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Biomedical subjects

W Schumann

Publications and source records attributed to W Schumann.

At least 73 records · Page 4Linked to original sources
PubMed1987

In vivo formation of gene fusions in Pseudomonas putida and construction of versatile broad-host-range vectors for direct subcloning of Mu d1 and Mu d2 fusions.

The Mu d1 and Mu d2 prophages were integrated into the conjugative broad-host-range plasmid R751. The two plasmids were then transferred into Pseudomonas putida, and derivatives carrying intact Mu prophages were recovered. After induction of Mu at 42 degrees C, both operon and gene fusions were observed on 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal) plates. Broad-host-range vectors were constructed which allow direct cloning of both operon or gene fusions and their analysis in Escherichia coli and P. putida. By using one of these vectors, two operon fusions were isolated from the P. putida chromosome and comparatively analyzed in E. coli and P. putida.

Bacteriophages↗
PubMed1987

[Pharmacokinetics of 14 beta-, 15 beta-methylenestratriene STS 593 after one-time and multiple administrations to beagles].

Disposition and excretion of the estrogen derivative STS 593 [1,3-methoxy-14 beta,15 beta-methylenestra-1,3,5(10)-triene-17 beta-ol] with antifertility activity were investigated in Beagle dogs after single and repeated administration of the tritium-labelled compound. The plasma concentration vs. time courses of total radioactivity (TRA) and of the parent drug alone were estimated in conscious animals simultaneously with the urinary and fecal excretion data. From this the basic pharmacokinetic parameters were calculated and experimentally confirmed by multiple-dosing data. STS 593 differs from estradiol with respect to its higher bioavailability after oral administration; it amounts to 34-62% depending on the administration formulation. The compound is metabolized rapidly. The accumulation factor of TRA resulting from a multiple once-a-day dose regimen of STS 593 was quantified with 3.1.

Animals↗
PubMed1986

Model systems for pharmacokinetics of steroid drugs subject to enterohepatic circulation.

A number of drugs including steroid hormones undergo enterohepatic circulation (EHC) which influences the drug disposition parameters. EHC of drugs leads to prolonged drug exposition which may enhance the risk of liver incompatibility. The extent of EHC expressed by the reabsorption rate of a given drug is of interest from the clinical and toxicological point of view. A two-compartment model with an additional time lag was realized by a hybrid computer system to study the influence of EHC on the shape of plasma concentration-time profiles and pharmacokinetic parameters. Reabsorption rates of potential steroid drugs were calculated by model-simulation and the results compared with the experimentally found ones. Although the lag time model is only a simplified approximation to the underlying physiological processes it reflects sufficiently the pharmacokinetic profile of steroid drugs subject to EHC.

Animals↗
PubMed1983

Mapping of binding sites for Mu repressor and ner product within the left-end EcoRI. C fragment of the Mu genome.

Bacterial cells containing the ner gene of phage Mu inserted into pBR322 express a binding activity with specificity for the left-end EcoRI.C fragment of Mu DNA. Crude extracts containing either Mu repressor or ner protein have been used to localize binding sites on TaqI subfragments of the EcoRI.C fragment. There are at least 3 distinct binding sites for the Mu repressor and 1 binding site for the ner protein on the EcoRI. C fragment. The possible biological function of these binding sites is discussed.

Bacteriophage mu↗
PubMed1983

Studies on pharmacokinetics of STS 557 in animal species and man.

Following oral and i.v. administration of [14 alpha, 15 alpha-3H]-STS 557 to beagle dogs, baboons, rats and female volunteers, plasma level courses of total radioactivity and STS 557, and radioactivity excretion in urine and feces have been investigated. Bioavailability of orally administered STS 557 was found to be 80--90% in man and beagle dog, 70--80% in baboon and rat. Concerning the systemic availability following oral administration of equivalent doses, the following order was established: beagle dog greater than man greater than baboon greater than rat. Equilibrium dialysis indicates species differences in plasma protein binding and a considerable part of STS 557 to be present in plasma unbound. STS 557 is rather rapidly eliminated from the plasma compartment of all species investigated with half lives less than or equal to 10 h. As an additional time parameter of pharmacokinetics the "mean residence time" was used. Urinary excretion of STS 557 metabolites is dominant in all species, including the rat. In contrast to the great part of STS 557 in plasma total radioactivity, only small amounts of unchanged STS 557 are excreted in urine. First results of current studies in rabbits are presented, too.

Animals↗
PubMed1981

Glycopeptides (FSH, LH, TSH, prolactin) and glycoproteins in patients with genitourinary cancer.

The present investigation has analyzed 249 patients suffering from urogenital cancer in respect to aberrant concentration of prolactin, TSH, LH and FSH. A simultaneous pattern of acute phase reactants (alpha 1-glycoprotein, alpha 1-antitrypsin, beta 2-glycoprotein and haptoglobin) was related to the content of these hormones. Abnormal results of prolactin and TSH were present in 30% of all patients, whereas frequent aberrations of alpha 1-acid glycoprotein and alpha 1-antitrypsin were detected in 60--80%. Acute phase reactants changed to more pathological values when correlated to elevated prolactin.

Adult↗
PubMed1980

Toxicological studies of liver cells by microspectrofluorometry.

The kinetics of xenobiotic biotransformation was measured in single, isolated, perifused liver cells with microspectrofluorometry using highly sensitive photodetection systems. A program of further applications to biochemical toxicological problems is presented.

Animals↗
PubMed1980

Plasmid vectors derived from phage Mu allow direct selection of transformants containing cloned HindIII and PstI fragments.

The vector plasmids pKN001 and pKN80 both contain the EcoRi.C fragment of E.coli phage Mu DNA which codes for a killing function that is efficiently expressed upon transformation into Mu-sensitive bacteria. By in vitro insertion of HindIII fragments at the single HindIII site of pKN80 or of PstI fragments at the single PstI site of pKN001 the killing function is inactivated. The resulting plasmids have a selective advantage over the religated vector when transformed into Mu-sensitive bacteria. More than 90% of the transformations contain hybrid plasmids. These results show the usefulness of Mu DNA containing plasmids pKN001 and pKN80 as vectors that allow the direct selection for recombinant plasmids.

Bacteriophage mu↗
PubMed1980

[Temperature dependence of courtship in male guppies, Poecilia reticulata Peters (Pisces, Cyprinidae)].

In poikilothermal animals, modes of behaviour as well as other physiological functions are dependent on the environmental temperature. Individual adaptation can decrease or cancel out this dependency. In experiments involving abrupt and slow temperature changes, we were able to prove temperature compensations and stress effects in the courting behaviour of the male Poecilia reticulata.

Aggression↗
PubMed1979

Construction of an HpaI and HindII plasmid vector allowing direct selection of transformants harboring recombinant plasmids.

The construction of the vector plasmid PKN80 is described, which can be used as HpaI or HindII cloning vehicle with direct selection on transformants harboring hybrid plasmids. pKN80 carries the EcoRI.C fragment of phage Mu DNA coding for a killing function which is efficiently expressed upon transformation of pKN80 into Mu-sensitive bacteria. Cloning of DNA fragments at the single HpaI site of pKN80 results in insertional inactivation of the killing function. Whereas religated pKN80 molecules yielded only a few transformants, the transformation efficiency had been increased by a factor of at least ten when HpaI fagments of lambda DNA were added to the linearized vector prior to ligation. More than 90% of the transformants tested containted hybrid plasmids.

DNA Restriction Enzymes↗
PubMed1979

Origin and binding specificity of protein(s) coded for by Mu prophages.

Crude extracts of bacteria lysogenic for temperature phage Mu contain proteins that retain specifically Mu DNA on nitrocellulose filters. The amount of binding protein is directly proportional to the number of Mu prophages per E. coli genome. Specificity of the binding reaction could be demonstrated by using heterologous DNAs as substrate and by a competition experiment. By using hybrid plasmids containing different amounts of the immunity end and extending to various degrees into MuDNA, it was found that the binding activity is coded for by the left 1,000 nucleotide-pair HindIII fragment. When using these hybrid plasmids as binding substrate, two different binding sites for the immunity product were detected. Joining of the MucI gene to the left lambda early promoter resulted in increased production of immunity protein at elevated temperature. A possible explanation for the relatively low amounts of immunity protein in all of the different strains studied is discussed.

Bacteriophage mu↗
PubMed1979

In vitro constructed plasmids containing both ends of bacteriophage Mu DNA express phage functions.

The construction of a plasmid carrying the right end PstI . B fragment of bacteriophage Mu DNA and of plasmids containing in addition the left end EcoRI.C fragment of Mu DNA into the vector pBR322 is described. Inversion of the G segment still occurs in all these plasmids. By marker rescue and complementation experiments the right PstI cleavage site was located to the left of gene Q. The composite plasmids inheriting also the left end EcoRI fragment of Mu DNA express both the immunity and killing functions of Mu and direct the in vitro synthesis of presumably Mu-specific polypeptides. These results demonstrates that Mu-specific functions can be analyzed from cloned fragments.

Coliphages↗
PubMed1979

Cloning and biological characterization of the immunity region of Escherichia coli phage Mu.

The construction of three hybrid plasmids containing different parts of the left or immunity and end of phage Mu DNA is described. The recombinant plasmids pKN05 and pKN54 carry the HindIII.C and PstI.C fragments of Mu DNA, respectively. Neither of these plasmids expresses the killing function. Moreover, they do not allow plating of superinfecting Mu phages. Plasmid pKN62 harbors the fragment located in between the left PstI and EcoRI cleavage sites on Mu DNA, allows plating of superinfecting Mu phages, but does not express the killing function. These data suggest that the gene coding for the killing function is either positively regulated by a product from the EcoRI.C fragment, or the killing function requires a second product not coded for by pKN62. Mu Vir A- or Mu Vir B- phages are able to grow on bacteria harboring the recombinant plasmid pKN001 which carries the left and EcoRI-C fragment of Mu DNA. This indicates that the superinfecting phages can induce the corresponding gene functions from pKN001. No such induction could be detected in cells harboring the hybrid plasmids pKN05, pKN54 or pKN62.

Coliphages↗
PubMed1978

Cloning of a restriction fragment of phage mu DNA coding for early functions.

The DNA of an E. coli K12 strain harboring ten wildtype Mu prophages was restricted with endonuclease EcoRI, and the fragments ligated into the plasmid vector pMB9. Upon transformation of a strain carrying a heat inducible (Mu cts62) prophage, one temperature-resistant transformant was isolated. This transformant strain harbors the hybrid plasmid pKN001, containing the EcoRI.C fragment of Mu DNA as shown by restriction and heteroduplex analysis. Stable transformants of pKN001 are immune to superinfection with phage Mu. Transformation of Mu sensitive bacteria with pKN001 results in killing of the recipients (10(-4) surviving bacteria). The killing function is not expressed upon transformation of Mu-immune (lysogenic) bacteria.

Cell Transformation, Viral↗
PubMed1977

A Salmonella typhimurium endonuclease that converts native DNA to fragments of about 8 X 10(5) daltons.

Crude extracts of Salmonella typhimurium were found to contain an endonuclease that degraded double-stranded linear DNA from bacteria and phages to fragments with a molecular weight of about 8 X 10(5). The nuclease did not have an absolute requirement for Mg2+. One discrete intermediate product had a molecular weight of 6-6 X 10(6). Extracts from two different mutants were tested: one completely lacked the endonuclease activity (strain DB5575), and the other showed an absolute requirement for Mg2+ (strain 4543). No biological role has yet been found for this endonuclease of S. typhimurium.

Bacteriophages↗