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Biomedical subjects

J Navarro

Publications and source records attributed to J Navarro.

At least 91 records · Page 5Linked to original sources
PubMed2000

Variational study of 3He droplets

We report variational calculations of energies of (3)He(N) droplets ( 20</=N</=40), using Aziz atom-atom interactions. The trial wave function has a simple structure, combining two- and three-body correlation functions coming from a translationally invariant configuration-interaction description, superimposed to a Jastrow-type correlated wave function with backflow. We find that the smallest bound drop has N = 35 atoms, and that for each N the minimum energy states have the highest spin values.

Journal Article↗
PubMed2000

French multicenter randomized double-blind placebo-controlled trial on nebulized amiloride in cystic fibrosis patients. The Amiloride-AFLM Collaborative Study Group.

The effect of amiloride, a sodium channel blocker, has been evaluated in a multicenter randomized double-blind placebo-controlled trial in cystic fibrosis patients more than 5-years-old (n = 137) whose forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV(1)), and forced mid-expiratory flow (FEF(25-75)) were not below 50%, 50%, and 30% of reference values, respectively. Patients were randomly allocated to two parallel groups. Sixty-four patients were chronically colonized with Pseudomonas aeruginosa; they received either amiloride or placebo as a nebulized solution three times daily for 6 months. Routine treatments were continued. Patients chronically colonized with Pseudomonas received nebulized colimycine twice a day for a month during the third and sixth months of treatment. Bronchopulmonary exacerbations were treated in the usual way. The effects of the amiloride treatment were assessed at the end of the 6-month treatment period. The effects on FVC and secondarily on FEV(1), FEF(25-75), the number of days on antibiotic therapy, the Shwachman score, a nutritional index (weight/height(2)), the change in sputum bacterial flora, and nocturnal cough were assessed. For the patients not chronically colonized with Pseudomonas, the effect of the treatment was also evaluated by counting chronic colonizations with pathogens appearing during the trial period. The present study failed to demonstrate any significant benefit of amiloride over placebo on FVC, FEV(1), and the other secondary endpoints in the studied population. Neither the chronically colonized, nor the noncolonized patients benefited. The confidence intervals of the differences between treatment groups indicated small differences that were most likely of no clinical significance. Complementary analyses taking into account the gender, the type of mutation, the subpopulations whose FVC and FEV(1) were below 80% of normal values at the beginning of the study, and also patients less than 10 years old, did not show any statistically or clinically significant improvements following amiloride therapy.

Administration, Inhalation↗
PubMed2000

Impact of stage III-IV endometriosis on recipients of sibling oocytes: matched case-control study.

OBJECTIVE: To evaluate the impact of severe endometriosis on IVF-ET outcome in women receiving oocytes from the-same donor. DESIGN: A matched case-control study. SETTING: Oocyte donation program at the Instituto Valenciano de Infertilidad. PATIENT(S): Fifty-eight recipients were included in a matched case-control study of IVF-ET in our oocyte donation program. Twenty-five patients were diagnosed by laparoscopy with stage III-IV endometriosis (group I), while the remaining 33 were free of the disease (group II). On the day of retrieval, oocytes from a single donor were donated to recipients from both groups. Some of the donors supplied oocytes for more than 2 patients. Recipients received steroid replacement therapy for endometrial preparation. INTERVENTION(S): Ovarian stimulation and oocyte retrieval in donors. Uterine embryo transfer (ET) in recipients after appropriate exogenous hormone replacement therapy (HRT). MAIN OUTCOME MEASURE(S): Pregnancy, implantation, miscarriage, and live birth rates. RESULT(S): The number of oocytes donated and fertilized, as well as the number of available and transferred embryos, was not statistically different between the two groups. Pregnancy, implantation, and miscarriage rates were not affected by stage III-IV endometriosis when compared with the control group. The live birth rate was 28.0% in the group with endometriosis and 27.2% in the control group. CONCLUSION(S): These results show that implantation is not affected by stage III-IV endometriosis. Given the contemporary methods of endometrial preparation for transfer of embryos derived from donor oocytes, any potential negative effect of severe endometriosis on the uterine environment is undetectable.

Abortion, Spontaneous↗
PubMed2000

Biochemical and ultrastructural alterations caused by newly synthesized 1,2,4-triazole[1,5a]pyrimidine derivatives against Phytomonas staheli (Trypanosomatidae).

Six compounds, all newly synthesized triazole-pyrimidine derivatives that proved inhibitory of in in vitro growth of epimastigotes in Trypanosoma cruzi and of promastigotes of Leishmania donovani and Phytomonas staheli, were studied to investigate their toxic effects. As a biological model, the plant trypanosome P. staheli, which causes sudden wilt in the oil palm and Hartrot in the coconut palm, was used. The six compounds markedly inhibited macromolecule synthesis (nucleic acids and proteins) by the parasite. The cells treated with these compounds present severe damage in their ultrastructure-intense 'vacuolization, and appearance of lysosomes as well as other residual bodies. The mitochondrial section appeared larger in size. with a swollen matrix. In addition, these compounds changed the excretion of end metabolites, primarily affecting ethanol and acetate excretion, possibly by directly influencing certain enzymes (alcohol dehydrogenase and acetate synthetase) or their synthesis. 2000 Elsevier Science Ltd.

Animals↗
PubMed2000

[Nutritional management of cystic fibrosis in children].

A major goal in the management of cystic fibrosis patients is to maintain a good nutritional status as it improves long-term survival. A link is clearly established between the degree of malnutrition and the severity of the disease. Clinical and biological follow-up, better knowledge of energy requirements, dietary counseling and nutritional intervention help to optimize the growth of these patients through childhood and adolescence.

Adolescent↗
PubMed2000

[Iodine nutrition in the infant. Committee on Nutrition of the French Society of Pediatrics].

Iodine is a trace element essential for the synthesis of thyroid hormones. It is present in the human body in minute amounts (15-20 mg in adults). The thyroid is very sensitive to iodine deficiency in newborns and infants because of its very low iodine content. Daily iodine requirements in humans vary from 40 micrograms in neonates to 150 micrograms in adults. Iodine deficiency represents the first cause of avoidable mental deficiency in developed countries; it has not yet disappeared in Europe, especially in the East, where it is responsible for a high prevalence of goiter. Iodine deficiency during pregnancy increases the risk of neonatal transient hypothyroidism, with a high recall rate in programs of systematic screening for congenital hypothyroidism. Data available in France suggest that screening for iodine deficiency should be performed during pregnancy, and that the minimal iodine concentration in formula milk should be increased to 10 micrograms/100 kcal for term infants and 20 micrograms/100 kcal for premature infants. Iodine deficiency is ideally prevented by the use of iodized salt. Because of the risk of iodine overexposure and secondary transient hypothyroidism, the use of iodinated antiseptics must be avoided in premature babies and neonates as well as in pregnant and lactating women. The fight against iodine deficiency, associated with oral stable preventive iodine administration, decreases sharply the risk of thyroid cancer in case of nuclear exposure, by diminishing thyroid uptake of iodine radioactive isotopes.

Adult↗
PubMed2000

Correlation between centromere and chromosome length in human male pronuclear chromosomes: ultrastructural analysis.

Ultrastructural and morphometric analyses of centromeric regions by scanning and transmission electron microscopy have been performed in chromosomes from male pronuclei obtained by heterologous fertilisation of hamster oocytes with human spermatozoa. In 1308 of 1323 chromosomes analysed, the primary constriction showed a defined biconcave constriction of variable length (0.56-1.34 microns) and constant width (0.64-0.7 micron). A positive correlation was observed between centromeric length and chromosome length. In some chromosomes, the primary constriction appears as decondensed regions of variable length (1.6-2.51 microns) composed of chromatin fibres with a minimum diameter of 30 nm.

Animals↗
PubMed2000

Effect of meal and intravenous erythromycin on manometric and electrogastrographic measurements of gastric motor and electrical activity.

Electrogastrography (EGG) measures, on the skin surface, the myoelectrical activity attributable to gastric smooth muscle cells. The physiological significance of signal amplitude and variation has not been clearly established. The increased signal amplitude after eating a meal may be related to increased contractile activity or to gastric distension. This study investigates the effect of increased gastric motor activity, unaccompanied by gastric distension, on the EGG recording and compares it to the effect of a meal. Nine children (3 months to 15 years old), were assessed by antroduodenal manometry for chronic intestinal pseudoobstruction (N = 5), chronic vomiting (N = 2), and abdominal distension (N = 2). Synchronized EGG recording was performed simultaneously. During the study, four children were given a meal and five were given intravenous erythromycin 3 mg/kg over 1 hr. The ratio of the antral motor index (MI = number of waves x sum of amplitudes) determined 1 hr before a meal (or erythromycin) to that determined 1 hr after a meal (or during intravenous erythromycin) was calculated. The ratio of the running total spectrum power of the electrical signal at the same times was also calculated. Antral MI increased after a meal [MI ratio (mean +/- SE) 5.33 +/- 2.2] and after intravenous erythromycin (MI ratio: 9.36 +/- 2.6). The amplitude of the electrical activity also increased after the meal [power ratio (mean +/- SE) 3.01 +/- 0.65] and after intravenous erythromycin (power ratio: 1.23 +/- 0.39), but the increase was greater after the meal (P < 0.05 vs intravenous erythromycin). No correlation was found between antral MI ratio and running total spectrum power ratio. In conclusion, the increased amplitude of the gastric electrical activity recorded by the EGG after a meal seems to be only partly due to the increase in antral motor activity. The increase in power is also related to gastric distension.

Adolescent↗
PubMed2000

Allergic bronchopulmonary aspergillosis in cystic fibrosis. A European epidemiological study. Epidemiologic Registry of Cystic Fibrosis.

Allergic bronchopulmonary aspergillosis (ABPA) is a disease resulting from a hypersensitivity response to Aspergillus fumigatus, although the pathogenesis of the disease is unknown and its prevalence in cystic fibrosis (CF) is still poorly defined. Data from the Epidemiologic Registry of Cystic Fibrosis (ERCF) on 12,447 CF patients gathered from 224 CF centres in nine European countries were analysed. The ERCF definition of ABPA diagnosis is a positive skin test and serum precipitins to A. fumigatus, together with serum immunoglobulin (Ig)E levels >1,000 U x mL(-1) and additional clinical or laboratory parameters. The overall prevalence of ABPA in the ERCF population was 7.8% (range: 2.1% in Sweden to 13.6% in Belgium). Prevalence was low <6 yrs of age but was almost constant approximately 10% thereafter. No sex differences were observed. ABPA affected 8.0% of patients with a deltaF508/deltaF508 genotype and 5-6% with deltaF508/G551D, deltaF508/G542X and deltaF508/N1303K genotypes. ABPA patients presented a lower forced expiratory volume in one second (FEV1) than those without ABPA at any age and the prevalence ranged from 6.6% in patients with FEV1 > or =20-12.9% in those with FEV1 <40%. ABPA was associated with higher rates of microbial colonization, pneumothorax and massive haemoptysis, and with higher IgG serum levels and poorer nutritional status. A mixed model regression analysis of lung function showed that FEVI decline during the follow-up period was not substantially different in ABPA patients compared with non-ABPA patients for any subgroups based on age or disease severity at enrollment. To conclude, allergic bronchopulmonary aspergillosis is a frequent complication in cystic fibrosis patients, particularly after the age of 6 yrs, and it is generally associated with a poorer clinical condition. However, any clear independent influence of allergic bronchopulmonary aspergillosis on the rate of lung function decline in the short term was not shown.

Adolescent↗
PubMed2000

Embryo reduction of multifetal pregnancies following assisted reproduction treatment: a modification of the transvaginal ultrasound-guided technique.

First-trimester transvaginal embryo reduction is an effective alternative for the management of multifetal pregnancy in assisted reproduction. We have modified the transvaginal technique by performing an intracardiac embryo puncture until asystolia is verified, without the injection of any substances. Any aspiration of embryo tissues or amniotic fluid was avoided. A total of 149 multifetal pregnancies was reduced to twins (n = 134) or singletons (n = 15) at early gestational age (7.8 +/- 0.8 weeks). Eleven cases (7.3%) of miscarriage, two cases (1.3%) of chorioamnionitis, and 17 cases (11.4%) of transient spotting were recorded as postoperative complications. Vanishing of one embryo occurred in four cases (3.0%) of those reduced to twins. The baby take-home rate was 89.5% for twins and 80.0% for singletons. Pregnancy outcome was analysed and compared with a control group of women with non-reduced multiple pregnancies. The birth weight of singleton pregnancies after reduction was lower (2929 +/- 160 versus 3291 +/- 422 g; P < 0.02). These studies show that early transvaginal intracardiac embryo puncture is an effective and safe technique.

Adult↗
PubMed2000

Analgesia for labor pain: a cost model.

BACKGROUND: Epidural analgesia and intravenous analgesia with opioids are two techniques for the relief of labor pain. The goal of this study was to develop a cost-identification model to quantify the costs (from society's perspective) of epidural analgesia compared with intravenous analgesia for labor pain. Because there is no valid method to assign a dollar value to differing levels of analgesia, the cost of each technique can be compared with the analgesic benefit (patient pain scores) of each technique. METHODS: The authors created a cost model for epidural and intravenous analgesia by reviewing the literature to determine the rates of associated clinical outcomes (benefit of each technique to produce analgesia) and complications (e.g., postdural puncture headache). The authors then analyzed data from their institution's cost-accounting system to determine the hospital cost for parturients admitted for delivery, estimated the cost of each complication, and performed a sensitivity analysis to evaluate the cost impact of changing key variables. A secondary analysis was performed assuming that the cost of nursing was fixed (did not change depending on the number of nursing interventions). RESULTS: If the cesarean section rate equals 20% for both intravenous and epidural analgesia, the additional expected cost per patient to society of epidural analgesia of labor pain ranges from $259 (assuming nursing costs in the labor and delivery suite do not vary with the number of nursing interventions) to $338 (assuming nursing costs do increase as the number of interventions increases) relative to the expected cost of intravenous analgesia for labor pain. This cost difference results from increased professional costs and complication costs associated with epidural analgesia. CONCLUSIONS: Epidural analgesia is more costly than intravenous analgesia. How the cost of the anesthesiologist and nursing care is calculated affects how much more costly epidural analgesia is relative to intravenous analgesia. Published studies have determined that epidural analgesia provides relief of labor pain superior to intravenous analgesia, quantified in one study as 40 mm better on a 100-mm scale during the first stage of labor and 29 mm better during the second stage of labor. Patients, physicians, and society need to weigh the value of improved pain relief from epidural analgesia versus the increased cost of epidural analgesia.

Adult↗
PubMed2000

Intestinal pseudo-obstruction and acute pandysautonomia associated with Epstein-Barr virus infection.

We report the association of neurological and intestinal disorders with the reactivation of Epstein-Barr virus (EBV) in a child. This previously healthy 13-yr-old boy presented with pharyngitis and acute abdominal ileus. Laparotomy excluded a mechanical obstruction. Postoperatively, he suffered from prolonged intestinal obstruction, pandysautonomia, and encephalomyelitis. Histological examination of the appendix and a rectal biopsy taken 3 months after the onset showed an absence of ganglion cells (appendix) and hypoganglionosis (rectum), with a mononucleate inflammatory infiltrate in close contact with the myenteric neural plexuses. EBV-PCR was positive in the blood and cerebrospinal fluid, and in situ hybridization with the Epstein-Barr virus encoded RNA probe showed positive cells throughout the appendix wall including the myenteric area, in a mesenteric lymph node, and in the gastric biopsies. EBV spontaneous lymphocytic proliferation was noted in the blood. The serology for EBV showed previous infection but anti-early antigen antibodies were present. No immunodeficiency was found. Neurological and GI recovery occurred after 6 months of parenteral nutrition and bethanechol. The omnipresence of EBV associated with the neurointestinal symptoms suggest that the virus was the causal agent. This is the first documented case of acquired hypoganglionnosis due to EBV reactivation.

Acute Disease↗
PubMed2000

In vitro pituitary and testicular effects of the leptin-related synthetic peptide leptin(116-130) amide involve actions both similar to and distinct from those of the native leptin molecule in the adult rat.

The obese gene (ob) product, leptin, has recently emerged as a key element in body weight homeostasis, neuroendocrine function and fertility. Identification of biologically active, readily synthesized fragments of the leptin molecule has drawn considerable attention, as they may provide a powerful tool for detailed characterization of the biological actions of leptin in different experimental settings. Recently, a fragment of mouse leptin protein comprising amino acids 116-130, termed leptin(116-130) amide, was shown to mimic the effects of the native molecule in terms of body weight gain and food intake, and to elicit LH and prolactin (PRL) secretion in vivo. As a continuation of our previous experimental work, the present study reports on the effects of leptin(116-130) amide on basal and stimulated testosterone secretion by adult rat testis in vitro. In addition, a comparison of the effects of human recombinant leptin and leptin(116-130) amide at the pituitary level on the patterns of LH, FSH, PRL and GH secretion is presented. As reported previously by our group, human recombinant leptin(10(-9)-10(-7)M) significantly inhibited both basal and human chorionic gonadotrophin (hCG)-stimulated testosterone secretion in vitro. Similarly, incubation of testicular tissue in the presence of increasing concentrations of leptin(116-130) amide (10(-9)-10(-5)M) resulted in a dose-dependent inhibition of basal and hCG-stimulated testosterone secretion; a reduction that was significant from a dose of 10(-7)M upwards. In addition, leptin(116-130) amide, at all doses tested (10(-9)-10(-5)M), significantly decreased LH and FSH secretion by incubated hemi-pituitaries from adult male rats. In contrast, in the same experimental protocol, recombinant leptin(10(-9)-10(-7)M) was ineffective in modulating LH and FSH release. Finally, neither recombinant leptin nor leptin(116-130) amide were able to change basal PRL and GH secretion in vitro. Our results confirm the ability of leptin, acting at the testicular level, to inhibit testosterone secretion, and map the effect to a domain of the leptin molecule that lies between amino acid residues 116 and 130. In addition, we provide evidence for a direct inhibitory action of leptin(116-130) amide on pituitary LH and FSH secretion, a phenomenon not observed for the native leptin molecule, in the adult male rat.

Animals↗
PubMed2000

Neonatal exposure to estrogen differentially alters estrogen receptor alpha and beta mRNA expression in rat testis during postnatal development.

The biological actions of estrogens on target cells are mediated by two nuclear receptors: the estrogen receptor (ER) alpha and the recently characterized ER beta. In the male rat, the physiological role of estrogens involves multiple actions, from masculinization of brain areas related to reproductive function and sexual behavior to regulation of testicular development and function. Paradoxically, however, administration of high doses of estrogen during the critical period of neonatal differentiation results in an array of defects in the reproductive axis that permanently disrupt male fertility. The focus of this study was to characterize the effects and mechanism(s) of action of neonatal estrogenization on the pattern of testicular ER alpha and beta gene expression during postnatal development. To this end, groups of male rats were treated at day 1 of age with estradiol benzoate (500 microg/rat), and testicular ER alpha and ER beta mRNA levels were assayed by semi-quantitative RT-PCR from the neonatal period until puberty (days 1-45 of age). Furthermore, the expression of androgen receptor (AR) mRNA was evaluated, given the partially overlapping pattern of tissue distribution of ER alpha, ER beta and AR messages in the developing rat testis. In addition, potential mechanisms for neonatal estrogen action were explored. Thus, to discriminate between direct effects and indirect actions through estrogen-induced suppression of serum gonadotropins, the effects of neonatal estrogenization were compared with those induced by blockade of gonadotropin secretion with a potent LHRH antagonist in the neonatal period. Our results indicate that neonatal exposure to estrogen differentially alters testicular expression of alpha and beta ER messages: ER alpha mRNA levels, as well as those of AR, were significantly decreased, whereas relative and total expression levels of ER beta mRNA increased during postnatal/prepubertal development after neonatal estrogen exposure, a phenomenon that was not mimicked by LHRH antagonist treatment. It is concluded that the effect of estrogen on the expression levels of ER alpha and beta mRNAs probably involves a direct action on the developing testis, and cannot be attributed to estrogen-induced suppression of gonadotropin secretion during the neonatal period.

Animals↗