Mechanical analysis of ovine and pediatric pulmonary artery for heart valve stent design.

Transcatheter heart valve replacement is an attractive and promising technique for congenital as well as acquired heart valve disease. In this procedure, the replacement valve is mounted in a stent that is expanded at the aimed valve position and fixated by clamping. However, for this technique to be appropriate for pediatric patients, the material properties of the host tissue need to be determined to design stents that can be optimized for this particular application. In this study we performed equibiaxial tensile tests on four adult ovine pulmonary artery walls and compared the outcomes with one pediatric pulmonary artery. Results show that the pediatric pulmonary artery was significantly thinner (1.06 ± 0.36 mm (mean ± SD)) than ovine tissue (2.85 ± 0.40 mm), considerably stiffer for strain values that exceed the physiological conditions (beyond 50% strain in the circumferential and 60% in the longitudinal direction), more anisotropic (with a significant difference in stiffness between the longitudinal and circumferential directions beyond 60% strain) and presented stronger non-linear stress-strain behavior at equivalent strains (beyond 26% strain) compared to ovine tissue. These discrepancies suggest that stents validated and optimized using the ovine pre-clinical model might not perform satisfactorily in pediatric patients. The material parameters derived from this study may be used to develop stent designs for both applications using computational models.

Fatty acids and neurodevelopment.

Knowledge of the importance of docosahexaenoic acid (DHA), arachidonic acid (AA), and long-chain polyunsaturated fatty acids (LCPUFAs) in neurodevelopment was originally obtained from animal studies. These fatty acids are rapidly accreted in brain during the first postnatal year in animal and human infants, and they are found in high concentrations in breast milk. Reports of enhanced intellectual development in breast-fed children, and reports linking LCPUFA deficiency with neurodevelopmental disorders have stressed the physiological importance of DHA in visual and neural systems. In addition to high concentrations of fatty acids in breast milk, they are also present in fish and algae oil and have recently been added to infant formulas. Esterified poplyunsaturated fatty acids act in cellular membranes, in signal transduction, in neurotransmission, and in the formation of lipid rafts. Nonesterified polyunsaturated fatty acids can modulate gene expression and ion channel activities, thus becoming neuroprotective agents. The conversion of linoleic acid and alpha-linolenic acid into ARA and DHA have led to randomized clinical trials that have studied whether infant formulas supplemented with DHA or both DHA and ARA would enhance visual and cognitive development. This review gives an overview of fatty acids and neurodevelopment, focusing on the findings from these studies.

Prenatal diagnosis for congenital adrenal hyperplasia in 532 pregnancies.

Congenital adrenal hyperplasia (CAH) refers to a family of monogenic inherited disorders of adrenal steroidogenesis most often caused by enzyme 21-hydroxylase deficiency (21-OHD). In the classic forms of CAH (simple virilizing and salt wasting), androgen excess causes external genital ambiguity in newborn females and progressive postnatal virilization in males and females. Prenatal treatment of CAH with dexamethasone has been successfully used for over a decade. This article serves as an update on 532 pregnancies prenatally diagnosed using amniocentesis or chorionic villus sampling between 1978 and 2001 at New York Presbyterian Hospital-Weill Medical College of Cornell University. Of the 532 pregnancies, 281 were prenatally treated for CAH due to the risk of 21-hydroxylase deficiency. Follow-up telephone interviews with mothers, genetic counselors, endocrinologists, pediatricians, and obstetricians were performed in all cases. Of the pregnancies evaluated, 116 babies were affected with classic 21-OHD. Of these, 61 were female, 49 of whom were treated prenatally with dexamethasone. Dexamethasone administered at or before 9 wk gestation (in proper doses) was effective in reducing virilization. There were no statistical differences in the symptoms during pregnancy between mothers treated with dexamethasone and those not treated with dexamethasone, except for weight gain, edema, and striae, which were greater in the treated group. No significant or enduring side-effects were noted in the fetuses, indicating that dexamethasone treatment is safe. Prenatally treated newborns did not differ in weight from untreated, unaffected newborns. Based on our experience, prenatal diagnosis and proper prenatal treatment of 21-OHD are effective in significantly reducing or eliminating virilization in the newborn female. This spares the affected female the consequences of genital ambiguity, genital surgery, and possible sex misassignment.

Long term outcome in adult males with classic congenital adrenal hyperplasia.

The effects of classic congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency on final height and fertility were evaluated in 30 affected males, aged 17-43 yr. The mean adult height of these patients was 165.64 +/- 8.4 cm (mean +/- SD), with a mean SD score of -1.65 +/- 1.2 cm. The difference between the mean final height SD score and mean target height SD score was -1.67 +/- 1.0 cm. All patients had short stature and did not reach their estimated target heights. There was no difference in height SD score between the salt-wasting and simple virilizing CAH patients. No correlation between the final height and degree of hormonal control or bone age advancement was observed. Of the 30 subjects, 18 had testicular sonograms. Abnormal sonogram findings of testicular adrenal rests were present in 9 patients (group 1), whereas sonogram without adrenal rests comprised the remaining 9 patients (group 2). In group 1, 8 of 9 patients and in group 2, 4 of 9 patients were salt-wasters; the remainder were simple virilizers. In group 1, 7 of 9 patients had semen analysis, and all were judged infertile. Of the 6 patients in group 2 who had semen analysis, 1 was azoospermic, and the remainder were normal. During optimal adrenal hormone suppression, gonadotropins at baseline and after GnRH stimulation were significantly higher in group 1 than in group 2, reflecting the loss of Leydig cell function to secrete testosterone. In conclusion, adult males affected with CAH due to 21-hydroxylase deficiency do not achieve the height predicted from parental heights. The presence of adrenal rests within the testes of adult males with classic CAH are more frequent in the salt-wasting form and are associated with a higher risk for infertility.

[Risk factors in osteoporosis: clinical and epidemiologic evidence]. / Factores de riesgo en la osteoporosis: evidencias clínicas y epidemiológicas.

The mechanisms of bone loss involve a predominance of osteodestructive cell activity over bone repair. Age and gender are the most significant biological risk factors; perimenopausal women constitute the most susceptible population group. Hormone-related phenomena, such as pregnancies and lactational performance, as well as heredity and ethnic origin, are also associated with osteoporosis. Alcohol and caffeine have been linked with progressive bone demineralization. A reduced body mass increases the probability of fractures. Dietary factors, such as adequate intakes of calcium, phosphates, and vitamin D, exert a protective action while the effect of fluoride and dietary fiber is still controversial. A constant physical activity promotes an appropriate development and maintenance of bone mass and architecture.

[Comparison of chlorthalidone and sustained-action nifedipine in the treatment of mild to moderate arterial hypertension]. / Comparación de la clortalidona y nifedipina retardada en el tratamiento de la hipertensión arterial leve-moderada.

The effectiveness and safety of sustained action nifedipine (NF) were compared to those of chlorthalidone (CL) in two groups of 35 and 37 patients with mild to moderate hypertension followed up for 4 months. There was a significant reduction in blood pressure (BP) after 15 days of therapy. The degree of control was acceptable with both drugs. A second drug was required in 20% patients of the NF group and in 30.8% of CL group. The therapeutic goal (BP less than 160/95) was achieved in 86.7% of patients in CL group and in 48.4% of those in NF group. We found 48.8% of dropouts in the NF group and none in CL group. There was a significant increase in blood glucose in CL group and a reduction of uric acid and an increase of HDL-cholesterol in NF group. Both drugs are useful to treat hypertension, although NF has the drawback of a high dropout rate and CL induces abnormalities in biochemical parameters.

[Family planning in primary care. One year of experience at a health center]. / Plantificación familiar en atención primaria. Un año de experiencia en un centro de salud.

We report in the present study the results of one year activity of the family planning (FP) clinic of the health center "Huerta de la Reina". We aimed at the characterization of the population on care and its response to the development of the FP program, as a possible basis for future policies. The consulting women is usually aged between 20 and 29 years, is a housewife, and her socioeconomic status is low. She has between one and three children; she had the first one when she was 20-24 years old, and had sexual intercourse for the first time before age 20. As regards birth control, she has usually not adopted any effective method during most of her fertile years; however, she has been taking oral contraceptives for 1-3 years and attends the FP clinic asking for method to secure no further pregnancies. In most cases she is free of medical risks for eventual pregnancies, and she is prescribed oral contraceptives. Women with the highest number of children are those of lower socioeconomic status (p less than 0.05). Likewise, there is a relationship between the educational level and the method used at the time of consultation (p less than 0.05).