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Biomedical subjects

G Weber

Publications and source records attributed to G Weber.

At least 667 records · Page 37Linked to original sources
PubMed1977

Regression of arteriosclerotic lesions in rhesus monkey aortas after regression diet. Scanning and transmission electron microscope observations of the endothelium.

Scanning and transmission microscopy were used to study aortic intima atherosclerotic lesions in Rhesus monkeys during both progression and regression phases. Scanning micrographs of severely atherosclerotic lesions showed areas of disjunctive endothelium and discontinuous basement membranes, frequently accompanied by red blood cells and other circulating elements adhering to the surface. Transmission micrographs also showed occasional areas of endothelial cell damage and loss with lipid-laden smooth muscle cells and foam cells beneath. Regressed lesions (affected by low-fat, low-cholesterol diet with or without cholestyramine) showed endothelial changes suggestive of reparative processes. Scanning micrographs showed flattened residual lesions with continous endothelial lining, while transmission microscopy disclosed interdigitated intercellular tight junctions and frequently reduplicated basement membranes.

Animals↗
PubMed1977

Description of a permeable eukaryotic cell system to study agents affecting DNA synthesis: demonstration that cytembena is a direct inhibitor of replicative DNA synthesis.

Cells were made permeable to DNTP's by a 15-minute treatment with 0.01 M Tris/HCl (pH 7.8), 0.25 M sucrose, 1 mM EDTA, 30 mM 2-mercaptoethanol, and 4 mM MgCl2 at 4 degrees C. These cells used exogenously supplied dNTP's to carry out semiconservative, replicative DNA synthesis. This system could be used to identify inhibitors of DNA synthesis and to determine whether chemotherapeutic agents affect precursor synthesis or whether they have a direct effect on the DNA replication complex. Thus DNA synthesis in the permeable cells was not inhibited by hydroxyurea or by the nucleoside analogue arabinofuranosyl cytosine. In contrast, the active form of the nucleoside analogue, arabinofuranosyl cytosine triphosphate, and daunorubicin promptly inhibited DNA synthesis in the permeable cells. Cytembena, sodium cis-beta-4-methoxybenzoyl-beta-bromoacrylate, also inhibited DNA synthesis in the permeable cells; this demonstrated that this agent functioned as a direct inhibitor of the DNA replication complex.

Acrylates↗
PubMed1977

Study of the effects of bromocriptine on sexual impotence.

Serum testosterone, prolactin, LH, FSH and plasma 17 beta-oestradiol levels were determined in forty-seven male patients with sexual impotence. Low testosterone values and slightly elevated prolactin levels were observed in 19% and in 17% of cases, respectively. Since sexual function in the male seems to be controlled by both dopaminergic stimulatory and serotoninergic inhibitory mechanisms, bromocriptine was given orally to seventeen patients. As the preliminary results appeared encouraging, a double blind study was undertaken in the other thirty patients. No appreciable difference in hormonal pattern was noticed between bromocriptine and placebo treatment. As far as sexual function was concerned, good results were obtained in 52% of cases treated with bromocriptine and in 44% of patients given placebo.

Adult↗
PubMed1977

Electron microscopy of free-floating cells: thin-layering technique, and selection of individual cells for ultramicrotomy.

A rapid and accurate procedure for electron microscopy of individual cells from suspensions (blood, peritoneal exudate, etc.) is described. After fixation of the sample with standard techniques, the particulate constituents are suspended in buffered 5% bovine serum albumin, thin-layered by gravity on clear supports (cover glasses or polyester slips) in which an orientation grid had been scored, and then immobilized by exposure of the preparations to acrolein vapors. The specimens are examined for cells of interest under a light microscope using interference or phase contrast; individual cells to be sectioned are documented in three photomicrographs taken at different magnifications. After this the specimens are embedded like ordinary cover slip preparations. When examining the face of the polymerized block under a light microscope, the position of the selected cell beneath the orientation grid relief can readily be relocated by the aid of the pre-embedding reference micrographs.

Animals↗
PubMed1977

[Utilisation of photochemotherapy by UVA and locally applied psoralens (author's transl)].

In the Skin Clinic of Neurnberg about 1,500 patients have been treated since 1972 with blacklight and 8-methoxypsoralen, approximately 120-150 every day. This new therapy has proved very good in psoriasis, acne, bacterial disseminated eczema, parapsoriasis and mycosis fungoides. The technique and the rate of relapses, the side effects and their endogenous as well as exogenous causes will be discussed.

Acne Vulgaris↗
PubMed1976

[Unusual joint complications in sickle cell anemia].

It is reported on the casuistics of a 23-year-old Lebanese who since his eighth year suffered from joint swellings and occasional attacks of jaundice. By the proof of false forms of erythrocytes and by the haemoglobin electrophoresis a homozygous sickle cell disease could be ascertained. Peculiarities of the clinical picture were among others changes of the bones of high degree (osteolyses of vertebral bodies, of the head of the right humerus and the heads of the two femurs) was well as of the knee-joints in form of ankyloses.

Adult↗
PubMed1976

Changes in rotational motion of a cell-bound fluorophore caused by colicin E1: a study by fluorescence polarization and differential polarized phase fluorometry.

The stationary fluorescence polarization and the differential phase delay of the polarized components of the fluorescence of 1-phenylnaphthylamine in Escherichia coli suspensions were measured before and after addition of colicin E1. Both sets of measurements register an increase in the rotational relaxation time of the fluorescent probe when colicin is present. These increases are absent in an E. coli mutant tolerant to colicin E1. The physical interpretation of the changes demands separate estimation of the fraction f2 of the emitting fluorophores that change their properties upon colicin addition and of the rotational relaxation time p2 of this fraction, following the colicin-induced changes. By themselves, the steady state polarizaiton observations permit only the conclusion that f2 must be in the range of 1-0.06 and the change in p2/pi between 1.5 and a value larger than 10. Combination of the data of stationary polarization with those of differential phase fluorometry results in an important reduction in the uncertainty:f2 must be in the range 1-0.33 and the change in p2/pi in the range 1.5-2.5.

Binding Sites↗
PubMed1976

Histone inhibition of DNA synthesis in eukaryotic cells permeable to macromolecules.

Mouse L Cells, grown in suspension culture can be rendered permeable to exogenous deoxynucleoside triphosphates by a cold shock in a near isotonic buffer system. These cells use the deoxynucleotides to synthesize DNA in a semiconservative fashion. The addition of 0.05% Triton X-100 to this system increases the permeability of the cells so that exogenously supplied macromolecules gain access to the DNA. When DNAase and phosphodiesterase are added to the detergent-permeabilized cells, the cell DNA is rapidly degraded, demonstrating that the enzymes reach the DNA within the first 2 min of the incubation period. Addition of whole calf thymus histone or histone fractions to the detergent-permeabilized cells inhibits DNA synthesis. The lysine-rich histone, F is a more effective inhibitor than the arginine-rich histone, F3. The other histone fractions including the slightly lysine-rich fractions, F2a and F2b, are intermediate between F1 and F3 as inhibitors of DNA- synthesis. Kinetic analysis demonstrates that the added histones increase apparent Km and reduce V of DNA synthesis in the permeabilized cells. These studies suggest the possibility that histones alter the association of the DNA replication complex and the DNA template in a manner that reduces the rate of DNA synthesis.

Biological Transport↗
PubMed1976

Effects of pressure upon the fluorescence of the riboflavin binding protein and its flavin mononucleotide complex.

The effect of pressure in the range of 10(-3)-10 kbars upon the ultraviolet fluorescence of the riboflavin binding protein and the fluorescences of its complex with flavin mononucleotide has been studied. The fluorescence spectrum of the isolated protein showed a reversible red shift of 12nm (1000 cm-1) at high pressure, indicating the reversible exposure of the tryptophan to solvent. From the pressure dependence of the visible fluorescence of the protein-flavin complex in the region of 1-4 kbars the volume change in dissociation of the protein-ligand complex was estimated to be +3.3ml/mol. A very sharp increase in fluorescence-up to 30-fold of the low-pressure value-takes place in the region 5-8 kbars. This increase is due to release of the flavin from the complex and is assigned to pressure denaturation of the protein. The midpoint, rho 1/2, of this transition was found at 6.5 kbars and the change in volume, delta, in the reaction (native-to-denatured) was calculated to be -74ml/mol. Addition of up to 30% methanol results in a progressive decrease both in delta and rho 1/2, in agreement with the concept that hydrophobic bonding stabilizes the native structure.

Bromosuccinimide↗