The study of GPX3 methylation in patients with Kashin-Beck Disease and its mechanism in chondrocyte apoptosis

Objective Selenium deficiency is a risk factor for Kashin-Beck Disease (KBD), an endemic osteoarthropathy. Although promoter hypermethylation of glutathione peroxidase 3 (GPX3) (a selenoprotein) has been identified in several cancers, little is known about promoter methylation and expression of GPX3 and their relation to selenium in KBD. The present study was thus conducted to investigate this research question. Methods Methylation and expressions of GPX3 in whole blood drawn from 288 KBD patients and 362 healthy controls and in chondrocyte cell line were evaluated using methylation-specific PCR and qRT-PCR, respectively. The protein levels of PI3K/Akt/c-fos signaling in the whole blood and chondrocyte cell line were determined with Western blotting. Chondrocytes apoptosis were detected by Hoechst 33342 and Annexin V-FITC/PI staining. Results GPX3 methylation was increased, GPX3 mRNA was decreased, and protein levels in the PI3K/Akt/c-fos signaling pathway were up-regulated in the whole blood collected from KBD patients as compared with healthy controls. Similar results were obtained for chondrocytes injured by oxidative stress. There was a significant, decreasing trend in GPX3 expression across groups of unmethylation, partial methylation, and complete methylation for GPX3, in sequence. Compared with unmethylation group, protein levels in PI3K/Akt/c-fos pathway were enhanced in partial and complete methylation groups. Treatment of chondrocytes with sodium selenite resulted in reduced methylation and increased expression of GPX3 as well as down-regulated level of PI3K/Akt/c-fos proteins. Conclusions The methylation and expression of GPX3 and expression of PI3K/Akt/c-fos pathway are altered in KBD and these changes are reversible by selenium supplementation

Rapid Determination of Complete Distribution of Pore and Throat in Tight Oil Sandstone of Triassic Yanchang Formation in Ordos Basin, China

This study aimed to investigate the complete distribution of reservoir space in tight oil sandstone combining casting slices, field emission scanning electron microscopy (FE-SEM), the pore-throat theory model, high-resolution image processing, mathematical statistics, and other technical means. Results of reservoir samples from the Xin'anbian area of Ordos Basin showed that the total pore radius curve of the tight oil sandstone reservoir exhibited a multi-peak distribution, and the peaks appeared to be more focused on the ends of the range. This proved that pores with a radius of 1-50,000 nm provided the most significant storage space for tight oil, indicating that special attention should be paid to this range of the pore size distribution. Meanwhile, the complete throat radius curve of the tight oil sandstone reservoir exhibited a multi-peak distribution. However, the peak values were distributed throughout the scales. This confirmed that the throat radius in the tight oil sandstone reservoir was not only in the range of hundreds of nanometers but was also widely distributed in the scale approximately equal to the pore size. The new rapid determination method could provide a precise theoretical basis for the comprehensive evaluation, exploration, and development of a tight oil sandstone reservoir

Using "Umbrella Deconstruction & Energy Dispersive Spectrometer (UD-EDS)" technique to quantify the anisotropic elements distribution of "Chang 7" shale and its significance

This study utilizes the experimental technique named "Umbrella Deconstruction & Energy Dispersive Spectrometer (UD-EDS)" method to quantify the anisotropic element distribution of shale which has been proved significant in the stimulation of shale. Direct quantification of anisotropic distribution of element in shale from the Triassic Yanchang formation in the HJS" district was carried out to ensure both observational resolution and sample representativeness. Results show that many types of elements distribution vary in eight directions. The element contents are similar in three directions - 90 degrees (270 degrees), 112.5 degrees (292.5 degrees) and 135 degrees (315 degrees), they are quite different from which in other five directions, which has obvious significance in shale stimulation. Results also prove that the evidence of dominant fracture direction in fracturing can be found in brittle minerals. As to "Chang 7" shale, the dominant fracture direction of shale reservoir is distributed in a specific area instead of overall extending along a single direction. In this specific area the best dominant fracture direction can be found. The subsequent results would offer the microscopic evidences for the shale fracturing and point to an innovative direction for research on exploration and development of the unconventional oil and gas. (C) 2019 Elsevier Ltd. All rights reserved

Complex flow in tight oil reservoirs: A new perspective

This study aimed to investigate a new mechanism of complex flow in tight oil reservoirs impacted by hetero-geneous minerals. In this study, a new classification scheme for seepage channels based on mineral types was firstly developed after considering the differences in their mechanical properties. There are nine types of seepage channels, consisting of four types of main minerals or mineral combinations. Results showed that the maximum flow velocity increases in a non-linear way as the average diameter of each type of seepage channel increases. Thus, the larger the diameter of the space, the greater the potential flow capability. As the injection pressure increases, the flow velocity could be higher in the larger seepage channels than the smaller seepage channels. When the oilfield enters the middle and later periods, in general, the oil in most of the large spaces has been removed. The average flow velocity ; thus, a small space does not have a greater potential of exploitation than a large space. This conclusion points to a new direction for enhancing unconventional oil recovery

Estimations of the upper and lower depth limits for kerogen to generate oil/gas worldwide: A hypothesis

This study focuses on the upper and lower depth limits for kerogen to generate oil/gas worldwide. For the first time, the upper and lower depth limits of the conversion process from kerogen to oil/gas are given by the equations with clear physical significance. The method for obtaining the parameters in the equations is also proposed. The results show that the upper limit of hydrocarbon generation of kerogen mainly depends on the ratio of the minimum dissociation energy and initial molar mass of hydrocarbon generation. The smaller the ratio is, the shallower the upper limit of hydrocarbon generation of kerogen is. The upper depth limit of hydrocarbon generation ranges from 688 m to 4925 m, with an average of 1944 m. The lower limit of hydrocarbon generation mainly depends on the ratio of the dissociation energy and molar mass at the end of hydrocarbon generation. The lower depth limit of hydrocarbon generation is proportional to the above ratio. The lower limit of hydrocarbon generation of kerogen ranges from 2539 m to 16 337 m, with an average of 6926 m. This study not only solves a major controversial issue which is the minimum and maximum depth of drilling required to capture oil/gas but also helps select the location of carbon storage. It will be conducive to the effective utilization of fossil energy and the early realization of global carbon neutralization. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved