Journal of comparative pathology
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Four groups (A, B, C and D) of 10 naïve rats were used to compare the virulence of isolates of a strain of Trypanosoma brucei before and after the development of diminazene aceturate resistance. Group A rats were uninfected (controls). Group B rats were infected with a trypanosome isolate unexposed to the drug, while groups C and D rats were infected with two different drug-resistant isolates of the same strain. ⋯ The parasitaemic periods in groups B, C and D were similar, but group C and D rats differed from group B rats in surviving longer, and in showing lower degrees of parasitaemia, anaemia and hepatomegaly. No differences were noted between group C and D rats. Thus, diminazene aceturate resistance appeared to reduce the virulence of T. brucei.
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Macrophages infiltrating injured tissue play an important part in fibrogenesis. To shed light on the functional roles of macrophages, we investigated the appearance of macrophage populations in thioacetamide (TAA)-induced rat hepatic lesions, with or without pretreatment with GdCl(3), a chemical capable of inhibiting Kupffer cell functions. In the GdCl(3)+TAA group rats received a single intraperitoneal injection of GdCl(3) (7.5mg/kg body weight) and, after 24h, a single intravenous injection of TAA (300mg/kg body weight). ⋯ By RT-PCR, the expression of TGF-beta1 mRNA was suppressed on PTI days 3 and 7 in the GdCl(3)+TAA group, and the suppressed expression was confirmed in vitro by treating rat macrophage-like cells (HS-P) with 1% GdCl(3). The study showed that GdCl(3) treatment decreased the numbers of macrophages appearing in hepatic lesions and inhibited TGF-beta1 mRNA expression in macrophages. Decreased numbers of macrophages may contribute to improvement of hepatic fibrosis.
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Macrophages may play a role in fibrogenesis. The kinetics and distribution of different macrophage populations were investigated immunohistochemically in hepatic lesions following acute hepatocyte injury induced in F344 rats by a single injection of thioacetamide (TAA) (300 mg/kg body weight, intraperitoneally). Hepatocyte degeneration or necrosis induced by TAA occurred mainly in the perivenular areas of hepatic lobules as early as post-injection (PI) days 1 and 3; fibrotic lesion development began in the damaged areas on day 1, and peaked on day 5; thereafter (PI days 7 and 10), the fibrotic areas decreased and were replaced by regenerated hepatocytes on PI days 15 and 20, indicating a remodelling process. ⋯ ED1- and OX6-positive cells appeared exclusively in the injured perivenular areas, whereas ED2-positive cells were present mainly in the mid-zonal areas and in smaller numbers in the perivenular areas. These findings indicated differences in kinetics and distribution between macrophage populations appearing in hepatic fibrosis. In addition, RT-PCR revealed that mRNA expression of osteopontin, a factor for induction and maintenance of macrophages in inflammation, was markedly increased on PI days 5, 7 and 10, suggesting a role in the pathogenesis of hepatic fibrosis.
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Collagenase was injected into the Achilles tendon of both hind legs of 10 clinically normal adult male New Zealand white rabbits. One month after induction of the injury, beta-aminoproprionitrile (BAPN) or hyaluronic acid (HA) was injected into the tendon core of the right hind leg of each rabbit, the left hind leg being left untreated. The treatment effects were evaluated by electron microscopy and analysis of the glycosaminoglycan (GAG) content of samples at 2 and 6 months post-treatment. ⋯ At 6 months, BAPN-treated tendons had small-diameter, regularly arranged collagen fibrils. HA-treated tendons, on the other hand, had large diameters, as well as regularly arranged collagen fibrils by comparison with non-treated tendon. The results suggest that HA, unlike BAPN, promoted healing.
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The neuropathological changes produced by a captive bolt pistol are described. The primary wound track in the brain was similar to that inflicted by a weapon such as a .22 calibre rifle. However neural and vascular damage at a distance from the primary wound canal was much less severe and widespread after penetration of the low velocity captive bolt projectile due to the formation of a smaller temporary wound cavity by radial forces imparted to the parenchyma. These findings suggest that the use of a captive bolt pistol for euthanasia should be immediately followed by further actions to ensure that an animal is rendered permanently unconscious.