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Biomedical subjects

F Thomas

Publications and source records attributed to F Thomas.

At least 325 records · Page 18Linked to original sources
PubMed1976

Solitary kidney and ageing as causes of low renin and aldosterone concentrations: relevance to "low-renin" essential hypertension.

1. As experimental models of reduced nephron population in man, (a) twelve men aged 15-32 years who had one kidney removed 1-13 years previously and (b) fourteen normotensive men aged 70-90 years were studied. Results were compared with those in eighteen normotensive men aged 18-28 years and eleven men aged 19-33 years with essential hypertension. 2. While the subjects followed a routine of normal diet and daily activity, measurements were made, after overnight recumbency and in the fasting state, of plasma volume and renin activity on one occasion in hospital and of blood pressure on five to fourteen occasions in the home. Blood pressure was also measured after standing for 2 min and plasma renin activity after 1 h standing, sitting or walking. Twenty-four hour urinary aldosterone excretion was also measured. 3. The measurements were repeated in the normotensive subjects and subjects in (a) and (b) above after 10 days of sodium-restricted diet (40 mmol of sodium/day). 4. The mean plasma renin activity (recumbent) in essential hypertensive subjects was higher than in normotensive subjects. In subjects of (a) and (b) above, it was lower than normotensive subjects, and was not increased by dietary sodium restriction in subjects of (a). 5. The mean aldosterone excretion level was lower in old normotensive subjects than in the other groups, and increased in each group after dietary sodium restriction. 6. Mean plasma volume/surface area was not different between the four groups and in normotensive, essential hypertensive and nephrectomized subjects but not subjects aged 70-90 years was negatively correlated with standing diastolic blood pressure.

Adolescent↗
PubMed1976

Use of plasma protein fraction in preservation of cadaveric kidneys.

We have compared 23 cadaver kidneys preserved with cryoprecipitated plasma (CPP) with 23 consecutive cadaver kidneys preserved with plasma protein fractions (PPF). In both groups the MOX-100 Waters machine was used. The PPF solution does not contain any fibrinogen or gamma globulin. The harvesting characteristics of both groups were comparable. Pulsatile perfusion time in the PPF group was up to 46 hours and in the CPP group was up to 44 hours. In the PPF group, 20 kidneys achieved immediate function upon transplant (85 percent). Two underwent periods of acute tubular necrosis (ATN) and one kidney never worked. In the CPP group, 18 kidneys achieved immediate function (78 percent). Two underwent periods of ATN and three never achieved satisfactory function. From this clinical experience, PPF is as effective as CPP for the preservation of kidneys up to 44 hours prior to transplant. The advantages of the PPF are easy availability, long shelf life, simple preparation, low cost, freedom from risk of hepatitis, and theoretical absence of antibody against the kidney. Graft and patient survival at 6 months showed no statistical difference.

Adolescent↗
PubMed1976

Monitoring and modulation of immune reactivity in human transplant recipients.

In this study parameters of humoral antibody (HA) and cell-mediated immunity (CMI) were measured before and after transplant in 44 renal transplant patients. The results indicated that, before transplant, CMI parameters but not HA measurements correlated with early graft rejection crises. In antithymocyte globulin (ATG)-treated patients, a striking loss of early rejection activity occurred which correlated with ablation of T cells in the peripheral blood. ATG-treated patients also had a marked loss of T cell reactivity, as measured by phytohemagglutinin (PHA) blastogenesis and these parameters also correlated with allograft reactivity. Concanavalin A (Con-A) reactivity, however, did not correlate well with early rejection activity. Triple drug therapy with ATG, but not prednisone-Imuran therapy, caused a marked fall of T cell levels and reactivity within hours of the first dose of ATG. None of the ATG-treated patients had irreversible or progressive rejection in the first month after transplant and only 32 percent of patients had rejections, of which more than 70 percent were Type I. A "permissive" level of T cells of about 20 percent of normal was associated with over 95 percent of acute rejection crises, whereas no correlation of a variety of humoral antibody parameters and rejection has been seen in our unit. These studies suggest a primary role of the T cell in early allograft reactivity and indicate that future immunosuppressive techniques for human transplantation should be directed toward effective monitoring and modulation of T cell levels and reactivity in the early post-transplant period.

Antibodies↗
PubMed1975

Studies of thymus-derived and bone marrow-derived lymphocytes in renal transplant patients.

Serial studies of levels and responsiveness of T and B lymphocytes were performed in human renal allograft recipients. Patients given prednisolone-azathioprine immunosuppression had only mild falls in levels and responsiveness of T cells. Patients given a quality controlled ATG preparation had marked and relatively selective falls in levels of T cells associated with a marked fall in T cell responsiveness as measured by PHA and Con-A responsiveness. In vivo correlates of this severe T cell deficiency suggest that T lymphocytes are central to acute allograft rejection and that acute severe T cell deficiency is not associated with risk of infectious complications above and beyond those seen in patients suppressed with prednisone-azathioprine alone. These studies suggest that ATG, produced under quality control conditions and having rather selective anti-T cell activity, is a useful adjunctive immunosuppressive agent for human renal transplantation.

Antilymphocyte Serum↗
PubMed1975

Rapid screening method for aflatoxins and zearalenone in corn.

The methanol-water extraction system used in AOAC Method II for aflatoxins extracts both the aflatoxins and zearalenone from corn. Using this methanol-water extraction system as a base, a rapid screening procedure has been developed for these mycotoxins. The methanol-water extract is defatted with hexane and the pigments are precipitated with copper carbonate. The aflatoxins and zearalenone are subsequently extracted into chloroform and are then detected by half-plate TLC. An elapsed time of about 1 hr is required to analyze 1 sample. The sensitivity of the method is about 2 mu-g/kg for aflatoxin B-1 and 100 mu-g/kg for zearalenone.

Aflatoxins↗