Strain stiffening of peripheral nerves subjected to longitudinal extensions in vitro.

The mechanical response of peripheral nerves is crucial to understand their physiological and pathological conditions. However, their response to external mechanical solicitations is still partially unclear, since peripheral nerves could behave in a quite complex way. In particular, nerves react to longitudinal strains increasing their stiffness to keep axons integrity and to preserve endoneural structures from overstretch. In this work, the strain stiffening of peripheral nerves was investigated in vitro through a recently introduced computational framework, which is able to theoretically reproduce the experimental behaviour of excised tibial and sciatic nerves. The evolution and the variation of the tangent modulus of tibial and sciatic nerve specimens were quantitatively investigated and compared to explore how stretched peripheral nerves change their instantaneous stiffness.

Retinal ganglion cells in Strigidae raptors: distribution and morphometry / Células ganglionares de la retina en aves rapaces Strigidae: distribución y morfometría

The authors studied the morphometry and the topographical distribution of Retinal Ganglion Cells (RGCs) in four nocturnal raptors of the order of Strigiformes, family of Strigidae: little owl, tawny owl, scops owl, eared owl. In order to recognize specialized retinal vision areas (fovea and visual streak), the number of RGCs/mm2 and the soma size in the four retinal fields (dorsal, ventral, temporal and nasal) by the histological analysis of retinal radial sections were recorded. A temporal fovea was identified in little owl, tawny owl and eared owl while in scops owl this visual area was localized near the fundus oculi. A radial visual streak ventrally directed was pointed out in the retinas of the four raptors with different shape according to its width. The Authors linked the obtained data with the predatory behavior of nocturnal raptors in their habitat.

Se estudió la morfometría y la distribución topográfica de las células ganglionares de la retina (CGR) en cuatro aves rapaces nocturnas del orden de los Strigiformes, familia Strigidae: búho pequeño, mochuelo, autillo, y cárabo. Con el objetivo de definir las áreas de visión retiniana especializadas (fóvea y campo visual), se registró el número de CGRs/mm2 y el tamaño del soma en los cuatro campos retinianos (dorsal, ventral, temporal y nasal), mediante análisis histológico de las secciones radiales de la retina. Se identificó una fóvea temporal en mochuelo, búho leonado y búho pequeño, mientras que en el búho real, esta área visual se localizó cerca del fondo de ojo. Se observó un campo radial visual dirigido ventralmente en las retinas de las cuatro aves rapaces, con diferentes formas según su extensión. Se relacionaron los datos obtenidos con el comportamiento predatorio de aves rapaces nocturnas en su hábitat.

Number and topographical distribution of retinal ganglion cells in diurnal and nocturnal raptors / Número y distribución topográfica de células ganglionares de la retina en rapaces diurnas y nocturnas

Retinal Ganglion Cells (RGCs) in two diurnal raptors, the buzzard (Buteo buteo) and kestrel (Falco tinnunculus), and in two nocturnal raptors, the little owl (Athene noctua) and tawny owl (Strix aluco), were studied in order to highlight their topographical distribution, taking into account the soma size. Cell density (RGCs/mm2) and median soma area from histological radial sections in four retinal fields (dorsal, ventral, temporal and nasal) were recorded in order to identify specialized retinal vision areas. The results showed a different RGCs distribution between diurnal and nocturnal raptors related to the location of the foveas and shape of the horizontal streak, confirming the bibliographic data. In diurnal raptors, a higher cell density was found in the temporal and central retinal fields as revealed by the presence of a temporal and a central fovea which showed a "horizontal streak". In nocturnal raptors the cell density was higher in the peripheral temporal field likely due to a temporal fovea. A peak in cell density observed in the ventral field, especially in the retina of little owls, might be linked to a more "radial visual streak". Comparing the data obtained we highlighted that the morphology and the number of RGCs are closely linked to the habitat and to the type of predation.

Se estudiaron las células ganglionares de la retina (RGC) en dos aves rapaces diurnas, el ratonero (Buteo buteo) y el cernícalo (Falco tinnunculus), y en dos aves rapaces nocturnas, el mochuelo (Athene noctua) y el búho leonado (Strix aluco), buscando resaltar su distribución topográfica, teniendo en cuenta el tamaño del soma. Se registraron la densidad celular (RGCs/mm2) y la media del área del soma de las secciones histológicas radiales en cuatro campos retinianos (dorsal, ventral, temporal y nasal) para identificar áreas de visión retinianas especializadas. Los resultados mostraron una distribución diferente de RGCs entre las rapaces diurnas y nocturnas relacionadas con la ubicación de las fóveas y la forma de la línea horizontal, lo que confirma los datos bibliográficos. En las aves rapaces diurnas, se encontró una densidad celular más alta en los campos de retina temporales y centrales como lo revela la presencia de una fóvea temporal y central que mostraba una "veta horizontal". En aves rapaces nocturnas, la densidad celular fue mayor en el campo temporal periférico probablemente debido a una fóvea temporal. Un aumento en la densidad celular, observado en el campo ventral, especialmente en la retina de los pequeños buhos, podría estar relacionado con una "línea visual radial". Comparando los datos obtenidos, resaltamos que la morfología y el número de RGC están estrechamente relacionados con el hábitat y el tipo de depredación.

Morphological study of the iris musculature in diurnal and nocturnal raptors / Estudio morfológico de la musculatura del diafragma en aves rapaces diurnas y nocturnas

In literature it is established that the iris musculature consists of striate muscle fibers in birds while in mammals it consists of smooth muscles. Some authors report the presence of smooth muscle tissue also in the iris of some species of birds. In the present study we report on the iris muscle tissues (type of tissue, direction and mean diameter of muscle fibers or cells) in five species of Accipitriformes (diurnal raptors) and four species of Strigiformes (nocturnal raptors) because they show different way of life depending of their predatory behavior. This morphological study was carried out from raptors died or euthanized at the Wild Life Rescue Centre of Sea and Water birds in Livorno (Italy). From histological examination of iris serial radial sections we find both striated and smooth musculature even if with marked differences among analyzed species, not directly correlated with diurnal or nocturnal lifestyle. Striated fibers are always present, mainly with cross direction, throughout the iris stroma, while the histological differences concern the smooth cells. Indeed, harrier and sparrow hawk (Accipitriformes) and great horned owl and little owl (Strigiformes) show a compact layer of cross smooth muscle cells throughout the iris stroma. In the other species analyzed smooth muscle cells are slightly detectable as scattered or not detectable. Since the cross smooth muscle tissue allows to maintain a myotic state for extended periods of time, our results might be correlated more to the predatory behavior than the taxonomic order.

En la literatura, se establece que la musculatura del iris se compone de fibras musculares estriadas en las aves, mientras que en los mamíferos, la forman los músculos lisos. Algunos autores informan también de la presencia de tejido muscular liso en el iris de algunas especies de aves. El presente estudio informa sobre los tejidos musculares del iris (tipo de tejido, la dirección y diámetro de las fibras musculares o células) en cinco especies de Accipitriformes y cuatro especies de Strigiformes que muestran diferentes hábitos en función de su comportamiento depredador. Este estudio morfológico se realizó en aves rapaces que murieron o fueron eutanasiadas en el Centro de Vida Salvaje de Rescate de Aves Marinas y Acuáticas de Livorno (Italia). El examen histológico de secciones seriadas radiales del iris mostró la presencia tanto de musculatura estriada como lisa, aunque con marcadas diferencias entre las especies analizadas, pero sin correlación directa con el estilo de vida diurna o nocturna. Las fibras estriadas estuvieron siempre presentes, principalmente en dirección transversal a lo largo del estroma del iris, mientras que las diferencias histológicas fueron de las células lisas. Tanto el aguilucho y el gavilán (Accipitriformes) como el buho real y el mochuelo (Strigiformes) mostraron una capa compacta de células musculares lisas transversales en todo el estroma del iris. En las otras especies analizadas, las células musculares lisas fueron ligeramente detectables de manera dispersa o no detectables. Dado que el tejido del músculo liso transversal permite mantener un estado miótico durante largos períodos de tiempo, nuestros resultados podrían estar más correlacionados con el comportamiento depredador, y no con el orden taxonómico.

An autologously generated platelet-rich plasma suturable membrane may enhance peripheral nerve regeneration after neurorraphy in an acute injury model of sciatic nerve neurotmesis.

BACKGROUND: The aim of this study was to investigate the ability of suturable platelet-rich plasma (PRP) membrane to promote peripheral nerve regeneration after neurotmesis and neurorraphy. METHODS: A total of 36 rats were used: 32 animals underwent surgery and were split in two groups. An interim sacrifice was performed at 6 weeks postsurgery and final sacrifice at 12 weeks; four animals did not sustain nerve injury and served as control. Clinical, electromyographic (EMG), gross, and histological changes were assessed. The EMG signal was evaluated for its amplitude and frequency spectrum. Number of regenerating fibers, their diameter, and myelin thickness were histologically analyzed. RESULTS: Both EMG parameters showed a significant (p < 0.05) effect of treatment at 6 and 12 weeks postsurgery. At 6 weeks, the fiber density was statistically different between treated and untreated animals with a higher observed density in treated nerves. No difference in fiber density was observed at 12 weeks postsurgery. The distribution of fiber diameters showed an effect at 12 weeks when only the sections of the nerves sutured with PRP showed fibers with diameters greater than 6 µm. DISCUSSION: Our data show that the application of a PRP fibrin membrane around the neurorraphy improves the nerve regeneration process in a rat sciatic nerve model. The use of PRP as a suturable membrane could perform an action not only as a source of bioactive proteins but also as a nerve guide to hold the scar reaction and thus improve axonal regeneration.

Glucagon-like peptide 1 (GLP-1) in the gastrointestinal tract of the pheasant (Phasianus colchicus).

The distribution of Glucagon-like peptide 1 (GLP-1) was investigated in the gastrointestinal tract of the pheasant using immunohistochemistry. GLP-1 immunoreactive cells were common in the small intestine, in the proventriculus and in the pancreas. Immunostained cells were not seen in the crop, in the gizzard and in the large intestine. Double labelling demonstrated that GLP-1 and pituitary adenylate cyclase-activating polypeptide (PACAP) were occasionally co-localized only in the duodenal villi. In contrast to what was previously described in the chicken and ostrich, we noted GLP-1 positive cells in the duodenum. These data were consistent with the presence of proglucagon mRNA in the chicken duodenum. Our findings indicate that GLP-1 might have an inhibitory effect on gastric and crop emptying and on acid secretion also in the pheasant. Moreover, the results of the present research regarding the initial region of the small intestine suggest a further direct mechanism of the GLP-1 release during the early digestion phase and an enhancement of its incretin role.

Isolation and expansion of equine umbilical cord-derived matrix cells (EUCMCs).

Stem cells from extra-embryonic sources can be obtained by non-invasive procedures. We have standardized a method for the expansion of equine umbilical cord-derived matrix cells (EUCMCs) for potential therapy. EUCMCs were isolated from the umbilical cord of five mares immediately after delivery. For expansion, cells were grown in alpha-MEM and MSCBM. Moreover, to measure the effect of growth factor supplementation, epidermal growth factor (EGF) was added to alpha-MEM. alpha-MEM and MSCBM media performed similarly in terms of population doubling and CFU number value. EGF supplementation of alpha-MEM determined a significant increase of the population doubling value. EGF supplementation did not affect the adipogenic and chondrogenic differentiation while bone nodule sizes an increased with the osteogenic protocol. Both alpha-MEM and MSCBM can be used to cultivate EUCMCs. alpha-MEM supplemented with EGF might represent an advantage for EUCMCs expansion. The results could be useful in choosing the culture medium since alpha-MEM is more cost-effective than MSCBM.

Different media and supplements modulate the clonogenic and expansion properties of rabbit bone marrow mesenchymal stem cells.

BACKGROUND: Rabbits provide an excellent model for many animal and human diseases, such as cardiovascular diseases, for the development of new vaccines in wound healing management and in the field of tissue engineering of tendon, cartilage, bone and skin.The study presented herein aims to investigate the biological properties of bone marrow rabbit MSCs cultured in different conditions, in order to provide a basis for their clinical applications in veterinary medicine. FINDINGS: MSCs were isolated from 5 New Zealand rabbits. Fold increase, CFU number, doubling time, differentiation ability and immunophenotype were analyzed.With the plating density of 10 cells/cm2 the fold increase was significantly lower with DMEM-20%FCS and MSCs growth was significantly higher with alphaMEM-hEGF. The highest clonogenic ability was found at 100 cell/cm2 with MSCBM and at 10 cell/cm2 with M199. Both at 10 and 100 cells/cm2, in alphaMEM medium, the highest CFU increase was obtained by adding bFGF. Supplementing culture media with 10%FCS-10%HS determined a significant increase of CFU. CONCLUSION: Our data suggest that different progenitor cells with differential sensitivity to media, sera and growth factors exist and the choice of culture conditions has to be carefully considered for MSC management.

Morphological and histological study of the ostrich (Struthio Camelus L.) liver and biliary system.

The peculiarity of the digestive system of the ostrich (Struthio Camelus L.), which is characterized by the continuous production of bile, led us to undertake macroscopical and histological studies of the liver and its biliary system, since very little bibliographic data exist on the subject. For this purpose we observed the organs of male and female ostriches 16-18 months of age, in situ, in order to describe their location, relationships and morphology. Samples of the liver were processed for observation by light microscopy; samples of the hepatoenteric duct were processed for observation by light and electron microscopy. Our findings regarding the liver revealed the presence of two lobes: a left lobe, subdivided into three lobes, and a right undivided lobe. There was no gall-bladder. The histological picture showed unlimited hepatic lobules, with hepatocytes arranged in cord-like fashion two cells thick. A large hepatoenteric duct arose from the porta hepatis, and opened into a papilla in the descending limb of the duodenum. The mucosa of the duct was lined by simple columnar epithelium consisting of cells having the same morphological cytoplasmatic features but distinguished by either a light or a dark nucleus.