Glutamine preconditioning protects against local and systemic injury induced by orthopaedic surgery.

INTRODUCTION: Long bone surgery represents a significant surgical insults, and may cause severe local and systemic sequalae following both planned and emergent surgery. Glutamine offers pharmacological modulation of injury through clinically acceptable preconditioning. This effect has not been previously demonstrated in an orthopaedic model. AIMS: The aim of the study was to test the hypothesis that glutamine preconditioning protects against the local and systemic effects of long bone trauma in a rodent model. METHODS: Thirty two adult male Sprague-Dawley rats were randomised into four groups: Control group which received trauma without preconditioning; Normal Saline preconditioning 1 hour before trauma; Glutamine preconditioning 1 hour before trauma; Glutamine preconditioning 24 hours prior to trauma. Trauma consisted of bilateral femoral fracture following intramedullary instrumentation. Blood samples were taken before the insult, and at an interval four hours following this. Bronchioalveolar lavage (BAL) was performed, with skeletal muscle and lung harvested for evaluation. RESULTS: Glutamine pre-treated rats had lower Creatine Kinase levels, less creatinine elevation, and a significant reduction in neutrophil infiltration into BAL fluid. Glutamine pre-treated rats showed less muscle and lung oedema. This effect was more pronounced for the group which received glutamine 24 hours before trauma. CONCLUSION: Preconditioning with a single bolus of intravenous glutamine prior to planned orthopaedic intervention affords loco-regional and distal organ protection. We believe these finding have significant implications for elective orthopaedic surgery where significant soft tissue and long bone manipulation is anticipated.

Tight glycaemic control is a key factor in wound healing enhancement strategies in an experimental diabetes mellitus model.

BACKGROUND: Diabetes mellitus is a leading cause of impaired wound healing. The aim of this study was to establish a glucose-controlled diabetic wound healing model. METHOD: Sprague-Dawley rats were divided into three groups: Control group (C), Diabetic Non-glucose Controlled group (DNC) and Diabetic glucose Controlled group (DC). RESULTS: Glucose control was achieved using Insulman Rapid (average daily glucose level <10 mmol/L). 18 Sprague-Dawley rats underwent a dorsal skin wound incision and 10 days later were killed. Fresh and fixed wound tensile strength, hydroxyproline and transforming growth factor beta-1 levels were improved in the DC group when compared to the DNC group. The quantity of fibroblasts present was similar in each group. CONCLUSION: This study demonstrates the impact that diabetes has on acute wound healing and suggests that wound modulating agents must be tested in both the tightly glucose-controlled as well as the poorly glucose-controlled diabetic animal models prior to proceeding with translational clinical studies.

Comparison of arterial stiffness and microcirculatory changes following abdominal aortic aneurysm grafting.

BACKGROUND: Abdominal aortic aneurysm (AAA) surgery provides a unique opportunity to study the impact of arterial stiffness on central haemodynamics, reflected in augmentation index (AI). The aneurysmal aorta is significantly stiffer than undilated age-matched aorta. AIM: We investigated whether replacement of an aneurysmal aorta with a compliant graft would result in a decrease in AI, which would thus decrease myocardial workload parameters. METHODS: Patients undergoing elective open or endovascular AAA repair were assessed with applanation tonometry and laser fluximetry pre-operatively, immediately and long-term post-operatively. RESULTS: Replacement of a small segment of abnormal conduit vessel resulted in improvements in AI, demonstrating that arterial stiffness can be surgically manipulated. CONCLUSIONS: These results reflect a decreased myocardial workload post-aortic grafting. This decrease in AI is important from a risk factor management perspective, and arterial stiffness should become a further recognised and screened for risk factor in patients with known aneurysmal disease.

Taurine attenuates radiation-induced lung fibrosis in C57/Bl6 fibrosis prone mice.

INTRODUCTION: The amino acid taurine has an established role in attenuating lung fibrosis secondary to bleomycin-induced injury. This study evaluates taurine's effect on TGF-beta1 expression and the development of lung fibrosis after single-dose thoracic radiotherapy. METHODS: Four groups of C57/Bl6 mice received 14 Gy thoracic radiation. Mice were treated with taurine or saline supplementation by gavage. After 10 days and 14 weeks of treatment, TGF-beta1 levels were measured in serum and bronchoalveolar lavage fluid (BALF). Lung collagen content was determined using hydroxyproline analysis. RESULTS: Ten days post radiotherapy, serum TGF-beta1 levels were significantly lower after gavage with taurine rather than saline (P = 0.033). BALF TGF-beta1 at 10 days was also significantly lower in mice treated with taurine (P = 0.031). Hydroxyproline content was also significantly lower at 14 weeks in mice treated with taurine (P = 0.020). CONCLUSION: This study presents novel findings of taurine's role in protecting from TGF-beta1-associated development of lung fibrosis after thoracic radiation.

Neoplasms escape selective COX-2 inhibition in an animal model of breast cancer.

BACKGROUND: Cyclo-oxygenase-2 (COX-2) is up-regulated in malignant tumours rendering it an attractive target for cancer therapeutics. However, whether long-term antagonism maintains its initial efficacy on established tumours is unclear. METHODS: 4T1 cells were injected into the mammary fat pad of BALB/c mice (n = 8). Once tumour deposits were established, animals were randomized into two equal groups to receive either a selective COX-2 inhibitor (SC-236) or a drug vehicle. Further animals similarly treated (n = 7) were studied in diuresis cages allowing urine capture and analysis by mass spectrometry to determine Prostaglandin F-1 levels (PGF-1). In addition, both wild-type receiving SC-236 and COX-2 knockout mice receiving either SC 236 or vehicle were subjected to the same studies to determine whether tumour-derived or host-derived (stromal) COX-2 was the critical element. Finally, BALB/c mice with 4T1 tumours (n = 7) were treated with a combination of COX-2 and lipoxygenase (LOX) inhibition to attenuate this escape phenomenon. RESULTS: While selective COX-2 inhibition initially retarded tumour growth, a rapid increase in tumour growth rate occurred later (day 9). This escape phenomenon correlated with an increase in urinary PGF-1 levels. An identical trend was also observed whether COX-2 knockout mice received SC-236 or not, suggesting that this effect is due to increased tumour-derived COX-2 production rather than recovery of host COX-2 functional capacity. Finally, dual inhibition of COX and LOX pathways attenuated this escape process. CONCLUSION: The anti-neoplastic effects of selective COX-2 inhibition may not be sustained as tumours demonstrate an escape capacity. However, this phenomenon maybe attenuated by a combination of COX/LOX inhibitors.

Preconditioning and its clinical potential.

Preconditioning is emerging as a simple, safe and highly effective means of attenuating local and systemic effects of medical and surgical insult. Its enormous potential has not yet been harnessed and ongoing work will continue to bring it to the fore. This article covers the history, development and future clinical potential of preconditioning with particular regard to surgical insult.

Recombinant bactericidal permeability increasing protein (rBPI21) inhibits surgery-induced tumour growth in a murine model of metastatic disease.

BACKGROUND: Endotoxin (LPS), a cell wall constituent of gram-negative bacteria, is a potent inflammatory stimulus. We demonstrated that laparotomy increases primary tumour growth and experimental lung metastases, implicating endotoxin as a causative factor. We hypothesised that the anti-endotoxin agent, rBPI(21) would block surgery-induced tumour growth. METHODS: Mammary adenocarcinoma cells were injected into female BALB/c mice to establish lung metastases. Mice were randomised into three groups receiving anaesthesia, laparotomy or laparotomy and rBPI(21) treatment on day 14. Animals were killed on day 19, lungs harvested and blood obtained. Number and size of lung metastases were recorded. Apoptosis, mitosis and microvessel density within metastases were assessed and VEGF measured. CONCLUSIONS: Laparotomy increased metastatic growth, decreased tumour cell apoptosis, increased tumour cell proliferation, increased microvessel density and circulating VEGF. LPS blockade by rBPI(21) attenuated this increased growth and decreased proliferation, increased apoptosis, decreased micro-vessel density and circulating VEGF. This suggests that rBPI(21), has clinical potential in attenuating surgery enhanced tumour growth, especially in patients with a history of cancer undergoing laparotomy.

The evolution of trauma services at Beaumont Hospital.

OBJECTIVE: To review and examine the epidemiology, severity and management of trauma admissions at the national neurosurgical teaching hospital. METHODS: An extensive audit of volume, type and severity of injury and the management requirements of the trauma population admitted to the hospital. RESULTS: The vast majority of severely injured patients were referred from outside the catchment area of the hospital with only 26% being admitted directly through the Emergency Department. As a consequence, 73% of patients arrived out of normal working hours, which posed problems in providing skilled trauma specialists. CONCLUSIONS: The management of patients with serious injury is complex. The large proportion of patients with critical injuries, some of whom were paediatric, highlighted the need for 24 h cover by senior trauma personnel and the provision of radiology and operating facilities to meet their needs. The inclusion of indicators of alterations in innate or adaptive immune responses may improve the predictive power of severity of injury scores.

Practice patterns in flexor tendon repair.

BACKGROUND: There is a considerable volume of literature describing new and supposedly superior methods of flexor tendon repair. AIM: The purpose of this study was to assess the flexor tendon techniques currently used in the Republic of Ireland. METHODS: A postal survey was conducted of all consultant plastic surgeons and consultant orthopaedic surgeons who were members of the Irish Hand Surgery Society. RESULTS: The response rate was 90% (27/30). A simple running peripheral suture was used by 73% (P = 0.03) and the Kessler was the core suture of choice for 68% (P = 0.06). A significant number of respondents use non-absorbable suture materials for core (P = 0.0028) and peripheral suture (P < 0.0001). Seventy-seven percent sutured the flexor sheath where possible (P = 0.009). CONCLUSIONS: Notwithstanding the proposed advantages of newer techniques, it is evident from this study that the two-stranded Kessler core and simple running peripheral suture remains the most popular flexor tendon repair, with sheath closure preferred by the majority of respondents.

Risk-based evaluation of thromboprophylaxis among surgical inpatients: are low risk patients treated unnecessarily?

BACKGROUND: Venous thromboembolism is a common source of morbidity and mortality but a variety of preventative measures are available. AIMS: To audit the current practice of thromboprophylaxis and compare against published protocols. METHODS: Three-hundred and seventy-six (376) surgical patients were surveyed prospectively. A Performa was completed recording the presence of up to 11 risk factors. A risk score was calculated and the use of specific thromboprophylatic measures identified. RESULTS: Heparin thromboprophylaxis was widely used, eight patients (who were on aspirin therapy) failed to receive any prophylaxis (risk factors 4-6). In addition there were 60 patients at low risk (risk score <2) received LMWH from which they were unlikely to benefit. CONCLUSIONS: Thromboembolic prophylaxis is widely but unselectively applied. Adoption of a risk: benefit ratio approach should ensure those who would benefit from thromboprophylaxis are adequately treated while those in whom thromboprophylaxis is not indicated are spared unnecessary therapy.

Preoperative selection of symptomatic breast cancer patients appropriate for lymphatic mapping and sentinel node biopsy.

BACKGROUND: This study examines whether preoperative ultrasound-assessed tumour diameter and diagnostic core biopsy-determined grade can be used to select those most likely to benefit from SLNB (i.e. those that are "node negative") before their definitive operation. METHODS: Breast ultrasound (US) and a simultaneous core biopsy was performed in all patients at their initial presentation, and their estimates of tumor size and grade compared with the final pathological specimen (FPS). RESULTS: Of the T1 group 47% had lymphatic metastases as did 49% of those with grade I or II cancers. By combining these measures, however, subgroups of patients with lower rates of nodal metastases were identified (32% of patients with T1, non-grade III disease had lymphatic disease while only 15% of those with T < 1.5 cm, non-grade III cancers had such metastases). CONCLUSION: Combination of the US and ultrasound guided core biopsy (UGCB) may however identify subgroups unlikely to have axillary disease that are therefore suitable for SLNB.

Thrombomodulin expression in colorectal carcinoma is protective and correlates with survival.

Thrombomodulin (TM) is an endothelial receptor that exhibits anticoagulant, antifibrinolytic and anti-inflammatory activity by inhibiting thrombin and cellular adhesion. In this study, the expression and significance of TM was examined in primary colorectal cancer and its prognostic implications explored. TM immunostaining was performed on formalin-fixed, paraffin-embedded tissue sections, from primary lesions of 200 patients with colorectal carcinoma. Institutional Ethical approval was granted and clinical data retrieved from patients' records. All normal colonic tissue expressed TM on endothelial cells. TM tumour cell expression was demonstrated in 53 (26.5%) cases and 147 (73.5%) showed no neoplastic cell staining. On univariate and multivariate analysis TM expression on tumour cells correlated significantly with tumour stage, differentiation, Jass score and 5 year survival. TM expression decreases as overall stage and tumour size increase (P=0.03). In all, 91% TM positive tumours were well differentiated and 85% of TM negative tumours were poorly differentiated (P<0.01). Five year survival rates of patients with positive and negative TM expression were 71 and 41%, respectively. Survival rate was poorer in those patients who were TM negative compared with those who were positive (P<0.01). A total of 101 (50.5%) of the cases were node negative. In this group, 5 year survival rates of patients with positive and negative TM expression were 87.5 and 37.8%, respectively, demonstrating a poorer survival rate for those who are node negative and TM negative at the time of surgery (P<0.001). This study demonstrates that loss of TM is a key indicator in tumour biology and prognosis.

Co-immunotherapy with interleukin-2 and taurolidine for progressive metastatic melanoma.

BACKGROUND: Recombinant interleukin-2(rIL-2) therapy in metastatic melanoma is limited by toxicities, particularly vascular leak syndrome(VLS). Taurolidine potentiates the anti-neoplastic effects of IL-2 while reducing its associated endothelial cell dysfunction in experimental settings. We hypothesized that co-administration of rIL-2 with taurolidine could enhance tolerability without weakening effectiveness. METHODS: Eleven patients with progressive metastatic melanoma received high-dose rIL-2 with co-infusion of taurolidine. Patients were monitored for the development of toxicities and evidence of response. RESULTS: Ten patients tolerated twenty-nine courses of high-dose rIL-2 without dose-reduction. Most toxicities were low-grade. No patient developed VLS. Seven patients died from disease progression. Two had complete clinical and radiological responses to treatment. Two patients remain alive despite evidence of disease progression a mean of 17.5 months after diagnosing metastatic disease. CONCLUSION: Co-administration of taurolidine with high-dose rIL-2 in stage IV melanoma patients appears to greatly enhance the tolerability of this regime without diminishing its therapeutic value.

Angiogenic and cell survival functions of vascular endothelial growth factor (VEGF).

Vascular endothelial growth factor (VEGF) was originally identified as an endothelial cell specific growth factor stimulating angiogenesis and vascular permeability. Some family members, VEGF C and D, are specifically involved in lymphangiogenesis. It now appears that VEGF also has autocrine functions acting as a survival factor for tumour cells protecting them from stresses such as hypoxia, chemotherapy and radiotherapy. The mechanisms of action of VEGF are still being investigated with emerging insights into overlapping pathways and cross-talk between other receptors such as the neuropilins which were not previously associated with angiogenesis. VEGF plays an important role in embryonic development and angiogenesis during wound healing and menstrual cycle in the healthy adult. VEGF is also important in a number of both malignant and non-malignant pathologies. As it plays a limited role in normal human physiology, VEGF is an attractive therapeutic target in diseases where VEGF plays a key role. It was originally thought that in pathological conditions such as cancer, VEGF functioned solely as an angiogenic factor, stimulating new vessel formation and increasing vascular permeability. It has since emerged it plays a multifunctional role where it can also have autocrine pro-survival effects and contribute to tumour cell chemoresistance. In this review we discuss the established role of VEGF in angiogenesis and the underlying mechanisms. We discuss its role as a survival factor and mechanisms whereby angiogenesis inhibition improves efficacy of chemotherapy regimes. Finally, we discuss the therapeutic implications of targeting angiogenesis and VEGF receptors, particularly in cancer therapy.

Correction of anaemia through the use of darbepoetin alfa improves chemotherapeutic outcome in a murine model of Lewis lung carcinoma.

Darbepoetin alfa (Aranesp), Amgen) is a novel erythropoiesis-stimulating protein with a serum half-life longer than recombinant human erythropoietin (Epo), used in the treatment of cancer-associated anaemia. Anaemia is known to adversely affect prognosis and response to treatment in cancer patients. Solid tumours contain regions of hypoxia due to poor vascular supply and cellular compaction. Although hypoxic stress usually results in cell death, hypoxia-resistant tumour cells are genetically unstable and often acquire a drug-resistant phenotype. Increasing tumour oxygenation and perfusion during treatment could have the doubly beneficial outcome of reducing the fraction of treatment-resistant cells, while increasing drug delivery to previously hypoxic tissue. In this study, we examined the effect of darbepoetin alfa on chemotherapy sensitivity and delivery in an in vivo model of Lewis lung carcinoma, shown here to express the Epo receptor (EpoR). We identified that weekly darbepoetin alfa treatment, commencing 10 days before chemotherapy, resulted in a significant reduction in tumour volume compared to chemotherapy alone. This was mediated by the prevention of anaemia, a reduction in tumour hypoxia and a concomitant increase in drug delivery. Darbepoetin alfa treatment alone did not modulate the growth of the EpoR-expressing tumour cells. This study identifies an important role for darbepoetin alfa in increasing the therapeutic index of chemotherapy.

Hydroxymethylglutaryl co-enzyme A reductase inhibition attenuates endotoxin-mediated inflammatory responses.

BACKGROUND: The aim of this study was to investigate whether inhibition of hydroxymethylglutaryl co-enzyme A reductase attenuates leucocyte-endothelial cell interactions and alters expression of endothelial constitutive nitric oxide synthase (ecNOS) and inducible nitric oxide synthase (iNOS) following exposure to endotoxin. METHODS: Male Sprague-Dawley rats were randomized into control, lipopolysaccharide (LPS) and pravastatin + LPS groups (seven per group). Pravastatin sodium was gavaged at 0.4 mg per kg per day for 5 days, after which LPS 15 mg/kg was administered via the jugular vein. Intravital microscopy was used to determine leucocyte-endothelial cell interactions. RESULTS: Following the administration of LPS there was a significant reduction in leucocyte rolling velocity at 10 min (mean(s.e.m.) 69(3) versus 102(6) per cent of baseline value; P = 0.041), an increase in the number of adherent leucocytes at 10 min (4.5(0.5) versus 2.8(0.3) per 100 microm; P = 0.044) and an increase in the number of leucocytes undergoing transendothelial migration at 30 min (4.2(0.4) versus 1.7(0.4) per field; P = 0.008) compared with controls. Pretreatment with pravastatin significantly attenuated LPS-induced leucocyte-endothelial cell interactions (rolling velocity 89(6) per cent at 10 min, P = 0.038; adherent leucocytes 3.0(0.5) per 100 microm at 10 min, P = 0.038; migrating leucocytes 1.9(0.5) per field at 30 min, P = 0.001). This endothelial protection was associated with maintenance of ecNOS and reduced iNOS expression within mesenteric tissues. CONCLUSION: These data show that pravastatin produces anti-inflammatory effects in response to injurious stimuli by attenuation of leucocyte-endothelial cell interactions.

Thrombomodulin: tumour biology and prognostic implications.

BACKGROUND: Thrombomodulin (TM) is an endothelial receptor that exerts anti-coagulant, anti-fibrinolytic, and anti-inflammatory activity by inhibiting thrombin and cellular adhesion. There is growing evidence that TM plays a role in tumour behaviour. METHODS: The electronic literature (1966-2004) was reviewed with a specific focus on tumour biology. RESULTS: TM is expressed on both the endothelium and tumour cells in several cancers. Loss of expression denotes a more malignant profile with poorer prognosis. Loss of TM is mediated by hypoxia, endotoxin, and various cytokines, while up-regulation can be achieved by pharmacological manipulation (e.g. pentoxyfylline and statins). CONCLUSION: Originally described as an endothelial anticoagulant, TM plays a key role in tumour biology and prognostics, and provides a potential therapeutic target in impeding cancer spread.