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Biomedical subjects

R Averdunk

Publications and source records attributed to R Averdunk.

At least 19 recordsLinked to original sources
PubMed1994

Serum carotene deficiency in HIV-infected patients. Berlin Diarrhoea/Wasting Syndrome Study Group.

OBJECTIVE: To assess total serum carotene concentration in HIV-infected patients as an indicator of fat malabsorption in correlation with diarrhoea, secondary enteric infections, and blood lymphocyte subsets. DESIGN: Prospective study. SETTING: Two referral-based tertiary care centres in Berlin, Germany. PATIENTS: A total of 33 controls and 116 HIV-infected patients who had complete microbiological evaluation of stools and biopsies obtained at upper endoscopy because of diarrhoea (n = 54), or other symptoms (n = 62), were studied. MAIN OUTCOME MEASURES: Total serum carotene concentration was determined spectrophotometrically. RESULTS: Total serum carotene concentration was abnormal (< 0.88 mumol/l) in 77% of HIV-infected patients and significantly decreased compared with controls [0.47 mumol/l (range, 0.06-1.69 mumol/l) versus 1.37 mumol/l (range, 0.88-2.92 mumol/l); P < 0.0001]. Total serum carotene concentration did not differ between AIDS patients and patients at earlier disease stages, between patients with or without secondary enteric infections, or between patients with or without fever. In patients at earlier disease stages, but not in AIDS patients, total serum carotene concentration was lower for patients with than without diarrhoea. The percentage of CD4 lymphocytes (r = 0.364; P < 0.001), CD4 count (r = 0.28; P = 0.0013), and CD4/CD8 ratio (r = 0.38; P < 0.001) in the peripheral blood correlated with total serum carotene levels in HIV-infected patients. CONCLUSION: HIV-infected patients frequently have abnormal total serum carotene concentrations indicating fat malabsorption which may contribute to diarrhoea. Furthermore, total serum carotene concentrations correlate with immunologic abnormalities in HIV infection.

CD4-Positive T-Lymphocytes↗
PubMed1991

Hyaline globules reacting positively with zidovudine antibody in brain and spinal cord of AIDS patients.

Histology of the central nervous system in nine AIDS showed extracellular hyaline globules in the white matter of the brain and the spinal cord. In immunohistochemical studies with a battery of antibodies, the only positive reaction of these globules was with an antibody to zidovudine. High-performance liquid chromatography showed the presence of a zidovudine isomer in eluates of brain tissue from these patients.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Concentrations of magnesium, zinc and copper in serum of patients with acquired immuno-deficiency syndrome.

The concentrations of Mg, Zn, Cu and albumin, and pseudocholinesterase activity were measured in the sera of 31 AIDS patients, 27 belonging to group IVC1 and 4 to group IVC2. Mean values for all patients were within the normal ranges. Only two patients showed hypozincaemia. A correlation was found between the concentrations of serum zinc and albumin. The serum albumin concentration was correlated with the serum pseudocholinesterase activity.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Characterization of furosemide-sensitive Mg2+ influx in Yoshida ascites tumor cells.

Partially Mg2+-depleted Yoshida ascites tumor cells took up Mg2+ after reincubation in Mg2+- and HCO3(-)-containing media. Mg2+ influx was insensitive to ouabain, amiloride and disulfonic stilbenes, but was noncompetitively inhibited by furosemide (Ki = 0.4 mM) and bumetanide. Mg2+ influx obeyed Michaelis-Menten kinetics with respect to Mg2+ concentration (Km = 1.1 mM) and was sigmoidal with respect to HCO3- concentration. Electroneutral Mg2+, HCO3- cotransport was supposed to be the mechanism of Mg2+ influx.

Amiloride↗
PubMed1986

Protein kinase C in cytosol and cell membranes of concanavalin A-stimulated rat thymocytes.

In concanavalin A-treated thymus cells and phytohemagglutinin-treated spleen cells, the distribution of protein kinase C is changed. Shortly after addition of plant lectins, the activity of protein kinase C increased in the cytosol and decreased in the particulate fraction. 2 h later, the activity of protein kinase C decreased in the cytosol and increased in the particulate fraction. Membrane binding of protein kinase C and tion of DNA synthesis showed the same dependency on concanavalin A concentration. A long-term membrane binding of protein kinase C seems to be essential for lymphocyte stimulation.

Animals↗
PubMed1986

Alteration of prostanoid metabolism in rats with magnesium deficiency.

Plasma and tissue concentrations of prostanoids PGE2, PGF2 alpha. 6-keto-PGF1 alpha (a stable metabolite of prostacyclin) and TXB2 (a stable metabolite of thromboxane A2) were measured in normal and magnesium-deficient rats. The mean values for prostanoids in plasma were significantly higher in magnesium-deficient rats than in normals (515 +/- 43 vs 296 +/- 31 pg/ml for 6-keto-PGF1 alpha, p less than 0.01, 3700 +/- 322 vs 346 +/- 33 pg/ml for TXB2, p less than 0.001 and 1234 +/- 132 vs 434 +/- 51 pg/ml for PGE2, p less than 0.001). Tissue levels of prostanoids were also significantly higher in magnesium-deficient rats as compared to normals. The increased synthesis of prostanoids is apparently linked to enhanced influx and translocation of Ca++ into the cells. If the adenylate cyclase is inhibited in magnesium deficiency, the lowered c-AMP will permit a high cyclooxygenase activity and a drastic increase in TXB2. It is possible that the changes in prostaglandin synthesis in magnesium deficiency are linked to the development of different diseases.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Membrane alterations in magnesium-deficiency-induced malignant T cell lymphoma.

Malignant T cell lymphoma cells induced in the thymus by chronic Mg deficiency showed a less ruffled surface in the scanning electron microscope, particularly after intraperitoneal transplantation. Their content of phosphatidylserine and phosphatidylinositol was increased. The content of phosphatidylcholine, cholesterol and the cholesterol/phospholipid ratio, and thus membrane microviscosity, were decreased. The activity of phospholipid methyltransferase I and II was reduced. In parallel to these alterations, 45Ca2+ influx and efflux as well as 45Ca2+ content in mitochondria, microsomes and cytosol of lymphoma cells were enhanced.

Animals↗
PubMed1982

Development and properties of malignant lymphoma induced by magnesium deficiency in rats.

Female wistar rats were fed on an Mg-deficient diet. After 8 to 10 weeks, the thymus glands were strongly degenerated and the number of lymphocytes was reduced, especially in the cortex. Thymus degeneration was associated with a decreased rate of DNA, RNA, and protein biosynthesis and necrosis and phagocytosis of lymphocytes. The degeneration was normalized after feeding on an Mg-rich diet. After 10 or 11 weeks of Mg deficiency, local cell proliferations of immature lymphocytes with a great number of free ribosomes were found in some thymus glands. The local cell proliferations developed into infiltrating tumors without metastases. In lymphoma cells the Na+ and Ca2+ content, the turnover of cellular Na+ and K+, and the aerobic production of CO2 and lactate were increased.

Animals↗
PubMed1982

Radiation effect on partially synchronized Yoshida sarcoma cells.

Yoshida sarcoma cells, which have the same growth characteristics as ascites cells in the mouse and in cell suspension, were partially synchronized in vitro by means of excess thymidine (0.1 mM thymidine for 18 h). The growth of non-synchronized cultures was inhibited by irradiation, the degree depending on the dose of radiation. At the same time, a 50% inhibition in vivo (380 rad) and in vitro (480 rad) was determined. The incorporation of 3H-thymidine into the DNA is inhibited by 10-32%, depending on the radiation dose. The mitotic index decreases 2 h after irradiation by a dose-dependent amount. A mitotic maximum develops later; the delay is dose-dependent. Partially synchronized cells were irradiated in the G1/S-, G2-, and G1-phase. As compared to the 3H-thymidine incorporation and the mitotic index there were no significant differences between the cultures which were irradiated in the individual phases of the non-synchronized control cultures. The cultures which were irradiated in the G2-phase, however, showed a significantly reduced growth in vivo after 48 h. If the cells were cultured for more than 72 h after irradiation, the differences between the cultures irradiated in the G2-phase and the other phases were reduced.

Animals↗
PubMed1981

Outpatient evaluation of dietary intake and nitrogen removal in continuous ambulatory peritoneal dialysis.

Five patients on continuous ambulatory peritoneal dialysis were studied to evaluate dietary intake, glucose absorption from the dialysate, and urinary and dialysate nitrogen removal. The study was done on an outpatient basis, while the patients ingested their usual diets and went about their usual activities. The results indicate that patients greatly overestimated their caloric and protein intake, which was 0.71 to 0.96 g/kg bodyweight per day. Dialysate glucose contributed considerably to total caloric intake, because approximately 75% of of the dialysate glucose was absorbed independent from total glucose administered, providing 20% to 29% of the total caloric intake. We concluded that protein requirement in clinically stable continuous ambulatory peritoneal dialysis patients still needs defining because the patients may be anabolic with lower protein intakes than previously recommended.

Aged↗
PubMed1981

[Sensitivity of several commercial thromboplastins to non-carboxylated clotting factors II and X (author's transl)].

All reagents for determination of thromboplastin time (Quick-test) tested so far are sensitive to non-carboxylated clotting factor X, and sensitivity varies, depending on the reagent. The thromboplastins of Behring and Thrombotest are very sensitive. The preparations of La-Roche and Boehringer are somewhat more sensitive than those of Dade and Goedecke. Only the differences between the first group (Behring, Thrombotest) and the others are significant. There is a good correlation between factor X sensitivity, prothrombin time and non-carboxylated clotting factor X sensitivity, with all reagents. These results may be of significance for quality control and standardization of the prothrombin time.

Biomarkers↗
PubMed1980

Characterization of the concanavalin A-induced increase in lymphocyte cell membrane permeability by furosemide.

The effect of ConA on passive 42K+ fluxes in human lymphocytes was analysed by treatment with furosemide and ouabain. Furosemide has no effect on net K+ transport and pump flux. The component of passive efflux of 42K+ which depends on K+-K+ exchange is inhibited by furosemide; its mechanism is discussed in detail. The 42K+ uptake in lymphocytes consists of 1. an ouabain-sensitive pump influx, 2. an ouabain-insensitive leak influx and 3. a furosemide-sensitive K+-K+-exchange. Only the first two components of 42K+ uptake are stimulated by ConA.

Biological Transport↗
PubMed1980

Effect of concanavaline A on intracellular K+ and Na+ concentration and K+ transport of human lymphocytes.

Incubation of human lymphocytes with ConA causes an increase in [Na+]i and a decrease in [K+]i. This effect is not due to the experimental washing procedure, but is due to the ConA-induced increase in permeability which is not fully compensated by the increase in active transport. The ConA-induced increase in 42K+ uptake consists of an increase in leak flux which is independent of [Na+]o, and of an increase in pump flux which is dependent on [Na+]o. The increase in leak flux may be caused by increased membrane fluidity. The increase in pump flux may be produced by the increased [Na+]i and by a stimulation of Na+, K+ATPase.

Binding Sites↗
PubMed1979

Reduced lectin stimulation of lymphocytes from magnesium-deficient rats.

Spleen cells and thymocytes from Mg-deficient rats, fed a Mg-deficient diet for 10--13 weeks, incorporate [3H]thymidine at half the rate of normal cells. The cells from Mg-deficient rats are less stimulated by lectins than those from normal animals. These effects correspond to the reduced content of gamma-globulins in serum in Mg deficiency. They are caused by the altered electrolyte content of the Mg-deficient cells.

Animals↗