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Biomedical subjects

N Fuchs

Publications and source records attributed to N Fuchs.

26 records · Page 2Linked to original sources
PubMed1992

Mutation and mapping of genes involved in production of the antibiotic TA in Myxococcus xanthus.

Transposition of TnV and Tn5lac into Myxococcus xanthus yielded 8,381 kanamycin-resistant mutants that were tested for antibiotic TA production. Twenty-four of the mutants were nonproducers of TA (less than 0.4 ng/ml), and 3 produced a higher level (2.5 micrograms/ml) than the parent strain (1.5 micrograms/ml). For most of the strains, there was 100% cotransduction between kanamycin resistance and the altered TA phenotype. Southern blot analysis of restriction digests of the mutant DNA indicated that the transposons were inserted at different sites on the M. xanthus chromosome. The TA genes were mapped by cotransduction between pairs of mutants following replacement of the initial insert of one of the pair with the tetracycline resistance transposon Tn5-132. Nine of the 13 nonproducers tested were linked over a 36-kb stretch of the chromosome. There was no linkage between one of the overproducers and any of the nonproducers tested.

Anti-Bacterial Agents↗
PubMed1992

Use of Tn5lac to study expression of genes required for production of the antibiotic TA.

The beta-galactosidase activities arising from Tn5lac insertions in several genes required for antibiotic TA production were measured under different growth conditions. In all of the non-TA-producing mutants, the beta-galactosidase specific activity was higher when the cells were grown in nutrient-limited 0.5CTS medium (0.5% Casitone plus alanine, serine, and glucose) than in rich 2CT medium (2% Casitone). One of the mutants, 420, had low beta-galactosidase specific activity in both media. The other seven mutants containing inserts in genes essential for TA production had specific activities of 139 to 367 U/mg of protein in 0.5CTS medium and 11 to 48 U/mg of protein in 2CT medium. The beta-galactosidase specific activities of two strains, 1030 and 420, increased during exponential growth in 0.5CTS medium. The beta-galactosidase specific activities of both strains increased greatly when the cells were grown in the presence of magnesium phosphate, which traps ammonium ions. The Tn5lac insertions in 1030 and 420 were used to screen for mutants with increased levels of transcription. An N-methyl-N'-nitro-N-nitrosoguanidine-induced mutation in 1030 that mapped 17 kb from the omega 1010 insert increased the specific activity of beta-galactosidase 21 times in 2CT medium. The regulatory mutation appears to release the repression caused by 2CT medium. A UV-induced mutation in 420 increased the beta-galactosidase specific activity 1.4 to 2.4 times. Medium conditions that affect the transcription of TA genes are discussed in terms of enhanced antibiotic TA production.

Anti-Bacterial Agents↗
PubMed1989

[The ultrasonic demonstration of gas in the endometrial cavity--an aid for the diagnosis of puerperal endometritis].

A pilot study was undertaken to determine the prevalence of gas in the puerperal endometrial cavity and to determine whether this finding has any relationship to the mode of delivery or to the development of puerperal endometritis. On the first day after delivery 192 patients were examinee ultrasonographically and gas was demonstrated in 26 (13.54%). Gas was found significantly more often in relation to caesarean section and intra-uterine manipulation than in normal vaginal deliveries (P less than 0.0001). On the third puerperal day the gas disappeared in 12 patients but persisted in 14, of whom 7 had signs of endometritis. Endometritis was diagnosed in a total of 8 patients and only 1 did not have signs of gas in the endometrial cavity. Although the figures are small it is concluded that ultrasonography of the puerperal uterus might assist in the diagnosis of puerperal endometritis.

Adolescent↗
PubMed1989

[Fluorescence diagnosis of porphyrin-marked urothelial tumors. Status of experimental development].

On the basis of selective storage of fluorescing hematoporphyrin derivative (HpD) in tumors, a method has been developed that enables the endoscopic detection of early-stage cancer by monitoring fluorescent images. The contrast-reducing portion of the superposed tissue autofluorescence is suppressed by the use of two-wavelength excitation and subsequent image processing in realtime. The amount of photosensitizing HpD necessary for diagnostic purposes is considerably reduced by means of sensitive detection devices. A clear distinction between benign and malignant bladder tissue seems possible according to the results of animal studies.

Animals↗
PubMed1975

Virus isolation and titration at 33 degrees and 37 degrees C.

Various prototype viruses and original specimens were comparatively titrated in cell cultures at 33 degrees and 37 degrees C. Higher titers at 37 degrees were consistently obtained with adenoviruses; for other viruses (enteroviruses, herpesvirus hominis, vaccinia virus, parainfluenza viruses) the titers were mostly identical at either temperature. Original specimens and prototye strains showed the same behavior. The habit to cultivate viruses from throat swabs at 33 degrees C is unsatisfactory for adenoviruses.

Adenoviridae↗
PubMedDate not supplied

[The prognostic significance of tumor volume in osteosarcoma with neoadjuvant chemotherapy].

In a retrospective analysis on 128 patients from the trials COSS-80, -82, -85 and -86 initial x-ray pictures were evaluated for tumor diameters in three planes and the prognostic meaning on survival was assessed. In a subset of patients (n = 27) the measured values were compared to values obtained by CT-Scan and a good correlation (r = 0.69) was found. Several parameters for tumor size were defined: absolute tumor length (ATL), relative tumor length (RTL, proportion of tumor to the length of the involved bone), absolute tumor volume (ATV, calculated by the ellipsoid formula) and relative tumor volume (RTL, tumor volume referred to the body surface area) and univariate and multivariate survival analysis were performed. Univariate analysis of metastasis free survival (MFS) revealed a high prognostic significance of the ATL, the ATV and the RTV. The RTL in this patient group demonstrated a tendency only toward an inferior prognosis in larger tumors. None of the patients with a ATV < 70 ml (n = 19) and only one of 33 patients with an ATV < 100 ml relapsed. Cox regression analysis was performed including the variables age, sex, site and response (> 90% tumor necrosis) in 84 patients. ATL and RTL do not enter the model, while the response proves its significance as a valid prognostic factor with a p-value of 0.0004. Adding the ATV as the measure of tumor size to the model it enters as the first term (p = 0.0000) followed by the response (p = 0.0002).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗