In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measuremen...In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were performed.Two projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 g.The onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and analysed.Uniaxial compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching process.During the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant grain.The calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were observed.The dynamic mechanical response process of the dummy propellant grain was analysed in detail.The results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.展开更多
Thalamic hemorrhage can lead to the development of central post-stroke pain.Changes in histone acetylation levels,which are regulated by histone deacetylases,affect the excitability of neurons surrounding the hemorrha...Thalamic hemorrhage can lead to the development of central post-stroke pain.Changes in histone acetylation levels,which are regulated by histone deacetylases,affect the excitability of neurons surrounding the hemorrhagic area.However,the regulato ry mechanism of histone deacetylases in central post-stroke pain remains unclea r.Here,we show that iron overload leads to an increase in histone deacetylase 2expression in damaged ventral posterolateral nucleus neurons.Inhibiting this increase restored histone H3 acetylation in the Kcna2 promoter region of the voltage-dependent potassium(Kv)channel subunit gene in a rat model of central post-stroke pain,thereby increasing Kcna2expression and relieving central pain.However,in the absence of nerve injury,increasing histone deacetylase 2 expression decreased Kcna2expression,decreased Kv current,increased the excitability of neurons in the ventral posterolateral nucleus area,and led to neuropathic pain symptoms.Moreover,treatment with the iron chelator deferiprone effectively reduced iron overload in the ventral posterolateral nucleus after intracerebral hemorrhage,reversed histone deacetylase 2 upregulation and Kv1.2 downregulation,and alleviated mechanical hypersensitivity in central post-stroke pain rats.These results suggest that histone deacetylase 2 upregulation and Kv1.2 downregulation,mediated by iron overload,are important factors in central post-stroke pain pathogenesis and co uld se rve as new to rgets for central poststroke pain treatment.展开更多
β-Sitosterol is a type of phytosterol that occurs naturally in plants.Previous studies have shown that it has anti-oxidant,anti-hyperlipidemic,anti-inflammatory,immunomodulatory,and anti-tumor effects,but it is unkno...β-Sitosterol is a type of phytosterol that occurs naturally in plants.Previous studies have shown that it has anti-oxidant,anti-hyperlipidemic,anti-inflammatory,immunomodulatory,and anti-tumor effects,but it is unknown whetherβ-sitosterol treatment reduces the effects of ischemic stroke.Here we found that,in a mouse model of ischemic stroke induced by middle cerebral artery occlusion,β-sitosterol reduced the volume of cerebral infarction and brain edema,reduced neuronal apoptosis in brain tissue,and alleviated neurological dysfunction;moreover,β-sitosterol increased the activity of oxygen-and glucose-deprived cerebral cortex neurons and reduced apoptosis.Further investigation showed that the neuroprotective effects ofβ-sitosterol may be related to inhibition of endoplasmic reticulum stress caused by intracellular cholesterol accumulation after ischemic stroke.In addition,β-sitosterol showed high affinity for NPC1L1,a key transporter of cholesterol,and antagonized its activity.In conclusion,β-sitosterol may help treat ischemic stroke by inhibiting neuronal intracellular cholesterol overload/endoplasmic reticulum stress/apoptosis signaling pathways.展开更多
Anti-jamming solutions based on antenna arrays enhance the anti-jamming ability and the robustness of global navigation satellite system(GNSS)receiver remarkably.However,the performance of the receiver will deteriorat...Anti-jamming solutions based on antenna arrays enhance the anti-jamming ability and the robustness of global navigation satellite system(GNSS)receiver remarkably.However,the performance of the receiver will deteriorate significantly in the overloaded interferences scenario.We define the overloaded interferences scenario as where the number of interferences is more than or equal to the number of antenna arrays elements.In this paper,the effect mechanism of interferences with different incident directions is found by studying the anti-jamming performance of the adaptive space filter.The theoretical analysis and conclusions,which are first validated through numerical examples,reveal the relationships between the optimal weight vector and the eigenvectors of the input signal autocorrelation matrix,the relationships between the interference cancellation ratio(ICR),the signal to interference and noise power ratio(SINR)of the adaptive space filter output and the number of interferences,the eigenvalues of the input signal autocorrelation matrix.In addition,two simulation experiments are utilized to further corroborate the theoretical findings through soft anti-jamming receiver.The simulation results match well with the theoretical analysis results,thus validating the effect mechanism of overloaded interferences.The simulation results show that,for a four elements circular array,the performance difference is up to 19 dB with different incident directions of interferences.Anti-jamming performance evaluation and jamming deployment optimization can obtain more accurate and efficient results by using the conclusions.展开更多
Dynamic tensile failure is a common phenomenon in deep rock practices,and thus accurately evaluating the dynamic tensile responses of rocks under triaxial pressures is of great significance.The Brazilian disc(BD)test ...Dynamic tensile failure is a common phenomenon in deep rock practices,and thus accurately evaluating the dynamic tensile responses of rocks under triaxial pressures is of great significance.The Brazilian disc(BD)test is the suggested method by the International Society for Rock Mechanics and Rock Engineering(ISRM)for measuring both the static and dynamic tensile strengths of rock-like materials.However,due to the overload phenomenon and the complex preloading conditions,the dynamic tensile strengths of rocks measured by the BD tests tend to be overestimated.To address this issue,the dynamic BD tensile strength(BTS)of Fangshan marble(FM)under different preloading conditions were measured through a triaxial split Hopkinson pressure bar(SHPB).The fracture onset in BD specimen was captured through a strain gage around the disc center.The discrepancy between the traditional tensile strength(TTS,determined by the peak load P_(f) of the BD specimen)and the nominal tensile strength(NTS,obtained from the load P_(i) when the diametral fracture commences in the tested BD specimen)was applied to quantitatively evaluating the overload phenomenon.The Griffith criterion was used to rectify the calculation of the tensile stress at the disc center under triaxial stress states.The results demonstrate that the overload ratio(s)increases with the loading rate(σ)and decreases with the hydrostatic pressure(σ_(s)).The TTS corrected by the Griffith criterion is independent of theσ_(s)due to the overload phenomenon,while the NTS corrected by the Griffith criterion is sensitive to both the andσ.Therefore,it is essential to modify the tensile stress in dynamic confined BD tests using both the overload correction and the Griffith criterion rectification to obtain the accurate dynamic BTS of rocks.展开更多
Background:It is known to all that iron overload is a fatal adverse effect on cells and tissue.Herein,our study aimed to investigate the effects of curcumin on iron-overloaded stress in macrophages.Methods:Ferric ammo...Background:It is known to all that iron overload is a fatal adverse effect on cells and tissue.Herein,our study aimed to investigate the effects of curcumin on iron-overloaded stress in macrophages.Methods:Ferric ammonium citrate was added to the macrophage cell line(RAW264.7)to establish an iron-overloaded macrophage model.Cell counting kit 8 assay was used to detect cell viability.Superoxide dismutase,reactive oxygen species,malondialdehyde,and apoptosis were performed to analyze the severity of cellular oxidative damage.In addition,quantitative real-time polymerase chain reaction and western blot were used to detect the expression of nuclear factor erythroid 2-related factor 2.Results:The result showed that iron overload of macrophage was visualized by incubating in 40μM ferric ammonium citrate for 24 h.The curcumin significantly reversed the iron overload-induced apoptotic cells at low(10μM)and middle(20μM)concentrations.Additionally,the levels of malondialdehyde and reactive oxygen species activity in the groups of curcumin at low(10μM)and middle(20μM)concentrations were significantly decreased,while superoxide dismutase activity was obviously increased compared with that of the ferric ammonium citrate group alone.Finally,we found that low(10μM)and middle(20μM)dose curcumin up-regulated nuclear factor erythroid 2-related factor 2 expression at mRNA and protein levels compared with the ferric ammonium citrate group alone.Conclusion:Curcumin reduces iron-overloaded stress in macrophages by activating nuclear factor erythroid 2-related factor 2 and enhancing the superoxide dismutase activity,thereby protecting cell apoptosis.展开更多
The ability of a pavement structure in carrying out its function reduces in line with the increase of traffic load, especially if there are overloaded heavy vehicle passing through the road. This study was done to kno...The ability of a pavement structure in carrying out its function reduces in line with the increase of traffic load, especially if there are overloaded heavy vehicle passing through the road. This study was done to know the effect of overloading vehicles on the road pavement and remaining service life of the pavement. In this study, the service life of pavement due to overloaded vehicles was analyzed using the AASHTO 1993. In Narayanghat-Mugling road the composition of traffic seems to be 83.76% heavy vehicles, 9.18% medium vehicle and 7.05% light vehicle. For the direction of Narayanghat-Mugling, the pavement service life might be reduced by 59.90% due to overloading condition, while for the opposite direction, the service life would not reduced caused by the same factor. The impact of overload conditions on the road pavement showed premature failure;that is, a condition which the damage reduced the life of roads before the design life of the road is reached. From the results, it can be concluded that overloaded vehicles on the road are very influential to the reduction in pavement service life. Therefore, it is expected that road users to comply with existing regulations in the conduct of transportation. As overloading is increasing, it has to be controlled by rules and regulations with penalty to control the overloading. So fines must be associated with intensified enforcement when considered in further strategy. Regular monitoring, inspection and enforcement are the effective ways to control overloading. Use of technology (Automatic overloading information system) may be the effective way to control the overloading.展开更多
The study of the deflection due to the passage of an axle on a pavement structure has the advantage to make possible to pronounce on the portance, the rigidity and the homogeneity of this one. In the case where the al...The study of the deflection due to the passage of an axle on a pavement structure has the advantage to make possible to pronounce on the portance, the rigidity and the homogeneity of this one. In the case where the allowed axle load is not respected, surface deflection leads to premature deterioration of the roadway. In order to study the evolution of these deformations, deflection measurements were made by using the Benkelman method in the Fatick-Kaolack road in Senegal by varying the axle load with the following values: 10, 13 and 16 tons on three different zones. The results show a linear evolution of the deflection as a function of the axle load. Also, the impact of truck overloading was studied by considering different values of the axle load with comparison to the allowed axle load by using frequent types of vehicle. A numerical simulation of the Cast3M pavement was done first, in the case of an isolated single wheel with a radius of 12.5 cm, then in the case of an equivalent dual wheel with a radius of 18.1 cm for loads of 10 to 19 tons. In the same way, the pavement design software (ALIZE) is used to analyse the variation of the axle load. The results show a linear evolution of the deflection, which corroborates the measurements made in the field and those obtained by Samb (2014) with a slope coefficient equal to 1.7. Nevertheless, the case of an isolated single wheel of 12.5 cm radius is closest to the measurements with a straight line of slope coefficient equal to 1.9.展开更多
BACKGROUND: The liver, as the main iron storage compartment and the place of hepcidin synthesis, is the central organ involved in maintaining iron homeostasis in the body. Excessive accumulation of iron is an importan...BACKGROUND: The liver, as the main iron storage compartment and the place of hepcidin synthesis, is the central organ involved in maintaining iron homeostasis in the body. Excessive accumulation of iron is an important risk factor in liver disease progression to cirrhosis and hepatocellular carcinoma.Here, we review the literature on the molecular pathogenesis of iron overload and its clinical consequences in chronic liver diseases.DATA SOURCES: Pub Med was searched for English-language articles on molecular genesis of primary and secondary iron overload, as well as on their association with liver disease progression. We have also included literature on adjuvant therapeutic interventions aiming to alleviate detrimental effects of excessive body iron load in liver cirrhosis.RESULTS: Excess of free, unbound iron induces oxidative stress, increases cell sensitivity to other detrimental factors,and can directly affect cellular signaling pathways, resulting in accelerated liver disease progression. Diagnosis of liver cirrhosis is, in turn, often associated with the identification of a pathological accumulation of iron, even in the absence of genetic background of hereditary hemochromatosis. Iron depletion and adjuvant therapy with antioxidants are shown to cause significant improvement of liver functions in patients with iron overload. Phlebotomy can have beneficial effects on liver histology in patients with excessive iron accumulation combined with compensated liver cirrhosis of different etiology.CONCLUSION: Excessive accumulation of body iron in liver cirrhosis is an important predictor of liver failure and available data suggest that it can be considered as target for adjuvant therapy in this condition.展开更多
The discovery of the natriuretic peptide system in the early 1980s aroused great interest among clinical cardiologists. The heart was not a mechanical pump alone, but also an endocrine organ that had powerful effects ...The discovery of the natriuretic peptide system in the early 1980s aroused great interest among clinical cardiologists. The heart was not a mechanical pump alone, but also an endocrine organ that had powerful effects on blood circulation. Natriuretic peptides caused both natriuresis and diuresis, and they responded to a volume overload which caused either stretch or pressure on the heart. As a result, the findings led to the conclusion that the human body had a hormone with effects similar to those of a drug which treats high blood pressure. Later, it became evident that the volume contraction was fortified by extrarenal plasma shift. Here, a hypothesis is presented in which the role of natriuretic peptides is to regulate oxygen transport as the volume contraction leads to hemoconcentration with an increased oxygen-carrying capacity. Wall stress, either chemical or mechanical, changes the oxygen gradient of the myocardium and affects the diffusion of oxygen within a myocyte. In support of this hypothesis, hypoxia-response elements have been found in both the atrial natriuretic peptide and the brain natriuretic peptide genes.展开更多
Objective: To investigate the electrophysiology effects and mechanism of iron overload on the slow response autorhythmic cells in the left ventricular outflow tract of guinea pigs.Methods: Standard microelectrode cell...Objective: To investigate the electrophysiology effects and mechanism of iron overload on the slow response autorhythmic cells in the left ventricular outflow tract of guinea pigs.Methods: Standard microelectrode cell recording techniques were adopted to observe the electrophysiological effects of different concentrations of Fe^(2+)(100 μmol/L, 200 μmol/L) on the left ventricular outflow tract autorhythmic cells.Heart tissues were perfused with FeSO_4(200 μmol/L) combing with CaCl_2(4.2 mmol/L), Verapamil,(1 μmol/L), and nickel chloride(200μmol/L) respectively to observe the influences of these contents on electrophysiology of FeSO_4(200μmol/L) on the left ventricular outflow tract autorhythmic cells.Results: Fe^(2+)at both 100 μmol/L and 200 μmol/L could change the electrophysiological parameters of the slow response autorhythmic cells of the left ventricular outflow tract in a concentrationdependent manner resulting into decrease in Vmax, APA and MDP, slower RPF and VDD, and prolonged APD_(50) and APD_(90)(P all <0.05).Besides, perfusion of increased Ca^(2+) concentration could partially offset the electrophysiological effects of Fe^(2+)(200 μmol/L).The L-type calcium channel(LTCC) blocker Verapamil(1 μmol/L) could block the electrophysiological effects of Fe^(2+)(200 μmol/L).But the T-type calcium channel(TTCC) blocker nickel chloride(NiCl_2, 200 μmol/L) could not block the electrophysiological effects of Fe^(2+)(200 μmol/L).Conclusions: Fe^(2+) can directly change the electrophysiological characteristics of the slow response autorhythmic cells of the left ventricular outflow tract probably through the L-type calcium channel.展开更多
Collimating lenses are an important component of laser ranging systems,and high overload environments severely affect the beam shaping effect of such lenses.This study proposes a buffer isolation method on the basis o...Collimating lenses are an important component of laser ranging systems,and high overload environments severely affect the beam shaping effect of such lenses.This study proposes a buffer isolation method on the basis of impact stress wave attenuation theory for collimating lens spacers,ANSYS finite element software was applied to simulate the high load dynamics of collimating lenses,and the buffer isolation performance of different materials and composite structures was compared and analysed.Optical simulation analysis of the collimating lenses under different buffer conditions was performed using ZEMAX software to study the mechanism by which a high overload affects the collimating lenses.High overload and optical shaping experiments based on theoretical analysis were further conducted.Results showed the superiority of butadiene rubber to polytetrafluoroethylene after application of 70000 g impact acceleration.The combination-gasket method was superior to the single-gasket method,and the sandwich combination-gasket method was superior to the double-layer combination-gasket method.展开更多
BACKGROUND: Liver steatosis and iron overload, which are frequently observed in chronic hepatitis C (CHC), may contribute to the progression of liver injury. This study aimed to evaluate the correlation between liver ...BACKGROUND: Liver steatosis and iron overload, which are frequently observed in chronic hepatitis C (CHC), may contribute to the progression of liver injury. This study aimed to evaluate the correlation between liver steatosis and iron overload in Polish patients with CHC compared to non- alcoholic fatty liver disease (NAFLD) and HFE-hereditary hemochromatosis (HH) patients. METHODS: A total of 191 CHC patients were compared with 67 NAFLD and 21 HH patients. Liver function tests, serum markers of iron metabolism, cholesterol and triglycerides were assayed. The inflammatory activity, fibrosis, iron deposits and steatosis stages were assessed in liver specimens. HFE gene polymorphisms were investigated by PCR-RFLP. RESULTS: Liver steatosis was associated with obesity and diabetes mellitus. This disease was confirmed in 76/174 (44%) CHC patients, most of whom were infected with genotype 1. The average grade of steatosis was higher in NAFLD patients. CHC patients had significantly higher iron concentrations and transferrin saturations than NAFLD patients. Compared with CHC patients, HH patients had higher values of serum iron parameters and more intensive hepatocyte iron deposits without differences in the prevalence and intensity of liver steatosis. In the CHC group, lipids accumulation in hepatocytes was significantly associated with the presence of serummarkers of iron overload. No correlation between the HFE gene polymorphism and liver steatosis in CHC patients was found. CONCLUSIONS: Liver steatosis was diagnosed in nearly half of CHC patients, most of whom were infected with genotype 1. The intensity of steatosis was lower in CHC patients than that in NAFLD patients because of a less frequent diagnosis of metabolic syndrome. Only in CHC patients were biochemical markers of iron accumulation positively correlated with liver steatosis; these findings were independent of HFE gene mutations.展开更多
Iron overload is reported to be associated with immune alterations and increased susceptibility to infections. HIV infection is characterized by progressive immunodeficiency leading to invasion by opportunistic pathog...Iron overload is reported to be associated with immune alterations and increased susceptibility to infections. HIV infection is characterized by progressive immunodeficiency leading to invasion by opportunistic pathogens. It was of interest to find out if disease course in HIV type-1 infection could have any relation with alteration in body iron status among individuals with history of oral iron intake. A follow-up study of immunologic and virologic markers in relation to disease progression was undertaken on asymptomatic HIV-1 positive blood donors with history of oral iron intake (subgroup I) compared to those without such history (subgroup II). High serum iron was associated with elevated levels of Th2 category of cytokines, heightened immune activation, faster decline in CD4 + T lymphocyte count and higher viral set point. Pulmonary tuberculosis (PT) was the most common AIDS related illness (ARI) (>70%) recorded among subgroup I compared to non-PT category of ARI. Median ARI free duration (months) was shorter among those who developed PT compared to those developing non-PT category of ARI i.e. 30 (95% CI as 26,32) versus 67(95% CI as 60,71) in subgroup I and 47 (95% CI as 42,49) versus 80 (95% CI as 72,87) in subgroup II (P P < 0.001 for PT versus non-PT in both subgroups). The present study indicates that body iron overload resulting from excess intake of iron may be associated with qualitative defects in cell mediated immunity at early stage of HIV-1 infection that may facilitate subsequent acquisition of pulmonary tuberculosis, shorter ARI free duration and reduced survival.展开更多
BACKGROUND:Increased liver iron stores may contribute to the progression of liver injury and fibrosis,and are associated with a higher risk of hepatocellular carcinoma development.Pre-transplant symptoms of iron overl...BACKGROUND:Increased liver iron stores may contribute to the progression of liver injury and fibrosis,and are associated with a higher risk of hepatocellular carcinoma development.Pre-transplant symptoms of iron overload in patients with liver cirrhosis are associated with higher risk of infectious and malignant complications in liver transplant recipients.HFE gene mutations may be involved in the pathogenesis of liver iron overload and influence the progression of chronic liver diseases of different origins.This study was designed to determine the prevalence of iron overload in relation to HFE gene mutations among Polish patients with liver cirrhosis.METHODS:Sixty-one patients with liver cirrhosis included in the study were compared with a control group of 42 consecutive patients subjected to liver biopsy because of chronic liver diseases.Liver function tests and serum iron markers were assessed in both groups.All patients were screened for HFE mutations (C282Y,H63D,S65C).Thirty-six of 61 patients from the study group and all controls had liver biopsy performed with semiquantitative assessment of iron deposits in hepatocytes.RESULTS:The biochemical markers of iron overload and iron deposits in the liver were detected with a higher frequency (70% and 47% respectively) in patients with liver cirrhosis.There were no differences in the prevalence of all HFE mutations in both groups.In patients with a diagnosis of hepatocellular carcinoma,no significant associations with iron disorders and HFE gene mutations were found.CONCLUSIONS:Iron disorders were detected in patients with liver cirrhosis frequently but without significant association with HFE gene mutations.Only the homozygous C282Y mutation seems to occur more frequently in the selected population of patients with liver cirrhosis.As elevated biochemical iron indices accompanied liver iron deposits more frequently in liver cirrhosis compared to controls with chronic liver disease,there is a need for more extensive studies searching for the possible influence of non-HFE iron homeostasis regulators and their modulation on the course of chronic liver disease and liver cirrhosis.展开更多
The effect of single overload on the fatigue crack growth in 2024-T3 and 7075-T6 Al alloys was analyzed.Fatigue tests under constantamplitude loading with overload peak were carried out on V-notched specimens.Fractogr...The effect of single overload on the fatigue crack growth in 2024-T3 and 7075-T6 Al alloys was analyzed.Fatigue tests under constantamplitude loading with overload peak were carried out on V-notched specimens.Fractographic analysis was used as a principal approach to explain the crack growth retardation due to the overload.Scanning electron microscopy(SEM)analyses were conducted on the fractured surface of failed specimens to study the retardation effect.The obtained results show that the overload application generates a plastic zone in both aluminum alloys.The generated plastic zone is three times larger in the case of 2024-T3 compared to 7075-T6,and thus,a significant crack retardation was induced for 2024-T3.The retardation effect due to the overload for 2024-T3 and 7075-T6 lasted for about 10 mm and 1 mm,respectively,from the point of overload application.展开更多
The fatigue crack growth rate (CGR) of ultra high strength steel 30CrMnSiNi2A in distilledwater at 18,35 and 55℃ were measured.It was confirmed that the temperature is strongly af-fected on the corrosion fatigue CGR ...The fatigue crack growth rate (CGR) of ultra high strength steel 30CrMnSiNi2A in distilledwater at 18,35 and 55℃ were measured.It was confirmed that the temperature is strongly af-fected on the corrosion fatigue CGR of ultra high strength steel.An expression concerning theeffects of Δ K and temperature on the CGR was proposed.The fact that the apparentactivation energy (36.6 kJ/mol) resulted from regressive analysis of CGR data was similarto the activation energy of hydrogen diffusion in γ-Fe,strongly supporting the theory ofhydrogen-assisted crack growth.The overload retardation effect was greatly reduced in cor-rosion fatigue crack growth,especially at lower frequency,e.g.,0.1 Hz.This phenomenonmight be due to the increase of the SCC component of CGR after an overload.展开更多
Summary:Ranolazine,a late sodium current inhibitor,has been demonstrated to be effective on heart failure.18B-glycyrrhetinic acid(18β-GA)has the similar inhibitory effect on late sodium currents.However,its effect on...Summary:Ranolazine,a late sodium current inhibitor,has been demonstrated to be effective on heart failure.18B-glycyrrhetinic acid(18β-GA)has the similar inhibitory effect on late sodium currents.However,its effect on diastolic function is still unknown.This study aimed to determine whether 18β-GA can improve the diastolic function and to explore the underlying mechanisms.Eighty male Sprague Dawley(SD)rats of Langendorff model were randomly divided into the following groups:group A,normal cardiac perfusion group;group B,ischemia-reperfusion group;group C,ischemia-reperfusion with anemoniasulcata toxinⅡ(ATX-Ⅱ);group D,ranolazine group;and group E,18β-GA group with four different concentrations.Furthermore,a pressure-overloaded rat model induced by trans-aortic constriction(TAC)was established.Echocardiography and hemodynamics were used to evaluate diastolic function at 14th day after TAC.Changes of free intracellular calcium(Ca27)concentration was indirectly detected by laser scanning confocal microscope to confirm the inhibition of late sodium currents.With the intervention of ATX-Ⅱon ischemia reperfusion injury group,5 umol/L ranolazine,and 5,10,20,40μmol/L 18β-GA could improve ATX-I-induced cardiac diastolic dysfunction.630 mg/kg glycyrrhizin tablets could improve cardiac diastolic function in the pressure-overloaded rats.18B-GA and ranolazine had similar effects on reducing the free calcium in cardiomyocytes.The study demonstrates that 18B-GA and glycyrrhizin could improve diastolic dysfunction induced by ischemia-reperfusion injury in Langendorff-perfused rat hearts and pressure-overloaded rats.The mechanism may be attributed to the inhibition of enhanced late sodium currents.展开更多
The recent technological advancement has proved to be tremendously helpful for medical consultants. However, this advancement has also generated an enormous volume and variety of data, with a high velocity causing an ...The recent technological advancement has proved to be tremendously helpful for medical consultants. However, this advancement has also generated an enormous volume and variety of data, with a high velocity causing an information load for the medical consultants. Information overload can be defined as a difficulty a person can have in comprehending issue and making judgments that are caused by the presence of too much information. Information overload occurs when the amount of input to a system surpasses its processing capability. Decision-makers have a limited cognitive processing ability. Consequently, when information overload happens, it is possible that a decline in decision quality will take place. Decision-makers, such as medical consultants, have fairly limited cognitive processing capacity. Consequently, when information overload occurs, it is likely that a reduction in decision quality will occur. The aim of this study is to assess the impact of information overload on medical consultants’ life, its causes, and potential ways to deal with it. We performed a literature review to find the effects of information overload on medical consultants. Twelve research papers were considered for thematic analysis using NVivo 10 tool. These papers revealed four themes: 1) traditional methods of data collection;2) modern ways of data collection;3) consequences of modern ways of data collection;and 4) the need for handling information overload. This study suggests the development of a Continuing Professional Development course that explains how to deal with information overload, and availing the same through E-Learning mode might be one immediate solution.展开更多
文摘In this paper,to study the mechanical responses of a solid propellant subjected to ultrahigh acceleration overload during the gun-launch process,specifically designed projectile flight tests with an onboard measurement system were performed.Two projectiles containing dummy HTPB propellant grains were successfully recovered after the flight tests with an ultrahigh acceleration overload value of 8100 g.The onboard-measured time-resolved axial displacement,contact stress and overload values were successfully obtained and analysed.Uniaxial compression tests of the dummy HTPB propellant used in the gunlaunched tests were carried out at low and intermediate strain rates to characterize the propellant's dynamic properties.A linear viscoelastic constitutive model was employed and applied in finite-element simulations of the projectile-launching process.During the launch process,the dummy propellant grain exhibited large deformation due to the high acceleration overload,possibly leading to friction between the motor case and propellant grain.The calculated contact stress showed good agreement with the experimental results,though discrepancies in the overall displacement of the dummy propellant grain were observed.The dynamic mechanical response process of the dummy propellant grain was analysed in detail.The results can be used to estimate the structural integrity of the analysed dummy propellant grain during the gun-launch process.
基金supported by the National Natural Science Foundation of China,Nos.U2004106 (to WY),81971061 (to JC)the Key Scientific Research Project of Colleges and Universities in Henan Province,No.21A320039 (to WY)。
文摘Thalamic hemorrhage can lead to the development of central post-stroke pain.Changes in histone acetylation levels,which are regulated by histone deacetylases,affect the excitability of neurons surrounding the hemorrhagic area.However,the regulato ry mechanism of histone deacetylases in central post-stroke pain remains unclea r.Here,we show that iron overload leads to an increase in histone deacetylase 2expression in damaged ventral posterolateral nucleus neurons.Inhibiting this increase restored histone H3 acetylation in the Kcna2 promoter region of the voltage-dependent potassium(Kv)channel subunit gene in a rat model of central post-stroke pain,thereby increasing Kcna2expression and relieving central pain.However,in the absence of nerve injury,increasing histone deacetylase 2 expression decreased Kcna2expression,decreased Kv current,increased the excitability of neurons in the ventral posterolateral nucleus area,and led to neuropathic pain symptoms.Moreover,treatment with the iron chelator deferiprone effectively reduced iron overload in the ventral posterolateral nucleus after intracerebral hemorrhage,reversed histone deacetylase 2 upregulation and Kv1.2 downregulation,and alleviated mechanical hypersensitivity in central post-stroke pain rats.These results suggest that histone deacetylase 2 upregulation and Kv1.2 downregulation,mediated by iron overload,are important factors in central post-stroke pain pathogenesis and co uld se rve as new to rgets for central poststroke pain treatment.
基金supported by the National Natural Science Foundation of China,Nos.82104158(to XT),31800887(to LY),31972902(to LY),82001422(to YL)China Postdoctoral Science Foundation,No.2020M683750(to LY)partially by Young Talent Fund of University Association for Science and Technology in Shaanxi Province of China,No.20200307(to LY).
文摘β-Sitosterol is a type of phytosterol that occurs naturally in plants.Previous studies have shown that it has anti-oxidant,anti-hyperlipidemic,anti-inflammatory,immunomodulatory,and anti-tumor effects,but it is unknown whetherβ-sitosterol treatment reduces the effects of ischemic stroke.Here we found that,in a mouse model of ischemic stroke induced by middle cerebral artery occlusion,β-sitosterol reduced the volume of cerebral infarction and brain edema,reduced neuronal apoptosis in brain tissue,and alleviated neurological dysfunction;moreover,β-sitosterol increased the activity of oxygen-and glucose-deprived cerebral cortex neurons and reduced apoptosis.Further investigation showed that the neuroprotective effects ofβ-sitosterol may be related to inhibition of endoplasmic reticulum stress caused by intracellular cholesterol accumulation after ischemic stroke.In addition,β-sitosterol showed high affinity for NPC1L1,a key transporter of cholesterol,and antagonized its activity.In conclusion,β-sitosterol may help treat ischemic stroke by inhibiting neuronal intracellular cholesterol overload/endoplasmic reticulum stress/apoptosis signaling pathways.
基金supported by the National Natural Science Foundation of China(62003354).
文摘Anti-jamming solutions based on antenna arrays enhance the anti-jamming ability and the robustness of global navigation satellite system(GNSS)receiver remarkably.However,the performance of the receiver will deteriorate significantly in the overloaded interferences scenario.We define the overloaded interferences scenario as where the number of interferences is more than or equal to the number of antenna arrays elements.In this paper,the effect mechanism of interferences with different incident directions is found by studying the anti-jamming performance of the adaptive space filter.The theoretical analysis and conclusions,which are first validated through numerical examples,reveal the relationships between the optimal weight vector and the eigenvectors of the input signal autocorrelation matrix,the relationships between the interference cancellation ratio(ICR),the signal to interference and noise power ratio(SINR)of the adaptive space filter output and the number of interferences,the eigenvalues of the input signal autocorrelation matrix.In addition,two simulation experiments are utilized to further corroborate the theoretical findings through soft anti-jamming receiver.The simulation results match well with the theoretical analysis results,thus validating the effect mechanism of overloaded interferences.The simulation results show that,for a four elements circular array,the performance difference is up to 19 dB with different incident directions of interferences.Anti-jamming performance evaluation and jamming deployment optimization can obtain more accurate and efficient results by using the conclusions.
基金We acknowledge the funding support from the National Natural Science Foundation of China(Grant Nos.42141010,51879184 and 12172253).
文摘Dynamic tensile failure is a common phenomenon in deep rock practices,and thus accurately evaluating the dynamic tensile responses of rocks under triaxial pressures is of great significance.The Brazilian disc(BD)test is the suggested method by the International Society for Rock Mechanics and Rock Engineering(ISRM)for measuring both the static and dynamic tensile strengths of rock-like materials.However,due to the overload phenomenon and the complex preloading conditions,the dynamic tensile strengths of rocks measured by the BD tests tend to be overestimated.To address this issue,the dynamic BD tensile strength(BTS)of Fangshan marble(FM)under different preloading conditions were measured through a triaxial split Hopkinson pressure bar(SHPB).The fracture onset in BD specimen was captured through a strain gage around the disc center.The discrepancy between the traditional tensile strength(TTS,determined by the peak load P_(f) of the BD specimen)and the nominal tensile strength(NTS,obtained from the load P_(i) when the diametral fracture commences in the tested BD specimen)was applied to quantitatively evaluating the overload phenomenon.The Griffith criterion was used to rectify the calculation of the tensile stress at the disc center under triaxial stress states.The results demonstrate that the overload ratio(s)increases with the loading rate(σ)and decreases with the hydrostatic pressure(σ_(s)).The TTS corrected by the Griffith criterion is independent of theσ_(s)due to the overload phenomenon,while the NTS corrected by the Griffith criterion is sensitive to both the andσ.Therefore,it is essential to modify the tensile stress in dynamic confined BD tests using both the overload correction and the Griffith criterion rectification to obtain the accurate dynamic BTS of rocks.
文摘Background:It is known to all that iron overload is a fatal adverse effect on cells and tissue.Herein,our study aimed to investigate the effects of curcumin on iron-overloaded stress in macrophages.Methods:Ferric ammonium citrate was added to the macrophage cell line(RAW264.7)to establish an iron-overloaded macrophage model.Cell counting kit 8 assay was used to detect cell viability.Superoxide dismutase,reactive oxygen species,malondialdehyde,and apoptosis were performed to analyze the severity of cellular oxidative damage.In addition,quantitative real-time polymerase chain reaction and western blot were used to detect the expression of nuclear factor erythroid 2-related factor 2.Results:The result showed that iron overload of macrophage was visualized by incubating in 40μM ferric ammonium citrate for 24 h.The curcumin significantly reversed the iron overload-induced apoptotic cells at low(10μM)and middle(20μM)concentrations.Additionally,the levels of malondialdehyde and reactive oxygen species activity in the groups of curcumin at low(10μM)and middle(20μM)concentrations were significantly decreased,while superoxide dismutase activity was obviously increased compared with that of the ferric ammonium citrate group alone.Finally,we found that low(10μM)and middle(20μM)dose curcumin up-regulated nuclear factor erythroid 2-related factor 2 expression at mRNA and protein levels compared with the ferric ammonium citrate group alone.Conclusion:Curcumin reduces iron-overloaded stress in macrophages by activating nuclear factor erythroid 2-related factor 2 and enhancing the superoxide dismutase activity,thereby protecting cell apoptosis.
文摘The ability of a pavement structure in carrying out its function reduces in line with the increase of traffic load, especially if there are overloaded heavy vehicle passing through the road. This study was done to know the effect of overloading vehicles on the road pavement and remaining service life of the pavement. In this study, the service life of pavement due to overloaded vehicles was analyzed using the AASHTO 1993. In Narayanghat-Mugling road the composition of traffic seems to be 83.76% heavy vehicles, 9.18% medium vehicle and 7.05% light vehicle. For the direction of Narayanghat-Mugling, the pavement service life might be reduced by 59.90% due to overloading condition, while for the opposite direction, the service life would not reduced caused by the same factor. The impact of overload conditions on the road pavement showed premature failure;that is, a condition which the damage reduced the life of roads before the design life of the road is reached. From the results, it can be concluded that overloaded vehicles on the road are very influential to the reduction in pavement service life. Therefore, it is expected that road users to comply with existing regulations in the conduct of transportation. As overloading is increasing, it has to be controlled by rules and regulations with penalty to control the overloading. So fines must be associated with intensified enforcement when considered in further strategy. Regular monitoring, inspection and enforcement are the effective ways to control overloading. Use of technology (Automatic overloading information system) may be the effective way to control the overloading.
文摘The study of the deflection due to the passage of an axle on a pavement structure has the advantage to make possible to pronounce on the portance, the rigidity and the homogeneity of this one. In the case where the allowed axle load is not respected, surface deflection leads to premature deterioration of the roadway. In order to study the evolution of these deformations, deflection measurements were made by using the Benkelman method in the Fatick-Kaolack road in Senegal by varying the axle load with the following values: 10, 13 and 16 tons on three different zones. The results show a linear evolution of the deflection as a function of the axle load. Also, the impact of truck overloading was studied by considering different values of the axle load with comparison to the allowed axle load by using frequent types of vehicle. A numerical simulation of the Cast3M pavement was done first, in the case of an isolated single wheel with a radius of 12.5 cm, then in the case of an equivalent dual wheel with a radius of 18.1 cm for loads of 10 to 19 tons. In the same way, the pavement design software (ALIZE) is used to analyse the variation of the axle load. The results show a linear evolution of the deflection, which corroborates the measurements made in the field and those obtained by Samb (2014) with a slope coefficient equal to 1.7. Nevertheless, the case of an isolated single wheel of 12.5 cm radius is closest to the measurements with a straight line of slope coefficient equal to 1.9.
基金supported by a grant from Polish National Science Centre(2011/01/B/NZ6/00320)
文摘BACKGROUND: The liver, as the main iron storage compartment and the place of hepcidin synthesis, is the central organ involved in maintaining iron homeostasis in the body. Excessive accumulation of iron is an important risk factor in liver disease progression to cirrhosis and hepatocellular carcinoma.Here, we review the literature on the molecular pathogenesis of iron overload and its clinical consequences in chronic liver diseases.DATA SOURCES: Pub Med was searched for English-language articles on molecular genesis of primary and secondary iron overload, as well as on their association with liver disease progression. We have also included literature on adjuvant therapeutic interventions aiming to alleviate detrimental effects of excessive body iron load in liver cirrhosis.RESULTS: Excess of free, unbound iron induces oxidative stress, increases cell sensitivity to other detrimental factors,and can directly affect cellular signaling pathways, resulting in accelerated liver disease progression. Diagnosis of liver cirrhosis is, in turn, often associated with the identification of a pathological accumulation of iron, even in the absence of genetic background of hereditary hemochromatosis. Iron depletion and adjuvant therapy with antioxidants are shown to cause significant improvement of liver functions in patients with iron overload. Phlebotomy can have beneficial effects on liver histology in patients with excessive iron accumulation combined with compensated liver cirrhosis of different etiology.CONCLUSION: Excessive accumulation of body iron in liver cirrhosis is an important predictor of liver failure and available data suggest that it can be considered as target for adjuvant therapy in this condition.
文摘The discovery of the natriuretic peptide system in the early 1980s aroused great interest among clinical cardiologists. The heart was not a mechanical pump alone, but also an endocrine organ that had powerful effects on blood circulation. Natriuretic peptides caused both natriuresis and diuresis, and they responded to a volume overload which caused either stretch or pressure on the heart. As a result, the findings led to the conclusion that the human body had a hormone with effects similar to those of a drug which treats high blood pressure. Later, it became evident that the volume contraction was fortified by extrarenal plasma shift. Here, a hypothesis is presented in which the role of natriuretic peptides is to regulate oxygen transport as the volume contraction leads to hemoconcentration with an increased oxygen-carrying capacity. Wall stress, either chemical or mechanical, changes the oxygen gradient of the myocardium and affects the diffusion of oxygen within a myocyte. In support of this hypothesis, hypoxia-response elements have been found in both the atrial natriuretic peptide and the brain natriuretic peptide genes.
基金supported by Zhangjiakou Project of Science and Technology Studies and Development Planning(Grand No.1321078D)
文摘Objective: To investigate the electrophysiology effects and mechanism of iron overload on the slow response autorhythmic cells in the left ventricular outflow tract of guinea pigs.Methods: Standard microelectrode cell recording techniques were adopted to observe the electrophysiological effects of different concentrations of Fe^(2+)(100 μmol/L, 200 μmol/L) on the left ventricular outflow tract autorhythmic cells.Heart tissues were perfused with FeSO_4(200 μmol/L) combing with CaCl_2(4.2 mmol/L), Verapamil,(1 μmol/L), and nickel chloride(200μmol/L) respectively to observe the influences of these contents on electrophysiology of FeSO_4(200μmol/L) on the left ventricular outflow tract autorhythmic cells.Results: Fe^(2+)at both 100 μmol/L and 200 μmol/L could change the electrophysiological parameters of the slow response autorhythmic cells of the left ventricular outflow tract in a concentrationdependent manner resulting into decrease in Vmax, APA and MDP, slower RPF and VDD, and prolonged APD_(50) and APD_(90)(P all <0.05).Besides, perfusion of increased Ca^(2+) concentration could partially offset the electrophysiological effects of Fe^(2+)(200 μmol/L).The L-type calcium channel(LTCC) blocker Verapamil(1 μmol/L) could block the electrophysiological effects of Fe^(2+)(200 μmol/L).But the T-type calcium channel(TTCC) blocker nickel chloride(NiCl_2, 200 μmol/L) could not block the electrophysiological effects of Fe^(2+)(200 μmol/L).Conclusions: Fe^(2+) can directly change the electrophysiological characteristics of the slow response autorhythmic cells of the left ventricular outflow tract probably through the L-type calcium channel.
基金National Natural Science Foundation of China(51605227)the Fundamental Research Funds for the Central Universities(NUST30915011303)。
文摘Collimating lenses are an important component of laser ranging systems,and high overload environments severely affect the beam shaping effect of such lenses.This study proposes a buffer isolation method on the basis of impact stress wave attenuation theory for collimating lens spacers,ANSYS finite element software was applied to simulate the high load dynamics of collimating lenses,and the buffer isolation performance of different materials and composite structures was compared and analysed.Optical simulation analysis of the collimating lenses under different buffer conditions was performed using ZEMAX software to study the mechanism by which a high overload affects the collimating lenses.High overload and optical shaping experiments based on theoretical analysis were further conducted.Results showed the superiority of butadiene rubber to polytetrafluoroethylene after application of 70000 g impact acceleration.The combination-gasket method was superior to the single-gasket method,and the sandwich combination-gasket method was superior to the double-layer combination-gasket method.
基金supported by agrant from Medical University of Gdansk(W-175)
文摘BACKGROUND: Liver steatosis and iron overload, which are frequently observed in chronic hepatitis C (CHC), may contribute to the progression of liver injury. This study aimed to evaluate the correlation between liver steatosis and iron overload in Polish patients with CHC compared to non- alcoholic fatty liver disease (NAFLD) and HFE-hereditary hemochromatosis (HH) patients. METHODS: A total of 191 CHC patients were compared with 67 NAFLD and 21 HH patients. Liver function tests, serum markers of iron metabolism, cholesterol and triglycerides were assayed. The inflammatory activity, fibrosis, iron deposits and steatosis stages were assessed in liver specimens. HFE gene polymorphisms were investigated by PCR-RFLP. RESULTS: Liver steatosis was associated with obesity and diabetes mellitus. This disease was confirmed in 76/174 (44%) CHC patients, most of whom were infected with genotype 1. The average grade of steatosis was higher in NAFLD patients. CHC patients had significantly higher iron concentrations and transferrin saturations than NAFLD patients. Compared with CHC patients, HH patients had higher values of serum iron parameters and more intensive hepatocyte iron deposits without differences in the prevalence and intensity of liver steatosis. In the CHC group, lipids accumulation in hepatocytes was significantly associated with the presence of serummarkers of iron overload. No correlation between the HFE gene polymorphism and liver steatosis in CHC patients was found. CONCLUSIONS: Liver steatosis was diagnosed in nearly half of CHC patients, most of whom were infected with genotype 1. The intensity of steatosis was lower in CHC patients than that in NAFLD patients because of a less frequent diagnosis of metabolic syndrome. Only in CHC patients were biochemical markers of iron accumulation positively correlated with liver steatosis; these findings were independent of HFE gene mutations.
文摘Iron overload is reported to be associated with immune alterations and increased susceptibility to infections. HIV infection is characterized by progressive immunodeficiency leading to invasion by opportunistic pathogens. It was of interest to find out if disease course in HIV type-1 infection could have any relation with alteration in body iron status among individuals with history of oral iron intake. A follow-up study of immunologic and virologic markers in relation to disease progression was undertaken on asymptomatic HIV-1 positive blood donors with history of oral iron intake (subgroup I) compared to those without such history (subgroup II). High serum iron was associated with elevated levels of Th2 category of cytokines, heightened immune activation, faster decline in CD4 + T lymphocyte count and higher viral set point. Pulmonary tuberculosis (PT) was the most common AIDS related illness (ARI) (>70%) recorded among subgroup I compared to non-PT category of ARI. Median ARI free duration (months) was shorter among those who developed PT compared to those developing non-PT category of ARI i.e. 30 (95% CI as 26,32) versus 67(95% CI as 60,71) in subgroup I and 47 (95% CI as 42,49) versus 80 (95% CI as 72,87) in subgroup II (P P < 0.001 for PT versus non-PT in both subgroups). The present study indicates that body iron overload resulting from excess intake of iron may be associated with qualitative defects in cell mediated immunity at early stage of HIV-1 infection that may facilitate subsequent acquisition of pulmonary tuberculosis, shorter ARI free duration and reduced survival.
基金supported by a grant from the Medical University of Gdansk (W-175)
文摘BACKGROUND:Increased liver iron stores may contribute to the progression of liver injury and fibrosis,and are associated with a higher risk of hepatocellular carcinoma development.Pre-transplant symptoms of iron overload in patients with liver cirrhosis are associated with higher risk of infectious and malignant complications in liver transplant recipients.HFE gene mutations may be involved in the pathogenesis of liver iron overload and influence the progression of chronic liver diseases of different origins.This study was designed to determine the prevalence of iron overload in relation to HFE gene mutations among Polish patients with liver cirrhosis.METHODS:Sixty-one patients with liver cirrhosis included in the study were compared with a control group of 42 consecutive patients subjected to liver biopsy because of chronic liver diseases.Liver function tests and serum iron markers were assessed in both groups.All patients were screened for HFE mutations (C282Y,H63D,S65C).Thirty-six of 61 patients from the study group and all controls had liver biopsy performed with semiquantitative assessment of iron deposits in hepatocytes.RESULTS:The biochemical markers of iron overload and iron deposits in the liver were detected with a higher frequency (70% and 47% respectively) in patients with liver cirrhosis.There were no differences in the prevalence of all HFE mutations in both groups.In patients with a diagnosis of hepatocellular carcinoma,no significant associations with iron disorders and HFE gene mutations were found.CONCLUSIONS:Iron disorders were detected in patients with liver cirrhosis frequently but without significant association with HFE gene mutations.Only the homozygous C282Y mutation seems to occur more frequently in the selected population of patients with liver cirrhosis.As elevated biochemical iron indices accompanied liver iron deposits more frequently in liver cirrhosis compared to controls with chronic liver disease,there is a need for more extensive studies searching for the possible influence of non-HFE iron homeostasis regulators and their modulation on the course of chronic liver disease and liver cirrhosis.
基金the Deanship of Scientific Research at King Saud University for funding the work through the research group (No. RGP-VPP-035)
文摘The effect of single overload on the fatigue crack growth in 2024-T3 and 7075-T6 Al alloys was analyzed.Fatigue tests under constantamplitude loading with overload peak were carried out on V-notched specimens.Fractographic analysis was used as a principal approach to explain the crack growth retardation due to the overload.Scanning electron microscopy(SEM)analyses were conducted on the fractured surface of failed specimens to study the retardation effect.The obtained results show that the overload application generates a plastic zone in both aluminum alloys.The generated plastic zone is three times larger in the case of 2024-T3 compared to 7075-T6,and thus,a significant crack retardation was induced for 2024-T3.The retardation effect due to the overload for 2024-T3 and 7075-T6 lasted for about 10 mm and 1 mm,respectively,from the point of overload application.
文摘The fatigue crack growth rate (CGR) of ultra high strength steel 30CrMnSiNi2A in distilledwater at 18,35 and 55℃ were measured.It was confirmed that the temperature is strongly af-fected on the corrosion fatigue CGR of ultra high strength steel.An expression concerning theeffects of Δ K and temperature on the CGR was proposed.The fact that the apparentactivation energy (36.6 kJ/mol) resulted from regressive analysis of CGR data was similarto the activation energy of hydrogen diffusion in γ-Fe,strongly supporting the theory ofhydrogen-assisted crack growth.The overload retardation effect was greatly reduced in cor-rosion fatigue crack growth,especially at lower frequency,e.g.,0.1 Hz.This phenomenonmight be due to the increase of the SCC component of CGR after an overload.
基金This project was supported by the National Natural Science Foundation of China(No.81600317 and No.81700345)the Open Foundation of Hubei Key Laboratory of Biological Targeted Therapy(No.02.03.2014-10).
文摘Summary:Ranolazine,a late sodium current inhibitor,has been demonstrated to be effective on heart failure.18B-glycyrrhetinic acid(18β-GA)has the similar inhibitory effect on late sodium currents.However,its effect on diastolic function is still unknown.This study aimed to determine whether 18β-GA can improve the diastolic function and to explore the underlying mechanisms.Eighty male Sprague Dawley(SD)rats of Langendorff model were randomly divided into the following groups:group A,normal cardiac perfusion group;group B,ischemia-reperfusion group;group C,ischemia-reperfusion with anemoniasulcata toxinⅡ(ATX-Ⅱ);group D,ranolazine group;and group E,18β-GA group with four different concentrations.Furthermore,a pressure-overloaded rat model induced by trans-aortic constriction(TAC)was established.Echocardiography and hemodynamics were used to evaluate diastolic function at 14th day after TAC.Changes of free intracellular calcium(Ca27)concentration was indirectly detected by laser scanning confocal microscope to confirm the inhibition of late sodium currents.With the intervention of ATX-Ⅱon ischemia reperfusion injury group,5 umol/L ranolazine,and 5,10,20,40μmol/L 18β-GA could improve ATX-I-induced cardiac diastolic dysfunction.630 mg/kg glycyrrhizin tablets could improve cardiac diastolic function in the pressure-overloaded rats.18B-GA and ranolazine had similar effects on reducing the free calcium in cardiomyocytes.The study demonstrates that 18B-GA and glycyrrhizin could improve diastolic dysfunction induced by ischemia-reperfusion injury in Langendorff-perfused rat hearts and pressure-overloaded rats.The mechanism may be attributed to the inhibition of enhanced late sodium currents.
文摘The recent technological advancement has proved to be tremendously helpful for medical consultants. However, this advancement has also generated an enormous volume and variety of data, with a high velocity causing an information load for the medical consultants. Information overload can be defined as a difficulty a person can have in comprehending issue and making judgments that are caused by the presence of too much information. Information overload occurs when the amount of input to a system surpasses its processing capability. Decision-makers have a limited cognitive processing ability. Consequently, when information overload happens, it is possible that a decline in decision quality will take place. Decision-makers, such as medical consultants, have fairly limited cognitive processing capacity. Consequently, when information overload occurs, it is likely that a reduction in decision quality will occur. The aim of this study is to assess the impact of information overload on medical consultants’ life, its causes, and potential ways to deal with it. We performed a literature review to find the effects of information overload on medical consultants. Twelve research papers were considered for thematic analysis using NVivo 10 tool. These papers revealed four themes: 1) traditional methods of data collection;2) modern ways of data collection;3) consequences of modern ways of data collection;and 4) the need for handling information overload. This study suggests the development of a Continuing Professional Development course that explains how to deal with information overload, and availing the same through E-Learning mode might be one immediate solution.
