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Biomedical subjects

A Schuster

Publications and source records attributed to A Schuster.

103 records · Page 6Linked to original sources
PubMed1983

Ribonucleic Acid and Protein Metabolism in Pea Epicotyls : III. Response to Auxin in Aged Tissue.

Applications of auxin to the tips of intact aged pea Pisum sativum L. var Alaska epicotyls resulted in an increase in the content of polyribosomes and poly(A) and in the capacity of isolated polysomes to support protein synthesis in vitro. Few changes were seen in the two-dimensional gel patterns of silver-stained proteins accumulated (or degraded) in vivo even after 15 hours of auxin treatment. In contrast, substantial changes were evident in the two-dimensional gel fluorographs of polypeptides generated in vitro by total RNA and by polysomal RNA from tissue treated with auxin for only 6 hours. Of the 200 spots resolved by fluorography, total RNA from auxin-treated tissue generated 33 spots with increased intensity and 10 with decreased intensity; polysomal RNA yielded 33 spots which increased and only three that decreased. In general, the polypeptides that increased in intensity were higher molecular weight and those that decreased were lower molecular weight. These changes occurred prior to growth and might be prerequisite for the auxin-induced slow growth response seen in this aged tissue.Comparisons were made between the changes in RNA and protein metabolism occuring during aging and after wounding and auxin treatment of aged tissue. Aging causes a decline in poly(A), polysomes, and protein synthesizing capacity, whereas wounding and auxin treatment cause increases. Wounding appears to act primarily at the level of translation, whereas auxin has a greater effect on transcription. It is argued that the use of excised tissue to study auxin effects on RNA and protein metabolism should be avoided.

Journal Article↗
PubMed1981

Intercellular communication in plants: Evidence for a rapidly generated, bidirectionally transmitted wound signal.

Wounding (whether by excision, abrasion, or puncture) elicited rapid, massive, and enduring formation of polysomes in aged pea stems and other mature tissues. The response depended on temperature and severity of wounding but not on water uptake, and it occurred in tissues adjacent to, distant from, above, and below the site of injury. The kinetics of polysome formation were similar in tissues adjacent to or up to 150 mm distant from the point of injury. The wound-induced increases in protein-synthesizing capacity of the polysomes both in vivo and in vitro were much greater than the increases in rRNA and poly(A)(+)RNA. The results indicate that wounding evokes the almost immediate production of a wound signal that travels rapidly both acropetally and basipetally to stimulate the recruitment of preexisting ribosomes onto primarily preexisting mRNA, thence forming polysomes with greatly enhanced protein-synthesizing capacity.

Journal Article↗
PubMedDate not supplied

High-performance liquid chromatographic-ultraviolet assay for the simultaneous quantitation of BMS-181101 and its putative hydroxy metabolites in rat and monkey plasma.

A specific, accurate, precise, and reproducible High-performance liquid chromatographic-Ultraviolet (HPLC-UV) method was developed for the simultaneous quantitation of BMS-181101 (I), a new antidepressant, and its putative metabolites, 6'-hydroxy (II) and 7'-hydroxy (III) of BMS-181101 in rat and monkey plasma. The assay procedure involved solid-phase extraction of the three analytes and the internal standard (IS; BMY-42568) on 1 mL Bond Elut CN cartridge using an automated solid phase extraction controller (ASPEC) system. The final elution of the analytes was performed using 0.25% triethylamine in methanol. The eluate mixture was evaporated to dryness, the residue was reconstituted in the mobile phase and injected onto a Zorbax Phenyl column (4.6 x 250 mm; 5 microns) at a flow-rate of 1.2 mL/min. The mobile phase consisted of 20% acetonitrile, 10% methanol, 69% water and 1% 1.0 M ammonium phosphate and 1.0 M tetramethylammonium hydroxide mixture adjusted to pH 3 by phosphoric acid. An ultraviolet absorbance detector set at 287 nm was used to detect the analytes. The nominal retention times were 5, 8, 15, and 18 min for II, III, I, and IS, respectively. The standard curves for the three analytes were linear in the concentration range of 50-1000 ng/mL. The lower limit of quantitation was 50 ng/mL for each analyte. The analyses of quality control (QC) samples indicated that the nominal values could be predicted with an accuracy of (+/-) 10.5% for all three analytes in rat and monkey plasma. The precision values of the QC samples for all three analytes were within 12.7% RSD for rat and monkey plasma. All three analytes and the IS were stable in the autosampler for at least 38 h; freeze/thaw stability of the 3 analytes was established for three cycles. Stability of BMS-181101 was established for one month at -20 degrees C. The application of the assay to a pharmacokinetic study in monkey is described.

Animals↗
PubMedDate not supplied

Antiemetic efficacy of smoked marijuana: subjective and behavioral effects on nausea induced by syrup of ipecac.

Although the public debate about the legalization of marijuana has continued for as long as 25 years, few controlled studies have been conducted to assess its potential medical benefits. The present study examined the antiemetic effect of smoked marijuana cigarettes (8.4 and 16.9 mg Delta(9)-tetrahydrocannabinol [THC]) compared to a highly potent antiemetic drug, ondansetron (8 mg) in 13 healthy volunteers. Nausea and emesis were induced by syrup of ipecac. Marijuana significantly reduced ratings of "queasiness" and slightly reduced the incidence of vomiting compared to placebo. Ondansetron completely eliminated the emetic effects of ipecac. These findings support and extend previous results, indicating that smoked marijuana reduces feelings of nausea and also reduces emesis in this model. However, its effects are very modest relative to ondansetron, and the psychoactive effects of marijuana are likely to limit its clinical usefulness in the general population.

Adolescent↗
PubMedDate not supplied

Transacromial approach to obtain fusion of unstable os acromiale.

The purpose of this study was to identify possible causes for the low union rate for surgically stabilized os acromiale. Between February 1990 and November 1995, fusion of an os acromiale was attempted in 15 shoulders in 12 patients at our institution. All patients were men. The mean age was 54 years (range 37 to 63 years). All shoulders had an os mesoacromiale considered too large for simple resection. An associated lesion of the rotator cuff ranging from partial-to full-thickness tear was present in all patients. Eleven had an unfused acromial epiphysis in both shoulders. Two different surgical approaches were used. Seven shoulders were approached through an anterior deltoid-off approach, thus potentially devascularizing the os acromiale. Eight shoulders were approached transacromially, preserving the deltoid origin and hence the terminal branches of the thoracoacromial artery. The technique of internal fixation (tension band wiring) was the same for both groups. The mean follow-up was 44 months (range 13 to 72 months). Union, as demonstrated by axial radiographic views, occurred in 3 out of 7 cases with a devascularized os acromiale and in 7 out of 8 shoulders with a perfused os acromiale (P = .017), respectively. Patients with a united os acromiale had a significantly better functional outcome as measured by the Constant score (P = .0169). In conclusion, aiming at a stable fusion of a sizable and hypermobile os acromiale is probably desirable because it enhances the overall functional result. Obtaining consolidation was possible when the vascularity of the acromial epiphysis was respected.

Acromion↗
PubMedDate not supplied

[Combined hypophyseal function test in children with homozygous beta-thalassemia].

Nowadays, endocrine problems like retarded sexual maturation and growth deficiency, lead to substantial suffering in patients with beta-thalassemia major. The aim of the present study is the differentiation between a possible insufficiency of the pituitary gland and dependent target organs, respectively. 12 patients (age 1.9-18.10 years) were examined by means of a combined pituitary function test. The corticotropic axis turned out to be normal as shown by a regular stimulation of cortisol in all patients tested. The thyrotropic function was unaffected in all children: elevated levels of TSH pointed to primary hypothyroidism. Pubertal values of LH and FSH were found in only 3 out of 7 patients at pubertal age. In 10 out of 12 children, stimulation led to a rise in STH levels above 10 ng/ml. On the whole, there was no evidence for pituitary insufficiency in beta-thalassemia major.

Adolescent↗