没食子酸对金黄色葡萄球菌抑菌活性及机制研究

以金黄色葡萄球菌为供试菌,利用2,3,5-氯化三苯基四氮唑(TTC)染色,细胞膜渗透性测定,SDS-PAGE蛋白谱变化等方法对没食子酸的抑菌活性及其机制进行研究,进而验证没食子酸的药效作用。实验结果显示,没食子酸对金黄色葡萄球菌作用其抑菌圈直径为13mm;其对金黄色葡萄球菌的最低抑菌浓度为0.01mg.mL-1;当药物作用5h时,实验组的电导率与对照组相比增加了6.38%;大分子的OD值随着作用时间的增加而逐渐增大,当培养至8h时,实验组大分子物质吸光值的变化率达到最大,比对照组增加了74.4%。SDS-PAGE蛋白谱变化实验表明,没食子酸对金黄色葡萄球菌作用20h后,其总蛋白量没有明显变化。上述结果表明,没食子酸对金黄色葡萄球菌有较强的抑菌活性,能影响金黄色葡萄球菌细胞膜的通透性。其抑菌机制是通过破坏细菌细胞膜的完整性来实现的。     

Bacterial cell wall components of Staphylococcus aureus induce endophthalmitis

AIM: To compare the responses of intraocular inflammation induced by heat-inactivated Staphylococcus aureus or its bacterial cell wall components in SD rats. METHODS: The rats were randomly divided into heat-inactivated bacteria (HIB) group (96 rats were injected with 10 μg of HIB), heat-inactivated bacteria fragments (HIBF) group (96 rats were injected with 10 μg of HIBF), peptidoglycan (PGN) group (96 rats were injected with 10 μg of PGN) and control group (96 rats were injected with sterile saline equivalent). At time points of 6 h, 12 h, 24 h, 48 h, 72 h and 5 d after vitreous injection of the pathogens, the ocular inflammation scores were determined under slit lamp microscope. The infiltration of white blood cells were counted in histological sections. The levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and cytokine induced neutrophil chemoattractant-1 (CINC-1) in serum and vitreous body were detected by ELISA, and protein concentration in aqueous humor were also measured. RESULTS: Severe ocular inflammation was observed in the animals of HIB, HIBF and PGN groups 6-72 h after injection. Five days after injection, the endophthalmitis subsided. The peak of intraocular white blood cell infiltration was observed 24 h after exposure to the bacteria and the components in each group and the cell infiltration rapidly declined after 3 days. The concentrations of TNF-α and IL-1β peaked at 24 h in each group, maintained to 48 h, then decreased rapidly, and returned to baseline level after 5 days. The concentration of CINC-1 peaked at 12 h in each group, and maintained to 24 h, then decreased rapidly, and returned to the normal level after 3 days. Significantly higher protein levels in aqueous humor were detected in the experimental groups at all time points as compared to that in control group (P<0.01). CONCLUSION: Staphylococcus aureus cells and its components induce typical experimental endophthalmitis in SD rats. Massive leukocyte infiltration and high levels of TNF-α, IL-1β and CINC-1 are the main pathological features in the experimental model. PGN and the bacterial cell wall fragments induce stronger intraocular inflammations than the whole heat-inactivated S. aureus.     

Effects of IL-6 and IL-1α on the peripheral blood polymorphonuclear neutrophil apoptosis postburn in rats

AIM:To study the effects of IL-6 and IL-1α on the blood polymorphonuclear-neutrophils(PMN) apoptosis postburn.METHODS:Wistar rats inflicted by 30% total body surface area (TBSA) Ⅲ degree scalding were employed as the model. PMN were isolated by density gradient centrifugation using Percoll-hypaque and labeled with TdT-mediated and dUTP nick end labeling (TUNEL) and analyzed by flow cytometric analysis. The intracellular caspase-3 activation and the serum levels of IL-6 and IL-1α were analyzed by fluorometric immunosorbent enzyme assay and enzyme-linked immunosorbent assay, respectively.RESULTS:The serum IL-6 levels (μg/L) in groups of 3, 6, 12, 24 and 48 h postburn (9.14±1.16, 12.49±1.14, 3.01±0.75, 1.41±0.28 and 1.56±0.43 in turn) and IL-1α (ng/L) in groups of 3, 6, 12 h postburn (90.08±8.39, 320.93±14.48 and 47.84±5.19) were much higher than IL-6 (0.24±0.07) and IL-1α (27.65±4.86) in control group (P＜0.05), respectively. The relative proportions of apoptotic PMN(%) in groups postburn were 9.89±2.00, 4.98±1.35, 1.31±0.72, 2.49±1.87 and 6.88±1.13 in turn, which were obviously less than 13.66 ± 3.88 in the control group. The results of intracellular caspase-3 activation in PMN were observed to be consistent with the results of apoptotic PMN analysis in experimental groups.CONCLUSION:IL-6 and IL-1α are the important factors to induce PMN apoptosis delay that occurred obviously postburn. And decrease in the activity of intracellular caspase-3 of PMN may be involved in their mechanisms.     

Effect of pulmonary vascular endothelial cells on the development of acute lung injury in rats

AIM: Effect of endothelial cell on the development of acute lung injury and the prevention of dexamethasone in acute lung injury were observed.METHODS:Rats were divided into three groups:1.Control group.2.LPS group:Venous injection with LPS(5mg/kg body weight),execute respectively at 1 h,2 h,6 h and 24 h after LPS injection. 3.dexamethasone group:intraperitoneal injection with dexamethasone ,1 h before LPS injection,execute after 2 hours after LPS injection.RESULTS: Serum NO,TNF-α levels,lung iNOS activity and lung ICAM-1mRNA expression were increased( P <0.05, P <0.01, vs control group),but serum ACE was decreased( P <0.01).Dexamethasone could improve all the changes above mentioned.CONCLUSION:Endothelial cell played a vital role in the development of acute lung injury and dexamethasone could prevent acute lung injury.     

Effects of burn serum on the membrane of intestinal epithelial cell in rats

AIM:To explore the mechanism and significance of the intestinal epithelial cellular membrane damage following burn serum. METHODS:The intestinal epithelial cell(IEC-6) were cultured. The changes of total membranous phospholipid contents fluidity of the IEC membrane were dynamically examined with fluorescence polarization technique and HPCE. RESULTS:In the early stage after stimulation by 20% burn serum, the membranous fluidity obviously decreased. The total phospholipid contents decreased, the content of PLA₂ markedly increased. CONCLUSION:The serial changes in IEC after burned could result in the damages of IEC membrane structure, the integrity of cell membrane and function.     

Role of 78 kD glucose-regulated protein in the development of liver cirrhosis promoted by intestinal endotoxemia in rats

AIM: To explore the role of 78 kD glucose-regulated protein (GRP78) in the development of liver cirrhosis in rats promoted by intestinal endotoxemia (IETM). METHODS: Fifty-one male Wistar rats were randomly divided into liver cirrhosis groups of 4th-week, 6th-week and 8th-week, and normal control group at the corresponding time points. The rat model of hepatic cirrhosis was induced by employing multiple pathogenic factors to the animals. The liver injury and hepatic fibrosis were observed with the staining of HE and VG, respectively. The expression of GRP78 at the mRNA and protein levels was measured by the methods of RT-PCR and immnunohistochemistry, respectively. The concentrations of alanine aminotransferase(ALT), endotoxin, TNF-α and homocystine (HCY) in plasma, and the content of TNF-α, malondialdehyde(MDA) and PⅢP in liver tissues were detected. RESULTS: As liver cirrhosis developed, the levels of ALT, endotoxin, TNF-α and HCY in plasma, the expression of GRP78 at mRNA and protein, the content of TNF-α, MDA and PⅢP in liver tissues, and the index of liver fibrosis were gradually increased and were significantly higher than those in normal control group (P<0.05). Elevated endotoxin in plasma was correlated positively with the protein expression of GRP78, the content of MDA and HCY in plasma and the index of liver fibrosis (P<0.01). Elevated protein expression of GRP78 was correlated positively with the content of MDA and HCY in plasma and the index of liver fibrosis (P<0.01). CONCLUSION: GRP78 plays an important role in the development of liver cirrhosis. Endoplasmic reticulum stress is a possible mechanism in the development of liver cirrhosis promoted by IETM.     

Changes in myocardial mitochondrial Ca2＋ concentration and its mechanism in the early stage of severe burn

AIM:To investigate the change in myocardial mitochondrial Ca^2＋ concentration ( [Ca²⁺]_m) and its mechanism in the early stage of severe burn. METHODS:An experimental model of 30%TBSA full-thickness skin scalding was reproduced in rats. [Ca²⁺]_m, cytosolic Ca^2＋ concentration ( _c) and mitochondrial Ca^2＋ transport velocity were determined. RESULTS: ① [Ca²⁺]_m increased evidently at 1st hour postburn, and continuously at 3rd hour, reached the peak at 6th hour postburn, then, it decreased at 12th and 24th hour, but remained in higher level than that of the control. ② There was no significant difference in _c between 1st hour postburn and the control, but _c increased evidently at 3rd, 6th, 12th, 24th hour postburn. ③ mitochondrial Ca^2＋ uptake velocity at 1st hour postburn was higher than that of control, and Ca^2＋ release velocity didn't change obviously, but both of them were decreased at 3rd, 6th, 12th, 24th hour postburn. ④ [Ca²⁺]_m was positive correlated with _c after burn, and negative correlated with mitochondrial Ca^2＋ release velocity at 3rd, 6th, 12th, 24th hour postburn, respectively. CONCLUSION: There was obvious Ca^2＋ overload in myocardial mitochondria after severe burn, the mechanism of which might include ascent of _c and disorder of Ca^2＋ transport in mitochondria.     

Effect of intervention for mast cell function before reperfusion on intestinal ischemia-reperfusion-induced early liver injury in rats

AIM：To explore the effect of intervention for mast cell function before reperfusion on intestinal ischemia-reperfusion (IR)-induced early liver injury. METHODS：Adult SD rats (n=35) were randomized into 5 groups with 7 rats each: sham operation group (S group), IR group, cromolyn sodium treatment group (IR+C group, 25 mg/kg), ketotifen treatment group (IR+K group, 1 mg/kg), compound 48/80 treatment group (IR+CP group, 0.75 mg/kg). IR was induced by superior mesenteric artery occlusion for 75 min followed by 4 h of reperfusion. The agents were intravenously administered 5 min before reperfusion. The serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and histamine, and the liver levels of lactate dehydrogenase (LDH), tumor necrosis factor α (TNF-α), interleukin-8 (IL-8), malondialdehyde (MDA) and superoxide dismutase (SOD) were assessed. The liver histopathologic changes were also evaluated. RESULTS：IR resulted in severe liver injury as demonstrated by great increases in injury scores, concomitant significant increases in serum levels of AST, ALT and histamine, and liver levels of LDH, TNF-α, IL-8, and MDA, accompanied by reduced SOD activity (all P<0.05 vs S group). Treatment with cromolyn sodium or ketotifen markedly alleviated IR-mediated liver injury as confirmed by significant reduction of the above biomedical changes, whereas compound 48/80 further aggravated liver injury by dramatically enhancing the biomedical changes (all P<0.05 vs IR group). CONCLUSION：Inhibition of mast cell function before reperfusion may reduce early liver injury induced by intestinal ischemia reperfusion. Histamine, oxidative stress and inflammatory response may provide promising effects on it.     

Involvement of mtNOS in the Ca2+-induced damages of myocardial mitochondria during the early stage after severe burns

AIM:To study the role of mitochondrial nitric oxide synthase (mtNOS) in the damages of myocardial mitochondria during the early stage after severe burns.METHODS:An experimental model of 30% TBSA full-thickness skin scalding was reproduced in rats. Myocardial mitochondria were isolated from control and burned rats at 1, 3, 6, 12 and 24 h postburn. The mitochondrial respiratory function, content of mitochondrial calcium( [Ca²⁺]_m) and activities of mtNOS and cytochrome c oxidase were determined. RESULTS: (1) Myocardial mitochondrial respiratory control rate(RCR) at 1 h was evidently higher than that of control, but at 3, 6, 12 and 24 h postburn, it was significantly lower than that of the control. The changes in ST₃ is parallel to those of RCR, and ST₄ was evidently increased only at 3 h postburn. (2) [Ca²⁺]_m was higher at all time points postburn and the activity of mtNOS was higher significantly only at 3, 6, 12 and 24 h than that of the control. The activity of cytochrome c oxidase at the 3, 6, 12 and 24 h was low comparing to the control. (3) After severe burns, RCR was negatively correlated with mtNOS activity(r=0.9347, P＜0.05) and mtNOS activity was positive correlated with [Ca²⁺]_m (r=0.8945, P＜0.05). CONCLUSION:The elevation of [Ca²⁺]_m significantly activates mtNOS, which might play an important role in the damages of myocardial mitochondria during the early stage after burn injury.     

The potential role of neurotrophic factor in the pathogenesis and therapy of Parkinson's disease

Parkinson’s disease is characterized by degeneration and dysfunction of dopaminergic neurons in the mid-brain substantia nigra, neurons that project to the caudate putamen. The clinical symptoms are caused by the loss of dopamine and the consequent dysfunction of the nigrostriatal pathway. Neurotrophic factors that may prevent nigrostriatal degeneration by improving the function of remaining dopaminergic neurons has the potential to be a useful therapy for Parkinson’s disease. Neurotrophic factors and their specific receptors could play an important role in the progress of Parkinson’s disease. The neuroprotective effects of neurotrophic factors GDNF, BDNF, IL-6 on dopaminergic neurons in vivo and in vitro, and the potential therapeutic use in treating Parkinson’s disease were discussed in this paper.     

The role of C-type natriuretic peptide in balloon injury of rat aorta

AIM and METHODS: In a model of balloon injury of rat aorta, the dynamic changes of C-type natriuretic peptide (CNP) in plasma and aortic tissues and the effect of exogenous CNP on intima/media (I/M) ratios were studied. RESULTS:CNP levels in plasma were significantly increased by 80.7% (P＜0.01),43.5%(P＜0.05) and 27.5% (P＜0.05) on 3 days, 10 days and 21 days after balloon injury, but its levels in aortic tissues were decreased by 46.6% (P＜0.05) on day 3 and increased by 2.8 (P＜0.01),1.6(P＜0.05) and 0.82-fold (P＜0.05) on day 10, day 21 and day 28 after balloon injury of rat aorta. Result also showed that the administration of CNP i.p. inhibited neointima formation. I/M ratios were decreased by 23% (P＜0.05) and 20% (P＜0.05) on 7 days, 21 days after balloon injury of rat aorta.CONCLUSION:CNP might be involved in the process of recovery after vascular endothelium-denudation and exogenous CNP suppress the neointima formation.     

Changes in action potential and the conduction time of ventricular cells in subendocardium and subepicardium during ischemia and early reperfusion

AIM:To investigate the electrophysiological characteristics of ventricular myocyte both in subendocardium and in subepicardium during ischemia. METHODS:Using modified Ferrier's method of ischemic and reperfusion injury in isolated guinea pig right ventricular wall. RESULTS: The transmembranal electric activities in subendocardium and in subepicardium were all significantly abnormal, and it was more significant in subendocardium. CONCLUSION: The alteration degree of ventricular myocyte in subendocardium and in subepicardium during ischemia and early reperfusion was different, and this might be the electrophysiological basis of the vulnerability of the subendocardium.     

Abnormal expression of angiopoietins in glomerulus following podocyte injury and its role in the development of progressive glomerulosclerosis in rats

AIM: To study the potential pathological role of abnormal expression of endogenous angiopoietins in progressive glomerulosclerosis. METHODS: 80 male Wistar rats were randomly allocated into sham operation group (sham, n=25), unilateral nephrectomy group (UNx, n=25) and UNx＋daunorubicin (DRB)group (n=30). The rats in DRB group were intravenously injected with DRB (5 mg/kg) on the seventh and the fourteenth day respectively after excising one kidney. Then, at week 1, 2, 4, 6 and 8, 5, male Wistar rats from each group were taken randomly for determining 24 h urinary protein quantitative measurement (24hUPQ), BUN, Scr, and the kidneys were examined by electronic microscope, PAS staining, immunohistochemical staining and in situ hybridization histochemistry. RESULTS: There was a trend towards an increase respectively in levels of 24hUPQ, Bun, Scr, GSI in DRB from week 2 to week 8. Electronic microscope revealed that podocyte injury presented in DRB group. Expression of Ang1 mRNA and protein in glomerulus in DRB group decreased, while expression of Ang2 protein in glomeruli in DRB group increased. In DRB group, expression of Ang1 protein had a negative correlation with 24hUPQ, BUN, Scr, GSI, expression of Ang2 protein and CoIV protein. Expression of Ang2 protein had a positive correlation with 24hUPQ, BUN, Scr, GSI,expression of CoIV protein. CONCLUSION: Podocyte injury may lead to glomeruli abnormally express angiopoietins. A decrease in expression of Ang1, and upregulation in expression of Ang2 may facilitate progressive glomerulosclerosis in the rat.     

Effect of propolis on the expression of CD54 and activation of NF-κB p65 of lung tissue in acute lung injury rats

AIM: To study the effect of propolis on the expression of CD54 and activation of NF-κB p65 in lung tissue of acute lung injury (ALI) rats. METHODS: 40 male Wistar rats were divided into 5 groups: normal control, model control, dectancyl group, water soluble derivative of propolis (WSP) group and ethanol extracted propolis (EEP) group. ALI animal model was performed by oleic acid and LPS twice attack. The pathologic slice was observed with light microscope and the NF-κB p65 activity and CD54 expression were tested by immunohistochemistry (SABC and SP). RESULTS: Both EEP and WSP antagonized the lung edema, decreased the inflammation and inhibited the expression of CD54 and activation of NF-κB p65. CONCLUSION: The increase in the expression of CD54 and the activation of NF-κB p65 in the lung tissues of ALI were involved in the formation of ALI. Propolis ameliorated the lung damage, which maybe related to the inhibition of CD54 expression and NF-κB p65 activation.     

The role of ATP- sensitive K+ channels in the cardiovascular system

15 years ago, Noma first applicated the patch clamp technique to CN-treated mamammalian heart cells, e-vealed specific K⁺ channels which were depressed by intracellular ATP at level greater than 1 mNl.He suggested the ATP-sensitive channels are important for regulating cellular energy metabolism in the control of membrane exitability. Recent studies supported the hypothesis and suggested that ATP- sensitive channels play an important role in hypoxia, myocardial ischemia/reperfusion and is chemic preconditioning     

The effect of partial liquid ventilation on the ultrastructure of pulmonary surfactant system in endotoxin-induced acute lung injury in rats

AIM: To study the effect of partial liquid ventilation on the ultrastructure of pulmonary surfactant(PS) system in endotoxin-induced acute lung injury. METHODS: The effect of partial liquid ventilation on the ultrastructure of PS system in endotoxin-induced acute lung injury was observed with electronmicroscope histochemistry. RESULTS: There was ultrastructure impairment of PS system in endotoxin-induced acute lung injury, the pulmonary surfactant layer was discontinuous, lamellar bodies and plasmosomes in type Ⅱ pneumonocytes vacuolated, and a few of them were even necrotized and disrupted into the alveolar space. The pulmonary surfactant layer was still continuous, the vacuolation of lamellar bodies and plasmosomes in type Ⅱ pneumonocytes was little with partial liquid ventilation. CONCLUSION: Partial liquid ventilation can lessen the impairment of PS system in endotoxin-induced acute lung injury in rats.     

The role of urban habitats in the abundance of red squirrels (Sciurus vulgaris,L.) in Finland

Because the amount of urban areas has increased, it is important to investigate the abundance of wildlife species in relation to urban environments. Analyzing the impact of urbanization on the presence of forest-dwelling mammals is of interest due to the possible effects of urbanization on human-wildlife relationships and urban biodiversity. The Eurasian red squirrel (Sciurus vulgaris) is a declining forest species, and its occurrence in urban environments has been inadequately studied. The loss and fragmentation of forests due to urbanization may be detrimental for squirrels, whereas the abundant and predictable food resources and the low number of natural predators in urban areas may encourage squirrels to invade towns. We used large-scale data collected by volunteer bird watchers along a 950 km south-north gradient to study whether the winter abundance of squirrels in Finland is dependent on urbanization, while controlling for effects of habitat type, food abundance (spruce cone crop; number of winter feeding sites), predator abundance (northern goshawk, Accipiter gentilis; feral cat Felis catus), season and latitude. We found that squirrel abundance increased with human population density, number of feeding sites and spruce cone crop and decreased with latitude and season. Feral cats showed weak negative connection with squirrel numbers, but there were no effect of goshawks. Relative squirrel abundance was approximately twice as high in urban habitats than in forests. Artificial feeding rather than a low number of predators may attract squirrels in urban environments. Planting spruce trees in urban environments will also benefit squirrels. Our results indicate that urban areas are an important habitat for the red squirrel even along the northern edge of their distribution range, where natural forest areas are still widespread. We conclude also that a citizen science −based bird survey protocol associated with mammal surveys seems to be a good large-scale monitoring method to study the urbanization of squirrels.     

The role of green roofs in mitigating Urban Heat Island effects in the metropolitan area of Adelaide,South Australia

Changing an urban environment and replacing vegetated surfaces with low albedo materials is one of the reasons for increasing temperatures in an urban environment and consequently also one of the key causes of urban heat island effects. In this study, an experimental investigation at the micro-scale and also a numerical simulation at the macro-scale of a typical urban environment in Adelaide were conducted to estimate the potential for mitigating the UHI effect. The results showed that existing low albedo materials such as asphalt, metal roofs and brick pavements contribute to the heat island potential. Also, urban development and a lack of natural vegetation contribute to increased temperatures in cities. The ability of two types of extensive and intensive green roofs to reduce the surrounding micro-climate temperature were monitored. The results showed that they have significant cooling effects in summer time and could behave as an insulation layer to keep buildings warmer in the winter. Furthermore, different scenarios of adding green roofs to the Adelaide urban environment were investigated using the Envi–MET model. The scenario modelling of adding green roofs in a typical urban area in Adelaide, Australia, supported the hypothesis that this can lead to reductions in energy consumption in the Adelaide urban environment. Also an increased use of other water sensitive urban design technologies such as green walls and street trees together with the adoption of high albedo materials is recommended for achieving the optimum efficiency in terms of reducing urban temperatures and mitigating urban heat island effects.