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Biomedical subjects

M Rao

Publications and source records attributed to M Rao.

At least 163 records · Page 9Linked to original sources
PubMed1993

Specific interaction of guanidine hydrochloride with essential carboxyl group of xylanase from alkalothermophilic Bacillus sp.

Experimental evidence for the specific interaction of guanidine hydrochloride with the carboxyl group of xylanase has been presented for the first time. Guanidine hydrochloride (0.1 M) inactivated the xylanase from alkalothermophilic Bacillus sp. to 50% without affecting the conformation of the protein as determined by the fluorometric profile. The kinetic analysis indicated a competitive type of inhibition and a requirement of 1.4 molecules of guanidine hydrochloride per molecule of the enzyme for inhibition. Maximum inhibition occurred at the pH which is optimum for the enzyme activity. The reaction of guanidine hydrochloride with the enzyme prior to modification by Woodward's Reagent K, a specific inhibitor of the carboxyl group, made it inaccessible for modification as indicated by absorbance data at 340 nm. Urea, sodium dodecyl sulphate, LiCl, KCl and NaCl at 0.1 M concentration each had negligible effect on the enzyme activity.

Bacillus↗
PubMed1993

The oligomeric nature of the murine Fc epsilon RII/CD23. Implications for function.

The low affinity receptor for IgE (Fc epsilon RII/CD23) is a type II integral membrane protein with an extracellular C-terminal region homologous to C-type animal lectins. Immediately adjacent to this lectin homology region is a sequence that is predicted to form an alpha-helical coiled-coil stalk leading to dimer or trimer formation. This provides an explanation for the known self-associative capacity for the Fc epsilon RII. In this study the self-association to a trimer or tetramer is shown with rFc epsilon RII by chemical cross-linking and affinity purification on IgE columns. The data indicate that only the oligomeric form of Fc epsilon RII has sufficient affinity/avidity to bind to an IgE adsorbent. In contrast, Fc epsilon RII that is purified using anti-Fc epsilon RII mAb adsorbents has largely lost its capacity to bind IgE, as well as its capacity to self-associate, indicating that IgE recognizes the oligomeric form of the Fc epsilon RII. This phenomenon was further examined by performing detailed binding analysis of the mouse IgE/Fc epsilon RII interaction. A biphasic binding curve with high (2-7 x 10(7) M-1) and low (2-7 x 10(6) M-1) affinity binding was seen. Fc epsilon RII mutants were prepared that lack one or more of the 21 amino acid homologous repeat domains in the stalk region of the molecule. These mutant Fc epsilon RII molecules bound IgE with only a single low affinity (5-10 x 10(6) M-1). In addition, cross-linking analysis of one of these mutants demonstrated that it does not exhibit the receptor self-association seen for the intact Fc epsilon RII. Two chimeric Fc epsilon RII molecules were prepared having the mouse Fc epsilon RII lectin homology (carboxyl-terminal) region and the stalk region of either the related human Fc epsilon RII or the corresponding domain of Ly-49. Chimeric molecules using the former (alpha-helical coiled-coil) stalk supported normal binding of IgE although the Ly-49/Fc epsilon RII chimera failed to bind IgE. Taken together, the results indicate that high (approximately 10(8) M-1) affinity IgE binding results from interaction of multiple lectin domains with (presumably) symmetrical sites on the IgE molecule. Specificity for IgE is determined by the lectin domain although the binding avidity is determined by oligomerization through the coiled coil stalk.

Animals↗
PubMed1993

Chromosomal location and isoform analysis of mouse Fc epsilon RII/CD23.

The gene for the mouse low affinity receptor for IgE (Fc epsilon RII, also known as CD23) was mapped on Chromosome (Chr) 8 proximal to Plat. This gene, symbolized Fcer2 (formerly Fce2) resides in a region of Chr 8 with linkage homology with human chromosomes 8 and 19. The mouse Fc epsilon RII was examined for the presence of alternate N-terminal forms such as seen in humans. An antisense RNA probe was prepared from the 5' end of the cDNA through the first 660 bp of the cDNA and was used to analyze message from Fc epsilon RII+ B cells and B cell hybridomas both before and after treatment with interleukin 4 (IL-4). Using RNase protection analysis, a major 640 bp band corresponding to the full length probe was seen, even after activation of the cells with LPS in the presence of IL-4, which is known to give high expression levels of the Fc epsilon RII. This result suggests that the mouse does not produce significant levels of an alternate IL-4 inducible Fc epsilon RII, as seen in man, and this may explain the more restricted cell lineage expression of the Fc epsilon RII in the mouse.

Animals↗
PubMed1993

Alveolar-arterial oxygen gradient in acute chest syndrome of sickle cell disease.

In 44 episodes of acute chest syndrome of sickle cell disease occurring in 37 children, simple clinical severity score, duration of hospital stay, transfusion data, and alveolar-arterial oxygen gradient were analyzed as indicators of severity of disease. The alveolar-arterial oxygen gradient, measured during breathing of room air, proved, on multivariate analysis, to be the strongest predictor of both clinical severity and the need for blood transfusion.

Acute Disease↗
PubMed1993

The design and analysis of cholera vaccine trials: recent lessons from Bangladesh.

The recent spread of cholera to Latin America, together with the persistent burden of this disease in Asia and Africa, have stimulated efforts to evaluate new cholera vaccines in field settings. Although the standard experimental paradigm for vaccine field trials is well established, the success of these trials will also depend on suitable consideration of the epidemiology of cholera and of cholera vaccination in the setting under study. Epidemiological studies done in Bangladesh emphasize the importance of appreciating the poorly predictable, multifocal occurrence of cholera in estimating a probable incidence of cholera for a field trial. They also underscore how the filtering effect of enrolling subjects into a prospective trial can dramatically reduce the available population for study, and can yield a study sample whose expected risk of cholera differs markedly from that for the source population. Finally, the data highlight the subtle effects that the mode of surveillance and the choice of an outcome definition can have upon protective efficacy, and emphasize the need for subgroup analyses that address the distinctive variations in vaccine protection that may occur in subjects differing in age and in ABO blood groups, and in subjects exposed to classical versus El Tor cholera.

ABO Blood-Group System↗
PubMed1993

Passive immunotherapy in the treatment of advanced human immunodeficiency virus infection.

To evaluate the safety and efficacy of passive immunotherapy for advanced human immunodeficiency virus (HIV) infection, a randomized, double-blind, controlled trial of human anti-HIV hyperimmune plasma was conducted. Sixty-three subjects with stage IV HIV disease (AIDS) were randomized to received 250 mL of either HIV-immune plasma or HIV antibody-negative plasma every 4 weeks. Although nonsignificant trends toward improved survival and delayed occurrence of a new opportunistic infection were noted, no significant effects on absolute CD4 lymphocyte counts or quantitative HIV viremia were seen. The only notable toxicity was the allergenicity to be expected from infusing plasma products, usually manifesting as urticaria. Thus, results do not rule out the potential usefulness of passive immunization with different preparations, but did fail to demonstrate clinical benefit of the product studied.

Adult↗
PubMed1993

Respiratory syncytial virus illnesses in human immunodeficiency virus- and noninfected children.

Respiratory syncytial virus (RSV) lower respiratory tract and febrile upper respiratory tract illnesses were prospectively assessed in cohorts of 83 infants born to human immunodeficiency virus (HIV)- and of 48 infants born to non-HIV-infected mothers. Of the infants born to HIV-infected mothers, 18 were themselves infected with HIV, 26 were indeterminant and 39 were free from HIV. Ten RSV illnesses occurred in 8 HIV-infected, 2 illnesses in 2 indeterminant and 17 illnesses occurred in 17 non-HIV-infected children. RSV shedding was prolonged in HIV class P2- vs. non-HIV-infected children, at medians of 30 days (range, 1 to 199 days) and 6 days (range, 1 to 21 days), respectively (P = 0.02). Ribavirin and intravenous immunoglobulin failed to eradicate RSV from one child who shed virus for 199 days. Wheezing occurred in 1 of 4 vs. 9 of 10 episodes of lower respiratory tract illness in HIV-infected and non-HIV-infected children, respectively (P = 0.04). No differences were noted in duration of illness, temperature, respiratory rate or oxygen saturation between HIV- and non-HIV-infected children. Infection control and public health concerns regarding prolonged shedding of RSV in HIV-infected children must be recognized.

AIDS-Related Opportunistic Infections↗
PubMed1993

Effect of hemodialysis on left ventricular contractility in pediatric patients with end-stage renal disease.

Assessment of the effect of hemodialysis on myocardial contractility is complicated by variations in loading conditions that can occur during hemodialysis and by the prevalence of coronary artery disease among patients with chronic renal failure. Therefore, we used a load-independent index of left ventricular contractility, derived from analyses of the rate corrected velocity of circumferential fiber shortening (Vcfc)-end systolic wall stress (ESWS) relationship, to study the acute effects of hemodialysis on left ventricular function in the cases of 15 pediatric patients with end-stage renal disease. Prior to dialysis, Vcfc was appropriate for ESWS (102% +/- 16% of predicted) and did not differ significantly from values obtained from a group of nine normal control subjects of similar ages (103% +/- 9% of predicted), indicating that the patients' left ventricles were functioning in a normal inotropic state. After dialysis, Vcfc increased to levels beyond those expected for ESWS (118% +/- 20% of predicted, P < .05 versus control; P < .001 versus predialysis levels), indicating that dialysis was associated with enhancement of the left ventricle's inotropic state. A statistically significant increase in plasma norepinephrine levels was also observed. However, the increase in the percentage of the predicted Vcfc did not correlate with observed changes in this inotropic agent or with dialysis-induced variations in body weight or levels of electrolytes, urea nitrogen, or creatinine, and firm conclusions regarding the identity of the factors responsible for the positive inotropic effect of hemodialysis could not be drawn.

Adolescent↗
PubMed1993

Live related renal transplantation for end stage diabetic nephropathy.

We report our results with live related renal transplantation in 43 diabetics, most of whom were non-insulin dependent, with end stage renal disease. The overall one year patient survival was 72.1% and graft survival was 65.1%. The use of Cyclosporine was associated with a significant improvement in the one year patient and graft survival (92.3% and 84.6% respectively). The most important cause of mortality was infection. Live related renal transplantation with Cyclosporine as immunosuppression is advisable for the uremic diabetic.

Actuarial Analysis↗
PubMed1993

Changes in ribosomal protein and ribosomal RNA synthesis during rat intestinal differentiation.

Subtraction hybridization studies, used to identify genes involved in the control of enterocyte proliferation and/or differentiation, allowed detection of a clone shown to have homologies with rat, chicken, and human acidic ribosomal phosphoprotein P1. Since increases in P1 transcript have been associated with intestinal malignancy, we explored the relationship of P1 and other ribosomal proteins to normal intestinal proliferation and differentiation. Male rats were used to prepare enterocytes as isolated cell fractions representative of the crypt to villus axis of differentiation. Total RNA was extracted from pooled cell fractions and evaluated for mRNA and rRNA steady-state levels. Nuclei were prepared from isolated enterocytes, and nuclear runoff studies were performed to estimate rates of nascent transcription. The P1 complementary DNA from the crypt cell library detected a mRNA of 650 base pairs which showed approximately 8-fold greater steady-state levels in crypt than in villus cells. Similar crypt specificity was also noted for mRNAs coding for elongation factor EF-12 and for ribosomal proteins P0, P1, and S6 (using clones from Y-L. Chan and I. G. Wool). In contrast, 28S rRNA steady-state levels did not differ between villus and crypt, indicating that ribosomal content had remained constant. In situ hybridization studies confirmed the predominant crypt localization of P1 mRNA. Nascent transcription rate studies showed that the proportion of newly synthesized P1 mRNA to total RNA was the same for the villus and crypt, suggesting that the lower content of villus P1 mRNA may be due to increased degradation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Breast-feeding and the risk of life-threatening rotavirus diarrhea: prevention or postponement?

PURPOSE: To assess the relationship between breast-feeding and the risk of life-threatening rotavirus diarrhea among Bangladeshi infants and children younger than 24 months of age. DESIGN: Case-control study. SETTING: A rural Bangladesh community. PARTICIPANTS: One hundred two cases with clinically severe rotavirus diarrhea detected in a treatment center-based surveillance system during 1985 and 1986, and 2587 controls selected in three surveys of the same community during the same calendar interval. OUTCOMES: Cases and controls were compared for the frequency of antecedent breast-feeding patterns. RESULTS: Compared with other feeding modes, exclusive breast-feeding of infants was associated with significant protection against severe rotavirus diarrhea (relative risk (RR) = 0.10; 95% confidence interval [CI] = 0.03, 0.34). However, during the second year of life, the risk of this outcome was higher in breast-fed than in non-breast-fed children (RR = 2.85; 95% CI = 0.37, 21.71), and no overall protection was associated with breast-feeding during the first 2 years of life (RR = 2.61; 95% CI = 0.62, 11.02). CONCLUSIONS: Although exclusive breast-feeding appeared to protect infants against severe rotavirus diarrhea, breast-feeding per se conferred no overall protection during the first 2 years of life, suggesting that breast-feeding temporarily postponed rather than prevented this outcome. While not detracting from efforts to promote breast-feeding to alleviate the burden of diarrhea due to nonrotaviral enteropathogens, our findings cast doubt on whether such efforts will impact on the problem of severe rotavirus diarrhea.

Bangladesh↗
PubMed1992

Symptoms after accelerated immunisation.

OBJECTIVE: To document the incidence of symptoms after accelerated immunisation with diphtheria-tetanus-pertussis vaccine. DESIGN: Controlled study of children immunised with adsorbed diphtheria-tetanus-pertussis vaccine at accelerated and standard schedules. SETTING: Colchester and north Hertfordshire. SUBJECTS: 107 children scheduled to receive immunisation at 2, 3, and 4 months of age and 115 children scheduled to receive immunisation at 3, 4 1/2 to 5, and 8 1/2 to 11 months of age. MAIN OUTCOME MEASURES: Parentally recorded symptoms, axillary temperatures, and size of local redness and swelling at the injection site during the seven days after immunisation. RESULTS: In general symptoms occurred less frequently with the accelerated schedule. Proportions of parents reporting axillary temperatures greater than 37.2 degrees C or local redness or swelling greater than 2.5 cm after the third dose of vaccine were significantly reduced in the accelerated schedule group. CONCLUSION: Immunisation at 2, 3, and 4 months of age is likely to cause fewer reactions than immunisation at 3, 4 1/2 to 5, and 8 1/2 to 11 months of age.

Diphtheria-Tetanus-Pertussis Vaccine↗
PubMed1992

Nonparticipation as a determinant of adverse health outcomes in a field trial of oral cholera vaccines.

The authors estimated the incidence rates of cholera and death between 1985 and 1988 for 32,642 age- and sex-eligible persons who did not participate in a randomized, placebo-controlled field trial of killed oral cholera vaccines in rural Bangladesh. As compared with 20,744 placebo recipients, the relative risk of cholera for all nonparticipants, adjusted for potentially confounding demographic variables, was 1.20 (95% confidence interval (CI) 1.03-1.41); this adjusted relative risk reflected elevated adjusted relative risks in nonparticipants who were medically ineligible (RR = 1.65; 95% CI 1.22-2.22) or refused to participate (RR = 1.19; 95% CI 1.01-1.41), but not in persons absent at the time of vaccination (RR = 1.00; 95% CI 0.78-1.28). The adjusted relative risk of death was also elevated in nonparticipants as compared with placebo recipients (RR = 1.28; 95% CI 1.10-1.48), with the same pattern of adjusted relative risks for different categories of nonparticipants: for ineligible subjects, 2.64 (95% CI 2.12-3.29); for refusers, 1.20 (95% CI 1.02-1.41); and for absentees, 0.95 (95% CI 0.75-1.22). The authors concluded that nonparticipation was associated with clinically cogent adverse health outcomes, but that the magnitude of these associations varied according to the reason for nonparticipation. These findings underscore the caution required in assessing vaccine efficacy with controls who are not vaccinated because of choices made by patients or vaccinators.

Administration, Oral↗