Restoration of the Mucosal IgA Response by Improving CD4+ T Pyroptosis Fails to Attenuate Gut Bacterial Translocation and Organ Damage After LPS Attack.

BACKGROUND: Currently, the mechanisms of impaired gut mucosal immunity in sepsis remain unclear. Gut immunoglobulin A (IgA) is an important defense mechanism against invasive pathogens, and CD4+ T cells regulate the IgA response. AIM: We aimed to verify the hypothesis indicating that CD4+ T pyroptosis induced by lipopolysaccharide (LPS) leads to an impaired gut IgA response and subsequent bacterial translocation and organ damage. METHODS: Cultured CD4+ T cells and mice were manipulated with LPS, and pyroptosis was improved by A438079 or adoptive CD4+ T cell transfer. The changes demonstrated in pyroptosis-related molecules, cytotoxicity and CD4+ T cells were examined to determine CD4+ T pyroptosis. The changes demonstrated in IgA+ B cells, AID (key enzyme for immunoglobulins) and IgA production and function were examined to evaluate the IgA response. Serum biomarkers, bacterial colonies and survival analysis were detected for bacterial translocation and organ damage. RESULTS: LPS attack induced CD4+ T pyroptosis, as evidenced by increased expression of P2X7, Caspase-11 and cleaved GSDMD, which elevated cytotoxicity and decreased CD4+ T cells. Decreased CD4+ T subsets (Foxp3+ T and Tfh cells) influenced the IgA response, as evidenced by lower AID expression, which decreased IgA+ B cells and IgA production and function. A438079 or cell transfer improved the IgA response but failed to reduce the translocation of gut pathogens, damage to the liver and kidney, and mortality of mice. CONCLUSION: LPS attack results in CD4+ T pyroptosis. Improvement of pyroptosis restores the mucosal IgA response but fails to ameliorate bacterial translocation and organ damage.

Controlling Drain Side Tunneling Barrier Width in Electrically Doped PNPN Tunnel FET.

In this paper, we propose and investigate an electrically doped (ED) PNPN tunnel field effect transistor (FET), in which the drain side tunneling barrier width is effectively controlled to obtain a suppressed ambipolar current. We present that the proposed PNPN tunnel FETs can be realized without chemically doped junctions by applying the polarity bias concept to a doped N+/P- starting structure. Using numerical device simulations, we demonstrate how the tunneling barrier width on the drain side can be influenced by several design parameters, such as the gap length between the channel and the drain (Lgap), the working function of the polarity gate, and the dielectric material of the spacer. The simulation results show that an ED PNPN tunneling FET with an ED drain, which has been explored for the first time, exhibits a low ambipolar current of 5.87 × 10-16 A/µm at a gap length of 20 nm. The ambipolar current is reduced by six orders of magnitude compared to that which occurs with a conventional ED PNPN tunnel FET with a uniformly doped drain, while the average subthreshold slope and the ON state and OFF state currents remained nearly identical.

Dexmedetomidine Alleviates Gut-Vascular Barrier Damage and Distant Hepatic Injury Following Intestinal Ischemia/Reperfusion Injury in Mice.

BACKGROUND: Intestinal ischemia/reperfusion (I/R) challenge often results in gut barrier dysfunction and induces distant organ injury. Dexmedetomidine has been shown to protect intestinal epithelial barrier against I/R attack. The present study aims to investigate the degree to which intestinal I/R attack will contribute to gut-vascular barrier (GVB) damage, and to examine the ability of dexmedetomidine to minimize GVB and liver injuries in mice. METHODS: In vivo, intestinal ischemic challenge was induced in mice by clamping the superior mesenteric artery for 45 minutes. After clamping, the mice were subjected to reperfusion for either 2, 4, 6, or 12 hours. Intraperitoneal injection of dexmedetomidine 15, 20, or 25 µg·kg-1 was performed intermittently at the phase of reperfusion. For the in vitro experiments, the challenge of oxygen-glucose deprivation/reoxygenation (OGD/R) was established in cultured vascular endothelial cells, and dexmedetomidine (1 nM) was used to treat the cells for 24 hours. Moreover, in vivo and in vitro, SKL2001 (a specific agonist of ß-catenin) or XAV939 (a specific inhibitor of ß-catenin) was applied to determine the role of ß-catenin in the impacts provided by dexmedetomidine. RESULTS: The attack of intestinal I/R induced GVB damage. The greatest level of damage was observed at 4 hours after intestinal reperfusion. There was a significant increase in plasmalemma vesicle-associated protein-1 (PV1, a specific biomarker for endothelial permeability) expression (5.477 ± 0.718 vs 1.000 ± 0.149; P < .001), and increased translocation of intestinal macromolecules and bacteria to blood and liver tissues was detected (all P < .001). Liver damages were observed. There were significant increases in histopathological scores, serum parameters, and inflammatory factors (all P < .001). Dexmedetomidine 20 µg·kg-1 reduced PV1 expression (0.466 ± 0.072 vs 1.000 ± 0.098; P < .001) and subsequent liver damages (all P < .01). In vitro, dexmedetomidine significantly improved vascular endothelial cell survival (79.387 ± 6.447% vs 50.535 ± 1.766%; P < .001) and increased the productions of tight junction protein and adherent junction protein (all P < .01) following OGD/R. Importantly, in cultured cells and in mice, ß-catenin expression significantly decreased (both P < .001) following challenge. Dexmedetomidine or SKL2001 upregulated ß-catenin expression and produced protective effects (all P < .01). However, XAV939 completely eliminated the protective effects of dexmedetomidine on GVB (all P < .001). CONCLUSIONS: The disruption of GVB occurred following intestinal I/R. Dexmedetomidine alleviated I/R-induced GVB impairment and subsequent liver damage.

HMGB1 signaling-regulated endoplasmic reticulum stress mediates intestinal ischemia/reperfusion-induced acute renal damage.

BACKGROUND: Ischemia/reperfusion of the intestine often leads to distant organ injury, but the mechanism of intestinal ischemia/reperfusion-induced renal dysfunction is still not clear. The present study aimed to investigate the mechanisms of acute renal damage after intestinal ischemia/reperfusion challenge and explore the role of released high-mobility group box-1 in this process. METHODS: Intestinal ischemia/reperfusion was induced in male Sprague-Dawley rats by clamping the superior mesenteric artery for 1.5 hours. At different reperfusion time points, anti-high-mobility group box-1 neutralizing antibodies or ethyl pyruvate were administered to neutralize or inhibit circulating high-mobility group box-1, respectively. RESULTS: Significant kidney injury was observed after 6 hours of intestinal reperfusion, as indicated by increased serum levels of urea nitrogen and creatinine, increased expression of neutrophil gelatinase-associated lipocalin, interleukin-6, and MIP-2, and enhanced cell apoptosis, as indicated by cleaved caspase 3 levels in renal tissues. The levels of phosphorylated eIF2ɑ, activating transcription factor 4, and C/EBP-homologous protein (CHOP) were markedly elevated, indicating the activation of endoplasmic reticulum stress in the impaired kidney. High-mobility group box-1 translocated to cytoplasm in the intestine and serum concentrations of high-mobility group box-1 increased notably during the reperfusion phase. Both anti-high-mobility group box-1 antibodies and ethyl pyruvate treatment significantly reduced serum high-mobility group box-1 concentrations, attenuated endoplasmic reticulum stress in renal tissue and inhibited the development of renal damage. Moreover, the elevated expression of receptor for advanced glycation end products in the kidneys after intestinal ischemia/reperfusion was abrogated after high-mobility group box-1 inhibition. CONCLUSION: These results suggested that high-mobility group box-1 signaling regulated endoplasmic reticulum stress and promoted intestinal ischemia/reperfusion-induced acute kidney injury. High-mobility group box-1 neutralization/inhibition might serve as a pharmacological intervention strategy for these pathophysiological processes.

Terlipressin relieves intestinal and renal injuries induced by acute mesenteric ischemia via PI3K/Akt pathway.

Background: To date, the effect of vasopressin on organ damages after acute mesenteric ischemia (MI) remains poorly understood. Aims: To investigate the effect of terlipressin, a selective vasopressin V1 receptor agonist, versus norepinephrine on the intestinal and renal injuries after acute MI, and to explore the underlying mechanism of terlipressin. Methods: Acute MI model was produced by clamping the superior mesenteric artery for 1 hour. Immediately after unclamping, terlipressin or norepinephrine was intravenously administered for 2 hours. Meanwhile, in vitro, RAW264.7 cells were treated with lipopolysaccharide or lipopolysaccharide+terlipressin. In addition, wortmannin was used to determine the role of phosphoinositide 3-kinase (PI3K)/ protein kinase B (Akt) pathway in the potential impacts of terlipressin. Results: MI led to severe hypotension, caused notable intestinal and renal impairments and resulted in high mortality, which were markedly improved by terlipressin or norepinephrine. Terlipressin increased mean arterial pressure, decreased intestinal epithelial cell apoptosis, inhibited the generation of M1 macrophage in intestinal and renal tissues, and hindered the release of inflammatory cytokines after MI. Moreover, in cultured macrophages, terlipressin reduced the mRNA level of specific M1 markers and the release of inflammatory cytokines caused by lipopolysaccharide challenge. Wortmannin decreased the expression of PI3K and Akt induced by terlipressin in cells and in tissues, and abolished the above protective effects conferred by terlipressin. Conclusions: Terlipressin or norepinephrine could effectively improve organ damages and mortality after acute MI. Terlipressin elevates blood pressure and inhibits intestinal epithelial apoptosis and macrophage M1 polarization via the PI3K/Akt pathway.

Activation of PD-1 Protects Intestinal Immune Defense Through IL-10/miR-155 Pathway After Intestinal Ischemia Reperfusion.

BACKGROUND: To date, mechanisms of intestinal immunoglobulin (Ig) dysfunction following intestinal ischemia/reperfusion (I/R) remain unclear. Programmed death 1 (PD-1) is associated with immune responses of lymphocytes. AIM: We aimed to verify the hypothesis that activation of PD-1 may improve intestinal immune dysfunction by regulating IL-10/miR-155 production after intestinal IR injury. METHODS: Intestinal I/R injury was induced in mice by clamping the superior mesenteric artery for 1 h followed by 2-h reperfusion. PD-L1 fusion Ig, anti-interleukin (IL)-10 monoclonal antibody (mAb), and microRNA (miR)-155 agomir were administered. PD-1 expression, IL-10 mRNA, and protein expression in Peyer's patches (PP) CD4+ cells were measured. MiR-155 levels, tumor necrosis factor (TNF)-α and IL-1ß concentration, and activation-induced cytidine deaminase (AID), a key enzyme for intestinal immune antibodies, in PP tissues were measured, respectively. Importantly, the production and cecal bacteria-binding capacity of IgA and IgM were detected. RESULTS: Intestinal I/R led to decreased PD-1 expression, imbalanced production, and impaired bacteria-binding capacity of IgA and IgM. Activating PD-1 by PD-L1 Ig facilitated IL-10 synthesis, then decreased miR-155 levels, and subsequently promoted AID expression and reduced TNF-α, IL-1ß concentration. Upregulation of AID improved the disruptions of intestinal immune barrier caused by IgA and IgM dysfunction. Anti-IL-10 mAb and miR-155 agomir abolished the protective effects of PD-L1 Ig on the intestinal immune defense. CONCLUSION: Activation of PD-1 with PD-L1 Ig relieves intestinal immune defensive injury through IL-10/miR-155 pathway following intestinal I/R attack. PD-1, IL-10, and miR-155 may be potential targets for the damages of intestinal barrier and immunity.

Terlipressin versus norepinephrine as infusion in patients with septic shock: a multicentre, randomised, double-blinded trial.

PURPOSE: Recent clinical data suggest that terlipressin, a vasopressin analogue, may be more beneficial in septic shock patients than catecholamines. However, terlipressin's effect on mortality is unknown. We set out to ascertain the efficacy and safety of continuous terlipressin infusion compared with norepinephrine (NE) in patients with septic shock. METHODS: In this multicentre, randomised, double-blinded trial, patients with septic shock recruited from 21 intensive care units in 11 provinces of China were randomised (1:1) to receive either terlipressin (20-160 µg/h with maximum infusion rate of 4 mg/day) or NE (4-30 µg/min) before open-label vasopressors. The primary endpoint was mortality 28 days after the start of infusion. Primary efficacy endpoint analysis and safety analysis were performed on the data from a modified intention-to-treat population. RESULTS: Between 1 January 2013 and 28 February 2016, 617 patients were randomised (312 to the terlipressin group, 305 to the NE group). The modified intention-to-treat population comprised 526 (85.3%) patients (260 in the terlipressin group and 266 in the NE group). There was no significant difference in 28-day mortality rate between the terlipressin group (40%) and the NE group (38%) (odds ratio 0.93 [95% CI 0.55-1.56]; p = 0.80). Change in SOFA score on day 7 was similar between the two groups: - 7 (IQR - 11 to 3) in the terlipressin group and - 6 (IQR - 10 to 5) in the NE group. There was no difference between the groups in the number of days alive and free of vasopressors. Overall, serious adverse events were more common in the terlipressin group than in the NE group (30% vs 12%; p < 0.001). CONCLUSIONS: In this multicentre, randomised, double-blinded trial, we observed no difference in mortality between terlipressin and NE infusion in patients with septic shock. Patients in the terlipressin group had a higher number of serious adverse events. TRIAL REGISTRATION: This trial is registered at ClinicalTrials.gov: ID NCT01697410.

Effect of Systolic Cardiac Function on Passive Leg Raising for Predicting Fluid Responsiveness: A Prospective Observational Study.

BACKGROUND: Passive leg raising (PLR) represents a "self-volume expansion (VE)" that could predict fluid responsiveness, but the influence of systolic cardiac function on PLR has seldom been reported. This study aimed to investigate whether systolic cardiac function, estimated by the global ejection fraction (GEF) from transpulmonary-thermodilution, could influence the diagnostic value of PLR. METHODS: This prospective, observational study was carried out in the surgical Intensive Care Unit of the First Affiliated Hospital of Sun Yat-sen University from December 2013 to July 2015. Seventy-eight mechanically ventilated patients considered for VE were prospectively included and divided into a low-GEF (<20%) and a near-normal-GEF (≥20%) group. Within each group, baseline hemodynamics, after PLR and after VE (250 ml 5% albumin over 30 min), were recorded. PLR-induced hemodynamic changes (PLR-Δ) were calculated. Fluid responders were defined by a 15% increase of stroke volume (SV) after VE. RESULTS: Twenty-five out of 38 patients were responders in the GEF <20% group, compared to 26 out of 40 patients in the GEF ≥20% group. The thresholds of PLR-ΔSV and PLR-Δ cardiac output (PLR-ΔCO) for predicting fluid responsiveness were higher in the GEF ≥20% group than in the GEF <20% group (ΔSV: 12% vs. 8%; ΔCO: 7% vs. 6%), with increased sensitivity (ΔSV: 92% vs. 92%; ΔCO: 81% vs. 80%) and specificity (ΔSV: 86% vs. 70%; ΔCO: 86% vs. 77%), respectively. PLR-Δ heart rate could predict fluid responsiveness in the GEF ≥20% group with a threshold value of -5% (sensitivity 65%, specificity 93%) but could not in the GEF <20% group. The pressure index changes were poor predictors. CONCLUSIONS: In the critically ill patients on mechanical ventilation, the diagnostic value of PLR for predicting fluid responsiveness depends on cardiac systolic function. Thus, cardiac systolic function must be considered when using PLR. TRIAL REGISTRATION: Chinese Clinical Trial Register, ChiCTR-OCH-13004027; http://www.chictr.org.cn/showproj.aspx?proj=5540.

Propofol Does Not Reduce Pyroptosis of Enterocytes and Intestinal Epithelial Injury After Lipopolysaccharide Challenge.

BACKGROUND: To date, mechanisms of sepsis-induced intestinal epithelial injury are not well known. P2X7 receptor (P2X7R) regulates pyroptosis of lymphocytes, and propofol is usually used for sedation in septic patients. AIMS: We aimed to determine the occurrence of enterocyte pyroptosis mediated by P2X7R and to explore the effects of propofol on pyroptosis and intestinal epithelial injury after lipopolysaccharide (LPS) challenge. METHODS: A novel regimen of LPS challenge was applied in vitro and in vivo. Inhibitors of P2X7R (A438079) and NLRP3 inflammasome (MCC950), and different doses of propofol were administered. The caspase-1 expression, caspase-3 expression, caspase-11 expression, P2X7R expression and NLRP3 expression, extracellular ATP concentration and YO-PRO-1 uptake, and cytotoxicity and HMGB1 concentration were detected to evaluate enterocyte pyroptosis in cultured cells and intestinal epithelial tissues. Chiu's score, diamine oxidase and villus length were used to evaluate intestinal epithelial injury. Moreover, survival analysis was performed. RESULTS: LPS challenge activated caspase-11 expression and P2X7R expression, enhanced ATP concentration and YO-PRO-1 uptake, and led to increased cytotoxicity and HMGB1 concentration. Subsequently, LPS resulted in intestinal epithelial damage, as evidenced by increased levels of Chiu's score and diamine oxidase, and shorter villus length and high mortality of animals. A438079, but not MCC950, significantly relieved LPS-induced enterocyte pyroptosis and intestinal epithelial injury. Importantly, propofol did not confer the protective effects on enterocyte pyroptosis and intestinal epithelia although it markedly decreased P2X7R expression. CONCLUSION: LPS attack leads to activation of caspase-11/P2X7R and pyroptosis of enterocytes. Propofol does not reduce LPS-induced pyroptosis and intestinal epithelial injury, although it inhibits P2X7R upregulation.

Terlipressin protects intestinal epithelial cells against oxygen-glucose deprivation/re-oxygenation injury via the phosphatidylinositol 3-kinase pathway.

Intestinal ischemia/reperfusion (I/R) injury is associated with a high morbidity and mortality. Vasopressin is administered to critically ill patients with potential intestinal I/R. However, the impacts of vasopressin on intestinal epithelia under ischemic/anoxic conditions remain unclear. The aim of the present study was to evaluate the effects of terlipressin, a highly selective vasopressin V1 receptor agonist, on oxygen and glucose deprivation/re-oxygenation (OGD/R)-induced damage in intestinal epithelial cells (IEC-6). IEC-6 cells were subjected to OGD for 4 h, followed by 4 h re-oxygenation. Terlipressin was incubated with cells for 4 h following OGD. Following OGD/R, IEC-6 cell viability, proliferation and apoptosis, as well as cell cycle dynamics, were assessed and the levels of tumor necrosis factor (TNF)-α and 15-F2t-isoprostane in the culture medium were measured. In addition, wortmannin, a specific phosphatidylinositol 3-kinase (PI3K) inhibitor, was administrated to investigate the mechanism of terlipressin action. The results demonstrated that IEC-6 cell viability and proliferation decreased, and cell apoptosis increased, following OGD/R. However, IEC-6 cell cycle dynamics did not significantly change 4 h after OGD. Incubation with 25 nM terlipressin significantly improved cell viability, proliferation and apoptosis. Furthermore, terlipressin inhibited the secretion of TNF-α and 15-F2t-isoprostane from IEC-6 cells following OGD/R. The aforementioned effects of terlipressin were completely abolished following the application of 2 µM wortmannin. Therefore, the current study demonstrated that terlipressin administration following OGD attenuates OGD/R-induced cell damage via the PI3K signaling pathway. These results may help physicians to better understand and more effectively use terlipressin in a clinical setting.

TGF-ß1 improves mucosal IgA dysfunction and dysbiosis following intestinal ischaemia-reperfusion in mice.

Intestinal ischaemia/reperfusion (I/R) severely disrupts gut barriers and leads to high mortality in the critical care setting. Transforming growth factor (TGF)-ß1 plays a pivotal role in intestinal cellular and immune regulation. However, the effects of TGF-ß1 on intestinal I/R injury remain unclear. Thus, we aimed to investigate the effects of TGF-ß1 on gut barriers after intestinal I/R and the molecular mechanisms. Intestinal I/R model was produced in mice by clamping the superior mesenteric artery for 1 hr followed by reperfusion. Recombinant TGF-ß1 was intravenously infused at 15 min. before ischaemia. The results showed that within 2 hrs after reperfusion, intestinal I/R disturbed intestinal immunoglobulin A class switch recombination (IgA CSR), the key process of mucosal IgA synthesis, and resulted in IgA dysfunction, as evidenced by decreased production and bacteria-binding capacity of IgA. Meanwhile, the disruptions of intestinal microflora and mucosal structure were exhibited. Transforming growth factor-ß1 activated IgA CSR as evidenced by the increased activation molecules and IgA precursors. Strikingly, TGF-ß1 improved intestinal mucosal IgA dysfunction, dysbiosis and epithelial damage at the early stage after reperfusion. In addition, SB-431542, a specific inhibitor of activating mothers against decapentaplegic homologue (SMAD) 2/3, totally blocked the inductive effect of TGF-ß1 on IgA CSR and almost abrogated the above protective effects on intestinal barriers. Taken together, our study demonstrates that TGF-ß1 protects intestinal mucosal IgA immunity, microbiota and epithelial integrity against I/R injury mainly through TGF-ß receptor 1/SMAD 2/3 pathway. Induction of IgA CSR may be involved in the protection conferred by TGF-ß1.

Decreased PD-1/PD-L1 Expression Is Associated with the Reduction in Mucosal Immunoglobulin A in Mice with Intestinal Ischemia Reperfusion.

BACKGROUND: Intestinal ischemia/reperfusion (I/R) disrupts intestinal mucosal integrity and immunoglobulin A (IgA) generation. It has recently been shown that the programmed cell death-1 receptor (PD-1) plays a crucial role in regulating intestinal secreted IgA (sIgA). AIMS: To evaluate changes in PD-1 and PD-ligand 1 (PD-L1) expression on Peyer's patches (PP) CD4(+) T cells and to investigate the correlation between PD-1/PD-L1 and intestinal IgA production/mucosal integrity in mice following intestinal I/R. METHODS: I/R injury was induced by clamping the superior mesenteric artery for 1 h followed by 2-h reperfusion. PD-1/PD-L1 expression on PP CD4(+) T cells was measured in I/R and sham-operated mice. Additionally, transforming growth factor-ß1 (TGF-ß1) and interleukin-21 (IL-21) mRNA in CD4(+) T cells and IgA(+) and IgM(+) in PP B cells, as well as intestinal mucosal injury and sIgA levels, were assessed. RESULTS: PD-1/PD-L1, TGF-ß1, and IL-21 expression was down-regulated after intestinal I/R. Furthermore, IgA(+) B cells decreased and IgM(+) B cells increased in mice with intestinal I/R. Importantly, decreased PD-1/PD-L1 expression was correlated with increased mucosal injury and decreased IgA levels, as well as with decreased TGF-ß1 and IL-21 expression. CONCLUSIONS: Intestinal I/R inhibits PD-1/PD-L1 expression on PP CD4(+) T cells, which was associated with an impaired intestinal immune system and mechanical barriers. Our study indicates that PD-1/PD-L1 expression on CD4(+) T cells may be involved in the pathogenesis of intestinal I/R injury.

Dexmedetomidine administration before, but not after, ischemia attenuates intestinal injury induced by intestinal ischemia-reperfusion in rats.

BACKGROUND: Intestinal ischemia-reperfusion (I/R) injury is a devastating complication in the perioperative period. Dexmedetomidine is commonly applied in the perioperative period. The authors aimed to determine the effects of different doses of dexmedetomidine (given before or after intestinal ischemia) on intestinal I/R injury and to explore the underlying mechanisms. METHODS: Intestinal I/R injury was produced in rat by clamping the superior mesenteric artery for 1 h followed by 2 h reperfusion. Intravenous infusion of dexmedetomidine was performed at 2.5, 5, and 10 µg · kg(-1) · h(-1) for 1 h before or after ischemic insult. In addition, yohimbine hydrochloride was administered intravenously to investigate the role of α2 adrenoreceptor in the intestinal protection conferred by dexmedetomidine. RESULTS: Intestinal I/R increased mortality of rats and caused notable intestinal injury, as evidenced by statistically significant increases in Chiu's scores; serum diamine oxidase and tumor necrosis factor-α concentration, accompanied by increases in the intestinal mucosal malondialdehyde concentration; myeloperoxidase activity; and epithelial cell apoptosis (all P < 0.05 vs. Sham). Except malondialdehyde and myeloperoxidase, all changes were improved by the administration of 5 µg · kg(-1) · h(-1) dexmedetomidine before ischemia (all P < 0.05 vs. Injury) but not after ischemia. Infusion of 2.5 µg · kg(-1) · h(-1) dexmedetomidine before or after ischemia produced no beneficial effects, and infusion of 10 µg · kg(-1) · h(-1) dexmedetomidine led to severe hemodynamic suppression. Yohimbine abolished the intestinal protective effect of the 5 µg · kg(-1) · h(-1) dexmedetomidine infusion before ischemia and was accompanied by the disappearance of its antiapoptotic and antiinflammatory effect. CONCLUSION: Dexmedetomidine administration before, but not after, ischemia dose-dependently protects against I/R-induced intestinal injury, partly by inhibiting inflammatory response and intestinal mucosal epithelial apoptosis via α2 adrenoreceptor activation.

[The study of the mechanism of the effect of heparin on tissue perfusion of sepsis patients].

OBJECTIVE: To assess the role of heparin administration in the early stage of sepsis and its mechanism of action. METHODS: This was a prospective study. One hundred and nineteen patients were enrolled in the study and were randomly divided into control group (64 cases) and therapy group (55 cases). Except the basic therapy of sepsis given to patients in both groups, the patients in the control group received normal saline, while the patients in the therapy group received heparin 2 mg.kg(-1).d(-1) with the aid of intravenous pump continuously after the onset of sepsis. The platelet count (PLT), D-dimer, and lactic acid in the blood were analyzed before therapy and on the 1st, 3rd, 5th and 10th day. The bleeding tendency was also observed. In every patient an acute physiology and chronic heath evaluation II (APACHE II) score was made. RESULTS: Patients in both groups had a similar APACHE II score. The pathogenetic and therapeutic condition were similar in both groups. The rate of the active bleeding in the therapy group was lower significantly than that of the control group (12.5% vs. 5.4%, P < 0.05). The PLT of the therapy group decreased on the 1st day, but began to rise on the 3rd day gradually, and up to the same level of the admission day on the 10th day. The PLT of the control group decreased progressively every day (P < 0.05 or P < 0.01). D-dimer in the therapy group raised significantly on the 1st day, but lowered to normal level after 3 days. D-dimer in the control group went up progressively every day (all P < 0.01). Lactic acid in the therapy group went up significantly on the 1st day (P < 0.01), but it no longer rose after 3 days (all P > 0.05). The lactic acid level in the control group rose progressively every day (all P < 0.01). There were no significant differences for the PLT, D-dimer, and lactic acid between the two groups before therapy and on the 1st day (all P > 0.05). However, on the 3rd, 5th and 10th day, the PLT in the therapy group was significant higher than that of the control group, the D-dimer and the lactic acid level in the therapy group were significantly lower than that of the control group (P < 0.05 or P < 0.01). CONCLUSION: The use of heparin at the earlier period of sepsis can inhibit the lowering of PLT and increase of D-dimer and lactic acid significantly, prevent microvascular thrombosis, improve the tissue perfusion, and decrease active bleeding.