Predatory Dinosaurs from the Sahara and Late Cretaceous Faunal Differentiation

Late Cretaceous (Cenomanian) fossils discovered in the Kem Kem region of Morocco include large predatory dinosaurs that inhabited Africa as it drifted into geographic isolation. One, represented by a skull approximately 1.6 meters in length, is an advanced allosauroid referable to the African genus Carcharodontosaurus. Another, represented by a partial skeleton with slender proportions, is a new basal coelurosaur closely resembling the Egyptian genus Bahariasaurus. Comparisons with Cretaceous theropods from other continents reveal a previously unrecognized global radiation of carcharodontosaurid predators. Substantial geographic differentiation of dinosaurian faunas in response to continental drift appears to have arisen abruptly at the beginning of the Late Cretaceous.     

RADIOGRAPHIC IMAGING OF THE CANINE INTERCONDYLAR FOSSA

The intercondylar fossa is believed to play an important role in the pathology of cranial cruciate ligament rupture and therefore has received considerable attention in the last decade. Accurate radiographic imaging of the intercondylar fossa requires that the central x-ray beam pass through the center of the intercondylar "tunnel". The anatomy of the canine intercondylar fossa is similar to humans, however, the orientations of the intercondylar fossa's differ. Consequently, the positioning techniques described for humans are not appropriate for the dog. To pass through the center of the dog, intercondylar fossa, the central x-ray beam should be 12° (S.D. 1.7°) caudal from the femoral diaphysis in the sagittal plane and obliqued caudolateral to craniomedial 7° (S.D. 0.60°) (caudo78°proximo7° lateralcraniodistomedial oblique). Cross table positioning was used with the hip flexed and the radiograph cassette placed on the cranial surface of the stifle. However, superimposition of the tuber ischii and soft tissues caudal to the femur made 15° to 20° the best angle obtainable. There was not a significant difference (p = 0.17) in the notch width index between a 12° versus 20° angle of the central x-ray beam caudal to the femoral diaphysis, both with 7° of external rotation of the stifle. The notch width index of 0.252 obtained from radiographic measurements was not significantly different from measurements obtained grossly of 0.254 (n = 26; p = 0.69). Failure to oblique the central x-ray beam caused a significant (p = 0.0008) decrease in the apparent fossa width radiographically.     

RADIOGRAPHIC AND COMPUTED TOMOGRAPHIC EVALUATION OF THE CANINE INTERCONDYLAR FOSSA IN NORMAL STIFLES AND AFTER NOTCHPLASTY IN STABLE AND UNSTABLE STIFLES

The role of the intercondylar fossa in cranial cruciate ligament injury has gained notable attention in humans and it's role is now being questioned in animals. Controversy exists regarding the accuracy of radiographs and computed tomography (CT) in evaluating the intercondylar fossa. This study compared radiographic and CT evaluation with gross evaluation of the intercondylar fossa. Six greyhounds were evaluated before notchplasty, immediately after notchplasty and 6 months after notchplasty in stable and unstable stifles. A fossa width index was used for comparison because it negates the effects of patient size and radiographic magnification. The fossa width index is calculated by dividing the width of the intercondylar fossa by the total condylar width.
The fossa width indices of dogs determined from radiographs and CT were not significantly different before notchplasty except for the cranial fossa width indices which were more inconsistent and tended to underestimate the size when compared to gross measurements. At six months, both stable and unstable stifles had refilling of the notchplasty, but the unstable stifles had significantly greater refilling resulting in no significant enlargement in intercondylar fossa size as compared to the prenotchplasty size. Osteophytes that occurred within the intercondylar fossa were less radiopaque and more easily visualized by computed tomography. Computed tomography provided several advantages, including clearer visualization of the intercondylar fossa, avoiding superimposition of the intercondylar fossa by caudal thigh muscles or tuber ischii and the ability to analyze the cranial and caudal components of the intercondylar fossa separately.     

Congenital elbow dislocations

Three categories of congenital elbow dislocations are described in the literature: humeroulnar, humeroradial, and dislocation or joint laxity with other congenital anomalies. Congenital humeroulnar dislocation is a well-defined problem that occurs predominantly in small breeds of dogs and causes severe limb deformity and dysfunction. Early reduction and stabilization are simple to achieve and have provided good results. Radial head dislocations occur most often as a result of growth disturbance of the radius and ulna. There is a lack of conclusive information on congenital radial head dislocations. Regardless of the etiology, radial head dislocation causes rather mild deformity and lameness and can be treated by conservative management, surgical correction, or radial head ostectomy. Dislocation of the elbow may occur concurrently with other rare congenital anomalies and has been described with ectrodactyly and polyarthrodysplasia.     

Ovarian choriocarcinoma in the mouse

Choriocarcinoma is one of the rarest ovarian tumors in any animal species. This paper describes the gross and microscopic appearance of seven such neoplasms in B6C3F1 mice. Mean age at death was 47 weeks. Tumors were described at necropsy as dark or hemorrhagic cystic lesions. On microscopic examination tumors were composed of hematocysts, intercellular hemorrhage, and cytotrophoblasts, syncytiotrophoblasts, and/or trophoblastic giant cells. Cytotrophoblasts, syncytiotrophoblasts, and occasional giant cells were present in three cases while the other four tumors contained only trophoblastic giant cells.     

A comparison between the effect of an avian reovirus and infectious bursal disease virus on selected aspects of the immune system of the chicken

Reovirus 81-176 was inoculated subcutaneously into day-old specific-pathogen-free leghorns and evaluated for its effects on the immune system over a 3-week period. Structural criteria included organ weights of the bursa of Fabricius (BF) and spleen (SP), scoring of histological lesions in the BF, SP, and thymus, and hematological analyses of the circulating leukocytes. Alterations in the functional capacity of the immune system were measured using the graft-versus-host reaction, the response of peripheral blood lymphocytes (PBLs) to mitogens, the ability of circulating monocytes to phagocytize latex beads, and the serological responses to Newcastle disease virus, sheep red blood cells, and Brucella abortus antigens. For comparison, infectious bursal disease virus (IBDV) was similarly evaluated by most of the same tests. Structurally, reovirus 81-176 altered BF and SP organ weights, the total numbers of white blood cells in circulation, and the degree of follicular atrophy in the BF. Functionally, reovirus inoculation reduced both the response of PBLs to the phytohemagglutinin-P stimulation and monocyte uptake of latex beads. According to the protocols used here, no significant alteration in B-cell function could be detected in reovirus-infected chicks. With the exception of leukocyte hematology, IBDV-infected chicks had significantly altered responses in all tests used. By way of comparison, the effects of IBDV were more persistent and pronounced than were those seen with reovirus. The graft-versus-host reaction indicated an elevated and/or uninhibited response of T-cells in the blood of IBDV-infected chicks.     

Technique for physiological examination of canine skeletal muscle in vivo

A technique is described for studying the physiological function of canine skeletal muscle in vivo. The contractile properties of the tarsal flexor muscles were examined in three beagle dogs under general anaesthesia. The force responses to electrical stimulation of the common peroneal nerve were measured at various frequencies to determine the frequency:force relationship for this muscle group. Fatigue characteristics were also examined during intermittent stimulated activity delivered in a set pattern of frequencies. The results provide quantitative characterisation of muscle function which is repeatable. The technique described could be applied to other animals and is a potentially powerful tool for evaluating the effects of drugs on muscle performance.