Search PubMed⌕ Search

Biomedical subjects

M Kruse

Publications and source records attributed to M Kruse.

At least 19 recordsLinked to original sources
PubMed1996

Interleukin-1 beta stimulates glucose uptake of human peritoneal mesothelial cells in vitro.

To investigate whether the glucose uptake (GU) of human peritoneal mesothelial cells (HPMC) is mediated by glucose transporters and whether this uptake is influenced by interleukin 1-beta (IL-1 beta), we measured 2-deoxy-(3H)-GU of HPMC in vitro, after exposing the cells for different times (two and 12 hours) to increasing concentrations (0.1, 1.0, and 2.0 ng/mL) of IL-1 beta. To exclude a noncarrier-mediated transport, GU was also tested in the presence of cytochalasin B. All experiments were performed in triplicate in the cells of two donors. Cytochalasin B inhibits GU of HPMC almost completely. GU of HPMC is not stimulated by insulin. GU is stimulated by IL-1 beta in a dose-dependent manner. These data indicate a GU of HPMC, which is mediated by a glucose transporter and stimulated by IL-1 beta. The increased uptake of glucose from the dialysate in patients with peritonitis may be mediated by a (cytokine-induced) increased activity of HPMC glucose transporters.

Blood Glucose↗
PubMed1995

Enzyme assembly after de novo synthesis in rabbit reticulocyte lysate involves molecular chaperones and immunophilins.

The folding kinetics of two luciferases were studied after synthesis in reticulocyte lysates to investigate whether molecular chaperones and/or folding catalysts are involved in the folding reactions. Two bacterial luciferases were used as model proteins: heterodimeric Vibrio harveyi luciferase (LuxAB), and a monomeric luciferase fusion protein (Fab2). Data indicate that folding of these enzymes to the native state occurs in the translation system, and that the extent of folding can be quantified. It was found that (i) folding of LuxAB and Fab2 can clearly be separated in time from synthesis, (ii) folding of Fab2 and LuxAB is slow because it involves either transient (Fab2) or permanent (LuxAB) interaction of polypeptides, (iii) preservation of the assembly competent state of LuxA and/or LuxB and folding of Fab2 depend on ATP-hydrolysis, (iv) folding of Fab2 and LuxAB is partially sensitive to cyclosporin A (CsA) and FK506, i.e. inhibitors of two distinct peptidylprolyl cis/trans-isomerases. Thus, bacterial luciferases provide a unique system for direct measurement of the effects of ATP-dependent molecular chaperones on protein folding and enzyme assembly in reticulocyte lysates. Furthermore, these two luciferases provide the first direct evidence documenting the involvement of peptidylprolyl cis/trans-isomerases in protein biogenesis in a eukaryotic cytosol.

Adenosine Triphosphate↗
PubMed1994

Molecular evidence for the presence of a developmental gene in the lowest animals: identification of a homeobox-like gene in the marine sponge Geodia cydonium.

During the development of higher animals, morphogenetic programs are switched on which are frequently controlled by homeotic genes. Until now these genes have not been identified in the lowest animals, the marine sponges. Since sponges show (i) an antero-posterior and/or dorso-ventral axis during embryogenesis and (ii) a complex differentiation pattern during spicula formation, we hypothesized that in sponges homeotic genes--if present--are also involved in the control of these processes. Therefore, we searched for homeobox or homeobox-like sequences in the marine sponge Geodia cydonium. Here we describe a homeobox-like sequence from these animals; it was isolated from a cDNA library of an adult specimen. The deduced amino acid sequence of the complete homeodomain shares over 70% similarity with other homeodomain sequences, including those from hydra, insects and vertebrates. These data indicate that the sponge homeodomain-like sequence is similar with respect to structure to those of other animals and may suggest that the sponge homeodomain-like sequence(s) might function during developmental processes and/or during spiculogenesis in a similar manner to that known for higher animals.

Amino Acid Sequence↗
PubMed1994

Dopamine alters glutamate receptor desensitization in retinal horizontal cells of the perch (Perca fluviatilis).

The patch-clamp technique in combination with a fast liquid filament application system was used to study the effect of dopamine on the glutamate receptor desensitization in horizontal cells of the perch (Perca fluviatilis). Kinetics of ligand-gated ion channels in fish horizontal cells are modulated by dopamine. This modulation is presumably mediated by a cAMP-dependent protein phosphorylation. Before incubation with dopamine, the glutamate receptors of horizontal cells activate and desensitize with fast time constants. In the whole-cell recording mode, fast application of the agonists L-glutamate, quisqualate, or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid prior to the dopamine incubation gives rise to fast transient currents with peak values of about 200 pA that desensitize within 100 ms. Kainate as agonist produced higher steady-state currents but no transient currents. After incubation of the cells with dopamine for 3 min, the desensitization was significantly reduced and the agonists L-glutamate, quisqualate, or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid induced steady-state currents with amplitudes that were similar to the previously observed transient currents. Kainate-induced currents were only slightly affected. Fast desensitizing currents upon fast application of L-glutamate were also recorded from outside-out patches that were excised from horizontal cells before incubation with dopamine. The currents from excised patches desensitized to a steady-state level of about 0.2 of the peak amplitude with time constants of less than 2 ms. When the outside-out patches were excised from cells after dopamine incubation, steady-state currents were enhanced and no transient currents were observed. The results may indicate that the dopamine-dependent modulation of glutamate-induced currents, which is presumably mediated by a protein phosphorylation, is due to an alteration of the desensitization of the glutamate receptors.

Animals↗
PubMed1994

Topology of the Glut 1 glucose transporter deduced from glycosylation scanning mutagenesis.

The erythrocyte glucose transporter (Glut 1) is predicted to contain 12 membrane-spanning domains based on the hydropathy plot of its deduced amino acid sequence. The membrane topology of Glut 1 was analyzed by a scanning mutagenesis procedure in which the glycosylated exofacial domain of Glut 4 was inserted independently into each of the putative hydrophilic soluble domains of an aglyco-Glut 1 construct. The transporter mutants were expressed both in vitro using a rabbit reticulocyte lysate translation system and in vivo in Xenopus oocytes. The cytoplasmic or exofacial orientation of each soluble domain was inferred from the glycosylation state of the corresponding insertion mutant. The results from the cell-free system were aberrant in that two topological orientations were observed when the epitope was inserted into any of the short cytoplasmic loops or the NH2 terminus. The in vivo data, however, were in complete agreement with the proposed 12-helix model. Therefore, the multiple topologies observed in vitro probably resulted from the inability of the cell-free system to facilitate the proper folding of the insertion mutants into the membrane. 2-Deoxyglucose uptake data on the glycosylation mutants indicated that epitope insertion into the NH2 terminus, the large central loop, or the second, third, or fifth exofacial loop had no dramatic effect on the activity of the transporter. However, insertion into the other soluble domains either completely abolished or significantly reduced transport activity.

Amino Acid Sequence↗
PubMed1994

Glutamine 161 of Glut1 glucose transporter is critical for transport activity and exofacial ligand binding.

The possible role of 5 transmembrane amino acid residues in the function of the Glut1 glucose transporter was investigated by site-directed mutagenesis. The residues were chosen based on their containing hydroxyl or amide side chains capable of hydrogen bonding to glucose and their complete conservation in Glut1 through Glut5. Asn100, Gln161, Gln200, Tyr292, and Tyr293 were individually replaced by hydrophobic and/or polar residues, and the mutants were analyzed by expression in Xenopus oocytes. Substitution of leucine or asparagine for Gln161 reduced the relative transport activity of Glut1 by 50- and 10-fold, respectively, as measured by uptake of 2-deoxyglucose normalized to the plasma membrane content of the mutant transporters. Substitutions at the other residues had either a modest (approximately 2-fold) effect or no effect on the relative transport activity. The Ki for binding of the exofacial ligand 4,6-O-ethylidene-alpha-D-glucose to Glut1 was increased by 18-fold upon substitution of asparagine for Gln161. The Km for zero-trans influx of 2-deoxyglucose was not affected by the substitution of asparagine for Gln161, but the catalytic turnover was decreased by 7.5-fold. These data, combined with the high degree of conservation of Gln161 among the specific members of the 12-helix membrane transporter superfamily that transport hexoses, support the contention that Gln161 forms part of the exofacial substrate-binding site of these molecules. However, the decreased transport activity resulting from mutations at Gln161 is likely due to an additional effect on the rate of a conformational change involved in net substrate uptake. This constitutes the first evidence that a residue within the NH2 terminal half of Glut1 is critical for transport function.

Amino Acid Sequence↗
PubMed1994

A mutation in the Glut2 glucose transporter gene of a diabetic patient abolishes transport activity.

Glut2, the facilitative glucose transporter isoform expressed in pancreatic beta cells, is believed to play a role in glucose-stimulated insulin secretion. Two polymorphisms that result in amino acid substitutions have been reported in the human Glut2 gene (Tanizawa, Y., Riggs, A. C., Chiu, K. C., Janssen, R. C., Bell, D. S. H., Go, R. P. C., Roseman, J. M., Acton, R. T., and Permutt, M. A. (1994) Diabetologia 37, 420-427). A threonine 110-->isoleucine substitution was present at equal frequency in diabetic and control populations, and a valine 197-->isoleucine substitution was discovered in a single allele of a patient with non-insulin-dependent diabetes. The effect of these amino acid changes on glucose transport activity was tested by expression of the mutant proteins in Xenopus oocytes. The polymorphism at threonine 110 had no effect on the expression of Glut2 protein or the uptake of 2-deoxyglucose. Remarkably, however, the highly conservative valine 197-->isoleucine amino acid change abolished transport activity of the Glut2 transporter expressed in Xenopus oocytes. This represents the first known dysfunctional mutation in a human facilitative glucose transporter protein. The presence of this mutation in a diabetic patient suggests that defects in Glut2 expression may be causally involved in the pathogenesis of non-insulin-dependent diabetes.

Animals↗
PubMed1994

Restriction fragment length polymorphism analysis of reverse transcription-PCR products reveals the existence of two major strain groups of beet necrotic yellow vein virus.

Beet necrotic yellow vein virus (BNYVV)-infected sugarbeets were obtained from many parts of Europe and also from some sites in Asia and the U.S.A. Reverse transcription (RT)-PCR products of more than 1 kbp were obtained for four different regions of the viral genome which may be particularly important with respect to the pathogenic properties of the virus, i.e. for the coat protein and the 42K protein-encoding regions on RNA 2 and for major parts of RNAs 3 and 4. Restriction fragment length polymorphism (RFLP) patterns obtained with these PCR products revealed the existence of two major strain groups of BNYVV, named type A and type B. The A type was detected in Greece, the former Yugoslavia, Slovakia, parts of Austria, Italy, Spain, parts of France, Belgium, The Netherlands and England as well as in Asia (Turkey, Kazachstan, China and Japan) and the U.S.A. The B type occurs in Germany and parts of France. Mixed infections were detected at the borderline regions between areas of the A and B types. Comparisons of published and newly determined nucleotide sequences of the respective parts of the BNYVV genome indicate that the percentage of nucleotide differences between the A and the B type is approximately 3% for the respective regions of RNAs 2 and 3 and approximately 1.5% for RNA 4. Nucleotide sequences appear to be remarkably stable within each of the two strain groups. The majority of the nucleotide differences between the A and B types occur in the third triplet position. The amino acid changes in the coat protein area are outside the four previously determined antigenic regions that are accessible on the surface of the virus particles and are involved in the formation of continuous and presumably also discontinuous epitopes. This may explain why serological differences between the two strain groups have not been found.

Base Sequence↗
PubMed1994

Detection of human immunodeficiency virus-1 nucleic acid on inactivated filter paper disks by polymerase chain reaction and microtiter plate assay.

Human immunodeficiency virus type 1 (HIV-1) in cultured cells, peripheral blood samples and sera were adsorbed on filter paper disks and inactivated by heat or ethanol. Two procedures, the polymerase chain reaction (PCR) and microtiter plate assay (HMPA) were used to detect the nucleic acid. The sensitivity after different heat treatments with nested PCR for HIV-1 DNA (or nested reverse transcription-PCR for HIV-1 RNA) was identical regardless of whether the samples were examined immediately or one month later. Inactivation by ethanol treatment resulted in a slight loss of sensitivity. The HMPA proved to be as reliable and specific as the conventional PCR technique. We conclude that the heat-treated filter paper disk assay is suitable for identifying HIV nucleic acid in clinical samples sent to the laboratory from a distance, e.g. in an envelope.

Base Sequence↗
PubMed1994

Cell adhesion receptors and nuclear receptors are highly conserved from the lowest metazoa (marine sponges) to vertebrates.

The shift from unicellular life to multicellular, integrated organisms has been accompanied by the acquisition of adhesion proteins/receptors. Recently we succeeded to clone some genes coding for such proteins from the lowest multicellular animals, the marine sponges (model: the siliceous sponge Geodia cydonium). G. cydonium contains e.g. several lectins; cDNAs for two of them were cloned. Both lectins have a framework sequence of 38 conserved amino acids which are characteristic for the carbohydrate binding site of vertebrate S-type lectins. Next, the cDNA coding for a receptor tyrosine kinase of class II was isolated and characterized. The deduced aa sequence shows two characteristic domains; (i) the tyrosine kinase domain and (ii) an immunoglobulin-like domain. The latter part displays high homology to the vertebrate type immunoglobulin domain. This result together with the lectin data demonstrates that binding domains of such adhesion proteins are not recent achievements of higher animals but exist already in animals (sponges) which have diverged from other organisms about 800 million years ago. Considering the fact that during embryogenesis of sponges a typical anteroposterior organization pattern is seen a 'home-otic' organ-like transformation has been postulated. The subsequent search for genes provided with the homeodomain-like sequence was successful. These data support the view that the kingdom Animalia is of monophyletic origin.

Amino Acid Sequence↗
PubMed1994

[Possibility for detecting HIV-1 in bone transplant by PCR using the HIV-1 microtiter plate assay].

It is known that HIV can be transmitted by allogenous bone transplantation. Hitherto neither chemical nor physical methods have existed to allow reliable disinfection and sterilization of bone specimens without reducing osteogenetic potency. Only demonstration or exclusion of the presence of HIV-1 in a bone specimen guarantees that infection will not occur. The method now presented for HIV detection is based on a polymerase chain reaction (PCR). This HIV microtiter-plate assay combines amplification of DNA molecules with a staining reaction. In cultures containing HIV-infected cells definite detection of viruses was possible when 50-100 cells per specimen were infected. Examination of 137 HIV-negative and 25 HIV-positive bone specimens showed sensitivity of 96% and specificity of 97.8% for the test. In subsequent studies, after drying on filter paper viral DNA was again demonstrable by the PCR. This means safe handling and uncomplicated transportation of non-infectious specimens to a central analysis laboratory are possible. This HIV test offers the possibility of quick and safe demonstration that specimens are free of HIV and is therefore likely to enhance the safety of bone transplantation considerably.

Bone Transplantation↗
PubMed1993

Studies on the dopamine-dependent modulation of amino acid-gated currents in cone horizontal cells of the perch (Perca fluviatilis).

The whole-cell patch-clamp technique was employed to record membrane currents from isolated horizontal cells in culture. Concentration-response relationships for currents induced by L-glutamate, kainate and quisqualate were measured. Preincubation with dopamine changed the parameters of the concentration-response curves in a particular way for each agonist. The maximum currents induced by glutamate increased by 50-100% and the EC50-values were slightly shifted to higher values. The increase of kainate-induced maximum currents after dopamine incubation did not exceed 30% but the EC50-values were clearly shifted to lower concentrations. Quisqualate-induced maximum currents were not enhanced by dopamine preincubation but the EC50-values were shifted to lower concentrations. The dopamine-dependent modulation was affected by removal of magnesium and preincubation with concanavalin A and aniracetam. The concentration-response relation and the time-course of the dopamine effect on glutamate-induced currents is described.

Animals↗
PubMed1985

Practical problems in assessing risk for coronary artery bypass grafting.

In order to put results of a surgical program in proper prospective, risk factors for the population being treated should be carefully assessed. This paper discusses the practical problems involved in determining the risk of surgical mortality for patients undergoing isolated coronary artery bypass grafting. A risk equation developed by the Collaborative Study in Coronary Artery Bypass was applied to a veterans hospital population. A simplified method of determining left ventricular function from clinical angiography reports was found to be a reasonable substitute for the more complex left ventricular scoring system used by the collaborative study. Results showed the veterans group to be at increased risk, primarily due to an older average age and higher incidence of left ventricular dysfunction.

Adult↗
PubMed1984

Changes in sex differences in sexual behavior: a replication of a study on West German students (1966-1981).

In 1966, at the start of the student movement and the sexual liberalization process, we studied the sexual behavior and attitudes of 3,666 male and female students from 12 West German universities by mailed questionnaires. In 1981 we replicated this study with 1,922 students from 13 universities (10 the same as 1966, 3 founded after 1966). In both studies the students were selected at random. Results of these comparative studies are presented with a view to the changes in sex differences. Sex differences in masturbation behavior have considerably decreased since 1966; masturbation is nonetheless still the form of sexual behavior with the most striking differences between the sexes. The sex differences in coital behavior are now reversed, female students being earlier and more active than males. As regards the tendency to change partners or for sexual relations outside a steady relationship, the differences between men and women have disappeared. In their attitudes to sexuality, female students in 1981 are somewhat more liberal than their male counterparts, whereas hardly any difference could be found in 1966. These changes in sex differences are observed in all subsamples, i.e., in young and old, in strictly religious and nonreligious students, and in students from both upper- and lower-class backgrounds (educational level of parents).

Adult↗