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A Arnaiz

Publications and source records attributed to A Arnaiz.

15 recordsLinked to original sources
PubMed2001

Development of a time-cycled volume-controlled pressure-limited respirator and lung mechanics system for total liquid ventilation.

Total liquid ventilation can support gas exchange in animal models of lung injury. Clinical application awaits further technical improvements and performance verification. Our aim was to develop a liquid ventilator, able to deliver accurate tidal volumes, and a computerized system for measuring lung mechanics. The computer-assisted, piston-driven respirator controlled ventilatory parameters that were displayed and modified on a real-time basis. Pressure and temperature transducers along with a lineal displacement controller provided the necessary signals to calculate lung mechanics. Ten newborn lambs (<6 days old) with respiratory failure induced by lung lavage, were monitored using the system. Electromechanical, hydraulic, and data acquisition/analysis components of the ventilator were developed and tested in animals with respiratory failure. All pulmonary signals were collected synchronized in time, displayed in real-time, and archived on digital media. The total mean error (due to transducers, analog-to-digital conversion, amplifiers, etc.) was less than 5% compared with calibrated signals. Components (tubing, pistons, etc.) in contact with exchange fluids were developed so that they could be readily switched, a feature that will be important in clinical settings. Improvements in gas exchange and lung mechanics were observed during liquid ventilation, without impairment of cardiovascular profiles. The total liquid ventilator maintained accurate control of tidal volumes and the sequencing of inspiration/expiration. The computerized system demonstrated its ability to monitor in vivo lung mechanics, providing valuable data for early decision making.

Analysis of Variance↗
PubMed2000

Prenatal dexamethasone rescues heart hypoplasia in fetal rats with congenital diaphragmatic hernia.

BACKGROUND/PURPOSE: Patients and rats with congenital diaphragmatic hernia (CDH) have lung and heart hypoplasia. Prenatal steroids improve lung hypoplasia in CDH rats. The current study tests the hypothesis that prenatal dexamethasone could rescue heart hypoplasia in rats with CDH. METHODS: Timed pregnant rats received intragastrically either 100 mg nitrofen or oil on day 9.5, and other animals had the same treatment with, in addition, either 0.25 mg/kg dexamethasone intraperitoneally or no treatment on days 19 and 20. Fetuses were recovered on day 21, and heart weight to body weight ratios, heart DNA, protein, and glycogen were measured in fresh specimens. Left-to-right ventricular diameter and aortic-to-pulmonary diameter ratios were measured after formalin fixation. RESULTS: Wet heart weight to body weight, left-to-right ventricular diameter, and aortic-to-pulmonary root diameter ratios, which were lower in fetuses exposed only to nitrofen than in their oil controls, were similar in those exposed to nitrofen plus dexamethasone than in their corresponding oil plus dexamethasone controls. Total heart DNA, which was decreased in fetuses exposed to nitrofen with CDH in comparison with their controls, was increased in those receiving nitrofen and dexamethasone in comparison with theirs. Protein to DNA ratio was decreased in all rats with CDH irrespective of their exposure or not to dexamethasone. Glycogen to DNA ratio was higher in all dexamethasone-treated fetuses than in those without this treatment. No gross histologic differences were seen among groups. CONCLUSIONS: Heart hypoplasia in rats with CDH is in part rescued by prenatal dexamethasone treatment as expressed by increased number of smaller myocytes with higher glycogen content. Prenatal steroids could modify heart involvement in human fetuses with CDH as well.

Animals↗
PubMed1999

Heart hypoplasia in experimental congenital diaphragmatic hernia.

BACKGROUND/PURPOSE: Heart hypoplasia is associated with congenital diaphragmatic hernia (CDH) and decisively influences survival rate. This study examines whether nitrofen-exposed fetal rats have heart hypoplasia. METHODS: Pregnant rats received either 100 mg nitrofen or vehicle on gestational day 9.5. The hearts recovered near full term were either formalin fixed for anatomic studies or snap-frozen for biochemical studies. Heart weight, ventricular chamber diameters and aortic-to-pulmonary root diameter ratios were measured in fixed hearts. Protein and DNA were determined in frozen hearts. Analysis of variance (ANOVA) and correlation-regression studies were used for statistical assessment. RESULTS: All control fetuses were normal, whereas 61% of those exposed to nitrofen had CDH. Cardiovascular malformations were found in 73% of CDH and in 50% of non-CDH animals. Wet and fixed heart weights in percent of fetal weight, left-to-right ventricular diameter ratio, and aortic-to-pulmonary root diameter ratio were significantly decreased in fetuses with CDH in comparison with controls. Only wet heart was significantly decreased in nitrofen-treated fetuses without CDH, although all other variables showed a trend in the same direction. Protein to DNA ratios were similar in the three groups. The structure of the myocytes was histologically similar in all groups. CONCLUSIONS: The spectrum of lesions in the nitrofen model of CDH encompasses heart hypoplasia, further validating its use for research on this condition. Heart hypoplasia is related to cardiopulmonary compression, but its presence in treated animals without CDH demonstrates that the teratogen itself participate directly in its pathogenesis, and this finding invites further research on this line.

Analysis of Variance↗
PubMed1998

Comparison of rapid bolus instillation with simplified slow administration of surfactant in lung lavaged rats.

The aim of this study was to compare the effects of modified porcine surfactant (Curosurf) given either by a simplified slow delivery technique or by the standard bolus method, on pulmonary gas exchange, lung mechanics, and surfactant distribution in rats with respiratory failure produced by lung lavage. Twelve rats with respiratory failure induced by lung lavage received 200 mg x kg(-1) body weight (b.w.) of tagged porcine surfactant, either by the standard bolus delivery technique or by a simplified 1-min intratracheal infusion method, not requiring interruption of mechanical ventilation. Cardiovascular parameters, arterial blood gases, and pulmonary mechanics were measured repeatedly. Surfactant distribution was also measured by dye-tagged microbead spheres. After surfactant administration, there were no overall major differences between groups in mean heart rate, blood pressure, arterial blood gases, dynamic lung compliance, respiratory system resistance, and pulmonary distribution of exogenous surfactant. However, after 180 min pulmonary gas exchange was better and compliance higher in the bolus than the 1-min infusion group. A transient decrease in blood pressure and heart rate was observed in the bolus group; this side effect was not seen in animals treated with the simplified 1-min infusion method. We conclude that in rats subjected to lung lavage, the infusion of porcine surfactant by a simplified 1-min procedure produced similar short-term effects compared to the same dose of surfactant given by the bolus method. We speculate that tracheal bolus dosing is highly effective and might be the preferable delivery method for porcine surfactant. Dosing by the simplified method described appears less effective, but since no significant differences were observed, and since it produced less acute adverse effects, it could be used when clinical circumstances preclude rapid delivery.

Animals↗
PubMed1997

Thyroid hormones in the pathogenesis of lung hypoplasia and immaturity induced in fetal rats by prenatal exposure to nitrofen.

BACKGROUND/PURPOSE: Nitrofen is believed to act on prenatally exposed fetuses by changing maternal or fetal thyroid hormone physiology. The aim of this study was to determine whether the amounts of circulating and lung tissue T3 and T4 are decreased in rat fetuses with nitrofen-induced pulmonary hypoplasia and diaphragmatic hernia. METHODS: Timed-pregnant rats were given 100 mg of nitrofen in oil on gestational day 9.5, and their fetuses were recovered on the 21st day. Lung weight to body weight ratio was determined. Hormonal studies consisted in measurement of plasma T3, T4, and TSH, and of T3, T4, and DNA in lung tissue. Suitable groups of control fetuses prenatally exposed to oil were used for comparison. RESULTS: The lungs of nitrofen-treated fetuses were hypoplastic and those who had congenital diaphagmatic hernia were even more so. Nitrofen treatment led to decreased plasma T3 and T4 levels without TSH changes. T3 and T4 in lung tissue were apparently decreased in treated fetuses when expressed by weight, but these differences disappeared when expressed by DNA (cell content). CONCLUSIONS: Lung hypoplasia and immaturity induced by nitrofen treatment are not related to decreased levels of thyroid hormones in tissue near term. This should be kept in mind when proposing hormonal treatment for prenatal induction of lung maturation.

Abnormalities, Drug-Induced↗
PubMed1996

Lung hypoplasia and surfactant system immaturity induced in the fetal rat by prenatal exposure to nitrofen.

We studied the biochemical maturity of the lungs of fetuses born to rats exposed to nitrofen on day 9.5 of gestation. In comparison with controls, nitrofen-treated fetuses had pulmonary hypoplasia (decreased lung/body weight), lung hypocellularity (low DNA content) and cellular atrophy (low protein/DNA and phospholipid/DNA) on gestational days 19 and 21. Treated animals with congenital diaphragmatic hernia (CDH) also had cell atrophy and surfactant immaturity (decreased disaturated phosphatidylcholine/DNA) near term. Our data demonstrate that nitrofen causes lung hypoplasia and some degree of surfactant system immaturity that is particularly prominent in fetuses with CDH.

Animals↗
PubMed1996

Pulmonary surfactant dysfunction in congenital diaphragmatic hernia: experimental and clinical findings.

Experimental and clinical findings indicate immaturity of pulmonary surfactant in congenital diaphragmatic hernia (CDH). Lung histology has shown a decreased amount of lamellar bodies. A low lecithin/sphingomyelin ratio in the amniotic fluid, and decreased concentrations of surfactant protein A and disaturated phosphatidylcholine in the pulmonary tissue and the amniotic fluid have been reported. Furthermore, low compliance and high surface tension have also been found. Evidence of clinical and experimental findings of structural, biochemical and functional pulmonary immaturity in CDH is reviewed. Prenatal administration of corticosteroids to accelerate fetal pulmonary maturation, and the use of early surfactant therapy, should be further evaluated in the clinical management of CDH.

Adrenal Cortex Hormones↗
PubMed1995

The effects of multiple small doses of exogenous surfactant on experimental respiratory failure induced by lung lavage in rats.

AIM: To test the effect on pulmonary gas exchange and mechanics of multiple small doses of exogenous surfactant as an alternative to bolus delivery in experimental respiratory failure induced by lung lavage. METHOD: After anesthesia, tracheostomy and constant volume ventilation, respiratory failure was induced by lung lavage in 20 rats. Animals were randomly assigned to an untreated control group or two experimental groups. Equal total doses of modified porcine surfactant (200 mg.kg-1 body weight), were given by tracheal instillation, either as a single bolus or in four (50 mg.kg-1 b.w.) fractional doses at 10-min intervals. Arterial pH and blood gases, and peak inspiratory pressure (PIP) were measured. RESULTS: After lavage, a rapid decrease in arterial pH and PaO2, and an increase in PaCO2 and PIP were observed in all animals. In both surfactant-treated groups, PaO2 increased after surfactant instillation, and remained significantly higher than controls throughout the experiment. Arterial pH was significantly higher and PaCO2 significantly lower only in the single bolus group. In the multiple dose group, these levels were similar to those of controls. CONCLUSION: In surfactant-depleted rats with respiratory failure, instillation of four fractional surfactant doses did not result in the same enhancement on gas exchange and PIP, in the following 60 min, as same total dose given by a single bolus.

Animals↗
PubMed1993

[Thromboangiitis obliterans (Buerger's disease). Study of 41 cases].

BACKGROUND: The aim of this study was to know the prevalence, clinical and immunological characteristics and evolution of thromboangiitis obliterans. METHODS: Between 1982-1990 41 cases of thromboangiitis obliterans were diagnosed from among 373,899 patients registered (11/100,000) according to the clinical and arteriographic criteria. Of these 41 cases 40 were males with mean age 36 +/- 7 years (mean +/- SD) with only two cases being over 45 years of age. In 40 cases was followed for 44 +/- 29 months (mean +/- SD). RESULTS: All the patients had ischemia of the lower limbs, 34% of the upper limbs, 39% superficial thrombophlebitis, 53% Raynaud's phenomenon, 5% mesenteric ischemia, and 7% myocardial infarction. In 30 symptomatic patients anticardiolipin antibodies were determined and one patient was positive for IgG antibodies. In the 23 patients in whom HLA and anticollagen antibody studies were performed a significant increase was found in HLA-B35, HLA-B40 and type VI denaturalized anticollagen antibodies compared to controls. In general the evolution was progressive when the patients continued smoking and favorable when tobacco was given up except in 2 cases who stopped smoking and in whom the disease progressed and death occurred. The total number of patients who died during follow up was 3 (7%), 2 due to mesenteric ischemia and the third during i.v. infusion of PGE1. CONCLUSIONS: The results demonstrate that thromboangiitis obliterans is a rare disease in Spain. The involvement of visceral arteries is not very infrequent with worse prognosis when the mesenteric arteries are involved. There is a significant increase of determined HLA antigens and anticollagen antibodies in the patients with thromboangiitis obliterans.

Adult↗
PubMedDate not supplied

Lumphocytotoxins in leprosy.

Occurrence of cold lymphocytotoxins has been observed in 59 leprosy sera. In 46% of the patients, cold lymphocytotoxins were present whereas in helathy controls only 13% showed such antibodies. The highest incidence of alloantibodies was detected in lepromatous leprosy. Levels of autoantibodies, immunoglobulins and C3 were tested in parallel without finding any significnat correlations.

Complement C3↗