The outstanding medical student in emergency medicine.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
S Mahadevan
Publications and source records attributed to S Mahadevan.
Evaluation of PCR using TRC(4) and IS6110 primers in detection of tuberculous meningitis.
We have evaluated a new set of primers (TRC(4)) in comparison with the IS6110 primers commonly used in PCR to detect tuberculous meningitis among children. The levels of concordance between the results of IS6110 PCR and TRC(4) PCR with cerebrospinal fluid specimens from patients with clinically confirmed tuberculous meningitis were 80 and 86%, respectively. Results with the two primer sets were concordant for 55 positive and 22 negative specimens (n = 98). We conclude that the sensitivity of PCR can be increased by using both IS6110 and TRC(4) primers.
Cerebrospinal Fluid↗
Mechanism of catabolite repression in the bgl operon of Escherichia coli: involvement of the anti-terminator BglG, CRP-cAMP and EIIAGlc in mediating glucose effect downstream of transcription initiation.
BACKGROUND: Expression of the bgl operon of Escherichia coli, involved in the regulated uptake and utilization of aromatic beta-glucosides, is extremely sensitive to the presence of glucose in the growth medium. We have analysed the mechanism by which glucose exerts its inhibitory effect on bgl expression. RESULTS: Our studies show that initiation of transcription from the bgl promoter is only marginally sensitive to glucose. Instead, glucose exerts a more significant inhibition on the elongation of transcription beyond the rho-independent terminator present within the leader sequence. Transcriptional analyses using plasmids that carry mutations in bglG or within the terminator, suggest that the target for glucose-mediated repression is the anti-terminator protein, BglG. Introduction of multiple copies of bglG or the presence of mutations that inhibit its phosphorylation by Enzyme IIBgl (BglF), result in loss of glucose repression. Studies using crp, cya and crr strains show that both CRP-cAMP and the Enzyme IIAGlc (EIIAGlc) are involved in the regulation. Although transcription initiation is normal in a crp, cya double mutant, no detectable transcription is seen downstream of the terminator, which is restored by a mutation within the terminator. Transcription past the terminator is also partly restored by the addition of exogenous cAMP to glucose-grown cultures of a crp+ strain. Glucose repression is lost in the crr mutant strain. CONCLUSIONS: The results summarized above indicate that glucose repression in the bgl operon is mediated at the level of transcription anti-termination, and glucose affects the activity of BglG by altering its phosphorylation by BglF. The CRP-cAMP complex is also involved in this regulation. The results using the crr mutant suggest a negative role for EIIAGlc in the catabolite repression of the bgl genes.
Bacterial Proteins↗
Burch colposuspension: a 10 to 12 years follow up.
Burch colposuspension is considered to be the gold standard for the surgical treatment of genuine stress incontinence in women. Short-term cure rates are as high as 90%. (Jarvis, 1994). The long-term (10 or more years) cure rate of 62% in this study confirms the time dependent decline in efficacy.
Journal Article↗
Analysis of the beta-glucoside utilization (bgl) genes of Shigella sonnei: evolutionary implications for their maintenance in a cryptic state.
The pattern of expression of the genes involved in the utilization of aryl beta-glucosides such as arbutin and salicin is different in the genus Shigella compared to Escherichia coli. The results presented here indicate that the homologue of the cryptic bgl operon of E. coli is conserved in Shigella sonnei and is the primary system involved in beta-glucoside utilization in the organism. The organization of the bgl genes in S. sonnei is similar to that of E. coli; however there are three major differences in terms of their pattern of expression. (i) The bglB gene, encoding phospho-beta-glucosidase B, is insertionally inactivated in S. sonnei. As a result, mutational activation of the silent bgl promoter confers an Arbutin-positive (Arb(+)) phenotype to the cells in a single step; however, acquiring a Salicin-positive (Sal(+)) phenotype requires the reversion or suppression of the bglB mutation in addition. (ii) Unlike in E. coli, a majority of the activating mutations (conferring the Arb(+) phenotype) map within the unlinked hns locus, whereas activation of the E. coli bgl operon under the same conditions is predominantly due to insertions within the bglR locus. (iii) Although the bgl promoter is silent in the wild-type strain of S. sonnei (as in the case of E. coli), transcriptional and functional analyses indicated a higher basal level of transcription of the downstream genes. This was correlated with a 1 bp deletion within the putative Rho-independent terminator present in the leader sequence preceding the homologue of the bglG gene. The possible evolutionary implications of these differences for the maintenance of the genes in the cryptic state are discussed.
Arbutin↗
Scorpion sting.
Explore the source record for details and available documents.
Adrenergic alpha-Antagonists↗
Compliance with hormone replacement therapy after prophylactic oophorectomy.
Explore the source record for details and available documents.
Journal Article↗
Detection of antipneumolysin in invasive childhood pneumococcal infections.
Antibody levels against pneumolysin, a virulence factor in pneumococcal infections were evaluated by a neutralization test, using crude pneumolysin. A study population of 28 hospitalised children with culture proven pneumococcal meningitis and pneumonia were tested for detection of antipneumolysin antibodies in their serum. Results were compared with age and sex matched controls who were admitted with infections other than pneumococcal. Geometric mean titer (GMT) of antipneumolysin in serum of patients with pneumococcal infections showed a significant difference when compared with controls, GMT of 196.1 and 185.2 were noted in patients with meningitis and pneumonia respectively, in contrast to a titer of 40.32 among controls. A difference of more than 4-fold antibody titers between patients and controls was considered significant. Detection of antipneumolysin in serum can therefore be considered as a useful laboratory investigation in diagnosing invasive pneumococcal infections.
Antibodies, Bacterial↗
Plasmid-mediated suppression of the mutational activation of the bgl operon in Shigella sonnei.
SSOR, a clinical isolate of Shigella sonnei which exhibits a Salicin-negative phenotype, is unable to mutate to give rise to Sal+ derivatives although a homolog of the Escherichia coli bgl operon is retained by the strain. This was correlated to the presence of an endogenous plasmid in the strain. A plasmid-cured derivative, AK711, could give rise to Sal+ mutants in two steps. Introduction of the plasmid DNA, extracted from SSOR, into various strains of E. coli and S. sonnei, resulted in ampicillin resistant transformants. Interestingly, the presence of the plasmid suppressed the mutational activation of the bgl operon in the transformants. This was further substantiated by the observation that, transformants that have lost the plasmid regained the ability for mutational activation of the bgl operon. Preliminary characterisation of the plasmid indicated a size of 3.8 kb with an origin of replication resembling that of ColE1 replicons and the bla gene homolog of Tn3. Observations of the mutation frequency at the srl and lac loci in the presence of the plasmid indicate that there is a reduction in the mutation frequency, suggesting an antimutator activity associated with the plasmid.
Escherichia coli↗
Mg2+ mediated sequence-specific binding of transcriptional activator protein C of bacteriophage Mu to DNA.
The contributions from the secondary structure of the transcriptional activator protein C of bacteriophage Mu to its specific DNA binding and the influence of various factors, viz., electrolytes, and minor groove and major groove binders on this protein-DNA interaction have been addressed. Circular dichroism (CD) spectral results suggest that, in the absence of Mg2+, C protein exhibits a beta-pleated sheetlike structure and Mg2+ changes the conformation to a more alpha-helical structure which could provide specific geometrical constraints complementary to those of DNA-helix. Thus, Mg2+ acts as a cofactor for the binding of the C protein to its specific site in DNA by inducing conformational changes in the protein. Competitive binding studies with minor and major groove binding drugs, viz., distamycin A and methyl green, respectively, and the DMS footprinting data indicate that the C protein recognizes the major groove of DNA during complex formation. Further, upon major groove binding, C protein brings about changes in DNA conformation; such conformational changes could have implications in the transcription process.
Amino Acid Sequence↗
Interrater reliability of cervical spine injury criteria in patients with blunt trauma.
STUDY OBJECTIVE: To determine the interrater reliability of previously defined risk criteria for cervical spine injury. METHODS: Two emergency physicians independently evaluated patients with blunt trauma to determine whether they exhibited any of four risk criteria: (1) altered neurologic function; (2) evidence of intoxication; (3) spinous process or posterior midline cervical tenderness; or (4) distracting painful injury. Each criterion was explicitly described on study data forms. Physician concordance was measured, and the kappa statistic was calculated, for the combined risk criteria (based on the presence of any individual criterion), and for each individual criterion. RESULTS: There were 122 patients evaluated. Physicians agreed on overall classifications for 107 patients (87.7%; kappa, .73; confidence interval [CI], .61 to .86). Agreement for individual criteria were as follows: (1) altered neurologic function--102 patients (83.6%; kappa, .58; CI, .41 to .74); (2) intoxication--118 patients (96.7%; kappa, .86; CI, .72 to .99); (3) posterior midline tenderness--109 patients (89.3%; kappa, .77; CI .65 to .89); (4) distracting injury--112 patients (91.8%; kappa.77; CI, .64 to .91). CONCLUSION: The combined cervical spine injury criteria have substantial interrater reliability. Individual criteria are slightly less reliable.
Adolescent↗
An expert system for assigning patients into clinical trials based on Bayesian networks.
Assigning patients into clinical trials is a knowledge and data intensive task. Eligibility determination for entry into a clinical trial is based upon specific inclusion and exclusion criteria. This paper investigates the use of an excerpt system to assist the physician through this task. This expert system uses Bayesian networks, a probabilistic method that can take advantage of pre-existing statistical knowledge. The paper also describes the feasibility of such a system by presenting the implementation of three clinical protocols. The experimental results reveal that the approach is feasible. The system gives correct eligibility scores when all evidence is available but also predicts eligibility when there is missing evidence. The system directs the physician to the protocols the patient is most eligible for, according to the current evidence. The system has the ability of learning its prior and conditional probabilities (expert knowledge) from training examples.
Algorithms↗
Meningitis in home delivered neonates in Pondicherry, South India.
Explore the source record for details and available documents.
Home Childbirth↗
Cutaneous malignant melanoma--clinical epidemiology and survival.
Melanoma of the skin is rare in the Asian population. However, this malignancy results in a high mortality due to the inadequacies in the referral pattern and management. India is one of the low incidence regions of the world. Cancer registries in India report that the age specific incidence rates for cutaneous malignant melanoma (CMM) are less than 0.5 per 1,000,000. There are only few reports in the literature on CMM in the Asian population. The Regional Cancer Centre at Trivandrum registers about 6000 new cancer cases per year and CMM forms 0.5% of them. This paper presents the clinical epidemiology and survival of 79 cases of CMM registered in the hospital cancer registry during the period 1985-90. The peak age frequency was in the 7th decade. The male:female ratio was 1.6:1. All cases had undergone a surgical manipulation in a peripheral centre, before being referred to this centre. This has posed limitation in staging and in deciding the extends of surgical excision. The overall 5-year survival rate was 25.2% (95% confidence intervals, or, CI, 14%-38%). CMM in the low incidence regions may have a different aetiology and needs to be addressed in epidemiological studies.
Adult↗
Characterisation of 3' end formation of the yeast HIS3 mRNA.
The nucleotide (nt) sequence of the 3' end of the yeast HIS3 mRNA was determined by PCR amplification of the 3' end. Analysis of 28 individual clones revealed that at least 13 distinct polyadenylation sites are present. The sites of polyadenylation are extremely heterogeneous and do not show any obvious similarity other than that they occur after pyrimidine residues in most cases. Most mutants carrying internal deletions of the 3' untranslated region (3' UTR) did not abolish 3' end formation and showed polyadenylation at normal sites. Deletion of a 90-nt region that contains an A+T-rich sequence close to the 3' end of the HIS3 coding sequence and a subset of processing sites resulted in a drastic reduction in the levels of full-length HIS3 mRNA and concomitant transcription past the normal HIS3 3' end. The 90-nt region appears to be sufficient to direct the formation of at least a subset of the HIS3 3' ends since mutants that carry deletions of flanking regions of this sequence show detectable levels of HIS3 mRNA. Spacing between the upstream A-T sequence and the site of processing is variable. In the light of the extreme heterogeneity of the sites, a possible mechanism for 3' processing is discussed.
Base Sequence↗
Characterization of the negative elements involved in silencing the bgl operon of Escherichia coli: possible roles for DNA gyrase, H-NS, and CRP-cAMP in regulation.
The bgl operon of Escherichia coli is rendered cryptic and uninducible in wild-type cells by the presence of DNA structural elements that negatively regulate transcription. We have carried out a detailed analysis of the sequences implicated in negative regulation. Fine-structure deletion analysis of the upstream sequences showed the presence of at least two elements involved in silencing the promoter. Chemical probing of genomic DNA in vivo showed that a region of dyad symmetry, present upstream of the promoter, is hypersensitive to KMnO4. The hypersensitive region detected corresponds to the potential cruciform structure implicated earlier in negative regulation. Enhancement of transcription from the wild-type promoter, observed in the presence of the gyrase inhibitor novobiocin, was absent in a mutant that carried point mutations in the inverted repeat. This observation suggests that the activation seen in a gyrase mutant is mediated by destabilization of the cruciform because of reduced supercoiling. Deletion of sequences downstream of the potential cruciform also resulted in an increase in transcription, indicating the presence of a second regulatory element. Measurement of transcription from the bgl promoter carrying the deletion, in a strain that has a mutation in the hns gene, indicated that this region is likely to be involved in binding to H-NS or a protein regulated by H-NS, which acts as a non-specific repressor. We also provide evidence which suggests that transcriptional activation by mutations at the cAMP receptor protein (CRP)-binding site is mediated partly by antagonization of the negative effect of H-NS by CRP-cAMP as a result of its increased affinity for the mutant site.
Bacterial Outer Membrane Proteins↗
Abundance, parity, and Japanese encephalitis virus infection of mosquitoes (Diptera:Culicidae) in Sepang District, Malaysia.
A 2-yr study of Japanese encephalitis (JE) virus in Sepang District, Selangor, Malaysia, was carried out to identify the mosquito vectors and to determine their seasonal abundance, parity, and infection rates. In total, 81,889 mosquitoes belonging to 9 genera and > 50 species were identified from CDC trap collections augmented with dry ice during 1992 and 1993. Culex tritaeniorhynchus Giles and Culex gelidus Giles were the most abundant species, and both increased in numbers with increases in rainfall. Overall, 45 JE virus isolations were made from 7 species-Cx. tritaeniorhynchus (24), Cx. gelidus (12), Culex fuscocephala Theobald (2), Aedes butleri Theobald (4), Culex quinquefasciatus Say (1), Aedes lineatopennis Ludlow (1), and Aedes (Cancraedes) sp. (1). Based on elevated abundance and JE infection rates, Cx. tritaeniorhynchus appears to be the most important vector of JE virus in Sepang.
Aedes↗