Derivatives of 1-naphthyl ethylenediamine dihydrochloride for standardization of direct-bilirubin assays done with the Technicon "SMAC".
The Jendrassik--Groff assay for direct bilirubin was adapted for analysis rates of 150/h on the Technicon "SMAC" continuous-flow analyzer. This requires development of a standard that is compatible with the other 19 channels on this analyzer. N-1-Naphthyl ethylenediamine dihydrochloride has been used for standardization of direct bilirubin assays, but we found it to be unsuitable because values for potassium are falsely elevated when potassium is determined with a valinomycin ion-selective electrode. This interference can be eliminated by alkylating the aliphatic amine group in the standard. The resulting compounds undergo the coupling reaction in the same way as the original compound and function equally well as standards for the direct bilirubin reaction. The only limitation of these analogs is their decreased solubility at physiological pH in some cases. Thus only certain alkyl groups are suitable.
Ultramicro method for serum bilirubin by diazo blue reaction.
An ultramicromethod is presented for the determination of serum bilirubin by the (acid) diazo blue reaction, using heel puncture or fingertip blood. Diazotization is accomplished in a strongly acid medium with the resulting blue azobilirubin having a maximum absorption at 580 mµ. The method is extremely reproducible and sensitive, being carried out in final serum dilutions of 1:100 to 1:40. The method is described for use with the Coleman Junior spectrophotometer and can be adapted to other instruments. The diazo blue micromethod compares very favorably with the Malloy and Evelyn method which was done in parallel. The results of this study also suggest that the diazo blue micromethod can be used on venous serum or serum obtained from fingertip puncture without having markedly altered results.
Exopolysaccharide biosynthesis and related enzyme activities of the medicinal fungus, Ganoderma lucidum, grown on lactose in a bioreactor
Exopolysaccharide (EPS) production and biosynthesis were studied in Ganoderma lucidum, a fungus used in traditional Chinese medicine, grown with lactose in a bioreactor. β-Galactosidase activity, which implies the existence of a lactose permease system, was induced by lactose. Lactose feeding also increased α-phosphoglucomutase activity and EPS accumulation but decreased phosphoglucose isomerase activity and lactate concentration in the culture broth. A maximum cell density of 22 g l−1 and EPS at 1.25 g l−1 were obtained in fed-batch bioreactor culture.