A meta-analysis approach with filtering for identifying gene-level gene–environment interactions

Abstract

There is a growing recognition that gene–environment interaction (G × E) plays a pivotal role in the development and progression of complex diseases. Despite a wealth of genetic data on various complex diseases/traits generated from association and sequencing studies, detecting G × E via genome-wide analysis remains challenging due to power issues. In genome-wide G × E studies, a common strategy to improve power is to first conduct a filtering test and retain only the genetic variants that pass the filtering step for subsequent G × E analyses. Two-stage, multistage, and unified tests have been proposed to jointly consider the filtering statistics in G × E tests. However, such G × E tests based on data from a single study may still be underpowered. Meanwhile, large-scale consortia have been formed to borrow strength across studies and populations. In this work, motivated by existing single-study G × E tests with filtering and the needs for meta-analysis G × E approaches based on consortia data, we propose a meta-analysis framework for detecting gene-based G × E effects, and introduce meta-analysis-based filtering statistics in the gene-level G × E tests. Simulations demonstrate the advantages of the proposed method—the ofGEM test. We apply the proposed tests to existing data from two breast cancer consortia to identify the genes harboring genetic variants with age-dependent penetrance (i.e., gene–age interaction effects). We develop an R software package ofGEM for the proposed meta-analysis tests.

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Non-enhanced MRI in combination with color Doppler flow imaging for improving diagnostic accuracy of parotid gland lesions

Abstract

Purpose

To determine the value of non-enhanced MRI in combination with color Doppler flow imaging (CDFI) for differentiating malignant parotid tumors from benign ones.

Methods

This retrospective study analyzed 51 parotid gland lesions (39 benign and 12 malignant) in 51 patients who underwent preoperative CDFI as well as non-enhanced MRI including T₁-weighted, T₂-weighted, and diffusion-weighted imaging (DWI). Degrees of intratumor vascularity were categorized into four grades basing on CDFI findings. The relationships between the lesion and its adjacent external carotid artery and retromandibular vein were inspected on T₁-weighted and T₂-weighted images. Apparent diffusion coefficient (ADC) values were calculated from diffusion-weighted images, and were used to classify the parotid gland lesions with and without reference to the CDFI findings. The classification results were compared using the McNemar test. Sensitivity, specificity, and accuracy percentages were calculated when the non-enhanced MRI/CDFI findings were used to differentiate benign lesions from malignant ones.

Results

The diagnostic accuracy (96.1 vs 82.4%) was significantly improved when ADCs were used together with CDFI findings for classifying parotid gland lesions compared to when ADCs were used alone. Pleomorphic adenomas had the highest ADCs. The ADC thresholds were 1.425 × 10⁻³ mm²/s for differentiating pleomorphic adenomas from carcinomas, 0.999 × 10⁻³ mm²/s for differentiating pleomorphic adenomas from other benign lesions, and 0.590 × 10⁻³ mm²/s for differentiating benign lesions other than pleomorphic adenomas from lymphomas.

Conclusion

Combining CDFI with non-enhanced MRI can improve the diagnostic accuracy of MRI for classifying parotid gland lesions.

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PLCγ2 promotes apoptosis while inhibits proliferation in rat hepatocytes through PKCD/JNK MAPK and PKCD/p38 MAPK signalling

Abstract

Objectives

The PLCG2 (PLCγ2) gene is a member of PLC gene family encoding transmembrane signalling enzymes involved in various biological processes including cell proliferation and apoptosis. Our earlier study indicated that PLCγ2 may be involved in the termination of regeneration of the liver which is mainly composed of hepatocytes, but its exact biological function and molecular mechanism in liver regeneration termination remains unclear. This study aims to examine the role of PLCγ2 in the growth of hepatocytes.

Materials and methods

A recombinant adenovirus expressing PLCγ2 was used to infect primary rat hepatocytes. PLCγ2 mRNA and protein levels were detected by qRT-PCR and Western blot. The subcellular location of PLCγ2 protein was tested by an immunofluorescence assay. The proliferation of hepatocytes was measured by MTT assay. The cell cycle and apoptosis were analysed by flow cytometry. Caspase-3, -8 and -9 activities were measured by a spectrophotometry method. Phosphorylation levels of PKCD, JNK and p38 in the infected cells were detected by Western blot. The possible mechanism underlying the role of PLCγ2 in hepatocyte growth was also explored by adding a signalling pathway inhibitor.

Results

Hepatocyte proliferation was dramatically reduced, while cell apoptosis was remarkably increased. The results demonstrated that PLCγ2 increased the phosphorylation of PKCD, p38 and JNK in rat hepatocytes. After PKCD activity was inhibited by the inhibitor Go 6983, the levels of both p-p38 and p-JNK MAPKs significantly decreased, and PLCγ2-induced cell proliferation inhibition and cell apoptosis were obviously reversed.

Conclusions

This study showed that PLCγ2 regulates hepatocyte growth through PKCD-dependently activating p38 MAPK and JNK MAPK pathways; this result was experimentally based on the further exploration of the effect of PLCγ2 on hepatocyte growth in vivo.

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Ethosuximide-induced Stevens–Johnson syndrome: Beneficial effect of early intervention with high-dose corticosteroid therapy

Abstract

We report two rare cases of childhood epilepsy patients who developed ethosuximide-induced Stevens–Johnson syndrome (SJS). Unlike typical SJS, the initial eruption of both patients presented well-demarcated, infiltrating firm papules mainly on the cheeks and the extensor aspects of the arms (case 1), and multiple vesicles on the soles and oral aphthosis (case 2), which closely mimicked viral exanthema. We diagnosed both patients with ethosuximide-induced SJS, based on the dosing period and the positive results of drug-induced lymphocyte stimulation test. Systemic corticosteroids are usually selected as a standard therapy for SJS, despite controversial results regarding their effectiveness. In case 1, an i.v. pulse therapy of methylprednisolone (30 mg/kg, 3 days consecutively) was initiated on day 7 from the onset of illness, and an i.v. immunoglobulin (400 mg/kg, 5 days consecutively) was added the following day. In case 2, an i.v. prednisone treatment (1 mg/kg, for 1 week) was initiated on day 4 from the onset. Eventually, the early therapeutic interventions resulted in good outcomes in both patients.

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Case of deep vein thrombosis in a patient with advanced malignant melanoma treated with dabrafenib and trametinib

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Immunocryosurgery as monotherapy for lentigo maligna or combined with surgical excision for lentigo maligna melanoma

Abstract

The incidence of lentigo maligna (LM), in situ (LM) or invasive (lentigo maligna melanoma, LMM), has increased during the last decades. Due to functional or cosmetic outcomes, optimal treatment with surgical excision may not be appropriate in some cases. We tried less invasive therapy, immunocryosurgery, as a single treatment for LM or combined with surgery for LMM, with better aesthetic results. Three patients with LM or LMM not amenable to complete surgical excision were selected. LMM patients underwent limited surgical resection of the invasive area. Subsequently, a combined treatment with topical imiquimod and cryosurgery was performed. The LM patient received immunocryosurgery directly. All of them were free of local and systemic disease at 48, 42 and 41 months after discontinuation of therapy. We consider that immunocryosurgery is an alternative option for LM or even for LMM (after removal of the invasive tissue with narrow margins) in poor surgical candidates, with good therapeutic, functional and cosmetic results.

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Benign cephalic histiocytosis: A case with infiltration of CD1a-positive langerin-negative cells

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