Frequent loss of heterozygosity at 8p22 chromosomal region in diffuse type of gastric cancer

AIM: To study the loss of heterozygosity (LOH) at 8p21-23 locus in diffuse gastric cancer.METHODS: To evaluate the involvement of this region in gastric cancer, we used eight microsatellite markers covering two Mb of mentioned region, to perform a high-resolution analysis of allele loss in 42 cases of late diffuse gastric adenocarcinoma.RESULTS: Six of these STS makers: D8S1149, D8S1645, D8S1643, D8S1508, D8S1591, and D8S1145 showed 36%, 28%, 37%, 41%, 44% and 53% LOH, respectively.CONCLUSION: A critical region of loss, close to the NAT2 locus and relatively far from FEZ1 gene currently postulated as tumor suppressor gene in this region.

Numerical Simulation of Diffusion Type Traffic Flow Model Using Second-Order Lax-Wendroff Scheme Based on Exponential Velocity Density Function

In order to control traffic congestion, many mathematical models have been used for several decades. In this paper, we study diffusion-type traffic flow model based on exponential velocity density relation, which provides a non-linear second-order parabolic partial differential equation. The analytical solution of the diffusion-type traffic flow model is very complicated to approximate the initial density of the Cauchy problem as a function of x from given data and it may cause a huge error. For the complexity of the analytical solution, the numerical solution is performed by implementing an explicit upwind, explicitly centered, and second-order Lax-Wendroff scheme for the numerical solution. From the comparison of relative error among these three schemes, it is observed that Lax-Wendroff scheme gives less error than the explicit upwind and explicit centered difference scheme. The numerical, analytical analysis and comparative result discussion bring out the fact that the Lax-Wendroff scheme with exponential velocity-density relation of diffusion type traffic flow model is suitable for the congested area and shows a better fit in traffic-congested regions.

Relationship between clinicopathological features and mucin phenotypes of advanced gastric adenocarcinoma

AIM: To investigate a relationship between the clinicopathological features and mucin phenotypes in advanced gastric adenocarcinoma (AGA). METHODS: Immunohistochemical staining was performed to determine the mucin phenotypes in 38 patients with differentiated adenocarcinomas (DACs), 9 with signet-ring cell carcinomas (SIGs), and 48 with other diffuse-type adenocarcinomas (non-SIGs) of AGA. The mucin phenotypes were classified into 4 types: gastric (G), gastrointestinal (GI), intestinal, and unclassified. RESULTS: The G-related mucin phenotypes were highly expressed in all the histological subtypes of AGA. The expression of the GI phenotype in SIG patients was lower than that in DAC patients (P = 0.02), and this phenotype was observed in 56% of the non-SIG patients in the intramucosal layer. Among non-SIG cases, the expression of the GI phenotype was significantly higherin patients with extended adenocarcinomas and those with positive rates of lymph node metastasis. There was no difference between the expressions of the G and other GI phenotypes factors. Among DAC and non-SIG patients, there were no differences between the survival rates of the corresponding patient groups. CONCLUSION: The GI phenotype might possess more invasive characteristics than the G phenotype in nonSIG. Neither of the phenotypes indicated a poor prognosis of DAC and non-SIG.

Diagnosis and treatment of primary diffuse-type tenosynovial giant cell tumors of the cervical spine

Diffuse-type tenosynovial giant cell tumor （D-TGCT） belongs to a group of lesions believed to arise from tendon sheaths,bursae,or the synovium of diarthrodial joints.The etiology of D-TGCT is unknown.Because it shares histological characteristics with pigmented villonodular synovitis,however,D-TGCT is also termed extra-articular pigmented villonodular synovitis.D-TGCT,which occurs mainly in middle-aged women （20-50 years of age1）,usually involves large load-bearing joints （e.g.,knee,ankle,and hip）.Clinical case reports of D-TGCT involving the spine are rare.2 We retrospectively analyzed a series of three patients diagnosed with cervical D-TGCT in our department over a 10-year period.

Molecular genetics of gastric adenocarcinoma in clinical practice

The molecular genetics of gastric carcinoma(GC) dictates their biology and clinical behavior. The two morphologically distinct types of gastric carcinoma by Lauren classification, i.e., intestinal and diffuse cell types, have a significant difference in clinical outcome. These two types of GC have different molecular pathogenetic pathways with unique genetic alterations. In addition to environmental and other etiologies, intestinal type GC is associated with Helicobacter pylori(H. pylori) infection and involves a multistep molecular pathway driving the normal epithelium to intestinal metaplasia, dysplasia, and malignant transformation by chromosomal and/or microsatellite instability(MSI), mutation of tumor suppressor genes, and loss of heterozygosity among others. Diffuse type shows no clear causal relationship with H. pylori infection, but is commonly associated with deficiency of cell-cell adhesion due to mutation of the E-cadherin gene(CDH1), and a manifestation of the hereditary gastric cancer syndrome. Thus, detection of CDH1 mutation or loss of expression of E-cadherin may aid in early diagnosis or screening of diffuse type GC. Detection of certain genetic markers, for example, MSI and matrix metalloproteinases, mayprovide prognostic information, particularly for intestinal type. The common genetic alterations may offer therapeutic targets for treatment of GC. Polymorphisms in Thymidylate synthase to metabolize 5-fluorouracil, glutathione S-transferase for degradation of Cisplatin, and amplification/overexpression of human epidermal growth factor receptor 2 targeted by monoclonal antibody Trastuzumab, are a few examples. P13K/Akt/mT OR pathway, c-Met pathways, epidermal growth factor receptor, insulin-like growth factor receptor, vascular endothelial growth factor receptor fibroblast growth factor receptor, and micro RNAs are several potential therapeutic biomarkers for GC under investigation.

Application of frequency division inversion in the prediction of heterogeneous natural gas hydrates reservoirs in the Shenhu Area,South China Sea

Drilling results suggest that the thickness of natural gas hydrates(NGHs)in the Shenhu Area,South China Sea(SCS)are spatially heterogenous,making it difficult to accurately assess the NGHs resources in this area.In the case that free gas exists beneath hydrate deposits,the frequency of the hydrate deposits will be noticeably attenuated,with the attenuation degree mainly affected by pore development and free gas content.Therefore,the frequency can be used as an important attribute to identify hydrate reservoirs.Based on the time-frequency characteristics of deposits,this study predicted the spatial distribution of hydrates in this area using the frequency division inversion method as follows.Firstly,the support vector machine(SVM)method was employed to study the amplitude versus frequency(AVF)response based on seismic and well logging data.Afterward,the AVF response was introduced as independent information to establish the nonlinear relationship between logging data and seismic waveform.Then,the full frequency band information of the seismic data was fully utilized to obtain the results of frequency division inversion.The inversion results can effectively broaden the frequency band,reflect the NGHs distribution,and reveal the NGHs reservoirs of two types,namely the fluid migration pathway type and the in situ self-generation self-storage diffusion type.Moreover,the inversion results well coincide with the drilling results.Therefore,it is feasible to use the frequency division inversion to predict the spatial distribution of heterogeneous NGHs reservoirs,which facilitates the optimization of favorable drilling targets and is crucial to the resource potential assessment of NGHs.

Rate decline analysis of multiple fractured horizontal well in shale reservoir with triple continuum

Multiple fractured horizontal well(MFHW) is widely applied in the development of shale gas. To investigate the gas flow characteristics in shale, based on a new dual mechanism triple continuum model, an analytical solution for MFHW surrounded by stimulated reservoir volume(SRV) was presented. Pressure and pressure derivative curves were used to identify the characteristics of flow regimes in shale. Blasingame type curves were established to evaluate the effects of sensitive parameters on rate decline curves, which indicates that the whole flow regimes could be divided into transient flow, feeding flow, and pseudo steady state flow. In feeding flow regime, the production of gas well is gradually fed by adsorbed gases in sub matrix, and free gases in matrix. The proportion of different gas sources to well production is determined by such parameters as storability ratios of triple continuum, transmissibility coefficients controlled by dual flow mechanism and fracture conductivity.

Thermionic emission theory and diffusion theory applied to CdTe PV devices

In this work, a comprehensive model that takes the phenomenon of carrier thermionic-emission within the frame work of a diffusion theory of current conducting into account in the type Ⅱ hetero-junction Cd Te solar cell is developed. According to this model, it is found that the total current flowing through the Cd Te solar cell is limited by the thermionic process for very thin quasi-neutral regions and limited by the diffusion process for the reverse case. In future research of the Cd Te solar cell, such an approach may enable the determination of the boundary conditions for all doping profiles and computation of the conversion efficiency, etc.