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Biomedical subjects

J V Jones

Publications and source records attributed to J V Jones.

At least 163 records · Page 9Linked to original sources
PubMed1976

Beta-adrenoreceptor blockade in hypertension.

There is good evidence from many sources that beta-adrenoreceptor blockade is an effective form of therapy in mild, moderate and severe hypertension either alone or in combination with other antihypertensive agents. Although a number os such beta blocking compounds are now available, they appear to have a hypotensive effect of approximately equal magnitude. This hypotensive effect is obtained in both the supine and standing positions thus avoiding postural hypotension. The maximum hypotensive effect may take some time to become apparent. Despite considerable work the mode of action remains uncertain, reduction in cardiac output, resetting of baroreceptors, reduction in plasma renin and a central nervous system effect have been suggested but remain unproved. There is evidence to suggest that these compounds can control, to some degree, the surges in blood pressure resulting from either mental or physical stress. A low incidence of serious side effects has been reported by many workers. Only the long-term use of these compounds in comparison with other antihypertensive agents will determine their place in the management of hypertension.

Adrenergic beta-Antagonists↗
PubMed1976

Plasmapheresis in the management of acute systemic lupus erythematosus?

Eight patients with systemic lupus erythematosus (S.L.E.) have been treated with plasmapheresis. In four patients in whom immunochemical studies indicated high levels of circulating immune complexes, the removal of 5-8 litres of plasma weekly produced a striking clinical and immunochemical improvement. The four other patients, with only minor complement disturbances and no direct evidence of circulating immune complexes, could not be shown to benefit from plasmapheresis and one patient in this group died of cerebral lupus despite intensive treatment with cytotoxic drugs. It is concluded that plasmapheresis may be of value as an adjuvant to the treatment of acute S.L.E.

Acute Disease↗
PubMed1976

The immunogenicity of starch glove powder and talc.

An antigen responsible for cutaneous delayed hypersensitivity to starch glove powder in guinea-pigs was found to be associated with starch grains. Talc was not immunogenic in this system, and did not cross-react in skin tests with starch glove powder. Additives and protein components in the glove powder did not appear to be antigenic.

Animals↗
PubMed1976

Allergic starch peritonitis in the guinea-pig.

An experimental starch peritonitis in guinea-pigs previously immunized with starch glove powder and Freund's complete adjuvant is described. After peritoneal challenge by 10 mg starch glove powder, 22 per cent of the animals developed florid omental granulomas resembling those found in some patients with post-operative glove powder peritonitis. It is suggested that delayed hypersensitivity to a component of the glove powder may be responsible for the clinical features of starch peritonitis in man.

Animals↗
PubMed1976

The renal handling of insulin and thyroid hormones in normal man.

1. The renal extraction of insulin and thyroid hormones T3 and T4 was studied in man by right renal vein catheterization. 2. The mean renal extraction of insulin was 0-46, suggesting that the right renal vein should be utilized in comparable studies. 3. No renal extraction of thyroid hormones was detected.

Adult↗
PubMed1976

Effects of noradrenaline on consecutive vascular segments at low or normal calcium concentrations in control and spontaneously hypertensive rats.

1. An 'isogravimetric' technique, plus measurement of pressure in a small artery, was used to investigate the responses of upstream and downstream precapillary and postcapillary resistance vessels in the hindquarters of spontaneously hypertensive rats (SHR) and normal control rats perfused at constant flow. 2. Dose-response curves to noradrenaline were constructed under conditions of low or normal calcium. 3. In both control rats and SHR the dependence on external calcium during contraction increased peripherally, with the smaller pre- and post-capillary resistance vessels being most dependent and larger arteries least dependent. 4. There may be differences between SHR and control rats in regard to the handling of calcium, particularly in the small pre- and post-capillary resistance vessels.

Animals↗
PubMed1976

Necrotizing vasculitis: a circulating immune complex producing inflammatory skin lesions.

A patient with acute necrotizing vasculitis is described in whom tests for circulating immune complexes were negative. The patient's serum injected intradermally produced lesions which closely resembled those occurring spontaneously. When the serum was fractionated, the skin-reactive fraction was found to be associated with IgG, but was of a higher molecular weight than normal IgG. Immunofluorescent studies showed that lesions induced by this active fraction contained IgG and complement in the epidermal basement membrane zone and within the small dermal vessels. We conclude that an immune complex of relatively low molecular weight is present in the active fractions, and capable of initiating the lesions of acute necrotizing vasculitis.

Antigen-Antibody Complex↗
PubMed1976

Evidence for circulating immune complexes in erythema nodosum and early sarcoidosis.

Twenty-two patients were investigated during acute attacks of erythema nodosum with a series of tests for circulating immune complexes. Nineteen had bilateral hilar lymphadenopathy and were considered to have sarcoidosis. Evidence of circulating immune complexes was found in 18, out of 22 patients (including 15 out of the 19 cases of sarcoidosis). The most frequent abnormality was the detection of elevated levels of C3 breakdown products (C3i), which were found in 14 out of 18 tests. The test results returned gradually to normal as symptoms subsided in 20-40 days, but 2 patients still showed abnormalities at 40 days despite the disappearance of symptoms. It is concluded that free immune complexes appear in the circulation during the early stages of acute sarcoidosis and gradually disappear as symptoms subside.

Antigen-Antibody Complex↗
PubMed1976

Immune response to phi X 174 in man. 5. Primary and secondary antibody production in primary biliary cirrhosis.

In primary biliary cirrhosis, the primary immune response to the bacteriophage phi X 174 is normal but the secondary response is significantly reduced. The reduction is primarily of IgG antibody, while IgM is proportionately less affected. These changes may be the result of a reduction in helper T lymphocyte function and may contribute to the increase in the ratio of serum concentration of IgM to IgG.

Adult↗
PubMed1976

Mitral valve replacement in the presence of severe pulmonary hypertension.

Thirty patients with severe preoperative pulmonary hypertension (pulmonary artery pressure range 90-165 mmHg, mean 118 mmHg) were reviewed following single mitral valve replacement, with prosthetic valves, within the last 10 years (1964-74). The early and late mortality for this group was no different from that of the total series of mitral valve replacements performed over the same period. Marked postoperative clinical improvement was accompanied by corresponding radiological and electrocardiographic changes. In addition there was a statistically highly significant haemodynamic improvement in the 21 survivors (mean survival time 5 1/2 years). At recatheterization the mean pulmonary artery pressure was 41-5%, the mean wedge pressure 46-3%, and the transpulmonary gradient (PAm-LAm) 36-1% of the preoperative values. It is concluded that gross pulmonary hypertension is not per se a contraindication to mitral valve replacement surgery.

Adult↗
PubMed1976

The cortisol response during heart-lung bypass.

The response patterns of plasma cortisol and plasma free cortisol have been studied in 20 consecutive patients undergoing cardiac surgery involving the use of heart-lung bypass. Sixteen consecutive patients undergoing closed mitral valvotomy have been used as controls. Total plasma cortisol levels fell at the onset of extracorporeal circulation (ECC) and did not rise significantly throughout the period of ECC. The peak cortisol level in the bypass patients occurred at 24 hours postoperatively with elevated levels still present at 48 hours. This pattern was significantly different from the control patients (P less than 0.001) who exhibited the typical cortisol stress response pattern. Synthetic ACTH stimulation of the adrenal cortex during heart-lung bypass produced a positive response (i.e., a rise in plasma cortisol greater than 7.5 mug/100 ml) in all six patients studied while the six mitral valvotomy patients had no response to synthetic ACTH administration during operation (P less than 0.01). Plasma free cortisol estimations indicate that a rapid and significant rise in % free cortisol occurred at the onset of ECC, but that despite the rise in percentage free, the overall plasma free cortisol concentration (i.e., total plasma cortisol X % free) was significantly lower during ECC in the bypass patients when compared with control (P less than 0.01). Twenty-four hours postoperatively these concentrations were significantly higher in the bypass patients (P less than 0.001).

Cardiac Surgical Procedures↗
PubMed1976

Effects of acutely induced hypertension in cats on pial arteriolar caliber, local cerebral blood flow, and the blood-brain barrier.

Acute hypertension was induced in 19 anesthetized cats by the intravenous administration of angiotensin. The caliber of pial arteries was measured by a television image-splitting technique and local cerebral blood flow by the hydrogen clearance technique. As the blood pressure was increased, pail arterioles constricted and cerebral blood flow remained relatively constant, showing that autoregulation of cerebral blood flow was intact. At mean arterial pressures of more than 170 mm Hg arteriolar dilation appeared. In smaller arterioles (initial diameter less than 100 mum) a segmental dilation (the "sausage'string" phenomenon) frequently preceded uniform dilation. This arteriolar dilation was associated with a marked increase in local cerebral blood flow indicating that the upper level of autoregulation had been breached. In no cat was vasospasm or a decrease in blood flow observed during induced hypertension. Hypertension also caused dysfunction of the bloodbrain barrier since, in 17 out of 19 of the cats examined, there was extravasation of protein-bound Evans blue into brain tissue. In only one of the 19 cats subjected to neuropathological analysis was ischemic brain damage identified and this was restricted to minimal ischemic cell change. The results indicate that severe, induced hypertension in cats produces cerebral arteriolar dilation, an increase of cerebral blood flow, and dysfunction of the blood-brain barrier. These observations may be of importance in understanding the pathogenesis of hypertensive encephalopathy.

Animals↗
PubMed1976

Lower limit of cerebral blood flow autoregulation in experimental renovascular hypertension in the baboon.

The effect of chronic renovascular hypertension on the autoregulation of cerebral blood flow was studied in anesthetized baboons. Cerebral blood flow was measured by the intracarotid 133Xe clearance method. Six baboons with renal hypertension of 8-12 weeks' duration were compared with six normotensive controls. The lower limit of autoregulation was determined following controlled hemorrhage. In the initially normotensive baboons, cerebral blood flow remained constant until mean arterial pressure had decreased to the range of 45-59 mm Hg. Thereafter, cerebral blood flow decreased with each further decrease in mean arterial pressure. In the chronically hypertensive baboons cerebral blood flow autoregulated until the mean arterial pressure had decreased to the range of 75-89 mm Hg. Therefore, the lower limit of autoregulation of cerebral blood flow was shifted to higher absolute levels of mean arterial pressure in baboons with chronic renovascular hypertension presumably due to adaptive changes in the cerebral circulation.

Animals↗