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Biomedical subjects

S Berger

Publications and source records attributed to S Berger.

At least 19 recordsLinked to original sources
PubMed1992

The redox-controlled light-harvesting chlorophyll a/b protein kinase. Deactivation by substituted quinones.

The deactivation of the redox-controlled light-harvesting chlorophyll a/b protein kinase of Acetabularia acetabulum and pea thylakoids was studied. Substituted benzoquinone, naphthoquinone, and anthraquinone analogs including mono-, di-, and trihalogenated and/or alkylated quinones, which are known to inhibit the cytochrome b6/f activity, deactivate the kinase in the dark, and prevent its activation in the light. Analogs halogenated at positions 2- or 3- are the most effective deactivators. Increasing the size of the alkyl side chain and/or the number of rings lowers the deactivation effect. The activated state of the pea kinase decays with a t1/2 of 15 min, while the Acetabularia enzyme retains its active state for at least 2 h. The midpoint potential for Acetabularia kinase activity in the dark is 120 +/- 10 mV and is compatible with the involvement of plastoquinone in the kinase activation via reduction of the cytochrome complex. Deactivation of kinase by the analogs inhibiting cytochrome b6/f complex activity and the kinase copurification with the cytochrome b6/f fraction obtained from the Acetabularia thylakoid further support this conclusion. These results indicate that the process of kinase activation/deactivation includes the binding of plastoquinol or quinone analogs by the cytochrome complex and its interaction with the kinase. We propose that the latter process may constitute the rate-limiting step controlling the kinase activation/deactivation kinetics.

Acetabularia↗
PubMed1992

The iron-sulfur-cluster-containing L-serine dehydratase from Peptostreptococcus asaccharolyticus. Stereochemistry of the deamination of L-threonine.

The stereochemistry of the deamination of L-threonine to 2-oxobutyrate, catalyzed by purified L-serine dehydratase of Peptostreptococcus asaccharolyticus, was elucidated. For this purpose the enzyme reaction was carried out with unlabelled L-threonine in 2H2O and in 3HOH, as well as with L-[3-3H]threonine in unlabelled water. Isotopically labelled 2-oxobutyrate thus formed was directly reduced in a coupled reaction with L- or D-lactate dehydrogenase and NADH. The (2R)- or (2S)-2-hydroxybutyrate species obtained were then subjected to configurational analyses of their labelled methylene group. The results from 1H-NMR spectroscopy and, after degradation of 2-hydroxybutyrate to propionate, the transcarboxylase assay consistently indicated that the deamination of L-threonine catalyzed by L-serine dehydratase of P. asaccharolyticus proceeds with inversion and retention in a 2:1 ratio. This partial racemization is the first ever to be observed for a reaction catalyzed by serine dehydratase, therefore confirming the distinction of the L-serine dehydratase of P. asaccharolyticus as an iron-sulfur protein from those dehydratases dependent on pyridoxal phosphate. For the latter enzymes exclusively, retention has been reported.

Carbon Radioisotopes↗
PubMed1992

Use of resorufin-labelled N-glycopeptide in a high-performance liquid chromatography assay to monitor endoglycosidase activities during cultivation of Flavobacterium meningosepticum.

Peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase F (PNGase F) and endo-beta-N-acetyl glucosaminidase F (Endo F) activities were monitored during cultivation of Flavobacterium meningosepticum using a new fluorescence-HPLC procedure based on a commercially available substrate. The PNGase F activity reached a maximum level at the end of the log phase and remained constant during the stationary phase, while Endo F continuously increased until late stationary phase. PNGase F obtained at the end of the log phase was less contaminated by other proteins compared with late stationary phase.

Amidohydrolases↗
PubMed1992

[Therapy of hemorrhagic shock using small volumes of hypertonic-hyperoncotic NaCl-dextran solution--effects on the brain].

Infusion of small volumes of hypertonic/hyperoncotic solution (HHL: 7.2% NaCl/10% dextran 60) is highly effective in haemorrhagic shock. Cardiovascular function is restored in a matter of minutes by rapid mobilisation of extravasal fluid. However, little experience has been collected to date on the side effects on the brain by this new form of shock therapy. The present studies on HHL were conducted with particular reference to cerebral blood flow, cerebral oxygen supply, and intracranial pressure. Haemorrhagic shock with a drop in arterial blood pressure to 40 mmHg over a period of 30 min was induced in rabbits under alpha-chloralose anaesthesia by means of bloodletting. Subsequently, the hypertonic/hyperoncotic solution (HHL) was infused into the experimental animals within two minutes. The regional cerebral blood flow (H2-clearance) and the cerebral O2 supply were studied by determining the pO2 of the cerebral cortex in experimental animals without haemorrhagic shock but with infusion of HHL. Finally, separate single tests were conducted to analyse the effect of the infusion of HHL on the intracranial pressure after induction of a focal cold lesion of the brain in combination with the implantation of a rubber balloon in the epidural space as an intracranial space-occupying growth. Infusion of HHL during shock produced rapid normalisation of cardiac output, whereas in normovolaemic animals without shock it produced a temporary increase of this parameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Mutations in the second-largest subunit of Drosophila RNA polymerase II interact with Ubx.

Specific mutations in the gene encoding the largest subunit of RNA polymerase II (RpII215) cause a partial transformation of a structure of the third thoracic segment, the capitellum, into the analogous structure of the second thoracic segment, the wing. This mutant phenotype is also caused by genetically reducing the cellular concentration of the transcription factor Ultrabithorax (Ubx). To recover mutations in the 140,000-D second-largest subunit of RNA polymerase II (RpII140) and determine whether any can cause a mutant phenotype similar to Ubx we attempted to identify all recessive-lethal mutable loci in a 340-kilobase deletion including this and other loci. One of the 13 complementation groups in this region encodes RpII140. Three RpII140 alleles cause a transformation of capitellum to wing but unlike RpII215 alleles, only when the concentration of Ubx protein is reduced by mutations in Ubx.

Alleles↗
PubMed1992

Treatment of hemorrhagic hypotension with hypertonic/hyperoncotic solutions: effects on regional cerebral blood flow and brain surface oxygen tension.

Hypertonic/hyperoncotic solutions (e.g. HHS: 7.2% NaCl/10% dextran-60) are highly effective to normalize cardiovascular function in hemorrhagic shock due to rapid mobilization of fluid from the extravascular compartment. Since experiences are limited with regard to potential side effects of this treatment on the central nervous system, the present studies were carried out under particular consideration of the cerebral blood flow and O2 supply. HHS was administered in albino rabbits subjected to alpha-chloralose anesthesia and artificial ventilation with and without hemorrhagic hypovolemia. Hemorrhagic hypovolemia of 30 min duration was induced by withdrawal of approximately one third of the circulating blood volume resulting in a decrease in arterial blood pressure to 40 mm Hg. HHS was studied in addition to normovolemic animals. Cardiac output was rapidly normalized by infusion of HHS in animals with hypovolemia, while it increased intermittently in normovolemic animals. In animals with hemorrhagic shock arterial blood pressure recovered by treatment to approximately 70% of normal, whereas blood pressure remained unchanged after infusion of HHS in normovolemic controls. Cerebral blood flow, which was assessed by H2 clearance at the brain surface, had a range of 43.0-50.3 ml/100 g/min under control conditions. It remained virtually unchanged during hemorrhagic hypovolemia and also after infusion of HHS in normovolemic animals. Treatment of shock by HHS was followed 90 or 120 min later by a moderate increase in regional cerebral blood flow to 61 ml/100 g/min. Local tissue PO2 at the brain surface was obtained by an O2 multiwire electrode in the vicinity of the H2 clearance measurements using a weightless suspension system to avoid compression of the brain surface. Infusion of HHS in normovolemic animals did not affect the O2 supply of the brain. Hemorrhagic hypovolemia which led to a left shift of the cerebral PO2 histogram was followed by gradual normalization after fluid resuscitation. The current findings taken together do not indicate adverse side effects of this efficient method of fluid resuscitation with regard to the cerebral blood and O2 supply. The results make worthwhile further investigations on HHS in the presence of a focal brain lesion causing brain edema to find out whether the HHS are useful also for the treatment of intracranial hypertension.

Animals↗
PubMed1992

[Enhanced lymphocyte proliferation in the presence of epidermal cells of HIV-infected patients in vitro].

Clinical observations show that the HIV infection is often associated with affections of the skin. In order to examine the involvement of the epidermal immune system in the HIV infection, we determined accessory cell function of epidermal cells from HIV-1-infected patients. For this we measured the proliferative response of enriched CD(4+)-T-lymphocytes from HIV-infected patients and noninfected controls to stimulation with anti-CD3 and IL-2 in the presence of epidermal cells; the enhancement of the response is dependent on the presence of functionally intact accessory cells. The capacity of epidermal cells to increase the anti-CD3-stimulated T-cell proliferative response was significantly enhanced in HIV patients (CDC III/IVA) as compared with noninfected donors. It is discussed, whether the increased activity of epidermal cells from HIV-infected patients may be responsible for several of the dermal lesions in the course of an HIV infection as due to an enhanced production and release of epidermal cell-derived cytokines.

Adult↗
PubMed1992

Cost-benefit analysis of a nationwide inoculation programme against viral hepatitis B in an area of intermediate endemicity.

The large decrease in the cost of vaccines against hepatitis virus B prompts a re-examination of nationwide vaccination campaign strategies. The present study estimates the costs and benefits that would result from a viral hepatitis B prevention programme (with no prior screening) targeted at all under-16-year-olds in Israel in 1990 and only neonates in the period 1991-2034. Israel is situated in an area of intermediate endemicity, where the majority of HBsAg carriers are anti-HBe positive. Such a policy would reduce the number of cases of viral hepatitis B in the vaccinated cohort from 654,000 to 270,000 over the period 1990-2059, yielding a benefit-to-cost ratio of 1.88: 1 for the health services only. Inclusion also of the indirect benefits of reduced work absences and mortality would increase the benefit-to-cost ratio to 2.77:1. Even when the benefits arising from the reduction in hepatocellular carcinoma and liver transplants were excluded, the benefit-to-cost ratio for the health services alone would still be 1.41:1. The adoption of such a nationwide inoculation policy appears therefore to be not only medically but also economically justifiable.

Adolescent↗
PubMed1991

Cyanobacteria contain a mitochondrial complex I-homologous NADH-dehydrogenase.

Thylakoid and cytoplasmic membranes of the cyanobacterium Synechocystis sp. PCC 6803 were purified by sucrose gradient centrifugation. Both membranes oxidize NADH in a rotenone-sensitive reaction. Antibodies prepared against psbG/ndhK and ndhJ fusion proteins detect the corresponding polypeptides in both membrane preparations. This demonstrates that a NADH-dehydrogenase, homologous to the mitochondrial NADH-ubiquinone-oxidoreductase (complex I of the respiratory chain) is present in cyanobacteria. The NADH-dehydrogenase can be solubilized with the detergent beta-D-dodecylmaltoside. Sedimentation analysis of the solubilized enzyme on a sucrose gradient indicates that it is a multisubunit protein complex.

Chromosome Mapping↗
PubMed1991

[Lymphocytes, Langerhans cells and CD68-positive monocytes/macrophages in the skin of HIV-infected patients and normal controls].

Human epidermal Langerhans cells play an important role in the immunoregulation of the skin. We measured the numbers of CD(3+)-, CD(8+)-, CD1a(+)-, HLADR(+)-, IL2R(+)-, CD(4+)- and CD68 positive cells in the skin of 8 asymptomatic HIV-infected Persons, 3 Patients with AIDS and 11 healthy volunteers by suction blister technique. Our results indicate increased numbers of CD1a+ cells and increased numbers of CD4+ cells in the epidermis in asymptomatic HIV-infection. At the same time CD68+ cells are decreased already in an early stage of HIV-Infection. The number of CD1a/CD4+ cells is related to the degree of immunodeficiency. This fact might be caused by the activation of MPS.

Acquired Immunodeficiency Syndrome↗
PubMed1991

[Blunt neck trauma].

Blunt neck trauma is usually caused by auto accidents and may result in various degrees of laryngeal injury. Treatment involves careful monitoring followed by surgical intervention when there is deterioration, or by early exploration and laryngeal fixation (internal or external). 16 patients treated for blunt neck trauma, ranging in age from 10-54 years (mean 27.7), were studied. Only 1 required surgical intervention.

Larynx↗
PubMed1991

Success rates in in vitro fertilization treatment and its correlation with high titer antibodies for Chlamydia trachomatis.

The prevalence of specific chlamydial IgG and IgA antibodies was determined in 86 infertile women undergoing in vitro fertilization (IVF) and in 56 male partners; 32.5% of women (28 of 86) under investigation had both types of antibodies at a titer of IgG greater than or equal to 1:128 and IgA greater than or equal to 1:16; 9% of their male partners (5 of 56) who were tested were also seropositive. The prevalence of local IgA in semen was 9.6% (5 of 52). Pregnancy was later achieved by IVF in 13 of 32 seropositive and 19 of 32 seronegative women. Our data suggest that high levels of specific antichlamydial antibodies (IgG and IgA) are not correlated with the outcome of IVF-embryo transfer treatment.

Adult↗