Pt@AuNF nanozyme and horseradish peroxidase-based lateral flow immunoassay dual enzymes signal amplification strategy for sensitive detection of zearalenone.

Lateral flow immunoassay (LFIA) has been employed extensively for the rapid, accurate, and portable detection of foodborne toxins. Here, the platinum gold nanoflower core-shell (Pt@AuNF) nanozyme with excellent optical properties, good catalytic ability and controllable reaction conditions were prepared to effectively improve the performance of lateral flow immunoassay (LFIA) strips. The Pt@AuNF nanozyme and horseradish peroxidase (HRP) combined with monoclonal antibody were used as signal probes based on the dual enzymes catalytic signal amplification strategy to detect Zearalenone sensitively. Dual enzymes catalyze the decomposition of hydrogen peroxide into hydroxyl radicals, and under the influence of hydroxyl radicals, colorless 3,3',5,5' -tetramethylbenzidine (TMB) is oxidized to blue ox-TMB, which is superimposed on the strips for signal amplification to broaden the detection range. The limit of detection (LOD) of the Pt@AuNF-HRP labeled LFIA strips after signal amplification was 0.052 ng/mL, and the detection range was 0.052-7.21 ng/mL. Compared with the Pt@AuNF labeled strips, while reducing the probes amount by half to achieve antibody conservation, the detection range was expanded by 5-fold based on achieving improved sensitivity. The study provided a meaningful reference for expanding the detection range based on immunoassay.

16α-OHE1, a novel oestrogen metabolite, attenuates dysfunction of left ventricle contractility via regulation of autophagy after myocardial ischemia and reperfusion.

BACKGROUND: Myocardial ischemia-reperfusion (MI/R) can exacerbate the initial cardiac damage in the myocardial functional changes, including dysfunction of left ventricular contractility. Oestrogen has been proven to protect the cardiovascular system. However, whether the oestrogen or its metabolites play the main role in attenuating dysfunction of left ventricular contractility is unknown. METHODS AND RESULTS: This study used the LC-MS/MS to detect oestrogen and its metabolites in clinical serum samples (n = 62) with heart diseases. After correlation analysis with markers of myocardial injury including cTnI (P < 0.01), CK-MB (P < 0.05), and D-Dimer (P < 0.001), 16α-OHE1 was identified. The result from LC-MS/MS in female and ovariectomised (OVX) rat serum samples (n = 5) matched the findings in patients. In MI/R model of animal, the recovery of left ventricular developed pressure (LVDP), rate pressure product (RPP), dp/dtmax and dp/dtmin after MI/R in OVX or male group were worsened than those in female group. Also, the infarction area of OVX or male group was larger than that in females (n = 5, p < 0.01). Furthermore, LC3 II in the left ventricle of OVX and male group was lower than that in females (n = 5, p < 0.01) by immunofluorescence. In H9C2 cells, after the application of 16α-OHE1, the number of autophagosomes was further increased and other organelles improved in MI/R. Simultaneously, LC3 II, Beclin1, ATG5, and p-AMPK/AMPK were increased, and p-mTOR/mTOR was decreased (n = 3, p < 0.01) by Simple Western. CONCLUSION: 16α-OHE1 could attenuate left ventricle contractility dysfunction via autophagy regulation after MI/R, which also offered fresh perspectives on therapeutical treatment for attenuating MI/R injury.

Colloidal Au sphere and nanoflower-based immunochromatographic strips for sensitive detection of zearalenone in cereals.

Zearalenone (ZEN), also known as an F-2 toxin, is a secondary metabolite in the toxic Fusarium species with estrogen properties. ZEN and its derivatives can cause developmental and reproductive disorders in humans and other mammals. In this study, colloidal Au spheres (AuSPs) and Au nanoflowers (AuNFs) were used as signal labels to detect ZEN in cereals, and the critical factors affecting the sensitivity of the immunochromatographic strip (ICS), namely the volume of antigen, antibody, and probe quantities were optimized and compared in detail. Since the large specific surface area of AuNFs reduces the steric hindrance of proteins, it is more conducive to improving the fixation rate of antibodies and proteins. Compared with the traditional colloidal AuSP immunochromatographic strip (AuSP-ICS), the volume of the antibody used in the AuNF immunochromatographic strip (AuNF-ICS) was 0.6 times that in the AuSPs-ICS. At the same antigen volume, a lower amount of probe can achieve the desired visual detection effect and higher sensitivity. For the AuNF-ICS, the limit of detection (LOD) was as low as 0.08 ng mL-1. ZEN could be detected quickly and accurately from 0.08-10.2 ng mL-1. And the AuNF-ICS had a high degree of specificity and sensitivity to ZEN. In summary, the AuNF-ICS serves as a valuable tool in large-scale on-site detection of ZEN.

Metabotropic glutamate receptor 5 blockade attenuates pathological cardiac remodelling in pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is characterized by cardiac remodelling. Glutaminolysis plays a crucial role in PAH-induced remodelling. The metabotropic glutamate receptor 5 (mGluR5) may mediate this process. This study investigated whether or not the blockade of mGluR5 may attenuate PAH-induced pathological cardiac remodelling. Pulmonary arterial hypertension was induced by intraperitoneally injecting male Sprague-Dawley (SD) rats with 60 mg/kg of monocrotaline (MCT). 3-((2-Methyl-4-thiazolyl)ethynyl)pyridine (MTEP) (10 mg/kg intraperitoneally) was used as a therapeutic intervention to block mGluR5. Cardiac functions were assessed with right heart catheterization and electrocardiography. Alterations in protein expressions and inflammatory markers were investigated using western blot and enzyme-linked immunosorbent assay (ELISA), respectively. Increased right ventricular systolic pressure (RSVP), elevated protein expressions of mGluR5, collagen types I and III and cartilage intermediate layer protein 1 (CILP1), enhanced phosphorylation of phosphatidylinositol 3-kinase (PI3K), AKT and p38 mitogen-activated protein kinase (P38MAPK), increased angiopoietin 2 (Ang 2) and vascular endothelial growth factor-α (VEGF) protein expressions and elevated serum levels of interleukin 6 (IL-6) and tumour necrotic factor α (TNF-α) were observed in MCT-induced PAH rats. MTEP improved hemodynamics and right ventricular hypertrophy. MTEP also attenuated MCT-induced elevations in the protein expressions of mGluR5, collagen types I and III, CILP1, Ang 2 and VEGF and decreased PI3K, AKT and P38MAPK phosphorylations and inflammatory cytokine levels. Metabotropic glutamate receptor 5 blockade using MTEP ameliorates PAH-induced pathological right cardiac remodelling via inhibiting the signalling cascade involving PI3K/AKT, P38MAPK, Ang 2 and VEGF.

Adverse skin reactions induced by sintilimab in advanced lung squamous carcinoma: a case report and review of the literature.

Background: Sintilimab is an immune checkpoint inhibitor (ICI). It can induce immune-related Adverse Events (irAEs). Severe adverse skin reactions are rare, but the mortality rate is high. We report the first case of successful treatment of adverse skin reactions using traditional Chinese medicine (TCM). Case Description: Here we present the case of a 67-year-old male with advanced lung squamous carcinoma. After 8 cycles of chemotherapy, the patient's disease progressed and the treatment regimen was adjusted to sintilimab combined with albumin paclitaxel and cisplatin. Thirty-two days after this cycle, the patient reported a sporadic rash with pruritus on the face, front chest, and both upper limbs. The area of rash was 40%, and the adverse reaction was grade 3. The level of interleukin-related indicators was above normal. The patient's skin symptoms disappeared after treatment with hormones, TCM, and other drugs. The patient's adverse skin reaction was due to an immune-related toxicity caused by sintilimab, so treatment with sintilimab was suspended. The albumin-paclitaxel plus cisplatin regimen was continued to treat lung cancer. Conclusions: Although rare, case of fatal adverse reaction caused by sintilimab have been reported. We recommend early monitoring and recognition of symptoms. During management, high-dose hormones combined TCM may be helpful.

Discovery of cyclooxygenase-2 inhibitors from Kadsura coccinea by affinity ultrafiltration mass spectrometry and the anti-inflammatory activity.

The medicinal plant Kadsura coccinea distributing in South China, was widely used for reducing inflammation and relieving pain. Previous study in our laboratory had proved the significant therapeutic effects of K. coccinea extract on adjuvant arthritis rats. To explore the responsible components and possible mechanisms, an AUF-HPLC-Q-TOF/ MS method was employed for screening and characterizing COX-2 ligands from K. coccinea stems for the first time. Meanwhile, the molecular docking was performed to simulate the binding modes for ligands and COX-2, the cell-free enzyme activity assay was applied to verify the direct COX-2 inhibition of potential inhibitors, and the cell-based study on COX-2 expression was to evaluate the anti-inflammatory effect of (+)-Anwulignan. As a result, the potential COX-2 inhibitor (+)-Anwulignan significantly suppressing COX-2 expressions in LPS signaling pathways might be a good candidate for anti-inflammation and analgesia. In conclusion, AUF mass spectrometry combining the molecular docking and bioassays in vitro was an efficient approach for discovering enzyme inhibitors from traditional herbs.

[Optimization of medical educational objectives by improving summative assessment system].

Summative assessment plays a decisive role in the educational assessment system, which is a yardstick to measure the cultivating goal of higher education. The rapid progress of modern society has put forward higher standard for higher medical education. Traditional summative assessment system with single dimension that focuses on evaluating the student's learning outcome via a standardized examination cannot meet the higher requirements for undergraduate medical education. We have improved the summative assessment system by optimizing the assessment content, criteria and method, as well as teachers' assessment skills and students' evaluation. The reform greatly increases the teaching quality and learning effect in our university.

MicroRNA-638 expression change in osteosarcoma patients via PLD1 and VEGF expression.

The present study aimed to investigate the function and mechanism of microRNA-638 (miR-638) in osteosarcoma. MiR-638 expression change in patients with osteosarcoma was detected by reverse transcription-quantitative polymerase chain reaction. Expression of miR-638 was observed to be downregulated in patients with osteosarcoma compared with the control group. In vitro, overexpression of miR-638 induced apoptosis, and inhibited cell proliferation and invasion of osteosarcoma cells. Overexpression of miR-638 induced Bcl-2 associated X and caspase-3 protein expression, and suppressed cyclin D1, phospholipase D1 (PLD1) and vascular endothelial growth factor (VEGF) protein expression in osteosarcoma. The promotion of PLD1 decreased the effects of miR-638 on osteosarcoma cell proliferation. In summary, it was demonstrated that miRNA-638 expression change in patients with osteosarcoma and an in vitro model via PLD1 and VEGF expression and miRNA-638 may be potential clinical indicators of osteosarcoma.

Surface immobilization of gelatin onto TiO2 nanotubes to modulate osteoblast behavior.

To improve the bioactivity of titanium implants, a homogeneous layer of TiO2 nanotubes with a diameter of approximately 110nm was prepared by anodization. Gelatin was immobilized onto TiO2 nanotubes through an intermediate layer of polydopamine. The surface characteristics of different substrates were evaluated using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurements, respectively. These results demonstrate that gelatin was successfully immobilized onto TiO2 nanotubes. In vitro cell culture experiments including immunofluorescence staining, cell viability, alkaline phosphatase (ALP), mineralization and the expression of osteogenic genes including runt-related transcription factor 2 (Runx2), ALP, collagen type I (Col I), and osteopontin (OPN) confirm that cell spreading, proliferation and osteoblastic differentiation were improved when cells were seeded onto gelatin-immobilized TiO2 nanotubes. This resulting material shows great promise as a future material in titanium implant applications.

Ibuprofen attenuates cardiac fibrosis in streptozotocin-induced diabetic rats.

OBJECTIVE: To investigate the effects of ibuprofen on cardiac fibrosis in a rat model of type 1 diabetes. METHODS: The diabetic model was established by injecting streptozotocin into the rats. Then, ibuprofen or pioglitazone was given by gavage for 8 weeks. The cardiac fibrosis was assessed, and the major components of the renin-angiotensin system, the transforming growth factor ß1 (TGF-ß1) and the mammalian target of rapamycin (mTOR), were evaluated by histopathological, immunohistochemical, Western blot analysis or ELISA assay. RESULTS: Obvious cardiac fibrosis was detected in the diabetic group and was alleviated by ibuprofen treatment. Angiotensin-converting enzyme (ACE), angiotensin (Ang) II and AngII type 1 receptor (AT1-R) levels were higher, and ACE2, Ang(1-7) and Mas receptor (Mas-R) were lower in the diabetic group. The ratio of ACE to ACE2 was raised in the diabetic group. All these changes were ameliorated by ibuprofen. TGF-ß1 and mTOR were raised in the hearts of the diabetic group and were attenuated by ibuprofen treatment. There was no significant difference between the ibuprofen and the pioglitazone groups. CONCLUSION: Ibuprofen could ameliorate the cardiac fibrosis in diabetic rats by reduction of the ACE/AngII/AT1-R axis and enhancement of the ACE2/Ang(1-7)/Mas-R axis, leading to a decrease in TGF-ß1 and mTOR.

[Danshensu delays the senescence of rat aortic endothelial cells via activation of SIRT1-SOD pathway].

The present study was aimed to investigate the effect of pretreatment with Danshensu (DSS) on rat aortic endothelial cells (RAECs) senescence and the underlying mechanisms. Cultured RAECs at fourth and twelfth passages were taken as young and old groups, respectively. DSS and DSS+nicotinamide (DSS+N) groups were incubated with DSS and DSS in combination with nicotinamide, an inhibitor of silent information regulator 1 (SIRT1), from the fourth to twelfth passage, respectively. The cell status of senescence was determined by the senescence-associated ß-galactosidase (SA ß-gal) staining, and 4,6-diamino-2-phenyl indole (DAPI) fluorescent dye was used to detect senescence associated heterochromatin foci (SAHF) formation; Thiobarbituric acid (TBA) and colorimetric methods were used to evaluate malondialdehyde (MDA) and H2O2contents; Western blot was employed to analysis the expressions of xanthine oxidase (XOD), SIRT1 and superoxide dismutase 2 (SOD2) in the RAECs. The results showed that, in comparison with young group, the old group exhibited higher SA ß-gal positive and SAHF formation rates, as well as higher MDA and H2O2levels (P < 0.05 or P < 0.01), whereas DSS pretreatment reduced SA ß-gal positive and SAHF formation rates, decreased MDA and H2O2 contents (P < 0.05 or P < 0.01). The protection of DSS was reversed by nicotinamide. Compared with the young group, the old group showed higher expression levels of XOD, but lower SIRT1 and SOD2expression levels (P < 0.05 or P < 0.01). With the pretreatment of DSS, the expression of XOD was declined, and the expression levels of SIRT1 and SOD2were elevated, while nicotinamide reversed the effects of DSS. These results suggest that DSS delays senescence of RAECs via up-regulation of SIRT1.

[Exogenous hydrogen sulfide reduces vascular aging in D-galactose-induced subacute aging rats].

The present study was aimed to observe the protective effect of exogenous hydrogen sulfide (H2S) on vascular structural and functional changes of aorta in D-galactose-induced subacute aging rats. Adult male SD rats were randomly divided to five groups: the vehicle group, the D-galactose (D-gal) group, and the three NaHS groups treated with low (1 µmol·kg⁻¹·d⁻¹), middle (10 µmol·kg⁻¹·d⁻¹) or high (100 µmol·kg⁻¹·d⁻¹) dose of NaHS respectively. The D-gal group rats were given subcutaneously injection of 125 mg/kg D-gal per day for eight weeks to induce subacute aging model. In the NaHS group, D-gal was administered as above but with NaHS intraperitoneally injected at a dosage of 1, 10, 100 µmol·kg⁻¹·d⁻¹ respectively. Equivalent volumes of saline were administered per day for eight weeks in vehicle group. Morphological changes of aorta were observed by HE and Masson staining. The level of H2S in serum, the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA), as well as anti-superoxide anions in vascular tissue were determined by spectrophotometry. Angiotensin II (AngII) levels in plasma were measured using competitive enzyme immunoassay. The expression of angiotensin II type 1 receptor (AT1R) in aorta was determined by Western blot. The results showed that the aging aortic morphologic changes in model rats were ameliorated in NaHS groups. Decreased vascular endothelial exfoliative cells and vascular smooth muscle cell (SMC) proliferation were shown in NaHS groups by HE staining. Masson staining analysis showed reduced relative contents of collagen fibers (P < 0.05) and SMC (P < 0.05) in NaHS groups. Compared to vehicle group, serum concentration of H2S in D-gal group was decreased, while it was increased in NaHS groups after treatment with NaHS (P < 0.05). In the D-gal group, the concentration of AngII in plasma was significantly increased compared with that in vehicle group, while it was decreased in NaHS groups (P < 0.05). Moreover, levels of vascular tissue anti-superoxide anion and the activity of SOD were obviously higher, MDA was significantly lower in all NaHS treated groups than those in the D-gal group respectively (P < 0.05). Western blot analysis showed that the expression of AT1R was increased in D-gal group compared with that in vehicle group, while it was decreased after treatment with NaHS compared with that in D-gal group (P < 0.05). These results suggest that exogenous H2S can ameliorate the age-related changes of aortic morphology, decrease the concentration of AngII in plasma, down-regulate the expression of AT1R in vascular tissue, and mitigate the level of oxidative stress. These changes delay the vascular aging in aging rats ultimately.

Hydrogen sulfide delays nicotinamide-induced premature senescence via upregulation of SIRT1 in human umbilical vein endothelial cells.

The present study was designed to investigate the effect of hydrogen sulfide on cellular senescence of human umbilical vascular endothelial cells (HUVECs CC-2517) and its underlying mechanism. The premature senescence-like phenotype HUVECs (the fourth passage) was induced by treatment with nicotinamide (NAM, an inhibitor of SIRT1, 5 mmol/L, 12 h). Cells were cultured with sodium hydrosulfide (NaHS, 12.5, 25, 50 and 100 µmol/L) for 48 h in premature senescence-like phenotype HUVECs. The fourth passage of HUVECs was considered as young group. Senescence-associated (SA)-ß-galactosidase activities were detected to evaluate cell senescence, and the expression of SA heterochromatin foci (SAHF) was visualized by DAPI DNA staining. The mRNA and protein levels of SIRT1 were detected using RT-PCR and western blotting analysis, respectively. The results showed that ß-galactosidase positive cells and the formation of SAHF were markedly increased after treatment with NAM (5 mmol/L) for 12 h. We also found that NaHS (12.5 µmol/L) had no effect on the percentage of SA ß-gal positive cells and the expression of SAHF, and the hallmarks decreased at the concentration of 25 and 50 µmol/L, reaching the minimum at 50 µmol/L, while the percentage of SA ß-gal positive cells and the expression of SAHF increased at the concentration of 100 µmol/L. Furthermore, we found that both on protein and mRNA levels of SIRT1 in the Y+N+S50 group was significantly increased compared with that in Y+N group. In conclusion, NaHS delays senescence of HUVECs induced by NAM via upregulation of SIRT1 expression.

Rational design of phosphorescent chemodosimeter for reaction-based one- and two-photon and time-resolved luminescent imaging of biothiols in living cells.

A selective phosphorescent biothiols probe is synthesized based on Ir(III) complex 1, which has 2,2'-biquinoline as the N^N ligand for realizing the satisfied two-photon absorption cross-section and two-functionalized 2-phenylpyridine ligands with an α,ß-unsaturated ketone moiety as the thiol reaction site. The one- and two-photon optical properties of 1 are investigated through UV-vis absorption spectrum and photoluminescence spectrum. This Ir(III) complex can act as an excellent one- and two-photon excited "OFF-ON" phosphorescent probe for biothiols based on the 1,4-addition of biothiol to α,ß-unsaturated ketones. Moreover, one- and two-photon-induced luminescent imagings of biothiols in living cells are also realized. Furthermore, the experiments of time-resolved photoluminescence technique and fluorescence lifetime imaging microscopy demonstrate that 1 is able to detect biothiols in the presence of strong background fluorescence. In addition, probe 1 is adsorbed into the shell of mesoporous silica nanoparticles with core-shell structure to form a nanoprobe, which can realize the ratiometric detection of biothiols in absolute water solution and living cells based on two phosphorescent signals.

Protective effect of endogenous hydrogen sulfide against oxidative stress in gastric ischemia-reperfusion injury.

Hydrogen sulfide (H(2)S) is a gaseous signaling molecule, which plays a critical role in a number of physiological and pathological progresses. In order to determine the effect of endogenous H(2)S on gastric ischemia-reperfusion (GI-R), we evaluated the gastric mucosal damage in rats intraperitoneally injected with DL-propargylglycine (PAG, 50 mg/kg/day) or L-cysteine (L-cys, 50 mg/kg/day) for 7 days before GI-R. GI-R injury was achieved by clamping the celiac artery for 30 min, followed by reperfusion for 60 min. Gastric mucosal damage was macroscopically assessed in the area of injury and deep damage was assessed by histopathological scoring. PAG increased the area of gastric mucosal injury and deep damage compared with that in untreated GI-R rats (P<0.05). While PAG decreased the H(2)S concentration and cystathionine γ-lyase (CSE) expression in the gastric mucosa, L-cys significantly attenuated the effects of GI-R. Western blot analysis revealed that the increases of malondialdehyde (MDA) and xanthine oxidase (XOD), and decreases of glutathione (GSH), superoxide dismutase (SOD) and the restriction of superoxide (O(2) (-)) production in the PAG group were inhibited by L-cys (P<0.05). Endogenous H(2)S has a protective effect against GI-R in rats by inhibiting oxygen free radical overproduction.

Smart poly(N-isopropylacrylamide) containing iridium(III) complexes as water-soluble phosphorescent probe for sensing and bioimaging of homocysteine and cysteine.

Homocysteine (Hcy) and cysteine (Cys) are two important kinds of amino acids in human bodies. Herein, we synthesized an iridium(III) complex-functionalized poly(N-isopropylacrylamide) and its hydrogel, which could be used as the excellent phosphorescent bioprobe for sensing Hcy and Cys. Their detection can be realized in aqueous system through the variations in absorption and photoluminescence spectra. Furthermore, living cell imaging experiments demonstrate that the phosphorescent bioprobe is membrane permeable and can monitor the changes of Hcy and Cys within living cells. In addition, the probe is also thermoresponsive, and its photoluminescence intensified with increasing temperature. These results suggests that this bioprobe has promising application in biomedical fields.

Oxidative stress induces gastric submucosal arteriolar dysfunction in the elderly.

AIM: To evaluate human gastric submucosal vascular dysfunction and its mechanism during the aging process. METHODS: Twenty male patients undergoing subtotal gastrectomy were enrolled in this study. Young and elderly patient groups aged 25-40 years and 60-85 years, respectively, were included. Inclusion criteria were: no clinical evidence of cardiovascular, renal or diabetic diseases. Conventional clinical examinations were carried out. After surgery, gastric submucosal arteries were immediately dissected free of fat and connective tissue. Vascular responses to acetylcholine (ACh) and sodium nitroprusside (SNP) were measured by isolated vascular perfusion. Morphological changes in the gastric mucosal vessels were observed by hematoxylin and eosin (HE) staining and Verhoeff van Gieson (EVG) staining. The expression of xanthine oxidase (XO) and manganese-superoxide dismutase (Mn-SOD) was assessed by Western blotting analysis. The malondialdehyde (MDA) and hydrogen peroxide (H2O2) content and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were determined according to commercial kits. RESULTS: The overall structure of vessel walls was shown by HE and EVG staining, respectively. Disruption of the internal elastic lamina or neointimal layers was not observed in vessels from young or elderly patients; however, cell layer number in the vessel wall increased significantly in the elderly group. Compared with submucosal arteries in young patients, the amount of vascular collagen fibers, lumen diameter and media cross-sectional area were significantly increased in elderly patients. Ach- and SNP-induced vasodilatation in elderly arterioles was significantly decreased compared with that of gastric submucosal arterioles from young patients. Compared with the young group, the expression of XO and the contents of MDA and H2O2 in gastric submucosal arterioles were increased in the elderly group. In addition, the expression of Mn-SOD and the activities of SOD and GSH-Px in the elderly group decreased significantly compared with those in the young group. CONCLUSION: Gastric vascular dysfunction and senescence may be associated with increased oxidative stress and decreased antioxidative defense in the aging process.

[Exogenous hydrogen sulfide attenuates gastric ischemia-reperfusion injury via activation of K(ATP) channel].

The present study aimed to investigate the protective effect and mechanism of hydrogen sulfide donor NaHS administration against gastric mucosal injury induced by gastric ischemia-reperfusion (GI-R) in rats. GI-R injury was induced by clamping the celiac artery of adult male SD rats for 30 min and followed by reperfusion for 1 h. The rats were randomly divided into sham group, GI-R group, NaHS group, glibenclamide group and pinacidil group. Gastric mucosal damage was analyzed with macroscopic injured area, deep damage was assessed with histopathology scores, and the hydrogen sulfide concentration in plasma was determined by colorimetric method. The results showed that pretreatment of NaHS significantly reduced the injured area and deep damage of the gastric mucosa induced by GI-R. However, NaHS did not significantly alter the levels of hydrogen sulfide in plasma 14 d after NaHS administration. The gastric protective effect of NaHS during reperfusion could be attenuated by glibenclamide, an ATP-sensitive potassium channel (K(ATP)) blocker. However, K(ATP) opener pinacidil inhibited the GI-R-induced injury. These results suggest that exogenous hydrogen sulfide plays a protective role against GI-R injury in rats possibly through modulation of K(ATP) channel opening.

Effects of H2S on myogenic responses in rat cerebral arterioles.

BACKGROUND: The potential biological significance of hydrogen sulfide (H2S) has attracted growing interests in recent years, but its role in the myogenic response of rat cerebral arterioles has not been explored. METHODS AND RESULTS: Rats were injected with NaHS (an H2S donor, 2-200 µmol·kg⁻¹·day⁻¹, i.p.) or saline for 3 weeks. MBP was measured with a tail-cuff method. Cerebral arterioles were isolated and cannulated in an organ bath system, and vessel diameters were measured with an image-shearing device. Changes in diameter in response to stepwise increases in intravascular pressure (20-120 mmHg) were investigated under no-flow conditions. After the treatments, plasma H2S increased and MBP decreased significantly. NaHS reduced the myogenic response in a dose-dependent manner. This effect was markedly attenuated by glibenclamide, a K(ATP) channel blocker. Blockade of nitric oxide (NO) production with NG-nitro-L-arginine methyl ester (L-NAME, a NO synthase inhibitor) enhanced, whereas removal of the endothelium abolished the inhibitory role of NaHS on the myogenic response. CONCLUSIONS: For the first time it has been demonstrated that H2S decreases the myogenic response of cerebral arterioles in vivo, and this effect is endothelium-dependent and partially mediated by K(ATP) channels.

Differential expression of Bcl-2 and Bax during gastric ischemia-reperfusion of rats.

AIM: To investigate expression of Bcl-2 and Bax in gastric ischemia-reperfusion (GI-R) and involvement of extracellular signal-regulated kinase (ERK) 1/2 activation. METHODS: The GI-R model was established by ligature of the celiac artery for 30 min and reperfusion in Sprague-Dawley rats. Rats were assigned to groups in accordance with their evaluation period: control, 0, 0.5, 1, 3, 6, 24, 48, and 72 h. Expression and distribution of Bcl-2 and Bax proteins were analyzed by immunohistochemistry and western blotting in gastric tissue samples after sacrifice. RESULTS: Compared with controls, the percentage of positive cells and protein levels of Bcl-2 decreased in the early phases of reperfusion, reached its minimum at 1 h (P < 0.05); it then increased, reaching its peak at 24 h of reperfusion (P < 0.05). The pattern of Bax expression was opposite to that of Bcl-2. Bax expression increased after reperfusion, with its peak at 1 h of reperfusion (P < 0.05), and then it decreased gradually to a minimum at 24 h after reperfusion (P < 0.05). On the other hand, inhibition of activation of ERK1/2 induced by PD98059, a specific upstream MEK inhibitor, had significant effects on Bcl-2 and Bax in GI-R. Compared with GI-R treatment only at 3 h of reperfusion, PD98059 reduced the number of Bcl-2 positive cells (0.58% of R3h group, P < 0.05) and Bcl-2 protein level (74% of R3h group, P < 0.05) but increased the number of Bax-positive cells (1.33-fold vs R3h group, P < 0.05) and Bax protein level (1.35-fold of R3h group, P < 0.05). CONCLUSION: These results indicated that the Bcl-2 and Bax played a pivotal role in the gastric mucosal I-R injury and repair by activation of ERK1/2.