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Biomedical subjects

J V Jones

Publications and source records attributed to J V Jones.

At least 19 recordsLinked to original sources
PubMed1979

Baroreflex control of blood pressure and plasma noradrenaline during exercise in essential hypertension.

1. Twelve subjects (mean age 46.3 +/- 12.5 years) with mild to moderate hypertension were studied before, during and after bicycle ergometer exercise. 2. Baroreflex sensitivity was determined by the Oxford phenylephrine method; sensitivity at rest was inversely related to intra-arterial pressure and age. Age and resting arterial pressure were not related. 3. Exercise for 5 min at 50 W and 5 min at 75 W raised the mean arterial pressure from 116.4 +/- 18.0 to 150.0 +/- 25.4 mmHg, the heart rate from 73.2 to 126.7 beats/min and the plasma noradrenaline from 541 +/- 142.7 to 1309.8 +/- 543.5 pg/ml (P less than 0.001). 4. The increase in noradrenaline during exercise and the maximum mean pressure achieved were inversely related to resting baroreflex sensitivity (r = -0.68 and -0.77 respectively). Resting values of noradrenaline were not related to baroreflex sensitivity, age, or resting blood pressure. 5. It is possible that the rise in both plasma noradrenaline and arterial blood pressure produced by exercise is controlled by the baroreceptor reflexes; these are less effective in hypertensive subjects and thus the increases in noradrenaline and arterial pressure during exercise are greater in subjects with raised blood pressure.

Adult↗
PubMed1979

Assessment of the antihypertensive effect of atenolol with 24 h ambulatory monitoring of blood pressure.

1. Twenty-four hour intra-arterial blood pressure measurements and electrocardiograms were obtained from 12 subjects with untreated essential hypertension. 2. The patients kept records of their activity, paying particular attention to times of retiring to bed, and times of waking in the morning. 3. All subjects were treated with a single daily dose of atenolol (50 to 200 mg) for between 2 and 9 months, and then underwent a second 24 h blood pressure study. 4. Arterial blood pressure was lowered significantly throughout the 24 h period with a single daily dose of atenolol.

Adult↗
PubMed1979

Evidence for a therapeutic effect of plasmapheresis in patients with systemic lupus erythematosus.

Fourteen patients with active systemic lupus erythematosus (SLE) have been treated with plasmapheresis at a rate of two litres daily on three to four days per week, over a period of two to three weeks. Plasma was replaced isovolemically with either fresh frozen plasma or with human plasma protein fractions. Ten patients were receiving treatment with prednisone at the time of plasmapheresis, and four had received no prior treatment. Eight patients showed evidence of either clinical improvement or clinical and immunochemical improvement, at the time of plasmapheresis. In the three patients who showed high levels of circulating complexes before treatment, there was a sudden fall in the level of circulating immune complexes, which was quantitatively greater than could be explained by the amount removed. This suggests that in some patients with SLE, clearance of complexes by the mononuclear phagocytic system is initially blocked by high levels of circulating complexes and that one effect of plasmapheresis may be to relieve this blockade. Five patients showed a clinical response to plasmapheresis despite the fact that tests for immune complexes were negative. Three patients showed no response to plasmapheresis, and three were regarded as unevaluable. In a limited number of patients, who show a high level of circulating immune complexes, and whose condition is deteriorating despite treatment with corticosteroids, there may be an important therapeutic role for plasmapheresis.

Adolescent↗
PubMed1978

Benzothiadazine diuretics and death from myocardial infarction in hypertension.

1. Case records were examined of 66 patients who died while being treated for high blood pressure. 2. The possibility that benzothiadazine diuretics may have some deleterious as well as beneficial effects was investigated. 3. It is possible that the thiazides may have some adverse clinical effects, at least in females, with regard to the incidence of myocardial infarction in hypertensive patients.

Adult↗
PubMed1978

Arousal and the circadian rhythm of blood pressure.

1. We have recorded ambulant intra-arterial blood pressure in five normo- and 14 hyper-tensive subjects over 24 h, particular attention being paid to the time of arousal. 2. The data were edited beat-by-beat before storing systolic, diastolic, and mean blood pressure +/- SD for every 2 min period on a computer file. 3. When pooled hourly mean data are plotted there is a rise of 52.9 mmHg systolic and 22.3 mmHg diastolic pressure from 03.00 hours to 11.00 hours in the 14 hypertensive subjects. 4. When the data are plotted in 20 min periods for the hours before and after arousal it is clear that the major rise in pressure occurs abruptly at that time. The 2 h period before arousal shows only a small rise in pressure, i.e. 6.9 mmHg systolic and 2.9 mmHg diastolic. 5. It is suggested that the apparent rapid early morning rise of blood pressure is an artifact of the method of analysis.

Arousal↗
PubMed1978

Effects of hypotension induced by halothane, on the cerebral circulation in baboons with experimental renovascular hypertension.

The effect of graded, progressive hypotension on the autoregulation of cerebral blood flow was studied in anaesthetized baboons with experimental renovascular hypertension. Graded hypotension was induced over a period of 5-6 h by the administration of increasing concentrations of halothane. In these chronically hypertensive animals cerebral blood flow remained constant until the mean arterial pressure had decreased to approximately 90 mm Hg. At mean arterial pressures of less than this value cerebral blood flow was pressure passive. At the completion of the investigation the brains were fixed by perfusion and submitted to neuropathological examination. Evidence of chronic hypertension and of ischaemic brain damage was found in every animal.

Animals↗
PubMed1978

Standardized stress and hypertension: comparison of effect of propranolol and methyldopa.

1 Using a standardized form of mental stress, 21 patients with idiopathic hypertension were investigated before and after treatment with placebo (n=8), propranolol (n=7) or methyldopa (n=6). 2 Blood pressure was satisfactorily controlled in the propranolol and methyldopa groups but only the propranolol group showed modification of the pressor response to stress testing. 3 These results suggest that propranolol may provide more uniform control of blood pressure than methyldopa in patients with essential hypertension.

Adult↗
PubMed1978

Cardiovascular reactivity and design in rats with experimental "neurogenic hypertension".

The arterial barorecptors were denervated in 20 normotensive Wistar rats. 2 1/2 months after the operation their cardiovascular responses to "mental stress" were compared to those of matched control rats (NCR). At the time of investigation the blood pressure of the baroreceptor denervated rats (BDR) was increased some 15 per cent above that of the control group. There was, however, no difference in response to "mental stress" between groups, if anything the BDR reponded with less pronounced tachycardia. Two months subsequent to the stress-test the men blood pressure of the BDR was still significantly above normal levels, but the BDR did not exhibit structural cardiovascular adaptation, which has been documented in most types of stable hypertension as a response to the increased mean blood pressure. The results imply that hypertension induced by baroreceptor denervation is not of a stable and persistent type in which case structural changes in the cardiovascular system would have developed within the observation period (approximately 4 months). Emotional stimuli, however, do not seem to contribute to periodic blood pressure increase at the time of measurement, as earlier suggested.

Animals↗