-
1.
Modulation of quorum sensing-associated virulence in bacteria: carbohydrate as a key factor.
Suresh, S, Alva, PP, Premanath, R
Archives of microbiology. 2021;(5):1881-1890
Abstract
Quorum sensing (QS) is a method of inter-cellular communication that permits bacteria to dispense information about cell density and to synchronize the gene expression accordingly. Gram-positive and Gram-negative bacteria utilize distinct quorum sensing mechanisms for effective pathogenesis. Virulence factor production by pathogenic bacteria is one of the important traits that is under the control of QS. A growing body of evidence has indicated the role of the nutritional environment notably by carbohydrates in dictating the QS-associated virulence gene regulation. The modulation of QS by carbohydrates mitigates the survival and establishment of the pathogen within its host which in turn leads to an increase in morbidity and mortality. This mini-review throws light on the predilection of pathogenic bacteria to rapidly regulate its QS-linked virulence gene expression based on the changing nutrient levels that assist them in prospering within diverse niches.
-
2.
Understanding the roles of osmolytes for acclimatizing plants to changing environment: a review of potential mechanism.
Ghosh, UK, Islam, MN, Siddiqui, MN, Khan, MAR
Plant signaling & behavior. 2021;(8):1913306
-
-
Free full text
-
Abstract
Abiotic stresses are significant environmental issues that restrict plant growth, productivity, and survival while also posing a threat to global food production and security. Plants produce compatible solutes known as osmolytes to adapt themselves in such changing environment. Osmolytes contribute to homeostasis maintenance, provide the driving gradient for water uptake, maintain cell turgor by osmotic adjustment, and redox metabolism to remove excess level of reactive oxygen species (ROS) and reestablish the cellular redox balance as well as protect cellular machinery from osmotic stress and oxidative damage. Perceiving the mechanisms how plants interpret environmental signals and transmit them to cellular machinery to activate adaptive responses is important for crop improvement programs to get stress-tolerant varieties. A large number of studies conducted in the last few decades have shown that osmolytes accumulate in plants and have strong associations with abiotic stress tolerance. Production of abundant osmolytes is needed for tolerance in many plant species. In addition, transgenic plants overexpressing genes for different osmolytes showed enhanced tolerance to various abiotic stresses. Many important aspects of their mechanisms of action are yet to be largely identified, especially regarding the relevance and relative contribution of specific osmolytes to the stress tolerance of a given species. Therefore, more efforts and resources should be invested in the study of the abiotic stress responses of plants in their natural habitats. The present review focuses on the possible roles and mechanisms of osmolytes and their association toward abiotic stress tolerance in plants. This review would help the readers in learning more about osmolytes and how they behave in changing environments as well as getting an idea of how this knowledge could be applied to develop stress tolerance in plants.
-
3.
The Low-Carbohydrate Diet: Short-Term Metabolic Efficacy Versus Longer-Term Limitations.
Barber, TM, Hanson, P, Kabisch, S, Pfeiffer, AFH, Weickert, MO
Nutrients. 2021;(4)
Abstract
BACKGROUND Diets have been a central component of lifestyle modification for decades. The Low-Carbohydrate Diet (LCD), originally conceived as a treatment strategy for intractable epilepsy (due to its association with ketogenesis), became popular in the 1970s and since then has risen to prominence as a weight loss strategy. OBJECTIVE To explore the efficacy, limitations and potential safety concerns of the LCD. DATA SOURCES We performed a narrative review, based on relevant articles written in English from a Pubmed search, using the terms 'low carbohydrate diet and metabolic health'. RESULTS Evidence supports the efficacy of the LCD in the short-term (up to 6-months) for reduction in fat mass and remission of Type 2 Diabetes Mellitus (T2D). However, the longer-term efficacy of the LCD is disappointing, with diminishment of weight loss potential and metabolic benefits of the LCD beyond 6-months of its adoption. Furthermore, practical limitations of the LCD include the associated restriction of food choices that restrict the acceptability of the LCD for the individual, particularly over the longer term. There are also safety concerns of the LCD that stem from nutritional imbalances (with a relative excess of dietary fat and protein intake with associated dyslipidaemia and increased risk of insulin resistance and T2D development) and ketotic effects. Finally, the LCD often results in a reduction in dietary fibre intake, with potentially serious adverse consequences for overall health and the gut microbiota. CONCLUSIONS Although widely adopted, the LCD usually has short-lived metabolic benefits, with limited efficacy and practicality over the longer term. Dietary modification needs tailoring to the individual, with careful a priori assessments of food preferences to ensure acceptability and adherence over the longer term, with avoidance of dietary imbalances and optimization of dietary fibre intake (primarily from plant-based fruit and vegetables), and with a posteriori assessments of the highly individual responses to the LCD. Finally, we need to change our view of diets from simply an excipient for weight loss to an essential component of a healthy lifestyle.
-
4.
Enzymatic glycosylation involving fluorinated carbohydrates.
Council, CE, Kilpin, KJ, Gusthart, JS, Allman, SA, Linclau, B, Lee, SS
Organic & biomolecular chemistry. 2020;(18):3423-3451
Abstract
Fluorinated carbohydrates, where one (or more) fluorine atom(s) have been introduced into a carbohydrate structure, typically through deoxyfluorination chemistry, have a wide range of applications in the glycosciences. Fluorinated derivatives of galactose, glucose, N-acetylgalactosamine, N-acetylglucosamine, talose, fucose and sialic acid have been employed as either donor or acceptor substrates in glycosylation reactions. Fluorinated donors can be synthesised by synthetic methods or produced enzymatically from chemically fluorinated sugars. The latter process is mediated by enzymes such as kinases, phosphorylases and nucleotidyltransferases. Fluorinated donors produced by either method can subsequently be used in glycosylation reactions mediated by glycosyltransferases, or phosphorylases yielding fluorinated oligosaccharide or glycoconjugate products. Fluorinated acceptor substrates are typically synthesised chemically. Glycosyltransferases are most commonly used in conjunction with natural donors to further elaborate fluorinated acceptor substrates. Glycoside hydrolases are used with either fluorinated donors or acceptors. The activity of enzymes towards fluorinated sugars is often lower than towards the natural sugar substrates irrespective of donor or acceptor. This may be in part attributed to elimination of the contribution of the hydroxyl group to the binding of the substrate to enzymes. However, in many cases, enzymes still maintain a significant activity, and reactions may be optimised where necessary, enabling enzymes to be used more successfully in the production of fluorinated carbohydrates. This review describes the current state of the art regarding chemoenzymatic production of fluorinated carbohydrates, focusing specifically on examples of the enzymatic production of activated fluorinated donors and enzymatic glycosylation involving fluorinated sugars as either glycosyl donors or acceptors.
-
5.
Effects of carbohydrate supplementation on aerobic exercise performance during acute high altitude exposure and after 22 days of acclimatization and energy deficit.
Bradbury, KE, Berryman, CE, Wilson, MA, Luippold, AJ, Kenefick, RW, Young, AJ, Pasiakos, SM
Journal of the International Society of Sports Nutrition. 2020;(1):4
Abstract
BACKGROUND The ergogenic effects of supplemental carbohydrate on aerobic exercise performance at high altitude (HA) may be modulated by acclimatization status. Longitudinal evaluation of potential performance benefits of carbohydrate supplementation in the same volunteers before and after acclimatization to HA have not been reported. PURPOSE This study examined how consuming carbohydrate affected 2-mile time trial performance in lowlanders at HA (4300 m) before and after acclimatization. METHODS Fourteen unacclimatized men performed 80 min of metabolically-matched (~ 1.7 L/min) treadmill walking at sea level (SL), after ~ 5 h of acute HA exposure, and after 22 days of HA acclimatization and concomitant 40% energy deficit (chronic HA). Before, and every 20 min during walking, participants consumed either carbohydrate (CHO, n = 8; 65.25 g fructose + 79.75 g glucose, 1.8 g carbohydrate/min) or flavor-matched placebo (PLA, n = 6) beverages. A self-paced 2-mile treadmill time trial was performed immediately after completing the 80-min walk. RESULTS There were no differences (P > 0.05) in time trial duration between CHO and PLA at SL, acute HA, or chronic HA. Time trial duration was longer (P < 0.05) at acute HA (mean ± SD; 27.3 ± 6.3 min) compared to chronic HA (23.6 ± 4.5 min) and SL (17.6 ± 3.6 min); however, time trial duration at chronic HA was still longer than SL (P < 0.05). CONCLUSION These data suggest that carbohydrate supplementation does not enhance aerobic exercise performance in lowlanders acutely exposed or acclimatized to HA. TRIAL REGISTRATION NCT, NCT02731066, Registered March 292,016.
-
6.
Effects of a commercially available branched-chain amino acid-alanine-carbohydrate-based sports supplement on perceived exertion and performance in high intensity endurance cycling tests.
Gervasi, M, Sisti, D, Amatori, S, Donati Zeppa, S, Annibalini, G, Piccoli, G, Vallorani, L, Benelli, P, Rocchi, MBL, Barbieri, E, et al
Journal of the International Society of Sports Nutrition. 2020;(1):6
Abstract
BACKGROUND Sports nutritional supplements containing branched-chain amino acids (BCAA) have been widely reported to improve psychological and biological aspects connected to central fatigue and performance in endurance exercise, although the topic is still open to debate. The aim of the present study was to determine whether the intake of a commercially available BCAA-based supplement, taken according to the manufacturer's recommendations, could affect the rating of perceived exertion (RPE) and performance indexes at the beginning (1d) and end of a 9-week (9w) scheduled high intensity interval training program, with an experimental approach integrating the determination of psychometric, performance, metabolic and blood biochemical parameters. METHODS This was a randomized double-blind placebo-controlled study. Thirty-two untrained, healthy young adults (20 males and 12 female) were enrolled. A high-intensity endurance cycling (HIEC) test was used to induce fatigue in the participants: HIEC consisted in ten 90 s sprints interspersed by ten 3 min recovery phases and followed by a final step time to exhaustion was used. In parallel with RPE, haematological values (creatine kinase, alanine, BCAA, tryptophan, ammonia and glucose levels), and performance indexes (maximal oxygen consumption - VO2max, power associated with lactate thresholds - WLT1, WLT2 and time to exhaustion - TTE) were assessed. All subject took the supplement (13.2 g of carbohydrates; 3.2 g of BCAA and 1.6 g of L-alanine per dose) or placebo before each test and training session. Dietary habits and training load were monitored during the entire training period. RESULTS The administration of the supplement (SU) at 1d reduced RPE by 9% during the recovery phase, as compared to the placebo (PL); at 9w the RPE scores were reduced by 13 and 21% during the sprint and recovery phase, respectively; at 9w, prolonged supplement intake also improved TTE and TRIMP. SU intake invariably promoted a rapid increase (within 1 h) of BCAA serum blood levels and prevented the post-HIEC tryptophan: BCAA ratio increase found in the PL group, at both 1d and 9w. There was no difference in dietary habits between groups and those habits did not change over time; no difference in glycemia was found between SU and PL. VO2max, WLT1 and WLT2 values improved over time, but were unaffected by supplement intake. CONCLUSIONS On the whole, these results suggest that i) the intake of the BCAA-based commercially available supplement used in this study reduces RPE as a likely consequence of an improvement in the serum tryptophan: BCAA ratio; ii) over time, reduced RPE allows subjects to sustain higher workloads, leading to increased TRIMP and TTE.
-
7.
Electrosynthesis of Biobased Chemicals Using Carbohydrates as a Feedstock.
Vedovato, V, Vanbroekhoven, K, Pant, D, Helsen, J
Molecules (Basel, Switzerland). 2020;(16)
Abstract
The current climate awareness coupled with increased focus on renewable energy and biobased chemicals have led to an increased demand for such biomass derived products. Electrosynthesis is a relatively new approach that allows a shift from conventional fossil-based chemistry towards a new model of a real sustainable chemistry that allows to use the excess renewable electricity to convert biobased feedstock into base and commodity chemicals. The electrosynthesis approach is expected to increase the production efficiency and minimize negative health for the workers and environmental impact all along the value chain. In this review, we discuss the various electrosynthesis approaches that have been applied on carbohydrate biomass specifically to produce valuable chemicals. The studies on the electro-oxidation of saccharides have mostly targeted the oxidation of the primary alcohol groups to form the corresponding uronic acids, with Au or TEMPO as the active electrocatalysts. The investigations on electroreduction of saccharides focused on the reduction of the aldehyde groups to the corresponding alcohols, using a variety of metal electrodes. Both oxidation and reduction pathways are elaborated here with most recent examples. Further recommendations have been made about the research needs, choice of electrocatalyst and electrolyte as well as upscaling the technology.
-
8.
Carbohydrate and bioactive compounds composition of starchy tropical fruits and tubers, in relation to pre and postharvest conditions: A review.
Rinaldo, D
Journal of food science. 2020;(2):249-259
Abstract
In some tropical countries, people are suffering from both undernourishment and noncommunicable disorders, such as overweight/obesity. Starchy tropical fruits and tubers are of particular interest for their carbohydrate content and for the micronutrients they provide. The present study summarizes the content in carbohydrate, phenolics, carotenoids, and vitamin C, as well as the antioxidant activity of a wide range of tropical fruits and tubers. The energy content of fruits and tubers studied is in the range of 1,200 to 1,800 kJ/100 g of dry weight. They are thus important staple foods and, due to their diversity and seasonality, they can provide energy all year long by alternating the resources in the human diet. Starchy fruit and tuber crops have antiobesity properties as they are bulky, rich in moisture, and contain less than 2% of fat. Noncolored fruit and tubers provide total phenolics at about 20 to 140 mEq/100 g fresh weight. They thus have a high antioxidant capacity, as related to their total phenolic content but also to the presence of carotenoids, such as lutein, mostly in Dioscorea bulbifera and cocoyam. Yellow and orange-fleshed varieties contain more total phenolics and also more provitamin A carotenoids than noncolored fleshed ones. The contents in total phenolic and carotenoid greatly vary with the species and variety. The influence of pre and postharvest conditions on micronutrient content is discussed. Further studies on new processing methods are needed to maximize polyphenols and carotenoids retention in the foods and increase the bioaccessibility of these compounds. PRACTICAL APPLICATION This paper provides information on the nutritional quality of starchy tropical fruits and tubers. Nutritional quality is studied from the point of view of providing energy and bioactive compounds. The paper aims to promote the use of local resources in tropical areas, which could ultimately limit the adverse effects of food globalization on noncommunicable disorders. It could also lead to tropical countries being less dependent on food imports.
-
9.
Titrating a modified ketogenic diet for patients with McArdle disease: A pilot study.
Løkken, N, Hansen, KK, Storgaard, JH, Ørngreen, MC, Quinlivan, R, Vissing, J
Journal of inherited metabolic disease. 2020;(4):778-786
Abstract
Glycogen storage disease type V (GSDV) is a rare inborn error of carbohydrate metabolism. Patients present with exercise intolerance due to blocked glycogen breakdown in skeletal muscle. Introducing alternative fuel substrates, such as ketone bodies (KBs), could potentially alleviate muscle symptoms. This pilot study investigates which of three different modified ketogenic diet regimes is optimal for GSDV-patients to follow in a future large-scale study. Participants were randomised to follow one of three diet regimes for 3 weeks (#1: 65%/15%/20%; #2: 75%/15%/10%, or #3: 80%/15%/5%, fat/protein/carbohydrate). The primary outcome was exercise tolerance assessed by heart rate (HR) changes during constant load cycling. Secondary outcomes included levels of ketosis, and changes in perceived exertion and indirect calorimetry measures during exercise. Ten GSDV-patients were included. Eight completed the study. The other two were excluded. Diet #3 showed the highest average KB level (1.1 mmol/L) vs #2 (0.5 mmol/L) and #1 (0.3 mmol/L). Five patients reported subjective symptom relief, all of whom were on diets #2 and #3. All diet regimes seemed to improve fatty acid oxidation rates and exercise capacity as indicated by a small decrease in HR and perceived exertion. The results of this open-label pilot study show that diets #2 and #3 induce ketosis and improve symptoms and exercise capacity in GSDV-patients. Diet #2 had the highest acceptability score and was superior or equal to diet #3 in all other parameters, except level of ketosis. Based on this, we suggest testing diet #2 in a large-scale, placebo-controlled study in GSDV.
-
10.
Effect of Oral Carbohydrate Intake During Labor on the Rate of Instrumental Vaginal Delivery: A Multicenter, Randomized Controlled Trial.
Simonet, T, Gakuba, C, Desmeulles, I, Corouge, J, Beucher, G, Morello, R, Gérard, JL, Ducloy-Bouthors, AS, Dreyfus, M, Hanouz, JL
Anesthesia and analgesia. 2020;(6):1670-1677
Abstract
BACKGROUND Carbohydrate intake during physical exercise improves muscle performance and decreases fatigue. We hypothesized that carbohydrate intake during labor, which is a period of significant physical activity, can decrease the instrumental vaginal delivery rate. METHODS In a multicenter, prospective, randomized, controlled trial, healthy adult pregnant women presenting with spontaneous labor were assigned to a "Carbohydrate" group (advised to drink 200 mL of apple or grape juice without pulp every 3 hours) or a "Fasting" group (water only). The primary outcome was the instrumental vaginal delivery rate. Secondary outcomes included duration of labor, rate of cesarean delivery, evaluation of maternal hunger, thirst, stress, fatigue, and overall feeling during labor by numeric rating scale (0 worst rating to 10 best rating), rate of vomiting, and hospital length of stay. Statistical analysis was performed on an intention-to-treat basis. The primary outcome was tested with the "Fasting" group as the reference group. The P values for secondary outcomes were adjusted for multiple comparisons. The differences between groups are reported with 99% confidence interval (CI). RESULTS A total of 3984 women were analyzed (2014 in the Carbohydrate group and 1970 in the Fasting group). There was no difference in the rate of instrumental delivery between the Carbohydrate (21.0%) and the Fasting (22.4%) groups (difference, -1.4%; 99% CI, -4.9 to 2.2). No differences were found between the Carbohydrate and the Fasting groups for the duration of labor (difference, -7 minutes; 99% CI, -25 to 11), the rate of cesarean delivery (difference, -0.3%; 99% CI, -2.4 to 3.0), the rate of vomiting (difference, 2.8%; 99% CI, 0.2-5.7), the degree of self-reported fatigue (difference, 1; 99% CI, 0-2), self-reported hunger (difference, 0; 99% CI, -1 to 1), thirst (difference, 0; 99% CI, -1 to 1), stress (difference, 0; 99% CI, -1 to 1), overall feeling (difference, 0; 99% CI, 0-0), and the length of hospitalization (difference, 0; 99% CI, -1 to 0). CONCLUSIONS Carbohydrate intake during labor did not modify the rate of instrumental vaginal delivery.