Evolution of Staircase Structures in Diffusive Convection.

Diffusive convection (DC) occurs when the vertical stratified density is controlled by two opposing scalar gradients that have distinctly different molecular diffusivities, and the larger- and smaller- diffusivity scalar gradients have negative and positive contributions for the density distribution, respectively. The DC occurs in many natural processes and engineering applications, for example, oceanography, astrophysics and metallurgy. In oceans, one of the most remarkable features of DC is that the vertical temperature and salinity profiles are staircase-like structure, composed of consecutive steps with thick homogeneous convecting layers and relatively thin and high-gradient interfaces. The DC staircases have been observed in many oceans, especially in the Arctic and Antarctic Oceans, and play an important role on the ocean circulation and climatic change. In the Arctic Ocean, there exist basin-wide and persistent DC staircases in the upper and deep oceans. The DC process has an important effect on diapycnal mixing in the upper ocean and may significantly influence the surface ice-melting. Compared to the limitations of field observations, laboratory experiment shows its unique advantage to effectively examine the dynamic and thermodynamic processes in DC, because the boundary conditions and the controlled parameters can be strictly adjusted. Here, a detailed protocol is described to simulate the evolution process of DC staircase structure, including its generation, development and disappearance, in a rectangular tank filled with stratified saline water. The experimental setup, evolution process, data analysis, and discussion of results are described in detail.

Relationship between lipoprotein lipase gene polymorphism and hemorrhagic stroke in a Chinese population.

OBJECTIVE: To investigate the relationship between lipoprotein lipase (LPL) gene polymorphism and cerebral hemorrhage in a Chinese population. METHOD: This study was based on the case-control study, PCR-RELP and sequencing method were utilized for genotyping. LPL gene Hind III polymorphism was detected both in 300 patients with cerebral hemorrhage (CH group) and in 300 healthy control subjects (control group). Blood lipid level and blood glucose were detected at the same time. RESULT: Our results showed that G allele frequency was significant lower in the CH group than that in the control group (OR=0.611; 95% CI: 0.427-0.876, P=0.001). We also found both GG (OR=0.543, 95% CI: 0.233-0.988; P=0.041) and TG (OR=0.609, 95% CI: 0.387-0.959, P=0.032) genotype were frequent in the control group than that in the CH group. TG level of the groups who carry TT genotype were much higher than that of the groups carrying TG+GG genotype (P<0.05). By means of adjusting age, hypertension and hyperglycemia, logistic multivariate regression analysis revealed that LPL Hind III G allele might be a protective factor (OR=0.601, 95% CI: 0.231-0.876; P=0.001) in the present study. CONCLUSION: It is suggested that LPL Hind III G allelic mutation might be a protective factor against cerebral hemorrhage disease in Chinese population.

Plasma levels of copeptin predict 1-year mortality in patients with acute ischemic stroke.

To evaluate the association between plasma levels of copeptin and 1-year mortality in a cohort of Chinese patients with acute ischemic stroke. We prospectively studied 275 patients with ischemic stroke who were admitted within 24 h after the onset of symptoms. Copeptin and NIH stroke scale (NIHSS) score were measured at the time of admission. The prognostic value of copeptin to predict mortality within 1 year was compared with the NIHSS score and other known outcome predictors. Nonsurvivors had significantly higher copeptin levels on admission compared with survivors (P<0.0001). Multivariate logistic regression analysis showed that elevated plasma levels of copeptin were an independent stroke mortality predictor, with an adjusted odds ratio of 4.48 [95% confidence interval (CI), 2.18-9.06]. The area under the receiver operating characteristic curve of copeptin was 0.882 (95% CI, 0.847-0.921) for stroke mortality, which yielded a sensitivity of 90.7% and a specificity of 84.5%. Copeptin improved the NIHSS score (area under the curve of the combined model, 0.94; 95% CI, 0.91-0.97; P=0.011). Elevated plasma copeptin levels at admission were an independent predictor of long-term mortality after ischemic stroke in a Chinese sample, suggesting that these alterations might play a role in the pathophysiology of stroke.

Effect of oxytocin on the behavioral activity in the behavioral despair depression rat model.

Oxytocin (OXT), a nonapeptide posterior hormone of the pituitary, is mainly synthesized and secreted in the hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON). The present study was to investigate in which level, brain or periphery, OXT effecting on the behavioral activity in the behavioral despair depression rat model. The results showed that (1) either the forced swimming or the tail suspension significantly increased OXT concentration in the brain (PVN, SON, frontal cortex, hippocampus, amygdala, lumbar spinal cord) and in the periphery (posterior pituitary and serum); (2) intraventricular injection (icv) of OXT decreased the animal immobility time, whereas OXT receptor antagonist-desGly-NH2, d(CH2)5[D-Tyr2, Thr-sup-4]OV (icv) increased the animal immobility time in a dose-dependent manner in forced swimming test (FST) and in tail suspension test (TST); (3) neither OXT nor OXT receptor antagonist (intravenous injection) influenced the animal immobility time in FST and in TST. OXT levels were increased in several areas of the brain and in the periphery following the behavioral despair, one stressor, yet pre-treatment with OXT appeared to be beneficial in term of reducing immobility time. The data suggested that behavioral despair could enhance OXT synthesis and secretion not only in the brain but also in the periphery, and OXT in the brain rather than the periphery played a role in the behavioral despair depression.