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Biomedical subjects

J R Cruz

Publications and source records attributed to J R Cruz.

At least 19 recordsLinked to original sources
PubMed1998

Procedures for developing a simple scoring method based on unsophisticated criteria for screening children for tuberculosis.

OBJECTIVE: To develop a scoring system for screening children for tuberculosis (TB) and for selecting suspects for further investigation in tuberculosis control programmes. Application of the score model, which would not require sophisticated or expensive technology, would be directed towards resource-poor countries with high prevalences of tuberculosis, where health care workers have to deal with diagnostic problems away from district hospitals or diagnostic facilities. DESIGN: Based on contributions from members of an IUATLD task group from 10 countries on the use of diagnostic criteria in childhood tuberculosis, criteria were selected to be used as elements in a score model. Data were collected by standardised questionnaire on 879 subjects aged under 15 years. Of these, 794 were considered probable or confirmed cases of tuberculosis by the diagnosing doctors. From each record, the criteria/procedures used in the diagnosis of probable/confirmed TB and regarded by the doctors as relevant criteria were selected. Bacteriology, histology and chest radiography were used either singly or collectively as the definitive reference (gold standard) against which the more subjective criteria (symptoms, clinical signs, skin test) would be evaluated. The latter criteria cited as relevant were then ranked and further explored for inclusion in the score model. The relative importance of each criterion to every other criterion on the list was expressed as weights, determined by employing a logarithmic least squares method to solve the ratio scale estimation problem which underlies decision-making involving more than one criterion. The resultant values were then assigned to each criterion in the final score model. RESULTS: The five clinical criteria thought to be most relevant as predictors of disease in children were history of contact with a case of tuberculosis, positive skin test, persistent cough, low weight for age, and unexplained/prolonged fever. In selecting the optimal cut-off points for the model at which tuberculosis would be suspected, low sensitivity and specificity (below 70%) but reasonably good positive predictive values (60%-77%) were obtained, depending on age group and epidemiological setting. In low tuberculosis prevalence settings, heavy reliance is placed by the model on a history of contact with a household case of tuberculosis and on a positive skin test, both of which have to be true. For high prevalence settings, more or less equal weighting is assigned to all five elements. Case contact and skin tests are less important, with low body weight, prolonged fever and cough being more indicative of tuberculosis. CONCLUSION: The model provides for epidemiological differences between target populations and should prove successful as a screening tool to select children for further investigation by radiography and bacteriology.

Adolescent↗
PubMed1997

Antibodies to Escherichia coli and Shigella flexneri in milk from undernourished mothers: studies on sodium dodecyl sulfate-polyacrylamide gel electrophoresis-separated antigens.

Analysis of IgA, IgM, and IgG antibodies against Escherichia coli O6, its lipopolysaccharide (LPS), and Shigella flexneri were performed in the milk of moderately undernourished Guatemalan women receiving either a low or a high calorie supplement, using SDS-PAGE. As expected, the immunostaining analysis of milk antibodies showed that IgA was the predominant isotype in both groups. Concerning the other Igs, antibodies against O6 LPS were mainly of the IgM isotype, whereas IgG antibodies were more prominent than IgM against the bacterial whole cell preparations. Seven to nine distinct bands, ranging in molecular mass from 13.5 to 109 kD were selected for each antigen to compare the milk antibodies between the two groups of women. After a 20-wk supplementation period, the IgA and IgG antibodies to the E. coli, O6 LPS, and S. flexneri were not found negatively affected by a low calorie intake. A significantly lower immunostaining intensity was, however, obtained for the low calorie intake group regarding the IgM antibody activity against four high molecular mass bands of the E. coli whole cell preparation. A decreased immunostaining intensity was also found in the same group for IgM antibodies against two bands of E. coli O6 LPS when analyzing paired samples collected at d 0 and wk 20. No differences were found for IgM antibodies against any of the S. flexneri antigens. In conclusion, the results suggest that low calorie intake does not significantly affect the production of milk IgA antibodies to E. coli and S. flexneri antigens in these women. Still, IgM antibodies against certain proteins and LPS molecules of E. coli may be decreased. IgG antibodies, although also present in milk, seemed to be directed mainly against bacterial proteins and not to LPS.

Antibodies, Bacterial↗
PubMed1997

Quality assessment activities in Latin America and the Caribbean.

The Pan American Health Organization (PAHO) supports performance evaluation programs in clinical chemistry, Caribbean. Much more work remains to be done before many labs in this part of the world can be certified as providing accurate results, but PAHO has taken an important first step toward establishing benchmarks and rallying for labs to improve test quality.

Caribbean Region↗
PubMed1997

Successful management of a national tuberculosis programme under conditions of war.

OBJECTIVE: To compare treatment results before and after introduction of short course tuberculosis chemotherapy and to identify factors affecting the results. DESIGN/SETTING: An eight-month chemotherapy regimen for smear-positive pulmonary tuberculosis was introduced in Nicaragua in 1984 with external financial assistance. We performed a retrospective record review to compare treatment results before and after introduction of short-course chemotherapy. Information on support services and programme administration, availability of hospital beds for tuberculosis patients, access to health services and the economic and war situation in the two periods was assessed. RESULTS: The overall success ratio improved by 39% between the two periods reviewed, in spite of evidence of a deteriorating economy and escalation in civil war. A success ratio of 71% was achieved and we estimate that between 80 and 90% of registered cases stopped transmitting tuberculosis. The best results were obtained in the treatment of previously untreated patients with eight-month chemotherapy and in retreatment of relapses. The worst results were obtained in retreatment of defaulters. Analysis of the findings by region suggests that short-course chemotherapy was important, but not enough by itself to guarantee success. Factors likely to have influenced treatment results are: commitment by health authorities in guaranteeing personnel and hospital beds, training of personnel, and supervision of service delivery. Possibilities for further improvement are discussed. CONCLUSIONS: Good results were achieved in tuberculosis control with the introduction of short-course chemotherapy in spite of poverty and war. Government commitment and simultaneous improvement in supportive services and programme management is important when introducing short-course chemotherapy in low income countries.

Antitubercular Agents↗
PubMed1995

Fecal excretion of leukotriene C4 during human disease due to Shigella dysenteriae.

Fecal excretion of leukotriene C4 was determined in 26 individuals with dysentery and in 19 healthy controls. Of the patients, five were infected with Shigella dysenteriae type 1, 15 were infected with Shigella flexneri, two were infected with Shigella boydii, and four were infected with Shigella sonnei. Three of the healthy controls were infected with non-dysenteriae Shigellae. All isolates of Shigella dysenteriae type 1 produced Shiga toxin; the other strains were not toxigenic. Patients with dysentery due to Shigella dysenteriae type 1 excreted higher concentrations of leukotriene C4 (median, 3,234 pg/0.05 g of feces) than either ill individuals infected with non-dysenteriae Shigellae (median, 202 pg/0.05 g) or healthy carriers (median, 145 pg/0.05 g) and uninfected controls (median, 129 pg/0.05 g). We propose that Shiga toxin stimulates intestinal mast cells, which release leukotriene C4, contributing to the inflammatory response in Shigella dysenteriae type 1-associated dysentery.

Adult↗
PubMed1994

Tuberculosis case-finding in Nicaragua: evaluation of routine activities in the control programme.

SETTING: The new International Union against Tuberculosis and Lung Disease (IUATLD) tuberculosis strategy developed in the 1980s in Tanzania, Malawi and Mozambique, was simultaneously implemented in Nicaragua. OBJECTIVE: Present results of case-finding, identify trends in incidence and limitations in case-finding and reporting. DESIGN: Data are based upon the traditional reporting system until 1987, replaced as the programme was reorganized. Data were also collected directly from the Central Laboratory, Programme and Laboratory registers during supervision of health centres. RESULTS: Quality control of sputum smears shows 1.8% discordance between peripheral and central laboratories. Notification rate of smear-positive tuberculosis declined 1.7% yearly 1983-1991 and 2.6% for all cases. Half of the patients are new smear-positive pulmonary cases, 40% smear-negative pulmonary cases. Relapses represent 11-13% of all smear-positive patients, children 7-30% of all cases. One-third of extrapulmonary tuberculosis cases are pleural effusions, another third lymphadenitis. 41% of adult patients entered as smear-negative in the programme had no smear reported in the laboratory. CONCLUSIONS: Quality control of sputum smears was established and the reporting system improved in spite of adverse conditions. Notification rate declined gradually. Smears should be done in all patients classified as smear-negative pulmonary tuberculosis.

Adolescent↗
PubMed1993

Protection against Campylobacter diarrhea: role of milk IgA antibodies against bacterial surface antigens.

In developing countries, Campylobacter jejuni causes diarrhea and dysentery, especially in children less than one year of age. Breast feeding protects against infectious diarrhea, with milk IgA antibody playing a determining role. Therefore, it has been proposed to increase the protective effect of human milk by vaccinating women of child-bearing age. To identify antigens which may induce protective breast-milk IgA, we analyzed 60 strains of C. jejuni isolated from asymptomatically- and symptomatically-infected breast-fed children less than 12 months of age. Surface antigens of C. jejuni, separated by polyacrylamide gel electrophoresis, were probed with breast milk collected concurrently with the fecal sample from which C. jejuni was isolated, and specific IgA was developed by immunoblotting. Our results indicate that milk antibodies against three high molecular weight bacterial surface antigens of 95, 110 and 185 kDa are involved in protection of infants infected with C. jejuni (p = 0.00964 for one-tailed Fisher's exact test).

Antigens, Bacterial↗
PubMed1993

The effect of caloric supplementation on selected milk protective factors in undernourished Guatemalan mothers.

The level and avidity indices of specific antibodies against tetanus toxoid, Escherichia coli O6 and a pool of 10 common E. coli O antigens, as well as the concentration and daily output of lactoferrin and total secretory IgA (SIgA), were evaluated in the milk of moderately undernourished mothers who were in a random blind design divided into two groups and given different caloric supplementations. Group A received a high caloric supplement (500 kcal/d), and group B received a low caloric supplement (140 kcal/d). Determinations were done using ELISA in various modifications, except for lactoferrin, which was quantified by single radial immunodiffusion. The avidity indices were investigated as an evaluation of the antibody quality. In all the parameters evaluated, the only difference found between the two groups at the end of the supplementation period was in the content of total SIgA, which was lower in group B, both in concentration and daily output. However, the SIgA remained within the normal range. Increases as well as decreases in the levels of specific IgA antibodies occurred within both groups. Avidity was decreased in group B only against one of the antigens tested. We conclude that moderate undernutrition does not impair the levels of milk antibodies, and supplementation does not enhance them but prevents the decrease in the content of total milk SIgA. There is a suggestion that the avidity of certain antibody specificities could be hampered.

Antibodies, Bacterial↗
PubMed1993

[Desmoplastic medulloblastoma: histologic factors of prognosis].

The histological features of eight cases of desmoplastic medulloblastoma were investigated and compared to classic medulloblastoma. The most benign histologic neoplasms belong to the group of desmoplastic medulloblastoma, characterized by low necrosis, low mitosis and light nuclear pleomorphism.

Adolescent↗
PubMed1992

Genotype-specific in vitro amplification of sequences of the wild type 3 polioviruses from Mexico and Guatemala.

The extensive nucleotide sequence heterogeneity among independent genotypes of wild polioviruses permits the systematic design of genotype-specific molecular reagents. We have prepared two sets of polymerase chain reaction (PCR) primer pairs specific for the genotype of wild poliovirus type 3 recently endemic to Mexico and Guatemala. Nucleotide sequences of a representative wild type 3 virus isolated in Mexico in 1989 differed from the corresponding Sabin 3 (Leon 12 a1b) sequences at 167 of 900 positions within the VP1 region. From the sequence data, wild virus-specific primer pairs were designed to complement regions of high mismatch (greater than 33%) with Sabin 3 templates. Primer binding sites were spaced along the genome so that the predicted amplification products (142 bp and 163 bp) could be easily resolved electrophoretically from the products generated with our Sabin strain-specific primers (Sabin 1: 97 bp; Sabin 2: 71 bp; Sabin 3: 53 bp). RNAs of all wild type 3 poliovirus isolates from Mexico and Guatemala obtained over a 13-year period (1977-1990) served as efficient templates for amplification of the 142-bp and 163-bp products. Genomic templates derived from vaccine-related polioviruses and most heterologous wild polioviruses were inactive under equivalent reaction conditions. Amplifications generating a 114-bp product with a broadly reacting primer pair, matching highly conserved sequences in the 5'-noncoding region, provided a positive control for the presence in samples of poliovirus (or enterovirus) RNAs. Selective amplification of wild Mexico-Guatemala type 3 poliovirus sequences was obtained with either primer set in reactions containing large stoichiometric excesses (up to 10(6)-fold) of vaccine-related RNAs. We have used wild genotype-specific PCR primer sets to facilitate identification of wild polioviruses present in both clinical and environmental samples.

Amino Acid Sequence↗
PubMed1992

Epidemiology of persistent diarrhea among Guatemalan rural children.

A prospective, longitudinal two-year study to determine the epidemiology of persistent (> or = 14 days' duration) diarrhea in rural children of Guatemala was undertaken. Three-hundred and twenty-one children aged 0-35 months were kept under surveillance by twice-a-week home visits. The overall incidence of diarrhea was 0.147 per child-week; the incidence of persistent diarrhea was 0.014 per child-week. The peak of persistent diarrhea was observed in infants below six months of age, with a continuous decline thereafter. This trend in incidence of persistent diarrhea was associated with a higher proportion (16%) of illnesses persisting for more than 13 days in children younger than six months of age as compared to children 30-35 months old (4%). Males had more diarrhea (0.156 per child-week) than females (0.139 per child week). Among children above 18 months of age, the proportion of episodes that lasted for more than 13 days was lower in females than in males.

Acute Disease↗
PubMed1992

Oral gentamicin is not effective treatment for persistent diarrhea.

We conducted a randomized, double-blind, placebo controlled clinical trial of oral gentamicin (10 milligrams/kilogram body weight/day for five days) in treatment of unselected cases of persistent diarrhea (duration 14-18 days at initiation of treatment) among 3-36-month-old children in a rural Guatemalan community. Following random assignment of each child to a treatment group, the appropriate dose of gentamicin or placebo was administered to the child three times daily by a study nurse; this nurse also identified the presence or absence of diarrhea on each day of treatment and for the next two days. Cure was defined as cessation of diarrhea during the five-day treatment period, sustained through at least the two days after completion of treatment. Among 92 evaluable cases who entered the clinical trial, there was essentially no difference in cure rate between gentamicin and placebo treatment groups (42% versus 43%). Enteroadherent strains of Escherichia coli were identified in 46% of children tested in this trial; no significant difference existed between treatment groups in frequency of isolation of this or any other enteropathogen. Among 40 children having successful duodenal cultures immediately prior to beginning treatment, > or = 10(4) aerobic organisms per milliliter of fluid were identified in 12 (30%); treatment groups did not differ substantially with respect to proportion of children identified with this level of duodenal microbial colonization. Failure of gentamicin treatment did not appear to be explained by emergence of resistance, although a small number of resistant enteropathogens were identified near the end of the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

Astrovirus-associated diarrhea among Guatemalan ambulatory rural children.

Fecal excretion of astroviruses was monitored in 321 children, 0 to 3 years old, living in the rural highlands of Guatemala. During the longitudinal study, from February 1987 to February 1989, we examined 5,000 stool specimens, including 1,805 collected during 1,369 episodes of diarrhea, 830 collected during the convalescent week, and 216 and 244 collected 2 weeks and 1 week, respectively, before the onset of diarrhea. Routine specimens were taken once a month from every child who had been free from diarrhea for at least three consecutive weeks. Of the children, 124 (38.6%) excreted astroviruses during the study. In total, we identified 184 infections by astroviruses. Of the samples collected 2 weeks and 1 week before the initiation of symptoms, 0.9 and 4.9%, respectively, were positive, while 7.3% of the diarrhea episodes were associated with astroviruses. Of the convalescent specimens, 3.4% were shown to be positive; 2.4% of the 1,905 specimens taken in diarrhea-free periods contained astroviruses. Infections by other potential enteropathogens were documented in 54 and 65% of the asymptomatic and symptomatic astrovirus infections, respectively. Diarrhea associated with astroviruses alone had a median duration of 5 days and was associated with vomiting in 8.6%, with fever in 17.1%, with dehydration in 5.7%, and with loss of appetite in 34.3% of the episodes. Diarrhea due to astroviruses was accompanied by negative changes in weight gain. Astrovirus diarrhea contributes to the high morbidity observed in young children living under poor conditions and has a deleterious effect on their nutritional status.

Body Weight↗
PubMed1990

Colors, humors and evil eye: indigenous classification and treatment of childhood diarrhea in highland Guatemala.

Focal group interviews on indigenous perceptions and reported management of childhood diarrhea were conducted in 1987-88 in Guatemala as a part of a prospective epidemiological field study of chronic diarrhea. Six cognitive schemata were identified, each with specific causes, a linked progression of concepts, symptoms, signs, and diagnostic characteristics. Nearly all were related to the humoral theory of disease, including the concept of evil eye. Diarrheal disease was conceptualized in the village as a set of processes which could be either "hot" or "cold" rather than as an unchanging single-symptom entity occupying only one spot on the humoral continuum. Clarification of the temporal relationship between concepts was found to be essential to the understanding of these indigenously-defined schemata. Stool color reflecting humoral theory was the primary concept used in household-level diagnosis. Reported behavior associated with these cognitive schemata (traditional treatments, pharmaceutical and dietary management) showed remarkable constancy, and adhered for the most part to the humoral concept of equilibrium. These included the use of oral rehydration solutions (ORS) and liquids. The applied importance of humoral theory to home-based use of ORS is discussed briefly as is the indigenous definition of dehydration.

Child, Preschool↗