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Biomedical subjects

R Ray

Publications and source records attributed to R Ray.

At least 163 records · Page 9Linked to original sources
PubMed1992

Indian hepatitis E virus shows a major deletion in the small open reading frame.

Enterically transmitted non-A, non-B hepatitis virus (HEV), the causative agent for sporadic and large epidemic outbreaks in developing countries, contains a positive-sense single-stranded RNA genome. The genome of the virus encodes three open reading frames (ORF1, ORF2, and ORF3). The gene segment corresponding to the small open reading frame (ORF3), overlapping between ORF1 and ORF2, was synthesized by reverse transcription-polymerase chain reaction (RT-PCR) from a number of previously identified HEV-positive clinical specimens. A DNA fragment of 166 bp was consistently obtained from all the clinical specimens. This small fragment was cloned, sequenced, and found to contain an open reading frame encoding only 41 amino acid residues. Comparison of our results with that of geographically related Burma HEV suggests a major inframe deletion of 246 bp in the ORF3 of Indian strain. The protein encoded by ORF3 does not appear to be useful for early serodiagnosis as a synthetic peptide deduced from the truncated ORF3 failed to show any demonstrable immunoreactivity against HEV-infected acute phase sera in an enzyme-linked immunosorbent assay.

Antibody Formation↗
PubMed1992

Distinct hemagglutinin and neuraminidase epitopes involved in antigenic variation of recent human parainfluenza virus type 2 isolates.

A panel of fourteen neutralizing anti-HN monoclonal antibodies (mAbs) to the prototype Greer strain of human parainfluenza virus type 2 (PI2) was used to determine the extent of antigenic variation in recent virus isolates. Competitive binding analysis with the mAbs indicated the presence of at least five distinct antigenic sites (I to V) on the HN glycoprotein molecule. MAbs recognizing different antigenic sites were found to be associated with the hemagglutinin (sites I, IV and V), hemagglutinin and neuraminidase (site II), or neuraminidase (site III) activities. The location of two distinct epitopes identifying the neuraminidase sites (II and III) was further verified from the generation of escape mutants. Antibodies directed to sites I and III failed to show any detectable binding or neutralizing activity against a number of natural PI2 virus isolates collected in Texas between 1986 and 1987. Interestingly, these natural variants, unlike the prototype virus, did not show any detectable neuraminidase activity with fetuin as a substrate and the enzyme activity was only detected with N-acetylneuramin-lactose as an alternative substrate. Despite the observed variation in the antigenic sites, primary infection with the prototype virus or the natural variants generated a protective immune response against challenge infection with the other virus strains.

Animals↗
PubMed1992

Tibial autogenous cancellous bone as an alternative donor site in maxillofacial surgery: a preliminary report.

This preliminary report reviews the use of the proximal tibial metaphysis as an alternative to other bone graft donor sites. A series of 21 cancellous grafts were procured from 20 patients using a predictable orthopedic approach. A singular finding was the overall lack of morbidity at the donor site and the apparent favorable quality and quantity of the procured bone. Data describing the use of tibial cancellous bone grafting in a wide range of maxillofacial reconstructive procedures are presented.

Adolescent↗
PubMed1992

Unidimensionality of alcohol dependence syndrome?

To evaluate the coherence of Alcohol Dependence Syndrome (ADS), as per DSM-III-R criteria, 72 and 223 subjects with alcohol dependence disorder from Hospital and Community settings, respectively, were interviewed. Nine DSM-III-R criteria assessing the dependence syndrome were factor-analysed. A single factor model provides an adequate description of the interrelationship among the nine criteria and supports the coherence of the dependence syndrome for the hospital sample but not for the community. A two factor model, namely 'withdrawal' and 'social', fits the community data. When the criteria were combined into cumulative scales, they formed good approximations of unidimensional Guttman scales for both the hospital and community settings. For hospital data, preoccupation was the highly central criterion (lambda = 0.95) in defining the dependence syndrome while 'can't stop' (v = 0.11) measured the most severe level of dependence. In the community the 'socially dysfunctional use' identified as a separate secondary factor measured the most severe level of dependence.

Adolescent↗
PubMed1992

Functional interactions between the fusion protein and hemagglutinin-neuraminidase of human parainfluenza viruses.

The fusion glycoprotein (F) and hemagglutinin-neuraminidase (HN) genes of human parainfluenza virus type 2 (PI2) were molecularly cloned and expressed in HeLa-T4 cells by using the vaccinia virus-T7 transient expression system. Expression of the F and HN proteins was detected by using immunoprecipitation and surface immunofluorescence staining. Although the F protein was found to be cleaved into F1 and F2 and expressed on cell surfaces, no cell fusion was observed. However, cotransfection of the F-protein gene together with the P12 HN gene resulted in significant levels of cell fusion. Cell fusion was also observed when separate cell cultures were transfected with the HN and F genes and the F-expressing cells were mixed with the HN-expressing cells. Surprisingly, when the PI2 F protein was expressed together with the parainfluenza virus type 3 (PI3) HN protein, no fusion was detectable in the transfected cells. Similarly, no fusion was found upon coexpression of the PI2 HN and PI3 F proteins. However, coexpression of the PI3 F and HN proteins resulted in extensive cell fusion, which resembled the PI2 coexpression result. These results indicate that under the conditions used, the F protein is unable to cause fusion by itself and the HN protein provides a specific function in cell fusion which cannot be provided by another paramyxovirus attachment protein. Further, the results suggest that a type-specific functional interaction between the F and HN proteins is involved in mediating cell fusion.

Animals↗
PubMed1992

In situ polymerase chain reaction detection of viral DNA, single-copy genes, and gene rearrangements in cell suspensions and cytospins.

The study of low-copy viral or genomic DNA sequences by in situ hybridization (ISH) is often limited by sensitivity. Using the polymerase chain reaction (PCR) for the amplification of target DNA sequences in fixed cells [in situ PCR] (ISPCR) before ISH, we have been able to greatly improve the sensitivity of ISH. Viral DNA present in low copy number, single-copy genes, as well as immunoglobulin gene rearrangements (VH3 family genes), were successfully amplified in cells in suspension or on glass slides (cytospins). Single primer pairs were used in the in situ amplification step and 35S- or digoxigenin-11-dUTP-labeled region specific oligonucleotide probes were used for detection of amplificants by ISH. Artifacts, presumably resulting from leakage of in situ amplificants out of cells, may be a significant problem in selected instances. By optimal fixation and permeabilization of cells, limiting PCR cycle number, amplification of long DNA sequences, and/or incorporation of biotinylated dNTPs to produce bulkier amplificants together with washing of cells after ISPCR, diffusion artifacts were significantly reduced. Probe hybridization to single-stranded long PCR fragments or messenger RNA were excluded as a source for false-positive ISPCR results. The techniques reported dramatically increase the sensitivity of ISH in the detection of low-copy viral infection as well as in the study of gene rearrangements, and provide unique opportunities to study chromosomal translocations and point mutations at the cellular level.

Animals↗
PubMed1992

Visceral leishmaniasis with cysticercosis.

A chest wall nodule in a boy with relapsed proven kala-azar was found to contain a cysticercus. In the fibrous wall with lymphohistiocytic aggregates were mononuclear phagocytes containing amastigotes of L. donovani.

Animals↗
PubMed1992

Intestinal endometriosis.

Two cases with intestinal endometriosis, one with a right iliac fossa mass and the other with subacute intestinal obstruction, are presented. In both the cases, the diagnosis was not suspected clinically and was reached only on histological examination of the resected specimens.

Adult↗
PubMed1992

Gelatinous transformation of bone marrow.

Gelatinous transformation of bone marrow is usually encountered in patients of anorexia nervosa. We report two cases of gelatinous transformation of the marrow, one without any detectable cause and the other associated with visceral leishmaniasis.

Aged↗
PubMed1991

Photoaffinity labeling of human serum vitamin D binding protein and chemical cleavages of the labeled protein: identification of an 11.5-kDa peptide containing the putative 25-hydroxyvitamin D3 binding site.

In this paper, we describe photoaffinity labeling and related studies of human serum vitamin D binding protein (hDBP) with 25-hydroxyvitamin D3 3 beta-3'-[N-(4-azido-2-nitrophenyl)amino]propyl ether (25-ANE) and its radiolabeled counterpart, i.e., 25-hydroxyvitamin D3 3 beta-3'-[N-(4-azido-2-nitro-[3,5-3H]phenyl)amino]propyl ether (3H-25-ANE) (Ray et al., 1986, 1991). We have carried out studies to demonstrate that (1) 25-ANE competes with 25-OH-D3 for the binding site of the latter in hDBP and (2) 3H-25-ANE is capable of covalently labeling the hDBP molecule when exposed to UV light. Treatment of a sample of purified hDBP, labeled with 3H-25-ANE, with BNPS-skatole produced two Coomassie Blue stained peptide fragments, and the majority of the radioactivity was associated with the smaller of the two peptide fragments (16.5 kDa). On the other hand, cleavage of the labeled protein with cyanogen bromide produced a peptide (11.5 kDa) containing most of the covalently attached radioactivity. Considering the primary amino acid structure of hDBP, this peptide fragment (11.5 kDa) represents the N-terminus through residue 108 of the intact protein. Thus, our results tentatively identify this segment of the protein containing the binding pocket for 25-OH-D3.

Affinity Labels↗
PubMed1991

Synthesis of 25-hydroxyvitamin D3 3 beta-3'-[N-(4-azido-2-nitrophenyl)amino]propyl ether, a second-generation photoaffinity analogue of 25-hydroxyvitamin D3: photoaffinity labeling of rat serum vitamin D binding protein.

Vulnerability of 25-hydroxy-[26,27-3H]vitamin D3 3 beta-N-(4-azido-2-nitrophenyl)glycinate, a photoaffinity analogue of 25-hydroxyvitamin D3 (25-OH-D3) (Ray et al., 1986) toward standard conditions of carboxymethylation promoted us to synthesize 25-hydroxyvitamin D3 3 beta-3'-[N-(4-azido-2-nitrophenyl)amino]propyl ether (25-ANE), a hydrolytically stable photoaffinity analogue of 25-OH-D3, and 25-hydroxyvitamin D3 3 beta-3'-[N-(4-azido-2-nitro-[3,5-3H]phenyl)amino] propyl ether (3H-25-ANE), the radiolabeled counterpart of 25-ANE. Competitive binding assays of 25-OH-D3 and 25-ANE with rat serum demonstrated that 25-ANE competes for the 25-OH-D3 binding site in rat serum vitamin D binding protein (rDBP). On the other hand, UV exposure of a sample of purified rat DBP (rDBP), preincubated in the dark with 3H-25-ANE, covalently labeled the protein. However, very little covalent labeling was observed in the absence of UV light or in the presence of a large excess of 25-OH-D3. These results provide strong evidence for the covalent labeling of the 25-OH-D3 binding site in rDBP by 3H-25-ANE.

Affinity Labels↗
PubMed1991

Mithramycin blocks transcriptional initiation of the c-myc P1 and P2 promoters.

The c-myc protooncogene plays an important role in the regulation of cellular proliferation. Mithramycin, a DNA binding antibiotic which binds G-C-rich DNA, inhibits c-myc expression in both differentiating and nondifferentiating cells. The G-C-rich nature of the c-myc promoter suggests that mithramycin may act by directly inhibiting promoter function. The mithramycin binding sites in the c-myc promoter regions were determined by DNAse I footprinting. Particularly prominent mithramycin binding is noted in the regions just 5' of the P1 and P2 promoter TATA boxes. Gel retardation experiments performed in the presence of mithramycin demonstrate that drug binding can prevent the formation of discrete complexes between HeLa cell nuclear proteins and c-myc promoter DNA fragments. Mithramycin also directly blocks the binding of the transcription factor Sp1 to the P1 promoter region. In vitro run-off transcription demonstrates that mithramycin can completely inhibit the in vitro function of both the P1 and P2 promoters. These data suggest that mithramycin inhibits transcription of the c-myc protooncogene by blocking the binding of important regulatory factors, thus preventing formation of the c-myc transcription initiation complex.

Base Sequence↗