Electrical field stimulation promotes anastomotic healing in poorly perfused rat colon.

INTRODUCTION: Hypoperfusion of the bowel is a risk factor for anastomotic failure. Electrical field stimulation has been shown to improve repair in ischemic tissue, but its influence in hypoperfused colon has not been investigated. The hypothesis of this experimental animal study was that electrical field stimulation improves anastomotic healing in ischemic bowel. MATERIALS AND METHODS: Thirty rats were divided evenly into three groups: control, ischemia/placebo, and ischemia/test group. Ischemia was induced by ligation of the arterial supply to the proximal colon. The watershed area was identified and transected. Field stimulation was achieved by application of negatively charged diethylaminoethyl Sephadex beads in methylcellulose gel to the colonic epithelium prior to anastomosis. The placebo group had methylcellulose gel only applied and control animals had anastomosis only. Anastomotic strength was measured using anastomotic bursting pressure and hydroxyproline content. Systemic effect was investigated via interleukin-6 and vascular endothelial growth factor assay. RESULTS: The ischemia/electrical field stimulation (EFS) group had significantly increased bursting pressure and hydroxyproline content in comparison with the placebo group (P < 0.001). Serum cytokine levels were unaffected. CONCLUSION: Negatively charged EFS improves anastomotic healing in hypoperfused colon without induction of systemic cytokines and has potential as a local treatment in high-risk bowel anastomosis.

The evolving role of taurolidine in cancer therapy.

BACKGROUND AND DESIGN: Taurolidine consists of two taurinamide rings derived from the naturally occurring amino acid taurine. It has been utilized to prevent adhesions, as an antimicrobial, and as an anti-inflammatory agent. More recently, it has been found to exert antineoplastic activity. We reviewed the literature regarding taurolidine and its role in cancer treatment. RESULTS AND CONCLUSION: Taurolidine induces cancer cell death through a variety of mechanisms. Even now, all the antineoplastic pathways it employs are not completely elucidated. It has been shown to enhance apoptosis, inhibit angiogenesis, reduce tumor adherence, downregulate proinflammatory cytokine release, and stimulate anticancer immune regulation following surgical trauma. Apoptosis is activated through both a mitochondrial cytochrome-c-dependent mechanism and an extrinsic direct pathway. A lot of in vitro and animal data support taurolidine's tumoricidal action. Taurolidine has been used as an antimicrobial agent in the clinical setting since the 1970s and thus far appears nontoxic. The nontoxic nature of taurolidine makes it a favorable option compared with current chemotherapeutic regimens. Few published clinical studies exist evaluating the role of taurolidine as a chemotherapeutic agent. The literature lacks a gold-standard level 1 randomized clinical trial to evaluate taurolidine's potential antineoplastic benefits. However, these trials are currently underway. Such randomized control studies are vital to clarify the role of taurolidine in modern cancer treatment.

Attenuation of lipopolysaccharide-mediated left ventricular dysfunction by glutamine preconditioning.

OBJECTIVE: Myocardial dysfunction is often seen during the inflammatory response to major surgery at 4 to 6h postoperatively. The aim of this study was to investigate the effect of glutamine pretreatment, as a means of preconditioning, on lipopolysaccharide-induced myocardial dysfunction. METHODS: C57BL/6 mice were randomized into four groups: Control; lipopolysaccharide; glutamine plus lipopolysaccharide; and Quercetin, an inhibitor of heat shock protein synthesis plus glutamine and lipopolysaccharide. Left ventricular function was assessed at 6h following lipopolysaccharide (LPS) insult by invasive hemodynamics. Heat shock protein (HSP)72 in heart tissue was determined by Western immunoblot at 12h after glutamine administration. RESULTS: Administration of lipopolysaccharide resulted in significant decrease in left ventricular end systolic pressure (LVESP) (69.1 +/- 2.52 mm Hg versus 106.3 +/- 3.36 mm Hg in controls), reduced dP/dtmax (4704.1 +/- 425.31 mm Hg/s versus 9389.8 +/- 999.4 mm Hg/s in controls), and the increase in left ventricular end diastolic pressure (LVEDP) (5.10 +/- 0.28 mm Hg versus 2.16 +/- 0.27 mm Hg in controls) (P < 0.05). Peritoneal injection of 25 g/kg of glutamine 12 h prior to lipopolysaccharide exposure induced HSP72 expression in heart tissues and attenuated lipopolysaccharide-induced left ventricular dysfunction: LVESP 85.94 +/- 3.8 mm Hg (P < 0.05), dP/dtmax 8331 +/- 425 mm Hg (P < 0.05), LVEDP 2.32 +/- 0.23 mm Hg (P < 0.01). Quercetin partially attenuated glutamine induced HSP72 expression and blocked the protective response of glutamine. CONCLUSION: These data demonstrate that cardioprotection with glutamine is associated with induction of HSP72 and may be an approach to activating the preconditioning response in the heart in clinical practise.

Contrast-induced nephrotoxicity: possible synergistic effect of stress hyperglycemia.

OBJECTIVE: Oxidative stress on the renal tubules has been implicated as a mechanism of injury in both stress hyperglycemia and contrast-induced nephrotoxicity. The purpose of this study was to determine whether the combination of these effects has a synergistic effect on accentuating renal tubular apoptosis and therefore increasing the risk of contrast-induced nephrotoxicity. MATERIALS AND METHODS: Dog kidney cells were incubated with 5- and 30-mmol/L glucose solutions and no glucose and then exposed for 2 hours to three types of contrast media-high osmolar (370 mg I/mL), low osmolar (300 mg I/mL), and isoosmolar (320 mg I/mL)-and a mannitol control solution. In an identical experiment, each group of cells was pretreated with an antioxidant-N-acetylcysteine or taurine-to evaluate the protective effect, if any. Apoptosis was assessed with fluorescence-activated cell sorter flow cytometry. RESULTS: The high-osmolar contrast medium was associated with significantly elevated levels of apoptosis compared with the mannitol control (percentage apoptosis, 27.98 +/- 1.08 vs 6.19 +/- 0.771; p < 0.001). This effect was less pronounced after incubation with the low-osmolar agent but was still significant (percentage apoptosis, 20.19 +/- 0.3665 vs 6.19 +/- 0.771; p < 0.001). The isosmolar agent did not have a significant effect. Both the high- and low-osmolar contrast media coupled with hyperglycemia (30-mmol/L glucose) were associated with a significantly increased level of apoptosis. In all contrast medium groups, taurine had a greater protective effect on attenuation of cell apoptosis than did N-acetylcysteine. CONCLUSION: The combination of contrast medium and an elevated glucose level has a synergistic effect on apoptosis. Taurine may be a more effective prophylactic antioxidant than the currently advocated antioxidant, N-acetylcysteine.

Taurine modulates neutrophil function but potentiates uropathogenic E. coli infection in the murine bladder.

Eradication of a urinary tract infection (UTI) appears to be related to a number of innate host defence mechanisms and their interactions with invading bacteria. Recurrent UTIs (rUTIs) pose a difficult problem in that these bacteria use both host and bacterial factors to evade elimination. Neutrophil bactericidal function is depressed, both systemically and in urine, in patients with a history of recurrent UTI. Taurine is a semi-essential amino acid and is successful in preserving neutrophil bactericidal function in urine. Taurine may preserve neutrophil function at the urothelium and thus aid UTI resolution. Adult female (6 weeks old) C57Bl/6 mice were randomised into three groups: a saline gavage only control group, a saline gavage + E. coli group, and a taurine gavage + E. coli group [21 g/70 kg taurine in 0.9% normal saline (N/S) for 5 days]. Whilst taurine gavage pre-treatment resulted in increased serum neutrophils respiratory burst activity, at the urothelial-endothelial interface it caused higher colony forming units in the urine and a higher incidence of E. coli invasion in the bladder wall with no evidence of increased bladder wall neutrophils infiltration on MPO assay of histological assessment. Histologically there was also evidence of reduced bladder inflammation and urothelial cell apoptosis. In conclusion, taurine effectively increases neutrophils activity but given its anti-inflammatory properties, at the expense of decreased urothelial-endothelial activation thus preventing clearance of active E. coli infection in the bladder. Despite the negative results, this study demonstrates the importance of modulating interactions at the urothelial interface.

Iodinated contrast media alter immune responses in pro-inflammatory states.

BACKGROUND: Hypertonic saline causes a transient elevation of blood osmolality and has been shown to alter cellular inflammatory responses in pro-inflammatory states. Intravascular administration of iodine contrast media also causes a transient elevation of blood osmolarity. PURPOSE: To investigate the effect of iodine contrast media on leukocyte-endothelial interaction in vivo using intravital microscopy. MATERIAL AND METHODS: Male Sprague-Dawley rats (n=36) were randomized into six groups and were treated with: saline, high osmolar contrast medium, low osmolar contrast medium, and endotoxin alone and in combination with the high and low osmolar contrast media. The effect on leukocyte-endothelial interaction in the post-mesenteric venules was observed using the technique of intravital microscopy. The sequence of leukocyte rolling velocity, leukocyte-endothelial cell adherence, and transmigration was recorded and analyzed at 10 min intervals to a maximum of 120 min. RESULTS: Endotoxin significantly decreased the rolling velocity and increased the adherence and transmigration of leukocytes in a time-dependent manner. Both types of iodine contrast media attenuated this pro-inflammatory response to endotoxin. This effect began between 60 and 70 min after the onset of the experiment. CONCLUSION: Hyperosmolar and lower osmolar iodine contrast media attenuate the pro-inflammatory leukocyte-endothelial response to endotoxin in vivo.

GLUT-1 expression and response to chemoradiotherapy in rectal cancer.

Preoperative chemoradiotherapy is used in locally advanced rectal cancer to reduce local recurrence and improve operability, however a proportion of tumors do not undergo significant regression. Identification of predictive markers of response to chemoradiotherapy would improve patient selection and may allow response modification by targeting of specific pathways. The aim of this study was to determine whether expression of glucose transporter-1 (GLUT-1) and p53 in pretreatment rectal cancer biopsies was predictive of tumor response to chemoradiotherapy. Immunohistochemical staining for GLUT-1 and p53 was performed on 69 pretreatment biopsies and compared to tumor response in the resected specimen as determined by the tumor regression grade (TRG) scoring system. GLUT-1 expression was significantly associated with reduced response to chemoradiotherapy and increasing GLUT expression correlated with poorer response (p=0.02). GLUT-1 negative tumors had a 70% probability of good response (TRG3/4) compared to a 31% probability of good response in GLUT-1 positive tumors. GLUT-1 may be a useful predictive marker of response to chemoradiotherapy in rectal cancer.

Should incidental asymptomatic angiographic stenoses and occlusions be treated in patients with peripheral arterial disease?

PURPOSE: The clinical importance of angiographically detected asymptomatic lower-limb stenoses and occlusions is unknown. This study aims to (i) assess the clinical outcome of asymptomatic lesions in the lower limb, (ii) identify predictors of clinical deterioration, and (iii) determine which asymptomatic lower-limb lesions should be treated at presentation. MATERIALS AND METHODS: All 918 patients undergoing peripheral angiography with or without angioplasty over a period of 7.5 years (January 1999 through June 2006) at a single institution were retrospectively evaluated. One hundred twenty-two patients (54% men; mean age, 70.3 years; age range, 41-91 y) with angiographic stenoses (> or =50%) or occlusions on the asymptomatic leg were included. The composite endpoint of interest was major adverse clinical outcome (MACO) of the asymptomatic limb at clinical follow-up, which was defined as the development of intermittent claudication (IC), critical limb ischemia (CLI), or need for subsequent endovascular or surgical revascularization. Actuarial freedom from MACO was assessed with Kaplan-Meier curves and multivariable Cox proportional-hazards regression. RESULTS: During a 4.2-year mean follow-up in 122 patients with significant concomitant asymptomatic disease, 32.8% of patients developed symptoms (13.9% with IC, 18.9% with CLI); 42.5% of these cases required revascularization. Cox regression revealed two independent predictors of MACO on the asymptomatic side: contralateral below-knee amputation (BKA; hazard ratio, 2.93; 95% CI, 1.21-7.10; P = .01) and statin treatment (hazard ratio, 3.56; 95% CI, 1.56-8.13; P = .003). CONCLUSIONS: Asymptomatic peripheral angiographic stenoses and occlusions become symptomatic in one third of patients, necessitating treatment in 13.9% overall. Previous contralateral BKA and statin use were independent predictors of adverse outcome in this population. Close clinical follow-up and appropriate risk factor modification are recommended.

Vascular endothelial growth factor is an autocrine survival factor for breast tumour cells under hypoxia.

Vascular endothelial growth factor (VEGF) is produced by most tumour types and stimulates the growth of new blood vessels in the tumour. The expansion of a solid tumour ultimately leads to the development of hypoxic regions, which increases VEGF production and further angiogenesis. In this study, we examined the role of VEGF in the survival of breast tumour cells under hypoxia. Murine 4T1 and human MDA-MB-231 tumour cells were cultured under normoxic and hypoxic growth conditions in the presence or absence of VEGF neutralising antibodies. Apoptosis was assessed in addition to changes in expression of the anti- and pro-apoptotic proteins, Bcl-2 and Bad, respectively. The effect of hypoxia on the novel VEGF receptor, NP1 (neuropilin-1) and the role of the PI3K (phosphatidylinositol-3-kinase) signalling pathway in response to VEGF were examined. VEGF blockade resulted in direct tumour cell apoptosis of both tumour cell lines under normoxia and hypoxia. While blocking VEGF resulted in a downregulation of hypoxia-induced Bcl-2 expression, there was a significant increase in the pro-apoptotic protein Bad relative to cells cultured under hypoxia alone. Both hypoxia and VEGF phosphorylated Akt. Neutralising antibodies to VEGF abrogated this effect, implicating the PI3K pathway in VEGF-mediated cell survival of mammary adenocarcinoma cells. This study demonstrates that VEGF acts as a survival factor not only for endothelial cells as previously thought, but also for some breast tumour cells, protecting them from apoptosis, particularly under hypoxic stress. The data presented provide an additional rationale for combining anti-VEGF strategies with conventional anti-cancer therapies such as chemotherapy and radiotherapy.

The Tromped: a solution for flight-related deep vein thrombosis?

Flight-related deep vein thrombosis (DVT) is well recognized. Reduced venous return occurs during immobility. This alteration in venous hemodynamics may contribute to DVT development. A prototype design of an in-flight exercise device to stimulate ambulatory bloodflow while seated has been developed, consisting of a foot pedal attached to a base by a hinge mechanism. Four devices of differing resistance were evaluated. Calf muscle pump function was assessed by air plethysmography in 10 healthy volunteers. Ejection volume fraction and RVF were determined in the standing position (control values) and were compared with those achieved by depression of the 4 devices while seated. Similar EVF and RVF values were achieved by the control and 2 of the devices. Plantar flexion against a predetermined resistance can effectively activate the calf muscle pump while seated and may reduce the incidence of flight-related DVT.

Two-week treatment with pravastatin improves ventriculo-vascular haemodynamic interactions in young men with type 1 diabetes.

Young patients with diabetes but without established vascular disease have altered conduit and resistance artery reactivity. Early endothelial dysfunction is an initial step in atherogenesis: reductions in nitric oxide (NO) production in these vascular beds are implicated. The study aim was two-fold: first, to detect baseline abnormalities in cardiac function, conduit vessels and the microcirculation using applanation tonometry, brachial artery ultrasound and laser Doppler fluximetry, respectively; and second, to investigate any modification in these parameters with the use of pravastatin. Nine young men with diabetes and normoalbuminuria were randomised in a double-blind cross-over fashion to placebo or pravastatin (40 mg) treatment for two weeks. They underwent scans on three separate occasions. Control patients (n=12) underwent a baseline scan but were not given any drug treatment. It was found that patients with diabetes had significantly higher systolic and diastolic blood pressures, heart rate and Buckberg index (propensity to myocardial ischaemia). Brachial artery reactivity and microcirculatory dilation were both reduced. Levels of von Willebrand Factor, a marker of endothelial damage, were also elevated. Pravastatin treatment restored these sub-clinical abnormalities towards normal levels. In conclusion, pravastatin improves vascular abnormalities in young male patients with diabetes through alterations in microcirculation and conduit vessel function, with secondary myocardial effects. This may be of benefit in preventing end-organ injury.

Tourniquet injuries: pathogenesis and modalities for attenuation.

Although it is widespread in orthopaedic surgery, tourniquet use is associated with appreciable morbidity and even mortality. We review the use of tourniquets, highlighting how an understanding of their design and application can reduce the complications and injuries associated with their use. We also review the attempts being made to modulate these injuries through physical and pharmacological advances, in particular looking at the phenomenon of preconditioning.

Tumour hypoxia, chemotherapeutic resistance and hypoxia-related therapies.

Tissue hypoxia occurs where there is an imbalance between oxygen supply and consumption. Hypoxia occurs in solid tumours as a result of an inadequate supply of oxygen, due to exponential cellular proliferation and an inefficient vascular supply. It is an adverse prognostic indicator in cancer as it is associated with tumour progression and resistance to therapy. The expression of several genes controlling tumour cell survival are regulated by hypoxia, e.g., growth factors governing the formation of new blood vessels, and hypoxia-responsive transcription factors modulating the expression of genes, which promote tumour cell survival. This review outlines some of the pathways by which tumour hypoxia leads to chemotherapeutic resistance, directly due to lack of oxygen availability, and indirectly due to alterations in the proteome/genome, angiogenesis and pH changes. Some innovative therapies are also detailed which may potentially minimise or eliminate these problems associated with targeting solid tumours.

Taurolidine attenuates the hemodynamic and respiratory changes associated with endotoxemia.

The purpose of this study was to determine if prereatment with taurolidine, a known anti-endotoxin agent, would attenuate the hemodynamic and respiratory responses associated with endotoxin induced lung injury in a large animal model in a randomized controlled study under license from the Department of Health. All animals underwent a general anesthetic. Vascular catheters were placed in the femoral artery and in the femoral vein. A Swan-Ganz Catheter was inserted for measurement of pulmonary artery pressure. Animals were randomized into three groups: Control, with measurements taken at baseline and half hourly up to 90 min; Endotoxin, receiving 5microg/Kg E. coli endotoxin intravenously after baseline measurements; and Endotoxin + Taurolidine, receiving 5g of taurolidine via intraperitoneal infusion 1 h before endotoxin administration. Main outcome measures were mean systemic arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), arterial oxygen tension (pO2), serum endotoxin concentration, and pulmonary myeloperoxidase. Endotoxin induced a significant lung injury characterized by an increase in pulmonary artery pressure, hypoxia, and systemic hypotension. Pretreatment with intraperitoneal taurolidine significantly attenuated these hemodynamic and respiratory changes. Serum endotoxin concentration was also significantly reduced as was lung myeloperoxidase. The data suggest that taurolidine may have a therapeutic role in preventing the lung injury seen in endotoxemia.

Clinically applicable thermal preconditioning attenuates leukocyte-endothelial interactions.

BACKGROUND: We have previously demonstrated that clinically applicable thermal preconditioning induces heat shock protein 72 (HSP72) and protects against a subsequent ischemia-reperfusion (I/R) injury in an animal model. A core component of I/R injuries is the interaction between activated leukocytes and endothelial cells. We hypothesized that the effects of clinically applicable thermal preconditioning are mediated through attenuation of this leukocyte-endothelial (L-E) interaction. STUDY DESIGN: Twenty-one male Sprague Dawley rats were divided into control, I/R, and preconditioning plus I/R groups. Preconditioning was done under general anesthesia and the animals' temperature raised by 1 degrees C for 15 minutes in a water bath. This was repeated once a day for 5 successive days. I/R injury was caused by occlusion of the superior mesenteric artery for 10 minutes followed by 1 hour of reperfusion. L-E interactions were analyzed using intravital microscopy of a mesenteric vessel in vivo. L-E interactions were determined using leukocyte velocity (which decreases as cells interact), and number of adherent and migrated leukocytes. HSP72 was assessed by Western blot. RESULTS: Ischemia-reperfusion caused a decrease in leukocyte rolling velocity at all timepoints (p < 0.05 versus controls). Preconditioning attenuated the effects of I/R, and leukocyte rolling velocity was significantly improved versus I/R (p < 0.05) to levels similar to those in controls. Similarly, the number of adherent and migrating leukocytes increased significantly (p < 0.05) after I/R versus control at all time points, and preconditioning attenuated these to control levels, (p < 0.05 versus I/R) at both the 30- and 60-minute postischemia time points. Upregulation of HSP72 was demonstrated on Western blot. CONCLUSIONS: These results demonstrate that the benefit of clinically applicable thermal preconditioning is at least partially because of an immunomodulatory role in attenuating leukocyte-endothelial interactions associated with an increased expression of HSP 72.

A novel gene delivery system for mammalian cells.

Although gene therapy holds great promise for the treatment of both acquired and genetic diseases, its development has been limited by practical considerations. Non-viral efficacy of delivery remains quite poor. We are investigating the feasibility of a novel lipid-based delivery system, cochleates, to deliver transgenes to mammalian cells. Rhodamine-labelled empty cochleates were incubated with two cell-lines (4T1 adenocarcinoma and H36.12 macrophage hybridoma) and primary macrophages in vitro and in vivo. Cochleates containing green fluorescent protein (GFP) expression plasmid were incubated with 4T1 adenocarcinoma cells. Cellular uptake of labelled cochleates or transgene GFP expression were visualised with fluorescence microscopy. 4T1 and H36.12 lines showed 39% and 23.1% uptake of rhodamine-cochleates, respectively. Human monocyte-derived macrophages and mouse peritoneal macrophages had 48+/-5.38% and 51.46+/-15.6% uptake of rhodamine-cochleates in vitro. In vivo 25.69+/-0.127% of peritoneal macrophages were rhodamine-positive after intra-peritoneal injection of rhodamine-cochleates. 19.49+/-10.12% of 4T1 cells expressed GFP. Cochleates may therefore be an effective, non-toxic and non-immunogenic method to introduce transgenes in vitro and in vivo.

Two weeks taurine supplementation reverses endothelial dysfunction in young male type 1 diabetics.

Type 1 diabetics have a well-recognised risk of accelerated cardiovascular disease. Even in the absence of clinical signs there are detectable abnormalities of conduit vessel function. Our group has previously reported reversal of endothelial dysfunction in diabetics with pravastatin. In young asymptomatic smokers, taurine supplementation has a beneficial impact on macrovascular function, assessed by FMD, and shows an up-regulation of nitric oxide from monocyte-endothelial cell interactions. We hypothesise that taurine supplementation reverses early endothelial abnormalities in young male type 1 diabetics, as assessed by applanation tonometry, brachial artery ultrasound and laser Doppler fluximetry. Asymptomatic, male diabetics (n=9) were scanned prior to treatment and then randomised in a double-blind cross-over fashion to receive either 2 weeks placebo or taurine. Control patients (n=10) underwent a baseline scan. Assessed diabetics had detectable, statistically significant abnormalities when compared with controls, in both arterial stiffness (augmentation index) and brachial artery reactivity (FMD). Both of these parameters were returned to control levels with 2 weeks taurine supplementation. In conclusion, 2 weeks taurine supplementation reverses early, detectable conduit vessel abnormalities in young male diabetics. This may have important implications in the long-term treatment of diabetic patients and their subsequent progression towards atherosclerotic disease.

The antiendotoxin agent taurolidine potentially reduces ischemia/reperfusion injury through its metabolite taurine.

BACKGROUND: Cardiopulmonary bypass results in ischemia/reperfusion (I/R)-induced endotoxemia. We conducted a prospective randomized trial to investigate the effect of taurolidine, an antiendotoxin agent with antioxidant and membrane-stabilizing properties, on patients undergoing coronary artery bypass grafting (CABG). METHODS: A total of 60 patients undergoing CABG were randomized into 4 groups. St Thomas' Hospital cold crystalloid cardioplegia was used in groups A and B, and cold blood cardioplegia in groups C and D. Groups A and C received a placebo infusion of normal saline, whereas groups B and D were administered intravenous taurolidine. Arrhythmias induced by pro- and anti-inflammatory cytokines (interleukin [IL]-6 and IL-10), and I/R were assessed perioperatively. RESULTS: Administration of taurolidine in crystalloid cardioplegia patients resulted in a significant decrease in serum IL-6 and an increase in serum IL-10 at 24 hours postaortic unclamping compared to placebo (P < .0001). Although not statistically significant, this trend in serum IL-6 decrease was mirrored in the blood cardioplegia patients (P = .068). Taurolidine treatment also significantly decreased I/R-induced arrhythmias compared to placebo in the crystalloid cardioplegia patients (P < .003). There were fewer I/R-induced arrhythmias compared to placebo in the blood cardioplegia patients; the difference, however, was marginal and not statistically significant (P = .583). CONCLUSION: This study demonstrates that administration of taurolidine in CABG patients induces a potent anti-inflammatory response that is associated with a significant decrease in arrhythmias.

Glutamine preconditioning protects against tourniquet-induced local and distant organ injury in a rodent ischemia-reperfusion model.

INTRODUCTION: Ischemia-reperfusion (IR) injury is a common surgical event, with tourniquet use being a recognized cause in orthopedic surgery. Preconditioning is a highly evolutionarily conserved endogenous protective mechanism, but finding a clinically safe, acceptable method of induction has proven difficult. Glutamine, a known inducer of the heat shock protein response, offers pharmacological modulation of injury through clinically acceptable preconditioning. Our aim was to test the hypothesis that glutamine preconditioning protects against tourniquet-induced regional and remote IR injury in a rodent model. ANIMALS AND METHODS: 40 adult male Sprague-Dawley rats were randomized into 4 groups: control, IR injury, normal saline-pretreated and IR injury, and glutamine-pretreated and IR injury. Pretreated groups received either normal saline or glutamine by intravenous bolus 24 h before injury. A bilateral hindlimb tourniquet model was used. Blood samples were analyzed, bronchioalveolar lavage (BAL) performed, and skeletal muscle and lung harvested for evaluation. RESULTS: The glutamine-pretreated group showed significantly lower muscle myeloperoxidase (MPO) content and creatine kinase levels than the untreated or saline-pretreated injury groups. Lung tissue showed reduced MPO content and a significantly reduced neutrophil count by BAL fluid microscopy. INTERPRETATION: These data suggest that preconditioning with glutamine offers local and distant organ protection in the setting of tourniquet-induced IR injury.

Taurine attenuates acute hyperglycaemia-induced endothelial cell apoptosis, leucocyte-endothelial cell interactions and cardiac dysfunction.

OBJECTIVES: Hyperglycaemia is implicated in microvascular inflammatory injury and subsequent cardiac injury/dysfunction. Leucocyte adhesion to the endothelium, migration into tissue and toxic metabolite release are early critical steps. Taurine is a semi-essential amino acid that is endothelial protective and restrains excess leucocyte activity by the formation of less toxic inflammatory mediators. The aim was to establish if taurine reduces acute hyperglycaemia-induced endothelial cell apoptosis and leucocyte interactions and associated cardiac abnormalities. METHODS: Male Sprague-Dawley rats (190-250 g) were randomised to control, hyperglycaemia, and hyperglycaemia plus taurine pre-treated groups. Taurine was gavaged (200 mg/kg body weight) for 5 days. Intravenous hyperglycaemia was established which was 4 times that of baseline for the 3-hour experiment. Using intravital microscopy, mesenteric post-capillary venules were examined for leucocyte rolling, adhesion and migration every 30 min from baseline. Endothelial cell apoptosis and intracellular adhesion molecule (ICAM-1) expression were assessed. In a separate experiment, blood pressure, pulse rate, cardiac injury marker (troponin T), cardiac tissue injury and oedema were also assessed. RESULTS: Hyperglycaemia significantly increased leucocyte adhesion and migration. Blood pressure and troponin T were also elevated significantly. Taurine prevented these cardiac changes, endothelial cell apoptosis and ICAM-1 expression. CONCLUSIONS: Taurine may have a therapeutic role in reducing diabetic microvascular inflammatory injury and concomitant cardiac dysfunction.