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M Conradi

Publications and source records attributed to M Conradi.

12 recordsLinked to original sources
PubMed2002

Structure and dynamics of freely suspended film of the smectic-C*alpha phase in an external transverse electric field.

We present a theoretical analysis of static and dynamic properties of freely suspended films of the smectic-C*alpha phase in an external electric field, applied along the smectic layers. The analysis is performed within the "clock" model, where the interactions up to next-nearest neighbors are considered. The calculated critical electric field for the unwinding of the smectic-C*alpha phase is of the order of several 100 V/mm and strongly depends on the interlayer interactions. The calculated relaxation rates of the eigenfluctuations of a system of N layers are in the kilohertz range for phase fluctuations and several megahertz for amplitude fluctuations.

Journal Article↗
PubMed1994

Synthesis of fluorescent derivatives of 7-methylguanine through reaction with 2-aryl-substituted malondialdehydes: analysis by HPLC with fluorescence detection.

Fluorescent derivatives of 7-methylguanine were prepared through reaction with 2-aryl-substituted-malondialdehydes and analysed by reversed-phase HPLC with fluorescence detection. Reaction of carbons 1 and 3 of the malondialdehyde molecule at the N1 and N2 positions of 7-methylguanine yielded fluorescent tricyclic structures. Two novel fluorescent derivatives of 7-MeG were obtained, namely, 7-(3,4-dimethoxyphenyl)-10-oxo-1-methyl-9,10-dihydropyrimido[1,2- alpha]purine (yield 15-34%) and 7-(1-naphthyl)-10-oxo-1-methyl-9,10- dihydropyrimido[1,2-alpha]purine (yield 56-70%) after reaction with 3,4-dimethoxyphenylmalondialdehyde and 1-naphthylmalondialdehyde, respectively which were characterized by IR, NMR, MS and UV and fluorescence spectroscopy. The fluorescence intensity of the derivatives was found to be 10-20-fold higher than the intrinsic fluorescence of 7-methylguanine. Concentration versus fluorescence intensity curves exhibit linearity in the picomole to nanomole range. The 2-aryl-substituted malondialdehydes were used to analyse the concentration of 7-methylguanine in neutral hydrolysates obtained from calf thymus DNA samples alkylated with dimethyl sulfate. The results obtained indicate their potential as reagents for the analysis of alkylated guanines in biological samples. Molecular modeling calculations were carried out to generate lowest energy spatial configurations. The results obtained indicated that the aryl-substituents on the malondialdehyde moiety do not lie in the same plane as the tricyclic moiety of the fluorescent derivatives with implications for their fluorescence properties.

Chromatography, High Pressure Liquid↗
PubMed1994

Development of a 32P-postlabelling method for the analysis of 2'-deoxyguanosine-3'-monophosphate and DNA adducts of methylglyoxal.

A 32P-postlabelling assay was developed for the analysis of adducts arising from the reaction of 2'-deoxyguanosine-3'-monophosphate with the 1,2-dicarbonyl compound methylglyoxal, a major mutagen in several foodstuffs, in particular, instant and brewed coffee. The 32P-postlabelling reaction was optimized by testing various parameters such as the kinetics of phosphorylation by T4 polynucleotide kinase, substrate concentration-dependent labelling efficiency and the concentration of the various ingredients of the phosphorylation reaction. The sensitivity to the 3'-monophosphate dephosphorylation activity of nuclease P1 was also studied. Four isomeric reaction products were separated by HPLC, structurally characterized and identified as 3-(2'-deoxy-beta-D-erythro-pentafuranosyl)-6,7-dihydro-6,7-dihydro xy-6- methylimidazo[2,3-b]purine-9(8H)one. The same adducts could be detected from calf thymus DNA that had been reacted in vitro with methylglyoxal. DNA adducts were isolated after enzymatic digestion to mononucleotides followed by nuclease P1 digestion of normal nucleotides. The total level of methylglyoxal-DNA adducts obtained was 5.7 +/- 1.7 (n = 15) adducts/10(6) nucleotides. The 32P-postlabelling method was further validated by the detection of adducts of methylglyoxal in DNA from freshly isolated and stimulated human lymphocytes exposed in vitro. The concentrations of the adducts detected in these samples were 8.2 +/- 0.9 (n = 3) adducts/10(7) nucleotides and 1.5 +/- 0.1 (n = 3) adducts/10(6) nucleotides after treatment with 1.5 and 3.0 mM methylglyoxal respectively.

Animals↗
PubMed1986

Pulmonary reaction associated with transfusion of plasma containing anti-5b.

A patient developed an acute respiratory distress syndrome with lung infiltrates during a transfusion of plasma. The transfused plasma was shown to contain a potent leucocyte agglutinating antibody of IgG type with anti-5b specificity, reactive with the patient's cells. A review of the literature on similar transfusion-related syndromes showed an association with more of less well-defined white cell antibodies, mainly in the donors' plasma. The majority of donors were multiparous women. The anti-5b in our donor was demonstrated only by granulocyte agglutination technique, as previously described antibodies in the five system. A long incubation procedure (20-25 h) seemed to be optimal for granulocyte agglutination.

Aged↗
PubMedDate not supplied

[Tocolysis with fenoterol suppositories--a comparison with oral administration of fenoterol tablets].

A new application form of fenoterol (Partusisten) as 15 mg suppositories from Boehringer Ingelheim was tested for its tocolytic effect, tolerance and the main side effects under usual clinical conditions in a prospective study in 50 pregnant patients with premature labour in 24-36th week of gestation. During one week's treatment 25 pregnant women received 3 to 4 15 mg fenoterol suppositories and 25 patients 6 to 8 5 mg fenoterol tablets. Beginning on the second day of treatment until the end of therapy in both groups a reduction of the uterine activity of at least 50 percent was achieved. The uterine relaxant effect was sufficient until 3 to 4 hours after the application of fenoterol tablets and 6 to 8 hours after the application of fenoterol suppositories. Side effects were mainly limited to cardiovascular complaints, restlessness and tremor, and we found no significant difference between tablets and suppositories. The maternal heart rate reached its highest level on the second day of treatment. Fenoterol suppositories can be recommended in all cases, where an oral tocolytic therapy is not possible e.g. in cases of vomiting or before operations. Here the application of fenoterol suppositories can replace in some cases the intravenous infusion of fenoterol.

Administration, Oral↗
PubMedDate not supplied

[Various aspects of Parkinson syndrome in the aged].

The author defines this syndrome with symptoms and diagnostics and describes its aetiopathogenesis, pathological and anatomical changes in the patient, course, treatment and epidemiology as well as primary and secondary measures to prevent it.

Aged↗