Sublethal irradiation of BALB/c mice 4 hours prior to inoculation with 5 X 10(4) virulent Brucella abortus, caused significant (P < 0.01) reductions in bacterial numbers in comparison with numbers in unirradiated controls. Numbers of brucellae in the spleen were significantly lower by 5 days after inoculation and decreased thereafter, so that at 2 and 3 weeks after inoculation, there were up to 1,000-fold fewer organisms in the spleen of irradiated mice. The number of brucellae in the spleen increased in irradiated mice thereafter. The course of events in the liver was similar, but developed more slowly, and peak differences in bacterial numbers were about 1 log less. These phenomena were not attributable to differences in implantation of brucellae in the liver or spleen, nor to an abnormal distribution of organisms in other organs of irradiated mice. Irradiation of mice during the plateau phase of infection also resulted in significant (P < 0.05) reductions in bacterial counts in the spleen during the succeeding 4 weeks. Macrophage activation in the spleen, measured by a Listeria monocytogenes-killing assay, was significantly (P < 0.01) increased by irradiation alone at 1 week after inoculation and at that time was significantly (P < 0.01) greater in B abortus-infected, irradiated mice than in B abortus-infected controls. Histologic, cytologic, and immunologic studies revealed that the decrease in numbers of organisms between 1 and 2 weeks after inoculation in irradiated mice occurred at a time when their immune response to B abortus was suppressed and when numbers of neutrophils and monocytes infiltrating the spleen were significantly (P < 0.01) diminished. The increase in numbers of B abortus in organs of irradiated mice that began after the third week coincided with recovery of the immune response and an increase in numbers of neutrophils and monocytes in the infected organs. The course of B abortus infection was not substantially altered during the first 11 days after inoculation in mice infected at the height of a profound monocytopenia and neutropenia induced by azathioprine, a drug that by itself failed to activate macrophages. We hypothesized that, in irradiated mice, a rapid radiation-induced activation of resident macrophages to a brucellacidal state was coupled with an absence of newly formed monocytes in which virulent strains of B abortus could establish persistent infection, and that as susceptible monocytes emerged in mice recovering from the effects of irradiation, chronic infection became established.

The assessment of cutaneous microcirculation by laser-Doppler velocimetry (LDV) has been primarily limited to human studies. The purpose of this investigation was to establish normal values in various species and anatomic sites for blood flow, velocity, and volume as determined by LDV. Microcirculation was measured with a laser-Doppler velocimeter in 54 animals, 6 healthy animals from each of 9 species. The standard sites used were the buttocks, convex surface of the ear, metacarpal pad, humeroscapular junction, thoracolumbar junction, ventral portion of the abdomen, dorsal metacarpus (hooved animals), and ventral surface of the tail (horse). Significant differences in blood flow, velocity, and volume were measured between species and sites within species. The ventral portion of the abdomen consistently had the highest relative blood flow across all species except the monkey. Measurements in the canine metacarpal pad had a high SD, possibly indicating the stratum corneum and epidermis to be too thick for LDV. Our findings provide baseline data in several species, with application of LDV in comparative dermatologic research.

To assess the effect of ivermectin on immune function (antibody production), male CD-1 mice were inoculated with an antigen the day after SC administration of ivermectin (0.2 mg/kg of body weight or 20 mg/kg). Responses were evaluated 5 days after inoculation of the antigen. Antibody production against sheep RBC, a T lymphocyte-, macrophage-dependent response, was enhanced by ivermectin treatment (P = 0.00049). In contrast, antibody production against dinitrophenyl-Ficoll, a T lymphocyte-independent, macrophage-dependent response, was not altered by ivermectin treatment. Results indicate that the immunostimulatory properties of ivermectin are associated with altered function of T lymphocytes, in particular, T-helper lymphocytes. The immunomodulating effects of ivermectin may provide an alternative approach for treatment of disease problems involving immunosuppression.

The Escherichia coli heat-stable enterotoxin (STb) is the most prevalent toxin associated with diarrheagenic E coli isolates of porcine origin. Unequivocal biological activity of this toxin has been observed only in swine intestine. In this study, when endogenous protease activity was blocked with soybean trypsin inhibitor, intestinal secretion was stimulated by STb in jejunal loops of rats, mice, calves, and rabbits. Compared with pigs, rats, mice, and calves, rabbits were relatively insensitive to STb. These data demonstrate that the activity of STb is not a species-specific toxic activity; there is species variation in sensitivity to STb, and some common laboratory animals may have potential to be used to measure biological activity Of STb.

Seven monoclonal antibodies (MAB) generated against sporozoites of Eimeria bovis were tested for reactivity against immature and mature first-generation meronts, sexual stages, and oocysts in tissues from experimentally infected calves by use of an avidin-biotin peroxidase complex (ABPC) immunohistologic test. Three of the 7 MAB reacted in the ABPC test. One of these, MAB-4FB4, reacted only with mature E bovis meronts. The other 2 MAB, MAB2AE7 and MAB4AD7, reacted with all the developmental stages of E bovis tested. Asexual stages and sexual stages of E tenella from chickens and E papillata from mice also were examined in the ABPC test. Monoclonal antibodies MAB-2AE7 and MAB-4AD7 reacted with all stages of these eimerian protozoa. None of the other 5 MAB reacted with these parasites. Results of this study suggested that antigens are shared among the asexual and sexual stages of several diverse Eimeria species.

Use of microangiography is now essential for the study of microcirculation in various organs. Renal microangiographic studies have been reported in rats, rabbits, dogs, human beings, and mice. However, we could not find any report on use of the technique in cattle, despite high incidence of renal disease in that species. The perfusion technique used in mice was improved over that of our previous report, and was applied to normal and diseased bovine kidneys. For the microangiographic technique, composition of the contrast medium, pressure of the injection, duration of perfusion, and washing of kidneys with heparinized saline solution before perfusion are important. In cattle, 1- to 2-mm-thick sections of the kidneys were generally necessary to observe renal vasculature: arcuate and interlobular arteries, afferent arterioles, and glomerular capillaries. In normal bovine kidneys, the angiographic and microangiographic findings were easily recognized as normal, compared with those of normal mice. In affected bovine kidneys, which histologically represented glomerulonephritis and pyelonephritis, angiography and microangiography revealed corresponding findings.

Monoclonal antibody (MAb) against Mycoplasma gallisepticum strain PG31 was produced in BALB/c mice. The MAb (designated M9) was of IgG3 isotype and reacted with an epitope in M gallisepticum antigens with molecular weights of 35, 90, 95, and 98 kilodaltons (kDa). The M9 reacted with M gallisepticum antigens in the dot-blot ELISA and in western blot assays. It agglutinated M gallisepticum strains PG31, F, R, S6, A5969, and 9 field isolates from various sources. A coagglutination assay, using Staphylococcus aureus (Cowan strain 1), was developed to enhance the agglutination of some weakly agglutinating M gallisepticum isolates. The M9 did not react with M synoviae, M iowae, M meleagridis, M gallinarum, or M gallinaceum in any of the aforementioned assays. This MAb may be useful in facilitating laboratory diagnosis of M gallisepticum infections.

Mice with a severe combined immunodeficiency in B and T lymphocytes and natural killer cells (SCID-beige) were inoculated intranasally with sialodacryoadenitis (SDA) virus, a coronavirus of rats. Animals were killed at designated intervals and tissues were examined for evidence of viral infection by light microscopy and immunofluorescence microscopy. Based on these criteria, there was no evidence that these immundeficient mice were susceptible to infection with SDA virus.

The beige (bgJ/bgJ) mouse is a well-described murine model of Chediak-Higashi syndrome. Platelet function was examined in normal and beige mice to better characterize the defective aggregation response in platelets from mice with Chediak-Higashi syndrome. Platelet aggregation after collagen, thrombin, and phorbol-12-myristate 13-acetate stimulation was significantly (P < 0.025) decreased in platelets from beige mice, relative to platelets from normal mice. Compared with beige and normal mice, those heterozygous for the bg trait had intermediate responses to collagen and thrombin, but not phorbol-12-myristate 13-acetate. The defect(s) in aggregation of platelets from beige mice was associated with a dense granule storage pool deficiency and decreased stores of serotonin and adenine nucleotides in platelets. Mice heterozygous for the bg trait had normal platelet serotonin and adenine nucleotide concentrations. Platelets from beige mice were approximately 10 times more sensitive to prostacyclin inhibition of collagen-induced aggregation than were platelets from control mice. However, a significant difference in platelet cyclic AMP concentration was not apparent between beige and normal mice after prostacyclin stimulation. Platelet endoperoxide synthesis measured by quantification of thromboxane B2, was normal in beige mice. Protein phosphorylation patterns in mouse platelets were similar to those seen in human platelets. Thrombin and collagen-induced [32P] phosphorylation of 40- and 20-kD proteins in platelets from normal and beige mice was similar. Results indicate that the biochemical defect(s) in platelet function in beige mice is partially attributable to storage pool deficiency and does not result in an absolute defect in phosphorylation of 40- and 20-kD proteins.

Enzyme-linked immunosorbent assay screening of antibody produced against aflatoxin was accomplished by a new and simple procedure. To demonstrate the new indirect ELISA technique used, antibody against aflatoxin M1 was produced in female BALB/CJ mice by immunization with an aflatoxin M1-bovine serum albumin conjugate. Instead of coating test-plate wells with purified antibody (direct ELISA) or synthesizing a second protein-aflatoxin conjugate (aflatoxin M1-poly-L-lysine) to coat test-plate wells, wells were coated with the readily available aflatoxin M1-bovine serum albumin and aflatoxin B1-bovine vine serum albumin. This method, applicable for any aflatoxin conjugated by the common cyclopentano-carboxymethoxyl-oxime technique, eliminates the more time-consuming and technically difficult portions of earlier direct and indirect ELISA. The new technique can be valuable in continued efforts toward development of new and improved immunoassays against aflatoxin metabolites.