Hemoglobin levels and anemia evaluation during pregnancy in the highlands of Tibet: a hospital-based study.

BACKGROUND: Anemia is regarded as a major risk factor for unfavorable pregnancy outcomes, but there have been no previous studies describing the pattern of hemoglobin concentration during pregnancy in Tibet and the relationship between altitude and Hb concentration in the pregnant women living in Tibet still has not been clearly established. The main objectives of this study were to study the hemoglobin levels and prevalence of anemia among pregnant women living in the highlands of Tibet and to evaluate potential associations of hemoglobin and anemia with women's characteristics. METHODS: The hospital-based study was conducted in 380 pregnant women. Their blood samples were tested and related sociodemographic information was collected. Multiple linear regression model and multiple logistic regression model were used to assess the association of pregnant women's characteristics with hemoglobin level and the occurrence of anemia. Centers for Disease Control (CDC), Dirren et al. and Dallman et al. methods were used to adjust the hemoglobin measurements based on altitude for estimating the prevalence of anemia. RESULTS: The mean hemoglobin concentration was 127.6 g/L (range: 55.0-190.0 g/L). Prevalence rate of anemia in this study was 70.0%, 77.9% and 41.3%, respectively for three altitude-correction methods for hemoglobin (CDC method, Dirren et al. method, and Dallman et al. method). Gestational age, ethnicity, residence and income were significantly associated with the hemoglobin concentration and prevalence of anemia in the study population. Specially, the hemoglobin concentration of pregnant women decreased with increase in gestational age. CONCLUSION: The hemoglobin level was low and prevalence rate of anemia was high among pregnant women in Lhasa, Tibet. Gestational age, ethnicity, residence and income were found to be significantly associated with the hemoglobin level and the occurrence of anemia in the study population

Hemoglobin levels and anemia evaluation during pregnancy in the highlands of Tibet: a hospital-based study

<p>Abstract</p> <p>Background</p> <p>Anemia is regarded as a major risk factor for unfavorable pregnancy outcomes, but there have been no previous studies describing the pattern of hemoglobin concentration during pregnancy in Tibet and the relationship between altitude and Hb concentration in the pregnant women living in Tibet still has not been clearly established. The main objectives of this study were to study the hemoglobin levels and prevalence of anemia among pregnant women living in the highlands of Tibet and to evaluate potential associations of hemoglobin and anemia with women's characteristics.</p> <p>Methods</p> <p>The hospital-based study was conducted in 380 pregnant women. Their blood samples were tested and related sociodemographic information was collected. Multiple linear regression model and multiple logistic regression model were used to assess the association of pregnant women's characteristics with hemoglobin level and the occurrence of anemia. Centers for Disease Control (CDC), Dirren et al. and Dallman et al. methods were used to adjust the hemoglobin measurements based on altitude for estimating the prevalence of anemia.</p> <p>Results</p> <p>The mean hemoglobin concentration was 127.6 g/L (range: 55.0-190.0 g/L). Prevalence rate of anemia in this study was 70.0%, 77.9% and 41.3%, respectively for three altitude-correction methods for hemoglobin (CDC method, Dirren et al. method, and Dallman et al. method). Gestational age, ethnicity, residence and income were significantly associated with the hemoglobin concentration and prevalence of anemia in the study population. Specially, the hemoglobin concentration of pregnant women decreased with increase in gestational age.</p> <p>Conclusion</p> <p>The hemoglobin level was low and prevalence rate of anemia was high among pregnant women in Lhasa, Tibet. Gestational age, ethnicity, residence and income were found to be significantly associated with the hemoglobin level and the occurrence of anemia in the study population.</p

Evaluation of a portable hemoglobin photometer in pregnant women in a high altitude area: a pilot study.

BACKGROUND: Anemia is a widespread public health problem associated with an increased risk of morbidity and mortality, especially in pregnant women. This study examined the agreement between a portable hemoglobin photometer and a laboratory analyzer in determining hemoglobin level in pregnant women. METHODS: This study recruited 69 pregnant women in Tibet, China. Capillary blood samples were taken to measure hemoglobin concentration using the hemoglobin photometer and the laboratory analyzer. Limit of agreement, concordance and intraclass correlation coefficient were used to evaluate the agreement. Laboratory measurement was considered as the standard reference method. Sensitivity and specificity were calculated to assess the error in screening for anemia. RESULTS: Mean difference between the two methods was -2.1 g/l. wide 95% limits of agreement were found (-22.6 g/l to 18.4 g/l). The intraclass correlation coefficient was 0.795, and concordance correlation coefficient was 0.793. Sensitivity and specificity were 94.9% and 76.7% respectively. Positive predictive value was 84.1%, and negative predictive value was 92.0%. CONCLUSION: This hemoglobin photometer is not recommended for determining hemoglobin concentration in pregnancy in a high altitude area

Expression of H3K27me3 in Tibetan Patients with Gastric Cancer and Its Significance

Objective  To investigate the expression and its significance of H3K27me3 in Tibetan patients with gastric cancer.  Methods  Clinical and pathological data were retrospectively collected from Tibetan patients with gastric cancer in the Tibet Autonomous Region People's Hospital from August 2019 to August 2021 and Tibetan non-gastric cancer patients during the same period. The expression of H3K27me3 in gastric cancer tissues, corresponding adjacent normal gastric mucosa and normal gastric mucosa of Tibetan patients with non-gastric cancer tissues was detected by immunohistochemical method, and the differences of H3K27me3 expression between gastric cancer patients with different clinical and pathological characteristics was compared.  Results  A total of 54 Tibetan gastric cancer patients and 55 Tibetan non-gastric cancer patients who met the inclusion and exclusion criteria were enrolled. H3K27me3 was localized in the nucleus, and the nucleus showed brownish-yellow granular staining when positively expressed. The high expression rate of H3K27me3 in gastric cancer tissues was significantly higher than that in adjacent normal gastric mucosa tissue[64.8%(35/54) vs. 29.6%(16/54), P < 0.001]and normal gastric mucosal tissue of Tibetan patients with non-gastric cancer[64.8%(35/54) vs. 34.5%(19/55), P=0.002], and the high expression rate of H3K27me3 in the adjacent normal gastric mucosa tissue was not significantly different from that in normal gastric mucosal tissue of Tibetan patients with non-gastric cancer(P=0.683). H3K27me3 expression in gastric cancer tissues was not related to gender, age, degree of differentiation, depth of invasion, maximum tumor size, Lauren's classification, lymph node metastasis, vascular and nerve invasion and TNM stage.  Conclusions  H3K27me3 is highly expressed in gastric cancer tissues of Tibetan people in Tibet. There is no significant difference in H3K27me3 positive expression cells in adjacent tissues and normal gastric mucosa. The significance of H3K27me3 in Tibetan patients with gastric cancer is uncertain and requires further investigations

Altitude adaptation in Tibetans caused by introgression of Denisovan-like DNA.

As modern humans migrated out of Africa, they encountered many new environmental conditions, including greater temperature extremes, different pathogens and higher altitudes. These diverse environments are likely to have acted as agents of natural selection and to have led to local adaptations. One of the most celebrated examples in humans is the adaptation of Tibetans to the hypoxic environment of the high-altitude Tibetan plateau. A hypoxia pathway gene, EPAS1, was previously identified as having the most extreme signature of positive selection in Tibetans, and was shown to be associated with differences in haemoglobin concentration at high altitude. Re-sequencing the region around EPAS1 in 40 Tibetan and 40 Han individuals, we find that this gene has a highly unusual haplotype structure that can only be convincingly explained by introgression of DNA from Denisovan or Denisovan-related individuals into humans. Scanning a larger set of worldwide populations, we find that the selected haplotype is only found in Denisovans and in Tibetans, and at very low frequency among Han Chinese. Furthermore, the length of the haplotype, and the fact that it is not found in any other populations, makes it unlikely that the haplotype sharing between Tibetans and Denisovans was caused by incomplete ancestral lineage sorting rather than introgression. Our findings illustrate that admixture with other hominin species has provided genetic variation that helped humans to adapt to new environments

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Sequencing of 50 human exomes reveals adaptation to high altitude

Residents of the Tibetan Plateau show heritable adaptations to extreme altitude. We sequenced 50 exornes of ethnic Tibetans, encompassing coding sequences of 92% of human genes, with an average coverage of 18x per individual. Genes showing population-specific allele frequency changes, which represent strong candidates for altitude adaptation, were identified. The strongest signal of natural selection came from endothelial Per-Arnt-Sim (PAS) domain protein 1 (EPAS1), a transcription factor involved in response to hypoxia. One single-nucleotide polymorphism (SNP) at EPASl shows a 78% frequency difference between Tibetan and Han samples, representing the fastest allele frequency change observed at any human gene to date. This SNP's association with erythrocyte abundance supports the role of EPASl in adaptation to hypoxia. Thus, a population genomic survey has revealed a functionally important locus in genetic adaptation to high altitude. Copyright 2010 by the American Association for the Advancement of Science; all rights reserved.Link_to_subscribed_fulltex

Altitude adaptation in Tibetans caused by introgression of Denisovan-like DNA

As modern humans migrated out of Africa, they encountered many new environmental conditions, including greater temperature extremes, different pathogens and higher altitudes. These diverse environments are likely to have acted as agents of natural selection and to have led to local adaptations. One of the most celebrated examples in humans is the adaptation of Tibetans to the hypoxic environment of the high-altitude Tibetan plateau1,2,3. A hypoxia pathway gene, EPAS1, was previously identified as having the most extreme signature of positive selection in Tibetans4,5,6,7,8,9,10, and was shown to be associated with differences in haemoglobin concentration at high altitude. Re-sequencing the region around EPAS1 in 40 Tibetan and 40 Han individuals, we find that this gene has a highly unusual haplotype structure that can only be convincingly explained by introgression of DNA from Denisovan or Denisovan-related individuals into humans. Scanning a larger set of worldwide populations, we find that the selected haplotype is only found in Denisovans and in Tibetans, and at very low frequency among Han Chinese. Furthermore, the length of the haplotype, and the fact that it is not found in any other populations, makes it unlikely that the haplotype sharing between Tibetans and Denisovans was caused by incomplete ancestral lineage sorting rather than introgression. Our findings illustrate that admixture with other hominin species has provided genetic variation that helped humans to adapt to new environments