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Biomedical subjects

G Hübner

Publications and source records attributed to G Hübner.

At least 109 records · Page 6Linked to original sources
PubMed1989

[Rapid diagnosis of Bacteroides using immunofluorescence].

Intestinal Bacteroides species belong to the most common causative agents of human anaerobic infections. Because their cultural diagnosis is complicated by the presence of a so-called "empty interval of diagnosis" lasting for several days, rapid diagnostic methods are of great significance. Due to the possibility of specific antigen detection the fluorescence antibody technique (FAT) is especially qualified for this purpose. The presented investigations demonstrate that the direct FAT should be preferred to the indirect method in the diagnosis of infections caused by intestinal Bacteroides species.

Antibody Specificity↗
PubMed1989

[The value of determining delta-aminolevulinic acid in urine (method II, East German occupational monitoring) as a screening procedure for the assessment of internal residues in occupational exposure to lead].

For the purpose of supervising workers exposed to lead the ratio of blood lead is determined several times per year. The withdrawal of blood samples from the vein necessary for this purpose as well as the comparatively high analytic expense make it essential to revise, whether it is possible to give up the analysis of blood lead at least partially in favour of other diagnostic measures less affecting the worker. Our investigation gave evidence of the fact, that the validity of a screening test for evaluating the blood lead concentration on the basis of the determination of delta-aminolaevulinic acid in urine (method II, AB-DDR; 2 nd morning urine) is insufficient.

Aminolevulinic Acid↗
PubMed1988

Copper storage disease of the liver and chronic dietary copper intoxication in two further German infants mimicking Indian childhood cirrhosis.

A severe copper storage disease of the liver with micronodular cirrhosis resembling Indian childhood cirrhosis (ICC) was found in two siblings of a German family leading to death in one infant at the age of 13 months. The fatal outcome correlated with severe ballooning of hepatocytes and excessive formation of Mallory bodies. The copper content of the liver was 698 micrograms per gramme wet weight (control 5 micrograms) in the living patient and 2154 micrograms per gramme dry weight (controls 39, 54 micrograms) in the dead infant. In both cases copper was stored not only in hepatocytes but also to a high degree in mesenchymal cells. Chronic contamination of drinking water supplied from a well via copper pipes could be verified as the cause of copper intoxication, lending further support to ICC as an environmental, acquired disorder. Accumulation of exogenic copper already very early in infancy appears most important for the development of the disease, as both the parents and one child not exposed to copper intoxication during the first 9 months of its life are clinically healthy.

Chemical and Drug Induced Liver Injury↗
PubMed1988

Human nesidioblastosis tissue as an immunogen for generation of islet cell specific monoclonal antibodies.

Nesidioblastosis pancreas was used as an immunogen in BALB/c-mice to generate monoclonal antibodies against structures of human islet cells. Seven clones were selected by screening 311 growing hybridomas for reactivity with the rat insulinoma cell line, RIN m5F, and with cryostat sections from human pancreas. None of the selected clones reacted with pancreatic hormones or endocrine-specific peptides. Monoclonal antibodies cross-reacting with the RIN-cell line also bound to different endocrine organs or cell lines, while some RIN-cell-negative clones bound only to Langerhans islets from human pancreas.

Animals↗
PubMed1988

Studies on the fast reacting thiol groups in phosphofructokinase from baker's yeast.

The fast reacting thiol groups of yeast phosphofructokinase were studied by means of stopped-flow measurements. The enzyme was found to contain four very fast reacting cysteinyl residues determined by their reactivity towards 5,5'-dithiobis(2-nitrobenzoic acid). A second class of eight thiol groups reveals an apparent first order rate constant which is three orders of magnitude lower than the rate constant of the first one. Due to the extreme high reactivity of the first class of cysteinyl residues partial oxidation was already observed under aerobic conditions. Fructose 6-phosphate, fructose 1.6-bisphosphate, and fructose 2.6-bisphosphate, respectively, decrease the reactivity of the first class of thiol groups but not the total number of the accessible cysteins. This result is discussed with regard to conformational changes of the enzyme after binding of the sugar phosphates.

Dithionitrobenzoic Acid↗
PubMed1988

[Morphological studies of the effect of chromium-III-chloride on the islet cell organ in rats under the conditions of high and low fat diets].

It is well known, that the glucose tolerance factor amplifies the peripheral action of insulin. This factor contains trivalent chromium. This investigation deals with the influence of trivalent chromium on morphometric and histological parameters of pancreatic islets of wistar rats. Animals were given chromium-III-chloride for 8 weeks (perorally, daily 15 ppm or 3 ppm) under conditions of high (HFD) and low (LFD) fat diet. Staining of pancreatic slices was performed with Victoria blue and acid Fuchsin. The relative volume density of the endocrine cells was obtained as the ratio of the number of islet cells to the number of exocrine pancreatic cells. The statistical evaluation was performed by using Students t-test. In HFD animals (n = 12) chromium supplementation caused an increase by 41% of volume of islets compared to HFD controls. A lot of small islets were found, which may be newly formed. Moreover, polynesia and hyperplasia of islets were observed. LFD animals (n = 12) do not show any morphometric changes in comparison with LED controls; but macronesia, micronesia and polynesia of islets were observed. In conclusion we suggest, that under special conditions trivalent chromium has growth stimulatory effects on the endocrine pancreas.

Animal Feed↗
PubMed1988

The functional role of thiol groups of pyruvate decarboxylase from brewer's yeast.

Pyruvate decarboxylase purified from brewer's yeast has been modified by the thiol specific reagents 4-hydroxy-mercuri-benzoate and 3-bromo-pyruvamide. The kinetic properties of the thiol-modified enzyme derivatives were investigated by stopped-flow technique. The enzyme--inactive in the absence of its substrate--is activated by binding pyruvate to the regulatory sites. This activation behaviour is lost after modification of six thiol groups per PDC molecule. The thiol groups have been subdivided into two classes according to their modification rates. Two of these six thiol groups are involved in the mechanism of enzyme activation.

Carboxy-Lyases↗
PubMed1987

Congestive heart failure due to mitochondrial cardiomyopathy in Kearns-Sayre syndrome.

Despite extensive analysis of the ultrastructural changes in skeletal muscle fibers in chronic progressive external ophthalmoplegia (CPEO), similar changes in the heart muscle fibers of patients with cardiac involvement in CPEO, called Kearns-Sayre syndrome, have not been described in detail. We report the clinical long-term course in a patient with Kearns-Sayre syndrome in whom mitochondrial cardiomyopathy was suspected in vivo and was confirmed at autopsy as the underlying cause of severe dilative cardiomyopathy. Enlarged, abnormally structured, excessively augmented mitochondria and loss of myofibrils could be shown both in skeletal and heart muscle cells.

Adult↗
PubMed1987

Fatal copper storage disease of the liver in a German infant resembling Indian childhood cirrhosis.

A female child of non-consanguineous, healthy German parents fell ill at the age of 7 months with a progressive liver disease leading to irreversible hepatic failure 3 months later. Histological examination revealed severe liver cell necrosis, excessive Mallory body formation and veno-occlusive-like changes associated with massive storage of copper, similar to Indian childhood cirrhosis (ICC). Chronic copper contamination of drinking water was the only detectable aetiological factor. The study illustrates that ICC most probably is an environmental disease, also occurring outside the Indian subcontinent, and is likely to be underdiagnosed in the Western world.

Child↗
PubMed1987

[Methodologic problems in the detection of indole formation by anaerobic pathogens].

The demonstration of indole formation is of great value for the identification of pathogenic anaerobes. A reduction of the pH to values below the critical range of 5.1-5.3 in complex media 5.5 in simple testing substrates, respectively, which is caused by the presence of fermentable carbohydrates and will result in false-negative reactions. For this reason, the indol test should be performed with an adequate buffer capacity and an addition of fermentable carbohydrates should be avoided. Strains showing a false-negative reaction in the spot indole test can be reliably accounted for by means of the rapid test in buffered tryptophan solution described here without having to use additional anaerobic culture methods.

Bacteriological Techniques↗
PubMed1986

Myoadenylate deaminase deficiency: successful symptomatic therapy by high dose oral administration of ribose.

A 55 years old patient suffering from exercise-induced muscle pain and stiffness due to primary myoadenylate deaminase deficiency has been successfully treated with D-ribose since 1984: single doses of 4 grams administered at the beginning of exercise prevented the symptoms completely; on continuation of exercise this dose had to be repeated all 10-30 min. Total doses of 50-60 g per day were tolerated without side-effects.

AMP Deaminase↗
PubMed1986

Study on the initial kinetics of yeast phosphofructokinase by stopped-flow measurements.

The initial kinetics of yeast phosphofructokinase was studied by stopped-flow measurements over an enzyme concentration range from 0.5 mg/ml to 0.01 mg/ml. Before attaining the steady state the reaction showed a lag phase in the product formation, the duration of which was found to decrease with increasing enzyme concentration. The lag phase disappeared after preincubation of the enzyme for at least five minutes with either fructose 6-phosphate, fructose 1,6-bisphosphate or fructose 2,6-bisphosphate. Preincubation of the enzyme with either AMP or ADP resulted in a reduction of this phase, while ATP was without effect. Simultaneous addition of fructose 1,6-bisphosphate to the reaction mixture of the enzyme causes a significant shortening of the transient phase, whereas micromolar concentrations of fructose 2,6-bisphosphate are capable of abolishing the lag phase completely. The occurrence of an initial transient phase suggests that the enzyme after starting the reaction converts from a state of low activity to one of high activity. This conversion mainly depends on the concentration of fructose 1,6-bisphosphate generated in the course of the reaction. In addition an association reaction of the enzyme seems to be involved in the process of conversion of the phosphofructokinase during the initial transient phase.

Adenosine Diphosphate↗
PubMed1986

Fatal mitochondrial cardiomyopathy in Kearns-Sayre syndrome.

The clinical and postmortem findings in a 26 year old man with Kearns-Sayre syndrome are described. In the last years of his life he suffered from cardiac arrhythmias and a congestive cardiomyopathy, dying of cardiac pump failure. The heart was enlarged, especially the left ventricle which was fibrotic and excessively dilated. Histological and fine structural investigation revealed an excessive loss of myofibrils and an increase of enlarged mitochondria with lamellar and atypically tubular cristae in widespread heart muscle cells. Mitochondrial anomalies were also observed in some cells of the conductive system. This patient thus suffered not only from a mitochondrial myopathy with ragged red fibers but also from a fatal mitochondrial cardiomyopathy. The anomalies observed in the mitochondria of the conductive system cells suggest that the well-known conductive abnormalities in patients with Kearns-Sayre syndrome might be at least partly caused by disturbed function of these mitochondria.

Adult↗
PubMed1986

Fatal mitochondrial cardiomyopathy in Kearns-Sayre syndrome with deficiency of cytochrome-c-oxidase in cardiac and skeletal muscle. An enzymehistochemical--ultra-immunocytochemical--fine structural study in longterm frozen autopsy tissue.

Morphological studies in a 26-year-old man with long-standing Kearns-Sayre syndrome, with cardiac arrhythmias and a fatal congestive cardiomyopathy, revealed a mitochondrial myopathy of both skeletal and myocardial muscle (Hübner et al. 1986). Histochemical investigation of cytochrome-c-oxidase showed multiple enzyme defects of both cardiac and skeletal muscle present in myocytes with normal and abnormal numbers of mitochondria demonstrated by ultracytochemistry. Immunohistochemical studies with antibodies against the holoenzyme and various subunits revealed that in the heart the enzyme defect affected both contractile and conductive fibres and was characterized by a severe reduction but not a complete loss of nuclear and mitochondrially coded immunoreactive enzyme protein. In skeletal muscle, however, where up to 30% of the fibres lacked enzyme activity, immunoreactivity was reduced only very occasionally. These results are most consistent with a defective enzyme assembly in the inner mitochondrial membrane and probably indicate heterogeneity of mitochondria, i.e. organ-specific pathological reaction patterns.

Adult↗