Guanxintai Exerts Protective Effects on Ischemic Cardiomyocytes by Mitigating Oxidative Stress

Oxidative stress participates in numerous myocardial pathophysiological processes and is considered a therapeutic target for myocardial ischemia and heart failure. Guanxintai (GXT), a traditional Chinese medicine, is commonly used to treat cardiovascular disease on account of its numerous beneficial physiological activities, such as dilating coronary arteries, inhibiting platelet aggregation, and reducing the serum lipid content. However, the antioxidative properties of GXT and potential underlying mechanisms remain to be established. In the present study, we investigated the protective effects of GXT on ischemic cardiomyocytes and the associated antioxidative mechanisms, both in vivo and in vitro. Notably, GXT treatment reduced the degree of cardiomyocyte injury, myocardial apoptosis, and fibrosis and partially improved cardiac function after myocardial infarction. Furthermore, GXT suppressed the level of ROS as well as expression of NADPH oxidase (NOX) and phospho-p38 mitogen-activated protein kinase (MAPK) proteins. Our results collectively suggest that the protective effects of GXT on ischemic cardiomyocytes are exerted through its antioxidative activity of NOX inhibition

Geology, U-Pb geochronology and stable isotope geochemistry of the Heihaibei gold deposit in the southern part of the Eastern Kunlun Orogenic Belt, China : A granitic intrusion-related gold deposit?

The Heihaibei gold deposit is a newly discovered gold deposit in the southern part of the Eastern Kunlun Orogenic Belt. Its most distinctive features are that the gold mineralization is hosted in monzogranite, and that the presence of pre-ore (possibly syn-ore) monzogranite and post-ore gabbro allows to constrain the minerali-zation's formation age. Zircons from the monzogranites yield U-Pb ages of 454 +/- 3 Ma, while zircons separated from the gabbro dikes cutting the monzogranites and gold mineralized body yield U-Pb ages of 439 +/- 3 Ma, which is interpreted to be the minimum age of the Au mineralizing event. Combined with the regional geological background, we proposed that the Heihaibei Au mineralization occurred during the subduction stage of the Early Paleozoic Proto-Tethys ocean. The ore assemblage is dominated by pyrite, arsenopyrite and native gold. The hydrothermal alteration that has led to the peculiar enrichment of Au is not systematically distributed and displays no clear concentric zoning pattern. The main mineralization formed during three stages: the K-feldspar-quartz-pyrite (Py1)-arsenopyrite-sericite-epidote stage (I), the quartz-pyrite (Py2)-native gold-chlorite stage (II), and the quartz-carbonate stage (III). The main gold mineralization occurred during stage II. Fluid inclusion homogenization temperature and salinities decrease from stage I (Th., 268-412 C; W., 6.87-16.63 wt% NaCl equiv.) to stage II (Th., 183-288 C; W., 3.69-14.84 wt% NaCl equiv.). The 818O and 8D values (818OH2O = 4.9 to 9.7%o; 8DV-SMOW =-84.1%o to -81.1%o) of quartz samples from stage I and stage II are comparable to a magmatic-hydrothermal ore-forming fluid that possibly underwent fluid-rock interaction with the Nachitai Group metamorphic rocks during the early ore-forming stage. The relatively uniform 834S values (834SV-CDT = 7.7 to 8.5%o) are slightly elevated compared to magmatic 834S values, but could be derived from a magma if a significant crustal melt component is present. Moreover, the 834S values are within the S isotopic composition range of a granitic reservoir, suggesting that they are probably inherited from the Heihaibei monzogranites. The Pb and Hf isotope compositions imply a close genetic association between the gold mineralization and granitic magmatism, which are both the products of the mixing of crustal and mantle sources. The trace element compositions of pyrite provide additional evidence that the gold mineralization in the Heihaibei deposit was related to the magmatism. Compared with the typical characteristics of orogenic gold and intrusion-related gold systems (IRGS) deposits, the Heihaibei gold deposit may instead be classified as a granitic intrusion-related gold deposit.Peer reviewe

Petrogenesis, Sources, and Tectonic Settings of Triassic Volcanic Rocks in the Ela Mountain Area of the East Kunlun Orogen: Insights from Geochronology, Geochemistry and Hf Isotopic Compositions

The Ela Mountain area is located at the easternmost point of the East Kunlun Orogen, in which voluminous igneous rocks developed in the Triassic period, and it is a good place to investigate the tectonic evolution of the Paleo-Tethys Ocean. In this study, petrological, geochemical, zircon U-Pb geochronology and zircon Hf isotope studies were carried out on the volcanic rocks in the Ela Mountain area. Dacite (239.3 ± 1.4 Ma) exhibits calc-alkaline I-type characteristics, and rhyolite (237.8 ± 2.1 Ma) is similar to high-K calc-alkaline highly fractionated I-type volcanic rock. The petrogenesis shows that both rhyolite and dacite originated from the partial melting of the mafic lower crust of the Mesoproterozoic under relatively high temperature and low pressure. Dacite and rhyolite were derived from the same or similar parent magma, and they are volcanic rocks with different differentiation degrees formed in the same magmatic pulse activity. Differing from rhyolite and dacite, basaltic andesite shows a relatively young age (234 ± 1.2 Ma), mainly originating from the partial melting of the lithospheric mantle modified by subducted slab-derived fluids; the magma was contaminated with a small amount of crustal source components and experienced the fractional crystallization of mafic minerals before the eruption to the surface. This study on the tectonic environment of these volcanic rocks shows that they were formed in the environment of slab failure in the late stage of syn-collision, and that they are different types of volcanic rocks from different sources under similar tectonic environments. The volcanic rocks of the Ela Mountain area in this contribution provide important evidence for Middle Triassic to Late Triassic syn-collisional magmatism in the slab failure stages. The results of this study constrain the lower age limit of the closure of the Paleo-Tethys Ocean and the initial time of extension of the late stage of syn-collision, providing important information regarding regional tectonic evolution processes and volcanic activity history. They can be applied to regional tectonic evolution, petrology, volcanic stratigraphy and mineral deposits related to volcanic rocks

Petrogenesis, Sources, and Tectonic Settings of Triassic Volcanic Rocks in the Ela Mountain Area of the East Kunlun Orogen: Insights from Geochronology, Geochemistry and Hf Isotopic Compositions

The Ela Mountain area is located at the easternmost point of the East Kunlun Orogen, in which voluminous igneous rocks developed in the Triassic period, and it is a good place to investigate the tectonic evolution of the Paleo-Tethys Ocean. In this study, petrological, geochemical, zircon U-Pb geochronology and zircon Hf isotope studies were carried out on the volcanic rocks in the Ela Mountain area. Dacite (239.3 ± 1.4 Ma) exhibits calc-alkaline I-type characteristics, and rhyolite (237.8 ± 2.1 Ma) is similar to high-K calc-alkaline highly fractionated I-type volcanic rock. The petrogenesis shows that both rhyolite and dacite originated from the partial melting of the mafic lower crust of the Mesoproterozoic under relatively high temperature and low pressure. Dacite and rhyolite were derived from the same or similar parent magma, and they are volcanic rocks with different differentiation degrees formed in the same magmatic pulse activity. Differing from rhyolite and dacite, basaltic andesite shows a relatively young age (234 ± 1.2 Ma), mainly originating from the partial melting of the lithospheric mantle modified by subducted slab-derived fluids; the magma was contaminated with a small amount of crustal source components and experienced the fractional crystallization of mafic minerals before the eruption to the surface. This study on the tectonic environment of these volcanic rocks shows that they were formed in the environment of slab failure in the late stage of syn-collision, and that they are different types of volcanic rocks from different sources under similar tectonic environments. The volcanic rocks of the Ela Mountain area in this contribution provide important evidence for Middle Triassic to Late Triassic syn-collisional magmatism in the slab failure stages. The results of this study constrain the lower age limit of the closure of the Paleo-Tethys Ocean and the initial time of extension of the late stage of syn-collision, providing important information regarding regional tectonic evolution processes and volcanic activity history. They can be applied to regional tectonic evolution, petrology, volcanic stratigraphy and mineral deposits related to volcanic rocks

Zircon U-Pb dating and sulfide Re-Os isotopes of the Xiarihamu Cu-Ni sulfide deposit in Qinghai Province, Northwestern China

The Xiarihamu Cu-Ni sulfide deposit is the secondary largest Cu-Ni deposit in China, located in the Eastern Kunlun orogenic belt. However, despite some previous study, the formation and evolution of this deposit remains a key unknown in the tectonic evolution of the Eastern Kunlun Orogenic Belt. Moreover, the petrogenesis of the ore-bearing rocks and the nature of ore genesis are the subject of on-going debate. Here, we present detailed field observations, petrology, zircon U-Pb geochronology, and Re-Os isotopic analyses to constrain the timing and genesis of the Xiarihamu Cu-Ni sulfide deposit. Sulfides from the massive ores yielded a Re-Os isotopic isochron age of 408 11 Ma. Four samples from the ore-bearing Xiarihamu mafic-ultramafic intrusions yielded zircon U-Pb ages of 423.12 Ma, 422.93.1 Ma, 422.72.3 Ma, and 422.62.7 Ma, respectively, indicating that the ore formed during the Silurian. The calculated initial 187Os/188Os ratio and γOs values ranged from 0.5109 to 0.8499 and from 311 to 584, respectively, indicating that crustal contamination played an extremely important role in triggering sulfide saturation. In combination with previous research, drill core observations and Re-Os data provide robust evidence for multiple pulses of magma replenishment throughout the process of ore genesis. Based on this evidence, the large-scale magmatic Cu-Ni mineralization in Xiarihamu likely occurred in a post-collisional setting related to tectonic slab breakoff.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Testosterone Replacement Modulates Cardiac Metabolic Remodeling after Myocardial Infarction by Upregulating PPARα

Despite the importance of testosterone as a metabolic hormone, its effects on myocardial metabolism in the ischemic heart remain unclear. Myocardial ischemia leads to metabolic remodeling, ultimately resulting in ATP deficiency and cardiac dysfunction. In the present study, the effects of testosterone replacement on the ischemic heart were assessed in a castrated rat myocardial infarction model established by ligating the left anterior descending coronary artery 2 weeks after castration. The results of real-time PCR and Western blot analyses showed that peroxisome proliferator-activated receptor α (PPARα) decreased in the ischemic myocardium of castrated rats, compared with the sham-castration group, and the mRNA expression of genes involved in fatty acid metabolism (the fatty acid translocase CD36, carnitine palmitoyltransferase I, and medium-chain acyl-CoA dehydrogenase) and glucose transporter-4 also decreased. A decline in ATP levels in the castrated rats was accompanied by increased cardiomyocyte apoptosis and fibrosis and impaired cardiac function, compared with the sham-castration group, and these detrimental effects were reversed by testosterone replacement. Taken together, our findings suggest that testosterone can modulate myocardial metabolic remodeling by upregulating PPARα after myocardial infarction, exerting a protective effect on cardiac function

Geochemistry, Geochronology, and Hf-S-Pb Isotopes of the Akechukesai IV Mafic-Ultramafic Complex, Western China

The Akechukesai IV mafic−ultramafic complex, located in the western segment of the eastern Kunlun orogenic belt (EKOB), represents a newly-discovered complex, containing Ni ores at grades of up to 0.98% Ni. It is dominated by olivine pyroxenite, pyroxenite, and gabbro units. The gabbros are enriched in lithophile elements (e.g., Rb, U, and K) and light rare-earth elements (LREE), with negative anomalies in high field-strength elements, except Zr, Ta. Nb/Ta(∼5) and Zr/Hf (∼10) ratios lower than the primitive mantle and chondrites, respectively, indicate the influence of the mantle metasomatic process or fractionation of accessory mineral phases. Zircon U−Pb dating of the gabbro yielded an age of 423.9 ± 2.6 Ma, indicating that the complex formed contemporaneously with the Xiarihamu Ni deposit (423 ± 1 Ma). The gabbro has negative εHf(t) values (−11.3 to −1.2) with corresponding TDM1 ages of 1535−1092 Ma. The vein-like and disseminated mineralization (i.e., pyrite and pyrrhotite) have δ34S values of 13.1‰−13.4‰ and 5.0‰−8.5‰, respectively, suggesting that the magmas that formed the complex assimilated crustal sulfur. They yield 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values of 17.323−18.472, 15.422−15.626, and 37.610−38.327, respectively, indicating Pb derived from multiple sources (i.e., mantle crustal sources). Geochemical and Hf−S−Pb isotopic characteristics suggest that the complex formed from a primitive magma derived by partial melting of a spinel- and garnet-bearing lherzolite mantle at variable degree of 5%−10%. This source region was geochemically enriched by previous interaction with slab-related fluids. Tectonic reconstruction suggests that the Akechukesai IV complex was generated in a post-collisional extensional environment