Biomedical subjects

M Weitz

Publications and source records attributed to M Weitz.

41 records · Page 3Linked to original sources

PubMed1984

Characterization of an active hydrophilic erythrocyte membrane acetylcholinesterase obtained by limited proteolysis of the purified enzyme.

Purified human erythrocyte membrane acetylcholinesterase was subjected to limited proteolysis with papain. This treatment generated a hydrophilic form of the enzyme as determined by charge-shift crossed immunoelectrophoresis and by binding to phenyl-Sepharose. The hydrophilic enzyme was stable and its activity was independent of the presence of amphiphiles. Electroimmunochemical analysis showed no antigenic difference between the two enzyme forms. Although the proteolytic treatment only brought about a small change in molecular weight, marked differences in the hydrodynamic properties were encountered. The Stokes radius decreased from 8.2 to 5.9 nm and the sedimentation coefficient increased from 6.3 to 7.0 S. The results are consistent with the view that a short hydrophobic peptide responsible for the amphipatic character of acetylcholinesterase is removed by the treatment with papain.

Acetylcholinesterase↗

PubMed1984

Stability of hepatitis A virus.

The stabilities of hepatitis A virus (HAV) and of poliovirus type 2 were compared under strictly controlled, identical conditions of pH value, temperature, and salt concentration. Although the resistance of the viruses proved to be the same from pH 3 to 11, the temperature at which 50% of poliovirus particles became disintegrated during heating at pH 7.0 for 10 min (T50,10 = 43 degrees) differed significantly from that characteristic for HAV (T50,10 = 61 degrees). In the presence of 1 M MgCl2, the T50,10 for poliovirus and for HAV shifted to 61 degrees and 81 degrees, respectively. Destabilization of the physical integrity of HAV by heating resulted in the release of viral RNA and, simultaneously, in the generation of several 'empty' capsid structures or dissociation products thereof. Empty capsids and further dissociation products were still serologically reactive with anti-HAV IgG contained in human convalescent sera. With further heating (greater than T50,10 = 67 degrees or greater than T50,1 = 87 degrees), however, they irreversibly lost this reactivity.

Capsid↗

PubMed1982

Quantitative composition and characterization of the proteins in membrane vesicles released from erythrocytes by dimyristoylphosphatidylcholine. A membrane system without cytoskeleton.

Membrane vesicles were prepared by incubation of human erythrocytes with dimyristoylphosphatidylcholine [3] and isolated by isopycnic centrifugation on Dextran density gradients. Protein analyses were carried out with crossed immunoelectrophoresis and dodecylsulfate polyacrylamide gel electrophoresis. The right-side-out-oriented membrane vesicles contained membrane and cytoplasmic proteins of the erythrocyte but lacked cytoskeletal components. Comparison of proteins in vesicles and erythrocyte membranes showed that acetylcholinesterase was enriched two to six times in the vesicles relative to both membrane-spanning proteins, band 3, and glycophorin. Two further, hitherto unidentified, sialic acid-containing membrane antigens were found in the vesicles. Both faced the outside of the membranes and were enriched two to seven times. Ankyrin was not present in the membrane vesicles and spectrin could not be detected by dodecylsulfate polyacrylamide gel electrophoresis. We suggest that the redistribution of proteins in the vesicles reflects differences in their interactions with other membrane components and their relative mobility within the erythrocyte membrane.

Dimyristoylphosphatidylcholine↗

PubMedDate not supplied

Effect of a twice daily 0.12% chlorhexidine rinse on the oral health of a geriatric population.

The inhibitory effect of a chlorhexidine rinse on gingival inflammation and plaque accumulation has been well documented. The purpose of this study was to determine whether a twice daily oral rinse with 0.12% chlorhexidine will resolve denture-associated inflammation in a geriatric population. Thirty-six subjects, average age 83 years, were randomly divided into two groups, active and control, and further stratified into three subgroups, removable partial dentures, complete overdentures and lacking a removable prosthesis. Gingival (Löe and Silness '63) and plaque (Silness and Löe '64) indexes were performed on teeth Nos 3, 9, 12, 19, 25 and 28 at baseline and at 60 days. The subjects, following baseline measurements, were required to rinse twice daily for 30 seconds with either a 15 ml solution of 0.12% chlorhexidine or a placebo and instructed to continue their normal oral hygiene routine. The data were statistically analyzed. When active and control groups were compared, either in total or within their stratified subdivisions, significant differences were observed (P less than 0.001). The active group had a 10.27% and 16.68% reduction in the gingival and plaque indexes, respectively, compared to insignificant changes in the control groups. It was concluded that although chlorhexidine proved effective in reducing inflammation and plaque scores, this reduction was not influenced by the type of prosthesis worn.

Aged↗

PubMedDate not supplied

Pulmonary contusion: CT vs plain radiograms.

In experimentally induced pulmonary contusions, CT (n = 27) and chest X-ray (n = 24) findings were compared with the findings at autopsy. Twenty-seven of 27 (100%) pulmonary contusions were visible by CT immediately after trauma compared with 9 of 24 (37.5%) in the chest X-ray. After 30 min follow-up, 18 of 24 (75%) lesions were seen on the plain film. Five of 24 (21%) contusions escaped detection on conventional radiographs. Computed tomography underestimated lesion size in 5 of 60 (8%) measurements, conventional radiographs in 21 of 36 (58%) measurements. Pathological examination never revealed a pulmonary contusion that was not demonstrated by CT. Therefore, pulmonary contusion seems unlikely in a trauma patient with normal pulmonary CT.

Animals↗