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Biomedical subjects

D J Warren

Publications and source records attributed to D J Warren.

At least 91 records · Page 5Linked to original sources
PubMed1981

The effect of indapamide on muscle blood flow in hypertensive patients.

The effect of indapamide on the peripheral circulation was investigated in hypertensive patients using a xenon washout technique. Resting muscle blood flow increased by 38% after 1 week's treatment in 5 patients and by 52.6% after 6 weeks treatment in 4 patients. Exercise muscle blood flow increased by 18% in 4 patients after 6 weeks' treatment. Resting supine and standing blood pressure was decreased by indapamide after 2, 4 and 6 weeks of treatment. Exercise systolic blood pressure was not changed by indapamide. The results in this pilot study suggest that peripheral resistance is reduced by a direct action on the vessel wall.

Antihypertensive Agents↗
PubMed1980

Familial gout and renal failure in young women.

Six members of kindred with only one surviving male in three generations, a history of an unusual combination of precocious gout in a girl of nine and rapidly progressive renal disease in young women, have been investigated. Sensitive indicators of the familial defect were the early development of hyperuricemia, an inability to concentrate the urine, and a patchy non-specific interstitial nephritis at biopsy. All these features were disproportionately severe for the young age and sex of affected subjects, and the relatively moderate reduction of GFR in some. Identification of these characteristics enabled the recognition of an early stage of the disease in one young family member whose renal function had previously been normal. The histopathology of the renal lesion in this normotensive teenage girl was similar to that frequently attributed to ageing or hypertension in the archetypal middle-aged gouty male, indicating that neither age nor vascular lesions are necessarily implicated in the latter. Allopurinol has halted further progression of the renal lesion in this young girl over two years. It is thus possible that early diagnosis may benefit the subsequent clinical course and may be important since the number of such families in our experience suggests that precocious familial gout with renal failure is more prevalent than currently recognized.

Acute Kidney Injury↗
PubMed1979

Modification of the normal postural changes in plasma renin activity by the application of positive pressure to the legs.

In six normal male subjects plasma renin activity (PRA) rose progressively on standing over a 2 hour period. PRA fell to basal levels after a further 2 hours of recumbency. The rate of rise of PRA on standing was largely abolised following the application of an anti-gravity ('G') suit. Continuous monitoring of blood pressure (BP) heart rate (HR) and packed cell volume (PCV) suggest that it is the fall in effective blood volume which elicits the stimuli to renin release during changes in posture.

Adult↗
PubMed1979

Acute proliferative glomerulonephritis with crescents and renal failure in pregnancy successfully managed by intermittent haemodialysis. Case report.

A 26-year-old patient with no previous history of renal disease developed acute non-streptococcal crescentile glomerulonephritis with severe renal failure in the 17th week of her second pregnancy. It became necessary to treat her with haemodialysis to maintain the blood urea around 25 mmol/l. The haemoglobin was maintained above 9 g/dl with regular blood transfusion and the blood pressure was controlled with hypotensive drugs. Measurement of fetal biparietal diameter and human placental lactogen indicated normal fetal growth and placental function. The patient spontaneously delivered a healthy infant at 32 weeks. Haemodialysis requirements decreased post partum and the patient even managed without dialysis for 12 weeks. Renal function, however, remained severely impaired and maintenance haemodilysis was again necessary at nine months post partum. Glomerulonephritis complicating pregnancy is reviewed and the management of acute and chronic renal failure in pregnancy is discussed.

Acute Disease↗
PubMed1978

Effects of propranolol and metoprolol on the peripheral circulation.

The effects of single doses of propranolol and metoprolol on skin temperature and skin and muscle blood flow were compared in 10 normal subjects and four patients with essential hypertension. In normal subjects the mean skin temperature fell by 1.30 +/- 0.62 degrees C 90 minutes after 80 mg propranolol and 0.15 +/- 0.05 degrees C after 100 mg metoprolol. Skin blood flow and resting muscle blood flow were not affected by metoprolol but fell significantly after propranolol. Both drugs reduced post-exercise muscle hyperaemia, propranolol by more than metoprolol. Similar changes were seen in the hypertensive patients. Propranolol should be used with care in patients with known vascular disease.

Blood Flow Velocity↗
PubMed1978

Renal vascular response to haemorrhage in the rabbit after pentobarbitone, chloralose-urethane and ether anaesthesia.

1. Total renal blood flow and its cortical distribution were measured by the microsphere technique before and after haemorrhage in conscious rabbits, and after haemorrhage in rabbits anaesthetized with pentobarbitone, chloralose-urethane or ether. 2. The average blood loss necessary to achieve a fall in systolic blood pressure to about 65 mmHg was 101 ml in conscious rabbits and 38, 90 and 118 ml in weight-matched groups of rabbits anaesthetized with pentobarbitone, chloralose-urethane and ether respectively. 3. After haemorrhage in conscious rabbits total renal blood flow fell by 25%, this fall being confined to the superficial renal cortex. 4. In rabbits subject to haemorrhage under pentobarbitone anaesthesia renal blood flow fell by a further 23% when compared with the conscious bled rabbits. This reduction in blood flow was confined to the superficial cortex. 5. Haemorrhage in the rabbits subjected to chloralose-urethane anaesthesia caused no significant change in renal blood flow, as compared with conscious bled rabbits. 6. Haemorrhage under ether anaesthesia was associated with a further 33% fall in total renal blood flow, as compared with conscious bled rabbits. This was associated with a fall of 32% and 34% in superficial and deep cortical blood flow respectively. 7. Animals subjected to general anaesthesia may be particularly susceptible to the renal haemodynamic effects of haemorrhage.

Anesthesia, General↗
PubMed1978

A comparison of methods for measurement of rectal potential difference in man: effects of rectal infusion of amiloride.

1. Two methods for measurement of rectal potential difference in man were compared. A saline-filled catheter technique gave more reproducible results and was better tolerated by patients than the solid probe technique. 2. Infusion of amiloride at a concentration of 4 x 10(-6) mol/l in saline produced a variable fall of potential difference in six normal subjects. Dose-response curves in two subjects showed that complete inhibition of rectal difference occurred at 4 x 10(-5) mol/l and 4 x 10(-6) mol/l respectively. 3. This finding provides additional evidence that rectal potential difference in man results from electrogenic ion transport across the mucosal epithelial cell.

Adult↗
PubMed1978

Successful pregnancy in a 44-year-old haemodialysis patient.

A 44-year-old patient had been treated by intermittent haemodialysis for almost three years when she presented with a 28-week pregnancy. Successful delivery of a healthy but small infant was achieved by Caesarean section at 36 weeks. The successful outcome of this pregnancy was attributed to close control of the haemoglobin concentration and blood chemistry, and to increased frequency of dialysis. The relative value of various chemical tests of fetal maturity in the presence of maternal renal failure are discussed.

Adult↗
PubMed1978

Nutritional blood flow to the limbs after access procedures.

We have measured the blood flow to skin and muscle in normal subjects, asymptomatic dialysis patients, and dialysis patients, and dialysis patients who complained of cold hands (symptomatic patients) in whom a radiocephalic fistula had been constructed. Mean skin blood flow in asymptomatic dialysis patients was identical to that in normal subjects. Skin blood flow in the fistula hand of symptomatic dialysis patients was greatly reduced but it was normal in the contralateral hand. Muscle blood flow at rest was lower in dialysis patients than in normal subjects, but was reduced still further in the fistula hand of symptomatic patients. Muscle hyperaemia in response to exercise was greatly impaired in the fistula hands of all patients, irrespective of symptoms. The haemodynamic consequences of arteriovenous fistulae may be a cause of pain, paraesthesiae, muscle wasting or claudication in dialysis patients.

Arteriovenous Shunt, Surgical↗
PubMed1975

Hyperuricaemic acute renal failure after epileptic seizures.

Seven patients admitted to hospital during or immediately after status epilepticus or recurrent episodes of grand-mal seizures had very high concentrations of uric acid in their blood at a time when the blood-urea was normal in five of them. The blood-lactic-acid was high in the five patients in whom it was measured. All of the patients developed reversible renal failure, and two required haemodialysis. The blood-uric-acid should be measured in patients who have had prolonged seizures, and the measures which might be taken in hyperuricaemic patients to prevent the development of acute renal failure include rehydration, alkalinisation of urine, and, where alkalinisation is impossible, haemodialysis.

Acute Kidney Injury↗
PubMed1975

Measurement of intrarenal blood-flow distribution in the rabbit using radioactive microspheres.

1. Total renal blood flow and its distribution within the renal cortex of the conscious rabbit were studied with radioactive microspheres of 15 and 25 mum diameter. 2. The reliability of the microsphere technique was influenced by microsphere diameter and number (dose). The optimum microsphere diameter for determination of flow distribution in the rabbit kidney was 15 mum and dose 100-150 000 spheres. 3. Spheres of 15 mum nominal diameter were randomly distributed within the renal cortex of adult rabbits. The larger spheres in batches nominally 15 mum in diameter in young rabbits and 25 mum diameter in adult rabbits were preferentially distributed to the superficial cortex. 4. In adult rabbits 15 mum diameter spheres lodged in glomerular capillaries. Larger spheres occasionally lodged in interlobular arteries causing intrarenal haemorrhage. 5. Microspheres of 15 mum caused a decrease in renal clearance of creatinine and of p-amino-hippurate when the total injection dose was about 200 000 spheres. These effects were greater when the injection dose was increased to 500 000 spheres. 6. The reduction in total renal blood flow observed with large doses of spheres largely reflected decreased outer cortical flow, as measured by a second injection of spheres, and confirmed by a decrease in p-aminohippurate extraction. 7. The reproducibility of multiple injection studies was limited by these intrarenal effects of microspheres. 8. Total renal blood flow measured in six rabbits in acute experiments by the microsphere technique was 107 plus or minus 12 (mean plus or minus SD) ml/min and by p-amino-hippurate clearance was 100 plus or minus 10 ml/min. 9. Total renal blood flow in twelve conscious, chronically instrumented rabbits was 125 plus or minus 11 ml/min, of which 92 plus or minus 6 ml/min was distributed to the superficial cortex and 33 plus or minus 4 ml/min to the deep cortex.

Animals↗
PubMed1975

Renal circulatory responses to general anaesthesia in the rabbit: studies using radioactive microspheres.

1. Total renal blood flow and its cortical distribution were measured by the radioactive microsphere technique in conscious rabbits and after anaethesia with pentobarbitone, chloralose-urethane or ether. 2. Pentobarbitone anaesthesia caused a fall of 26% in total renal blood flow, of 26% in superficial cortical flow, and of 24% in deep cortical flow. Sodium excretion rate fell by 33%. 3. Chloralose-urethane anaesthesia caused no change in total or regional renal blood flow, or in sodium excretion. 4. Ether anaesthesia caused an insignificant fall in total renal blood flow, but superficial cortical flow fell by 13% and deep cortical flow rose by 21%. Urinary sodium excretion fell by 65%. 5. Possible mechanisms for these changes in response to anaesthesia are discussed. 6. The effects of anaesthetic agents may influence the interpretation of published work on control mechanisms in the renal circulation.

Anesthesia, General↗
PubMed1975

Effects of beta-adrenergic receptor blockade on the renal vascular response to a low sodium diet in the rabbit.

1. The effect of propranolol on total and regional renal blood flow was measured in conscious rabbits after 6 days on normal or low sodium diets. 2. Propranolol inhibited the fall in total superficial cortical renal blood flow which occurred in response to the low sodium diet but did not influence renal blood flow in rabbits on a normal sodium diet. 3. Reduction and redistribution of renal blood flow in response to a low sodium diet appears to be mediated by a beta-receptor mechanism and may be a consequence of intrarenal release of renin.

Animals↗