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Biomedical subjects

A Haas

Publications and source records attributed to A Haas.

At least 91 records · Page 5Linked to original sources
PubMed1994

Vitamin E inhibits retinal pigment epithelium cell proliferation in vitro.

Retinal pigment epithelium (RPE) cells migrating through the damaged retina play an important role in the pathogenesis of proliferative vitreoretinopathy (PVR). We found that alpha-tocopherol (vitamin E) inhibits proliferation of human RPE in culture without exerting cytotoxic effects. Maximal inhibition was achieved with 100 microM alpha-tocopherol. Our result could explain the observation that vitamin E supplements have an adverse effect on light-damaged retina and on the course of retinitis pigmentosa. Since it has been shown that supplemental oral administrations of vitamin E can raise the RPE concentration of alpha-tocopherol well above 100 microM and supplementation is not associated with any clinical relevant adverse effect, we believe that vitamin E could be beneficial in the treatment of PVR.

Adult↗
PubMed1994

[Heparin-induced extracorporeal LDL precipitation (H.E.L.P.). A new therapeutic possibility in vascular occlusion of the retina--initial results].

Heparin-induced extracorporeal LDL precipitation (HELP) eliminates selectively fibrinogen, LDL cholesterol, cholesterol, triglycerides and LP(a) from the blood plasma using extracorporeal circulation. The reduction of fibrinogen and LDL about 50% after only one procedure immediately improves the hemorrheological situation, which has so far not been achieved by any hemorrheologically active substance. Five patients (1 central retinal vein occlusion, 3 branch vein occlusions, 1 central arterial occlusion) ranging from 59-76 years underwent HELP treatment six times over a 5-week period. After the first HELP procedure the fibrinogen was lowered from 278 +/- 57.8 to 157 +/- 22.2 mg/dl and LDL from 162.2 +/- 58 to 82.4 +/- 32.5 mg/dl. Plasma viscosity decreased from 1.3 +/- 0.07 to 1.1 +/- 0.05 mPa/s. At the end of the treatment an increase in visual acuity of 3 or more lines and an improvement in the visual field was seen in all patients. Measurements of the arteriovenous passage time with laser scan video fluorescein angiography before and at the end of the therapy showed a significant decrease from 3.5 +/- 1.59 to 2.88 +/- 1.54 s (P < 0.05) without influencing the arm-retina time. This first clinical and hemorrheological data on the HELP procedure in retinal vessel occlusion demonstrate a promising regimen in the treatment of acute retinal microcirculatory diseases.

Aged↗
PubMed1993

Specific regulation of male rat liver cytosolic estrogen receptor by the modulator of the glucocorticoid receptor.

Modulator is a novel low-molecular-weight organic compound that regulates activities of glucocorticoid and mineralocorticoid receptors as well as protein kinase C. In this study we show that male rat liver cytosolic estrogen receptor activation is inhibited by modulator in a dose-dependent manner. Fifty percent inhibition is obtained with 1 unit/ml modulator purified from bovine liver which is within the physiological concentration for modulator. However, sheep uterine cytosolic estrogen and androgen receptors are insensitive to regulation by modulator. Exogenous sodium molybdate treatment inhibits activation of all of these receptors of liver or uterus origin in an identical manner, further differentiating the effects of modulator and the molybdate anion.

Adrenalectomy↗
PubMed1993

Fetal development of the human orbit.

The development of the orbits in 70 human fetal skulls was investigated by measuring the width and height of the orbital entrance, as well as the volume and depth of the orbital cavity and the interorbital width. For determination of the orbital volume, we used the imprint method; the remaining parameters were estimated. Our measurements showed a linear growth rate for the orbital width, height, and depth. After transformation to the cubic root, the values of the orbital volume also demonstrated a linear increase. The orbital index (height/width x 100) expressed the change in the oval outline of the orbital entrance during fetal development from a flat, wide form to a nearly round form at birth. No statistically significant difference between the right and left orbit was found.

Anthropometry↗
PubMed1992

A gene encoding a superoxide dismutase of the facultative intracellular bacterium Listeria monocytogenes.

A gene (lmsod) encoding superoxide dismutase (SOD; EC 1.15.1.1) of the facultative intracellular pathogen, Listeria monocytogenes, was cloned by functional complementation of an SOD-deficient Escherichia coli mutant. The nucleotide sequence was determined and the deduced amino acid (aa) sequence (202 aa) showed close similarity to manganese-containing SOD's from other organisms. Subunits of the recombinant L. monocytogenes SOD (re-SOD) and of both E. coli SODs formed enzymatically active hybrid enzymes in vivo. DNA/DNA-hybridization experiments showed that this type of recombinant re-sod gene is conserved within the genus Listeria.

Amino Acid Sequence↗
PubMed1992

Listeriolysin genes: complete sequence of ilo from Listeria ivanovii and of lso from Listeria seeligeri.

The complete DNA sequences coding for the thiol-activated cytolysins from Listeria ivanovii, ivanolysin O (ILO) and for seeligerolysin O (LSO) from Listeria seeligeri have been determined. The deduced amino acid sequences revealed that: (i) the primary translation products comprise 528 (ILO) and 530 (LSO) amino acids, respectively, (ii) ILO contains two cysteines, LSO has a substitution in the conserved cysteine motif.

Amino Acid Sequence↗
PubMed1992

Cloning of a superoxide dismutase gene from Listeria ivanovii by functional complementation in Escherichia coli and characterization of the gene product.

A gene encoding superoxide dismutase (EC 1.15.1.1., SOD) was isolated from a plasmid library of chromosomal DNA from Listeria ivanovii by functional complementation of an SOD-negative Escherichia coli host. The nucleotide sequence of the cloned gene was determined and contained an open reading frame which codes for a protein of 202 amino acid residues (calculated molecular weight 22755 Da including the amino-terminal methionine residue). Comparison of the deduced amino acid sequence of L. ivanovii SOD with previously reported SOD amino acid sequences revealed considerable homologies with Fe- and Mn-dependent SODs. Enzymatic analyses using cell lysates and the purified recombinant enzyme indicated that this SOD is manganese-dependent. The recombinant SOD accounted for up to 30% of the total soluble protein in recombinant E. coli and protected sodA sodB mutants against the toxic effects of paraquat. Subunits of the recombinant Listeria SOD and of both E. coli SODs formed enzymatically active hybrids in vivo.

Amino Acid Sequence↗
PubMed1992

[Perimetry findings before and after surgical removal of epimacular membranes].

The visual acuity and the central visual field (Octopus program M1) were analyzed before and after peeling of epimacular membranes (EMM) in 18 eyes. The EMM were classified according to their etiology as idiopathic, secondary nonvascular and secondary vascular. A large variability of initial visual field indices was found pre- and postoperatively (table 1). The least functional improvement was found following peeling of EMM with a history of more than 12 months as well as of idiopathic EMM with an initial mean defect (MD) of greater than 3 dB (fig. 8 und 9). The best success rate was achieved for eyes with idiopathic EMM and MD less than or equal to 3 dB and for eyes with secondary nonvascular EMM (fig. 6 and 7). The visual acuity but not the MD improved postoperatively in the 3 eyes with vascular EMM which had developed after a retinal vascular branch occlusion.

Aged↗
PubMed1992

Microbial strategies to prevent oxygen-dependent killing by phagocytes.

Microorganisms which are taken up by professional phagocytic cells of a host organism (e.g., by macrophages and polymorphonuclear leukocytes) encounter a series of antimicrobial events including confrontation with toxic oxygen species, derived mainly from the superoxide radical produced by phagocytic NADPH oxidase after uptake of the microorganism. Many microbes are susceptible to the oxygen-dependent phagocytic stress and are efficiently killed. The strategies of some microorganisms to bypass an encounter with the phagocytes' reactive oxygen species, and biochemical systems contributing to the microbes' resistance to killing by reactive oxygen species are outlined.

Animals↗
PubMed1992

Zinc in lymphocytes--the assessment of zinc status in patients with Crohn's disease.

A group of 26 Crohn's disease patients was compared to a healthy control group with regard to their zinc status in plasma, urine, hair, and lymphocytes. A method for lymphocyte preparation, which was in part newly designed, was used; it proved to be very effective as to recovery and purity of the harvested cell fraction. Results of the study suggest that an accurate estimation of zinc status can be more reliably obtained by determination of lymphocyte zinc--provided the cell preparation described is used--than by using any other of the examined body compartments.

Adolescent↗
PubMed1991

Cloning, characterization, and expression in Escherichia coli of a gene encoding Listeria seeligeri catalase, a bacterial enzyme highly homologous to mammalian catalases.

A gene coding for catalase (hydrogen-peroxide:hydrogen-peroxide oxidoreductase; EC 1.11.1.6) of the gram-positive bacterium Listeria seeligeri was cloned from a plasmid library of EcoRI-digested chromosomal DNA, with Escherichia coli DH5 alpha as a host. The recombinant catalase was expressed in E. coli to an enzymatic activity approximately 50 times that of the combined E. coli catalases. The nucleotide sequence was determined, and the deduced amino acid sequence revealed 43.2% amino acid sequence identity between bovine liver catalase and L. seeligeri catalase. Most of the amino acid residues which are involved in catalytic activity, the formation of the active center accession channel, and heme binding in bovine liver catalase were also present in L. seeligeri catalase at the corresponding positions. The recombinant protein contained 488 amino acid residues and had a calculated molecular weight of 55,869. The predicted isoelectric point was 5.0. Enzymatic and genetic analyses showed that there is most probably a single catalase of this type in L. seeligeri. A perfect 21-bp inverted repeat, which was highly homologous to previously reported binding sequences of the Fur (ferric uptake regulon) protein of E. coli, was detected next to the putative promoter region of the L. seeligeri catalase gene.

Amino Acid Sequence↗
PubMed1991

Cloning and expression in Escherichia coli of a gene encoding superoxide dismutase from Listeria ivanovii.

A chromosomal DNA fragment from the gram-positive bacterium Listeria ivanovii (ATCC 19119) encoding a superoxide dismutase (SOD) gene has been cloned in Escherichia coli QC779 (sodAsodB) using the plasmid vector pTZ19R. The DNA fragment inserted into the plasmid showed high structural instability in E. coli QC779 (recA+), but turned out to be a stable 1.95 kbp DNA fragment when transformed into E. coli DH5 alpha (recA-). The gene is expressed in both of these E. coli strains at high levels. Preliminary studies showed that the activity of the recombinant SOD within E. coli DH5 alpha was up to 13-times the combined activity of both E. coli SODs. The recombinant SOD forms active hybrid SODs with both E. coli SODs in vivo.

Bacterial Proteins↗
PubMed1991

Activation of the ubiquitin-ATP-dependent proteolytic system in skeletal muscle during fasting and denervation atrophy.

The rapid atrophy of skeletal muscles upon fasting or denervation is due largely to an increased rate of protein breakdown. Blocking the lysosomal or the Ca(2+)-dependent pathways did not prevent increased proteolysis in muscles from fasted animals or following denervation. In contrast, upon food deprivation, the nonlysosomal ATP-dependent process increased by 150-350%. After refeeding, this process returned to control levels by 24 h. Similarly, within one day after denervation of the soleus, proteolysis increased by 50-250%. By contrast, the residual energy-independent process did not change in fasting or denervation. Because the ATP-dependent process might involve activation of the ubiquitin-ATP-dependent pathway, we measured the levels of mRNA for ubiquitin [Ub] in the atrophying muscles. After food deprivation, the levels of polyUb transcripts increased 2- to 4-fold in the soleus and extensor digitorum longus (EDL) muscles, and returned to control levels within 1 day of refeeding. After denervation of the soleus, a 2- to 3-fold increase in polyUb mRNA also occurred within 1 day. The muscle content of ubiquitinated protein also changed in parallel with Ub mRNA levels under these conditions. Thus, polyUb genes appear to be selectively induced in atrophying muscle, and levels of Ub mRNA and ubiquitin-protein conjugates change coordinately with the rate of ATP-dependent proteolysis. These data suggest that in atrophying muscle the ATP-Ub-dependent system plays an important physiological role in the degradation of the bulk of cell proteins.

Adenosine Triphosphate↗
PubMed1990

Ubiquitin-mediated degradation of histone H3 does not require the substrate-binding ubiquitin protein ligase, E3, or attachment of polyubiquitin chains.

Radioiodinated histone H3 was incubated with ubiquitin, the ubiquitin-activating enzyme E1, and one of three ubiquitin carrier proteins, reticulocyte E2(20K) or E2(32K) or the yeast RAD6 product. Although the resulting ubiquitin-histone conjugates were synthesized in the absence of the substrate-binding protein E3, they were nevertheless degraded by purified rabbit reticulocyte 26 S protease. In contrast, unmodified histone H3 remained intact upon challenge with the 26 S ubiquitin/ATP-dependent enzyme. Conjugates produced by the RAD6 protein were better proteolytic substrates than those formed by reticulocyte E2 unless ubiquitin molecules with altered lysines were used for conjugate synthesis. Substitution of methylated ubiquitin or ubiquitin molecules in which lysine 48 was converted to arginine by site-directed mutation produced histone conjugates that were degraded at slow but measurable rates. Since methylated ubiquitin molecules are incapable of forming branched polyubiquitin chains, these results demonstrate that neither ubiquitin "trees" nor the substrate binding factor E3 is absolutely required for ubiquitin-dependent degradation of histone H3 in vitro.

Animals↗
PubMed1990

Enzyme visualization with partially dehydrated agarose substrate layers: detection of paraoxonase after thin-layer isoelectric focusing in agarose.

A new approach is described for studying the polymorphism of paraoxon hydrolyzing serum esterases after isoelectric focusing of native sera. Enzyme visualization is performed by a modified sandwich procedure which is faster and also affords higher resolution and considerably improved sensitivity. Up to seven paraoxon splitting isoenzymes can be visualized and clearly distinguished from arylesterases and phosphatases by using 3-naphtyl acetate, paraoxon, 5-bromo-4-chloro-3-indolyl acetate and 5-bromo-4-chloro-3-indolyl phosphate as substrates. The new technique is also able to differentiate between paraoxonase isoenzymes sensitive to EDTA and those which are EDTA-stable. Immunofixation with anti-human serum albumin-antibodies revealed similar isoelectric points for these isoenzymes, although they are not assumed to be identical. The new technique may prove useful in other applications of enzyme visualization where diffusion of enzymes and/or cleavage products is the major problem.

Aryldialkylphosphatase↗
PubMed1990

Treatment of massive rhinophyma with the carbon dioxide laser.

A case of massive rhinophyma that produced significant functional and cosmetic difficulties was treated using the carbon dioxide laser. Minimal bleeding occurred during the operative procedure despite the grotesque enlargement and high degree of vascularity of the skin and soft tissue. Using this technique, restoration of normal function and excellent cosmesis was possible without complication.

Aged↗
PubMed1990

Glyceraldehyde-3-phosphate dehydrogenase from the hyperthermophilic archaebacterium Pyrococcus woesei: characterization of the enzyme, cloning and sequencing of the gene, and expression in Escherichia coli.

The glyceraldehyde-3-phosphate dehydrogenase from the hyperthermophilic archaebacterium Pyrococcus woesei (optimal growth temperature, 100 to 103 degrees C) was purified to homogeneity. This enzyme was strictly phosphate dependent, utilized either NAD+ or NADP+, and was insensitive to pentalenolactone like the enzyme from the methanogenic archaebacterium Methanothermus fervidus. The enzyme exhibited a considerable thermostability, with a 44-min half-life at 100 degrees C. The amino acid sequence of the glyceraldehyde-3-phosphate dehydrogenase from P. woesei was deduced from the nucleotide sequence of the coding gene. Compared with the enzyme homologs from mesophilic archaebacteria (Methanobacterium bryantii, Methanobacterium formicicum) and an extremely thermophilic archaebacterium (Methanothermus fervidus), the primary structure of the P. woesei enzyme exhibited a strikingly high proportion of aromatic amino acid residues and a low proportion of sulfur-containing residues. The coding gene of P. woesei was expressed at a high level in Escherichia coli, thus providing an ideal basis for detailed structural and functional studies of that enzyme.

Amino Acid Sequence↗