Rapid biophysical analyses of gastric aspirates from risk newborns for lung maturity assessment after corticosteroid therapy.

BACKGROUND: One of the main causes for the higher mortality among risk newborn children (including preterm infants) is neonatal respiratory distress syndrome (NRDS), which develops as a result of primary deficiency or secondary inactivation of alveolar surfactant (AS). Therefore, fast and early diagnostics of risk newborns lung maturity is crucial for their prompt therapy. MATERIALS AND METHODS: Gastric aspirates (GA) were collected from 77 infants divided into three groups: a control of 38 healthy full-term infants; 16 prematurely newborns with NRDS, and 23 prematurely born infants after in vitro fertilization and corticosteroid therapy (CST). Surface parameters: equilibrium (γeq), maximal (γmax) and minimal (γmin) surface tension, and the shape of hysteresis curves of GA monolayers were measured by axisymmetric drop shape analysis (ADSA) of a pending drop. In addition, the morphology of GA monolayers was studied by Brewster angle microscopy (BAM). RESULTS: Our results showed that only γmin values were reliable and were significantly lower in full-term infants, as compared to the risk neonates. The results obtained were proved by the shape of hysteresis curves of GA surface active films. BAM images of GA monolayers from NRDS group showed impaired surface morphology due to the surfactant insufficiency, as compared to the control group. Corticosteroid therapy improved both GA surface characteristics and monolayer morphology. CONCLUSIONS: GAs analyses by ADSA and BAM are fast and informative approaches for lung maturity assessment. In addition, the corticosteroid therapy applied improved all GAs surface parameters due to AS maturation.

Detection and characterization of OXA-48-producing Klebsiella pneumoniae originated in Bulgaria.

We report the identification of OXA-48-producing Klebsiella pneumoniae, causing peritonitis in a cancer patient admitted to the Oncology Hospital in Sofia. The isolate had reduced susceptibility to carbapenems but remained susceptible to extended-spectrum cephalosporins. PCR and sequencing confirmed the presence of blaOXA-48 gene flanked by two intact copies of IS1999 on truncated ΔTn1999.1. This transposon was located on unusual non-typeable 29-kb plasmid that could be transferred only by transformation. Multilocus sequence typing (MLST) indicated the presence of the sequence type ST530.This is the first documented infection due to OXA-48-producing Enterobacteriaceae strain in Bulgaria.

AmyA, an alpha-amylase with beta-cyclodextrin-forming activity, and AmyB from the thermoalkaliphilic organism Anaerobranca gottschalkii: two alpha-amylases adapted to their different cellular localizations.

Two alpha-amylase genes from the thermophilic alkaliphile Anaerobranca gottschalkii were cloned, and the corresponding enzymes, AmyA and AmyB, were investigated after purification of the recombinant proteins. Based on their amino acid sequences, AmyA is proposed to be a lipoprotein with extracellular localization and thus is exposed to the alkaline milieu, while AmyB apparently represents a cytoplasmic enzyme. The amino acid sequences of both enzymes bear high similarity to those of GHF13 proteins. The different cellular localizations of AmyA and AmyB are reflected in their physicochemical properties. The alkaline pH optimum (pH 8), as well as the broad pH range, of AmyA activity (more than 50% activity between pH 6 and pH 9.5) mirrors the conditions that are encountered by an extracellular enzyme exposed to the medium of A. gottschalkii, which grows between pH 6 and pH 10.5. AmyB, on the other hand, has a narrow pH range with a slightly acidic pH optimum at 6 to 6.5, which is presumably close to the pH in the cytoplasm. Also, the intracellular AmyB is less tolerant of high temperatures than the extracellular AmyA. While AmyA has a half-life of 48 h at 70 degrees C, AmyB has a half-life of only about 10 min at that temperature, perhaps due to the lack of stabilizing constituents of the cytoplasm. AmyA and AmyB were very similar with respect to their substrate specificity profiles, clearly preferring amylose over amylopectin, pullulan, and glycogen. Both enzymes also hydrolyzed alpha-, beta-, and gamma-cyclodextrin. Very interestingly, AmyA, but not AmyB, displayed high transglycosylation activity on maltooligosaccharides and also had significant beta-cyclodextrin glycosyltransferase (CGTase) activity. CGTase activity has not been reported for typical alpha-amylases before. The mechanism of cyclodextrin formation by AmyA is unknown.