[Effects of hypoxia on the secretions of proinflammatory cytokines TNF-alpha and IL-6 in macrophages and its mechanism].

AIM: To investigate the effects of hypoxia on the secretions of proinflammatory cytokines TNF-alpha and IL-6 and to inquire into the mechanism. METHODS: Separated mice abdominal macrophages which were identified with non-specific esterase dye method, and created the hypoxic cultured model. The levels of TNF-alpha and IL-6 in the medium were determined by ELISA method. The mRNA expressions of TNF-alpha and IL-6 were measured by RT-PCR method. NF-kappaB activation was assayed by Western blot method. Finaly, we added cortone (5 microg/ml) to the medium, then observed the secretion levels of TNF-alpha and IL-6 during hypoxia. RESULTS: The secretions of TNF-alpha and IL-6 from Mphi exposed to hypoxia for 12 h were increased significantly compared with control (P < 0.01). The expressions of TNF-alpha mRNA and IL-6 mRNA were enhanced obviously contrasted with control (P < 0.01). NF-kappaB activation in Mphi nuclei was raised at 2 h during hypoxia and persisted to 5 h. We added cortone to the medium and found no significant change in secretion of TNF-alpha and IL-6 during hypoxia. CONCLUSION: Hypoxia could activate NF-kappaB and make it shift to nucleus which promoted the transcriptions and expressions of TNF-alpha and IL-6.

[Cloning and sequencing of alpha, beta globin coding genes in Tibetans living at high altitude].

AIM: To explore the molecular biological mechanism of hemoglobin with high oxygen affinity in Tibetans by determining the sequence of globin cDNA in Tibetans living at high altitude. METHODS: Total RNA was isolated from human bone marrow samples of three Tibetans who live in Qinghai-Tibet plateau. cDNA fragments coding for alpha and beta genes of human hemoglobin were obtained through RT-PCR and were ligated to plasmid pGEM-T easy vectors, and then the ligation liquid were transformed to Escherichia coli and cloned and sequenced. Nucleotide sequences were compared with GenBank data by BLAST method. RESULTS: sequence of a globin cDNA in Tibetans were the same with the registering globin genes in the GenBank, and Hb Abruzzo (beta143 (H21), His- > Arg) gene mutation, a high oxygen affinity beta globin mutation, was found in one Tibetan' beta goblin coding gene (CAC- > CGC). CONCLUSION: This hemoglobin gene mutation may be associated with high altitude adaptation of Tibetans living at high altitude.

[Changes in expression of apoptosis correlative proteins and HIF-1 during acute hypoxia and hypoxic preconditioning in cultured cardiomyocyte of rat].

AIM: To investigate the relationship between the hypoxia-inducible factor 1(HIF-1) and apoptosis correlative proteins in the cardiomyocyte during hypoxia. METHODS: Rat cardiomyocytes cultured in vitro were divided into normoxia, hypoxia and hypoxic preconditioning groups. The cardiomyocytes in hypoxic preconditioning group were cultured in 1% O2, 5% CO2, 94% N2 for 5 days, 12 h daily before exposed to 0% O2 hypoxia with the hypoxic group. The protein expression of HIF-1alpha, Bcl-2, P53 and Bax in the cardiomyocytes were analysis with Western blot after 48 h 0% O2 hypoxia. RESULTS: With the increment of HIF-1 expression, the Bcl-2 expression was inhibited, the Bax and P53 expression were increased as well during hypoxia. Hypoxic preconditioning could suppress the HIF-1 expression, meanwhile the Bcl-2 expression was elevated, and the Bax expression was decreased. CONCLUSION: HIF-1 may contribute to the regulation of the cardiomyocyte apoptosis with the Bcl-2 family during hypoxia.