Biomedical subjects

A Chávez

Publications and source records attributed to A Chávez.

At least 37 records · Page 2Linked to original sources

PubMed1994

Iron, vitamin B-12 and folate status in Mexico: associated factors in men and women and during pregnancy and lactation.

To determine the prevalence and causes of anemia in rural Mexico, blood samples and longitudinal dietary data were collected from 187 women, some pregnant and then lactating, and from 72 men. Blood was used to measure anemia, mean cell volume, and plasma ferritin, folate and vitamin B-12. Anemia was found in 33% of the men, 54% of nonpregnant, nonlactating women, 35% of pregnant women and 41% of lactating women, and varied by season. Low iron stores (ferritin) accompanied anemia in only 8% of men compared with 38-67% of women. Low meat intake and poor dietary iron bioavailability were associated with anemia in women. There were no cases of low plasma folate. Low plasma vitamin B-12 was common in all groups, and the incidence increased from 15% at 7 mo of pregnancy to 30% at 7 mo of lactation. Vitamin B-12 was lower in the plasma and milk of anemic lactating women than in plasma and milk of non-anemic lactating women and was classified as deficient in 62% of breast milk samples.

Adult↗

PubMed1994

[Multidisciplinary study of cerebrovascular disorders. II. Cardiovascular profile of occlusive vascular disorders].

Ischemic stroke constitute a mayor cause of morbidity and mortality in the adult population, particularly in the elderly. Heart disease may predispose to ischemic stroke, especially in the presence of transient or permanent precipitating factors such as atrial fibrillation. To elucidate the role of heart disease in predisposing to ischemic stroke we studied the clinical and non invasive cardiac profile (EKG, 2D-Echo, Holter) of 186 consecutive patients, 91 of them embolic (GI) and 96 non embolic (lacunar, atherothrombotic, others) (GII), as determined by brain CT scan and thorough clinical evaluation. Age and male/female ratio were significantly different (71 + 13 vs 65 + 12 years, 40/60 vs 65/35, p < 0.003). Hypertension was equally common in both groups (38 and 40%). Patients in GI had higher prevalence of valvular heart disease (23 vs 1%), atrial fibrillation (67 vs 10%), 2D Echo left atrial enlargement (45 vs 16%) and supraventricular ectopy in Holter (59 vs 32%) p < 0,001. By contrast absence of heart disease (45 vs 19%), ST-T changes in EKG (28 vs 14%), left ventricular hypertrophy in 2D Echo (28 vs 9%) and ventricular ectopy in Holter (54 vs 23%) were more prevalent in GII patients, p < 0.001. Multiple stepwise logistic regression analysis showed age > 70 years (relative risk (RR) 1.67), valvular heart disease (RR 2.25), chronic AF (RR 2.44) and paroxysmal AF (RR 1.89) were significant independent predictors of embolic stroke, whereas the presence of left ventricular hypertrophy in 2D-Echo (RR 0.76) and frequent ventricular premature beats in Holter (RR 0.47) were predictors of occlusive non embolic stroke. Thus, the clinical and non invasive cardiac profile of embolic and non embolic ischemic stroke is significantly different, which is relevant to preventive strategies.

Age Factors↗

PubMed1992

Risk factors for systemic embolism in patients with paroxysmal atrial fibrillation.

The purpose of this study was to define the risk factors for systemic embolism in patients with recently diagnosed paroxysmal atrial fibrillation. We therefore studied 63 consecutive patients with symptomatic nonvalvular paroxysmal atrial fibrillation and performed a clinical and noninvasive cardiac, peripheral vascular, and neurologic evaluation that included two-dimensional echocardiography, 24-hour Holter monitoring, and computed tomographic brain scan. Patients with predisposing clinical conditions for systemic embolism (valvular heart or coronary artery disease) or paroxysmal atrial fibrillation (sick sinus disease, preexcitation, or thyroid dysfunction) were excluded. At entry 34 patients had idiopathic paroxysmal atrial fibrillation and 29 had hypertension. Fourteen patients had a recent systemic embolic complication: nine had a recent occlusive nonlacunar cerebrovascular accident, two had transient ischemic attacks, and three had peripheral systemic emboli that required surgery. In addition, five patients had evidence of old cerebrovascular accident on the computed tomographic scan (group 1). Forty-four patients had no systemic embolism (group 2). Results of univariate analysis showed that patients in group 1 were older (72 +/- 9 vs 63 +/- 13 years, p less than 0.05), had a higher incidence of hypertension (70% vs 35%, p less than 0.01), and had an increased left atrial diameter (4.1 +/- 0.7 vs 3.6 +/- 0.5 cm, p less than 0.05). Multiple stepwise logistic regression analysis showed that a history of hypertension and left atrial enlargement on two-dimensional echocardiography were significant independent risk factors for systemic embolism in patients with symptomatic nonvalvular paroxysmal atrial fibrillation.

Aged↗

PubMed1992

The interactive effects of dietary quality on the growth and attained size of young Mexican children.

Predictors of attained size at 30 mo and growth rate between 18 and 30 mo (eg, diet, maternal size, morbidity, age at weaning, and selected environmental factors) were investigated by using longitudinal data from 67 Mexican children aged 18-30 mo. These children were small because of growth stunting in early infancy. Between 18 and 30 mo they grew on average at the 50th percentile of National Center for Health Statistics references values for weight, and the 25th for length. Size at 30 mo and growth rates were unrelated to energy or protein intakes during the previous year, but positively related to consumption of animal-origin foods. Maternal weight predicted size and growth only for children with larger intakes of animal products. Individual rates of weight and length growth were uncorrelated on average, correlated negatively when animal-product intake was low, and positively only when more animal products were consumed. Integrated weight and length growth, and the influence of maternal size on growth, may be disrupted by poor dietary quality. Different children would be identified as malnourished depending on whether weight or length growth was measured.

Analysis of Variance↗

PubMed1992

[Multidisciplinary study of cerebrovascular accidents: I. Definition, design, and general results].

Cerebrovascular accidents (CVA) constitute a major cause of adult cardiac cardiovascular mortality in Chile. From July 87 to August 89 we prospectively studied 300 patients with CVA utilizing a multidisciplinary approach. Besides clinical evaluation this included brain CT scan (48 hrs), glucidic and lipid profile. Occlusive CVA were additionally studied with 2D-Echocardiogram, 24 hr Holter, Cerebral Angiography and/or carotid Duplex Echotomograph, and a second brain CT scan was performed within the first week. We found a 62.3% incidence of cerebral infarcts, 28.3% of cerebral hemorrhages and 9.3% of transient ischemic attacks. Cerebral infarcts were found to be cardiac related in 33.5% of cases, whereas 13.2% were lacunar, 4.4% were atherothrombotic and 14% had no precise etiology. Hypertension was associated to cerebral hemorrhages in 76% of cases, 26% of which were intracranial. At 2 months of follow-up 16.3% of patients were severely handicapped and mortality was 19.3%. We have confirmed that cerebral infarcts constitute the most common cause of CVA and most of them are cardiac related. Hypertension appears to be the most important cause of cerebral hemorrhage. A multidisciplinary approach to cerebrovascular accidents allowed a more precise diagnosis and contributed to implement appropriate therapeutic and preventive strategies. Proper identification of high risk patients could contribute to decrease the high incidence and mortality of CVA in our community.

Aged↗

PubMed1990

Effects of ketanserin on left ventricular hypertrophy in hypertensive patients.

Ketanserin, a serotonergic S2-receptor antagonist, was used in a prospective study in nine hypertensive patients with ECG criteria of left ventricular hypertrophy (LVH). Echocardiographic measurement with M mode was made after 1 month of placebo, and after 3, 6, and 12 months of ketanserin treatment as monotherapy at a mean dose of 31 mg bid. Ketanserin treatment decreased mean left ventricular mass by 9.3% at 3 months (not significant), by 15.3% at 6 months (p less than 0.008), and by 26.2% at 12 months (p less than 0.02), with a tendency towards improvement in left ventricular ejection fraction, which was not statistically significant. The study showed a sustained effect upon regression of LVH in hypertensives, with preservation of left ventricular function.

Adult↗

PubMed1989

Body weight, tick burden (Boophilus microplus), physiological parameters and reproductive efficiency of crossbred zebu cattle.

Body weight at calving, degree of tick load (Boophilus microplus), rectal temperature, respiratory frequency and heart rate were evaluated and correlated to reproductive efficiency in 63 F1 Brown Swiss x Nellore milked animals reared in the tropical region of Peru. Cows were bred by free natural service, and first ovulation was estimated by progesterone measurements. The physiological parameters were registered at morning milking (04.00 to 06.00) at an average air temperature of 22.4 +/- 0.9 degrees C. The intervals from parturition to first ovulation and conception were significantly affected when the body weight at calving was lower than 400 kg (p less than 0.01). The degree of tick burden, rectal temperature (38.4 +/- 0.2 degrees C, mean +/- s.e.), respiratory rate (25.2 +/- 0.3 breaths/min) and heart rate (66.7 +/- 0.4 beats/min) were not related to post-partum reproductive efficiency. The average intervals from parturition to first ovulation and to conception were 56.3 +/- 55.5 and 77.7 +/- 46.0 days mean +/- s.d.), respectively. The fertility rate was 85.7%. The results indicate the F1 cross to be well adapted to the given environment. It remains to be determined whether higher levels of temperate blood can be used without an accompanying decrease in reproductive performance.

Animals↗

PubMed1987

Prevalence and age at development of enamel hypoplasias in Mexican children.

Enamel hypoplasias, deficiencies in enamel thickness resulting from disturbances during the secretory phase of enamel development, are generally believed to result from nonspecific metabolic and nutritional disruptions. However, data are scare on the prevalence and chronological distributions. of hypoplasias in populations experiencing mild to moderate malnutrition. The purpose of this article is to present baseline data on the prevalences and chronological distributions of enamel hypoplasias, by sex and for all deciduous and permanent anterior teeth, in 300 5 to 15-year-old rural Mexican children. Identification of hypoplasias was aided by comparison to a published standard (Federation Dentaire Internationale: Int. Dent. J. 32(2):159-167, 1982). The location of defects, by transverse sixths of tooth crowns, was used to construct distributions of defects by age at development. One or more hypoplasias were detected in 46.7% (95% CI = 40.9-52.5%) of children. Among the unworn and completely erupted teeth, the highest prevalence of defects was found on the permanent maxillary central incisors (44.4% with one or more hypoplasias), followed by the permanent maxillary canine (28.0%) and the remaining permanent teeth (26.2 to 22.2%) Only 6.1% of the completely erupted and unworn deciduous teeth were hypoplastic. The prevalence of enamel defects on the permanent teeth was up to tenfold greater than that found in studies of less marginal populations that used the FDI method. The prevalence of defects in transverse zones suggests a peak frequency of hypoplasias during the second and third years for the permanent teeth, corresponding to the age at weaning in this group. In the deciduous teeth, a smaller peak occurs between 30 and 40 weeks post gestation. The frequency of defects after three years of age is slightly higher in females than males, suggesting a sex difference in access to critical resources.

Adolescent↗

PubMed1985