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Biomedical subjects

E Fernandez

Publications and source records attributed to E Fernandez.

At least 235 records · Page 13Linked to original sources
PubMed1989

Efficiency of the respiratory muscles in healthy individuals.

We evaluated respiratory muscle performance by determining the energy cost of breathing against incremental threshold loads and calculating the efficiency of the respiratory apparatus for handling the added work. In five subjects, the energy cost of breathing against the loads, and thus the calculated efficiency of the respiratory muscles, was reproducible on repeated measurements. In all subjects, the calculated efficiency varied while breathing with low loads but was relatively constant at loads that resulted in a mouth pressure of 20 to 60% of the subjects' maximal static inspiratory pressure (PImax). The mean efficiency calculated between 20 to 60% of PImax in 30 normal subjects (15 males and 15 females) ranged between 1.54 and 7.98%. It was significantly greater in males (5.41 +/- 0.43%) (mean +/- SEM) than in females (2.41 +/- 0.17%). There was no relationship between efficiency and body size, but the efficiency correlated with inspiratory muscle strength (PImax). We suggest that measurement of the efficiency of the respiratory muscles over a spectrum of incremental threshold loads is a simple, noninvasive, and reproducible method of assessing respiratory muscle performance and may have clinical application.

Adolescent↗
PubMed1989

The effects of acute hypoxia and hypercapnia on pulmonary mechanics in normal subjects and patients with chronic pulmonary disease.

The influence of progressive hypoxia and hypercapnia on respiratory mechanics was evaluated in 26 subjects (six normal subjects, seven asthmatic subjects, seven patients with IPD, and six patients with COPD). During separate rebreathing runs of progressive isocapnic hypoxia and normoxic hypercapnia, breath-to-breath changes in RL and Cdyn were determined. In five of the six normal subjects, seven of the seven asthmatic subjects, and six of the seven subjects with IPD, RL decreased with both progressive hypoxia and hypercapnia without a change in Cdyn. In the patients with COPD, the effects of hypoxia and hypercapnia on RL and Cdyn were variable. Compared to normal subjects, the changes in RL during hypoxia and hypercapnia were not significantly different in the asthmatic subjects and the patients with IPD. These data provide evidence that acute progressive hypoxia and hypercapnia are associated with significant changes in Raw in both normal subjects and patients with chronic pulmonary disease.

Adult↗
PubMed1989

Efficacy of a pulsed oxygen delivery device during exercise in patients with chronic respiratory disease.

The ability of a pulsed oxygen delivery system (Puritan-Bennett Companion Oxygen Saver (COS-5) to track respiratory rate during exercise and the oxygenation achieved during the exercise while oxygen was being delivered by this system was compared to that attained while oxygen was delivered continuously in six patients with chronic obstructive pulmonary disease (COPD) and six patients with idiopathic pulmonary fibrosis (IPF). The COS-5 appeared to respond appropriately at respiratory rates between 15 and 45, even when there were minimal pressure changes at the nose. There was an excellent correlation in PaO2 at equivalent flow settings during the exercise in the patients with COPD and IPF. There were six instances (in four patients) of the 31 comparisons in which the PaO2 differed by more than 5 mm Hg. The PaO2 was higher with continuous oxygen delivery on two occasions in a patient with COPD who utilized pursed-lip breathing during the exercise. The PaO2 was higher with COS-5 delivery on two occasions in a patient with IPF who was breathing at the highest respiratory rates (44 and 45/min) during the exercise.

Adult↗
PubMed1989

Studies on embryonic transplants to the transected spinal cord of adult rats.

Spinal cord tissue was obtained from 13- and 14-day embryonic rats and homologously grafted to the completely transected spinal cord of adult rats. Eight and 12 weeks after grafting, clinical, electrophysiological, histological, and neuroanatomical studies were performed. Motor performance of the hosts was assessed by the inclined-plane test. The conduction of nerve impulses across the lesion-transplantation site was evaluated by recording the spinal corticomotor and somatosensory evoked potentials. The survival, growth, differentiation, and parenchymal integration of the graft were documented histologically on semi-thin sections. The axonal interactions between the host spinal cord and the graft as well as the posttraumatic retrograde degeneration of corticospinal axons were investigated using the horseradish peroxidase (HRP) technique. Clinical and electrophysiological assessments did not demonstrate any functional activity of the graft. On histological examination, grafted neurons showed a survival rate of 55%. Such neurons exhibited a limited degree of growth and differentiation. The extent of parenchymal integration between the host spinal cord and the graft varied considerably among different specimens and in the various regions of every specimen. The HRP investigations demonstrated that some axonal interactions between the host spinal cord and the graft had occurred. Regenerated axons arising from both the spinal cord and the dorsal root ganglia of the host entered the graft and elongated in it. Also, axons from the grafted neurons were able to grow for some distance in the host spinal cord. The phenomenon of the posttraumatic retrograde degeneration of corticospinal axons was not affected by this embryonic tissue grafting.

Animals↗
PubMed1989

Age influence on digestive transit time of particulate and soluble markers in broiler chickens.

The gastrointestinal transit-time of two markers, Cr-mordanted bran, a solid marker, and Cr-EDTA, a soluble marker, have been studied in chickens (Gallus gallus) at 1, 2, and 3 wk of age. Mean retention time of the particular marker decreased as chicks grew. The excretion of Cr-EDTA took longer as birds grew; this soluble marker was retained in the ceca of the fowl. It was postulated that the ceca are not fully functional until total resorption of the yolk sac content occurs.

Aging↗
PubMed1989

Swine cysticercosis treated with praziquantel, a short report.

Swines with cysticercosis are a useful model to study human disease. A multidisciplinary approach was undertaken to study in detail the effect of praziquantel treatment on hosts and parasites. Computerised tomographic scans showed changes in the number and size of parasites in treated pigs. These changes were more apparent in muscle than in brain cysticerci. Neurophysiologic data were normal in cysticercotic pigs before and after drug treatment. An increase in antibody response was seen immediately after treatment regarding the amount of antibodies and number of antigens recognised. A lower number of polyploid lymphocytes was seen after treatment in cysticercotic pigs as compared to untreated pigs. At different times after treatment pigs were humanely euthanised. Oxygen consumption rate of cysticerci decreased after treatment and evagination was abolished. The inflammatory reaction that surrounded parasites increased in number and type of cells. This was more apparent around cysticerci obtained from muscle than from the brain.

Animals↗
PubMed1989

[The "retention complex" and its relationship to abutments: what is today's thought?].

Based up on a review of the literature, the authors have tried to define the possible responsibility of each component of a retention complex (occlusal support--cross-piece--locking arm--retention arm) in the mechanical mobilisation of abutment teeth supporting partial removable prostheses (Kennedy, Class I and II). Taken separately, all these components are intrinsically able to mobilise the teeth. However, no "modern" retention complex (Nally & Martinet--R.P.I.--R.P.A.--"equipoise"...) should jeopardize the abutments, as long as they have been correctly prepared as well as the entire prosthesis.

Dental Abutments↗
PubMed1988

Peripheral nerve autografts to the rat spinal cord: a study of the origin of regenerating fibres using fluorescent double labelling.

In adult Wistar rats a segment of the right sciatic nerve was grafted to the right dorsal funiculus of the spinal cord (SC). After survivals of 25-54 weeks a solution of the retrograde fluorescent cytoplasmatic tracer Fast Blue (FB) was injected into the SC and microgranules of the retrograde fluorescent nuclear tracer Diamidino Yellow (DY) were inserted into the graft. DY labelled neurones were found in the SC up to 30 mm both rostrally and caudally to the graft and were always single labelled. DY labelled cells were also found in the dorsal root ganglia (DRG) for 6-7 consecutive levels caudally to the graft. Ten to 30% of the DY labelled DRG cells were double labelled and also contained the FB tracer. The present work using the multiple retrograde fluorescent tracing method demonstrates that peripheral nerve (PN) grafts implanted in the rat SC are reinnervated by axones arising from intrinsic SC neurones and DRG cells. The axones from intrinsic SC neurones seem to result only from the regrowth of damaged neurones which have lost their intraspinal projections. The regeneration from DRG cells seem to be sustained by both the regrowth of damaged axones and the preterminal and/or collateral sprouting.

Amidines↗
PubMed1988

Risk factors for developing voiding dysfunction after abdominoperineal resection for adenocarcinoma of the rectum.

Voiding dysfunction is a common sequel of abdominoperineal resection of the rectum. Twenty patients symptomatic after abdominoperineal resection, 14 with a preoperative normal urodynamic study and six with evidence of obstruction, were studied postoperatively. The importance of the following factors is analyzed: sex, stage, grade, size, distance of the tumor from the anal verge, metastatic lymph-node involvement, and extent of lymphadenectomy. Male gender, tumors situated between 4 and 8 cm from the anal verge, and lymphadenectomy that includes more than ten nodes may be considered risk factors for neurologic damage and postoperative voiding dysfunction.

Adenocarcinoma↗
PubMed1988

Serological and biochemical analysis of foot-and-mouth disease virus (serotype C3) isolated in Argentina between 1981 and 1986.

The evolution in the field is described for foot-and-mouth disease viruses belonging to serotype C3 in Argentina between 1981 and 1986. During 1981 and 1982 only three isolations of this serotype took place, which showed minor serological and biochemical variations from the prototype strain C3 Resende-Brasil/55. At the beginning of 1983 an outbreak was detected in a restricted geographical region caused by strains which had important serological and biochemical differences from the prototype strain. However, revaccination of the animals with the available commercial vaccine was sufficient to control the disease. During 1984 and up to 1986, a new outbreak of the same serotype took place in an extended geographical region of Argentina. During this outbreak, two field strains were isolated, studied and later included in the vaccine. One of them, strain C84, was a serological variant of the prototype strain and its inclusion in the vaccine had only a limited effect in controlling the disease. Inclusion of the other representative strain, C85, together with virus C84 finally reduced the number of outbreaks to the usual number reported.

Animals↗
PubMed1988

Determination of flunarizine in plasma by a new high-performance liquid chromatography method. Application to a bioavailability study in the rat.

A reversed-phase high performance liquid chromatographic (HPLC) method is described for the study of the pharmacokinetics of flunarizine. The method involves selective liquid-solid extraction of flunarizine and meclizine (as internal standard) from samples of rat plasma. The optimization of the extraction and HPLC separation parameters are discussed. Recoveries were satisfactory and the relative standard deviation for replicate assays was below 10%. The sensitivity of the method would allow the detection of flunarizine in plasma at 13 ng ml(-1). Kinetic parameters for a bioequivalency study between flunarizine and a liquid formulation (oral drops) have been evaluated; the relative bioavailability was 88%.

Journal Article↗
PubMed1988

Early changes in cerebrospinal fluid Ca2+ and FFA levels following experimental spinal cord injury.

Cerebrospinal fluid (CSF) Ca2+ and free fatty acids (FFA) levels were determined for 4 h following experimental spinal cord (SC) injury in rabbits. The injury was produced by dropping a 20 g weight from 20 cm on exposed dura mater at the C5-C6 level. Samples of CSF were obtained from the cisterna magna from a second laminectomy at the C1 level. A significant decrease in CSF Ca2+ levels was observed 10 and 30 min post-injury; such levels increased above normal values 180 min post-injury. A significant increase in CSF FFA levels was seen from 10 to 240 min post-injury with a peak at 30 min. The early decrease of CSF Ca2+ levels and the concomitant increase in CSF FFA levels seem to confirm in role of Ca2+ in mediating the lipolytic response of the SC tissue to trauma.

Animals↗
PubMed1988

The third nerve transection and regeneration in rats with preliminary results on the sixth nerve transection and regeneration in guinea pigs.

The relationship between the phenomenon of the nonselective reinnervation and the functional recovery after section and repair of the highly organized third cranial nerve motor system in rats was studied. The same relationship after section and repair of the more simply organized sixth cranial nerve motor system in guinea pigs is presented as preliminary results. Anatomical demonstration of nonselective reinnervation was obtained by injecting horseradish peroxidase (HRP) into the extraocular muscles. A bilateral reinnervation of previously ipsilateral innervated muscles both in the third and the sixth nerve was interpreted as a plastic response of the brain stem neurons to the nerve injury. Functional recovery, evaluated by measuring with an infrared light technique the horizontal and vertical vestibulo-ocular reflexes, was excellent for the rectus lateralis muscle while it was relatively poor i.e. partial for the muscles depending on the third nerve. These data suggest that one of the most important factors influencing the functional recovery after section and repair of a peripheral nerve is the complexity of the nerve motor system organization.

Abducens Nerve↗
PubMed1988

Retrograde degeneration of corticospinal axons following transection of the spinal cord in rats. A quantitative study with anterogradely transported horseradish peroxidase.

The extent of the retrograde degeneration of corticospinal axons following transection of the spinal cord was studied in rats by labeling corticospinal axons with anterogradely transported horseradish peroxidase injected in the sensorimotor cortex. Axotomized corticospinal axons underwent progressive and continuing retrograde degeneration. In specimens examined 5, 14, 28, and 56 days after trauma, the tips of the transected corticospinal axons were seen to terminate at 181 +/- 80 microns, 977 +/- 203 microns, 1751 +/- 344 microns, and 2559 +/- 466 microns (mean +/- standard deviation), respectively, from the site of transection. The rate of retrograde degeneration varied according to the interval after spinal cord transection, as follows: 36.2 microns/day during the first 5 days; 88.4 microns/day between 5 and 14 days; 55.3 microns/day between 14 and 28 days; and 28.8 microns/day between 28 and 56 days. These findings may serve as useful parameters for the objective assessment of therapeutic modalities in spinal cord injury research.

Animals↗