Effects of pre-slaughter fasting on antemortem skeletal muscle protein degradation levels and postmortem muscle free amino acid concentrations in broiler chickens.

This study investigated the effects of pre-slaughter fasting time on the relationship between skeletal muscle protein degradation levels at slaughter and chicken meat quality after 48 h of postmortem aging. Twenty-four broiler chicks at 0 d of age were used in this study until 28 d of age. At 27 d of age, the chickens were assigned to 4 treatment groups: 0 h of fasting (0H), 8 h of fasting (8H), 16 h of fasting (16H), or 24 h of fasting (24H). They were slaughtered at 28 d of age. Blood samples were collected before fasting and immediately before slaughter. Plasma Nτ-methylhistidine concentration, an index of skeletal muscle protein degradation level, and muscle free amino acid concentration were analyzed. Antemortem changes in individual plasma Nτ-methylhistidine concentrations were significantly increased in 8H, 16H, and 24H compared to that in 0H (P < 0.05). After 48 h of postmortem storage, the glutamic acid content in the pectoralis major muscles increased with fasting time (P < 0.05), and the umami taste of chicken soup in the fasting groups (8H, 16H, 24H) was higher than that in the 0H group (P < 0.05). The antemortem changes in plasma Nτ-methylhistidine concentrations were correlated with glutamic acid content in the pectoralis major muscles (r = 0.57, P < 0.05) and umami taste (r = 0.66, P < 0.05). These results suggest that skeletal muscle protein degradation levels at slaughter are related to postmortem chicken meat quality, especially glutamic acid content and umami taste.

Association between fasting stress hyperglycemia ratio and contrast-induced acute kidney injury in coronary angiography patients: a cross-sectional study.

Aims: Stress hyperglycemia ratio (SHR), an emerging indicator of critical illness, exhibits a significant association with adverse cardiovascular outcomes. The primary aim of this research endeavor is to evaluate the association between fasting SHR and contrast-induced acute kidney injury (CI-AKI). Methods: This cross-sectional study comprised 3,137 patients who underwent coronary angiography (CAG) or percutaneous coronary intervention (PCI). The calculation of fasting SHR involved dividing the admission fasting blood glucose by the estimated mean glucose obtained from glycosylated hemoglobin. CI-AKI was assessed based on elevated serum creatinine (Scr) levels. To investigate the relationship between fasting SHR and the proportion of SCr elevation, piecewise linear regression analysis was conducted. Modified Poisson's regression analysis was implemented to evaluate the correlation between fasting SHR and CI-AKI. Subgroup analysis and sensitivity analysis were conducted to explore result stability. Results: Among the total population, 482 (15.4%) patients experienced CI-AKI. Piecewise linear regression analysis revealed significant associations between the proportion of SCr elevation and fasting SHR on both sides (≤ 0.8 and > 0.8) [ß = -12.651, 95% CI (-23.281 to -2.022), P = 0.020; ß = 8.274, 95% CI (4.176 to 12.372), P < 0.001]. The Modified Poisson's regression analysis demonstrated a statistically significant correlation between both the lowest and highest levels of fasting SHR and an increased incidence of CI-AKI [(SHR < 0.7 vs. 0.7 ≤ SHR < 0.9) ß = 1.828, 95% CI (1.345 to 2.486), P < 0.001; (SHR ≥ 1.3 vs. 0.7 ≤ SHR < 0.9) ß = 2.896, 95% CI (2.087 to 4.019), P < 0.001], which was further validated through subgroup and sensitivity analyses. Conclusion: In populations undergoing CAG or PCI, both lowest and highest levels of fasting SHR were significantly associated with an increased occurrence of CI-AKI.

Mechanism of skeletal muscle atrophy by muscle fiber types in male rats under long-term fasting stress.

Fasting induces metabolic changes in muscles, which are differentiated by muscle fiber type. In this study, the mechanism of fasting-induced muscle atrophy in rats was examined to determine the differences between muscle fiber types in energy production. Fasting for 96 h did not alter the weight of the soleus (SOL), a fiber type I muscle, but did significantly reduce the weight of gastrocnemius (GM), a fiber type II muscle. GM, SOL and blood pregnenolone and testosterone levels decreased under fasting, which induced energy deprivation, whereas corticosterone (CORT) levels significantly increased. However, the expression of 3ß-HSD and P45011ß in GM was unaffected by fasting. The decrease in GM weight may be due to decreased levels of testosterone and reduced synthesis of mammalian target of rapamycin (mTOR). Significant increases in CORT both GM and SOL were associated with increases in the amount of branched-chain amino acids available for energy production. However, decreased levels of mTOR and IGF1 and increased levels of CORT and IL-6 in SOL suggest that GM proteolysis was followed by SOL proteolysis for additional energy production. In conclusion, IGF1 levels decreased significantly in SOL, whereas those of IL-6 significantly increased in SOL and blood but decreased in GM. Blood branched-chain amino acids (BCAA) levels were unaffected due to fasting, whereas an increase was noted in the levels of BCAA in GM and SOL. These results show that fasting for 96 h restricts energy supply, producing fast-twitch muscle atrophy followed by slow-twitch muscle atrophy.

The impact of fasting stress hyperglycemia ratio, fasting plasma glucose and hemoglobin A1c on in-hospital mortality in patients with and without diabetes: findings from the China acute myocardial infarction registry.

BACKGROUND: Stress hyperglycemia was positively associated with poor prognosis in individuals with acute myocardial infarction (AMI). However, admission glucose and stress hyperglycemia ratio (SHR) may not be the best indicator of stress hyperglycemia. We performed this study to evaluate the comparative prognostic value of different measures of hyperglycemia (fasting SHR, fasting plasma glucose [FPG], and hemoglobin A1c [HbA1c]) for in-hospital mortality in AMI patients with or without diabetes. METHODS: In this prospective, nationwide, multicenter China Acute Myocardial Infarction (CAMI) registry, 5,308 AMI patients including 2081 with diabetes and 3227 without diabetes were evaluated. Fasting SHR was calculated using the formula [(first FPG (mmol/l))/(1.59×HbA1c (%)-2.59)]. According to the quartiles of fasting SHR, FPG and HbA1c, diabetic and non-diabetic patients were divided into four groups, respectively. The primary endpoint was in-hospital mortality. RESULTS: Overall, 225 (4.2%) patients died during hospitalization. Individuals in quartile 4 had a significantly higher rate of in-hospital mortality compared with those in quartile 1 in diabetic cohort (9.7% vs. 2.0%; adjusted odds ratio [OR] 4.070, 95% CI 2.014-8.228) and nondiabetic cohort (8.8% vs. 2.2%; adjusted OR 2.976, 95% CI 1.695-5.224). Fasting SHR was also correlated with higher in-hospital mortality when treated as a continuous variable in diabetic and nondiabetic patients. Similar results were observed for FPG either as a continuous variable or a categorical variable. In addition, fasting SHR and FPG, rather than HbA1c, had a moderate predictive value for in-hospital mortality in patients with diabetes (areas under the curve [AUC] for fasting SHR: 0.702; FPG: 0.689) and without diabetes (AUC for fasting SHR: 0.690; FPG: 0.693). The AUC for fasting SHR was not significantly different from that of FPG in diabetic and nondiabetic patients. Moreover, adding fasting SHR or FPG to the original model led to a significant improvement in C-statistic regardless of diabetic status. CONCLUSIONS: This study indicated that, in individuals with AMI, fasting SHR as well as FPG was strongly associated with in-hospital mortality regardless of glucose metabolism status. Fasting SHR and FPG might be considered as a useful marker for risk stratification in this population. TRIAL REGISTRATION: ClinicalTrials.gov NCT01874691.

Fasting stress hyperglycemia ratio and in-hospital mortality after acute myocardial infarction in patients with different glucose metabolism status: Results from China acute myocardial infarction registry.

AIMS: To evaluate the predictive value of fasting stress hyperglycemia ratio (SHR) for in-hospital mortality in patients with acute myocardial infarction (AMI) under different glucose metabolism status. METHODS: We evaluated 5,308 AMI patients from the prospective, nationwide, multicenter China Acute Myocardial Infarction (CAMI) registry, of which 2,081 had diabetes. Fasting SHR was calculated by the formula [(first fasting plasma glucose (mmol/l))/(1.59 × HbA1c (%)-2.59)]. Patients were divided into high and low fasting SHR groups according to the optimal fasting SHR thresholds to predict in-hospital mortality for patients with and without diabetes, respectively. The primary endpoint was in-hospital mortality. RESULTS: The optimal cutoff values of SHR were 1.06 and 1.26 for patients with and without diabetes. Patients with high fasting SHR presented higher in-hospital mortality than those with low fasting SHR in both cohorts with diabetes (7.9% vs 2.2%; OR adjusted 3.159, 95% CI 1.932-5.165; OR IPTW 3.311, 95%CI 2.326-4.713) and without diabetes (10.1% vs 2.5%; OR adjusted 3.189, 95%CI 2.161-4.705; OR IPTW 3.224, 95%CI 2.465-4.217). The prognostic powers of fasting SHR for in-hospital mortality were similar in patients with different glucose metabolism status. Moreover, adding fasting SHR to the original model led to a significant improvement in C-statistic, net reclassification, and integrated discrimination regardless of diabetes status. CONCLUSIONS: This study firstly demonstrated a strong positive association between fasting SHR and in-hospital mortality in AMI patients with and without diabetes. Fasting SHR should be considered as a useful marker for risk stratification in AMI patients regardless of glucose metabolism status. TRIAL REGISTRATION: ClinicalTrials.gov NCT01874691.

Testicular induced corticosterone synthesis in male rats under fasting stress.

Testicular steroidogenesis is depressed by adrenal-secreted corticosterone (CORT) under stress. However, the mechanisms are not well understood. This study investigated the details of testicular steroidogenesis depression during fasting. Blood levels of adrenocorticotropic hormone secreted from the pituitary glands increased, but blood CORT was not changed in rats that fasted for 96 h, in spite of the rats being severely stressed. CORT in fasting adult male rats increased more than three times in the testis, but reduced testicular testosterone (T) and blood T levels to 5% and 2% of the control, respectively, was observed. The contents of T precursor (except PGN) were drastically reduced in the fasted-rat testes. Testicular CORT levels were elevated, but the enzymatic activity of cytochrome P45011ß, which produces CORT, remained unchanged. The enzymatic activities of 3ß-hydroxysteroid dehydrogenase (3ß-HSD), mediating the conversion of pregnenolone to progesterone, decreased in the fasted-rat testes. Thus, fasting suppressed testicular steroidogenesis by affecting the enzyme activity of 3ß-HSD in the testes and drastically reduced T and increased CORT synthesis. It can be considered that T synthesis involved in cell proliferation is suppressed due to lack of energy during fasting. Conversely, 11ß-hydroxylase enzyme activity was induced and CORT synthesis is increased to cope with the fasting stress. Hence, it can be concluded that CORT synthesis in the testes plays a role in the local defense response.

RNA-sequencing reveals the metabolism regulation mechanism of sheep skeletal muscle under nutrition deprivation stress.

Although the skeletal muscle is one of the main sites of metabolism, little is known about the molecular mechanisms involving its response to nutrition stress. The aim of the study was to screen the transcriptome of sheep muscle to identify the metabolism-related genes under nutrition deprivation stress. Ten healthy adult female Small-tailed Han sheep with similar age and weight were randomly divided into a normal group and fasted group. After 3 days, three sheep were randomly selected from each group and the semitendinosus samples were subjected to RNA-sequencing (RNA-seq) and a series of analyses and function annotations. Compared with the normal group, 391 differentially expressed genes (DEGs) were identified in the fasted group that had obvious weight loss, including 278 down-regulated and 113 up-regulated genes. Gene Ontology enrichment annotation classified 228 DEGs in the metabolic process, 11 of which were new genes and only Sheep_newGene_4578 had been annotated by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. The results of Clusters of Orthologous Groups annotation indicated that 11, 9, and 4 DEGs were respectively classified in lipid transport and metabolism, amino acid transport and metabolism, and carbohydrate transport and metabolism. In addition, KEGG enrichment analysis showed that there were not only pathways which were directly related to metabolisms such as protein digestion and absorption pathway, fatty acid metabolism pathway, and biosynthesis pathway of unsaturated fatty acids, but also PI3K-AKT pathway, AMPK pathway, MAPK pathway, and FoxO pathway which were important to metabolism among the top 20 pathways with the lowest significant Q value. The MCODE analysis of protein-protein interaction revealed that two identified subnetworks with top score were closely associated with metabolism. The correlation analysis showed that the mRNA levels of most of DEGs that might be related in the two subnetworks were significantly correlated respectively, and the mRNA levels of most of 10 metabolism-related DEGs including Sheep_newGene_4578 were significantly correlated. Finally, 16 random and 10 metabolism-related DEGs were chosen for confirmation by quantitative real-time PCR, demonstrating the same expression change as determined by RNA-seq. In conclusion, multiple interrelated metabolism-related DEGs in skeletal muscle contributed to the response of sheep to nutritional deprivation stress.