EBV, HCMV, HHV6, and HHV7 screening in bone marrow samples from children with acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is the most common cancer in childhood worldwide and Mexico has reported one of the highest incidence rates. An infectious etiology has been suggested and supported by epidemiological evidences; however, the identity of the involved agent(s) is not known. We considered that early transmitted lymphotropic herpes viruses were good candidates, since transforming mechanisms have been described for them and some are already associated with human cancers. In this study we interrogated the direct role of EBV, HCMV, HHV6, and HHV7 human herpes viruses in childhood ALL. Viral genomes were screened in 70 bone marrow samples from ALL patients through standard and a more sensitive nested PCR. Positive samples were detected only by nested PCR indicating a low level of infection. Our result argues that viral genomes were not present in all leukemic cells, and, hence, infection most likely was not part of the initial genetic lesions leading to ALL. The high statistical power of the study suggested that these agents are not involved in the genesis of ALL in Mexican children. Additional analysis showed that detected infections or coinfections were not associated with prognosis.

Allergy and acute leukaemia in children with Down syndrome: a population study. Report from the Mexican inter-institutional group for the identification of the causes of childhood leukaemia.

BACKGROUND: Allergies have been described as protective factors against the development of childhood acute leukaemia (AL). Our objective was to investigate the associations between allergy history and the development of AL and acute lymphoblastic leukaemia (ALL) in children with Down syndrome (DS). METHODS: A case-control study was performed in Mexico City. The cases (n=97) were diagnosed at nine public hospitals, and the controls (n=222) were recruited at institutions for children with DS. Odds ratios (OR) were calculated. RESULTS: Asthma was positively associated with AL development (OR=4.18; 95% confidence interval (CI): 1.47-11.87), whereas skin allergies were negatively associated (OR=0.42; 95% CI: 0.20-0.91). CONCLUSION: Our findings suggest that allergies and AL in children with DS share biological and immune mechanisms. To our knowledge, this is the first study reporting associations between allergies and AL in children with DS.

Breastfeeding and early infection in the aetiology of childhood leukaemia in Down syndrome.

BACKGROUND: For a child to develop acute leukaemia (AL), environmental exposure may not be sufficient: interaction with a susceptibility factor to the disease, such as Down syndrome (DS), may also be necessary. We assessed whether breastfeeding and early infection were associated with the risk of developing AL in children with DS. METHODS: Children with DS in Mexico City, and either with or without AL, were the cases (N=57) and controls (N=218), respectively. Population was divided in children with AL and with acute lymphoblastic leukaemia (ALL) and also in children < or = 6 and >6 years old. RESULTS: Breastfeeding and early infections showed moderate (but not significant) association for AL, whereas hospitalisation by infection during the first year of life increased the risk: odds ratios (confidence interval 95%) were 0.84 (0.43-1.61), 1.70 (0.82-3.52); and 3.57 (1.59-8.05), respectively. A similar result was obtained when only ALL was analysed. CONCLUSION: We found that breastfeeding was a protective factor for developing AL and ALL, and during the first year of life, infections requiring hospitalisation were related to a risk for developing the disease in those children with DS >6 years of age. These data do not support the Greaves's hypothesis of early infection being protective for developing ALL.

KIR gene in ethnic and Mestizo populations from Mexico.

Killer cell immunoglobulin-like receptors are characterized by their great diversity of genes and alleles. Population studies have identified the presence of a broad variety of genotypes. In Mexico, there are diverse ethnic groups representing 9% of the total population and the rest is composed of Mestizos with a more varied biology. For the purpose of this study, genotyping was performed in Mestizos, in Mexico City inhabitants, and in three ethnic groups. The frequencies of genes KIR2DL2, 2DL5, 2DS1-3, 2DS5, and 3DS1 showed a greater variability in the groups studied. A total of 12 different genotypes were identified, the higher number for the Mestizos and the lower number for the Tarahumaras. Genotype 1 was found at a greater frequency in all the groups, except for the Tarahumaras, in which genotype 4 was more frequent. The frequency of genotypes 4 and 8 in Mexicans was higher than that for other populations analyzed. By subtyping of KIR3DL1, 3DL2, 2DL1, and 2DL3, two B haplotypes were identified in families; both were absent in Caucasian families. Our results indicated a greater diversity of genes in the Mestizos group than in the ethnic groups.

Epidemiology of cancer in children under one year of age in Mexico City.

In this work, the epidemiology of cancer in children under one year of age in Mexico City is described. A survey (observational, descriptive and prolective study) from 1 January 1996 to 31 December 1999 was conducted at two paediatric hospitals of the Instituto Mexicano de Seguro Social in Mexico City (IMSS-MC). To calculate both the general and the by sex incidence (rates are given per 10) all new cases recorded for children under one year of age (numerator) and Mexico City population served by the IMSS (denominator) were used. When the total of 34 cases that fulfilled the requirements was analysed, an incidence of 194.5 was obtained. Leukaemia occupied first place with a rate of 68.6 and hepatic and germinal cells tumours occupied second place with an incidence of 28.6, whereas peripheral nervous system tumours (neuroblastoma) showed a very low rate (11.4). Overall, the male/female ratio for tumours was 1.4:1, with the ratio varying with different types of tumours. Cancer incidence in this population was shown to be close to that in developed countries, but differed in the distribution of the type of tumour: leukaemia had a very high incidence and that for neuroblastoma was very low.

[Incidence of acute leukemia in children in Mexico City, from 1982 to 1991]. / Incidencia de las leucemias agudas en niños de la ciudad de México, de 1982 a 1991.

OBJECTIVE: To measure the incidence rate and trend of acute leukemia (AL) in political districts of Mexico City. MATERIAL AND METHODS: Descriptive longitudinal study conducted at six hospitals that care for nearly 97.5% of all cancer cases among children in Mexico City. Study data were collected in 1995 and 1996, and were analyzed in 1999, at the National Medical Center "Siglo XXI" Children's Hospital, of the Mexican Institute for Social Security. Calculations of acute leukemia annual incidence rates, standardized rates, and standardized morbidity rates (SMR) with 95% confidence intervals, were obtained for each district. Morbidity trends were assessed through average change rates. RESULTS: In this study we observed an increasing trend of acute lymphoblastic leukemia (ALL) incidence in five districts: Alvaro Obregon, Cuauhtemoc, Gustavo A. Madero, Iztacalco, and Venustiano Carranza. Acute myeloblastic leukemia (AML) showed no significantly statistic increase of incidence in any district. AML did show a significant SMR in Alvaro Obregon district (SMR = 2.91, 95% CI 1.63-4.80). Higher SMRs were found in the south and southwest areas of the city. CONCLUSIONS: Increasing incidence of ALL was observed in five districts of Mexico City. AML incidence was the highest in Alvaro Obregon district.

[Pneumonia complicated with empyema in children, to operate or not? Risk factors for surgery and review of the literature]. / Neumonía complicada con empiema en niños, operar o no operar? Factores de riesgo para cirugía y revisión de la literatura.

The precise indication for surgery for pleural empyema is still a controversy. With the aim of identifying the risk factors associated with surgery in pediatric patients with empyema post-pneumonia, a retrospective case control study was performed. From 1992 to 1996, 18 children underwent surgery (cases) and 12 did not (controls). The analyzed variables were those mentioned in the literature as risk factors. More than 25 days of evolution, more than three antibiotic schemes, fever, empyema organizing phase, two or more chest tubes lasting more than nine days, multiple loculations, trapped lung and paquipleura were associated with thoracostomy and decortication (p < 0.05). We conclude that a pediatric patient with a late referral to the hospital, empyema organizing phase, and multiple loculations with large purulent collections no longer susceptible to drainage and complications that impair lung expansion will probably require major surgery.

[Consistency and validity of the evaluation of the clinical chart]. / Consistencia y validez en la evaluación del expediente clínico.

OBJECTIVE: Assess the degree of external consistency and validity of the EXP CLIN instrument has for measuring the quality information contained in medical charts. MATERIAL AND METHODS: In a transverse comparative study, two hundred and twelve clinical charts were randomly selected belonging to patients seen at a pediatric hospital. The charts were assessed using the EXP-CLIN for phases: 1) internal assessment: by hospital personnel of the pediatric hospital, and, II) external assessment: by personnel from other hospitals. The results were analyzed using the concordance method. RESULTS: The concordance percentages were found to be 76% for medical charts and medical notes related with the process of diagnosis-treatment, as well as the general characteristics of the clinical chart. The concordance percentages average was 88%, supporting the idea that when the EXP-CLIN instrument is applied twice to the same chart, good concordance is obtained between the two measures. CONCLUSIONS: Given that the application of the instrument documented a good level of external consistency, its use is justified for assessing the quality of the information contained in the charts of the patients seen at our unit.

[Descriptive epidemiology of malignant tumors in children]. / Epidemiología descriptiva de las neoplasias malignas en niños.

The object of this study is to present the descriptive epidemiology of cancer in children at the world and national levels. The international and national literature published on cancer in children was comprehensively reviewed, with emphasis on reports treating epidemiological aspects of time, place and person. For practical reasons and with the aim of integrating the information, only the more relevant publications were included. Incidence and child mortality were analyzed. Overall incidence is between 100 and 150 (annual rates = cases x 10(6) children). Specific incidence varies according to the type of cancer, the region and the country. The Latin American pattern of neoplasms is constituted by leukemias, lymphomas, and central nervous system tumors (CNST); in the Northamerican/European pattern the CNST appear in second place and in the African pattern, lymphomas show predominance. Incidence is higher among the younger than 5 year olds, from urban environments, and there is a 1% annual increase of cancer in Northamerican children. Child mortality has diminished remarkably, mainly in developed countries, whereas in developing or underdeveloped countries, incidence remains stable or shows a slight fall. The incidence of cancer in children is greater in developed countries, but in underdeveloped countries it may be underestimated. These countries have not managed to reduce the incidence of child mortality caused by cancer, as have the United States or Great Britain. Further studies on the epidemiology of cancer in children are necessary, since many data remain unknown.

Malnutrition in childhood lymphoblastic leukemia: a predictor of early mortality during the induction-to-remission phase of the treatment.

BACKGROUND: Previous reports have shown that undernourished children with acute lymphoblastic leukemia (ALL) have a poorer long-term survival as compared with children with normal nourishment status. It has been shown that both the relapse and mortality rates of undernourished children with ALL are higher during the continuation phase of the chemotherapy and are apparently related to a poor tolerance of ablative chemotherapy. No previous articles have analyzed the early mortality rate of these patients. METHODS: We carried out a case-control study, and have studied the effect of severe malnutrition on the mortality of 17 children with ALL during the initial induction-to-remission phase of the treatment. These 17 cases were compared with 76 controls who had survived at least the phases of induction and consolidation. RESULTS: It was found that the chance of dying during the initial phase of the treatment was 2.6 times higher (confidence interval 95%: 0.55-11.89) in undernourished children with ALL than in those children with normal nourishment status. The risk of death increased with the severity of undernourishment (p = 0.04). CONCLUSIONS: These data confirm the prognostic value of malnutrition in children with ALL and suggest that undernourishment may also influence early mortality during the induction-to-remission phase of the treatment.

[Lipid profile in healthy newborn infants and its correlation with maternal lipid levels]. / Perfil de lípidos en recién nacidos sanos y su correlación con los niveles de lípidos maternos.

OBJECTIVE: To determine serum levels of lipid, cholesterol, triglycerides and lipoproteins in newborns and their mothers and to know the association between them. MATERIAL AND METHODS: Blood samples were taken from 200 newborns and from their mothers, and analyzed for lipid, cholesterol, triglyceride and lipoprotein content in an autoanalyzer. Data were analyzed with the Epi Info 6 program. Central tendency measurements, variance analysis and Pearson correlation coefficient were obtained. RESULTS: Average lipid levels in newborn blood samples was 625.2 +/- 130, 158.8 +/- 44 mg/dl of cholesterol, 136.9 +/- 97 mg/dl of triglycerides, 70.5 +/- 23.9 mg/dl LDL, 52.7 +/- 14 mg/dl HDL and 26.5 +/- 15.5 mg/dl VLDL. CONCLUSIONS: Newborn cholesterol levels were similar to values reported by Alpers and higher than levels published by the American Committee of Pediatric Biochemistry in USA. An association between levels in mothers and their children was found.

[Classification by levels of clinico-epidemiological research designs]. / Clasificación en niveles de los diseños de investigación clínico-epidemiológicos.

The objective was to identify the characteristics of epidemiologic designs enabling their classification. A critical review of the literature in the clinical epidemiologic area was done to establish the main differences between designs. A meeting with experts to discuss this controversial topic and obtain criteria by consensus was organized. We propose an integral classification based on levels with two fundamental shafts: intervention and explanatory reasoning.

Nutritional state alterations in children with acute lymphoblastic leukemia during induction and consolidation of chemotherapy.

The objective of the study was to determine if children with high risk acute lymphoblastic leukemia (ALL) exhibit higher frequency of alterations in nutritional state during the phases of induction and consolidation of chemotherapy than children with low risk ALL, based on the arm muscle area. The design was concurrent comparative cohorts. It was performed at pediatric hematology service of the Hospital General del Centro Médico Nacional "La Raza" and hematology service of the Hospital de Pediatría del Centro Médico Nacional "Siglo XXI". One hundred-five patients were incorporated into the study: 53 with high risk (HR) ALL and 52 with low risk (LR) ALL. Basal measurements of arm circumference and tricipital skinfold were surveyed monthly (for 3 months) by standardized personnel. Altered nutritional state during follow-up was defined as the loss of 10% or more of the arm muscular area (AMA) measured at diagnosis. Statistics of proportion analysis with a significance level of 0.05 and relative risk (RR) with confidence intervals (CI) were calculated. In the first month the RR was 0.77 (CI 0.31-1.87); the LR group was the most affected. In the second month the RR was 7.31 (CI 1.41-38.03); the most affected group was the HR. In the third month the RR was 1.77 (CI 0.60-4.92); the HR group was the most affected. High-risk patients show a higher frequency of nutritional state alterations reflected in AMA during the second month after diagnosis. This may be caused by the more aggressive chemotherapy received by these patients.

[Dyslipidemia associated with food]. / La dislipidemia asociada con los alimentos.

The increase of the morbi-mortality due to CHD in México, particularly among the Social Security Institute (IMSS) workers led us to do research on the relative risk and the protection provided by foodstuffs usually consumed by these workers. We found significant evidence of low levels of cholesterol associated with dry alcoholic drinks, skimmed milk and yogurt as well as fresh cheeses. C-LDL was low among people that usually consume sweet alcoholic drinks and fresh cheese. High levels of TG were associated with those people consuming food products containing saturated fat (bacon, pork crackling, fatty red meat, fowl with skin) and viscera, more than three standard cups of alcoholic drinks three times a week, soft drinks and salt. Skimmed milk and yogurt and all vegetables were related to low levels of TG. Products related to high levels of C-HDL were all kinds of vegetables and beans. This study of IMSS worker eating habits could be useful to do research on the food intake of other worker populations, and could help us to design Health Education programs based on scientific knowledge.

[Incidence of common ophthalmological disorders in preschool children in Mexico City]. / Frecuencia de transtornos oftalmológicos comunes en población preescolar de una delegación de la ciudad de México.

OBJECTIVE: To estimate the prevalence of undetected vision abnormalities among preschool children. These problems can lead to a variety of adverse consequences, the most serious being amblyopia, which becomes irreversible after the fifth year without treatment. In some other countries there are screening programs to identify visual abnormalities among four year old children. In our country there are no studies about the prevalence of this problem among preschool children. MATERIAL AND METHODS: A total of 39 preschool children were randomly selected from 93 kindergarten schools in a District of Mexico City. In total, 343 children were screened for ophthalmologic abnormalities by two pediatricians who were previously trained for this purpose. RESULTS: Fifty-seven (16.6%) children failed the visual acuity testing: four had strabismus, four cataract, and one glaucoma, and 48 refraction defects. Only 13 (3.8%) had been previously examined, ever. CONCLUSIONS: We consider that the prevalence found supports the recommendation to promote ophthalmologic examining as part of the routinary child care practice and to perform preventive preschool screening.

Incidence trends of acute leukemia among the children of Mexico City: 1982-1991.

The objective of this study was to identify the tendency of acute leukemia among children in Mexico City from 1982 to 1991. A hospital survey was performed. Medical records of children under 15 years of age with a diagnosis of acute leukemia were reviewed. The cases were chosen from hospitals which provide medical attention to children with cancer in Mexico City. The annual incidence rate (AIR) was calculated in general, by sex, age groups (under 1 year of age, from 1 to 4 years, 5 to 9 years and 10 to 14 years) and standardized with the world population. The trend was evaluated with Spearman's correlation method. Acute lymphoblastic leukemia showed a significantly increasing trend during the study period. The AIR was 7.75 (per million) in 1982 and 22.19 (per million) in 1991. For age groups a tendency to increase was observed in females of age group 1 to 4 years and in males of age group 10 to 14 years. Acute non-lymphoblastic leukemia did not display a specific trend. In conclusion, acute lymphoblastic leukemia shows a tendency to increase in the children of Mexico City.

[Evaluation of immunologic diagnostic tests in amebiasis: diagnosis or bias? A critical review of the literature]. / Evaluación de las pruebas de diagnóstico inmunológico en amibiasis: diagnóstico ó sesgo?

OBJECTIVE: 1. To describe the frequency of adherence to methodologic criteria proposed for assessment of diagnostic tests. 2. To identify potential bias. 3. To construct Receiver Operating Characteristic (ROC) curves based on data published on the assessed papers. DESIGN: Descriptive cross-sectional survey. STUDY MATERIAL: All papers listed under diagnosis and immunological headings of amebiasis in the Index Medicus from 1970 to 1988. STUDY UNITS: 80 papers. MEASUREMENT: a: Adherence to methodologic criteria proposed for assessment of diagnostic test. b: presence of potential bias. MAIN RESULTS: The adherence to methodologic criteria varied 1 to 55% of the papers. The comparison with a "gold standard" occurred in 40% the independent "blind" assessment occurred in 6% the setting for the study was described 1%. The study of an appropriate spectrum of disease was done in 11%. We were able to construct ROC curves with data from 37 papers and differences were observed among studies evaluating the same test. A high proportion of papers had potential bias. CONCLUSIONS: The adherence to methodologic standards is poor in the papers analyzed in this series. Consequently the frequency of potential bias was high.