Pattern of Disease after Murine Hepatitis Virus Strain 3 Infection Correlates with Macrophage Activation and Not Viral Replication

Murine hepatitis virus strain (MHV-3) produces a strain-dependent pattern of disease which has been used as a model for fulminant viral hepatitis. This study was undertaken to examine whether there was a correlation between macrophage activation and susceptibility or resistance to MHV-3 infection. Peritoneal macrophages were isolated from resistant A/J and susceptible BALB/cJ mice and, following stimulation with MHV-3 or lipopolysaccharide (LPS), analyzed for transcription of mRNA and production of interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta), mouse fibrinogen-like protein (musfiblp), tissue factor (TF), leukotriene B4, and prostaglandin E2 (PGE2). Macrophages from BALB/cJ mice produced greater amounts of IL-1, TNF-alpha, TGF-beta, leukotriene B4, and musfiblp following MHV-3 infection than macrophages from resistant A/J mice, whereas in response to LPS, equivalent amounts of IL-1, TNF-alpha, TGF-beta, and TF were produced by macrophages from both strains of mice. Levels of mRNA of IL-1, TNF-alpha, and musfiblp were greater and more persistent in BALB/cJ than in A/J macrophages, whereas the levels and kinetics of IL-1, TNF-alpha, and TF mRNA following LPS stimulation were identical in macrophages from both strains of mice. Levels of production of PGE2 by MHV-3-stimulated macrophages from resistant and susceptible mice were equivalent; however, the time course for induction of PGE2, differed, but the total quantity of PGE2 produced was insufficient to inhibit induction of musfiblp, a procoagulant known to correlate with development of fulminant hepatic necrosis in susceptible mice. These results demonstrate marked differences in production of inflammatory mediators to MHV-3 infection in macrophages from resistant A/J and susceptible BALB/cJ mice, which may explain the marked hepatic necrosis and fibrin deposition and account for the lethality of MHV-3 in susceptible mice

RNase L Mediated Protection from Virus Induced Demyelination

IFN-α/β plays a critical role in limiting viral spread, restricting viral tropism and protecting mice from neurotropic coronavirus infection. However, the IFN-α/β dependent mechanisms underlying innate anti-viral functions within the CNS are poorly understood. The role of RNase L in viral encephalomyelitis was explored based on its functions in inhibiting translation, inducing apoptosis, and propagating the IFN-α/β pathway through RNA degradation intermediates. Infection of RNase L deficient (RL−/−) mice with a sub-lethal, demyelinating mouse hepatitis virus variant revealed that the majority of mice succumbed to infection by day 12 p.i. However, RNase L deficiency did not affect overall control of infectious virus, or diminish IFN-α/β expression in the CNS. Furthermore, increased morbidity and mortality could not be attributed to altered proinflammatory signals or composition of cells infiltrating the CNS. The unique phenotype of infected RL−/− mice was rather manifested in earlier onset and increased severity of demyelination and axonal damage in brain stem and spinal cord without evidence for enhanced neuronal infection. Increased tissue damage coincided with sustained brain stem infection, foci of microglia infection in grey matter, and increased apoptotic cells. These data demonstrate a novel protective role for RNase L in viral induced CNS encephalomyelitis, which is not reflected in overall viral control or propagation of IFN-α/β mediated signals. Protective function is rather associated with cell type specific and regional restriction of viral replication in grey matter and ameliorated neurodegeneration and demyelination

Liver Transplants for Alcoholic Liver Disease

Alcohol related end-stage liver disease is a principal cause of liver failure. The scarcity of donor livers and the predominance of alcohol related end-stage liver disease has raised the issue of including alcoholics as candidates for liver transplantation. In rationalizing the arguments for and against the treatment of alcoholic end-stage liver disease with transplantation, factors such as recidivism, resource allocation and principles of medical practice must be considered. Public confidence in organ transplantation depends on the scientific validity and moral integrity of the policies adopted. Sound policies will prove defensible while policies based on perceptions or prejudices will, in the long run, harm the process

Aortoenteric Fistula Assocaited with Acute Myocardial Infarcation

A 64-year-old male with a prior abdominal aortic graft for lower limb ischemia presented with melena and myocardial infarction. Despite aggressive investigation, an aortoenteric fistula was not diagnosed until after massive gastrointestinal hemorrhage. The patient's myocardial infarction may have heen precipitated by hypotension induced by hemorrhage through the aortoenteric fistula. Patients with prior abdominal aortic graft surgery presenting with gastrointestinal bleeding, abdominal pain or occult sepsis need to be aggressively investigated to determine whether an aortoenteric fistula is present. Laparotomy should be done in such patients if no cause for these symptoms can be determined

Update in Small Bowel Physiology: Part 2

The recent advances in clinically important diseases of the small intestine have been reviewed however, the basis for many of these clinical advances rests with important observations on alterations in the physiology of the small intestine, as well as mechanistic observations of alterations in small 1nrestinal function in models of human disease. In this review a summary of the past year's literature is presented which will draw attention to the considerable progress in small bowel physiology which will soon be translated into an improved understanding of the pathophysiology of a variety of intestinal disorders