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Biomedical subjects

R Gupta

Publications and source records attributed to R Gupta.

At least 793 records · Page 44Linked to original sources
PubMed1985

Transcription and excision of a large intron in the tRNATrp gene of an archaebacterium, Halobacterium volcanii.

The archaebacterium Halobacterium volcanii contains a single expressed gene for tRNATrp. This gene is interrupted, at a position corresponding to two nucleotides 3' to the anticodon, by an 105-base pair intervening sequence. Northern hybridization experiments show that the gene is transcribed in its entirety in vivo into a precursor of at least 180 nucleotides, and that one of the products of post-transcriptional processing is a 105-nucleotide species containing intron-specific sequences.

Base Sequence↗
PubMed1985

Sequence of the 16S rRNA gene from the thermoacidophilic archaebacterium Sulfolobus solfataricus and its evolutionary implications.

The sequence of the small-subunit rRNA from the thermoacidophilic archaebacterium Sulfolobus solfataricus has been determined and compared with its counterparts from halophilic and methanogenic archaebacteria, eukaryotes, and eubacteria. The S. solfataricus sequence is specifically related to those of the other archaebacteria, to the exclusion of the eukaryotic and eubacterial sequences, when examined either by evolutionary distance matrix analyses or by the criterion of minimum change (maximum parsimony). The archaebacterial 16S rRNA sequences all conform to a common secondary structure, with the S. solfataricus structure containing a higher proportion of canonical base pairs and fewer helical irregularities than the rRNAs from the mesophilic archaebacteria. S. solfataricus is unusual in that its 16S rRNA-23S rRNA intergenic spacer lacks a tRNA gene.

Archaea↗
PubMed1985

Protective immunity to systemic nocardiosis in mice immunized with cell extract antigens of Nocardia asteroides.

Mice immunized with crude cell extract antigens of Nocardia asteroides as well as its purified fraction F1 elicited significant levels of both humoral and cellular immune responses. These animals when challenged with 50% lethal dose of N. asteroides, two weeks after the complete immunization exhibited significant protection as seen by decreased mortality and viable counts compared to nonimmunized. The immunized animals were capable of clearing the infection much faster as compared to control. Cell extract antigens which were mainly protein in nature are thought to have a prime role in prevention and restriction of nocardial infection.

Animals↗
PubMed1985

Treatment of un-united fractures of the shaft of the humerus with bent nail.

The results of operative treatment of 78 cases of un-united fractures of the humeral diaphysis are reported. The operation consisted of medullary nail fixation, the nail being bent at the fracture site in order to engage the cortex above and below the fracture, and was followed by plaster splintage. Forty-nine cases showed evidence of union within 20 weeks and 21 united between 20 and 30 weeks. Of the remaining cases, two had broken nails and five were lost to follow-up.

Adult↗
PubMed1985

Immune responses to the protein, carbohydrate and lipid antigens of Nocardia asteroides in experimental nocardiosis in mice.

The intravenous injection of Nocardia asteroides into mice produced systemic nocardiosis involving all the vital organs. Infection of the kidneys and adrenals was more persistent and progressive than in other organs as evidenced by increased bacterial counts and histopathological findings. During the course of the experimental infection, no humoral immune response was detected against various protein antigens up to 4 weeks after challenge, but significant cell-mediated immunity (CMI) was found. Phospholipid antigens elicited only a humoral immune response. The increased CMI responses with protein antigens correlated well with the decreasing bacterial load, which suggested that CMI against proteins was important in the pathogenesis of this disease.

Animals↗
PubMed1985

Immunological responses to protein, carbohydrate and lipid fractions of Nocardia asteroides in mice.

The protein, polysaccharide and phospholipid constituents of Nocardia asteroides have been partially purified and their immunogenicity studied in mice. Humoral and cellular immune responses were demonstrated against a crude cytoplasmic protein fraction (CPF). Two fractions of CPF were prepared on a Sephadex G-200 column; a high mol. wt fraction, fraction-1(F1) was capable of eliciting both types of immune responses, whereas fraction-2(F2) behaved more like a hapten. Phosphatides elicited only humoral responses whereas polysaccharides were non-immunogenic.

Animals↗
PubMed1985

Chlorpropamide-induced cholestatic jaundice and pseudomembranous colitis.

A previously healthy 59-year-old man received chlorpropamide 250 mg/day for adult-onset diabetes. Within 1 month of starting the drug, he developed cholestatic jaundice and pseudomembranous colitis. The colitis worsened during subsequent treatment with multiple antibiotics and sulfasalazine. Oral vancomycin produced a prompt and total remission. One similar case of chlorpropamide toxicity manifested by jaundice and colitis has been previously reported. It is possible that the sulfonamide moiety of the chlorpropamide was implicated in the development of the colitis.

Chlorpropamide↗
PubMed1985

Conversion from cyclosporine to azathioprine in renal graft recipients.

Only one of six patients in whom a clinical diagnosis of rejection was confirmed by both biopsy and FNA benefited from a switch from cyclosporine to azathioprine. Nine patients, in whom nephrotoxicity and rejection could not be separated and in whom the biopsy was positive but the FNA negative, improved when converted to cyclosporine. This improvement was, however, followed by subsequent rejection episodes in four of these patients. This study suggests caution in changing from CsA therapy in patients with unstable function.

Azathioprine↗
PubMed1985

Serial biopsy controlled evaluation of fine needle aspiration in renal allograft rejection.

Transplant fine needle aspiration (FNA) cytology has been suggested as a method for monitoring intrarenal changes of acute rejection after transplantation. We studied this technique by sampling dog renal allografts daily with simultaneous FNA's and core needle biopsies from the time of transplantation to complete rejection. Individual FNA's were analyzed by the increment method, subtracting peripheral white blood cell counts from aspirated white blood cell counts to define the composition and extent of interstitial mononuclear infiltrate. The increment for each mononuclear cell type was corrected by a factor related to its immunologic relevance and the new values summed to produce the total corrected increment, an index of rejection. FNA findings were compared to histologic sections graded 0 to 4 according to the extent of mononuclear infiltrate that was present. FNA sample adequacy was assessed by the aspirate sampling index (ASI), the concentration of renal tubular cells per high power microscopic field. Mean FNA increments for all mononuclear cell groups increased as rejection progressed histologically. Mean total corrected increment ranged from 0.9 with no rejection to 9.8 with grade 4 rejection (R = 0.73; p = 0.001). Mild and moderate infiltrates were detected more accurately when ASI was at least 0.25, while denser infiltrates could be detected in samples with lower ASI. These findings indicate FNA can identify the mononuclear infiltrate associated with acute rejection and the FNA score correlates with the magnitude of the infiltrate if the parenchymal component of the sample is large enough. The ASI is of value in evaluating the samples and reducing the likelihood of false-negative interpretations.

Animals↗
PubMed1984

Probing the structure of 16 S ribosomal RNA from Bacillus brevis.

A majority (approximately 89%) of the nucleotide sequence of Bacillus brevis 16 S rRNA has been determined by a combination of RNA sequencing methods. Several experimental approaches have been used to probe its structure, including (a) partial RNase digestion of 30 S ribosomal subunits, followed by two-dimensional native/denatured gel electrophoresis, in which base-paired fragments were directly identified; (b) identification of positions susceptible to cleavage by RNase A and RNase T1 in 30 S subunits; (c) sites of attack by cobra venom RNase on naked 16 S rRNA; and (d) nucleotides susceptible to attack by bisulfite in 16 S rRNA. These data are discussed with respect to a secondary structure model for B. brevis 16 S rRNA derived by comparative sequence analysis.

Bacillus↗
PubMed1984

Halobacterium volcanii tRNAs. Identification of 41 tRNAs covering all amino acids, and the sequences of 33 class I tRNAs.

Transfer RNAs of Halobacterium volcanii, an archaebacterium, were separated by two-dimensional gel electrophoresis and sequenced by a combination of methods. A total of 41 tRNAs, at least one for each amino acid, were identified. These are five tRNAs for Leu, four for Gly, three each for Ala, Arg, Pro, and Ser, two each for Glu, Ile, Lys, Met (initiator and noninitiator), Thr, and Val, and one each for the remaining eight amino acids. As in eucaryotes, only Leu and Ser tRNAs are class II (large extra arm). The sequences of the 33 class I tRNAs, for the remaining 18 amino acids, are presented here. These cover at least 44 codons out of a possible 49 codons for the 18 amino acids. Although these archaebacterial tRNAs follow general tRNA patterns, they are in detail distinct from both eucaryotic and eubacterial tRNAs. Moreover, the initiator tRNA is unique in having a 5'-triphosphorylated end.

Amino Acids↗
PubMed1984

Mutants of chinese hamster ovary cells affected in two different microtubule-associated proteins. Genetic and biochemical studies.

Several colchicine-resistant (ColR) mutants of a Chinese hamster ovary cell line, PodRII6, which has earlier been shown to be affected in a microtubule-associated protein (referred to as P1 in these studies), have been isolated. Gel electrophoretic analyses show that one of the ColR mutants (ColR22) contains an additional new protein spot (designated as M2; Mr congruent to 70,000) that is derived by a mutational alteration in a neighboring more acidic protein P2 present in both PodRII6 and ColR22 cell lines. Studies on the relative amounts of the M2 and P2 proteins (and also the M1 and P1) in the ColR22 mutant and hybrid (i.e. ColR22 X PodS) cells are in accordance with the codominant behavior of the mutations and provide evidence that in the ColR22 mutant only one of the two copies of the genes for these proteins has been mutated. The two proteins which are affected in this mutant have been shown to constitute microtubule-associated proteins by a number of criteria. (i) These proteins along with tubulins are specifically released upon Ca2+ treatment of detergent-extracted cytoskeletons containing microtubules, but not if microtubules have been destroyed by prior treatment with colchicine. (ii) Cold treatment of a microtubule-containing fraction also releases the same set of proteins as in criterion i above. (iii) When the mutant cells are treated as in criterion i or ii, then along with the wild type forms, the mutant forms of the above proteins are also found in the microtubule-specific fractions. The cell extracts from PodRII6 and ColR22 mutants show reduced binding of both [3H] podophyllotoxin and [3H]colchicine, indicating that the above proteins are involved in the binding of these drugs to microtubules. It is suggested that the proteins P1 and P2, which are present in Chinese hamster ovary cells in nearly equimolar amounts with (alpha + beta)-tubulins, may comprise important microtubule structural components.

Animals↗