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Biomedical subjects

M J Weber

Publications and source records attributed to M J Weber.

At least 163 records · Page 9Linked to original sources
PubMed1980

Comparative inactivation of viruses by chlorine.

The kinetics of inactivation of six enteric viruses plus simian virus 40 and Kilham rat virus by free available chlorine was studied under carefully controlled laboratory conditions. It was found that the different virus types demonstrated a wide range of susceptibility to chlorine disinfection. The rate of inactivation was greater at pH 6 than at pH 10; however, the relative susceptibilities of the different viruses were affected differently by a change in pH, suggesting that the pH influenced both the species of chlorine present and the susceptibility of the different viruses to chlorine. The presence of potassium chloride also affected the susceptibility of viruses to chlorine.

Antiviral Agents↗
PubMed1980

[The effectiveness of recurrence prophylaxis four to five years after struma surgery].

Four to five years after the operation of an endemic goiter, 63% of the patients regularly take thyroxin prophylactically and 85% as substitution. The effect of this hormone therapy was checked using the radioiodine uptake of the thyroid. In those patients with an increase in the size of the thyroid in the scintigram, there was usually a pathological TRH-TSH test with elevated basal and very elevated late values for TSH. While the prophylactic benefit of thyroxin after unilateral thyroidectomy must be further evaluated with other parameters, there is no doubt that thyroxin is necessary for those patients in whom a bilateral thyroidectomy has been performed.

Goiter, Endemic↗
PubMed1980

Efficacy of various forms of fixation of transverse fractures of the patella.

To determine whether any of the commonly used wiring techniques are rigid enough to allow early motion in the treatment of transverse fracture of the patella, the patellae of twenty-five fresh cadaver knees were fractured transversely and fixed using the following techniques: circumferential wiring, tension-band wiring, Magnusson wiring, and a modification of tension-band wiring. The knees were mounted in a machine capable of measuring quadriceps force, flexion angle, and fracture separation simultaneously. The knees were extended from 90 to zero degrees by applying tension to the quadriceps tendon with the force of gravity as the only resistance, and separation of the fracture fragments was measured first with the retinaculum unrepaired and then again with the retinaculum repaired. Separation of the fracture fragments was much less with the Magnusson wiring and modified tension-band wiring than with circumferential wiring or standard tension-band wiring. The retinacular repair was found to contribute to stability; however, this seemed most important in the less rigid repairs. We concluded that if early motion is to be used in treating transverse fractures of the patella, techniques in which the wire is anchored directly in bone should be used and the retinaculum should be repaired.

Cadaver↗
PubMed1980

Device and method for controlling cement thickness.

The ideal thickness of cement between the prosthesis and bone has not been accurately determined, but there is general agreement that the surgeon should be able to provide and accurately produce a certain thickness of cement between the prosthesis and the bone. Conventional cementing technique could allow the surgeon to ovepush the cup into direct contact with the bone producing a very thin cement coat or a void. We have developed a simple method of achieving a predictable thickness. We insert small spacers made of methylmethacrylate, which can be placed between the bone of the acetabulum and the acetabular component, preventing voids or thin areas in the cement coat. The device has been used in over 50 patients and has proven to be a simple and reliable method of allowing the surgeon to produce a predictable thickness of cement surrounding a joint replacement component. An additional benefit obtained from the use of these spacers is the ability to rigidly hold the acetabular component during polymerization of the acrylic without fear of overpushing. This allows better packing of the bone cement and prevents imperfections caused by the cup contacting the bone.

Acetabulum↗
PubMed1979

Amino acid transport in normal and Rous sarcoma virus-transformed chicken embryo fibroblasts.

A study was made of the transport of a variety of amino acids by uninfected and Rous sarcoma virus-infected chicken embryo fibroblasts. Following a period of amino acid starvation, transformed, but not normal cells, showed increased levels of transport for alpha-aminoisobutyric acid, proline and alanine, three amino acids which are transported primarily by the A transport system. There was no starvation-induced increase in the transport of leucine, phenylalanine, lysine, or cycloleucine. In the absence of starvation, normal and transformed cells exhibited comparable rates of amino acid transport. Cycloheximide was able to block the increase in uptake. The enhanced uptake was characterized by an increase in Vmax for transport and little change in Km. The data demonstrate that an alteration in the regulation of the A amino acid transport system is an early event in malignant transformation by Rous sarcoma virus. However, since this alteration in made manifest only following a period of starvation, our findings suggest that increased amino acid uptake does not play a role in generating the other manifestations of the transformed state seen in cell culture.

Amino Acids↗
PubMed1979

Potassium fluxes and ouabain binding in growing, density-inhibited and Rous sarcoma virus-transformed chicken embryo cells.

Potassium fluxes, ouabain binding, and Na+ and K+ intracellular concentrations were determined for cultures of growing normal, density-inhibited and Rous sarcoma virus-transformed chicken embryo fibroblasts. No significant differences in K+ influx or ouabain binding were detected between growing normal cells and Rous sarcoma virus-transformed cells; however, ouabain binding and ouabain-sensitive K+ influx were 1.5- to 1.8-fold lower in density-inhibited cells. Thus, potassium influx in this system can be classified as a growth-related, but not transformation-specific change. As determined by both flame photometry and radioisotopic (42K) equilibration, growing normal and density-inhibited cells had similar potassium contents, whereas transformed cells exhibited 1.4-fold higher potassium levels. Sodium ion levels, as measured by flame photometry, were also 2- to 4.5-fold higher in transformed than normal or density-inhibited cells. Complementary studies of potassium efflux showed a 1.3- to 1.5-fold higher rate (based on the percentage of pool exiting the cell) in growing normal versus density-inhibited or transformed fibroblasts. Because of the larger potassium pool in transformed cells, efflux based on absolute number of potassium ions is similar in normal and transformed chicken embryo fibroblasts.

Animals↗
PubMed1979

Effect of growth conditions on the content of the major groups of carbohydrates in chick embryo fibroblasts.

The levels of glycogen, hyaluronic acid, chondroitin sulfates, N-acetylneuraminic acid, all of the monosaccharide components of the glycoprotein and glycolipid fractions, and the monosaccharide pools were measured in cultured chick embryo fibroblasts. Under all growth conditions, the glycogen plus the glucose phosphate pool contained approximately 50% of total monosaccharide content of the cells. However, marked qualitative and quantitative alterations were found in the glycoprotein, glycolipid, and mucopolysaccharide fractions when growing cells reached confluence, when the growth temperature was shifted from 36 to 41 degrees, or when the cells were transformed with Rous sarcoma virus. From 65 to 95% of the total monosaccharide residues in these complex carbohydrates were found in the glycoprotein fraction, while the glycolipids contained only 5 to 10% of the residues, and the mucopolysaccharides contained 5 to 25%. Changes in the complex carbohydrates in normal cells following changes in cell density or growth temperature were so great that they obscured any transformation-dependent changes that might have occurred consistently in the virus-infected cells under different growth conditions.

Animals↗
PubMed1978

Increased membrane transport of 2-deoxyglucose and 3-O-methylglucose is an early event in the transformation of chick embryo fibroblasts by Rous sarcoma virus.

Transformation of chicken embryo fibroblasts with Rous sarcoma virus results in cells with an enhanced rate of hexose uptake. We have examined transport of the glucose analogs 2-deoxyglucose and 3-O-methylglucose in cells infected with a temperature sensitive variant of the virus. In cells shifted from restrictive to permissive conditions for transformation, increased transport of the non-phosphorylatable analog 3-O-methylglucose occurs at the same time as that of 2-deoxyglucose, a phosphorylatable analog. This enhanced rate of transport can be observed within three hours of the temperature shift. There is a corresponding decrease in the transport rate of both analogs following shift to the restrictive temperature. These results suggest that increased transport is likely to be the primary event in causing transformation-specific changes in sugar metabolism. We have also examined uptake into the internal pools of both the phosphorylated and non-phosphorylated forms of 2-deoxyglucose in normal cells and in cells transformed by the wild-type virus. These data indicate a corresponding increase in the rate of accumulation of the free sugar in transformed cells and point to transport as the rate limiting step in the accumulation of 2-deoxyglucose in both normal and transformed chicken embryo cells.

Animals↗
PubMed1978

Turnover of cellular carbohydrates in normal and Rous sarcoma virus-transformed cells.

We have analyzed the distribution of glucosamine-labeled polymers on the cell surface, in the growth medium, and inside the cell and the net turnover of these polymers during the process of malignant transformation of chick embryo fibroblasts by Rous sarcoma virus. The distribution of label and the turnover kinetics for hyaluronic acid, total glycoproteins, and chondroitins were found to be identical in both normal and transforming cultures. We conclude that nonspecific degradative processes are probably not involved in causing transformation-related alterations in cell surface carbohydrates, althougn degradation of specific macromolecules is not excluded.

Avian Sarcoma Viruses↗
PubMed1977

Decreased adherence to the substrate in Rous sarcoma virus-transformed chicken embryo fibroblasts.

Cell-substrate adherence in cultures of chicken embryo fibroblasts was examined by determining the number of cells which could be detached from the culture dish by a stream of medium. Transformed cells were significantly less adherent than their normal counterparts. In cultures infected with a mutant of Rous sarcoma virus which is temperature-conditional for transformation, adherence changed promptly following a temperature shift. This change did not require progression through the cell cycle. The transformation-specific decrease in adherence required new protein synthesis, but the restoration of adherence which occurred following a shift to the restrictive temperature could occur in the absence of new protein synthesis. Inhibitor experiments suggested the importance of microfilaments and perhaps microtubules in the changes in detachability. In addition, there was a positive correlation between levels of surface LETS protein and cell substrate adherence following a temperature shift, although it seems probable that the bulk of the surface LETS is neither necessary nor sufficient for maintenance of normal cell substrate adherence.

Avian Sarcoma Viruses↗
PubMed1976

Solubilization of adenylate cyclase from normal and Rous sarcoma-transformed chicken embryo fibroblasts.

Adenylate cyclase activities in membranes prepared from Rous sarcoma-transformed chicken embryo fibroblasts are 2 to 4 times lower than in membranes prepared from normal chicken embryo fibroblasts. Adenylate cyclase activities were solubilized from normal and transformed membranes with five different nonionic detergents. In all cases, the specific activities of the enzyme solubilized from normal and transformed preparations were essentially identical. These data suggest that the microenvironment of adenylate cyclase in transformed membranes may be wholly or partially responsible for the decreased activities of this enzyme.

Adenylyl Cyclases↗