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We chose the "natural laboratory" provided by high-altitude native ethnic Tibetan women who had completed childbearing to examine the hypothesis that multiple oxygen delivery traits were associated with lifetime reproductive success and had genomic associations. Four hundred seventeen (417) women aged 46 to 86 y residing at ≥3,500 m in Upper Mustang, Nepal, provided information on reproductive histories, sociocultural factors, physiological measurements, and DNA samples for this observational cohort study. Simultaneously assessing multiple traits identified combinations associated with lifetime reproductive success measured as the number of livebirths. Women with the most livebirths had distinctive hematological and cardiovascular traits. A hemoglobin concentration near the sample mode and a high percent of oxygen saturation of hemoglobin raised arterial oxygen concentration without risking elevated blood viscosity. We propose ongoing stabilizing selection on hemoglobin concentration because extreme values predicted fewer livebirths and directional selection favoring higher oxygen saturation because higher values had more predicted livebirths. EPAS1, an oxygen homeostasis locus with strong signals of positive natural selection and a high frequency of variants occurring only among populations indigenous to the Tibetan Plateau, associated with hemoglobin concentration. High blood flow into the lungs, wide left ventricles, and low hypoxic heart rate responses aided effective convective oxygen transport to tissues. Women with physiologies closer to unstressed, low altitude values had the highest lifetime reproductive success. This example of ethnic Tibetan women residing at high altitudes in Nepal links reproductive fitness with trait combinations increasing oxygen delivery under severe hypoxic stress and demonstrates ongoing natural selection., Competing Interests: Competing interests statement:The authors declare no competing interest.

Objective: Blood-blister aneurysms (BBAs) of the internal carotid artery (ICA) are challenging lesions with high morbidity and mortality rates. Although research on BBAs is well documented in different populations, the study of BBAs in the Tibetan population is extremely rare. This study aimed to evaluate the characteristics of BBAs and analyze the treatment modalities and long-term outcomes in the Tibetan population in comparison with the Han population., Methods: The characteristics of patients with BBAs of the ICA from January 2009 to January 2021 at our institution were reviewed. The features of aneurysms, treatment modalities, complications, and follow-up outcomes were retrospectively analyzed., Results: A total of 130 patients (41 Tibetan and 89 Han patients) with BBAs of the ICA who underwent treatment were enrolled. Compared with the Han group, the Tibetan group significantly demonstrated a high ratio of BBAs among ICAs (8.6%, 41/477 vs. 1.6%, 89/5563; p<0.05), a high ratio of vasospasm (34.1%, 14/41 vs. 6.7%, 6/89; p=0.001), a high risk of ischemic events (43.9%, 18/41 vs. 22.5%, 20/89; p<0.05), and a low ratio of good outcomes (modified Rankin scale, 0-2) at the 1-year follow-up (51.2%, 21/41 vs. 74.2%, 66/89; p<0.05). The multivariate regression model showed that ischemic events significantly contributed to the prediction of outcomes at 1 year. Further analysis revealed that microsurgery and vasospasm were associated with ischemic events., Conclusion: In comparison with Han patients, the Tibetan population had a high ratio of BBA occurrence, a high incidence of ischemic events, and a high ratio of poor outcomes. The endovascular approach showed more benefits in BBA patients.

Objective To analyze the clinicopathological features and immunohistochemical expression of meningiomas in the Tibetan population in Tibet,and improve the understanding of meningiomas. Methods The clinical and pathological data of all the meningiomas diagnosed by pathology in Tibet Autonomous Region People's Hospital from April 2013 to March 2021 were analyzed retrospectively.All the cases underwent immunohistochemical staining of trimethylation of lysine 27 on histone H3 (H3K27me3),mucin 4 (MUC4),somatostatin receptor 2 (SSTR2),progesterone receptor,epithelial membrane antigen,glial fibrillary acidic protein,vimentin,S-100,P53,and Ki-67.The histopathological features and the staining results were observed under a light microscope. Results A total of 116 cases of meningiomas were included in this study,with the male-to-female ratio of 1.0∶2.6 and the age of 4-73 years.The main clinical symptom was headache.The imaging examination showed that 114 cases had single lesions and 2 cases had multiple lesions.The tumors were located in the cranium (108 cases) and spinal canal (8 cases).The maximum diameter of the tumors ranged from 0.3 cm to 10.0 cm,with a mean of (5.7±2.2) cm.In terms of microscopic grading and histological types,the 116 cases included 111 cases of WHO grade Ⅰ (including 53 cases of fibrous type,20 cases of meningothelial type,24 cases of transitional type,10 cases of psammomatous type,etc.),4 cases of WHO grade Ⅱ (3 cases of atypical type and 1 case of clear cell type),and 1 case of WHO grade Ⅲ (papillary type).The immunohistochemical staining showed H3K27me3 expression absent in 9 cases (9/116,7.8%),MUC4 positive in 64 cases (64/116,55.2%),SSTR2 positive in 101 cases (101/116,87.1%).Eighty cases had follow-up results,among which 71 cases had no recurrence,while 9 cases recurred. Conclusions Meningioma is the most common tumor in the central nervous system in the pathological file of Tibet.It mainly attacks the middle-aged female patients,occupying the parasagittal sinus,falx,and convex surface of the brain.Fibrous meningioma of WHO grade Ⅰ is common,while the meningiomas of WHO grades Ⅱ and Ⅲ are rare.The expression degree of MUC4 is higher in meningothelial and transitional meningiomas but lower in fibrous meningiomas.There may be no correlation between the absence of H3K27me3 expression and prognosis.

Background: A depressive state is a negative emotional state characterized by abnormal dejection and unpleasant mood. Long-term depressive symptoms can result in psychological disorders such as depression. However, little is known about the depression status and risk factors of the Tibetan people on the Qinghai-Tibet Plateau., Objective: This study explores the depression status of the Tibetan people to better promote ethnic minorities' physical and mental health., Participants and Setting: The Center for Epidemiologic Studies Depression Scale (CES-D) was administered to 24,141 Tibetan people from Yushu Prefecture; the average age was 34.33 years (SD = 9.18, range = 18-94 years)., Materials and Methods: Participants completed questionnaires collecting demographic information and evaluating symptoms of depression., Results: The depression prevalence was higher at high altitudes, and there may be a significant positive correlation between depression rates and altitude. Significant differences were found for each demographic variable. Participants with depressive symptoms (scores ≥8) accounted for 52.3% of the total sample, and participants with depression (scores ≥14) accounted for 28.6%. The binary logistic regression results showed that alcohol drinkers, unmarried participants, participants with high self-assessed socioeconomic status, participants with a high income level, and those with a middle-school education were more likely to be depressed., Conclusions: The results provide the first evidence that the prevalence of depression in Tibetans of the Qinghai-Tibet Plateau is higher than that in the general Chinese population and that reported in Western studies, a finding that may be related to cultural differences and chronic hypoxia caused by the high altitude. This paper offers insight into the mental health status of people living in plateau areas and provides a basis for formulating pertinent mental health policy., Competing Interests: The authors declare that they have no conflicts of interest and there was no significant financial support for this work that could have influenced its outcome. The funders had no role in the study design; the collection, analysis, or interpretation of the data; the writing of the manuscript; or the decision to submit the paper for publication.