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Biomedical subjects

J Wilhelm

Publications and source records attributed to J Wilhelm.

At least 109 records · Page 6Linked to original sources
PubMed1976

Characterization of adenovirus type 2 transcriptional complexes isolated from infected HeLa cell nuclei.

HeLa cell nuclei, isolated 17 h after infection with human adenovirus type 2 (Ad2), were treated with 200 mM ammonium sulfate. The extract (S200 fraction) contained 50 to 70% of the nonintegrated Ad2 DNA, which was in the form of nucleoprotein complexes. These complexes contained native, intact Ad2 DNA (with the exception of replicative intermediates) and could be partially purified and resolved by velocity gradient centrifugation. Using high-salt (200 mM ammonium sulfate) incubation conditions, more than 95% of the nuclear RNA polymerase activity belonged to class B. About 45% of the class B enzyme molecules bound to DNA in the nuclei (those "engaged" in RNA synthesis) were released from the nuclei in the form of Ad2 transcriptional complexes by treatment with 200 mM ammonium sulfate. At least 90% of the RNA synthesized in high salt in the nuclei or in the S200 fraction was Ad2 specific, and essentially all of this RNA was complementary to the l strand of Ad2 DNA. These findings are compatible with what is known about Ad2-specific RNA synthesis in vivo. The analysis of the RNA synthesized from partially purified transcriptional complexes supports the contention that its transcription is almost entirely asymmetric, and that the asymmetry observed in vivo is not a consequence of the rapid degradation of h-strand transcripts. The RNA synthesized in vitro in the absence of detectable RNase activity sedimented with a maximum size of 35 to 40S. Less than 5% of the nuclear or the S200 fraction RNA polymerase activity was class C when assayed under non-reinitiating conditions. Although much of the RNA synthesized by the class C enzyme was Ad2 specific, 5.5S virus-associated RNA was not the predominant product. The isolation of Ad2 DNA transcriptional complexes provides an attractive system for further characterizing the Ad2 DNA template used for transcription and for studying the regulation of the expression of the Ad2 genome during the productive infection cycle.

Adenoviridae↗
PubMed1975

The diagnostic value of enzymuria, cell excretion, and proteinuria in experimental renal diseases.

Enzymuria, urinary cell excretion and proteinuria were simultaneously determined in renal diseases of female Wistar rats in order to investigate the diagnostic value of urinary enzymes. Investigations were carried out on rats with E. coli-pyelonephritis facilitated by oestradiolundecylate, aminonucleoside nephrosis, aminoglycoside induced renal lesions and pyelonephritic animals treated with therapeutic and toxic doses of tobramycin. --From the results of these studies it was concluded that the main diagnostic value of urinary enzymes is detection of drug induced tubular lesions in individuals with preexisting renal diseases.

Animals↗
PubMed1975

[Experimental study in rats on the renal compatibility of cephalothin and cephalothin-aminoglycoside combinations (author's transl)].

The possible nephrotoxity of cephalothin and the antibiotic combinations cephalotin-gentamicin and cephalothin-tobramycin was investigated in standardized animal experiments. Toxicity parameters were blood-urea concentration, the urinary enzymes GOT, LDH, MDH and the cell excretion rate, supplemented by histological investigations of the kidneys. Compared with other cephalosporine derivates, the antibiotic cephalothin in a toxic threshold-dose of 3000 mg/kg/day proved to be realtively well tolerated by the kidneys. On comparison with the respective monotherapy, the renal tolerance for cephalothin-aminoglycoside combinations was reduced. The clinical value of these findings is discussed.

Aminoglycosides↗
PubMed1975

Regional ventilation-perfusion relationships.

Regional ventilation-perfusion ratios have been determined in 12 healthy subjects, 16 patients with pulmonary embolism, and 22 patients with chronic obstructive lung disease. The ventilation-perfusion ratios were determined from xenon-133 ventilation studies and 99-tc-m-labeled particle perfusion scans, using either the fractional exchange of air or the relative distribution of tidal volume per unit volume as the numerator of the ratio. A comparison of these two methods showed comparable distributions of regional ventilation-perfusion relationships in the healthy subjects and patients with pulmonary embolism. However, in the patients with chronic obstructive pulmonary disease, the fractional exchange method clearly separated this group of patients from the others.

Chemotherapy, Cancer, Regional Perfusion↗
PubMedDate not supplied

Redox regulation of proliferation of lens epithelial cells in culture.

Both oxidants and antioxidants have been shown to modulate cell proliferation. We studied the effects of hydrogen peroxide and two antioxidants on the rate of proliferation of lens epithelial cells in culture. Hydrogen peroxide at concentrations higher than 32 microM caused a significant inhibition of proliferation. However, in the concentration range of 0.01-0.5 microM, hydrogen peroxide stimulated the rate of proliferation. The effect of hydrogen peroxide was dependent on the amount of cells in an individual culture well, indicating decomposition of hydrogen peroxide by cellular enzymes. In order to eliminate the possibility of decomposition of the dose of hydrogen peroxide given as a bolus, we induced continual production of hydrogen peroxide by adding glucose oxidase to the incubation medium. We found that hydrogen peroxide, generated by 1-50 microU x ml(-1) of glucose oxidase significantly increased the rate of cell proliferation. This effect was most apparent at the beginning of the exponential phase of cellular growth. Glucose oxidase alone (100-500 microU x ml(-1)) did not produce any effect. The effects of pro-oxidative hydrogen peroxide were compared with the effects of two biologically important antioxidants, alpha-tocopherol and retinol. Both antioxidants completely inhibited proliferation at concentrations of 30 microM and higher. In contrast to retinol, the effect of alpha-tocopherol was dependent on the amount of cells, indicating cellular decomposition of alpha-tocopherol. The results document the possibility of redox regulation of cellular proliferation at physiologically relevant reactant concentrations.

Anilides↗
PubMedDate not supplied

Mechanistic studies on the role of PAHs and related compounds in PCDD/F formation on model fly ashes.

Model fly ashes containing Florisil, CuCl2.2H2O and PAHs with structures similar to dibenzo-p-dioxin or dibenzofuran were heated at 250 degrees C in He/O2 with regard to a supposed intramolecular reaction mechanism for oxygen incorporation. Highest reactivities in PCDF formation could be found for model compounds containing a biphenyl structure, while condensed pi-systems lead to a decrease in reactivity for such compounds. Biphenyl is almost completely converted to dibenzofuran. PCDD formation from six-membered rings like xanthene/9,10-dihydroanthracene is of minor importance. 18O-labeling of gaseous oxygen reveals no common reaction step for oxygen incorporation using 9-fluorenone, xanthene, diphenyl ether and diphenyl-2-carboxylic acid as model compounds. Pre-existing oxygen in reactants is a major source for ether groups in PCDD and PCDF. Determination of labeled and unlabeled CO and CO2 besides He/O2 reflects higher reactivities towards oxidation for model compounds containing ether groups than for compounds with carbonyl groups.

Journal Article↗