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Biomedical subjects

H Hoffmann

Publications and source records attributed to H Hoffmann.

At least 253 records · Page 14Linked to original sources
PubMed1983

[Protein binding of the macrolide antibiotic turimycin. Methodologic effects on results].

A methodological investigation deals with the binding of the macrolide antibiotic turimycin to bovine serum albumin (BSA) and serum proteins. On this occasion, it is pointed out that, especially when serum is used, the critical evaluation of the analytical method is of the same importance as the utilization of standardized procedures for the quantification of the protein binding in the sense of general comparability. This concerns, for example, the chemistry of the reaction used for detection, the formation of degradation products of the active principle in the serum during the study of the binding and possible repercussions on the chemical determination, the electrolyte content of the sample in the punched hole of the microbiological test plate, losses of activity or synergistic effects of the serum-antibiotic combination during incubation of microbiological test plates after termination of the equilibrium dialysis. The determination of binding constants by means of a competitive fluorescence titration, the chemical analysis of equilibrium dialyses and their parallel assessment with the aid of the agar-diffusion plate test led to results which were not in agreement with each other. Turimycin which is very slightly soluble at pH = 7.4 and fairly soluble at pH = 5.0, is practically not bonded at the lower pH value of BSA and serum proteins (fluorescence titration of BSA: Kb approximately 20; equilibrium dialysis and chemical evaluation). The microbiological determination in serum on the basis of equilibrium dialyses yields higher values for the binding of turimycin.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Assay↗
PubMed1983

Suppression of tumorigenicity in hybrids of tumorigenic Chinese hamster cells and diploid mouse fibroblasts: dependence on the presence of at least three different mouse chromosomes and independence of hamster genome dosage.

Somatic cell hybrids were generated between Chinese hamster cell lines (Cl-4 and TK 17-O) with a near-diploid number of partially abnormal chromosomes and embryonic mouse fibroblasts (BALB/c). Hybrids harboring a near-diploid, near-triploid, and near-tetraploid set of hamster chromosomes plus 22 to 30 mouse chromosomes were analyzed for the expression of the transformed or tumorigenic phenotype, respectively, indicated by their capacity to form colonies in soft agar and by tumor formation after s.c. injection into nude mice. The hybrids showed (partial) suppression of tumorigenicity and of anchorage independence. The minimum number of hybrid cells required to initiate tumor growth in nude mice was 100- to 50,000-fold higher, and the latency period was 3- to 6-fold longer in comparison with the highly tumorigenic parental hamster cells. Suppression of tumorigenicity was also found in intraspecific Chinese hamster hybrids involving tumorigenic cells (E 36-O and TK 17-O) and embryonic hamster fibroblasts. To identify those mouse chromosomes associated with suppression of tumorigenicity, we investigated the expression of mouse isozyme genes and the presence of mouse chromosomes in interspecific suppressed hybrids and their tumorigenic hybrids described previously. No single mouse chromosome, even if present in two copies, and no combination of two different mouse chromosomes was sufficient to suppress tumorigenicity in these hybrids. This conclusion is based on either the presence of these chromosomes in hybrids isolated from tumors or their absence in suppressed hybrids.

Agar↗
PubMed1982

Toxicity of the progestagen STS 557 compared to levonorgestrel in beagles after oral administration for 6 months.

Female and male beagle dogs were administered orally STS 557 (17 alpha-cyanomethyl-17 beta-hydroxy-13 beta-methyl-gon-4,9(10)-dien-3-one) for 6 months at dose levels of 0.01, 0.1, or 1.0 mg/kg/day, and levonorgestrel at a dose of 1.0 mg/kg/day, respectively. The results mainly confirmed the gestagenic efficacy on the reproductive organs of both compounds acting directly or via the anterior pituitary gland. In contrast to levonorgestrel, STS 557 did not show any androgenic activity, but had slightly estrogenic effects. Neither clinical, functional nor morphological investigations revealed toxic side effects of the drugs on the liver, the kidneys, the bone marrow, or on blood clotting function.

11-Hydroxycorticosteroids↗
PubMed1982

Postnatal differentiation of sex-specific distribution patterns of G6Pase, G6PDH and ME in the rat liver.

The activity of the liver enzymes G6Pase, G6PDH and ME was studied in rats of 2-9 weeks old by histochemical means. In addition, G6PDH and ME activity was quantitatively determined in homogenates. In the 2nd and 3rd week G6Pase is similarly distributed in both sexes: while in the periportal zone high activity is demonstrable, the perivenous zone shows only low activity. After this period a nearly homogeneous distribution pattern becomes evident in all animals. Sex difference occurs after the 6th week: in the livers of male rats the periportal "maximum" is sometimes combined with a second peak in the perivenous area, in females a steep gradient emerges with high activity in the periportal zone and a low one in the perivenous zone. In the first postnatal weeks G6PDH activity is very low in parenchymal cells, but very prominent in Kupffer cells. Around the 5th week there is an increase, predominantly in the perivenous zone of both sexes. While there is again a further decrease demonstrable in male rats, the G6PDH activity of female rats rises to high adult values. This increase seems to be restricted to the perivenous zone. ME can be demonstrated at first in leucocytes. In the course of the 3rd week there is an increase of activity in both sexes: ME is demonstrable in parenchymal cells of the perivenous area and in scattered hepatocytes of the periportal area. In male rats, the perivenous activity is diminished towards the end of the investigation period, in females, however, a high activity remains in the perivenous zone. The data show that in females the activity of NADP dependent enzymes is high in the perivenous zone, so it may be assumed that a lipogenic area is situated around the terminal efferent vessels. Because of the sex difference this area may be hormone-dependent. The lipogenic area is situated opposite to the gluco(neo)genic area which corresponds to the periportal zone.

Aging↗
PubMed1982

Pharmacokinetics of 3-[bis(2-hydroxyethyl)amino]acetophenone [4,5-diphenyloxazolyl-(2)]hydrazone (ZIMET 98/69) in rats.

The pharmacokinetics of 3H-ZIMET 98/69 after i.v. and oral administration to rats was studied. After i.v. administration of 2.5 and 10 mg/kg a biphasic exponential decay of total serum radioactivity was found, so that a two compartment open model could be assumed. Oral administration of 10 mg/kg results only a moderate bioavailability (25%), which further decreased after administration of higher doses. The distribution steady state between serum and tissue is reached rapidly. Elimination proceeds slowly, the serum half-life being 64-84 h.

Administration, Oral↗
PubMed1982

[The "social prestige" of the manic patient].

A total of 55 male patients with endogenous manic psychoses were studied over a period of four years. In 50 of them, a loss of prestige in the social milieu, which in some cases was quite considerable, had developed, partly directly due to the disease-specific psychic disturbances and the resulting abnormalities in behaviour (sometimes of penal relevance), but in some cases also due to legally prescribed measures (change of occupation, withdrawal of driving license, frequent hospitalizations). From this the necessity results to consider in maniacs also the social aspects of their disease and if possible to include the reference persons in the therapy conception.

Adult↗
PubMed1982

[Studies in mice on diminishing acute toxicity of violamycin BI by combined therapy (author's transl)].

In mice the effect of L-ascorbic acid (i.p., drink. wat.), DL-carnitine (i.p., drink. wat.), L-cysteine (i.p., drink. wat.), DL-methionine (i.p., drink. wat.), folic acid plus ascorbic acid (i.v.), and alpha-tocopherol (i.p.), respectively, on sublethal and lethal i.v. doses of the anthracycline antibiotic violamycin BI (VBI) was tested. The VBI induced lethality (%) of the animals was found to be unaffected by combined treatment with the drugs used. Only a delayed toxicity following alpha-tocopherol administration was observed.

Aminoglycosides↗
PubMed1982

[A non-invasive stress test for fetal movement stimulation].

A method for foetal stimulation is required for both interpretation of external CTG and assessment of foetal mobility status. All methods so far described in the literature proved to be impracticable for their invasive nature or for insufficient controllability. An approximately unitised level of stimulation is necessary for proper assessment of mobility standards, and this has been achieved by means of sound stimulation. The latter is based on a body sound transmitter coupled to a sinus generator. Sensitivity of the method is 90 per cent. Preliminary comparison between quantity of movement and birth weight of examined foetuses has provided some clues to the effect that the responsiveness to external stimuli of newborns with low birth weight had been comparatively low, which was reflected in less movement activity.

Acoustic Stimulation↗
PubMed1981

Studies on anti LSP autoantibodies in acute and chronic non-B hepatitis -- evidence for the lack of anti LSP in non-A, non-B (NANB) viral hepatitis.

The prevalence of autoantibodies against the liver membrane antigen LSP (anti LSP) has been studied in acute and chronic non-B hepatitis. Anti LSP autoantibodies were detected in five of eight patients with type A and in two of 18 patients with type non-A, non-B (NANB) acute hepatitis. No statistically significant difference was observed between the group of anti LSP positive and anti LSP negative cases of acute non-B hepatitis concerning age, serum glutamic pyruvic transaminase (SGPT), and serum bilirubin levels. In hepatitis A SGPT and bilirubin levels were significantly higher as compared to type NANB acute hepatitis. Sera which were positive for anti LSP in the acute phase were negative within 2 months from onset although the two anti LSP positive patients hepatitis (CPH). None of 27 patients with chronic NANB hepatitis displaying the morphology of CPH were anti LSP positive; in contrast, six of nine patients with autoimmune type chronic hepatitis were anti LSP positive, displaying the morphology of chronic active hepatitis. In conclusion, in acute hepatitis anti LSP autoantibodies are a consequence of liver cell destruction rather than being involved in the mechanism of liver cell necrosis. Anti LSP autoantibodies are unlikely to play an important role in the development of chronic NANB hepatitis.

Acute Disease↗