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Biomedical subjects

W Hofmann

Publications and source records attributed to W Hofmann.

At least 163 records · Page 9Linked to original sources
PubMed1992

[Educational emphasis at university centers].

In Germany four postgraduate courses in public health were set up since 1989. They all offer a public health training including research activities, field experience and international perspectives. The public health administration should decide in the near future whether this new training could be passed by the public health officers instead of the compulsory courses in the academies in Düsseldorf and München.

Curriculum↗
PubMed1992

[Multiple admissions to the psychiatric hospital--a study of the status of so-called "revolving door patients"].

The graph of the frequency distribution of rehospitalization shows a constant exponential decline without demarking a particular population of so-called "revolving-door" patients. Patients with at least four admissions to a regional psychiatry hospital within a time span of two years are compared to a control group of the total clinic population. Multiple admission patients suffer significantly more often from diseases with an unfavourable prognosis, the illness has started earlier in their lives, and the course of illness is marked by unstable dynamic states with frequent crises of suicide. A demographic analysis shows the group under survey to be younger and less often married; participation in the world of labour has been lost more often, schizophrenics who have frequently stayed in hospitals even loose their former autonomy in housing. Guardianships are significantly more often installed, but they have not proved to be an efficient form of help. The therapeutic care of this problem patients is rather unsatisfactory. The offered ambulatory services are not claimed and in hospital the special treatment units fail to reach these patients. Lack of therapeutic continuity and compliance determines the course of treatment and complicates therapeutic strategies.

Adult↗
PubMed1992

A new strategy for characterizing proteinuria and haematuria from a single pattern of defined proteins in urine.

Prerenal, glomerular, tubulointerstitial and postrenal proteinurias and haematurias are usually differentiated by a number of non-invasive and invasive diagnostic procedures. We have applied a new analytical strategy based on the observation that different urine protein patterns are excreted in normal, prerenal, renal and postrenal proteinurias and haematurias. When analysed by turbidimetric procedures urine albumin, IgG, alpha 1-microglobulin and alpha 2-macroglobulin can be used as marker proteins to characterize the degree of glomerular permeability, tubular protein reabsorption and postrenal bleeding respectively. Primary glomerulopathies (selective and non-selective) and tubulointerstitial nephropathies can be differentiated by plotting the excretion rates of IgG or alpha 1-microglobulin against that of albumin. Postrenal contaminations are detected by quantitative turbidimetric assay of the high molecular weight proteins, alpha 2-macroglobulin and IgG. In postrenal bleeding, with albumin concentrations above 100 mg/l, the relative excretion rates of these proteins were proportional to their plasma concentrations. In glomerular haematurias, however, the ratios to albumin were much lower. The optimal discriminating ratio was found to be 2.0 x 10(-2) for alpha 2-macroglobulin/albumin and 2 x 10(-1) for IgG/albumin. Tubulointerstitial involvement in haematuria is characterized by elevated alpha 1-microglobulin excretion rates, with alpha 2-macroglobulin/albumin ratios below 2.0 x 10(-2) and IgG/albumin ratios above 2 x 10(-1). The reported procedure allows the exclusion and differentiation of clinically relevant proteinurias and haematurias in a single urine specimen.

Adult↗
PubMed1991

Time-resolved cryo-electron microscopic study of the dissociation of actomyosin induced by photolysis of photolabile nucleotides.

The rapid release of a substrate or other ligand from photolabile precursors in a thin layer suspension of biological specimens followed by rapid freezing provides a method of trapping and visualizing short-lived states in a dynamic system. We demonstrate here the first successful application of this method to study the interaction of actin filaments with myosin subfragment 1 (S1) after release of nucleotides. The results obtained suggest that structural changes in actin filaments occur as a result of interaction with S1.

Actins↗
PubMed1991

Differentiation of hematuria by quantitative determination of urinary marker proteins.

Hematuria caused by prerenal, glomerular, postglomerular, and postrenal causes is usually differentiated by a number of noninvasive and invasive diagnostic procedures. In the present study we have applied a new analytical strategy based on observations that the various forms of hematuria can be classified by their typical protein pattern. When analyzed by quantitative turbidimetric assays, urines from postrenal hematurias contained high-molecular-weight proteins (alpha 2-macroglobulin and IgG) in proportions found in plasma. Relating excretion rates (mg/mg) of these proteins to those of albumin, ratios for alpha 2-macroglobulin/albumin and IgG/albumin were 2.0-31 x 10(-2) and 20.0-180 x 10(-2), respectively. In contrast, glomerular hematurias exhibited ratios of 0.01-2.0 x 10(-2) (alpha 2-macroglobulin/albumin) and 2.0-20 x 10(-2) (IgG/albumin). Additional determination of alpha 1-microglobulin allowed us to differentiate postglomerular hematurias caused by interstitial nephropathies from glomerular and postrenal diseases. Critical evaluation of 93 cases diagnosed by independent clinical examination including histology, sonography, and cystoscopy revealed that the criteria derived from protein measurements resulted in correct classification when urine albumin exceeds 100 mg/l. This noninvasive procedure is expected to be of considerable help in the primary care of patients with unexplained hematuria.

Adolescent↗
PubMed1991

Alteration of the lung parenchyma associated with autoimmune hepatitis.

The clinical history, radiological and histomorphological alterations of the lung parenchyma associated with chronic active autoimmune hepatitis are described. A 6-month-old female infant developed chronic active autoimmune hepatitis associated with autoimmune haemolytic anaemia. She was treated with immunosuppressive drugs, including steroids, for more than 6 years and developed symptoms and radiological signs of interstitial pneumonitis 4 years after onset of the autoimmune hepatitis. Associated bronchiectasis was detected 1 year later. No abnormalities of lung defence mechanisms could be demonstrated. Resection of the sixth left segment and of the basal parts of the left lower lobe revealed honeycombing with changes in the lung parenchyma which included chronic interstitial pneumonitis with multinucleate giant cells, seen predominantly in the distal airways, marked diffuse interstitial mononuclear infiltrates and mild diffuse interstitial fibrosis as well as bronchiectasis and organizing pneumonia. Granulomatous lesions, angiitis and necrotic areas were absent. Immunohistochemistry for immunoglobulins was negative for IgA, IgG and IgM and positive for IgD in the multinucleate giant cells. A strong positive reaction to HLA-DR-specific monoclonal antibody was noted, whereas no specific sugar receptors (endogenous lectins) could be detected by use of biotinylated glyconeoproteins.

Autoimmune Diseases↗
PubMed1991

Concentration and fluence dependence of the disturbance of the membrane integrity of human fibroblasts by the photodynamic action of Photosan III.

Two human fibroblast cell lines were treated with varying concentrations of the photosensitizer Photosan III for different incubation times, and subsequently irradiated with an He-Ne laser. The biological parameter investigated was trypan blue exclusion by the cells. For each given drug concentration and incubation time, a threshold fluence was observed, which resulted in the complete loss of the cell membrane integrity. Using the equation tcr = b X CPS-a, the correlation between threshold light dose (tcr) and the concentration of the photosensitizer (CPS) can be described for all three incubation times (10 min, 2 h, 20 h) characterized by different sets of a and b values. This power function implies that these parameters are inversely correlated to each other. A correlation of incubation time with critical exposure time for different drug concentrations gave saturation curves. No differences were observed between the two cell lines. The method applied may be useful for a fast comparison of the sensitizing efficiencies of different treatment protocols for the in vitro investigation of photodynamic laser therapy.

Cell Line↗
PubMed1991

Rapid increase in the activity of enzymes of eicosanoid synthesis in hepatic and extrahepatic tissues after experimental liver transplantation.

Previous studies have demonstrated a marked release of prostanoids from hepatic tissue after liver grafting. In addition, eicosanoid synthesis was shown to be regulated at the level of key enzymes. The present study addressed changes of the local availability of these enzymes during and after porcine orthotopic liver transplantation. We determined kinetic parameters of cyclooxygenase (CO), the initial enzyme of prostaglandin synthesis, of prostacyclin and thromboxane synthase (PCS, TXS), two more peripheral enzymes, in microsomal preparations of hepatic and gluteal muscle biopsies, and the activity of 5-lipoxygenase (5-LO), the key enzyme of leukotriene synthesis. Maximal velocity (Vmax) of CO and PCS showed a 4-fold increase both in liver and gluteal muscle tissue 1 hr after reperfusion of the grafted liver and a more than 20-fold increase after 24 hr (P less than 0.001), whereas apparent affinities (Km) remained unchanged. In contrast, Vmax of TXS and the activity of 5-LO disclosed a striking increase only within the hepatic graft (P less than 0.001). No changes of enzymatic activity could be observed during donor operation, cold storage, and 5 min after reperfusion. Results were independent of the duration of preservation (3 hr and 20 hr with Euro-Collins) and the addition of Iloprost, a prostacyclin-analogue. These results suggest that after liver grafting, abnormalities at the level of local enzyme expression in hepatic and extrahepatic tissues might contribute to preservation damage and systemic injury of the host.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

Hippocampal activity in the presence of quinolones and fenbufen in vitro.

Rare side effects on the central nervous system including dizziness, restlessness, and even very rare convulsions as reported during the course of antibiotic treatment with quinolones were the topic of a well-controlled in vitro approach. The excitability of brain matter was tested by electrically evoking field potentials in the CA1 region of the rat hippocampus in vitro. Direct effects of nalidixic acid, enoxacin, pefloxacin, norfloxacin, ofloxacin, and ciprofloxacin were found to occur as a dose-dependent increase in amplitude of this field potential, which is in line with the view that the quinolones increase excitability. The highest increase was found with enoxacin and nalidixic acid, and the lowest increase was found with ciprofloxacin. In order to keep the potential risk of the antibiotic therapy as low as possible, ciprofloxacin might be the drug of choice of the quinolones. In contrast to the quinolones, which only increased the amplitudes of electrically evoked potentials, fenbufen induced spontaneous firing in the pyramidal cell layer without stimulation in addition to its dose-dependent effects on the amplitudes of the evoked potentials. Threshold doses of the quinolones tested (0.25 microM) increased the amplitudes of evoked potentials in the presence of an otherwise ineffective concentration of fenbufen (1 microM) to different degrees, ranging from 39.2% for ciprofloxacin to 72.6% for enoxacin.

4-Quinolones↗
PubMed1991

[Infection-induced change in the pharmacokinetics of cefotaxime. Dose calculation in multiple organ failure and relevance of score systems].

The pharmacokinetics of cefotaxime were investigated in 14 patients suffering from multiple-organ failure requiring pump-assisted, continuous volume-constant hemofiltration (CVHF) for blood purification, whereby the filtration rate was 20 ml/min. Samples of blood and ultrafiltrate were evaluated by high-pressure liquid chromatography. For dose adjustment, three different algorithms of Dettli and Kroh were used. As compared with values obtained for anuric patients during the dialysis-free period, the mean serum half-life was nearly doubled (2.75 vs 4.48 h). This reduced elimination depended mainly on a diminished non-renal elimination ratio ranging from 0.085 to 0.366. The volume of distribution remained unchanged within a wide interindividual range (Vz, 0.35 l/kg, from 0.22 to 0.56 l/kg); the sieving coefficient increased to 0.89 as compared with 0.62 in healthy volunteers. Dose adjustment by algorithms showed varied degrees of over-dosage. The estimate closest to an optimal dose was reached by the application of a new algorithm of Kroh (mean dose deviation +19%; SD, +/- 27%) using an individual non-renal elimination ratio (QIND). QIND correlated significantly with the severity of disease according to the sepsis score of Elebute and Stoner (r = 0.763, P less than 0.005). Thus, it is possible to adjust reliably individual dosage in multiple-organ failure and to reduce the frequency of drug monitoring required.

Adult↗
PubMed1991

An effect-specific track-length model for radiations of intermediate to high LET.

A model for the induction of transformation, mutation, and cell killing by radiations of intermediate to high linear energy transfer (LET) is presented. The mathematical formulation presupposes a constant probability per unit path length for damaging multiple subcellular targets by radiation of a fixed LET. The coupling between effects is accounted for through an explicit calculation of the probability that any specific combination of effects occurs in a given cell. This feature avoids the false assumption that cell killing and mutation (or transformation) are independent events. The resulting model then is applied to data on the in vitro survival, mutation, and transformation of cells by radiations of varying LET. A summary of estimated parameter values is provided and calculations of the effect of cellular flattening on transformation are presented.

Cell Survival↗