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Biomedical subjects

M Levine

Publications and source records attributed to M Levine.

At least 469 records · Page 26Linked to original sources
PubMed1984

Magnetic resonance imaging of the orbit: a preliminary experience.

Eleven patients with various space-occupying lesions in the orbit were examined, using a 0.3-tesla superconducting magnet to assess the capabilities and limitations of magnetic resonance (MR) imaging in the investigation of orbital lesions. Although the images provided valuable anatomic data, the bright signal intensity of fat and the partial volume effects of large section thickness resulted in loss of resolution for small, low-signal-intensity structures. The limitations of MR imaging were also reaffirmed by the lack of visualization of calcifications and of the bony orbit. These preliminary results show that MR offers no advantage over x-ray computed tomography except for its lack of ionizing radiation. Further technical improvements are needed before MR imaging will be made useful in this area.

Adult↗
PubMed1984

Circumcision using the Mogen clamp.

The purpose of this study was to analyze the results of 313 circumcisions using the Mogen clamp. This procedure was done between 1 day and 2 years of age in all but four patients. The complication rate was low (1.6%). Two patients had local infection, one mild hemorrhage, one concealed penis, and one postcircumcision phimosis. Circumcision using the Mogen clamp is a simple, quick, and safe procedure.

Circumcision, Male↗
PubMed1984

A residency program in community pharmacy practice.

As pharmacists increase their involvement in patients' drug therapy, the lack of opportunity for advanced clinical and administrative training becomes more critical, particularly for community pharmacists. To assist in the postgraduate development of community pharmacists, the faculty of pharmaceutical sciences at the University of British Columbia began a residency program in community pharmacy practice in June 1981. Modeled on the successful hospital pharmacy residencies, the program goals are to provide advanced clinical training in ambulatory patient care, and detailed and practical management training, and to develop pharmacists with skill in clinical teaching who will participate in the undergraduate programs of the faculty. The 12-month residency includes guided self-study and a series of practica in areas of therapeutics, management, drug information, clinical and teaching skill, professional service, and continuing education. These practica are served mainly in clinical practice settings such as community pharmacies, clinics, physicians' offices, and teaching hospitals. The residency has demonstrated its value and viability. Growing interest in such programs, and the success of this program in particular, should encourage the development of similar programs in Canada.

British Columbia↗
PubMed1984

Utilization of mental health services by the aging.

A descriptive study of persons 55 years of age and older who were newly admitted (60 cases) or in ongoing treatment (30 cases) in a mental health center was done as an outgrowth of a utilization review study. The total population of 461 was studied from July 1, 1977, to June 30, 1978. A chart review of 90 cases was performed. The newly admitted subsample was married, was diagnosed as depressed, and had a broad range of dispositions into various treatment modalities. The chronic subsample was single, diagnosed as schizophrenic, and in treatment in a single community-support unit. These differences were statistically significant at the P<.01, P<.001, and P<.001 levels, respectively. Although the newly admitted subsample had no previous contact with psychiatric services, 44 of the 60 patients (73 percent) were on psychoactive medication prescribed by nonpsychiatric physicians. Implications for the training of general medical practitioners and mental health center staff, and the need for ongoing assessment of patients in community support units are discussed, as well as the significant risk to patients from potentially harmful drug interactions.

Aged↗
PubMed1983

Ascorbic acid and catecholamine secretion from cultured chromaffin cells.

Ascorbic acid was found to be secreted from cultured bovine adrenal chromaffin cells coincidentally with catecholamines using a variety of secretagogues, including veratridine, nicotine, acetylcholine, and potassium chloride. Secretion of ascorbic acid was measured by preloading the cells for 3 h with (R)-[14C]ascorbic acid and then quantitating release of the label. The newly transported ascorbic acid constituted nearly 90% of total cellular ascorbic acid. Although chromaffin granules are known to contain endogenous ascorbic acid, only 16% of the total labeled ascorbic acid taken up by cultured cells was localized to the chromaffin granule fraction. Under the same isolation conditions, 95% of the endogenous catecholamines was found in the granule fraction. The secretion of both (R)-[14C] ascorbic acid and catecholamines was calcium dependent. However, only catecholamine secretion was effectively inhibited by the presence in the medium of isethionate, an impermeant ion that inhibits catecholamine secretion from isolated chromaffin granules. Analysis of the ratios of cellular and granular (R)-[14C] ascorbate as well as secreted (R)-[14C]ascorbate and catecholamines revealed that the secreted (R)-[14C]ascorbic acid did not come exclusively from the chromaffin granule fraction but also from a nonsedimenting cytoplasmic compartment. Indeed, for all four agonists, the amounts of (R)-[14C]ascorbic acid secreted were more than 1.5 times greater than could be accounted for by chromaffin granule ascorbate alone. We took these data to indicate that, while ascorbic acid and catecholamines were secreted concomitantly, the sources of the secreted substances were not necessarily identical.

Acetylcholine↗
PubMed1983

Inhibition of glycosylation of herpes simplex virus glycoproteins: identification of antigenic and immunogenic partially glycosylated glycopeptides on the cell surface membrane.

The surface membranes of cells infected with herpes simplex virus type 1 (HSV-1), strain KOS, contain three principal glycoproteins, gC (apparent Mr 129k), gB (apparent Mr 120k), and gD (apparent Mr 58k). Infections carried out in the presence of the glycosylation inhibitor 2-deoxy-D-glucose result in the loss of the mature species with the concurrent appearance of lower-molecular-weight polypeptides which are presumably partially glycosylated forms of the fully processed glycoproteins. Specific immunoprecipitation of radiolabeled cytoplasmic extracts of 2-deoxy-D-glucose-inhibited infections identified partially glycosylated proteins designated DG92, DG88, and DG53, which are antigenically related to the corresponding mature forms gB, gC, and gD. Cell surface radioiodination, in combination with specific immunoprecipitation, revealed that DG88 and DG53 were the principal species transported to the cell surface in 2-deoxy-D-glucose-inhibited infections. DG92 was readily detected in the cytoplasm but not on the plasma membrane. Cells infected with the KOS mutant, syn LD70, did not synthesize glycoprotein gC. In glycosylation-inhibited syn LD70 infections, DG88 was not detected in either the cytoplasm or plasma membrane, demonstrating a genetic relationship between DG88 and gC. Polyclonal and monoclonal antibodies directed against the glycoproteins gC, gB, and gD sensitized infected cells to complement-mediated immune cytolysis. Cells infected in the presence of the inhibitor were sensitized to lysis only by antibody specific for gC and gD. The glycosylation-inhibited cells were insensitive to immunolysis by anti-gB monoclonal antibody. These findings confirm that the glycosylation-deficient forms of gC and gD, but not gB reach the cell surface in the presence of inhibitor and that the inhibitor-induced alterations in glycosylation do not cause a complete loss of antigenicity. Inoculation of mice with syngeneic 3T3 cells infected in the presence or absence of inhibitor-induced cytolytic and neutralizing antibody. A major portion of the cytolytic antibody was directed against gC, but anti-gC antibody appeared to play a minor role in virus neutralization. While the serum induced by the control infected cells contained precipitating antibodies for gC, gB, and gD, the serum derived from mice inoculated with inhibitor-treated infected cells had only weak immunoprecipitating activity against gB. Together, these findings have identified partially glycosylated forms of the major HSV glycoproteins and show that complete glycosylation is not required for transport of some of these partially glycosylated polypeptides to the cell surface. Moreover, complete glycosylation of the glycopeptides is not essential for maintenance of antigenicity or immunogenicity, indicating that at least some determinants recognized by antibodies directed against the mature glycoproteins are not affected by 2-deoxy-D-glucose-induced carbohydrate alterations.

Animals↗
PubMed1983

An improved in situ hybridization method for the detection of cellular RNAs in Drosophila tissue sections and its application for localizing transcripts of the homeotic Antennapedia gene complex.

An improved method for the detection of cellular RNAs in tissue sections has been developed. It involves in situ hybridization of tritium-labeled cloned DNA probes to tissue sections and autoradiography. The method was calibrated by using a cloned DNA probe complementary to transcripts abundant in the midgut cells of Drosophila larvae. The improved method also permitted the detection of these transcripts in sectioned embryos where they are much less abundant. The sensitivity of the method can be approximated by quantifying the signal intensities over the hybridizing embryonic midgut cells relative to the larval midgut cells for which the number of transcripts has been estimated. Based on these calculations we estimate that the method is sensitive enough to detect 100 complementary RNA molecules per cell after 3 days of autoradiographic exposure with a signal-to-noise ratio of 10. The method has been successfully applied to detect transcripts of the homeotic gene Antennapedia. Serial sections allow us to study the spatial pattern of gene expression in the course of development.

Journal Article↗
PubMed1983

Spatial distribution of Antennapedia transcripts during Drosophila development.

We have localized transcripts specified by the homeotic Antennapedia (Antp) locus within serial tissue sections of Drosophila embryos and larvae by in situ hybridization. As a hybridization probe we used a 2.2-kb cDNA sequence (903) which is complementary to at least four non-contiguous chromosomal DNA regions within a span of 100 kb derived from the Antp+ locus. The tritiated probe was directly hybridized to frozen tissue sections of wild-type embryos and larvae. Hybridization was first detected to the progenitors of the thoracic segments during the cellularization of the syncytial blastoderm, when embryonic cells first become determined to form particular adult segments. At later embryonic stages the ventral nervous system also becomes labeled in a spatially-restricted manner. Initially, accumulation of transcripts is detected in all thoracic and abdominal ganglia of the ventral cord. Subsequently, the highest concentration of transcripts is detected in the ganglion cells of the mesothorax. Proper development of this segment is known to be affected in individuals homozygous for putative Antp null alleles. In third-instar larvae, hybridization to the different imaginal disks of all three thoracic segments is observed, localized mainly to those regions that will form proximal, cuticular portions of the respective segments. These results are discussed with respect to the role of homeotic genes in the specification of particular anatomical segments.

Animals↗
PubMed1983

High-efficiency transfer of DNA into eukaryotic cells by protoplast fusion.

Protoplast fusion is a highly efficient method for effecting gene transfer to cells in culture resulting in stable transformation at high frequency. A number of cell lines have been used successfully as recipients. There is no need to isolate and purify the DNA, which not only saves time and effort but eliminates steps that cause nicking or breaking of large cloned inserts. The high-frequency transformation achievable by protoplast fusion should make this procedure useful for studies on gene expression and for screening cloned genomic libraries for genes that can be expressed in recipient cells.

Animals↗
PubMed1983

Theory of the electrokinetic behavior of human erythrocytes.

We develop a theory of electrophoresis of human erythrocytes that predicts mobilities significantly smaller than those based on the classical Smoluchowski relation. In the classical treatment the charge is assumed to be spread uniformly on the hydrodynamic surface. The present model takes into account that most of the charge, due mainly to sialic acid, is contained in the glycocalyx. The glycocalyx is modeled as a permeable layer of polyelectrolyte molecules anchored to the cell membrane. The charge is assumed to be uniformly distributed throughout this layer. The fluid flow in the layer is treated as being dominated by Stokes friction arising from idealized polymer segments. The Navier-Stokes equations are solved to give the dependence of electroosomotic velocity with distance from the cell surface. An expression for the electrophoretic mobility is obtained which contains two parameters (a) the thickness of the glycocalyx and (b) the mean polymer segment radius. The best fit to experimental data is obtained if these are given the values 75 A and 7 A, respectively. Deviation from experimental data at low ionic strength (less than 0.05 M) occurs. However, this deviation is in the direction one would expect if at low ionic strength the polyelectrolyte layer expands slightly due to decreased charge shielding.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1983

Chemical evidence that catecholamines are transported across the chromaffin granule membrane as noncationic species.

Catecholamines are transported into chromaffin granules by a Mg2+/ATP-driven process under conditions in which the substrate exists primarily as a positively charged or neutral species. In order to distinguish between these two states, we studied the transport properties of a permanently charged quaternary analogue of epinephrine, (R,S)-dimethylepinephrine. We found that this compound was a classical competitive inhibitor of (R)-[3H]norepinephrine uptake, with a Ki of 3.8 mM for the racemic form, or 1.9 mM for the R form. However, the [3H]dimethylepinephrine was not transported at all into granules. Our control for steric hindrance as an explanation for deficient translocation was analysis of the transport properties of isoproterenol, a secondary catecholamine with an isopropyl group around the amine residue. (R)-Isoproterenol was an effective competitive inhibitor of (R)-[3H]norepinephrine transport, with a Ki of 91 microM. In contrast to dimethylepinephrine, (R,S)-[3H]isoproterenol was clearly translocated across the granule membrane, with a Km of 123 microM, or 61.5 microM for the R isomer. Thus, the positive charge on dimethylepinephrine and not the size of the amine moiety appeared to be responsible for the lack of translocation. We interpret these data to indicate that, although the positively charged species can interact with the transport site, an uncharged species is the one actually transported.

Animals↗
PubMed1983

Serologic differentiation between antitoxin responses to infection with Vibrio cholerae and enterotoxin-producing Escherichia coli.

A ganglioside enzyme-linked immunosorbent assay (ELISA) was used to study and attempt to differentiate between antitoxin responses in persons infected with either Vibrio cholerae or Escherichia coli producing heat-labile enterotoxin. In most cases (69%-94%), experimentally infected North Americans and naturally infected Bangladeshis responded to either infection with significant (greater than twofold) increases in serum antibody titer to both heat-labile enterotoxin and cholera toxin. In all but one instance, the response was higher to the homologous than to the heterologous toxin, and for the Americans the homologous antitoxin titers remained significantly higher for at least one year. Determination of levels of antibodies to purified subunits A and B of cholera toxin by an ELISA showed that V. cholerae infection in most instances induced a significant response to subunit B but rarely to subunit A. E. coli infection, on the other hand, induced only slight increases in antibody titer to either subunit.

Adolescent↗
PubMed1983

Primary amyloid tumor of the lacrimal gland: CT findings.

We present a rare case of primary amyloid tumor originating in the lacrimal gland. The computed tomographic findings are similar to those of an orbital angioma, showing an enhancing soft tissue mass with multiple calcifications simulating phleboliths.

Amyloidosis↗
PubMed1983

Antigenic variants of herpes simplex virus selected with glycoprotein-specific monoclonal antibodies.

Monoclonal antibodies specific for herpes simplex virus type 1 (HSV-1) glycoproteins were used to demonstrate that HSV undergoes mutagen-induced and spontaneous antigenic variation. Hybridomas were produced by polyethylene glycol-mediated fusion of P3-X63-Ag8.653 myeloma cells with spleen cells from BALB/c mice infected with HSV-1 (strain KOS). Hybrid clones were screened for production of HSV-specific neutralizing antibody. The glycoprotein specificities of the antibodies were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of immunoprecipitates of radiolabeled infected-cell extracts. Seven hybridomas producing antibodies specific for gC, one for gB, and one for gD were characterized. All antibodies neutralized HSV-1 but not HSV-2. Two antibodies, one specific for gB and one specific for gC, were used to select viral variants resistant to neutralization by monoclonal antibody plus complement. Selections were made from untreated and bromodeoxyuridine- and nitrosoguanidine-mutagenized stocks of a plaque-purified isolate of strain KOS. After neutralization with monoclonal antibody plus complement, surviving virus was plaque purified by plating at limiting dilution and tested for resistance to neutralization with the selecting antibody. The frequency of neutralization-resistant antigenic variants selected with monoclonal antibody ranged from 4 X 10(-4) in nonmutagenized stocks to 1 X 10(-2) in mutagenized stocks. Four gC and four gB antigenic variants were isolated. Two variants resistant to neutralization by gC-specific antibodies failed to express gC, accounting for their resistant phenotype. The two other gC antigenic variants and the four gB variants expressed antigenically altered glycoproteins and were designated monoclonal-antibody-resistant, mar, mutants. The two mar C mutants were tested for resistance to neutralization with a panel of seven gC-specific monoclonal antibodies. The resulting patterns of resistance provided evidence for at least two antigenic sites on glycoprotein gC.

Antibodies, Monoclonal↗
PubMed1983

Physical mapping of the mutation in an antigenic variant of herpes simplex virus type 1 by use of an immunoreactive plaque assay.

Two mutations affecting herpes simplex virus type 1 glycoprotein B were mapped by marker rescue using cloned sequences of wild-type herpes simplex virus type 1 strain KOS DNA. One mutant, tsB5, is a temperature-sensitive mutant which does not express mature, functional glycoprotein B at the nonpermissive temperature. The other mutant, marB1.1, expresses an antigenic variant of glycoprotein B and was selected for resistance to neutralization by a monoclonal antibody. The mutation in tsB5 mapped to a 1.2-kilobase segment of the herpes simplex virus type 1 genome between coordinates 0.361 and 0.368, whereas the mutation in marB1.1 mapped to a 1.6-kilobase segment between coordinates 0.350 and 0.361. An in situ enzyme immunoassay was used to detect plaques of recombinant wild-type virus among the progeny of transfections with mutant marB1.1 DNA and wild-type DNA fragments.

Antigens, Viral↗