[Determination of isobutyl methacrylate in workplace air by gas chromatography].

Objective: To establish a gas chromatography method for detecting isobutyl methacrylate in workplace air. Methods: From July to October 2019, isobutyl methacrylate in workplace air was collected by activated charcoal tube, absorbed using carbon disulfide and analyzed by gas chromatography (FID) with FFAP capillary column. Results: The linear range of isobutyl methacrylate in the method was 0-800 µg/ml, the correlation coefficient was 0.99993. The detection limit was 0.35 µg/ml. The lowest detected concentration was 0.12 mg/m(3). The within-run precision was 2.06%-2.72%, the between-run precision was 3.03%-3.83%. The rates of desorption was 96.7%. The breakthrough volume was 14.46 mg. The average sampling efficience was 100%. The samples could be stored at room temperature for 7 days. Conclusion: The method is simple, highly sensitive and precise. Isobutyl methacrylate in workplace air could be determined accurately.

[Detecting the concentrations of diphenylamine in air of workplace with HPLC].

Objective: To establish the method of detecting the concentrations of diphenylamine in air of workplace with high performance liquid chromatographic (HPLC) . Methods: According to standards of methods for determining the chemical substances in workplace air, diphenylamine in the air was collected by glass fiber filter treated with sulfuric acid, then dissolved by methanol and determined by high performance liquid chromatography with UV-detector. Results: There was a linear relationship within the range of 0-30.0 µg/ml, and regression equation was y=8425.6x-150.7, correlation coefficient was 0.999 9, the detection limit was 0.045 µg/ml. The lowest detected concentration was 0.030 mg/m(3) (sampling volume 15 L) . The within-run precision was 2.41 ℅-3.02%, the between-run precision was 3.11%-4.45%. The desorption efficiencies was 97.8℅ and the sampling efficiencies were 100%. The samples in glass fiber filter could be stored for 7 d at room temperature. Conclusion: The present method could meet with the requirements of Guide for establishing occupational health standards-Part 4 Determination methods of air chemicals in workplace and be feasible for determination of diphenylamine in workplace air.

Sonographic appearance of cervical lymphadenopathy due to infectious mononucleosis in children and young adults.

AIM: To depict the grey-scale and Doppler features of cervical lymphadenopathy due to infectious mononucleosis (IM) and to compare the findings with other benign conditions and lymphoma. MATERIALS AND METHODS: One hundred and four patients <30 years old with 138 enlarged lymph nodes (LNs) were enrolled for sonographic analysis. These LNs were grouped as: IM LNs (59 LNs in 30 patients), lymphoma (30 LNs in 30 patients), bacterial lymphadenitis (24 LNs in 20 patients), tuberculosis (TB; 14 LNs in 13 patients), and reactive hyperplasia (11 LNs in 11 patients). Sonographic assessments included shape, echotexture, hilum, border, matting, cystic necrosis, calcification, and vascular pattern. For each sonographic feature, Fisher's exact test was performed to determine whether the difference between IM LNs and any another aetiology were statistically significant. RESULTS: IM LNs tended to be round in shape (69%), heterogeneous in echotexture (61%), absent of echogenic hilum (66%), indistinct margins (80%), bilateral distribution (91%), and matting (83%) [even bilateral matting (66%)], and central hilar vascularity (89.8%). On analysis, bilateral matting had the highest specificity to IM LNs; however, its sensitivity was relatively low. In contrast to IM LNs, TB LNs were more likely to have unilateral matting, cystic necrosis, and calcification. Indistinct margins and decreased echogenicity of the hilum were more frequently seen in IM LNs than in bacterial LNs. Furthermore, central hilar vascularity was a common feature of IM LNs and other benignity, which can distinguish these from lymphoma and TB LNs. CONCLUSION: Although an individual sonographic feature had considerable overlaps between IM LNs and other aetiologies, the combination of several features may be helpful in the diagnosis of IM.

Akt-induced endocrine therapy resistance is reversed by inhibition of mTOR signaling.

BACKGROUND: Resistance to endocrine therapy is a major impediment in breast cancer therapeutics. The Phosphatidylinositol-3-OH kinase (PI3K)/Protein kinase B (Akt/PKB) kinase signaling pathway has been implicated in altering breast cancer response to multiple therapies. How Akt modulates response is an area of significant clinical relevance. METHODS: We have used an in vitro model to discern the effects of robust Akt activity on breast cancer cellular response to endocrine therapies. RESULTS: High levels of Akt activity confer resistance to the aromatase inhibitor Letrozole (Let) and the selective estrogen receptor (ER) down-regulator Fulvestrant (ICI). Akt-induced resistance is not due to failure of these endocrine agents to inhibit estrogen receptor alpha activity. Instead, resistance is characterized by altered cell cycle and apoptotic response. Cotreatment with low concentrations of the mTOR inhibitor RAD-001 and either Let or ICI restores response of the resistant cells to levels observed in the responsive cells treated with either Let or ICI as a single agent. CONCLUSIONS: Our preliminary findings in experiments with RAD-001 indicate that cotreatment with mTOR inhibitors and either Let or ICI reverses the Akt-mediated resistance and restores responsiveness to antiestrogens. Concurrent ER and mTOR inhibition is therefore an effective strategy to overcome growth factor-induced resistance and bears significant implications for optimal clinical development of these agents in breast cancer treatment.