Community-based evaluation of the effect of breast-feeding on the risk of microbiologically confirmed or clinically presumptive shigellosis in Bangladeshi children

To assess the association between breast-feeding and the risk of microbiologically confirmed or clinically presumptive shigellosis, the authors performed a case-control analysis of Bangladeshi children younger than 3 years of age who were followed up for 1 month after exposure to Shigella in their residential neighborhoods. Two hundred sixty-nine cases with culture-confirmed shigellosis (n = 119) or clinically presumptive shigellosis (culture-negative dysentery, n = 150) were compared with 819 controls without Shigella diarrhea or other invasive diarrheal illnesses. The odds ratio relating breast-feeding to confirmed or presumptive shigellosis, adjusted for potentially confounding variables, was 0.48 (95% confidence interval = 0.32 to 0.72; P less than .001), suggesting a substantial protective effect. The protective association decreased with age but was still significant during the third year of life; appeared to be directly related to the degree of stunting; and was equivalent for confirmed and presumptive shigellosis. Notably, the protective association remained substantial against episodes due to Shigella which were resistant to at least one of the antibiotics customarily used for treatment of Shigella diarrhea (age-adjusted odds ratio = 0.40; 95% confidence interval = 0.22 to 0.74; P less than .01). These data suggest that breast-feeding confers a high level of protection against shigellosis throughout the first 3 years of life, especially among nutritionally compromised children, and thereby underscore the importance of promotion of breast-feeding as a central component of Shigella control programs in less developed settings.

Effect of family size and income on the biochemical indices of urban school children of Bangladesh

The relationship between family size and income and the biochemical indices of 242 children (aged from 5 to 12 years) from five schools in Dhaka City, Bangladesh, was investigated. Socio-economic data were collected by questionnaire and blood samples were drawn by visiting each school on a prefixed date. Mean levels of all measures, except for serum zinc, fell within the normal range. Older boys, but not girls (10-12 years of age) had statistically significantly higher haemoglobin, serum protein and serum vitamin A levels compared with those of the younger boys (5-9 years of age). The children were divided into three family size groups (small, up to 4 members; medium, 5-7 members; and large, 8 or more) to investigate the effect of family size on the biochemical data. The children from smaller families showed significantly higher levels of haemoglobin and serum vitamin A compared with the children from large families. For serum protein, copper and zinc, there was no statistically significant difference between the children of different family size groups. To analyse the effect of family income, children were divided into three income groups (low, up to taka 2000; medium, taka 2001-4500; and high, 4501 or more). The children from the low family income group had significantly lower serum protein (7.5 g/100 ml) and haemoglobin (13.4 g/100 ml) levels compared with those of the children from the high family income group (for protein, 7.7 g/100 ml and haemoglobin, 14.1 g/100 ml).(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Shigella-specific IgA in saliva of children with bacillary dysentery

To study the secretory immune response after Shigella infection, the anti-lipopolysaccharide and anti-Shiga-toxin response in saliva, obtained from children with confirmed shigellosis and healthy children, were determined by enzyme-linked immunosorbent assay and by Western blot. Children with infection showed high titers compared to healthy controls. After Shigella dysenteriae type 1 infection a significant change in titer could be observed in a large number of cases, in contrast to Shigella flexneri infection. It appeared that, in children living in endemic areas, infection with one serotype can give a rise in antibody titer to another serotype. This could be ascribed to polyclonal B cell activation since children in endemic areas routinely show relatively high titers to Shigella antigens. We conclude that the dynamics of salivary anti-Shigella LPS and anti-Shiga-toxin in children with dysentery indicate that it can be applied to studies of immune response in shigellosis for epidemiological and vaccination purposes.

Seroepidemiologic evaluation of antibodies to rotavirus as correlates of the risk of clinically significant rotavirus diarrhea in rural Bangladesh

A case-control study was conducted among children and adult women in rural Bangladesh to evaluate whether serologic immunity to rotavirus was associated with a lower risk of rotavirus diarrhea of sufficient severity to cause patients to seek medical care. Acute-phase sera from 219 cases of rotavirus diarrhea, detected among patients treated in three diarrheal treatment centers, were compared with sera from 477 contemporaneously selected community controls. Overall, serum IgG antirotavirus antibody titers were nearly one-fourth as high in cases as in controls (107 vs. 417 units/ml; P less than .001). Among persons aged greater than or equal to 8 months, in whom titers of maternal antirotavirus antibodies should have been negligible, even the lowest range of detectable titers (100-200 units/ml) was associated with a substantial (75%, P less than .05) reduction of the risk of rotavirus diarrhea. We conclude that titers of serum IgG antirotavirus antibodies induced by earlier infection were inversely related to the risk of clinically significant rotavirus diarrhea.

Culture adaptation and characterization of group A rotaviruses causing diarrheal illnesses in Bangladesh from 1985 to 1986

Group A rotaviruses collected between 1985 and 1986 during comprehensive surveillance of treated diarrheal episodes occurring in a rural Bangladesh population were culture adapted and characterized by electropherotype, serotype, and subgroup. Of 454 episodes of rotavirus-associated diarrhea, rotaviruses were culture adapted from 381 (84%), and 335 contained 11 electrophoretically identical segments in unpassaged and cultured preparations. These 335 comprised 69 different electropherotypes with between 1 (32 isolates) and 79 representatives. The persistence of specific rotavirus strains within the study population, as defined by the detection of viruses with particular electropherotypes, was generally limited to a period of only a few months. All 335 isolates were serotyped by neutralization with hyperimmune antisera to prototype rotavirus strains representative of serotypes 1 to 4, i.e., Wa, DS-1, P, and ST-3. It was found that 80, 48, 119, and 88 isolates belonged to serotypes 1 to 4, respectively. The concentrations of hyperimmune antisera required to neutralize these isolates, however, were at least threefold greater than those needed to neutralize the homologous strains. Therefore, the isolates appeared to have altered neutralization epitopes from their prototype strains. Furthermore, the serotype 4 isolates were consistently shown to be much more closely related to the serotype 4B VA70 strain than the serotype 4A ST-3 strain. All but two isolates identified as serotypes 1, 3, or 4 had long electropherotypes and were subgroup II, and all but one serotype 2 isolate were subgroup I and had short electropherotypes. The three disparate strains appeared to be genetic reassortants. Evidence is presented that dual infections required for reassortant formation were not uncommon. Thus, formation of multiple reassortants may have been a cause for the observed rapid shift in viral strains within the study population.

Leading causes of infant deaths in the District of Columbia

Causes of infant deaths were analyzed from the linked vital records of 1988 for the District of Columbia. According to a new cause-of-death classification, 57% of the deaths were attributed to "prematurity and related conditions," as compared with only 31% due to "disorders relating to short gestation and unspecified low birthweight" and respiratory distress syndrome (RDS) in the three-digit ICD-9 classification. Two thirds of infant deaths were "preventable." However, 92% of these occurred to infants weighing less than 1500 g. Not only was a greater proportion of black deaths (71%) preventable as compared to nonblacks (40%), but also 15% of the preventable deaths among blacks were due to causes unrelated to prematurity. The Infant Mortality Rate (IMR) in the District of Columbia would be reduced from 23.2 to 7.7 if all preventable deaths were prevented, to 20.9 if only the preventable deaths not related to prematurity were prevented, and to 15.2 if the percentage of "preventable" deaths among blacks was brought down to the level of nonblacks. Mortality from RDS was substantially higher in the District of Columbia compared with blacks nationally and appeared to offer the best opportunity for reduction. However, detailed examination of circumstances surrounding each infant death would be necessary to inform the strategies for the reduction in IMR.

Antibody responses after immunization with killed oral cholera vaccines during the 1985 vaccine field trial in Bangladesh

Sera collected during the 1985 oral cholera vaccine trial in Matlab, Bangladesh, which demonstrated efficacy of a whole cell combined with cholera B subunit vaccine (WC/BS) and a whole cell only vaccine (WC), were analyzed for antitoxin and vibriocidal antibodies. Before vaccines were given, antitoxin titers were highest in children, especially those with O blood group, whereas vibriocidal titers rose throughout life. Two weeks after three doses of vaccine, geometric mean antitoxin titers were 2.5-4.5 times higher in vaccinees who received the WC/BS vaccine; the vibriocidal titers were 1.3-2.1 times higher in vaccinees who received either vaccine. The titer elevations were relatively brief and were barely detectable 7 months after the third dose even though significant levels of protection persisted greater than or equal to 3 years. Thus, the oral vaccines induced a serum response in this large field trial that was similar to that seen in earlier pilot studies, but the duration of the serum responses was much shorter than the duration of the protection.

Local preparation, standardization and quality control of technetium labelled macroaggregated albumin for lung perfusion studies

Lung perfusion study is an important investigation in various pulmonary diseases. The radiopharmaceutical commonly used now-a- days is imported macroaggregated human albumin (in kit form), which is labelled with technetium (Tc99m-MAA). Due to its high cost the technique could not be fully exploited. We have tried to locally prepare freeze dried MAA particles. Various parameters like concentration of protein, pH value, temperature, quality and quantity of reducing agents were studied to find out the optimum conditions for radiolabelling and the desired particle size. More than 98% of the added radioactivity was found tagged to the MAA particles in the final preparation (confirmed by paper chromatography). Labelled agent was found to be radiochemically stable for up to 6 hours. Initial animal and later human studies showed an ideal spectrum of particle size.

ABO blood groups and the risk of diarrhea due to enterotoxigenic Escherichia coli

To determine whether blood group O persons are at higher risk for enterotoxigenic Escherichia coli (ETEC) diarrhea, a case-control study was done for 17 months among rural Bangladeshis who were under systematic surveillance for diarrhea. Cases were children less than 3 years old who presented between 1 January 1985 and 1 June 1986 for care of heat labile (LT) or heat stabile toxin-producing ETEC diarrhea. Controls were of similar ages and were randomly selected from three community-based serosurveys between July 1985 and May 1986. No association between blood group O and ETEC diarrhea was found for the 510 cases and 641 controls, nor was an association evident for cases of each toxin phenotype. Further refinement of the case definition to include only patients with LT-ETEC diarrhea, without enteric copathogens, also failed to reveal a substantial association with blood group O. These data suggest that a strong association with ABO groups, analogous to that for cholera, does not exist for ETEC diarrhea.

The effect of caffeine on postprandial blood pressure in the frail elderly

In a double-blind, random-order, cross-over study the effects of placebo and 100 mg of caffeine on postprandial sitting and erect blood pressure and heart rate were studied in 20 frail elderly subjects (mean age 84, range 75-93 years) after a standardized 400 K-calorie glucose drink. Maximal postprandial reduction in sitting systolic blood pressure occurred, at 60 minutes post-placebo, of - 11 mmHg (95% confidence interval -5 to -17 mmHg, P less than 0.01), and was attenuated by caffeine (P less than 0.05) with changes in systolic blood pressure, at 60 minutes post-drink, of 1 mmHg (95% CI -6 to 7 mmHg, not significant). Four subjects developed symptomatic postprandial hypotension after placebo which was prevented by caffeine. There were no significant changes in erect systolic blood pressure, postural systolic blood pressure change, sitting and erect, diastolic blood pressure and heart rate between treatment phases. Caffeine attenuates the postprandial fall in sitting blood pressure in frail elderly subjects and in particular prevented symptomatic blood pressure reductions in subjects with postprandial hypotension.

Field trial of oral cholera vaccines in Bangladesh: serum vibriocidal and antitoxic antibodies as markers of the risk of cholera

The relationship of serum vibriocidal (VC) and IgG anti-cholera toxin (CT) antibodies to the risk of cholera was evaluated during the first year of follow-up of recipients of three oral doses of B subunit (BS)-whole-cell vaccine, whole-cell vaccine, or Escherichia coli K12 strain placebo in Bangladesh. Acute sera from 121 cholera patients were compared with sera from 2592 contemporaneous community controls. Each doubling of VC titer was associated, on average, with a 22%-47% reduction of cholera risk in the three groups. In contrast, in the two groups that did not receive BS, anti-CT titers were directly associated with cholera and thus served as markers of higher cholera risk. Each vaccine conferred approximately 65% protective efficacy against cholera, but antibody titers did not correlate with vaccine efficacy, indicating that serum VC and anti-CT antibodies are poor markers of the longitudinal pattern of vaccine efficacy.

Effect of socio-demographic conditions on growth of urban school children of Bangladesh

The relationship between socio-demographic variables and growth of 242 school children from five schools in Dhaka city, Bangladesh, was investigated. The socio-demographic data were collected by questionnaire and the anthropometric data were collected by visits to each school on a prefixed date. Children from the high-family-income group showed significantly higher body weight, height, MUAC, SFT, wt/age, and ht/age compared with children from the low-family-income group. When the effect of age, sex, father's occupation and family size were adjusted for by means of multiple analysis of variance, the family income still showed a significant contribution to the variation in the anthropometric indices of these children. These findings suggest that family income makes a significant contribution as a determinant of growth of urban school children in Bangladesh.

Effect of vitamin A deficiency on the immune response to epizootic diarrhoea of infant mice (EDIM) rotavirus infection in mice

The effect of vitamin A deficiency on the immune response to epizootic diarrhoea of infant mice (EDIM) rotavirus was studied in mice. The virus was given by oral dosing or by intraperitoneal injection. For oral challenge, weanling mice were fed on either a control or vitamin A-deficient diet ad lib. or pair-fed the control diet to the intake of the vitamin A-deficient group. A fourth group was fed on the vitamin A-deficient diet ad lib. for 10 weeks and then refed the control diet for 2 weeks. On day 77, mice were each given 30 microliters EDIM rotavirus orally and the animals were killed and examined 1 week later. The delayed-type hypersensitivity (DTH) response to picryl chloride was measured as an index of cell-mediated immunity. For intraperitoneal challenge, weanling mice were fed on either the control diet or the vitamin A-deficient diet ad lib. or pair-fed the control diet to the intake of the vitamin A-deficient group. On day 77, mice were each injected intraperitoneally with 30 microliters EDIM rotavirus and 1 week later antibody production was measured. In both experiments the body-weight, liver and serum vitamin A levels of the vitamin A-deficient group were significantly lower than the control or pair-fed groups. Following oral dosing the serum antibody levels specific to rotavirus were statistically significantly lower in vitamin A-deficient animals than the control or pair-fed groups. Vitamin A-deficient mice also showed an impaired DTH response compared with the control and pair-fed animals. Animals refed vitamin A for a short period showed a partial restoration of the antibody response. Following intraperitoneal challenge no statistically significant changes were observed in the serum antibody levels between any of the dietary groups. It is concluded that vitamin A deficiency impaired antibody production when rotavirus was given orally. Vitamin A deficiency also impaired cell-mediated immunity.

Biotype as determinant of natural immunising effect of cholera

To test the hypothesis that clinical Vibrio cholerae O1 infections protect against recurrent cholera, treated cholera episodes in a rural Bangladesh population of 188,153 people who were followed between 1985 and 1988 were analysed. Of the 2214 people with initial episodes of cholera, 7 had a second episode. The incidence of cholera was 61% lower in subjects who had had an earlier episode than in those without such an episode. Whereas initial episodes of classical cholera were associated with complete protection against subsequent cholera, initial episodes of El Tor cholera were associated with negligible protection.

Effect of severe food restriction on the gut following rotavirus infection in mice

The effect of severe food restriction on the histopathology of the gut following infection with epizootic diarrhoea of infant mice (EDIM) rotavirus was studied in mice. Over a period of 12 weeks, weanling mice were fed either 70 or 50% of the diet eaten by a control group on the previous day. After 11 weeks of feeding, animals were given 30 microliters/mouse of EDIM rotavirus orally and the histopathology of the gut and lymphoid organs examined. The histology of the spleen and thymus of different dietary groups appeared normal and no changes were observed due to the rotavirus challenge. Both the control and 70% food group had normal villi in the small intestine. In contrast there was severe atrophy of the villi in the animals whose intake was reduced by 50%. No additional damage to the villi was seen in association with the rotavirus infection. It is concluded that a prolonged, balanced reduction in food intake can itself cause villous atrophy in the gut but following rotavirus infection, adult animals were able to resist further villous damage.

Field trial of oral cholera vaccines in Bangladesh: evaluation of anti-bacterial and anti-toxic breast-milk immunity in response to ingestion of the vaccines

In a field trial conducted in Bangladesh, ingestion of either B subunit-killed whole cell (BS-WC) or killed whole cell (WC) oral cholera vaccines by mothers was associated with a 47% reduction of the risk of cholera in their non-vaccinated children aged under 36 months. Because vaccine-induced breast-milk immunity seemed a possible explanation for these findings, we evaluated anti-lipopolysaccharide (LPS) and anti-cholera toxin (CT) IgA antibody responses in breast milk collected during the trial from 53 lactating women who ingested three doses of BS-WC, WC, or an Escherichia coli K12 strain (K12). Despite induction of moderate vibriocidal (1.4 to 2.0-fold) and anti-CT (4.5-fold) serum antibody responses, the vaccines did not elicit significant rises of anti-LPS or anti-CT IgA breast-milk antibodies. The failure of the vaccines to elicit significant levels of breast-milk anti-cholera antibodies suggests an alternative explanation for protection of young children by maternal vaccination, such as interruption of maternal-child transmission of Vibrio cholerae 01.

Seroepidemiologic evaluation of anti-toxic and anti-colonization factor immunity against infections by LT-producing Escherichia coli in rural Bangladesh

To evaluate serologic immunity against clinical infections by heat-labile enterotoxin-producing Escherichia coli (LT-ETEC) in rural Bangladesh, 124 children and adult women with LT-ETEC diarrhea (cases) were compared with 347 age-matched community controls. In paired acute-convalescent sera from the cases, IgG anti-CFA I and anti-CFA II antibody titers increased eight-to ninefold after infection by LT-ETEC with the homologous CFA, and IgG anti-LT antibody titers increased fourfold for all LT-ETEC infections. Anti-CFA and anti-LT titers peaked in controls aged 12-23 months, the age group with the highest incidence of ETEC infections. However, antibody titers were similar in acute sera from cases and in sera from controls. Although serum IgG anti-CFA and anti-LT antibodies rose in response to LT-ETEC infections and paralleled the age-specific incidence of ETEC in the community, these antibodies were not associated with a lower risk of LT-ETEC diarrhea.

Site predilection of oral cancer and its correlation with chewing and smoking habit--a study of 103 cases

Like many other countries in South East Asia, oral cancer is one of the common cancers in Bangladesh. This report is based on one hundred and three cases of biopsy proven squamous Cell Carcinoma of the oral cavity collected from different Medical Institutions in Dhaka. The aim was to find out relationship between chewing and smoking habit and anatomic site of the cancer in oral cavity. It has been observed that oral cancers are common in older age groups and the proportion is higher in males as compared to females. Buccal mucosa has been the commonest site, the next being the anterior two-thirds of tongue. A high percentage of patients revealed tobacco habits in the form of chewing with betel quid and or smoking. Both smoking and chewing were found to be important in males in all the anatomical sites and chewing of tobacco with betel quid appeared to play a dominant role in the females. Duration of betelquid chewing and smoking seem important. Site of origin of the majority of the lesions corresponded with site maximally exposed to betelquid with or without incorporation of tobacco. In majority of the cases the cancer was well differentiated.

Excessive faecal losses of vitamin A (retinol) in cystic fibrosis

Vitamin A (retinol) deficiency is a recognised complication of cystic fibrosis and is presumed to be a consequence of an impairment in the digestion and absorption of dietary fats. The dietary intake of fat and retinol was assessed from a seven day weighed food intake in 11 subjects with cystic fibrosis and 12 matched controls. Faecal excretion of retinol and fat were measured from three day stool collections. There was little difference between the two groups in the intake of fat or retinol equivalents. When studied the subjects with cystic fibrosis were clinically stable and the apparent absorption of fat was not significantly different to that in the controls. There was a significant increase in the faecal losses of retinol in cystic fibrosis, which was unrelated to the degree of fat in the stool. In cystic fibrosis the median retinol recovered in the stool was 40% of the intake, compared with 1.8% in the controls. It is concluded that there is a specific defect in the handling of retinol by the gastrointestinal tract in cystic fibrosis, which may be unrelated to the digestion and absorption of dietary fat.

The interaction of vitamin A deficiency and rotavirus infection in the mouse

Weanling mice were fed on a control diet ad lib., a vitamin A-deficient diet ad lib. or pair-fed to the intake of the vitamin A-deficient group. Vitamin A deficiency was induced by 63-70 d of age. On day 77 mice were given 30 microliters rotavirus/mouse orally and examined histologically 1 week later. There were no changes in relative liver weight in any of the groups, but following infection animals deficient in vitamin A showed a significant increase in spleen weight compared with the other groups. The relative weight of the thymus was reduced by vitamin A deficiency, in both non-infected and infected animals. The histology of the spleen, thymus and small intestine was similar in all three dietary groups before infection. The number of goblet cells per duodenal villus in vitamin A-deficient animals was significantly lower than that of control and pair-fed animals. In the small intestine of vitamin A-deficient animals, rotavirus infection caused dramatic changes to the mucosa, with almost complete destruction of the tips of the villi, but control and pair-fed animals had normal villi. It is concluded that although rotavirus infection and vitamin A-deficiency cause few changes alone, in their action together there is significant destruction of the mucosal barrier of the small intestine.

Field trial of oral cholera vaccines in Bangladesh: results from three-year follow-up

The protective efficacy (PE) of B subunit killed whole-cell (BS-WC) and killed whole-cell-only (WC) oral cholera vaccines was assessed in a randomised double-blind field trial among children aged 2-15 years and women over 15 years in rural Bangladesh. Among the 62 285 subjects who received three doses of BS-WC, WC, or Escherichia coli K12 strain placebo, cumulative PE at 3 years of follow-up was 50% for BS-WC and 52% for WC. PE was similar against severe and non-severe cholera, but was significantly lower in children who were vaccinated at 2-5 years (26% for BS-WC; 23% for WC) than in older persons (63% for BS-WC; 68% for WC). Among persons vaccinated at 2-5 years, protection at 4-6 months of follow-up was similar to that for older persons, but rapidly waned thereafter and was not evident during the third year of follow-up. In contrast, persons vaccinated at older ages were protected even in the third year of follow-up (PE 40% for BS-WC; 62% for WC). PE was substantially higher against classical cholera (58% for BS-WC; 60% for WC) than against El Tor cholera (39% and 40%).

Unmarried mothers as a high-risk group for adverse pregnancy outcomes

A total of 36,608 singleton births occurring to Black mothers in the District of Columbia in 1980-84 were examined. Infants of unmarried mothers had a 34 percent higher incidence of low birthweight and a 35 percent higher neonatal mortality rate than infants born to married mothers. To delineate the independent effect of marital status, a logit model was fit to 23,461 births occurring to mothers over 19 years of age. Despite controlling on maternal age, educational attainment and adequacy of prenatal care, the odds ratio for low birthweight was 1.18 for the infants of unmarried mothers. Supplemental analyses showed that if mothers were drug addicted or had their first delivery before age 18, the marital status differentials in the birthweights of their infants were no longer significant. These results indicate the importance of unmarried status as a demographic risk factor, and the need for discerning specific high-risk behaviors associated with life styles of unmarried mothers.

Effect of undernutrition on the immune response to rotavirus infection in mice

The effect of moderate and severe undernutrition on the immune response to EDIM rotavirus was studied in mice. A moderate state of undernutrition was produced by feeding weanling mice either 15 or 30% less diet than the control group had eaten on the previous day, for 7 weeks. After 6 weeks, mice were given 30 microliters/mouse of EDIM rotavirus orally and the antibody production was measured 1 week later. The delayed-type hypersensitivity (DTH) response to picryl chloride (PC) was measured as an index of cell-mediated immunity. For severe undernutrition, weanling mice were fed either 30 or 50% less diet than the control group had eaten on the previous day, for 12 weeks. After 11 weeks of feeding, animals were given 30 microliters/mouse of EDIM rotavirus either orally or intramuscularly and the antibody production was measured 1 week later. In moderate undernutrition, the serum antibody levels specific to rotavirus and the DTH response to PC were normal in all dietary groups compared with the control group. In severe undernutrition, the antibody levels following oral challenge of rotavirus were similar in all dietary groups. There was a significant impairment of serum antibody levels following intramuscular challenge in the group fed 50% less than the control group. It is concluded (1) that a balanced reduction in food intake does not impair the immune response, unless severe restriction is maintained for a long period of time, and (2) that the antibody response varies with the route of immunization.

Lysosomal mutations increase susceptibility to anaesthetics

The anaesthetic responses of homozygous mutant mice were compared with those of their normal heterozygous littermates. The two recessive mutations studied were beige (bg) and reduced pigmentation (rp). Homozygosity for either significantly increased the sleeping time of both sexes after treatment with pentobarbital, tribromoethanol or the steroid anaesthetic alphaxalone.

Urban-suburban differences in the incidence of low birthweight in a metropolitan black population

To study the urban-suburban differences in low birthweight among black Americans, 54,870 single births occurring to black mothers in the hospitals of Washington, DC, from 1980 to 1984 were analyzed. The observed data showed a 25% higher incidence of low birthweight (under 2501 gm) among infants born to urban mothers compared with those born to suburban mothers. Bivariate analysis showed that a greater proportion of urban mothers, compared with the proportion of suburban mothers, was teenage (23.6% vs 10.3%) and unmarried (67.6% vs 32.9%), had less than a high school education (31.7% vs 9.1%), and received inadequate prenatal care (34.3% vs 20.3%). The logit model fit to these data showed that by controlling for the above risk factors, the residential differences in the incidence of low birth rate were almost eliminated. Exploration of the medical risks associated with adverse pregnancy outcomes showed that the urban mothers had substantially higher rates for premature rupture of membrane, concurrent hypertension, pre-existing diabetes, hyperemesis, anemia, and narcotic addiction. The findings of the article underline the usefulness of studying intra-black differences rather than relying solely on race comparative research.

Exclusion of clinically atypical or microbiologically mixed diarrhoeal episodes from outcome events in a field trial of oral cholera vaccines

We investigated whether alternative clinical and microbiological criteria for outcome events affected estimates of vaccine efficacy in a randomized, double-blind field trial of B subunit-killed whole cell (BS-WC) and killed whole cell-only (WC) oral cholera vaccines among 62,285 rural Bangladeshi participants. At one year of follow-up estimates of vaccine protective efficacy (PE = 60%, P less than 0.0001 for BS-WC; PE = 54%, P less than 0.0001 for WC) against all treated diarrhoeal episodes associated with V. cholerae 01 were similar to estimates of efficacy against only those episodes which were clinically typical and unassociated with additional enteric pathogens (PE = 62%, P less than 0.0001 for BS-WC; PE = 52%, P less than 0.0001 for WC). In contrast, estimates of vaccine cross-protection against episodes associated with each of several agents antigenically related to V. cholerae 01 (LT-ETEC, non-cholera Vibrio sp, Aeromonas sp) were substantially reduced when mixed infections with V. cholerae 01 were excluded. We conclude that restrictive criteria intended to improve the specificity of the definition of cholera did not increase the detectability of vaccine efficacy against V. cholerae 01, but that exclusion of mixed infections with V. cholerae 01 was necessary to avoid false-positive conclusions about vaccine cross-protection against other potential target pathogens.

Laser damage threshold of KTiOPO(4)

Laser damage thresholds are reported for two unpoled and one poled KTiOPO(4) crystals under similar experimental conditions. For the TEM(00) mode of a Nd:YAG laser, the fluence and power density values for the unpoled crystals (23-33 J/cm(2) and 2-3 GW/cm(2), respectively) were higher than for the poled crystal (10-17 J/cm(2) and 0.8-1.3 GW/cm(2)). Even for a poled KTP, the damage threshold is higher than potassium dihydrogen phosphate or KDP (6-9 J/cm(2)).

The removal of exogenous thiols from proteins by centrifugal column chromatography

Centrifugal column chromatography was shown to provide a rapid, efficient, and useful means of separation of various low molecular weight thiols from proteins. The single chromatographic step procedure employed standard 5 ml plastic syringes containing Sephadex G-25 as the bed matrix and required less than 5 min to produce average dilutions of 5000-, 980-, and 25-fold, respectively, from 5 to 200 mM initial concentrations of 2-mercaptoethanol, dithiothreitol, and reduced glutathione in the sample as measured by titration with 5,5'-dithiobis-(2-nitrobenzoic acid). Dihydrofolate reductase solutions of 0.07-0.08 mM were separated from 50 mM 2-mercaptoethanol, dithiothreitol, or reduced glutathione with a minimum 16,500-fold dilution of the thiol after centrifugal chromatography on two consecutive columns. Thymidylate synthase solutions of 0.06 mM were effectively separated from 50 mM 2-mercaptoethanol or dithiothreitol with a minimum average 5900-fold dilution of the thiol after consecutive column chromatography. There was no change in either the physical or chemical properties of the enzyme throughout the course of the experiments as determined by activity, active site sulfhydryl group titration, and binding assays. Recoveries of protein obtained in the load fraction were usually in excess of 70% of the protein loaded with virtually no dilution from the initial concentration. This method was developed in order to facilitate the study of the active site sulfhydryl groups in enzymes.

Field trial of oral cholera vaccines in Bangladesh: results of one year of follow-up

We assessed the protective efficacy (PE) of three doses of B subunit-killed whole cell (BS-WC) and killed whole cell-only (WC) oral cholera vaccines in a randomized, double-blind trial among 62,285 children and women residing in rural Bangladesh. After one complete year of surveillance, 110 cases of cholera were detected in the placebo group, 52 in the WC group (PE, 53%; P less than .0001), and 41 in the BS-WC group (PE, 62%; P less than .0001). Protection was greater for BS-WC recipients than for WC recipients only during the initial eight months of observation. Both vaccines conferred equivalent protection against cholera associated with life-threatening dehydration and against less severe cholera. High-grade, sustained protection was observed in persons vaccinated when older than five years; in younger persons protection was transient. We conclude that BS-WC and WC vaccines confer significant protection against cholera, particularly in persons vaccinated when older than five years.

Impact of B subunit killed whole-cell and killed whole-cell-only oral vaccines against cholera upon treated diarrhoeal illness and mortality in an area endemic for cholera

The impact of B subunit killed whole-cell (BS-WC) and killed whole-cell-only (WC) oral cholera vaccines was assessed in a randomised double-blind trial in rural Bangladesh. 62,285 children aged 2-15 years and women aged over 15 ingested three doses of one of the vaccines or placebo. During the first year of follow-up there was a 26% reduction of all visits for treatment of diarrhoea in the BS-WC group and a 22% reduction in the WC group. The reduction of all admissions for fatal or severely dehydrating diarrhoea was 48% in the BS-WC group and 33% in the WC group. Overall mortality rates were 26% lower in the BS-WC group and 23% lower in the WC group during the first year, and reductions of mortality were observed only in women vaccinated at ages over 15 years. However, no differences in cumulative mortality were evident at the end of the second year of surveillance.

Deep venous thrombophlebitis: detection with 4-hour versus 24-hour platelet scintigraphy

Thirty-one nonheparinized patients with suspected deep venous thrombophlebitis (DVT) underwent contrast venography and indium-111 platelet scintigraphy (In-111 PS). Venography permitted identification of acute DVT in 12 of 31 cases (39%). One additional patient was considered to have acute DVT despite nonconclusive venography results. In-111 PS results were positive at 4 hours in nine of 13 cases (69%) and at 24 hours in 12 of 13 cases (92%). Two of four patients with false-negative 4-hour In-111 PS studies had received warfarin. Thus, the sensitivity of 4-hour In-111 PS in patients not receiving anticoagulants was 82%. Venography results were negative for acute DVT in 18 cases, and 4-hour In-111 PS studies were negative or equivocal in each. In-111 PS is an alternative to contrast venography for detecting acute DVT. If 4-hour In-111 PS results are positive, anticoagulation can be initiated. Delayed images are necessary if the 4-hour images are negative or equivocal.

Hypolipidemic activity of trimethylamine-carbomethoxyborane and related derivatives in rodents

A number of substituted amine-carboxyborane esters were examined for their hypolipidemic activity in rodents. Trimethylamine-carbomethoxyborane, Me3NBH2C(O)OMe, was observed to be the most effective hypolipidemic agent in the rodent at the low dose of 8 mg/kg/d. This agent effectively increased the high density lipoprotein (HDL) cholesterol content and lowered the low density lipoprotein (LDL) cholesterol and triglyceride contents of rat lipoproteins. Furthermore, the agent accelerated cholesterol excretion from the body of the rat and reduced the activity of the rate-limiting enzyme involved in the de novo synthesis of lipids in the liver. The agent has a safe therapeutic index, and appeared to have more promise as a therapeutic agent than other borane esters.

B subunit-whole cell and whole cell-only oral vaccines against cholera: studies on reactogenicity and immunogenicity

We conducted a randomized trial among persons in rural Bangladesh to evaluate the side effects and immunogenicity of orally administered B subunit-killed whole cell (BS-WC) and killed whole cell-only (WC) cholera vaccines and a killed Escherichia coli strain K12 placebo proposed for field testing. Three doses of BS-WC, WC, E. coli, or a control agent were given with antacid to 1,257 women (aged greater than 15 years) and children (aged to to 15 years). The four groups exhibited no statistically significant differences in occurrence of symptoms after each dose, and rises in titers of vibriocidal (VC) antibodies to Inaba and Ogawa were twofold higher for vaccinees than for controls (P less than .001). Half of the persons with fourfold or greater VC responses to WC responded after the first dose; many additional patients, particularly young children, responded after subsequent doses. In contrast, 89% of persons who responded to BS-WC with twofold or greater rises in titer of IgG antibodies to cholera toxin did so after the first dose. After the third dose, vaccinees exhibited a fivefold higher rise in titer than did controls (P less than .001); a dose-to-dose booster effect was most evident in young children.

Evidence for the existence of covalent nucleotide-thymidylate synthase complexes, identification of site of attachment, and enhancement by folates

The formation of covalent binary complexes of thymidylate synthase and its nucleotide substrate dUMP, product dTMP, and inhibitor, 5-fluorodeoxyuridylate (FdUMP) was investigated using the trichloroacetic acid precipitation method. It was observed that, in addition to FdUMP, both dUMP and dTMP were capable of covalent interactions with the enzyme in the absence of added folates. The presence of folate, dihydrofolate, or tetrahydrofolate (H4folate) was found to produce substantial enhancements in the covalent binding of both FdUMP and dUMP to the enzyme with H4folate being the most effective agent. Further, covalent binary complexes of the enzyme with the three radiolabeled nucleotides were isolated by trichloroacetic acid precipitation and subjected to CNBr cleavage. The active-site CNBr peptide was isolated by reverse phase high performance liquid chromatography, and the first five N-terminal amino acid residues were sequenced by the dansyl-Edman procedure. Each active site peptide obtained from the covalent binary complexes as well as that from the covalent inhibitory ternary complex formed from enzyme, FdUMP, and 5,10-methylene-H4folate exhibited an identical sequence of Ala-Leu-Pro-Pro-(X)-, and the 5th amino acid was found to be associated with radiolabeled nucleotide ligand. Dansyl-Edman sequence analysis of the active site CNBr peptide, derived from enzyme which had been treated with iodoacetic acid, gave a sequence of Ala-Leu-Pro-Pro-CmCys (where CmCys is carboxymethylcysteine), thus confirming the fact that the fifth residue from the N terminus is Cys-198. In all the cases, the active site Cys-198 residue was found to be covalently linked to the nucleotides. These results provide unequivocal proof that the covalent binary complexes of enzyme with dUMP and dTMP predicted in the catalytic reaction mechanism actually exist.

Trapping and partial characterization of an adduct postulated to be the covalent catalytic ternary complex of thymidylate synthase

The proposed mechanism of action of thymidylate synthase envisages the formation of a covalent ternary complex of the enzyme with the substrate dUMP and the cofactor 5,10-methylenetetrahydrofolate (CH2H4folate). The proposed structure of this adduct has been based by analogy on that of the covalent inhibitory ternary complex thymidylate synthase-FdUMP-CH2H4folate. Our recent success in using the protein precipitant trichloroacetic acid to trap the latter complex and covalent binary complexes of the enzyme with FdUMP, dUMP, and dTMP led to the use of this technique in attempts to trap the transient putative covalent catalytic ternary complex. Experiments performed with [2-14C]dUMP and [3',5',7,9-3H]CH2H4folate show that both the substrate and the cofactor remained bound to the protein after precipitation with trichloroacetic acid. The trapped putative covalent catalytic complex was subjected to CNBr fragmentation, and the resulting peptides were fractionated by reverse-phase high-pressure liquid chromatography. The isolated active site peptide was shown to retain the two ligands and was further characterized by a limited sequence analysis using the dansyl Edman procedure. The inhibitory ternary complex, which was formed with [14C]FdUMP and [3H]CH2H4folate, served as a control. The active site peptide isolated from the CNBr-treated inhibitory ternary complex was also subjected to sequence analysis. The two peptides exhibited identical sequences for the first four residues from the N-terminus, Ala-Leu-Pro-Pro, and the fifth amino acid residue was found to be associated with the labeled nucleotides and the cofactor.(ABSTRACT TRUNCATED AT 250 WORDS)

Lysosomal mutations inhibit lipofuscinosis of the spleen in C57BL mice

Beige, bg, and reduced pigmentation, rp, are recessive mutations affecting lysosomal function. Homozygosity for beige prevented lipofuscinosis of the spleen in C57BL mice and its incidence was greatly reduced by homozygosity for rp. Dilute (d) homozygotes, with normal lysosomes, were susceptible to lipofuscinosis even though their melanosomes were more severely affected than those of beige mice.

Some effects of nifedipine in guinea-pig isolated trachealis

In trachealis depolarized by a K+-rich medium, nifedipine (0.001-1 mumol 1(-1) caused concentration-dependent antagonism of CaCl2-induced increase in tension, moving the CaCl2 log concentration-effect curve to the right and depressing the maximal response. In trachealis in normal Krebs solution, similar concentrations of nifedipine had marked antispasmogenic activity against the responses to potassium chloride (KCl) and tetraethylammonium (TEA). However, nifedipine had little, if any, antispasmogenic activity against the responses to acetylcholine or histamine. Nifedipine 1 mumol 1(-1) was tested for spasmolytic activity in tissues generating tension in response to the EC50 of acetylcholine, KCl or CaCl2. In producing spasmolysis nifedipine was most effective against CaCl2 and least effective against acetylcholine. Nifedipine (0.01-1 mumol-1) had little or no effect on the tone of trachealis in normal Krebs solution. Intracellular electrophysiological recording showed that nifedipine 1 mumol 1(-1) could abolish spontaneous slow wave activity. This was associated with very minor depolarization and little or no loss of mechanical tone. In tissues treated with TEA (8 mmol 1(-1) nifedipine abolished spike and slow wave discharge and reduced mechanical activity to the pre-TEA level. It is concluded that nifedipine prevents KCl- or TEA-induced spasm by inhibition of Ca2+ influx. Spasm evoked by acetylcholine or histamine and the maintenance of spontaneous tone depend largely on mechanisms for increasing the cytoplasmic concentration of free Ca2+ which are resistant to nifedipine.

A nitrocellulose-filter assay for the binary complex of 5-fluorodeoxyuridylate and Lactobacillus casei thymidylate synthetase

The interaction of 5-fluorodeoxyuridylate (FdUMP) with thymidylate synthetase to form a binary complex has been widely reported, yet previous attempts to detect this complex by nitrocellulose filtration have failed. In contrast, a nitrocellulose-filter-binding assay utilizing [6-3H]FdUMP which measures the interaction of the enzyme with the nucleotide is reported. Extensive washing of the nitrocellulose-filtered complex between FdUMP and the enzyme resulted in no loss of bound ligand. Following denaturation with trichloroacetic acid, intact complex was detected by nitrocellulose filtration. No binding was observed between 5-fluorodeoxyuridine and the enzyme or between FdUMP and the N-ethylmaleimide-modified enzyme. As measured by the nitrocellulose filtration method, at least a 600-fold excess of FdUMP to enzyme was required to achieve saturation. The stoichiometry of FdUMP bound to the enzyme detected at saturation was 0.5-0.6 for native samples. When identical samples were subjected to denaturation prior to filtration, the stoichiometry of nucleotide binding was 0.3-0.4.

Isolation of the covalent binary complex of 5-fluorodeoxyuridylate and thymidylate synthetase by trichloroacetic acid precipitation

Strong chemical evidence for the existence of a covalent binary complex between 5-fluorodeoxyuridylate and thymidylate synthetase was provided by the isolation of the complex by trichloroacetic acid precipitation. This result together with that of a control experiment with N-ethymaleimide inactivated thymidylate synthetase demonstrated that only nucleotide covalently bound to the protein survived repeated washings of the precipitate. Under the conditions used, a maximum binding stoichiometry of about 0.9 was obtained for the covalent binary complex, Kd = 1.1 X 10(-5) M. Also, a binding ratio of 1.7 was obtained for the methylenetetrahydrofolate-5-fluorodeoxyuridylate-thymidylate synthetase ternary complex.