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SUMMARY

A study was conducted to determine the effect of monophosphoryl lipid A (mpl) and trehalose dimycolate (tdm) as adjuvants on the protective responses in balb/c mice vaccinated with Brucella abortus salt-extractable protein (bcsp) or proteinase-K-treated B abortus lipopolysaccharide (pklps). Mice were vaccinated with different doses of bcsp or pklps given alone or in combination with mpl or tdm. Mice were challenge-exposed 4 weeks later with virulent B abortus strain 2308. Two weeks after challenge exposure, the number of B abortus colony-forming units (cfu) per spleen, spleen weights, and spleen cell interleukin 1 production were measured. Serum IgG and IgM concentrations specific for vaccinal immunogens were measured before and after challenge exposure with B abortus.

Spleen weights and mean B abortus cfu per vaccine group were significantly lower in bcsp- and pklps-vaccinated mice, compared with those of nonvaccinated control mice. Monophosphoryl lipid A enhanced the suppression of splenic infection when given with the bcsp vaccine, but not when given with the pklps vaccine. Trehalose dimycolate had no effect on mean cfu when given with bcsp, but incorporation of tdm resulted in a significant increase in mean cfu when given with pklps. Spleen weights in bcsp- or pklps-vaccinated mice were not different when these vaccines were combined with mpl or tdm. Because of the wide variation in the results, we could not conclude that vaccination with bcsp or pklps alone, or in combination with mpl altered spleen cell interleukin-1 production in B abortus-infected mice. Increased host protection as defined by decreased cfu could not be related consistently to increased bcsp- or pklps-specific serum IgG or IgM antibodies introduced by any of the vaccines. These results do not eliminate a role for antibodies in the protection observed.

Free access
in American Journal of Veterinary Research

  • Splenic trauma is a serious, often life-threatening condition in horses.

  • Laparoscopy permits direct observation of the spleen and determination of the location and extent of any lesions, making diagnosis of splenic trauma easier.

  • Laparoscopy may help clinicians choose between splenectomy and conservative treatment for horses with splenic trauma.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Sublethal irradiation of BALB/c mice 4 hours prior to inoculation with 5 × 104 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.

Free access
in American Journal of Veterinary Research

Summary

Two distinct monoclonal antibodies (mab) were prepared for testing with kidney, spleen, and retrobulae tissue imprints made from chinook salmon (Oncorhnchus tshawytscha) affected with plasmacytoid leukemia. (pl). Hybridomas were prepared from mice immunized with whole and lysed cells purified from renal or retrobular pl-positive tissues, which had been obtained from naturally and experimentally infected fish from British Columbia, Canada. The mab reacted with at least 4 morphologically different cell types; of fluorescence was associated with the plasma membrane and cytoplasm. The mab also reacted with kidney imprints made from chinook salmon affected with a pl-like lymphoproliferative disease in California, indicating that these 2 diseases might be caused by a similar agent. The mab did not react with any of the kidney or spleen imprints made from wild chinook salmon collected from a river in Ontario, Canada

Free access
in American Journal of Veterinary Research

Summary

Sixty-eight cattle under general anesthesia were splenectomized. The transthoracic approach was used to provide better access to the spleen and to facilitate ligature of the major splenic vessels. The procedure was easier and less time-consuming, compared with other surgical approaches, and is considered to be less stressful to the animals. Postoperative recovery was complete in 67 of 68 cattle. After surgery, 1 animal developed respiratory tract disease that was thought to have been unrelated to the surgery.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice.

Animals—Female Balb/c mice, 6 to 8 weeks old.

Procedure—Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy.

Results—Measurable splenomegaly was evident at 3 and 7 weeks after inoculation. A demonstrable increase in splenic colony-forming units (CFU) from infected mice increased over time with increasing dose when comparing inocula of 103, 104, and 105 CFU. Recovery of brucellae from the lungs was possible early in infection with 101, 103, and 105 CFU, but only the group inoculated with 105 CFU consistently yielded quantifiable bacteria. At a dose of 101 CFU, few organisms were located in the spleen. Bacteria were recovered up to 140 days after inoculation in mice given 103 CFU. At an inoculum of 105 CFU, bacterial counts were highest early in infection. Histologic examination of tissues revealed an increase in white pulp and marginal zone in the spleen and lymphohistiocytic hepatitis.

Conclusion and Clinical Relevance—Changes in the spleen and liver increased with increases in dose and with increased time following intranasal inoculation with B melitensis 16M. Surprisingly, histologic changes were not observed in the lungs of inoculated mice. (Am J Vet Res 2001;62:398–405)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the induction of cytotoxic T cells in carp (Cyprinus carpio) after inoculation of fish with 2 xenogeneic line cells and to examine specificity of the cytotoxic activity.

Animals—22 carp.

Procedure—Fish were inoculated with mouse myeloma line cells P3.NS-1/1Ag4.1 (NS-1) or chicken Marek's disease tumor-derived lymphoma line cells (MDCC MSB-1). Cytotoxic activity of immune lymphocytes was evaluated by incubating effector cells with homologous and heterologous target cells. Populations of effector cells were identified by blocking T-lymphocytes from effector cells, using anti-carp T-cell monoclonal antibody and complement.

Results—Lymphocytes in blood, spleen, and head kidney of carp inoculated with NS-1 cells or MDCC MSB-1 cells had dose-dependent cytotoxic effects against homologous target cells but not against heterologous target cells. Lymphocytes from noninoculated carp did not have cytotoxic effects. Depletion of Tlymphocytes in spleen cells from NS-1-inoculated carp resulted in a decrease of cytotoxic activity against NS-1 cells. Cytotoxic activity of spleen lymphocytes from NS-1-inoculated or noninoculated carp was not evident when cytotoxic tests were performed after addition of anti-NS-1 carp serum.

Conclusion and Clinical Relevance—Inoculation with xenogeneic target cells induces a specific cytotoxic T-cell response in carp. Thus, cell-mediated immunity plays a role in defense against infection of parasitic organisms such as protozoa and helminths. (Am J Vet Res 2001;62:599–603)

Full access
in American Journal of Veterinary Research

SUMMARY

Visceral leishmaniasis was experimentally induced in hamsters by the intracardiac inoculation of 107 amastigotes of Leishmania leishmania infantum of canine origin. At postinoculation (pi) days 7, 21, 42, and 63, hamsters were euthanatized. Body weights and total parasite numbers of the liver and spleen were determined. Gross and histologic evaluations of tissues were done. Dogs also were inoculated IV with 108 amastigotes/kg of body weight. Samples were obtained from dogs prior to infection and at biweekly pi intervals for CBC and serum chemical analysis, for lymphocyte blastogenic assay by use of blood leukocytes, and for ELISA to determine antileishmanial antibody titers. At pi week 12, dogs were necropsied; organ weights, tissue imprints of the liver and spleen, and histologic interpretations of tissues were obtained.

Hamsters developed high parasite numbers within 7 days after inoculation, at which time the total parasite numbers in the liver (3.51 × 107 amastigotes) was observed to be approximately 11 times that in the spleen (2.93 × 106). The liver had the highest parasite numbers throughout the infection period. Some infected hamsters became either cachectic and emaciated or ascitic. Two of the 10 infected hamsters died at pi days 54 and 58. Moderate to severe hepatosplenomegaly with granulomatous inflammatory reactions characterized by the presence of varied numbers of parasitized macrophages, giant cells, and hepatic Schaumann bodies were observed in infected hamsters. Infected dogs developed significantly altered hematologic values consisting of mild anemia and moderate leukopenia at pi weeks 8 to 12. Hyperproteinemia characterized by hyperglobulinemia (4.5 g/dl) was noticed at pi week 4. Serum globulin values remained high and increased to > 5.0 g/dl at pi weeks 8, 10, and 12. At pi week 4, ELISA titers were > 16. By pi week 12, all infected dogs had titers > 1,024. The dog with the highest antibody titer had the lowest number of parasites and mild pathologic changes. Evidence of lymphoproliferative response was not noticed up to pi week 12. Similarities between infected hamsters and dogs included the presence of higher parasite numbers in the liver than in other organs. The highest total parasite numbers in the spleen and liver were 1.12 × 109 and 2.86 × 109, respectively. Mild to moderate granulomatous inflammatory reactions were observed in the liver, spleen, thymus, and lymph nodes. Within 12 weeks after inoculation, parasitized macrophages were found in the dermis.

The overall results indicate that hamsters are highly susceptible to experimental infection, and that infected hamsters develop findings similar to those in natural human infections. Our findings also indicate that dogs are susceptible and develop high antileishmanial titers that correspond to low parasite numbers. This suggests the possible role of antibody in determining the seriousness of disease.

Free access
in American Journal of Veterinary Research

Summary

During a 5-year period, leiomyosarcoma was diagnosed in 57 dogs. Forty-four dogs were included in the study on the basis of completeness of medical records. All dogs underwent exploratory laparotomy, and dogs were allotted to 4 groups according to primary site of tumor: spleen (16 dogs, median age 10.3 years), stomach/small intestine (13 dogs, median age 10.3 years), cecum (10 dogs, median age 11.8 years), and liver (5 dogs, median age 9 years). All dogs with leiomyosarcoma of the liver had visible metastasis and were euthanatized at surgery. In the other 3 groups, 79% of the dogs had no gross evidence of metastasis at surgery, and 64% survived > 2 weeks. Median survival in these 3 groups was 10 months (range, 1 month to 7 years); 48% died of metastasis, 32% died of unrelated causes, and 16% died of unknown causes. The prognosis in dogs with leiomyosarcoma of the spleen, stomach, small intestine, and especially the cecum is good to excellent if surgery is performed. In dogs with leiomyosarcoma of the liver, the prognosis is poor.

Free access
in Journal of the American Veterinary Medical Association

SUMMARY

Technetium-99m sulfur colloid scintigraphy was used to study alterations of reticuloendothelial function in 7 dogs with experimentally induced biliary cirrhosis and portosystemic shunting. Scintigraphic studies were performed before and 6 weeks after common bile duct ligation. Radiocolloid plasma clearance rate was determined by measuring activity in plasma samples and by analyzing the rate of liver uptake on dynamic scintigraphic image sequences. Percentage of uptake in the liver, spleen, and lungs, as well as the ratio of hepatic-to-extrahepatic uptake, was determined from static equilibrium images. Relative to preoperative values, there were significant decreases in plasma clearance rate, percentage of fiver uptake, and ratio of hepatic-to-extrahepatic uptake and significant increases in percentage of spleen and lung uptake on postoperative studies.

The mechanism of technetium-99m-labeled sulfur colloid extraction by the liver is different from that of other radiocolloids; it does not require active phagocytosis or pinocytosis. Thus, fiver uptake of this tracer principally reflects effective liver blood flow. Portosystemic shunting was documented in these dogs at the time of the postoperative radiocolloid scans, and we believed was responsible for the decrease in liver reticuloendothelial activity. Possible mechanisms for the increased splenic and pulmonary reticuloendothelial activities are discussed.

Free access
in American Journal of Veterinary Research