Intermediate-term toxicity of repeated orally administered doses of the anti-malarial β-artemether in dogs

The artemisinin derivative beta-artemether, an anti-malarial, was evaluated for its toxicity and tolerability in a 2-week, multiple-dose study in dogs. Eight beagle dogs (4 females, 4 males) were given beta-artemether by oral gavage 3 times daily at 45 mg/kg/dosing (a total daily dose-level of 135 mg/kg) for 2 weeks. This beta-artemether dose regime was well tolerated. Body weight changes were normal although feed consumption during the treatment period reduced compared to that of the pre-trial period. Clinical signs were transient spells of soft to liquid feces. On completion of the treatment period, the animals were sacrificed and submitted to a full macroscopic post-mortem examination. Designated organs were weighed and a complete light microscopic examination was performed on 43 selected tissues from 1 animal per sex, and on the liver, kidneys, thymus, mandibular lymph nodes and lungs of the three other animals per sex. Major findings were high liver weight and histopathologic findings of slight diffuse hepatocellular hypertrophy and distal tubular dilatation, together with flattened epithelium, in the kidneys. With the dose regime used in this trial beta-artemether produced no clinical or apparent histopathological signs of neurotoxicity in dogs.     

Toll-like receptor 9 contributes to recognition of Mycobacterium bovis Bacillus Calmette-Guérin by Flt3-ligand generated dendritic cells

Recognition of mycobacteria by the innate immune system is essential for the development of an adaptive immune response. Mycobacterial antigens stimulate antigen presenting cells (APCs) through distinct Toll-like receptors (TLRs) resulting in rapid activation of the innate immune system. The role of TLRs during infection with Mycobacterium bovis Bacillus Calmette-Guérin (BCG) has been evaluated for TLR2 and TLR4 only. Surprisingly, despite the fact that immune stimulatory CpG-motifs have been originally derived from BCG, for the vaccine strain the role of TLR9 has not been addressed before. To identify the set of TLRs involved in the recognition of BCG, we infected bone marrow-derived macrophages and bone marrow-derived dendritic cells (Flt3-ligand generated DCs) from TLR2, TLR3, TLR4, TLR7, TLR9, MyD88 knockout, TLR2/4 and TLR2/4/9 multiple knockout mice. The degree of activation and stimulation was determined by TNFα, IL-6 and IL-12p40 ELISA. Activation of DCs was measured by surface expression of the costimulatory molecule CD86. We observed the most dramatic reduction of the inflammatory response for TLR2-deficient antigen presenting cells. Both macrophages and DCs produce markedly decreased amounts of TNFα and IL-6 in the absence of TLR2 whereas no significant reduction could be observed for TLR3, 4, 7, 9 single TLR-knockouts. However, IL-12 production in DCs appears not exclusively dependent on TLR2 and only in TLR2/4/9-deficient DCs BCG-induced IL-12 is reduced to background levels. Similarly, up-regulation of CD86 is abolished only in TLR2/4/9-deficient DCs supporting a role of TLR9 in the recognition of M. bovis BCG by murine dendritic cells.     

Analysis of proliferating biliary epithelial cells in human liver disease using a monoclonal antibody against DNA polymeraseα

The proliferative activity and ultrastructural characteristics of proliferating biliary epithelial cells were analysed immunohistocytochemically in 39 biopsied liver specimens from patients with acute viral hepatitis, chronic hepatitis and liver cirrhosis using a monoclonal antibody against DNA polymerase (DNA-PA). In acute viral hepatitis with perivenular confluent necrosis, proliferation of typical bile ducts was found frequently in portal areas. In chronic aggressive hepatitis and cirrhosis, ductular proliferation of both typical and atypical forms was found in enlarged portal and periportal areas and in confluent necrotic areas. The number of proliferating biliary epithelial cells that stained positive for DNA-PA was small. There were very few positively stained cells in atypical bile ducts in confluent necrotic areas of cirrhosis. Atypical bile ducts seen in chronic aggressive hepatitis, cirrhosis and acute hepatitis with confluent necrosis were positively stained for both cytokeratins 8 and 19. In cirrhosis, the number of stained biliary epithelial cells in typical bile ducts was larger than the number of such cells in atypical bile ducts (P< 0.01). By electron microscopy, the cells positively stained for DNA-PA were mostly so-called clear cells with irregular nuclei containing coarse nucleoplasm, and a few small cells with scanty cytoplasm and few organelles.     

Evidence that transmitter can be released from regions of the nerve cell other than presynaptic axon terminal: axonal release of acetylcholine without modulation

Release of acetylcholine from isolated preganglionic axons of sympathetic nerve trunk (cervical preganglionic sympathetic branch) of the cat was studied. In response to depolarization (KCl, 48.4 mM) acetylcholine was released into the eserinized Krebs solution. This release was shown to be dependent on extracellular Ca2+. Electrical stimulation (1 Hz) enhanced the release of acetylcholine from the isolated axonal preparation. The release by stimulation proved to be tetrodotoxin-sensitive and Ca2+-dependent. Evidence has been obtained that the acetylcholine released from sympathetic nerve trunks originates from the axon and not from Schwann cells: 5 days after section of the nerve, there was no release in response to stimulation. The release of acetylcholine from the axon is unlike that from axon terminals in that the rate of release cannot be enhanced by the inhibition of Na, K-adenosine 5'-triphosphatase (ouabain 2 X 10(-5) M) and cannot be modulated by noradrenaline (10(-6) M) or by morphine. Furthermore, although isolated nerve trunks took up [3H]choline by a hemicholinium-sensitive process, no radioactivity could be released upon electrical stimulation. It is suggested that the release of acetylcholine is not confined to axon terminals, but that it can be non-synaptically released by depolarization from axons provided Ca2+ is present.     

On the VIP-ergic innervation of the uterotubal junction

Chronic ACTH treatment (3 IU/kg daily for 8 days) caused an increase in wet weight of the interscapular brown adipose tissue (ISBAT) in the rat without affecting the enzyme activities of the cardiac or skeletal muscles or of ISBAT. On the other hand, chronic β-blockade (alprenolol 10 mg/kg daily for 8 days) induced elevated activities in the oxidative enzymes of the ISBAT but not of the muscle tissues measured. Combined ACTH and alprenolol treatment also increased significantly the citrate synthase and malate dehydrogenase activities and protein concentration, but decreased the weight of ISBAT to normal. The results suggest that, although a direct antagonism between the β-blockers and ACTH has not been demonstrated, β-blockers can abolish the ACTH-induced weight gain of the ISBAT.     

The expression of γΔ T cell receptor and the prevalence of primed,activated and IgA-bound T cells in Behçet's syndrome

Mucosal ulceration of the oral, and to a lesser extent genital tissues is an essential feature of Behçet''s syndrome and is associated with changes in the IgA class of immune responses. Indeed, a significant increase in the proportion of cytophilic IgA1 was found in circulating CD8 and CD4 cells (P less than 0.01), with a corresponding decrease in IgA-Fc receptors on these T cells. Furthermore, 30-40% of the cytophilic IgA1 on T cells may have been of the polymeric secretory type and the rest of the monomeric variety. IgA isotype of B cells was also significantly increased (P less than 0.001), without an overall change in circulating B cells. However, a surprising finding was the significant up-regulation of gamma delta T cell receptor in the CD8 (P less than 0.01) in the absence of a change in the proportion of alpha beta T cell receptor. The results suggest that some common microbial antigen might initiate at the mucosal surface an immune defence reaction characterized by T cells with gamma delta receptors and IgA-specific B cells. However, IgA1 bound to circulating T cells may down-regulate the central T cell function.