Metabolism and Nutrition Disorder

The aim of this study is to investigate when critically ill patients transition from a non-suppressible catabolism to a normal response to feeding. Endogenous production of glucose, fat and protein will be studied on a minimum of two occasions in mechanically ventilated ICU patients, in a fasted state and during parenteral nutrition. Substrate kinetics are estimated by a tracer dilution method using infusions of isotopically labeled glucose, glycerol and phenylalanine. Blood sampling for metabolomics analysis will be performed to elucidate potential biomarkers indicating an anabolic response to nutrition.

Introduction Sarcopenia is defined as progressive generalized loss of skeletal muscle mass, strength and function. Sarcopenia due to lack of physical activity is a known phenomenon and is usually observed as a normal part of aging or in certain diseases and pathogenic processes. Major associated factors causing development of sarcopenia may be summarized as interactions of environmental and hormonal factors, underlying diseases, activation of inflammatory pathways, mitochondrial dysfunction, reduced satellite cell numbers, and loss of neuromuscular junctions. Intensive care acquired weakness (ICU-AW) known formerly as critical illness polyneuropathy, is a diagnosis that becomes more common as survival rates from long ICU hospitalization are more prevalent. It is characterized by a primary axonal degeneration, without demyelination, that typically affects motor nerves more than sensory nerves. ICU-AW affects the limbs (particularly the lower extremities) in a symmetric pattern. Weakness is most notable in proximal neuromuscular areas (e.g., the shoulders and hip girdle). In addition, involvement of the respiratory muscles can occur and can impede weaning from mechanical ventilation. The pathophysiological mechanisms of ICU-acquired weakness are believed to be multifactorial. Some suspected factors include dysfunctional microcirculation and hyperglycemia. It has been shown that tight glucose control in ICU patients reduces the risk for ICU-AW (although it has been associated with other adverse events). Sodium channels channelopathy is also a researched cause for ICU-AW. Muscle loss in the ICU are usually related to bedridden condition and lack of mobility, increase in ubiquitination and inadequate protein administration associated with large negative nitrogen balance. In addition mechanical ventilation contributes greatly to this problem. This has been particularly relevant in post trauma/surgical long stayer patients. In the past years great progress was made in the investigation of protein balance, breakdown and synthesis using stable isotope tracers in various medical conditions. In a research performed in PICU (1-5) and ICU (6, 7) regarding the measurement of plasma amino acid during critical illness, stable phenylalanine, tyrosine leucine, arginine and citrulline isotope were used intravenously without any safety issue problem. Another study was performed on adults suffering from COPD with matched healthy adults, using stable isotopes of phenylalanine, tyrosine leucine, isoleucine and valine (8). During the study the isotopes were given parenterally as well as enterally. The study showed significant change in splanchnic extraction of various amino acids and higher turnover of BCAA in COPD patients. Using the theory that supplemental milk can compensate for the elevated turnover of BCAA in COPD patients, using the isotope analysis demonstrated that this theory was proven wrong and the conclusion was that alterations are present in BCAA metabolism despite normal plasma levels in normal weight COPD. Further research is needed to find a way to compensate for it. These studies and other recent studies (9-19) show us the safety regarding the use of stable isotope tracers whether IV or PO, while giving us the opportunity to assess the metabolism of amino acid in all sorts of pathological states. Hypothesis \& Aim of the study We think that based on current literature, there are important differences between critically ill patients and healthy population in the amino acid profile and distribution in the body as well as synthesis and breakdown. The aim of the study is to measure these differences in long ICU stayers (above 7 days) admitted in the ICU after surgical/trauma injury, and to try and help aiming future treatment and research in this field.

The goal of this study is to investigate the effects of a potato-based diet intervention on Chinese university students. Employing a randomized controlled double-blind trial design, the intervention will span 8 weeks. The primary objectives include: * Examining the impact of the potato-based diet intervention on the overall glucose and lipid metabolism levels of university students; * Exploring the interactions between the potato-based diet intervention and individual metabolic profiles and glucose-lipid metabolic pathways; * Analyzing the association between the potato-based diet intervention and gut health through gut microbiota analysis. Participants will undergo either the potato-based diet intervention or the control group treatment. Changes in waist circumference, blood pressure, blood glucose, and blood lipid levels will be observed to assess the effects of the potato-based diet on university students' health. Additionally, alterations in metabolic profiles and glucose-lipid metabolic pathways will be analyzed, along with gut microbiota analysis, to investigate the relationship between the potato-based diet and gut health.

The circadian regulation in mammals have been known for a long time. A special group of clock genes, organized in feedback loops, are responsible for the circadian regulation in both the SCN and peripheral organs. The central clock is mainly entrained by the light-dark cycle, while the peripheral ones in organs such as liver and intestine, are more influenced by the feeding-fasting cycles. The coordination of central and peripheral clocks is thought to be essential in the maintenance of physiological homeostasis.This study aim to investigate the association between biological rhythm and metabolism.