Modulation of glucocorticoid binding to rat liver cytosol receptor by lipid-soluble extracts from the serum of AIDS patients

Role of nonesterified fatty acids in necrotizing pancreatitis: an in vivo experimental study in rats

INTRODUCTION

In acute pancreatitis, nonesterified fatty acids (NEFA) might be released by lipase and cause tissue necrosis by their detergent properties, but this has not been established in vivo.

AIMS

To measure the release of NEFA in the blood stream, pancreatic tissue, and peritoneal cavity during taurocholate-induced acute necrotizing pancreatitis in rats.

METHODOLOGY

Ascites and blood were repeatedly sampled; after 24 hours, pancreatic lesions were scored, and NEFA were measured in the pancreas. The effects of a specific lipase inhibitor (Tetrahydrolipstatin [THL]) were also studied.

RESULTS

A slight transient increase (22%) of NEFA concentration was observed in systemic circulation but did not parallel the time course of lipase activity, arguing against an intravascular production of NEFA by circulating lipase. Pancreatic NEFA did not differ between rats with pancreatitis and control rats. NEFA in ascites increased to threefold the basal value immediately after taurocholate and decreased rapidly thereafter, whereas lipase increased later in ascites and remained elevated during the 24-hour duration of the experiment. Lipase inhibition by THL neither modified the early increase of NEFA in ascites, nor altered the macroscopic, enzymatic, and histologic evolution of pancreatitis.

CONCLUSION

This in vivo study does not confirm the hypothetical role of NEFA produced by pancreatic lipase in the necrotic process and its systemic complications, up to now mainly suggested on the basis of ex vivo experiments.

Release of nonesterified fatty acids during cerulein-induced pancreatitis in rats

During acute pancreatitis, data obtained in vitro suggest that pancreatic lipase, acting on circulating or tissular triglycerides, might generate nonesterified fatty acids (NEFA) that could promote pancreatic and fat tissue necrosis. This work determined whether NEFA were actually produced in vivo in pancreatic tissue and in blood during cerulein-induced pancreatitis in rats. Intraperitoneal injections of cerulein induced pancreatitis. To promote the possible NEFA release by pancreatic lipase, a venous infusion of human very low density lipoprotein (VLDL) was used to cause hypertriglyceridemia. NEFA were measured in portal and aortic blood and in tissue extracts prepared from pancreas homogenates. NEFA did not increase either in peripheral or in portal blood. In pancreatic tissue, NEFA levels did not differ from controls. The major hypertriglyceridemia produced by human VLDL intravenous infusion neither altered the course of the disease nor promoted plasma NEFA release. The role commonly attributed to NEFA in acute pancreatitis seems questionable.

Aetiology and pathogenesis of hormonal and metabolic disorders in HIV infection

Many hormonal and metabolic disturbances are documented in HIV infection, the most important of which is the wasting syndrome associated with progressive HIV infection. We are only now beginning to understand the pathogenesis of these disturbances. In rare cases, infiltration of endocrine tissue by secondary infectious or malignant processes is the underlying cause of hormonal insufficiency. In most instances, however, hypofunction is secondary to the well-known effects of severe illness. Similarly, hyperfunction of the adrenal axis along with many of the derangements in substrate metabolism are also likely to be secondary to severe illness, perhaps through activation of cytokines and other molecules. Specific disturbances in asymptomatic patients are more difficult to document and may represent unique and as yet unexplained manifestations of HIV disease. Hypermetabolism and depletion of lean body mass are most profound in the acutely ill patient with active secondary infection. At this stage, the HIV-infected patient is in a catabolic state and adaptive mechanisms which normally decrease energy expenditure and preserve lean body mass are either overridden or not operative. Strategies to reverse the catabolic state and diminish wasting are only now being developed.