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Biomedical subjects

M Rao

Publications and source records attributed to M Rao.

At least 127 records · Page 7Linked to original sources
PubMed1996

Sociodemographic, hygienic and nutritional correlates of Helicobacter pylori infection of young Bangladeshi children.

BACKGROUND: By the age of 10 years most children in developing countries have been infected by Helicobacter pylori Identification of clues to modes of transmission of this organism to children, as well as evaluation of the sequelae of childhood infections, constitute important research priorities for developing countries. OBJECTIVES: To evaluate demographic, socioeconomic and hygienic factors associated with acquisition of infection by H. pylori early in childhood among Bangladeshi children ages 2 to 5 years and to assess whether infection by H. pylori was associated with poor nutritional status in these children and in an older group ages 6 to 9 years. METHODS: A random population-based survey of 257 rural Bangladeshi children ages 2 to 5 years and 312 children ages 6 to 9 years. Seropositivity for H. pylori, as manifested by the presence of serum IgG anti-H. pylori antibodies, was correlated with nutritional status of the sampled children and with sociodemographic features and access to clean water and latrine facilities among families of the children. RESULTS: Among children ages 2 to 5 years, the 123 (48%) who were infected by H. pylori were similar to the 134 noninfected children with respect to socioeconomic level, family access to tube well water and family ownership of a latrine. However, families of infected children had more persons per sleeping room in the home (3.8 vs. 3.2, P < 0.05) and were more likely to be Hindu (20% vs. 10%, P < 0.05). Infected children did not differ significantly from noninfected children in Z scores for weight-for-age (-2.66 vs. -2.78), weight-for-height (-1.17 vs. -1.28) or height-for-age (-3.58 vs. -3.56). Analysis of survey children ages 6 to 9 years also revealed similar nutritional indexes among infected vs. noninfected children. CONCLUSIONS: Household crowding and behaviors that differ between Hindus and Muslims, but not lack of access to clean water and latrines, may enhance the transmission of H. pylori to rural Bangladeshi children. Although confirming the high frequency of infections in young Bangladeshi children, our findings do not support the notion that H. pylori is responsible for the high prevalence of malnutrition in this setting.

Age Distribution↗
PubMed1996

[The effect of nimodipine and papaverine on delayed cerebral vasospasm in dogs].

OBJECTIVE: To evaluate the effect of nimodipine and papaverine (Pap) on the spastic arteries with delayed cerebral vasospasm (DCVS) in dogs. METHODS: A model of DCVS in dogs was induced by the cisterna magna injections of fresh autologous blood twice. The diameter of the basilar arteries with and without DCVS was measured with the aid of a JVC operative microes cope in vivo after nimodipine and Pap were directly placed around the arteries. RESULTS: The dilation of the basilar arteries was obviously induced by application of nimodipine and Pap in the dogs without DCVS no dilation was induced by application of nimodipine and slight dilation by application of Pap but in those with DCVS. CONCLUSION: The cerebral blood flow is improved by the effect of nimodipine on non-spastic arteries. Pap has been found to reverse slightly the narrowing of the basilar arteries with DCVS and to dilate the arteries without DCVS, but the vasodilation effect is transient.

Animals↗
PubMed1996

Physiological and clinical importance of nitric oxide.

Nitric oxide is an unusual messenger molecule with many physiologic roles, in the cardiovascular, neurologic and immune systems. It mediates blood vessel relaxation, neurotransmission and pathogen suppression. Two major categories of nitric oxide synthase enzyme produce nitric oxide. The constituent isoforms present in the endothelial cell and neurons release small amounts of nitric oxide intermittently to signal adjacent cells. The inducible isoforms found in macrophages release large amounts of nitric oxide continuously eliminating bacteria and parasites. Nitric oxide regulates blood pressure, transmits signals between neurons and suppresses pathogens. Excess amounts of nitric oxide may damage host cells causing neurotoxicity during strokes, and causing hypotension associated with sepsis. Further research is needed to understand the role of nitric oxide in the treatment of disease.

Cardiovascular Diseases↗
PubMed1995

Impaired immune response to natural infection as a correlate of vaccine failure in a field trial of killed oral cholera vaccines.

In a field trial carried out in 1985 in Matlab, Bangladesh, the authors evaluated whether subjects who developed Vibrio cholerae 01 infections during the first year after earlier receipt of B subunit-killed whole cell (BS-WC) or killed whole cell-only (WC) oral cholera vaccines exhibited deficient serum vibriocidal immune responses to these infections. After severe V. cholerae 01 infections (n = 70) in subjects > 5 years of age, the age group in which both vaccines were efficacious, a 6.5 geometric mean-fold rise of serum vibriocidal antibodies was observed among vaccinees, compared with an 18.6 geometric mean-fold rise in placebo-recipients (p < 0.01). Depressions of serum vibriocidal responses among vaccinees were even more marked after asymptomatic infections (n = 30): a 1.1 geometric mean-fold rise in vaccinees versus a 5.9 geometric mean-fold rise in placebo-recipients (p < 0.01). The authors conclude that subjects who failed to be protected by BS-WC and WC, despite being in the age group for which these vaccines were protective, exhibited poor immune responses even to the vigorous stimulus of natural infection. These findings raise the possibility that immune hyporesponsiveness may limit the potential efficacy attainable by cholera vaccines in populations with endemic cholera.

Administration, Oral↗
PubMed1995

Outcome of referrals to a district immunisation advisory clinic.

We have studied referrals to and outcomes of consultation at a district immunisation advisory clinic, aiming to examine and confirm the rarity of true contraindications, the safety of immunising children with possible contraindications, and the influence on parents of counselling by well informed professionals. We examined medical records and postal questionnaires to parents, representing 30 months' work. Three hundred and fifty-eight children were referred to the clinic, 248 of whom were seen and 110 (31%) did not attend. Fourteen children who attended (6%) had a true contraindication to the vaccine(s) in question and 202 of the remaining 234 (86%) proceeded to vaccination with no adverse effect. Forty of the 110 (36%) who were referred but did not attend were vaccinated, and no adverse effects were reported, but the immunisation rate of this group was significantly lower than that seen in the clinic (chi 2 test, p < 0.001). True contraindications to childhood immunisation were rare, and children with difficult problems were safely vaccinated. The immunisation advisory clinic is effective in counselling parents who are uncertain about childhood immunisation.

Adolescent↗
PubMed1995

The cellular function of MASH1 in autonomic neurogenesis.

Using primary cultures and immortalized multipotential stem cell lines derived from wild-type and Mash1 mutant neural crest cells, we have analyzed the cellular function of MASH1 in autonomic neurogenesis. We present evidence for the existence of a precursor expressing MASH1 and neuronal markers such as neurofilament, neuron-specific tubulin, and tetanus toxin receptor. This cell has a nonneuronal morphology. Differentiation of this precursor to neurons that express markers such as SCG10, peripherin, and neuron-specific enolase is dependent upon MASH1 function. These data imply that the differentiation of autonomic neurons from uncommitted neural crest cells occurs in several sequential steps. Moreover, they suggest that MASH1 does not commit multipotent cells to a neural fate, like its Drosophila achaete-scute counterparts, but rather promotes the differentiation of a committed neuronal precursor.

Animals↗
PubMed1995

Effect of transfusion in acute chest syndrome of sickle cell disease.

OBJECTIVE: To study the effects of transfusion on the clinical course and oxygenation indexes of children with sickle cell disease and acute chest syndrome. METHODS: During a 2-year period, 36 children with sickle cell disease admitted with a total of 40 episodes of acute chest syndrome were examined. Patients were given a clinical severity score indicative of the degree of respiratory distress. Arterial blood gas values were determined 4 to 24 hours before and 12 to 24 hours after transfusion, and indexes of oxygenation were calculated; six patients who were not given transfusions also had blood gases measured on admission and approximately 24 hours later for comparison. RESULTS: Blood transfusion was administered during 27 episodes (67.5%); 20 children received a simple packed cell transfusion, four had a partial packed cell exchange transfusion, and three had a simple transfusion followed by whole blood exchange transfusion because of worsening clinical symptoms. Although there was no significant change in oxygenation indexes for the six patients not treated with transfusion, there was significant improvement in all indexes after transfusion. The transfused group had more severe disease on admission, but there was no significant difference in duration of fever, tachypnea, retractions, or hospital stay between the transfusion and the nontransfusion groups. CONCLUSION: Blood transfusion, even simple transfusion of packed erythrocytes, significantly improves oxygenation in children with acute chest syndrome and is a valuable adjunct to therapy.

Acute Disease↗
PubMed1995

Impact of infection by Helicobacter pylori on the risk and severity of endemic cholera.

To evaluate the relationship between Helicobacter pylori infection and the subsequent risk and severity of endemic Vibrio cholerae O1 diarrhea among rural Bangladeshis, 285 children and adults with cholera (cases) and 881 contemporaneously selected community controls were studied. Cases and controls were contrasted for H. pylori infection, as manifested by serum IgG anti-H. pylori antibodies. Although the overall risk of cholera was not significantly increased among H. pylori-infected subjects, the risk of cholera of life-threatening severity was significantly elevated (relative risk [RR] = 1.61; 95% confidence interval [CI] = 1.07-2.42). A significant increase in the risk of severe cholera was seen in subjects who lacked natural serum vibriocidal antibodies (RR = 2.88; 95% CI = 1.28-6.48) but not in those with such antibodies. Thus, H. pylori infection was associated with a significant increase in the risk of life-threatening cholera, but only among persons lacking natural vibriocidal immunity.

Adolescent↗
PubMed1995

Liposomes as carriers of peptide antigens: induction of antibodies and cytotoxic T lymphocytes to conjugated and unconjugated peptides.

In the quest for effective immunization against complex diseases such as cancer, parasitic diseases, AIDS, and other viral infections, numerous peptides and recombinant proteins have been synthesized, examined for the ability to induce antibodies and CTLs, and tested for binding capability and therapeutic or prophylactic efficacy against the original target cell or organism. A liposome formulation, consisting of alum-adsorbed liposomes containing both a potent adjuvant, lipid A, and encapsulated or surface bound antigen, has had a record of safety and strong effectiveness for induction of antibodies in human vaccine trials. These same liposomes can also serve as effective vehicles for delivering conjugated or unconjugated peptides and proteins to antigen presenting cells for presentation via MHC class I and class II pathways for induction of CTLs and antibodies in experimental animal models. Liposomal lipid A appears to be extremely important, and is often a requirement, as an adjuvant for induction of CTLs against liposomal peptide antigens. Computer-generated molecular modelling analysis of small unconjugated or lipid-conjugated peptides strongly suggests that the expression of peptide antigen on the surface of the liposomes can be an important factor both in the induction of antibodies and in determining antibody specificities to small peptides. However, antigenic surface expression of liposomal peptide is not required for induction of CTLs. The data suggest that small synthetic peptides, synthesized with or without a lipid tail, or chemically conjugated to the surface of liposomes, might serve as effective antigenic epitopes, in combination with liposomal lipid A for induction of antibodies and CTLs.

Amino Acid Sequence↗
PubMed1995

Intracellular processing of liposome-encapsulated antigens by macrophages depends upon the antigen.

Two proteins, a recombinant malaria protein (R32NS1) and conalbumin, were encapsulated in separate liposomes. The mechanisms of presentation of unencapsulated and liposome-encapsulated R32NS1 and conalbumin to antigen-specific T-cell clones were investigated in in vitro antigen presentation assays using murine bone marrow-derived macrophages (BMs) as antigen-presenting cells. A much lower concentration of liposomal antigen than of unencapsulated antigen was required for T-cell proliferation. Liposome-encapsulated conalbumin required intracellular processing by BMs for antigen-specific T-cell proliferation, as determined by inhibition with chloroquine, NH4Cl, leupeptin, brefeldin A, monensin, antimycin A, NaF, and cycloheximide and by treatment of BMs with glutaraldehyde. Liposome-encapsulated conalbumin therefore follows the classical intracellular antigen processing pathway described for protein antigens. Similarly, unencapsulated conalbumin also required intracellular processing for presentation to antigen-specific T cells. In contrast, both unencapsulated R32NS1 and liposome-encapsulated R32NS1 were presented to T cells by BMs without undergoing internalization and intracellular processing. These results suggest that the antigen itself is the major element that determines whether a requirement exists for intracellular processing of liposomal antigens by macrophages.

Amino Acid Sequence↗
PubMed1994

The immunisation coordinator: improving uptake of childhood immunisation.

Attention to local uptake of childhood immunisation is fundamental to the achievement of national targets. The aim of this investigation was to discover whether local interventions by the immunisation coordinator in a district health authority improved uptake. The immunisation coordinator and a public health nurse determined the immunisation uptake in their locality. They made inquiries, and responded to general practitioners and health visitors who asked them to help encourage persistent non-attenders to consent to immunisation. All interventions intended to encourage parents to consent to immunisation (such as telephone calls, letters, and home visits), and their outcomes, were monitored. The uptake of immunisation was remeasured after one year. Ninety-three children were identified whose parents had not responded to repeated invitations for immunisation. Eleven cases were lost to follow up: the families of 10 children had moved out of the area, and one child had died. The remaining 82 children could be divided into two groups: one group, of 49 children, was due for primary vaccination (diphtheria, tetanus, pertussis, and polio, and measles, mumps, and rubella), and a second group, of 33 children, was due for the preschool (diphtheria, tetanus, and polio) booster. Fifty-eight of the 82 children were vaccinated as a result of the intervention. All but two general practices achieved the 90% target for uptake. The review showed that the locality as a whole achieved greater vaccine coverage. The biggest improvement was in the preschool booster uptake, which rose from 87% to 90%.

Age Factors↗