Off-axis crustal thickness across and along the east pacific rise within the MELT area

Wide-angle seismic data along the Mantle Electromagnetic and Tomography (MELT) arrays show that the thickness of 0.5- to 1. 5-million-year-old crust of the Nazca Plate is not resolvably different from that of the Pacific Plate, despite an asymmetry in depth and gravity across this portion of the East Pacific Rise. Crustal thickness on similarly aged crust on the Nazca plate near a magmatically robust part of the East Pacific Rise at 17 degrees15'S is slightly thinner (5.1 to 5.7 kilometers) than at the 15 degrees55'S overlapping spreading center (5.8 to 6.3 kilometers). This small north-south off-axis crustal thickness difference may reflect along-axis temporal variations in magma supply, whereas the across-axis asymmetry in depth and gravity must be caused by density variations in the underlying mantle.     

Rumen digestive physiology and microbial ecology

The rumen is a dynamic, continuous fermentation compartment that provides a suitable environment for a variety of species of anaerobic bacteria, protozoa, and fungi. These microorganisms have a complex series of interactions with the feeds supplied to the host, with some using particulate matter as both sources of nutrients and sites of sequestration to avoid being washed from the rumen by the rapid flow of fluids. Because of the ability to use soluble nutrients and to reproduce rapidly, other microbes associate primarily with the liquid phase of the rumen contents. Due to the metabolic activity of all microbial populations, feeds are converted to microbial matter and fermentation end products, which serve as nutrients for the ruminant. Optimum feed utilization by ruminants is dependent on achieving maximum rumen fermentation and flow of microbial protein to the duodenum. At this time, it is clear that the major nutrients required by the microbial populations include both fibrous and nonfibrous sources of carbohydrates and nitrogen in the form of ammonia, amino acids, and peptides. In spite of five decades of research, the exact quantities and sources of these nutrients that will result in optimum rumen fermentation rates and microbial yields are only partially known.     

Anesthesia of bulls undergoing surgical manipulation of the vas deferentia.

Twelve bulls ranging from 341 to 545 kilograms in body mass were successfully anesthetized for either vasectomy or prosthetic vas deferens implantation with a combination of thiopental sodium, glyceryl guaiacolate, nitrous oxide, halothane and oxygen. Duration of anesthetic administration was 119.2 plus or minus 24.2 (S.D.) minutes. Righting reflexes returned 15.0 plus or minus 8.0 minutes after cessation of anesthetic administration and the bulls were capable of standing within 46.6 plus or minus 17.8 minutes. Interpretations of pulse rate, respiratory rate and eye reflexes were related to anesthetic depth and maintenance. A control mean respiratory frequency of 28.8 plus or minus 3.6 per minute compared to minimum and maximum frequencies of 26.8 plus or minus 5.1 and 37.6 plus or minus 6.3, respectively, during anesthetic maintenance. A control mean pulse frequency of 91.6 plus or minus 15.9 per minute compared to minimum and maximum frequencies of 84.8 plus or minus 13 and 102.3 plus or minus 13.4, respectively, during maintenance of anesthesia. Methods for avoiding complications related to anesthetic induction, maintenance and emergence were described. Specific pharmacological aspects of atropine, halothane and nitrous oxide were emphasized in light of their application to ruminant anesthesia.     

Attempted transmission of Toxoplasma gondii infection from pregnant cats to their kittens

Sixteen 1- to 7-week-old pregnant specific-pathogen free cats were inoculated orally with Toxoplasma gondii cysts. Fetuses and neonatal kittens were examined for toxoplasma infection by inoculating suspensions of their tissues into mice. Toxoplasma gondii was not isolated from 23 fetuses and 16 newborn kittens from 13 queens. Six (3 litters) of the 15 kittens from the 3 remaining queens were killed on the day of or a day after birth, and the remaining 9 kittens were housed with their mothers for 7 to 33 days. None of the 9 kittens from the 2 litters examined between 0 and 33 days of age was infected with T gondii. In the other litter, T gondii was isolated from 3 kittens killed at 9, 16, and 22 days of age but not from 3 littermates killed on days 1, 1, and 22. Internal organs from the 3 kittens with proved toxoplasma infectivity in mice were examined histologically. Multifocal granulomatous encephalitis, hepatitis, nephritis, myocarditis, myositis, and interstitial pneumonia were found in all 3 kittens. Toxoplasma forms were demonstrated histologically in the tissues of 2 of these kittens. The mode of toxoplasma infection in newborn kittens was not determined but did not appear to be either transplacental or via fecal contamination from oocysts excreted by the mother cat. Evidence obtained in these experiments suggests that transplacental toxoplasma infection in the cat is not an important epidemiologic factor in perpetuation of the disease in the feline population.     

Influence of thymectomy on the susceptibility of cats to feline leukemia virus and lymphosarcoma.

Twelve cats were thymectomized at 5 weeks of age. Six of these cats were inoculated at 8 weeks of age and 6 at 4 months of age with the Rickard (R) strain of feline leukemia virus (FeLV), which produces a high incidence of thymic lymphosarcoma. Two groups of age-matched nonthymectomized cats were inoculated with the same FeLV-R stock. Thymectomy prior to FeLV infection had no influence on the induction of viremia or the incidence of lymphosarcoma. In the FeLV-inoculated nonthymectomized cats, lymphosarcoma developed in the thymus. In the thymectomized cats, lymphosarcoma developed in the intestine, mesenteric lymph nodes, and bone marrow, but the malignant lymphoblasts had surface markers characteristic of feline T lymphocytes. It was concluded that the presence of the thymus per se is not required for infection and oncogenesis by FeLV and that feline T lymphocytes may be transformed after peripheralization to other tissues.     

Modifications of the immunofluorescence assay for feline leukemia virus group-specific antigens.

Observations and minor modifications are presented concerning the immunofluorescence assay for feline leukemia virus (FeLV) group-specific antigens (GSA) in blood cells of cats. Data are given regarding absorption of goat FeLV GSA antiserum in vivo in cats, absorption of the antiserum in vitro with feline blood cells, and the comparative efficacy of various chemical fixatives in preservation of FeLV GSA for immunofluorescent staining. The best results were obtained with in vitro absorption of antiserum and methanol fixation of FeLV GSA in blood smears.     

The subacute neurotoxicity of excess pyridoxine HCl and clioquinol (5-chloro-7-iodo-8-hydroxyquinoline) in beagle dogs. I. Clinical disease

The clinical and clinicopathologic effects of excess oral pyridoxine hydrochloride (150 mg/kg body weight/day) and clioquinol (200 mg/kg body weight/day) alone and in combination were evaluated in adult Beagle dogs over an experimental period of approximately 100 days. Anorexia and loss of body weight occurred in the first weeks of the trial period in each treatment group, but was most severe in dogs given both compounds. Dogs in each treatment group (10 of 10 pyridoxine-treated dogs, 6 of 13 clioquinol-treated dogs and 12 of 13 pyridoxine plus clioquinol-treated dogs) developed neurologic disease, manifested principally by ataxia. Pyridoxine-treated dogs had proprioceptive loss involving both fore- and hindquarters, characterized by stiff, spastic, dysmetric leg movements. In clioquinol-treated dogs, dysmetric leg movements were accompanied by failure to support body weight in the hindquarters, but similar forelimb involvement occurred in severely affected dogs. The neurologic disease in dogs given both compounds varied; signs in some dogs resembled those of affected dogs of the pyridoxine-treated group, and in others, those in clioquinol-treated group. Erythrocyte counts, hemoglobin concentrations and packed cell volumes were reduced in dogs in each treatment group and were lowest in dogs given both compounds. Plasma protein was mildly reduced in dogs given pyridoxine or pyridoxine plus clioquinol. Few or no differences were present in the leukocyte counts, blood urea nitrogen concentrations, in activities of serum alanine aminotransferase and aspartate aminotransferase, and in concentrations of sodium, chloride or potassium in treated dogs as compared to control dogs.     

Phytomitogen- and antigen-induced blast transformation of feline lymphocytes.

A semiautomated microassay of blast transformation of feline lymphocytes was developed and used in a study of the response of normal cats to phytomitogen- and antigen-induced stimulation. Peripheral blood lymphocytes were isolated from defibrinated blood by ficolldiatrizoate gradient centrifugation and incubated at a concentration of 1 X 10(5) cells/culture. Blast transformation was measured by the incorporation of tritiated thymidine, to which the cells were exposed during the last 18 hours of incubation. Phytomitogens induced maximal transformation after 3 days' incubation. Greatest stimulation produced by 10 mug of concanavalin A (38- to 183-fold) followed by 4 mug of pokeweek mitogen (nine- to 51-fold), and finally phytohemagglutinin-P (three- to sixfold). Three of 4 cats sensitized to keyhole limpet hemocyanin responded when exposed to 50 mug of keyhole limpet hemocyanin in vitro, maximal transformation occurring after 4 days' incubation. Lymphocyte blast tranformation provides a convenient technique to assess lymphocyte function serially during experimentally induced immunologic alterations in the cat.