scholarly journals The wasting-associated metabolite succinate disrupts myogenesis and impairs skeletal muscle regeneration

2019 ◽  
Author(s):  
Paige C Arneson ◽  
Kelly A Hogan ◽  
Alexandra M Shin ◽  
Adrienne Samani ◽  
Aminah Jatoi ◽  
...  
Keyword(s):  
Linear Regression ◽  
Muscle Regeneration ◽  
Metabolic Profiling ◽  
Muscle Wasting ◽  
Post Injury ◽  
Feret Diameter ◽  
Regression Curves ◽  
Non Linear ◽  
The Mean

ABSTRACTBackgroundMuscle wasting is a debilitating co-morbidity affecting most advanced cancer patients. Alongside enhanced muscle catabolism, defects in muscle repair/regeneration contribute to cancer-associated wasting. Among the factors implicated in suppression of muscle regeneration are cytokines that interfere with myogenic signal transduction pathways. Less understood is how other cancer/wasting-associated cues, such as metabolites, contribute to muscle dysfunction. This study investigates how the metabolite succinate affects myogenesis and muscle regeneration.MethodsWe leveraged an established ectopic metabolite treatment (cell permeable dimethyl-succinate) strategy to evaluate the ability of intracellular succinate elevation to 1) affect myoblast homeostasis (proliferation, apoptosis), 2) disrupt protein dynamics and induce wasting-associated atrophy, and 3) modulate in vitro myogenesis. In vivo succinate supplementation experiments (2% succinate, 1% sucrose vehicle) were used to corroborate and extend in vitro observations. Metabolic profiling and functional metabolic studies were then performed to investigate the impact of succinate elevation on mitochondria function.ResultsWe found that in vitro succinate supplementation elevated intracellular succinate about 2-fold, and did not have an impact on proliferation or apoptosis of C2C12 myoblasts. Elevated succinate had minor effects on protein homeostasis (∼25% decrease in protein synthesis assessed by OPP staining), and no significant effect on myotube atrophy. Succinate elevation interfered with in vitro myoblast differentiation, characterized by significant decreases in late markers of myogenesis and fewer nuclei per myosin heavy chain positive structure (assessed by immunofluorescence staining). While mice orally administered succinate did not exhibit changes in overall body composition or whole muscle weights, these mice displayed smaller muscle myofiber diameters (∼6% decrease in the mean of non-linear regression curves fit to the histograms of minimum feret diameter distribution), which was exacerbated when muscle regeneration was induced with barium chloride injury. Significant decreases in the mean of non-linear regression curves fit to the histograms of minimum feret diameter distributions were observed 7 days and 28 days post injury. Elevated numbers of myogenin positive cells (3-fold increase) supportive of the differentiation defects observed in vitro were observed 28 days post injury. Metabolic profiling and functional metabolic assessment of myoblasts revealed that succinate elevation caused both widespread metabolic changes and significantly lowered maximal cellular respiration (∼35% decrease).ConclusionsThis study broadens the repertoire of wasting-associated factors that can directly modulate muscle progenitor cell function and strengthens the hypothesis that metabolic derangements are significant contributors to impaired muscle regeneration, an important aspect of cancer-associated muscle wasting.

scholarly journals Rumen protein degradation rates estimated by non-linear regression analysis of Michaelis–Menten in vitro data

1992 ◽  
Vol 67 (1) ◽  
pp. 27-42 ◽  
Author(s):  
Glen A. Broderick ◽  
Murray K. Clayton
Keyword(s):  
Linear Regression ◽  
Protein Degradation ◽  
Degradation Rate ◽  
Soya Bean ◽  
Protein Sources ◽  
Degradation Rates ◽  
Non Linear ◽  
Bean Meal ◽  
Soya Bean Meal

An in vitro method applying Michaelis–Menten saturation kinetics was developed as an alternative approach for estimating protein degradation rates in the rumen. Non-linear regression (NLR) analysis of the integrated Michaelis–Menten equation yielded fractional degradation rates,kd, from direct estimates of the maximum velocity: Michaelis constant ratio (kd=Vmax:Km). Degradation rates obtained using data from a series of 2 h inhibitor in vitro incubations were respectively 0.989, 0.134, and 0.037 /h for casein, solvent soya-bean meal (SSBM) and expeller soya-bean meal (ESBM). Degradation rates obtained from 2 h incubations had lower standard errors than those obtained using 1 h incubations; 2 h rates were not significantly different from 1 h rates, suggesting end-product inhibition was not significant at 2 h. The NLR Michaelis–Menten method was used to determine degradation rates for twelve protein sources: casein, bovine serum albumin, two samples of lucerne (Medicago sativa) hay, and four samples each of SSBM and ESBM. Statistical analysis of NLR results revealed significant differences among the twelve protein sources. Casein was degraded most rapidly (0.827 /h), and the four ESBM samples most slowly (0.050–0.098 /h). Degradation rate for serum albumin was 0.135 /h; rates for SSBM and lucerne hays ranged from 0.160 to 0.208 /h. Degradation rates estimated using the NLR method were more rapid than those obtained with a limited substrate approach; NLR rates were more consistent with in vivo estimates of rumen protein escape. Greater concentrations of slowly degraded proteins were needed with the NLR method to define curvilinearity of the degradation curve more accurately.Protein degradation rate: Rumen protein escape: Michaelis–Menten kinetics: Non-linear regression

More Linear Models in R!

2021 ◽  
pp. 139-180
Author(s):  
Justin C. Touchon
Keyword(s):  
Linear Regression ◽  
Linear Model ◽  
Confidence Intervals ◽  
Linear Models ◽  
Analysis Of Covariance ◽  
Regression Curves ◽  
The World ◽  
Non Linear ◽  
Post Hoc

Chapter 6 continues exploring the world of statistics that are covered within the linear model, namely two-way and three-way ANOVA, linear regression and analysis of covariance (ANCOVA). In each type of model, a detailed description of how to interpret the summary output is undertaken, including understanding how to interpret and plot interactions. Conducting post-hoc analyses and using the predict() function are also covered. The chapter ends by reinforcing earlier plotting skills in ggplot2 by walking through an example of making a professional looking figure with multiple non-linear regression curves and confidence intervals.

Molecular and Clinical Associations Between Vitamin D and Chronic Lymphocytic Leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5282-5282
Author(s):  
Nina Beri ◽  
Daphne R. Friedman ◽  
Tiffany M. Simms ◽  
Maragatha Kuchibhatla ◽  
J. Brice Weinberg ◽  
...  
Keyword(s):  
Gene Expression ◽  
Vitamin D ◽  
Chronic Lymphocytic Leukemia ◽  
Linear Regression ◽  
Vitamin D Insufficiency ◽  
Lymphocytic Leukemia ◽  
Vitamin D Levels ◽  
The Mean ◽  
25 Oh Vitamin D

Abstract Introduction Vitamin D deficiency is common in the general population. Approximately 25-50% of adult patients seen at routine visits in the United States are found to have an insufficient vitamin D level. Vitamin D has been shown to be prognostic in several types of cancers including breast, prostate and colon cancer. Vitamin D activates a nuclear transcription factor that regulates the expression of almost 200 genes which modulate a variety of cellular processes including angiogenesis, differentiation, proliferation, and apoptosis. Recent research has shown that vitamin D levels may have a prognostic effect in patients with chronic lymphocytic leukemia (CLL), where 25-OH vitamin D insufficiency was associated with shortened time to treatment and poorer overall survival. A centrally important unanswered question relates to causation: does vitamin D insufficiency yield more aggressive cancer disease biology, or do intrinsically progressive cases of CLL cause vitamin D insufficiency? We hypothesized that vitamin D insufficiency alters CLL cell biology and favors a more aggressive disease phenotype. Methods Untreated patients within 12 months of initial diagnosis of CLL from Duke University Hospital and the Durham VA were studied. Serum samples from 185 patients were assayed for the 25-OH vitamin D level (immunochemiluminometric assay). A multivariate analysis was performed using: age, race, gender, Rai stage, CD38, Zap70, hierarchical FISH, IGHV, and season of diagnosis to determine whether vitamin D levels are a significant predictor of OS and TTT in this group. Global mRNA expression from 23 patients was analyzed using Affymetrix U133 Plus 2.0 arrays as a function of vitamin D level and gene list generated for those with p values < 10-5. rtPCR was performed on samples from an additional 50 patients to validate the findings from the mRNA expression analysis. Linear regression analysis was conducted to evaluate for significant associations between genes and 25-OH vitamin D levels. An in vitro assessment of 1,25-di-OH vitamin D effects on CLL cell viability in serum free media was evaluated using an MTS assay. Results The mean vitamin D level amongst the group of 185 patients was 25.6± 9.7 ng/mL. Eighty-nine patients had a vitamin D level less than 25 and 96 had a level above 25, which we used as our cutoff, as prior reports have used this level to define insufficiency in CLL. Thirty-one of 95 (33%) of the sufficient vitamin D group were treated versus 39 of 89 (44%) of the insufficient vitamin D group (p=0.12). Among those requiring treatment, the mean TTT was approximately the same between the two groups: 4.7±0.3 yrs for the higher vitamin D group vs. 4.6±0.4 yrs for the insufficient group (p=0.126). OS for the higher vitamin D group was 8.3±0.3 vs. 7.0±0.2 years for the lower vitamin D group (p=0.935). Multivariable analysis showed that IGHV mutation (HR = 0.386; p=0.0159) and Rai stage 0 or 1 (HR = 0.174; p=0.0002) predicted TTT, while age and race influenced OS, with age>62 conferring greater risk of death (p=0.0191) and African Americans having decreased survival (p=0.0110). Preliminary studies of gene expression data identified eight probes that were differentially expressed as a function of vitamin D level. rtPCR was then performed on GPR82, MPZL3, FBXW4, ROR1, and CXCL11 to validate these results. Linear regression confirmed that ROR1 and FBXW4 gene expression correlated with vitamin D level (p=0.0065; r2=0.144 and p=0.0185; r2=0.110, respectively). High levels of ROR1 are observed in B-CLL. FBXW4 has been shown to be mutated or under-expressed in a variety of human cancer cell lines. Early in vitro cytotoxicity of 1,25 di-OH vitamin D in CLL (n = 5 patient derived samples) showed an IC50 = 334 nM. Discussion Our results show that the basal level of vitamin D is not significantly correlated with either OS or TTT in CLL in contrast to previous studies. No interaction between vitamin D levels and race, age, gender, Rai stage, IGHV mutation, season of diagnosis was observed. However, ongoing in vitro experiments show that 1,25 vitamin D is cytotoxic to CLL, raising the intriguing possibility that intermittent bolus dosing could potentially be used therapeutically. Further, we have identified specific genes where quantitative gene expression is correlated with basal vitamin D levels. These findings expand our understanding of the interaction between vitamin D and B cell malignancies. Disclosures: No relevant conflicts of interest to declare.

Evaluating sample stability in the clinical laboratory with the help of linear and non-linear regression analysis

2020 ◽  
Vol 58 (2) ◽  
pp. 188-196 ◽  
Author(s):  
Joachim K.W. Pum
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Study Design ◽  
Clinical Laboratory ◽  
Linear Regression Analysis ◽  
Time Points ◽  
Stability Functions ◽  
Sample Stability ◽  
Non Linear

AbstractAs it is common practice for laboratories to store patient samples for a predefined period, allowing clinicians to request additional tests on previously collected samples, knowledge about sample stability is indispensable for the laboratorian. A common approach to estimating the maximum storage time is to use a discrete study design, measuring the analyte of interest at various time-points and then checking for significant differences with the help of a statistical test, such as Student’s t-test, Wilcoxon’s test or an analysis of variance (ANOVA) test. Because only discrete time intervals are considered, stability data can just be approximated. Alternatively, a continuous study design, as described by the Clinical and Laboratory Standards Institute (CLSI) for performing stability experiments for in vitro diagnostic reagents, can also be adopted by the clinical laboratory to evaluate the stability of biological samples. The major advantage of this approach is that it allows laboratories to define individual stability limits for different medical situations and offers more flexibility when choosing time-points for measurements. The intent of this paper is to demonstrate the evaluation of sample stability in the clinical laboratory with a continuous study design implemented with linear or non-linear regression analysis. Appropriate statistical modeling and acceptance criteria are presented, stability functions are described briefly, and checking the overall validity of the results is discussed.

scholarly journals Adsorption between Quercetin Derivatives and β-Glucan Studied with a Novel Approach to Modeling Adsorption Isotherms

2020 ◽  
Vol 10 (5) ◽  
pp. 1637 ◽  
Author(s):  
Lidija Jakobek ◽  
Petra Matić ◽  
Šima Kraljević ◽  
Šime Ukić ◽  
Mirta Benšić ◽  
...  
Keyword(s):  
Linear Regression ◽  
Adsorption Isotherms ◽  
Spatial Arrangement ◽  
Experimental Results ◽  
Oh Groups ◽  
Quercetin Derivatives ◽  
Novel Approach ◽  
Non Linear ◽  
Modeling Of Adsorption

Interactions between polyphenols and fibers are important for polyphenol bioactivities, and have been studied in vitro with adsorption process and isotherms. However, the theoretical interpretations of adsorption potentially can be affected by the method of isotherm modeling. The aim was to study the interactions between β-glucan and quercetin derivatives (quercetin-3-glucoside, quercetin-3-galactoside, quercetin-3-rhamnoside) by studying adsorption, and to potentially improve the modeling of adsorption isotherms. Quercetin derivatives were determined by using spectrophotometric method. Experimental results were modeled with Langmuir, Dubinin-Radushkevich, and Hill isotherms using non-linear regression, linear regression, and improved non-linear regression. For improved non-linear regression, code in the R programming language was developed. All quercetin derivatives adsorbed onto the surface of β-glucan. Improved non-linear regression gave somewhat lower errors and may be the most appropriate for adsorption interpretation. According to isotherms obtained with improved regression, it may be suggested that adsorption is higher for rhamnoside and glucoside of quercetin than for quercetin-3-galactoside which agrees with experimental results. Adsorption could be a physical process. The spatial arrangement of hydroxyl (OH) groups on the glycoside part of quercetin could affect the adsorption. In conclusion, a novel approach using improved non-linear regression has been shown to be a useful, novel tool for adsorption interpretation.

Influence of Platelet Membrane Sialic Acid and Platelet-Associated IgG on Ageing and Sequestration of Blood Platelets in Baboons

1993 ◽  
Vol 70 (04) ◽  
pp. 676-680 ◽  
Author(s):  
H F Kotzé ◽  
V van Wyk ◽  
P N Badenhorst ◽  
A du P Heyns ◽  
J P Roodt ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Life Span ◽  
Blood Platelets ◽  
Senescent Cell ◽  
Platelet Membrane ◽  
Antigen Complex ◽  
The Mean ◽  
Aggregation Of Platelets

SummaryPlatelets were isolated from blood of baboons and treated with neuraminidase to remove platelet membrane sialic acid, a process which artificially ages the platelets. The platelets were then labelled with 111In and their mean life span, in vivo distribution and sites of Sequestration were measured. The effect of removal of sialic acid on the attachment of immunoglobulin to platelets were investigated and related to the Sequestration of the platelets by the spleen, liver, and bone marrow. Removal of sialic acid by neuraminidase did not affect the aggregation of platelets by agonists in vitro, nor their sites of Sequestration. The removal of 0.51 (median, range 0.01 to 2.10) nmol sialic acid/108 platelets shortened their life span by 75 h (median, range 0 to 132) h (n = 19, p <0.001), and there was an exponential correlation between the shortening of the mean platelet life span and the amount of sialic acid removed. The increase in platelet-associated IgG was 0.112 (median, range 0.007 to 0.309) fg/platelet (n = 25, p <0.001) after 0.79 (median, range 0.00 to 6.70) nmol sialic acid/108 platelets was removed (p <0.001). There was an exponential correlation between the shortening of mean platelet life span after the removal of sialic acid and the increase in platelet-associated IgG. The results suggest that platelet membrane sialic acid influences ageing of circulating platelets, and that the loss of sialic acid may have exposed a senescent cell antigen that binds IgG on the platelet membrane. The antibody-antigen complex may then provide a signal to the macrophages that the platelet is old, and can be phagocytosed and destroyed.

Prediction of Surface Roughness and Optimization of Cutting Parameters in CNC Turning of Rotational Features

2020 ◽  
Vol 38 (8A) ◽  
pp. 1143-1153
Author(s):  
Yousif K. Shounia ◽  
Tahseen F. Abbas ◽  
Raed R. Shwaish
Keyword(s):  
Surface Roughness ◽  
Linear Regression ◽  
Regression Model ◽  
Linear Regression Model ◽  
Feed Rate ◽  
Cutting Parameters ◽  
Spindle Speed ◽  
Depth Of Cut ◽  
Non Linear ◽  
Optimization Of Cutting Parameters

This research presents a model for prediction surface roughness in terms of process parameters in turning aluminum alloy 1200. The geometry to be machined has four rotational features: straight, taper, convex and concave, while a design of experiments was created through the Taguchi L25 orthogonal array experiments in minitab17 three factors with five Levels depth of cut (0.04, 0.06, 0.08, 0.10 and 0.12) mm, spindle speed (1200, 1400, 1600, 1800 and 2000) r.p.m and feed rate (60, 70, 80, 90 and 100) mm/min. A multiple non-linear regression model has been used which is a set of statistical extrapolation processes to estimate the relationships input variables and output which the surface roughness which prediction outside the range of the data. According to the non-linear regression model, the optimum surface roughness can be obtained at 1800 rpm of spindle speed, feed-rate of 80 mm/min and depth of cut 0.04 mm then the best surface roughness comes out to be 0.04 μm at tapper feature at depth of cut 0.01 mm and same spindle speed and feed rate pervious which gives the error of 3.23% at evolution equation.

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