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Biomedical subjects

R D Schmid

Publications and source records attributed to R D Schmid.

118 records · Page 7Linked to original sources
PubMed1979

[Light sensitivity of creatine kinase in control sera].

The light sensitivity of creatine kinase in different control sera was investigated. Control sera were dispensed into reaction vessels, then exposed for 4 h at 25 degrees C to a light source equivalent in intensity to normal laboratory illumination. In 12 out of 22 control sera, the catalytic concentration of the creatine kinase fell by 25-63%. Under the same conditions, in patient sera, creatine kinase is stable. In the "light sensitive" control sera, the instability of the enzyme increased with the intensity of illumination. When exposed to sunlight creatine kinase was unstable in all the investigated control and patient sera. The addition of mercaptoethanol stabilized the creatine kinase in "light sensitive" control sera. The reason for the different light sensitivity of different control sera is not known.

Creatine Kinase↗
PubMed1978

[Interference by glutathione reductase in the "CK-MB-inhibition-test": elimination of the catalytic activity of glutathione reductase by anti-glutathione reductase (author's transl)].

Glutathione reductase interferes in the determiniation of creatine kinase-MB by the "CK-MB-inhibition-test". In 36 out of 55 serum samples with normal and elevated catalytic activities of creatine kinase, "negative" values greater than 14 U/l were obtained for the creatine kinase-MB. This interference by glutathione reductase is avoided by preincubation of the serum samples for 5 min with anti-glutathione reductase.

Catalysis↗
PubMed1977

Excretion of galactitol in the urine of heterozygotes of both forms of galactosemia.

In 36 heterozygotes with Gal-1-PUT deficiency and 3 heterozygotes with galactokinase deficiency galactitol (and galactose) was determined in the urine 2 and 4 h after an intravenous injection of 350 mg galactose/kg body weight (maximum dosis in adults 16 g). For the sake of comparison 10 healthy children and 5 adults, also 4 homozygotes with Gal-1-PUT deficiency and one sick child with galactokinase deficiency were included in this study. The heterozygotes with Gal-1-PUT deficiency demonstrated the same galactitol excretion as the healthy probands, while heterozygotes with galactokinase deficiency excreted a four-fold higher quantity of galactitol than the healthy and heterozygous probands of Gal-1-PUT deficiency. The child with the galactokinase deficiency excreted galactitol for a period of more than 24 h. These results are discussed.

Galactose↗
PubMed1977

[Familial translocation 3/22 MAT with partial trisomy 3q (author's transl)].

Two mentally retarded brothers with partial trisomy 3q show clinically similar malformations and deformities : dwarfism, bushy eyebrows, eversion of the nostrils, low inserted ears, high palate, microgeny, low hair insertion, short and broad hands with proximally inserted thumbs, clinodactylia of the 5th finger, syndactylies, mostly arch patterns on the digital pulps, muscular hypotonia, joint relaxation and cryptorchism. Both children had fits of convulsions. The younger boy showed, moreover, a perception deafness. The mother, the maternal grand-mother as well as the phenotypically normal sister of the patients revealed a balanced translocation 3/22 with a karyotype : 46,XX,t(3;22) (q25;p11).

Abnormalities, Multiple↗
PubMedDate not supplied

Interactions between aldehyde derivatives and the aldehyde binding site of bacterial luciferase.

The interaction of triazine aldehydes with the aldehyde binding site of bacterial luciferases was investigated using a series of triazine aldehydes with different aldehyde chain length, and substituents on the s-triazine ring. Substrate activity was determined using luciferase from Photobacterium fischeri and Vibrio harveyi in a dithionite-based luciferases assay. The chain length optimum was determined for two triazine aldehyde classes to be C-10 and C-11, respectively. Only the substrate activity of 10-(4-chloro-6-methylthio-s-triazine-2-yl)aminodecanal (5) was as high as n-decanal, the reference aldehyde. All other triazine derivatives reduced light emission, probably by hindered binding of the substrates. The degree of activity reduction correlated with the volume of the triazine ring moiety. The triazine moiety volume of compound 5 was estimated to be 200 x 10(-30) m3. Triazine aldehydes which showed reduced light emission had an estimated volume of 228 x 10(-30) m3 or greater. All triazine aldehydes showed approximately 10-fold lower activities for Vibrio harveyi than for Photobacterium fischeri luciferase. Substrate specificity was the same for both luciferases. A schematic superposition of quinone aldehydes and triazine aldehydes which showed substrate activities equivalent to n-decanal, indicated potential interaction sites of aldehyde substrates with the aldehyde binding site of bacterial luciferases. The in vivo relevance of the results is discussed.

Aldehydes↗
PubMedDate not supplied

Optical biosensor investigation of interactions of biomembrane and water-soluble cytochromes P450 and their redox partners with covalently immobilized phosphatidylethanolamine layers.

A phospholipid-containing biochip was created by covalently immobilizing phospholipids on the optical biosensor's aminosilane cuvette and employed to monitor the interactions of the membrane and water-soluble proteins in cytochrome P450-containing monooxygenase systems with planary layers of dilauroylphosphatidylethanolamine (DLPE) and distearoylphosphatidylethanolamine (DSPE), differing in acyl chain length. It was shown that the full-length membrane proteins-cytochrome P4502B4 (d-2B4), cytochrome b5 (d-b5) and NADPH-cytochrome P450 reductase (d-Fp)-readily incorporated into the phospholipids. The incorporation was largely due to hydrophobic interactions of membranous protein fragments with the phospholipid layer. However, electrostatic forces were also but not always involved in the incorporation process. They promoted d-Fp incorporation but had no effect on d-b5 incorporation. In low ionic strength buffer, no incorporation of these two proteins into the DSPE lipid layer was observable. Incorporation of d-b5 into the DLPE layer was abruptly increased at temperatures exceeding phospholipid phase transition point. Incorporation of d-2B4 was dependent on its aggregation state and decreased with increasing protein aggregability. Water-soluble proteins either would not interact with the phospholipid layer (adrenodoxin) or would bind to the layer at the cost of only electrostatic (albumin) or both electrostatic and hydrophobic (P450cam) interactions.

Biosensing Techniques↗
PubMedDate not supplied

Reporter gene bioassays in environmental analysis.

In parallel to the continuous development of increasingly more sophisticated physical and chemical analytical technologies for the detection of environmental pollutants, there is a progressively more urgent need also for bioassays which report not only on the presence of a chemical but also on its bioavailability and its biological effects. As a partial fulfillment of that need, there has been a rapid development of biosensors based on genetically engineered bacteria. Such microorganisms typically combine a promoter-operator, which acts as the sensing element, with reporter gene(s) coding for easily detectable proteins. These sensors have the ability to detect global parameters such as stress conditions, toxicity or DNA-damaging agents as well as specific organic and inorganic compounds. The systems described in this review, designed to detect different groups of target chemicals, vary greatly in their detection limits, specificity, response times and more. These variations reflect on their potential applicability which, for most of the constructs described, is presently rather limited. Nevertheless, present trends promise that additional improvements will make microbial biosensors an important tool for future environmental analysis.

Biological Assay↗
PubMedDate not supplied

[Photoreduction of flavocytochrome P450 2B4].

It was shown that noncovalent complexes of riboflavins and cytochrome P450 2B4 (flavocytochrome P450 2B4) can be used for photoinduced intramolecular electron transfer between the isoalloxazine cycle of flavins and the cytochrome P450 2B4 heme. The measurement of the photocurrent generated by photoreduction of noncovalent flavocytochrome P450 2B4 was carried out. It was found that, in the presence of typical substrates for cytochromes P450, the cathode photocurrent generated by both riboflavin and a mixture of riboflavin with cytochrome P450 decreases. A comparison of photocurrents in the presence and absence of substrates enabled one to register xenobiotics in solutions and use the photosensitivity of artificial flavocytochrome P450 for the determination of xenobiotic concentration. It was demonstrated that artificial flavocytochromes may serve as molecular amplifiers of the photocurrent generated upon the reduction of flavins. The introduction of flavin residues into the cytochrome P450 molecule transformed this hemoprotein into a photoreceptor and a photodiod and, in addition, into a photoactivated enzyme.

Aryl Hydrocarbon Hydroxylases↗