Identification of an indigo precursor from leaves of Isatis tinctoria (Woad).

Indole is presumably a product of indole-3-glycerol phosphate catabolism in Isatis tinctoria. It is oxidized into indoxyl and stored in young leaves as indigo precursor. Further oxidation and dimerization of indoxyl produces indigoid pigments. In this work, we describe an HPLC method dedicated to the identification and quantification of indigoid pigments (indigo, indirubin, isoindigo and isoindirubin) and indigo precursors produced in I. tinctoria (Woad). This work, carried out with two cultivars of I. tinctoria, has confirmed that the quantity of indigo precursors is dependent on the species and the harvest period. In addition we have shown for the first time that young leaves of I. tinctoria, harvested in June contained a new indigo precursor in addition to isatan B (indoxyl-5-ketogluconate) and indican (indoxyl-beta-D-glucoside). We suggest the name "isatan C" for this new indigo precursor in I. tinctoria. Its chemical characteristics point to an dioxindole ester with PM of 395. We have shown that isatan C reacts with isatan B increasing the red pigment production.

Gas phase biotransformation reaction catalyzed by baker's yeast.

The gas phase continuous production of acetaldehyde from ethanol and hexanol from hexanal using dried baker's yeast was studied as an alternative approach to conventional processes. The effects of water activity, activity of substrates, and amount of yeast on the performance of the continuous bioreactor were investigated. The extent of yeast hydration and ethanol activity are the most important factors affecting yeast activity and stability.

Study of vitamin ester synthesis by lipase-catalyzed transesterification in organic media.

Immobilized lipase from Candida antarctica (Novozym 435) was used in organic media to catalyze esterifications of vitamins (ascorbic acid and retinol) from hydroxy acid. We described the synthesis of retinyl L-lactate by transesterification between retinol and L-methyl lactate with yield reaching 90% and the synthesis of ascorbyl L-lactate by transesterification between ascorbic acid and L-methyl lactate with yield reaching 80%. The kinetic study of the esterification of vitamins with L-methyl lactate in organic media has been carried out and agrees with ping-pong-ordered Bi-Bi when the initial vitamin concentration is low. When initial vitamin concentration is high, the kinetic is similar to a hybrid ping-pong-ordered Bi Bi or hybrid ping-pong-random Bi Bi mechanism. However, with high initial substrate concentration, change of the kinetic by other phenomena, such as interaction of substrates with molecular sieves, adsorption of the methanol formed, and decreases of substrate diffusion, could be considered. It is obvious that in these conditions, classical enzymology (i.e., Michaelian enzymology) cannot be used for the interpretation of results.

Kinetic study of chemoselective acylation of amino-alditol by immobilized lipase in organic solvent: effect of substrate ionization.

The kinetics of the lipase-catalyzed synthesis of oleoyl-N-methylglucamide and 6-O-oleoyl-N-methylglucamine in organic systems were investigated. We have shown that in apolar media, the ionic state of substrates and the ionic state of enzyme microenvironment play an important role in immobilized Candida antarctica lipase activity and chemoselectivity of the reaction. In order to define the optimal conditions of the reaction, to obtain the highest initial rate for amide formation, the influence of acid/N-methylglucamine molar ratio is studied. This ratio determines the protonation states of substrates and of ionizable groups of catalytic site, on which the enzyme activity is dependent. To confirm our hypothesis, we have added to the medium a non-reactive base which is not a substrate of the enzyme. We observed that when the acid/base ratio is higher than 1, the initial rate of ester synthesis increases whereas that of amide synthesis decreases. On the opposite, when the acid/base ratio is lower than 1, the initial rate of amide synthesis becomes preponderant.

[Bacteriological study in acute otitis media]. / Etude bactériologique au cours de I'otite moyenne aiguë.

AIM: A prospective study on bacteriological epidemiology in acute otitis media was conducted in a pediatric hospital emergency service from January 1993 to October 1995. PATIENTS: One hundred and fifty-eight children, aged 6 months to 6 years, with an acute otitis media were included. Culturing and cleansing of the ear canal and tympanocentesis for aspiration and culture of the secretions were performed in 118 children (46 of whom had received antibiotics before for 48 hours). MAIN RESULTS: Middle ear aspirates were sterile in 35% of the children who had not received antibiotics and in 64% of those already treated. Bacteria in middle ear were predominantly Haemophilus influenzae and Streptococcus pneumoniae. Fifty-nine percent of S pneumoniae strains were penicillin-resistant; however, they were responsible for clinical failure in only 8% of cases. No Staphylococcus strains, commensal of the ear canal, could be considered as pathogenic for the middle ear. CONCLUSION: The preciseness with which secretions of middle ear are aspirated reduces the risk of contamination and comparison of ear canal and middle ear cultures allows to identify them. The high ratio of sterile middle ear aspirates after antibiotic treatment raises the question if other factors are responsible for persistent symptoms. The existence of penicillin-resistant S pneumoniae must be known to adjust treatment.

[Hepatoportal sclerosis: apropos of a familial case]. / La sclérose hépatoportale: à propos d'un cas familial.

BACKGROUND: Hepatoportal sclerosis is uncommon in European countries and its diagnosis is difficult. The etiology remains unknown; its familial origin is probably exceptional. CASE REPORT: An 18-month-old girl born to a mother with hepatoportal sclerosis had hepatomegaly. She also had a moderate splenomegaly and mild increase transaminase and gamma GT activities. Ultrasound examination failed to show portal hypertension. Histological study of liver showed changes quite similar to those seen in her mother. Two members of the mother's family had portal hypertension. DISCUSSION: Familial forms of portal hypertension have been reported: a familial form of incomplete septal cirrhosis and a familial occurrence of cavernous transformation of the portal vein. Obstruction of the portal vessels was not found in our patient, the youngest in whom hepatoportal sclerosis is documented.

Trisomy 18 mosaicism in a mildly retarded boy with postnatal overgrowth.

We report a 6-year-old mildly retarded boy with trisomy 18 in 44% of peripheral lymphocytes. He had mild nonspecific dysmorphic features, microcephaly, micropenis with cryptorchidism and postnatal overgrowth. Trisomy 18 mosaicism was confirmed by a fluorescent in situ hybridization study. Ten previous reports of trisomy 18 mosaicism with normal or subnormal intelligence have been described but only one case of trisomy 18 mosaicism with high stature has been reported.