Glutathione and tissue amino acid responses to light-exposed parenteral nutrients.

Effects of infusion of light-exposed (+L) or light-protected (-L) total parenteral nutrition solutions were investigated in rats. The parenteral infusions were carried out for 7 days through jugular cannulas in freely moving rats in metabolic cages. Plasma tyrosine and citrulline, hepatic methionine, valine, isoleucine, leucine and tyrosine, and biliary cystathionine were significantly greater in the -L than +L rats, whereas biliary arginine was significantly lower in the -L compared to +L rats. Bile flow, biliary inorganic phosphate and glucose were significantly lower, whereas biliary total glutathione (GSH+GSSG) was significantly greater in the -L compared to +L animals. These data suggest adverse effects on hepatobiliary function due to light exposure of parenteral nutrients. The endogenous markers used suggest that tight junction permeability, bile acid-independent flow, glutathione and amino acid homeostasis are altered by light exposure and that these changes can be minimized by light protection. The mechanisms involved in the induction of these changes need to be elucidated. The role of light exposure of parenteral nutrients during routine clinical use in the induction of hepatic dysfunction, a common metabolic complication of parenteral nutrition, needs to be considered.     

Fatty acid ethyl and methyl ester synthases, and fatty acid anilide synthase in HepG2 and AR42J cells: interrelationships and inhibition by tri-o-tolyl phosphate.

Synthesis of fatty acid ethyl esters (FAEEs), fatty acid methyl esters (FAMEs), and fatty acid anilides (FAAs) in humans and/or experimental animals and in vitro have been reported by us and other investigators. In previous studies, we have demonstrated that fatty acid ethyl ester synthase (FAEES), purified from rat liver microsomes, is structurally and functionally identical to the rat liver microsomal carboxylesterase (pI 6.1) and suggested a role in the conjugation of a variety of xenobiotic alcohols with endogenous fatty acids (B. S. Kaphalia, R. R. Fritz, and G. A. S. Ansari, Chem. Res. Toxicol. 11, 211-218, 1997). However, hepatic FAEES was found to be structurally and functionally different from that of pancreas. Therefore, the present study was undertaken to determine structural and functional interrelationships among the enzyme(s) involved in the synthesis of FAEEs, FAMEs, and FAAs, in HepG2 and AR42J cells using tri-o-tolyl phosphate (TOTP), a specific inhibitor for beta-esterases. Synthesis of FAEEs, FAMEs, and FAAs, studied in the HepG2 cells, was found to be dose- and time-dependent following incubation with methanol, ethanol, or aniline, respectively. Approximately 86-90% inhibition of FAEE, FAME, and FAA synthesizing activities was found in HepG2 cells following exposure to 2.5 microM TOTP. Identical profiles of dose- and time-dependent inhibition of FAEE, FAME, and FAA synthesizing activities by TOTP in HepG2 cells suggest that synthesis of FAEEs, FAMEs, and FAAs is catalyzed by the same enzyme(s). However, FAEE, FAME, and FAA synthesizing activities in AR42J cells could not be inhibited by TOTP under similar experimental conditions. A differential pattern of p-nitrophenyl acetate hydrolyzing activity (a measure of esterase activity) similar to that of fatty acid ester/anilide synthesizing activities was observed in the two cell lines. These results are further substantiated by the presence of approximately 60 kDa (subunit molecular weight) protein in the postnuclear fraction of HepG2 but not in AR42J cells by Western blot analysis using antibodies raised against FAEES, purified from rat liver microsomes or adipose tissue. Therefore, the enzyme responsible for the FAEE, FAME, or FAA synthesizing activities is most probably carboxylesterase in HepG2 cells and is structurally and functionally different than that present in AR42J cells. These studies also indicate the utility of HepG2 and AR42J cell cultures as an alternative to the animal model regarding studies on nonoxidative metabolism of alcohols and amines, in general.     

Selective pancreatic toxicity of palmitoylpentachlorophenol

Palmitoylpentachlorophenol (PPCP), which is a lipid conjugate of a xenobiotic compound, has been found in human fat. To study the toxicity associated with PPCP, rats were given 100 mg/kg PPCP and sacrificed at 4, 8 and 12 days. The target organ identified was the exocrine pancreas; no other major organs examined showed any gross or histopathological abnormality. At 4 and 8 days after treatment, focal, spotty vacuolation, and loss of pancreatic acini was observed. Acute inflammatory infiltrate was also observed in parenchyma at all time points and the loss of acinar tissue was resolved through fibrous tissue formation by 12 days. The present study indicates that PPCP has a specific target organ toxicity.     

Epidemiology of sporadic bloody diarrhea in rural Western Kenya

We conducted laboratory-based surveillance and a case-control study to characterize the epidemiology of bloody diarrhea in rural Western Kenya. From May 1997 through April 2001, we collected stool from 451 persons with bloody diarrhea presenting to four rural clinics. Cultures of 231 (51%) specimens yielded 247 bacterial pathogens: 198 Shigella (97 S. flexneri, 41 S. dysenteriae type 1, 39 S. dysenteriae type non-1, 13 S. boydii, 8 S. sonnei), 33 Campylobacter, 15 non-typhoidal Salmonella, and 1 Vibrio cholerae O1. More than 90% of the isolates (excluding Campylobacter) were resistant to trimethoprim-sulfamethoxazole and tetracycline, and more than 80% were resistant to ampicillin. Most (74%) ill persons received medication to which their isolate was resistant. Drinking Lake Victoria water and sharing latrines between multiple households increased risk of bloody diarrhea. Washing hands after defecating was protective. Providing safe drinking water and more latrines, and promoting hand washing could reduce the burden of illness from bloody diarrhea while limiting injudicious antimicrobial use.     

Acute pancreatitis as the road to diagnosis of primary hyperparathyroidism

The authors present the case of a 78-year-old female patient who was admitted on account of acute pancreatitis complicated by acute myocardial infarction. The authors detected in the patient a serum repeatedly high calcium levels and high levels of intact parathormone. Scintigraphic examination revealed marked foci in the middle of the neck at the level of the inferior pole of the thyroid gland. These examinations confirmed the diagnosis of primary hyperparathyroidism. In view of the patient a serious condition, conservative treatment of hypercalcaemia and acute pancreatitis and myocardial infarction was started. The patient was released into domiciliary care after 40 days in hospital in a state of cardiopulmonary compensation, with cystic transformation of the pancreas and without signs of acute pancreatitis.     

A chimeric TCR-beta chain confers increased susceptibility to EAE

Autoreactive myelin-specific CD4(+) T cells play an important role in CNS demyelination observed in MS and EAE. Consequently, it is important to understand the mechanisms of T cell receptor signalling leading to the activation of autoreactive T cells. We have previously generated a chimeric T cell receptor beta-chain (betaIII) displaying increased antigen sensitivity by exchanging most of the transmembrane and the intracellular domain of the TCR-beta chain with the corresponding TCR-gamma sequence. To investigate the effect of this "super-signalling" TCR in an autoimmune setting, we generated MOG(35-55) specific TCR transgenic mice expressing either the wild-type or the chimeric betaIII TCR-beta chain. We found that na?ve transgenic T cells expressing the chimeric betaIII chain proliferated more extensively than wild-type cells in response to MOG(35-55)in vitro. Likewise, betaIII T cells skewed into a TH1 phenotype maintained the proliferative advantage over wild-type TH1 T cells at low antigen concentration. However, when skewed into a TH2 phenotype, there was no difference in proliferation between wild-type and betaIII T cells. Blocking of Fas-mediated cell death evenly affected wild-type and betaIII TH1 T cells and resulted in increased proliferation of both subsets, suggesting that betaIII T cells did not show defective Fas-FasL signalling. Finally, we found that betaIII TCR transgenic mice are more susceptible to EAE than wild-type TCR transgenic mice. We conclude that the change in the transmembrane domain of the TCR-beta chain affects TH1 T cells and the susceptibility to EAE, but does not affect TH2 cells. Investigating the molecular interaction within the TCR complex will help us to identify signalling pathways that can be manipulated to stop the progression of MS.