Impairment of sugar transport in the vascular system acts on nitrogen remobilization and nitrogen use efficiency in Arabidopsis.

Carbon (C) and nitrogen (N) metabolisms have long been known to be coupled, and this is required for adjusting nitrogen use efficiency (NUE). Despite this intricate relationship, it is still unclear how deregulation of sugar transport impacts N allocation. Here, we investigated in Arabidopsis the consequences of the simultaneous downregulation of the genes coding for the sugar transporters SWEET11, SWEET12, SWEET16, and SWEET17 on various anatomical and physiological traits ranging from the stem's vascular system development to plant biomass production, seed yield, and N remobilization and use efficiency. Our results show that intracellular sugar exchanges mediated by SWEET16 and SWEET17 proteins specifically impact vascular development but do not play a significant role in the distribution of N. Most importantly, we showed that the double mutant swt11 swt12, which has an impacted vascular development, displays an improved NUE and nitrogen remobilization to the seeds. In addition, a significant negative correlation between sugar and amino acids contents and the inflorescence stem radial growth exists, highlighting the complex interaction between the maintenance of C/N homeostasis and the inflorescence stem development. Our results thus deepen the link between sugar transport, C/N allocation, and vascular system development.

A vacuolar hexose transport is required for xylem development in the inflorescence stem.

In Angiosperms, the development of the vascular system is controlled by a complex network of transcription factors. However, how nutrient availability in the vascular cells affects their development remains to be addressed. At the cellular level, cytosolic sugar availability is regulated mainly by sugar exchanges at the tonoplast through active and/or facilitated transport. In Arabidopsis (Arabidopsis thaliana), among the genes encoding tonoplastic transporters, SUGAR WILL EVENTUALLY BE EXPORTED TRANSPORTER 16 (SWEET16) and SWEET17 expression has been previously detected in the vascular system. Here, using a reverse genetics approach, we propose that sugar exchanges at the tonoplast, regulated by SWEET16, are important for xylem cell division as revealed in particular by the decreased number of xylem cells in the swt16 mutant and the accumulation of SWEET16 at the procambium-xylem boundary. In addition, we demonstrate that transport of hexoses mediated by SWEET16 and/or SWEET17 is required to sustain the formation of the xylem secondary cell wall. This result is in line with a defect in the xylem cell wall composition as measured by Fourier-transformed infrared spectroscopy in the swt16swt17 double mutant and by upregulation of several genes involved in secondary cell wall synthesis. Our work therefore supports a model in which xylem development partially depends on the exchange of hexoses at the tonoplast of xylem-forming cells.

[Ketogenic Diet and its Evidence-Based Therapeutic Implementation in Endocrine Diseases]. / Ketogene Diät: evidenzbasierte therapeutische Anwendung bei endokrinologischen Erkrankungen.

Ketogenic Diet and its Evidence-Based Therapeutic Implementation in Endocrine Diseases Abstract. Abstract: The ketogenic diet (KD) is a high-fat and very low-carb diet, which has been used primarily for treatment of therapy-resistant epilepsy in children. Implementation of the KD in other target populations is increasingly being discussed. This literature review provides first indications for a clinical benefit of the KD in diabetes mellitus type 2 (T2DM) and polycystic ovarian syndrome (PCOS). In many analysed studies, KD led to significant weight loss and had beneficial effects on lipoprotein profile and insulin resistance. In half of the comparative studies with T2DM, the KD lead to signifiantly greater reductions in HbA1c-levels (HbA1c difference: -0.5 to -1.5 %) compared to reference diets (HbA1c difference: +0.2 to -0.5 %). Nevertheless, study results are too heterogenic for a general recommendation of the KD in this patient population.

Arabidopsis Natural Accessions Display Adaptations in Inflorescence Growth and Vascular Anatomy to Withstand High Salinity during Reproductive Growth.

Plant responses to abiotic stresses entail adaptive processes that integrate both physiological and developmental cues. However, the adaptive traits that are involved in the responses to a high soil salinity during reproductive growth are still poorly studied. To identify new clues, we studied the halophyte, Thellungiella salsuginea, and three Arabidopsis accessions, known as tolerant or salt-sensitive. We focused on the quantitative traits associated with the stem growth, sugar content, and anatomy of the plants subjected to the salt treatment, with and without a three-day acclimation, applied during the reproductive stage. The stem growth of Thellungiella salsuginea was not affected by the salt stress. By contrast, salt affected all of the Arabidopsis accessions, with a natural variation in the effect of the salt on growth, sugar content, and stem anatomy. In response to the high salinity, irregular xylem vessels were observed, independently of the accession's tolerance to salt treatment, while the diameter of the largest xylem vessels was reduced in the tolerant accessions. The stem height, growth rate, hexoses-to-sucrose ratio, and phloem-to-xylem ratio also varied, in association with both the genotype and its tolerance to salt stress. Our findings indicate that several quantitative traits for salt tolerance are associated with the control of inflorescence growth and the adjustment of the phloem-to-xylem ratio.

Lateral Transport of Organic and Inorganic Solutes.

Organic (e.g., sugars and amino acids) and inorganic (e.g., K⁺, Na⁺, PO42-, and SO42-) solutes are transported long-distance throughout plants. Lateral movement of these compounds between the xylem and the phloem, and vice versa, has also been reported in several plant species since the 1930s, and is believed to be important in the overall resource allocation. Studies of Arabidopsis thaliana have provided us with a better knowledge of the anatomical framework in which the lateral transport takes place, and have highlighted the role of specialized vascular and perivascular cells as an interface for solute exchanges. Important breakthroughs have also been made, mainly in Arabidopsis, in identifying some of the proteins involved in the cell-to-cell translocation of solutes, most notably a range of plasma membrane transporters that act in different cell types. Finally, in the future, state-of-art imaging techniques should help to better characterize the lateral transport of these compounds on a cellular level. This review brings the lateral transport of sugars and inorganic solutes back into focus and highlights its importance in terms of our overall understanding of plant resource allocation.

Is testing for postprandial hyperinsulinemic hypoglycemia after gastric bypass necessary?

INTRODUCTION: Postprandial hyperinsulinemic hypoglycemia (pHH) is an increasingly reported complication after Roux-en-Y gastric bypass (RYGB). As pHH can cause life-threatening emergencies if occurring without warning symptoms, challenge testing may detect patients at risk. The study objective was to determine the frequency of occurrence of pHH with or without symptoms of hypoglycemia after RYGB. METHODS: We undertook an observational cohort study of consecutive, unselected patients approximately one year after uncomplicated RYGB. To simulate normal habits, all patients received a standardized carbohydrate-rich solid mixed meal. Plasma glucose and insulin were measured at 30, 60, 90, 120, and 150 min thereafter. Symptoms were classified as autonomous or neuroglycopenic. Patients with hypoglycemia (plasma glucose <3.0 mmol/L [55 mg/dL]), were tested a second time with a protein-rich solid mixed meal. RESULTS: 113 patients were included. Total weight loss at the first follow-up check (14 ± 0.4 months) was 33.97 ± 9.3%. After the carbohydrate-rich meal, glucose dropped to <3.0 mmol/L in 13.2% (n = 15) of patients vs no drop to <3.0 mmol/L after a protein-rich meal. The pHH occurred in 11.5% (n = 13) of patients. Asymptomatic patients (5.3%, n = 6) carried an increased risk (p = 0.008) for pHH. One patient needed emergency treatment after sudden loss of consciousness after the carbohydrate-rich meal. CONCLUSIONS: The occurrence of pHH was quite high in our study population with 11.5% thereof 5.3% asymptomatic. We therefore suggest that detection of these patients warrants a screening of patients after RYGB. At-risk patients should than be adequately advised to avoid carbohydrate-rich meals in order to optimize risk management.

Refeeding syndrome in the frail elderly population: prevention, diagnosis and management.

Aging is linked to physiological and pathophysiological changes. In this context, elderly patients often are frail, which strongly correlates with negative health outcomes and disability. Elderly patients are often malnourished, which again is an independent risk factor for both frailty and adverse clinical outcomes. Malnutrition and resulting frailty can be prevented by adequate nutritional interventions. Yet, use of nutritional therapy can also have negative consequences, including a potentially life-threatening metabolic alteration called refeeding syndrome (RFS) in high-risk patients. RFS is characterized by severe electrolyte shifts (mainly hypophosphatemia, hypomagnesemia and hypokalemia), vitamin deficiency (mainly thiamine), fluid overload and salt retention leading to organ dysfunction and cardiac arrhythmias. Although the awareness of malnutrition among elderly people is well established, the risk of RFS is often neglected, especially in the frail elderly population. This partly relates to the unspecific clinical presentation and laboratory changes in the geriatric population. The aim of this review is to summarize recently published recommendations for the management of RFS based on current evidence from clinical studies adapted with a focus on elderly patients.

A Comparative Study on Carbohydrate Estimation: GoCARB vs. Dietitians.

GoCARB is a computer vision-based smartphone system designed for individuals with Type 1 Diabetes to estimate plated meals' carbohydrate (CHO) content. We aimed to compare the accuracy of GoCARB in estimating CHO with the estimations of six experienced dietitians. GoCARB was used to estimate the CHO content of 54 Central European plated meals, with each of them containing three different weighed food items. Ground truth was calculated using the USDA food composition database. Dietitians were asked to visually estimate the CHO content based on meal photographs. GoCARB and dietitians achieved comparable accuracies. The mean absolute error of the dietitians was 14.9 (SD 10.12) g of CHO versus 14.8 (SD 9.73) g of CHO for the GoCARB (p = 0.93). No differences were found between the estimations of dietitians and GoCARB, regardless the meal size. The larger the size of the meal, the greater were the estimation errors made by both. Moreover, the higher the CHO content of a food category was, the more challenging its accurate estimation. GoCARB had difficulty in estimating rice, pasta, potatoes, and mashed potatoes, while dietitians had problems with pasta, chips, rice, and polenta. GoCARB may offer diabetic patients the option of an easy, accurate, and almost real-time estimation of the CHO content of plated meals, and thus enhance diabetes self-management.

Are patients affected by mitochondrial disorders at nutritional risk?

OBJECTIVES: Patients with mitochondrial disorders (MD) frequently present with gastrointestinal complaints, mainly gastrointestinal dysmotility, that interfere with their food intake. A deterioration of their nutritional state may worsen the course of the disease. Our study aimed to evaluate a simple screening tool to identify nutritional risk and perform an extended nutritional assessment to explore the potential presence of deficiencies in this population compared with controls. METHODS: A prospective cohort study was conducted to compare outpatients with MD to matched healthy controls. Nutritional screening and full nutritional assessments were performed, including quantitative and qualitative dietary habits (7-d food log), body function and composition, and resting energy expenditure and quality of life (QoL) measurements. Blood and 24-h urine sample analyses were performed in the patient group. RESULTS: Twenty-six subjects were included in the study, with 11 in the patient group and 15 in the control group. No patient was deemed malnourished according to the nutritional risk score NRS-2002. When compared with the controls, however, the patients with MD had significantly lower muscle mass (P = 0.04), reduced handgrip strength (P = 0.07), and significant changes in QoL and pathologic creatinine height index, which indicate malnutrition. The patients with MD also had a significantly lower protein intake (P = 0.01). CONCLUSIONS: According to the current definition by the European Society of Clinical Nutrition and Metabolism (ESPEN) and the American Society of Parenteral and Enteral Nutrition (ASPEN), all patients fulfilled the criteria for malnutrition. Thus, the usual nutritional screening tool is less sensitive for chronically ill outpatients. These results provide a rationale to increase protein intake and adapt patients' energy stores to improve symptoms and QoL.