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Biomedical subjects

A Figueroa

Publications and source records attributed to A Figueroa.

At least 19 recordsLinked to original sources
PubMed2005

Fetal growth in Peru: comparisons with international fetal size charts and implications for fetal growth assessment.

OBJECTIVES: To compare fetal biometry measurements obtained in a Peruvian population with reference fetal size charts obtained in Peruvian and non-Peruvian populations. METHODS: Fetal biometry measurements collected prospectively in 195 uncomplicated pregnancies were included in the presented analysis. At 20, 24, 28, 32, 36 and 38 weeks' gestation, fetal head circumference, abdominal circumference and femur diaphysis length were measured. Fetal biometry measurements were compared with fetal size charts obtained from another Peruvian and two non-Peruvian populations from North America and Europe. RESULTS: When compared with ultrasound-based reference fetal size charts obtained from North American and European populations, fetuses from the studied population appeared to grow more slowly with advancing gestational age. This trend was not observed when a Peruvian population, similar to the one studied here, was used as a reference. CONCLUSIONS: The results suggest that fetal growth in this Peruvian population may not be adequately assessed by using reference charts obtained from other populations and have implications for the use of growth standards in antenatal management.

Abdomen↗
PubMed2003

Effects of exercise training on bone remodeling, insulin-like growth factors, and bone mineral density in postmenopausal women with and without hormone replacement therapy.

The purpose of this study was to determine the effects of 12 months of weight bearing and resistance exercise on bone mineral density (BMD) and bone remodeling (bone formation and bone resorption) in 2 groups of postmenopausal women either with or without hormone replacement therapy (HRT). Secondary aims were to characterize the changes in insulin-like growth factors-1 and -2 (IGF-1 and -2) and IGF binding protein 3 (IGFBP3) in response to exercise training. Women who were 3-10 years postmenopausal (aged 40-65 years) were included in the study. Women in the HRT and no HRT groups were randomized into the exercise intervention, resulting in four groups: (1) women not taking HRT, not exercising; (2) those taking HRT, not exercising; (3) those exercising, not taking HRT; and (4) women exercising, taking HRT. The number of subjects per group after 1 year was 27, 21, 25, and 17, respectively. HRT increased BMD at most sites whereas the combination of exercise and HRT produced increases in BMD greater than either treatment alone. Exercise training alone resulted in modest site-specific increases in BMD. Bone remodeling was suppressed in the groups taking HRT regardless of exercise status. The bone remodeling response to exercise training in women not taking HRT was not significantly different from those not exercising. However, the direction of change suggests an elevation in bone remodeling in response to exercise training, a phenomenon usually associated with bone loss. No training-induced differences in IGF-1, IGF-2, IGF-l:IGF-2 (IGF-1 : IGF-2), and IGFBP3 were detected.

Adult↗
PubMed2001

Stirrer tank: an appropriate technology to immobilize the CB.Hep-1 monoclonal antibody for immunoaffinity purification.

The CB.Hep-1 monoclonal antibody was coupled to CNBr-activated Sepharose CL 4B at three different immobilization scales for purification of recombinant hepatitis B surface antigen. Standard laboratory apparatus to obtain immunosorbents of 1 l (scale I) and 3 l (scale II) as well as a stirrer tank to prepare 6 l immunosorbents (scale III) were used. The binding capacity at scale III was 2- and 1.5-fold higher with respect to the scales II and I, while a reduction in the ligand leakage of 5- and 2-folds was observed. Immunosorbents from scale II showed a significantly reduced adsorption, and an increased ligand leakage. Differences in the coupling efficiency were not observed. Antigen purity eluted from the immunosorbents was always above 85%.

Antibodies, Monoclonal↗
PubMed2001

Thyroid hormone regulates TAG-1 expression in the developing rat brain.

TAG-1 is a member of the immunoglobulin superfamily of cell adhesion molecules thought to play important roles in neuronal differentiation and the establishment of connectivity during brain development. Because these are processes also affected by hypothyroidism, we studied the effects of thyroid hormone deprivation and administration on TAG-1 expression in the developing rat brain. By in situ hybridization, immunohistochemistry and Western blotting we found that TAG-1 RNA and protein levels are upregulated in the hypothyroid brain. From embryonic day 20 to postnatal day (P) 15, elevated TAG-1 RNA was found in several areas including the cerebral cortex, hippocampus and olfactory bulb. In agreement with this, TAG-1 protein was overexpressed in the major fibre tracts arising from these structures, including the corpus callosum, anterior and hippocampal commissures and lateral olfactory tract. A similar overexpression of TAG-1 by hypothyroidism was detected in the cerebellum, but starting only at P15. In all cases, elevation of TAG-1 RNA and protein expression could be reversed by thyroid hormone treatment. These results show that the deregulation of TAG-1 might contribute to the alterations caused by the lack of thyroid hormone during brain development.

Aging↗
PubMed2001

Probe selection algorithms with applications in the analysis of microbial communities.

We propose two efficient heuristics for minimizing the number of oligonucleotide probes needed for analyzing populations of ribosomal RNA gene (rDNA) clones by hybridization experiments on DNA microarrays. Such analyses have applications in the study of microbial communities. Unlike in the classical SBH (sequencing by hybridization) procedure, where multiple probes are on a DNA chip, in our applications we perform a series of experiments, each one consisting of applying a single probe to a DNA microarray containing a large sample of rDNA sequences from the studied population. The overall cost of the analysis is thus roughly proportional to the number of experiments, underscoring the need for minimizing the number of probes. Our algorithms are based on two well-known optimization techniques, i.e. simulated annealing and Lagrangian relaxation, and our preliminary tests demonstrate that both algorithms are able to find satisfactory probe sets for real rDNA data.

Algorithms↗
PubMed2001

Changes in speech following unilateral mandibular distraction osteogenesis in patients with hemifacial microsomia.

OBJECTIVE: The purpose of this study was to describe changes in articulation, resonance, and velopharyngeal function following mandibular distraction osteogenesis. DESIGN: This is a descriptive, post hoc study comparing the performance of patients on measures of articulation, resonance, and velopharyngeal function before and after mandibular distraction. SETTING: The data were collected at a tertiary health care center located in Chicago. PATIENTS: The clinical data from preoperative and postoperative evaluations of seven mandibular distraction patients were used. OUTCOME MEASURES: The outcome measures were number of articulation errors, severity of hypernasality and audible nasal emission, and velopharyngeal orifice size as estimated using the pressure-flow technique. RESULTS: Immediately after distraction, 28% (2/7) experienced a temporary deterioration in articulation and 42% (3/7) experienced a deterioration in nasal resonance. But by the long-term follow-up evaluation, all had returned to their preoperative levels. Pressure-flow test results generally support the perceptual findings. CONCLUSIONS: Patients being considered for mandibular distraction surgery should receive preoperative and postoperative speech evaluations and be counseled about risks for changes in their speech following surgery.

Adolescent↗
PubMed2001

Changes in speech following maxillary distraction osteogenesis.

OBJECTIVE: The purpose of this study was to describe changes in articulation and velopharyngeal function following maxillary distraction osteogenesis. DESIGN: This is a descriptive, post hoc clinical report comparing the performance of patients before and after maxillary distraction. The independent variable was maxillary distraction while the dependent variables were resonance, articulation errors, and velopharyngeal function. SETTING: The data were collected at a tertiary health care center in Chicago. PATIENTS: The data from pre- and postoperative evaluations of 18 maxillary distraction patients were used. OUTCOME MEASURES: The outcome measures were severity of hypernasality and hyponasality, velopharyngeal orifice size as estimated using the pressure-flow technique, and number and type of articulation errors. RESULTS: At the long-term follow-up, 16.7% exhibited a significant increase in hypernasality. Seventy-five percent of patients with preoperative hyponasality experienced improved nasal resonance. Articulation improved in 67% of patients by the 1-year follow-up. CONCLUSIONS: In a predominately cleft palate population, the risk for velopharyngeal insufficiency following maxillary distraction is similar to the risk observed in Le Fort I maxillary advancement. Patients being considered for maxillary distraction surgery should receive pre- and postoperative speech evaluations and be counseled about risks for changes in their speech.

Adolescent↗
PubMed2001

[Unstable angina in octogenarians: is an invasive approach feasible and effective?].

BACKGROUND AND OBJECTIVE: Octogenarian patients with unstable angina are usually managed more conservatively despite having a worse prognosis. Studies of balloon angioplasty in the elderly have demonstrated a higher incidence of adverse events but the new advances (mainly stenting) have improved the results. We evaluated the efficacy and safety of an invasive approach in octogenarians with unstable angina. PATIENTS AND METHOD: From January 1996 to October 1999, 100 patients at least 80 years old with unstable angina were admitted to our unit and among these, 74 (74%) underwent percutaneous revascularization. We evaluated immediate results, in-hospital events and clinical follow-up. RESULTS: A total of 145 lesions were treated in 74 patients. The stent implantation rate was 79%. The success rate was 92%. Two patients died during hospitalization due to cardiac causes and 1 patient had a non-Q infarction. At follow-up, 24 +/- 12 months (range: 4 -50 months) 14 patients died (19.4%). New revascularization was performed in 10 patients (13.5%), 9 with PTCA and 1 with surgery. The survival rate free of death and infarction in the first year was 89.2%. At the end of follow-up 58 patients were alive (78.4%), 45 asymptomatic and 13 had stable angina, class I or II. CONCLUSIONS: The results of stent implantation in octogenarians were good with a 92% procedural success. Ninety-six percent of patients were free of death and infarction during hospitalization and 78.4% of the patients remained alive, most of them asymptomatic at the end of follow-up.

Age Factors↗
PubMed2001

[Blood concentrations of calcium and magnesium in women with severe pre-eclampsia].

Abnormalities in the calcium and magnesium metabolism may participate in the pathogenesis of preeclampsia. Serum levels of magnesium, calcium, sodium, potassium and chlorine were measured in 15 pregnant women with severe preeclampsia and 20 uncomplicated pregnant women. Serum sodium, potassium and chlorine concentrations were similar in both groups. Nevertheless, serum magnesium levels were significantly elevated in severe preeclamptic women relative to women with uncomplicated pregnancy. The serum calcium concentration and calcium/magnesium ratio were not differences in the preeclamptic and the healthy pregnant woman.

Adolescent↗
PubMed2000

Evaluation of direct stent implantation without predilatation by intravascular ultrasound.

The present study shows that direct stent implantation without predilatation in selected lesions provides angiographic and ultrasonographic results that could be comparable to those expected with conventional stenting. These results may even safely improve if a balloon-artery ratio of 1.1 to 1.2 is used in combination with implantation pressures of 12 to 16 atm.

Coronary Disease↗
PubMed2000

[Intravascular ultrasonographic evaluation of direct stents, implanted without predilatation. Comparison of results according to lesion types].

INTRODUCTION AND OBJECTIVES: Direct stenting is a safe and feasible technique in selected lesions yielding excellent angiographic results. However, there are no studies providing intravascular ultrasonographic examination after direct stenting. The aim of this study was to evaluate direct stent expansion with ultrasonography and to know whether there are differences in the results based on lesion types. METHODS: Patients with amenable lesions for direct stenting were enrolled; including patients with no occlusion, no calcification, no significant tortuosity or angulation, a length 15 mm and a reference lumen diameter 2.5 mm. Intravascular ultrasonography was performed after stent implantation. The ultrasonographic criteria for optimal expansion were: complete apposition and a minimal intrastent lumen area > 80% of the average reference luminal area and 90% of the distal reference lumen area. RESULTS: We included 40 patients (50 lesions). The final angiographic result was good in all the patients but in one case an additional stent was used due to dissection. The ultrasonographic examination did not show significant differences between type A and B lesions. Optimal expansion was achieved in 14/21 (66%) of type A lesions and 17/29 (58%) of type B lesions (p = 0.5). The balloon/artery ratio was the only factor significantly related to ultrasonographic results. When this ratio was 1.1-1.2 (25 cases), 76% of the stents were optimally expanded and when the ratio was < 1. 1 (25 cases) only in a 48% an optimal result was achieved (p < 0.05). CONCLUSIONS: Direct stenting in selected lesions provides ultrasonographic results comparable to those expected with conventional stenting and these results could be even improved if a balloon artery ratio 1.1-1.2 is used. Taking into consideration the selection criteria the differences observed between lesion types A and B are not significant.

Coronary Disease↗
PubMed1999

Adding zinc to prenatal iron and folate tablets improves fetal neurobehavioral development.

OBJECTIVE: Our objective was to examine whether improvement in maternal zinc status during pregnancy is positively associated with fetal neurobehavioral development in a Peruvian population. STUDY DESIGN: We electronically monitored, at 32 and 36 weeks' gestation, 55 fetuses whose mothers were randomly assigned to receive, during pregnancy, a daily supplement containing 60 mg iron and 250 microg folate, with or without 15 mg zinc. Fetal heart rate and movement patterns were quantified in 55 and 34 fetuses, respectively, as indexes of neurobehavioral development. RESULTS: Fetuses of mothers who received zinc supplementation showed fewer episodes of minimal fetal heart rate variability, increased fetal heart rate range, an increased number of accelerations, an increased number of movement bouts, an increased amount of time spent moving, and an increased number of large movements. Differences by supplementation type increased with gestational age and were statistically significant at 36 weeks' gestation (P <.05). CONCLUSION: Improving maternal zinc status through prenatal supplementation may improve fetal neurobehavioral development.

Adult↗
PubMed1999

Adding zinc to prenatal iron and folate supplements improves maternal and neonatal zinc status in a Peruvian population.

BACKGROUND: Maternal zinc deficiency during pregnancy may be widespread among women in developing countries, but few data are available on whether prenatal zinc supplementation improves maternal and neonatal zinc status. OBJECTIVE: We studied whether maternal zinc supplementation improved the zinc status of mothers and neonates participating in a supplementation trial in a shantytown in Lima, Peru. DESIGN: Beginning at gestation week 10-24, 1295 mothers were randomly assigned to receive prenatal supplements containing 60 mg Fe and 250 microg folate, with or without 15 mg Zn. Venous blood and urine samples were collected at enrollment, at gestation week 28-30, and at gestation week 37-38. At birth, a sample of cord vein blood was collected. We measured serum zinc concentrations in 538 women, urinary zinc concentrations in 521 women, and cord zinc concentrations in 252 neonates. RESULTS: At 28-30 and 37-38 wk, mothers receiving zinc supplements had higher serum zinc concentrations than mothers who did not receive zinc (8.8 +/- 1.9 compared with 8.4 +/- 1.5 micromol/L and 8.6 +/- 1.5 compared with 8.3 +/- 1.4 micromol/L, respectively). Urinary zinc concentrations were also higher in mothers who received supplemental zinc (P < 0.05). After adjustment for covariates and confounding factors, neonates of mothers receiving zinc supplements had higher cord zinc concentrations than neonates of mothers who did not receive zinc (12.7 +/- 2.3 compared with 12.1 +/- 2.1 micromol/L). Despite supplementation, maternal and neonatal zinc concentrations remained lower than values reported for well-nourished populations. CONCLUSION: Adding zinc to prenatal iron and folate tablets improved maternal and neonatal zinc status, but higher doses of zinc are likely needed to further improve maternal and neonatal zinc status in this population.

Adult↗
PubMed1999

Maternal zinc supplementation does not affect size at birth or pregnancy duration in Peru.

To estimate the effect of maternal zinc deficiency on pregnancy outcomes, we conducted a zinc supplementation trial in an urban shantytown in Lima, Peru, a population with habitual low zinc intakes. Beginning at 10-24 wk gestation, 1295 mothers were randomly assigned to receive prenatal supplements containing 60 mg iron and 250 (g folate, with or without 15 mg zinc. Women were followed up monthly during pregnancy. At birth, newborn weight was recorded, and crownheel length, head circumference and other circumferences and skinfold thicknesses were assessed on d 1. At delivery, 1016 remained in the study; duration of pregnancy was known for all women, and birth weight information was available for 957 newborns. No differences were noted in duration of pregnancy (39.4 +/- 2.2 vs. 39. 5 +/- 2.0 wk) or birth weight (3267 +/- 461 vs. 3300 +/- 498 g) by prenatal supplement type (iron + folate + zinc vs. iron + folate; P > 0.05), and there were no differences in the rates of preterm (<37 wk) or post-term (>42 wk) delivery, low birth weight (<2500 g) or high birth weight (>4000 g). Finally, there were no differences by prenatal supplement type in newborn head circumference, crownheel length, chest circumference, mid-upper arm circumference, calf circumference or skinfold thickness at any of three sites. Adjustment for covariates and confounding factors did not alter these results. Adding zinc to prenatal iron and folate tablets did not affect duration of pregnancy or size at birth in this population.

Adult↗
PubMed1998

An integrated approach to the quantification of aortic regurgitation by Doppler echocardiography.

BACKGROUND: Although different Doppler methods have been proposed for the quantification of aortic regurgitation, no study has prospectively compared these methods with each other and their correlation with angiography. The aim of this study was to prospectively analyze the usefulness of different Doppler echocardiography parameters by testing all such parameters in each patient. METHODS: Fifty-one patients with aortic regurgitation underwent 2-dimensional and Doppler echocardiographic studies and catheterization. The following Doppler indexes were analyzed and compared with aortography. Color Doppler: (1) jet color height/left ventricular outflow tract height in parasternal long-axis view, and (2) jet color area/left ventricular outflow tract area in short-axis view. Continuous Doppler: (3) regurgitant flow pressure half-time, (4) regurgitant flow time velocity integral (in centimeters), and (5) regurgitant flow time velocity integral (in centimeters)/diastolic period (in milliseconds). Pulsed Doppler in thoracic and abdominal aorta: (6) time velocity integral of diastolic reverse flow (in centimeters), (7) time velocity integral of systolic anterograde flow/integral of diastolic reverse flow, (8) (time velocity integral of diastolic reverse flow/diastolic period) x 100, and (9) diastolic reverse flow duration/diastolic period (as a percentage). We compared these parameters with severity of regurgitation measured by angiography and classified as mild, moderate, or severe. RESULTS: The most useful parameters were (1) jet color height/left ventricular outflow tract height (correctly classified 42 of 49 patients), (2) (time velocity integral of diastolic reverse flow/diastolic period) x 100 in the thoracic aorta (correctly classified 41 of 46 patients), and (3) (time velocity integral of diastolic reverse flow/diastolic period) x 100 in the abdominal aorta (correctly classified 42 of 49 patients). Sequential integration of these 3 parameters correctly classified 96% of patients (44 of 46 patients) and was achieved in 90% of cases. CONCLUSION: An integrated combination of several Doppler parameters can quickly and accurately classify the degree of aortic regurgitation as determined by angiography.

Aged↗
PubMed1998

A serous lined antireflux valve: in vivo fluorourodynamic evaluation of antireflux continence mechanism.

PURPOSE: We evaluate the fluoroscopic and urodynamic performance of a new serosal lined antireflux continence valve (T pouch valve) using an in vivo animal model. MATERIALS AND METHODS: Intestinal reservoirs were constructed using an in vivo pig model. Multiple serosal lined valves of varying diameters and tunnel lengths were evaluated in the acute (immediately after construction) and chronic (4 weeks postoperatively) settings. Video fluorourodynamic evaluations were performed to identify valve leak point pressures and optimal tunnel length-to-luminal diameter ratios. RESULTS: Four serosal lined valves tapered to a diameter of 18 and 30F in 1 and 2 cm. tunnels were evaluated. Immediately following construction of the valves no leakage was observed during reservoir filling (maximal pressure 50 cm. water) or external compression maneuvers to simulate a Valsalva maneuver (maximal intra-reservoir pressure 100 cm. water). Identical fluorourodynamic studies performed after a 4-week recuperation demonstrated leakage through the 30F, 1 cm. tunnel valve during reservoir filling (intra-reservoir pressure 19 cm. water). Increasing the tunnel length of the 30F system to 2 cm. (tunnel length-to-luminal diameter ratio 2:1) eliminated all evidence of valve leakage up to a maximal intra-reservoir pressure of 100 cm. water. CONCLUSIONS: These studies demonstrate the urodynamic characteristics of a new serosal lined valve. This easily constructed mechanism serves as a reliable antireflux (afferent) or continence (efferent) system.

Animals↗