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Exercising with low muscle glycogen content increases fat oxidation and decreases endogenous, but not exogenous carbohydrate oxidation.
Margolis, LM, Wilson, MA, Whitney, CC, Carrigan, CT, Murphy, NE, Hatch, AM, Montain, SJ, Pasiakos, SM
Metabolism: clinical and experimental. 2019;:1-8
Abstract
BACKGROUND Initiating aerobic exercise with low muscle glycogen content promotes greater fat and less endogenous carbohydrate oxidation during exercise. However, the extent exogenous carbohydrate oxidation increases when exercise is initiated with low muscle glycogen is unclear. PURPOSE Determine the effects of muscle glycogen content at the onset of exercise on whole-body and muscle substrate metabolism. METHODS Using a randomized, crossover design, 12 men (mean ± SD, age: 21 ± 4 y; body mass: 83 ± 11 kg; VO2peak: 44 ± 3 mL/kg/min) completed 2 cycle ergometry glycogen depletion trials separated by 7-d, followed by a 24-h refeeding to elicit low (LOW; 1.5 g/kg carbohydrate, 3.0 g/kg fat) or adequate (AD; 6.0 g/kg carbohydrate, 1.0 g/kg fat) glycogen stores. Participants then performed 80 min of steady-state cycle ergometry (64 ± 3% VO2peak) while consuming a carbohydrate drink (95 g glucose +51 g fructose; 1.8 g/min). Substrate oxidation (g/min) was determined by indirect calorimetry and 13C. Muscle glycogen (mmol/kg dry weight), pyruvate dehydrogenase (PDH) activity, and gene expression were assessed in muscle. RESULTS Initiating steady-state exercise with LOW (217 ± 103) or AD (396 ± 70; P < 0.05) muscle glycogen did not alter exogenous carbohydrate oxidation (LOW: 0.84 ± 0.14, AD: 0.87 ± 0.16; P > 0.05) during exercise. Endogenous carbohydrate oxidation was lower and fat oxidation was higher in LOW (0.75 ± 0.29 and 0.55 ± 0.10) than AD (1.17 ± 0.29 and 0.38 ± 0.13; all P < 0.05). Before and after exercise PDH activity was lower (P < 0.05) and transcriptional regulation of fat metabolism (FAT, FABP, CPT1a, HADHA) was higher (P < 0.05) in LOW than AD. CONCLUSION Initiating exercise with low muscle glycogen does not impair exogenous carbohydrate oxidative capacity, rather, to compensate for lower endogenous carbohydrate oxidation acute adaptations lead to increased whole-body and skeletal muscle fat oxidation.
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Effect of Exogenous Application of Methyl Jasmonate on the Lipid and Carbohydrate Content and Composition of Winter Triticale ( Triticosecale Wittm.) Grain and the Severity of Fungal Infections in Triticale Plants and Grain.
Zalewski, K, Lahuta, LB, Martysiak-Żurowska, D, Okorski, A, Nitkiewicz, B, Zielonka, Ł
Journal of agricultural and food chemistry. 2019;(21):5932-5939
Abstract
Kernels of winter triticale ( Triticosecale Wittm. cv. Dinaro) were analyzed. In the autumn of 2015, the effect of methyl jasmonate (MJ) on the germination of triticale kernels and the development of triticale seedlings was analyzed in a laboratory before kernels were sown in experimental plots. Kernels harvested from plots in August 2016 were analyzed to determine their lipid and carbohydrate content and composition and the severity of fungal infections. Triticale grain was harvested at full maturity. The plots were sprayed with MJ at concentrations of 10-6 to 10-3 M in the stem elongation stage (200 L/ha) and in the early milk stage (300 L/ha). Other preventive treatments, fungicides, pesticides, or foliar fertilizers were not applied. Lipids of triticale kernels contained 20 fatty acids (FAs) with the highest proportion of linoleic acid. Methyl jasmonate did not exert a significant effect on the FA composition of kernel lipids treated with the plant hormone during the growing season. Statistical analysis did not reveal significant ( p < 0.05) differences in the total content of soluble carbohydrates in control kernels and in the kernels collected from triticale plants treated with MJ. Methyl jasmonate applied at a concentration of 10-3 M in BBCH stages 54 and 73 reduced the prevalence of stem base, leaf, and spike diseases. However, the severity of grain infections caused by mycotoxin-producing fungi increased in treatments where MJ was applied at a concentration of 10-5 M relative to the control treatment. The study describes the results noted in naturally infected plants and provides valuable inputs for agricultural practice, but further research is required to validate the presented findings.
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Are carbohydrate drinks more effective than preoperative fasting: A systematic review of randomised controlled trials.
Noba, L, Wakefield, A
Journal of clinical nursing. 2019;(17-18):3096-3116
Abstract
AIMS AND OBJECTIVES To evaluate current evidence to determine whether oral preoperative carbohydrate drinks shorten hospital stays, reduce insulin resistance and/or improve postoperative discomfort for patients undergoing abdominal or cardiac surgery. BACKGROUND Criticisms of standard preoperative fasting have forced practitioners to explore new ways of preparing patients for theatre. Consequently, the use of preoperative carbohydrate drinks prior to elective surgery has gained momentum. Current evidence regarding the efficacy of this treatment has been inconsistent and contradictory which prompted a review of the current literature. DESIGN A systematic review of randomised clinical trials (RCTs). METHODS In accordance with Prisma guidelines, the review incorporated a systematic, comprehensive search of English-language-only texts published between 2001-2018. The search focused on five databases (MEDLINE, EMBASE, CINAHL, British Nursing Index and ASSIA). Reference lists of relevant systematic reviews and studies located were also hand-searched for eligibility and further references. All RCTs investigating the effect of preoperative carbohydrate drinks on adult patients undergoing cardiac or abdominal surgery were included. The review excluded RCTs conducted on patients with type 1 or 2 diabetes mellitus and patients under the age of 18. RESULT The review included 22 RCTs with a total sample of 2,065 patients across thirteen countries. Nine different types of surgery were identified. No significant reductions in hospital stay were noted in 8 of the ten trials. Preoperative carbohydrate drinks significantly reduced insulin resistance and improved postoperative discomfort especially in patients undergoing laparoscopic cholecystectomy. No definite conclusion regarding the impact of preoperative carbohydrate drinks on gastric volume and gastric pH was noted. Similarly, no adverse events such as pulmonary aspiration were reported. CONCLUSION Preoperative carbohydrate drinks were found to be safe and can be administered up to 2 hr before surgery. Such drinks were also found to reduce insulin resistance and improve postoperative discomfort especially in patients undergoing laparoscopic cholecystectomy. However, there is insufficient evidence to definitively conclude what impact they have on length of hospital stay. RELEVANCE TO CLINICAL PRACTICE Patients undergoing surgery are often required to fast from midnight, while in some extreme cases patients are fasted for up to 24 hr prior to surgery. The main purpose of asking patients to undergo this prolonged fasting is to reduce the risk of aspiration. However, there is a general consensus that this traditional practice is out of date, and it is often associated with postoperative complications. On the other hand, current evidence suggests oral intake of fluids up to 90-180 min prior to surgery is safe and consumption of a preoperative carbohydrate drinks does not delay gastric emptying or affect gastric acidity.
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Unexplained case of hypophosphataemic rickets.
Godden, B, Hilditch, C, Agrawal, R
Journal of paediatrics and child health. 2019;(7):851-853
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All that a physician should know about FODMAPs.
Mehtab, W, Agarwal, A, Singh, N, Malhotra, A, Makharia, GK
Indian journal of gastroenterology : official journal of the Indian Society of Gastroenterology. 2019;(5):378-390
Abstract
A diet low in poorly absorbed, fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) is now considered as an effective strategy for symptoms control in patients with irritable bowel syndrome (IBS). The low FODMAP diet is administered in three phases, namely restriction of all dietary FODMAPs followed by rechallenge and then reintroduction of specific FODMAPs according to the tolerance of patients. A dietician should be involved in patients in whom a low FODMAP diet is planned. While restricting high FODMAPs, it is pertinent that patients are advised a well-balanced diet and suitable alternatives with low FODMAP contents in each food groups are prescribed. Strict adherence to a low FODMAP diet has been shown to improve symptoms, stool output, quality of life, and the overall well-being of patients with IBS. For those who do not respond to this dietary approach, a normal diet may be initiated and other treatment strategies (dietary or nondietary) should be considered. Interestingly, the low FODMAP diet has also been tried in other functional disorders, nonceliac gluten sensitivity, and even inflammatory bowel disease. Since the concept of FODMAP is relatively new, there is only limited data on the content of FODMAP in the Indian food items and there is a need to address this question. There is also a need for well-designed and adequately powered studies to explore the efficacy of low FODMAP diet in patients with IBS. In the present review article, we have compiled all the relevant information about FODMAPs with an objective to provide comprehensive information on FODMAPs to a physician.
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Copolymers containing carbohydrates and other biomolecules: design, synthesis and applications.
Ma, Z, Zhu, XX
Journal of materials chemistry. B. 2019;(9):1361-1378
Abstract
Glycopolymers are synthetic polymers containing pendant carbohydrate groups. Other biological compounds can be incorporated into glycopolymers to prepare both random and block copolymers aimed at bio-related applications: boronic acid can be introduced as a functional group to obtain crosslinked hydrogels; cholesterol and bile acids can be introduced to render the polymers more hydrophobic for the formation of micelles. Sugar-containing block copolymers with biocompatible blocks such as polypeptides, poly(ethylene glycol), poly(lactic acid) and poly(ε-caprolactone) were also prepared for potential application in drug carriers. These glycopolymers interact with lectins or lectin-containing surfaces as natural carbohydrate mimics. This review highlights the recent progress in the synthesis of random or block glycopolymers. Examples of the applications of glycopolymers in the separation and removal of toxins and bacteria, tumor cell recognition and glucose-responsive insulin delivery are presented and discussed.
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Interaction of carbohydrate-binding modules with poly(ethylene terephthalate).
Weber, J, Petrović, D, Strodel, B, Smits, SHJ, Kolkenbrock, S, Leggewie, C, Jaeger, KE
Applied microbiology and biotechnology. 2019;(12):4801-4812
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Abstract
Poly(ethylene terephthalate) (PET) is one of the most widely applied synthetic polymers, but its hydrophobicity is challenging for many industrial applications. Biotechnological modification of PET surface can be achieved by PET hydrolyzing cutinases. In order to increase the adsorption towards their unnatural substrate, the enzymes are fused to carbohydrate-binding modules (CBMs) leading to enhanced activity. In this study, we identified novel PET binding CBMs and characterized the CBM-PET interplay. We developed a semi-quantitative method to detect CBMs bound to PET films. Screening of eight CBMs from diverse families for PET binding revealed one CBM that possesses a high affinity towards PET. Molecular dynamics (MD) simulations of the CBM-PET interface revealed tryptophan residues forming an aromatic triad on the peptide surface. Their interaction with phenyl rings of PET is stabilized by additional hydrogen bonds formed between amino acids close to the aromatic triad. Furthermore, the ratio of hydrophobic to polar contacts at the interface was identified as an important feature determining the strength of PET binding of CBMs. The interaction of CBM tryptophan residues with PET was confirmed experimentally by tryptophan quenching measurements after addition of PET nanoparticles to CBM. Our findings are useful for engineering PET hydrolyzing enzymes and may also find applications in functionalization of PET.
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Increased carbohydrate production from carbon dioxide in randomly mutated cells of cyanobacterial strain Synechocystis sp. PCC 6714: Bioprocess understanding and evaluation of productivities.
Kamravamanesh, D, Slouka, C, Limbeck, A, Lackner, M, Herwig, C
Bioresource technology. 2019;:277-287
Abstract
Recently, several mutants of Synechocystis sp. PCC 6714 were obtained showing superior PHB content and productivities. Here, the most promising mutant named MT_a24 is compared in detail with the wild-type in controlled photobioreactors. In order to provide an easily scalable and alternative approach to the normally done two-step process -comprising of growth phase and limitation phase- a one-step cultivation was optimized. The multivariate experimental design approach was used for the optimization of the one-step, self-limiting media. During one-step cultivation of MT_a24 with optimized media 30 ± 4% (DCW) corresponding to 1.16 g L-1 PHB was obtained. Using pulse experiments it was demonstrated that phosphate is the key driver of glycogen synthesis in Synechocystis sp. PCC 6714 and it can be used to boost glycogen productivity. The maximum glycogen content acquired was 2.6 g L-1 (76.2% DCW) for mutant MT_a24 using phosphate feeding and carbon dioxide as carbon source.
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A randomized controlled trial of preoperative carbohydrate drinks on postoperative walking capacity in elective colorectal surgery.
Wongyingsinn, M, Luangchan, S, Tungsongsawat, S, Trakarnsanga, A, Lohsiriwat, V
Asia Pacific journal of clinical nutrition. 2019;(4):727-733
Abstract
BACKGROUND AND OBJECTIVES Routine overnight fasting may increase the risk of postoperative complications and delay postoperative recovery. Oral carbohydrate drinks have been shown to reduce glucose utilization and postoperative negative nitrogen balance while preserving muscle mass and strength. This randomized controlled trial aimed to examine whether preoperative oral carbohydrate drinks can enhance postoperative physical recovery in patients undergoing major colorectal surgery. METHODS AND STUDY DESIGN Seventy patients were randomly assigned to receive either a 12.5% oral carbohydrate drink or pure water. Patients in both groups received 800- mL of one of the drinks on the evening before surgery, and another 400-mL drink on the morning of the operative day. The primary outcomes were the distances covered in 2-minute-walk tests at 24, 48 and 72-hours and 6- minute walk tests at 7-10 days postoperatively. The secondary outcomes were the postoperative serum insulin and glucose concentrations, nitrogen balance, duration of hospital stay, and the patient satisfaction scores. RESULTS There were no significant differences in the characteristics of the two patients-groups. The postoperative 2-minute and 6-minute walk test distances, serum insulin and glucose concentrations of both groups were not statistically different. Patients receiving carbohydrate drink had more positive nitrogen balance than the control group. The duration of hospital stay and patient satisfaction scores were similar for both-groups. CONCLUSIONS There were no statistically significant differences in the postoperative walking capacities of patients receiving a carbohydrate drink or pure water; only the nitrogen balance on postoperative day 3 was higher for patients receiving the carbohydrate drink.
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Nutritional hypophosphatemic rickets secondary to Neocate® use.
Akhtar Ali, S, Mathalikunnel, A, Bhardwaj, V, Braskett, M, Pitukcheewanont, P
Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. 2019;(9):1887-1891
Abstract
Elemental formula is commonly used in children with feeding intolerance. We describe two, medically complex and feeding tube dependent, patients exclusively fed with Neocate® who subsequently developed hypophosphatemic rickets. Both patients had gross motor decline and pain with physical touch. They were found to have low serum phosphorus, normal calcium, and vitamin D studies, with elevated alkaline phosphatase suggestive of nutritional hypophosphatemia. Both courses were complicated by hypocalcemia following formula change and phosphorus supplementation, highlighting the need for careful management of phosphate repletion in affected individuals. Diligent serial electrolyte monitoring as well as attention to bone health is needed in conjunction with elemental nutrition. Formula change led to restoration of calcium and phosphorus homeostasis and radiographic improvement in these patients.