Tonic Shock Induces Detachment of Giardia lamblia

The single-celled organism Giardia lamblia colonizes the small intestine of a wide variety of hosts, including humans. Giardiasis infections can cause severe gastrointestinal symptoms and pose a major health concern in the developing world. Giardia are known to attach robustly to a variety of surfaces, but the conditions that influence this attachment are not known. In this study, we examined the behavior of attached Giardia parasites exposed to rapid changes in solution properties, like those Giardia might encounter in the intestine. After systematically varying media concentration and composition, we found that only one solution property caused rapid detachment of Giardia cells: tonicity, which is a measure of the total concentration of solutes in the solution that are unable to pass through a semi-permeable membrane (here, the cell membrane of Giardia). We found similar results for Giardia initially attached to monolayers of intestinal cells. Giardia cells remaining attached after a change in tonicity are able to adapt to the change, highlighting the general ability of this organism to weather normal changes in the intestinal environment. We propose that Giardia's susceptibility to large changes in tonicity could be explored as a possible new route for treatment of giardiasis

First Evaluation of [11C]R116301 as an In Vivo Tracer of NK1 Receptors in Man

PURPOSE: NK1 receptors have been implicated in various neuropsychiatric and other disorders. R116301 is a selective NK1 receptor antagonist. In this pilot study, [(11)C]R116301 was evaluated as a potential positron emission tomography (PET) ligand for the NK1 receptor. PROCEDURES: Two dynamic PET studies were performed in three normal volunteers before and after a blocking dose of aprepitant. Data were analyzed using striatum to cerebellum standardized uptake value (SUV) ratios. RESULTS: Baseline SUV ratios at 60-90 min after injection ranged from 1.22 to 1.70. Following aprepitant administration, this specific signal was completely blocked. Aprepitant administration did not significantly affect uptake in cerebellum, confirming the absence of NK1 receptors in cerebellum. CONCLUSION: These preliminary results indicate that [(11)C]R116301 has potential as a radioligand for in vivo assessment of NK1 receptors in the human brai

Management of primary biliary cirrhosis

Primary biliary cirrhosis is a slowly progressive cholestatic liver disease with autoimmune features. Antimitochondrial antibodies are detected in the serum of 95 percent of patients. The antibodies are directed against the E2 component of the pyruvate dyhydrogenase complex on the inner mitochondrial membrane, Fatigue, pruritus and bone pain are the most troublesome complaints which affect the quality of life of these patients. Ursodeoxycholic acid therapy has been shown to improve laboratory values, symptoms and in some trials also the liver histology. An influence on survival has not been proved. New trials are being conducted where ursodeoxycholic acid is combined with immunosuppressive, antiinflammatory or antifibrotic drugs. Prognostic models have been developed that help in the planning of liver transplantation. As primary biliary cirrhosis probably can recur in the transplanted liver its clinical relevance in the long-run needs to be assessed

Antisecretory drugs for diarrheal disease

Acute diarrhea is a major cause of morbidity and mortality worldwide. Infants and pre-school children are the most vulnerable in whom there are 2–3 million deaths each year as a result of the associated dehydration and acidosis. Although oral rehydration therapy has reduced mortality during the past 30 years ago, the search for agents that will directly inhibit intestinal secretory mechanisms and thereby reduce faecal losses in patients with high-volume watery diarrhea has continued for more than 20 years. A variety of potential targets for antisecretory agents have been explored which include loci within the enterocyte (the chloride channel, calcium-calmodulin) and other sites such as enteric nerves and endogenous mediators (such as 5-HT, prostaglandins). Although the potential of calcium-calmodulin inhibition has as yet not been realised, preliminary studies suggest that there are chloride channel blockers under development that will find a place in the management of secretory diarrheas. Recent work has highlighted the importance of neurohumoral mechanisms in the pathogenesis of acute diarrhea. Potentiation of the effects of endogenous enkephalin activity by enkephalinase inhibition has already produced a safe, effective anti-secretory drug, racecadotril. Speculative early work indicates that there may be a role for antagonists of 5-HT, substance P, and VIP receptors. There now seems to be a real possibility that antisecretory therapy will become more widely available in the future