Comparison of non-diglyceride- and diglyceride-based assays for pancreatic lipase activity

Biochemical alterations induced by Zn and Cd individually or in combination in the serum of Oreochromis niloticus

Measurement of serum biochemical parameters in response to metal exposures can be especially useful to help identify target organs of toxicity as well as the general health status of animals. Oreochromis niloticus were exposed to 5.0 mg/L Zn, 1.0 mg/L Cd, and 5.0 mg/L Zn + 1.0 mg/L Cd mixture for 7 and 28 days, and alterations in serum enzyme activities and ion levels were measured. Significant changes in all the biochemical parameters were found to be time dependent. Following metal exposure, alkaline phosphatase activity was elevated at both exposure periods. No changes in activities of lactate dehydrogenase and lipase were observed in response to single or combined Zn and Cd exposure at 7 days while they increased at 28 days. Fish exposed to metals showed a decrease in cholinesterase activity at 7 days followed by a return to control levels at the end of the exposure period. The individual and combined effects of metals caused a decline in levels of Na(+), Cl(-), and Ca(2+), especially at 28 days. K(+) level increased at 7 days but it returned to control levels with increasing duration of exposure. This study indicated that the alterations in serum parameters may be a result of the target tissue (i.e., liver, gill, and kidney) damage and dysfunction induced by the metals and that these parameters can thus be used to assess the effects of metals on organisms.

Enzymatic determination of diglyceride using an iridium nano-particle based single use, disposable biosensor

A single use, disposable iridium-nano particle contained biosensor had been developed for the determination of diglyceride (DG). In this study hydrogen peroxide, formed through the enzymatic breakdown of DG via lipase, glycerol kinase and glycerol 3-phosphate oxidase, was electrochemically oxidized at an applied potential of +0.5 V versus the Ag/AgCl reference electrode. The oxidation current was then used to quantify the diglyceride concentration. Optimum enzyme concentrations and the surfactant loading used were established for successful sensor response. Good linear performance was observed over a DG concentration range of 0 to 25 μM in phosphate buffer and bovine serum media.

New procedure for the measurement of pancreatic lipase activity in human serum using a thioester substrate

BACKGROUND

Definitive substrates for the measurement of pancreatic lipase activity in human serum have not been conclusively identified owing to poor aqueous solubility and nonspecific susceptibility of substrates with existing methods. Thus, it is still important to propose new substrates for robust lipase measurements.

METHODS

Reaction conditions were studied for a lipase method using newly synthesized 2,3-dibutyrylthio-1-propyl oleate as the substrate and 5,5'-dithio-bis-(2-nitro-benzoic acid) as the chromogen.

RESULTS

Optimum conditions, using colipase and Mg(++) in aqueous hexamethyl phosphoric triamide medium at pH 9.2, were defined. The substrate was highly selective to pancreatic lipase. The reaction increased linearly with lipase concentrations up to 500 U/l. The reference interval of serum lipase concentrations was 21.5-65 U/l. Using the Passing-Bablok regression analysis, the present assay shows a slope of 0.414, an intercept of -2.4 U/l, and r-value of 0.992 in the comparison with the chromogenic method using the 6-methylresorufin ester of 1-O,2-O-dilauryl-rac-glycero-3-glutaric acid as the substrate.

CONCLUSION

Because of the simple composition of the reagents, the proposed procedure may represent a significant advancement in the commercially available methods for pancreatic lipase determination.