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Biomedical subjects

T Stein

Publications and source records attributed to T Stein.

At least 55 records · Page 3Linked to original sources
PubMed1995

Medical student knowledge levels and performance in doing HIV risk assessment.

The primary purpose of the study was to develop and evaluate a training program for medical students in sexual history-taking and HIV risk assessment. Sexual-history-taking performance was evaluated in the semester subsequent to the one in which the students received the instruction. An additional purpose of the study was to determine whether students, following participation in a sexual-history training program, would take a sexual history when course instructions did not explicitly direct her/him to do so but the patient presented with HIV risk factors. A final goal was to find out whether direct participation in, versus only observation of, sexual-history interviews would improve performance. Adequate performance on measurement on knowledge and skills was defined as above 75% correct on content examinations and satisfactory performance of the sexual history. Results showed that, when course instruction directed students to take a sexual history, performance was excellent. When students were not specifically directed to take a sexual history, but the patient had an HIV risk factor, performance was not as consistent. Following participation in the training program, student attitudes about the importance of taking a sexual history were very positive. Finally, when a student conducted a sexual-history interview him/herself, compared with viewing other students taking a history, he/she showed no significant improvement in examination performance.

Clinical Competence↗
PubMed1994

Detection of 4'-phosphopantetheine at the thioester binding site for L-valine of gramicidinS synthetase 2.

Biosynthesis of gramicidinS in Bacillus brevis is catalysed by a multienzyme system consisting of two multifunctional proteins, gramicidinS synthetase 1 and 2 codified by the grsA and grsB genes, respectively. GramicidinS synthetase 2 shows a modular architecture of four amino acid-activating domains each containing a thioester binding motif LGG H/D S L/I highly conserved in its C-terminal region, as demonstrated by sequence analysis of the grsB gene [W. Schlumbohm et al. (1991) J. Biol. Chem. 266, 23135-23141]. This multienzyme was specifically labeled at the thioester binding site of L-valine with [3H]N-ethylmaleimide using a substrate protection technique. After enzymatic digestion a labeled active site peptide was isolated in pure form by multistep methodology. This fragment was identified by gas-phase sequencing as the active site peptide of the thiotemplate site for L-Val by comparison with the grsB gene sequence. By mass spectrometry in combination with amino acid analysis it was demonstrated that a 4'-phosphopantetheine carrier was attached to the active serine in this motif. Our results give evidence that multiple peripheral 4'-phosphopantetheine carriers are involved in the formation of gramicidinS in contrast to a central carrier arm as assumed in the original version of the thiotemplate mechanism. A 'Multiple Carrier Model' of nonribosomal peptide biosynthesis is proposed.

Amino Acid Isomerases↗
PubMed1994

Natural history and treatment with ursodiol of gallstones formed during rapid loss of weight in man.

Cholesterol gallstones form frequently among obese patients during rapid loss of weight. The aims of the present study were to determine the short-term natural history of these gallstones and the efficacy of ursodiol for their dissolution. Twenty-two patients whose gallstones had formed during rapid loss of weight were randomized in double-masked fashion to either ursodiol, 1200 mg/day, or placebo for nine months. Ultrasonography of the gallbladder was performed after three and nine months of treatment. All patients without disappearance of their gallstones after nine months received open-label ursodiol for an additional nine months with ultrasonography after three and nine months. Among the patients completing three months of masked treatment, disappearance of gallstones was seen in five of 11 patients who received placebo and four of seven patients who received ursodiol. Only one additional patient of six continuing placebo for nine months experienced disappearance. Neither of two patients continuing ursodiol for nine months had disappearance of gallstones. None of the five patients treated with open-label ursodiol for nine months had disappearance of gallstones. Thus, half of the gallstones that form during rapid loss of weight disappear rapidly once loss of weight ceases; ursodiol may not increase the frequency or rapidity of their disappearance.

Adult↗
PubMed1994

Evaluating multicultural approaches in HIV/AIDS educational material.

In recent years health educators have become more aware of the impact of culture on the success of health education programs. This awareness has prompted experimentation with the use of cultural elements in HIV prevention and education efforts. The literature on multicultural education offers little guidance to the health educator on how to evaluate the appropriate and effective use of culturally distinctive messages in educational materials. The authors describe common errors in the development, pedagogical approach, and design of printed HIV educational material and suggest a framework for evaluating the impact of cultural elements on HIV education programs. The guidelines help one determine how effectively language and visual images are used in a given material, as well as how clearly information is conveyed.

Acquired Immunodeficiency Syndrome↗
PubMed1993

The long goodbye.

Explore the source record for details and available documents.

Ill-Housed Persons↗
PubMed1991

An active serine is involved in covalent substrate amino acid binding at each reaction center of gramicidin S synthetase.

The condensing peptide forming multienzyme of gramicidin S synthetase (gramicidin S synthetase 2) was specifically labeled at its putative thiotemplate sites for L-valine and L-leucine by covalent incorporation of the 14C-labeled substrate amino acids. The thioester complexes of the multienzyme were digested with CNBr, Staphylococcus aureus V8 protease, and pepsin. Reaction center peptides containing the [14C]valine and [14C]leucine labels were isolated in pure form. They show a high degree of sequence similarity and contain the same consensus sequence LGGH/DXL. The labels were eliminated in the first Edman degradation step. A dehydroalanine was identified which can originate from either a cysteine or a serine. The comparison of the chemical results with the deduced amino acid sequence of the grsB gene encoding the gramicidin S synthetase 2 revealed that 4 such motifs are located within the gene structure, each of them being localized in the 3'-terminal region of one of 4 gene segments grsB1-B4. They have a size of approximately 2 kilobases and presumably code for the 4 amino acid activating domains of the synthetase. Surprisingly a serine was found at each putative substrate amino acid-binding position instead of a cysteine as postulated by the thiotemplate mechanism. Therefore the data suggest that active serine residues are involved in nonribosomal peptide syntheses of microbial peptides.

Amino Acid Isomerases↗
PubMed1990

[Conjunctival oxygen partial pressure, hemorheology and circulatory parameters in acute cerebral infarct before and following infusion of 6 percent low molecular hydroxyethyl starch].

A prospective clinical trial was performed on the effects of a three hour infusion of 500 ml 6% low-molecular-weight hydroxyethyl starch in patients with acute ischemic stroke. Hemorheology and conjunctival oxygen tension were found to be disturbed prior to treatment. After the infusion there was a marked improvement of the pertinent parameters, indicative of an increase in cerebral microcirculation and oxygen supply. Even 3 h later persistent significant effects were observed. The infusion was well tolerated. Blood pressure and cardiac index remained unchanged.

Blood Viscosity↗
PubMed1988

A staged approach to long gap esophageal atresia employing a spiral myotomy and delayed reconstruction of the esophagus: an experimental study.

In beagle dogs, the cervical esophagus was divided 5 cm cranial to the thoracic inlet employing a stapler. The distal esophageal stump was attached to the external surface of the trachea. A spiral myotomy (2 1/2 revolutions) was made in a 3-cm long segment constituting the distal end of the proximal esophageal segment. This was twisted on a bias with the muscle edges approximated by interrupted stitches to cover the denuded submucosal layer. With moderate traction, this segment could be elongated to a length of 5 cm. A subcutaneous tunnel was created in the anterior chest to accommodate the reconstructed proximal esophageal segment (under slight traction), with its distal end forming a cutaneous esophagostomy. A gastrostomy was created using a Gauderer button (Bard Interventional Products, Billerica, MA) for feeding. After 3 weeks, the proximal esophageal segment was mobilized and removed from the subcutaneous tunnel. The distal esophageal segment was freed from the trachea and 5 to 8 cm of its proximal end was excised. The proximal (myotomized) esophagus was brought down to the stump of the remaining distal esophagus and an anastomosis formed in an end-to-end fashion. Oral feeding was reestablished within 1 week. Prolonged ingestion, observed soon after operation, gradually improved. During a period of 1 to 6 months after the operation, motility of the myotomized segment was tested by barium swallow and manometry. There was neither diverticulum formation nor stenosis. Transit of contrast material in the myotomized segment was smooth and rapid. Manometry demonstrated preservation of motility in the myotomized segment of the esophagus.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1983

Hemodynamic assessment of the circulation in 200 normal hands.

The frequent use of arterial puncture, cannulation, and A-V shunting has demonstrated a greater degree of safety than could be predicted from previous anatomic and angiographic studies. Using a noninvasive technique, the status of the superficial palmar arch (SPA) and relative contributions of radial and ulnar arteries were determined in 100 volunteers with no history of vascular disease. Although there was no significant difference in the diameter of the vessels at the wrist, the flows showed statistically significant ulnar dominance, suggesting that the difference is a factor of a lower distal resistance on the ulnar side. The lower resistance across the ulnar bed probably is responsible for the clinically observed ease of sacrifice of the radial artery contribution to palmar flow. The SPA was found to be incomplete in 11.0% of the hands.

Adult↗
PubMed1983

Biosynthesis of proteokeratan sulfate in the bovine cornea. 2) Isolation of subcellular membrane fragments from bovine cornea cells with keratan sulfate synthesizing activity.

Cornea cells were isolated from bovine corneae after collagenase treatment. Subcellular fragments were fractionated by density gradient centrifugation. The density gradient run was monitored by determination of the marker enzyme activities for mitochondria, plasma membranes, lysosomes and endoplasmatic reticulum, of the enzyme activities involved in keratan sulfate synthesis and of the protein content. The fractions were further investigated by electron microscopy. Two membrane fractions with keratan sulfate-synthesizing activity (UDP-N-acetylglucosamine:keratan-N-acetylglucosaminyl-transferase, UDPgalactose:keratan galactosyltransferase and keratan sulfotransferase) were detected: a heavy fraction separated from the other organells investigated and a light fraction exhibiting the same density as plasma membranes. The activities of the three enzymes were found in the same density gradient fractions with a similar distribution pattern between the fractions, which suggests a joint localization of these 3 enzymes at the same intracellular sites.

Animals↗
PubMed1982

Structure of the linkage-region between polysaccharide chain and core protein in bovine corneal proteokeratan sulfate.

Peptidokeratan sulfate from bovine cornea was degraded by a combination of desulfation, exo-enzymic digestion and finally digestion with endo-beta-N-acetylglucosaminidase D. The same procedure was carried out both with [3H]fucose-labelled and [3H]mannose-labelled peptidokeratan sulfate. Data obtained by methylation analysis of peptidokeratan at the different degradation steps, as well as action of endo-beta-N-acetylglucosaminidase D, showed that the binding-region in proteokeratan sulfate from bovine cornea is identical with a structure found in various GlcNAc(beta 1-N)-Asn-linked mannosyl glycoproteins. The existence of a chitobiose unit between asparagine and mannose was proved by action of endo-beta-N-acetylglucosaminidase D. The existence and position of an (alpha 1 leads to 6)-linked fucosyl residue at the Asn-bound GlcNAc was demonstrated by action of alpha-fucosidase, endo-beta-N-acetylglucosaminidase D and by gel chromatography on Bio-Gel P-4. By gas chromatography/mass spectrometry studies, the existence of a 1,4,6-trisubstituted beside a 1,4-disubstituted GlcNAc in the binding-region oligosaccharide was shown. Other results reported here are according to analytical data previously published (Keller, R., Stein, T., Stuhlsatz, H.W., Greiling, H., Ohst, E., Müller, E. & Scharf, H.-D. (1981) Hoppe-Seyler's Z. Physiol. Chem. 362, 327-336).

Acetylglucosamine↗