Effect of Maillard induced glycation on protein hydrolysis by lysine/arginine and non-lysine/arginine specific proteases

Enzymatic protein hydrolysis is sensitive to modifications of protein structure, e.g. Maillard reaction. In early stages of the reaction glycation takes place, modifying the protein primary structure. In later stages protein aggregation occurs. The specific effect of glycation on protein hydrolysis was studied using α-lactalbumin glycated with D-glucose at 50 °C (0–10 h). This resulted in proteins with different degrees of glycation (DG = 0–63%) without changes in secondary, tertiary and quaternary structure. These glycated proteins were hydrolyzed by lysine/arginine specific proteases (bovine and porcine trypsin) or by non-lysine/arginine specific proteases (Bacillus licheniformis protease (BLP), α-chymotrypsin and subtilisin A). For bovine and porcine trypsin, the maximal degree of hydrolysis decreased linearly with 65% from untreated to maximal glycated protein (DG = 63%). This means trypsin cannot hydrolyze glycated cleavage sites. BLP and subtilisin A hydrolyses were independent of glycation, while α-chymotrypsin cannot hydrolyze cleavage sites with glycated binding sites. This means for non-lysine/arginine specific proteases, the effect of glycation depends on the enzyme sensitivity towards modifications on binding sites. Since not all cleavage sites are efficiently used by the enzymes, the extent of the effects depends on the enzyme selectivity towards cleavage sites (for trypsin) or cleavage sites near glycation sites (for α-chymotrypsin). Combining the results of all proteases, an equation was derived describing the effect of modification of protein primary structure on the extent of hydrolysis based on the enzyme specificity, selectivity and binding site sensitivity

Титульні сторінки та зміст

Colostrum oligosaccharides are known to exhibit prebiotic and immunomodulatory properties. Oligosaccharide composition is species-specific, and equine colostrum has been reported to contain unique oligosaccharides. Therefore, equine oligosaccharides (EMOS) from colostrum from different horse breeds were analyzed by CE-LIF, CE-MSn, HILIC-MSn, and exoglycosidase degradation. Sixteen EMOS were characterized and quantified, of which half were neutral and half were acidic. EMOS showed about 63% structural overlap with human milk oligosaccharides, known for their bioactivity. Seven EMOS were not reported before in equine oligosaccharides literature: neutral Gal(beta 1-4)HexNAc, Gal(beta 1-4)Hex-Hex, beta 4'-galactosyllactose, and lactose-N- hexaose, as well as acidic 6'-Sialyl-Hex-Ac-HexNAc, sialyllacto-N-tetraose-a, and disialylacto-N-tetraose (isomer not further specified). In all colostrum samples, the average oligosaccharide concentration ranged from 2.12 to 4.63 g/L; with beta 6'and 3'- galactosyllactose, 3'-sialyllactose, and disialyllactose as the most abundant of all oligosaccharides (27-59, 16-37, 1-8, and 1-6%, respectively). Differences in presence and in abundance of specific EMOS were evident not only between the four breeds but also within the breed

Digestibility of resistant starch type 3 is affected by crystal type, molecular weight and molecular weight distribution

Resistant starch type 3 (RS-3) holds great potential as a prebiotic by supporting gut microbiota following intestinal digestion. However the factors influencing the digestibility of RS-3 are largely unknown. This research aims to reveal how crystal type and molecular weight (distribution) of RS-3 influence its resistance. Narrow and polydisperse α-glucans of degree of polymerization (DP) 14–76, either obtained by enzymatic synthesis or debranching amylopectins from different sources, were crystallized in 12 different A- or B-type crystals and in vitro digested. Crystal type had the largest influence on resistance to digestion (A >>> B), followed by molecular weight (Mw) (high DP >> low DP) and Mw distribution (narrow disperse > polydisperse). B-type crystals escaping digestion changed in Mw and Mw distribution compared to that in the original B-type crystals, whereas A-type crystals were unchanged. This indicates that pancreatic α-amylase binds and acts differently to A- or B-type RS-3 crystals.</p

Comparing risk-adjusted inpatient fall rates internationally: validation of a risk-adjustment model using multicentre cross-sectional data from hospitals in Switzerland and Austria

Background Inpatient falls in hospitals are an acknowledged indicator of quality of care. International comparisons could highlight quality improvement potential and enable cross-national learning. Key to fair cross-national comparison is the availability of a risk adjustment model validated in an international context. This study aimed to 1) ascertain that the variables of the inpatient fall risk adjustment model do not interact with country and thus can be used for risk adjustment, 2) compare the risk of falling in hospitals between Switzerland and Austria after risk adjustment. Methods The data on inpatient falls from Swiss and Austrian acute care hospitals were collected on a single measurement day in 2017, 2018 and 2019 as part of an international multicentre cross-sectional study. Multilevel logistic regression models were used to screen for interaction effects between the patient-related fall risk factors and the countries. The risks of falling in hospital in Switzerland and in Austria were compared after applying the risk-adjustment model. Results Data from 176 hospitals and 43,984 patients revealed an inpatient fall rate of 3.4% in Switzerland and 3.9% in Austria. Two of 15 patient-related fall risk variables showed an interaction effect with country: Patients who had fallen in the last 12 months (OR 1.49, 95% CI 1.10–2.01, p = 0.009) or had taken sedatives/psychotropic medication (OR 1.40, 95% CI 1.05–1.87, p = 0.022) had higher odds of falling in Austrian hospitals. Significantly higher odds of falling were observed in Austrian (OR 1.38, 95% CI 1.13–1.68, p = 0.002) compared to Swiss hospitals after applying the risk-adjustment model. Conclusions Almost all patient-related fall risk factors in the model are suitable for a risk-adjusted cross-country comparison, as they do not interact with the countries. Further model validation with additional countries is warranted, particularly to assess the interaction of risk factors “fall in the last 12 months” and “sedatives/psychotropic medication intake” with country variable. The study underscores the crucial role of an appropriate risk-adjustment model in ensuring fair international comparisons of inpatient falls, as the risk-adjusted, as opposed to the non-risk-adjusted country comparison, indicated significantly higher odds of falling in Austrian compared to Swiss hospitals

Risk-adjusted trend in national inpatient fall rates observed from 2011 to 2019 in acute care hospitals in Switzerland: a repeated multicentre cross-sectional study

Objectives: This study aimed to investigate whether a significant trend regarding inpatient falls in Swiss acute care hospitals between 2011 and 2019 could be confirmed on a national level, and whether the trend persists after risk adjustment for patient-related fall risk factors. Design: A secondary data analysis was conducted based on annual multicentre cross-sectional studies carried out between 2011 and 2019. Setting: All Swiss acute care hospitals were obliged to participate in the surveys. Except for emergency departments, outpatient wards and recovery rooms, all wards were included. Participants: All inpatients aged 18 or older who had given their informed consent and whose data were complete and available were included. Outcome measure Whether a patient had fallen in the hospital was retrospectively determined on the survey day by asking patients the following question: Have you fallen in this institution in the last 30 days? Results Based on data from 110 892 patients from 222 Swiss hospitals, a national inpatient fall rate of 3.7% was determined over the 9 survey years. A significant linear decreasing trend (p=0.004) was observed using the Cochran-Armitage trend test. After adjusting for patient-related fall risk factors in a two-level random intercept logistic regression model, a significant non-linear decreasing trend was found at the national level. Conclusions: A significant decrease in fall rates in Swiss hospitals, indicating an improvement in the quality of care provided, could be confirmed both descriptively and after risk adjustment. However, the non-linear trend, that is, an initial decrease in inpatient falls that flattens out over time, also indicates a possible future increase in fall rates. Monitoring of falls in hospitals should be maintained at the national level. Risk adjustment accounts for the observed increase in patient-related fall risk factors in hospitals, thus promoting a fairer comparison of the quality of care provided over time

Inactivation of glycogen synthase kinase-3 beta (GSK-3 beta) enhances skeletal muscle oxidative metabolism

Background: Aberrant skeletal muscle mitochondrial oxidative metabolism is a debilitating feature of chronic diseases such as chronic obstructive pulmonary disease, type 2 diabetes and chronic heart failure. Evidence in non-muscle cells suggests that glycogen synthase kinase-3 beta (GSK-3 beta) represses mitochondrial biogenesis and inhibits PPAR-gamma co-activator 1 (PGC-1), a master regulator of cellular oxidative metabolism. The role of GSK-3 beta in the regulation of skeletal muscle oxidative metabolism is unknown. Aims: We hypothesized that inactivation of GSK-3 beta stimulates muscle oxidative metabolism by activating PGC-1 signaling and explored if GSK-3 beta inactivation could protect against physical inactivity-induced alterations in skeletal muscle oxidative metabolism. Methods: GSK-3 beta was modulated genetically and pharmacologically in C2C12 myotubes in vitro and in skeletal muscle in vivo. Wild-type and muscle-specific GSK-3 beta knock-out (KO) mice were subjected to hind limb suspension for 14 days. Key constituents of oxidative metabolism and PGC-1. signaling were investigated. Results: In vitro, knock-down of GSK-3 beta increased mitochondrial DNA copy number, protein and mRNA abundance of oxidative phosphorylation (OXPHOS) complexes and activity of oxidative metabolic enzymes but also enhanced protein and mRNA abundance of key PGC-1 signaling constituents. Similarly, pharmacological inhibition of GSK-3 beta increased transcript and protein abundance of key constituents and regulators of mitochondrial energy metabolism. Furthermore, GSK-3 beta KO animals were protected against unloading-induced decrements in expression levels of these constituents. Conclusion: Inactivation of GSK-3 beta up-regulates skeletal muscle mitochondrial metabolism and increases expression levels of PGC-1 signaling constituents. In vivo, GSK-3 beta KO protects against inactivity-induced reductions in muscle metabolic gene expression

Dietary Isomalto/Malto-Polysaccharides Increase Fecal Bulk and Microbial Fermentation in Mice

Scope: The prevalence of metabolic-syndrome-related disease has strongly increased. Nutritional intervention strategies appear attractive, particularly with novel prebiotics. Isomalto/malto-polysaccharides (IMMPs) represent promising novel prebiotics that promote proliferation of beneficial bacteria in vitro. The present study investigates for the first time the in vivo effects of IMMP in mice. Methods and results: C57BL/6 wild-type mice received control or IMMP-containing (10%, w/w) diets for 3 weeks. IMMP leads to significantly more fecal bulk (+26%, p < 0.05), higher plasma non-esterified fatty acids (colorimetric assay, +10%, p < 0.05), and lower fecal dihydrocholesterol excretion (mass spectrometry, −50%, p < 0.05). Plasma and hepatic lipid levels (colorimetric assays following lipid extraction) are not influenced by dietary IMMP, as are other parameters of sterol metabolism, including bile acids (gas chromatography/mass spectrometry). IMMP is mainly fermented in the cecum and large intestine (high-performance anion exchange chromatography). Next-generation sequencing demonstrates higher relative abundance of Bacteroides and butyrate producers (Lachnospiraceae, Roseburia Odoribacter) in the IMMP group. Conclusion: The combined results demonstrate that IMMP administration to mice increases fecal bulk and induces potentially beneficial changes in the intestinal microbiota. Further studies are required in disease models to substantiate potential health benefits.</p

Type of intrinsic resistant starch type 3 determines in vitro fermentation by pooled adult faecal inoculum

Resistant starch (RS) results in relatively high health-beneficial butyrate levels upon fermentation by gut microbiota. We studied how physico-chemical characteristics of RS-3 influenced butyrate production during fermentation. Six highly resistant RS-3 substrates (intrinsic RS-3, 80-95 % RS) differing in chain length (DPn 16-76), Mw distribution (PI) and crystal type (A/B) were fermented in vitro by pooled adult faecal inoculum. All intrinsic RS-3 substrates were fermented to relatively high butyrate levels (acetate/butyrate ≤ 2.5), and especially fermentation of A-type RS-3 prepared from polydisperse α-1,4 glucans resulted in the highest relative butyrate amount produced (acetate/butyrate: 1). Analysis of the microbiota composition after fermentation revealed that intrinsic RS-3 stimulated primarily Lachnospiraceae, Bifidobacterium and Ruminococcus, but the relative abundances of these taxa differed slightly depending on the RS-3 physico-chemical characteristics. Especially intrinsic RS-3 of narrow disperse Mw distribution stimulated relatively more Ruminococcus. Selected RS fractions (polydisperse Mw distribution) obtained after pre-digestion were fermented to acetate and butyrate (ratio ≤ 1.8) and stimulated Lachnospiraceae and Bifidobacterium. This study indicates that especially the α-1,4 glucan Mw distribution dependent microstructure of RS-3 influences butyrate production and microbiota composition during RS-3 fermentation.</p