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Biomedical subjects

D Gray

Publications and source records attributed to D Gray.

At least 235 records · Page 13Linked to original sources
PubMed1984

Blood volume changes and arginine vasotocin (AVT) blood concentration in conscious fresh water and salt water adapted ducks.

Blood volume changes consisting in the removal and reinfusion respectively, of 10% of the estimated blood volume (23.2 ml on average) were induced to determine their effects on the blood concentration of arginine vasotocin (AVT), the antidiuretic hormone (ADH) of birds, in fresh water adapted ducks (water ducks) with blood osmolalities and ADH concentrations similar to those of normally hydrated mammals, and in salt water adapted ducks (salt ducks) with chronically elevated blood osmolalities and ADH concentrations. The investigations were carried out in steady state conditions, when infusion of 1 ml . min-1 of isotonic saline was matched by the excretion in water ducks and when infusion of 0.4 ml . min-1 of 1,000 mosmolal saline was matched by the salt gland excretion in the salt ducks. After blood removal, AVT blood concentration (mean +/- SE) increased from 6.5 +/- 0.4 to 8.4 +/- 0.6 pg . ml-1 in water ducks and from 18.1 +/- 1.6 to 22.6 +/- 1.9 pg . ml-1 in salt ducks. The respective blood osmolalities of 297.4 +/- 1.4 and 318.6 +/- 3.3 mOsm . kg-1 did not change. Reinfusion of the blood after steady-state conditions had been reattained decreased blood AVT from 7.9 +/- 0.7 to 6.7 +/- 0.5 pg . ml-1 in water ducks. In the salt ducks AVT concentration had already returned to the control level before blood reinfusion which induced no further reduction. The blood osmolalities remained unchanged in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1984

Relation of intra-splenic migration of marginal zone B cells to antigen localization on follicular dendritic cells.

Injection of heat-killed Escherichia coli into rats results in massive loss of IgM + ve, IgD - ve B cells from the marginal zones of their spleen within 4 hr. This is matched by a concomitant increase of cells with this phenotype in the splenic follicles. The marginal zone remains depleted and the follicles distended for about 16 hr, but the histological picture returns to normal within 24 hr. Surface marker analysis of blood and spleen B lymphocyte populations throughout the course of the migration suggest that there is intrasplenic migration of IgM + ve cells from marginal zone to follicles rather than via the circulation. Factors inhibiting localization of immune complex on follicular dendritic cells were assessed for their influence on marginal-zone B cell migration. Immune complex, injected 5 hr post-endotoxin administration localized poorly on follicular dendritic cells. While C3 depletion, by cobra venom, has no effect on marginal-zone B cell migration induced by endotoxin, it completely inhibits transport of heat-aggregated human gammaglobulin to follicular dendritic cells.

Animals↗
PubMed1984

Control of central release of vasopressin.

A diffuse extrahypophyseal vasopressinergic system has been described in the brain, and vasopressin (AVP) has also been identified in the cerebrospinal fluid (CSF) of several species. Administration of AVP to the central nervous system has been found to influence several brain functions. It has been suggested therefore that this peptide may act as a physiologically significant neuromodulator of the central nervous system functions, including the control of the body fluid homeostasis. However, the mechanisms controlling the central release of AVP are poorly recognized. The purpose of the present investigation was to find out whether the release of AVP into the CSF is controlled by volume and osmotic stimuli and whether it may be relevant to the control of water intake. The experiments were performed on conscious dogs chronically implanted with a device enabling the withdrawal of CSF from the anterior part of the third ventricle which is situated in the vicinity of abundant vasopressinergic fibers. AVP measured by radio-immunoassay and osmolality were determined in blood and CSF samples taken simultaneously. 24 h dehydration caused a significant elevation of plasma (Posm) and CSF (CSFosm) osmolalities as well as of plasma (PAVP) and of CSF (CSFAVP) AVP concentrations. During rehydration total water intake (TWI) X kg-1 b.w. was significantly correlated with Posm and PAVP as well as with CSFosm and CSFAVP prior to drinking. Rehydration caused Posm, PAVP, CSFosm and CSFAVP to decrease significantly within 90 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1983

Percutaneous initiation of cardiopulmonary bypass.

Improved technology has allowed us to develop support pumps that can be applied rapidly and safely. A system utilizing thin-walled (4 mm inner diameter) percutaneously inserted sheaths has been designed for rapid bedside arterial and central venous cannulation to establish femoral arterial and venous cardiopulmonary bypass. The system utilizes two 30-cm-long large-bore, thin-walled (end and side holes) venous cannulas and a single 15-cm-long (end hole) arterial reperfusion cannula, which is connected to a pediatric oxygenator and a vortex pump head. Five patients with refractory cardiac arrest who could not be resuscitated by conventional means were revived with this system. Application time was approximately five minutes. This system appears to be an easily applied and reliable short-term mechanical support device.

Cardiopulmonary Bypass↗
PubMed1983

A job club for older job seekers: an experimental evaluation.

Labor market trends and expert opinion have recently highlighted the existence of an "older worker problem" that will require policy and programmatic remedies. This study details the findings of a longitudinal field experiment on the effectiveness of a promising behavioral/self-help job-finding program --the job club. Employment service clients (N = 46) were randomly assigned to receive the job club program or normally available (control) services. Twelve week follow-up data revealed a 74% employment rate for job club participants versus 22% for controls. Both groups obtained comparable placements. Study findings indicate the job club is an effective employment service for older job seekers.

Aged↗
PubMed1983

Vasopressin in blood and third ventricle CSF of dogs in chronic experiments.

A device for chronic implantation was developed that allowed sampling of cerebrospinal fluid (CSF) from the anterior part of the third cerebral ventricle (A3V) of dogs in repeated experiments for up to 4 mo. Osmolalities, electrolyte concentrations, and concentrations of arginine vasopressin (AVP) measured with a radioimmunoassay were determined in repeated experiments on the chronically prepared animals under conditions of normal hydration, both in the conscious state and during inhalation anesthesia. In conscious dogs, AVP concentrations in plasma and CSF were 3.3 +/- 0.4 and 21.8 +/- 2.5 pg X ml-1, respectively. During anesthesia without surgical interference, the AVP concentrations in plasma and CSF were increased twofold above the levels obtained in conscious dogs. During the time of observation (180 min) all measured parameters remained constant. The AVP concentrations in plasma and CSF samples collected during the surgical procedure of device implantation were about 10-fold higher than in the samples collected during the conscious state. Thus, in each experimental condition, AVP concentration in the CSF collected from the A3V was consistently higher than that in the simultaneously collected blood samples.

Animals↗
PubMed1983

Vasopressin in blood and third ventricle CSF during dehydration, thirst, and hemorrhage.

Samples of cerebrospinal fluid (CSF) were collected from the anterior part of the third cerebral ventricle of mongrel dogs with a chronically implanted device. Repeated experiments with simultaneous sampling of CSF and venous blood in 60- to 90-min intervals were performed in conscious dogs after 24-h water deprivation and during subsequent rehydration by drinking, during thirst stimulation by intravenous infusion of 5% saline, and during blood removal (12 ml X kg body wt-1). The CSF and plasma samples were analyzed for osmolality and arginine vasopressin (AVP) with a radioimmunoassay. Compared with normally hydrated dogs, 24-h water deprivation caused plasma AVP to rise significantly from 2.5 to 7.7 pg X ml-1 and CSF AVP from 24.2 to 31.3 pg X ml-1. Subsequent drinking significantly reduced plasma and CSF AVP. Thirst stimulation by hypertonic infusions was associated with rises of plasma and CSF AVP. Modest reduction of blood volume also increased both plasma and CSF AVP. Plasma AVP in each of the described physiological disturbances of salt or fluid balance was positively correlated with CSF AVP.

Animals↗
PubMed1983

Evidence bearing on the generalizability of laboratory findings relating to high-altitude mountaineering.

An evaluation of the psychological effects of high-altitude mountaineering was conducted on three subjects before, during, and after their ascent of a 25,600-ft. mountain. The assessment incorporated a battery of cognitive tests within a single-subject design, and the results indicated the absence of an effect. This is contrary to laboratory findings on the stressors involved in mountaineering, such as hypoxia. These have generally been reported as significantly influencing cognitive functioning.

Adaptation, Psychological↗
PubMed1982

Composition of urinary calculi collected in the Durban area.

Three hundred urinary calculi were collected in the Durban area during the period August 1979--August 1980. Analysis by the X-ray diffraction method showed that their composition is generally similar to that found in the USA and UK. The incidence of uric acid, present in 17% of the calculi, is higher than that found overseas. There is a significantly higher incidence of calcium oxalate in calculi from Indians (83% v. 70% in Whites) while there is a significantly higher incidence of urinary apatite in Whites (35% v. 21% in Indians).

Black or African American↗
PubMed1982

Migrant mu+ delta+ and static mu+ delta- B lymphocyte subsets.

Immunoglobulin isotype expression in isolated lymph node (LN), spleen and blood lymphocyte suspensions was assessed in rats. The proportion of mu+ delta- B cells in spleen (34%) was approximately twice that in blood and LN. Immunohistological examination of spleens showed the cells of the marginal zones to be predominantly mu+ delta-. On the other hand, mu+ delta+ B cells were mainly confined to the follicles in both spleen and LN. These follicles had a minor mu+ delta- component. The migratory properties of B cells with these two phenotypes were assessed by depleting lymphocytes migrating through the white pulp of rat spleen. This was achieved by placing a 32P-impregnated beta-emitting polythene strip over one half of the spleen. Examination of the nonirradiated half of the spleen, LN and peripheral blood after 12 days irradiation showed selective loss of delta + B cells. The mu + delta- cells of the splenic marginal zone were numerically unaltered. There was also a substantial residual mu + delta- B cell presence in the small lymphocyte compartment of follicles of LN and spleen in depleted animals. In addition, the blood selectively retained a mu + delta- B cell component. This was not derived from the spleen, as mu + delta- blood B cell numbers were sustained even where both halves of the spleen were irradiated. It is concluded that: (a) the major static B cell component of spleen and LN is mu + delta-, (b) that most if not all delta + B cells repeatedly migrate through the spleen and (c) there is a blood-born mu + delta- component which is resistant to depletion by splenic irradiation.,

Animals↗