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Biomedical subjects

R S Verma

Publications and source records attributed to R S Verma.

At least 109 records · Page 6Linked to original sources
PubMed1994

T-cell receptor J beta I/J beta II locus rearrangements concurring with a complex chromosomal aberration in an HTLV-1 positive T-cell lymphoma.

Human T-lymphotropic virus type I (HTLV-1) integration has been associated with the development of adult T-cell leukemia/lymphoma (ATL). Recently, a correlation between T-cell receptor (TCR) gene rearrangements and chromosomal aberrations has been implicated in this leukemia. We present a case of HTLV-1 infected adult T-cell lymphoma that initially presented with a normal karyotype and germline J beta I/J beta II loci. As the disease evolved to the aggressive stage, a complex chromosomal rearrangement with a duplication of chromosome 6p23-->pter translocated to a derivative chromosome 16, was identified by molecular cytogenetic techniques. The nature of this complex abnormality would have been difficult to determine if only conventional banding techniques were performed. Rearrangement involving one J beta allele was also detected at that time. After initiation of chemotherapy, no germline J beta loci were detected, suggesting a possible second rearrangement involving this locus that was homologous. Although no known immune response genes are located at the breakpoints involved in this abnormality, the chromosomal aberration concurred with the initial J beta rearrangement.

Adult↗
PubMed1994

In situ nick translation of human chromosomes with the restriction endonuclease Pvu II [5' CAG decreases CTG 3'].

The treatment of fixed human chromosomes by a number of restriction endonucleases has opened additional avenues towards understanding the mechanism(s) of chromosome banding. Metaphase chromosomes from five unrelated individuals were treated with restriction endonuclease Pvu II [CAG decreases CTG] which has a 6 bp recognition site. The banding patterns were compared with another restriction endonuclease Alu I [AG decreases CT] which recognizes only 4 bp but the recognition sequences are identical. The results demonstrate that the banding pattern of human chromosomes observed by Pvu II digestion are apparently identical to those observed by Alu I. The mechanisms of chromosomal banding are discussed.

Chromosome Banding↗
PubMed1993

Molecular characterization of a complex translocation in a newborn infant.

A newborn infant was referred because of low-set ears, mild downward slant of the palpebral fissures, micrognathia with high-arched palate, a flat midface, small mouth, and thin upper lip with cupid bow configuration. To some extent her cry resembled that associated with cri du chat syndrome. Cytogenetic findings with G- and Q-banding alone failed to characterize precisely the complex translocations. By the chromosome in situ suppression (CISS) hybridization technique using whole chromosome specific probes, a complex 4 breakpoint rearrangement involving both arms of a single chromosome 1 with the long arms of chromosomes 5 and 11 was disclosed, i.e., 46,XX, der(1),t(1;5) t(1;11) (5qter-->5q31::1p31.3-->1q44::11q23-->11 qter;5pter-->5q31::1p31.3-->1pter;11pter-- >11q 23::1q44-->1qter). Gene deregulation and position effect may explain the multiple anomalies in individuals with apparently balanced translocations. The molecular characterization of such cytogenetically balanced translocations may shed some light towards unveiling the clinical consequences associated with aberrations which are presumably balanced.

Abnormalities, Multiple↗
PubMed1993

New translocation involving homologous chromosome 3 in acute myelogenous leukemia (M2)

An apparent balanced translocation involving the long arms of homologous chromosomes is described for the first time in a patient with acute myelogenous leukemia (AML) (M2), i.e., 46,XY,t(3;3) (q21;q26). After reviewing the literature, it was noted that a breakpoint involving band 3q26 is a frequent anomaly in other translocations. Thus, we are tempted to hypothesize that 3q26 band may also play an important role in the pathogenesis of AML (M2).

Adult↗
PubMed1993

Direct visualization of the transposed ABL gene in a duplicated masked Ph chromosome.

In a small percentage of cases of chronic myelogenous leukemia (CML), where the Ph chromosome is masked because of highly complex translocations and sub-microscopic rearrangements, precise identification of chromosomal aberrations by routine banding techniques has been difficult. We report on a new case of CML in which a single copy of a masked Ph chromosome was duplicated during blast crisis, i.e., the karyotype was 47,XY,dir ins(22;9)(q11;q34.1q34.2),t(1;22) (q21;q11), + der (22)t(1;22)(q21;q11). The chromosome in situ suppression hybridization (CISS) technique with whole chromosome 1 and 22 specific painting probes demonstrated that 22q11-qter had been translocated to 1q21, whereas 22q11 was the recipient of 1q21-qter. Furthermore, a cosmid probe identified the location of the ABL gene on only one chromosome 9 (band q34). The other ABL gene could be detected on both derivative chromosomes 22 at band q11 which was flanked by the translocated part of the long arm of chromosome 1, thus providing direct visualization of the ABL insertion in a double masked Ph chromosome. A breakpoint within the 5.8 kb major breakpoint cluster [M-BCR] region was shown by Southern blotting.

Adult↗
PubMed1993

Telomeric repeat [TTAGGG]n sequences of human chromosomes are conserved in chimpanzee (Pan troglodytes).

Using a series of genetic parameters, attempts have been made for more than two decades to establish the close kinship of human (Homo sapiens) with chimpanzee (Pan troglodytes). Molecular and cytogenetic data presently suggest that the two species are closely related. The recent isolation of a human telomeric probe (P5097-B.5) has prompted us to cross hybridize it to chimpanzee chromosomes in order to explore convergence and/or divergence of the telomeric repeat sequences (TTAGGG)n. On hybridization, the human probe bound to both ends (telomeres) of chimpanzee chromosomes, suggesting a concerted evolution of tandemly repeated short simple sequences (TTAGGG)n. Even the terminal heterochromatin of chimpanzee chromosomes was found to be endowed with telomeric repeats, suggesting that evolution of heterochromatin and capping with tandemly repeated short sequences are highly complex phenomena.

Animals↗
PubMed1993

The genomic synteny at DNA level between human and chimpanzee chromosomes.

The evolutionary relationship between human (Homo sapiens) and chimpanzee (Pan troglodytes) has been the subject of debate and scrutiny for over two decades. The close relationship established by numerous parameters may or may not reflect homology at the DNA level. The recent advent of a molecular method termed the chromosome in situ suppression hybridization (CISS)-technique has prompted us to explore the phylogenetic relationship at the DNA sequence level. Cross-hybridization data using human-derived whole chromosome paints (WCPs) suggests an apparent genomic synteny with chimpanzee chromosomes at the DNA level, thus providing a better understanding of an evolutionary relationship between humans and chimpanzees.

Animals↗
PubMed1993

A comprehensive review of medicolegal procedures in service hospitals.

Medicologal service is one of the vital component of hospital services which helps in providing justice to the victim and strengthen the public relations. Any shortcomings in the form of disrespect, negligence and inadvertant delay on the part of hospital staff towards the patient masks the image of the hospital. Some events such as expert evidence, methods of proff, assesment of disability, the work of the medical examiner, Blood groupings, organ transplantation and effectiveness of other tests have great practical importance in providing justice. Steps to deal with medicologal cases effectively and minimising legal complications are enumerated.

Crime↗
PubMed1993

Molecular topography of the secondary constriction region (qh) of human chromosome 9 with an unusual euchromatic band.

Heterochromatin confined to pericentromeric (c) and secondary constriction (qh) regions plays a major role in morphological variation of chromosome 9, because of its size and affinity for pericentric inversion. Consequently, pairing at pachytene may lead to some disturbances between homologous chromosomes having such extreme variations and may result in abnormalities involving bands adjacent to the qh region. We encountered such a case, where a G-positive band has originated de novo, suggesting a maternal origin from the chromosome 9 that has had a complete pericentric inversion. In previously reported cases, the presence of an extra G-positive band within the 9qh region has been familial, and in the majority of those cases it was not associated with any clinical consequences. Therefore, this anomaly has been referred to as a "rare" variant. The qh region consists of a mixture of various tandemly repeated DNA sequences, and routine banding techniques have failed to characterize the origin of this extra genetic material. By the chromosome in situ suppression hybridization technique using whole chromosome paint, the probe annealed with the extra G-band, suggesting a euchromatic origin from chromosome 9, presumably band p12. By the fluorescence in situ hybridization technique using alpha- and beta-satellite probes, the dicentric nature was further revealed, supporting the concept of unequal crossing-over during maternal meiosis I, which could account for a duplication of the h region. The G-positive band most likely became genetically inert when it was sandwiched between two blocks of heterochromatin, resulting in a phenotypically normal child. Therefore, an earlier hypothesis, suggesting its origin from heterochromatin through so-called euchromatinization, is refuted here.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Immunoreactive folate-binding proteins from human saliva. Isolation and comparison of two distinct species.

Human saliva contains a single 72,000-M(r) species which specifically reacted with rabbit anti-[human placental folate receptor (PFR)] serum on SDS/PAGE and Western blots. Although a specific radioimmunoassay for human PFR and related folate-binding proteins (FBPs) identified 55 ng of cross-reacting material (CRM) per mg of crude salivary proteins, only a minor fraction (1.6 ng) specifically bound radiolabelled folate. The major fraction of CRM did not contain bound endogenous folate and did not bind radiolabelled folates. On the basis of folate binding, salivary CRM species to PFR were designated as either functional (f-FBP) or non-functional (nf-FBP) species respectively. nf-FBPs and f-FBPs were isolated by different purification schemes. Both purified f-FBPs and nf-FBPs migrated as a single apparent 72,000-M(r) species on SDS/PAGE, but on Sephacryl S-200 gel filtration and sucrose-density-gradient ultracentrifugation they were eluted/sedimented with 40,000-M(r) markers. Each microgram of purified f-FBP and nf-FBP was measured in the radioimmunoassay for PFR as being equivalent to 18 ng and 24 ng of CRM respectively, indicating low epitope-relatedness to PFR. The Kd of f-FBPs was 50 pM and 0.94 mol of folate was bound/mol of protein. f-FBPs exhibited an unusual dependence on Triton X-100 for optimal ligand binding, despite the fact that Triton X-100 micelle binding was not demonstrated. The relative order of affinity of f-FBPs for pteroylglutamate greater than methotrexate greater than 5-formyltetrahydrofolate greater than 5-methyltetrahydrofolate was also distinct from that of purified PFR. Whereas amino acid and carbohydrate analysis revealed that nf-FBP (M(r) 51,400) and f-FBP (M(r) 39,200) were distinct glycoproteins with 8 and 13% carbohydrate respectively, isoelectric focusing and immunological studies suggested some structural identity. The presence of f-FBP and nf-FBP in normal saliva raises new questions about their possible role in vivo.

Adult↗
PubMed1992

Detection of the heteromorphic spectrum of heterochromatin in the human genome by in situ digestion using restriction endonuclease AluI.

A battery of selective banding techniques has been utilized to identify the heteromorphic markers in the human genome. The recent addition of the AluI/Giemsa (G)-technique has helped not only in identifying the variable sites, but in characterizing their heteromorphic spectra. In the present investigation, we classified the pericentromeric heterochromatin by the AluI/G-technique by its size and position using 50 normal individuals and suggested the potential uses of this banding technique over earlier methods.

Chromosome Banding↗
PubMed1992

Evidence that the hydrophobicity of isolated, in situ, and de novo-synthesized native human placental folate receptors is a function of glycosyl-phosphatidylinositol anchoring to membranes.

Although normal human chorionic villi-associated hydrophobic placental folate receptors (PFR) are converted to hydrophilic forms by an endogenous, EDTA-sensitive, Mg(2+)-dependent protease under serum-free conditions (Verma, R. S., and Antony, A. C. (1991) J. Biol. Chem. 266, 12522-12535), it is not known whether hydrophobic PFR are also susceptible to conversion by endogenous phospholipases. We isolated and characterized hydrophobic PFR, and tested the hypothesis that purified, in situ, and de novo-synthesized native PFR were covalently linked to glycosyl-phosphatidylinositol (GPI) anchors. 125I-hydrophobic PFR, but not 125I-hydrophilic PFR, (i) separated into the Triton X-114 micellar phase at 30 degrees C, (ii) efficiently incorporated into phosphatidylcholine-cholesterol liposomes, and (iii) were covalently labeled by the hydrophobic probe 3-(trifluoromethyl)-3-(meta[125I]iodophenyl)diazirine, [125I]TID. (iv) [125I]TID-labeled- and [phenyl-3H]Triton X-100-bound hydrophobic PFR, as well as native PFR in situ, were released as hydrophilic forms by recombinant (r) GPI-specific phospholipase(PL) C (GPI-PLC), and GPI-PLD (but not by PLC), in the absence and presence of a concentration of EDTA known to inhibit endogenous Mg(2+)-dependent protease. (v) Nitrous acid deamination of [125I]TID-labeled hydrophobic PFR as well as (r)GPI-PLC cleavage of [phenyl-3H]Triton-X-100- and [125I] TID-labeled hydrophobic PFR, released hydrophobic radiolabeled moieties which comigrated on thin layer chromatography distinct from free radiolabel. Finally, (vi) biosynthetic studies on chorionic villi cultured in vitro revealed incorporation of radiolabeled precursors into the GPI anchor of hydrophobic PFR. We conclude that native hydrophobic PFR are linked to GPI anchors and are therefore potential substrates for three distinct endogenous enzymes (GPI-PLC, GPI-PLD, and specific Mg(2+)-dependent metalloprotease) in maternal serum and placenta in vivo.

Affinity Labels↗
PubMed1992

Evolution of pericentromeric heterochromatin of human X chromosome.

An unusual large heterochromatic segment around the pericentromeric region of the X-chromosome is reported. In normal circumstances, the pericentromeric region of the X-chromosome is negative by the restriction endonuclease AluI/Giemsa technique. However, this unusual X-chromosome was found to have AluI resistant (positive) chromatin. The evolution of extra heterochromatin is a postzygotic event as substantiated by the presence of a normal cell line.

Biological Evolution↗
PubMed1992

Molecular characterization of "inverted" pericentromeric heterochromatin of chromosome 3.

Inversion of the pericentromeric region of human chromosome 3 [inv (3) (p11q11.2)] is a rare event. Initially, this inversion was identified with staining for Q-bands by fluorescence using quinacrine (QFQ) and later characterized with staining for C-bands by CBG technique. The molecular methods of fluorescence in situ hybridization (FISH) and AluI/Giemsa and TaqI/Giemsa techniques were utilized. The findings suggest that the variable band q11.2 on chromosome 3 contains alphoid DNA sequences, which appear to be similar to those identified by conventional methods in the centromeric region (band p11).

Adolescent↗
PubMed1992

Chromosomal localization of HTLV-1 viral integration sites using in situ hybridization: detection of a novel IL2R fragment.

The presence of human T-cell leukemia virus (HTLV-1) in patients with adult T-cell leukemia (ATL) was investigated by Southern blotting and in situ hybridization. In all seven patients, HTLV-1 provirus was detected. A large and variable number of labeled restriction fragments were observed, indicating multiple integrations. Two of the patients analyzed by in situ hybridization had two, while the third patient had three, sites of viral integration on six different chromosomes, suggesting random integration. A single site of integration was shared by two patients, which was on chromosome 10 at bands p11-->p15. One of these sites was on an apparently normal chromosome 10 and the other was on a derivative chromosome 10,t(10;14)(p12;q32). The interleukin 2 receptor (IL2R) has previously been localized to this region (10p14-->p15). The alpha-chain of the IL2R is continuously expressed on affected T-cells in this disease. Southern blotting with pIL2R showed the presence of a novel 3.5 kb fragment in five out of the seven patients. This novel fragment has not been previously reported. No direct correlation was found between the novel 3.5 kb fragment, present in patients both cytogenetically normal and abnormal, and viral integration in the 10p11-->p15 region in two patients. Therefore, it is suggested that the presence of the 3.5 kb fragment and the numerous chromosomal breaks associated with this disease may not be direct results of viral integration.

Blotting, Southern↗