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Biomedical subjects

R Hoffmann

Publications and source records attributed to R Hoffmann.

At least 433 records · Page 24Linked to original sources
PubMed1983

Correlation between calmodulin-dependent increase in the rate of calcium transport and calmodulin-dependent phosphorylation of cardiac sarcoplasmic reticulum. Characterization of calmodulin-dependent phosphorylation.

The aim of the present study was to prove a correlation between the calmodulin-dependent increase in the rate of calcium transport by dog cardiac sarcoplasmic reticulum and calmodulin-dependent phosphorylation. The dependence of phosphorylation on the total calmodulin concentration at 75 microM and 1 microM free calcium gave apparent calmodulin half-saturation constants Km (CaM) of 9.4 nM and 181 nM, respectively, whilst the apparent Km (CaM) for the rate of calmodulin-stimulated calcium transport carried out at 1 microM calcium, but phosphorylated prior to the calcium uptake at 75 microM or 1 microM calcium, were 12.5 nM and 127 nM, respectively. A positive correlation was obtained between calmodulin-dependent increase in the rate of calcium transport and hydroxylamine-insensitive phosphoester formed by the calcium/calmodulin-regulated, membrane-bound protein kinase. More than 90% of incorporated [32P]phosphate is confined to a 26-28-kDa or 9-11-kDa protein as determined by polyacrylamide gel electrophoresis following solubilization in sodium dodecyl sulfate at 37 degrees C and at 100 degrees C, respectively, similar to the results obtained by phosphorylation with cAMP-dependent protein kinase. The data indicate that calmodulin-dependent phosphorylation of the above protein(s) is causally related to the stimulation of the rate of calcium transport by cardiac sarcoplasmic reticulum, which is at least partially due to a shift in the calcium dependence of the rate of calcium transport to lower free calcium concentrations, K(Ca), of 1.25 microM and 0.61 microM in controls and calmodulin-dependent phosphorylation, respectively. Activation of calmodulin-dependent phosphorylation by free calcium at total calmodulin concentrations of 300 nM, 100 nM and 30 nM gave apparent K(Ca) values of 0.83 microM, 1.44 microM and 2.3 microM and Hill coefficients of 4.13, 3.76 and 3.79, respectively, indicating that all four calcium binding sites of calmodulin have to be saturated to obtain activation of the calcium/calmodulin-regulated protein kinase. The calmodulin-dependent modulation of calcium transport in vivo is, therefore, determined to great extent by the total calmodulin concentration present in the sarcoplasm.

Animals↗
PubMed1983

[Complications following cholecystectomy and their therapy].

426 patients who had undergone cholecystectomy took part in a retrospective study covering four years (1977-1980). 53 patients had gallbladder empyema. The complications in the 373 cholecystectomies without empyema were 4 wound infections (1.1%), 2 other infections, 10 postoperative hemorrhages (2.7%), 3 cases of retained stones (0.8%) and 7 other complications. Only 3 of the total of 6 infections required antibiotic therapy. Since the infection rate in the 373 patients without empyema was very low, and since it is known that bile is sterile in the early stages of acute cholecystitis, there is no indication even for prophylactic antibiotics. Treatment of acute cholecystitis is cholecystectomy within 24-48 h of onset of acute symptoms. The rate of infectious complications in patients with gallbladder empyema was 15.1%. Primary treatment for this disease is surgical removal of the infectious focus (cholecystectomy) and reduction of bacterial spread or treatment of peritonitis if already present.

Aged↗
PubMed1983

Involvement of the cytotoxic/suppressor T-cell subset in liver tissue injury of patients with acute and chronic liver diseases.

So far, phenotypic and functional analyses of cytotoxic lymphocytes in viral hepatitis, as well as in primary biliary cirrhosis, have focused on circulating lymphocyte subpopulations, whereas their occurrence and distribution at the involved site, namely the liver, remain largely unknown. In the present study, monoclonal antibodies were used to characterize both circulating and liver-tissue-infiltrating lymphocyte subsets in acute cytomegalovirus hepatitis, in chronic B-virus hepatitis, and in primary biliary cirrhosis. Special emphasis was laid on the cytotoxic/suppressor T-cell subset. Total T cells were identified by the monoclonal antibody T411. The monoclonal antibody T811 was used to identify the cytotoxic/suppressor T-cell subset, which comprises virus-specific, altered self, and alloreactive cytolytic T lymphocytes and their precursors, a fraction of killer and natural killer cells. Furthermore, killer and natural killer cells were identified more specifically by the monoclonal antibody. HNK1. Irrespective of the number of cytotoxic/suppressor T cells in peripheral blood, these cells (T811 phenotype) were accumulated in the liver at the site of tissue injury. The preponderance of this lymphocyte subset at the site of tissue injury suggests an important role for these cells in the mechanism leading to tissue injury.

Adult↗
PubMed1983

[Direct and indirect parameters for free thyroxine. II. Diagnostic accuracy in disorders of thyroid function and binding protein anomalies].

Part II of the study concerning the clinical applicability of direct and indirect parameters for free thyroxine evaluates the diagnostic accuracy of the FT4-RIAs ImmoPhase, GammaCoat, Liquisol, Amerlex and LisoPhase in relation to FT4 index and T4/TBG ratio. This comparison of methods is done on a thoroughly classified collection (n = 640) of patients with normal and impaired thyroid function including patients with binding protein anomalies (pregnancy, estrogen-medication, phenytoin therapy, renal protein loss). FT4 normal ranges of a given kit harmonize well with data of the manufacturers and of the literature. On the other hand, the normal ranges of the various kits are not comparable. The differentiation of euthyroidism from hyper- or hypothyroidism can be made without problems using any of these methods, with the exception of the FT4-RIA GammaCoat. As expected, patients with euthyroid goiter show, on the average, slightly lower parameters for FT4. In pregnancy all direct and indirect parameters for FT4 have a tendency to lower values after the first trimester. This trend is most distinct for the T4/TBG ratio. A weak negative correlation of FT4 parameters with basal TSH, which does not exceed the upper normal range, however, can be interpreted in the sense of a relative hypothyroxinemia. Under contraceptive estrogen medication FT4 parameters do not fall outside the normal range, with the exception of the FT4-RIA ImmoPhase assay which yields a significantly increased frequency of high FT4 levels. On therapy with phenytoin FT4 values are generally lower than in controls. FT4 parameters in patients with renal protein loss of more than 2 g daily do not behave uniformly. While three of the FT4-RIAs tested (ImmoPhase, GammaCoat, Amerlex) show a tendency to lower values, the results of the remaining FT4 parameters do not differ significantly from the distribution of normals. The study leads to the conclusion that indirect FT4 parameters are still useful in the diagnosis of thyroid function; currently available FT4 radioimmunoassays may yield comparable results. With regard to the varying quality of the various commercial test kits, the choice between FT4-RIAs and indirect FT4 parameters does not depend primarily on clinical but on technical viewpoints.

Adult↗
PubMed1983

[Direct and indirect parameters of free thyroxine. I. Method, quality control and in vitro experiments on storage of samples and effect of drugs].

The clinical applicability of direct FT4 determinations by the radioimmunoassays ImmoPhase, GammaCoat, Liquisol, Amerlex and LisoPhase is tested in comparison to the FT4 index and the T4/TBG ratio. Part I of this study deals with technical aspects concerning quality control as well as with in-vitro experiments concerning storage of samples and interference of drugs. The precision of FT4-RIAs is satisfactory; inter-assay coefficients of variation are generally lower than 10% for medium hormone concentrations. Because of a change of the standard curve calibration by the manufacturer of the Liquisol kit, the inter-assay variability (17%) of this assay is unacceptably high. The comparison of working ranges shows that the sensitivity of all FT4 assays is sufficient. However, the upper limits of working ranges of the Liquisol and LisoPhase kits are too low. Storing the samples in form of serum yields lower values for any FT4 parameter than storing as whole blood. This unexpected observation is true for room temperature as well as for refrigeration at 4 degrees C. To be sure, the values of indirect FT4 parameters from serum and whole blood coincide somewhat better especially when the samples are stored in the refrigerator. Repeated thawing and refreezing does not influence the results of FT4-RIAs significantly. In vitro testing of drug interferences by addition of therapeutic doses of primidone, phenobarbital, phenytoin and acetylsalicylic acid yields significant effects only for the last quoted pharmaceutical. While the FT4 levels of the Liquisol and LisoPhase assays rise with the acetylsalicylic acid dose according to expectations, the values of the Amerlex and GammaCoat assays decrease. With regard to handling of the tests, there are no special technical problems for all FT4-RIAs tested.

Aspirin↗
PubMed1982

Seasonal and daily activity changes in captive Cheirogaleus medius.

Seasonal and daily variation in locomotor activity are recorded in 11 animals over 17 weeks, covering the last 8 weeks of the inactive season and the ensuing breeding season. The results are compared with changes in body weight and with the onset, duration and frequency of reproductive activity. These and some behavioral observations are related to the conclusions of previous publications.

Animals↗
PubMed1982

Eperythrozoon suis in naturally infected pigs: a light and electron microscopic study.

The light and electron microscopic characteristics of natural infections with Eperythrozoon suis are reported. E. suis are enclosed by a single membrane, and they reach a length of up to 600 nm and a diameter of 375 to 500 nm. Neither distinct organelles nor nuclear structures appear in the parasites cytoplasm. They replicate by binary fission, and have close contact with red blood cells without showing any signs of membrance alteration. Massive phagocytosis of whole red blood cells not parasitized by E. suis in spleen and lymph nodes.

Anaplasmataceae Infections↗
PubMed1982

[Radiological diagnosis of cavernous hemangioma of the liver (author's transl)].

Eight cases of cavernous hemangioma of the liver are described and their sonographic, scintigraphic, computertomographic and angiographic findings are discussed. The angiographic diagnosis was the most reliable, especially when the computertomography was performed without using contrast medium for tissue enhancement. In cases of doubt laparatomy was necessary in order to maintain a histological diagnosis.

Adult↗