Search PubMed⌕ Search

Biomedical subjects

E Fernandez

Publications and source records attributed to E Fernandez.

At least 253 records · Page 14Linked to original sources
PubMed1988

Ultrastructural peculiarities of the supraoptic nucleus of Mauremys caspica (turtle): its evolutionary interest in reptiles.

The hypothalamic Supraoptic Nucleus (SON) supposes an evolutionary achievement in the reptiles, zoological group in which this nucleus is first differentiated. Its scarce development in the chelonian, subject of the present study, is related to their primitive brain pattern. The peculiar location and the topographical configuration of the SON in the hypothalamus of the turtle Mauremys caspica allows to evidence morphologically the successive steps in the evolutionary process from lower to higher vertebrates. The marked neurosecretory character of the chelonian SON is the unequivocal proof of its philogenetic origin derived from the magnocellular preoptic nucleus of lower vertebrates.

Animals↗
PubMed1988

New insights on the mode of action of intrauterine contraceptive devices in women.

To gain a better understanding of the mechanism of action of intrauterine devices (IUDs), a search was made for ova in the genital tracts of 115 women using no contraception and of 56 women using IUDs, all of whom volunteered for study in conjunction with surgical sterilization. Ova were recovered from tubal flushings between 48 and 120 hours after the midcycle peak of luteinizing hormone in 39% of the IUD users compared with 56% of women in the control group (0.05 less than P less than 0.10). This suggests an action of the IUD before the ovum reaches the uterus. Eggs with a microscopic appearance consistent with fertilization were recovered from the fallopian tubes of half of the women using no contraception who had intercourse within the fertile period of the reproductive cycle and from whom ova were recovered. In contrast (P less than 0.01), no eggs with this appearance were recovered in IUD users who had intercourse within the fertile period. No ova were recovered from the body of the uterus of any of the IUD users. Fertilized ova are less likely to reach the uterine cavity containing an IUD. Thus, the principal mode of IUDs is by a method other than destruction of live embryos.

Fallopian Tubes↗
PubMed1987

Postnatal development of microtubules and neurofilaments in the rat optic nerve: a quantitative study.

In this paper the postnatal changes in the cytoskeleton of the rat optic nerve fibers are described and quantified. These changes are also compared with other parameters such as myelination and axonal caliber with the aim of describing a general pattern of optic nerve maturation from a morphological point of view. The results showed that during the first postnatal week microtubules outnumbered neurofilaments but between days 8 and 20 the neurofilaments rapidly increased and on day 20 were about twice as numerous as microtubules. This proportion remained almost unaltered from the end of the third week to the 44th postnatal day. The comparison with other parameters suggested that the cytoskeleton, and in particular the proportion between its components, may be a more reliable index for measuring optic nerve maturation than other variables commonly used.

Animals↗
PubMed1987

Ion transport by lasalocid A across red-blood-cell membranes. A multinuclear NMR study.

Na+ and K+ fluxes mediated by lasalocid A across erythrocyte membranes have been determined from 23Na-NMR peak areas and chemical shifts, respectively. In similar experiments, Cl- transport has been monitored by NMR signal intensities. Taking into account the external pH variations, the results are readily explainable in terms of charge-balance conservation. The effect of disodium 4,4'-diisothiocyanostilbene-2,2'-disulfonate, an anion-exchange inhibitor, has also been studied.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1987

Vasoconstriction of the basilar artery in rabbits: the vasoconstrictor activity of blood, CSF and blood-CSF mixtures incubated for varying periods of time.

After subarachnoid haemorrhage, the amount of blood in the subarachnoid space and the time elapsed since the haemorrhage seem important factors in predicting the occurrence of vasospasm. In this experiment we studied the responses of the rabbit basilar artery to acute topical application of samples of human cerebrospinal fluid (CSF), mixtures of blood and CSF incubated at 37 degrees C for 0 to 12 days. The degree and the duration of the vasoconstriction depended on the time of incubation and on the concentration of blood in the samples. Samples incubated for five and seven days caused severe and long-lasting vasoconstrictions. Samples incubated for 0, 1, 3, 8, 10 and 12 days caused slight or moderate and short-lasting vasoconstriction. Samples incubated for 5, 7, 8, and 10 days showed a linear relationship between the concentration of blood and the degree of constriction up to the blood-CSF ratio of 0.6 to 1 (blood content of 37.5%); further increases of blood concentration did not cause further vasoconstriction. This phenomenon may be related to the saturation of arterial receptors. The course of the vasoconstriction using samples with different blood concentrations suggests the existence of more vasoactive substances. This work seems to confirm the importance of blood concentration in the CSF and of time as factors governing the development of vasospasm.

Animals↗
PubMed1987

Harlequin foetus in four siblings.

Four siblings (three males, one female), affected by harlequin foetus, are presented. Genetic aspects and classification of this variety of ichthyosis are discussed.

Diseases in Twins↗
PubMed1987

The influence of permethrin-impregnated bednets and mass drug administration on the incidence of Plasmodium falciparum malaria in children in Sabah, Malaysia.

A small-scale trial was carried out in the Upper Kinabatangan district of Sabah, Malaysia, to determine the effect of using permethrin-impregnated bednets on malaria transmission. A total of 306 nylon bednets with cotton borders, impregnated at a dose estimated to have been 0.062 g permethrin/m2 of nylon netting, were distributed to 139 households in five villages. At the time of distributing bednets, mass drug administration with Fansidar plus primaquine was also administered to the human population to clear all parasitaemias due to Plasmodium falciparum Welch. In another village, for comparison, mass drug administration was the only intervention. After intervention measures in December 1984 and January 1985, the parasite rates in children declined in all villages during the first month, significantly more in the villages with impregnated bednets than in the control, thus proving that the nets had an impact on malaria. However, after about 2 months, parasite rates started to increase again. After 4-6 months, parasite rates in the villages with bednets approached the rate in the control village without nets. The increase in parasite rates was paralleled by a significant deterioration in the quality, physical condition and the degree of non-utilization of bednets. Entomological evaluation proved the efficacy of permethrin-impregnated nets for controlling Anopheles balabacensis Baisas and other anophelines. Bioassays (1 h exposure) of permethrin-impregnated bednets gave 100% mortality initially and 44-61% mortality after 85-106 days. Mosquito collections in treated bednets were significantly reduced for at least 217 days. The project failed to achieve prolonged suppression of malaria transmission for a combination of entomological, sociological and practical reasons which are discussed in relation to the objectives and implementation of future bednet studies.

Animals↗
PubMed1987

Oculomotor nerve regeneration in rats. Functional, histological, and neuroanatomical studies.

To study oculomotor nerve regeneration in rats, the oculomotor nerve was approached microsurgically and was sectioned at the base of the skull. The nerve stumps were reapproximated and affixed with a plasma clot in Group I animals and were separated by a gap in Group II animals. Visceral eye motility was evaluated weekly between 1 day and 40 weeks after surgery by recording the pupillary diameter under standardized photic stimulation. Somatic eye motility was assessed after 26 weeks by measuring the ocular displacement evoked by vestibular stimulation in the horizontal and vertical planes. Nerve regeneration was documented histologically and morphometrically at 8, 16, and 40 weeks after section. The selectivity of axonal regeneration to the extraocular muscles was investigated after 26 weeks by mapping (with injection of retrograde horseradish peroxidase) the motoneurons that supplied each reinnervated muscle. Between 6 and 20 weeks after section, the pupil diameter showed a progressive reduction in Group I rats, and no changes were observed in Group II rats. Compared with normal rats, the amplitude of horizontal and vertical ocular displacements was decreased, respectively, by 30% and 45% in Group I and by 65% and 80% in Group II. In Group I rats, the vestibular stimulation in the horizontal plane evoked anomalous eye movements with vertical components. On histological examination, regenerated nerves showed a progressive increase of axonal diameter and myelin-sheath thickness. Reinnervated muscles were associated with a less specific, bilateral representation in the midbrain compared with normal muscles, which have unilateral representation. The changes of the somatotopic organization were interpreted as being the result of the misdirected regrowth of axons in the postlesional nerve stump and of the collateral sprouting in the midbrain.

Animals↗
PubMed1987

Epiperineurium-fascial stitches along the stumps of a transected nerve. An additional method for closing the gap in the nerve trunk.

Following peripheral nerve repair, tension on the suture line is regarded as an important factor in producing scar tissue. In some cases, one or more microsurgical epiperineurium-fascial stitches (EPFS) along the proximal and distal stumps of a transected nerve permit their firm approximation, shifting tensile forces from the suture line over longer segments of the nerve stumps. This simple method was used to treat three ulnar and two cranial nerve lesions with gaps ranging from 8 to 20 mm with an end-to-end suture, avoiding any tension on the suture line. In all cases, functional recovery was satisfactory.

Humans↗
PubMed1986

Peripheral nerve autografts to the rat spinal cord: study on the origin and course of regenerating fibres.

Autologous sciatic nerve grafts were implanted to the lower thoracic spinal cord (SC) of adult rats. The grafts were longitudinally placed on both sides of the SC midline over the dura mater and their cut ends were inserted into the dorsal white matter of the SC. Eight to 60 weeks later the grafts were exposed. In a first experimental group (A) either horseradish peroxidase (HRP) or lectin conjugated horseradish peroxidase (WGA-HRP) was injected into the grafts in order to investigate the origin and the course of regenerated fibres entering the grafts. In a second experimental group (B) the SC was acutely transected between the upper and lower graft insertions and either HRP or WGA-HRP was injected into the caudal stump of the SC in order to investigate the ability of regenerating axons once entered the grafts to re-enter the SC. In group A retrogradely labelled cells were found in the SC scattered in proximity of both the caudal and rostral graft insertions and in the ventral horns as far as 30 mm rostrally to the grafts. Labelled cells were also located in the spinal ganglia, at the level of the grafts and up to 6 segments caudal to them. In group B retrogradely labelled cells were present in the SC rostrally to the transection, both in proximity of the upper graft insertions and in the ventral horns as far as 30 mm rostrally to the grafts. These findings demonstrate that PN grafts implanted to the SC of adults rats can be innervated by regenerated axons arising from both intraspinal neurons and dorsal root ganglion cells (group A); furthermore axons from intraspinal neurons entered and elongated in the grafts can re-enter the SC (group B).

Animals↗
PubMed1986

Total excision of spinal lipomas using CO2 laser at low power. Experimental and clinical observations.

Total excision of spinal lipomas (SL) is difficult because of the intimate adhesion between the fibro-adipose tissue and the neural structures. Radical surgery in SL can provoke nervous lesions; therefore many authors recommend only partial excision as a means of decompression. Nevertheless the role of traction or tethering of the spinal cord in all spinal disraphism, including SL, is known to be very important in determining the clinical picture. So partial removal of SL cannot be effective in releasing the tethered cord. The use of a CO2 laser at low power (3-5 W) permitted radical surgery without any neural damage and complications in 2 adult patients with large, not well capsulated SL. These patients were previously operated on by the same surgeon with conventional microsurgical techniques for partial excision. After CO2 laser surgery there was significant improvement of the clinical pictures, the follow-up being respectively 24 and 36 months. This clinical experience was performed after a CO2 laser had successfully been used in an experimental model in rats simulating a condition of SL. Using power of 3-5 W was not sufficient to attain an immediate vaporization, but the adipose tissue first changed into a transparent liquid across which it was possible to recognize the interfaces between the neural structures and the adipose tissue.

Adult↗