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Biomedical subjects

M Rao

Publications and source records attributed to M Rao.

At least 145 records · Page 8Linked to original sources
PubMed1994

Chemical modification of xylanase from alkalothermophilic Bacillus species: evidence for essential carboxyl group.

The role of carboxyl group in the catalytic action of xylanase (M(r) 35,000) from an alkalothermophilic Bacillus sp. was delineated through kinetic and chemical modification studies using Woodward's Reagent K. The kinetics of inactivation indicated that one carboxyl residue was essential for the xylanase activity with a second order rate constant of 3300 M-1 min-1. The spectrophotometric analysis at 340 nm revealed that the inhibition was correlated with modification of 24 carboxyl residues. In the presence of protecting ligand, modification of one carboxyl group was prevented. The pH profile showed apparent pK values of 5.2 and 6.4 for the free enzyme and 4.9 and 6.9 for enzyme-substrate complex. The pH dependence of inactivation was consistent with the modification of carboxyl group. The kinetic analysis of the modified enzyme showed similar Km and lower kcat values than the native enzyme indicating that catalytic hydrolysis and not the substrate binding was affected by chemical modification. The chemical modification of xylanase from alkalothermophilic Bacillus revealed the presence of tryptophans in the active site (Deshpande, V, Hinge, J. and Rao, M. (1990) Biochim. Biophys. Acta 1041, 172-177). This finding and present studies demonstrated the experimental evidence for the participation of carboxyl as well as tryptophan groups as essential residues of xylanase from alkalothermophilic Bacillus sp.

Amino Acids↗
PubMed1994

The association of Chlamydia pneumoniae infection and reactive airway disease in children.

OBJECTIVE: To determine the possible association of Chlamydia pneumoniae infection and reactive airway disease in children. DESIGN: Prospective observational study. SETTING: Pediatric emergency department in Children's Medical Center of Brooklyn (NY), Kings County Hospital Center. PARTICIPANTS: One hundred eighteen children with acute episodes of wheezing and 41 age- and sex-matched healthy controls, aged 5 to 16 years. INTERVENTIONS: Children with cultures positive for C pneumoniae were treated with antibiotics. MEASUREMENTS/MAIN RESULTS: Cultures for C pneumoniae and serum samples for antibody testing were obtained from subjects and healthy controls. We isolated C pneumoniae from 13 (11%) children with wheezing and from two (4.9%) controls. Seven (58.3%) of 12 children with positive cultures had no detectable antibody to C pneumoniae and only three (25%) children had serologic evidence of acute infection. Six children had positive cultures on multiple occasions, ranging from 1 to 5 months. The children with wheezing were treated with erythromycin or clarithromycin, a new macrolide antibiotic approved for use in adults; all eventually had a negative culture. Nine (75%) of these children demonstrated clinical and laboratory improvement of the reactive airway disease after the eradication of chlamydial infection. CONCLUSIONS: Infection with C pneumoniae can trigger acute episodes of wheezing in children with asthma. Treatment of C pneumoniae infection may improve the course of reactive airway disease in these patients.

Adolescent↗
PubMed1994

Laminin receptor expression in rat intestine and liver during development and differentiation.

BACKGROUND/AIMS: Studies have identified a 67-kilodalton high-affinity laminin receptor (LR) whose expression has also been related to development, differentiation, and neoplastic transformation. The relationship of the 67-kilodalton LR to hepatic and enterocyte development and to enterocyte differentiation was investigated. METHODS: LR messenger RNA (mRNA) was identified using a complementary DNA isolated from a rat crypt cell library. LR and integrin (alpha 6, beta 1, and beta 4) expression by rat intestinal crypt cells was compared with that of the more differentiated villus cells using Northern blotting. Developmental differences in LR expression were studied in fetal and neonatal rats. The pattern of LR expression in fetal and adult rat intestines was examined further by in situ hybridization. RESULTS: LR mRNA levels were highest in fetal liver and intestine and adult rat crypt cells. LR mRNA levels were 9-10 times greater in crypt than in villus cells. Integrin subunit expression differed little between crypt and villus cells. Nascent transcription studies showed that the proportion of newly transcribed LR mRNA per total RNA synthesized was similar for crypt and villus cells, suggesting posttranscriptional control of LR mRNA levels in villus cells. CONCLUSIONS: Increased LR mRNA expression is a feature of the fetal intestine and of the undifferentiated, mitotically active crypt cells.

Aging↗
PubMed1994

Production and Purification of Extracellular D-Xylose Isomerase from an Alkaliphilic, Thermophilic Bacillus sp.

An alkaliphilic, thermophilic Bacillus sp. (NCIM 59) produced extracellular xylose isomerase at pH 10 and 50 degrees C by using xylose or wheat bran as the carbon source. The distribution of xylose isomerase as a function of growth in comparison with distributions of extra- and intracellular marker enzymes such as xylanase and beta-galactosidase revealed that xylose isomerase was truly secreted as an extracellular enzyme and was not released because of sporulation or lysis. The enzyme was purified to homogeneity by ammonium sulfate precipitation followed by gel filtration, preparative polyacrylamide gel electrophoresis, and ion-exchange chromatography. The molecular weight of xylose isomerase was estimated to be 160,000 by gel filtration and 50,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating the presence of three subunits. The enzyme is most active at pH 8.0 and with incubation at 85 degrees C for 20 min. Divalent metal ions Mg, Co, and Mn were required for maximum activity of the enzyme. The K(m) values for D-xylose and D-glucose at 80 degrees C and pH 7.5 were 6.66 and 142 mM, respectively, while K(cat) values were 2.3 x 10 s and 0.5 x 10 s, respectively.

Journal Article↗
PubMed1994

Demonstration of the cost-effectiveness of a nurse practitioner/physician team in long-term care facilities.

To an HMO with a Medicare risk contract, providing high-quality medical care to a nursing home resident may generate considerable costs. To address this issue, Fallon initially assigned each primary care physician to just one nursing home. The program was successful in that coverage of all Fallon patients admitted to nursing homes was assured. In a pilot project 5 years ago, a geriatric nurse practitioner (GNP) was hired to provide primary and episodic visits to nursing home residents in three area nursing homes. Research was conducted to determine the effectiveness of a GNP-MD team. Based on positive outcomes, additional GNPs were recruited. In the current follow-up study, a review of the 1992 fiscal and utilization data for nursing home patients revealed significantly lower rates of emergency room transfers, hospital lengths of stay and specialty visits for patients covered by GNP-MD teams, as compared to patients covered by physician only. Nursing home drug costs, skilled nursing days and primary care visits were higher for patients covered by the teams, but the differences were not statistically significant. Overall costs were 42% lower for the aggregate pool (skilled nursing plus intermediate care) and 26% lower for those with long-term stays.

Aged↗
PubMed1994

Waiting periods versus early innervation: the development of axonal connections in the zebra finch song system.

This study examines the development of two neural pathways within the zebra finch forebrain that function respectively in the juvenile acquisition and the adult production of learned song. In the adult male zebra finch forebrain, the song nuclei L-MAN and HVc both innervate nucleus RA; L-MAN plays a crucial role in juvenile song acquisition but, unlike HVc and RA, is not essential for adult song production. Previous studies have shown that HVc axons arrive at the dorsal border of RA as early as posthatch day 15 (day 15), and only enter the male RA after days 25-30, but never enter the female RA. The present study examines the development of axonal projections from L-MAN to RA and finds that, in contrast to HVc axons, L-MAN terminals are present within the male and female RA by day 15, and persist there throughout adult life. Unlike RA-projecting HVc neurons, HVc neurons projecting to area X innervate this target by day 20. Like L-MAN, area X plays a transient role in song acquisition. These results suggest that in the zebra finch forebrain, neural pathways essential to juvenile song learning develop before those needed for adult song production.

Animals↗
PubMed1994

Age-related changes in guinea pig prostatic stroma.

BACKGROUND: The histology of benign disease of the human prostate (benign prostatic hyperplasia) is heterogeneous. No other species demonstrates the same complexity, and current animal models do not appear to fully encompass the stromal and epithelial developmental changes involved in the human disease. This study describes age-related changes in the prostatic smooth muscle stroma of guinea pigs and humans, which may be pertinent to some aspects of the disease process in humans. EXPERIMENTAL DESIGN: Histologic and ultrastructural changes were examined and measured in the prostates of guinea pigs during aging (2 weeks to 31 months). Similar measurements were also made in human prostatic tissues during aging and the development of benign prostatic pathology. RESULTS: Morphometric analyses of prostates in guinea pigs and men demonstrated similar changes in stromal volume with age. The stromal volume proportion of the prostate in both species decreases at puberty due to the expansion of the epithelial cell compartment, and is followed by a progressive increase during adulthood until a maximum stromal content of approximately 75% of total tissue volume is reached at age 2 years in guinea pigs, and at age 70 years in men. The pathognomic feature of nodularity and the dramatic increase in gland size observed during the late stages of human benign prostatic disease did not occur in the guinea pig prostate. Ultrastructural analysis of guinea pig prostatic smooth muscle cells identified a progressive hypertrophy (approximately 10-fold) from prepuberty through to old age. Two-thirds of smooth muscle cells in the prostatic stroma of aging individuals of both species demonstrated perinuclear organelles (rough endoplasmic reticulum and free ribosomes) that were not present in younger individuals. CONCLUSIONS: The prominent histologic features of the guinea pig prostate during aging are increased stromal mass, significant stromal fibrosis, and occasional prostatitis. These features are frequently observed in men with clinical benign prostatic hyperplasia. The age-related increases in prostatic smooth muscle cell size and content of perinuclear organelles in the guinea pig suggest a re-activation of cellular synthetic activity. The similarity in some features of the prostatic smooth muscle stroma between aging men and guinea pigs suggests that there may be common pathophysiologic processes. We conclude that the guinea pig could be a useful model for examination of the age-related hypertrophy of the smooth muscle cell and the processes inducing reversion to a more synthetic smooth muscle cell phenotype.

Adolescent↗
PubMed1993

An outbreak of infection with Salmonella enteritidis phage type 4 associated with the use of raw shell eggs.

A community outbreak of Salmonella enteritidis phage type (PT) 4 infection, associated with eating food from a sandwich bar in Colchester, occurred in July 1991. One hundred and forty-four people were reported with food poisoning, of whom 132 met the clinical case definition. Three cohort studies of 92 people showed that illness was associated with the consumption of food containing mayonnaise. S. enteritidis PT4, indistinguishable by plasmid profile analysis, was isolated from stool samples from 83 people, food items including egg shells from the sandwich bar, and birds taken from the egg producing farm which supplied the eggs. This was the largest recorded outbreak of S. enteritidis PT4 infection in recent years associated with eggs produced in the United Kingdom. Existing advice on avoiding the use of raw eggs in uncooked dishes had not been followed. This outbreak highlights the importance of training in the implementation of this advice.

Adolescent↗
PubMed1993

Correlation of epithelial proliferation and squamous esophageal histology in 1185 biopsies from Linxian, China.

Epithelial proliferation is an active area of research in gastrointestinal cancer, but only a few studies have examined the relationship of esophageal epithelial proliferation and squamous histologic findings in populations with high rates of squamous esophageal cancer. In order to study this correlation, tritiated thymidine labeling was performed on 1185 esophageal biopsies from 745 residents of Linxian, China, a county with some of the highest esophageal-cancer rates in the world. Total labeling index (TLI = total labeled cells/total cells counted) was used to measure the amount of proliferation, and the proportion of labeled cells found in cell layers 4 to 10 (labeled cell fraction 4 plus, LF4+ = labeled cells in layers 4-10/total labeled cells) was used to measure the vertical distribution of proliferation. Of the biopsies, 979 were histologically normal, 51 showed acanthosis, 35 showed esophagitis, 116 showed squamous dysplasia, and 6 showed invasive squamous cancer. The mean values of both proliferation variables, stratified by histologic diagnosis, showed the following relationships: normal = acanthosis < esophagitis = dysplasia < cancer. The ranges of proliferation values overlapped extensively in all biopsy categories, so that measuring proliferation could not substitute for histologic diagnosis. It remains to be seen whether proliferation values, histologic diagnoses, or some combination of these methods is most predictive of subsequent esophageal cancer.

Adult↗
PubMed1993

Chromosomal gene integration and enhanced xylanase production in an alkalophilic thermophilic Bacillus sp. (NCIM 59).

Chromosomal integration and xylanase gene amplification were demonstrated for the first time in an alkalophilic thermophilic Bacillus sp. (NCIM 59). The integrants were characterized by larger zone of xylan clearance than the parent culture and hybridization with vector (pUC8) DNA. Repeated transformation strategy was used for further amplification of the xylanase gene. The results of Southern blot analysis indicated the occurrence of homologous recombination in the 6.5 kb xylanase gene region of the genomic DNA and suggested a non campbell mode of recombination. The integrants were checked for xylanase production up to ten subcultures and consistently showed two fold higher xylanase activity than the parent strain with the maximum xylanase productivity (U/ml/h) at 16 h.

Bacillus↗
PubMed1993

Antibody response to accelerated immunisation with diphtheria, tetanus, pertussis vaccine.

From May, 1990, a new schedule of immunisation against diphtheria, tetanus, and pertussis (at 2, 3, and 4 months) replaced the previous more widely spaced schedule. A report that children had lower concentrations of diphtheria and tetanus antibodies a month after an accelerated schedule led us to undertake a controlled study to assess antibody response and the persistence of antibodies a year after immunisation in children receiving vaccine according to widely spaced and accelerated schedules. Concentrations of antibodies to diphtheria and tetanus toxoids and to Bordetella pertussis filamentous haemagglutinin (FHA) were measured by solid-phase radioimmunoassay (SP-RIA). We studied 57 children who received accelerated immunisation at median ages of 11, 16, and 21 weeks and two control cohorts (total n = 82) who received vaccine at median ages of 15, 21, and 45 weeks. 6-8 weeks after the third dose the accelerated-schedule group had lower (p < 0.0001) geometric mean concentrations of antibody to tetanus (0.522 [95% CI 0.383-0.710] vs 3.43 [2.45-4.81] IU/mL), diphtheria (0.266 [0.179-0.396] vs 2.39 [0.616-3.53] IU/mL), and FHA (0.044 [0.030-0.063] vs 0.270 [0.196-0.374] units/mL) than the longer-schedule group. 12 months after the third dose the differences between the groups had narrowed (tetanus 0.197 vs 0.341 IU/mL, p = 0.29; diphtheria 0.100 vs 0.131 IU/mL, p = 0.64; FHA 0.014 vs 0.016 units/mL, p = 0.72). At that time all children had tetanus antibody concentrations above protective levels (0.01 IU/mL); only 2 of 31 in the accelerated-schedule group and 3 of 31 in the longer-schedule group had diphtheria antibody concentrations below the protective level. The use of an accelerated schedule of diphtheria, tetanus, and pertussis vaccination is unlikely to lead to an increase in the proportion of children unprotected against these diseases before the preschool booster.

Antibodies, Bacterial↗
PubMed1993

Cloning and extracellular expression in Escherichia coli of xylanases from an alkaliphilic thermophilic Bacillus sp. NCIM 59.

A genomic DNA library of an alkaliphilic thermophilic Bacillus was constructed in Escherichia coli with pUC 8 vector and was screened using a Congo red xylan plate clearance assay. Six xylanase positive transformants having identical inserts showed immunological reactivity towards polyclonal antibodies raised against purified xylanase (M(r) 15,800) from the Bacillus. A 4.5-kb HindIII-EcoRI subfragment was found to code for two xylanases of M(r) 14,500 and 35,000. Equivalent amounts of xylanase activity were detected from IPTG induced and noninduced recombinants irrespective of the orientation of the 4.5-kb insert with respect to the lac promoter, indicating that xylanase gene expression was under the control of its own promoter. 95% of the xylanase activity (2 U/ml) was found in the extracellular culture filtrate. The hydrolysis of xylan by the recombinant xylanases yielded mainly xylobiose.

Bacillus↗