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Biomedical subjects

W Kraus

Publications and source records attributed to W Kraus.

At least 19 recordsLinked to original sources
PubMed1998

Combination of LC-MS and LC-NMR as a Tool for the Structure Determination of Natural Products

Application of both LC-MS and LC-NMR to a partially purified extract of Vernonia fastigiataled to the direct identification of antibacterial sesquiterpene lactones 1-9 without isolation of individual compounds. The rapid structural analysis of both major and minor components of this class of compounds demonstrated the power of structure-guided screening as a complementary method to assay-guided screening.

Journal Article↗
PubMed1998

Effects of extremely low frequency electromagnetic field (EMF) on collagen type I mRNA expression and extracellular matrix synthesis of human osteoblastic cells.

Human osteoblastic cells were grown in a three-dimensional (3-D) cell culture model and used to test the effects of a 20 Hz sinusoidal electromagnetic field (EMF; 6 mT and 113 mV/cm max) on collagen type I mRNA expression and extracellular matrix formation in comparison with the effects of growth factors. The cells were isolated from trabecular bone of a healthy individual (HO-197) and from a patient presenting with myositis ossificans (MO-192) and grown in a collagenous sponge-like substrate. Maximal enhancement of collagen type I expression after EMF treatment was 3.7-fold in HO-197 cells and 5.4-fold in MO-192 cells. Similar enhancement was found after transforming growth factor-beta (TGF-beta) and insulin-like growth factor-I (IGF-I) treatment. Combined treatment of the cells with EMF and the two growth factors TGF-beta and IGF-I did not act synergistically. MO-192 cells produced an osteoblast-characteristic extracellular matrix containing collagen type I, alkaline phosphatase, and osteocalcin, together with collagen type III, TP-1, and TP-3, two epitopes of an osteoblastic differentiation marker. The data suggest that the effects of EMFs on osteoblastic differentiation are comparable to those of TGF-beta and IGF-I. We conclude that EMF effects in the treatment of skeletal disorders and in orthopedic adjuvant therapy are mediated via enhancement of collagen type I mRNA expression, which may lead to extensive extracellular matrix synthesis.

Cell Line↗
PubMed1997

Rhodanine resistance and dependence of echovirus 12: a possible consequence of capsid flexibility.

Recombinant viruses of echovirus 12 carrying mutations of a rhodanine-resistant or -dependent variant, were investigated, and five single mutations each inducing a rhodanine-resistant or -dependent phenotype were defined. Four mutations are localized in the capsid protein VP1, and the fifth exchange is in VP4. All original and recombinant viruses were shown to be stabilized by the antiviral drug rhodanine against heat inactivation. Hence, resistant and dependent variants still seem able to bind rhodanine, and apparently none of the exchanges affects the putative drug binding site. We hypothesize that drug resistance and dependence are consequences of an increased flexibility of the virus capsid.

Amino Acid Sequence↗
PubMed1996

The in vivo quantification of myocardial performance in rabbits: a model for evaluation of cardiac gene therapy.

Evaluating cardiac gene therapy in the intact animal requires an index of cardiac function capable of detecting regional differences in contractility in a load-independent fashion. Potentially load-insensitive measures of ventricular performance were therefore evaluated in 10 open- and closed-chested, anesthetized rabbits. LV transmural pressure and myocardial segment length were measured using micromanometry and sonomicrometry during steady-state and transient inferior vena caval occlusion, over a range of inotropic and loading conditions. For each intervention, segmental stroke work was calculated as the area within the left ventricular transmural pressure-length loops at a given end-diastolic segment length during inferior vena caval occlusion; regression analysis was applied to obtain the linear Frank-Starling relationship. In both open- and closed-chested states, these relationships were highly linear (r = 0.97 +/- 0.1) and reproducible. The slope of the linear relationship between segmental stroke work and end-diastolic segment length increased significantly with calcium and epinephrine infusions (P < 0.05 v control) but was not significantly altered by decreased afterload or increased afterload (P > 0.4). The x-intercept was not significantly altered by changes in intropy or afterload (P > 0.4). These data validate the linear Frank-Starling relationship and the slope, MW, as a load-insensitive index of contractility in the intact rabbit. This study presents a novel approach to the quantification of regional cardiac function in smaller animals.

Animals↗
PubMed1995

Complete nucleotide sequence and biological properties of an infectious clone of prototype echovirus 9.

The prototype Hill of echovirus 9, a human enterovirus, exhibits no pathogenicity for newborn mice in contrast to some other echovirus 9 strains isolated subsequently during epidemics. In this communication we report the first complete nucleotide sequence and construction of an infectious clone of echovirus 9. Aside from the 3' poly(A)-tract, the RNA genome is 7420 nucleotides (nt) in length and encodes a single polyprotein of 2193 amino acids (aa). The open reading frame extends from position 740 to position 7318 of the genome. Sequence comparisons to other enteroviruses reveal a strong overall amino acid identity to echovirus types 11 and 12 (in each case 76%). The proteolytic cleavage sites of the three major capsid proteins were determined after purification by HPLC and protein sequencing. A full-length clone coding for an infectious RNA transcript was constructed, and recombinant echovirus 9 particles could be isolated from the supernatant of transfected cell culture. It is shown that the recombinant virus, like the original prototype, is non-pathogenic for newborn mice and does not multiply in skeletal muscles.

Amino Acid Sequence↗
PubMed1995

Centrally tinted contact lenses. A useful visual aid for patients with achromatopsia.

Achromatopsia (rod monochromacy) is a congenital color-vision defect of autosomal recessive inheritance due to severely abnormal or totally absent cone function. The disease is characterized by markedly reduced visual acuity, nystagmus, and, often, ametropia. Even under normal daylight conditions, these patients are extremely handicapped by glare because of a lack of rod inhibition by the abnormal or deficient cones. Light-absorbing glasses (absorption > 90%) can ameliorate this visual impairment to a certain extent but are sometimes not accepted by the patient since they are felt to disfigure the face. Especially during the first few years of school, this can lead to psychological problems. A special contact lens (Hydroflex, Wöhlk Company, Kiel) with a centrally tinted area (absorption 80%) that is slightly greater in diameter than the pupil under daylight conditions can correct ametropia and reduce light exposure and dazzle in a cosmetically much better way. Our first experience with this kind of visual aid in a 9-year-old girl suffering from incomplete achromatopsia is presented.

Child↗
PubMed1994

Epigenetic lesions at the H19 locus in Wilms' tumour patients.

To test the potential role of H19 as a tumour suppressor gene we have examined its expression and DNA methylation in Wilms' tumours (WTs). In most WTs (18/25), H19 RNA was reduced at least 20-fold from fetal kidney levels. Of the expression-negative tumours ten retained 11p15.5 heterozygosity: in nine of these, H19 DNA was biallelically hypermethylated and in two cases hypermethylation locally restricted to H19 sequences was also present in the non-neoplastic kidney parenchyma. IGF2 mRNA was expressed in most but not all WTs and expression patterns were consistent with IGF2/H19 enhancer competition without obligate inverse coupling. These observations implicate genetic and epigenetic inactivation of H19 in Wilms' tumorigenesis.

Alleles↗
PubMed1992

[The effect of the calf spleen and calf thymus extracts, thymopentin and tuftsin, on the phagocytosis activity of neutrophilic granulocytes].

In the present in vitro study, the influence of proteolytic as well as untreated spleen and thymus extracts and, as a comparison, of biologically active peptides tuftsin and thymopentin on the phagocytic activities of human polymorphonuclear leukocytes was investigated. At a chosen concentration of 200 micrograms/ml, all products studied exhibited a significant stimulation of polymorphonuclear leukocyte activity, when lucigenin-amplified chemiluminescence was measured. This effect was considerably enhanced with tuftsin, thymopentin and spleen extract, compared to the thymus preparations. No difference in chemiluminescence was obvious between hydrolyzed and untreated thymus extracts. In parallel experiments, phagocytosis of opsonized zymosan was investigated by light microscopy. Using identical substrate concentrations, only spleen extract showed significant stimulation. This observation indicates that the investigated polymorphonuclear leukocyte activities may be caused by substrate-specific mechanism on the cellular level.

Adult↗
PubMed1991

Control of ligand specificity in cyclic nucleotide-gated channels from rod photoreceptors and olfactory epithelium.

Cyclic nucleotide-gated ionic channels in photoreceptors and olfactory sensory neurons are activated by binding of cGMP or cAMP to a receptor site on the channel polypeptide. By site-directed mutagenesis and functional expression of bovine wild-type and mutant channels in Xenopus oocytes, we have tested the hypothesis that an alanine/threonine difference in the cyclic nucleotide-binding site determines the specificity of ligand binding, as has been proposed for cyclic nucleotide-dependent protein kinases [Weber, I.T., Shabb, J.B. & Corbin, J.D. (1989) Biochemistry 28, 6122-6127]. The wild-type olfactory channel is approximately 25-fold more sensitive to both cAMP and cGMP than the wild-type rod photoreceptor channel, and both channels are 30- to 40-fold more sensitive to cGMP than to cAMP. Substitution of the respective threonine by alanine in the rod photoreceptor and olfactory channels decreases the cGMP sensitivity of channel activation 30-fold but little affects activation by cAMP. Substitution of threonine by serine, an amino acid that also carries a hydroxyl group, even improves cGMP sensitivity of the wild-type channels 2- to 5-fold. We conclude that the hydroxyl group of Thr-560 (rod) and Thr-537 (olfactory) forms an additional hydrogen bond with cGMP, but not cAMP, and thereby provides the structural basis for ligand discrimination in cyclic nucleotide-gated channels.

Alanine↗
PubMed1991

Epitopes of group A streptococcal M protein shared with antigens of articular cartilage and synovium.

Rabbit antisera evoked by purified pepsin-extracted group A streptococcal M proteins were screened for the presence of joint cross-reactive antibodies by indirect immunofluorescence using thin sections of mouse knee joints. Pep M1, M5, and M18 antisera contained antibodies that cross-reacted with chondrocytes, cartilage, and synovium. Immunofluorescence inhibition assays showed that some of the joint cross-reactive epitopes were shared among the three heterologous serotypes of M protein. The pep M5 joint cross-reactive epitopes were localized to three different synthetic peptides of the C-terminal region of pep M5. Immunoblot analyses showed that the M5 joint cross-reactive antibodies recognized two proteins of human synovium and cartilage of molecular mass 56 and 58 kDa. The cross-reactive antibodies binding to the 56-kDa protein were inhibited by purified vimentin in immunoblot inhibition experiments. M protein-specific antibodies from patients with acute rheumatic fever were also shown to cross-react with joint tissue in a pattern similar to the rabbit antisera. Rabbit and human M protein-specific antibodies that were bound to articular cartilage activated significant levels of complement when compared to control serum, suggesting that M protein joint cross-reactive antibodies could potentially be involved in the pathogenesis of ARF and arthritis.

Antibodies, Bacterial↗
PubMed1990

Identification of an epitope of type 1 streptococcal M protein that is shared with a 43-kDa protein of human myocardium and renal glomeruli.

The localization of opsonic and tissue-cross-reactive epitopes within the amino terminus of type 1 streptococcal M protein was investigated by using murine mAb raised against synthetic peptides of type 1 M protein. Two mAb (IIIA2 and IIIB8) reacted with epitopes located within amino acid residues 1-12 of type 1 M protein. These antibodies opsonized type 1 streptococci and did not cross-react with human kidney and heart tissue. Another mAb (IC7) reacted with mesangial cells of renal glomeruli and human myocardium. The cross-reactive epitope of mAb IC7 was localized to position 13-19, indicating that it is not the same epitope as the previously described vimentin-cross-reactive epitope at position 23-26 of type 1 M protein. In Western blots of mesangial cell and myocardial proteins, mAb IC7 cross-reacted with a 43-kDa protein. Neither vimentin nor actin inhibited the binding of mAb IC7 to the cross-reactive protein, as determined by Western blot or immunofluorescence inhibition tests. These results provide evidence that type 1 M protein contains at least one autoimmune epitope shared with both human glomeruli and myocardium.

Amino Acid Sequence↗
PubMed1989

Autoimmune sequence of streptococcal M protein shared with the intermediate filament protein, vimentin.

The crossreactivity of antibodies against a renal autoimmune epitope of Streptococcus pyogenes M protein with glomerular mesangial cells was investigated. The antibodies directed against the amino acid sequence Ile-Arg-Leu-Arg of the nephritogenic type 1 M protein reacted in a fibrillar pattern with mesangial cells cultured from isolated glomeruli. In Western blots of urea-extracted mesangial proteins, the antibodies reacted with a 56-kD protein. Monoclonal and polyclonal antibodies identified the 56-kD mesangial protein as vimentin. Two synthetic peptides of human vimentin containing the sequence Arg-Leu-Arg reacted with the autoimmune antibodies raised against a streptococcal M protein peptide. These results provide evidence that the intermediate filament protein vimentin shares autoimmune epitopes with streptococcal M protein.

Amino Acid Sequence↗
PubMed1989

Vimentin-cross-reactive epitope of type 12 streptococcal M protein.

The NH2-terminal amino acid sequence of type 12 M protein was determined by automated Edman degradation of a 38-kilodalton polypeptide fragment purified from a limited pepsin digest of intact type 12 streptococci. The sequence of the first 13 amino acid residues of the polypeptide confirmed that predicted by the nucleotide sequence of the mature type 12 M protein. A chemically synthesized peptide copying the NH2-terminal 25 residues, SM12(1-25)C, evoked opsonic antibodies against type 12 streptococci as well as renal glomerular cross-reactive antibodies. The serum from one of six rabbits reacted in immunofluorescence tests with human glomeruli in a mesangial staining pattern. The cross-reactive antibodies were completely inhibited by the immunizing peptide and absorption with type 12 streptococci. Subpeptides of the 25-residue synthetic peptide were without inhibitory effect, suggesting that the cross-reactive antibodies are directed against a conformational epitope of SM12(1-25)C. Anti-SM12(1-25)C antisera reacted specifically with the intermediate filament protein vimentin extracted from mesangial cells. None of the cross-reactions of anti-SM12(1-25)C were inhibited by a synthetic peptide SM1(1-26)C of type 1 M protein, which was previously shown to share a cross-reactive epitope with vimentin. These results indicate that type 12 M protein contains at least one vimentin cross-reactive epitope that is clearly distinct from the tetrapeptide epitope shared with vimentin by type 1 M protein.

Amino Acid Sequence↗