António J. Ferreira

Functional evaluation of peripheral nerve regeneration in the rat : walking track analysis

The experimental model of choice for many peripheral nerve investigators is the rat. Walking track analysis is a useful tool in the evaluation of functional peripheral nerve recovery in the rat. This quantitative method of analyzing hind limbs performance by examining footprints, known as the sciatic function index (SFI), has been widely used to quantify functional recovery from sciatic nerve injury in a number of different injury models, although some limitations of the SFI has been questioned by several authors. This article is designed to offer the peripheral nerve investigator a noninvasive method to evaluate quantitatively the integrated motor recovery in experimental studies.

Long-term functional and morphological assessment of a standardized rat sciatic nerve crush injury with a non-serrated clamp.

We have recently described the sequence of functional and morphologic changes occurring after a standardized sciatic nerve crush injury. An 8-week post-injury time was used because this end point is the far most used. Unexpectedly, both functional and morphological data revealed that animals had still not recovered to normal pre-injury levels. Therefore, the present study was designed in order to prolong the observation up to 12 weeks. Functional recovery was evaluated using sciatic functional index (SFI), static sciatic index (SSI), extensor postural thrust (EPT), withdrawal reflex latency (WRL) and ankle kinematics. In addition, quantitative morphology was carried out on regenerated nerve fibers. A full functional recovery was predicted by SFI/SSI, EPT and WRL but not all ankle kinematics parameters. Moreover, only two morphological parameters (myelin thickness/axon diameter ratio and fiber/axon diameter ratio) returned to normal values. Data presented in this paper provide a baseline for selecting the adequate end-point and methods of recovery assessment for a rat sciatic nerve crush study and suggest that the combined use of functional and morphological analysis should be recommended in this experimental model.

Ankle kinematics to evaluate functional recovery in crushed rat sciatic nerve

Peripheral nerve researchers frequently use the rat sciatic nerve crush model in order to test different therapeutic approaches. The purpose of this study was to determine the sequence of changes after an axonotmetic injury by means of a biomechanical model of the foot and ankle, and compare them with walking track analysis, over a fixed period of time. A kinematic analysis program was used to acquire ankle motion data for further analysis. Although repeated measures analysis of variance showed significant cumulative changes induced by the crush lesion for both ankle kinematic parameters and sciatic functional index, post‐hoc multiple comparisons by the Student‐Neuman‐Keuls test revealed significant differences between week 0 and week 8 only for ankle kinematics. These results are of importance in showing the superiority of ankle kinematics in detecting small biomechanical deficits related to hyperexcitability of the plantarflexor muscles, in contrast with walking track analysis, which showed full motor functional recovery 8 weeks after the crush lesion. Muscle Nerve 27: 706–714, 2003

Diagnosis, genetic control and preventive management of canine hip dysplasia: a review.

Despite expensive screening and breeding programmes, hip dysplasia (HD) continues to be one of the most common orthopaedic diseases in dogs. The vast majority of dogs afflicted with HD show minimal to no clinical signs, but it can also be a highly debilitating condition for both working and pet dogs. Hip joint laxity is considered a major risk factor for the development of degenerative joint disease and a definitive diagnosis is made if characteristic signs are evident on a ventrodorsal view of the pelvis. Early prediction of the condition can be made using stress radiographic techniques to evaluate the passive hip laxity. The diagnosis of HD may be used for the purpose of selecting breeding stock or to decide on the best treatment approach. Breeding programmes based on individual dog phenotypes have been ineffective and a selection procedure based on breeding value (BV) estimation is recommended. Traditional conservative and surgical treatment approaches are reserved for dogs with overt clinical signs of the disease but such treatments can be expensive and aggressive, and are often ineffective in eliminating clinical signs or subluxation and in preventing the development of degenerative joint disease. The implementation of breeding programmes based on BVs and further research into early prediction/diagnosis of HD and effective preventive treatment approaches are essential.

Use of PLGA 90:10 Scaffolds Enriched with In Vitro–Differentiated Neural Cells for Repairing Rat Sciatic Nerve Defects

Poly(lactic-co-glycolic acid) (PLGA) nerve tube guides, made of a novel proportion (90:10) of the two polymers, poly(L-lactide): poly(glycolide) and covered with a neural cell line differentiated in vitro, were tested in vivo for promoting nerve regeneration across a 10-mm gap of the rat sciatic nerve. Before in vivo testing, the PLGA 90:10 tubes were tested in vitro for water uptake and mass loss and compared with collagen sheets. The water uptake of the PLGA tubes was lower, and the mass loss was more rapid and higher than those of the collagen sheets when immersed in phosphate-buffered saline (PBS) solution. The pH values of immersing PBS did not change after soaking the collagen sheets and showed to be around 7.4. On the other hand, the pH values of PBS after soaking PLGA tubes decreased gradually during 10 days reaching values around 3.5. For the in vivo testing, 22 Sasco Sprague adult rats were divided into four groups--group 1: gap not reconstructed; group 2: gap reconstructed using an autologous nerve graft; group 3: gap reconstructed with PLGA 90:10 tube guides; group 4: gap reconstructed with PLGA 90:10 tube guides covered with neural cells differentiated in vitro. Motor and sensory functional recovery was evaluated throughout a healing period of 20 weeks using sciatic functional index, static sciatic index, extensor postural thrust, withdrawal reflex latency, and ankle kinematics. Stereological analysis was carried out on regenerated nerve fibers. Both motor and sensory functions improved significantly in the three experimental nerve repair groups, although the rate and extent of recovery was significantly higher in the group where the gap was reconstructed using the autologous graft. The presence of neural cells covering the inside of the PLGA tube guides did not make any difference in the functional recovery. By contrast, morphometric analysis showed that the introduction of N1E-115 cells inside PLGA 90:10 tube guides led to a significant lower number and size of regenerated nerve fibers, suggesting thus that this approach is not adequate for promoting peripheral nerve repair. Further studies are warranted to assess the role of other cellular systems as a foreseeable therapeutic strategy in peripheral nerve regeneration.

PASSIVE HIP LAXITY IN ESTRELA MOUNTAIN DOG - DISTRACTION INDEX, HERITABILITY AND BREEDING VALUES

Two hundred and fifteen Estrela Mountain Dogs (EMD) were examined using the PennHIP method between 2002 and 2006. Passive hip laxity (PHL) was estimated calculating the distraction index (DI). Pedigree information was obtained from the Portuguese Kennel Club. The heritability and breeding values were estimated using the linear Animal Model. The DI, using as reference the worst joint of each animal, ranged from 0.15 to 1.12 (0.55 +/- 0.19). The PHL was equal in right and left sides, and was higher in females than in males (P > 0.05 and P <0.01 in the t-test, respectively). The estimated heritability was 0.83 +/- 0.11. The mean breeding values for PHL were stable in EMD born between 1991 and 2003, and showed an improvement in 2004 and 2005. The data confirm high PHL in breeds with high prevalence and severity of canine hip dysplasia. The high heritability indicates that the DI could be reduced in the breed if PHL were used as a selection criterion. The early favourable evolution of DI breeding values could be related with the increase of voluntary radiographic hip screening in the last years, and the subsequent introduction of hip quality as a breeding criterion.

Neural cell transplantation effects on sciatic nerve regeneration after a standardized crush injury in the rat.

The goal of the present study was to assess whether in vitro‐differentiated N1E‐115 cells supported by a collagen membrane would enhance rat sciatic nerve regeneration after a crush injury. To set up an appropriate experimental model for investigating the effects of neural cell transplantation, we have recently described the sequence of functional and morphologic changes occurring after a standardized sciatic nerve crush injury with a nonserrated clamp. Functional recovery was evaluated using the sciatic functional index, the static sciatic index, the extensor postural thrust, the withdrawal reflex latency, and ankle kinematics. In addition, histomorphometric analysis was carried out on regenerated nerve fibers by means of the 2D‐disector method. Based on the results of the EPT and of some of the ankle locomotor kinematic parameters analyzed, the hypothesis that N1E‐115 cells may enhance nerve regeneration is partially supported although histomorphometry disclosed no significant difference in nerve fiber regeneration between the different experimental groups. Therefore, results suggest that enrichment of equine type III collagen membrane with the N1E‐115 cellular system in the rat sciatic nerve crush model may support recovery, at least in terms of motor function. The discrepancy between functional and morphological results also suggests that the combined use of functional and morphological analysis should be recommended for an overall assessment of recovery in nerve regeneration studies.

Early hip laxity examination in predicting moderate and severe hip dysplasia in Estrela Mountain Dog

OBJECTIVES To determine the reliability of early passive hip laxity examination in predicting moderate and severe hip dysplasia. METHODS The passive hip laxity of 104 Estrela Mountain dogs was evaluated using the Ortolani method, conventional hip-extended radiography and the PennHIP method, when the animals were between four and 12 months of age. After the age of one, dogs were re-examined for hip dysplasia using the Fédération Cynologique Internationale scoring system. The passive hip laxity results were subsequently compared with the Fédération Cynologique Internationale scores for sensitivity, specificity, positive predictive value, negative predictive value and accuracy. RESULTS The PennHIP method achieved the best results in specificity (93 per cent), positive predictive value (91 per cent) and accuracy (88 per cent), and the Ortolani method was the best in sensitivity (92 per cent) and negative predictive value (92 per cent). CLINICAL SIGNIFICANCE The Fédération Cynologique Internationale grades D and E can be predicted with confidence even before animals are one year old.

The Dorsal Sagittal Venous Sinus Anatomical Variations in Brachycephalic, Dolichocephalic, and Mesocephalic Dogs and Their Significance for Brain Surgery

Dorsal sagittal venous sinus (DSVS) is an encephalic structure located in the midline of brain dorsal surface, starting behind the frontal venous sinus and following the brain falx in its extension. Knowing DSVS morphology and cranial‐cerebral relationships it is very important for surgeon when he is planning the placement of craniotomies, in order to prevent the damage of this structure. The main purpose of this study were to establish craniometric points that can be used as key points of neurosurgical importance providing an anatomic framework to brain access regarding the localization of DSVS, and to characterize the morphology of DSVS in the three groups considered in study according their type of skull (brachycephalic‐B, dolychocephalic‐D and mesocephalic‐M). The study was performed on 138 formalin‐fixed cerebral hemispheres of 69 adult dog cadavers (23 of each group) which had been removed from the skulls after the introduction of plastic catheters through properly positioned burr holes placed on the five craniometric points considered: asterion(ast), bregma(br), glabella(g), stephanion(st) and pterion(pt). From the three groups, DSVS length and width were different, his geometry in B assumed a triangular appearance and in D, M a “butterfly” shape. From all craniometric points considered, only bregma (br) can be useful as a landmark to delimitate DSVS morphology in all three groups. Asterion in M, stephanion in B, glabella and pterion in all three groups, can not be used to compose a framework that help to understand skull surface projection of DSVS morphology, since their measurements were not uniform. Anat Rec, 2011.

Morphometric assessment of the hip joint in the Estrela Mountain Dog breed

OBJECTIVES To study the radiographic projected hip parameters of the proximal femur and acetabulum in young and adult Estrela Mountain Dogs with normal and abnormal hip joints. The parameters evaluated were: femoral angles of inclination and anteversion (FAI and FAA), femoral neck length and width (FNL and FNW), acetabular depth (AD) and acetabular angle of retrotorsion (AAR). METHODS Five hundred and twenty-five standard hip-extended ventrodorsal radiographic views and 622 mediolateral views of the right and left femur were used to measure the FAI, FAA, FNL, FNW, AD, AAR and modified AAR (mAAR). RESULTS The FAI decreased in adult dysplastic dogs, in females and in right femora; FAA decreased with age; FNL was characterized by a greater relative size in normal adult animals; FNW was greater in abnormal hips in young and adult animals; AD was less in adult dysplastic dogs and in right hips; AAR was similar in the studied groups; mAAR was greater in abnormal hips and in left hips. CLINICAL SIGNIFICANCE The data may be used in future studies, which compare this breed to others. Morphological variations in femoral neck and acetabular morphometric parameters were present, and these variables in dogs with different ages and with hips in varying states of health should not be compared.