Are cursorial birds good kinematic models of non-avian theropods? / ¿Son los pájaros corredores buenos modelos cinemáticos de terópodos no aviares?

Determining kinematics of hindlimbs of theropod dinosaurs has been a challenge. Since cursorial birds are phylogenetically closest to theropod dinosaurs they are commonly used as a kinematic model of theropod dinosaur locomotion. Using a comparative biomechanical approach, we found that cursorial birds have a different morphology of legs than non avian theropodos and that appears to be that felines and ungulates share more morphological properties in the hindlimbs with theropod dinosaurs than cursorial birds. We calculated the ratio between the lower leg and the femur, and the relative length of the tibia and the metatarsus with respect to the length of the femur in cursorial birds, as well as felines, ungulates and non-avian theropods. We found that as the length of the femur increases, the length of the lower leg increases similarly in felines, ungulates and non-avian theropods. On the other hand, existing and extinct cursorial birds did not follow this pattern. This observation suggests that the hindlimb of cursorial birds are not well suited to serve as kinematic models for hindlimb of extinct theropod dinosaur locomotion.

Determinar la cinemática de los miembros pelvianos de los dinosaurios terópodos ha sido un desafío. Dado que las aves corredoras son filogenéticamente más cercanas a los dinosaurios terópodos, son comúnmente utilizadas como modelo cinemático de la locomoción del dinosaurio terópodo. Usando un enfoque biomecánico comparativo, encontramos que las aves corredoras tienen una morfología de pies diferente a la de los terópodos no aviares y parece ser que los felinos y los ungulados comparten más propiedades morfológicas en los pies con los dinosaurios terópodos que las aves corredoras. Calculamos la proporción entre la parte inferior de la pierna y el fémur, y la longitud relativa de la tibia y el metatarso con respecto a la longitud del fémur en aves corredoras, así como en los terópodos no aviares y ungulados. Encontramos que a medida que aumenta la longitud del fémur, la longitud de la parte inferior de la pierna aumenta de manera similar en los terópodos, los ungulados y los terópodos no aviares. Por otro lado, las aves corredoras existentes y extintas no siguieron este patrón. Esta observación sugiere que el miembro pelviano de las aves corredoras no es adecuada para servir como modelos cinemáticos de locomoción del miembro pelviano del dinosaurio terópodo extinto.

Screening of Connexin 26 in Nonsyndromic Hearing Loss

Introduction The first locus for nonsyndromic autosomal recessive hearing loss is on chromosome 13q11-22. The 35delGmutation is present in 80% of cases in which GJB2 is involved, which makes the study of this mutation very important. The viability and benefits of screening for mutations in the connexin 26 gene are now beginning to change the diagnostic evaluation and identification of the etiology of hearing loss. Objective To investigate the occurrence of the 35delG mutation in patients with nonsyndromic sensorineural hearing loss and their first degree relatives. Methods This transversal study included 72 patients from the local hospital. The patients were divided into three groups: group A, sensorineural hearing loss (n = 58); group B, first-degree relatives of group A with sensorineural hearing loss (n = 09); and group C, first-degree relatives of patients from group A without hearing loss (n = 05). All patients had audiological evaluation and genetic testing of the 35delG mutation. Results The 35delG mutation was found in four heterozygous mutations (three of them found in the same family). The other heterozygous mutation was found in a female patient with bilateral, moderate, prelingual, sensorineural hearing loss. A single homozygous mutation was found in a male patient, with severe sensorineural hearing loss in his right ear and profound hearing loss in the left ear. Conclusions The 35delG mutation was found in 7% of the cases. The test is easy to perform and inexpensive, but it is necessary to investigate other genes related to hearing loss. .

Analysis on Bilateral Hindlimb Mapping in Motor Cortex of the Rat by an Intracortical Microstimulation Method

Intracortical microstimulation (ICMS) is a technique that was developed to derive movement representation of the motor cortex. Although rats are now commonly used in motor mapping studies, the precise characteristics of rat motor map, including symmetry and consistency across animals, and the possibility of repeated stimulation have not yet been established. We performed bilateral hindlimb mapping of motor cortex in six Sprague-Dawley rats using ICMS. ICMS was applied to the left and the right cerebral hemisphere at 0.3 mm intervals vertically and horizontally from the bregma, and any movement of the hindlimbs was noted. The majority (80%+/-11%) of responses were not restricted to a single joint, which occurred simultaneously at two or three hindlimb joints. The size and shape of hindlimb motor cortex was variable among rats, but existed on the convex side of the cerebral hemisphere in all rats. The results did not show symmetry according to specific joints in each rats. Conclusively, the hindlimb representation in the rat motor cortex was conveniently mapped using ICMS, but the characteristics and inter-individual variability suggest that precise individual mapping is needed to clarify motor distribution in rats.

Effects of Exercise on Affected and Unaffected Hindlimb Muscles in Rats with Neuropathic Pain Induced by Unilateral Peripheral Nerve Injury

PURPOSE: The purpose of this study was to examine the effects of exercise on muscle weight and Type I and II fiber cross-sectional area of affected and unaffected hindlimb muscles in rats with neuropathic pain induced by unilateral peripheral nerve injury. METHODS: Neuropathic pain was induced by ligation and cutting of the left L5 spinal nerve. Adult male Sprague-Dawley rats were randomly assigned to one of two groups: The Pain+Exercise (PE) group (n=21) and the Sham+Exercise (SE) group (n=20). All rats had 28 sessions of treadmill exercise at grade 10 for 30 minutes, twice/day at 10 m/min for 14 days. Body weight, food intake and activity were measured every day. At 15 days all rats were anesthetized and soleus, plantaris and gastrocnemius muscles were dissected. Muscle weight and Type I, II fiber cross-sectional area of the dissected muscles were measured. RESULTS: The PE group showed significant increases (p<.05), as compared to the SE group for body weight and total diet intake, muscle weight of the unaffected soleus and plantaris, and in Type I and II fiber cross-sectional area of unaffected three muscles and affected plantaris. CONCLUSION: Exercise for 14 days attenuates unaffected soleus, plantaris and gastrocnemius muscle atrophy in neuropathic pain model.

The Use of Elastic Adhesive Tape to Promote Lymphatic Flow in the Rabbit Hind Leg

Any method that deforms the skin of the extremities may increase lymphatic flow rate, and may be applied to treat peripheral lymphedema. This study was undertaken to investigate whether or not elastic adhesive tape with passive exercise can increase lymph flow in the rabbit hind leg by effective and periodic skin deformation. Cannulation into a pre-popliteal afferent lymphatic vessel in the lower left leg of 22 male New Zealand White rabbits was performed under a stereomicroscope. After stabilization, lymph was collected at rest or during passive exercise with an electric motor at 60 r.p.m. for 15 minutes and was then measured. Lymph flow rate was calculated and expressed as g/hour. Increase of lymph flow rate due to taping was significant only for passive exercise (p=0.0317). The lymph flow rate increased linearly as the area of tape was increased (p=0.0011), and lymph flow rates were significantly different according to site (p=0.0017). Tape on the anterior aspect of the ankle caused salient deformation and tended to increase the lymph flow rate more so than tape on the dorsum of the foot (p=0.0831). Taping with elastic adhesive tape in passive exercise increased the lymph flow rate in the rabbit hind leg by deforming the skin, which suggests a novel therapeutic method in cases of peripheral lymphedema.

Restoration of limb regeneration ability in frog tadpoles by electrical stimulation.

Electrical stimulation of advanced tadpoles of Rana breviceps for 24 hr with 3 microA current after hindlimb amputation through shank and ankle slightly increased the number of perfect regenerates as compared to controls. When amputation was made through thigh in tadpoles of the same stage regeneration failed in all cases of the controls but 24 hr stimulation of these tadpoles after similar operation with 3 and 10 microA currents induced fair degree of regeneration in 9 and 40% cases, respectively.

Role of vagus during exercise in thermal panting.

In dogs anaesthetised with pentobarbitone sodium raising the body temperature from 37 degrees C during mild exercise increased the rate of respiration and pulmonary ventilation but decreased the tidal volume. Cold blocking the vagi during the exercise resulted in decrease in respiration rate and minute ventilation, but increase in tidal volume. At 40 degrees C body temperature vagal block was not effective in decreasing the respiration rate and minute ventilation, which may be due to stimulation of lung irritant receptors through hyperthermia.