Obstructive sleep apnea and periodic limb movement in children: is there really an association?

PURPOSE: Periodic limb movements (PLMs) can be found isolated or related to other sleep disorders, as Obstructive Sleep Apnea (OSA). Nevertheless, this association was described before the proposal for modification of the World Association of Sleep Medicine (WASM), which incorporated major changes modifying the definition of respiratory-related leg movements (RRLM) so that the relationship between OSA and PLM could be affected. METHODS: A total of 131 PSG were studied (children with ages from 5 to 12 years old), all referred because of a suspicion of sleep-disordered breathing (65 children were diagnosed of OSA, and 66 presented snoring but no sleep apnea). Leg movements were manually scored according to both 2006 and 2016 WASM/IRLSSG criteria. RESULTS: According to 2006 WASM rules, statistical differences were found, not only for PLM index (p 0.002), but all indexes. Nevertheless, according to new 2016 WASM rules, no statistical differences were found for PLM index (p 0.677), non-REM PLM index (p 0.299), REM PLM index (P 0.511) or PLM with arousal index (p 0.180), between OSA and non-OSA group. Positive correlation between PLM and RRLM have been found with both set of rules. The percentage of children with PLM>5/h is higher when using the prior PLM scoring criteria developed in 2006 (38.93%) versus the updated PLM scoring criteria (19.08%). CONCLUSION: The lack of association when using the new WASM/IRLSSG scoring rules together with the absence of a previous clear etiopathology explanation may suggest that the association between OSA and PLM might be indeed overestimated and that, perhaps, it really did not exist.

Selection and molecular identification of fungal isolates that produce xylanolytic enzymes.

Xylan is a heteropolysaccharide and its complete hydrolysis involves a complex set of xylanolytic enzymes. Fungal xylanases have been widely used in the holocellulose industry to obtain by-products or for its elimination. The aim of this study was to select and identify filamentous fungi from different ecosystems that produce extracellular xylanases showing biotechnological potential. One hundred three fungal isolates were obtained from orchard, horticultural, and forest ecosystems. The ability of fungi to degrade xylan was measured by quantifying their xylanolytic indices after growth on solid culture media and their extracellular xylanolytic and cellulolytic activities after submerged fermentation. All fungal isolates grew on solid medium supplemented with xylan as the sole carbon source, but only 44% of isolates showed xylanolytic indices greater than 1.0. In submerged fermentation, 39% of the fungi tested showed no cellulolytic activity. Filamentous fungi were chosen from correspondence analysis and were identified by molecular tools using internal transcribed spacers. One of the 9 isolates selected belonged to the Phoma genus and the remaining were from the Fusarium genus. Fusarium solani (isolate 59) showed the highest xylanolytic index (0.964 ± 0.042), rapid growth on solid medium (1.233 ± 0.050 cm/day), significant xylanolytic activity (3.823 ± 0.210 U/mg), and a total deficiency of cellulolytic activity compared to other fungal isolates. In the zymogram, a clear zone was observed, indicating that F. solani possesses at least 1 xylanase. Fusarium solani was selected for its ability to produce extracellular xylanases with biotechnological potential.

The abundant 31-kilodalton banana pulp protein is homologous to class-III acidic chitinases.

We have identified and characterized the abundant protein from the pulp of banana fruit (Musa acuminata cv. Grand Nain), and have isolated a cDNA clone encoding this protein. Comparison of the amino terminal sequence of the purified 31 kDa protein (P31) suggests that it is related to plant chitinases. Western analyses utilizing rabbit anti-P31 antiserum demonstrate that this protein is pulp-specific in banana. A full-length cDNA clone homologous to class III acidic chitinase genes has been isolated from a pulp cDNA library by differential screening. The identity of this clone as encoding P31 was verified by comparisons between the amino-terminal peptide sequence and the cDNA sequence and cross-hybridization of the translation product of the cDNA clone with P31 antiserum. Northern and western blot analyses of RNA and protein isolated from banana pulp at different stages of ripening indicate that the cDNA and protein are expressed at high levels in the pulp of unripe fruit, and that their abundance decreases as the fruit ripens. Based on its expression pattern and deduced amino acid sequence and composition, we hypothesize that the physiological role of P31 is not for plant protection, but as a storage protein in banana pulp.