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Biomedical subjects

D Gordon

Publications and source records attributed to D Gordon.

At least 451 records · Page 25Linked to original sources
PubMed1981

Selective inhibition of thromboxane biosynthesis in human blood mononuclear cells and the effects of mitogen-stimulated lymphocyte proliferation.

1. The effects of six imidazole compounds were examined on thromboxane B2 (TxB2) and prostaglandin E2 (PGE2) production and mitogen-stimulated lymphocyte transformation in human blood mononuclear cells. 2. UK 37248 (4-(2-[IH-imidazol-l-yl]ethoxy)benzoic acid), imidazole and 1-methylimidazole selectively inhibited TxB2 synthesis in a dose-related manner, with corresponding increases in PGE2 production. 3. Clotrimazole, benzimidazole and 2-methylimidazole preferentially inhibited TxB synthesis but had little effect on PGE2 production. 4. Clotrimazole and benzimidazole inhibited proliferative responses of the lymphocytes, but UK 37248 and 1-methylimidazole did not affect transformation at concentrations which inhibited TxB2 synthesis to a similar level (over 90%). 5. The results do not support involvement of endogenous TxB2 in the process of lymphocyte mitogenesis or in the mechanism of the suppressive effects of some TxB2 synthetase inhibitors.

Humans↗
PubMed1981

An analysis of the regulation of sodium excretion during induced changes in plasma sodium concentration in anaesthetized dogs.

1. Renal sodium excretion (UNaV) was studied during acute changes in plasma sodium concentration (PNa) induced by altering the concentration of a sodium chloride infusion in anaesthetized dogs. 2. The change in PNa induced other changes, notably in blood pH, the degree of blood dilution, and in glomerular filtration rate and renal plasma flow. No attempt was made to restrain these changes and their effects on UNaV were assessed using factor analysis. This defined new variables ('factors') that are linear functions of the primary variables. Four factors were defined, two of which were related to UNaV. 3. Factor 1 was strongly correlated with UNaV and PNa: its other correlations described the acidosis and plasma dilution of hypernatraemia. Further examination of these inter-relationships by regression analysis and data selection showed that the increase in UNaV with rising PNa depended upon a fall in both the blood pH and PCO2. 4. Factor 2 was negatively correlated with UNaV: its correlations with plasma protein concentration, haematocrit, blood pressure, glomerular filtration rate and renal plasma flow implied that it represented post-glomerular plasma protein concentration and its influence on sodium reabsorption. 5. Thus, two independent processes may regulate UNaV during acute salt loading: one is initiated by changes in PNa and plasma dilution but requires a concomitant acidosis and ventilatory adjustment for its full expression; the second relates UNaV to several variables whose influences could be understood by changes they produce in the peritubular capillary plasma protein concentration.

Animals↗
PubMed1981

A right ventricular cardiac assist device.

A good method of assisting the right ventricle of the heart has, up to the present, not been available. This paper presents a new approach to assisting the right ventricle of the heart which can be utilised independently or during cardiac surgery. Through implementation of this approach, and timed inflation and deflation of several types of balloon catheters in the pulmonary artery, distal pulmonary arterial flow is augmented with subsequent unloading of the right side of the heart. This approach, hopefully, will be of benefit in the treatment of atherosclerotic and congenital heart disease as well as in many cases of pulmonary hypertension.

Animals↗
PubMed1981

Comparison of the inhibition by glucocorticosteroids and cyclosporin A of mitogen-stimulated human lymphocyte proliferation.

We examined the effects of dexamethasone, hydrocortisone and cyclosporin A (CyA), alone and in combination, on tritiated thymidine (3H-TdR) incorporation into human blood mononuclear cells stimulated by phytohaemagglutinin (PHA), pokeweed mitogen (PWM) and phorbol myristic acetate (PMA). Pharmacological concentrations of glucocorticosteroids displaced the PHA and PWM dose-response curves to the right, but the same maximum response was achieved indicating selective inhibition at suboptimal levels of stimulation. In contrast, steroid inhibition of PMA-stimulated cells was not mitogen dose-dependent and the maximum response was clearly depressed. In the case of CyA, the stimulation by all three mitogens was inhibited in the latter fashion, but 10-fold higher concentrations were required to inhibit PMA-stimulated cells compared with PHA- and PWM-stimulated cells. These results suggest that a steroid-sensitive mechanism or lymphocyte sub-population may be selectively activated by PMA and by low doses of PHA and PWM, while the different inhibition profile observed for CyA might be taken to indicate that this drug affects a separate subpopulation and that PMA activation occurs later than the CyA-sensitive stage. Predominantly synergistic effects were obtained when the drugs were used together, thus providing an experimental basis for combination therapy in the treatment of reactions involving multiple lymphocyte activation mechanisms.

Cells, Cultured↗
PubMed1980

Blood-pressure and its correlates in urban and tribal Africa.

Blood-pressure and associated factors were compared in tribal and urban Xhosa people of Southern Africa. In the urban group blood-pressures were high and rose significantly with age whereas in the tribal group they were low and rose little with age. Indices of obesity including weight, skin-fold thickness, and ponderal index were significantly greater in urban dwellers and correlated strongly with arterial pressure. Dietary sodium and urine-sodium/creatinine ratio were significantly higher in the urban people, but there was no within-population relationship between either dietary sodium or urine-sodium/creatinine ratio and blood-pressure. Plasma-noradrenaline, an index of sympathetic activity, was similar in both populations, as was plasma-renin activity. Low plasma-renin was common and may be genetically determined. Diet and obesity may contribute to the rise in arterial pressure that is a consequence of urbanisation.

Adolescent↗
PubMed1980

Reye's syndrome in three siblings. Association with type A influenza infection.

Reye's syndrome occurred simultaneously in three siblings. All had characteristic changes in liver histology ascertained by light and electron microscopy. The two patients with the most severe disease also had serum that caused marked stimulation of mitochondrial state 4 respiration in vitro. Histocompatibility locus antigen typing showed that no unique haplotypes were shared by all three children. There was no evidence of exposure to aflatoxins, pesticides, or other substances that have been previously postulated to be associated with Reye's syndrome. Influenza A/Brazil/11/78-like virus was isolated from one patient, and all three patients had a fourfold or greater rise in hemagglutination-inhibiting antibody to H1N1 influenza virus.

Antigens, Viral↗
PubMed1980

Effect of propranolol on heart rate, blood pressure and plasma noradrenaline during coitus in the rabbit.

1. The effects of coitus on heart rate, blood pressure and plasma concentration of noradrenaline were studied in six male rabbits. 2. During coitus, heart rate rose from 228 +/- 6 to 324 +/- 8 beats/min (mean +/- SEM; n = 24). Mean blood pressure rose from 87 +/- 3 to 165 +/- 4 mmHg, and plasma concentration of noradrenaline from 2.07 +/- 0.21 to 5.02 +/- 0.26 nmol/l. The maximum heart rate did not occur until after the peak in blood pressure. 3. Propranolol had no effect on the power expended during coitus, but there was a dose dependent fall in the changes in heart rate, blood pressure and plasma concentration of noradrenaline.

Animals↗
PubMed1980

Pulmonary functional abnormalities after upper dorsal sympathectomy. A comparison between the supraclavicular and transaxillary approaches.

Results of pulmonary function studies were compared in two groups of 12 patients each, in whom upper dorsal sympethectomy was performed by the supraclavicular or by the transaxillary approach. Patients were evaluated clinically, radiologically and functionally before operation and again three weeks, three months and six months after denervation. Findings suggest that an increase in small airway resistance concomitant with some degree of pneumoconstriction occurred after upper dorsal sympathectomy by both routes. Musclar transection and possible phrenic nerve retraction damage due to the operative procedure could not be the cause of the above abnormalities because the inspiratory and expiratory forces, inspiratory peak flow and diaphragmatic movement were not significantly reduced after operation by both approaches. However, in a few cases, extrapleural hematomas, segmental atelectasis and relaxation of the daiphrgm could have contributed to the loss of the lung volume. This was evident only in the early period and was obvious in the transaxillary approach group.

Adult↗
PubMed1980

Alteration of T and null lymphocyte frequencies in the peripheral blood of human opiate addicts: in vivo evidence for opiate receptor sites on T lymphocytes.

Street opiate addiction produces a significant depression in the absolute number of total T lymphocytes in peripheral blood as measured by the ability of the lymphocytes to rosette sheep red blood cells (SRBC). Associated with the decrease in T cells, there is an increase in the absolute number of null lymphocytes but no significant changes in B lymphocytes or total white blood cell count. The T cell values for 2 different populations of addicts (n = 12 and 32) are 31.8% and 23.1%, whereas the null cell values are 51.1% and 57.6%, respectively. The values for comparable control populations (n = 18 and 10) are: T% = 70.7% and 67.4%, and null % = 9.2% and 14.5%. Self-reported use of marihuana does not significantly alter the distribution of cell populations. A 1- to 3-hr incubation of addicted-derived lymphocytes with 10(-6) to 10(-7) M Naloxone reverses both T cell depression and null cell increase by allowing the null cells to express SRBC receptors. Cyclic AMP and dibutyryl cyclic AMP can also convert the null cells to T cells. The conversion of null to T lymphocytes has additionally been measured by monitoring the increase in PHA-stimulated growth in 72-hr cultures as determined by tritiated thymidine incorporation into DNA. These results support the hypothesis that opiates can alter T lymphocyte number and function in vivo, and that this alteration may produce a significant degeneration in the immune competence of street opiate addicts.

B-Lymphocytes↗
PubMed1980

Correlations of plasma high-density lipoprotein cholesterol levels with other plasma lipid and lipoprotein concentrations.

We investigated the association of plasma high-density lipoprotein (HDL) cholesterol levels with levels of cholesterol in other plasma lipoprotein fractions (low-density [LDL], very low density [VLDL] and their sum) and with total plasma cholesterol and triglyceride levels in 3493 males and 3318 females in the Lipid Research Clinics (LRC) Prevalence Study. Correlation coefficients were calculated for each stratum of age, sex and hormone use using a logarithmic transformation. The correlations of log HDL cholesterol with the other lipid and lipoprotein fractions generally depended strongly on age and sex but not on use of gonadal hormones. In the 20-70-year range, the age dependence of each correlation coefficient was well described by a linear regression model. The weakly positive association between HDL and total cholesterol levels in adults and the marked negative association of HDL cholesterol with triglyceride and VLDL cholesterol levels in almost all strata are in good general agreement with the results of earlier studies.

Adolescent↗