Gluco-oligosaccharides synthesized by glucosyltransferases from constitutive mutants of Leuconostoc mesenteroides strain Lm 28.

AIMS: To find different types of glucosyltransferases (GTFs) produced by Leuconostoc mesenteroides strain Lm 28 and its mutant forms, and to check the effectiveness of gluco-oligosaccharide synthesis using maltose as the acceptor. METHODS AND RESULTS: Constitutive mutants were obtained after chemical mutagenesis by ethyl methane sulfonate. Lm M281 produced more active GTFs than that obtained by the parental strain cultivated on sucrose. GTF from Lm M286 produced a resistant glucan, based on endo-dextranase and amyloglucosidase hydrolysis. The extracellular enzymes from Lm M286 catalyse acceptor reactions and transfer the glucose unit from sucrose to maltose to produce gluco-oligosaccharides (GOS). By increasing the sucrose/maltose ratio, it was possible to catalyse the synthesis of oligosaccharides of increasing degree of polymerization (DP). CONCLUSIONS: Different types of GTFs (dextransucrase, alternansucrase and levansucrase) were produced from new constitutive mutants of Leuc. mesenteroides. GTFs from Lm M286 can catalyse the acceptor reaction in the presence of maltose, leading to the synthesis of branched oligosaccharides. SIGNIFICANCE AND IMPACT OF THE STUDY: Conditions were optimized to synthesize GOS by using GTFs from Lm M286, with the aim of producing maximum quantities of branched-chain oligosaccharides with DP 3-5. This would allow the use of the latter as prebiotics.

Pathogenetic aspects of clinico-electrophysiological differentiation of transient cerebral circulation disorders terminating with a complete clinical recovery.

The present study offers a clinico-theoretical, electrophysiological and rheoencephalographic analysis of the brain matter condition and the cerebral hemodynamics of patients with acute cerebral circulation disorders which resolve with a complete clinical recovery. The purposes of the study were (1) to achieve pathogenetic differentiation of the syndromes of transient ischemic attacks (TIA) and reversible ischemic neurologic deficit (RIND) with greater confidence than that achieved by using the clinical criterion of "the neurologic deficit duration" (24 hours for TIAs, three weeks for RIND). (2) to determine the subclinical level in a single case, and (3) to develop a new approach to secondary prophylaxis in such patients. Fifty four patients (30 men and 24 women, mean age 57.2 +/- 1.9 years) presenting with acute ischemic disorders of cerebral circulation at the Clinic of Vascular Cerebral Diseases in the Department of Neurology of Plovdiv Medical University were followed up in the period between 1989 and 1991. On the 5th and 20th days of the episode onset the central latency time (CLT) of an evoked motor potential (MEP) was investigated on the symptomatic and asymptomatic sides. The study also involved rheoencephalography not only of the clinically followed-up population but also of 59 outpatients with TIA, 129 patients with RIND and 38 patients with an ischemic cerebral stroke. The results obtained objectify the differences among the researchers and confirm their views on the most common pathogenetic mechanisms associated with the occurrence and the course of the two forms of cerebral ischemia terminating with a complete clinical recovery.