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A Kalia

Publications and source records attributed to A Kalia.

At least 19 recordsLinked to original sources
PubMed2001

Recombination within natural populations of pathogenic bacteria: short-term empirical estimates and long-term phylogenetic consequences.

The identification of clones within bacterial populations is often taken as evidence for a low rate of recombination, but the validity of this inference is rarely examined. We have used statistical tests of congruence between gene trees to examine the extent and significance of recombination in six bacterial pathogens. For Neisseria meningitidis, Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus, the congruence between the maximum likelihood trees reconstructed using seven house-keeping genes was in most cases no better than that between each tree and trees of random topology. The lack of congruence between gene trees in these four species, which include both naturally transformable and nontransformable species, is in three cases supported by high ratios of recombination to point mutation during clonal diversification (estimates of this parameter were not possible for Strep. pyogenes). In contrast, gene trees constructed for Hemophilus influenzae and pathogenic isolates of Escherichia coli showed a higher degree of congruence, suggesting lower rates of recombination. The impact of recombination therefore varies between bacterial species but in many species is sufficient to obliterate the phylogenetic signal in gene trees.

Alleles↗
PubMed2001

A baseline study of pediatric dialysis in Texas.

This study provides a cross-sectional view of the management of 94 Texas children with end-stage renal disease in 1996 and serves as a point of comparison for future changes in management practice. Data collected in 6 pediatric and 18 adult dialysis facilities in Texas revealed that a greater proportion of younger pediatric patients received peritoneal dialysis (PD). Patients on PD had a significantly lower serum albumin level than those on hemodialysis (HD). HD and PD patients were 2.3 and 1.7 standard deviation scores (SDS) below the average height of the age- and gender-matched populations, respectively. There was no significant difference in hematocrit, use of growth hormone, parathyroid hormone level, weight SDS, or bone age by treatment modality. However, patients dialyzed in pediatric facilities were more likely to receive growth hormone and to be regularly evaluated for Tanner stage and bone age than those in adult facilities. Measurement of creatinine clearance as a measure of adequacy of PD in young children was not a common practice. Instead pediatric nephrologists tended to rely more on anthropometric measurements, developmental maturation, and serum albumin to assess adequacy. Opportunities remain to maximize the growth potential and to develop standards for the adequacy of dialysis in the younger patient.

Adolescent↗
PubMed2001

Comparison of the effects of ketoprofen on platelet function in the presence and absence of aspirin.

PURPOSE: Although aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) exert inhibitory effects on platelets in vitro and in vivo, there are insufficient data to substantiate the use of NSAIDs alone as antiplatelet drugs in patients already taking aspirin. We therefore sought to determine whether aspirin, added to NSAID therapy, further suppresses platelet function. SUBJECTS AND METHODS: We enrolled 25 healthy adult volunteers who were administered ketoprofen (extended-release capsules, 200 mg daily) for 1 week, followed by ketoprofen (200 mg daily) and aspirin (325 mg daily) or ketoprofen (200 mg daily) alone during the second week. Platelet aggregation, stimulated by epinephrine and arachidonic acid, and cyclooxygenase activity, measured by thromboxane B(2), were measured at baseline, on day 8, and on day 15. RESULTS: On day 8, all subjects demonstrated abnormal platelet aggregation (>50% inhibition), which persisted at day 15 in both the aspirin and no aspirin groups. One week of ketoprofen treatment reduced thromboxane B(2) levels by 84% in the aspirin group and by 85% in the no aspirin group (P = 0.8), without any further inhibition measured on day 15. CONCLUSION: Extended-release ketoprofen significantly inhibited platelet aggregation and thromboxane B(2) production in healthy volunteers. Addition of aspirin had no additional effect. Trials are warranted to determine whether these in vitro effects result in clinical antiplatelet activity in patients who require chronic treatment with NSAIDs, thereby avoiding the toxicity of NSAID/aspirin combination therapy.

Adult↗
PubMed2001

Multilocus sequence typing of Streptococcus pyogenes and the relationships between emm type and clone.

Multilocus sequence typing (MLST) is a tool that can be used to study the molecular epidemiology and population genetic structure of microorganisms. A MLST scheme was developed for Streptococcus pyogenes and the nucleotide sequences of internal fragments of seven selected housekeeping loci were obtained for 212 isolates. A total of 100 unique combinations of housekeeping alleles (allelic profiles) were identified. The MLST scheme was highly concordant with several other typing methods. The emm type, corresponding to a locus that is subject to host immune selection, was determined for each isolate; of the >150 distinct emm types identified to date, 78 are represented in this report. For a given emm type, the majority of isolates shared five or more of the seven housekeeping alleles. Stable associations between emm type and MLST were documented by comparing isolates obtained decades apart and/or from different continents. For the 33 emm types for which more than one isolate was examined, only five emm types were present on widely divergent backgrounds, differing at four or more of the housekeeping loci. The findings indicate that the majority of emm types examined define clones or clonal complexes. In addition, an MLST database is made accessible to investigators who seek to characterize other isolates of this species via the internet (http://www.mlst.net).

Alleles↗
PubMed2001

Directional gene movement from human-pathogenic to commensal-like streptococci.

Group A streptococci (GAS) are highly pathogenic for humans, and their closest genetic relatives, group C and G streptococci (GCS and GGS, respectively), are generally regarded as commensals, although they can be found in association with human disease. As part of an effort to better understand the evolution of virulence, the phylogenetic relationships between GAS, GCS, and GGS were examined. The nucleotide sequence was determined for an internal portion of seven housekeeping (neutral) loci among >200 isolates of GAS and 34 isolates of GCS or GGS obtained from human subjects. Genotypic analysis failed to show support for the separation of GCS and GGS into two distinct populations. Unlike GAS, there was poor concordance between emm type and genetic relatedness among GCS and GGS. All housekeeping genes within GAS displayed relatively low levels of sequence diversity. In contrast, individual GCS and GGS strains had mosaic genomes, containing alleles at some loci that were similar or identical to GAS alleles, whereas the alleles at other loci were about 10 to 30% diverged. The data provide evidence for a history of recent interspecies transfer of neutral genes that exhibits a strong net directionality from GAS donors to GCS and GGS recipients. A model for the evolution of GAS and of GCS and GGS is described.

Base Sequence↗
PubMed2000

Role of transplant induction therapy on recurrence rate of focal segmental glomerulosclerosis.

Individuals with focal segmental glomerulosclerosis (FSGS) are at risk for recurrence of disease following renal transplantation. The rate of recurrence has been estimated to range from 20% to 30%. The factors associated with an increased probability of recurrence are not known, although the rapidity of progression of disease, age at onset, and the presence of diffuse mesangial proliferation in the native kidney have all been implicated. We analyzed the data from 35 patients with FSGS who received 37 renal transplants at this institution between October 1968 and December 1997. Recurrence was diagnosed by the development of nephrotic-range proteinuria and a transplant biopsy compatible with the diagnosis. Sixteen recurrences were noted, with an overall recurrence rate of 43%. The risk of recurrence was associated with the use of antilymphocytic serum (ALS) for initial induction therapy; being 11% in those who received no induction therapy versus 53% in those who received ALS. Furthermore, in the latter group, the rate of recurrence was 88% in those who received antithymocyte globulin (ATGAM) versus 40% in those who received Minnesota antilymphocytic globulin. Factors such as race, sex, age at time of diagnosis, rapidity of progression to end-stage renal disease (ESRD), response to alkylating agents and/or cyclosporin therapy prior to ESRD, age at time of transplant, donor source, and triple or double immunosuppressive therapy did not appear to have an effect on the rate of recurrence. We conclude that induction therapy with ALS at time of transplantation increases the risk of recurrence of FSGS following renal transplantation.

Adolescent↗
PubMed1999

A method for extraction of high-quality and high-quantity genomic DNA generally applicable to pathogenic bacteria.

In this study, we report a modified procedure for extraction of high-quality genomic DNA that is rapid, simple, biologically nonhazardous, and generally applicable to pathogenic bacteria. Bacterial cells were pretreated with 70% ethanol prior to enzymatic digestion with lysozyme. Exposure of bacterial cells to 70% ethanol sterilized the cultures, making the process biologically safe and increased the susceptibility of the cells to lysozyme-induced lysis. Consistently high yields of genomic DNA (mean average yield, 0.5-2.5 mg/ml) were obtained from 465 isolates representing over 30 clinically important bacterial species. Genomic DNA obtained was determined to be suitable for further analysis, including bacterial fingerprinting techniques like restriction endonuclease analysis, Southern hybridization, and repetitive PCR. Availability of a generally applicable procedure for extraction of high-quality and high-quantity genomic DNA would be immensely beneficial for laboratories engaged in molecular surveillance of nosocomial and community-based outbreaks.

Bacteriolysis↗
PubMed1998

Study of Pseudomonas aeruginosa causing ventilator associated pneumonia.

Ps. aeruginosa is a frequent and prominent cause of nosocomial pneumonia especially in persons on assisted ventilation in the intensive care units. In a year long surveillance of ventilator associated pneumonia (VAP) we isolated 42 strains from broncho alveolar lavage samples collected and processed from 102 patients. By pyocin typing 40 of the 42 strains could be typed into 39 types but this designation changed each time the test was repeated. SDS-PAGE analysis of the whole cell proteins grouped the 42 strains of Ps. aeruginosa into 20 groups. After ribotyping, using an 18 mer DIG labelled oligonucleotide to the conserved region of 16S rRNA gene, the strains were designated into 18 types. The major type contained 8 isolates, but there was no clustering of isolates, indicating that each infecting strain was acquired separately and not from a common source. It would, therefore, appear that cross infection with a single clone was not the predominant mode of Ps. aeruginosa infection causing VAP in our ICU.

Cross Infection↗
PubMed1997

Comparative evaluation of two indigenously developed tests for rapid detection of group-A streptococci directly from throat swabs.

The efficacy of two indigenously developed rapid tests, latex agglutination and antibody capture assay (a colour immunochromatographic assay) to detect group A Streptococcus pyogenes (GAS) was evaluated in comparison with the traditional culture method ('Gold Standard') in both asymptomatic children (1500) and symptomatic patients (233). Throat swabs were taken in duplicate and rapid tests performed on one swab and culture on the other. Both latex agglutination and antibody capture assays showed a sensitivity of 100 per cent and specificity of > 98 per cent as compared to culture and isolation in symptomatic patients. However, among asymptomatic carriers sensitivity of 100 per cent and 87.5 per cent and specificity > 95 per cent were observed for latex agglutination and antibody capture assays respectively. Latex agglutination showed no false negative results and sensitivity was not affected by low beta-haemolytic counts in asymptomatic children. The rapid tests described here will help in the detection and thereby the management of GAS infection.

Adolescent↗
PubMed1996

A preliminary study of fingerprinting of Pseudomonas aeruginosa by whole cell protein analysis by SDS-PAGE.

Forty two strains of Pseudomonas aeruginosa isolated from bronchoalveolar lavage fluid from intubated patients admitted to the Intensive care unit in AIIMS between December 1993 to June 1994 were included in the study. After obtaining typical biochemical profile, antimicrobial susceptibility was performed against ceftazidime, amikacin, gentamicin, ampicillin, cefotaxime and ciprofloxacin. Pyocin typing of these 42 strains was performed by scrape and streak method using 22 indicator strains. Forty strains could be typed showing excellent discrimination but on repeated testing the group designation changed indicating that the system had low reproducibility. SDS-PAGE of whole cell protein profile indicated the presence of 45 protein bands of different molecular weights, individual isolates had 37 to 42 protein band ranging in molecular weight from 340 kDa to 14.3 kDa. On the basis of Dice index of similarity the strains could be grouped into 20 types. Since all strains could be typed, the system has adequate typability. Similar results were obtained on repeated testing indicating good reproducibility.

Bacterial Proteins↗
PubMed1995

Increased glomerular and urinary malondialdehyde in puromycin aminonucleoside-induced proteinuria in rats.

Puromycin aminonucleoside (PAN)-induced proteinuria in rats may be mediated by reactive oxygen metabolites (ROM), which are injurious to several cell components including membrane lipids. Increased malondialdehyde (MDA) production is indicative of lipid peroxidation. We examined if MDA content of glomeruli and its urinary excretion were increased in rats administered PAN. Of three groups of 8 Sprague-Dawley rats each, group 1 served a control, group 2 animals received a single intravenous injection of PAN (5 mg/100 g body weight) and group 3 animals PAN with intraperitoneal injections of dimethylthiourea (DMTU), a free radical scavenger of oxidants such as hydroxyl radicals, for 4 days. The rats were sacrificed on day 8 after PAN injection. Increasing proteinuria, starting on day 4, developed in animals in group 2 but not in the others. The glomerular MDA (nmol/mg protein) in group 2 animals was 2.93 +/- 1.91, significantly higher than 0.87 +/- 0.63 and 1.26 +/- 0.76 in groups 1 and 3, respectively. Urinary levels of MDA markedly increased in group 2 rats on day 3 and remained high thereafter, but no such increase occurred in the control animals and those administered PAN with DMTU; the latter was thus protective against PAN toxicity. Our observations support the view that ROM are involved in PAN-induced glomerular injury and that increased urinary MDA excretion can be a marker of ROM-mediated lipid peroxidation.

Animals↗
PubMed1994

Prompt remission of post-renal transplant nephrotic syndrome with high-dose cyclosporine.

A 2.8-year-old girl with focal segmental glomerulosclerosis had recurrence of nephrotic syndrome within 3 days of renal transplantation and the serum creatinine increased. Renal biopsy showed cellular rejection and also complete effacement of the epithelial cell foot processes. The rejection responded to methylprednisolone therapy but massive proteinuria persisted. An increase in the dose of cyclosporine A to 14 mg/kg per day was followed by immediate remission of the proteinuria. One month later, a second renal biopsy showed only focal fusion of foot processes. She remains free of proteinuria 2 years later. We propose that the higher dose of cyclosporine caused remission of the nephrotic syndrome.

Biopsy↗
PubMed1991

Renal transplantation in children: experience of 23 years at the children's renal center of the University of Texas Medical Branch at Galveston.

This report describes a 23-year experience with renal transplantation in infants, children, and adolescents at the Children's Renal Center of the Division of Pediatric Nephrology at The University of Texas Medical Branch at Galveston. One hundred ninety-four transplants have been performed in 162 persons. Patient and graft survival is illustrated and is similar to that from other US centers. The data suggest an enhanced graft survival in transplants from living, related donors and from cadaveric donors after introduction of cyclosporine A as the primary immunosuppressive agent. The data for infants and small children are similar to that reported for adolescents and adults. Thus, all infants, children, and adolescents with chronic renal failure are potential candidates for renal transplantation. The timing of the transplant appears more critical than in the adult due to the need to consider growth and developmental milestones as well as the level of renal function. It is recommended that the counsel of a pediatric nephrologist be sought early in the course of any renal disease where progression to end-stage renal disease is probable.

Adolescent↗
PubMed1989

Effects of some divalent metal ions on the aging phenomenon of hematoporphyrin and photofrin II.

Dilute aqueous solutions of hematoporphyrin (Hp) and its derivative (Hpd or PF II) have been found to undergo a transformation (aging) on keeping at room temperature leading to (i) shift of the Soret band from 395 nm to 405 nm, (ii) disappearance of visible bands I (610 nm) and IV (503 nm) and (iii) shift of the first emission band from 615 nm to 580 nm. The transformation was concentration dependent. The effects of concentration and temperature on the absorption spectra were much more pronounced in Hp than in Photofrin II (PF II). Variation of pH resulted in changes in the relative intensities of the absorption bands, possibly due to formation of different ionic species at different pH. The rate of transformation was accelerated in the presence of Zn ions (0.01 microM) and considerably increased at higher (50 microM) concentration. The effect of Cu ions was different from the effect of aging. It formed the metal-chelate even when present in very small amounts. The results (absorption and fluorescence analysis) suggest that in dilute solutions (conc. less than or equal to 2 microM) of Hp and PF II, Zn ions present in glass and water as impurity, deform the porphyrin nucleus leading to changes in the conjugated ring symmetry and hence changes in the absorption and fluorescence spectra, while in higher concentrations (greater than 2 microM) it forms the metal chelate as evidenced by their absorption and fluorescence spectra.

Chemical Phenomena↗