Stoichiometric models for prediction of enteric methane production

This study aimed to empirically evaluate the adjustment quality of two stoichiometric models of methane production from diets that used different rumen fermentation modulators. We used the models proposed by Moss et al. (2000) and Blümmel et al. (1997). The data set consisted of 169 observations of in vitro methane production and volatile fatty acids (acetate, propionate, and butyrate) from dissertations, theses, and scientific articles. The model's adequacy evaluation was only possible through combination of several statistical analyzes. The models were unable to predict the enteric methane precisely and accurately. Despite this, the model proposed by Moss et al. (2000) showed a better fit based on the mean bias (% of observed, MB), MEF, RMSEP, Cb and CCC measures compared to the model proposed by Blümmel et al. (1997). However, both models presented strong evidence against the general hypothesis H0: a = 0 & b = 1. Thus, the model proposed by MOSS et al. (2000) was more efficient, whereas the model by Blümmel et al. (1997) showed a better fit for diets with high availability of H2.

Avaliação do modelo NRC para predição do consumo de matéria seca por vacas leiteiras manejadas em pastos tropicais / NCR Model Evaluation for prediction of dry matter intake by dairy cows managed in tropical pastures

Objetivou-se avaliar o poder preditivo do modelo do National Research Council (NRC) para gado leiteiro em estimar o consumo de matéria seca (CMS) por vacas mestiças, em pastagens tropicais. Foi efetuada uma análise conjunta de cinco estudos, contemplando três forrageiras. Foram avaliadas 132 estimativas individuais do CMS observado (CMSObs), obtidas por meio do indicador externo Cr2O3. O CMS também foi predito por meio do software do NRC (CMSPred), que, por sua vez, foi abastecido com inputs referentes aos animais e ao ambiente de criação. Os valores de CMSPred (12,7±1,6kg/d) foram semelhantes aos de CMSObs (12,3±3,3kg/d). Foram obtidas as seguintes estimativas da avaliação do poder preditivo do modelo: viés médio (-0,419kg/d), coeficiente de determinação (0,029), coeficiente de correlação (0,17; P=,051), quadrado médio do erro de predição (11,844±20,034), fator de eficiência do modelo (-0,081), coeficiente de determinação do modelo (4,1032) e fator de correção do viés (0,767). A comparação entre CMSObs e CMSPred permitiu identificar a tendência de superestimação das predições se considerado o ajuste por meio de regressão robusta para o modelo linear simples sem intercepto. Nas condições avaliadas, o modelo produz predições de CMS com satisfatória exatidão, porém com baixa precisão.(AU)

The aim of the present study was to evaluate the predictive power of estimating the dry matter intake (DMI) of crossbred cows on tropical pastures by the National Research Council (NRC) equation for dairy cattle. A joint analysis of five studies covering three forages was performed in which 132 individual estimates of observed DMI obtained through Cr2O3 as a marker. DMI was also predicted from the NRC (DMIPred) software with inputs concerning animals and breeding environment of the studies used. Predicted DMIPred average values (12.7±1.6kg/d) were similar to the observed DMIObs ones (12.3±3.3kg/d). We obtained the following estimates of the evaluation of the predictive power of the model: average bias (- 0.419kg/d), coefficient of determination (0.029), Person's correlation coefficient (0.17, P= 0.051), mean square error of prediction (11,844±20,034), model efficiency factor (- 0.081), coefficient of determination (4.1032), and bias correction factor (0.767). The comparison between DMIObs and DMIPred values allowed the identification of the overestimating tendency of the predictions demonstrated by the robust regression fit of the simple linear no intercept model. Nevertheless, the model yields predictions with satisfactory accuracy, but with low precision.(AU)

Relationship between alcohol consumption and new-onset cholelithiasis: a multicentre retrospective study(A report of 77 755 cases) / 中华消化外科杂志

Objective To explore the relationship between alcohol consumption and new-onset cholelithiasis.Methods The retrospective cohort study was conducted.The data of 77 755 participants who participated health examination at the Kailuan General Hospital,Kailuan Linxi Hospital,Kailuan Zhaogezhuang Hospital,Kailuan Tangjiazhuang Hospital,Kailuan Fan'gezhuang Hospital,Kailuan Lyujiatuo Hospital,Kailuan Jinggezhuang Hospital,Kailuan Linnancang Hospital,Kailuan Qianjiaying Hospital,Kailuan Majiagou Hospital and Kailuan Branch Hospital from June 2006 to December 2015 were collected.According to definition of alcohol consumption from literature,all the 77 755 participants were allocated into the 5 groups,including 50 695 with never drinking in the never group,3 154 with alcohol withdrawal time≥ 1 year in the past group,12 410 with light drinking in the light group,1 606 with moderate drinking in the moderate group and 9 890 with heavy drinking in the heavy group.All participants received the same-order health examinations by the fixed team of doctors in 2006,2008,2010,2012 and 2014 at the same place.Epidemiological investigation,anthropometric parameters and biochemical indicators were collected.Observation indicators:(1) comparisons of clinical characteristics among the 5 groups;(2) incidence of cholelithiasis;(3) risk factors analysis affecting new-onset cholelithiasis;(4) comparisons of the fitting degree of alcohol consumption on new-onset cholelithiasis model.Measurement data with normal distribution were represented as (x)±s,and comparisons among groups were analyzed using the one-way ANOVA.The pairwise comparison and homogeneity of variance were done using the least significance difference (LSD) test.Heterogeneity of variance was analyzed by the Dunnett's T3 test.Measurement data with skewed distribution were described as M (Q),and comparisons among groups were analyzed using the rank sum test.Comparisons of count data were analyzed using chi-square test.The cumulative incidence of new-onset cholelithiasis was calculated by the Kaplan-Meier method,and comparisons of incidences among groups were done by the Log-rank test.The hazard ratio (HR) and 95％ confidence interval (CI) of different intakes of alcohol on new-onset cholelithiasis were estimated by the COX proportional hazards regression models.The fitting degree of alcohol consumption on new-onset cholelithiasis model was calculated by the likelihood ratio test and akaike information criterion (AIC).Results (1) Comparisons of clinical characteristics among the 5 groups:male,age,systolic pressure,diastolic pressure,body mass index (BMI),total cholesterol (TC),triglyceride (TG),fasting plasma glucose (FPG) and waistline and cases with diabetes,hypertension,smoking and physical exercise were respectively 33 406,(51±12)years,(130±21) mmHg (1mmHg=0.133 kPa),(83± 12)mmHg,(25±4)kg/m2,(4.93±1.13)mmol/L,1.26 mmol/L (0.90-1.88 mmol/L),(5.5±1.7)mmol/L,(86±10) cm,4 538,21 773,5 873,6 140 in the never group and 3 077,(56±12) years,(134±22)mmHg,(85±12)mmHg,(25± 3) kg/m2,(4.93 ± 1.21) mmol/L,1.29 mmol/L (0.91-1.90 mmol/L),(5.6 ± 1.8) mmol/L,(89 ±9)cm,420,1 652,856,856 in the past group and 11 859,(46±12)years,(127±19)mmHg,(82±11)mmHg,(25±3)kg/m2,(4.89± 1.15) mmol/L,1.30 mmol/L (0.89-2.01 mmol/L),(5.4± 1.4) mmol/L,(87±9)cm,891,4294,2 186,2 186 in the light group and 1 585,(58±11)years,(134±22)mmHg,(84±11)mmHg,(25±3)kg/m2,(5.06±1.21)mmoL/L,1.23 mmoL/L (0.85-1.82 mmol/L),(5.5±1.7) mmol/L,(88±9)cm,159,762,591,591 in the moderate group and 9 868,(52±9) years,(135±21)mmHg,(86±12)mmHg,(25±3)kg/m2,(5.18±1.21)mmoL/L,1.36 mmol/L (0.92-2.19 mmol/L),(5.5±1.5)mmoL/L,(88±9) cm,819,4 900,2 183,2 183 in the heavy group,showing statistically significant differences among groups [x2 =9 989.71,F=869.28,F=254.13,195.97,27.52,112.63,H(x2) =154.09,F=11.92,63.37,x2 =128.17,656.31,23 561.80,656.31,P＜0.05].(2) Incidence of cholelithiasis:all 77 755 participants were observed for (6.8±2.1)years,3 757 were diagnosed as new-onset cholelithiasis,with a cumulative incidence of new-onset cholelithiasis of 4.5％.The cumulative incidences of new-onset cholelithiasis in the never,past,light,moderate and heavy groups were respectively 5.1％,4.9％,3.7％,3.4％ and 3.3％,showing a statistically significant difference among groups (x2=83.14,P＜0.05).The cumulative incidence of new-onset cholelithiasis in the never group was significantly different from that in the past,light,moderate and heavy groups (x2 =18.34,40.58,45.41,48.44,P＜0.05).The cumulative incidence of new-onset cholelithiasis in the past group was significantly different from that in the light,moderate and heavy groups (x2 =18.72,20.47,25.41,P＜0.05).There were statistically significant differences in the cumulative incidence of new-onset cholelithiasis among the light,moderate and heavy groups (x2=8.47,12.41,P＜0.05) and no statistically significant difference between the moderate and heavy groups (x2=0.85,P＞0.05).(3) Risk factors analysis affecting new-onset cholelithiasis:results of COX proportional hazards regression models showed that risks of new-onset cholelithiasis in the light,moderate and heavy groups were reduced compared with never group after adjustment of gender,age,TC,TG,BMI,hypertension,diabetes,smoking and physical exercise (HR=0.88,0.82,0.73,95％CI:0.79-0.98,0.76-0.89,0.64-0.83,P＜0.05).(4) Comparisons of the fitting degree of alcohol consumption on newonset cholelithiasis model:multivariate model was constructed after adding risk factors of gender,age,BMI,TG,TC,hypertension,diabetes mellitus,smoking and physical exercise,and-2Log L and AIC were 76 331.83 and 76 353.83 for the multivariate model.Then drinking variable was added into multivariate model,and the-2Log L and AIC of the multivariate model+drinking model were 76 307.86 and 76 337.86,respectively,with statistically significant differences (x2=23.97,P＜0.05).Conclusion Alcohol consumption is an independent protective factor for new-onset cholelithiasis,and the risk of cholelithiasis is decreased with increasing alcohol intake.

Prediction of cold and heat patterns using anthropometric measures based on machine learning / 中国结合医学杂志

<p><b>OBJECTIVE</b>To examine the association of body shape with cold and heat patterns, to determine which anthropometric measure is the best indicator for discriminating between the two patterns, and to investigate whether using a combination of measures can improve the predictive power to diagnose these patterns.</p><p><b>METHODS</b>Based on a total of 4,859 subjects (3,000 women and 1,859 men), statistical analyses using binary logistic regression were performed to assess the significance of the difference and the predictive power of each anthropometric measure, and binary logistic regression and Naive Bayes with the variable selection technique were used to assess the improvement in the predictive power of the patterns using the combined measures.</p><p><b>RESULTS</b>In women, the strongest indicators for determining the cold and heat patterns among anthropometric measures were body mass index (BMI) and rib circumference; in men, the best indicator was BMI. In experiments using a combination of measures, the values of the area under the receiver operating characteristic curve in women were 0.776 by Naive Bayes and 0.772 by logistic regression, and the values in men were 0.788 by Naive Bayes and 0.779 by logistic regression.</p><p><b>CONCLUSIONS</b>Individuals with a higher BMI have a tendency toward a heat pattern in both women and men. The use of a combination of anthropometric measures can slightly improve the diagnostic accuracy. Our findings can provide fundamental information for the diagnosis of cold and heat patterns based on body shape for personalized medicine.</p>