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K C Gupta

Publications and source records attributed to K C Gupta.

At least 91 records · Page 5Linked to original sources
PubMed1986

Localization and characterization of Sendai virus nonstructural C and C' proteins by antibodies against synthetic peptides.

Antibodies were raised in rabbits against two synthetic peptides, each 30 residues in length, one corresponding to the predicted common carboxyl termini of the nonstructural C and C' proteins of Sendai virus and the other to the unique amino terminus of the larger C protein. Each peptide was inoculated as a covalent complex with tetanus toxoid or in uncomplexed form. Only antibodies to the free carboxyl-terminal peptide precipitated both C and C' proteins made by in vitro translation of viral mRNA and reacted with the C protein from infected cells. These results confirm that the C and C' proteins are carboxyl-coterminal. Contrasting with the reported colocalization of intracellular measles virus C proteins with nucleocapsid inclusions, immunofluorescence studies revealed that Sendai virus C proteins were uniformly distributed in the cytoplasm whereas the viral P protein was present in inclusions that were mainly perinuclear. Since almost all P protein molecules are associated with viral nucleocapsids, these observations suggested that Sendai virus C protein molecules may be both nucleocapsid-associated and free in the cytoplasm. This interpretation was supported when the C and C' proteins were found in both nucleocapsid and free protein fractions of cell lysates. Anti-C antibodies did not inhibit viral RNA synthesis when added to an extract of infected cells. This result was consistent with the conclusion that the C proteins have no direct role in viral transcription, since virions lack C proteins but are transcriptionally active. Therefore, the functions of the C proteins remain undefined.

Animals↗
PubMed1986

Drug interaction between guanfacine and nonsteroidal antiinflammatory drugs in dogs.

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to attenuate the hypotensive actions of various antihypertensive agents. This experimental study in dogs was undertaken to find out whether NSAIDs modified the pharmacological actions of an antihypertensive drug, guanfacine. Indomethacin and enphenamic acid significantly prolonged the initial hypertensive response and blunted the subsequent hypotension produced by intravenous guanfacine. Ibuprofen and acetyl salicylic acid also interacted in a similar manner, but to a lesser extent. Phenylbutazone, on the other hand, caused a blunting of the pressor response and potentiated the hypotension following guanfacine. When indomethacin was given intracerebroventricularly, there was no interaction. These results suggest the necessity of monitoring hypertensive subjects taking guanfacine when NSAIDs are co-administered.

Animals↗
PubMed1985

Expression of Sendai virus defective-interfering genomes with internal deletions.

Sendai virus strain 7 has been shown to contain four defective interfering (DI) RNA species in which both genome termini and various adjacent fragments of the 3'-terminal NP gene and 5'-terminal L gene are represented, but most or all internal genes and gene boundaries are deleted. Previous sequence analyses of these mutant RNAs suggested that all four possessed the transcription initiation signal of the NP gene and the transcription termination signal of the L gene. The supposition that these signals should specify transcripts has now been supported by oligo(dT) selection of four DI 7 specific RNA species that had apparent molecular weights slightly lower than each DI genome. DI RNA 7a, which contains the entire NP gene, except for two U residues at the end of the poly(A) initiation signal, appeared to be transcribed solely as a readthrough product. Since DI RNA 7a contains the entire NP protein-coding sequence and DI RNAs 7c and 7d contain fragments of it, whereas DI RNA 7b is devoid of it, only transcripts of RNAs 7c and 7d were expected to specify fusion proteins containing NP gene-specific sequences. A strain 7-induced protein that reacted with monoclonal antibodies against the NP protein had the 33,000 Mr size appropriate for the translation product predicted by the sequence of RNA 7d. Other proteins of lower molecular weight were seen only in cells infected by strain 7, but they did not react with NP-specific antibody and their translation in vitro was not blocked by hybridization to an NP gene-specific oligonucleotide. Therefore, at least some of these proteins may be cellular products induced by DI virus infection. These DI transcripts and translation products may influence interference with replication of the parental helper virus.

Antibodies, Monoclonal↗
PubMed1985

Translational modulation in vitro of a eukaryotic viral mRNA encoding overlapping genes: ribosome scanning and potential roles of conformational changes in the P/C mRNA of Sendai virus.

Expression of proteins from three overlapping genes in a single mRNA species of Sendai virus was modulated in a cell-free rabbit reticulocyte translation system. Hybrid-arrested translation by oligodeoxynucleotides complementary to specific regions of the mRNA that specifies the viral P, C, and C' proteins demonstrated that ribosomes scan the RNA from its 5' end to find initiation codons, and suggested that the secondary structure of the mRNA influences the selection of alternative initiation codons. Translational modulation of P, C, and C' proteins by Mg++ and spermidine indicated that RNA folding is involved in this selection process.

Animals↗
PubMed1985

Polytranscripts of Sendai virus do not contain intervening polyadenylate sequences.

Discrete high-molecular-weight RNA species with the properties of polytranscripts were observed in poly(A)-rich RNA extracted from Sendai virus-infected cells. These RNA species were virus specific, being synthesized in the presence of actinomycin D, but not seen in uninfected cells. They were not genome or antigenome fragments, since they were not encapsidated, as shown by their destruction when ribonuclease was added to cell homogenates and by their absence from the RNA fractions that did not bind to oligo(dT)-cellulose. Two lines of evidence indicated that the gene-specific regions of these polytranscripts were not linked by poly(A) sequences, but were faithful copies of virus genomic RNA sequences at gene boundaries. First, a small cDNA clone obtained by reverse transcription of poly(A)-rich RNA species from infected cells contained 90 bases from the 5' terminus of the gene for the P protein and about 600 bases from the 3' end of the downstream gene, which specifies the M protein, the entire cloned sequence being an accurate complement of the genomic RNA. Second, dideoxynucleotide sequencing of poly(A)-rich RNA species primed by virus gene-specific oligodeoxynucleotides revealed read-through products of transcription containing no detectable poly(A). If Sendai virus polytranscripts are intermediates in the production of monocistronic viral mRNAs by a cleavage process, and poly(A) sequences do not link the mRNAs, polyadenylation would have to follow the cleavage step; it seems more likely that these polytranscipts are aberrant transcription products generated by occasional termination failure in a stop-start mechanism of transcription.

Base Sequence↗
PubMed1984

Complete sequences of the intergenic and mRNA start signals in the Sendai virus genome: homologies with the genome of vesicular stomatitis virus.

All of the consensus intergenic and transcription initiation sequences of the genome of Sendai virus, a paramyxovirus, have been determined. The boundary between the intergenic sequence, 3'-GAA, and the mRNA start signal, 3'- UCCCANUUUC , was identified by sequencing the 5' termini of specific viral mRNA molecules. One of the five intergenic trinucleotides differed from the rest, consisting of 3'- GGG , and single base substitutions were observed in two of the mRNA start signals. The Sendai virus intergenic sequence was similar to the analogous sequence (3'-GA) of vesicular stomatitis virus (VSV), a member of another family of negative-strand RNA viruses, the rhabdoviruses , but there was no sequence homology between the mRNA start signals of the two viruses. Nevertheless, these mRNA start signals were organized in the same way, being ten bases long and possessing two consensus regions, divided by one (Sendai virus) or two (VSV) variable internal nucleotides. These findings extend the evidence that both families of negative-strand RNA viruses descended from a common ancestor and that an archetypal mechanism of transcriptional regulation has been conserved in their evolution.

Allantois↗
PubMed1983

Sequence of the 5' end of the Sendai virus genome and its variable representation in complementary form at the 3' ends of copy-back defective interfering RNA species: identification of the L gene terminus.

Direct sequencing showed that the 5' termini of several defective interfering RNA species, both fusion and copy-back types, were homologous to the 5' terminus of the Sendai virus genome. Size analyses of spontaneously formed terminal duplexes (stems) of three copy-back defective interfering RNA species revealed variable extents of terminal complementarity, ranging from about 155 to 210 nucleotides. Direct sequencing of the 3' terminus of one of these copy-back RNA species demonstrated its complementarity to the 5'-terminal sequence of the virus genome. This copy-back sequence contained, in complementary form, the 5' terminus of the L gene, comprising the same sequence, 3'-AUUCUUUUU-5', that was previously identified at the 5' ends of the five other major Sendai virus genes.

Base Sequence↗
PubMed1983

Molecular clones representing Sendai virus genes P, NP and M.

DNA copies of segments of Sendai virus genes P, NP and M, obtained by reverse transcription of virus mRNA species extracted from infected cells, were cloned in plasmid pBR322. Genes were identified by hybrid-arrested translation of viral mRNAs in vitro. Hybrid selection of NP mRNA confirmed the identity of an NP gene clone. Partial sequencing of this insert showed that it represents the 5'-terminal region of the gene, containing transcription termination signals. Hybridization of DNA inserts to blots of electrophoretically separated, denatured mRNA species indicated that the P, NP and M messages had sizes of 2400, 2100 and 1500 nucleotides, respectively. Specific T1 ribonuclease-resistant oligonucleotides, previously identified in the NP and M genes, were selected by hybridization to the respective inserts. Although most of the inserts are smaller than 500 base pairs, representing no more than 16% of the P gene and 24% of the NP gene, one of the M gene inserts, comprising 700 base pairs, represents almost half of that gene. These cloned virus gene segments will assist further investigations of the molecular biology of this model paramyxovirus.

Base Sequence↗
PubMed1983

Genomic and copy-back 3' termini in Sendai virus defective interfering RNA species.

Direct sequencing of nine Sendai virus defective interfering RNA species revealed two kinds of 3'-terminal sequences. Six RNA species had 3' termini identical to the virus genome (negative strand), confirming that internal deletions are a frequent cause of Sendai virus defectiveness. The other three RNA species had 3'-terminal sequences identical to that described as the complement of the 5' terminus of the virus genome (R. A. Lazzarini, J. D. Keene, and M. Schubert, Cell 26:145-154, 1981), indicating that they are of the copy-back type. Extensive homology between these two types of 3' sequences evidently accounts for the ability of the copy-back sequence to function as an initiation signal for viral RNA replication. There may not be a selective advantage of one type of terminus over the other, since one defective interfering strain possessed two RNA species, one of which had the genomic 3' terminus and the other copy-back type.

Base Sequence↗
PubMed1982

Regulation of de novo purine biosynthesis in Chinese hamster cells.

Regulation of de novo purine biosynthesis was examined in two Chinese hamster cell lines, CHO and V79. De novo purine biosynthesis is inhibited at low concentrations of adenine. The mechanism of inhibition was studied using the RNA and protein synthesis inhibitors actinomycin D, cycloheximide, and azacytidine. Although all three inhibitors rapidly inhibited de novo purine biosynthesis in vivo, neither adenine nor the RNA and protein synthesis inhibitors could be found to have an effect in vitro on either phosphoribosylpyrophosphate (PRPP) synthetase or amido phosphoribosyltransferase, the first enzymes of the de novo pathway. However, in the presence of actinomycin D, cycloheximide, and azacytidine, there was a 50% or greater reduction in PRPP concentrations. This reduction in PRPP levels is correlated with a 2-fold increase in purine nucleotides in the acid-soluble pool. It is proposed that in the presence of the metabolic inhibitors there is an increase in nucleotide pools due to degradation of RNA, with a resulting feedback inhibition on de novo purine biosynthesis. In contrast to a previous report (Martin, D. W., Jr., and Owen, N. T. (1972) J. Biol. Chem. 247, 5477-5485), we could find no evidence for a repressor type mechanism in these cells.

Adenine↗
PubMed1982

Effect of low estrogen combination oral contraceptive on metabolism of aspirin and phenylbutazone.

Plasma levels of aspirin and phenylbutazone were estimated before and during administration of low estrogen combination type oral contraceptive for two menstrual cycles in ten and seven female volunteers, respectively. Aspirin was administered at doses of 300 and 600 mg, while phenylbutazone was administered at a dose of 400 mg. Blood samples were collected at intervals of 1, 2, 4, 6, and 8 h for aspirin and 2, 4, 6, 8, 24, 48, 72, and 80 h for phenylbutazone. Plasma levels, plasma half-life (t1/2), as well as area under curve (AUC) for aspirin after use of oral contraceptive revealed lower values. Phenylbutazone levels were not affected. Repeat studies of plasma t1/2 and AUC for aspirin after discontinuation of oral contraceptive showed values similar to basal levels.

Adult↗