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Biomedical subjects

R Volk

Publications and source records attributed to R Volk.

24 records · Page 2Linked to original sources
PubMed1990

Studies on the 4-carbon precursor in the biosynthesis of riboflavin. Purification and properties of L-3,4-dihydroxy-2-butanone-4-phosphate synthase.

The formation of the riboflavin precursor, 6,7-dimethyl-8-ribityllumazine, from 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione requires a phosphorylated 4-carbon intermediate which has been designated as Compound X (Neuberger, G., and Bacher, A. (1985) Biochem. Biophys. Res. Commun. 127, 175-181). The enzyme catalyzing the formation of Compound X has been purified about 600-fold from the cell extract of the flavinogenic yeast Candida guilliermondii by chromatographic procedures. The purified protein appeared homogeneous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and consisted of a single polypeptide of 24 kDa. The committed substrate of the enzyme was identified as D-ribulose 5-phosphate. The enzyme yields two products which were identified as L-3,4-dihydroxy-2-butanone 4-phosphate and formate by NMR and CD spectroscopy. Mg2+ is required for activity.

Candida↗
PubMed1990

Inactivation of HIV-1 and HIV-2 by various manufacturing procedures for human plasma proteins.

Human retroviruses causing AIDS (HIV-1, HIV-2) can occur in human plasma donations. Since HIV-contaminated plasma cannot be completely excluded by testing for anti-HIV-1 (routine plasma screening for anti-HIV-2 has not yet been established), a safeguard against AIDS in therapeutics derived from human plasma can only be achieved by introducing HIV inactivating/eliminating methods into the manufacturing process of plasma derivatives. To investigate the HIV inactivating efficiency of such methods, aliquots of infectious HIV-1 or HIV-2 concentrates were added to a protein preparation, the resulting HIV spiked preparation was then treated according to the method to be studied, and the amount of infectious HIV in this preparation was determined before and after treatment. Methods by which HIV-1 or HIV-2, respectively, were completely inactivated were ethanol fractionation according to the Cohn procedure, pepsin treatment, affinity chromatography, protein precipitation by various methods, and pasteurization (heat treatment at 60 degrees C in aqueous solution). The use of these methods for manufacturing human plasma derivatives resulted in products that were free of any infectious HIV-1 or HIV-2 and thus unable to transmit AIDS.

Blood Proteins↗
PubMed1990

Individual and family factors impacting diabetic control in the adolescent: a preliminary study.

The focus of this preliminary study is the impact of family and individual factors on diabetes control for the adolescent. Adolescents between the age of 15 and 18 years and their parents participated in this study. Questionnaires completed by subjects included FACES III, FILE, Social Support Inventory, and the Kvebaek Family Sculptures. Diabetic control was determined by measuring glycosylated hemoglobin. Subjects were asked to identify how they perceived family cohesion, family dysfunction, relationship distance, and social support. Initial analysis, utilizing bivariate correlations because of the small sample size, revealed statistically significant correlations between the adolescent's perception of family cohesion and diabetes control. Moreover, the more dysfunctional the parents perceived the family system, the worse the diabetic control of the adolescent. Adolescents with better diabetic control had fathers who perceived a greater distance between the mother-father relationship as well as a greater distance between the ideal father-patient relationship. Patients who perceived their mothers as nonsupportive experienced worse diabetic control. Yet patients who perceived they had more social support experienced better control of their diabetes. The more disengaged the family system, the worse the diabetic control for the adolescent.

Adaptation, Psychological↗
PubMed1989

An antisense transcript from the Xenopus laevis bFGF gene coding for an evolutionarily conserved 24 kd protein.

Screening of a Xenopus laevis oocyte cDNA library with a rat basic fibroblast growth factor (bFGF) cDNA led to the isolation of a 1.35 kb sequence containing exon III of the bFGF gene. Reverse complementary listing of this sequence revealed a polyadenylated transcript with an open reading frame coding for an unknown protein of mol. wt 24,292 daltons. The coding part of bFGF exon III is located in this putative mRNA in opposite direction within the 3' untranslated region. By hybridization studies on transcription orientation with single-stranded probes it could be proven that this transcript actually represents an antisense transcript to part of the Xenopus bFGF gene. Sequence organization on corresponding genomic fragments revealed that it is processed from a larger precursor by splicing mechanisms. Sequence comparison with elongated transcripts from the bFGF gene in human hepatoma has shown that the gene coding for the antisense mRNA is evolutionarily conserved.

Amino Acid Sequence↗