Computational fluid dynamic (CFD) simulations of the three-dimensional flow structures in realistic cystic ducts have been performed to obtain quantitative readings of the flow parameters to compare with clinical measurements. Resin casts of real patients' cystic ducts lumen that possess representative anatomical features were scanned to obtain three-dimensional flow domains that were used in the numerical analysis. The convoluting nature of the studied cystic ducts resulted in strong secondary flow that contributed towards a dimensionless pressure drop that is four times higher than those of a straight circular tube of an equivalent length and average diameter. The numerical pressure drop results across the cystic duct compared very well with those obtained from clinical observations which indicate that CFD is an appropriate tool to investigate the flow and functions of the biliary system. From the hydrodynamic point of view, the cystic duct lumen seems to serve as a passive resistor that strives to provide a constant amount of resistance to control the flow of bile out of the gallbladder. This is mainly achieved by the coupling of the secondary flow effects and bile rheology to provide flow resistance.
Certain arsenic and selenium compounds show a remarkable mutual cancelation of toxicities, where a lethal dose of one can be voided by an equimolar and otherwise lethal dose of the other. It is now well established that the molecular basis of this antagonism is the formation and biliary excretion of seleno bis-(S-glutathionyl) arsinium anion [(GS)2AsSe](-). Previous work has definitively demonstrated the presence of [(GS)2AsSe](-) in rabbit bile, but only in the presence of other arsenic and selenium species. Rabbits have a gall bladder, which concentrates bile and lowers its pH; it seems likely that this may be responsible for the breakdown of biliary [(GS)2AsSe](-). Since rats have no gall bladder, the bile proceeds directly through the bile duct from the hepatobiliary tree. In the present work we have shown that the primary product of biliary co-excretion of arsenic and selenium in rats is [(GS)2AsSe](-), with essentially 100% of the arsenic and selenium present as this species. The chemical plausibility of the X-ray absorption spectroscopy-derived structural conclusions of this novel arsenic and selenium co-excretion product is supported by density functional theory calculations. These results establish the biomolecular basis to further explore the use of selenium dietary supplements as a possible palliative for chronic low-level arsenic poisoning of human populations.
This study investigated the dose-dependent and time-course effects of intramuscular (i.m.) and intraperitoneal (i.p.) injection of benzo[a]pyrene (BaP) on the biomarkers EROD activity, GST activity, concentrations of BaP metabolites in bile, and visceral fat deposits (Lipid Somatic Index, LSI) in African catfish (Clarias gariepinus). Intraperitoneal injection resulted in 4.5 times higher accumulation of total selected biliary FACs than i.m. injection. Hepatic GST activities were inhibited by BaP via both injection methods. Dose-response relationships between BaP injection and both biliary FAC concentrations and hepatic GST activities were linear in the i.p. injected group but nonlinear in the i.m. injected fish. Hepatic EROD activity and LSI were not significantly affected by BaP exposure by either injection route. We conclude that i.p. is a more effective route of exposure than i.m. for future ecotoxicological studies of PAH exposure in C. gariepinus.
In this study we sought to optimize recovery of fluorescent aromatic compounds (FACs) from the bile of African catfish (Clarias gariepinus) injected with 10mg/kg benzo[a]pyrene (BaP). Fractions of pooled bile were hydrolyzed, combined with ten volumes of methanol, ethanol, acetonitrile, or acetone, centrifuged and supernatants were analyzed by high-performance liquid chromatography with fluorescent detection (HPLC/FL). As well, to test whether FACs were being lost in solids from the centrifugation, pellets were resuspended, hydrolyzed and mixed with six volumes of the organic solvent that produced best FAC recovery from the supernatant, and subjected to HPLC/FL. Highest FAC concentrations were obtained with 2000μl and 1250μl acetone for supernatants and resuspended pellets respectively. FACs concentrations were negatively correlated with biliary protein content but were unaffected by addition of bovine serum albumin (BSA) followed by no incubation indicating that the presence of proteins in the biliary mixture does not simply interfere with detection of FACs. In another experiment, efficiency of acetone addition was compared to two different liquid-liquid extractions (L-LEs). Acetone additions provided significantly higher biliary FACs than the L-LE methods. The new two-stage bile preparation with acetone is an efficient, inexpensive and easily performed method.
Lactobacillus acidophilus is categorized as a probiotic strain because of its beneficial effects in human health and prevention of disease transmission. This study is aimed to characterize the probiotic potential of L. acidophilus 36YL originally isolated from the vagina of healthy and fertile Iranian women. The L. acidophilus 36YL strain was identified using 16S rDNA gene sequencing and characterized by biochemical methodologies, such as antibiotics susceptibility, antimicrobial activity, and acid and bile resistance. The bioactivity of the secretion of this strain on four human cancer cell lines (AGS, HeLa, MCF-7, and HT-29) and one normal cell line (HUVEC) was evaluated by cytotoxicity assay and apoptosis analysis. This newly isolated strain was found to exhibit notable probiotic properties, such as admirable antibiotic susceptibility, good antimicrobial activity, and favorable resistance to acid and bile salt. The results of bioactivity assessment demonstrated acceptable anticancer effects on the four tested cancer cell lines and negligible side effects on the assayed normal cell line. Our findings revealed that the anticancer effect of L. acidophilus 36YL strain secretions depends on the induction of apoptosis in cancer cells. L. acidophilus 36YL strain is considered as a nutraceutical alternative or a topical medication with a potential therapeutic index because of the absence of cytotoxicity to normal cells, but effective toxicity to cancer cell lines.