Postmortem comparison of ultrasonography, endocrine measurements and histology of large abnormal ovarian follicles in cows.
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Animals↗
Biomedical subjects
S J Scott
Publications and source records attributed to S J Scott.
Quantification of the depressive effects of diazepam on the guinea pig righting reflex.
The effects of 5 mg/kg/day diazepam (IP for 21-39 days) on righting reflex latency (RRL) and neuronal activity in the medial vestibular nucleus (MVN) were investigated in guinea pigs. Diazepam treatment increased the RRL relative to vehicle-injected controls (p < 0.05, ANOVA); although the average RRL in the diazepam-treated animals did decrease over time, this decrease was not statistically significant and therefore evidence of tolerance was not obtained. MVN slices were removed from diazepam-treated animals and recordings were made from MVN neurons in vitro. The average resting activities for MVN neurons in slices from diazepam-treated animals and uninjected animals from a previous study were not significantly different.
Animals↗
Understanding cultural obstacles to HIV/AIDS prevention in Africa.
Global efforts to prevent further spread of the human immunodeficiency virus (HIV) are faced with tremendous obstacles, and limited understanding of the cultural and social context of HIV and AIDS is an important factor hindering prevention efforts to date. Examples from the authors' experience in providing technical support to 7 nongovernmental projects for HIV/AIDS prevention in Africa illustrate the importance of including qualitative data in initial baseline studies for projects responding to the problem. Qualitative data are needed to provide a deeper understanding of the meanings of behavior and other phenomena that are identified through quantitative methods. Runyoka is discussed as an example of a traditionally-defined illness in Zimbabwe that appears to affect local understanding of HIV/AIDS. The authors suggest approaches that would assist HIV/AIDS projects to better understand and respond to the social and cultural context of AIDS in local settings.
Africa↗
Simple device for quantifying drug effects on the righting reflex.
A simple, inexpensive device is described that allows quantification of the effects of drugs on the righting reflex. This device consists of a modified set of kitchen scales connected to a digital timer. Two moveable Hall effect switches are positioned around the pointer, which registers the weight of the animal on the scales; when the animal is placed on the scales in the supine position, the initiation of a righting reflex causes the pointer to cross one of the switches, stopping the digital timer and providing a measure of righting reflex latency (RRL). We describe an efficient protocol for using this device that provides quantification of drug effects on the RRL, which can then be subjected to analysis using parametric statistics such as analysis of variance.
Animals↗
Induction of FMLP-mediated calcium mobilization requires crosslinking of surface immunoglobulin in Daudi cells.
We have explored the requirements for the induction of the N-formyl-methionyl-leucyl-phenylalanine (FMLP) response in Daudi cells after anti-immunoglobulin treatment. Our results indicate that (a) induction of responsiveness to FMLP was observed in Daudi only after crosslinking of surface immunoglobulin by anti-immunoglobulin; (b) this induced responsiveness was not observed in Ramos or Wil-2 cells; (c) the F(ab')2 fragment was sufficient for the induction of the FMLP response, but the Fab fragment and the Fc fragment were ineffective; (d) of the many agents active in B lymphocyte regulation which were tested, none were as effective as anti-immunoglobulin in the induction of the FMLP response; and (e) three inhibitors of calcium mobilization (W-7 (N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide), PMA (phorbol 12-myristate 13-acetate), and colchicine), acting on distinct mechanisms, inhibited both the calcium mobilization due to anti-immunoglobulin and the induction of responsiveness to FMLP. Our results suggest important determinants in the induction of a calcium-mobilizing FMLP response in cells of B lymphocyte lineage include (a) the cell type, (b) a selective requirement for activation via surface immunoglobulin, and (c) crosslinking of the surface immunoglobulin.
Antibodies↗
G-proteins and the role of second messengers in the regulation of the human neutrophil.
The ideas discussed above clearly point to increasingly complex and interactive transduction mechanisms for the regulation of the neutrophil. The central challenges to be met include the following: 1. Better assays are needed for the study of physiological parameters such as adherence, aggregation, shape change, and cytoskeletal rearrangements, assays which are not prohibitively complex and expensive while still allowing for more detailed physiological observations. 2. The neutrophil receptors need to be characterized in greater detail at the molecular level. Protein purification, sequencing, and cloning approaches are needed. Given the inherent shortcomings of working with the neutrophil system due to the presence of proteases and the problems of obtaining sufficient amounts of plasma membranes as source material for receptor purification, this is a difficult task. Advances in micropurification and sequencing may alleviate some of the difficulties here. 3. The size and complexity of the G-protein family continue to expand. However, as pointed out earlier, stimulus-responsive enzymes without G-protein-associated regulation, and G-proteins without clearly identified targets, remain. A better definition and description of the G-protein family will be required if cellular regulation is to be understood at the molecular level. In terms of second messengers and their role in cellular regulation, the main questions which remain to be answered concern identification of the precise pathways which are important to cellular regulation. In order to understand the complex cascades of arachidonate metabolism, phospholipid turnover, and calcium homeostasis, it is all the more important that the manner in which second messengers may regulate particular cell functions be better understood. An omission in this review is the role of kinases in cellular regulation. Activation of kinase C (through calcium and diacylglycerol) and kinase A (through cAMP) has been demonstrated. The substrates for these kinases have been described by various investigators. However, relating phosphorylation changes in a particular protein to the activity of the protein, and assignment of activity to particular physiological roles, has not been satisfactorily accomplished and remains a challenge for the future.
Arachidonic Acid↗
The role of non-governmental organizations in the global response to AIDS.
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Acquired Immunodeficiency Syndrome↗
Successful haemodialysis via an unusually sited subclavian catheter.
A 38-year old woman with a history of congenital rubella required temporary venous access for haemodialysis. A left sided subclavian catheter was inserted percutaneously and on check radiography it was found to be on the left side of the mediastinum. Contrast radiography showed that the catheter was in a left sided superior vena cava which drained into the right atrium via the coronary sinus. Haemodialysis was performed without any difficulty.
Adult↗
Desensitization of calcium mobilization and cell function in human neutrophils.
Neutrophils pretreated with the chemoattractant formylmethionyl-leucyl-phenylalanine become unresponsive when re-exposed to the same ligand, a process termed desensitization. We have examined whether desensitization of transduction (Ca2+ mobilization) or of other cell functions (superoxide generation, enzyme release, or aggregation) occurs synchronously. Simultaneous studies of Ca2+ mobilization and aggregation by using Fura-2-loaded cells indicate that, under conditions where the aggregation response is abolished, most of the Ca2+ mobilization is unaltered. Further studies were then carried out to ascertain whether desensitization of Ca2+ mobilization could in fact be induced. Desensitization was observed, and was dependent on the number of exposures of the cells to the ligand, the concentration of the ligand, and whether the ligand was left in the medium or was removed. The pattern of resensitization was dependent on the experimental design. Under conditions where ligand was continuously present, no recovery of the Ca2+-mobilization response was seen with subsequent challenges. In contrast, on removal of ligand, this response showed partial recovery. Whereas complete desensitization of aggregation was noted, enzyme release showed a markedly lesser degree of desensitization and required more frequent exposures to the ligand before it was observed. Little or no desensitization of superoxide generation was observed regardless of the conditions utilized. Studies using phorbol myristate acetate as the ligand showed that Ca2+ mobilization and aggregation could be simultaneously inhibited. Our results suggest that discrete mechanisms of desensitization are possible in human neutrophils, and that desensitization of one particular function (aggregation) does not imply concomitant desensitization of other functions.
Calcium↗
Peptide mapping studies of the pertussis toxin substrate in human neutrophils, platelets and erythrocytes.
Protease digestion of the ADP-ribosylated pertussis toxin substrate (PTS) protein was carried out after solubilization with SDS (Cleveland gels) and in the intact membrane. Cleveland gel analysis showed substantial similarities in the maps for the PTS component in neutrophils, platelets and erythrocytes and also in the S49 AC-lymphoma cell line. In the intact membrane ADP-ribosylation followed by digestion showed limited access of proteases to the PTS component. Of eight proteases tested, only papain and Staphylococcus aureus gave substantial digestion. This pattern was observed in the human platelet, erythrocyte and neutrophil plasma membranes. When the sequence was reversed and ADP-ribosylation was carried out after protease digestion, a very different pattern was observed with much greater susceptibility to digestion being noted with several proteases. By contrast, analysis of the murine AC-membrane showed some minor variations in the digest patterns. In addition, under all three conditions tested, maps of the cholera toxin substrate for the human platelet showed remarkable similarities to those obtained with the pertussis toxin substrate. Our results indicate that the protease sensitive sites of the alpha subunit of PTS and protection from proteolysis after ADP-ribosylation are properties which are shared by the PTS components of human platelets, erythrocytes and neutrophils.
Adenosine Diphosphate Ribose↗
Anti-immunoglobulin pretreatment induces a calcium-mobilization response to the chemotactic agent N-formylmethionylleucylphenylalanine in Daudi lymphoblastoid cells.
Anti-immunoglobulin treatment of fura-2-loaded Daudi cells induces a calcium mobilization as judged by the increase in the fluorescence of the dye fura-2, AM. No calcium mobilization by N-fMet-Leu-Phe is observed in these cells. However, exposure of the cells to N-fMet-Leu-Phe after the first hit with anti-immunoglobulin (but not after soluble IgG) shows a rapid, dose-dependent calcium mobilization by N-fMet-Leu-Phe. The expression of the calcium-mobilizing response occurs in less than 2 min and is stable. Binding of tritiated N-fMet-Leu-Phe is increased in anti-immunoglobulin-treated but not control cells. The induction is specific for N-fMet-Leu-Phe because the chemoattractant platelet-activating factor did not induce any calcium mobilization. The N-fMet-Leu-Phe antagonist t-butoxycarbonyl-L-Phe-D-Leu-L-Phe-D-Leu-L-Phe- OH did not show any calcium mobilization on its own, either before or after anti-immunoglobulin treatment, and inhibited the calcium mobilization of N-fMet-Leu-Phe at low concentrations. Treatment of the cells with phorbol 12-myristate 13-acetate or pertussis toxin prior to anti-immunoglobulin treatment caused a dose-dependent abolition of both the anti-immunoglobulin-mediated calcium mobilization and the subsequent calcium mobilization by N-fMet-Leu-Phe. Metabolic inhibitors that act predominantly by lowering the ATP levels within the cell (iodoacetate, sodium fluoride, oligomycin, and 2-deoxyglucose) all produced a greater inhibition of the N-fMet-Leu-Phe-mediated calcium mobilization than the anti-immunoglobulin-mediated response. Lowering the temperature from 37 degrees C to 22 degrees C reduced the anti-immunoglobulin response and completely inhibited the expression of the N-fMet-Leu-Phe effect. Our results indicate that activation of the calcium-mobilization pathway in B cells by crosslinking of bound surface immunoglobulin causes an induction of N-fMet-Leu-Phe-sensitive calcium mobilization.
Antigen-Antibody Complex↗
Cap formation in a B-lymphocyte cell line is inhibited by pertussis toxin and phorbol ester.
We have examined concanavalin A (Con A)-induced cap formation in a B-lymphocyte derived cell line, LAZ-559. Treatment with pertussis toxin (PT) or phorbol-12-myristate-13-acetate (PMA) prior to exposure of the cells to Con A abolished the capping reaction. The possible role of calcium mobilization was tested using cells pre-loaded with the fluorescent dye Quin2. Both PT and PMA caused inhibition of calcium mobilization at concentrations similar to those observed for the inhibition of capping. The possible identity of the substrate for pertussis toxin was examined by carrying out ADP-ribosylation of the isolated plasma membranes using [alpha-32P]NAD and pertussis toxin. Several bands were observed at molecular weights of 109,000, 43,000, 34,000 and 22,000. Comparative labelling with cholera toxin revealed a separate band at 42,000. The bands at 43,000 and 34,000 are PT specific. Of these, the 43,000 band comigrated with the PT substrate that has been shown to regulate capping in human neutrophils (Lad et al., 1985a, 1986b). PMA-induced phosphorylation was examined in 32P-loaded cells, and multiple bands were observed to be labelled in a dose-dependent manner, at least two of which were very similar in mobility to the PT substrate. Our results suggest that regulation of calcium mobilization and the control of capping via a PMA-sensitive, GTP-binding protein are probably general phenomena observable in multiple cell systems.
B-Lymphocytes↗
Severity scoring in intensive care.
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Critical Care↗
Technetium-99m Medronate uptake in subcutaneous soft-tissue nodules in a patient with renal failure and renal adenocarcinoma.
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Abdominal Muscles↗
Cerebral dysfunction in intensive care.
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Brain Diseases↗
A pertussis toxin-sensitive GTP-binding protein in the human neutrophil regulates multiple receptors, calcium mobilization, and lectin-induced capping.
Human neutrophils treated with pertussis toxin had decreased functional responses to several agents including zymosan-treated serum, heat-aggregated immunoglobulin, platelet-activating factor, and fMet-Leu-Phe. Responses affected include superoxide generation and release of lysozyme. The degree and type of inhibition was dependent on the individual receptor and the cellular response studied. Measurement of intracellular calcium levels with quin-2 showed that both fMet-Leu-Phe- and platelet-activating factor-mediated increases in quin-2 fluorescence were diminished as a result of pertussis toxin treatment. fMet-Leu-Phe-mediated calcium uptake was also inhibited. However, under conditions where fMet-Leu-Phe-mediated effects on cell function were completely abolished, only a partial inhibition of 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester (TMB-8) sensitive calcium uptake was observed. A study of the linked reactions of chemotaxis, capping, and shape change revealed that chemotaxis was inhibited regardless of the chemoattractant utilized (zymosan-treated serum, fMet-Leu-Phe, and platelet-activating factor) and the associated reactions of Con A capping and fMet-Leu-Phe- or Con A-mediated shape change were reduced in pertussis toxin-treated cells. Our results suggest that multiple mediators of inflammation act through a pertussis toxin-sensitive GTP-binding protein that regulates the mobilization of internal calcium as well as calcium uptake and is, in addition, a key control element of shape change, capping, and chemotaxis.
Calcium↗
The Medicare prospective payment system.
In 1983 Congress adopted the most significant change in the Medicare program since its inception in 1965. Along with measures to ensure the solvency of the Social Security System into the next century, Congress approved a system of prospective payment for hospital inpatient services, whereby hospitals are paid a fixed sum per case according to a schedule of diagnosis related groups (DRGs). The program will be phased in over a four-year period that began October 1, 1983. Several types of hospitals and distinct part units of general hospitals are excluded from the system until 1985, when Congress will receive a report on a method of paying them prospectively. Information used to calculate the DRG rates was published September 1, 1983, as part of the interim final regulations. Other third party payers, such as state Medicaid systems and insurance companies, are considering converting to this method of payment, and several have adopted it. The implications for occupational therapy include a greater emphasis on reducing hospital length of stay, expanding outpatient care, increasing productivity, and a trend toward documentation and accounting consistent with computer technology.
Diagnosis-Related Groups↗