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Biomedical subjects

P Novak

Publications and source records attributed to P Novak.

At least 73 records · Page 4Linked to original sources
PubMed1986

Localization and purification of two enzymes from Escherichia coli capable of hydrolyzing a signal peptide.

The signal peptide generated during the maturation of prolipoprotein by the purified prolipoprotein signal peptidase can be isolated in substrate amounts (Dev, I. K., and Ray, P. H. (1984) J. Biol. Chem. 259, 11114-11120). This signal peptide is degraded predominantly from the carboxyl terminus by cell-free extracts of Escherichia coli. The signal peptide is degraded (at least 300-fold) more rapidly than other cellular proteins in E. coli. Greater than 90% of the signal peptide hydrolase activity is localized in the cytoplasm. Two enzymes from the cytoplasmic fraction responsible for the degradation of the signal peptide have been identified and purified to near homogeneity. The major activity is associated with a monomeric protein with a molecular weight of 68,000 (S.E. 3,400) as determined by gel filtration and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This enzyme appears to be similar to the oligopeptidase (Vimr, E. R., Green, L., and Miller, C. G. (1983) J. Bacteriol. 153, 1259-1265) that hydrolyzes N-acetyl tetra alanine. The second protein represents approximately 5% of the total cytoplasmic activity and has been shown to be a dimer with a monomer molecular weight of 81,000 (S.E. 5,300). This enzyme is similar to protease So (Chung, H. C., and Goldberg, A. L. (1983) J. Bacteriol. 154, 231-238).

Chromatography, DEAE-Cellulose↗
PubMed1985

Vitreous stimulates proliferation of fibroblasts and retinal pigment epithelial cells.

In proliferative vitreoretinopathy, retinal pigment epithelial cells and glial cells migrate into the vitreous, proliferate, and assume characteristics of myofibroblasts. The addition of vitreous to the culture media stimulates the proliferation of porcine retinal pigment epithelial cells, bovine and lapine dermal fibroblasts but not the proliferation of bovine aortic endothelial cells and smooth muscle cells. The mitogenic activity is not species-specific, since vitreous from various species stimulates the proliferation of these cells. The mitogenic activity is destroyed by heating at 100 degrees C for 10 min or by trypsin treatment. Since the vitreous, under our assay conditions, was not mitogenic for endothelial cells or smooth muscle cells, the mitogenic activity is probably not derived from leakage into the vitreous of circulating fibroblast, epidermal or platelet-derived growth factor.

Animals↗
PubMed1984

Study of fenfluramine in outpatients with the syndrome of autism.

Fenfluramine was administered to 14 outpatient children with the syndrome of autism to determine whether previously produced decreases in blood serotonin concentrations and clinical improvements could be reinstituted. A double-blind medication-placebo crossover design was used. Each patient received fenfluramine 1.5 mg/kg daily (0.75 mg/kg twice daily) for 8 months, followed by placebo for 2 months. Blood serotonin levels promptly fell approximately 49% regardless of baseline levels. Clinical improvement returned, and on some scales gains after 8 months exceeded those noted after only 4 months of treatment. Significant correlations emerged among the amount of clinical response, initially high verbal IQs, and low blood serotonin concentrations. Compliance was excellent, and no clinically relevant side effects or weight changes occurred. It appears that fenfluramine is effective in ameliorating specific symptoms in certain autistic patients. The extent and mechanism of its action remain to be discovered.

Adolescent↗
PubMed1984

Perceived marital and family environment of opiate addicts.

Addicts have described their family environment as providing inadequate modeling of social and role skills, while having high expectations for achievement. These self-reports have not been compared to either the reports of other family members or observer ratings of addict families. Observer ratings are important because addicts have also described their families as having significantly less conflict than normative families. We administered the Moos Family Environment Scale (FES) to 73 addicts and found that our addicts' scores supported the previous descriptions of addicts' perceived family environment. Addicts' perceived family environment differed from normative samples. They perceived their family as providing little preparation for social roles, while expecting high achievement. When addicts' wives or mothers completed the FES (n = 27), they disagreed with the addicts' perceptions of having high expectations for achievement in the marriage or family. Relative to their mothers and wives, the addicts seemed to be insensitive to the lack of effective organization and limit setting in either their family of origin or marriage. However, the mothers and wives agreed with the addicts in reporting low levels of conflict, but behavioral ratings of the married addicts and their wives (n = 16) showed a poor correlation between the observed behavior and the couples' perceptions. Furthermore, the level of conflict appeared to be above rather than below normative samples. Thus, addicts' perceptions of their family environment demonstrated significant discrepancies from the perceptions of their wives and mothers and from ratings of their marital behavior.

Adult↗
PubMed1983

R plasmid dihydrofolate reductase with a dimeric subunit structure.

Dihydrofolate reductase specified by plasmid R483 from a trimethoprim-resistant strain of Escherichia coli has been purified 2,000-fold to homogeneity using dye-ligand chromatography, gel filtration, and polyacrylamide gel electrophoresis. The protein migrated as a single band on nondenaturing polyacrylamide gel electrophoresis and had a specific activity of 250 mumol/mg min(-1). The molecular weight was estimated to be 32,000 by gel filtration and 39,000 by Ferguson analysis of polyacrylamide gel electrophoresis. When subjected to electrophoresis in the presence of sodium dodecyl sulfate, the protein migrated as a single 19,000-molecular weight species, a fact that suggests that the native enzyme is a dimer of similar or identical subunits. Antibody specific for R483-encoded dihydrofolate reductase did not cross-react with dihydrofolate reductase encoded by plasmid R67, T4 phage, E. coli RT500, or mouse L1210 leukemia cells. The amino acid sequence of the first 34 NH2-terminal residues suggests that the R483 plasmid dihydrofolate reductase is more closely related to the chromosomal dihydrofolate reductase than is the enzyme coded by plasmid R67.

Amino Acid Sequence↗
PubMed1983

Nif- Hup- mutants of Rhizobium japonicum.

Two H2 uptake-negative (Hup-) Rhizobium japonicum mutants were obtained that also lacked symbiotic N2 fixation (acetylene reduction) activity. One of the mutants formed green nodules and was deficient in heme. Hydrogen oxidation activity in this mutant could be restored by the addition of heme plus ATP to crude extracts. Bacteroid extracts from the other mutant strain lacked hydrogenase activity and activity for both of the nitrogenase component proteins. Hup+ revertants of the mutant strains regained both H2 uptake ability and nitrogenase activity.

Hydrogen↗
PubMed1981

[Medical sociology and community-centered care of psychic patients. Methodical considerations of a concrete research project (author's transl)].

The need, problems and possible approaches to sociological investigation of community-centered care of psychological patients is the theme of this contribution. It will at the same time sketch out, even if only in very rough outline, a direction for present day medical sociologic research which has its origin in psychiatric research but which, under the present sociopolitical and care relations, it is necessary to submit to the extramedical field of rehabilitation and aftercare for psychic patients at communal and regional levels according to the importance.

Aftercare↗
PubMed1979

R plasmid dihydrofolate reductase with subunit structure.

Dihydrofolate reductase, specified by the type II plasmid of a trimethoprim-resistant Escherichia coli, was purified 40-fold to homogeneity using a combination of gel filtration, DEAE-Sephacel chromatography, and hydrophobic chromatography. The final product shows a single protein band on polyacrylamide gel electrophoresis and has a specific activity of 1.0 unit/mg. The molecular weight of the purified enzyme is 36,000 as determined both by gel filtration and Ferguson analysis of polyacrylamide gel electrophoresis. In contrast, a single polypeptide with a molecular weight of 8,500 was observed on sodium dodecyl sulfate-gel electrophoresis. These experiments suggest that, unlike any bacteria or vertebrate dihydrofolate reductase previously examined, the type II R plasmid reductase is a tetramer composed of four identical subunits. A partial amino acid sequence determination shows no heterogeneity of the subunits and also no clear homology with any reductase sequence previously reported.

Amino Acid Sequence↗
PubMedDate not supplied

Smoking behavior and attitude toward smoking regulations and passive smoking in the workplace. A study among 974 employees in the German metal industry.

BACKGROUND: Smoking regulations at the workplace have been found to be acceptable and effective in many studies conducted in the United States. There is limited knowledge, however, on acceptance and effects of smoking regulations in European countries, particularly among blue collar employees. METHODS: We conducted a survey on smoking behaviour and attitude toward smoking regulations and passive smoking in a South German metal company. A self-administered questionnaire was mailed to 1,500 predominantly blue collar employees of whom 974 participated in the study (response rate 64.9%). RESULTS: About 30% of the employees were not allowed to smoke at their immediate work area. Among them, about 95% of both smokers and nonsmokers agreed with this smoking policy. More than 60% of nonsmoking blue collar workers were bothered by passive smoking at work whether or not smoking was allowed at their immediate work area. In contrast, the proportion of nonsmoking white collar employees who were bothered by passive smoking varied from 52% if smoking was allowed at their immediate work area to 18% if smoking was not allowed. Prevalence of active smoking and average amount of smoking among active smokers were considerably lower among employees who were not allowed to smoke at work than among other employees. These differences were partly due to confounding by occupation, however, which was strongly related to both smoking habits and smoking policy. CONCLUSIONS: Our results, which confirm and extend previous findings, give further support to the acceptability and potential effectiveness of smoking regulations at the workplace. Particular efforts should be devoted to limit both active and passive smoking among blue collar employees.

Adult↗
PubMedDate not supplied

High resolution MRI of the brainstem at 8 T.

A recently developed ultra high field MRI system operating at 8 T (UHFMRI) was applied for brainstem imaging. UHFMRI was performed in five healthy volunteers (three men, two women; age range 34--46 years). Sagittal and axial slices were obtained with the following settings: GE, TR 750--1,000 ms, TE 7-9 ms, FOV 20 cm, matrix 1,024 x 1,024 or 512 x 512 points, slice thickness 2 mm, resolution 195 or 390 microm/pixel. The brainstem structures were assigned based on anatomy and course. Images with good signal strength and homogeneity were acquired from the midbrain and the pons. Main intraaxial structures could be directly visualized. The periaqueductal gray matter and nuclei had higher signal intensity than the predominantly white matter structures such as the corticobulbar/corticopontine/corticospinal tracts, the sensory lemnisci, and the medial longitudinal fasciculus. Structures with high iron content such as the substantia nigra and the red nucleus were seen as prominent signal hypointensities. Numerous vessels traversing the brainstem including small perforators were also distinguished. It is concluded that UHFMRI enables the acquisition of high quality images of the upper brainstem with details approaching that of histologic specimen.

Adult↗