PubMed Health⌕ Search

Biomedical subjects

R Lenz

Publications and source records attributed to R Lenz.

14 recordsLinked to original sources
PubMed1995

Purification and properties of codeinone reductase (NADPH) from Papaver somniferum cell cultures and differentiated plants.

Codeinone reductase (NADPH), which catalyzes the stereospecific reduction of (-)codeinone to (-)codeine, was detected and purified to electrophoretic homogeneity from a cytosolic fraction of Papaver somniferum L. cell cultures. The purification involved ammonium sulfate precipitation (40-80%), affinity chromatography (matrex red A), gel filtration (fractogel TSK HW 55S), affinity chromatography (fractogel TSK AF Blue), ion-exchange chromatography (DEAE-Sephacel) and native PAGE. The purified codeinone reductase was found to be a monomeric protein of 35 +/- 1 kDa that is highly substrate-specific, reducing only the C6 oxo group of codeinone and morphinone as well as a few analogues. The physiological forward reaction has a pH optimum at 7.0, the reverse reaction at 9.1. The temperature optimum is at 40 degrees C and the isoelectric point (p1) at 4.4. The apparent Km values (forward reaction) for codeinone and NADPH are 23 microM and 168 microM, respectively. Using capsule tissue of differentiated P. somniferum plants as an enzyme source, two codeinone reductase (NADPH) isoenzymes were detected and purified to homogeneity. These isoenzymes could not be separated for characterization and showed slightly different kinetic features (Km values: codeinone 9 microM; NADPH 81 microM) compared with the cell culture enzyme.

Alcohol Oxidoreductases↗
PubMed1991

[The laboratory animal management system--an animal housing management data-processing system].

The Laboratory Animal Management System (LAMS) is a flexible, multi-purpose animal house management tool. It has a decentralized structure and was developed using UNIFACE and Oracle-database software. The multiuser LAMS system runs on a Micro-Vax computer and can be accessed from several workstations. LAMS has been designed to manage the following functions: animal study details; animal procurement; book keeping and follow-up; amendments; update of data; inquiries; statistics and numerous additional tasks. LAMS is a user-friendly interactive system which does not allow input of incorrect data and can be operated by staff with very little computer experience. The system fully complies with German legal requirements and is becoming an increasingly important tool for routine management of animal house facilities and animal experimentation.

Animals↗
PubMed1991

Streptokinase immunogenicity in thrombolytic therapy for acute myocardial infarction.

The major drawback in implementing thrombolytic therapy with streptokinase in cases of acute myocardial infarction (AMI) stems from its antigenicity. To evaluate the dimensions of this problem, the immune response following thrombolytic therapy with streptokinase was prospectively studied in 16 patients with AMI. Streptokinase was given to 12 patients once and to 4 patients twice within 4-14 days. No clinical immune responses were observed following treatment. The specific antistreptokinase immune responses subsequent to streptokinase administration were monitored. The cellular immune response, reflected by the 3H-thymidine uptake of streptokinase-stimulated peripheral blood mononuclear cells, was three times higher than that of the controls. The antistreptokinase circulating IgG antibody level, measured by an enzyme-linked immunosorbent assay, was 8 times higher than that of the controls. No antistreptokinase circulating IgE antibodies could be detected and no decrease in complement concentration was noted. The profile and magnitude of the immune response of patients who had received two treatments were similar to those of patients who had received a single treatment only. Our data suggest that thrombolytic therapy with streptokinase in AMI elicits a characteristic profile of antistreptokinase immune responses, in vitro, not necessarily associated with parallel clinical immune responses. An early repeat treatment with streptokinase was not accompanied by clinical or exacerbated in vitro immune responses.

Antibody Formation↗
PubMed1990

Stimulation of human T cell colony growth by a lymphocyte colony enhancement factor derived from lymphocyte subpopulations.

Blood mononuclear cells (MNC) develop into T cell colonies when the cells are sensitized with PHA and seeded in a two-layer soft agar system. Conditioned medium (CM) derived from MNC enhanced lymphocyte colony formation when it was added to the culture system. CFU-TL appear to be stimulated into colony formation by molecules secreted by lymphocyte subpopulations contained in the seeded cells. In this study, human peripheral blood MNC were fractionated by a battery of techniques into adherent, E+, CD4+, CD8+, B and null cells. CM was prepared from each of the subpopulations and its effects on T cell colony growth assayed. All the lymphocyte subpopulations were found to generate lymphocyte colony enhancement factor (LCEF). After several purification procedures, CM prepared from CD4 and CD8+, displayed LCEF activity corresponding to proteins of molecular weight 30-40 and 100-140 kD.

Antigens, CD↗
PubMed1988

Jakarta kampung morbidity variations: some policy implications.

Urban growth in the developing world is likely to be accompanied by health problems in crowded zones where services are not available. Geographical analyses of aggregated data may prove interesting, but reliability and utility of spatial correlations are greater when microscale data are acquired. In this study data for households in 11 Jakarta neighborhoods were collected in interviews. Malaria and diarrheal disease patterns have been correlated with environmental and socioeconomic variables at the household level. Several environmental characteristics seem to be closely associated with the incidence of malaria and diarrheal diseases.

Diarrhea↗
PubMed1985

Possible role of gangliosides in the interaction of colony-stimulating factor with granulocyte-macrophage progenitor cells.

Our previous studies have shown that preincubation of murine bone marrow (BM) cells with cholera toxin (CT) or with its B subunit inhibited their responsiveness to colony-stimulating factor (CSF). Because ganglioside GM1 is a component of the CT receptor, the present study was undertaken to determine whether gangliosides interact with CSF and therefore might play a role in the binding sites for CSF. Preincubation of CSF with increasing concentrations of bovine-brain mixed gangliosides resulted in decreased numbers of colonies of BM-derived granulocyte-macrophage progenitor cells (CFU-C) in soft agar. The inhibitory effect of the gangliosides could be reduced by increasing the concentrations of CSF. Evidence for direct binding of CSF to gangliosides was obtained by affinity chromatography of CSF on gangliosides-sepharose beads. CSF activity was retained on the beads and could be eluted with 6 M guanidine HCl. Four different individual gangliosides (GM1, GM2, GD1a, GT1b) were tested for their inhibitory effect on CSF-induced clonal growth of CFU-C. GM1 was the most effective with a 50% inhibition (I50) of clonal growth at a concentration of 15 microM. while the other three gangliosides had slight inhibitory activity (I50 at a concentration greater than 100 microM). In addition, preincubation of BM cells with rabbit anti-GM1 antibodies before addition of CSF reduced the clonal growth of CFU-C to 45%. These data indicate that GM1 interacts with CSF and suggest that gangliosides may play a role in the interaction of CSF with CFU-C and that the binding site for CSF on the surface of these cells might either consist of or contain this ganglioside.

Animals↗
PubMed1982

Inhibition by cholera toxin of clonal growth of murine granulocyte/macrophage progenitor cells in soft agar cultures.

Proliferation in vitro of the committed granulocyte-macrophage progenitor cell (CFUC) is inhibited by cholera toxin (CT) in a dose-dependent manner. This inhibition is reduced and counteracted by higher doses of colony stimulating factor (CSF), an obligatory growth stimulator of CFUC. Mixing of CT with its specific receptor, the monosialoganglioside, GM1, before exposure to bone marrow (BM) cells, blocks the toxin's effect, and a restoration of colony formation is achieved. A dose-dependent inhibition of CSF-induced colony formation is also observed in the presence of choleragenoid, the B subunit of the toxin which binds to the specific receptor on the cell surface, but is biologically inactive. Incubation of BM cells with CT prior to cloning in soft agar cultures supplemented with CSF inhibits clonal proliferation of CFUC, whereas a brief in vitro exposure of BM cells to CSF prior to CT protects the cells against subsequent CT inhibition. The ability of CT to inhibit the CSF-induced clonal proliferation of CFUC and the effectiveness of CSF in reducing and even counteracting CT inhibition suggests that CT, by binding to BM cells through the B subunit, might either directly or indirectly interfere with the stimulatory activity of CSF upon its target cells.

Animals↗
PubMed1976

[Suitability test of various food mixtures for breeding and rearing of beagle dogs. 2nd Communication: Methods and results of feeding experiments of the Mannheim team (author's transl)].

A comparison of 3 commercially available dog foods (Ssniff C, Altromin H, Altromin HW) with 2 newly formulated dog food mixtures was carried out with regard to breeding, rearing and maintenance of Beagle dogs. No significant differences were found between the individual feeding groups with regard to the fertility and breeding ability of the bitches. All the foods supplied the requirements for energy, nutrients and feed additives in the rearing and maintenance of the dogs. The parameters used for the assessment, such as body weight, daily gain, daily food consumption and feed efficiency, were satisfactory for all food groups and were partially reproduceable. If the consumption of food, energy and nutrients per kg body weight are calculated and are related to the rearing results obtained then inconsistencies occur which can only be explained by differences in digestibility of the individual food components, and these underline the need for digestibility tests in dogs. The 2 newly formulated foods compared favourably with the other food stuffs and fulfilled the requirements for better standardised food mixtures. Further experiments will investigate the effects on the morphological, haematological and clinico-chemical characteristics. A comparison of different age groups confirmed the data in the literature which indicates that younger animals have a higher requirement for energy and nutrients per kg body weight than older animals. Results that have not yet been explained are the findings that the consumption of food, and thus of energy and nutrients, per kg body weight in younger male animals is lower than that of the female animals of the same age to a highly significant degree.

Age Factors↗
PubMedDate not supplied

Evaluation of methods for shaded surface display of CT volumes.

There are several ways to compute a shaded surface display of radiological 3D density volumes. In this paper we evaluate 12 methods which are different combinations of principles for detection of the surface to be displayed (gray-value threshold, gradient threshold, zero-crossing of 2nd derivative), localizing this surface in space (grid-point accuracy, subvoxel accuracy) and finally estimating the direction of the surface normal (from the gradient in the 2D depth image, from the gradient in the 3D-volume). The best quality is obtained by zero-crossing detection, subvoxel localization, and 3D-gradient orientation.

Data Display↗