Search PubMed⌕ Search

Biomedical subjects

J Villar

Publications and source records attributed to J Villar.

At least 91 records · Page 5Linked to original sources
PubMed1998

Nutritional interventions to prevent intrauterine growth retardation: evidence from randomized controlled trials.

This report summarizes the evidence from systematic reviews of randomized controlled trials on the effectiveness of nutritional interventions aimed at reducing intrauterine growth retardation (IUGR). There were 12 interventions including protein-energy, vitamin, mineral, and fish oil supplementation, as well as the prevention and treatment of anemia and hypertensive disorders. A primary concern is the limited data supporting the effectiveness of recommended nutritional interventions during pregnancy, some of which are widely used even in women without nutritional deficiencies. Overall, with the exception of perhaps balanced protein/energy supplementation (typical odds ratio: 0.77; 95 per cent confidence interval: 0.58 to 1.01), no effective nutritional interventions for reducing the risk of IUGR have been demonstrated. Other interventions, such as zinc, folate and magnesium supplementation during gestation, merit further research which should be conducted among populations at risk of IUGR, using larger sample sizes, and addressing coexisting factors limiting fetal growth. Appropriate combinations of interventions should be a priority for evaluation as it is unlikely that a single factor will reduce a multicausal outcome like IUGR that is so dependent on socioeconomic disparities.

Dietary Proteins↗
PubMed1997

Long-term effect of calcium supplementation during pregnancy on the blood pressure of offspring: follow up of a randomised controlled trial.

OBJECTIVE: To explore the long-term effect of calcium supplementation during pregnancy on the offspring's blood pressure during childhood. DESIGN: Follow up of a population enrolled in a double blind, randomised, placebo controlled trial. SETTING: Perinatal research unit, World Health Organisation's collaborative research centre. SUBJECTS: 591 children at a mean age of 7 years whose mothers were randomly assigned during pregnancy to receive 2 g/day of elemental calcium (n = 298) or placebo (n = 293). MAIN OUTCOME MEASURES: Mean blood pressure and rate of high blood pressure of children. RESULTS: Overall, systolic blood pressure was lower in the calcium group (mean difference -1.4 mm Hg; 95% confidence interval -3.2 to 0.5) than in the placebo group. The effect was found predominantly among children whose body mass index at assessment was above the median for this population (mean difference in systolic blood pressure -5.8 mm Hg (-9.8 mm Hg to -1.7 mm Hg) for children with an index > 17.5 and -3.2 mm Hg (-6.3 mm Hg to -0.1 mm Hg) for those with an index of > 15.7 to 17.5). The risk of high systolic blood pressure was also lower in the calcium group than in the placebo group (relative risk 0.59; 0.39 to 0.90) and particularly among children in the highest fourth of body mass index (0.43; 0.26 to 0.71). CONCLUSION: Calcium supplementation during pregnancy is associated with lower systolic blood pressure in the offspring, particularly among overweight children.

Blood Pressure↗
PubMed1997

[Clinical significance of Blastocystis hominis infection: epidemiologic study].

BACKGROUND: To evaluate the frequency of Blastocystis hominis parasitation and to ascertain its role as an intestinal a prospective study during 18 months pathogen has been carried out. SUBJECTS AND METHODS: The study included 2,039 patients, which were classified in three groups (asymptomatic [group A], with suspicion of parasitosis [group B], with diarrhoea [group C]). In all cases a coproparasitological study was performed. In the group C the presence of non-parasitic enteropathogens was also investigated. In patients with B. hominis in the absence of other pathogens clinical and epidemiological characteristics were evaluated. Also, its was determined the morphology and quantification of parasites. RESULTS: Parasites were identified in 26.2% of population. B. hominis was identified in 336 patients (16.5%). The frequency of parasitation was superior in adults (p < 0.0001), with a slight predominance in the female sex. The rate of asymptomatic carriers was 3.3%. In 21 patients B. hominis (group C) was observed in absence of other enteropathogens. Statistical significant association was found between B. hominis, in absence of other pathogens and the presence of clinical manifestations (p < 0.0001), the most common of which were diarrhoea and abdominal pain. We did not find a statistically significant association between the number of B. hominis present and stool characteristics. The vacuolar form was the predominant morphological type. The ameboid form was observed only in diarrhoeal stools. CONCLUSIONS: B. hominis is the most frequent parasite found in faecal parasitological investigation. In absence of other causes, B. hominis must be considered as a pathogen.

Adolescent↗
PubMed1997

[Hypertensive subpopulations as defined by their natriuretic response to ambulation].

BACKGROUND: The heterogeneity among patients with essential hypertension is known. We observed in an earlier study a large spread in the values of fractional excretion of sodium in a group of subjects with mild essential hypertension after ambulation, suggesting possible subgroups among them. We defined as the retainer (R) group that which presented a reabsorption index (RI = fractional excretion of sodium during supine/fractional excretion of sodium after ambulation) < 2.5 and the non-retainer (NR) group as that whose RI < 2.5. We analyzed at what level the reabsorption of Na was produced and the differences between the possible groups. PATIENTS AND METHODS: We studied 51 mild essential hypertensive patients, 22 men and 29 women, in two consecutive periods -recumbent, 90 minutes; ambulation, 90 minutes-. We calculated the clearance of creatinine and lithium, fractional proximal and distal reabsorption of Na, plasma renin activity (PRA), plasma aldosterone (ALDO) and elimination of PGE2 and kallikrein in the urine; the plasma catecholamines at the end of the recumbent position and after 10 minutes in the upright position. The study was taken after at least ten days without treatment and following a diet with free Na intake. RESULTS: We did not encounter significant differences between the retainer (n = 19) and non-retainer (32) group with regard to age, sex, body mass index or elimination of Na/24 h. The lower natriuresis in ambulation in the R group compared with the NR group is due to a higher fractional reabsorption of sodium, proximal (83.7 +/- 4.9% vs 79 +/- 5.2; p < 0.01) as well as distal (96.8 +/- 2 vs 95.3 +/- 2%; p < 0.05). The increment in the PRA was greater in the R group (1.3 +/- 1.4 vs 0.8 +/- 0.8; p < 0.05) after ambulation; in the R group showed a lower index -increment in ALDO/increment in PRA- in response to postural change although without significancy. We observed a lower elimination of PGE2 and kallikrein in the R group as compared with NR group (p < 0.05). We did not find differences with regard to plasma catecholamines. CONCLUSIONS: Ambulation allows to distinguish two groups of essential hypertensive patients according to natriuresis. The lower natriuresis in ambulation on the part of the R group could be due to the increase in PRA and therefore of the angiotensin II at the level of the proximal tubule, and to a lower activity of natriuretic hormones (PGE21 kallikrein) at the distal level.

Adult↗
PubMed1997

Intake of olive oil can modulate the transbilayer movement of human erythrocyte membrane cholesterol.

Transbilayer movement of erythrocyte membrane cholesterol is impaired in patients affected with essential hypertension. This is an inherited disorder, but environmental factors are also involved. Dietary fats might play a role in the prevention and/or treatment of such abnormality in the kinetic pools of membrane cholesterol. We tested this hypothesis by using a diet (in which 30% of the energy came from fat) rich in olive oil or in high-oleic sunflower oil (as natural sources of monounsaturated fatty acids, MUFAs) and determining their influence on the movement of cholesterol into the lipid bilayer of the erythrocyte membrane after a four-week period. We concluded that dietary olive oil is helpful in normalizing the impaired transbilayer movement of membrane cholesterol in erythrocytes of eight normocholesterolaemic and eight hypercholesterolaemic hypertensive patients. However, the effects cannot be attributed exclusively to the content of MUFAs (mainly oleic acid) in the diet, as high-oleic sunflower oil was unable to induce favourable changes.

Cholesterol↗
PubMed1997

Description of an improved method for Blastocystis hominis culture and axenization.

An improved method for Blastocystis hominis culture and axenization was developed in the present study. Stool samples were cultured in prereduced Boeck-Drbohlav NHI modified medium (with several modifications) supplemented with antibiotics (0.4% ampicillin, 0.1% streptomycin, 0.0006% amphotericin B). Axenization was performed by the combination of partial purification of B. hominis by Ficoll-metrizoic acid gradient and inoculation in fresh medium containing active antibiotics against remaining bacteria. A total of 25 strains were obtained by this procedure. The time required for axenization ranged between 3 and 5 weeks. The generation time of axenic strains ranged from 6.6 to 12.1 h (mean +/- SD 110.0 +/- 1.8 h) and the mean number of generations was 2.5 +/- 0.6 h per 24 h. The size of vacuolar and ameboid forms found in stools and in culture was similar. The special formulation of the medium used reduced the generation time and did not modify the cellular size as compared with fecal forms.

Animals↗
PubMed1997

Karyotypic diversity among Blastocystis hominis isolates.

Fifteen Blastocystis hominis strains, 13 axenic and 2 monoxenic, have been included in the present study. The chromosomal pattern was analyzed by the contour-clamped homogeneous electric-field (CHEF) system. The number of chromosomes detected ranged between 9 and 13, with sizes from 2200 kbp to 260 kbp. Eleven karyotypic profiles, with a common pattern constituted by 8 chromosomes of 2200, 1280, 890, 840, 700, 650, 540 and 260 kbp, were observed. The Jaccard index demonstrated that the similarity between isolates ranged from 0.5714 to 1. The different isolates were clustered in 3 karyotypes (A: 8 isolates; B: 6 isolates and C: 1 isolate). All isolates grouped in karyotype A presented a characteristic band of 730 kbp, whereas in the isolate of karyotype C the 810-kbp band was not observed.

Animals↗
PubMed1997

Factors affecting the comparability of meta-analyses and largest trials results in perinatology.

The objective of this report is to provide a new methodology for evaluating the performance of meta-analysis (MA) in corroborating results of large trials (LT) and to identify factors that could explain lack of similarity in the results. We used two criteria to judge the degree of similarity between a MA and the LT: (a) the ratio of the relative risk of the MA to the relative risk of the LT; and (b) the 95% confidence interval about this ratio. Furthermore, this degree of similarity was cross-tabulated with the presence or not of evidence of selective inclusion of positive studies (e.g., publication bias) as judged from "funnel plots" and statistical indicators. Depending on which of our two criteria was used, we found that between 20% and 53% of the 30 MAs studied have high or very high degree of similarity with the LT. We also found strong evidence that factors influencing asymmetrical funnel plots of MA, such as publication bias, may play an important role in this degree of similarity. There was a sizeable proportion of meta-analyses that did not agree with large trial results. We recommend that funnel plots be used as a tool for identifying which MAs can mislead. However, the statistical indicators at hand are unlikely to be of use in many area of medicine considering the regrettably small number of randomized controlled trials per topic available.

Bias↗
PubMed1997

Effectiveness of interventions to prevent or treat impaired fetal growth.

This is an overview of 126 randomized controlled trials (RCTs) evaluating 36 prenatal interventions to prevent or treat impaired fetal growth (IFG). Results are based on systematic reviews including the meta-analyses of these RCTs. Most of the prenatal interventions do not show any significant effects on short-term perinatal outcomes. There are, however, a few interventions likely to be beneficial: smoking cessation, antimalarial chemoprophylaxis in primigravidae, and balanced protein/energy supplementation. Others merit further research: zinc, folate, and magnesium supplementation during gestation. Appropriate combinations of interventions should be a priority for evaluation because it is unlikely that a single intervention will reduce a multicausal outcome like IFG that is so dependent on socioeconomic disparities. Of concern is the discrepancy between the importance given in the epidemiological and clinical literature to the problem of IFG and the methodological quality and sample size of the RCTs conducted for the evaluation of preventive or treatment modalities.

Fetal Growth Retardation↗
PubMed1997

Scientific basis for the content of routine antenatal care. I. Philosophy, recent studies, and power to eliminate or alleviate adverse maternal outcomes.

BACKGROUND: Scope and content of antenatal care programs are ritualistic rather than evidence-based. We wanted to identify elements of antenatal care which are of proven benefit in preventing or ameliorating specific adverse outcomes in the mother: bleeding, anemia, preeclampsia, sepsis and genito-urinary infection and obstructed labor. METHODS: Review of recent literature, especially randomized controlled trials. RESULTS AND CONCLUSIONS: Recent trials indicate that fewer routine visits for low-risk women do not put pregnancies at increased risk but may lessen patient satisfaction. Bleeding in pregnancy has many causes, none of which can be eliminated through antenatal care. Risk factors can be identified by history-taking. Counselling and advice on what to do is the best option. Anemia in pregnancy is common, especially in developing countries. Routine iron supplementation is not necessary in well-nourished populations, but iron and folate should be provided for every pregnant woman in areas of high anemia prevalence; based on circumstantial evidence. Hemoglobin (Hb) determination as a routine test is more important late (around week 30) than early in pregnancy: high Hb is a danger signal. It is uncertain whether early detection of pre-eclampsia will reduce the incidence of eclampsia. Recent trials do not support routine aspirin to prevent pre-eclampsia among low risk women, nor is there evidence that anti-hypertensive treatment of mild pre-eclampsia will prevent more severe disease, but improved detection and care may still lead to better outcome. As to infections, urine culture and dipstick for leucocyte esterase and nitrite with subsequent treatment of positive cases will reduce the risk of pyelonephritis and appears to be cost-effective. Serological screening and treatment of syphilis is inexpensive and cost-effective. Obstructed labor can be anticipated in multiparas based on obstetrical history. Hospital delivery should be secured. Height of nulliparas should be recorded where hospital birth is not routine and a discriminatory level for hospital delivery decided locally. External version of breech lie does reduce the incidence of breech births and cesarean delivery.

Developed Countries↗
PubMed1997

Scientific basis for the content of routine antenatal care. II. Power to eliminate or alleviate adverse newborn outcomes; some special conditions and examinations.

BACKGROUND: There is uncertainty concerning antenatal care as a tool to eliminate or alleviate adverse outcomes in the newborn. We identified congenital conditions, intrauterine infections, intrauterine growth retardation, preterm birth and some specific infectious diseases in the mother with a view to prophylactic and other interventions. The value of some special diagnostic tools is also under discussion. METHODS: Review of recent literature, especially randomized controlled trials and systematic reviews. RESULTS AND CONCLUSIONS: Genetic abnormalities cannot be prevented after conception, but many of them, and a number of acquired conditions, can be discovered by ultrasonographic and biochemical diagnostics. The advisability of screening must be determined locally for each condition, based on prevalence, treatment options and the legal requirements for abortion. Smoking, excessive alcohol intake, and severe undernutrition cause fetal growth retardation. Interventions to reduce maternal smoking have had limited success. Protein-energy supplementation only modestly affects birthweight. Routine measurement of uterine height is a good predictor of severe growth retardation and in rural settings of perinatal death. Preterm birth has been linked to ascending infection and subsequent rupture of the membranes. Attempts to eradicate local infections have shown some benefit but results are not convincing yet. Cervical cerclage and betamimetic drugs have little, if any, effect. Claims for reduction of physical strain (standing > 5 hours) at work should be supported. Tuberculosis in the mother should be discovered and treated. Malaria prophylaxis during pregnancy will protect the mother and possibly benefit the fetus. Adequate tetanus immunization of all mothers is a high priority intervention in developing countries. In HIV-positive mothers, Zidovudine ante- and perinatally will lower perinatal HIV-transmission significantly. Risk scoring may help identify some women for referral to higher level of care. Routine ultrasonography does not improve the outcome of pregnancy in terms of live births and morbidity, but may influence mortality through discovery and abortion of fetuses with major malformations. One vaginal examination during pregnancy is recommended but no repeat procedure unless medically indicated.

Evidence-Based Medicine↗
PubMed1997

[Total intravenous anesthesia with propofol in orthotopic liver transplantation in swine].

OBJECTIVE: To study the use of total intravenous anesthesia with propofol as an anesthetic model for orthotopic liver transplantation (OLT) in pigs. ANIMALS AND METHOD: Fifteen OLT were performed in pigs using portacava-jugular veno-venous shunt with an injector pump. Anesthesia was maintained by perfusion of 10 mg/kg/h propofol. Hemodynamic and biochemical measurements were recorded at the following times: AO, baseline; AI, five minutes before removal of the liver; B1, five minutes later but before starting the bypass injector pump; B2, five minutes after starting the injector pump; B3, five minutes before reperfusion; C1, five minutes after starting reperfusion, and C2, after aortic declamping. RESULTS: No cases of malignant hyperthermia appeared. When the liver was removed cardiac output decreased (p < 0.01), as did mean arterial pressure (p < 0.01), mixed venous saturation (p < 0.05), pulmonary capillary pressure and temperature (p < 0.05). Pulmonary vascular resistances increased (p < 0.05). CONCLUSIONS: The use of total intravenous anesthesia with propofol is a satisfactory experimental anesthetic model for OLT in pigs, and it prevents the possible appearance of malignant hyperthermia.

Anesthesia, General↗
PubMed1996

Cholesteryl ester transfer activity in liver disease and cholestasis, and its relation with fatty acid composition of lipoprotein lipids.

Liver disease is accompanied by major qualitative and quantitative disturbances in plasma lipoprotein metabolism, the extent and intensity of which depend on the degree of parenchymal damage, cholestasis, or both. The main objective of this study was to determine the cholesteryl ester transfer CETP activity and its association with the lipoprotein neutral lipid composition in patients with either liver cirrhosis or cholestasis, as compared to normal controls. Lipoproteins were isolated by ultracentrifugation, lipids and apolipoproteins were measured by conventional methods, and the fatty acid composition was established by gas chromatography; CETP activity in lipoprotein-deficient plasma was measured by determining the transfer of [3H]cholesteryl esters from HDL to VLDL. Lipoprotein lipase and hepatic lipase activities were measured in post-heparin plasma by radiochemical methods. In patients with liver cirrhosis, low levels of VLDL, HDL, apo B, and Lp(a) were observed, as well as a change in the composition of HDL particles, with increases in the relative proportion of triglyceride and free cholesterol. Respectively, the last two changes could be attributed in part to the low hepatic lipase activity observed in this study, and to the low lecithin:cholesterol acyltransferase activity previously observed by others. In patients with cholestasis, a moderate hyperlipidemia due to the elevation of LDL was found. In contrast, HDL and apo A-I levels were very low reflecting a low number of HDL particles, which also had altered compositions with increases in the triglyceride and free cholesterol contents relative to apo A-I and esterified cholesterol, respectively. As regards the fatty acid composition of lipoprotein lipids, the two groups of patients showed, in general, a lower proportion of linoleic acid and a compensating higher proportion of oleic acid as compared to the controls, changes that were observed in both cholesteryl esters and triglycerides. In contrast, the proportions of oleic and palmitoleic acids in phospholipids were increased, whereas that of stearic acid was decreased in patients as compared to controls. In patients with liver cirrhosis, as well as in controls, no changes were observed in the fatty acid compositions of cholesteryl ester, triglycerides, or phospholipids among the different lipoproteins, which probably reflects the equilibration reached by the action of CETP. In patients with cholestasis, no differences were observed in fatty acid composition among the lipoprotein phospholipids but, interestingly, cholesteryl esters from VLDL had a significantly lower linoleic acid content than those from HDL, whereas triglycerides from VLDL had significantly higher oleic acid and lower linoleic acid contents than those from HDL. This distinct fatty acid composition of the neutral lipids between lipoproteins was associated with a significant decrease (25%) in the cholesteryl ester transfer activity in patients with cholestasis. We suggest that fat malabsorption due to the biliary defect may induce a decrease in cholesteryl ester transfer protein synthesis or section, which in turn would slow the equilibration of the neutral lipids among plasma lipoproteins.

Adult↗
PubMed1996

The Latin American trial of psychosocial support during pregnancy: effects on mother's wellbeing and satisfaction. Latin American Network For Perinatal and Reproductive Research (LANPER).

A randomized controlled trial including 2235 women at high risk of low birthweight was conducted in four Latin American institutions. The objective of this trial was to evaluate a psychosocial support intervention during pregnancy aimed at improving perinatal health and mothers' psychosocial conditions. The core of the intervention was four to six home visits where emotional support, counseling and strengthening of the woman's social network was provided. Outcomes were measured at 36 weeks of pregnancy, post-partum and 40 days after delivery. The intervention was not successful in either altering women's perception of social support and satisfaction with the reproductive experience, as well as maternal and newborn's health care. It is concluded that although high levels of psychosocial distress during pregnancy may play an independent role in determining adverse pregnancy outcomes, this adverse effect does not appear to be ameliorated by psychosocial interventions conducted only during pregnancy, particularly those of a magnitude that can be realistically implemented (in content and frequency) at public care services in most developing countries.

Adolescent↗