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Biomedical subjects

J Michael

Publications and source records attributed to J Michael.

At least 145 records · Page 8Linked to original sources
PubMed1983

Renal and pancreatic transplantation in the treatment of diabetic renal failure.

Twenty-two diabetic patients with renal failure have entered an integrated dialysis and transplant programme in 30 months. Ten have subsequently undergone combined renal and segmental pancreatic transplantation, and have been followed for between one month and 25 months. Currently 80 per cent of the kidneys and 40 per cent of the pancreatic grafts are functioning. Four of the 22 patients have died from myocardial disease. Pancreatic transplantation at the time of renal grafting in diabetics does not significantly increase morbidity, and currently offers a 40 per cent chance of freedom from exogenous insulin. The successful treatment of diabetic renal failure is not compromised by the addition of this developmental procedure.

Adolescent↗
PubMed1982

Distinguishing between discriminative and motivational functions of stimuli.

A discriminative stimulus is a stimulus condition which, (1) given the momentary effectiveness of some particular type of reinforcement (2) increases the frequency of a particular type of response (3) because that stimulus condition has been correlated with an increase in the frequency with which that type of response has been followed by that type of reinforcement. Operations such as deprivation have two different effects on behavior. One is to increase the effectiveness of some object or event as reinforcement, and the other is to evoke the behavior that has in the past been followed by that object or event. "Establishing operation" is suggested as a general term for operations having these two effects. A number of situations involve what is generally assumed to be a discriminative stimulus relation, but with the third defining characteristic of the discriminative stimulus absent. Here the stimulus change functions more like an establishing operation than a discriminative stimulus, and the new term, "establishing stimulus," is suggested. There are three other possible approaches to this terminological problem, but none are entirely satisfactory.

Animals↗
PubMed1980

Zinc transport in normal human leucocytes: dependence upon media composition.

1. The transport of zinc has been studied in normal human leucocytes incubated in both a tissue culture medium and Krebs buffer. 2. 65Zn influx is characterized by an initial rapid phase followed by a slower influx. 65Zn influx is directly dependent upon the extracellular zinc concentration. 3. Net zinc influx could only be demonstrated in Krebs buffer at zinc concentrations in excess of 4.3 mumol/l and in tissue culture fluid at zinc concentrations in excess of 43.1 mumol/l. 4. A 65Zn efflux rate constant of approximately 1.0 per h was observed in both 4.3 and 15.4 mumol of zinc/l of Krebs buffer or tissue culture fluid. 5. In a zero external zinc Krebs buffer the 65Zn efflux rate constant fell to 0.57 per h and was accompanied by a small net zinc efflux.

Biological Transport↗
PubMed1980

Management of relative polycythaemia: studies of cerebral blood flow and viscosity.

Cerebral blood flow has been shown to be reduced in a group of patients with high packed cell volume due to a reduced plasma volume (relative polycythaemia). 500 ml of intravenous Dextran 40 resulted in a significant fall in PCV and whole blood viscosity with a concomitant rise in cerebral blood flow (CBF). This effect, however, lasted less than 24 h. Oral fludrocortisone therapy (0.2 mg daily) resulted in no definite change in either PCV, viscosity or CBF. Venesection brought about a significant fall in PCV and whole blood viscosity with a significant rise in CBF. Of the methods used, venesection was the only practical long-term method of lowering PCV in this group of patients.

Aged↗
PubMed1980

Red cell mass, plasma volume and blood volume before and after venesection in relative polycythaemia.

Seven male patients with relative polycythaemia have had red cell mass, plasma volume and blood volume measurements made before and after venesection. The mean PCV prior to venesection was 0.522. Using a small volume (250 ml) serial venesection technique, in each the PCV was reduced to or below 0.45, the overall mean value being 0.431. Venesection resulted in a rise in plasma volume with no significant reduction in blood volume in six of the patients. Thus hypovolaemia does not occur in the majority of the patients. One patient did not increase his plasma volume on packed cell volume reduction. His blood volume fell by 15%. None of the patients developed any symptoms of hypovolaemia. To maintain the PCV at values less than 0.45, venesection was required on average once every 2 months. It is suggested that venesection of small volumes is an acceptable long-term method of lowering the PCV in patients with relative polycythaemia.

Aged↗
PubMed1980

Shigella septicaemia following renal transplantation.

Two patients are described who developed septicaemia with Shigella flexneri following renal transplantation. Pre-operative screening had not identified either patient as a chronic carrier of Shigella sp. The acute management and problems posed by unrecognized carriers amongst patients undergoing transplantation in areas of the world where Shigella is endemic, are discussed.

Adult↗
PubMed1980

Immunoglobulins in cerebrospinal fluid in various neurologic disorders.

We determined the concentrations of immunoglobulins A, G, and M in cerebrospinal fluid of 16 patients suffering from multiple sclerosis, 13 with non-bacterial meningitis, 10 with stroke syndrome, and 13 with epilepsy. The differences in concentrations of immunoglobulins in these groups were remarkable in the patients with multiple sclerosis, meningitis, or stroke syndrome. We propose that the determination of the absolute immunoglobulin content in cerebrospinal fluid is of greater significance than the relative immunoglobulin concentration.

Central Nervous System Diseases↗
PubMed1978

Effect of zinc on leucocyte sodium transport in vitro.

1. In a preparation of human leucocytes maintained in tissue culture fluid, increasing the extracellular zinc concentration leads to a significant increase in both ouabain-sensitive sodium efflux and in sodium influx. 2. Cell water and sodium content do not alter significantly with increasing extracellular zinc concentration. 3. A small increase in the ouabain-insensitive sodium efflux can be demonstrated when the external zinc concentration is raised from 0.75 mumol/l to 90 mumol/l.

Biological Transport, Active↗
PubMed1978

Zinc and the sodium pump in uremia.

A defect in sodium transport is known to exist in the leucocytes of uremic patients. Recent work has shown changes in cation flux rates associated with alterations of extracellular zinc concentration. As plasma zinc is known to be low in uremia, the possibility that this might be the cause of the defect in membrane transport was investigated. Plasma zinc was shown to be lower in uremic patients than in normal controls but this was not matched by alterations in leucocyte zinc content. Leucocytes from normal subjects and from patients with uremia have similar increases in the sodium efflux rate constant when exposed to elevated extracellular zinc concentrations. However, the abnormality in leucocyte sodium transport in uremia was not completely corrected by elevation of the extracellular zinc, when compared with normal cells in the same zinc concentrations. Although extracellular zinc is a factor that must be controlled in studies of cellular membrane transport, a low plasma zinc is not the explanation for the defect of sodium transport seen in uremia.

Biological Transport↗