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Biomedical subjects

J Böhm

Publications and source records attributed to J Böhm.

15 recordsLinked to original sources
PubMed1992

[The significance of the mycotoxins desoxynivalenol, zearalenone and ochratoxin A for agricultural domestic animals].

Mycotoxins are metabolic products of mycotoxins which have various chemical structures and show various toxic effects. Deoxynivalenol (vomitoxin) is an important economic factor in pig production due to growth depression and suppression of the immune system. Previous studies have shown that the 1-ppm limit in the sole feed for pigs should not be exceeded. Studies of methods of detoxification have as yet not produced conclusive results. Zearalenone has an tolerable effect and may lead to fertility disturbances on the oestrogen production in pigs and can cause remarkable economic damage even in the ppb range. Recommendations of upper limits cannot be made on the basis of the available results. The kidney toxin ochratoxin A is of importance in pig and poultry breeding and--due to its accumulation in the tissue--represents a possible source of danger to man. Since a possible carcinogenic effect of the toxin cannot be excluded, its content in animal rations should be kept as low as possible. For ruminants mycotoxins as a whole do not represent a particular source of danger as these substances can be degraded or converted by rumen flora.

Animal Feed↗
PubMed1991

Carboxy-terminal truncated rhuIFN-gamma with a substitution of Gln133 or Ser132 to leucine leads to higher biological activity than in the wild type.

The biological function of the 20 C-terminal amino acids of human interferon-gamma (IFN-gamma) was examined by recombinant DNA methodology. Six truncated IFN-gamma analogues were produced by modification of the 3' end of the coding sequence of the cloned gene, insertion into a vector with the trc promoter and expression of the recombinant IFN-gamma analogue genes in Escherichia coli strain JM 105. The IFN-gamma analogue proteins were shortened by 10 (C-10L), 11 (C-11, C-11L), 14 (C-14L), 19 (C-19L) and 20 (C-20) amino acid. Four of these constructs were modified to have a C-terminal leucine. The expression rates of precipitating IFN-gamma variants in E. coli cells (wild type, C-10L, C-11, C-11L) amount to 35-40% of the total protein, in contrast to 14-21% for the mainly soluble ones (C-14L, C-20). The variant C-19L has an exceptional position in its solubility behaviour with a nearly 1:1 distribution between its soluble and insoluble form by an expression rate of 8%. The purification protocol of the insoluble variants contains a denaturing and a renaturation step. The characteristic step for purification soluble IFN-gamma is HPLC cation-exchange chromatography. The antiviral activities of the variants lacking 14 or more amino acids are less than 2% of the wild-type activity. The variants C-10L, C-11 and C-11L show higher biological activities than wild-type IFN-gamma. The most active variant, C-10L, with leucine as the last C-terminal amino acid, has a fourfold higher specific antiviral activity (A549 cells, encephalomyocarditis virus). Removal, but not replacement of the leucine, represented by the variant C-11, reduces the biological activity compared with variant C-10L. The activity of C-11 is, nevertheless, higher than in the wild type. Comparing the secondary structures, as judged by CD analyses, no significant differences for C-10L, C-14L and C-20, compared with wild type, are observed. Also, all molecules, including the wild-type protein, exist as dimers under physiological conditions. There is a correlation between the grade of truncation and the pI values, which range from pI = 10.4 (wild type) to pI = 8.0 (C-20). The variant C-10L demonstrates a higher temperature stability (tm = 55 degrees C) compared with wild type (tm = 53 degrees C). Perhaps this higher stability will result in a longer half-life in vivo.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1991

Bilateral stromal Leydig cell tumour of the ovary. Case report and literature review.

The stromal Leydig cell tumour of the ovary is a very rare benign neoplasm which usually occurs in postmenopausal women. Due to a significant production of androgens by the tumour, it is frequently associated with symptoms of virilization. To our knowledge only 7 cases have been reported in the literature, one of them with bilateral manifestation. We report an additional case affecting both ovaries in a 59-year-old nun with long-standing virilism, review the literature, and discuss the histomorphological features for differential diagnosis.

Diagnosis, Differential↗
PubMed1991

Removal of 3' nontranslated cDNA sequence improves interferon gamma synthesis in Escherichia coli.

The cDNA coding for human interferon gamma contains approximately 600 basepairs not translated sequence with 4 adenine/thymidine (AT)-rich clusters at its 3'end. The influence of this sequence on the expression of recombinant human Interferon gamma in Escherichia coli was investigated. Removal of the non-translated sequence and especially of the AT-rich clusters yielded an increase in expression of interferon gamma from 10 to 40% of total protein. These results may also be important for the production of other recombinant human proteins with similar 3' sequences in their cDNA.

Bacterial Proteins↗
PubMed1990

[Androgenization in postmenopause in rare ovarian tumors--2 case reports].

Androgen-producing tumours of the ovary are uncommon in postmenopausal women. We report on symptoms of two patients with androgenization due to a stromal-Leydig cell tumour and a steroid-cell tumour, respectively. Clinical signs and symptoms, laboratory findings and therapeutic consequences are discussed.

Aged↗
PubMed1987

Lead in human bones. Investigations on an occupationally non-exposed population in southern Bavaria (F.R.G.). I. Adults.

The concentration of lead in three different bones (pelvic bone, cortical part of the mid-femur, petrous portion of the temporal bone) of 240 occupationally non-exposed adults who died between October 1983 and February 1985 was determined by electrothermal atomic absorption spectrometry. As far as sex, age and domicile (urban and rural) are concerned, a balanced distribution was achieved (for each age decade 10 urban females, 10 rural females, 10 urban males and 10 rural males). The predominantly cortical femur (geom. mean, 3.86 mg Pb/kg bone wet wt.) and temporal bones (5.59) showed higher Pb concentrations than the trabecular pelvic bone (1.65) (in each case n = 240). For each of the three types of bone, the mean lead content of the males (n = 120) was significantly higher than those of the females (n = 120): e.g. for pelvic bone by 38.3%, mid-femur by 51.3% and temporal bone by 24.8%. No statistically significant difference was obtained when comparing residents of Munich (population greater than 1 X 10(6] (n = 120) with people in the remaining parts of Southern Bavaria (n = 120). The Pb content of the temporal bone increased steadily with age. In contrast, in the mid-femur and the pelvic bone the Pb content reaches a plateau in middle age with a decrease at higher ages; this decline is more distinct for females. The mean lead body burden was calculated to be 41.4 +/- 24.2 mg for all males (n = 120) and 24.1 +/- 12.5 mg for all females (n = 120). We conclude that the lead burden, at least in the area investigated, has been reduced in the last decade, probably because of a reduction in the lead content of petrol.

Adolescent↗
PubMed1985

[Animal experiment results with a new vena cava filter].

A new cava filter has been tried in 23 dogs weighing between 16 and 23 kg. The filter consists of a stainless steel basket which can be introduced either antegrade or retrograde through a 10F teflon catheter and which can be removed again within the first four days. The filter was effective in holding back embolising thrombus. In the early stages, even without artificial embolisation, two out of five animals showed clot formation in the basket. After three or four months, all the filters were permeable and on only two occasions was a small amount of thrombus found.

Angioplasty, Balloon↗
PubMed1980

A histone-specific acetyltransferase is associated with simian-virus-40 chromatin.

[14C]Thymidine-labeled simian virus 40 nucleoprotein complexes were prepared from nuclei of lytically infected African green monkey kidney cells. The nucleoprotein complexes were further purified by sucrose gradient centrifugation and then incubated in the presence of [3H]acetyl-coenzyme A. We observed a transfer of [3H]acetyl groups to the endogenous histones H2B, H3 and H4. The enzyme was solubilized in the presence of 0.5 M NaCl and showed properties described for the DNA-binding acetyltransferase (J. Böhm, E. J. Schlaeger and R. Knippers, preceding paper in this journal).

Acetylation↗
PubMed1977

Studies on protein-phosphorylation reactions in isolated chromatin.

The endogenous protein-phosphorylating activity of isolated chromatin was tested. We have found that a group of high-molecular-weight proteins (Mr greater than 50 000) was preferentially phosphorylated when chromatin from mouse ascites cells or from bovine lymphocytes was incubated in the presence of ATP. After disintegration of chromatin by nuclease treatment or by high salt concentration, a larger spectrum of chromatin proteins becomes accessible for phosphorylation by the chromatin-bound protein kinase. Some observations described in this communication may help to partially explain this result. The protein kinase was not found in nucleosomal subunits, indicating a non-random distribution of the enzyme in chromatin. This suggests that enzyme and substrate have to be in close spatial contact for the phosphorylation reaction to occur. Furthermore, we have shown for one protein, histone H1, that phosphorylation sites for the endogenous protein kinase are available on the free but not on the DNA-bound protein, suggesting that phosphate-accepting sites in chromatin proteins may be blocked by protein-DNA or by protein-protein interactions. We also discuss the possibility that chromatin protein kinase occurs in stable complexes with its phosphate-accepting substrates, as has been suggested by the findings of other [Kish, V.M. & Kleinsmith, L.J. (1974) J. Biol. Chem. 249, 750-760].

Animals↗
PubMed1976

Saturation corrections for plane-parallel ionization chambers.

Experiments described in the literature lead to different formulae for saturation corrections in ionization chambers. To elucidate the differences, saturation curves of an extrapolation chamber irradiated with beta particles from 90Sr+90Y sources have been studied experimentally. The results could be described by one formula which was a combination of known formulae for charge collection losses due to volume recombination, initial recombination and diffusion.

Mathematics↗
PubMedDate not supplied

Interferons inhibit chemotaxis of transformed cells and their invasion of a reconstituted basement membrane.

Tumor cell migration and invasion are critical steps in the complex process of metastasis formation. It has been demonstrated that interferons (IFNs) inhibit the motility of human fibroblasts. In the present investigation we tested the effect of human leukocyte IFN and murine fibroblast IFN on the chemotactic migration of transformed and tumor-derived cells towards fibroblast conditioned medium. We were able to show that IFNs preferentially inhibit the chemotaxis of transformed and tumor-derived cell lines when compared to control fibroblasts. Inhibition was dose-dependent and most tumor cell strains were sensitive to concentrations of IFNs 10- to 100-fold lower than fibroblast cultures. Furthermore, leukocyte interferon was able to inhibit the invasion of transformed 3T3 fibroblasts through a gel of reconstituted basement membrane (Matrigel). These effects could be related to the antineoplastic activity of interferon.

Basement Membrane↗