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Biomedical subjects

R Misra

Publications and source records attributed to R Misra.

At least 19 recordsLinked to original sources
PubMed1995

Oocyte activation and passage through the metaphase/anaphase transition of the meiotic cell cycle is blocked in clams by inhibitors of HMG-CoA reductase activity.

Cell cycle progression for postembryonic cells requires the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-R), the enzyme which catalyzes the production of the isoprenoid precursor, mevalonate. In this study, we examine the requirements of HMG-R activity for cell cycle progression during the meiotic and early mitotic divisions using oocytes and dividing embryos from the surf clam, Spisula solidissima. Using two different inhibitors of HMG-R, we find that the activity of this enzyme appears to be required at three distinct points of the cell cycle during meiosis. Depending on the stage at which these inhibitors are added to synchronous clam cultures, a reversible cell cycle block is triggered at the time of activation or at metaphase of either meiosis I or II, whereas there is not block to the mitotic cell cycle. Inhibition of HMG-R activity in activated oocytes does not affect the transient activation of p42MAPK but results in a block at metaphase of meiosis I that is accompanied by the stabilization of cyclins A and B and p34cdc2 kinase activity. Our results suggest that metabolites from the mevalonate biosynthetic pathway can act to influence the process of activation, as well as the events later in the cell cycle that lead to cyclin proteolysis and the exit from M phase during clam meiosis.

Animals↗
PubMed1995

Compound heterozygosity of HLA-DR4 and DR1 antigens in Asian Indians increases the risk of extra-articular features in rheumatoid arthritis.

The relationship of HLA-DR antigens in rheumatoid arthritis (RA) patients with the presence of rheumatoid factor (RF), extra-articular features, joint erosions, functional status and response to disease modifying anti-rheumatic drugs (DMARDs) was studied. Seventy-four patients with RA were serologically typed for class II antigens. Clinical features were recorded before starting DMARDs and during follow-up to assess response and side-effects. HLA-DR1 and DR4 antigens were present more frequently in patients with RA than in the general population. The presence of DR4 correlated with RF seropositivity (P < 0.001) while DR1 was associated with seronegativity (P < 0.02). Ten of the 11 patients with extra-articular features had DR1 and/or DR4. Patients with both DR4 and DR1 had a significantly higher frequency of extra-articular features compared with those with only one of these (P < 0.01). HLA-DR4 and DR1 had no relation with the presence of subcutaneous nodules, erosive changes, deformities, response to drugs and side-effects of DMARDs.

Adult↗
PubMed1995

Arthritis in scleroderma.

Thirty-four patients (24 females and 10 males) selected from 300 consecutive patients with established systemic sclerosis (SSc), with a current or past history of articular symptoms, were clinically documented and further studied using thermography and bone scan to define the pattern of arthritis. Clinical evidence of synovitis was observed in 30 (88%) and joint inflammation was detected in 31 (91%) by the above-mentioned imaging techniques. A distinctive subset of 10 patients with deforming arthritis was characterized in which seven (70%) patients fulfilled criteria for both rheumatoid arthritis and SSC; three of these satisfied the criteria for diagnosis of CREST, but none met the criteria of mixed connective tissue disease. These patients, as a group, when compared with the rest showed limited skin involvement (skin score of 19 +/- 11 vs 33 +/- 14; P < 0.05) and were positive for rheumatoid factor (80 vs 13%; P < 0.05) and anticentromere antibodies (37 vs 4%; P < 0.05).

Adult↗
PubMed1995

Molecular analysis of asmA, a locus identified as the suppressor of OmpF assembly mutants of Escherichia coli K-12.

We present the molecular characterization of the asmA gene, whose product is involved in the assembly of outer membrane proteins in Escherichia coli K-12. The asmA locus was initially identified as a site for suppressor mutations of an assembly defective OmpF315. Our data suggest that these suppressor mutations either completely abolish or reduce asmA expression and can be complemented in trans by plasmid clones carrying asmA sequences. The recessive nature of asmA suppressor mutations suggests that the functional AsmA protein participates in inhibiting the assembly of OmpF315 and other mutant OmpFs. As the assembly of wild-type and parental OmpF proteins was not affected by asmA mutations, AsmA must provide an environment refractory only to the assembly of mutant OmpF proteins. However, we cannot completely rule out the possibility that AsmA plays a minor role in the assembly of wild-type and parental OmpF in wild-type cells. The presence of a putative signal sequence within the amino-terminal sequence of AsmA suggests that it is either a periplasmic or an outer membrane protein. This predicted location of AsmA is compatible with its role in the assembly of outer membrane proteins.

Alleles↗
PubMed1994

1,N6-etheno deoxy and ribo adenosine and 3,N4-etheno deoxy and ribo cytidine phosphoramidites. Strongly fluorescent structures for selective introduction in defined sequence DNA and RNA molecules.

Synthesis of 1,N6-etheno-2'-deoxyadenosine, 3,N4-etheno-2'-deoxycytidine, and further chemistry on both deoxy and ribo series etheno nucleosides produces the corresponding phosphoramidites. These novel phosphoramidites are introduced selectively, quantitatively, and at specific positions at single or multiple sites into DNA or RNA sequences. The purification and chemistry involved in the synthesis of these products has been optimized to achieve the purity in excess of 99%. The resulting phosphoramidites were tested for their ability to couple and produce poly deoxy and ribonucleotides by solid phase chemistry. The coupling efficiency achieved was greater than 99% per step. Due to the instability of these etheno compounds in acidic and basic medium, various criteria to obtain pure oligomers have been established. The selective introduction of these fluorescent nucleosides into defined sequence DNA and RNA molecule will greatly facilitate the structure-function studies of various RNAs, protein-RNA structures, and DNA-RNA based diagnostics applications. The characteristic and high fluorescent intensity (detection below 1 x 10(-9) M for adenosine sites and below 1 x 10(-7) M for cytidine sites) is particularly suited for the biochemical and biological research and product development applications. The usefulness of these etheno containing modified sequences as sequencing and amplification primers is demonstrated by their full participation in polymerase chain reaction experiments.

Base Sequence↗
PubMed1994

Juvenile chronic arthritis in India: is it different from that seen in Western countries?

Medical records of 89 children with juvenile chronic arthritis attending the clinical immunology outpatient department of a tertiary care hospital were analysed. Polyarticular type of juvenile chronic arthritis was the most common, followed by pauciarticular and systemic onset types. No patient with the early onset pauciarticular disease subset, which is associated with iridocyclitis and antinuclear antibody (ANA) positivity was seen. Uveitis was observed in only one patient with late onset pauciarticular disease. The ANA positivity rate (1/89) was very low. Polyarticular onset type disease had a higher incidence of deformities.

Acute-Phase Proteins↗
PubMed1994

Serum IgM rheumatoid factor by enzyme-linked immunosorbent assay (ELISA) delineates a subset of patients with deforming joint disease in seronegative juvenile rheumatoid arthritis.

Using human IgG as an antigen in an enzyme-linked immunosorbent assay (ELISA), we looked for the presence of IgM rheumatoid factor (RF) in the sera of 74 children with juvenile rheumatoid arthritis (JRA). Nine children had RF detectable by both latex agglutination and ELISA. Forty-five percent (26 of 65) of the children who were seronegative by latex agglutination were found to be positive for IgM RF by ELISA. The prevalence of IgM RF was higher in patients with polyarticular onset disease (57.4%) than in those with pauciarticular onset (38.5%) or systemic onset (27.2%) disease. The prevalence of RF was higher in sera from patients with deforming joint disease than those without deformities (P < 0.01).

Adolescent↗
PubMed1994

Effective control of cisplatin induced emesis by combination drug regimen.

Thirty two cycles of chemotherapy were administered to sixteen patient containing 50-75 mg/msq. of cisplatin. For antiemetic prophylaxis, each patient received metoclopramide alone in the first cycle and a combination of metoclopramide + dexamethasone + lyrazepam in the next cycle. Effective control of emesis was achieved in 81% cycles on the combination antiemetic regime as compared to 19% on MCP alone. There was no statistical difference in the relief of nausea by the two regimens.

Adult↗
PubMed1993

A novel ompC mutation of Escherichia coli K-12 that reduces OmpC and OmpF levels in the outer membrane.

A novel ompC mutation was isolated that not only lowered the amount of its own product, OmpC27, but also reduced the level of OmpF present in the outer membrane. ompC27 codes for a mutant OmpC protein that contains two non-native cysteine residues. The ompC27 allele confers phage resistance by lowering the level of OmpC present in the outer membrane. This effect on OmpC27 was manifested at the level of assembly as a result of disulphide bond formation between the two cysteine residues. This disulphide bonding in OmpC27 also produced a novel phenotype by specifically influencing OmpF levels. The effect of OmpC27 on OmpF was partly a result of a lowering of ompF transcription, and partly a result of an effect at the post-transcription level. The transcriptional effect is likely to be brought about by a defective membrane as a result of the insertion of the disulphide bond containing OmpC27. The post-transcriptional effect of OmpC27 on OmpF could be due to interference at the assembly level. In a dsbA::kan1 background where the in vivo disulphide bonding ability was dramatically reduced, the OmpC27-mediated effects were also curtailed.

Bacterial Outer Membrane Proteins↗
PubMed1992

Scleromyxoedema with features of systemic sclerosis.

The case is described of a patient with scleromyxoedema with features typical of systemic sclerosis. The features were so characteristic that the disease was misdiagnosed as systemic sclerosis. A brief review of the association of the two diseases is given.

Adult↗
PubMed1991

A genetic approach for analyzing the pathway of LamB assembly into the outer membrane of Escherichia coli.

Results presented in this study demonstrate that a mutation which inserts an additional tyrosine between the 2 tyrosines at residues 118 and 119 of mature LamB protein results in a temperature-dependent assembly defect. This defect leads to the accumulation of an intermediate at the restrictive temperature that is most likely an assembly-defective monomer. These monomers are rapidly degraded in the wild type (htrA+) strain, and the biphasic kinetics of this degradation indicate that the mutation affects the assembly process and not the final product, i.e. stable trimers. In addition, our data show that the temperature-dependent assembly defect in the mutant strain is reversible, and therefore the accumulated monomers represent a true assembly intermediate. Fractionation studies show that the monomers, which can be accumulated in htrA (degP) mutants at the restrictive temperature, are associated with the outer membrane, indicating that trimerization of LamB is not a prerequisite for localization.

ATP-Binding Cassette Transporters↗
PubMed1991

Nur77 is differentially modified in PC12 cells upon membrane depolarization and growth factor treatment.

The rat pheochromocytoma cell line PC12 can be induced by growth factors to undergo proliferation and neuronal differentiation. These cells also have excitable membranes that can be depolarized by neurotransmitters or elevated levels of extracellular KCl. Treatment of PC12 cells with growth factors or membrane-depolarizing agents rapidly activates the expression of specific genes whose products are thought to mediate the subsequent biological responses. One such gene, nur77, is a member of the steroid and thyroid hormone receptor gene superfamily. We have identified the Nur77 protein and shown that it is synthesized rapidly and transiently in PC12 cells following stimulation, has a short half-life of 30 to 40 min, and is located in both the nucleus and the cytoplasm. Nur77 is posttranslationally modified, primarily by phosphorylation on serine residues. Phosphopeptide analysis reveals that Nur77 is modified differently upon membrane depolarization than after treatment with growth factors. We hypothesize that the activity of Nur77 is regulated by both differential gene expression and posttranslational modification and that these modes of regulation contribute to distinct downstream responses specific to membrane depolarization and growth factor treatment.

Adrenal Gland Neoplasms↗
PubMed1991

Occurrence of systemic autoimmune disorders & autoantibodies in house-hold contacts of patients with systemic lupus erythematosus.

Household contacts of 22 randomly selected patients with systemic lupus erythematosus (SLE) were screened for autoimmune diseases and autoantibodies. Thirty nine consanguineous and 17 nonconsanguineous household contacts were studied. In the first group symptomatic SLE was seen in 5 per cent, rheumatoid arthritis in 2.5 per cent, antinuclear antibody (ANA) in 10 per cent and rheumatoid factor (RF) in 5 per cent while anti-dsDNA, anti-nRNP and anti-Sm antibodies were not detected in any individual. The second group showed total absence of any marker of autoimmunity. In normal controls only RF was detected in 3 per cent. The occurrence of markers of autoimmunity only in consanguineous household contacts of patients with SLE further confirms the recognised role of genetic factors in the etiology of SLE.

Aged↗