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Biomedical subjects

J R Cruz

Publications and source records attributed to J R Cruz.

53 records · Page 3Linked to original sources
PubMed1982

Studies on human milk III. Secretory IgA quantity and antibody levels against Escherichia coli in colostrum and milk from underprivileged and privileged mothers.

We studied the milk content of secretory IgA (SIgA) and of specific IgA antibodies to E. coli in relation to volume, in 24 h samples from mothers belonging to different socio-economic groups and living under different ecologic conditions in Ethiopia, Guatemala and Sweden. There were no statistically significant differences in the daily output of milk SIgA among the population groups investigated at different times after onset of lactation. There was, however, a certain trend towards lower SIgA levels among the Guatemalan poor women, compared to the corresponding privileged one (Tables 2 and 3). Three days after delivery the underprivileged Ethiopian mothers showed significantly lower antibody levels than the privileged Ethiopian. These differences were no longer seen when the values were corrected for differences in volume (Table 5). One month after delivery, the levels of SIgA antibodies in milk from Swedish women and Guatemalan privileged women, against a pool of eight E. coli somatic antigens were comparable; these two groups of mothers had significantly higher antibody levels than the Guatemalan rural and urban ones (Table 4). The same pattern was observed after correction for differences in 24 h volumes (Table 5). At 3 months after delivery, the Guatemalan urban privileged women, again showed higher levels and daily output of antibodies against the E. coli antigens than the urban poor and rural mothers (Tables 4 and 5). The milk samples taken from a population where malnutrition is evident, i.e., mothers from Santa María Cauqué, did not show any changes in the levels of SIgA and the anti-E. coli antibodies 3, 6, 9 months after initiation of lactation. The data presented here provide evidence that chronically malnourished mothers are able to produce SIgA and transfer it to their offspring via breast milk. Furthermore, they do so in quantities that are comparable to those observed in well-nourished populations. There was a wide range of concentrations and daily output of SIgA and of specific antibodies in all groups, suggesting that some of the infants get less than others. The observed differences in levels of antibodies against E. coli may be explained by differences in exposure to E. coli strains of the eight serogroups studied here. The possibility of a deficiency in the SIgA antibody response in the undernourished mothers still remains unanswered.

Adult↗
PubMed1981

Protective effect of low-dose interferon against neonatal murine cytomegalovirus infection.

Mice were injected with 10 to 5,000 reference units of interferon intraperitoneally or subcutaneously within 24 h of birth and reinoculated intraperitoneally 24 h later with 200 plaque-forming units of murine cytomegalovirus. Mock interferon and virus diluent were the control inocula. Infection of mock interferon-treated mice resulted in significant retardation of growth, accompanied by tissue injury and a depressed blastogenic response of splenic lymphocytes. Prophylactic administration of interferon prevented growth retardation and resulted in lower tissue viral titers and diminished injurious effects of the virus. Intraperitoneal inoculation of interferon was more protective than was subcutaneous, and 10 U of interferon was often as effective as 5,000 U. Accelerated maturation and enhanced activity of lymphoid elements were observed histologically in spleens and lymph nodes of interferon-treated mice; supportive of these findings was the greater incorporation of [3H]thymidine of splenocytes from interferon-treated mice. The protective effect of interferon may, therefore, be due to stimulation or accelerated maturation of cellular immune functions.

Animals↗
PubMed1978

Effect of concurrent cytomegaloviral infection and undernutrition on the growth and immune response of mice.

Mice were inoculated with murine cytomegalovirus (MCMV) passaged in cell cultures within 24 h of birth and subsequently fed an adequate or a low-protein diet after weaning; increases in body weight, the blastogenic response of lymphocytes to T and B cell mitogens, and the capability to produce antibodies to T or B cell-dependent antigens were observed for the first 28 to 42 days of life. Neonatal infection resulted in immunosuppression and retarded physical growth through the first 4 weeks of life. After weaning (3 weeks), the effect of MCMV infection of well-nourished mice paralleled the effect of undernutrition in uninfected animals. Undernutrition and MCMV infection functioned synergistically.

Animals↗
PubMedDate not supplied

The effects of deworming on indicators of school performance in Guatemala.

Intestinal helminths are among the most common infections in school-age children. Of 246 children, aged 7-12 years, attending school in rural Guatemala, 91% carried Ascaris lumbricoides and 82% carried Trichuris trichiura. These children were randomly assigned to receive either albendazole or placebo at 0 and 12 weeks in a 'double-blind' study of the effects of deworming on indicators of school performance. Albendazole successfully rid the children of Ascaris but it was less effective against Trichuris. The children's performance in tests of reading and vocabulary were measured at 0 and 24 weeks, the Peabody picture vocabulary test was given at 24 weeks, and attendance was measured throughout the school year. Comparison of the treated and placebo groups showed no positive effect of deworming. The treated children were largely free of Ascaris for at least 6 months, but during that period we could not detect any improvement in reading, vocabulary, or attendance. The effects of being Trichuris-free were not examined because of the limited effectiveness of albendazole against this worm at the dosage used.

Albendazole↗
PubMedDate not supplied

Field evaluation of a simplified unit-dose syringe for administration of measles vaccine.

Ezeject is a plungerless syringe prefilled with lyophilized measles vaccine. Ezeject syringes were compared with standard 3-cc syringes and 10-dose measles vaccine vials in the vaccination of 884 Guatemalan infants 8-23 months of age. Vaccination was performed by experienced vaccinators and by individuals without prior vaccination experience who received 2.5-3 hours of training. The overall seroconversion rate following administration was 96%, regardless of the type of syringe used or of the experience of the vaccinator. No significant adverse events were observed in children vaccinated with the new syringes. Although incomplete emptying was noted in 87% of the Ezeject syringes used, this had no effect on the serologic response to measles vaccine. Aspiration for detection of blood before injection of the vaccine was performed significantly (P less than .001) less frequently with Ezeject than with 3-cc syringes by both experienced and inexperienced personnel. Inexperienced vaccinators administered measles vaccine significantly faster (P less than .001) with Ezeject than with 3-cc syringes, but the times were similar for experienced vaccinators. Ezeject is an acceptable alternative to standard syringes for the administration of measles vaccine. Several design modifications that would improve the handling of the device and eliminate the possibility of its reuse have been suggested.

Antibodies, Viral↗
PubMedDate not supplied

Epidemiology of acute respiratory tract infections among Guatemalan ambulatory preschool children.

Acute respiratory tract infections (ARI) were studied during a 2-year period in 521 preschool children living in a marginal area of Guatemala City. There were 3,646 episodes of ARI detected during 26,329 child-weeks at risk, for an incidence of 14 per 100 child-weeks or 7.2 episodes per child per year. The median duration of ARI episodes was 11 days. The highest incidence of ARI was observed in children 6-23 months old. Boys had more respiratory tract illnesses than did girls; the presence of a cigarette smoker in the household was associated with higher morbidity. Acute lower respiratory tract illnesses (ALRI) were more common among younger infants 0-5 months old, with nutritional status having no apparent effect. Parental formal education and crowding in households were found to be directly related to the incidence of ALRI. In general, ARI morbidity interfered with appropriate physical growth.

Acute Disease↗
PubMedDate not supplied

Specific milk immune response of rural and urban Guatemalan women to oral immunization with a food protein.

Forty-nine lactating women from Guatemala, 18 from a rural community and 31 from Guatemala City, were immunized orally with a protein extract from Vigna sinensis. Oral vaccination during the 1st week postpartum induced the appearance of short-lived, specific antibodies in milk in 59% of the subjects. No differences in rates of lactoconvertion were found either between socioeconomic groups or between malnourished and well-nourished women.

Adult↗
PubMedDate not supplied

Immature circulating lymphocytes in severely malnourished Guatemalan children.

The percentage of peripheral blood lymphocytes forming rosettes with sheep erythrocytes (E-rosettes) was determined in 33 severely malnourished Guatemalan children, and in two groups of clinically well but mildly growth retarded children from the same environment. Mean E-rosettes in the acutely ill patients was lower than the value observed in the mildly malnourished children, although there was considerable overlap between groups. These data differ from previously published studies of severely malnourished children from other parts of the world in that not all patients had decreased values for E-rosettes, in contrast to the uniform depression reported by others. As all patients were clinically similar, the results suggest that there may be specific nutrient defects associated with protein-energy malnutrition that particularly affect immune function. In addition, in vitro incubation of lymphocytes from the acutely malnourished children with the thymic factor, thymosin fraction 5, increased the percentage of E-rosettes in a dose-dependent fashion. These data suggest that immature, thymosin-responsive T cells are present in circulation. It is possible that in vivo thymosin administration may be beneficial for malnourished individuals.

Cell Differentiation↗
PubMedDate not supplied

Effects of nutritional recuperation on E-rosetting lymphocytes and in vitro response to thymosin in malnourished children.

The percentage of peripheral blood lymphocytes forming rosettes with sheep erythrocytes (E-rosettes) was determined at admission to the INCAP Clinical Center in eight acutely malnourished Guatemalan children, and again after 14 and 28-30 days of nutritional therapy. While the mean percentage of E-rosettes increased during therapy, the change (from 35.6 +/- 10% to 43.3 +/- 19%) did not reach statistical significance because of the variable response of different subjects. At each time period, however, in vitro incubation with the thymic factor, thymosin fraction 5, significantly increased the percentage of E-rosetting lymphocytes. The presence of thymosin responsive cells in circulation after 1 month of optimal nutritional support indicates that immature T-lymphocytes can persist in circulation in patients with severe malnutrition, even after clinical improvement. Thus, neither the percentage of E-rosettes in peripheral blood nor their response to in vitro incubation with thymosin correlated with anthropometric measures of nutritional status in individual patients. This suggests that other nutritional or nonnutritional factors may be important modulating influences on T-lymphocytes, and that prospective studies with thymic factor administration are warranted.

Child, Preschool↗