A Quantitative Method for Determining Polarization of Neutrophil Adhesion Molecules Associated with Ischemia Reperfusion

Postconditioning Ozone Alleviates Ischemia-Reperfusion Injury and Enhances Flap Endurance in Rats

Introduction: Muscle-flap transferring is a routine approach utilized in reconstructive operations; however, flap morbidity is often a source of post-operative difficulty. Ischemia-Reperfusion Injury (IRI) is an important contributor to the viability of flaps after transferring. The goal of this research was for assess the probable useful impacts of ozone on flap survival in a rat muscle-flap design. Materials and Methods: We examined the effects of postconditioning ozone administration on viability of pedicled composite flaps. Twenty-eight Wistar rats were randomized into four groups: sham-operated (S), ischemia-reperfusion (IR), sham-operated + ozone (O), IR + ozone (IR + O), respectively. The animals were sacrificed on the eighth day. In a general histological evaluation, flap tissues were examined with a light microscope, and apoptotic cells were counted. The Apoptotic Index (AI) was then calculated. Flap-tissue samples were sent for analyses of malondialdehyde (MDA), catalase (CAT), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and protein carbonyl (PCO), and blood samples were sent for analyses of Total Oxidant Score (TOS), and Total Antioxidant Capacity (TAC). Data were evaluated statistically using the Kruskal-Wallis test. Results: The histomorphometric score was remarkably greater in O (p = .002). The AI was greater in IR (p = .002). The antioxidant parameters values as regards SOD, GSH-Px, CAT, and TAC were found to be greater in O (p < .005). The oxidant parameters values as regards MDA, PCO, TOS were found to be greater in IR (p < .005). Discussion: The current research indicates that ozone application can attenuate the muscle-flap injury brought about by IR through triggering the increase of the antioxidant capacity.

Hyperbaric Oxygen Inhibits Reperfusion-Induced Neutrophil Polarization and Adhesion Via Plasmin-Mediated VEGF Release

Background:

Ischemia-reperfusion (IR) injury is seen in many settings such as free flap salvage and limb replantation/revascularization. The consequences—partial/total flap loss, functional muscle loss, or amputation—can be devastating. Of the treatment options available for IR injury, hyperbaric oxygen (HBO) is the most beneficial. HBO inhibits neutrophil-endothelial adhesion through interference of CD18 neutrophil polarization in IR, a process mediated by nitric oxide. The purposes of this study were to examine the involvement of vascular endothelial growth factor (VEGF) in the beneficial HBO effect on CD18 polarization and neutrophil adhesion and investigate the effect of plasmin on VEGF expression in skeletal muscle following IR injury.

Methods:

A rat gracilis muscle model of IR injury was used to evaluate the effect of VEGF in IR, with and without HBO, on neutrophil CD18 polarization and adhesion in vivo and ex vivo. Furthermore, we investigated the effects that plasmin has on VEGF expression in gracilis muscle and pulmonary tissue by blocking its activation with alpha-2-antiplasmin.

Results:

HBO treatment following IR injury significantly decreased neutrophil polarization and adhesion ex vivo compared with the IR group. Anti-VEGF reversed the beneficial HBO effect after IR with polarization and adhesion. In vivo adhesion was also increased by anti-VEGF. HBO treatment of IR significantly increased the VEGF protein in both gracilis and pulmonary vasculature. Alpha-2-antiplasmin significantly reversed the HBO-induced increase of VEGF in gracilis muscle.

Conclusions:

These results suggest that HBO inhibits CD18 polarization and neutrophil adhesion in IR injury through a VEGF-mediated pathway involving the extracellular matrix plasminogen system.

Ischaemia-reperfusion injury and hyperbaric oxygen pathways: a review of cellular mechanisms

Ischaemia-induced tissue injury has wide-ranging clinical implications including myocardial infarction, stroke, compartment syndrome, ischaemic renal failure and replantation and revascularization. However, the restoration of blood flow produces a 'second hit' phenomenon, the effect of which is greater than the initial ischaemic event and characterizes ischaemia-reperfusion (IR) injury. Some examples of potential settings of IR injury include: following thrombolytic therapy for stroke, invasive cardiovascular procedures, solid organ transplantation, and major trauma resuscitation. Pathophysiological events of IR injury are the result of reactive oxygen species (ROS) production, microvascular vasoconstriction, and ultimately endothelial cell-neutrophil adhesion with subsequent neutrophil infiltration of the affected tissue. Initially thought to increase the amount of free radical oxygen in the system, hyperbaric oxygen (HBO) has demonstrated a protective effect on tissues by influencing the same mechanisms responsible for IR injury. Consequently, HBO has tremendous therapeutic value. We review the biochemical mechanisms of ischaemia-reperfusion injury and the effects of HBO following ischaemia-reperfusion.

Effects of taurine on reperfusion injury

Taurine is an organic acid, which has a very important function in the human body. Recently, the antioxidant property of taurine has been much emphasised. In this study, the gracilis muscle flap model was used to investigate the effect of taurine in ischaemia/reperfusion injury in rats. Totally 32 Sprague-Dawley rats were divided into two groups: control group (n = 16) and the treatment group with taurine (n = 16). After elevation of the gracilis muscle flap, 4 h of ischaemia was performed in both groups. Thirty min before the reperfusion, taurine (200 mg kg(-1)) was injected intravenously. After 24 h of reperfusion, the amount of malondialdehyde (MDA), tissue water content and flap viability were evaluated. After 72 h of reperfusion, histological findings were evaluated. Amount of MDA and tissue water content were significantly lower (p < 0.005), and the flap viability was significantly higher (p < 0.005) in the treatment group 24 h after reperfusion. On comparing the outcomes of histological analysis between control and treatment groups, the amounts of collagen, fibroblast and angiogenesis in treatment group were significantly higher than those in the control group. However, the amount of polymorphonuclear leucocyte and tissue necrosis in the treatment group were significantly lower than in the control group. Our results showed that taurine played an important role in the process of ischaemia/reperfusion injury and presented certain protective effects with the improvement in flap survival after ischaemia/reperfusion injury.

Hyperbaric oxygen inhibits ischemia-reperfusion-induced neutrophil CD18 polarization by a nitric oxide mechanism

BACKGROUND

Hyperbaric oxygen decreases ischemia-reperfusion-induced neutrophil/intercellular adhesion molecule-1 adhesion by blocking CD18 polarization. The purpose of this study was to evaluate whether this hyperbaric oxygen effect is nitric oxide dependent and to determine whether nitric oxide synthase is required.

METHODS

A gracilis muscle flap was raised in nine groups of male Wistar rats. Global ischemic injury was induced by clamping the gracilis muscle pedicle artery and vein for 4 hours. The hyperbaric oxygen treatment consisted of 100% oxygen at 2.5 atm absolute during the last 90 minutes of ischemia. Groups were repeated with and without various nitric oxide synthase inhibitors and carboxy-2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide (C-PTIO), a nitric oxide scavenger. Normal neutrophils were exposed to activated plasma on intercellular adhesion molecule-1-coated coverslips (percentage adherent) and labeled with fluorescein isothiocyanate/antirat-CD11b for confocal microscopy (percentage polarized). The percentage of adherent and polarized cells was reported as mean + or - SEM. Statistical analysis was by analysis of variance. A value of p < or = 0.05 was considered significant.

RESULTS

C-PTIO-treated ischemia-reperfusion/hyperbaric oxygen plasma showed a significant increase in the percentage polarization of CD18 compared with ischemia-reperfusion/hyperbaric oxygen-untreated plasma from 4.1 + or - 2.5 percent to 33.7 + or - 7.7 percent (p < or = 0.05). The nitric oxide scavenger C-PTIO also increased the percentage of adherent cells from 1.6 + or - 0.4 percent to 20.3 + or - 5.9 percent (p < or = 0.05). Administration of N-nitro-L-arginine methyl ester and other nitric oxide synthase inhibitors before hyperbaric oxygen treatment restored neutrophil adhesion and CD18 polarization to ischemia-reperfusion control values, significantly greater than ischemia-reperfusion/hyperbaric oxygen alone.

CONCLUSION

These results suggest that the hyperbaric oxygen reduction of ischemia-reperfusion-induced neutrophil polarization of CD18 and adherence to intercellular adhesion molecule-1 is mediated through a nitric oxide mechanism that requires nitric oxide synthase.

Fluorescence-based assays for in vitro analysis of cell adhesion and migration

Cell adhesion and cell migration are two primary cellular phenomena for which in vitro approaches may be exploited to effectively dissect the individual events and underlying molecular mechanisms. The use of assays dedicated to the analysis of cell adhesion and migration in vitro also afford an efficient way of conducting larger basic and applied research screenings on the factors affecting these processes and are potentially exploitable in the context of routine diagnostic, prognostic, and predictive tests in the biological and medical fields. Therefore, there is a longstanding continuum in the interest in devising more rationale such assays and major contributions in this direction have been provided by the advent of procedures based on fluorescence cell tagging, the design of instruments capable of detecting fluorescent signals with high sensitivity, and informatic tools allowing sophisticated elaboration of data generated through these instruments. In this report, we describe three representative fluorescence-based model assays for the qualitative and quantitative assessment of cell adhesion and cell locomotion in static and dynamic conditions. The assays are easily performed, accurate and reproducible, and can be automated for high-to-medium throughput screenings of cell behavior in vitro. Performance of the assays involves the use of certain dedicated disposable accessories, which are commercially available, and a few instruments that, due to their versatility, can be regarded as constituents of a more generic laboratory setup.

Potential of 3,4-dihydroxy-phenyl lactic acid for ameliorating ischemia-reperfusion-induced microvascular disturbance in rat mesentery

This study intended to examine the effect of 3,4-dihydroxy-phenyl lactic acid (DLA), a major ingredient of Salvia miltiorrhiza, on ischemia-reperfusion (I/R)-induced rat mesenteric microcirculatory injury. DLA (5 mg.kg(-1).h(-1)), superoxide dismutase (SOD, 12,000 U.kg(-1).h(-1)), or catalase (CAT, 20 mg/kg) was continuously infused either starting from 10 min before the ischemia or 10 min after the initiation of reperfusion. The venule diameter, number of adherent leukocytes, FITC-albumin leakage, dihydrorhodamine 123 fluorescence, and mast cell degranulation were determined using an intravital microscope. The production of hydrogen peroxide (H(2)O(2)) and the expression of adhesion molecules CD11b/CD18 in neutrophils were evaluated by in vitro experiments. The results showed that pretreatment with DLA significantly reduced peroxide production in and leukocyte adhesion to venular wall, albumin leakage, and mast cell degranulation induced by I/R. The DLA posttreatment exerted an ameliorating effect on I/R-induced disorders as well, characterized by inhibiting further increase in peroxide production in venular wall and albumin leakage and diminishing the number of leukocytes that had adhered to the venular wall. In vitro experiments revealed that treatment with DLA significantly attenuated TNF-alpha plus fMLP-evoked production of H(2)O(2) and the H(2)O(2)-elicited expression of CD11b/CD18 on neutrophils. SOD and CAT manifested similarly but with the exception that either SOD or CAT were unable to retrieve the adherent leukocytes if administrated after initiation of reperfusion and to depress the H(2)O(2)-induced expression of CD11b/CD18 on neutrophils. It is concluded that DLA protects from and ameliorates the I/R-induced microcirculatory disturbance by interfering with both peroxide production and adhesion molecule expression.

Metabolomic biomarkers in a model of asthma exacerbation: urine nuclear magnetic resonance

RATIONALE

Airway obstruction in patients with asthma is associated with airway dysfunction and inflammation. Objective measurements including sputum analysis can guide therapy, but this is often not possible in typical clinical settings. Metabolomics is the study of molecules generated by metabolic pathways. We hypothesize that airway dysfunction and inflammation in an animal model of asthma would produce unique patterns of urine metabolites measured by multivariate statistical analysis of high-resolution proton nuclear magnetic resonance ((1)H NMR) spectroscopy data.

OBJECTIVES

To develop a noninvasive means of monitoring asthma status by metabolomics and urine sampling.

METHODS

Five groups of guinea pigs were studied: control, control treated with dexamethasone, sensitized (ovalbumin, administered intraperitoneally), sensitized and challenged (ovalbumin, administered intraperitoneally, plus ovalbumin aerosol), and sensitized-challenged with dexamethasone. Airway hyperreactivity (AHR) to histamine (administered intravenously) and inflammation were measured. Multivariate statistical analysis of NMR spectra based on a library of known urine metabolites was performed by partial least-squares discriminant analysis. In addition, the raw NMR spectra exported as xy-trace data underwent linear discriminant analysis.

MEASUREMENTS AND MAIN RESULTS

Challenged guinea pigs developed AHR and increased inflammation compared with sensitized or control animals. Dexamethasone significantly improved AHR. Using concentration differences in metabolites, partial least-squares discriminant analysis could discriminate challenged animals with 90% accuracy. Using only three or four regions of the NMR spectra, linear discriminant analysis-based classification demonstrated 80-90% separation of the animal groups.

CONCLUSIONS

Urine metabolites correlate with airway dysfunction in an asthma model. Urine NMR analysis is a promising, noninvasive technique for monitoring asthma in humans.

Ischemia/reperfusion-induced necrosis and apoptosis in the cells isolated from rat skeletal muscle

Necrosis was considered to be the solo mechanism for ischemia/reperfusion (I/R)-induced cell death. Recent evidence from I/R models of the heart, liver, kidney, and brain indicates that apoptosis is a major contributor to I/R-induced cell death. However, evidence of I/R-induced apoptosis in skeletal muscle is sparse and divided. The purpose for the present study was to investigate I/R-induced necrosis and apoptosis in the cells isolated from rat skeletal muscle. A rat gracilis muscle model was used. After surgical preparation, clamps were applied on the vascular pedicle to create 4 h of ischemia and released for 24 h of reperfusion (I/R, n = 10). Clamping was omitted in sham I/R rats (sham I/R, n = 10). The muscle samples were harvested after 24 h of reperfusion for the process of cell isolation. Cells were stained by Propidium Iodide (PI) or Annexin V-FITC or both. Twenty thousand cells from each muscle sample were scanned and analyzed by flow cytometry. The average percentage of live cells was 45 +/- 2% in the I/R group versus 65 +/- 3% in the sham I/R group (p < 0.01). The average percentage of necrotic cells was 18 +/- 1% in I/R versus 12 +/- 1% in sham I/R (p < 0.01). The average percentage of apoptotic cells was 40 +/- 3% in I/R versus 27 +/- 3% in sham I/R (p < 0.01). Our results clearly demonstrated that I/R not only causes necrosis, but also accelerates apoptosis in the cells isolated from rat skeletal muscle.

Digital image analysis of cytoskeletal F-actin disintegration in renal microvascular endothelium following ischemia/reperfusion

BACKGROUND

Damaged and/or dysfunctional microvascular endothelium has been implicated in the pathogenesis of ischemic acute renal failure (ARF). Rapidly occurring changes in the endothelial F-actin cytoskeleton as observed in vitro might be responsible, but have been proven difficult to measure accurately in situ. Therefore, the purpose of this study was to examine several methods of digital image analysis in order to quantify the alterations of endothelial F-actin after renal ischemia and reperfusion (I/R), and to relate these to deterioration of renal function.

METHODS

Frozen sections of Sham and I/R rat kidneys were fixed in 4% formaldehyde and stained with rhodamine-phalloïdin. Microvascular structures were captured using a 3i Marianastrade mark digital imaging fluorescence microscope workstation. Images were analyzed using 3i SlideBooktrade mark software, employing several masking techniques and line-scans.

RESULTS

Digital image analysis demonstrated a decrease in the mean intensity of rhodamine-phalloïdin fluorescence after I/R from 1030 +/- 187 to 735 +/- 121 a.u. (arbitrary units, mean +/- SD, n = 7). The number of F-actin fragments per pixel increased from (15.8 +/- 4.9) x 10(-5) to (20.7 +/- 3.5) x 10(-5) (n = 7), indicating cytoskeletal fragmentation. In addition, line-scan analysis demonstrated a disturbed spatial orientation of the F-actin cytoskeleton after I/R. Finally, the loss of F-actin correlated with a rise in plasma creatinine.

CONCLUSIONS

The methods of digital image analysis described in the present study demonstrate that renal I/R induces profound changes in the F-actin cytoskeletal structure of microvascular endothelial cells, implicating an injured and dysfunctional microvascular endothelium, which may contribute to acute renal failure (ARF).

Sulforaphane enhances aquaporin-4 expression and decreases cerebral edema following traumatic brain injury

Brain edema, the infiltration and accumulation of excess fluid causing an increase in brain tissue volume, often leads to a rise in intracranial pressure and is a key contributor to the morbidity and mortality associated with traumatic brain injury (TBI). The cellular and molecular mechanisms contributing to the development/resolution of TBI-associated brain edema are poorly understood. Aquaporin-4 (AQP4) water channel is expressed at high levels in brain astrocytes, and the bidirectional transport of water through these channels is critical for the maintenance of brain water homeostasis. By using a rodent injury model, we show that TBI decreased AQP4 level in the injury core and modestly increased it in the penumbra region surrounding the core. Postinjury administration of sulforaphane (SUL), an isothiocyanate present in abundance in cruciferous vegetables such as broccoli, attenuated AQP4 loss in the injury core and further increased AQP4 levels in the penumbra region compared with injured animals receiving vehicle. These increases in AQP4 levels were accompanied by a significant reduction in brain edema (assessed by percentage water content) at 3 days postinjury. These findings suggest that the reduction of brain edema in response to SUL administration could be due, in part, to water clearance by AQP4 from the injured brain.

Sulforaphane reduces infarct volume following focal cerebral ischemia in rodents

Stroke is the third leading cause of death and disability in the United States. As several biochemical mechanisms have been proposed to contribute to stroke pathophysiology, treatments acting on multiple targets may be desirable. Sulforaphane (SUL), a naturally occurring isothiocyanate present in cruciferous vegetables, has been shown to induce the expression of multiple NF-E2-related factor-2 (Nrf2) responsive genes. In the present study, we demonstrate that systemically administered SUL can enter the brain as determined by increased mRNA and protein levels of the Nrf2-responsive gene heme oxygenase 1 (HO-1). Delayed administration (15 min) of a single dose of SUL significantly decreased cerebral infarct volume following focal ischemia, suggesting a potential therapeutic value for this compound.