Absolute and convective instabilities of natural convection flow in boundary-layer regime

The spatiotemporal instability of the buoyancy-driven flow adjacent to a vertically heated wall, which is immersed in thermally stratified medium, is studied theoretically and numerically. The temperature gradients ratio between the wall and the ambient fluid is shown to lead to rich scenario of absolute-convective instability transitions. The direct numerical simulations consistent with the theoretical prediction are presented. The supercritical steady state, found in previous simulations of the natural convection in vertically heated square cavity, is explained in terms of the convective instability, and the nonlinear effect on the convectively unstable waves is discussed as well.

[Relationship between cholinesterase, prothrombin activity and albumin and the pathology of the liver]

BACKGROUND

To investigate the relationship between serum cholinesterase, albumin and plasma prothrombin activity and the pathology of the liver in patients with viral hepatitis.

METHODS

Totally 135 patients diagnosed as chronic hepatitis, cirrhosis and/or severe hepatitis with needle biopsy of liver were enrolled in this study. Serum cholinesterase and albumin of the patients were detected with enzyme rate method; meanwhile, their plasma prothrombin activity was detected with turbidimetry test.

RESULTS

The percentage of decrease of the level of serum cholinesterase was higher than that of albumin and plasma prothrombin activity in chronic mild and moderate hepatitis; the level of serum cholinesterase, albumin and plasma prothrombin activity decreased gradually followed by the exacerbation of inflammatory reaction (P<0.001) and by the elevation of degree of fibrosis of the liver (P <0.001) their correlation coefficient was 0.720 to 0.778 (P<0.001).

CONCLUSION

The level of serum cholinesterase could better a nd more sensitively reflect the synthetic function and the damage of the pathology of the liver than that of albumin and plasma prothrombin activity could do, they all negatively correlated with the pathology of the liver.

[Study on the expression of endothelial nitric oxide synthase and its mRNA in liver tissues of patients with chronic hepatitis B]

BACKGROUND

To study the expression of endothelial nitric oxide synthase (eNOS) and its mRNA in liver tissues of patients with chronic hepatitis B (CHB) and the relationship between its expression and pathological changes of hepatic tissues and the clinical significance.

METHODS

48 cases of specimens of liver tissues with CHB were observed and analyzed using immunohistochemical method and in situ nucleic acid hybridization.

RESULTS

eNOS was expressed in hepatocytes, sinusiod endothelial cells and vessel endothelial cells, being predominantly expressed in hepatocytes. The number and distribution of eNOS mRNA positive cells were similiar to those of its protein. Increase in expression of eNOS was correlated with degrees of inflammatory activity and fibrosis (r=0.6855 [P<0.05]; r=0.4828 [P<0.05]; respectively), and with decreasing PA and ALB (F=3.4101 [P<0.05]; F=9.1714 [P<0.0]). Changes of expression of TGF-alpha-R were parallel to those of eNOS.

CONCLUSIONS

eNOS may be involved in pathological lesion of CHB by affecting the expression of TGF-R in liver tissues with CHB.

Drosophila Chk2 is required for DNA damage-mediated cell cycle arrest and apoptosis

Chk2 is a major target of ataxia telangiectasia-mutated (ATM) and ATM- and Rad3-related (ATR). Germline mutations in Chk2 have been identified in a subset of patients with Li-Fraumeni syndrome, suggesting that Chk2 is a tumor suppressor gene. To investigate the role of Chk2 in multicellular organisms, a Drosophila chk2 (Dmchk2) mutant was generated. Dmchk2 mutants are viable but show defects in maintaining genome stability and are highly sensitive to ionizing radiation. Interestingly, mutating Dmchk2 completely blocks DNA damage-induced apoptosis and partially blocks DNA damage-induced cell cycle arrest. These results indicate that Chk2 protein plays a crucial role in the DNA damage response pathway mediating cell cycle arrest and apoptosis, and that the ATM-Chk2 pathway is likely conserved in Drosophila.

[Serological and pathological follow-up studies of the patients with single GBV-C/HGV RNA infection]

OBJECTIVE

To elucidate the pathogenicity of GBV-C/HGV in causing viral hepatitis.

METHODS

The sera and bioptic liver tissues, which involved 8 cases of the second liver puncture with an interval of 2 years, from 24 cases of single GBV-C/HGV RNA positive patients were observed for more than 2 years. GBV-C/HGV RNA in the sera and liver tissues was detected by using RT-PCR and in situ hybridization, respectively. Under light and electron microscope, the pathology of the liver tissues was observed.

RESULTS

At the beginning of the observation, the mean serum alanine transaminase(ALT) level was 60.17 IU/ml(range, 42.00-87.00 IU/ml), and the positive rates of anti-E2 antibody and GBV-C/HGV RNA in the sera and NS3 and/or NS5 in the liver tissues were 4.17%, 75.00% and 54.17%, respectively. In all the examined specimens, 79.17% of them showed mild acute or chronic hepatitis, mainly presenting with degeneration of hepatocytes, mild portal inflammation. GBV-C/HGV RNA and its NS3 and/or NS5 antigens were mainly detected in hepatocytes and a few mononuclear cells. In contrast, after more than 2 years, the natural change rate (negative rate of GBV-C/HGV) of 24 cases was 66.67% (P < 0.001). 75.00% had normal ALT level (P < 0.001) and 41.67% of anti-E2 antibody in the patients was positive (P < 0.001). Through histological observation, besides 2 cases of liver tissues showing very mild hydropic degeneration, there were no abnormal findings in 8 cases of the second liver biopsy.

CONCLUSION

GBV-C/HGV could induce mild and self-limited hepatitis, which showed that GBV-C/HGV may be a light and self-limited pathogenic agent to human liver. E2 antibody appearance may indicate a recovery and provide a protection from GBV-C/HGV infection. Whether there is any other recovery marker in serum requires further study.

[The expression of transforming growth factor-beta receptor I and its mRNA in liver tissues of chronic hepatitis B and the clinical significance]

OBJECTIVE

To study the expression of transforming growth factor-beta receptor I (TGF-beta RI) and its mRNA in liver tissues of chronic hepatitis B (CHB) and the relationship between its expression and the pathological injury of hepatic tissues.

METHODS

Forty-eight liver specimens from patients with CHB were observed by techniques of immunohistochemistry and in situ nucleic acid hybridization.

RESULTS

TGF-beta RI was expressed in the hepatocyte, sinusoid endothelial cell and bile duct epithelial cell, with predominance in the hepatocyte and distribution in small granule or cell membrane. Increased expressing of TGF-beta RI was parallel to the degree of inflammatory activity and fibrosis (r=0.7095, P<0.05; r=0.6915, P<0.05; respectively). The number and the distribution of TGF-beta RI mRNA in the positive cells were coincident to those of its protein. The expression of TGF-beta RI was closely correlated with Tbil (r= 0.3396, P<0.05), PA (r= -0.3430, P<0.05) and ALB (r= -0.4173, P<0.01).

CONCLUSION

The TGF-beta RI may involve in the pathological injury of hepatic tissues of CHB.

[Expression of CPP32, Fas and Fas ligand and the relationship between their expression and viral antigens in chronic hepatitis]

OBJECTIVE

To study the significance of Fas-Fas ligand (FasL)-CPP32 mediated hepatocytic apoptosis and the relationship between their expression and hepatitis C virus (HCV) antigens in pathogenesis of chronic hepatitis C (CHC).

METHODS

The expression of Fas and FasL proteins and CPP32 protease and their mRNAs was detected by immunohistochemistry and in situ hybridization respectively. Meanwhile, HCV core protein and nonstructural protein NS(3) and NS(5) were examined on the sequential liver tissue sections from 65 cases of patients with CHC and 5 cases of normal subjects. The positive staining was quantified by image analysis.

RESULTS

In CHC liver tissues, CPP32 protease, Fas and their mRNAs were mainly expressed in the hepatocytes, especially in the HCV core protein-positive hepatocytes and their surroundings, but FasL protein and its mRNA were expressed dominantly in the infiltrating mononuclear cells in the portal area and hepatic sinusoid. According to the increase of histological activity index (HAI) in the CHC liver tissues, the expression of the three proteins (protease) and their mRNAs were upregrulated obviously.

CONCLUSION

The results suggest i) that Fas-FasL-CPP32 system is associated with HAI of CHC, ii) that HCV core antigen may affect the expression of CPP32 and Fas hepatocytes apoptosis.

[Study on relationship between the apoptosis of hepatocytes and liver fibrosis of chronic viral hepatitis]

OBJECTIVE

To study the relationship between apoptosis of hepatocytes and liver fibrosis of chronic viral hepatitis (CH).

METHODS

DNA fragmentation, one of the characteristic features of apoptosis, was detected by in situ terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and the expression of Fas, transforming growth factor beta 1 (TGF-beta 1) and Pre-collagen III peptide (P III P) in liver tissues were detected by immunohistochemistry. Soluble Fas (sFas) and TGF-beta 1 in serum were detected by ELISA.

RESULTS

The damage of DNA in hepatocytes of CH correlated closely with the expression of Fas and TGF-beta 1 in liver tissue and serum (r = 0.6129, 0.5368, 0.5564, 0.5996; P <0.05-0.01). In severe type CH and liver cirrhosis, the degree of liver fibrosis and the expression of P III P and TGF-beta 1 were higher than that in mild type and moderate type CH.

CONCLUSIONS

The sFas in serum may be one of the factors associated with the apoptosis. The apoptosis of hepatocytes correlated with liver fibrosis of CH and TGF-V beta 1 may play an important role between apoptosis and liver fibrosis.

[The study of expression and distribution of PCNA in hypertrophic scar tissue]

OBJECTIVE

To analyze the expression and the distribution of proliferation cell nuclear antigen (PCNA) in hypertrophic scar for identifying its certain characteristics during the fibroblast proliferation.

METHODS

Bioptic samples were taken form 12 cases of hypertrophic scar, 8 cases of matured scars and 20 cases of controlled normal skin. Each sample was immunohistochemically stained and examined with monoclonal antibody[PCNA(pc10)] technique. The level of PCNA expression was decided for evaluation of the fibroblast proliferation.

RESULTS

The level of PCNA in the hypertrophic scar(45.4 +/- 12.3) was significantly higher than mature scar(17.4 +/- 6.2), also normal skin(13.5 +/- 4.1, P < 0.01). But, there was no significant deference between the matured scar and the normal skin. The PCNA intracellular particles may sometimes be bound in the keratinocytes and the fibroblasts of some connective tissue.

CONCLUSION

The fibroblast proliferation in the hypertrophic scar has kept a high level. During the process of hypertrophic scar formation it may play an important role.

Serological and histological findings in infection and transmission of GBV-C/HGV to macaques

Seven healthy macaques were inoculated with the GBV-C/HGV-RNA serum from a non-A-E hepatitis patient. The serology and pathology of the liver in the animals were observed. The results indicated that all inoculated animals were infected with a GBV-C/HGV-RNA viremia and had mildly abnormal alanine transaminase levels during the infectious period. The histology, immuno-histochemistry, and in situ hybridization in the liver tissues of the inoculated animals also showed that there was a very mild hepatitis with the positive antigenic expression and the genome of GBV-C/HGV-NS5 in hepatocytes. The pathological changes in the infected animals appeared to become normal whether or not GBV-C/HGV-RNA viremia persisted. There is a possibility that the mild virulence of the GBV-C/HGV to the host became harmless with time after inoculation. Infection and the transmission of the GBV-C/HGV virus in the macaques provides an appropriate animal model and new information about GBV-C/HGV infection in both humans and animals. It is possible that this virus is a mild and self-limited pathogenic agent to the hepatic cells of primates.

Serological and histological findings in infection and transmission of GBV-C/HGV to macaques

Seven healthy macaques were inoculated with the GBV-C/HGV-RNA serum from a non-A-E hepatitis patient. The serology and pathology of the liver in the animals were observed. The results indicated that all inoculated animals were infected with a GBV-C/HGV-RNA viremia and had mildly abnormal alanine transaminase levels during the infectious period. The histology, immuno-histochemistry, and in situ hybridization in the liver tissues of the inoculated animals also showed that there was a very mild hepatitis with the positive antigenic expression and the genome of GBV-C/HGV-NS5 in hepatocytes. The pathological changes in the infected animals appeared to become normal whether or not GBV-C/HGV-RNA viremia persisted. There is a possibility that the mild virulence of the GBV-C/HGV to the host became harmless with time after inoculation. Infection and the transmission of the GBV-C/HGV virus in the macaques provides an appropriate animal model and new information about GBV-C/HGV infection in both humans and animals. It is possible that this virus is a mild and self-limited pathogenic agent to the hepatic cells of primates.

Transforming growth factor-beta is a potent inhibitor of extracellular matrix degradation by cultured human mesangial cells

Accumulation of the glomerular extracellular matrix (ECM) is a pivotal event in the progression from acute glomerular injury to end-stage renal disease. Although enhanced ECM synthesis has been demonstrated to contribute to ECM accumulation, the role of decreased ECM degradation is largely unknown. It was previously shown that glomerular ECM degradation is mediated by a plasminogen activator (PA)/plasmin/matrix metalloproteinase 2 (MMP-2) cascade. However, little information is available regarding the factors that regulate the activity of this degradative cascade in normal or pathologic states. Transforming growth factor-beta1 (TGF-beta1) is shown here to be a potent inhibitor of ECM degradation by cultured human mesangial cells. Using human mesangial cells grown on thin films of 125I-labeled Matrigel, dose-dependent inhibition of ECM degradation in the presence of TGF-beta1 was observed, reaching >90% inhibition with 0.4 ng/ml TGF-beta1. Addition of anti-TGF-beta antibodies (4 microg/ml) in the absence of exogenous TGF-beta increased ECM degradation (1.8+/-0.2-fold versus controls, P<0.05). In contrast, platelet-derived growth factor, at concentrations up to 10 ng/ml, had no effect on ECM degradation. TGF-beta completely blocked the conversion of plasminogen to plasmin and markedly reduced the conversion of latent MMP-2 to active MMP-2. TGF-beta did not significantly alter the levels of tissue PA, total MMP-2, or tissue inhibitor of metalloproteinase-1, but did increase the levels of PA inhibitor- (1.8-fold, P<0.05), the major physiologic inhibitor of PA. These data document that TGF-beta is a potent inhibitor of ECM degradation by cultured human mesangial cells, and they suggest that decreased mesangial matrix degradation, caused by TGF-beta-mediated decreases in the activity of the PA/plasmin/MMP-2 cascade, may contribute to the glomerular matrix accumulation that occurs in progressive renal disease.

[Effects of inflammatory infiltration on the formation of abdominal aortic aneurysm]

OBJECTIVE

To explore inflammatory infiltration and its effects on the formation of abdominal aortic aneurysm (AAA).

METHODS

Immunohistochemical technique was used to detect lymphocyte (CD45 positive) and macrophage (CD68 positive) infiltration while in situ hybridization was applied to investigate the mRNA expression of Matrix Metalloproteinase-9 (MMP-9) in 20 cases of human AAA and 4 cases of normal human abdominal aortas.

RESULTS

Inflammatory infiltration occurred in every case of AAA with various degree, and there was a parallel tendency between the degree of injury of abdominal aortic elastin and that of inflammatory infiltration in AAA. Inflammatory infiltration was not found in normal aortas. MMP-9 mRNA was detected in macrophages and lymphocytes in all 20 cases, in smooth muscle cells in 13, and not in normal abdominal aortas.

CONCLUSIONS

Inflammatory infiltration attended and enhanced the formation of AAA through a complex of sequence of biochemical, cellular and immune events.

[Relationship between PDGF-A, bFGF and proliferation of smooth muscle cells in vein grafts]

OBJECTIVE

To detect the relationship between platelet-derived growth factor-A (PDGF-A), basic fibroblast growth factor (bFGF), and proliferation of smooth muscle cells in vein grafts.

METHODS

An animal model of autogenous vein graft was established by transplanting internal branch of the jugular vein to the common iliac artery by end-to-end anastomosis. 25 rats were used. The grafted veins were harvested at 6 h, 2 d, 1 w, 2 w and 4 w respectively after the operation. The expression of PDGF-A and bFGF in different stages after grafting procedure was observed immunohistochemically.

RESULTS

The expression of PDGF-A peaked at 1 w, paralleled with proliferation of SMC, and was significantly higher than that at 6 h (P < 0.01). The expression of PDGF-A diminished gradually. At 4 w, it was significantly lower than that at 1 w (P < 0.01). bFGF demonstrated bimodal pattern of the expression: the first peak of expression occurred by 2 d and the second peak by 2 w. The difference was significantly compared with other stages.

CONCLUSIONS

The expression of PDGF-A 1 contributed to migration and proliferation of SMC. Except for contributing to proliferation of SMC, bFGF perhaps took part in endothelization.

[Expression of Bcl-2 and Bax proteins in liver tissues of chronic viral hepatitis]

In order to study the significance of expression of Bcl-1 and Bax proteins in the liver tissues, 35 cases of chronic viral hepatitis (CH) were immunohistochemically studied. The results showed that Bcl-2 and Bax were mainly colocated in cytoplasm of the mononuclear cells(MN) in the areas of focal necrosis, bridging necrosis and piecemeal necrosis (PN). Some hepatocytes surrounding these areas expressed Bcl-2 and Bax or expressed Bax only. Pathological examination found that these hepatocytes Suffered from hydropic or acidophilic degeneration. In the severe viral hepatitis, survival hepatocytes also expressed Bcl-2 and Bax. It is suggested that the expression of Bcl-2 and Bax in the liver tissues correlated with the apoptosis of hepatocytes in CH and influenced the progress of severe viral hepatitis.

[Study on expression of P16 protein in the liver tissue of viral hepatitis]

P16 protein is a cell cycle regulator involved in the genesis of many types of tumors. In order to study the significance and expression of P16 protein in liver tissue of viral hepatitis, 48 patients with viral hepatitis and 7 cases with hepatocarcinoma were investigated by immunohistochemistry. The results showed that the positive rate of P16 protein expressed in the liver tissues of mild (85.0%) and moderate (91.66%) chronic viral hepatitis were significantly higher than that in liver cirrhosis and hepatocarcinoma (P < 0.01, 0.001), this suggest that the expression of P16 plays an important role in the carcinogenesis.