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Biomedical subjects

M Levine

Publications and source records attributed to M Levine.

At least 415 records · Page 23Linked to original sources
PubMed1987

Neutralizing monoclonal antibodies specific for herpes simplex virus glycoprotein D inhibit virus penetration.

Nine monoclonal antibodies specific for glycoprotein D (gD) of herpes simplex virus type 1 were selected for their ability to neutralize virus in the presence of complement. Four of these antibodies exhibited significant neutralization titers in the absence of complement, suggesting that their epitope specificities are localized to site(s) which contribute to the role of gD in virus infectivity. Each of these antibodies was shown to effectively neutralize virus after virion adsorption to cell surfaces, indicating that neutralization did not involve inhibition of virus attachment. Although some of the monoclonal antibodies partially inhibited adsorption of radiolabeled virions, this effect was only observed at concentrations much higher than that required to neutralize virus and did not correlate with complement-independent virus-neutralizing activity. All of the monoclonal antibodies slowed the rate at which virus entered cells, further suggesting that antibody binding of gD inhibits virus penetration. Experiments were carried out to determine the number of different epitopes recognized by the panel of monoclonal antibodies and to identify epitopes involved in complement-independent virus neutralization. Monoclonal antibody-resistant (mar) mutants were selected by escape from neutralization with individual gD-specific monoclonal antibodies. The reactivity patterns of the mutants and antibodies were then used to construct an operational antigenic map for gD. This analysis identified a minimum of six epitopes on gD that could be grouped into four antigenic sites. Antibodies recognizing four distinct epitopes contained in three antigenic sites were found to neutralize virus in a complement-independent fashion. Moreover, mar mutations in these sites did not affect the processing of gD, rate of virus penetration, or the ability of the virus to replicate at high temperature (39 degrees C). Taken together, these results (i) confirm that gD is a major target antigen for neutralizing antibody, (ii) indicate that the mechanism of neutralization can involve inhibition of virus penetration of the cell surface membrane, and (iii) strongly suggest that gD plays a direct role in the virus entry process.

Animals↗
PubMed1987

The pseudorabies virus gII gene is closely related to the gB glycoprotein gene of herpes simplex virus.

We have looked for conserved DNA sequences between four herpes simplex virus type 1 (HSV-1) glycoprotein genes encoding gB, gC, gD, and gE and pseudorabies virus (PRV) DNA, HSV-1 DNA fragments representing these four glycoprotein-coding sequences were hybridized to restriction enzyme fragments of PRV DNA by the Southern blot procedure. Specific hybridization was observed only when HSV-1 gB DNA was used as probe. This region of hybridization was localized to a 5.2-kilobase (kb) region mapping at approximately 0.15 map units on the PRV genome. Northern blot (RNA blot) analysis, with a 1.2-kb probe derived from this segment, revealed a predominant hybridizing RNA species of approximately 3 kb in PRV-infected PK15 cells. DNA sequence analysis of the region corresponding to this RNA revealed a single large open reading frame with significant nucleotide homology with the gB gene of HSV-1 KOS 321. In addition, the beginning of the sequenced PRV region also contained the end of an open reading frame with amino acid homology to HSV-1 ICP 18.5, a protein that may be involved in viral glycoprotein transport. This sequence partially overlaps the PRV gB homolog coding sequence. We have shown that the PRV gene with homology to HSV-1 gB encoded the gII glycoprotein gene by expressing a 765-base-pair segment of the PRV open reading frame in Escherichia coli as a protein fused to beta-galactosidase. Antiserum, raised in rabbits, against this fusion protein immunoprecipitated a specific family of PRV glycoproteins of apparent molecular mass 110, 68, and 55 kilodaltons that have been identified as the gII family of glycoproteins. Analysis of the predicted amino acid sequence indicated that the PRV gII protein shares 50% amino acid homology with the aligned HSV-1 gB protein. All 10 cysteine residues located outside of the signal sequence, as well as 4 of 6 potential N-linked glycosylation sites, were conserved between the two proteins. The primary protein sequence for HSV-1 gB regions known to be involved in the rate of virus entry into the cells and cell-cell fusion, as well as regions known to be associated with monoclonal antibody resistance, were highly homologous with the PRV protein sequence. Furthermore, monospecific antibody made against PRV gII immunoprecipitated HSV-1 gB from infected cells. Taken together, these findings suggest significant conservation of structure and function between the two proteins and may indicate a common evolutionary history.

Amino Acid Sequence↗
PubMed1987

Pulmonary angiography in severe chronic pulmonary hypertension.

We have analyzed the safety of doing pulmonary angiography in 67 consecutive patients with moderate-to-severe primary pulmonary hypertension or hypertension secondary to chronic thromboembolic occlusions of the pulmonary arteries. The average (+/- SD) pulmonary arterial systolic and diastolic pressures were 74 +/- 19 and 34 +/- 10 mm Hg, respectively. Fourteen patients had a right ventricular end-diastolic pressure of 20 mm Hg or more. Selective left and right main pulmonary artery injections were done using ionic contrast agents in 56 patients and nonionic contrast agents in 11. No major rhythm disturbances or systemic hypotension requiring therapy occurred, and there were no deaths. Thrombotic occlusions of the pulmonary arteries were identified in 52 patients and confirmed in all 42 of those who had a thromboendarterectomy. At autopsy, 3 of the 15 patients who had normal angiograms were found not to have had thrombotic occlusions. We conclude that pulmonary angiography can be done safely despite the presence of severe pulmonary hypertension and right ventricular failure, and that the procedure leads to the identification of chronic, major-vessel thromboembolic pulmonary hypertension that may be alleviated by thromboendarterectomy.

Adolescent↗
PubMed1987

Spatial regulation of homeo box gene expression in Drosophila.

1. Each of the 17 known homeo box genes shows a unique pattern of expression during early embryonic development. Thus, virtually every embryonic cell contains a unique combination of active and inactive homeo box genes. 2. These different permutations of homeo box gene expression are thought to specify unique positional values, and appear to play key roles in selecting diverse pathways of morphogenesis. 3. It has been proposed that selective patterns of homeo box gene expression involve cross-regulatory interactions. For example, it appears that homeotic genes expressed in posterior regions of the embryo (such as abd-A and Abd-B) repress the expression of those homeotic genes expressed in more anterior regions (such as Antp and Ubx). Such interactions might involve sequence-specific DNA binding and occur at the level of transcription. 4. The establishment of selective patterns of pair-rule gene expression along the anterior-posterior embryonic body axis might involve the differential regulation of these genes by a common set of transcription factors. In particular, it appears that eve and ftz show opposite responses to regulatory products that are either directly or indirectly specified by several gap genes.

Amino Acid Sequence↗
PubMed1986

Cross-regulatory interactions among pair-rule genes in Drosophila.

The pair-rule genes of Drosophila are required for the subdivision of the developing embryo into a repeating series of homologous body segments. One of the pair-rule genes, even-skipped (eve), appears to be particularly important for the overall segmentation pattern since eve- embryos lack all segmental subdivisions in the middle body region. On the basis of homeo box cross-homology we have isolated a gene, S72, which probably corresponds to eve. In embryo tissue sections S72 transcripts show a periodic distribution pattern. The eve- phenotype appears to involve altered patterns of fushi tarazu and engrailed expression. These and other findings suggest that pair-rule gene expression might involve hierarchical cross-regulatory interactions.

DNA↗
PubMed1986

Ascorbic acid specifically enhances dopamine beta-monooxygenase activity in resting and stimulated chromaffin cells.

Ascorbic acid enhancement of norepinephrine formation from tyrosine in cultured bovine chromaffin cells was characterized in detail as a model system for determining ascorbate requirements. In resting cells, ascorbic acid increased dopamine beta-monooxygenase activity without changing tyrosine 3-monooxygenase activity. [14C]Norepinephrine specific activity was increased by ascorbic acid, while [14C]dopamine specific activity was unchanged. Dopamine content, dopamine biosynthesis, tyrosine content, and tyrosine uptake were also unaffected by ascorbic acid. Furthermore, increased norepinephrine formation could not be attributed to changes in norepinephrine catabolism. Enhancement of dopamine beta-monooxygenase activity was specific for ascorbic acid, since other reducing agents with higher redox potentials were unable to increase norepinephrine formation. The specific effect of ascorbic acid on enhancement of norepinephrine formation was also observed in chromaffin cells stimulated to secrete with carbachol, acetylcholine, veratridine, and potassium chloride. In stimulated cells with and without ascorbate, there were no differences in dopamine content, tyrosine uptake, dopamine specific activity, and norepinephrine catabolism. These data indicate that, under a wide variety of conditions, only one catecholamine biosynthetic enzyme activity, dopamine beta-monooxygenase, is specifically stimulated by ascorbic acid alone in cultured chromaffin cells. This model system exemplifies a new approach for determining ascorbic acid requirements in cells and animals.

Animals↗
PubMed1986

Spatial regulation of Antennapedia and bithorax gene expression by the Polycomb locus in Drosophila.

Transcripts encoded by six of the homeotic lethal complementation groups within the Antennapedia and bithorax gene complexes (ANT-C and BX-C) accumulate primarily in nonoverlapping regions of the embryonic central nervous system (CNS). It has been previously proposed that the maintenance of these selective patterns of expression involve hierarchical cross-regulatory interactions among ANT-C and BX-C loci. Selective expression of the ANT-C and BX-C also involves regulation by a number of unlinked genetic loci, including the Polycomb (Pc) locus. Here we show that the ANT-C and BX-C transcript distribution patterns are dramatically altered in the CNS of Pc- embryos. We discuss these altered patterns of expression in the context of different models for the spatial regulation of ANT-C and BX-C gene expression.

Animals↗
PubMed1986

Histochemical analysis of the ecdysterone-regulated expression of the Drosophila genes P1 and LSP-2.

3H-labeled DNA probes for the ecdysterone-inducible Drosophila genes P1 and LSP-2 were hybridized in situ to RNA in sections of embryos and larvae. Intense hybridization was detected specifically in fat body cells of third-instar larvae and not in other cells of third-instar larvae nor in any cells at earlier stages. These results confirm the stringent tissue- and stage-specificity of P1 and LSP-2 expression. Hybridization of both probes occurred to virtually all the cells in the fat bodies, indicating that both genes are expressed in the same cells. Since P1 expression begins several hours later than LSP-2 expression, and appears to be induced directly by ecdysterone, this finding implies that one or more of the fat body components mediating the response to ecdysterone is gene-specific.

Animals↗
PubMed1986

Analysis of the specificity of natural human antibody reactive to Actinomyces.

The specificity of a frequently-occurring precipitin response to soluble antigens from cell-walls and culture filtrates of A. viscosus ATCC 19246 was examined. After precipitation with isopropanol (50-75% v/v), antigen fractions of different charge and molecular weight were isolated by ion exchange and gel filtration. When heated in mineral acid or alkali above 0.15 M, each of the purified antigens lost precipitating activity, but now inhibited the precipitin reaction between serum and exogenous unheated antigen. The inhibitor was isolated over Biogel P30 and characterized as a peptide fragment (mol. wt about 2 kd) containing approximately 50 moles of ornithine and 6-12 moles, respectively, of aspartate, serine, threonine, glutamate, glycine, alanine and histidine per 100 moles amino acids. The inhibitor was totally destroyed by heating for 1.0 hr in 2.0 M HCl. Variability in the number of fragments and differences in the non-antigenic portions probably accounted for the complexity of the antigens. Ornithine, putrescine, N-acetyl putrescine and various sugars had little or no effect on the precipitin reaction with intact antigen at high concentrations (200 mM), whereas the fragment inhibited completely at 0.4 mM. This indicates that neither ornithine nor its side-chain amides are exclusively recognized by antibody. However, ornithine may be part of a larger sequence and/or important in forming the configuration recognized by the human antibodies.

Actinomyces↗
PubMed1986

Limited dermal ossification: clinical features and natural history.

For 9 years we have observed a girl who has ossification in the dermis with a strikingly limited distribution. Recently a second girl with similar dermal ossification restricted to a single extremity was identified. The ectopic bone is histologically identical to normal membranous bone. These two patients have no obvious underlying cause for soft tissue bone formation, and no disorder of calcium or phosphate metabolism. Ossification first involved the dermal and subcutaneous connective tissue, and with time advanced locally in the affected areas to bridge joints and limit mobility. The ossification has now extended to involve muscle fascia but has not involved the muscle itself. This disease appears to represent a heretofore unrecognized disorder of mesenchymal differentiation.

Bone and Bones↗
PubMed1986

Long-term follow-up of cardiac rhythm in repaired total anomalous pulmonary venous drainage.

Seven consecutive patients with total anomalous pulmonary venous drainage were operated at the Medical College of Ohio at Toledo and long-term follow-up is reported on their rhythm status. The patients were generally under 3 months of age at operation. All patients are alive at the present time. The median length of follow-up is 4 years. Five of the 7 patients demonstrated ectopic pacemaker activity and 2 exhibited episodes of nodal rhythm as well. In general, these were not apparent on standard screening electrocardiography. There was no correlation between the presence or absence of this arrhythmia and the type of repair. It is concluded that arrhythmias may be present in these patients, but that they are unrelated to the type of surgery performed. The ectopic atrial focus may be of no clinical significance but there is more cause for concern in those patients with nodal rhythm.

Arrhythmias, Cardiac↗
PubMed1986

Homeo box gene expression in anterior and posterior regions of the Drosophila embryo.

The homeo box is a 180-base-pair coding sequence that has been implicated in the control of Drosophila development. A common feature of the nine previously reported homeo box genes is their involvement in the establishment of the segmentation pattern of the embryo. In this report we describe the isolation and properties of two additional homeo box genes, F90-2 and S67. Transcripts encoded by the two genes are detected in embryonic tissues that derive from regions near the anterior and posterior poles of the embryo, which are outside the limits of expression of known homeotic genes. These results suggest that at least some homeo box genes specify positional identity along the anterior-posterior body axis that is independent of the process of segmentation.

Amino Acid Sequence↗
PubMed1986

Amenorrhea-galactorrhea due to occult hypothyroidism.

A 25-year-old woman with galactorrhea, oligomenorrhea, hyperprolactinemia, and CT evidence of pituitary enlargement had transsphenoidal microsurgery with initial resolution of hyperprolactinemia, but persistent oligomenorrhea and galactorrhea. In retrospect, she had biochemical evidence of primary hypothyroidism before operation, despite being clinically euthyroid. Administration of thyroid hormone resulted in resolution of the pituitary enlargement and the symptoms.

Adult↗
PubMed1986

Stimulatory effect of ascorbic acid on norepinephrine biosynthesis in digitonin-permeabilized adrenal medullary chromaffin cells.

The regulatory role of ascorbic acid in norepinephrine biosynthesis was studied using digitonin-permeabilized chromaffin cells. When permeabilized chromaffin cells were incubated with [3H]3,4-dihydroxyphenylethylamine ([3H]dopamine) in calcium-free medium, the amounts of radioactive dopamine and norepinephrine measured in the cell fraction were increased as a function of incubation time and dopamine concentration. Both the accumulation of dopamine and the formation of norepinephrine were shown to require the presence of Mg-ATP in the medium. These results indicate that the permeabilization of chromaffin cells by digitonin treatment does not disrupt the functions of chromaffin granules, including dopamine uptake, norepinephrine formation, and storage of these amines. Using this permeabilized cell system, the effect of ascorbic acid on the rates of dopamine uptake and hydroxylation was investigated. The formation of norepinephrine was stimulated by ascorbic acid at concentrations of 0.5-2 mM in the presence of Mg-ATP. By contrast, dopamine uptake was not affected by the presence or absence of ascorbic acid in the medium. These findings provide evidence that ascorbic acid may stimulate the conversion of dopamine to norepinephrine by increasing dopamine beta monooxygenase activity rather than by increasing the substrate supply of dopamine. These observations also suggest that the rate of norepinephrine biosynthesis in adrenal medullary cells may be regulated by the concentration of ascorbic acid within the cell cytoplasm.

Adenosine Triphosphate↗
PubMed1986

T-cell chronic lymphocytic leukaemias and T-cell lymphoma-leukaemia: heterogeneity and anomalous cell markers.

We studied cell surface markers in 8 men with T-cell chronic lymphocytic leukaemia, using fluorescein-conjugated monoclonal antibodies and a cell analyser/sorter. 1 patient's cells had a T-suppressor/cytolytic phenotype (T4-, T8+) and in 3 patients the phenotype was a T-helper cell (T4+, T8-) as described in retrovirus-associated adult T-cell lymphoma-leukaemia. In 4 patients, the cell phenotype was anomalous, with both helper and suppressor antigenic markers (T4+, T8+). Terminal deoxynucleotidyl transferase was positive in 1 of the 4 cases with dual markers. Clinical features and cytological characteristics, including cell size and the density of T8 antigen on the cell surface, showed no obvious correlation with the immunophenotypes, but study of additional cases is needed to evaluate this further.

Aged↗