Repair of nerve injury by implanting prostheses obtained from isogenic acellular nerve segments. / Reparación de lesiones en nervios mediante el implante de prótesis obtenidas de segmentos acelulares de nervio isogénico.

INTRODUCTION: When a nerve section with a significant gap occurs, it is necessary to use a prosthesis to suture it. To date an autologous nerve segment graft appears to be the best treatment; but it has several important disadvantages. Our goal is to study the effectiveness of an isogenic acellular nerve prosthesis comparing a simple suture with tubulisation. MATERIAL AND METHOD: Four groups of Wistar rats were used. The animals in Group 0 served as donors of nerve segments to graft. Group 1 received the implant with an end-to-end suture. In group 2, the implant was sutured inside an ɛ-caprolactone tube. Group 3 received it in a polylactic-co-glycolic acid tube. We evaluated the motor function (sciatic index and step test in motion), and the regeneration length by histological study of regeneration, after a maximum of 3 weeks. RESULTS: Regeneration was uneven in the three groups. In all groups, there were implants with regenerated nerve fibres at the maximum studied length (15mm) and others where regeneration was scarce. The mean regeneration length was greater in the direct end-to-end suture group (G1), although the regeneration speed was similar in the three groups. Group 1 showed the highest percentage of regeneration, but the variability of results prevents this difference reaching statistical significance. We found no significant differences between the two groups with polymer tubes. CONCLUSION: For the implantation of isogenic acellular nerve prosthesis, under our experimental conditions, the direct end-to-end suture was more effective than when it isprotected with biopolymer tubes.

Interaction between surgical procedure for repairing retinal detachment and clinical risk factors for proliferative vitreoretinopathy.

PURPOSE: To asses risk factors of proliferative vitreoretinopathy (PVR) and a model for predicting it. METHODS: Observational, case-control. 335 patients with non-complicated retinal detachment (RD) were included: 134 developed PVR (Cases); 201 patients did not (Controls). Risk factors for PVR were identified by multivariate analysis. Influence of variables was assayed according to the surgical approach. By logistic regression analysis a model to predict the risk of developing PVR and odds ratio (OR) values for each clinical factor were estimated. RESULTS: Risk was higher in patients > 70 years and with intraocular pressure lower than 14 (OR: 3.84; CI 95%: 2.04-7.30) and in retinal breaks larger than "1 clock hour" (OR: 2.54; CI: 1.28-5.05), extended retinal detachments (OR: 4.01; CI: 1.98-8.10) and reinterventions (OR: 1.55; CI: 1.14-9.22). Scleral surgery also was a risk factor (OR: 3.89; CI: 2.12-7.14) and aphakia/pseudophakia when scleral surgery is performed (OR: 3.33; CI: 1.54-7.22). A model to predict PVR was proposed with these results. CONCLUSIONS: Surgical approach modifies risk factors of PVR, and should be taken into account to improve the models for predicting it.

The need for continuous immunosuppression with cyclosporin A to maintain an experimental model of uveal melanoma.

We investigated the need for continuous immunosuppression to maintain experimental tumours derived from human uveal melanoma cells implanted in the choroid of pigmented rabbits. Two groups of pigmented rabbits immunosuppressed with cyclosporin A (CsA) were implanted with human uveal melanoma cells in the suprachoroidal space. After 5 weeks, CsA was discontinued in group 2. Animals were treated with prophylactic antibiotics and examined weekly for tumour growth, weight and secondary effects; blood urea nitrogen levels were measured every two weeks. Autopsies and histopathological studies were performed after death or euthanasia at the end of week 12. The difference between the groups in the development of ophthalmoscopic tumours was not statistically significant 5 weeks after implantation. Tumours in group 1 grew progressively throughout the experiment, whereas group 2 tumours showed marked regression 3-4 weeks after discontinuing CsA. Tumours in group 1 were significantly larger and had greater mitotic activity and showed more ciliary body, optic nerve and extrascleral invasion than tumours in group 2, which showed massive fibrosis, minimal mitotic activity and marked inflammatory cell infiltration. Continuous immunosuppression with CsA seems to be necessary to maintain tumour growth in this experimental model of uveal melanoma.

[Use of systemic antibiotics in Valladolid (1996-2000)]. / Consumo de antibióticos sistémicos en Valladolid (1996-2000).

A longitudinal retrospective study was conducted to analyze the changes in the use of systemic antibiotics from 1996 to 2000 in the province of Valladolid, Spain. The use of systemic antibiotics was determined according to the defined daily dose and showed a progressive increase during the first four years of the study, followed by a large decrease in the year 2000. When examined by subgroup, wide spectrum penicillins accounted for almost 60% of the antibiotics consumed, and were therefore responsible for this change. Macrolides represented 16.4% of the consumption, which increased during the whole study period. Quinolones, with 9.3% of the total, showed a slow but steady increase. Cephalosporins accounted for 8.1%, with their use decreasing since 1998. It was concluded that wide spectrum penicillins were the most used systemic antibiotics in the study population, although a decreasing trend in their use and an increase in the use of macrolides and quinolones was observed.

[Retinal shortening: the most severe form of proliferative vitreoretinopathy (PVR)]. / Acortamiento retiniano: la forma más grave de la vitreorretinopatía proliferante (VRP).

PURPOSE: To identify the clinical characteristics of patients developing retinal shortening due to intraretinal PVR. METHODS: Observational and retrospective cohort study on 110 PVR patients operated on between 2000 and 2001. During surgery, after removing epiretinal membranes and ruling out the presence of subretinal membranes, a perfluorocarbon liquid was injected. Those cases in which retinal flattening was not accomplished, were considered intraretinal PVR (group 1). Those in which retinal flattening allowed endolaser application, were taken as the control group (group 2). Clinical features of both groups were compared by chi-square test. RESULTS: 60 cases (54.5%, CI 95%: 40.5-68.5) showed retinal shortening (group 1). In 24 cases (21.8%, CI 95%: 12.9-30.7) complete retinal flattening was accomplished (group 2). In 26 cases (23.6%), evaluation was inconclusive. In 9 out of the 60 cases of group 1 (15%) a retinectomy was necessary to reattach the retina. Differences between both groups were not statistically significant for any of the clinical variables. However, the number of retinal detachments of more than 60 days of evolution was significantly higher in retinectomized eyes (20.7%) than in group 1 (3.7%) (p=0.04). CONCLUSIONS: Retinal shortening is a relatively frequent phenomenon in PVR. Further studies are necessary to characterize this clinical presentation of PVR and its pathogenesis.

[Dry eye signs and symptoms in hydrogel contact lens wearers: relation to smoking habit]. / Síntomas y signos de ojo seco en usuarios de lentes de contacto hidrofílicas: relación con el hábito de fumar.

PURPOSE: To determine whether there may be a relationship between the smoking habit ant the presence of dry eye signs and symptoms in a population of hydrogel contact lens (HCL) wearers. MATERIAL AND METHODS: 60 adults HCL wearers were chosen randomly. The sample was divided into three groups: nonsmokers, smokers of less than 15 cigarettes per day and smokers of more than 15 cigarettes per day. The ocular symptoms were evaluated with a questionnaire (modified Mc Monnies test). Evaluation of tear meniscus, Schirmer test with anesthesia, non invasive break-up time (NIBUT), slit lamp examination and fluorescein staining were performed to assess ocular signs of dry eye. RESULTS: No significant differences were found among the three study groups. CONCLUSION: Smoking does not seem to affect the presence of signs and symptoms of ocular dryness in a population of HCL wearers and does not predispose to contact lens intolerance.

[Experimental study on usefulness of silicone-fluorsilicone copolymer oil (SiFO) in vitreoretinal surgery]. / Estudio experimental sobre la utilidad del aceite de copolímero de silicona-fluorsilicona (SiFO) en la cirugía vitreorretiniana.

PURPOSE: To evaluate the usefulness of silicone-fluorsilicone copolymer oil (SiFO) as an intraoperative tool and a vitreous substitute in vitreoretinal surgery. METHODS: Handling properties of SiFO were tested and compared with those of perfluorooctane (PFO). The transparency of both substances was measured by spectrophotometry and subjectively assessed. Their tendency to dispersion was observed during injection in balanced saline solution (BSS) and after mechanized and manual shaking. Ease of injection and aspiration through small-gauge instruments was evaluated. Ocular tolerance to SiFO and PFO was studied after intravitreal injection in rabbit eyes: intraocular pressure, anterior segment inflammatory response and dispersion were evaluated, and a histopathological study was performed. RESULTS: Injection and aspiration of SiFO were more difficult than those of PFO because of its higher viscosity. PFO dispersed progressively into small droplets as early as two days after intravitreal injection, whereas SiFO remained as a single bubble for 14 days. Histopathologically both substances induced an inflammatory response over the inferior retina, with microvacuolated macrophages and foreign body giant cells, which were larger in eyes wearing SiFO. CONCLUSIONS: SiFO may be useful as an intraoperative tool, although its main drawback is a more difficult injection and aspiration compared to PFO. It has been well tolerated as a short-term vitreous substitute, but further clinical studies are needed.

Flow changes in forearm arteries after elevating the radial forearm flap: prospective study using color duplex imaging.

The aim of the present study was to assess the changes in flow patterns of forearm arteries produced by excision of the radial artery when harvesting the radial forearm flap. A prospective study using color duplex imaging for quantitative flow measurements was accomplished in 11 patients. After raising the radial flap, the forearm flow tended to increase overall, the ulnar (P = 0.04), the posterior interosseous (P = 0.003), and the anterior interosseous (P = 0.003) arteries being responsible for this tendency. Therefore, harvesting of a radial flap must not be considered as causing vascular morbidity in terms of blood supply to the hand.