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High altitude polycythemia is a maladaptation of highlanders exposed to hypoxic environment, leading to high blood viscosity and severe cardiorespiratory dysfunction. Prolonged hypoxia causes respiratory depression and severe hypoxemia, and further mediates changes in genetic and molecular mechanisms that regulate erythropoiesis and apoptosis, ultimately resulting in excessive erythrocytosis (EE). This updated review investigated the maladaptive mechanisms of EE, including respiratory chemoreceptor passivation, sleep-related breathing disorders, sex hormones, iron metabolism, and hypoxia-related factors and pathways.

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BACKGROUND: Patients with deep venous thrombosis (DVT) residing at high altitudes can only rely on anticoagulation therapy, missing the optimal window for surgery or thrombolysis. Concurrently, under these conditions, patient outcomes can be easily complicated by high-altitude polycythemia (HAPC), which increases the difficulty of treatment and the risk of recurrent thrombosis. To prevent reaching this point, effective screening and targeted interventions are crucial. Thus, this study analyzes and provides a reference for the clinical prediction of thrombosis recurrence in patients with lower-extremity DVT combined with HAPC. AIM: To apply the nomogram model in the evaluation of complications in patients with HAPC and DVT who underwent anticoagulation therapy. METHODS: A total of 123 patients with HAPC complicated by lower-extremity DVT were followed up for 6-12 months and divided into recurrence and non-recurrence groups according to whether they experienced recurrence of lower-extremity DVT. Clinical data and laboratory indices were compared between the groups to determine the influencing factors of thrombosis recurrence in patients with lower-extremity DVT and HAPC. This study aimed to establish and verify the value of a nomogram model for predicting the risk of thrombus recurrence. RESULTS: Logistic regression analysis showed that age, immobilization during follow-up, medication compliance, compliance with wearing elastic stockings, and peripheral blood D-dimer and fibrin degradation product levels were indepen-dent risk factors for thrombosis recurrence in patients with HAPC complicated by DVT. A Hosmer-Lemeshow goodness-of-fit test demonstrated that the nomogram model established based on the results of multivariate logistic regression analysis was effective in predicting the risk of thrombosis recurrence in patients with lower-extremity DVT complicated by HAPC (χ 2 = 0.873; P > 0.05). The consistency index of the model was 0.802 (95%CI: 0.799-0.997), indicating its good accuracy and discrimination. CONCLUSION: The column chart model for the personalized prediction of thrombotic recurrence risk has good application value in predicting thrombotic recurrence in patients with lower-limb DVT combined with HAPC after discharge.

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High-altitude polycythemia (HAPC) is a common chronic altitude disease caused by living in low-pressure and low-oxygen environment. At present, there is still no effective cure for HAPC. HIF-2α may play an important role in the development of HAPC in regulating the increased red blood cell excessively induced by HIF-EPO and the blood vessel formation induced by VEGF-VEGFR. Here, we established a rat HAPC model and treated it with the HIF-2α inhibitor PT2385. We mainly evaluated the therapeutic effect of PT2385 on HAPC rats by observing the changes in rat phenotype, tissue and organ damage, red blood cell and hemoglobin content, angiogenesis, lipid peroxidation reaction, and inflammatory factors. The results showed that PT2385 treatment improved the congestion phenotype characteristics, inhibited increased erythrocytes and hemoglobin, reduced blood vessel formation, lipid peroxidation, and inflammation, and reduced tissue and organ damage in HAPC rats. This study preliminarly explains the physiological, pathological, and immunological effects of PT2385 treatment for HAPC. It provides a new idea, a reliable experimental basis, and theoretical support for the clinical prevention and treatment of HAPC.

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High-altitude polycythemia (HAPC) affects individuals living at high altitudes, characterized by increased red blood cells (RBCs) production in response to hypoxic conditions. The exact mechanisms behind HAPC are not fully understood. We utilized a mouse model exposed to hypobaric hypoxia (HH), replicating the environmental conditions experienced at 6000 m above sea level, coupled with in vitro analysis of primary splenic macrophages under 1% O2 to investigate these mechanisms. Our findings indicate that HH significantly boosts erythropoiesis, leading to erythrocytosis and splenic changes, including initial contraction to splenomegaly over 14 days. A notable decrease in red pulp macrophages (RPMs) in the spleen, essential for RBCs processing, was observed, correlating with increased iron release and signs of ferroptosis. Prolonged exposure to hypoxia further exacerbated these effects, mirrored in human peripheral blood mononuclear cells. Single-cell sequencing showed a marked reduction in macrophage populations, affecting the spleen's ability to clear RBCs and contributing to splenomegaly. Our findings suggest splenic ferroptosis contributes to decreased RPMs, affecting erythrophagocytosis and potentially fostering continuous RBCs production in HAPC. These insights could guide the development of targeted therapies for HAPC, emphasizing the importance of splenic macrophages in disease pathology.

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Introduction: High-altitude polycythemia (HAPC) is a common chronic high-altitude disease characterized by significantly increased erythrocyte, hemoglobin (Hb), and hematocrit values and decreased arterial oxygen saturation. The mechanisms underlying HAPC development are unclear; we aimed to investigate this in an HAPC rat model. Methods: Twelve Sprague-Dawley rats were divided into control and HAPC groups. The HAPC group was exposed to hypobaric hypoxia. This HAPC model was assessed using routine blood tests and blood gas analyses. Bone marrow, peripheral blood reticulocytes (RETs), and peripheral blood erythrocyte apoptosis were measured using flow cytometry. Erythrocyte osmotic fragility (EOF) tests were conducted. Abnormal erythrocytes were counted using electron microscopy. Plasma-free hemoglobin, 5'-nucleotidase (CD73), adenosine, erythrocyte cytosolic adenosine, sphingosine-1-phosphate (S1P), and 2,3-bisphosphoglycerate (BPG) levels were measured using enzyme-linked immunosorbent assays. Erythrocyte metabolic pathway-related protein [adenosine A2B receptor (ADORA2B), erythrocyte equilibrative nucleoside transporter 1 (eENT1), sphingosine kinase 1 (SPHK1), phospho-SPHK1, bisphosphoglycerate mutase (BPGM), and glyceraldehyde 3-phosphate dehydrogenase (GAPDH)] levels were assessed by Western blotting. Results: The HAPC rat model was successfully established (Hb > 210 g/L). Indices of bone marrow and peripheral blood RET proportions were significantly higher in the HAPC than the control group (p = 0.04 and p < 0.001, respectively). The proportion of peripheral blood erythrocytes in early apoptosis was significantly lower in the HAPC than the control group (p < 0.001). Vesicular erythrocyte and acanthocyte proportions were significantly higher in the HAPC than the control group (p < 0.001 and p = 0.019, respectively). The EOF tests revealed that 50% erythrocyte hemolysis occurred at 4.0-4.5 and 4.5-5.0 g/L NaCl in the control and HAPC groups, respectively. Plasma-free hemoglobin, CD73, adenosine, erythrocyte cytosolic adenosine, S1P, and 2,3-BPG levels and ADORA2B, eENT1, phospho-SPHK1, S1P, BPGM, and GAPDH erythrocyte expression levels (all p ≤ 0.02) were significantly higher in the HAPC than the control group. Conclusion: In model rats, an HAPC-related erythrocyte increase was associated with enhanced bone marrow hematopoietic function and reduced erythrocyte apoptosis, whereas numerous abnormal erythrocytes, increased EOF, and reduced hemolysis resistance were associated with erythrocyte metabolism. CD73/adenosine/S1P/2,3-BPG and eENT1/adenosine/BPGM/2,3-BPG metabolic pathways in erythrocytes were activated in HAPC rats, facilitating oxygen release. These findings further reveal the intrinsic HAPC mechanism and forms a basis for future development of preventive and therapeutic strategies for HAPC.

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BACKGROUND: As a chronic mountain sickness(CMS) with the highest incidence and the greatest harm, the pathogenesis of high altitude polycythemia (HAPC) is still not fully understood. METHODS: 37 HAPC patients and 42 healthy subjects were selected from plateau, and peripheral venous blood samples were collected for transcriptome sequencing on Illumina NovaSeq platform. The sequenced data were analyzed by bioinformatics and phenotypic association analysis. RESULTS: The results showed significant differences in multiple clinical indicators including RBC and HGB et al. existed between HAPC and control. Based on the RNA-seq data, 550 genes with significant differential expression were identified in HAPC patients. GO and KEGG pathway enrichment analysis showed that the up-regulated genes were mainly enriched in processes such as erythrocyte differentiation and development and homeostasis of number of cells, while the down-regulated genes were mainly enriched in categories such as immunoglobulin production, classical pathway of complement activation and other biological processes. The coupling analysis of differential expression genes(DEGs) and pathological phenotypes revealed that 91 DEGs were in close correlation with in the phenotype of red blood cell volume distribution (width-CV and width-SD), and they were all up-regulated in HAPC and involved in the process of erythrocyte metabolism. Combined with the functional annotation of DEGs and literature survey, we found that the expression of several potential genes might be responsible for pathogenesis of HAPC. Besides, cell type deconvolution analysis result suggested that the changes in the number of some immune cell types was significantly lower in HAPC patients than control, implying the autoimmune level of HAPC patients was affected to a certain extent. CONCLUSION: This study provides an important data source for understanding the pathogenesis and screening pathogenic genes of HAPC. We found for the first time that there was a significant correlation between HAPC and the pathological phenotype of width-CV and width-SD, wherein the enriched genes were all up-regulated expressed and involved in the process of erythrocyte metabolism. Although the role of these genes needs to be further studied, the candidate genes can provide a starting point for functionally pinning down the underlying mechanism of HAPC.

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Qile, Muge, Qiying Xu, Yi Ye, Huifang Liu, Drolma Gomchok, Juanli Liu, Tana Wuren, and Ri-Li Ge. Erythrocytes display metabolic changes in high-altitude polycythemia. High Alt Med Biol. 24:104-109, 2023. Background: Sphingosine-1-phosphate (S1P) levels are increased after acute exposure to high altitude; however, whether this effect is observed in chronic high-altitude hypoxia is unknown. Methods: We studied erythrocyte S1P levels in 13 subjects with high-altitude polycythemia (HAPC) and 13 control subjects and also used a mouse model of HAPC. HAPC subjects lived in Maduo (4,300 m altitude) for 10 years, whereas control subjects lived permanently in Xining (2,260 m). The mouse model of HAPC was established by stimulating an altitude of 5,000 m in a hypobaric chamber for 30 days. Hematology and S1P, CD73, 2,3-bisphosphoglycerate (2,3-BPG), and reticulocyte levels were measured. Results: The hemoglobin concentration and number of red blood cells were significantly elevated in human and mouse HAPC groups. Blood S1P levels in HAPC subjects and mice were higher than those in control groups (p < 0.05 and p < 0.001, respectively). 2,3-BPG and CD73 levels in HAPC subjects were significantly higher than those in control subjects (p < 0.05). No significant changes in reticulocyte levels were observed. Conclusions: The critical altitude-induced metabolic changes such as S1P retained high levels even after prolonged exposure, and it may inspire future research into therapeutic strategies for hypoxia-associated illnesses.

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BACKGROUND: As China's population ages, the nationwide prevalence of dementia is increasing. However, the epidemiology of dementia among the Tibetan population remains unclear. OBJECTIVE: A cross-sectional study was conducted involving 9116 participants aged >50 years in the Tibetan population to investigate the risk factors and prevalence of dementia among this population. Permanent residents of the region were invited to participate, and the response rate was 90.7 %. METHODS: The participants underwent neuropsychological testing and clinical assessments, from which physical measurements (e.g., body mass index, blood pressure), demographic information (e.g., gender, age), and lifestyle details (e.g., family living arrangement, smoking, alcohol arrangement) were recorded. Dementia diagnoses were made using the standard consensus diagnostic criteria. The risk factors of dementia were identified using stepwise multiple logistic regression. RESULTS: The average age of the participants was 63.71 (standard deviation = 9.36), and there were 44.86 % males. The prevalence of dementia was 4.66 %. The multivariate logistic regression analysis revealed that older age, unmarried status, lower education level, obesity, hypertension, diabetes, coronary heart disease, cerebral vascular disease, and HAPC were independently and positively associated with dementia (P < 0.05). However, no association was found between the frequency of religious activities and the prevalence of dementia in this population (P > 0.05). CONCLUSIONS: There exist a number of contributory risk factors for dementia in the Tibetan population, with variations associated with high altitude, religious activities (i.e., scripture turning, chanting, spinning Buddhist beads, and bowing), and dietary habits. These findings suggest that social activities, such as religious activities, are protective factors for dementia.

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Liu, Fang, Caiyan Hu, Jin Ding, Chengbing Fu, Shuqiong Wang, and Tiantian Li. GATA-1 promotes erythroid differentiation through the upregulation of miR-451a and miR-210-3p expression in CD34+ cells in high-altitude polycythemia. High Alt Med Biol. 24:59-67, 2023. Background: The clinical manifestations of high-altitude polycythemia (HAPC) include excessive accumulation of erythrocytes, and its pathogenesis is not yet clear. Methods: Peripheral blood was collected from 10 HAPC patients (HAPC group) and normal individuals (control group) each. CD34+ cells were sorted using immunomagnetic beads and differentiated into erythroid cells for 7, 11, and 15 days. Changes in GATA-binding protein 1 (GATA-1), miR-451a, and miR-210-3p expression and their possible regulatory relationships were investigated. Results: Under hypoxia, GATA-1 expression on day 15 was about 2.4 times that on day 7 in the control group and about 1.3 times that on day 7 in the HAPC group, which was significantly lower compared with the control group. miR-451a and miR-210-3p expressions in the HAPC group were 2.6 and 1.8 times that in the control group, respectively, and were significantly increased. When GATA-1 was inhibited, miR-451a and miR-210-3p expressions were significantly decreased by 0.43 and 0.39 times, respectively, compared with those in the control group. Conclusions: Hypoxia stimulated the upregulation of GATA-1 level and accelerated the change of expression, which promoted miR-451a and miR-210-3p expressions and shortened the time taken by cells to enter end-stage differentiation, so as to enhance erythroid differentiation, which may be a pathogenetic mechanism underlying HAPC polycytosis.

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High-altitude polycythemia (HAPC) can occur in individuals who are intolerant to high-altitude hypoxia. In patients with HAPC, erythrocytosis is often accompanied by a decrease in platelet count. Chronic hypoxia can increase the incidence of arteriovenous thrombosis and the risk of bleeding during antithrombotic treatment due to thrombocytopenia; therefore, understanding the cause of thrombocytopenia can reduce the risk of treatment-related bleeding. In this study, we examined platelet production and apoptosis to understand the cause of thrombocytopenia in patients with HAPC. The classification of myeloid-derived megakaryocytes (MKs) in HAPC patients was mainly granular MKs rather than mature MKs, suggesting impaired differentiation and maturation. However, the total number of MKs and newly generated reticulated platelets in the peripheral blood increased, indicating sufficient platelet generation in HAPC thrombocytopenia. Increased platelet apoptosis may be one of the causes of thrombocytopenia. Platelet activation and GP1bα pathway activation induced by thrombin and von Willebrand factor can lead to platelet apoptosis. Platelet production was not reduced in patients with HAPC, whereas platelet apoptosis was associated with thrombocytopenia. These findings provide a rationale for considering the bleeding risk in HAPC patient while treating thrombotic diseases.

What is the context?Platelets are essential in the process of blood clotting; hence, low platelet count increases the risk of bleeding. Thrombocytopenia is present in patients with high-altitude polycythemiaHypoxia can lead to platelet activation and increase in procoagulant factors, while at the same time increase the risk of thrombosis due to erythrocytosis and blood stasis.Antithrombotic therapy should be administered when thrombosis occurs in patients with high altitude polycythemia; however, due to the low platelet count, risk of bleeding must be considered.What is new?In this study, we found that platelet production was not decreased in patients with high-altitude polycythemia.One cause of thrombocytopenia is apoptosis, which is associated with platelet activation, especially GP1bα activation.Inhibition of GP1bα binding to ligand decreased the level of platelet apoptosis.What is the impact?This study provides novel insights into antithrombotic therapy for patients with high-altitude polycythemia complicated by thrombosis.Thrombocytopenia is associated with excessive apoptosis.Interfering with GP1bα targets may have a dual benefit, both in inhibiting thrombosis and avoiding thrombocytopenia.

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BACKGROUND: To assess retinal structural parameters in high-altitude (HA) residents with and without high altitude polycythemia (HAPC) and to elucidate the relationship between retinal structural parameters and hemoglobin (HGB). METHODS: This cross-sectional study included 55 HAPC patients and 52 healthy HA residents. Retinal structural parameters included retinal nerve fiber layer (RNFL) thickness, optic nerve head (ONH) parameters and retinal vessel diameter. RNFL thickness were acquired from spectral domain optical coherence tomography (SD-OCT) built-in software. ONH parameters including neuroretina rim height, cup area, disc area and vertical cup/disc ratio were obtained by OCT built-in software and ImageJ software. Retinal vessel measurements including central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE) and AVR (artery/vein ratio) were calculated by revised formulas for summarizing retinal vessel diameters. All parameters were compared between HAPC group versus healthy HA group. The associations between retinal parameters and HGB were assessed by Pearson correlation analyses. RESULTS: In comparison of HAPC group versus healthy HA group, RNFL thickness was thicker in the nasal quadrant of the optic disc in HAPC group (74.82 ± 14.4 VS. 66.06 ± 13.71 µm, P = 0.002). Bigger disc area and bigger cup area were also observed in HAPC group (all P < 0.05). Meanwhile, the value of CRVE was higher in HAPC group which suggested that retinal veins dilated significantly in HAPC patients (P < 0.001), however, CRAE and AVR were comparable between groups. Pearson analyses revealed that HGB was positive correlated with CRVE in HAPC group (r = 0.469, P = 0.003). CONCLUSIONS: long-term HA exposure secondary HAPC could result in thickened RNFL, enlarged ONH and dilated retinal veins. Moreover, increased blood viscosity caused by HGB should be responsible for dilated veins, but not for thickened RNFL and enlarged ONH. This study deepens the understanding of the impact of HA environment on retina.

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High-altitude polycythemia (HAPC) is a chronic mountain sickness characterized by multiple severe ill-effects. Its pathogenesis is still unclear, and till date, no study has been conducted to investigate the plasma exome profile of Tibetan patients with HAPC. In this study, we aimed to elucidate the pathogenesis of HAPC by determining the microRNA (miRNA) signatures. We compared the plasma exosome miRNA expression profiles of eight patients with HAPC and eight healthy controls using next-generation miRNA sequencing. Further, we extracted and identified plasma exosomes using transmission electron microscopy, nanoparticle tracking analysis, and western blotting. We used quantitative reverse-transcription polymerase chain reaction (qRT-PCR) to validate differentially expressed plasma exosomal miRNAs. Finally, we analyzed the diagnostic values of the differentially expressed miRNAs for HAPC using receiver operating characteristic (ROC) curves. We detected 2007 miRNAs from confirmed plasma exosomes, including 1342 known miRNAs and 665 newly predicted miRNAs. We verified the expression of the top 10 differentially expressed miRNAs via qRT-PCR. Patients with HAPC showed significantly upregulated hsa-miR-122-5p, hsa-miR-423-5p, hsa-miR-4433b-3p, hsa-miR-1291, and hsa-miR-106b-5p expression levels, while hsa-miR-200c-3p expression was downregulated. This study may provide background knowledge for future studies on HAPC studies, which may further facilitate the development of novel therapies against this common disease.

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Hypoxic exposure makes plateau migrators susceptible to high altitude polycythemia (HAPC). Astragalus membranaceus (AM) is an edible and medicinal plant with remarkable immunomodulatory activities. The purpose of this study was to discover if AM could be a candidate for the prevention of HAPC and its mechanism. Here, network pharmacology was applied to screen active compounds, key targets, and enriched pathways of AM in the treatment of HAPC. Molecular docking evaluated the affinity between compounds and core targets. Subsequently, the mechanisms of AM were further verified using the hypoxia exposure-induced mice model of HAPC. The network pharmacology analysis and molecular docking results identified 14 core targets of AM on HAPC, which were predominantly mainly enriched in the HIF-1 pathway. In the HAPC animal models, we found that AM inhibited the differentiation of hematopoietic stem cells into the erythroid lineage. It also suppressed the production of erythrocytes and hemoglobin in peripheral blood by reducing the expression of HIF-1α, EPO, VEGFA, and Gata-1 mRNA. Furthermore, AM downregulated the expression of IL-6, TNF-α, and IFN-γ mRNA, thereby alleviating organ inflammation. In conclusion, AM supplementation alleviates hypoxia-induced HAPC in mice, and TNF-α, AKT1, HIF-1α, VEGFA, IL-6, and IL-1B may be the key targets.

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This study focused on the association of dietary patterns and Tibetan featured foods with high-altitude polycythemia (HAPC) in Naqu, Tibet, to explore the risk factors of HAPC in Naqu, Tibet, to raise awareness of the disease among the population and provide evidence for the development of prevention and treatment interventions. A 1:2 individual-matched case-control study design was used to select residents of three villages in the Naqu region of Tibet as the study population. During the health examination and questionnaire survey conducted from December 2020 to December 2021, a sample of 1,171 cases was collected. And after inclusion and exclusion criteria and energy intake correction, 100 patients diagnosed with HAPC using the "Qinghai criteria" were identified as the case group, while 1,059 patients without HAPC or HAPC -related diseases were identified as the control group. Individuals were matched by a 1:2 propensity score matching according to gender, age, body mass index (BMI), length of residence, working altitude, smoking status, and alcohol status. Dietary patterns were determined by a principal component analysis, and the scores of study subjects for each dietary pattern were calculated. The effect of dietary pattern scores and mean daily intake (g/day) of foods in the Tibetan specialty diet on the prevalence of HAPC was analyzed using conditional logistic regression. After propensity score matching, we found three main dietary patterns among residents in Naqu through principal component analysis, which were a "high protein pattern," "snack food pattern," and "vegetarian food pattern." All three dietary patterns showed a high linear association with HAPC (p < 0.05) and were risk factors for HAPC. In the analysis of the relationship between Tibetan featured foods and the prevalence of HAPC, the results of the multifactorial analysis following adjustment for other featured foods showed that there was a positive correlation between the average daily intake of tsampa and the presence of HAPC, which was a risk factor. Additionally, there was an inverse correlation between the average daily intake of ghee tea and the presence of HAPC, which was a protective factor.

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In high-altitude environments, the prevalence of high-altitude polycythemia (HAPC) ranges between 5 and 18 percent. However, there is currently no effective treatment for this condition. Therefore, disease prevention has emerged as a critical strategy against this disease. Here, we looked into the microarray profiles of GSE135109 and GSE29977, linked to either short- or long-term exposure to the Qinghai Tibet Plateau (QTP). The results revealed inhibition in the adaptive immune response during 30 days of exposure to QTP. Following a gene set enrichment analysis (GSEA) discovered that genes associated with HAPC were enriched in Cluster1, which showed a dramatic upregulation on the third day after arriving at the QTP. We then used GeneLogit to construct a logistic prediction model, which allowed us to identify 50 genes that classify HAPC patients. In these genes, LRRC18 and HCAR3 were also significantly altered following early QTP exposure, suggesting that they may serve as hub genes for HAPC development. The in-depth study of a combination of the datasets of transcriptomic changes during exposure to a high altitude and whether diseases occur after long-term exposure in Hans can give us some inspiration about genes associated with HAPC development during adaption to high altitudes.

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High-altitude polycythemia (HAPC) is characterized by excessive proliferation of erythrocytes, resulting from the hypobaric hypoxia condition in high altitude. The genetic variants and molecular mechanisms of HAPC remain unclear in highlanders. We recruited 141 Tibetan dwellers, including 70 HAPC patients and 71 healthy controls, to detect the possible genetic variants associated with the disease; and performed targeted sequencing on 529 genes associated with the oxygen metabolism and erythrocyte regulation, utilized unconditional logistic regression analysis and GO (gene ontology) analysis to investigate the genetic variations of HAPC. We identified 12 single nucleotide variants, harbored in 12 genes, associated with the risk of HAPC (4.7 ≤ odd ratios ≤ 13.6; 7.6E - 08 ≤ p-value ≤ 1E - 04). The pathway enrichment study of these genes indicated the three pathways, the PI3K-AKT pathway, JAK-STAT pathway, and HIF-1 pathway, are essential, which p-values as 3.70E - 08, 1.28 E - 07, and 3.98 E - 06, respectively. We are hopeful that our results will provide a reference for the etiology research of HAPC. However, additional genetic risk factors and functional investigations are necessary to confirm our results further. Supplementary Information: The online version contains supplementary material available at 10.1007/s12288-021-01474-1.

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High-altitude polycythemia (HAPC) is a clinical syndrome that occurs in native inhabitants or long-term residents living at altitude. The kidney is one of the most affected organs. However, the clinical and kidney histopathological profiles of HAPC-related kidney disease have rarely been reported. Here, we report kidney biopsy-based clinicopathological study on this disease. HAPC was defined as excessive erythrocytosis [females, hemoglobin 190 g/L or more; males, 210 g/L or more] in patients living above an altitude of 2500 m for more than ten years. A total of 416 Tibetan patients underwent kidney biopsy between January 1, 2016, and November 31, 2020. Of these patients 17 met the diagnostic criteria for HAPC-related kidney disease. Clinically, these patients had a median urinary protein level of 2.5 g/24-hour (range 1.81-6.85). Twelve patients had hyperuricemia, nine had hypertension, and three had kidney insufficiency. On histopathology, glomerular hypertrophy, glomerular basement membrane thickening, podocyte foot process effacement, segmental glomerulosclerosis and global glomerulosclerosis were the main features. Extraglomerular arterial/arteriolar lesions were common, presenting as intimal fibrosis, hyalinosis and endothelial cell swelling/subintimal edema. Expansion of the arterial/arteriolar medial wall area characterized by smooth muscle cell proliferation was clearly observed, potentially indicating vascular remodeling. Hypoxia-inducible factor 2α was expressed in the kidney tissues of these patients. Thus, the pathological changes of HAPC-related kidney disease encompassed both glomerular and extraglomerular vascular lesions, suggesting a key role of both chronic hypoxia itself and secondary hemodynamic changes in the pathogenesis of this disease.

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OBJECTIVE: To explore the relationship between high altitude polycythemia (HAPC) and peptic ulcer bleeding, in order to provide the evidence for the clinical diagnosis and treatment of peptic ulcer disease in Tibet of China. METHODS: A retrospective case-control study was conducted. Patients who hospitalized in the Department of Gastroenterology with the diagnosis of peptic ulcer bleeding from January 1, 2015 to April 30, 2021 in Tibet Autonomous Region People's Hospital were enrolled in the case group, and patients who hospitalized in the Department of Urology without tumor and without the history of peptic ulcer and gastrointestinal bleeding during the same period were selected as the control group. In the study, 1 ∶ 1 case matching was conducted between the two groups according to the gender, age (±2 years), ethnic group (Tibetan, Han), and the residence altitude level (grouped by < 4 000 m or ≥4 000 m), and 393 cases were included in the case group and the control group respectively. All the patients had lived in Tibet with the altitude >2 500 m for more than 1 year, and with age ≥ 18 years. The risk factors of peptic ulcer bleeding (place of residence, smoking, alcohol, the use of NSAIDs/anticoagulants, and combined with chronic diseases, such as HAPC, hypertension, diabetes mellitus, heart disease, hyperlipidemia, cerebrovascular disease, chronic lung disease, joint disease) were analyzed and compared between the two groups. RESULTS: There were 28 (7.1%) patients with HAPC in the case group, and 5 (1.3%) in the control group. The incidence of HAPC in the case group was significantly higher than those in the control group, P < 0.001, and the OR value was 5.953. Multivariate Logistic regression analysis showed that HAPC (OR=5.270, 95%CI: 1.806-15.380), living in cities and towns (OR=2.369, 95%CI: 1.559-3.602), alcohol (OR=3.238, 95%CI: 1.973-5.317) and the use of NSAIDs/anticoagulants (OR=20.584, 95%CI: 2.639-160.545) were the independent risk factors for peptic ulcer bleeding in Tibet. After adjusting for the possible confounding factors, such as living in cities and towns, alcohol, and the use of NSAIDs/anticoagulants, HAPC was associated with an increased risk of peptic ulcer bleeding in Tibet, and the OR value was 5.270. CONCLUSION: HAPC was associated with a significantly increased risk of peptic ulcer bleeding in Tibet. Patients with HAPC and peptic ulcer should be diagnosed and treated actively, in order to avoid gastrointestinal bleeding and other serious complications.

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OBJECTIVE@#To explore the relationship between high altitude polycythemia (HAPC) and peptic ulcer bleeding, in order to provide the evidence for the clinical diagnosis and treatment of peptic ulcer disease in Tibet of China.@*METHODS@#A retrospective case-control study was conducted. Patients who hospitalized in the Department of Gastroenterology with the diagnosis of peptic ulcer bleeding from January 1, 2015 to April 30, 2021 in Tibet Autonomous Region People's Hospital were enrolled in the case group, and patients who hospitalized in the Department of Urology without tumor and without the history of peptic ulcer and gastrointestinal bleeding during the same period were selected as the control group. In the study, 1 ∶ 1 case matching was conducted between the two groups according to the gender, age (±2 years), ethnic group (Tibetan, Han), and the residence altitude level (grouped by < 4 000 m or ≥4 000 m), and 393 cases were included in the case group and the control group respectively. All the patients had lived in Tibet with the altitude >2 500 m for more than 1 year, and with age ≥ 18 years. The risk factors of peptic ulcer bleeding (place of residence, smoking, alcohol, the use of NSAIDs/anticoagulants, and combined with chronic diseases, such as HAPC, hypertension, diabetes mellitus, heart disease, hyperlipidemia, cerebrovascular disease, chronic lung disease, joint disease) were analyzed and compared between the two groups.@*RESULTS@#There were 28 (7.1%) patients with HAPC in the case group, and 5 (1.3%) in the control group. The incidence of HAPC in the case group was significantly higher than those in the control group, P < 0.001, and the OR value was 5.953. Multivariate Logistic regression analysis showed that HAPC (OR=5.270, 95%CI: 1.806-15.380), living in cities and towns (OR=2.369, 95%CI: 1.559-3.602), alcohol (OR=3.238, 95%CI: 1.973-5.317) and the use of NSAIDs/anticoagulants (OR=20.584, 95%CI: 2.639-160.545) were the independent risk factors for peptic ulcer bleeding in Tibet. After adjusting for the possible confounding factors, such as living in cities and towns, alcohol, and the use of NSAIDs/anticoagulants, HAPC was associated with an increased risk of peptic ulcer bleeding in Tibet, and the OR value was 5.270.@*CONCLUSION@#HAPC was associated with a significantly increased risk of peptic ulcer bleeding in Tibet. Patients with HAPC and peptic ulcer should be diagnosed and treated actively, in order to avoid gastrointestinal bleeding and other serious complications.

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【Objective】 To investigate the quality changes of suspended red blood cells (SRBCs) prepared from the blood of Tibetan high Hb population, and explore the availability and safety of blood collected from Tibetan high Hb population. 【Methods】 The voluntary blood donors were grouped according to the Hb concentration at the initial screening: female blood donors from Tibet Autonomous Region (>3 500 m) with Hb≥190 g/L and male blood donors with Hb≥210 g/L were classified as plateau high hemoglobin group. A total of 13 male blood donors from Tibet Autonomous Region were recruited. And the female blood donors (n=13) with Hb(115~165) g/L and male blood donors (n=12) with Hb(120~185) g/L from Chengdu were classified as control group. Whole blood of 200 mL specification was centrifuged to remove the plasma, and MAP additive solution was added to prepare SRBCs, then SRBCs were divided into four aliquots (50 mL/bag and stored at 4℃. Parameters as blood routine, free Hb and hemolysis rate were measured aseptically at day 1, 14, 21, 35 of storage. And 10 mL SRBCs was used to extract membrane proteins for tyrosine phosphorylation detection of band 3 protein. 【Results】 The RBCs counts(×1012/L), hematocrit(%) and hemoglobin(g/L) of Tibetan high Hb group and control group were 6.76±0.95 vs 4.65±0.52, 63.3±6.8 vs 43.1±4.4 and 214.4±19.8 vs 143.2±16.9 (P<0.01). The erythrocyte deformability test on the day 1, 14, 21, 35 of storage showed that the deformability of SRBCs prepared from Tibetan high Hb group was significantly lower than that of the control group under shear stress of 3, 5.33, 9.49, 16.87, and 30 Pa, while the hemolysis rate of SRBCs prepared from the Tibetan high Hb group and the control group on the day 1, 14, 21, 35 were 0.050 2±0.040 2 vs 0.022 2±0.011 1, 0.055 4±0.043 vs 0.032 1±0.028 7, 0.061 2±0.025 9 vs 0.034 3±0.031 7 and 0.069 6±0.032 0 vs 0.044 0±0.033 3 (P<0.05). Western blotting showed that the cytoplasmic N-terminal Y21 of band 3 protein of SRBCs prepared from Tibetan high Hb group was highly phosphorylated. 【Conclusion】 The deformability of SRBCs prepared from the Tibetan high Hb group was significantly lower while the hemolysis rate of SRBCs was higher than that of the control group. The hemolysis rate of the SRBCs at the end of storage prepared from the Tibetan high Hb group meets the requirements of the national standard GB18469-2012(<0.8%). The increase of hemolysis rate of SRBCs prepared from the Tibetan high Hb group was closely related to the phosphorylation of band 3 protein.