Biomedical subjects

A Varma

Publications and source records attributed to A Varma.

At least 37 records · Page 2Linked to original sources

PubMed1999

Piriformospora indica: a new biological hardening tool for micropropagated plants.

Piriformospora indica is a novel plant growth promoting root endophyte. Regenerated plantlets of tobacco subjected to two different biological hardening techniques showed 88-94% survival when inoculated with P. indica as compared to 62% survival of uninoculated controls under similar conditions. The tendency of the plantlet to overcome the stress in terms of revival capacity was maximal in the case of P. indica as compared to the control. The fungus has the potential to render protection to the micropropagated plantlets and help them escape the 'transient transplant shock'.

Fungi↗

PubMed1999

Characterization of the glyceraldehyde-3-phosphate dehydrogenase gene [correction of glyceraldehyde-3-phosphate gene] and the use of its promoter for heterologous expression in Cryptococcus neoformans, a human pathogen.

The GPD gene encoding glyceraldehyde-3-phosphate dehydrogenase was isolated from Cryptococcus neoformans, a heterobasidiomycetous yeast that is pathogenic to humans. The gene contains 11 introns, differing from the conserved intron positions found in the GPD genes of Basidiomycetes. The predicted amino-acid sequence of this gene is extremely similar to that reported from GPD proteins of other basidiomycetes. The promoter region of the C. neoformans GPD gene was similar to those of other basidiomycetes. Plasmid constructs containing up to 1600 base pairs upstream of the native GPD open reading frame were used to express either the native URA5 gene in a ura5 mutant or the heterologous hphI gene (a bacterial gene that confers resistance to the aminoglycoside hygromycin) in a wild-type strain of C. neoformans. Transformation frequencies resulting from the plasmid-borne Gpdp::URA5 gene were at levels similar to those of the native URA5, which suggested that all the sequences necessary for proper expression were present. Transformation frequencies using the Gpdp::hphI gene constructs were poor. However, addition of DNA sequences flanking the 3'-end of an native C. neoformans gene significantly improved the transformation frequencies resulting from the expression of the heterologous hphI gene.

Amino Acid Sequence↗

PubMed1999

The yeast Cryptococcus neoformans uses 'mammalian' enhancer sites in the regulation of the virulence gene, CNLAC1.

Transcriptional regulation in mammalian and plant cells is distinguished from fungi by the presence of blocks of multiple interacting DNA binding sites distributed over a relatively large upstream region of genes and the ability to use glutamine-rich enhancers such as Sp1. We offer evidence that the haploid yeast Cryptococcus neoformans contains a virulence gene, CNLAC1, having regulatory properties more similar to mammalian systems than to that of yeast. We used a novel promoter plasmid, pVEW, and electromobility shift assay techniques adapted for the fungus for the first systematic structural and functional study of a 5'-enhancer region of a basidiomycete fungus using the upstream region of CNLAC1. Two groups of interactive enhancer regions, located over a range of 1.5kb from the mRNA start site are involved in CNLAC1 regulation (region 2: -1721 to -1615 and region 7) in addition to a TATA promoter at position -539. Region 2 contains a consensus Sp1 site and region 7 contains a consensus E2F site, each of which shows significant binding to nuclear proteins under derepressed conditions; cooperative binding was also suggested between DNA-binding protein of these sites and those binding nearby CCAAT sequences in each region. Two regions of repression were also evident under derepressed conditions (region 5: -1351 to -1207 and region 8: -991 to -971). Identification of functional Sp1 binding sites and the presence of multiple interactive enhancer sites over a fairly large upstream range suggests that cryptococcal transcriptional regulation contains features often associated with higher eukaryotic regulation. C. neoformans thus may provide a unique system for the study of certain aspects of higher eukaryotic transcription, using yeast genetic approaches. In addition, properties of basidiomycete yeast such as Cryptococcus exemplified in the present study suggest an evolutionary progression in gene regulation within fungi toward properties exhibited in the kingdoms Animalia and Plantae.

Animals↗

PubMed1999

Do routinely measured delivery variables predict anal sphincter outcome?

PURPOSE: Trauma to the anal sphincter is a recognized complication of primiparous childbirth. This damage may be compounded during subsequent deliveries leading to symptoms. Earlier work is inconclusive as to which delivery variables are associated with such damage and may prove useful in predicting its occurrence, thereby allowing the potential for intervention in these later deliveries to protect the traumatized anal sphincter. The purpose of the present study was to determine whether routinely recorded obstetric variables can be correlated to anal sphincter damage in a consecutive series of females. METHODS: A prospective study was undertaken in a single maternity unit. Patients delivering were assessed before discharge using a symptom questionnaire and endoanal ultrasound. Delivery data were collected prospectively and analyzed statistically to see if a significant difference existed in the presence of an anal sphincter defect. RESULTS: A total of 159 patients were assessed. Endosonography revealed sphincter injuries in 8.7 percent of the normal vaginal delivery group and 83 percent of the forceps delivery group. No correlation was found between head circumference, baby weight, maternal body mass index, epidurals, episiotomy, length of each stage of labor, and duration of active pushing. Forceps delivery was the only factor to be significantly associated with sphincter trauma. CONCLUSION: Besides forceps delivery, commonly measured delivery variables are not useful predictors of anal sphincter trauma. Normal vaginal deliveries do not warrant routine postnatal anorectal assessment, but this should be routine for all instrument deliveries.

Adult↗

PubMed1999

Obstetric anal sphincter injury: prospective evaluation of incidence.

PURPOSE: An obstetrically damaged anal sphincter is the principal cause of the development of fecal incontinence in otherwise healthy females. Reports suggest that such damage complicates as many as 35 percent of primiparous vaginal deliveries, with 13 percent of first-time mothers becoming symptomatic. In maternity units delivering 3,000 patients annually, it would follow that 390 symptomatic patients would develop new symptoms each year. This incidence of dysfunction does not reflect current clinical practice. We have investigated this discrepancy to establish the actual incidence of anal sphincter trauma associated with childbirth. METHODS: During a six-week period, 159 females (105 primiparous and 54 para-I) were prospectively assessed postnatally using a standardized symptom questionnaire, endoanal ultrasound, and anal manometry. This group constituted 84 percent of all eligible deliveries occurring in the unit during the study period. RESULTS: One patient developed fecal urgency after this delivery; there were no reports of fecal incontinence. Anal sphincter injuries were identified ultrasonically in 6.8 percent of primiparous patients, 12.2 percent of para-I patients having vaginal deliveries, and 83 percent of patients having forceps deliveries overall. Manometric data provided confirmatory evidence, with significantly reduced maximum squeeze pressures in patients with a disrupted anal sphincter (P<0.0005). CONCLUSIONS: A symptom questionnaire is inadequate to identify anal sphincter injuries. The incidence of sphincter injury in relation to vaginal delivery has been overestimated in previous published work. This study demonstrates that the true incidence is 8.7 percent overall and that symptoms of sphincter dysfunction are uncommon this is in keeping with current clinical practice.

Adolescent↗

PubMed1999

Piriformospora indica, a cultivable plant-growth-promoting root endophyte

Piriformospora indica (Hymenomycetes, Basidiomycota) is a newly described cultivable endophyte that colonizes roots. Inoculation with the fungus and application of fungal culture filtrate promotes plant growth and biomass production. Due to its ease of culture, this fungus provides a model organism for the study of beneficial plant-microbe interactions and a new tool for improving plant production systems.

Journal Article↗

PubMed1999

Isolation of Desulfovibrio intestinalis sp. nov. from the hindgut' of the lower termite Mastotermes darwiniensis.

A Gram-negative, anaerobic sulfate-reducing bacterium was isolated from hindgut contents of the lower termite Mastotermes darwiniensis Froggatt (strain KMS2). Strain KMS2 is motile by a single polar flagellum. The isolate possesses desulfoviridin and catalase activity. The G+C content of its DNA is in the range of 54.5-55.5 mol% (strain KMS2). It respires hydrogen and different low molecular weight organic compounds in the presence of sulfate, thiosulfate, and sulfite, and also oxygen. The isolated strain ferments pyruvate. Fastest growth with a doubling time of 12.5 h was obtained at 37 degrees C and not at 28 degrees C, the temperature at which the termites were grown. The isolate showed a 16S rDNA sequence homology of 95.9% to Desulfovibrio desulfuricans ATCC 27774 and a DNA-DNA homology of 44.6% to D. desulfuricans Essex 6 (type strain). Based on its biochemical properties and 16S rDNA sequence, the isolate was assigned to a new species named Desulfovibrio intestinalis.

Animals↗

PubMed1998

Kaposi's sarcoma-associated herpesvirus (KSHV) chemokine vMIP-II and human SDF-1alpha inhibit signaling by KSHV G protein-coupled receptor.

Kaposi's sarcoma-associated herpesvirus (KSHV) encodes two proteins that are similar to human CC chemokines and a G protein-coupled receptor (KSHV-GPCR) that is constitutively active. KSHV-GPCR binds a number of human CXC and CC chemokines. We showed that interferon gamma-inducible protein-10 (IP-10), a human CXC chemokine, inhibits KSHV-GPCR signaling (Geras-Raaka et al., J. Exp. Med. 188, 405-408, 1998). Here we show that viral monocyte inflammatory protein-II (vMIP-II), one of the KSHV-encoded CC chemokines, and stromal cell-derived factor 1alpha (SDF-1alpha), a human CXC chemokine that blocks infection by human immunodeficiency virus-type 1, inhibit KSHV-GPCR signaling also. If KSHV-GPCR signaling is involved in viral pathogenesis, then these chemokines may affect the course of Kaposi's sarcoma and primary effusion lymphoma.

Chemokine CXCL12↗

PubMed1998

Chemokines activate Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor in mammalian cells in culture.

Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus 8, a virus that appears to be involved in the pathogenesis of Kaposi's sarcoma and primary effusion lymphomas, encodes a G protein-coupled receptor (KSHV-GPCR) that exhibits constitutive signaling. In this report, we show that two chemokines, interleukin 8 (IL-8) and growth-related protein-alpha, activate KSHV-GPCR over constitutive levels. Moreover, as with human receptors, the integrity of the ELR motif of these chemokines is required for activation of KSHV-GPCR. Other residues that are required for IL-8 binding to human chemokine receptors CXCR1 and CXCR2 are important for KSHV-GPCR activation also. Thus, it appears that the ELR binding site and other key domains of ELR chemokine activation have been preserved in the virus KSHV-GPCR. The results suggest that KSHV-GPCR originated from CXCR1 or CXCR2 and that activation of KSHV-GPCR by endogenous chemokines may affect the pathobiology of KSHV infection in humans.

3T3 Cells↗

PubMed1998

Complex behavior of self-propagating reaction waves in heterogeneous media.

Self-propagating high temperature reaction waves, leading to the synthesis of advanced materials, are investigated in a variety of heterogeneous reaction systems by using a digital high-speed microscopic video recording technique. It is shown that, although on the macroscopic length and time scales, the reaction appears to move in a steady mode, on the microscopic level it has a complex character that is related to the reaction mechanism.

Aluminum↗

PubMed1998

Human interferon-gamma-inducible protein 10 (IP-10) inhibits constitutive signaling of Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor.

A G protein-coupled receptor (GPCR) is encoded within the genome of Kaposi's sarcoma- associated herpesvirus (KSHV)/human herpesvirus 8, a virus that may be involved in the pathogenesis of Kaposi's sarcoma and primary effusion lymphomas. KSHV-GPCR exhibits constitutive signaling activity that causes oncogenic transformation. We report that human interferon (IFN)-gamma-inducible protein 10 (HuIP-10), a C-X-C chemokine, specifically inhibits signaling of KSHV-GPCR. In contrast, monokine induced by IFN-gamma (HuMig), which like HuIP-10 is an agonist of C-X-C chemokine receptor 3, does not inhibit KSHV-GPCR signaling. Moreover, HuIP-10, but not HuMig, inhibits KSHV-GPCR-induced proliferation of NIH 3T3 cells. These results show that HuIP-10 is an inverse agonist that converts KSHV-GPCR from an active to an inactive state. Thus, a human chemokine inhibits constitutive signaling and cellular proliferation that is mediated by a receptor encoded by a human disease-associated herpesvirus.

3T3 Cells↗

PubMed1998

Construction of stable episomes in Cryptococcus neoformans.

We report the generation of stable plasmids constructed by inserting specific DNA sequences into previously known unstable vectors. These sequences were obtained from a DNA library recovered from a previously reported stable minichromosome created by electroporative transformation in Cryptococcus neoformans (Varma and Kwon-Chung 1994). A 6-kb insert from this minichromosome significantly enhanced both the frequencies at which URA5 transformants were obtained as well as the stability of their uracil prototrophy on non-selective media. A 1.5-kb sequence of this insert contained telomeric sequence repeats which when introduced into plasmids resulted in significant increases in transformation frequency. A 1081-bp sequence (STAB), present in the remainder of the insert, had an ARS-like function enhancing the episomal maintenance of plasmids in the transformants regardless of the gene (ADE2/URA5) used as a selection marker.

Blotting, Southern↗

PubMed1998

The impact of ratee's disability on performance judgments and choice as partner: the role of disability-job fit stereotypes and interdependence of rewards.

An experiment assessed the impact of disability-job fit stereotypes and reward interdependence on personnel judgments about persons with disabilities. Students (N = 87) evaluated 3 confederates. The experiment varied disability of the target confederate (dyslexia vs. nondisabled), task, and dependence of rater rewards on partner performance. Two disability-task combinations represented stereotypical poor fit and good fit. Dependent variables were performance evaluations, performance expectations, and ranking of target as a partner. There was negative bias against the confederate with dyslexia in poor-fit conditions. In the interdependent reward condition, there was a negative main effect for disability, regardless of fit. No effects for disability were found on performance ratings or expectations. Results indicate the need to consider disability-job fit stereotypes and consequences to raters when assessing the impact of disability on personnel judgments.

Adult↗

PubMed1998

Histopathological changes following the use of biological and synthetic glue for dural grafts: an experimental study.

Dural defects and CSF leaks are common neurosurgical problems and the search for a suitable sealant continues. The effects of such sealants on meninges and brain have not been previously studied. To study the effect of two commonly used sealants, burrholes were made in 20 rats, with the creation of dural tears which were covered with human cadaveric dura smeared with synthetic (cyanoacrylate) glue and gelatine (GRG) glue. Plain dura, placed in one of the burrholes served as a control. An intense inflammatory reaction was observed with both glues, which was found to persist till the eleventh week.

Adult↗

PubMed1997

Human herpesvirus KSHV encodes a constitutively active G-protein-coupled receptor linked to cell proliferation.

Kaposi's sarcoma-associated herpesvirus (KSHV, also known as human herpesvirus 8, or HHV 8) is a virus that is consistently present in Kaposi's sarcoma and in primary-effusion (body-cavity-based) lymphomas, malignancies that occur frequently, but not exclusively, in AIDS patients. KSHV is a gamma herpesvirus with homology to herpesvirus Saimiri and Epstein-Barr virus, both of which can transform lymphocytes. Cloning of a KSHV genome fragment revealed the presence of an open reading frame encoding a putative G-protein-coupled receptor that is homologous to a G-protein-coupled receptor encoded by herpesvirus Saimiri and to human interleukin-8 receptors. Here we show that the KSHV G-protein-coupled receptor is a bona fide signalling receptor which has constitutive (agonist-independent) activity in the phosphoinositide-inositoltrisphosphate-protein kinase C pathway. Furthermore, the KSHV G-protein-coupled receptor stimulates cellular proliferation, making it a candidate viral oncogene.

Animals↗

PubMed1997

Immunoassays to study prevalence of antibody against GB virus C in blood donors.

Immunoassays were developed to determine the seroprevalence of antibody against human GB virus C (GBV-C). The antigenic target in each assay was a 44.6-kDa glycosylated protein representing the first 315 amino acids encoded by the GBV-C E2 gene. Sera or plasma were assayed for E2 antibody using an anti-human EIA format in which antigen-coated polystyrene beads were reacted with sample, and bound antibody was detected by addition of enzyme labelled goat anti-human IgG. The presence of anti-E2 antibody was confirmed using a sandwich EIA format in which samples were reacted with antigen coated polystyrene beads, followed by addition of solution phase biotinylated antigen. Detection of antibody captured biotinylated E2 was accomplished by addition of enzyme-conjugated anti-biotin antibody. Antibody against the E2 antigen was detected in 7.4 and 7.8% of 500 sera and 500 plasma, respectively, from US volunteers donating to a Wisconsin blood center, and in approximately 10.7% of hepatitis and retrovirus marker-negative volunteer blood donors from a Missouri blood center. The rate in 1018 sera from US commercial donors at multiple US blood centers was 36.7%. These results indicated a relatively high prevalence of GBV-C exposure in US volunteer donors, and particularly in commercial donors. The clinical implication of the high exposure rate is unclear. These immunoassays are being combined with nucleic acid detection to assess prevalence of GBV-C world wide and to determine if GBV-C plays a role as an etiologic agent.

Animals↗

PubMed1997

Pituitary abscess: a series of six cases.

Pituitary abscess is a rare condition occurring in various age groups. Only about a hundred cases have been reported in the literature. We describe six cases that constitute 0.6% of all the pituitary lesions operated at this centre in the last 10 years. All the patients presented with visual symptoms, though systemic features of infection were present in only two cases. The abscess was seen in association with adenoma in two cases and Rathke's cleft cyst in one. One patient developed an abscess following surgery for pituitary adenoma. The offending organisms was fungal in two cases, mycobacterium in one, bacterial in one and two cultures were sterile. Preoperative diagnosis is difficult and a high degree of suspicion in ring enhancing lesions of the sella is required.

Abscess↗

PubMed1997

Breast cancer risk and alcohol consumption: results from a large case-control study.

BACKGROUND: Alcohol use is associated with breast cancer in many epidemiological studies. Most, however, have measured risk from recent consumption patterns, and only a few include analyses for duration of drinking or age that a woman started to drink. The authors studied the effect of these variables, as well as of recent alcohol consumption patterns, on breast cancer risk. METHODS: Data from a large case-control study conducted in Long Island, New York from 1 January 1984 to 31 December 1986 were used. A total of 1214 women aged 20-79 years with incident breast cancer were interviewed. A control was selected for each case from driver's license files, and matched on age and county of residence. Alcohol consumption was measured as: ever versus never, grams of alcohol per day, age started drinking, and total years drinking. RESULTS: After adjustment for breast cancer risk factors, the odds ratio for ever versus never drinking was 1.40 (95% confidence interval [CI] 1.09-1.79); odds ratios for > 0-5 and > or = 5 grams of alcohol use per day, as compared to nondrinkers, were 1.29 (95% CI: 1.00-1.65) and 1.46 (95% CI: 1.13-1.89), respectively. Age when drinking began was not related to breast cancer risk, but the greater the total years of drinking, up to 40 years (odds ratio 1.48, 95% CI: 1.13-1.93), the greater the risk. However, when grams per day and duration of drinking were simultaneously included in the multivariate model, duration was not important as a risk factor. This suggests that intensity of drinking may be the important factor for breast cancer risk. After covariate adjustment, risk from alcohol intake did not differ between pre- and postmenopausal women.

Adult↗