Biomedical subjects
W Kos
Publications and source records attributed to W Kos.
Expression of genes encoding peroxisomal proteins in Saccharomyces cerevisiae is regulated by different circuits of transcriptional control.
In Saccharomyces cerevisiae induction of the FOX3 gene, encoding peroxisomal 3-oxoacyl-CoA thiolase, by growth on oleate as sole carbon source, is exerted via the cis-acting DNA element designated oleate response element (ORE) (Einerhand et al. (1991) Eur. J. Biochem. 200, 113-122). The transcription factor(s) binding to this upstream activation site (UAS) are still unknown, however. Induction of another peroxisomal enzyme, citrate synthase (CIT2) is dependent on the products of two genes called RTG1 and RTG2 (Liao and Butow (1993) Cell 72, 61-71). In the present study we have investigated whether RTG1 controls other genes coding for peroxisomal proteins, and whether such control takes place via the ORE. A number of genes coding for a variety of peroxisomal proteins such as: thiolase and catalase (peroxisomal matrix proteins), PAS3p (a peroxisomal membrane protein) and PAS10p (a protein involved in the import of peroxisomal proteins) were studied in their response to RTG1. Although the RTG1 and 2 products proved to be required for the increase in number and volume of peroxisomes upon induction by oleate, the single promoter output of the chosen set of genes remained practically unchanged in a rtg1 mutant strain. In addition gel retardation experiments indicated that RTG1 does not bind to the ORE. The behavior of genes coding for the various proteins also varied during repression, derepression and induction, indicating that probably a number of proteins are involved in tuning the output of each gene to cellular demand.
The upstream region of the FOX3 gene encoding peroxisomal 3-oxoacyl-coenzyme A thiolase in Saccharomyces cerevisiae contains ABF1- and replication protein A-binding sites that participate in its regulation by glucose repression.
Expression of the FOX3 gene, which encodes yeast peroxisomal 3-oxoacyl-coenzyme A thiolase, can be induced by oleate and repressed by glucose. Previously, we have shown that induction was mediated by an oleate response element. Just upstream of this element a negatively acting control region that mediated glucose repression was found. In order to study this negative control region, we carried out DNA-binding assays and analyzed phenotypes of mutations in this region and in the trans-acting factor CAR80, which is identical to UME6. DNA-binding assays showed that two multifunctional yeast proteins, ABF1 and RP-A, interacted with the negative control element independently of the transcriptional activity of the FOX3 gene. ABF1 and RP-A, the latter being identical to BUF, were able to bind to DNA independently of one another but also simultaneously. The phenotypes of mutations in either DNA-binding sites of ABF1, RP-A, or both, which affected the DNA binding of these factors in vitro, indicated that these sites and the proteins that interact with them participate in glucose repression. The involvement of the RP-A site in glucose repression was further supported by our observation that the CAR80 gene product, which is required for repression mediated by the RP-A site, was essential for maintenance of glucose repression. In addition to the RP-A site in the FOX3 promoter, similar sequences were observed in other genes involved in peroxisomal function. RP-A proved to bind to all of these sequences, albeit with various affinities. From these results it is concluded that the ABF1 and RP-A sites are being required in concert to mediate glucose repression of the FOX3 gene. In addition, coordinated regulation of expression of genes involved in peroxisomal function in response to glucose is mediated by proteins associated with the RP-A site, probably RP-A and CAR80.
Evaluation of the antibacterial effects of intracanal Nd:YAG laser irradiation.
Fifty canals of extracted single-rooted teeth were prepared to a size 50 master apical file, sterilized in ethylene oxide, and inoculated with a known quantity of Bacillus stearothermophilus spores. Five groups of 10 canals each were used. The control group received no treatment. The four treatment groups were exposed to pulsed Nd:YAG laser radiation or 0.5% NaOCl alone and in combination. The root canals were flushed with sterile distilled water to recover spores, and serial dilutions were incubated on blood agar and the number of colony-forming units recovered was determined. Analysis of the data indicated a 2-log reduction in colony-forming units among the four treatment groups as compared with the controls; however, no significant differences were observed among the treatment groups. In none of the treatment groups were the root canals sterilized.
[Immediate and late results following endarterectomy of the carotid bifurcation].
In a retrospective study we analysed two groups each consisting of 100 consecutive patients of similar age and sex distribution who underwent surgery for carotid disease with an intervening period of 5 years (group A 1980/82, group B 1986/87) between the collectives. Against a background of changing indications, tactics and techniques the aim of the study was to detect any differences between the two groups. Group A had a higher proportion of coronary and peripheral vascular disease. The states of cerebral ischemia I, II and III were distributed equally, but state IV was seen more frequently in group B (p less than 0.05). The number of shunt/without shunt operations in group A was 97/2, in group B 10/84 (p less than 0.005). The external carotid artery was deobliterated in 58/81 cases group A versus group B (p less than 0.005). We closed the artery by direct suture in 8/31 (p less than 0.005), by autologous venous patch in 53/26 (p less than 0.005) and by Dacron patches in 39/41 patients. In group A the operative mortality was zero and in group B 1 patient died; one patient in group B developed sudden occlusion (with TIA) postoperatively. Transient intra-/postoperative neurological deficits occurred in 1/2, permanent in 4/2 patients (n.s.). 54/25 patients have died up to 31/08/91. Coronary heart disease was the main cause of late complications and deaths in group A (p less than 0.025). Statistically, there was no dependence of neurological deficits on group, sex, age or intraoperative management. Only patients with preoperative PRINDS hat a higher postoperative neurological deficit rate than the others.
Computerised tomography of keratoconus.
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Direct "metrizamide" myelocystography in syringohydromyelia. Report of 3 cases.
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[Blunt abdominal injuries in children].
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[Our experiences with the LeVeen peritoneal-venous shunt].
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