exeter, UK
| | | | | |
Collapse
|
46
|
Abstract
The development of techniques for measuring microvascular pressure, flow and permeability in man has allowed the construct of a pathophysiological framework for the development of diabetic microangiopathy. In insulin dependent disease the abnormalities observed conform to the haemodynamic hypothesis with early elevation of capillary pressure playing a primary role. In non insulin dependent diabetes differences are apparent, supporting the concept that changes in microvascular vasodilatory mechanisms may antedate the emergence of diabetes. Given the crucial role played by the endothelium in the regulation of local microvascular haemodynamics it is not surprising that disturbance of this tissue has been implicated in the pathogenetic process, an assertion supported by mounting experimental evidence suggesting that the nitric oxide pathway is crucially involved.
Collapse
Affiliation(s)
- J E Tooke
- Department of Vascular Medicine (Diabetes Research), Postgraduate Medical School, Exeter, Devon, UK
| | | | | |
Collapse
|
47
|
Puri A, Morris SJ, Jones P, Ryan M, Blumenthal R. Heat-resistant factors in human erythrocyte membranes mediate CD4-dependent fusion with cells expressing HIV-1 envelope glycoproteins. Virology 1996; 219:262-7. [PMID: 8623537 DOI: 10.1006/viro.1996.0244] [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: 01/31/2023]
Abstract
It has been shown that human CD4 expressed in nonhuman cells does not support HIV-1 entry into those cells and that components from human cells in addition to CD4 are required to overcome the block. We have used human red blood cells (huRBC) as a source for the accessory components since their membrane composition is less complex than that of nucleated cells and they are well characterized. Components were transferred by fusion of huRBC to nonhuman CD4(+) cells mediated by influenza hemagglutinin or polyethylene glycol. The RBC-modified nonhuman CD4(+) cells were labeled with fluorescent markers and incubated with gp 120-gp41-expressing cells labeled with a different fluorescent probe. Fusion between RBC- modified nonhuman CD4(+) cells and gp 120--gp41-expressing cells was quantified by fluorescence video microscopy. Human erythrocyte components transferred to nonhuman CD4+ cells conferred HIV-1 envelope glycoprotein-mediated fusion susceptibility to those cells. The fusion was enhanced by pretreatment of the erythrocytes for 10 min at 56 degrees. No gp 120--gp41-mediated fusion was observed when components from nonhuman RBC were transferred to nonhuman CD4+ cells. Human cell lines with pre-RBC characteristics (K562-CD4) also supported HIV-1 envelope glycoprotein-mediated fusion.
Collapse
Affiliation(s)
- A Puri
- Section on Membrane Structure and Function, NCI/NIH, Bethesda, Maryland 20892-1350, USA
| | | | | | | | | |
Collapse
|
48
|
Wiegmann TB, Vamos S, Welling LW, Beatty DM, Morris SJ. Simultaneous imaging of intracellular [Ca2+] and pH in single cells. Int Rev Exp Pathol 1996; 36:175-196. [PMID: 8860942] [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] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- T B Wiegmann
- Renal Section and Laboratory Service, Veterans Affairs Medical Center, Kansas City, Missouri 64128, USA
| | | | | | | | | |
Collapse
|
49
|
Morris SJ, Bass JM, Matthai CC. Reflectance anisotropy of the GaAs(001) (2 x 4) surface: Ab initio calculations. Phys Rev B Condens Matter 1995; 52:16739-16743. [PMID: 9981078 DOI: 10.1103/physrevb.52.16739] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
|
50
|
Abstract
The mechanisms involved in the pathogenesis of microangiopathy occurring in non-insulin-dependent diabetes mellitus (NIDDM) are unclear. In the present study, blood flow responses to the vasodilators acetylcholine (which acts via the endothelium) and sodium nitroprusside (a smooth muscle relaxant) were evaluated in this patient group. In 14 male patients with NIDDM, treated with either diet alone (n = 6) or diet plus insulin, (mean age 59 years) and 14 age-pair-matched control subjects, forearm skin perfusion following multiple doses of iontophoretically applied 1% acetylcholine and 0.01% sodium nitroprusside was recorded by laser Doppler perfusion imaging. Basal skin blood flow was not significantly different in the diabetic group compared with the control group. The following results are expressed as drug-minus-vehicle response. Acetylcholine significantly increased forearm skin perfusion (p < 0.001, analysis of variance) in all subjects, but the vasodilatation was attenuated in the patient group compared with control subjects (0.86 +/- 0.09 vs 1.36 +/- 0.14 arbitrary units of volts (V) respectively, at the fifth measurement point, mean +/- SEM, p < 0.01). Skin perfusion significantly increased following sodium nitroprusside (p < 0.001) but was lower in patients than control subjects (0.12 +/- 0.05 vs 0.45 +/- 0.11 V, respectively, at the fifth measurement point, p < 0.01). These data suggest that endothelial and/or smooth muscle function may be impaired in the skin microcirculation of patients with NIDDM.
Collapse
Affiliation(s)
- S J Morris
- Department of Diabetes and Vascular Medicine, Postgraduate Medical School, University of Exeter, UK
| | | | | |
Collapse
|