Study of the correlation between NRAMP1 gene polymorphisms and susceptibility to tuberculosis in Tibetan people in Qinghai / 中华微生物学和免疫学杂志

Objective To investigate the correlation between NRAMP1 gene polymorphisms and susceptibility to tuberculosis ( TB) in Tibetan people in Qinghai. Methods A case-control study was con-ducted in this study, involving 99 Tibetan patients with TB and 89 healthy Tibetans. The single nucleotide polymorphisms of NRAMP1 gene at rs17235409 and rs3731865 sites were detected by using TaqMan probe method. Gene cloning and sequencing typing were performed to analyze the single nucleotide polymorphisms of NRAMP1 gene at the rs17235416 site. SPASS20. 0 software was used to statistically analyze the correla-tion between NRAMP1 gene polymorphisms and susceptibility to TB in Tibetan people. Results No signifi-cant difference in the genotype frequencies of rs3731865 and rs17235409 was found between the two groups (χ2=0. 852, P=0. 356;χ2=0. 279, P=0. 597). The genotype frequencies of TGTG/TGTG and TGTG/del+del/del at the rs17235416 site were 70. 7% ( 70/99 ) and 29. 3% ( 29/99 ) in patients with TB and 86. 5% (77/89) and 13. 5% (12/89) in healthy subjects. There were significant differences in the geno-type frequencies of TGTG/TGTG and TGTG/del+del/del between the two groups (χ2=6. 870, P=0. 009). The genotypes of TGTG/del and del/del at rs17235416 were risk factors for TB ( OR=0. 376; 95%CI:0. 178-1. 794 as compared with the TGTG/TGTG genotype in Tibetan people in Qinghai. Conclusion This study suggested that the NRAMP1 gene polymorphisms at rs3731865 and rs1723409 sites had no correlation with the susceptibility to TB in Tibetans in Qinghai. However, the NRAMP1 gene polymorphisms at rs17235416 site were correlated with the susceptibility to TB. The TGTG/del alleles at the rs17235416 site might be the risk factors for tuberculosis in Tibetans in Qinghai.

Cardiac adaptation to high altitude in the plateau pika (Ochotona curzoniae).

The aim of this study was to assess maximal heart rate (HR) and heart morphological changes in high altitude living "plateau pikas" and rats bred at 2260 m. Rats and pikas were catheterized to measure HR (2260 m). After baseline measurements, 1 mg/kg of atropine (AT) and increasing doses of isoproterenol (IsoP) (0.1, 1, 10, and 100 µg kg) were injected into animals. Right (RV) and left ventricles (LV) were removed to calculate Fulton's ratio (LV + septum (S) to RV weights) and to assess mRNA expression level of ß1- and ß2-adrenoceptors, muscarinic m1 and m2 receptors, and vascular endothelial growth factor (VEGF). Resting HR was significantly lower in rats than in pikas and increased after AT injection only in rats. IsoP injection induced a significant increase in HR in rat for all doses, which was systematically greater than in pikas. In pikas HR was slightly increased only after the two highest concentrations of IsoP. Fulton's ratio was greater in rats compared with pikas but the LV + S adjusted for body weight was greater in pikas. Pikas showed lower ß1-adrenoceptors and muscarinic m2 receptors mRNA expression but larger VEGF mRNA expression than rats both in RV and LV. These results suggest that pikas have a lower maximal HR compared with rats certainly due to a decrease in ß-adrenergic and muscarinic receptors mRNA expression. However, the LV hypertrophy probably led to an increase in stroke volume to maintain cardiac output in response to the cold and hypoxic environment.

The mechanism of miR-181c induced neuroprotection by hypoxia preconditioning in rats / 中华神经科杂志

Objective To investigate the neuroprotective effect of miR-181c on hypoxia-preconditioned ischemia in rats and its mechanism.Methods Thirty-nine male SD rats were randomly divided into 5 groups of control group,sham-operated group,middle cerebral artery occlusion (MCAO)group,hypoxia-preconditioned group,hypoxia-preconditioned and MCAO group.Infarct volume and behavioral deficits were quantified.Real-time PCR was applied to detect the expression levels of miR-181c and Western blotting was used to verify the target protein of mt-cox1.Results Under the treatment of hypoxia-preconditioned,the neurological impairment was alleviated and the infarct volume was reduced significantly from 22.50％ ±2.96％ to 16.40％ ±3.13 ％ (t =5.26,P ＜0.01).The expression of miR-181c was decreased significantly in hypoxia-preconditioned and MCAO group than that in MCAO group (1.89 ± 0.14 vs 3.05 ± 0.26,t =6.10,P ＜ 0.01),and the expression of mt-cox1 protein was also significantly decreased (0.54 ± 0.07 vs 0.93 ± 0.04,t =8.01,P ＜ 0.01).Conclusion Hypoxia-preconditioned may attenuate the ischemic injury in SD rats,which may be related to the down-regulation of the expression of miR-181c,therefore increasing the expression of its targeted protein mt-cox1.

Long-term ventilatory adaptation and ventilatory response to hypoxia in plateau pika (Ochotona curzoniae): role of nNOS and dopamine.

We assessed ventilatory patterns and ventilatory responses to hypoxia (HVR) in high-altitude (HA) plateau pikas, repetitively exposed to hypoxic burrows, and control rats. We evaluated the role of neuronal nitric oxide synthase (nNOS) and dopamine by using S-methyl-l-thiocitrulline (SMTC) inhibitor and haloperidol antagonist, respectively. Ventilation (Vi) was measured using a whole body plethysmograph in conscious pikas (n = 9) and low-altitude (LA) rats (n = 7) at different Pi(O(2)) (56, 80, 111, 150, and 186 mmHg) and in HA acclimatized rats (n = 9, 8 days at 4,600 m) at two different Pi(O(2)) (56 and 80 mmHg). The effects of NaCl, SMTC, and haloperidol on ventilatory patterns were assessed in pikas at Pi(O(2)) = 56 and 80 mmHg. We observed a main species effect with larger Vi, tidal volume (VT), inspiratory time/total time (T(i)/T(tot)), and a lower expiratory time in pikas than in LA rats. Pikas had also a larger VT and lower respiratory frequency compared with HA rats in hypoxia. HVR of pikas and rats were not statistically different. In pikas, SMTC induced a significant increase in Vi and VT for a Pi(O(2)) of 56 mmHg, but had no effect for a PiO(2) of 80 mmHg, i.e., the living altitude of pikas. In pikas, haloperidol injection had no effect on any ventilatory parameter. Long-term ventilatory adaptation in pikas is mainly due to an improvement in respiratory pattern (VT and T(i)/T(tot)) with no significant improvement in HVR. The sensitivity to severe acute hypoxia in pikas seems to be regulated by a peripheral nNOS mechanism.

Expression of aquaporin 2 in rat kidney under hypoxia at an altitude of 4600 m / 中华肾脏病杂志

Objective To investigate the change of aquaporin 2 (AQP2) mRNA and protein levels in renal collecting duct of SD rats after hypoxin caused by rising of the altitude to 4600 m. Methods Forty male SD rats were randomly divided into 4 groups (24 h, 48 h, 72 h and 1 week group), and 10 rats in Xining city were used as control group. All the 40 SD rats were transported to Kekexili Natural Reservation areas (4600 m) in Qinghai province. Rats of four experimental groups were sacrificed and renal tissue samples were harvested at different time point respectively, the control group rats were treated in Xining city (2260 m) as well. The concentration of plasma antidiuretic hormone (ADH) was measured by radioimmunity method. The expression of AQP2 mRNA and proteins was evaluated by real-time fluorescent quantitative-PCR, Western blot and immunofluorescence assay. Results The concentration of plasma ADH was decreased at 24 h and was only 28.5% of that of control group, reaching the lowest concentration at 48 h [(86.94±6.49) μg/L vs (302.5±310.48) μg/L], then it increased gradually and was similar to the control group at 7 d [(306.46±11.14) μg/L vs (302.53±10.48)μg/L, P＞ 0.05]. There were significant differences of the control group with 24 h, 48 h and 72 h groups, respectively[(302.53± 10.48) μg/L vs (142.46±10.57)μg/L, (86.94±6.49)μg/L, (169.65±11.15) μg/L respectively, P＜0.01]. The change of AQP2 gene expression level was consistent with the change of ADH. It was decreased at the begining when exposure to altitude and it reached its lowest level at 48 h. It was then returned to high level similarly to that of the control group at 7 d (0.09±0.01 vs 0.09± 0.008, P＞0.05 ). There were significant differences of the control group with 24 h, 48 h and 72 h group, respectively (0.09±0.008 vs 0.04±0.005, 0.03±0.002, 0.04±0.003 respectively, P＜0.01 ). Conclusions AQP2 expression in the renal collecting duct of SD rats is altered over the period exposed to altitude. It is decreased in the early hypoxia period, and is increased in later period. This change may be related to the intensity of hypoxia, which is mediated by a potential adaptation mechanisms against hypoxia caused by high altitude.

Molecular cloning and characterization of hemoglobin alpha and beta chains from plateau pika (Ochotona curzoniae) living at high altitude.

Hemoglobin (Hb) plays an important role in oxygen transfer from lung to tissues. Possession of a Hb with high oxygen affinity helps highland animals to adapt to high altitude, has been studied profoundly. Plateau pika (Ochotona curzoniae), a native species living at 3,000-5,000 m above sea level on Qinghai-Tibet Plateau, is a typical hypoxia and low temperature tolerant mammal. To investigate the possible mechanisms of plateau pika Hb in adaptation to high altitude, the complete cDNA and amino acid sequences of plateau pika hemoglobin alpha and beta chains have been described. Compared with human Hb, alterations in important regions can be noted: alpha111 Ala-->Asn, beta35 Tyr-->Phe, beta112 Cys-->Val, beta115 Ala-->Ser, and beta125 Pro-->Gln. Phylogenetic analysis of alpha and beta chains shows that plateau pika is closer to rabbit than to other species. This study provides essential information for elucidating the possible roles of hemoglobin in adaptation to extremely high altitude in plateau pika.

Molecular cloning of hemoglobin alpha-chain gene from Pantholops hodgsonii, a hypoxic tolerance species.

To investigate the possible mechanisms of high-altitude native animals in adapting to high altitude, we cloned hemoglobin alpha-chain (alpha-chain Hb) gene from Pantholops hodgsonii, an animal species that indigenously lives at elevations of 3700-5500 m on the Qinghai-Tibetan plateau. Using reverse transcription polymerase chain reaction (RT-PCR) technique, the alpha-chain Hb gene was amplified from total RNA in the liver of the Pantholops hodgsonii. TA cloning technique was used and the PCR product was cloned into pGEM-T vector. The DNA sequence of the gene was highly homologous with sheep (99.1%), goat (98.6%), cattle (95.6%) and human (86.5%). The alpha-chain Hb gene encoded a 142-amino acid protein that could be identified with the homology of alpha-chain Hb protein in sheep (98%), goat (96%), cattle (91%) and human (87%). However, 18 alternations were detected when compared with the alpha-chain Hb gene in human, and 2 in sheep. Moreover, the alterations of á117 GluAsp and alpha 132 AsnSer in important regions were noted in human and sheep, respectively. Phylogenetic analysis suggested that the structure of alpha-chain Hb was highly similar to that in sheep. This study provided essential information for elucidating the possible roles of hemoglobin in adapting to extremely high altitude in Pantholops hodgsonii.