Robert A. Kainer

Clinical Anatomy of the Equine Foot

A review of investigations of the functional anatomy of the equine foot is presented. Emphasis is placed on the relationships of structures involved in the major diseases of the foot.

Ultrastructural studies of myonecrosis induced by cobra venom in mice

The fine structure of necrotic skeletal muscle in mice injected im with venom of the cobra (Naja naja kaouthia) was studied. Degeneration of the entire muscle fiber and its constituents was observed. The myofilaments coalesced to form an amorphous mass, and the sarcotubular system disappeared. The mitochondria swelled into vacuoles containing fragmented cristae. The vacuoles ruptured and were lysed. The degenerated fibre became a less electron-dense mass containing a few cellular remnants enclosed by a vestige of the plasma membrane. Envenomation with cobra venom does cause necrosis of skeletal muscle in mice.

Histological and histochemical periodicity of cervine Leydig cells in relation to antler growth

Seasonal variation in the testicular interstitial cells and seminal vesicles of 52 Colorado mule deer (Odocoileus hemionus), aged 1.5–7.0 years, was related to phases of the antler cycle to determine whether gonadal activity was altered at the time antler growth was initiated. Concomitant with the onset of antler growth (April), resurgence of testicular activity was indicated by restoration of spermatogenesis and increased nuclear volume and straining intensity of succinic dehydrogenase, 3β-hydroxysteroid dehydrogenase, glucose-6-phosphate dehydrogenase, and fluoride-sensitive esterase in Leydig cells. Changes in enzyme localizations and enhancement of glucose-6-phosphate dehydrogenase indicated stimulation of seminal vesicle glandular epithelium 3–4 weeks after renewed Leydig cell activity. Maximal Leydig cell activity was attained in late September subsequent to velvet shedding. Regression began during the rutting season (November) and proceeded to a baseline of minimal activity (January) that was extant during antler shedding and retained until renewed antler growth. The temporal relatioship between antler growth and gonadal stimulation suggests that gonadotropin secretion is augmented commensurate with antler formation.

IMMUNOTHERAPY OF EXPERIMENTAL CANCER AS A GUIDE TO THE TREATMENT OF HUMAN CANCER

Cancer patients in many centers throughout the world are being treated by a variety of immunologic procedures. One of the most widely used of these therapies requires the administration of the BCG strain of Mycobacterium b0vis.l I t is difficult, however, to determine whether BCG immunotherapy has benefited cancer patients beyond palliation. The major problem is that immunotherapy is being applied at relatively late stages of the disease and after other forms of therapy that may be detrimental to the immune system. According to results obtained with a guinea pig hepatoma model,*, successful cancer immunotherapy with BCG requires: Treatment when there is a small primary tumor burden with no more than microscopic regional lymph node metastases, close contact between BCG organisms and the primary tumor; patients capable of an immune inflammatory response to BCG antigens, an adequate dose of BCG and the production of lymphocytes capable of promoting toxicity against tumor cells in vivo. These requirements may have relevance to the treatment of human carcinomas when there are microscopic but not palpable metastases. The relevance of these requirements to other forms of human cancer is not known. The guinea pig hepatoma model is only distantly related to published clinical studies and, therefore, has had limited value in interpreting the results of these investigations. Treatment of patients with recurrent malignant melanoma by the injection of living BCG into cutaneous metastases comes closest to the guinea pig hepatoma model. The applicability of the guinea pig hepatoma model to these studies is limited because recurrent rather than primary disease was treated; the fact that most, if not all, of the patient benefit was palliative rather than curative, however, is consistent with the results of studies with the guinea pig model. This model is also limited in its applicability to human cancer because it is a hepatoma that is studied as transplants growing in the skin of syngeneic guinea pigs. Human cancer on the other hand is a primary autochthonous disease occurring in a large allogeneic species. Extensive studies on the mechanism of action of intratumorally administered BCG have yielded little information on how this agent causes eradication of primary transplants and regional lymph node metastases. Several in vitro tests with cells and serum from treated animals revealed a variety of immunologic reactivities that accompany tumor de~truction.~ Animals possessing any or all of these reactivities, however, are not always cured. Attempts to correlate cure with the development of tumor specific delayed cutaneous hypersensitivity (DCH) have also failed.5 Animals with established hepatoma transplants in the

Clinical Anatomy of the Equine Head

This topical presentation emphasizes the structures most likely to be encountered in the diagnosis and treatment of diseases of the equine head. Most of the approaches are from superficial to deep. Anatomic variations associated with aging are described. The larynx and guttural pouches are not included in this article.

Effect of diethylenetriaminepentaacetic acid and procaine on hemorrhage induced by rattlesnake venom.

Nineteen compounds and seven combinations of compounds were tested for their ability to neutralize the hemorrhagic activity of Crotalus atrox venom in vitro and in vivo. Two compounds and four combinations were effective in reducing hemorrhage in an in vivo test in which the venom was injected before injection of compounds. DTPA plus procaine HCl was the most effective combination and reduced hemorrhage when injected 1, 5, or 15 minutes after injection of venom. DTPA-procaine reduced hemorrhage induced by injection of C. atrox venom into dogs as well as mice. DTPA in combination with procaine did not reduce myonecrosis or lethality resulting from injection of venom into mice, but it could be used in conjunction with antivenin to treat local tissue damage resulting from rattlesnake venom poisoning.

Histology, Embryology and Gross Morphology of The Mandibular Dentition in Mule Deer

Histologic development of the dentition of the mule deer, Odocoileus hemionus hemionus , is similar to that of other mammalian species. In the dentin the incremental lines and the lines of Owen appear to be the result of one or more of four factors: minute and simultaneous deviation of the dentinal tubules; slight bulges in the dentinal tubules with a localized flourish of branches; differential effect of transmitted or reflected light unaccompanied by variation in the dentinal tubules; interglobular dentin consistent with the incremental pattern. A thin layer of cementum is continuous over the crowns of the cheek teeth. The fibers of the periodontal membrane surrounding the incisors and canines are modified to compensate for the moment imposed upon them by their position. Blood sinuses are conspicuous by their numbers and extent in the periodontal membrane. Both the incisors and the canines are incisiform teeth; the deciduous and permanent second and third premolars are lophodont; the deciduous and permanent fourth premolar and the molars are selenodont. In the selenodont teeth, the enamel dips sharply, separating the cusps to a level deep within the crown. Although the crowns are somewhat hypsodont, these teeth are actually brachyodont.