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The rhythmic nature of insulin secretion over the 24h cycle in pancreatic islets has been mostly investigated using transcriptomics studies showing that modulation of insulin secretion over this cycle is achieved via distal stages of insulin secretion. We set out to measure β-cell exocytosis using in depth cell physiology techniques at several time points. In agreement with the activity and feeding pattern of nocturnal rodents, we find that C57/Bl6J islets in culture for 24h exhibit higher insulin secretion during the corresponding dark phase than in the light phase (Zeitgeber Time ZT20 and ZT8, respectively, in vivo). Glucose-induced insulin secretion is increased by 21% despite normal intracellular Ca2+ transients and depolarization-evoked exocytosis, as measured by whole-cell capacitance measurements. This paradox is explained by a 1.37-fold increase in beta cell insulin content. Ultramorphological analyses show that vesicle size and density are unaltered, demonstrating that intravesicular insulin content per granule is modulated over the 24h cycle. Proinsulin levels did not change between ZT8 and ZT20. Islet glucagon content was inversely proportional to insulin content indicating that this unique feature is likely to support a physiological role. Microarray data identified the differential expression of 301 transcripts, of which 26 are miRNAs and 54 are known genes (including C2cd4b, a gene previously involved in insulin processing, and clock genes such as Bmal1 and Rev-erbα). Mouse β-cell secretion over the full course of the 24h cycle may rely on several distinct cellular functions but late night increase in insulin secretion depends solely on granule insulin content. [ABSTRACT FROM AUTHOR]

Rationale: Tumor necrosis factor-alpha (TNF-α) is a potent pro-inflammatory mediator and its expression is up-regulated in chronic obstructive pulmonary disease (COPD). Tristetraprolin (TTP) is implicated in regulation of TNF-α expression; however, whether TTP is involved in cigarette smoke-induced TNF-α expression has not been determined. Methods: TTP expression was examined by western blot analysis in murine alveolar macrophages and alveolar epithelial cells challenged without or with cigarette smoke extract (CSE). TNF-α mRNA stability, and the decay of TNF-α mRNA, were determined by real-time quantitative RT-PCR. TNF-α protein levels were examined at the same time in these cells. To identify the molecular mechanism involved, a construct expressing the human beta-globin reporter mRNA containing the TNF-α 3’-untranslated region was generated to characterize the TTP targeted site within TNF-α mRNA. Results: CSE induced TTP down-regulation in alveolar macrophages and alveolar epithelial cells. Reduced TTP expression resulted in significantly increased TNF-α mRNA stability. Importantly, increased TNF-α mRNA stability due to impaired TTP function resulted in significantly increased TNF-α levels in these cells. Forced TTP expression abrogated the increased TNF-α mRNA stability and expression induced by CSE. By using the globin reporter construct containing TNF-α mRNA 3’-untranslated region, the data indicate that TTP directly targets the adenine- and uridine-rich region (ARE) of TNF-α mRNA and negatively regulates TNF-α expression at the post-transcriptional level. Conclusion: The data demonstrate that cigarette smoke exposure reduces TTP expression and impairs TTP function, resulting in significantly increased TNF-α mRNA stability and excessive TNF-α expression in alveolar macrophages and epithelial cells. The data suggest that TTP is a novel post-transcriptional regulator and limits excessive TNF-α expression and inflammatory response induced by cigarette smoke. [ABSTRACT FROM AUTHOR]

Background: Laryngeal squamous cell carcinoma (LSCC) is a head and neck cancer type. In this study, we introduced a novel inflammation- and nutrition-based prognostic system, referred to as COR-BMI (Combination of red blood cell distribution width and body mass index), for LSCC patients. Methods: A total of 807 LSCC patients (784 male and 23 female, 22–87 y of age) who underwent surgery were enrolled in this retrospective cohort study. The patients were stratified by COR-BMI into three groups: COR-BMI (0) (RDW ≤ 13.1 and BMI ≥ 25); COR-BMI (1) (RDW ≤ 13.1 and BMI < 18.5 or 18.5 ≤ BMI < 25; RDW > 13.1 and 18.5 ≤ BMI < 25 or BMI ≥ 25); or COR-BMI (2) (RDW > 13.1 and BMI < 18.5). Cox regression models were used to investigate the association between COR-BMI and cancer-specific survival (CSS) rate among LSCC patients. Results: The 5-y, 10-y, and 15-y CSS rates were 71.6%, 60.1%, and 55.4%, respectively. There were significant differences among the COR-BMI groups in age (< 60 versus ≥ 60 y; P = 0.005) and T stage (T1, T2, T3, or T4; P = 0.013). Based on the results, COR-BMI (1 versus 0: HR = 1.76; 95% CI = 0.98–3.15; 2 versus 0: HR = 2.91; 95% CI = 1.53–5.54, P = 0.001) was a significant independent predictor of CSS. Conclusion: COR-BMI is a novel inflammation- and nutrition-based prognostic system, which could predict long-term survival in LSCC patients who underwent surgery. [ABSTRACT FROM AUTHOR]

Recent research found that Tiron was an effective antioxidant that could act as the intracellular reactive oxygen species (ROS) scavenger or alleviate the acute toxic metal overload in vivo. In this study, we investigated the inhibitory effect of Tiron on matrix metalloproteinase (MMP)-1 and MMP-3 expression in human dermal fibroblast cells. Western blot and ELISA analysis revealed that Tiron inhibited ultraviolet B (UVB)-induced protein expression of MMP-1 and MMP-3. Real-time quantitative PCR confirmed that Tiron could inhibit UVB-induced mRNA expression of MMP-1 and MMP-3. Furthermore, Tiron significantly blocked UVB-induced activation of the MAPK signaling pathway and activator protein (AP)-1 in the downstream of this transduction pathway in fibroblasts. Through the AP-1 binding site mutation, it was found that Tiron could inhibit AP-1-induced upregulation of MMP-1 and MMP-3 expression through blocking AP-1 binding to the AP-1 binding sites in the MMP-1 and MMP-3 promoter region. In conclusion, Tiron may be a novel antioxidant for preventing and treating skin photoaging UV-induced. [ABSTRACT FROM AUTHOR]