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Biomedical subjects

W Bauer

Publications and source records attributed to W Bauer.

At least 163 records · Page 9Linked to original sources
PubMed1979

[The facial mask as a basis of clindamycin therapy for acne vulgaris].

In 29 healthy male subjects aged between 20 to 25 years a powder face mask, consisting of 1.19% clindamycin phosphate (= 1% clindamycin base) in 70% ethanol was applied to the right side of the forehead once daily over a period of 5 days. At the same time half of the test subjects were treated in the same way on the left side of the forehead with a solution consisting of 1.19% clindamycin phosphate in 70% ethanol, and the other half with the same powder mask as on the right side but without clindamycin phosphate. The face mask containing clindamycin phosphate leads to a greater reduction of P. acnes. the total propionibacteria and the total bacterial counts (anaerobic culture) in the pilosebaceous duct than both other preparations. Compared with the initial values these do, however, reduce the bacterial count. The use of face masks containing antibiotics seems to offer a successful way of topical antibiotic treatment of acne.

Acne Vulgaris↗
PubMed1979

[Pharmacokinetic studies on broad spectrum antibiotic combinations of penicillin and oxacillin in normal volunteers (author's transl)].

After i.v. application of broad spectrum penicillins (ampicillin, mezlocillin, carbenicillin) alone or combined with oxacillin (concomitantly) in different dosages to normal volunteers, the course of serum levels and recovery from urine were assessed and pharmacokinetic data were calculated for a 1-compartment model, in some cases also for a 2-compartment model. The following penicillins were tested alone and combined with oxacillin; ampicillin 3 g, oxacillin 2 g and their combination; ampicillin 2 g, oxacillin 1 g and their combination; mezlocillin 3.75 g, oxacillin 1.25 g and their combination; mezlocillin 2 g, oxacillin 1 g and their combination; carbenicillin 7.5 g, oxacillin 2.5 g and their combination. Apart from one combination (oxacillin 2 g + ampicillin 3 g), all penicillin combinations exceeded the serum levels achieved after individual application at any time. In combinations, the elimination constants decreased, total clearance was lower, and half-lives increased. The distribution volumes varied. With one exception, oxacillin 2.5 g + carbenicillin 7.5 g, all the combinations yielded a higher recovery from urine than did individual administration. When administering i.v. two penicillins simultaneously, a process similar to that following administration of probenecid in association with caronamide must need be considered. It may be assumed that the prolongation and elevation of serum levels after combined administration likewise lead to higher tissue concentrations, which effect might be of clinical consequence.

Adult↗
PubMed1978

A spectroscopic and electron microscopic examination of the highly condensed DNA structures formed by denaturation in Mg(ClO4)2.

1. Thermal denaturation in 1.5 M Mg(ClO4)2 of the DNA from bacteriophage lambda results in four well-separated subtransitions, as monitored by the accompanying increase in absorbance. The midpoint of the hyperchromic spectrum is significantly lowered compared to either 1.5 M MgCl2 or 3.0 M NaClO4. 2. The first two subtransitions are associated with the melting of the A . T-richest regions of the lambda DNA, as revealed by electron micrographs following fixation with formaldehyde. 3. Commencing with the third subtransition, an unusual DNA structure is observed in electron micrographs. In this structure the A . T-rich half of the molecule appears completely condensed, whereas the G . C-rich half remains native. 4. During the fourth subtransition DNA molecules condense completely and eventually aggregate to form extremely high molecular weight particles containing centers of electron density. Tendrils of DNA, primarily duplex, radiate outward from these centers. 5. The aggregation may be reversed by the removal of magnesium. The intramolecular condensation may be at least partly reversed by increasing the Mg(ClO4)2 concentrations to saturating levels.

Coliphages↗
PubMed1977

Measurement of superhelix densities in buoyant dye/CsCl. The use of a standard other than native SV40 DNA.

The dye-induced separation between closed and open duplex DNAs in buoyant CsCl is determined primarily by the superhelix density of the closed DNA, provided that all other experimental variables (such as the solution density and dye concentration) are held constant. The extent of the buoyant separation may be used to estimate the superhelix density of an uncharacterized closed DNA, by comparison with the corresponding separation with native SV40 DNAs under identical conditions. We present here an extension of these quantitative relationships to permit the use of an arbitrarily selected closed duplex DNA of known superhelix density, with the accompanying open form, as a reference. The general result is that the ratio of buoyant separations for any two closed/open DNA pairs remains a linear function of the difference in superhelix densities between the closed DNAs. The value of the proportionality constant depends, however, upon the magnitude of the superhelix density of the closed DNA selected as reference.

Bacteriophages↗
PubMed1977

The effects of fractions (chalones) obtained from lymphoid organs on lymphocyte proliferation in vitro.

Aqueous extracts of lymphoid organs were prepared and fractionated by means of gel filtration, ion exchange chromatography, and isoelectric focusing. A protein-containing fraction with a molecular weight of approximately 80,000--90,000 and isoelectric points of 7.6 and 5.3--6.2 was isolated and shown to inhibit reproducibly both thymidine incorporation and proliferation of concanavalin A-stimulated mouse spleen lymphocytes in vitro. This effect appeared specific since proliferation of mastocytoma P-815 and leukemia L-1210 cells remained unaffected. A small molecular weight fraction (500 to 10,000 daltons) was also found to inhibit lymphocyte proliferation in vitro but was without apparent specificity for cell type.

Animals↗
PubMed1977

Heteroduplex mapping of small plasmids derived from R-factor R12: in vivo recombination occurs at IS1 insertion sequences.

Small, autonomously replicating plasmids derived by in vivo recombination from R-factor R12 (= R100) have been structurally mapped by heteroduplex formation between the plasmids and an R-factor which is structurally closely related to R6-5. Recombination resulting in generation of the small resistance-free plasmids occurs between the (IS1)b insertion sequence and various other sites on the opposite side of an origin of replication. A larger R12-derived plasmid pSM17, carrying streptomycin (Sm), sulfadiazole (Sa), and chloramphenicol (Cm) resistances, has recombined in a similar manner but at the (IS1)a sequence. A new structural coordinate origin for R100 and for partially homologous R-factors is proposed based upon the location of the (IS1)b sequence.

DNA, Bacterial↗
PubMed1977

Physical properties and gel electrophoresis behavior of R12-derived plasmid DNAs.

A series of closed circular (I) plasmid DNAs has been derived from drug resistance factor R12, and the nicked circular (II) and linear (III) derivatives of these molecules prepared by irradiation in the presence of ethidium bromide and by treatment with restriction enzyme EcoRI, respectively. These DNAs encompass the molecular weight range 3.6 to 61 megadaltons. The base compositions range from 45% to 51% (GC) as estimated by buoyant density determinations. The smaller plasmids are significantly less supercoiled (9-10%) than are the larger (12-13%). The gel electrophoretic behavior of the three DNA structural forms was determined as a function of molecular weight in agarose gels of concentrations ranging from 0.7% to 1.6% and at electrophoresis salt concentrations from 0.02 M to 0.08 M sodium acetate. The mobilities of DNAs I and III undergo a reversal relative to each other at a molecular weight which decreases with increasing agarose gel concentration. The molecular weight at which DNA II fails to enter a gel depends upon the ionic strength during electrophoresis but not upon the gel concentration.

Centrifugation, Density Gradient↗
PubMed1977

An endoscopically-introducible T-tube for tracheal stenosis.

Five cases of tracheal stenosis are presented, and aspects of etiology and pathophysiology of the disease are discussed. A new soft, flexible T-tube is described along with a method of endoscopic introduction. Although many patients with tracheal stenosis will eventually need tracheal reconstruction, stenting may be definitive in selected cases.

Adult↗
PubMed1976

Isolation, by tetracycline selection, of small plasmids derived from R-factor R12 in Escherichia coli K-12.

The examination, by agarose gel electrophoresis, of tetracycline-resistant colonies of Escherichia coli K-12 carrying R-factor R12 reveals the presence of smaller plasmid deoxyribonucleic acids (DNAs), incompatible with R12, in many of the clones. These plasmids are demonstrated to be homologous with R12 DNA by electron microscope heteroduplex experiments and by the production of consistent fragment patterns upon digestion with various restriction endonucleases. These autonomously replicating plasmids form a related series of covalently closed circular DNA molecules ranging in size from 3.6 X 10(6) to 61 X 10(6) daltons. Plasmids of molecular weight between 3.6 X 10(6) and 37 X 10(6) confer no antibiotic resistances, but when jointly present with R12 by nonetheless enhance the expression of the tetracycline resistance associated with this latter molecule.

DNA Restriction Enzymes↗