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Biomedical subjects

G Thomas

Publications and source records attributed to G Thomas.

At least 775 records · Page 43Linked to original sources
PubMed1982

Reduction of carbohydrate-induced hypertriglyceridemia in (fa,fa) "Zucker" rats by the alpha-glucosidase inhibitor acarbose (BAY g 5421).

Inhibition of carbohydrate digestion by the alpha-glucosidase inhibitor acarbose (BAY g 5421)reduces carbohydrate-induced postprandial blood glucose increase and insulin secretion. As a consequence, in feeding experiments sucrose-induced hyperinsulinemia and hypertriglyceridemia in genetically obese (fa,fa) "Zucker" rats were dose-dependently reduced by addition of acarbose to the diet (15-80 mg/100 g feed). The body weight gain was dose-dependently reduced. In short-term experiments with a fat-free diet acarbose not only prevented serum triglyceride and free fatty acid increase in spite of lowered insulin concentrations but also decreased their concentrations below the values obtained on standard feed. Under these conditions there were no significant effects on body weight. Hypertriglyceridemia induced by i.v. injection of the lipoprotein lipase inhibitor Triton WR 1339 was reduced without affecting body weight in "Zucker" rats after 3 days on a fat-free diet supplemented with acarbose. The triglyceride increase was even lower than in animals kept on standard feed. The data demonstrate that acarbose reduces sucrose-induced hypertriglyceridemia in (fa,fa) "Zucker" rats by diminishing VLDL production and/or secretion rather than by increasing VLDL removal from the blood.

Acarbose↗
PubMed1982

The effect of serum, EGF, PGF2 alpha and insulin on S6 phosphorylation and the initiation of protein and DNA synthesis.

To test the connection between S6 phosphorylation and the activation of protein and DNA synthesis, we compared the effects of serum, epidermal growth factor (EGF), prostaglandin F2 alpha (PGF2 alpha) and insulin (which is not mitogenic in these cells). Increasing concentrations of serum or EGF produced roughly parallel effects on all three processes, though the maximum response elicited by EGF (10(-9) M) was only a portion of that caused by saturating levels of serum (7.5% to 10%). PGF2 alpha (8.5 x 10(-7) M) alone acted similarly to EGF (10(-9) M) and with EGF produced a synergistic effect on all three processes. Insulin (10(-9) M) alone stimulated both S6 phosphorylation and protein synthesis to approximately the same level as EGF or PGF2 alpha, but had no effect on initiation of DNA synthesis. Thus neither stimulation of S6 phosphorylation nor activation of protein synthesis is sufficient for initiation of DNA synthesis. The requirement for S6 phosphorylation could not be dissociated from the activation of protein synthesis. Ribosomes containing the most highly phosphorylated forms of S6 appear to have a selective advantage in entering polysomes.

Animals↗
PubMed1982

Increased phosphorylation of ribosomal protein S6 during meiotic maturation of Xenopus oocytes.

A single ribosomal protein (Mr, 32,000) becomes phosphorylated during progesterone-induced in vitro maturation of Xenopus laevis oocytes. The protein is identified as 40S ribosomal protein S6. Phosphorylation of S6 is monitored by incorporation of 32Pi and by two-dimensional polyacrylamide gel electrophoresis. S6 is minimally phosphorylated in unstimulated oocytes. After progesterone treatment, phosphorylation of S6 precedes germinal vesicle breakdown (GVBD) and is maximal at the time when 50% of the oocytes have undergone GVBD. S6, when maximally phosphorylated, exists in derivatives that correspond to the most highly phosphorylated forms observed in other systems, and the increase in S6 phosphorylation occurs at approximately the same time as the increase in the overall protein synthesis rate reported to occur during oocyte maturation. S6 is also maximally phosphorylated in unfertilized eggs following maturation in vivo. Injection of a partially purified preparation of maturation-promoting factor into immature oocytes induces immediate phosphorylation of S6 and rapidly increases the rate of protein synthesis. Moreover, incubation of ribosomes with this factor and radiolabeled ATP results in labeling of S6. These findings suggest that S6 phosphorylation may be important in the control of protein synthesis during maturation and may also play a role in the mechanism of action of maturation-promoting factor.

Animals↗
PubMed1982

Patient acceptance and effectiveness of a balanced lavage solution (Golytely) versus the standard preparation for colonoscopy.

An oral electrolyte solution containing 125 mM/L sodium, 10 mM/L potassium, 80 mM/L sulfate, 20 mM/L bicarbonate, and 80 mM/L of polyethylene glycol, and associated with little water or electrolyte absorption from the gut was recently described in this journal. To determine the efficacy of this solution (Golytely) for colonoscopy, 20 consecutive patients were randomized to either a standard colonoscopy prep or Golytely. Both preps resulted in a feces-free colon, allowing colonoscopy to the cecum in most cases. Although Golytely produced mild cramps (3 of 12) and transient fullness (6 of 12 vs. 0 of 8 with standard prep, p less than 0.02), 11 of 12 were willing to repeat Golytely vs. 3 of 8 with the standard prep (p less than 0.02). It is concluded that Golytely is an effective prep for colonoscopy and well tolerated by patients. It is especially useful for those requiring repeated examinations because of patient acceptance and efficacy.

Adult↗
PubMed1982

Gas-liquid chromatographic-thermal energy analyzer determination of N-nitrosodimethylamine in beer: collaborative study.

The GLC/TEA method for N-nitrosodimethylamine (NDMA) in beer was studied collaboratively by 13 laboratories from 7 countries. Collaborators were asked to analyze a total of 10 randomly labeled samples of beer consisting of the following duplicates: a naturally contaminated commercial beer; a beer extremely low (ca 0.1 ppb) in NDMA; and the low NDMA beer spiked with 0.5, 1.9, and 5.0 ppb NDMA. The pooled repeatability and reproducibility coefficients of variation (CV) for all samples were 17% and 27%, respectively. However, when data from 2 laboratories (outliers) were omitted, the corresponding CV values improved considerably (11% and 15%, respectively). Variance analysis showed the presence of a significant laboratory-sample interaction when all data were used for analysis, but this interaction disappeared when data from the 2 outlying laboratories were excluded. The pooled percent recovery of the overall method (omitting outliers) was 101.4 +/- 3.5. All the laboratories detected NDMA in the low NDMA beer. The method was adopted official first action.

Beer↗
PubMed1981

[The bacteria stop system of Meierhans-Weber as room air technical alternative to laminar-air-flow and its air hygienic effectiveness].

Statistics of wound infections demonstrate the linear dependence between postoperative wound infection and the quantity of bacteria in the air of operating theatres. In the most extensive examination series we have made as yet with a special work group of DGOT the quantity of bacteria in the air of non air-conditioned operating theatres and such fitted out with different aircleaning systems was determined. Non air-conditioned operating theatres proved so extremely infected that the risk of wound infection cannot be borne any more in the future. Also air-conditioned systems according to DIN 1946/4 with an average of 190 bacteria/m3 are not sufficiently secure for bone and joint surgery. In Switzerland for such operations a value of 10/m3 at the most is admissible. Such equivalents have been attained only with LAF until today. After extensive air tests the so-called "Keimstop"-system by Meierhans and Weber is to be considered the sole system suitable to supplement air conditioning DIN 1946/4. This combination yields the same effect as the expensive LAF systems.

Air Conditioning↗
PubMed1981

Photocrosslinking of thiolated aminoacyl-tRNA to ribosomal RNA and proteins.

tRNA has been converted to a form that can be photoactivated by chemical modification of some of the exposed cytidine residues to thio-4-uridine A certain percentage of the modified molecules can be charged and bound to the ribosome; thiolated fMet-tRNAfMet is bound to the P-site as shown by puromycin reactivity. Near the UV irradiation produces covalent crosslinks between total thiolated AA-tRNA or fMet-tRNAfMet and the ribosome. AA-tRNA becomes crosslinked to both 30S and 50S subunits but fMet-tRNAfMet to 50S subunits alone. In each case, crosslinking of tRNA was found to be not only to ribosomal proteins, but also to rRNA. The covalent complexes appear sufficiently stable to allow identification of the proteins or rRNA sequences involved.

Escherichia coli↗
PubMed1981

Transcriptional and translational control of cytoplasmic proteins after serum stimulation of quiescent Swiss 3T3 cells.

The synthesis of cytoplasmic proteins from quiescent and serum-stimulated Swiss 3T3 cells was compared by two-dimensional polyacrylamide gel electrophoresis. Four new proteins of Mrs 26,000, 28,000, 45,000, and 47,000 designated N26, N28, N45, and N47, which were not detectable in quiescent cells, appeared 60 min after addition of serum. During the same period, the amount of [35S]methionine incorporated into 10 proteins present in quiescent cells, ranging in Mr from 23,000 to 98,000 and designated Q23-98, increased up to 6-fold, whereas the amount incorporated into three other proteins decreased by a factor of approximately 2. Of the new proteins, N26 was no longer detectable, and the amount of [35S]methionine incorporated into N47 was significantly reduced by 150 min. During this same time, a fifth new protein, N56, appeared, and there was a large increase in the amount of radioactivity incorporated into another protein, Q121. The increases in nine of the proteins were either strongly or completely inhibited by actinomycin D, arguing that the expression of these proteins was under transcriptional control. In contrast, the increases in seven other proteins were unaffected by actinomycin D, suggesting that their expression was under translational control. These proteins will serve as useful markers for determining how cells progress through early lag phase.

Animals↗
PubMed1981

Partial trisomy 6q, due to balanced maternal translocation (6;22) (q21; p13) or (q21; pter).

We report a stillborn infant with partial trisomy 6q who had several major congenital malformations not previously associated with the chromosomal aberration. These included occipital encephalocele, ambiguous genitalia with imperforate anus, omphalocele and unilateral hydronephrosis. The infant's karyotype was 46,XY,-22,der(22),t(6;22)(q21; p13) or (q21;pter)mat. The mother and maternal grandmother are balanced translocation carriers.

Abnormalities, Multiple↗
PubMed1981

tRNA thiolated pyrimidines as targets for near-ultraviolet-induced synthesis of guanosine tetraphosphate in Escherichia coli.

Illumination with near-ultraviolet light triggers synthesis of ppGpp (guanosine 3'-diphosphate 5'-diphosphate) not only in growing Escherichia coli cells containing the putative chromophore 4-thiouridine in their tRNAs [Ramabhadran, T. V and Jagger, J. (1976) Proc. Natl Acad. Sci. USA, 73, 59--69], but also in nuv- cells which lack 4-thiouridine. The burst of ppGpp in nuv- cells is, however, induced exclusively by light of wavelengths shorter than 350 nm. Its maximum level is half that obtained in the parental strain. This ppGpp synthesis is also under the control of the relA gene, indicating that it is due to the accumulation of uncharged tRNAs. A candidate likely to trigger this effect is a 5-methylaminomethyl-2-thiouracil residues present in the first position of the anticodon loop of tRNAGlu, tRNALys and one tRNAGln isoacceptor. In conditions in vitro, this base is highly photoreactive at wavelengths shorter than 350 nm. Furthermore, near-ultraviolet-photomodified tRNAGlu and tRNALys become poor substrates of their acylation enzyme.

Escherichia coli↗