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Biomedical subjects

G Winkler

Publications and source records attributed to G Winkler.

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

Newly synthesized dengue-2 virus nonstructural protein NS1 is a soluble protein but becomes partially hydrophobic and membrane-associated after dimerization.

In a previous paper (G. Winkler, V. B. Randolph, G. R. Cleaves, T. E. Ryan, and V. Stollar, 1988, Virology 162, 187-196) we showed that the newly synthesized dengue-2 virus nonstructural protein, NS1, exists briefly as a monomer and then undergoes dimerization. We demonstrate here that the dimerization of NS1 is associated with a change in hydrophobicity and sedimentability of this protein. Newly synthesized monomeric NS1 is a hydrophilic and water-soluble protein which cannot be pelleted at 75,000 g. After dimerization, however, NS1 showed increased hydrophobicity in a Triton X-114 phase partitioning system and was completely pelletable at 75,000 g; these findings are consistent with NS1 becoming membrane-associated. In experiments in which infected cells were treated with tunicamycin it was shown that the glycosylation of NS1 was not required for either the dimerization or the membrane association.

Animals↗
PubMed1989

[10 years' experience with heart surgery in Jehovah's witnesses].

UNLABELLED: As a result of their interpretation of the Bible, members of Jehovah's Witnesses do not accept blood transfusions under any circumstances. Consequently, they present moral and ethical problems to surgeons and anesthetists, especially in cardiac surgery. PATIENTS and METHODS. From November 1978 to November 1988, 66 members Jehovah's Witnesses were scheduled for cardiac surgery; 57 patients were operated upon (mean age 33.3 years, 14 days to 70.4 years; mean body weight 51 kg, 0.7 to 95.5 kg); 21 were younger than 14 years. Patients with hematocrit (Hct) less than 35%, expected high intra- and postoperative blood loss, compromised left ventricular function, ST-segment alterations, critical aortic stenosis, severe unstable angina pectoris, complex heart defects, especially in children, extreme body weight, severe diabetes, renal insufficiency, coagulopathies, severe pulmonary disease, and heavy smokers were excluded from operation. Whereas in nonbypass patients no special blood-saving techniques were used, in bypass patients a modified version of isovolemic hemodilution, with a hypothermic, bloodless priming technique of extracorporeal circulation (ECC) was performed after induction of anesthesia. At the end of the ECC all blood collected in the pericardial and pleural cavities was returned to the oxygenator and the entire content of the extracorporeal circuit was infused into the patient through the aortic cannula. All patients receiving ECC were ventilated for 24 h postoperatively and received dopamine (2-5 micrograms/kg) and antibiotics routinely. RESULTS: Due to the above mentioned contraindications, 9 patients were not accepted for surgery, 10 were operated upon without cardiopulmonary bypass or blood-saving techniques. In 47 patients open heart surgery with ECC and moderate or deep hypothermia was performed. In the adult patients (n = 36) Hct values decreased from 44.4% (35-70%) preoperatively to 32.1% (21-46%) after hemodilution, reached their lowest levels during cardiopulmonary bypass at 17.9% (9.9-43%), and increased to 33.7% (22%-43%) at the end of the operation. Hct averaged 28.2% (20%-39%) on the 3rd and 33.2% (23%-46%) on the 12th postoperative day. In children (n = 11) Hct decreased from 47.2% (36.9%-70%) to 33.6% (27.2%-49.1%) after hemodilution, during bypass to 16.1% (10.5%-25.5%) and increased to 32.1% (24.4%-37.4%) at the end of the operation. On the 3rd postoperative day Hct was 25% (21.4%-39%) and increased to 29.4% (25.1%-40%) on the 12th postoperative day. No statistical differences in Hct values were found between both groups. (ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1988

Chemical composition of the yeast ascospore wall. The second outer layer consists of chitosan.

In a preceding paper (Briza, P., Winkler, G., Kalchhauser, H., and Breitenbach, M. (1986) J. Biol. Chem. 261, 4288-4294), we reported the presence of dityrosine in the outer layers of yeast ascospore walls. Both outer layers seen in electron micrographs of yeast ascospore walls are sporulation-specific. Here we show that the second of these two outer layers consists of chitosan. In intact spores, it is shielded from staining with primulin by the outermost layer. However, in purified spore walls, the second layer is brightly stained by primulin, and hydrolysates of such preparations contain about 10% glucosamine relative to spore wall dry weight. The spore wall material staining with primulin is resistant to chitinase, but readily degraded by treatment with HNO2. Acetylation prior to HNO2 treatment completely prevents its degradation. A partial acid hydrolysate of spore walls contains predominantly soluble poly-beta-(1,4)-glucosamine as determined by 13C NMR spectroscopy. By these criteria, the glucosamine polymer of yeast ascospore walls is chitosan. As spore walls treated with alkali lack the inner layers but contain chitosan and as chitosan is not exposed at the surface of the spore, we conclude that it is localized in the second outer layer of the spore wall.

Chitin↗
PubMed1988

Evidence that the mature form of the flavivirus nonstructural protein NS1 is a dimer.

Evidence is presented which indicates that the dengue-2 virus nonstructural protein NS1 (soluble complement fixing antigen) exists in infected BHK and mosquito cell cultures as part of a stable oligomer. Identification of the dissociation products of the isolated oligomer and comparison of the number of N-linked glycans in native and denatured NS1 is consistent with the idea that the high-molecular-weight form of NS1 is a homodimer. By analyzing lysates of BHK cells infected with St. Louis encephalitis virus or Powassan virus and proteins from dengue-2 virus-infected mouse brain we have demonstrated that the appearance of the high-molecular-weight form of NS1 is a general feature of flavivirus infection. It is formed between 20 and 40 min after NS1 is synthesized and before the protein passes the Golgi apparatus. Both soluble and pelletable extracellular NS1 are also found as the high-molecular-weight form.

Capsid↗
PubMed1988

Intraoperative heart rate reduction--alinidine versus metoprolol.

In a double-blind randomized protocol the effectiveness of the specific bradycardic agent alinidine (0.6 mg.kg-1 i.v.) was compared to that of the betablocker metoprolol (0.035 mg.kg-1 i.v.). Twenty-four coronary artery disease patients undergoing a bypass procedure with an intraoperative heart rate increase of more than 20% were included. Patients with a concomitant intraoperative mean arterial pressure increase of more than 30% or with an intraoperative wedge pressure higher than 15 mmHg (2.0 kPa) were excluded. After application of alinidine and metoprolol, heart rate decreased significantly (P less than 0.01) in the alinidine group from 88 +/- 19 beats per min to 72 +/- 13 and in the metoprolol group from 82 +/- 16 to 72 +/- 12. Baseline values were not obtained. Compared to the hemodynamic changes in the metoprolol group, the alterations of pulmonary capillary wedge pressure (PCWP) (P less than 0.05), stroke volume index (SVI) (P less than 0.05), left ventricular stroke work index (LVSWI) (P less than 0.01) and right ventricular stroke work index (RVSWI) (P less than 0.05) in the alinidine group were statistically significantly different. PCWP remained unchanged after alinidine and increased in the metoprolol group (1.4 +/- 0.4 to 1.6 +/- 0.4 kPa). In the alinidine group LVSWI (43.1 +/- 15 to 49.2 +/- 18 g-m.m-2), RVSWI (5.1 +/- 4 to 6.6 +/- 3 g-m.m-2) and SVI (37.2 +/- 12.2 to 42.5 +/- 12.8 ml.m-2) increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Studies on the glycosylation of flavivirus E proteins and the role of carbohydrate in antigenic structure.

The glycosylation pattern of several flavivirus E proteins as well as the role of carbohydrate in biological functions and the antigenic structure of tick-borne encephalitis (TBE) virus were investigated by the use of specific endoglycosidases. Endoglycosidase F digestion revealed the presence of a single asparagine-linked oligosaccharide side chain in TBE virus (Western and Far Eastern subtype), Louping III virus, Murray Valley encephalitis virus, and Rocio virus. Consistent with published sequence data, the E protein of West Nile virus apparently is not glycosylated at all. Evidence derived from digestion experiments using endoglycosidase H indicates that the tick-borne viruses contain high-mannose type N-linked oligosaccharide side chains, whereas that of the mosquito-borne Murray Valley encephalitis virus and Rocio virus is endoglycosidase H resistant. Complete deglycosylation of TBE virus by endoglycosidase F did not impair infectivity and HA activity. Carbohydrate does not seem to play a major role in the antigenic structure of the TBE virus glycoprotein since the reactivity of the native virus and the deglycosylated virus was identical when analyzed with monoclonal as well as polyclonal immune sera.

Antigens, Viral↗
PubMed1987

Characterization of a disulphide bridge-stabilized antigenic domain of tick-borne encephalitis virus structural glycoprotein.

Proteolytic digestion of purified whole tick-borne encephalitis virus or its isolated envelope glycoprotein (E) in the form of rosettes yields an Mr 9000 fragment that is resistant to further digestion and carries polyclonal and monoclonal antibody-defined antigenic determinants. In a denaturation/renaturation experiment it was demonstrated that the antigenic reactivity of this domain, which was lost upon reduction and carboxymethylation, could be regained if the reducing agent was dialysed out before carboxymethylation. By the use of [35S]cysteine-labelled E protein and amino acid analysis it was confirmed that the reacquisition of antigenic reactivity in the renaturation experiment was associated with the reformation of disulphide bridges, which apparently confer structural stability to this part of the molecule. By the experiments performed we have identified an independently folding antigenically active domain of the E protein that is stabilized by disulphide bridges and has a strong tendency for renaturation.

Animals↗
PubMed1987

Pain threshold and subjectively perceived epidural sensory blockade with 0.5% bupivacaine.

We investigated the relationship between patients' pain thresholds and the quality of the subjectively perceived epidural sensory blockade (SPESB). The pain thresholds of 50 patients were evaluated with a modification of the submaximum effort tourniquet technique. There was a significant correlation between pain threshold and the number of subjectively perceived anesthetic and analgesic segments, the likelihood of developing an extensive SPESB being greater in patients with higher pain thresholds. Forty-one percent of patients with pain scores of less than 10 mm on the visual analogue scale, but no patient with a pain score of 20 mm or more, developed anesthesia in ten or more spinal segments.

Adult↗
PubMed1987

Growth hormone reserve in diabetes mellitus.

The magnitude of hGH reserve was investigated in young (16-40 years old) diabetic patients. Forty patients were examined with the arginine infusion test, twenty three with a sensitized version of the L-Dopa test. The patients were divided into four groups based on the type of their illness (IDDM or NIDDY) and the clinical stage of IDDM. It was concluded that the hGH reserve of the various diabetic groups differs from the hGH reserve of healthy persons as well as from one another. Taking into consideration the possible causes of these differences, it is suggested that the hGH reserve depends primarily on the metabolic condition of the patients, while the type of diabetes (IDDM or NIDDY) and the insulin therapy used may also be important contributing factors. Achievement of a good metabolic control within the same type of diabetes leads to the normalization of the previously pathologic hGH reserve.

Adolescent↗
PubMed1986

Dityrosine is a prominent component of the yeast ascospore wall. A proof of its structure.

The yeast ascospore wall consists of four morphologically distinct layers. The hydrophobic surface layers are biogenically derived from the prospore wall and appear dark after OsO4 staining. They seem to be responsible for the stability of the spores against attack by lytic enzymes. By amino acid analysis of acid hydrolysates of ascospore walls, two new peaks were detected, which were shown to be the racemic and meso form, respectively, of dityrosine. The identity of this hitherto unknown component of the yeast ascospore wall with standard dityrosine was proven by 1H NMR and by mass spectrometry. A 13C NMR spectroscopic investigation of the structure of dityrosine confirmed that, in natural dityrosine, the biphenyl linkage is located ortho, ortho to the hydroxyl groups. Following digestion of the inner layers of isolated ascospore walls it was shown that dityrosine is very probably located only in the surface layers. The same conclusion was reached independently by an investigation of spores of a strain homozygous for the mutation gcn1, which lack the outermost layers of the spore wall and were practically devoid of dityrosine. In sporulating yeast, L-tyrosine was readily incorporated into the dityrosine of the ascospore wall. Control experiments involving vegetative a/alpha cells and nonsporulating alpha/alpha cells under sporulation conditions showed that dityrosine is indeed sporulation-specific.

Amino Acids↗
PubMed1986

A personal computer program using a 4-component logit for the evaluation of ELISA calibration curves with unknown asymptotic values.

A BASIC program is described for the calculation of ELISA calibration curves using a 4-component logit for the linearisation of the sigmoidal shape. The difficulty of estimating the four logit parameters without knowledge of upper and lower asymptotic values is overcome by statistical analysis of the experimental data. The program is run on an IBM-PC and the curves are plotted by a HP7475A plotter.

Biometry↗
PubMed1986

[Description of neurocutaneous melanoblastosis].

Description of a rare case of neurocutaneous Melanoblastosis. In a 25 year-old man there was an extraordinary massiveness of the tumor in the field of the cerebrospinal soft membranes. Tumor cells, relevant for diagnosis, from lumbal and suboccipital liquor could be shown. Nomenclature and pathogenesis of the disease are discussed.

Adult↗
PubMed1985

Separation of flavivirus membrane and capsid proteins by multistep high-performance liquid chromatography optimized by immunological monitoring.

Complete separation of the three structural proteins, E, C and M, of an enveloped virus (tick-borne encephalitis virus) was achieved by means of a two-step high-performance liquid chromatography (HPLC) technique in less than 1 h. The hydrophobically associated membrane proteins E and M were successfully separated by high-performance gel permeation chromatography (TSK-3000 SW column) in the presence of sodium dodecyl sulphate (SDS), whereas the separation of M and C as well as desalting and removal of SDS was achieved by subsequent reversed-phase chromatography on a C3 column. With regard to further characterization by peptide mapping, analysis of the amino acid composition and aminoterminal sequencing, the second step was performed with volatile buffer systems. Quality control of the separation was achieved by a combination of HPLC with a highly sensitive dot immunoassay by the use of polyclonal as well as monoclonal antibodies. This method proved extremely sensitive and revealed strong tailing effects and cross-contaminations of peaks well-separated in reversed-phase chromatography, which were neither apparent in the absorbance curve at 214 nm nor in the analysis by SDS-polyacrylamide gel electrophoresis. By visualization of the peak-tailing effect, the chromatographic conditions could be modified in order to achieve an optimum separation of proteins.

Antibodies, Monoclonal↗