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Biomedical subjects

M Valcarcel

Publications and source records attributed to M Valcarcel.

15 recordsLinked to original sources
PubMed1997

Effect of prenatal T4 treatment in neonatal morbidity: preliminary findings.

We report our experience with the use of intra-amniotic thyroxine to accelerate fetal maturation in preterm delivered infants. One hundred and fourteen infants who had received 500 micrograms of thyroxine weekly prenatally until an L/S ratio greater or equal to 2.0 was achieved, were compared to 113 premature infants who had not been given thyroxine or steroids prenatally. After stratification by weight, the relative incidence of respiratory distress syndrome (RDS), patent ductus arteriosus (PDA), necrotizing enterocolitis (NEC) and intraventricular hemorrhage (IVH) were compared. A decrease in the incidence of RDS was observed in the infants with birth weight between 1000 and 1500 g who had received more than one dose of intra-amniotic thyroxine. No difference in the incidence of RDS was observed in infants with birth weight of less than 1000 g or over 1500 g. One dose of thyroxine had no effect in decreasing the incidence of RDS, PDA, NEC, and IVH in any of the groups. We conclude intra-amniotic thyroxine seems to decreases the incidence of RDS in very low birth weight infants.

Amnion↗
PubMed1996

An automated preconcentration-derivatization system for the determination of cocaine and its metabolites in urine and illicit cocaine samples by gas chromatography/mass spectrometry.

Although gas chromatography/mass spectrometry (GC/MS) is the most powerful technique for analysing cocaine and its hydrolysis products (benzoylecgonine, ecgonine methyl ester and ecgonine) in urine, the sample pretreatment required is rather laborious and involves a large number of steps. This paper reports a continuous method for the separation (based on the retention properties of cocaine and its major metabolites on a reversed phase C18 column), preconcentration (evaporation under nitrogen) and derivatization (collection of the residue in a few microlitres of derivatizing reagent) of cocaine and its metabolites in urine samples for subsequent analysis by GC/MS. Calibration graphs are linear from 5 to 3000 ng/mL; the detection limits are 1 ng/mL (cocaine and ecgonine methyl ester), 20 ng/mL (benzoylecgonine) and 200 ng/mL (ecgonine). The method was applied to illicit cocaine samples and to urine from a drug addict.

Autoanalysis↗
PubMed1996

Precipitation flow injection immunoassay for human immunoglobulin G.

The development of a precipitation flow injection immunoassay is described. This approach is based on the immunoprecipitin reaction, whereby the precipitate formed by binding of the sample antigen (HIgG) to fluorescein-labelled antibodies is retained on a filter built in on-line in a flow-injection system. After dissolving the precipitate with sodium hydroxide solution the liberation of fluorescein-labelled antibodies results in a fluorescence signal that is directly proportional to the concentration of HIgG. The instrumental set-up is very simple and fully automated. One assay cycle takes about 10 min. The RSD ranged between 1 and 3%, depending on concentration. The detection limit was about 140 fmol. The recovery from spiked serum samples was between 96 and 102%.

Automation↗
PubMed1989

Comparison of different flow injection approaches to the automatic determination of enzymatic activity.

Three configurations based on the principles behind flow injection analysis (FIA) are proposed for the automatic determination of enzymatic activity. The proposed approaches are normal, stopped-flow and open-closed FIA. The comparative study of the methods developed from these approaches allows the establishment of the scope of the application of each, with inherent advantages and disadvantages.

Enzymes↗
PubMed1989

Development of a statistical model for predicting the ethanol content of blood from measurements on saliva or breath samples.

Blood, saliva and breath samples from a population of males and females subjected to the intake of preselected amounts of ethanol, whilst in different physical conditions (at rest, after physical exertion, on an empty stomach and after eating), were analysed by automatic methods employing immobilized (blood) or dissolved (saliva) enzymes and a breathanalyser. Treatment of the results obtained enabled the development of a statistical model for prediction of the ethanol concentration in blood at a given time from the ethanol concentration in saliva or breath obtained at a later time.

Adult↗
PubMed1986

Effects of atypical patterns of fetal growth on newborn (NBAS) behavior.

Newborn infants who showed anthropometric signs of atypical patterns of fetal growth were compared with infants of appropriate growth on the Neonatal Behavioral Assessment Scale (NBAS) and on recently developed supplementary items. The sample consisted of lower-socioeconomic-status families in San Juan, Puerto Rico, and included teenage and older mothers. Infants with atypical patterns of fetal growth showed lower scores than did infants of appropriate growth on the NBAS orientation, motor, and reflex clusters and on 15 of the 18 supplementary scores. Gestational age was covaried and showed independent effects on 6 items. Differential effects on measures of state and autonomic function were also found when the effects of the ponderal index were held constant. The results suggested that neonatal behavior is related to multiple indices of fetal growth patterns that may indicate early versus late nutritional insult. Supplementary NBAS items do not improve the discriminability of the NBAS but may help explain the basis for observed group differences.

Adolescent↗
PubMed1978

Early mother--infant interaction and somatic growth.

This study tests the proposition that selected behaviors of both mother and infant during feeding are predictors of weight gain during the 1st mth of life. 40 normal mother--neonate pairs were studied, and the target behaviors were examined using an adaptation of the techniques developed by Brown and Bakeman [18]. Aggregate scores of 4 specific maternal and infant behaviors accounted for over 32% of the variance in total weight gain. These findings indicate that the availability of nutrients is not, in itself, a sufficient condition to meet the infant's nutritional needs. Implicit in these findings are the possibilities that infants at risk of failure-to-thrive can be identified, and measures to prevent this syndrome can be introduced.

Anesthesia, Obstetrical↗