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Biomedical subjects

H Schwab

Publications and source records attributed to H Schwab.

At least 55 records · Page 3Linked to original sources
PubMed1991

Molecular characterization and functional analysis in Aspergillus nidulans of the 5'-region of the Penicillium chrysogenum isopenicillin N synthetase gene.

The isopenicillin N synthetase gene (pcbC) was isolated from a genomic library of Penicillium chrysogenum BC39813, a penicillin production strain. The nucleotide sequence, including 555 bp upstream of the translation start site was determined. Various deletions within the pcbC 5'-region were constructed and linked to the Escherichia coli lacZ gene. An Aspergillus nidulans argB strain was transformed with DNA of these constructions. The region essential for promoter function could be localized between positions -307 and -89 by analyzing beta-galactosidase expression of transformants containing a single copy of the corresponding plasmid integrated at the homologous argB locus. A region responsible for regulatory effects concerning nitrogen metabolism was identified by determining beta-galactosidase activities in cell-lysates of transformants cultivated under varying growth conditions. Two major transcription start sites at positions -131 and -132, as well as a further upstream located site at position -397 +/- 1 could be located by primer extension studies employing RNA isolated from P. chrysogenum BC39813.

Amino Acid Sequence↗
PubMed1991

Expression of the Bacillus subtilis levanase gene in Escherichia coli and Saccharomyces cerevisiae.

The gene coding for the inulin hydrolyzing enzyme levanase which was previously cloned from Bacillus subtilis was fused to the tac-promoter. Overexpression in Escherichia coli resulted in high amounts of intracellularly produced levanase (up to 20 U mg-1). After removal of the bacterial 5' sequences, the levanase gene was also cloned into a yeast expression vector based on the PGK-promoter. Clones containing the intact levanase gene including the bacterial signal sequence gave rise to synthesis of active levanase by Saccharomyces cerevisiae transformants. A considerable amount of levanase protein was found in the culture medium (around 0.5 U ml-1) indicating efficient secretion of B. subtilis levanase from yeast.

Amino Acid Sequence↗
PubMed1991

Molecular cloning and sequencing of a pectinesterase gene from Pseudomonas solanacearum.

Two pectinesterase-positive Escherichia coli clones, differing in expression levels, were isolated from a genomic library of Pseudomonas solanacearum. Both clones contained a common DNA fragment which included the pectinesterase-encoding region. The different expression levels found with the two clones could be ascribed to different positioning of the pectinesterase gene with respect to a vector promoter. Restriction analysis, subcloning, and further exonuclease deletion mapping revealed that the genetic information for pectinesterase was located within a 1.3 kb fragment. A protein of 41 to 42 kDa was expressed from this fragment. Nucleotide sequence analysis of the respective region disclosed an open reading frame of 1188 bp. The deduced polypeptide had a calculated molecular mass of 41,004 Da, which is consistent with the determined size of the pectinesterase protein. The predicted amino acid sequence showed significant homology to pectinesterases from Erwinia chrysanthemi and tomato. In cultures of E. coli clones up to 30% of total pectinesterase activity was transported into the medium. However, no significant pectinesterase activity could be detected in the periplasm.

Amino Acid Sequence↗
PubMed1990

Partitioning of broad-host-range plasmid RP4 is a complex system involving site-specific recombination.

The broad-host-range plasmid RP4 encodes a highly efficient partitioning system (par) that was previously mapped within the 6.2-kb PstI C fragment. The essential functions were assigned to a region of 2.2 kb between fiwA and IS21 (IS8). On the basis of the nucleotide sequence data of the entire par locus and of in vitro and in vivo expression studies, three distinct loci encoding polypeptides of 9, 18, and 24 kDa were identified. Evidence for the expression of another polypeptide was found. A putative divergent promoter was localized in an intergenic region and is suggested to be responsible for transcription of these genes. It was found that the RP4 par region includes a function resolving plasmid dimers. The 24-kDa polypeptide is considered to function as a resolvase, since its predicted amino acid sequence shows homology to sequences of resolvases of the Tn3 family. Furthermore, palindromes present in the intergenic region containing the divergent promoter resemble repeat structures specific for res sites of Tn3-related transposons. However, it was found that dimer resolution itself was not sufficient for stabilization; additional functions, including the other two polypeptides, seemed to play an important role. These results suggested that RP4 contains a complex stabilization system involving resolution of plasmid dimers during cell division, thus ensuring the delivery of at least one copy to each daughter cell.

Amino Acid Sequence↗
PubMed1988

Transformation of Penicillium chrysogenum using dominant selection markers and expression of an Escherichia coli lacZ fusion gene.

An industrial Penicillium chrysogenum strain was transformed using two dominant selection markers, namely the bacterial gene for phleomycin resistance (ble) fused to a fungal promoter, and the acetamidase (amdS) gene from Aspergillus nidulans. Transformation frequencies of up to 20 transformants per microgram of DNA were obtained with the ble system. With the amdS marker the frequency was up to 120 transformants. Cotransformation was very efficient when using amdS as a selection marker. The introduction of pAN5-41B, a plasmid carrying the Escherichia coli lacZ gene fused to the strong glyceraldehyde-3-phosphate dehydrogenase gene (gpd) promoter from A. nidulans, resulted in the formation of blue colonies on XGal plates indicating expression of the lacZ fusion gene in P. chrysogenum. A more detailed analysis of expression levels in several transformants showed that up to 6% of the total amount of soluble protein consists of the beta-galactosidase fusion protein.

Amidohydrolases↗
PubMed1988

Comparison of hypothalamus-pituitary-adrenal axis suppression from superpotent topical steroids by standard endocrine function testing and gas chromatographic mass spectrometry.

We evaluated 38 males who had psoriasis vulgaris for evidence of hypothalamus-pituitary-adrenal axis suppression (HPAS) during treatment with superpotent topical glucocorticosteroids. All men were treated with 49 g per week of either Betamethasone Diproprionate in an optimized vehicle or Clobetasol Proprionate ointment. Three methods used to assess HPAS were compared. Classic 8 a.m. plasma cortisol measurements, urinary-free cortisol, and 17-hydroxycorticosteroid determinations and gas chromatograph-mass spectrometry (GCMS) quantitation of urinary cortisol metabolites were compared. Values for all methods were obtained just prior to therapy and at days 4, 7, 14, and 21 during therapy and at day 28 after treatment was stopped for 7 d. Plasma cortisol measurements correlated well with other measures of HPAS. GCMS determination of urinary cortisol metabolites was slightly more sensitive at detecting HPAS than the other two methods. Persistent HPAS after day 7 was only appreciated by GCMS. Urinary-free cortisol and 17-hydroxycortisol was the least sensitive of the three methods. Analysis of urinary cortisol metabolites by GCMS may be most useful in the monitoring of HPAS resulting from use of topical glucocorticosteroid preparations.

17-Hydroxycorticosteroids↗
PubMed1983

Occurrence of deletion plasmids at high rates after conjugative transfer of the plasmids RP4 and RK2 from Escherichia coli to Alcaligenes eutrophus H16.

The broad host-range IncP-1 plasmids RP4 and RK2 were transferred by conjugation from Escherichia coli to Alcaligenes eutrophus H16. Among the transconjugants selected on media containing tetracycline, a considerable number did not express kanamycin resistance. By comparing restriction patterns of plasmids isolated from a large number of transconjugants a variety of different deletion derivatives were found. All of these possess more or less extended deletions always including parts of the tra 1-region. The plasmids RP4 and RK2, once established in A. eutrophus H16 showed a high stability and it can be concluded that deletion formation is connected with the conjugation process. Evidence is given that degradation of DNA entering an A. eutrophus recipient cell during the conjugative transfer process may be involved in deletion formation. Furthermore, the finding of a small deletion derivative of RP4 lacking the transacting replication function trfB and the entire kil-kor-system may allow the assumption that these gene functions are not essential for replication and maintenance of RP4 in A. eutrophus hosts.

Alcaligenes↗
PubMed1980

Interactions of cardiac glycosides with cultured cardiac cells. II. Biochemical and electron microscopic studies on the effects of ouabain on muscle and non-muscle cells.

Electron microscopic and biochemical studies revealed a salient difference in the response to toxic doses of ouabain by cultured cardiac muscle and non-muscle cells from neonatal rats. Progressive cellular injury in myocytes incubated with 1 . 10(-4)--1 . 10(-3) M ouabain ultimately leads to swelling and necrosis. The morphological damage in myocytes was accompanied by a drastic decrease in 14CO2 formation from 14C-labeled stearate or acetate but not glucose. Neither morphological nor biochemical impairments were observed in non-muscle cells. The interaction between ouabain and the cultured cells, using therapeutic doses of ouabain (i.e., less than 1 . 10(-7) M), was characterized. Two binding sites were described in both classes of cells, one site is a saturable K+-sensitive site whereas the other is non-saturable and K+-insensitive. The complexes formed between the sarcolemma receptor(s) and ouabain, at low concentrations of the drug (e.g., 7.52 . 10(-9) M), had Kd values of 8.9 . 10(-8) and 2.3 . 10(-8) M for muscle and non-muscle cells, respectively. The formation and dissociation of the complexes were affected by temperature and potassium ions.

Animals↗
PubMed1980

Tetronic acid derivatives from Aspergillus panamensis. Production, isolation, characterization and biological activity.

When Aspergillus panamensis, CBS 120.45, was grown on a medium with high carbon and low nitrogen content, it was found to produce six antibiotically active metabolites. All compounds were identified as tetronic acid derivatives; three of them were found to be identical with gregatins A, B, and D, previously reported as metabolites of Cephalosporium gregatum. The other three compounds are new. All six compounds show antibacterial activity towards Gram-negative and Gram-positive bacteria. Five of the antibiotics exhibit inhibitory effects on the macromolecular syntheses in cells of the ascitic form of EHRLICH carcinoma (ECA) of mice.

Animals↗
PubMed1978

A new organ spectrophotometer for sensitive dual-wavelength absorbance measurement and spectral scanning of intact perfused organs.

1) A new spectrophotometer was designed and constructed for application in high sensitivity dual-wavelength absorbance and fluorescence measurement and spectral scanning (non corrected) from intact perfused organs, combining advantages of other instruments described in the literature. 2) The time-sharing principle was applied to gain high stability. All optical and electronic components except the light paths of the wavelength modulation system are common to both wave-lengths. For this purpose the logarithmic stage was introduced before demodulation. Stability is about 0.001 A/h and noise about 0.001 A. 3) The performance of the instrument with a biological object, the isolated perfused rat liver, is demonstrated in the dual-wavelength mode and in the spectral scanning mode. Limitations in stability and in time resolution in such an application result from the properties of the biological object, not from the instrument.

Aminopyrine↗
PubMed1976

[Obese patients in obstetrics].

The results of two studies about the course of pregnancy and delivery in adipose women in our hospital are combined and discussed. We found a higher rate of EPH-gestosis in overweight patients. The frequency of Cesarean section was increased. Belated uterine involution post partum is more frequent in adipose women, also the occurrence of urinary tract infections. There is a significant increase in perinatal mortality, mainly due to an increase in still-born. Pneumonia due to aspiration and birth traumata occur more frequently as well and endanger the children.

Female↗