Pentoses Used in Cultures of Synechococcus nidulans and Spirulina paracas: Evaluation of Effects in Growth and in Content of Proteins and Carbohydrates

Abstract The biological assimilation of the sugars present in lignocellulosic residues has gained prominence since these residues are the most abundant and economic residues in nature. Thus, the objective of this work was to determine whether the use of D-xylose and L-arabinose as sources of carbon in Synechococcus nidulans and Spirulina paracas cultures affects the growth and production of proteins and carbohydrates. Kinetic growth parameters, pentose consumption, protein content and carbohydrates were evaluated. Synechococcus nidulans and Spirulina paracas consumed all concentrations of pentose used. The highest cellular concentration (1.37 g.L-1) and the highest protein productivity (54 mg.L-1.d-1) were obtained for Spirulina paracas, which was submitted to the addition of 38.33 mg.L-1 D-xylose and 1.79 mg.L-1 L-arabinose. The use of pentose promoted the accumulation of proteins for the studied microalgae. This is one of the first works to report protein bioaccumulation as a result of pentose addition.

Dietary D-xylose effects on growth performance, portal nutrient fluxes, and energy expenditure in growing pigs.

Xylanase is commonly added to pig diets rich in arabinoxylans to promote nutrient utilization and growth. However, high doses of xylanase could release high amounts of xylose in the upper gut, which could have negative nutritional and metabolic implications. However, the amount of xylose to elicit such adverse effects is not clear. Thus, two experiments were conducted to investigate the effects of dietary xylose on the growth performance and portal-drained viscera (PDV) fluxes of glucose (GLU), urea-N (BUN), insulin production, and O2 consumption in growing pigs. In Exp. 1, 64 pigs (21.4 ± 0.1 kg BW), housed as either two barrows or gilts per pen (eight pens per diet) were used to determine the effects of increasing levels of D-xylose (0, 5, 15, and 25%) in a corn-soybean meal-cornstarch-based diet on pig growth performance in a 28-d trial. Cornstarch was substituted for D-xylose (wt/wt) in the control diet. BW and feed intake were monitored weekly. D-xylose linearly reduced (P < 0.05) final BW, ADG, and G:F but not ADFI. However, final BW, ADG, and G:F of pigs fed 15% D-xylose did not differ from pigs fed 0% D-xylose. Thus, the results suggested that pigs could tolerate up to 15% dietary D-xylose. In Exp. 2, six gilts (22.8 ± 1.6 kg BW), fitted with permanent catheters in the portal vein, ileal vein, and carotid artery, were fed the 0% and 15% D-xylose diets at 4% of their BW once daily at 0900 h for 7 d in a cross-over design (six pigs per diet). On d 7, pigs were placed in indirect calorimeters to measure whole-animal O2 consumption and sample blood simultaneously for 6 h from the portal vein and carotid artery after feeding to assay GLU, O2, BUN, and insulin concentrations. Net portal nutrients and insulin production were calculated as porto-arterial concentration differences × portal blood flow (PBF) rate, whereas PDV O2 consumption was calculated as arterial-portal O2 differences × PBF. Diet had no effect on postprandial PBF, insulin production, and portal BUN flux and O2 consumption. Pigs fed 0% D-xylose had greater (P < 0.05) postprandial portal and arterial BUN concentrations, and portal GLU concentration and flux than pigs fed 15% D-xylose diet. In conclusion, feeding growing pigs a diet containing 15% D-xylose did not reduce pig performance or affect PDV energetic demand but reduced GLU fluxes.

Small intestinal absorption in patients with chronic obstructive pulmonary disease complicated by cor pulmonale - A pilot study.

BACKGROUND: Cor pulmonale is a common complication to Chronic Obstructive Pulmonary Disease (COPD), and may result in increased pressure in the inferior caval vein and stasis of the liver. The chronic pulmonary hypertension may lead to stasis in the veins from the small intestine and thereby compromise absorption of nutrients. AIM: To investigate whether patients with pulmonary hypertension have reduced absorption capacity compared to COPD patients without cor pulmonale. METHODS: Absorption of d-xylose (25 g) and zinc (132 mg), administered as a single dose, was tested in 14 COPD patients, seven with and seven without cor pulmonale. The presence of cor pulmonale was determined by echocardiography. The concentration of d-xylose and zinc were measured in peripheral blood one, two and three hours after ingestion and used as markers of absorption. Furthermore, urine was collected for five hours to determine the amount of excreted d-xylose. RESULTS: No significant difference in absorption of d-xylose (p = 0.28) or zinc (p = 0.51) was found between the two groups. However, a trend towards a delay in d-xylose absorption, as assessed by time-to-peak concentration, was observed in patients with cor pulmonale (p = 0.08). There was no significant difference in the amount of excreted d-xylose in the urine between the groups (p = 0.52). No correlation was found between the tricuspid regurgitation gradient and the absorption of both test-markers (rs = 0.34 and rs = -0.25). Likewise, no correlations were found between the inferior caval pressure during the in- and expiration phases and the absorption of d-xylose (rs = -0.09 rs = 0.23) or zinc (rs = -0.39, rs = -0.39). CONCLUSION: We found no indications that small intestinal absorption is affected in a clinically relevant degree in patients with cor pulmonale.

Beneficial effect of xylose consumption on postprandial hyperglycemia in Korean: a randomized double-blind, crossover design.

BACKGROUND: Previous studies have reported that xylose selectively inhibited the activity of sucrase. Xylose supplementation may have a beneficial effect on the postprandial glycemic response. However, no studies have investigated patients with IFG or the effectivity of a dose of D-xylose less than 10 % (w/w). METHODS: The present study determined the effect of xylose consumption on postprandial hyperglycemia in normal (n = 25) and hyperglycemic subjects (n = 50). Subjects in this double-blind crossover design study were randomly assigned to consume a sucrose drink (Control, sucrose 50 g + deionized water 100 g) or a sucrose drink additionally containing 5 g (Test 1, sucrose:xylose = 10:1), 3.33 g (Test 2, sucrose:xylose = 15:1), or 2.5 g (Test 3, sucrose:xylose = 20:1) of D-xylose separated by a one-week interval. RESULTS: Normal subjects in all test groups exhibited a significant decrease in serum glucose levels 15 min and 30 min after consuming the xylose-containing drinks compared to the control group. Significantly lower serum levels of insulin were observed at 15 min and 30 min after consuming the xylose-containing drinks compared to the control group. The test 1 group also exhibited a significantly lower insulin area under the curve than the control group. Hyperglycemic subjects (n = 50) in all test groups exhibited a significant decrease in serum glucose levels at 30 min compared to the control group. However, the test 1 group exhibited a significant increase in serum glucose levels at 120 min compared to the control group. Glucose-related markers did not significantly differ in each group. CONCLUSION: Xylose supplementation may exert a beneficial effect on postprandial glycemic responses in subjects with normal glucose levels and prediabetes. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02654301 . Registered 12 January 2016.

Peroxidised dietary lipids impair intestinal function and morphology of the small intestine villi of nursery pigs in a dose-dependent manner.

The objective of this study was to investigate the effect of increasing degrees of lipid peroxidation on structure and function of the small intestine of nursery pigs. A total of 216 pigs (mean body weight was 6·5 kg) were randomly allotted within weight blocks and sex and fed one of five experimental diets for 35 d (eleven pens per treatment with three to four pigs per pen). Treatments included a control diet without added lipid, and diets supplemented with 6 % soyabean oil that was exposed to heat (80°C) and constant oxygen flow (1 litre/min) for 0, 6, 9 and 12 d. Increasing lipid peroxidation linearly reduced feed intake (P<0·001) and weight gain (P=0·024). Apparent faecal digestibility of gross energy (P=0·001) and fat (P<0·001) decreased linearly as the degree of peroxidation increased. Absorption of mannitol (linear, P=0·097) and d-xylose (linear, P=0·089), measured in serum 2 h post gavage with a solution containing 0·2 g/ml of d-xylose and 0·3 g/ml of mannitol, tended to decrease progressively as the peroxidation level increased. Increasing peroxidation also resulted in increased villi height (linear, P<0·001) and crypt depth (quadratic, P=0·005) in the jejunum. Increasing peroxidation increased malondialdehyde concentrations (quadratic, P=0·035) and reduced the total antioxidant capacity (linear, P=0·044) in the jejunal mucosa. In conclusion, lipid peroxidation progressively diminished animal performance and modified the function and morphology of the small intestine of nursery pigs. Detrimental effects were related with the disruption of redox environment of the intestinal mucosa.

Influence of laxatives on gastric emptying in healthy Warmblood horses evaluated with the D-xylose absorption test.

The use of laxatives is crucial in the treatment of horses with large colon impaction. To reach the impacted mass, the laxative must leave the stomach and pass through the small intestine. The aim of this study was to determine whether the most frequently used saline and lubricant laxatives influence gastric emptying. Six fasted normal adult Warmblood horses were used in a randomized study design with five laxative trials (1.8% sodium sulfate [1.8% Na2SO4], 4.2% magnesium sulfate [4.2% MgSO4], mineral oil [MOil], 25% sodium sulfate [25% Na2SO4], 25% magnesium sulfate [25% MgSO4]) and two trials with water (at either 20 ml/kg BW [Water 20] or 4 ml/kg BW [Water 4]), administered via nasogastric intubation. For indirect measurement of liquid-phase gastric emptying, a liquid passage marker (0.5 g D-xylose/kg BW as 10% solution) was added to each trial. Serum samples were collected at pre-determined time points for pharmacokinetic analysis. The time to reach maximum serum concentration (T(max)) was considered as gastric emptying rate. Significant differences were detected for T(max) of 4.2% MgSO4 compared to Water 20 and for T(max), the maximum serum concentration (C(max)) and the area under the curve determined up to 90 min (AUC90) of 25% Na2SO4 and 25% MgSO4 compared to Water 4. Neither 1.8% Na2SO4, nor MOil delayed gastric emptying rate compared to water (Water 20, Water 4, respectively). 4.2% MgSO4 as well as 25% Na2SO4 and 25% MgSO4 significantly delayed gastric emptying rate in comparison to water (Water 20, Water 4, respectively).

Prebiotic and other health-related effects of cereal-derived arabinoxylans, arabinoxylan-oligosaccharides, and xylooligosaccharides.

Arabinoxylans (AX) from cereals are cell wall components that constitute an important part of the dietary fiber intake in humans. Enzymatic hydrolysis of AX yields arabinoxylan-oligosaccharides (AXOS), consisting of arabinoxylooligosaccharides and xylooligosaccharides (XOS). This reaction takes place in the production of AXOS and of cereal-derived food products such as bread and beer, as well as in the colon upon ingestion of AX. This review mainly focuses on the available evidence that AXOS and XOS exert prebiotic effects in the colon of humans and animals through selective stimulation of beneficial intestinal microbiota. In addition, in vitro experiments and in vivo intervention studies on animals or humans are discussed that have investigated potential health-related effects resulting from the dietary intake of AX, AXOS, or XOS.

Novel L-xylose derivatives as selective sodium-dependent glucose cotransporter 2 (SGLT2) inhibitors for the treatment of type 2 diabetes.

The prevalence of diabetes throughout the world continues to increase and has become a major health issue. Recently there have been several reports of inhibitors directed toward the sodium-dependent glucose cotransporter 2 (SGLT2) as a method of maintaining glucose homeostasis in diabetic patients. Herein we report the discovery of the novel O-xyloside 7c that inhibits SGLT2 in vitro and urinary glucose reabsorption in vivo.

Xylose as a carrier for boron containing compounds.

A xylosylated carborane was synthesized by standard carbohydrate methodology and tested on normal HFL-1 cells as well as transformed T24 cells. The xylosylated carborane initiated glycosaminoglycan (GAG) synthesis in both cell lines and treatment with the carborane gave a pronounced translocation of proteoglycans to the nuclei of T24 cells. However, most of the boron-containing compounds were secreted to the medium. We conclude that xylosides carrying carboranes are not suitable for boron neutron capture therapy (BNCT) for T24 cells. However, the uptake of boron-containing xyloside, the GAG priming capacity, and the nuclear translocation of glypican-1 make this xyloside a candidate for further investigation for selectivity toward other tumor cell lines.

Plasma citrulline concentration: a reliable marker of small bowel absorptive capacity independent of intestinal inflammation.

OBJECTIVES: Postabsorptive plasma citrulline concentration has been proposed as a reliable marker of small bowel absorptive capacity in short bowel patients. The aim of this study was to address the potentially confounding impact of intestinal inflammation. METHODS: Fifty-five patients were selected according to diagnosis, small bowel length, and degree of bowel inflammation. (a) Crohn's disease (CD) with massive small bowel resection leaving 220) (N = 7), (d) CD without resection or active inflammation (normal CRP and CDAI <150) (N = 9), (e) mesenteric infarction (MI) with resection leaving

Lack of carcinogenicity of D-xylose given in the diet to F344 rats for two years.

The two year carcinogenicity of D-xylose was examined in groups of 50 male and 50 female F344 rats at dietary doses of 0% (control), 2.5% and 5%. The doses were selected on the basis of results from a 13-week subchronic toxicity study. Growth suppression and soft feces were observed in male and female rats of the 5% group. However, no significant differences from the controls were noted with regard to clinical signs, mortality and hematological findings. Decrease in absolute weight and increase in relative weight of the brain in males, and decrease of absolute kidney weight in females were observed in the 5% group, but there were no remarkable histopathological changes. A variety of tumors developed in all groups, including the controls, but all were histologically similar to those known to occur spontaneously in F344 rats, and no statistically significant increase in the incidence of any type of neoplastic lesion was found for either sex in the treated groups. Thus, it was concluded that, under the present experimental conditions, D-xylose is not carcinogenic to F344 rats.

Effect of xylooligosaccharide intake on severe constipation in pregnant women.

Xylooligosaccharides (XOS) are mainly composed of two or three xylose units with beta-1,4 linkages. They are obtained by hemicellulose hydrolysis, which is relatively abundant in the cell walls of grains. XOS increases the number of intestinal Bifidobacterium in humans, and maintains the fecal water content within the normal range. To examine the effect of XOS intake on severe constipation in pregnancy, which is predominant in the third trimester, thirty constipated pregnant women were treated with 4.2 g XOS daily for 4 wk. During the study, the clinical efficacy was assessed using a daily diary. The subjects indicated the number of stools and the clinical symptom scores. Twenty-nine subjects completed the study. The mean number of stools was 1.1 +/- 0.4 in the pre-treatment week, and increased in weeks 1-4 of XOS administration to 5.3 +/- 2.1, 5.9 +/- 2.5, 6.2 +/- 2.2 and 6.7 +/- 1.9, respectively. At the end of the study, 27 subjects could defecate spontaneously. The occurrence of very loose or very hard stools decreased and the stool consistency normalized. The stool color changed from dark to yellowish brown. No side effects were observed. XOS intake was highly effective for the reduction of severe constipation in pregnant women without adverse effects.

Aldose reductase and the importance of experimental design.

Kinetic studies on the AR (aldose reductase) protein have shown that it does not behave as a classical enzyme in relation to ring aldose sugars. As with non-enzymatic glycation reactions, there is probably a free-radical element involved derived from monosaccharide autoxidation. In the case of AR, there is free radical oxidation of NADPH by autoxidizing monosaccharides, which is enhanced in the presence of the NADPH-binding protein. Thus any assay for AR based on the oxidation of NADPH in the presence of autoxidizing monosaccharides is invalid, and tissue AR measurements based on this method are also invalid, and should be reassessed. AR exhibits broad specificity for both hydrophilic and hydrophobic aldehydes that suggests that the protein may be involved in detoxification. The last thing we would want to do is to inhibit it. ARIs (AR inhibitors) have a number of actions in the cell which are not specific, and which do not involve them binding to AR. These include peroxy-radical scavenging and effects of metal ion chelation. The AR/ARI story emphasizes the importance of correct experimental design in all biocatalytic experiments. Developing the use of Bayesian utility functions, we have used a systematic method to identify the optimum experimental designs for a number of kinetic model data sets. This has led to the identification of trends between kinetic model types, sets of design rules and the key conclusion that such designs should be based on some prior knowledge of K (m) and/or the kinetic model. We suggest an optimal and iterative method for selecting features of the design such as the substrate range, number of measurements and choice of intermediate points. The final design collects data suitable for accurate modelling and analysis and minimizes the error in the parameters estimated, and is suitable for simple or complex steady-state models.

Labeled acetate to assess intestinal absorption in critically ill patients.

OBJECTIVE: To compare the absorption of carbon-13(13C) acetate-enriched nutrients with D-xylose absorption. DESIGN: Prospective cohort observational study. SETTING: Surgical intensive care unit of a university hospital. PATIENTS: A total of 24 critically ill patients requiring enteral nutritional support. INTERVENTION: The patients were divided into three groups according to the route of 13C acetate administration: 1) gastric, 2) jejunal, and 3) intravenous. D-xylose was administered via the same route as enteral nutrition. MEASUREMENTS AND MAIN RESULTS: 13C acetate absorption and oxidation were reflected by pulmonary 13CO2 excretion. Breath 13CO2 isotopic enrichment was measured by mass spectrometry. 13C acetate absorption was rapid, and D-xylose absorption was depressed in all three groups, compared with the normal values (p <.0001). Breath CO isotopic enrichment was similar after intravenous and jejunal administration but slightly delayed during the first 240 mins after gastric administration (p <.01). Enteral feeding was well tolerated: mean energy delivery amounted to 77%, 88%, and 86% of measured resting energy expenditure on days 1-3. CONCLUSIONS: Gastric and jejunal 13C acetate are rapidly absorbed in critically ill surgical patients requiring enteral nutrition, contrasting with a depressed or delayed D-xylose absorption. 13CO2 recovery kinetics was similar after jejunal or intravenous 13C acetate and slightly depressed after gastric administration. Further studies are required to determine the value of labeled nutrients to assess gastric emptying and intestinal absorption.

Optimization of glycosidases production by Pseudoalteromonas issachenkonii KMM 3549(T).

AIMS: The present work aimed to design an optimized medium to yield a higher production of glycosides by Pseudoalteromonas issachenkonii KMM 3549(T). METHODS AND RESULTS: Higher levels of fucoidan hydrolase, alginase, laminaranase and b-N-acetylglucosaminidase production were obtained with peptone concentrations ranging from 2.5 g l(-1) to 10 g l(-1), while the presence of both yeast extract and glucose did not affect enzyme production. The activity of fucoidan hydrolase and laminaranase increased up to 4.83 microM h(-1) mg(-1) and 19.23 microM h(-1) mg(-1) protein, respectively, in growth media containing xylose (1.0 g l(-1)), laminarin (0.5 g l(-1)) or alginate (0.5 g l(-1)), and production of b-N-acetylglucosaminidase substantially increased in the presence of fucoidan (0.5 g l(-1)) or galactose (1 g l(-1)). All polysaccharides tested in concentrations of 0.5 g l(-1) fucoidan and 0.2 g l(-1) fucose induced production of alginase (up to 5.06 microM h(-1) mg-1 protein). CONCLUSIONS: The production of glycosidases is not only stimulated by the presence of algal polysaccharides, but may also be stimulated by monosaccharides (e.g. xylose). SIGNIFICANCE AND IMPACT OF THE STUDY: The production of glycosidases by Pseudoalteromonas issachenkonii KMM 3549(T) was significantly improved by using a simple nutrient medium containing peptone (2.5 g l(-1)) and xylose (5.0 g l(-1)) in 100% natural seawater.

D-xylose absorption after urinary orthotopic bladder replacement: colon neobladder compared with ileal neobladder.

BACKGROUND: To evaluate the digestive and absorptive status using the D-xylose test in patients who underwent radical cystectomy and orthotopic bladder replacement either by colon or ileal segment. METHODS: D-xylose serum levels after an oral load, nutritional status, plasma vitamin B12 levels, and acid-base and electrolyte balances were studied in 18 patients with colon neobladder and 12 patients with ileal neobladder. Mean follow-up period was 51 months. Results of both types of bladder replacement and a healthy control group were compared. RESULTS: Although no significant difference in the changes of plasma levels of D-xylose after oral load was observed between patients with colon neobladder and healthy controls, plasma levels of D-xylose 90 min after oral load in patients with ileal neobladder were significantly lower than those with colon neobladder. In contrast, there was no significant difference in nutritional status, plasma levels of vitamin B12, and acid-base and electrolyte balances between patients with colon and ileal neobladders. CONCLUSION: Despite acceptable nutritional status, intestinal malabsorption might be present in patients with ileal neobladder, as indicated by the plasma levels of D-xylose, while the colon neobladder group showed no significant differences compared with normal controls. Therefore, absorptive and metabolic status should be carefully monitored after ileal neobladder creation.

Ritonavir combination therapy restores intestinal function in children with advanced HIV disease.

OBJECTIVES: To investigate the intestinal absorptive processes in children with HIV infection before and after treatment with combination therapy that includes ritonavir. To test the hypothesis that combination therapy improves intestinal function. DESIGN: Intestinal function tests were performed in 10 children with advanced HIV disease at the enrollment and after 3 and 6 months of therapy with ritonavir combined with two HIV reverse transcriptase inhibitors. HIV viral load and CD4 cell counts were also determined; body weight was monitored. METHODS: The D-xylose absorption test, the steatocrit and the determination of fecal alpha1-antitrypsin concentration were used to evaluate carbohydrate and fat absorption, as well as fecal protein loss. Serum iron levels were measured to indirectly evaluate iron absorption. HIV-1 RNA-polymerase chain reaction (PCR) and immunofluorescence imaging were used to evaluate virologic and immunologic responses. RESULTS: In all, 9 children had carbohydrate malabsorption, 3 steatorrhea, 2 protein loss, and 7 iron deficiency. Most tests produced normal results after 3 months of therapy, and all abnormalities were abolished 6 months after institution of combination therapy. Mean results of each of four absorption tests were significantly changed on combination therapy. Viral load was progressively reduced and CD4 count was increased, with an inverse relationship. An evident shift of body weight pattern toward catch-up growth was observed in all children. CONCLUSIONS: Ritonavir combination therapy results in prompt and sustained restoration of intestinal function, which is associated with reduction in viral load, increase in CD4 counts, and gain in body weight.

[A 13-week subchronic toxicity study of D-xylose in F344 rats].

A 13-week subchronic toxicity study of D-xylose was performed in male and female F344 rats at dose levels of 0%, 0.2%, 0.6%, 1.7%, and 5% D-xylose in the CRF-1 powder diet to determine the maximum tolerable dose (MTD) for subsequent investigation of carcinogenicity. Rats were randomly allocated to 5 groups each consisting of 10 males and 10 females. Rats were randomly allocated to 5 groups each consisting of 10 males and 10 females. No treated groups showed changes in body weight gain or food intake, and all animals survived until the end of the experiment. Hematological examination revealed significant increases in RBC, Hb, and Ht in the male groups treated with 0.6% and 5% concentrations, whereas these values decreased significantly in all of the female groups treated with D-xylose. However, no clear dose-response effect was observed in the hematological data in either males or females given D-xylose. Serum biochemistry studies revealed decreases in AsT in the 0.2% and 5% D-xylose group male and 0.2%, 1.7%, and 5% group female, compared to the control value. However, the changes were not considered specific because of the lack of any clear dose-response effect. In addition, no histopathological changes indicating obvious toxicity of D-xylose were observed in the livers of either sex treated with D-xylose. Based on these data, the MTD of D-xylose in F344 rats of both sexes is judged to be 5% or more in the diet.

Increase of xylitol yield by feeding xylose and glucose in Candida tropicalis.

Candida tropicalis, a strain isolated from the sludge of a factory manufacturing xylose, produced a high xylitol concentration of 131 g/l from 150 g/l xylose at 45 h in a flask. Above 150 g/l xylose, however, volumetric xylitol production rates decreased because of a lag period in cell growth. In fed-batch culture, the volumetric production rate and xylitol yield from xylose varied substantially with the controlled xylose concentration and were maximum at a controlled xylose concentration of 60 g/l. To increase the xylitol yield from xylose, feeding experiments using different ratios of xylose and glucose were carried out in a fermentor. The maximum xylitol yield from 300 g/l xylose was 91% at a glucose/xylose feeding ratio of 15%, while the maximum volumetric production rate of xylitol was 3.98 g l-1 h-1 at a glucose/xylose feeding ratio of 20%. Xylitol production was found to decrease markedly as its concentration rose above 250 g/l. In order to accumulate xylitol to 250 g/l, 270 g/l xylose was added in total, at a glucose/xylose feeding ratio of 15%. Under these conditions, a final xylitol production of 251 g/l, which corresponded to a yield of 93%, was obtained from 270 g/l xylose in 55 h.