Israel Medical Association Journal

Cancer is a multi-step disease involving a series of genetic alterations that result in the loss of control of cell proliferation and differentiation. Such genetic alterations could emerge from the activation of oncogenes and the loss or malfunctioning of tumor suppressor gene activity. Our understanding of cancer has greatly increased through the use of DNA tumor viruses and their transforming proteins as a biological tool to decipher a cascade of events that lead to deregulation of cell proliferation and subsequent tumor formation. For the past ten years our laboratory has focused on the molecular biology of the human neurotropic papovavirus, JCV. This virus causes progressive multifocal Ieukoencephalopathy, a fatal neuro­degenerative disease of the central nervous system in immunocompromised patients. JCV is a common human virus that infects more than 80% of humans but does not induce any obvious clinical symptoms. The increased incidence of acquired immune deficiency syndrome and the use of immunosuppressive chemotherapy have dramatically raised the incidence of PML. The coincidental occurrence of malignant astrocytes and oligodendrocytes in PML patients, coupled with the induction of glioblastoma in JCV-intected non­human primates, provides intriguing speculation on the association between JCV and CNS malignancies. In this report we discuss clinical data and laboratory observations pointing to the direct involvement of JCV in cancer.

Trophic factors such as nerve and fibroblast growth factors are important modulators of 13 cell physiology. These two factors induce the extension of neurite-Iike processes in primary cultures of adult rat 13 cells. Moreover, both NGF and FGF enhance glucose-induced insulin secretion. Since â cells synthesize NGF and pancreatic islet cells produce FGFs, it is possible that autocrine/paracrine interactions may be major regulators of insulin secretion, and impairment of these interactions could lead to pathological states such as diabetes mellitus.

Background: Cholestasis is a frequent problem in patients on total parenteral nutrition. Cisapride has a prokinetic effect on the biliary system, but its effect on hepatic excretory function is unknown.

Objectives: To study the effect of cisapride on TPN-induced cholestasis in a rat model.

Methods: Bile flow and bile salt secretion rate were measured in rats given TPN. There were four groups of 8 to 13 animals each. After a one hour baseline period during which all four groups received i.v. saline infusion, two groups received a TPN solution for another 2 hours, while saline was infused in the two control groups.

At the beginning of the second hour, 2 mg/kg cisapride was injected i.v. as a bolus into one experimental and one control group. Bile was collected from the common bile duct.

Results: At the end of the third hour, TPN caused a significant reduction in bile flow (P<0.02) and bile salt secretion rate (P<0.001) (61.24 vs. 50.74 µl/min/kg, and 1.173 vs. 0.799 µmol/min/kg, respectively). Addition of cisapride abolished the cholestatic effect of TPN.

Conclusions: Cisapride has a protective effect against TPN-associated cholestasis. This may have clinical significance, and further studies are warranted.

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TPN= total parenteral nutrition
 

Objective: To examine to what extent and for how long nedocromil sodium prevents exercise-induced asthma when given immediately before exertion compared to chronic administration.

Patients and Methods: Eighteen asthmatic patients were given 4 mg NS at 30 min or 3.5 hours before exertion. We compared the resultant effect with that of the same protocol measured after 2 and 4 weeks of continuous treatment with the drug.

Results: Nedocromil sodium decreased exercise-induced asthma similarly at both points when given acutely. Chronic treatment of up to 4 weeks did not improve this protective effect at either interval following the inhalation.

Conclusion: Nedocromil sodium most likely reaches its maximal effect on exercise-induced asthma upon the first administration, although treatment for longer than 4 weeks might be required to prove a chronic effect of the drug.