Hypoxia-induced apoptosis and mitochondrial dysfunction in chondrocytes arising from CREB phosphorylation reduction.

Chondrocytes, which are embedded within the growth-plate or the intervertebral disc, are sensitive to environmental stresses, such as inflammation and hypoxia. However, little is known about the molecular signaling pathways underlying hypoxia-induced mitochondrial dysfunction and apoptosis in chondrocytes. We first examined the apoptosis, caspase-3 activity, and apoptosis-associated markers in human chondrocyte cell line C28/I2 under normoxia or hypoxia. We then investigated mitochondrial dysfunction and the activation of cyclic adenosine monophosphate response element-binding protein (CREB) signaling in the same human chondrocyte cell line. Our results indicated that hypoxia induced apoptosis and reduced CREB phosphorylation in chondrocytes. Upregulated mitochondrial superoxide and reactive oxygen species levels, and reduced mitochondrial membrane potential and complex IV activity were observed in hypoxia-treated C28/I2 cells. In conclusion, the present study confirmed reduced CREB phosphorylation, apoptosis induction, and mitochondrial dysfunction in the hypoxia-treated chondrocyte cells. This implies the key role played by CREB signaling in hypoxia-induced mitochondrial dysfunction and apoptosis in chondrocytes.

Cloning and expression analysis of cysteine protease gene (MwCP) in Agropyron mongolicum Keng.

In this study, a cysteine protease gene (MwCP) from Agropyron mongolicum Keng was isolated using RACE. Sequence analysis indicated that MwCP was 1473 bp, and it contained a 1134-bp open reading frame, which encoded 377 amino acids with a 24-amino acid N-terminal signal peptide. The results indicated that the MwCP protein was a new member of the papain C1A family, and it was predicted to be an extracellular, secretory stable hydrophilic protein. The secondary structure of MwCP was mainly composed of α-helices and random coils, and the space structure primarily contained α-helices, ß-sheets, and ß-turns. Homology analyses showed the 98% homology between MwCP amino acids and a cysteine protease found in Triticum aestivum (GenBank accession No. AAW21813.1). Analysis of mRNA using semi-quantitative RT-PCR indicated that during a 48-h drought stress period, MwCP was expressed during the 4th hour, and the expression level peaked during the 6th hour before declining to the original level. The results revealed that MwCP was involved in drought-resistant physiological processes of A. mongolicum. Moreover, the MwCP expression levels were highest in leaves, intermediate in roots, and lowest in stems.

Regulating effects of insertion direction of matrix attachment regions on transgenic expression in stably transformed Chinese hamster ovary cells.

We investigated the effects of different directions of insertion of matrix attachment region (MAR) sequences on transgenic expression in stably transformed Chinese hamster ovary (CHO) cells. The MAR sequences were inserted in forward or reverse directions into the expression vectors, and transfected into CHO cells. The expression of the chloramphenicol acetyltransferase (CAT) reporter gene and the relative copy numbers of the CAT gene were analyzed. The CAT gene expression levels in the vector with the MAR sequence inserted in the forward or reverse directions increased compared with expression without the MAR sequence. The relative copy numbers of the CAT gene with MAR sequenced vectors inserted in the reverse and forward directions were lower, than in the control group. The direction of insertion of MAR sequences had no significant effect on expression levels. The expression levels were not proportional to the copy numbers of the gene.

Intra-aortic balloon pump treatment for patients with acute anterior wall myocardial infarction after reperfusion therapy.

We evaluated the effects of an intra-aortic balloon pump on hemodynamics, brain natriuretic peptide concentration and cardiac function of patients with acute myocardial infarction, after reperfusion therapy. Sixty-three patients with acute anterior wall ST-elevation myocardial infarction who underwent primary percutaneous coronary intervention were given an intra-aortic balloon pump (32 cases) or not (control group, 31 cases). The mean pulmonary arterial pressure, pulmonary capillary wedge pressure and cardiac index were measured with a Swan-Ganz catheter. The brain natriuretic peptide concentration was detected by immunochemiluminometric assay. Left ventricular end-diastolic diameter and left ventricular ejection fraction were measured by echocardiography. No difference in baseline was observed between the two groups on day 1 in the hospital. On day 5, mean pulmonary artery pressure and pulmonary capillary wedge pressure of patients with the intra-aortic balloon pump were significantly lower, and cardiac index of was higher than that of the controls, whereas no differences in left ventricular end-diastolic diameter or left ventricular ejection fraction were observed between the two groups. On days 5 and 90, the brain natriuretic peptide concentration of the intra-aortic balloon pump patients was lower than that of the controls. On day 90, left ventricular end-diastolic diameter was smaller in the intra-aortic balloon pump patients, but no difference in left ventricular ejection fraction was observed between the two groups. The intra-aortic balloon pump improved the hemodynamic index and cardiac function and decreased brain natriuretic peptide concentration in patients with acute anterior wall ST-elevation myocardial infarction.

Left ventricular posterior wall thickness is an independent risk factor for paroxysmal atrial fibrillation.

BACKGROUND: Atrial fibrillation is the most common significant cardiac arrhythmia in clinical practice, but its risk factors remain to be clarified. We have hypothesized that left ventricular posterior wall thickness is an independent risk factor for paroxysmal atrial fibrillation (PAF). METHODS: A total of 166 consecutive patients with paroxysmal atrial fibrillation were included in this study. Another 166 healthy check-up people, strictly age and sex-matched, were enrolled as controls in the same period. Univariable analysis and multivariable conditional logistic stepwise regression analysis were conducted. Receiver operating characteristic (ROC) curve analysis was performed on those significant indices obtained from the multivariable logistic regression analysis. RESULTS: The multivariable stepwise analysis identified left ventricular posterior wall thickness, left atrial diameter tricuspid insufficiency and residence (countryside) as independent predictors for paroxysmal atrial fibrillation. Receiver operating characteristic curve analysis demonstrated the cutoff values of those risk factors aforementioned. CONCLUSIONS: In this strictly age and sex-matched population-based sample, left ventricular posterior wall thickness, left atrial diameter, tricuspid insufficiency and residence were predictive risks for paroxysmal atrial fibrillation. This study offers novel information therapeutically beyond that provided by traditional clinical atrial fibrillation risk factors.