FFA treatments increase Ca²⁺ influx to induce ERS in β-TC3 cells.

<p>(A) β-TC3 cells were incubated with FFA or BSA for 16 h, western blot was used to examine the protein expression levels of Grp78 and CHOP following the treatment with Ca²⁺ channel blocker NiCl₂. (B) β-TC3 cells were incubated with FFA or BSA for 16 h, and then stimulated with 4 µM thapsigargin for 20 min to activate store-operated Ca²⁺ entry. Fluorescence densities of Ca²⁺ change were monitored in Fluo-8/AM-loaded β-TC3 cells after FFA or BSA treatments. (C) The protein expression levels of STIM1 and Orai1 were tested by western blot following treatments with FFA or BSA for 16 h in β-TC3 cells. (D) β-TC3 cells were incubated with FFA or BSA for 16 h, and then stimulated with 4 µM thapsigargin for 20 min. Cell lysates were immunoprecipitated with anti-STIM1 antibody followed by western blot using anti-Orai1 antibody and with anti-Orai1 antibody followed by western blot using anti-STIM1 antibody. Immunoprecipitated with anti-IgG antibody was used as the negative control. Bars represent each sample performed in triplicate, and the error bars represent the standard deviations. *<i>P</i><0.05, by the Student’s <i>t</i>-test.</p

Calpain-2 is required for FFA treatment-induced β-TC3 cell apoptosis.

<p>The cells were treated with calpain-2 siRNA, incubated for 24 h, and then stimulated with FFA or BSA for 16 h. (A) Cell death was quantified by annexin V/PI double staining. (B) Caspase-12 activity was detected after cells were treated with calpain-2 siRNA. (C) Caspase-3 activity was detected after cells were treated with calpain-2 siRNA. snc-RNA-treated cells were used as a negative control. Bars represent each sample performed in triplicate, and the error bars represent the standard deviations. *<i>P</i><0.05, by one-way ANOVA.</p

FFA treatments increase calpain-2 activity, thus inducing ERS in β-TC3 cells.

<p>(A) The activity of calpain-2 was tested in β-TC3 cells treated with 0.5 mM FFA or BSA for 16 h. (B) β-TC3 cells were treated with calpain-2 siRNA for 24 h. Western blot was performed to examine calpain-2 protein levels. (C) RT-PCR was used to analyze calpain-2 mRNA levels. (D) Calpain Activity Assay Kit was used to analyze calpain-2 activity. Silencer negative control siRNA (snc-RNA)-treated cells were used as a negative control. (E) β-TC3 cells were treated with calpain-2 siRNA for 24 h and then stimulated with FFA for 16 h, and western blot was used to examine the protein expression levels of Grp78 and CHOP. (F) RT-PCR was used to test Grp78 and CHOP mRNA levels. BSA-treated β-TC3 cells were used as a negative control. Bars represent each sample performed in triplicate, and the error bars represent the standard deviations. *<i>P</i><0.05, by the Student’s <i>t</i>-test.</p

FFA treatments induce ERS in β-TC3 cells and increase cell apoptosis.

<p>(A) Cells were treated with 0.5 mM FFA or BSA for 0, 8, 16, or 24 h. Western blot was used to examine Grp78 and CHOP protein levels. (B) RT-PCR was used to test Grp78 and CHOP mRNA levels. (C) Cells were treated with 0.5 mM FFA or BSA for 16 h. Western blot was used to examine the expression levels of ATF6, p-PERK, PERK, p-IRE1 and IRE1. (D) Cells were treated with 0.5 mM FFA or BSA for 16 h. Cell death was quantified by annexin V/PI double staining. (E) Caspase-12 activity was detected after cells were treated with 0.5 mM FFA or BSA for 16 h. (F) Caspase-3 activity was detected after cells were treated with 0.5 mM FFA or BSA for 16 h. BSA-treated cells were used as a negative control. Bars represent each sample performed in triplicate, and the error bars represent the standard deviations. *<i>P</i><0.05, by the Student’s <i>t</i>-test.</p

Additional file 4: Figure S3. of The association between obstructive sleep apnea and metabolic syndrome: a systematic review and meta-analysis

Galbraith plot. (TIFF 44 kb

Additional file 3: Figure S2. of The association between obstructive sleep apnea and metabolic syndrome: a systematic review and meta-analysis

Funnel plots among all studies including two conference reports that were not subsequently published. Two conference reports referred by Velazquez, 2011 and Papatsimpas, 2011. (TIFF 45 kb

Additional file 2: Figure S1. of The association between obstructive sleep apnea and metabolic syndrome: a systematic review and meta-analysis

Meta-analysis for all studies including two conference reports that were not subsequently published. Two conference reports referred by Velazquez, 2011 and Papatsimpas, 2011. OR: odds ratio; CI: confidence interval. (TIFF 156 kb

Prevalence of metabolic syndrome components combination in male and female participants with abdominal obesity.

<p>Abbreviations: BG: raised fasting plasma glucose, BP: raised blood pressure, TG: raised triglycerides, HDL: reduced high-density lipoprotein cholesterol.</p

Flow chart of study participants.

<p>Abbreviations: MS: metabolic syndrome; AO: abdominal obesity.</p

Kaplan-Meier curve of effect of gender for participants in sample 2with ages below 50 years (A) and above 50 years (B) divided by gender.

<div><p>Abbreviations: MS: metabolic syndrome. </p> <p>Male as reference. The relative ratio (RR) and 95% confidence intervals (CI) were calculated by cox regression after adjustment for ethnics, educational level, cigarette smoking, alcohol drinking, and physical activity.</p></div