Genetic rearrangement MLL/AF4 is most frequent in children with acute lymphoblastic leukemias in Mexico City

One of the highest incidences of acute lymphoblastic leukemia (ALL) in the world has been reported in Mexico City. In the current study (26 cases), the frequencies of the most frequent genetic rearrangements TEL-AML1, MLL/AF4, BCR-ABL (major and minor) in ALL in children from Mexico City were determined. For the ALL, the frequency of MLL/AF4 was 65.4%, for TEL-AML1 and that of BCR/ABL was 3.8%. Only 6 of the 17 children with the MLL/AF4 rearrangement were less than 26 months old. The frequency reported for MLL/AF4 in Mexican children with ALL is one of the highest worldwide. These findings could potentially explain the higher frequency of ALL with poor prognosis for children in Mexico City.

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 ⩽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.

Father's occupational exposure to carcinogenic agents and childhood acute leukemia: a new method to assess exposure (a case-control study)

Background

Medical research has not been able to establish whether a father's occupational exposures are associated with the development of acute leukemia (AL) in their offspring. The studies conducted have weaknesses that have generated a misclassification of such exposure. Occupations and exposures to substances associated with childhood cancer are not very frequently encountered in the general population; thus, the reported risks are both inconsistent and inaccurate. In this study, to assess exposure we used a new method, an exposure index, which took into consideration the industrial branch, specific position, use of protective equipment, substances at work, degree of contact with such substances, and time of exposure. This index allowed us to obtain a grade, which permitted the identification of individuals according to their level of exposure to known or potentially carcinogenic agents that are not necessarily specifically identified as risk factors for leukemia. The aim of this study was to determine the association between a father's occupational exposure to carcinogenic agents and the presence of AL in their offspring.

Methods

From 1999 to 2000, a case-control study was performed with 193 children who reside in Mexico City and had been diagnosed with AL. The initial sample-size calculation was 150 children per group, assessed with an expected odds ratio (OR) of three and a minimum exposure frequency of 15.8%. These children were matched by age, sex, and institution with 193 pediatric surgical patients at secondary-care hospitals. A questionnaire was used to determine each child's background and the characteristics of the father's occupation(s). In order to determine the level of exposure to carcinogenic agents, a previously validated exposure index (occupational exposure index, OEI) was used. The consistency and validity of the index were assessed by a questionnaire comparison, the sensory recognition of the work area, and an expert's opinion.

Results

The adjusted ORs and 95% confidence intervals (CI) were 1.69 (0.98, 2.92) during the preconception period; 1.98 (1.13, 3.45) during the index pregnancy; 2.11 (1.17, 3.78) during breastfeeding period; 2.17 (1.28, 3.66) after birth; and 2.06 (1.24, 3.42) for global exposure.

Conclusion

This is the first study in which an OEI was used to assess a father's occupational exposure to carcinogenic agents as a risk factor for the development of childhood AL in his offspring. From our results, we conclude that children whose fathers have been exposed to a high level of carcinogenic agents seem to have a greater risk of developing acute leukemia. However, confounding factors cannot be disregarded due to an incomplete control for confounding.

Magnetic fields and acute leukemia in children with Down syndrome

BACKGROUND

: We analyzed effects of exposure to magnetic fields on the expression of acute leukemia in children with Down syndrome (who have a 20-fold higher risk of leukemia).

METHODS

: We performed a case-control study that included 42 children with both acute leukemia and Down syndrome as cases and 124 healthy children with Down syndrome as controls. We obtained demographic information concerning the children and took spot measurements of magnetic fields at each residence.

RESULTS

: The odds ratio for direct measurements of magnetic fields >/=6.00 mG was 3.7 (95% confidence interval = 1.05-13.1).

CONCLUSION

: The association between magnetic fields and leukemia in children with Down syndrome suggests the possibility of a causal role for magnetic fields in the etiology of leukemia among a genetically susceptible subgroup of children.

Prevalence of high blood pressure and associated coronary risk factors in an adult population of Mexico City

BACKGROUND

Several studies have addressed arterial hypertension prevalence in Mexico. However, few include an analysis of other types of hypertension and their associated risk factors. The present work describes the prevalence of high blood pressure (HBP), isolated systolic hypertension (ISH) and diastolic hypertension (DH) and their association to certain risk factors of cardiovascular disease in an adult population of Mexico City.

METHODS

A cross-sectional study was performed on 825 subjects aged between 20 and 90 years, selected by multistage cluster sampling. HBP was diagnosed by previous history if systolic blood pressure was > or = 140 mmHg and/or diastolic blood pressure > or = 90 mmHg. The measurements taken included body mass index, waist-to-hip ratio, systolic and diastolic blood pressure, levels of insulin, glucose, trigylycerides, total cholesterol, high and low density lipoprotein cholesterol, and lipoprotein(a).

RESULTS

Prevalence adjusted by age for HBP was 19.4%, for ISH, 4.7%, and for DH, 4.1%. Age had an important influence on HBP and ISH with a highly significant X2t. The profile of metabolic variables was modified according to sex and type of hypertension. Thus, in DH, metabolic variables were more affected than in other types of hypertension.

CONCLUSIONS

Results in HBP prevalence in the present study were lower than in other surveys performed in Mexico. It must be noted, however, that much care should be taken to choose the strategy of subject selection, since results of the prevalence of a disease depend on it to a great extent. The ISH and DH and their association to risk factors must be studied thoroughly because they constitute different clinical entities.

Clustering of metabolic disorders and hyperinsulinemia in Mexico City

OBJECTIVE

To investigate the relationship between fasting insulin concentrations and several metabolic and anthropometric variables in the Mexico City population.

DESIGN

Cross-sectional, randomized, stratified by age, sex and economically active and inactive.

SUBJECTS

700 healthy adults, older than 20 years, 396 males and 304 females.

MEASUREMENTS

Body mass index, waist to hip ratio, systolic and diastolic blood pressure, insulin, glucose, triglycerides, total, HDL and LDL cholesterol and lipoprotein(a).

RESULTS

Means for age were 39 +/- 13 years for men and 41 +/- 12 for women (p < 0.05). In males, the mean values of body mass index, waist-to-hip ratio, systolic and diastolic blood pressure, triglycerides, glucose and LDL-cholesterol : HDL-cholesterol increased significantly with higher insulin levels. A significant inverse tendency was observed for the mean concentrations of HDL-cholesterol and lipoprotein(a). Age, total cholesterol and LDL-cholesterol were not related to the insulin levels. A similar pattern was observed in women, significance, however, was only obtained for the body mass index, triglycerides, glucose, HDL-cholesterol and lipoprotein(a). Age-adjusted multiple regression analysis showed that insulin was directly and independently associated to triglyceride levels and inversely with lipoprotein(a) concentrations for both sexes, and with HDL-C, only in males.

CONCLUSIONS

The prevalence of insulin resistance related metabolic disorders was high in a random sample of the Mexico City population. Increased cardiovascular risk factors associated with the insulin resistance syndrome were observed with higher insulin levels, and lipoprotein(a) was inversely and significantly related to insulin. Preventive strategies are urgently needed to avoid the already increased incidence of morbidity and mortality associated to atherosclerotic disease.

[Puerperium with short-term hospitalization]

Seventy seven cases with discharge before 12 hours post-partum and 240 cases with discharge after 24 or more hours after delivery, were evaluated at Hospital General de México, in an observational, prospective, cohort, study in low risk deliveries. Both groups were reviewed ten days after delivery. There were no different ratios for abnormal uterine hemorrhage, urinary tract infection or endometritis. Thrombophlebitis was more frequent in early discharge patients, both statistically and clinically significant (RR3.58, CI95% 1.48-8.67, P = 0.003). This finding is discussed, as well as measures to prevent it. It is concluded that early discharge programs in low risk conditions, are convenient.

The prevalence of NIDDM and associated coronary risk factors in Mexico City

OBJECTIVE

To determine the prevalence of diabetes and associated coronary risk factors in the Mexico City population.

RESEARCH DESIGN AND METHODS

A sample of 805 adults was selected from Mexico City. The participants, 20-90 years of age and living in the city, were selected by the method of multistage cluster sampling with proportional allocation. Diabetes was diagnosed by previous history or if fasting blood glucose was > or = 7.8 mmol/l ( > or = 7.8 mmol/l ( > or = 140 mg/dl).

RESULTS

The crude rate prevalence of NIDDM was 8.7%, with an age-adjusted rate of 10.6% for women and 6.0% for men. Age strongly influenced diabetes prevalence, with a chi 2 of risk tendency of 39.1 (P < 0.00005). A significant proportion (5.9%) of younger individuals (35-44 years of age) was affected by the disease. Diabetes was associated with advanced age, had a greater impact in the low-income group, and showed increased odds ratio for hypertension, dyslipidemias, and myocardial infarction in men and women and for obesity only in women.

CONCLUSION

There is a high prevalence of NIDDM in Mexico City that also strikes a significant group of younger individuals. Associated coronary risk factors are also common and more prevalent in diabetic individuals. Current epidemiological data in Mexico and Mexican-Americans in the U.S. suggest that we may be on the ascending limb for diabetes and cardiovascular disease. There is a critical need for resources to be allocated to programs for primary and secondary prevention, which must be well structured and organized so that proper standards of care are followed to prevent progression of the disease.