The activity of family 11 xylanases at alkaline pH

Xylanases have several industrial uses, particularly in baking, modification of animal feed and in pulp bleaching in the paper industry. Process conditions in kraft pulp bleaching generally favour an enzyme that is active at high pH values. The activities of several glycosyl hydrolase family 11 xylanases reported to be active under alkaline conditions were determined under optimal conditions and found to have optima in the pH 5–6 range. Only one enzyme tested, BadX, was shown to have an alkaline pH optimum. Significant activity at pH values higher than 8 appears often to be the result of excess enzyme added to the reaction mixtures so that substrate is limiting. The different nature of laboratory and industrial substrates needs to be taken into consideration in designing assay conditions. In some cases, significant differences were observed in pH profiles generated using a small-molecule substrate when compared to those generated using xylan. We conclude that small-molecule substrates are not a suitable proxy for determining the pH profiles of family 11 xylanases

Outcome after resection for perihilar cholangiocarcinoma in patients with primary sclerosing cholangitis: an international multicentre study

Item does not contain fulltextBACKGROUND: Resection for perihilar cholangiocarcinoma (pCCA) in primary sclerosing cholangitis (PSC) has been reported to lead to worse outcomes than resection for non-PSC pCCA. The aim of this study was to compare prognostic factors and outcomes after resection in patients with PSC-associated pCCA and non-PSC pCCA. METHODS: The international retrospective cohort comprised patients resected for pCCA from 21 centres (2000-2020). Patients operated with hepatobiliary resection, with pCCA verified by histology and with data on PSC status, were included. The primary outcome was overall survival. Secondary outcomes were disease-free survival and postoperative complications. RESULTS: Of 1128 pCCA patients, 34 (3.0%) had underlying PSC. Median overall survival after resection was 33 months for PSC patients and 29 months for non-PSC patients (p = .630). Complications (Clavien-Dindo grade ≥ 3) were more frequent in PSC pCCA (71% versus 44%, p = .003). The rate of posthepatectomy liver failure (21% versus 17%, p = .530) and 90-day mortality (12% versus 13%, p = 1.000) was similar for PSC and non-PSC patients. CONCLUSION: Median overall survival after resection for pCCA was similar in patients with underlying PSC and non-PSC patients. Complications were more frequent after resection for PSC-associated pCCA, with no difference in postoperative mortality

Shallow-water Aplysina Nardo (Aplysinidae, Verongida, Demospongiae) from the São Sebastião Channel and its environs (Tropical southwestern Atlantic), with the description of a new species and a literature review of other brazilian records of the genus

Two species of Aplysina Nardo, 1834 are described in this article, Aplysina caissara sp. n. and A. fulva (Pallas, 1766). Additionally, a possible third species was identified as A. aff. cauliformis. Collections were done in the São Sebastião Channel area as an ongoing effort to assess the poriferan biodiversity of the northern sector of the São Paulo State coastline. Specimens were collected by scuba diving, and descriptions of external morphology are based on the observation of populations alive, and on extensive underwater photography. A literature review of other brazilian records of Aplysina was undertaken, and an ammended species list is offered

Comments on brazilian Halichondria Fleming (Halichondriidae, Halichondrida, Demospongiae), with the description of four new species from the S\ue3o Sebasti\ue3o Channel and its environs (Tropical Southwestern Atlantic)

Over 70 species of Halichondria Fleming, 1828 are known world-wide, but only five from the Brazilian Coast. Brazilian records have their status re-evaluated here, and four new species are described for the São Sebastião Channel area, in the Tropical Southwestern Atlantic, viz. H. cebimarensis sp. n., H. sulfurea sp. n., H. migottea sp. n. and H. tenebrica sp. n