Chemopreventive efficacy of lycopene on 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis.

The chemopreventive efficacy of lycopene on 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis was examined using lipid peroxidation, reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR) as biomarkers of chemoprevention. Twenty four male Syrian hamsters were divided into four groups of six animals each. The right buccal pouches of the animals in group 1 were painted with a 0.5% solution of DMBA in liquid paraffin three times a week. The animals in group 2 were painted with DMBA as in group 1 and in addition received 2.5 mg/kg body weight lycopene orally three times a week on days alternate to DMBA application. Group 3 animals received lycopene as in group 2. Animals in group 4 received neither DMBA nor lycopene and served as control. The hamsters were killed after an experimental period of 14 weeks. Biochemical measurements were carried out in tumour and normal tissues. All hamsters painted with DMBA alone for 14 weeks developed well-differentiated squamous cell carcinomas. Diminished lipid peroxidation in the oral tumour tissue was accompanied by a significant increase in the levels of GSH, GPx, GST and GR. Administration of lycopene significantly suppressed DMBA-induced oral carcinogenesis as revealed by the absence of carcinomas. The results of the present study suggest that lycopene may exert its chemopreventive effects by modulating lipid peroxidation and enhancing the activities of the enzymes in the glutathione redox cycle.     

P‐20 Clinical,cytopathological and histopathological evaluation of sporotrichosis in experimentally infected cats

The purpose of this study was to evaluate the clinicopathological aspects of experimental sporotrichosis in cats and compare the sensitivity of cytopathology, histopathology and culture as diagnostic tools in different phases of the infection. Twenty adult, mixed‐breed cats (10 males and 10 females) were inoculated subcutaneously with 10⁶ fungal microorganisms. Clinical examination was performed weekly. Cytopathologic, histopathologic and culture examinations were performed at 15, 30 and 60 days postinoculation. Culture of multiple organs was performed after euthanasia at 30 (10 cats) and 60 (10 cats) days postinoculation. Friedman parametric and nonparametric statistical analysis were applied to the results. The nodular, tumoral and necrotic lesionsprogressed significantly until day 30 postinoculation, and partial spontaneous regression occurred at day 60, particularly in males. An intense inflammatory pyogranulatomous and lymphocytic infiltrate with rare giant cells and sparse fibrosis associated with numerous, pleomorphic, intra‐ and extracellular fungal cells were observed on day 30. These findings gradually decreased by day 60. Despite the inflammatory granuloma associated with feline sporotrichosis, a tendency for dissemination was observed, with fungal isolation in the lymph nodes, spleen and liver at the 30 and 60 days postinoculation. No significant differences were observed between cytopathology, histopathology and fungal culture during the different phases of the disease. Therefore, cytological examination was considered a simple, rapid and inexpensive diagnostic method at all stages of this disease. Funding: Self‐funded.     

Adrenergic and peptidergic innervation of the trachealis muscle in the normal horse: a preliminary report

The tone of respiratory smooth muscle is largely determined by the input from autonomic nerves. The distribution of adrenergic and selected nonadrenergic, non-cholinergic (NANC) nerves in the normal equine trachealis muscle was investigated using immunohistochemistry. The smooth muscle of the trachealis was found to contain numerous nerves immunoreactive for an enzymatic marker of adrenergic nerves, as well as many nerves immunoreactive for a putative NANC neurotransmitter, peptide histidine isoleucine, a potent bronchodilator. The tissues surrounding the respiratory smooth muscle contained numerous nerves immunoreactive for the neuropeptides substance P and calcitonin gene-related peptide, which can cause marked vasodilation and bronchoconstriction. The complex innervation of the equine trachea should be kept in mind when interpreting the results of physiological experiments.     

Distribution of calcium in peat deposits of the central part of Western Siberia

Distribution patterns of calcium in peat deposits of seventeen bogs in the middle and southern taiga of Western Siberia have been studied. Four types of Ca distribution patterns related to the genesis of peat deposits are specified. Up to three Ca-enriched peat layers are distinguished in thick deposits. This Ca distribution pattern is typical of different peat deposits formed under various conditions. It is shown that Ca accumulation in particular layers of peat deposits is related to the warm stages of the Holocene.     

Pasteurella haemolytica A1 and Bovine Respiratory Disease: Pathogenesis

The severe fibrinonecrotic pneumonia associated with pneumonic pasteurellosis usually results from colonization of the lower respiratory tract by Pasteurella haemolytica biotype A, serotype 1(A1). Despite recent research efforts, the authors lack a detailed understanding of the interactions and host response to P. haemolytica in the respiratory tract. The authors hypothesize that management and environmental stress factors or viral infection alters the upper respiratory tract (URT) epithelium allowing P. haemolytica to colonize the epithelium. Once the URT is colonized, large numbers of organisms enter the lung where they interact with alveolar macrophages. Endotoxin, released from the bacteria, crosses the alveolar wall where it activates pulmonary intravascular macrophages, endothelium, neutrophils, lymphocytes, platelets, complement, and Hageman factor leading to complex interactions of cells and mediators. It is the progression of this inflammatory response with neutrophil influx that is ultimately responsible for the pulmonary injury. Leukotoxin is a major virulence factor of P. haemolytica that allows it to survive by destroying phagocytic cells. At subcytolytic concentrations it may also enhance the inflammatory response by activating cells to produce mediators and release reactive oxygen metabolites and proteases.     

Specificity of the carbon immunoassay (CIA) test for the diagnosis of Toxoplasma infections.

A rapid and low cost procedure, the carbon immunoassay (CIA) test, was evaluated for the diagnosis of Toxoplasma gondii infections. Using a closely related parasite (Besnoitia jellisoni) as antigen, and homologous or heterologous immune sera, it was demonstrated by light and electron microscopy that CIA is a very reliable and specific test. As it is neither expensive nor time-consuming, it can be recommended for general and routine laboratory use.     

Teratological examination of the insecticide methyl-parathion (Wofatox 50 EC) on pheasant embryos. 2. Biochemical study.

Fertile pheasant's eggs were treated with the insecticide Wofatox 50 EC (50% methyl-parathion) by injection technique on day 12 of the hatching period. Treatment consisted of inoculation of 0.1 ml of different concentrations of the insecticide into the air space of embryonated eggs. The following dose levels were employed: 0.00, 1.35, 13.5 and 135.0 mg/kg egg of active ingredient. Biochemical changes in the plasma were evaluated by micro (photometric) methods which rendered possible the determination of several blood plasma variables of the embryos. At the highest dose level applied, serum alkaline phosphatase (SAP) enzyme activity and inorganic P concentration of the treated embryos showed statistically differences (reduction) as compared to the control data. Macroscopic alterations were detected at necropsy.     

Effects of Pasteurella haemolytica A1 leukotoxin on bovine neutrophils: degranulation and generation of oxygen-derived free radicals.

To further define the role of Pasteurella haemolytica A1 leukotoxin in the pathogenesis of bovine pneumonic pasteurellosis, its in vitro effects on bovine neutrophils were investigated. Leukotoxin-containing culture supernatant, from P. haemolytica, stimulated a neutrophil respiratory burst as measured by the generation of oxygen-derived free radicals O2- and H2O2. This effect was immediate because preincubation of neutrophils with the culture supernatant for 5 min or longer substantially suppressed this respiratory burst. This suppression was due to cytolysis of the neutrophils. Prolonged incubation of neutrophils with the same culture supernatant caused further cytolysis and degranulation. Heat-inactivated P. haemolytica culture supernatant that had lost its cytotoxic properties failed to stimulate respiratory burst by neutrophils. Furthermore, the respiratory burst, cytolysis and degranulation were abrogated only by leukotoxin-neutralizing monoclonal and polyclonal antibodies, but not by antibodies against the lipopolysaccharide. These studies show that the leukotoxin component in the culture supernatant was responsible for the generation of oxygen-derived free radicals and proteolytic enzymes from neutrophils which may participate in direct lung injury.     

Genetic analysis of bovine respiratory disease in beef calves during the first year of life.

The prevalence of bovine respiratory disease (BRD) was assessed in a population of 10,142 beef calves representing nine pure breeds and three composite populations born in 1983 through 1988. Twenty-four percent of the calves experienced at least one episode of respiratory disease during the 1st yr of life; frequencies over the six birth years ranged from 14 to 38%. The timing of respiratory disease outbreaks differed among birth years; in 4 of the 6 yr, more illness occurred in the pasture before weaning than in the feedlot after weaning. Frequencies of BRD during preweaning and postweaning periods were analyzed separately. Pure breeds and composite populations within a single preweaning location differed in frequency of illness during the preweaning period. However, not all possible breed comparisons could be made because preweaning location differed for the breed groups, and preweaning location had a significant effect on the frequency of respiratory disease in the preweaning period. The preweaning location effect did not carry through to the postweaning period. Pinzgauers had the highest BRD frequency within the feedlot (24.6%). The heritability estimates of BRD during the preweaning and postweaning periods did not differ significantly from 0 (.10 +/- .02 and .06 +/- .07, respectively). Although it is likely that response to selection for resistance to BRD would be slight using the animal's history of BRD as the selection criterion, including information on relatives or additional immune traits may improve the accuracy of an estimated breeding value for BRD resistance.