Brain microvascular basement membrane damage and the expression of uPA and uPA mRNA in brain areas after focal cerebral ischemia/reperfusionin renovascular hypertensive stroke-prone rats

AIM:To investigate the effects of lowdosage of nitric oxide synthase(NOS)inhibitor NG-nitro-L-argi ni ne methyl ester(L-NAME)i n two-week treatment on the hyperdynamic circulatory state i n rats withcirrhosis.METHODS:Cirrhosis model was induced in male SDrats by injection of 60%CCl 4 oily sol utionsubcuta-neously.Cirrhotic rats were treated with L-NAME(0.5 mg·kg^-1·d^-1)by gavage for two weeks.Mean arterial pres-sure(MAP), portal pressure(PP), cardiac output(CO), cardiac index(CI), splanchnic vascular resistance(SVR), splanchnic blood flow(SBF)and serumnitrite levels were determi ned in L-NAME-treated, L-NAME-untreatedcirrhotic rats and controls by usi ng57 Co-labled microsphere technique and a fl uorometric assay, respectively.RESULTS:Untreated cirrhotic rats had significantly lower MAP, SVR and higher PP, CO, CI, SBF and nitrite concentra-tion than those of the controls(all, P<0.01).In treated cirrhotic rats, L-NAME significantly attenuated the in-crease of CO, CI, SBF, nitrite concentration and the decrease of MAP and SVR.Intreated cirrhotic rats, L-NAME induced a marked decrease of nitrite concentrationthan untreated cirrhotic rats[(1.471±0.907)μmol/L vs(4.204±1.253)μmol/L, P<0.01].CONCLUSION:The endogenous NO may play animportant role inthe changes of hemodynamics patterni n cirrhosis, and hyperdynamic circulatory state in rats with cirrhosis can be ameliorated by oral two-week administration of lower dose of L-NAME.     

Relationship between matrix metalloproteinase-9 and tissue metalloproteinase inhibitor-1 and carotid atheromatous plaque stability

AIM: To investigate the correlation between matrix metalloproteinase-9 (MMP-9),tissue metalloproteinase inhibitor-1 (TIMP-1),MMP-9/TIMP-1 and carotid atheromatous plaque stability in cerebral infarction patients.METHODS: 80 patients with cerebral infarction were categorized as microemboli-negative group (n=70) and microemboli-positive group (n=10),20 normal human were served as control group.The MMP-9 and TIMP-1 levels in plasma were determined by mean of ELISA in 3 groups.RESULTS: The levels of MMP-9 and TIMP-1 in plasma were significantly higher in cerebral infarction patients than those in control group (P<0.01).The plasma MMP-9 content was positively correlated with TIMP-1 content (r=0.76，P<0.01).The ratio of MMP-9/TIMP-1 increased only in microemboli-positive patients (P<0.01).CONCLUSION: The results indicate that the plasma MMP-9 participates in pathophysiological process of cerebral infarction.The ratio of MMP-9/TIMP-1 shows a close relationship with carotid atheromatous plaque instability.     

Cerebral salt wasting syndrome

There is significant evidence to show that many neurosurgical patients with hyponatremia, who were previously diagnosed with syndrome of inappropriate antidiuretic hormone secretion (SIADH), actually have cerebral salt wasting syndrome (CSWS). The critical difference between SIADH and CSWS is that CSWS involves renal salt loss leading to hyponatremia and volume loss, whereas SIADH is a euvolemic or hypervolemic condition. The primary treatment for CSWS is water and salt replacement. The mechanisms underlying CSWS are not understood but may involve ANP or other natriuretic factors and direct neural influence on renal function.     

Effect of CoQ10 on apoptosis and proliferation of cultured mouse microvascular endothelial cells and it's mechanism

AIM: To study the inhibitory effect of CoQ₁₀ on the apoptosis of microvascular endothelial cells and it's probable mechanism. METHODS: Using serum pharmacology method and cytoflowmetery, the effects of CoQ₁₀ at different concentrations on apoptosis and proliferation in cultured mouse brain microvascular endothelial cells (bEnd.3) were investigated. The expression of Fas protein and Bcl-2 protein were observed with immunocytochemical method (ABC). RESULTS: The cell apoptosis was inhibited significantly in CoQ₁₀ groups (50 μL and 25 μL) in cultured bEnd.3 cells. The results of immunocytochemical staining showed that the expressions of Fas protein was inhibited and Bcl-2 protein was stimulated significantly in CoQ10 group with above concentration. But there was no significant change in cell proliferation. CONCLUSIONS: CoQ₁₀ may inhibit apoptosis of microvascular endothelial cells (bEnd.3) via up-regulation of Bcl-2 and down-regulation of Fas. Authors suggest that this is one of the protection mechanisms of CoQ₁₀ from dysfunction of microvascular endothelial cells.     

Therapeutic action of transplantation of marrow mesenchymal stem cells into infarction area after cerebral middle artery occlusion in rats

AIM: To explore the differentiation and the functional behavior of marrow mesenchymal stem cells (MSC) transplanted into the cerebral infarction area after cerebral middle artery ischemia in rats. METHODS: MSC were isolated from human rib marrow and cultured in L DMEM medium in vitro. The model of rat cerebral infarction by cerebra middle artery occlusion was established, and the identified MSC were transplanted intracerebrally 10 days later. Immunohistochemistry technique was used to identify the cell survivor and its differentiation to the neurogenesis in the transplantation site, and at 2 weeks and 6 weeks after transplantation, the functional tests were comparatively studied. RESULTS: The results showed that the survivor of transplanted MSC was differentiated to neural phenotype cells, and the functional behavior of the injury rats was recovered significantly after MSC transplantation (P<0.05). CONCLUSION: Our data suggest that transplantation of MSC may be a powerful autoplastic therapy for the stroke.     

Effect of endogenous carbon monoxide on intracellular calcium concentration in focal ischemic cerebral tissue in rats

AIM: To study effect of endogenous carbon monoxide on intracellular calcium concentration and explore the mechanism in brain protection of endogenous CO in focal cerebral ischemia in rats. METHODS: SD rats were divided into three groups randomly, which including hemin, ZnPP group and saline group as control. Respectively saline, hemin, ZnPP were injected intra-peritoneally twelve hours before middle cerebral artery was occluded. Twenty four hours after MCAO model was set up, the concentration of carbon monoxide in blood and intracellular calcium in neural cells was examined. RESULTS: Contrast to saline group, the concentration of CO in blood rose up while intracellular calcium in occluded side decreased in hemin group; the concentration of CO in blood went down while intracellular calcium in occluded side rose up in ZnPP group, there was significant difference among them (P<0.05). Hemin and ZnPP had no effect on intracellular calcium in non-occluded sides (P>0.05). CONCLUSIONS: It may be one of mechanisms on brain protection in ischemic cerebral tissue that carbon monoxide affected intracellular calcium concentration of neural cells by regulating Ca²⁺-K⁺ channel on cell membrane as a messenger gaseous molecular and neurotransmitter.     

New strategy of constructing the β2m gene targeting vector

AIM:The purpose of this study was to establish a new strategy for constructing the mouse β₂m gene targeting vector in order to increase the homologous recombination frequency in contrast with our previous one, which was successfully constructed in the normal way.METHODS:A 4.2 kb 3' arm and a 0.8 kb 5' arm were amplified by PCR from the mouse β₂m-pSV2△HXgpt genomic clone. They included the start region and the three exons, which were separated into two parts from exons 2 (the main coding block) for the two arms——5' arm and 3' arm.RESULTS:The two fragments, in reverse orientation to the Neo gene, were cloned into pPNT respectively on either side of Neo. They were identified by PCR, restriction analysis and sequence analysis as well.CONCLUSION:The mouse β₂m gene targenting vector has been cloned successfully.     

Protective effect of ischemic preconditioning on rat brain with ischemia/reperfusion injury

AIM:To study whether ischemic preconditioning(IPC) has a protective effect against ischemia/reperfusion(I/R) injury in brain, and the possible relationship between IPC and the regulating function of microcirculation.METHODS:The I/R models were established both in I/R and IPC groups of Sprague-Dawley rats. Additional procedure was performed of short term cerebral ischemic preconditioning in IPC group 24 hours before I/R. Skull windows were performed through which microcirculation features were measured before ischemia, during ischemia, and reperfusion. Finally, brains were cut into slices and stained with red tetrazoline(TTC).RESULTS:Most TTC stained brains in I/R group presented irregular palely red areas which were few in IPC group. Compared with I/R group, IPC group presented relatively increase in accumulated length of capillaries, mean cerebral microcirculatory perfusion, and microcirculatory velocity in ischemic and reperfusion phase. There was no-reflow phenomenon in I/R group in reperfusion phase, which was substituted by the course of increasing reperfusion in IPC group.CONCLUSIONS:IPC could relieve the reduction of tissue perfusion during ischemia and the no-reflow phenomenon during reperfusion by improving the regulating function of microcirculation, which relatively promote the opening of capillaries and accelerating of microvascular flow, therefore protect brain from I/R injury.     

Recent advances in molecular mechanisms of cerebral ischemic injury

A complex cascade of molecular events is considerd to be initiated following cerebral is chemia, which include release of excitatory amino acid, calcium dyshomeostasis, free radical injury, increased cytokines, caspase activation and altered gene expression. This review provides an overview of molecular mechanisms involved in postischemic neuronal death and analyses the potential for therapeutic intervention.