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Biomedical subjects

M Verma

Publications and source records attributed to M Verma.

At least 127 records · Page 7Linked to original sources
PubMed1989

Dental caries and periodontal diseases--a hospital based study.

Two thousand children aged 3 to 12 years, attending the Pediatric Outdoor and Well Baby Clinic were examined to find the prevalence of dental caries (DC) and periodontal diseases (PD). DC was detected in 55.75% whereas PD were present in 9.35% children. Even 3 to 5 years old were found to have a significant prevalence of the diseases. Children with an urban background, irregular brushing habits and malnutrition had significantly higher prevalence of both the diseases.

Child↗
PubMed1988

Corticosteroids suppress cyclooxygenase messenger RNA levels and prostanoid synthesis in cultured vascular cells.

Prostacyclin synthesis by cultured vascular smooth muscle cells was inactivated by aspirin. Recovery required serum factors replaceable by EGF plus TGF-beta and was blocked by cycloheximide but not by actinomycin D. Recovery of cyclooxygenase activity was prevented by preincubation with dexamethasone (0.1 to 2 microM), which also suppressed basal enzyme activity by up to 70%. A full length 2.8 Kb cDNA hybridization probe for human cyclooxygenase identified a cyclooxygenase messenger RNA of approximately 2.8 Kb in these cells. Cyclooxygenase mRNA levels were enhanced by EGF/TGF-beta, but suppressed completely by corticosteroids. It is concluded that inhibition of prostanoid synthesis by corticosteroids is mediated by suppressing cyclooxygenase messenger RNA. These observations provide a new molecular mechanism for the anti-inflammatory activity of the corticosteroids.

Adrenal Cortex Hormones↗
PubMed1988

Tumor necrosis factor-enhanced leukotriene B4 generation and chemotaxis in human neutrophils.

In an in vivo study of five normal volunteers infused with endotoxin (20 U/kg of US reference endotoxin lot EC-5), increased neutrophil (PMN) generation of leukotriene B4 and chemotaxis to leukotriene B4 were found concomitantly with elevated plasma tumor necrosis factor (TNF) levels. To clarify the role of TNF in PMN activation, neutrophil responsiveness after in vitro treatment with TNF was examined. Neutrophils from seven normal subjects were incubated with TNF for 30 minutes and tested for chemotaxis to leukotriene B4, formyl-methionyl-leucyl-phenylalanine and zymosan-activated serum, or the calcium ionophore A23187 to assess leukotriene B4 generation. A range of 10(-13) to 10(-9) mol/L of TNF was used for these assays. When 10(-9) mol/L of TNF was used, the amount of leukotriene B4 that was produced was significantly greater than in control cells. The effect of TNF on PMN chemotaxis was uniformly inhibitory for the three stimuli at 10(-10) mol/L compared with untreated cells. At a picomolar range, PMN migration to leukotriene B4, but not to zymosan-activated serum or formyl-methionyl-leucyl-phenylalanine, was significantly increased over that of PMNs not exposed to TNF. This suggests that TNF has a specific facilitatory effect on PMN responsiveness for both leukotriene B4 production and chemotaxis to leukotriene B4 and may be the same signal for this phenomenon in endotoxemic patients.

Calcimycin↗
PubMed1987

Phylogenetic implication of heterogeneity of the nontranscribed spacer of rDNA repeating unit in various Neurospora and related fungal species.

Nontranscribed spacer (NTS) regions of ribosomal (r)RNA genes are non-conserved and are shown to be useful for phylogenetic studies. 32P-labelled N. crassa NTS pCC3400 DNA, was used as a molecular probe to hybridize Southern blots of genomic DNAs obtained from Neurospora, Gelacinospora, Sordaria, bacteria, plants, and animals. Our studies conclude that: (a) the homotahllic species of Neurospora should not belong to genus Gelacinospora (a historical question) and that Neurospora homothallic species are closer to Gelacinospora than to Sordaria; and that (b) all of the filamentous fungal species tested are indeed closer to the higher plant genome than to higher primate animal genome based on shared restriction sites of 12 enzymes. Our studies also demonstrate the usefulness of nontranscribed rRNA gene probes in resolving questions regarding phylogenetic relatedness between widely separated organisms using the parsimony principle based on mutation sites from DNA restriction maps; it has not been possible to do this using DNA: DNA hybridization procedures that involved the total genome.

DNA Restriction Enzymes↗
PubMed1987

Neurospora crassa nuclear genome contains analogy of Saccharomyces cerevisiae genes for ribosomal RNA processing.

Neurospora crassa wild type genome shows DNA sequences which are homologous to the sequences present in the rRNA processing genes of the yeast Saccharomyces cerevisiae. Five such processing genes from yeast, viz., RNA1 through RNA5, cloned in plasmid pBR322 were transformed in Escherichia coli strain LE392. Southern blots containing DNAs from these clones were restricted with several restriction endonucleases along with DNAs from lambda phage, rice (plant) and neuroblastoma (animal), were hybridized with 32P-labelled nick-translated N. crassa nuclear DNA under very stringent conditions. Autoradiograms of these blots revealed that four yeast rRNA processing genes (RNA1, RNA2, RNA3, and RNA4) showed homology with N. crassa nuclear DNA but such analogs were not found in DNAs representing prokaryotes, phages, higher plants and animals.

Cell Nucleus↗
PubMed1987

Serotonin in tension headache.

Serotonin (5-hydroxytryptamine, 5-HT) is implicated in the pathogenesis of migraine; however, its role in tension headache has not yet been studied. The uptake of 5-HT by platelets in patients of tension headache was significantly higher compared with migraineurs as well as controls. The basal platelet 5-HT levels did not show a significant difference. The study implicates the role of serotonin in tension headache.

Adult↗
PubMed1987

Isolation and characterization of non-neuronal enolase (NNE) from Neurospora crassa and comparison with neuron specific enolase isolated from neuroblastoma cell line NG108.

Enolase is a vital enzyme of the glycolytic pathway. It exists mainly in two forms, non-neuronal enolase (NNE) and neuron specific enolase (NSE). Neurospora crassa, a filamentous fungus, was used as the source of pure NNE, and by using DEAE-cellulose and a Sephadex G-150 column chromatography highly purified enzyme (20.4 fold purification with 54.7 percent recovery) was obtained. The development profile of the enzyme shows a peak value after 90 hours of mycelial growth from conidia of N. crassa. In this respect, it differs from neuroblastoma NSE where the peak value of the enzyme activity appears 7 1/2 hours after the splitting of the cells. N. crassa enolase (NNE) is more thermolabile than NG108 NSE and N. crassa enolase is more sensitive to urea, chloride, and fluorophosphate. The Km values for 2-phosphoglycerate and Mg++ were 0.34 mM and 0.47 mM, respectively, for N. crassa enolase, whereas these values were 1.1 mM and 3.1 mM, respectively, in the case of neuroblastoma NSE. N. crassa enolase is a dimer molecule of molecular weight 85,000 daltons. N. crassa enolase is not neutralized by NSE antisera and neutralized by NNE antisera as opposed to neuroblastoma NSE.

Cell Line↗
PubMed1986

Sulphinpyrazone and the platelet serotoninergic mechanism in ischaemic heart disease.

A double blind study in 25 patients with ischaemic heart disease and 20 matched healthy controls examined the effect of sulphinpyrazone on the uptake of serotonin by platelets and the basal concentrations of serotonin in platelets. Uptake was measured using tritium labelled serotonin and basal concentrations estimated spectrophotofluorometrically. Serotonin uptake was significantly increased both in the patients with chronic stable angina of effort and in those with a history of myocardial infarction six months or more previously. Sulphinpyrazone reduced serotonin uptake from 94.25 (SE 8.65) to 57.86 (5.37) cpm/10(8) platelets after 24 weeks of treatment in the group with stable angina and from 137.45 (16.26) to 68.08 (8.38) cpm/10(8) platelets in the myocardial infarction group. Raised basal concentrations in the two groups were also reduced by sulphinpyrazone. Placebo had no effect on serotonin uptake or basal concentrations in either group of patients. The ability of sulphinpyrazone to inhibit uptake and reduce basal concentrations of serotonin in patients with ischaemic heart disease may be yet another mechanism through which this drug exerts its beneficial antiplatelet effect.

Adult↗
PubMed1986

Isolation of temperature-sensitive mutants of bacteriophage MB78 and correlation between the physical and genetic maps.

In order to study the biochemistry and genetics of the virulent virus MB78 of Salmonella typhimurium, 31 temperature-sensitive mutants of the phage were isolated following mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. These have been classified into six complementation groups (A through F). Linkage between different complementation groups has been mapped by using two factor crosses between representative members of each group. To correlate the physical and genetic maps of the phage, complementation between bacterial clones carrying plasmids with EcoRI fragments of the phage DNA as inserts and the ts mutants was studied. Good correlation between the physical and genetic maps has been obtained. Tentative locations of the ts mutations on the phage genome have thus been determined.

Alleles↗
PubMed1986

Endosulfan induced inhibition of 3H-5-hydroxytryptamine uptake in platelets.

Endosulfan, a chlorinated pesticide, is widely used to control various insect pests. Rats exposed to 1 mg and 3 mg endosulfan/kg for periods of 10, 30, and 60 days showed significant (P less than 0.05) inhibition of [3H]5-hydroxytryptamine (5-HT) uptake by platelet-rich plasma (PRP) in an ex vivo study. Rats treated with endosulfan (1 and 3 mg/kg) up to 60 days elucidated a marked inhibition of ADP-induced aggregatory responses of the platelets. Incubation of PRP with 10 microM and 100 microM endosulfan for 15 min at 37 degrees C also resulted in significant (P less than 0.05) inhibition of platelet aggregation in vitro. The paper discusses the use of rat blood platelets as a model for the study of neuro- and cardiovascular toxicity of endosulfan.

Animals↗
PubMed1986

Purification and characterization of bacteriophage 9NA lysozyme.

Bacteriophage 9NA is a virulent phage of Salmonella typhimurium which induces a lysozyme in host cells toward the later stages of its multiplication. 9NA lysozyme has been purified about 1000 fold starting from the lysate of 9NA infected cells. The enzyme has an optimum pH between 7 and 8 and its activity is dependent on the ionic strength of the assay medium. Salts like NaCl and KCl are inhibitory to the lysozyme. Gram-negative cells act as better substrate for the lysozyme than do Gram-positive cells. The enzyme has a molecular weight of about 2.1 X 10(4) and rapidly loses its activity at temperatures higher than 45 degrees C. The properties of 9NA lysozyme have been compared with those of T4, lambda and P22 lysozymes.

Enzyme Induction↗
PubMed1986

Purification and properties of RNA polymerase of phage KB1.

Bacteriophage KB1 belongs to group C of Bradely's classification After infection a bacteriophage specific RNA polymerase is induced in infected cells. KB1 RNA polymerase is a stable enzyme and is easily purified to homogeneity in good overall yield. The activity resides in a single polypeptide chain of molecular weight about 90,000. Synthesis of RNA by KB1 RNA polymerase requires a DNA template and Mg++ and like SP6 RNA polymerase, is strongly stimulated by either bovine serum albumin or spermidine. Thiol reactive reagents inhibit the enzyme, suggesting the presence of essential sulfhydryl residues. The enzyme possess a stringent promoter specificity. The KB1 RNA polymerase is also highly active in synthesis of poly(rG) with poly(dI).(dC) as template. My experiments suggest that the catalytic portion of the polymerase can be separated from the RNA polymerase holoenzyme.

Chloromercuribenzoates↗
PubMed1986

Purification and characterization of enolase from neuroblastoma cell line NG108.

Neuroblastoma Cell line NG108 (a hybrid from Chinese hamster and mouse) produces high levels of enolase. Using ion-exchange chromatography and gel filtration, we have purified the enzyme (about 19 fold purification) and characterized it. The purified enzyme is a dimer of 90,000 m.wt. and is stable at room temperature. At higher temperatures (e.g., 50 degrees, 60 degrees C etc.) it gets inactivated. Enolase requires Mg++ for its activity and is resistant to urea. The optimum pH for the enzyme is 7, and Km values for Mg++ and 2-phosphoglycerate were found to be 3.1 and 1.1 mM, respectively. Fluorophosphate is a strong inhibitor of the enzyme. The clinical applications of the enzyme have been discussed.

Animals↗
PubMed1985

Hybrid between temperate phage P22 and virulent phage MB78.

Bacteriophage MB78, a virulent phage of Salmonella typhimurium can not grow in rifampicin resistant mutant of the host. However, the temperate phage P22 which grows normally in this host helps MB78 to grow in its non-permissive host. P22 can not itself multiply under the condition of mixed infection and the burst size of MB78 is very much reduced. The burst sizes of both are reduced even when the permissive host LT2 is mixedly infected with P22 and MB78. When rifampicin resistant mutants are mixedly infected, only P22-specific mRNAs are produced in the early stage. This is followed by transcriptions from both P22 and MB78 genomes. Subsequently, only MB78-specific messengers are detected in the infected host. Hybrids between the two phages have been isolated from the mixedly infected cells. These hybrids which contain only 15-20% of P22 genome can grow in the rifampicin resistant mutants of the host. The analysis of hetero-duplex between MB78 and hybrid phages revealed the presence of at least three mismatch regions. Experiments are in progress to identify the parts of P22 genome present in the hybrid phage.

Crosses, Genetic↗