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Biomedical subjects

F J Rodríguez

Publications and source records attributed to F J Rodríguez.

At least 19 recordsLinked to original sources
PubMed2003

Engineering an artificial nerve graft for the repair of severe nerve injuries.

Nerve repair with tubes has a limit to regeneration depending upon the length of the gap. The characteristics of the guide, in terms of permeability, durability and adhesiveness, also influence regeneration. Considering the importance of the cellular component in regeneration, the development of artificial grafts, composed of a biocompatible nerve guide filled with a neurotropic matrix and seeded with Schwann cells (SCs), is an interesting option to enhance nerve regeneration and provide an alternative to the classical autologous nerve graft. We evaluated the ability of SCs transplanted into a nerve guide to improve regeneration after sciatic nerve resection, leaving a 6-mm gap, in the mouse. Syngeneic, isogeneic and autologous SCs were suspended in Matrigel and seeded in resorbable guides, and compared to acellular guides and to nerve autografts. The immunogenicity of the transplanted SCs clearly influenced the outcome. Transplants of autologous SCs resulted in only slightly lower levels of reinnervation than autografts, but higher recovery and number of regenerated axons than transplants of isologous and syngeneic SCs, and than acellular guides. Thus, by combined developments on nerve guides, extracellular matrix components and cell transplantation, an artificial graft has been designed that allows axonal regeneration across long gaps to levels comparable with an autograft.

Absorbable Implants↗
PubMed2001

Restrictions on the coherence of the ultrafast optical emission from an electron-hole-pair condensate.

We report on the transfer of coherence from a quantum-well electron-hole condensate to the light it emits. As a function of density, the coherence of the electron-hole-pair system evolves from being full for the low-density Bose-Einstein condensate to a chaotic behavior for a high-density BCS-like state. This degree of coherence is transferred to the light emitted in a damped oscillatory way in the ultrafast regime. Additionally, the photon field exhibits squeezing properties during the transfer time. Our results suggest a new type of ultrafast experiments for detecting electron-hole-pair condensation.

Journal Article↗
PubMed2000

Expansion of adult Schwann cells from mouse predegenerated peripheral nerves.

We present an effective technique for culture and expansion of Schwann cells (SC) from adult peripheral nerves. Cultures from adult mouse sciatic nerves (one to six nerves per culture) in defined medium showed markedly higher purity and density of SC when the nerve was predegenerated in vivo for 7 days than when it was harvested fresh. SC from degenerated nerves were then cultured in defined media conditioned by primary cultures of adult SC. The best results were obtained with a conditioned medium supplemented with 1% fetal calf serum. In these conditions the purity of SC was about 90% and the density about 190 cell/mm(2) by 7-10 days in vitro. These findings indicate that adult SC can be expanded from small preinjured nerve fragments in a short time period to provide a source of SC for autologous cellular transplants.

Age Factors↗
PubMed2000

Polyimide cuff electrodes for peripheral nerve stimulation.

This paper describes a new tripolar spiral cuff electrode, composed of a thin (10 microm) and flexible polyimide insulating carrier and three circumneural platinum electrodes, suitable for stimulation of peripheral nerves. The cuffs were implanted around the sciatic nerve of two groups of ten rats each, one in which the polyimide ribbon was attached to a plastic connector to characterize the in vivo stimulating properties of the electrode, and one without a connector for testing possible mechanical nerve damage by means of functional and histological methods. The polyimide cuff electrodes induced only a very mild foreign body reaction and did not change the nerve shape over a 2-6 month implantation period. There were no changes in the motor and sensory nerve conduction tests, nociceptive responses and walking track pattern over follow-up, and no morphological evidence of axonal loss or demyelination, except in one case with partial demyelination of some large fibers after 6 months. By delivering single electrical pulses through the cuff electrodes graded recruitment curves of alpha-motor nerve fibers were obtained. Recruitment of all motor units was achieved with a mean charge density lower than 4 microC/cm(2) for a pulse width of 50 micros at the time of implantation as well as 45 days thereafter. These data indicate that the polyimide cuff electrode is a stable stimulating device, with physical properties and dimensions that avoid nerve compression or activity-induced axonal damage.

Animals↗
PubMed2000

Nerve guides seeded with autologous schwann cells improve nerve regeneration.

This study evaluates the ability of Schwann cells (SCs) transplanted into a nerve guide to improve regeneration and reinnervation after sciatic nerve resection and repair, leaving a 6-mm gap, in the mouse. SCs were isolated from predegenerated adult sciatic nerves and expanded in culture using a chemically defined medium. Syngeneic, isogeneic, and autologous SCs were suspended in Matrigel and seeded in resorbable, permeable poly(l-lactide-co-epsilon-caprolactone) guides at 150,000 cells/tube. Guides containing SCs were compared to guides filled with Matrigel alone and with peroneal nerve autografts. Functional reinnervation was assessed by noninvasive methods to determine recovery of sweating, nociceptive, sensory, and motor functions in the hindpaw during 4 months postoperation. Morphological analysis of the regenerated nerves was performed at the end of follow-up. The group with an autograft achieved faster and higher levels of reinnervation and higher number of regenerated myelinated fibers than groups repaired by tubulization. The immunogenicity of transplanted SCs influenced the outcome of nerve regeneration. Transplants of autologous SCs resulted in slightly lower levels of reinnervation than autografts, but higher recovery and number of regenerated fibers reaching the distal nerve than transplants of isologous and syngeneic SCs, although most of the differences were not statistically significant. Syngeneic SCs did not improve regeneration with respect to acellular guides. Prelabeled transplanted SCs were found to survive into the guide 1-3 months after implantation, to a larger number when they were autologous than syngeneic. Cellular prostheses composed of a resorbable guide seeded with autologous SCs appear as an alternative for repairing long gaps in injured nerves, approaching the success of autografts.

Action Potentials↗
PubMed2000

Pinus pollen in the atmosphere of Vigo and its relationship to meteorological factors.

The Pinus genus has an elevated pollen production and an anemophilous nature. Although considered to be hypoallergenic, numerous cases of allergies caused by Pinus pollen have been cited and different authors believe that its allergenicity should be studied in more depth. In the city of Vigo several patients have tested positive for Pinus pollen extracts in skin tests, some of them being mono-sensitive to such pollens. In order to ascertain the behaviour of Pinus pollen and its correlation to the main meteorological factors, we carried out an aerobiological study in the city of Vigo from 1995 to 1998 by using a Hirst active-impact volumetric sporetrap, model Lanzoni VPPS 2000, placed on the left bank of the Vigo estuary (42 degrees 14'15"N, 8 degrees 43'30"W). Pinus has high quantitative importance in the airborne pollen spectrum of the city. It is one of the best represented taxa constituting 13%-20% of the total annual pollen levels. The quantity of Pinus pollen present in the atmosphere of the city of Vigo throughout a year is 5,751 grains (as the average for the sampled years), with a very long pollination period, from the middle of January until May. The maximum concentration was recorded in 1998 with 1,105 grains/m(3) on 3 March, a much greater value than those for the previous years. At the end of its pollination period there is usually a final increase in Pinus pollen concentrations coinciding with the pollination of Pinus silvestris, which are more abundant in mountainous areas far from the city.

Humans↗
PubMed2000

TNF-alpha dependent production of inducible nitric oxide is involved in PGE(1) protection against acute liver injury.

BACKGROUND: Tumour necrosis factor alpha (TNF-alpha) and nitric oxide modulate damage in several experimental models of liver injury. We have previously shown that protection against D-galactosamine (D-GalN) induced liver injury by prostaglandin E(1) (PGE(1)) was accompanied by an increase in TNF-alpha and nitrite/nitrate in serum. AIMS: The aim of the present study was to evaluate the role of TNF-alpha and nitric oxide during protection by PGE(1) of liver damage induced by D-GalN. METHODS: Liver injury was induced in male Wistar rats by intraperitoneal injection of 1 g/kg of D-GalN. PGE(1) was administered 30 minutes before D-GalN. Inducible nitric oxide synthase (iNOS) was inhibited by methylisothiourea (MT), and TNF-alpha concentration in serum was lowered by administration of anti-TNF-alpha antibodies. Liver injury was evaluated by alanine aminotransferase activity in serum, and histological examination and DNA fragmentation in liver. TNF-alpha and nitrite/nitrate concentrations were determined in serum. Expression of TNF-alpha and iNOS was also assessed in liver sections. RESULTS: PGE(1) decreased liver injury and increased TNF-alpha and nitrite/nitrate concentrations in serum of rats treated with D-GalN. PGE(1) protection was related to enhanced expression of TNF-alpha and iNOS in hepatocytes. Administration of anti-TNF-alpha antibodies or MT blocked the protection by PGE(1) of liver injury induced by D-GalN. CONCLUSIONS: This study suggests that prior administration of PGE(1) to D-GalN treated animals enhanced expression of TNF-alpha and iNOS in hepatocytes, and that this was causally related to protection by PGE(1) against D-GalN induced liver injury.

Alanine Transaminase↗
PubMed1999

Olfactory bulb ensheathing cells enhance peripheral nerve regeneration.

Sciatic nerve resection leaving a 15 mm gap could not be repaired by bridging the stumps with a silicone tube prefilled with a laminin gel. However, when purified olfactory ensheathing cells (EC) were added to the gel filling the tube, successful axonal regeneration was observed in 50% of rats. With 12 mm gaps, regeneration occurred in 79% of rats with transplanted EC compared with 60% of those receiving collagen gel alone. Therefore, ECs help repair severe peripheral nerve injuries, in addition to their ability to promote axonal regeneration within the central nervous system.

Action Potentials↗
PubMed1999

Physiological and immunohistochemical characterization of cisplatin-induced neuropathy in mice.

We investigated the neuropathic effects of cisplatin in two groups of mice treated with 5 or 10 mg/kg/week of cisplatin for 7 or 8 weeks. Peripheral nerve functions were evaluated by sweat imprints, and electrophysiological, rotarod, and nociceptive tests. Protein gene product 9.5 (PGP), calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP) were immunohistochemically localized in footpads. Tibial nerves were analyzed morphometrically. Functional deficits developed progressively with higher cumulative doses, more markedly in mice treated with high than in those with low doses. From cumulative doses of 10 mg/kg, significant declines in sensory nerve conduction velocity and sudomotor responses were found, whereas motor and nociceptive functions were involved later. There were no morphometrical changes in tibial nerves. A marked decrease of CGRP- and VIP-immunoreactive nerves occurred in samples from treated mice, whereas PGP-labeled profiles decreased mildly at late stages. Impairment of the content of neuropeptides with neurosecretor role was detectable earlier than functional abnormalities. Immunohistochemical analysis of skin biopsies offers a useful diagnostic tool for peripheral neuropathies.

Animals↗
PubMed1999

Ensheathing glia transplants promote dorsal root regeneration and spinal reflex restitution after multiple lumbar rhizotomy.

Previously, we have shown that transplants of olfactory bulb ensheathing cells promoted regeneration of transected dorsal roots into the spinal cord. In this study, we assessed the ability of regenerating axons to make functional connections in the cord. Dorsal roots L3 to L6 were sectioned close to their entrance into the spinal cord and reapposed after injecting a suspension of ensheathing cells into each dorsal root entry zone (Group G). Afferent regeneration into the cord and recovery of spinal reflexes were compared with animals that received no injection (Group S) or culture medium without cells (Group C). Electrophysiological tests, to measure nerve conduction and spinal reflexes (H response and withdrawal reflex) evoked by stimulation of afferents of the sciatic nerve, were performed. At 14 days after surgery, H response was found in only 1 of 7 rats of Group G, and withdrawal reflexes were absent from all animals. At 60 days, the H response reappeared in 7 of 10 rats of Group G, and 1 of 5 of each of Groups C and S. The withdrawal reflex recovered in 4 of 10 rats of Group G, but in none of Groups C and S. Immunohistochemical labeling for calcitonin gene-related peptide (CGRP) in rats of Group G showed immunoreactive fibers entering the dorsal horn from sectioned roots, although at lower density than in the contralateral side. In conclusion, transplanted ensheathing cells promoted central regeneration and functional reconnection of regenerating sensory afferents.

Animals↗
PubMed1999

Highly permeable polylactide-caprolactone nerve guides enhance peripheral nerve regeneration through long gaps.

We compared regeneration and functional reinnervation after sciatic nerve resection and tubulization repair with bioresorbable guides of poly(L-lactide-co-epsilon-caprolactone) (PLC) and permanent guides of polysulfone (POS) with different degrees of permeability, leaving a 6 mm gap in different groups of mice. Functional reinnervation was assessed to determine recovery of motor, sensory and sweating functions in the hindpaw during four months postoperation. Highly permeable PLC guides allowed for faster and higher levels of reinnervation for the four functions tested than impermeable or low-permeable PLC guides, while semipermeable 30 and 100 kDa POS tubes yielded very low levels of reinnervation. The regeneration success rate was higher with PLC than with POS tubes. Morphometrical analysis of cross-sectional nerves under light microscopy showed the highest number of regenerated myelinated fibers at mid tube and distal nerve in high-permeable PLC guides. Impermeable PLC guides allowed slightly worse levels of regeneration, while low-permeable PLC guides promoted neuroma and limited distal regeneration. The lowest number of regenerated fibers were found in POS tubes. In summary, highly permeable bioresorbable PLC guides offer a suitable alternative for repairing long gaps in injured nerves, approaching the success of autologous nerve grafts.

Absorbable Implants↗
PubMed1998

Changes in cholinergic responses of sweat glands during denervation and reinnervation.

Functional sudomotor responses have been studied in sweat glands reinnervated after sciatic nerve crush and partially denervated by cisplatin intoxication in the mouse. The sudomotor function mediated by the sciatic nerve was evaluated by silicone imprints on the plantar surface of the hindpaws. Five days after nerve crush, completely denervated sweat glands became unresponsive to cholinergic stimulation with pilocarpine. During the following weeks, the number of reinnervated, reactive sweat glands increased progressively to reach a maximum of 89% of preoperative control counts by 40 days after nerve crush. At this time, the mean volume of sweat secreted per gland was normal, but reinnervated glands showed a secretory activity abnormally sustained over time after pilocarpine stimulation and, on the other hand, had an increased resistance to the inhibition of secretion induced by atropine. The effects of cisplatin administration on sudomotor function were investigated in two groups of mice, one treated with high doses of cisplatin (10 mg/kg/week for 4 weeks) and another treated with low doses of cisplatin (5 mg/kg/week for 8 weeks). Cisplatin intoxication produced abnormal sudomotor responses indicative of denervation from cumulative doses of 10 mg/kg. The first abnormality found was a partial resistance of sweat glands to atropine, followed by a decrease in the sweat output per gland and finally a decline in the number of sweat glands activated by pilocarpine. These abnormalities in the sudomotor responses were more pronounced in mice treated with a high dose than in those with a lower dose regime.

Animals↗
PubMed1998

Stimulation and recording from regenerated peripheral nerves through polyimide sieve electrodes.

This paper describes the use of a new polyimide sieve electrode as a chronic neural interface to stimulate and record signals from regenerated peripheral nerves. Flexible thin polyimide electrodes were placed in silicone chambers and implanted between the severed ends of the sciatic nerve in rats. The sieve part of the interface has 281 round via holes of 40 microns diameter, with seven integrated recording-stimulating electrodes arranged around via holes. Axonal regeneration through the via holes was demonstrated by histological and physiological methods over a two to six month post-implantation period in all the rats. The regenerated nerves were organized in fascicles corresponding to the grid pattern of the via holes. Longitudinal sections showed myelinated fibers, with normal appearance and well developed myelin sheath, crossing the via holes. Stimulation of the regenerated nerve through the polyimide electrode evoked distal muscle and nerve responses similar in amplitude to those evoked by nerve stimulation with hook metal electrodes. The polyimide electrodes were useful for recording nerve action potentials in response to electrical stimulation of the distal regenerated nerve, and in response to functional sensory stimulation of several modalities.

Animals↗
PubMed1996

Peripheral nerve regeneration through bioresorbable and durable nerve guides.

We compared reinnervation of target organs after sciatic nerve resection and repair by tubulization with biodurable tubes of silicone and teflon, or bioresorbable nerve guides of collagen and poly(L-lactide-co-6-caprolactone) (PLC) leaving a 6 mm gap in different groups of mice. All tubes were of 1 mm inside diameter and thin-walled (50 to 250 microm). Functional reinnervation was assessed by noninvasive methods to determine recovery of sweating, sensory and motor functions in the hindpaw repeatedly during 5 months postoperation. PLC guides allowed faster and higher levels of reinnervation for the four functions tested than collagen and silicone tubes, while teflon tubes gave the lowest levels of recovery. Regenerative reinnervation by thin nociceptive and sudomotor fibers was higher than by large sensory and alphamotor fibers in all groups. Resorbable tubes promoted regeneration in a higher proportion of mice than durable tubes. In cases with effective regeneration the nerve cable was multifascicular, with mild to moderate mononuclear cell infiltrates and a thin newly formed perineurium. The number of myelinated fibers was higher in PLC and silicone tubes than in collagen and teflon tubes. There was only minimal inflammatory reaction within the remnants of collagen tubes, but not in the other materials. PLC tubes of slow reabsorption rate seem useful for repairing long gaps in injured nerves.

Absorbable Implants↗
PubMed1994

Presumed occlusion of posterior ciliary arteries following central retinal vein decompression surgery.

OBJECTIVE: Sectioning of the posterior scleral ring has been advocated in the treatment of central retinal vein occlusion. We reviewed cases in which this surgery apparently produced sectioning or closure of the short and long posterior ciliary arteries that resulted in a triangular area of choroidal ischemia and permanent chorioretinal lesions. DESIGN: Case series. SETTING: Clinic-based vitreoretinal referral practice. PATIENTS: Four eyes of three patients whose ages ranged from 17 to 53 years underwent sectioning of the posterior scleral rings as treatment for central retinal vein occlusion. MAIN OUTCOME MEASURES: Findings from complete ophthalmologic evaluation. RESULTS: All patients had either an oval or a triangular area of choroidal ischemia nasal to the optic disc and had permanent chorioretinal lesions. CONCLUSIONS: Valid basis for performing this operation requires further investigation.

Adolescent↗
PubMed1992

Separation and determination of aminohalogenbenzophenones by high-performance liquid chromatography with electrochemical detection.

A high-performance liquid chromatographic method with electrochemical detection has been developed for the determination of three aminohalogenbenzophenones: 2-amino-2',5-dichlorobenzophenone, 2-amino-5-chlorobenzophenone and 2-amino-5-bromo-2'-fluorobenzophenone, metabolites of benzodiazepinooxazoles and other psychotropic drugs. A mobile phase of methanol-water (65:35), containing 5 mM KH2PO4 appeared to be the optimal when a 4-microns, 60-A Nova-Pak C18 column and a flow-rate of 0.75 ml/min (130 bar) were used. The temperature was optimized at 30 degrees C. The amperometric detector, equipped with glassy carbon electrode, was operated at 1.3 V versus Ag/AgCl in the DC mode. The method was applied to the determination of these compounds at two concentration levels: ppm and ppb (ng/cm3) using 2-amino-5-chlorobenzophenone as internal standard. The limit of determination was 750 pg/ml of biological fluid for each compound, and recoveries greater than 97% were obtained for spiked samples of urine and serum, using C18 Sep-Pak cartridges in the sample clean-up procedure.

Anti-Anxiety Agents↗