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Biomedical subjects

J G Ledingham

Publications and source records attributed to J G Ledingham.

At least 91 records · Page 5Linked to original sources
PubMed1984

Acute renal failure due to leptospirosis: clinical features and outcome in six cases.

Six cases of severe leptospiral infection with renal failure are described. Five of the six patients had acute oliguric renal failure requiring dialysis. Renal function recovered over three weeks and by two months all patients had plasma creatinine levels less than 200 mumol/litre. The initial diagnosis of leptospirosis depended on clinical and epidemiological features because serological confirmation was not possible during the first week of the illness. All the patients had either high risk occupations or a history of exposure to external sources of infection. All had fever, myalgia, jaundice and muscle tenderness. Although bilirubin levels were high (greater than 350 mumol/litre in five) the elevations of aspartate transaminase and alkaline phosphatase levels, and prolongations of prothrombin times were relatively slight. Thrombocytopenia occurred in five of the six cases. Leptospira complement fixation tests were weakly positive or negative on admission in five cases but rose to significant levels subsequently. Penicillin treatment resulted in Jarisch-Herxheimer reactions in three cases. The important complications were: upper gastro-intestinal haemorrhage (five cases), thrombocytopenia less than 30 000 platelets/mm3 (four cases), atrial fibrillation (three cases), drowsiness with asterixis (four cases). All six patients were seriously ill and required intensive supportive therapy. All survived.

Acute Kidney Injury↗
PubMed1984

Resetting of pressure-natriuresis and frusemide sensitivity in spontaneously hypertensive rats.

We compared pressure-natriuresis in isolated perfused kidneys of spontaneously hypertensive rats (SHR), and age-matched controls, and studied the effect of frusemide on sodium excretion. Okamoto SHR and age-matched Wistar-Kyoto controls (WKY) were used. Conscious BP was measured in a tail artery cannulated before the experiment. Isolated kidneys were perfused at 37 degrees C and glomerular filtration rate, urinary sodium excretion (UNaV) and percentage sodium reabsorption (%TNa) were measured as mean perfusion pressure was increased in steps from 100 to 180 mmHg and repeated after addition of frusemide. At all perfusion pressures GFR and UNaV were lower in SHR and %TNa higher, consistent with a 50 mmHg rightward shift of the pressure-natriuresis relationship in SHR. However, at intrarenal perfusion pressure equal to MBP, sodium excretion was the same (2.9 microEq/min/g WKY; 2.7 microEq/min/g SHR). Subsequent response to frusemide was markedly reduced in SHR. We conclude that resetting of pressure-natriuresis in SHR compensates exactly for increased renal perfusion pressure. The mechanism by which these are so precisely linked is not known, nor is the reason for the blunted sensitivity to frusemide in SHR, but it is possible that Na-K-Cl cotransport in Henle's loop may be altered in this genetic model of hypertension.

Absorption↗
PubMed1983

Comparison of the kinetics and utilisation of D(-)-and L(+)-sodium lactate in normal man.

After infusion of sodium D(-)L(+)-lactate in healthy man the clearance of the D(-)-isomer from blood was 70% of that of the L(+)-isomer. Utilisation of L(+)-lactate may have been inhibited by the presence of the D(-)-isomer. The changes in blood pyruvate concentration and ketone body ratio were compatible with mitochondrial oxidation of D(-)-lactate to pyruvate. After infusion of a D(-)L(+)-lactate racemic mixture, the renal excretion of the D(-)-isomer was much greater than that of the L(+)-isomer, although peak blood concentrations of the L(+) were higher than those of the D(-)-isomer. After infusion of sodium L(+)-lactate, the renal excretion of D(-)-lactate increased 7 times, although no D(-)-lactate could be detected in the blood or in the sodium L(+)-lactate infused.

3-Hydroxybutyric Acid↗
PubMed1983

Calcium sensitivity and cardiac performance in genetic and renal models of hypertension.

We have compared cardiac performance, hypertrophy and sensitivity to calcium and verapamil of hearts of six to nine-month-old spontaneously hypertensive rats (SHR), two-kidney, one clip renal hypertensive rats (RHR) and age-matched controls. Cardiac output and heart rate were measured using an isolated perfused heart preparation. Mean blood pressure (BP) and heart weight were equally increased in SHR and RHR as was optimal left atrial filling pressure. Cardiac output was increased in both SHR and RHR at any given work load; this improvement was seen especially in SHR and at high aortic pressure (160 cm H2O) was significant in SHR but not RHR. In low [Ca2+], 0.6 mM, cardiac output of RHR and controls fell markedly, but changed little in SHR, whereas in high [Ca2+], 5.1 mM, cardiac performance deteriorated in SHR but was improved in RHR and controls. Verapamil 2 X 10(-7) M reduced Ca2+ responsiveness of RHR and controls threefold but had no effect in SHR. The results suggest there may be an abnormality of cardiac calcium utilization in inherited but not in acquired hypertension.

Animals↗
PubMed1982

Clinical experience with captopril in the treatment of severe drug-resistant hypertension.

Thirty-three patients aged 12 to 77 years with severe hypertension uncontrolled on maximal combination therapy (mean arterial pressure on treatment 149 +/- 4 mm Hg) were treated with captopril, 45 to 450 mg daily for up to 30 months. Renovascular lesions were present in 11 and other renal disease in a further 15, of whom 8 had undergone renal transplantation. Good control (mean blood pressure less than 110 mm Hg) was achieved in 11 patients and moderate control (mean blood pressure 110 to 130 mm Hg) in 13. Captopril was given with a diuretic agent in 13 patients, with a diuretic agent and a beta-adrenoreceptor blocker in 13, and with three or more other agents in 7, of whom 4 had undergone renal transplantation. Side effects of rash, fever and gastrointestinal symptoms were observed, but there were no adverse effects on renal function or leukocyte counts. Severe hyperkalemia (potassium level greater than 6.0 mmol/liter) occurred in four patients despite the use of furosemide and low potassium diet. There was no significant correlation between the long-term hypotensive response and the initial decrease in blood pressure during captopril therapy.

Adolescent↗
PubMed1982

A model of L(+)-lactate metabolism in normal man.

Mathematical models were used to study the elimination of L(+)-lactate during and after an intravenous load of unlabelled sodium L(+)-lactate in 20 normal postprandial subjects. Clearance of L(+)-lactate from blood was 17.9 +/- 1.1 ml (kg BW)-1 min-1 and the endogenous production rate of L(+)-lactate at rest was 1.38 +/- 0.16 mol (70 kg BW)-1 24 h-1. Clearance and production were unchanged after a 36-hour fast in 4 subjects. Renal excretion of L(+)-lactate accounted for less than 1.2% of the infused load. Clearance of L(+)-lactate was closely related to the pre-infusion concentrations of ketone bodies and alanine.

Adult↗
PubMed1982

Utilization of L(+) lactate in patients with liver disease.

Clearance of intravenously infused sodium L(+) lactate was slower in 37 patients with liver disease (14.5 +/- 0.9 ml (kg BW)-1min-1) than in 20 normal subjects (17.9 +/- 1.1 ml (kg BW)-1min-1). This difference is statistically significant (2p less than 0.0125). Impairment of L(+) lactate utilization was not related to the aetiology of the liver disease. Both increased production and decreased utilization of L(+) lactate were found in patients with secondary malignancy of the liver. Penetration of L(+) lactate into ascitic fluid was variable and estimates of L(+) lactate utilization may be unreliable if ascites is present.

Adult↗
PubMed1980

Captopril and frusemide in severe drug-resistant hypertension.

10 patients with severe refractory hypertension were treated with captopril and frusemide. All patients had uncontrolled blood pressure (mean arterial pressure > 140 mm Hg), and 7 had developed accelerated hypertension despite maximum conventional treatment. Captopril and frusemide controlled blood pressure in all 10 patients, without side effects in 9. There was a significant rise in plasma-potassium in 9 patients (1 mmol/l), and hyperkalaemia (plasma-potassium > 6 mmol/l) developed in 3 patients despite coincident treatment with frusemide.

Adolescent↗
PubMed1980

Total body potassium falls with age.

1. Plasma volume, 24 h urine sodium and total body potassium were similar among 89 previously untreated patients with mild hypertension and 89 control subjects matched for age and sex. 2. Total body potassium correlated with renin activity in both hypertensive patients and controls. 3. Renin activity and total body potassium fell significantly with age in both groups. 4. The relationship between renin and total body potassium was no longer present when the effects of age were allowed for in a partial correlation.

Aging↗
PubMed1980

Thirst following water deprivation in humans.

The effect of 24-h water deprivation and subsequent drinking on systemic fluid balance and subjective sensations has been determined in human beings. The deprivation caused significant intracellular and extracellular depletions, thirst, and a dry unpleasant tasting mouth. During rehydration, subjects drank 65% of their total intake within 2.5 min. The marked decrease in drinking rate thereafter, and the alleviation of thirst, occurred before plasma dilution had become significant. This attenuation of drinking was subjectively attributed to stomach fullness. Presystemic factors may therefore be important for drinking termination in humans. Within 20 min systemic deficits were removed, but intermittent drinking continued at a low rate, reportedly to alleviate unpleasant oral sensations, Following rehydration, the concentrated urine of hydropenia had disappeared. However, the excretion of solute-free water varied between subjects. Plasma renin activity was significantly elevated by water deprivation, while after rehydration this activity had decreased to levels not significantly different from predeprivation values.

Adult↗