Biomedical subjects
Publications and source records attributed to G Mecca.
It is suggested that patients with the haemolytic-uraemic syndrome and related disorders (such as thrombotic thrombocytopenic purpura) lack a plasma factor which stimulates prostacyclin (P.G.I2) activity. Normal plasma would supply the missing factor and is a rational treatment for some life-threatening symptoms (thrombocytopenia, haemolytic anaemia, hypertension) of this syndrome.
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To determine whether the prolonged bleeding time so common to chronic renal failure (CRF) was due to defective factor VIII-related activities, as in von Willebrand's disease, vascular-factor VIII-related protein was measured in patients with CRF. Factor VIII-related protein was detected by immunofluorescence on the vascular intima of all 13 patients with CRF and greatly prolonged bleeding times. This protein was also present on the vascular intima of a patient with CRF and moderate von Willebrand's disease. These findings support a previous suggestion that the disturbed haemostasis in patients with CRF is not linked to defective factor VIII-related activities.
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Bleeding time, blood loss and platelet retention by glass beads, measured by standardized techniques, were significantly altered in a group of 30 non-thrombocytopenic patients with chronic renal failure undergoing maintenance haemodialysis. Bleeding time or blood loss did not correlate with platelet retention either before or after haemodialysis. No correlation could be found between the above tests and a number of biochemical parameters characterizing the uraemic condition. Haemodialysis only partially corrected the abnormal bleeding time, blood loss and platelet retention. These tests were still significantly different after haemodialysis from those of 30 normal subjects. It is suggested that some non-dialyzable material could play an important role in the aetiology of uraemic bleeding.
To determine the possible role of vascular factors in the bleeding tendency of uraemic patients, three major factors of the haemostatic system normally present in vascular tissues were studied. Factor VIII-related protein (F VIII) was detected on the vascular intima of 13 patients and 10 normal subjects. Comparable values of plasminogen activator (PA) were found in tissue slices from 7 patients and 7 controls. In contrast, prostacyclin like (PGI2) activity, measured as platelet aggregation inhibitory potency, was significantly higher in specimens from 15 patients with either acute or chronic uraemia than in 10 controls. The latter abnormality, leading to impaired platelet-vessel wall interaction, might contribute to the disturbed haemostasis of uraemic patients.
Congestive heart failure may frequently occur in patients with isolated coarctation of the aorta within the first six months of life. Renal failure is on the contrary a very rare pathologic sequela. This is caused by a low renal blood flow related either to a poorly developed collateral circulation or in those instances of preductal coartation to an early closure of ductus arteriosus. Peritoneal dyalisis is very effective in these critically ill infants both in correcting biochemical abnormalitics and in supporting cardiac performance. Surgical treatment is however the only way to restore normal renal blood flow and good cardiac output. This report describes two patients with isolated coarctation of the aorta in whom renal failure developed within the first two months of life. Both patients were successfully treated by peritoneal dyalisis and subsequent surgical intervention.
Plasma free carnitine in 6 chronic uremic patients fell 73% during hemodialysis. The recovery time was 6 h with placebo and only 2 h when dl carnitine (3 g oral) was taken at the end of dialysis.
The involvement of peripheral motor and sensory nerve, at least on a subclinical level, is nearly constant event with chronic renal failure. The study of the motor and sensory propagation velocity indicates that a widespread functional lesion of the axon with a peripheral point of attack and secondary demyelination, may be the basic pathogenetic event of uremic polyneuropathy. Prolonged hemodialytic treatment is substantially unable to influence the evolution of uremic polyneuropathy. The electrophysiological follow-up study of the peripheral nerve does not seem to be an index of adequate dialysis.
Specimens of venous tissue from three normal subjects and three patients with renal failure and very prolonged bleeding-times showed prostacyclin-like activity (inhibition of platelet aggregation) during incubation at room temperature. The specimens from all three uraemic patients showed more prostacyclin-like activity than those from the controls. After repeated washings, when this activity could hardly be detected in the controls, pronounced inhibitory activity was still evident in samples containing venous tissue from the three uraemic patients. These findings may be relevant to the pathogenesis of bleeding in renal failure.
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Normal or increased concentrations of factor VIII procoagulant activity (VIIIC), factor VIII-related antigen (VIIIRA), and factor VIII-von Willebrand activity (VIIIVWF) were found in the predialysis plasma of 10 out of 11 patients with chronic renal failure (CRF). All patients had a bleeding time longer than 15 minutes and platelet retention to glass beads lower than 40%. The only patient who had reduced concentrations of all three factor VIII complex components was subsequently shown to have von Willebrand's disease. In four patients with CRF, very low platelet retention, and slightly prolonged bleeding time none of the three factor VIII COMPLEX COMPONENTS WERE SELECTIVely modified in predialysis samples. These findings suggest that the bleeding tendency common in CRF is not necessarily linked to defective plasma factor VIII-related activities.
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The plasma lipid pattern was investigated in 103 dialysis patients and 66 renal transplant patients. Only 32 percent of dialysed patients and 30 percent of transplanted patients had a normal lipid pattern. In other patients the most frequent disorder with hypertriglyceridaemia, and less frequently combined or isolated hypercholesterolaemia. Since these lipid abnormalities are known to predispose to an accelerated atherosclerosis, a dietetic therapeutic approach was tried. Fifteen transplanted patients with severe hypertriglyceridaemia were submitted to a hypocaloric (1700 kcal) and low carbohydrate (130 g) diet. During dieting the plasma lipid pattern was normalised and maintained in a normal range for the period of observation (3-12 months).