Apparent thiamin status of cattle and its relationship to polioencephalomalacia.

The thiamin status (thiamin concentration in whole blood, plasma, and erythrocytes; erythrocyte transketolase activity) of normal cattle consuming varying diets did not differ from that of cattle with polioencephalomalacia or lead poisoning. Dairy cattle had higher ruminal content of thiamin and lower thiamin destroying activity than did beef cattle. Renal oxalosis was no more frequent in cattle which had polioencephalomalacia than in postnatal calves. In normal beef cattle, approximately 75% of total blood thiamin is in erythrocytes and the remainder in plasma.     

Identification of multiple equine infectious anemia antigens by immunodiffusion reactions.

Equine infectious anemia (EIA) cell antigens prepared from infected equine spleen, equine leukocyte cultures or a persistently infected equine dermis cell line contained at least two serologically reacting components. For convenience one component was designated as soluble antigen (SA) and the other as cell-associated antigen (CAA). The SA appeared as a single component when it was prepared from EIA virus precipitated from infectious tissue culture fluid with polyethylene glycol and ether treated but it was mixed with CAA when the source was infected cells. Cytolytic or mechanical disruption of infected cells appeared to accelerate the release of CAA. Reaction to each component could be identified in double and radial immunodiffusion tests by increasing the concentrations of SA in a two-component antigenic mixture. The CAA component does not appear to affect the value of the immunodiffusion test as a diagnostic aid.     

In vitro antimicrobial sensitivity of Mycoplasmas isolated from the bovine genital tract.

The in vitro antimicrobial sensitivity of 14 mycoplasma and 13 ureaplasma strains isolated from the genital tracts of bulls was examined. It was found that at relatively low concentrations, tetracycline, declomycin and tylosin were lethal to both types of organisms. Lincospectin, berenil, streptomycin and erythromycin were lethal to mycoplasmas but were only inhibitory to the ureaplasma strains at the same concentrations. Polymyxin B and novobiocin were ineffective at the levels tested.     

Stabilization of hog cholera virus by dimethyl sulfoxide.

The stability of hog cholera virus through five freeze-thaw cycles in the presence and absence of dimethyl sulfoxide was studied. In the absence of dimethyl sulfoxide the hog cholera virus titer was reduced 52% to 91% following successive freezing and thawing cycles. However, when dimethyl sulfoxide was added to the viral suspension the virus titer appeared to remain the same after the same number of freezing and thawing cycles.     

The Kinetics of Hematopoiesis in the Light Horse I. The Lifespan of Peripheral Blood Cells in the Normal Horse

Three Standardbred horses were given 0.2 mg (1 mCi) of ⁷⁵selenomethionine intravenously and a second group of three were given 10 mCi of tritiated diisopropylfluorophosphate (0.5 mg) intravenously. Observations on labeled cells were continued for 250 days after radioselenium injection and 160 days after tritium injection.

The lifespan of erythrocytes using ⁷⁵selenmethionine was 155 ± 10 days and 148 ± 7.8 days using tritiated diisopropylfluorophosphate. There was no significant difference at the 10% level between the lifespans, using these labels. The uptake of radioselenium into erythrocytes reached a mean maximum of 11.5% at 82 ± 18.9 days after injection of the label. There was an elution of from 17.6% of the injected dose of tritium label down to 7.5% eight days after injection of this isotope. From this study both of these labels appear to be satisfactory for determining the erythrocyte lifespan of the horse.

The mean time of the curve of mean radioselenium activity of peripheral blood leukocytes for the three horses was 5.54 days and the lifespan of these cells was seven days. The mean lifespan of peripheral blood leukocytes of the three horses after in vivo labelling with tritiated diisopropylfluorophosphate was 17.3 hours. No specific labelling was found in bone marrow or peripheral blood cells at this level of tritium labelling by dipping emulsion autoradiography.

The mean lifespan of equine platelets for three horses using radioselenomethionine was 9.2 days and the mean lifespan of equine platelets using tritiated diisopropylfluorophosphate was 6.6 days in a group of three horses.

     

Experimental Edema Disease of Swine (E. Coli ENTEROTOXEMIA) III. Pathology and Pathogenesis

Experimental colibacillary (Escherichia coli) enterotoxemia as described in this report mimics natural edema disease both clinically and in gross pathology. The histopathology is characterized by accumulations of non-inflammatory edema and by arteriopathy. The smaller arterial and arteriolar changes recorded here are similar to those described in natural edema disease. The vascular changes described in recovered cases of experimental colibacillary enterotoxemia concur with those reported in so-called subacute and chronic edema disease. The arteriolar changes that occur in colibacillary enterotoxemia of swine are comparable to those associated with hypertension.

Thin sections of cerebral cortex from four pigs with acute experimental edema disease were examined by electron microscopy in an attempt to demonstrate brain edema. Sections from one pig taken during the convulsive phase of disease revealed dilatation of perivascular glial processes. However, examination of sections taken from three other pigs during an earlier phase of the neurological disturbance revealed no significant lesions. We were unable to ascertain the role of brain edema in the pathogenesis of the nervous system disturbance in these experiments.