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Biomedical subjects

A D Cumming

Publications and source records attributed to A D Cumming.

At least 37 records · Page 2Linked to original sources
PubMed1992

Effect of diclofenac on renal function and prostacyclin generation after surgery.

We have examined the effect of diclofenac on renal function after major surgery in a randomized, double-blind, controlled study of 20 patients undergoing oesophagogastrectomy. Diclofenac 75 mg or placebo was given i.m. 12-hourly for 2 days. I.v. fluid administration was standardized. Renal function was assessed by fluid balance and measurement of serum creatinine and electrolyte concentrations, creatinine and free water clearance, and urinary sodium and potassium excretion. Urinary 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) was measured by radioimmunoassay to assess renal prostacyclin production. After surgery, 6-keto-PGF1 alpha production increased, but this did not occur with diclofenac. On the first day after surgery, use of diclofenac was associated with a decreased urine flow rate, decreased urinary sodium and potassium excretion and a tendency to hyperkalaemia. Frusemide was required more often in the diclofenac group. One patient was withdrawn from the diclofenac group because of impaired renal function. Urine flow rate and blood potassium concentration should be monitored if diclofenac is used after major surgery.

Aged↗
PubMed1992

Hemodynamic, renal, and hormonal actions of aprotinin in an ovine model of septic shock.

BACKGROUND AND METHODS: Previous studies documented activation of protease enzymes such as the plasma kallikrein-kinin system in endotoxemia and sepsis, both in experimental animals and in patients. We investigated the actions of aprotinin (a protease inhibitor that binds to plasma kallikrein) on systemic hemodynamics and renal function, in an ovine model of septic shock. Aprotinin was infused intravenously in high dosage (1 x 10(6) kallikrein inhibitor units [KIU] loading, 200,000 KIU/hr), commencing 30 mins after surgical induction of sepsis (cecal ligation and puncture). RESULTS: In the control group (n = 6), there were significant decreases with time in BP and systemic vascular resistance, an increase in pulmonary artery pressure, reductions in creatinine clearance and sodium excretion, and an increase in plasma renin activity. In aprotinin-treated animals (n = 6), none of these changes occurred. There were significant between-group differences (controls vs. treatment) for mean arterial pressure, pulmonary artery pressure, and plasma renin activity. CONCLUSIONS: In this large animal model of septic shock, which reproduces the important features of clinical sepsis, treatment with aprotinin after the initiation of sepsis appears beneficial in relation to systemic hemodynamics, renal function, and hormonal stimulation, with no evidence of adverse effects.

Analysis of Variance↗
PubMed1992

Vasoactive effects of aprotinin.

The protease inhibitor aprotinin was given a) in experimental septic shock, and b) in patients with hepatic cirrhosis and ascites, since in both conditions, activation of the plasma kallikrein-kinin system is associated with pathological systemic vasodilatation, which may trigger reflex neuroendocrine activation and renal solute retention. Given early in experimental sepsis, aprotinin maintained the arterial pressure, systemic vascular resistance (SVR), creatinine clearance and sodium excretion, all of which fell in controls. Aprotinin also blocked increases in pulmonary artery pressure and plasma renin activity (PRA). Given late in sepsis, aprotinin caused a rapid rise in arterial pressure and SVR towards baseline levels. In cirrhosis, aprotinin increased SVR in patients with low baseline values, and improved glomerular filtration rate, renal plasma flow and sodium excretion in all subjects; PRA was suppressed by aprotinin. Aprotinin reverses pathological systemic vasodilatation in these two conditions, and this is associated with a reduction in renin release and improved renal function.

Animals↗
PubMed1992

Portal and systemic hemodynamics and humoral factors in cirrhosis with and without ascites.

The pathogenesis of salt and water retention in cirrhosis remains unclear. Systemic and portal hemodynamic parameters, including cardiac output, portal pressure gradient and systemic vascular resistance, were measured in six patients with untreated ascites and in six patients with hepatic cirrhosis with no history of ascites. Renal blood flow, urinary volume, and humoral factors, including plasma renin, aldosterone, angiotensin II, and urine kallikrein, were measured. Significant differences were seen between the two groups in urine volume, urine sodium and fractional sodium excretion, plasma angiotensin II, and the ratio between plasma renin activity and urinary kallikrein excretion (PRA:UKallV). A strong correlation existed between urinary sodium excretion and the PRA:UKallV ratio. No significant differences were detected between the groups in portal, renal, and systemic hemodynamics. The present results suggest that humoral changes occur early in ascites. Altered relationships between intrarenal hormone systems, such as the renin-angiotensin and kallikrein-kinin systems, may be important in salt and water retention.

Ascites↗
PubMed1991

Influence of the plasma protein concentration on renal function.

1. The effect of the plasma protein concentration on renal function remains controversial. Most, but not all, experimental studies suggest that a reduced plasma protein concentration perfusing the kidney may reduce tubular sodium reabsorption. Hypoproteinaemic disease states are usually associated with sodium retention, which is not always volume-dependent. 2. We induced a 21% and 24% reduction in plasma total protein and plasma albumin, respectively, in unanaesthetized sheep by acute extracorporeal plasmapheresis. Arterial pressure did not change, and changes in circulatory volume were minimised by infusion of crystalloid to maintain pulmonary artery occlusion pressure, measured using a Swann-Ganz pulmonary artery catheter. 3. After plasmapheresis, there was no significant change in creatinine clearance, sodium excretion, plasma renin activity or urinary kallikrein excretion. 4. After plasmapheresis, there was no significant reduction in plasma osmolality, increase in urine osmolality and fall in free water clearance. 5. The results suggest that in the absence of detectable changes in circulating volume or arterial pressure, acute hypoproteinaemia is associated with significant changes in renal water handling, but has no direct effect on sodium excretion or on renal release of renin and kallikrein.

Acute Disease↗
PubMed1989

Sheep-acquired severe Chlamydia psittaci infection in pregnancy.

There have been five confirmed cases of severe Chlamydia psittaci infection during pregnancy, three having been treated in Edinburgh, Scotland. The most recent case is presented and previous experience is reviewed. The illness usually causes thrombocytopenia with disseminated intravascular coagulation, renal failure and hepatic dysfunction during the late second and early third trimester. The outcome for the fetus is usually fatal and the infection only resolves after delivery or abortion. The main hope is for education to prevent infection occurring in susceptible populations.

Abortion, Incomplete↗
PubMed1989

The protective effect of thromboxane synthetase inhibition on renal function in systemic sepsis.

To study the role of thromboxane in systemic sepsis and renal failure, peritonitis was induced surgically in 22 sheep, leading to local and systemic sepsis. A selective thromboxane synthetase inhibitor, U63,557A (Upjohn Co, Kalamazoo, MI) was given before surgery in five animals and 30 minutes after surgery in five animals. A typical picture of volume-loaded, normotensive, vasodilated septic shock developed in all animals. Twenty four hours after induction of sepsis, the control group showed a marked reduction in glomerular filtration rate (GFR), urine volume, and urinary sodium excretion. Pretreated animals showed no change in GFR and a smaller reduction in urine volume and sodium excretion. The posttreatment group showed no change in any parameters of renal function. Plasma renin activity, urinary TXB2 excretion, and urinary 6-keto PGF1 alpha excretion increased after 24 hours only in the control group. Urinary TXB2 excretion was reduced by 80% in animals given U63,557A before surgery. The results indicate a significant protective effect of U63,557A on renal function during septic shock, probably related to reduced thromboxane synthesis, with no apparent deleterious systemic effects. The results support a role for thromboxane in the pathogenesis of acute renal failure in systemic sepsis.

Animals↗
PubMed1989

The kallikrein-kinin and renin-angiotensin systems in nephrotic syndrome.

We previously found that virtually all patients with nephrotic syndrome (NS) excrete supranormal amounts of urinary kallikrein; it is known that activity of the renin-angiotensin system (RAS) is increased in some such patients. We therefore studied the relationship between urinary kallikrein excretion (UKa) and plasma renin activity (PRA) in 16 patients with NS. Compared with healthy controls, PRA was normal in 8 subjects and elevated in 8; UKa was elevated in the high-renin group (40.4 +/- 5.2 nkat/24 h, normals 12.0 +/- 1.1). UKa was also elevated in the normal renin group (25.7 +/- 2.4 nkat/24 h) but to a significantly lesser degree. Significant activity in plasma against a specific substrate of glandular and renal kallikreins was observed in 8 of 10 patients with NS. Such activity was not found in plasma of 17 patients with glomerulonephritis without NS, or in 10 healthy controls. The results are in keeping with previous suggestions of a functional link between the renal kallikrein-kinin system (KKS) and the RAS, but indicate that the renal KKS is activated in NS, in some cases independently of the RAS. It is possible that renal kallikrein reaches the systemic circulation in some patients with NS.

Adult↗
PubMed1988

The acute renal haemodynamic and endocrine response to felodipine in normal man.

Felodipine (0.075 mg/kg p.o.), a calcium antagonist, was given to 9 male volunteers, with and without indomethacin pretreatment. Diuresis and natriuresis occurred after felodipine without significant change in effective renal plasma flow or glomerular filtration rate. There was no significant change in urinary 6 keto PGF 1 alpha or urinary kallikrein excretion and indomethacin did not inhibit the natriuretic or diuretic response to felodipine. The felodipine induced diuresis and natriuresis appears most likely to be mediated by an action of the drug on renal tubules.

Adult↗
PubMed1988

Vasoactive hormones in the renal response to systemic sepsis.

The pathophysiology of renal dysfunction in generalized sepsis remains unknown. In this study, 24 hours after surgical induction of peritonitis in 20 volume-loaded sheep, three patterns of renal function were seen. In group 1 (n = 8), glomerular filtration rate (GFR) decreased by 70%, urine volume by 85%, absolute sodium excretion by 95%, and fractional sodium excretion by 83%. Group 2 (n = 4) exhibited similar sodium retention but GFR did not fall. Group 3 (n = 8) showed no change in GFR or urine volume and only minimally reduced sodium excretion. Mean arterial pressure fell 17% in group 1 only; central venous pressure, pulmonary capillary wedge pressure, and plasma volume were maintained at or above presepsis values in all groups. Cardiac index was either increased or unchanged, and renal plasma flow was maintained in all groups; there was thus no hemodynamic evidence to suggest volume contraction. Histologic examination showed only minor changes with no consistent pattern. Renal functional changes correlated with other manifestations of severe sepsis--GFR and sodium retention correlated significantly with increased cardiac index, decreased systemic vascular resistance, pulmonary arterial hypertension, leukopenia, hypoproteinemia, and hypoglycemia. All of these changes were most marked in group 1. In groups 1 and 2, plasma renin activity (PRA) increased and urinary kallikrein excretion decreased. PRA correlated inversely with GFR, urine volume, and sodium excretion; urinary kallikrein excretion correlated positively with urine volume and sodium excretion. Urinary excretion of 6-keto-PGF1 alpha was increased in groups 1 and 2 and correlated inversely with mean arterial pressure in group 1 animals. During sepsis, urinary thromboxane B2 excretion continued at presepsis values in all groups. The results suggest that unusual reciprocal changes in activity of the renin-angiotensin and renal kallikrein-kinin systems may play a role in the renal response to sepsis. PGI2 synthesis is increased and may affect systemic hemodynamics and renal function; the role of thromboxane A2 in this context is unknown.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

Association between renal and sympathetic responses to nonhypotensive systemic sepsis.

We investigated the association between plasma catecholamines and the renal response to nonhypotensive sepsis. Arterial plasma catecholamines were measured in 16 sheep, before and 24 h after surgical induction of peritonitis. Animals were volume loaded with lactated Ringer's solution (8 L/24 h) before and after surgery; non became hypotensive. For analysis, animals were retrospectively divided into those with increased serum creatinine after 24 h of sepsis (group 1, n = 8) and those without (group 2, n = 8). Group 1 showed increased cardiac index and decreased systemic vascular resistance typical of severe sepsis, with decreased glomerular filtration rate (GFR), oliguria, sodium retention, increased plasma renin activity (PRA), decreased urinary kallikrein excretion, and increased urinary 6-keto-prostaglandin-F1 alpha excretion. Group 2 showed insignificant hemodynamic disturbance, and no significant renal response. Plasma catecholamines were equal in both groups at baseline. In group 1, there were uniform increases after 24 h in plasma norepinephrine (474 +/- 115 to 1183 +/- 158 [SEM] pg/ml; p less than .01) and plasma epinephrine (108 +/- 8 to 309 +/- 70 pg/ml; p less than .05). In group 2, neither plasma norepinephrine (343 +/- 59 to 330 +/- 56 pg/ml) nor plasma epinephrine (116 +/- 16 to 116 +/- 13 pg/ml) changed significantly. Plasma norepinephrine correlated inversely with GFR; plasma epinephrine correlated with PRA. The sympathetic nervous system may be involved in the renal response to nonhypotensive sepsis, both directly and via effects on other vasoactive hormone systems.

Acute Kidney Injury↗
PubMed1987

Acute effect of a thromboxane synthetase inhibitor on renal function in unanaesthetized sheep.

1. Eleven healthy, unanaesthetized sheep were given either a single intravenous bolus infusion of U63,577A (Upjohn), a selective thromboxane synthetase inhibitor, at a dose of 30 mg/kg (group 1, n = 6), or vehicle alone (group 2, n = 5). Animals were maintained in metabolic cages during the study, and received 150 ml of water/h and 7.5 mmol of sodium/h as Ringers lactate by intravenous infusion for 24 h before and during the study. During two 1 h control urine collections via bladder catheter, urine volume and sodium excretion closely paralleled these infusion rates. 2. In the first hour after injection of U63,577A, there were significant two- to three-fold increases in urine volume, urinary sodium excretion and fractional sodium excretion, compared with the control collections. During the subsequent 4 h, urine volume, urinary sodium excretion, and fractional sodium excretion fell to values significantly lower than in the control period. Creatinine clearance was reduced 1, 2 and 4 h post injection and returned to control values at 5 h. Urinary excretion of thromboxane B2 was significantly reduced compared with control values during the 5 h after injection of U63,577A. Excretion of 6-keto-prostaglandin F1 alpha did not change. Plasma renin activity was significantly increased 1, 3 and 5 h after injection of U63,577A. Vehicle controls showed no change in any of the above parameters. 3. The results indicate that in healthy conscious sheep, sodium and water replete, U63,577A has a transient but significant diuretic and natriuretic effect, followed by sodium and water retention and increased plasma renin activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Abnormal diurnal urinary sodium and water excretion in diabetic autonomic neuropathy.

1. Diurnal patterns of urine output and sodium and potassium excretion were studied in 10 diabetic patients with and 10 without autonomic neuropathy, and in 10 normal subjects. 2. The diurnal patterns of excretion in the diabetic patients with autonomic neuropathy differed significantly from the two other groups, as a smaller proportion of the 24 h output of urine, sodium and potassium was excreted during the day and a larger proportion was excreted at night. 3. Similar changes were noted in the diurnal patterns of urinary kallikrein excretion in diabetic patients with autonomic neuropathy, and urinary kallikrein output correlated significantly with urine volume but not with urinary sodium excretion. 4. The diurnal patterns of excretion of urinary prostaglandin E2 and 6-keto-PGF1 alpha were not significantly different in diabetic patients with autonomic neuropathy. 5. Nocturia was a common complaint in this group, and the number of nocturnal voidings correlated with night urine volume. There was no evidence of premature bladder emptying. 6. The changes observed in the day/night urine output and sodium excretion could not be explained by glycosuria, insulin regimens, impaired renal function or abnormal diurnal prostaglandin excretion; their possible relevance to the diurnal changes of urinary kallikrein excretion is discussed.

6-Ketoprostaglandin F1 alpha↗