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Biomedical subjects

M Rao

Publications and source records attributed to M Rao.

At least 19 recordsLinked to original sources
PubMed1999

Reduction of cisplatin-induced nephrotoxicity by cystone, a polyherbal ayurvedic preparation, in C57BL/6J mice bearing B16F1 melanoma without reducing its antitumor activity.

The effect of cystone, a polyherbal ayurvedic preparation, on the nephrotoxicity and antitumor activity of cisplatin is studied in C57BL/6J mice bearing B16F1 melanoma. Intraperitoneal administration of cisplatin 6 mg/kg, resulted in significant reduction of body weight, elevation of blood urea nitrogen (BUN) and serum creatinine levels on day 5. Cystone was found to protect tumor-bearing mice from cisplatin-induced nephrotoxicity, when given i.p. 1 h before cisplatin. At 1000 mg/kg, it showed 46, 57 and 66% protection on body weight, BUN and serum creatinine levels, respectively. Treatment of cisplatin alone to tumor bearing mice resulted in significant antitumor activity as measured by tumor appearance, tumor volume and tumor weight. Pre-treatment with cystone (1000 mg/kg) did not reduce the antitumor activity of cisplatin. These results suggested that cystone protects against cisplatin-induced nephrotoxicity without interfering with its antitumor activity. The present study has many clinical implications in cisplatin chemotherapy.

Animals↗
PubMed1999

Xylanase II from an alkaliphilic thermophilic Bacillus with a distinctly different structure from other xylanases: evolutionary relationship to alkaliphilic xylanases.

A 1.0 kilobase gene fragment from the genomic DNA of an alkaliphilic thermophilic Bacillus was found to code for a functional xylanase (XynII). The complete nucleotide sequence including the structural gene and the 5' and 3' flanking sequences of the xylanase gene have been determined. An open reading frame starting from ATG initiator codon comprising 402 nucleotides gave a preprotein of 133 amino acids of calculated molecular mass 14.090 kDa. The occurrence of three potential N-glycosylation sites in XynII gene is a unique feature for a gene of bacterial origin. The stop codon was followed by hairpin loop structures indicating the presence of transcription termination signals. The secondary structure analysis of XynII predicted that the polypeptide was primarily formed of beta-sheets. XynII appeared to be a member of family G/11 of xylanases based on its molecular weight and basic pI (8.0). However, sequence homology revealed similar identity with families 10 and 11 of xylanases. The conserved triad (Val-Val-Xaa, where Xaa is Asn or Asp) was identified only in the xylanases from alkaliphilic organisms. Our results implicate for the first time the concept of convergent evolution for XynII and provide a basis for research in evolutionary relationship among the xylanases from alkaliphilic and neutrophilic organisms.

3' Untranslated Regions↗
PubMed1999

Heparin is a unique marker of progenitors in the glial cell lineage.

The oligodendrocyte-type-2 astrocyte progenitor cells (precursors of oligodendrocytes and type-2 astrocytes) are an excellent system in which to study differentiation as they can be manipulated in vitro. Maintenance of oligodendrocyte-type-2 astrocyte progenitor cells requires basic fibroblast growth factor, a growth factor whose action normally depends on a heparan sulfate coreceptor. Biochemical analysis revealed a most surprising result: that the oligodendrocyte-type-2 astrocyte progenitors did not synthesize heparan sulfate, the near ubiquitous N-sulfated cell surface polysaccharide, but the chemically related heparin in a form that was almost completely N- and O-sulfated. The heparin was detected in the pericellular fraction of the cells and the culture medium. In contrast the differentiated glial subpopulations (oligodendrocytes and type-2 astrocytes) synthesized typical heparan sulfate but with distinctive fine structural features for each cell type. Thus heparin is a unique differentiation marker in the glial lineage. Previously heparin has been found only in a subset of mature mast cells called the connective tissue mast cells. Its presence within the developing nervous system on a precise population of progenitors may confer specific and essential recognition properties on those cells in relation to binding soluble growth and/or differentiation factors and the extracellular matrix.

Animals↗
PubMed1999

Typhoid fever in children aged less than 5 years.

BACKGROUND: Calculation of the incidence of typhoid fever during preschool years is important to define the optimum age of immunisation and the choice of vaccines for public-health programmes in developing countries. Hospital-based studies have suggested that children younger than 5 years do not need vaccination against typhoid fever, but this view needs to be re-examined in community-based longitudinal studies. We undertook a prospective follow-up study of residents of a low-income urban area of Delhi, India, with active surveillance for case detection. METHODS: A baseline census was undertaken in 1995. Between Nov 1, 1995, and Oct 31, 1996, we visited 8172 residents of 1820 households in Kalkaji, Delhi, twice weekly to detect febrile cases. Blood samples were obtained from febrile patients, and those who tested positive for Salmonella typhi were treated with ciprofloxacin. FINDINGS: 63 culture-positive typhoid fever cases were detected. Of these, 28 (44%) were in children aged under 5 years. The incidence rate of typhoid per 1000 person-years was 27.3 at age under 5 years, 11.7 at 5-19 years, and 1.1 between 19 and 40 years. The difference in the incidence of typhoid fever between those under 5 years and those aged 5-19 years (15.6 per 1000 person-years [95% CI 4.7-26.5]), and those aged 19-40 years (26.2 [16.0-36.3]) was significant (p<0.001 for both). The difference between the incidence of typhoid at 5-19 years and the incidence at 19-40 years was also significant (10.6 [6.3-14.8], p<0.001). Morbidity in those under 5 and in older people was similar in terms of duration of fever, signs and symptoms, and need for hospital admission. INTERPRETATION: Our findings challenge the common view that typhoid fever is a disorder of school-age children and of adults. Typhoid is a common and significant cause of morbidity between 1 and 5 years of age. The optimum age of typhoid immunisation and the choice of vaccines needs to be reassessed.

Adolescent↗
PubMed1999

Cytotoxic T lymphocytes to Ebola Zaire virus are induced in mice by immunization with liposomes containing lipid A.

An eight amino acid sequence (TELRTFSI) present in the carboxy terminal end (aa 577-584) of membrane-anchored GP, the major structural protein of Ebola virus, was identified as an H-2k-specific murine cytotoxic T cell epitope. Cytotoxic T lymphocytes (CTLs) to this epitope were induced by immunizing B10.BR mice intravenously with either irradiated Ebola virus or with irradiated Ebola virus encapsulated in liposomes containing lipid A. The CTL response induced by irradiated Ebola virus could not be sustained after the second round of in vitro stimulation of immune splenocytes with the peptide, unless the irradiated virus was encapsulated in liposomes containing lipid A. The identification of an Ebola GP-specific CTL epitope and the requirement of liposomal lipid A for CTL memory recall responses could prove to be a promising approach for developing a vaccine against Ebola virus infection.

Animals↗
PubMed1999

Enhanced contractility and decreased beta-adrenergic receptor kinase-1 in mice lacking endogenous norepinephrine and epinephrine.

BACKGROUND: Elevated circulating norepinephrine (NE) has been implicated in causing the profound beta-adrenergic receptor (betaAR) downregulation and receptor uncoupling that are characteristic of end-stage human dilated cardiomyopathy, a process mediated in part by increased levels of beta-adrenergic receptor kinase (betaARK1). To explore whether chronic sustained NE stimulation is a primary stimulus that promotes deterioration in cardiac signaling, we characterized a gene-targeted mouse in which activation of the sympathetic nervous system cannot lead to an elevation in plasma NE and epinephrine. METHODS AND RESULTS: Gene-targeted mice that lack dopamine beta-hydroxylase (dbh-/-), the enzyme needed to convert dopamine to NE, were created by homologous recombination. In vivo contractile response to the beta1AR agonist dobutamine, measured by a high-fidelity left ventricular micromanometer, was enhanced in mice lacking the dbh gene. In unloaded adult myocytes isolated from dbh-/- mice, basal contractility was significantly increased compared with control cells. Furthermore, the increase in betaAR responsiveness and enhanced cellular contractility were associated with a significant reduction in activity and protein level of betaARK1 and increased high-affinity agonist binding without changes in betaAR density or G-protein levels. CONCLUSIONS: Mice that lack the ability to generate NE or epinephrine show increased contractility associated primarily with a decrease in the level of betaARK1 protein and kinase activity. This animal model will be valuable in testing whether NE is required for the pathogenesis of heart failure through mating strategies that cross the dbh-/- mouse into genetically engineered models of heart failure.

Adrenergic beta-Agonists↗
PubMed1999

Extractive cultivation of recombinant Escherichia coli using aqueous two phase systems for production and separation of extracellular xylanase.

Recombinant Escherichia coli (pATBX 1.8) secreting extracellular xylanase was used as a model system to study the application of an aqueous two phase system for extractive cultivation. An increase in the polymer concentrations from 6 to 20% in the polyethylene glycol phosphate aqueous two phase system resulted in an increase in the phase volume ratio with a concomitant decrease in the partition coefficient (K) and recovery of xylanase in the top phase. However, varying phosphate concentrations from 8 to 16% decreased both the phase volume ratio and the partition coefficient of xylanase. The polyethylene glycol (6%) and phosphate (12%) system was found to be optimum for extracellular cultivation of E. coli, where extracellular xylanase was selectively partitioned to the top phase giving a purification ratio of above 1.0. The process was extended to a semicontinuous operating mode at the optimal condition, wherein the top phase containing xylanase was recovered and the surviving cells were recycled together with the new top phase. The maximum recovery of xylanase was obtained after 12 h in the top phase with a twofold increase in the specific activity as compared to the one obtained in the reference fermentation. In the present work, we report for the first time the use of the two phase system for the extractive cultivation of recombinant E. coli (pATBX 1.8) with the purpose of obtaining a simple and inexpensive separation procedure and achieving the maximal extraction of xylanase to one phase.

Bacteriological Techniques↗
PubMed1999

Trafficking of liposomal antigen to the trans-Golgi of murine macrophages requires both liposomal lipid and liposomal protein.

Major histocompatibility complex (MHC) class I molecules found on antigen-presenting cells present peptides derived from cytoplasmic proteins to T cells. In contrast, peptides from exogenous proteins are mostly presented by class II molecules. It has been well established that liposomes can serve as an efficient delivery system for entry of exogenous protein antigens into the MHC class I pathway. Our previous studies utilizing fluorophore-labeled proteins encapsulated in liposomes demonstrated that after phagocytosis of the liposomes by bone marrow-derived macrophages (BMs), the processed peptides were subsequently visualized in the trans-Golgi, while free conalbumin was excluded from the trans-Golgi area. In the present study, we investigated whether liposomal lipids follow the same intracellular route as the liposomal proteins after phagocytosis by BMs. Multilamellar liposomes with different lipid compositions that also contained fluorescent phospholipids (empty liposomes) were incubated with murine BMs. Our results indicate that although empty liposomes were avidly phagocytosed by macrophages, the fluorescent liposomal lipids did not localize to any particular area of the cell but were distributed throughout the cell. In contrast, when a protein was encapsulated in the liposomes, the liposomal lipids were no longer dispersed throughout the cell, but were concentrated and localized in the trans-Golgi area. Furthermore, when the liposomes contained a fluorescent-labeled protein, the fluorescent peptides also localized to the trans-Golgi. These results demonstrate that the combination of both liposomal lipids and liposomal protein is required for Golgi-specific targeting of liposomal antigens. Transport of both liposomal lipids and liposomal proteins to the Golgi complex, a major subcellular organelle in the passage of MHC class I molecules, might explain why antigens encapsulated in liposomes readily induce cytotoxic T lymphocytes.

Animals↗
PubMed1999

Effect of treating obstructive sleep apnea by tonsillectomy and/or adenoidectomy on obesity in children.

BACKGROUND: Obstructive sleep apnea is common in obese children who have enlarged tonsils and adenoids. OBJECTIVE: To determine if treatment of obstructive sleep apnea by tonsillectomy and/or adenoidectomy will result in normalization of an obese child's weight, as it does in underweight children, and as it does with other signs and symptoms. DESIGN: Retrospective cohort study. We recorded weight and height changes after tonsillectomy and/or adenoidectomy and compared changes of the obese and morbidly obese patients with those of the other patients. SETTING: A tertiary care inner-city hospital. PARTICIPANTS: Children (n = 45) who underwent tonsillectomy and/or adenoidectomy for obstructive sleep apnea in 1994-1995; their mean (+/-SD) age was 4.9+/-2.4 years at operation. RESULTS: At the time of surgery, 25 children were of normal weight; 3, underweight; 7, obese; and 10, morbidly obese. Postoperatively, 31 children (69%), including 10 of the 17 who were obese or morbidly obese, had substantial weight gain: the z score +/- SD for weight of the entire group increased from 1.37+/-2.49 to 2+/-2.27 (P<.001). The mean z score +/- SD for height increased from 0.03+/-1.08 to 0.58+/-0.94 (P<.001). The body mass index (BMI or Quetelet index): calculated as weight in kilograms divided by the square of the height in meters increased in 28 patients (62%) (P = .004). CONCLUSION: Treating obstructive sleep apnea by tonsillectomy and/or adenoidectomy is associated with increased gain in height, weight, and body mass index in most children, including the obese and morbidly obese.

Adenoidectomy↗
PubMed1999

A dietary survey in Indian hemodialysis patients.

Malnutrition is a common problem in maintenance hemodialysis (MHD) patients, and compromised intake is an important cause. There is no information available about the nutrient intakes of MHD patients in India. The nutrient intakes of 106 MHD patients were studied cross-sectionally and on follow-up. A 24-hour recall was used on 4 consecutive days. After 2 months on dialysis, the mean energy intake was 29 +/- 6.6 kcal/kg ideal body weight (IBW) and the mean protein intake was.93 +/-.39 g/kg IBW (high biological value [HBV] protein 49% +/- 8.5%). Dietary deficiency of both protein and calories was present in 64.9%. Intake was better on nondialysis days compared with dialysis days, and in women and older patients. On follow-up there was no significant increase in food intake up to 6 months. After that, the total calorie intake increased significantly with a disproportionate drop in high biological value protein consumed and appeared to be derived predominantly from carbohydrate food (mean kcal/kg, 37 +/- 6.9; mean protein g/kg, 0.96 +/- 0.19; ratio of HBV protein to total protein consumed,.42 +/-.09). In summary this study showed suboptimal energy and protein intake in an MHD population. Intakes were further compromised on dialysis days, and with increasing time spent on dialysis, the quality of nutrient intake became poorer.

Adult↗
PubMed1999

Oral, inactivated, whole cell enterotoxigenic Escherichia coli plus cholera toxin B subunit vaccine: results of the initial evaluation in children. PRIDE Study Group.

Two randomized, double-blinded trials assessed the safety and immunogenicity of an oral, killed enterotoxigenic Escherichia coli (ETEC) plus cholera toxin B subunit vaccine in Egyptian children. Two doses of vaccine or E. coli K-12 were given 2 weeks apart to 105 6- to 12-year-olds and 97 2- to 5-year-olds. Safety was monitored for 3 days after each dose. Blood was collected before immunization and 7 days after each dose to measure immune responses. Few children reported postdosing symptoms, with no differences in the frequency of symptoms between treatment groups. Most vaccinees had an IgA antibody-secreting cell response against colonization factor antigen I (100%, 6-12 years; 95%, 2-5 years), coli surface antigen 2 (92%, 6-12 years; 83%, 2-5 years), and coli surface antigen 4 (93%, 6-12 years). Vaccination evoked a >/=4-fold rise in antitoxic IgA and IgG titers in 93% and 81% of children, respectively. In conclusion, the oral ETEC vaccine was safe and immunogenic in 2- to 12-year-old children, justifying further evaluation in infants.

Administration, Oral↗
PubMed1999

Epidemiology of enterotoxigenic Escherichia coli diarrhea in a pediatric cohort in a periurban area of lower Egypt.

Enterotoxigenic Escherichia coli (ETEC) are diverse pathogens that express heat-labile (LT) and/or heat-stable (ST) enterotoxins, yet little is known about whether epidemiologic patterns of pediatric ETEC diarrhea vary by the expressed ETEC toxin phenotype. In total, 242 Egyptian children aged <3 years were prospectively followed in 1993-1995. ETEC episodes were detected during twice-weekly home visits, and asymptomatic ETEC excretion was identified from monthly cross-sectional surveys. ETEC episodes were 0.6 per child-year. ST-only ETEC was 2.6 times (P<.001) more common in warmer than cooler months, while LT-only ETEC showed no seasonal variation. Ownership of a household sanitary latrine, but not breast-feeding, was associated with a lower risk of both enterotoxin phenotypes. Coexpression of a colonization factor by LT- or ST-only ETEC strengthened the association with diarrhea. These findings indicate that the epidemiologic patterns of LT-only and ST-only ETEC are not identical and that disease interventions should include improved household sanitation.

Cohort Studies↗
PubMed1999

In vitro and in vivo effects of phenolic antioxidants against cisplatin-induced nephrotoxicity.

We have investigated the effect of phenolic antioxidants on cisplatin-induced cytotoxicity in vero (African Green Monkey Kidney) cells and in rat renal cortical slices in vitro, and on cisplatin-induced nephrotoxicity in rats in vivo. Incubation of cisplatin with vero cells resulted in time- and concentration-dependent cytotoxicity, as characterized by decreased tryphan blue exclusion (TBE) and increased release of lactate dehydrogenase (LDH) into the medium. Cisplatin also caused reduction of glutathione (GSH) in a concentration-dependent manner. In the rat renal cortical slices model, incubation of cisplatin for 120 min caused an increase in malondialdehyde (MDA), a decrease in GSH and inhibited p-aminohippurate (PAH) uptake in a concentration-dependent manner. Among phenolic antioxidants, isoeugenol (IG) was found to be more active against cisplatin-induced cytotoxicity in vero cells as well as in rat renal cortical slices than eugenol (EG) and dehydrozingerone (DZ). However none of the test compounds were able to arrest the reduction of the GSH content induced by cisplatin in either the vero cells or the renal cortical slice model. Administration of cisplatin (3 mg/kg) i.p. to rats resulted in significant reduction of body weight, and elevation of blood urea nitrogen (BUN) and serum creatinine. Treatment with IG 10 mg/kg i.p. 1 h before cisplatin resulted in partial but significant protection against the cisplatin-induced reduction of body weight, and elevation of BUN and serum creatinine, the protection being 34, 46, and 62%, respectively. EG and DZ (10 mg/kg, i.p.) were found to be inactive in vivo. Because IG is a potent free radical scavenger and protects against cisplatin-induced toxicitiy, the present results have many clinical implications in chemotherapy and thus warrants further investigation.

Animals↗
PubMed1999

Molecular and biotechnological aspects of xylanases.

Hemicellulolytic microorganisms play a significant role in nature by recycling hemicellulose, one of the main components of plant polysaccharides. Xylanases (EC 3.2.1.8) catalyze the hydrolysis of xylan, the major constituent of hemicellulose. The use of these enzymes could greatly improve the overall economics of processing lignocellulosic materials for the generation of liquid fuels and chemicals. Recently cellulase-free xylanases have received great attention in the development of environmentally friendly technologies in the paper and pulp industry. In microorganisms that produce xylanases low molecular mass fragments of xylan and their positional isomers play a key role in regulating its biosynthesis. Xylanase and cellulase production appear to be regulated separately, although the pleiotropy of mutations, which causes the elimination of both genes, suggests some linkage in the synthesis of the two enzymes. Xylanases are found in a cornucopia of organisms and the genes encoding them have been cloned in homologous and heterologous hosts with the objectives of overproducing the enzyme and altering its properties to suit commercial applications. Sequence analyses of xylanases have revealed distinct catalytic and cellulose binding domains, with a separate non-catalytic domain that has been reported to confer enhanced thermostability in some xylanases. Analyses of three-dimensional structures and the properties of mutants have revealed the involvement of specific tyrosine and tryptophan residues in the substrate binding site and of glutamate and aspartate residues in the catalytic mechanism. Many lines of evidence suggest that xylanases operate via a double displacement mechanism in which the anomeric configuration is retained, although some of the enzymes catalyze single displacement reactions with inversion of configuration. Based on a dendrogram obtained from amino acid sequence similarities the evolutionary relationship between xylanases is assessed. In addition the properties of xylanases from extremophilic organisms have been evaluated in terms of biotechnological applications.

Amino Acid Sequence↗
PubMed1999

Phenotypic diversity of enterotoxigenic Escherichia coli strains from a community-based study of pediatric diarrhea in periurban Egypt.

No past studies of diarrhea in children of the Middle East have examined in detail the phenotypes of enterotoxigenic Escherichia coli (ETEC) strains, which are important pathogens in this setting. During a prospective study conducted from November 1993 to September 1995 with 242 children under 3 years of age with diarrhea living near Alexandria, Egypt, 125 episodes of diarrhea were positive for ETEC. ETEC strains were available for 98 of these episodes, from which 100 ETEC strains were selected and characterized on the basis of enterotoxins, colonization factors (CFs), and O:H serotypes. Of these representative isolates, 57 produced heat-stable toxin (ST) only, 34 produced heat-labile toxin (LT) only, and 9 produced both LT and ST. Twenty-three ETEC strains expressed a CF, with the specific factors being CF antigen IV (CFA/IV; 10 of 23; 43%), CFA/II (5 of 23; 22%), CFA/I (3 of 23; 13%), PCFO166 (3 of 23; 13%), and CS7 (2 of 23; 9%). No ETEC strains appeared to express CFA/III, CS17, or PCFO159. Among the 100 ETEC strains, 47 O groups and 20 H groups were represented, with 59 O:H serotypes. The most common O serogroups were O159 (13 strains) and O43 (10 strains). O148 and O21 were each detected in five individual strains, O7 and O56 were each detected in four individual strains, O73, O20, O86, and O114 were each detected in three individual strains, and O23, O78, O91, O103, O128, and O132 were each detected in two individual strains. The most common H serogroups were H4 (16 strains), 12 of which were of serogroup O159; H2 (9 strains), all of which were O43; H18 (6 strains); H30 (6 strains); and H28 (5 strains); strains of the last three H serogroups were all O148. Cumulatively, our results suggest a high degree of clonal diversity of disease-associated ETEC strains in this region. As a low percentage of these strains expressed a CF, it remains possible that other adhesins for which we either did not assay or that are as yet undiscovered are prevalent in this region. Our findings point out some potential barriers to effective immunization against ETEC diarrhea in this population and emphasize the need to identify additional protective antigens commonly expressed by ETEC for inclusion in future vaccine candidates.

Bacterial Proteins↗
PubMed1999

Early initiation of breastfeeding and the risk of infant diarrhea in rural Egypt.

BACKGROUND: Initiation of breastfeeding shortly after delivery may enhance breastfeeding's protective effect against diarrhea because of the protective properties of human colostrum contained in early breast milk. OBJECTIVE: To evaluate whether initiation of breastfeeding within the first 3 days of life, when breast milk contains colostrum, was associated with a lower rate of diarrhea in rural Egyptian infants during the first 6 months of life. METHODS: Infants initially breastfed (n = 198) were monitored prospectively with twice-weekly home visits to ascertain dietary practices and diarrheal illnesses. RESULTS: The burden of diarrhea during the first 6 months of life in the cohort was high: seven episodes per child-year of follow-up. Only 151 (76%) infants initiated breastfeeding during the first 3 days of life ("early initiation"). Infants in whom breastfeeding was initiated early had a 26% (95% CI: 2%,44%) lower rate of diarrhea than those initiated late. The protective association between early initiation and diarrhea was independent of the pattern of postinitiation dietary practices and was evident throughout the first 6 months of life. CONCLUSIONS: Early initiation of breastfeeding was associated with a marked reduction of the rate of diarrhea throughout the first 6 months of life, possibly because of the salutary effects of human colostrum. These data highlight the need for interventions to encourage early initiation of breastfeeding in less developed settings.

Breast Feeding↗