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.

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.

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.

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.

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.

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.

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.

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 µm; 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 µm 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.

A peptide corresponding to the neuropilin-1-binding site on VEGF(165) induces apoptosis of neuropilin-1-expressing breast tumour cells

There is increasing evidence that vascular endothelial growth factor (VEGF) has autocrine as well as paracrine functions in tumour biology. Vascular endothelial growth factor-mediated cell survival signalling occurs via the classical tyrosine kinase receptors Flt-1, KDR/Flk-1 and the more novel neuropilin (NP) receptors, NP-1 and NP-2. A 24-mer peptide, which binds to neuropilin-1, induced apoptosis of murine and human breast carcinoma cells, whereas a peptide directed against KDR had no effect. Both anti-NP1 and anti-KDR peptides induced endothelial cell apoptosis. Confocal microscopy using 5-(6)-carboxyfluorescein-labelled peptides showed that anti-NP1 bound to both tumour and endothelial cells, whereas anti-KDR bound endothelial cells only. This study demonstrates that NP-1 plays an essential role in autocrine antiapoptotic signalling by VEGF in tumour cells and that NP1-blockade induces tumour cell and endothelial cell apoptosis. Specific peptides can therefore be used to target both autocrine (tumour cells) and paracrine (endothelial cells) signalling by VEGF.

Taurine attenuates CD3/interleukin-2-induced T cell apoptosis in an in vitro model of activation-induced cell death (AICD)

Interleukin (IL)-2 immunotherapy is used for the treatment of metastatic melanoma and renal cell carcinoma and mediates its effects through the clonal expansion of lymphocytes. Although IL-2 remains the most effective form of therapy for these cancers, response rates are poor and dose escalation is hampered by side effects, which include vascular leak and lymphopenia. The mechanism underlying T cell loss is currently unidentified but could be the induction of activation-induced cell death (AICD) mediated by FasL. Our previous studies have shown that the amino acid taurine can attenuate apoptosis induced by a number of factors in different cell types. Here, we induced T cell AICD via CD3 and IL-2 stimulation and investigated the effect of taurine on lymphocyte apoptosis. Anti-CD3-activated Jurkat T cells treated with IL-2 significantly increased FasL expression, which was associated with increased apoptosis. Treatment with taurine prior to stimulation down-regulated FasL protein expression and partially inhibited apoptosis. Inhibition of FasL-signalling resulted in an identical reduction in apoptosis. As the kinetics of AICD are completely different in circulating T cells, we repeated these experiments in such cells to confirm our finding. Stimulation of CD4(+) circulating T cells induced apoptosis in sensitized, but not freshly isolated T cells, which was abrogated partially by taurine. In Jurkat cells it was determined that taurine-mediated down-regulation of FasL protein expression was associated with decreased FasL mRNA expression and reduced NFkappaB activation. These results reveal one possible mechanism underlying the lymphopenia observed with IL-2 immunotherapy, involving increased FasL expression leading to apoptosis. Taurine may be of use in reversing the lymphopenia associated with IL-2, thereby augmenting its immunotherapeutic potential.

Antimetastatic activity of a cyclooxygenase-2 inhibitor

Cyclooxygenase-2 (COX-2) expression is increased in breast cancer and surgery has been shown to increase the growth of metastatic tumours. We investigated the effect of selective COX-2 inhibition on the growth of metastases in either an experimental metastasis model or following excision of a murine primary breast tumour. 50 000 4T1 mammary carcinoma cells were injected into the mammary fat pad of female BALB/c mice. When the mean TD reached 8±0.4 mm, tumours were excised and the mice were randomised into two groups (n=12 per group) to receive daily intraperitoneal injections of the selective COX-2 inhibitor, SC-236 or drug vehicle for 14 days. Alternatively, experimental metastases were established by tail-vein injection of 50 000 4T1 cells. Mice received either the selective COX-2 inhibitor, SC-236 or drug vehicle for 14 days (n=12 per group). SC-236 treatment significantly reduced tumour burden, the number and size of spontaneous metastases following primary tumour excision. SC-236 treatment also reduced tumour burden, the number and size of experimental metastases. Immunohistochemical staining demonstrated that COX-2 inhibition reduced microvessel density and increased apoptosis within both spontaneous and experimental metastases. These data clearly demonstrate that the selective COX-2 inhibitor, SC-236, has potent antimetastatic activity against both spontaneous metastases arising following primary tumour excision and experimental metastases.

Management of patients undergoing splenectomy in an Irish teaching hospital: impact of guidelines

INTRODUCTION

Overwhelming post-splenectomy infection (OPSI) has a 50-70% mortality rate and carries a lifetime risk for the asplenic patient. Specific British guidelines have been developed to reduce its incidence.

AIMS

To determine whether British guidelines were being followed in our own institution and what impact they had on overwhelming post-splenectomy infection.

METHODS

Retrospective chart review of 100 splenectomies performed by Department of Surgery, Beaumont Hospital from January 1990 to January 2000.

RESULTS

Twenty per cent of patients were discharged without any recommended vaccinations. Prophylactic antibiotics were not prescribed in 53% of patients. Just 12% of charts document a verbal explanation of the complications and management of asplenia to the patient. Overall septic mortality was 12%, of whom 8% died in hospital and 4% after discharge.

CONCLUSION

Management of the asplenic patient has improved but is far from complete. A central register of asplenic patients and national asplenic guidelines should be established in Ireland to ensure optimum patient care.

Traumatic pseudoaneurysm of the internal carotid artery presenting with oculosympathetic palsy

BACKGROUND

Blunt internal carotid artery (ICA) injury is rare but undiagnosed can have disastrous clinical consequences.

AIM

To report a late presentation of blunt ICA injury in a young male following a road traffic accident.

RESULT

A 16-year-old male presented 11 days following a head injury with a unilateral Horner's syndrome. Imaging confirmed a pseudoaneurysm of the ICA. The patient was treated with anticoagulant therapy.

CONCLUSION

Diagnosis of ICA injury requires a high index of suspicion and presentation with unusual neurological signs following blunt trauma to the head and neck requires prompt investigation.

Are elective surgical operations cancelled due to increasing medical admissions?

BACKGROUND

Cancellation of operations increases theatre costs and decreases efficiency. We examined the causes of theatre cancellations in general surgery.

METHODS

The Beaumont hospital database (ORSUS system) and theatre records were examined retrospectively between April 1997 and March 2002. The number and causes of theatre cancellations, the number of emergency admissions and their length of hospital stay were studied.

RESULTS

The number of elective operations cancelled between April 1997-March 1998 and April 2001-March 2002 were 368 and 427 respectively. 'No bed' was the reason for theatre cancellation in 114 (31.0%) cases between April 1997-March 1998 and this increased to 267 (62.5%) cases between April 2001-March 2002. Between April 1997-March 1998 and April 2001-March 2002, general surgical emergency admissions decreased by 6.74% (3,116 to 2,906), and emergency surgical admissions across the specialties decreased by 2.02% (4,002 to 3,921). In the same time interval, general medical emergency admissions rose from 4,195 to 5,386 (a 28.39% increase), and emergency medical admissions across the specialties rose from 5,401 to 6,689 (a 23.84% increase). General surgical bed days for emergency admissions fell between April 1997-March 1998 and April 2001-March 2002 from 28,839 to 26,698 (7.4% decrease). There was a similar decrease from 38,188 to 36,004 (5.7% decrease) for all surgical specialties. Total bed days necessitated by general medical emergency admissions increased from 53,226 to 61,623 (15.8%). Across the medical specialties, an increase from 71,590 to 82,180 bed days (14.79%) was seen.

CONCLUSIONS

Elective surgery cancellation is a significant problem with far-reaching consequences. While multifactorial in aetiology, increased bed usage by medical specialties is one important factor. This study has implications for doctors, training, administrators and patients.

Hydroxy-methylglutaryl-coenzyme A reductase inhibition improves endothelial dysfunction in type-1 diabetes

OBJECTIVE

We hypothesize that treatment with Pravastatin, a HMG CoA reductase inhibitor would improve flow-mediated dilation (FMD), a nitric oxide dependent phenomenon and the earliest detectable marker of endothelial dysfunction, in asymptomatic patients with type-1 diabetes.

MATERIALS AND METHODS

FMD of the brachial artery in response to reactive hyperaemia was measured using high-resolution ultrasonography. Young male patients with type-1 diabetes (n=9) were compared with age matched non-diabetic controls (n=8).

RESULTS

The FMD response in the control group was a median increase in diameter of 7.9 (range 3.8-12.6)%. In the diabetic group the FMD response was impaired when compared with controls with a median increase only of 4.4 (range 3.7-5.8)% (p<0.01). Following Pravastatin, 40 mg per day for one month in the diabetic group, there was a significant diameter change in response to reactive hyperaemia with a median of 8.4 (range 6.9-12.6)% (p<0.01).

CONCLUSIONS

These data confirm the presence of endothelial dysfunction in young patients with type-1 diabetes. We have shown that 1-month of Pravastatin treatment normalizes FMD. This suggests that HMG CoA reductase inhibitors may have a role in the management of diabetes mellitus, even in the presence of normal serum cholesterol levels.

Young male smokers have altered platelets and endothelium that precedes atherosclerosis

BACKGROUND

Cigarette smoking results in abnormalities of platelets and endothelium with platelet dysfunction implicated in vascular complications. Healthy endothelium plays a pivotal role in regulating hemostasis via the inhibition of platelet activation and aggregation. Thus, we examined if platelet dysfunction correlated with serum vWF levels-a circulating marker of endothelial dysfunction.

MATERIALS AND METHODS

We tested this hypothesis in young male smokers. The parameters of platelet function tested included: CD62/CD63; Glycoprotein (GP) IIb/IIIa; Platelet function analzyer (PFA) studies, platelet aggregometry, flow assessment of platelet microparticles, platelet-leukocyte interactions and receptor numbers. Endothelial dysfunction was assessed with serum von Willebrand Factor (vWF).

RESULTS

There was a significant increase in platelet CD62 receptor expression and aggregation with an associated delay in time to aggregation using PFA. Endothelial dysfunction was represented by higher serum levels of von Willebrand Factor. All other platelet parameters tested were within the standardized reference range.

CONCLUSIONS

These initial data suggests that anti-platelet therapy may have a role in reduction of platelet activation and aggregation in young smokers and possibly alter vascular endothelial abnormalities.

Improvement in efficacy of chemoradiotherapy by addition of an antiangiogenic agent in a murine tumor model

BACKGROUND

Chemoradiotherapy improves survival for some cancer patients. Methods of enhancing treatment response would further enhance survival rates. The effect of the addition of an antiangiogenic agent to a chemoradiotherapy regime has not previously been examined.

MATERIALS AND METHODS

C57B16 mice were inoculated with 1 x 10(6) Lewis lung carcinoma cells into the flank and randomized to 1 of 10 treatment groups when tumor volume approached 1000 mm(3). Animals received combinations of standard doses of intraperitoneal cisplatin, 5-fluorouracil, and the antiangiogenic agent genistein, together with 10 or 20 Gy of external beam radiotherapy. Animals were sacrificed at day 6 when tumor volume, microvessel density, and serum VEGF were determined.

RESULTS

Mean (SEM) tumor volume in the chemoradiotherapy group was 762 (212) mm(3) versus 565 (79) mm(3) in the chemoradiotherapy plus genistein group (P = 0.04, unpaired t-test). The addition of genistein produced a significant reduction in tumor microvessel density (P = 0.01) as well as serum VEGF levels (P < 0.05) compared to those animals receiving chemoradiation alone.

CONCLUSIONS

This study provides proof of principle that chemoradiation can be enhanced by the addition of an antiangiogenic agent to the regime and suggests that further examination of such regimes is warranted.

Effect of neoadjuvant chemoradiotherapy on angiogenesis in oesophageal cancer

Background

Vascular endothelial growth factor (VEGF) levels are raised in the serum of patients with oesophageal carcinoma. The aim of this study was to evaluate the tumour microvasculature and the role of tumour-associated macrophages in VEGF production after neoadjuvant chemoradiotherapy and surgery for oesophageal cancer.

Methods

Sections from 92 consecutively resected oesophageal tumours were stained for VEGF, von Willebrand factor and CD68. Twenty-seven patients received preoperative chemoradiation and 65 underwent surgical excision alone. The cellular source of VEGF was determined by parallel-section staining. Microvessel density and macrophage count were determined for each tumour by means of image analysis software.

Results

There were no significant differences between the two groups in age, sex or tumour type. Local downstaging of disease was evident in most specimens of tumours that had received preoperative chemoradiation. All tumours stained positive for VEGF, including those demonstrating a complete pathological response. Staining of parallel sections confirmed macrophages as the principal source of VEGF. Mean microvessel density was 6·4 per high-power field (h.p.f.) in tumours that received preoperative chemoradiation compared with 5·3 per h.p.f. in those treated by surgery alone (P = 0·130). A significant increase in tumour-associated macrophage infiltration was noted in tumours treated with neoadjuvant chemoradiation (22·1 per h.p.f.) compared with those treated by surgery alone (14·3 per h.p.f.) (P = 0·042).

Conclusion

Preoperative chemoradiation had little effect on the local angiogenic profile of the tumour in patients with oesophageal cancer. Tumour-infiltrating macrophages seem to be the source of persistent VEGF production after chemoradiotherapy and might explain the raised serum levels. Addition of an antiangiogenic agent to this regimen may be worthwhile in patients with oesophageal carcinoma.

Taurine and vitamin C modify monocyte and endothelial dysfunction in young smokers

BACKGROUND

Endothelial dysfunction initiated by monocyte-endothelial interactions has previously been observed in many vasculopathies, including chronic cigarette smoking. Taurine, a semiessential amino acid, and vitamin C, a naturally occurring antioxidant, have previously been shown to have endothelial protective effects when exposed to proinflammatory insults. Therefore, we hypothesized that taurine and vitamin C would restore endothelial function in young smokers by modifying monocyte-endothelial interactions.

METHODS AND RESULTS

Endothelial-dependent vasodilatation was assessed in vivo using duplex ultrasonography, and monocyte-endothelial interactions were assessed in vitro using endothelial cell culture (human umbilical vein endothelial cells [HUVECs]) with monocyte-conditioned medium (MCM). Endothelial-dependent vasodilatation was significantly impaired in young smokers compared with nonsmokers. Pretreatment of young smokers for 5 days with 2 g/d vitamin C and, more significantly, with 1.5 g/d taurine attenuated this response. MCM taken from smokers impaired the release of nitric oxide and increased the levels of endothelin-1 release from HUVECs. When HUVECs were cultured with MCM from smokers who had been treated with taurine, the levels of nitric oxide and endothelin-1 returned toward control levels. This was attributed to an upregulation in endothelial nitric oxide synthase expression.

CONCLUSIONS

These observations suggest that taurine supplementation has a beneficial impact on macrovascular endothelial function, and an investigation of its effect on altered endothelial function in dyslipidemic states is warranted.

Pharmacological induction of HSP27 attenuates intimal hyperplasia in vivo

OBJECTIVES

intimal hyperplasia (IH) is a major cause of re-stenosis post-vascular intervention. Induction of heat shock proteins (HSPs), by thermal pre-conditioning, reduces IH. Our aim was to investigate the effect of the pharmacological HSP inducer herbimycin A on IH in the rat carotid balloon injury model.

MATERIALS AND METHODS

thirty male Sprague-Dawley rats were randomized into three groups. All groups underwent balloon injury to the left carotid artery. Stress proteins were induced 18 h pre-operatively by heat shock or herbimycin A. Two weeks post-operatively, animals were sacrificed and carotid intima/media area ratio (I/M ratio) calculated using computerized planimetry. Neo-intimal proliferation was assessed immunohistochemically with PCNA (proliferating cell nuclear antigen). Western blot and immunohistochemistry for arterial HSP70 and HSP27 were performed.

RESULTS

heat stress and herbimycin significantly reduced the I/M ratio (p < 0.05 vs balloon injury alone). Neo-intimal proliferation was significantly reduced in the heat stress and herbimycin groups (p < 0.05 vs balloon injury alone). Heat stress induced arterial HSP70 and HSP27. Herbimycin A increased arterial HSP27.

CONCLUSION

herbimycin A significantly attenuates IH after balloon injury. HSP27 may be the HSP involved in mediating this response. Pharmacological inducers of HSPs may have a therapeutic role to play in preventing re-stenosis post-vascular intervention.

Clinically relevant thermal preconditioning attenuates ischemia-reperfusion injury

INTRODUCTION

Thermal preconditioning has previously been shown to attenuate ischemia-reperfusion induced injuries, possible due to increased expression of heat shock proteins (HSP). The model of thermal preconditioning used, however, was not clinically relevant as preconditioning was to 41 degrees C, leading to cellular damage. Our aim was thus to establish a novel and clinically applicable method of preconditioning.

MATERIALS AND METHODS

Twenty-six male Sprague-Dawley rats were split into three groups (nine control, nine ischemia-reperfusion, and eight preconditioned followed by ischemia-reperfusion). To precondition the animals, they were anesthetized and, using a water bath, their core temperature was raised by 1 degrees C for 15 min once a day for five successive days. I/R injury consisted of 30 min of aortic cross-clamping followed by 120 min of reperfusion; control animals had a laparotomy only. Indicators of lung injury were tissue myeloperoxidase, broncho-alveolar lavage protein concentration, and tissue edema. Tissue heat shock protein expression was detected by Western blot analysis.

RESULTS

Lower torso ischemia-reperfusion causes significant lung injury versus control, with raised levels of myeloperoxidase 4.53 iu/g to 7.88 iu/g (P < 0.05), raised B.A.L. protein concentration 419 microg/ml to 684 microg/ml (P < 0.05) and altered wet dry ratio 4.63 to 5.50. Clinically relevant thermal preconditioning attenuates all of these parameters back to control levels: myeloperoxidase 3.87 iu/g (P < 0.05 vs I/R), B.A.L. to 284 microg/ml (P < 0.01 vs I/R) and wet dry ratio to 4.44 (P < 0.05 vs I/R). Western blot demonstrated increased expression of H.S.P. 72 in the preconditioned group versus control and I/R alone. Western blot demonstrated increased expression of HSP72 in the preconditioned group vs control and I/R alone.

CONCLUSIONS

We conclude that clinically applicable thermal preconditioning can attenuate ischemia-reperfusion induced lung injury, possibly through increased expression of HSP72.

Inosine modulates gut barrier dysfunction and end organ damage in a model of ischemia-reperfusion injury

INTRODUCTION

Gut barrier failure is an important source of morbidity in critically ill patients, and patients undergoing aortic cross-clamp. Inosine, an endogenous purine nucleoside without known side effects, formed from the breakdown of adenosine by adenosine deaminase, has been shown to modify the effects of hypoxia on various tissues, including the heart and the brain.

MATERIALS AND METHODS

This study examined the effect of inosine on ischemia-reperfusion-induced gut barrier dysfunction and on the associated lung injury. Twenty-four male Sprague-Dawley rats were divided into three groups. Eight were subjected to 60 min of superior mesenteric artery occlusion followed by 4 h of reperfusion. Eight had 100 mg/kg inosine prior to ischemia-reperfusion and 8 had sham laparotomy with encircling but not occlusion of the superior mesenteric artery.

RESULTS

Rats treated with inosine had significantly less gut barrier dysfunction. Rats subjected to SMAO sustained a substantial lung injury and this was attenuated by inosine treatment. Serum cytokine levels were also significantly lower.

CONCLUSIONS

We conclude that inosine has a beneficial effect in modulating both gut barrier dysfunction and distant organ injury in response to gut ischemia-reperfusion.

Oral folic acid improves endothelial dysfunction in cigarette smokers

INTRODUCTION

Endothelial dysfunction is an early manifestation of the atheromatous process and is evident without overt clinical signs or symptoms of the disease. Cigarette smoking has been shown to be associated with endothelial dysfunction in otherwise healthy adults. Although cessation of smoking is the ideal objective, it is not always attainable, and therefore any strategy to prevent early endothelial dysfunction is desirable. Folic acid is currently under review as a rational therapeutic agent in hyperhomocysteinemia. However, folic acid may modify endothelial function independent of its effect on homocysteine. We therefore investigated the effect of folic acid on endothelial function in young otherwise healthy cigarette smokers.

METHODS

Volunteer cigarette smokers (n = 10) and control lifelong nonsmokers were enrolled in the study. Baseline folate, vitamin B12, homocysteine, and cholesterol levels were analyzed. Flow-mediated dilatation, an endothelial-dependent phenomenon, was assessed using ultrasonography. This scan was performed at baseline and following 4 weeks of folic acid supplementation (5 mg/day).

RESULTS

There were no significant differences in the baseline hematological investigations between the groups. Homocysteine levels were within normal limits in both groups and did not change following folic acid supplementation. Cigarette smokers demonstrated significant endothelial dysfunction compared to controls (P < 0.005). This difference was significantly attenuated by folic acid supplementation (P < 0.005).

CONCLUSION

Folic acid significantly improves endothelial function in otherwise healthy cigarette smokers. This provides a potential therapeutic tool in attenuating the atheromatous process in this group.

Cyclo-oxygenase inhibition reduces tumour growth and metastasis in an orthotopic model of breast cancer

The effect of selective and non-selective cyclo-oxygenase inhibition on tumour growth and metastasis in an orthotopic model of breast cancer was investigated. 4T1 mammary adenocarcinoma cells were injected into the mammary fat pad of female BALB/c mice. When tumours reached a mean tumour diameter of 8.4+/-0.4 mm, mice were randomised into three groups (n=6 per group) and received daily intraperitoneal injections of the selective cyclo-oxygenase-2 inhibitor, SC-236, the non selective cyclo-oxygenase inhibitor, Indomethacin, or drug vehicle. Tumour diameter was recorded on alternate days. From 8 days after initiation of treatment, tumour diameter in animals treated with either SC-236 or indomethacin was significantly reduced relative to controls. Both primary tumour weight and the number of lung metastases were significantly reduced in the SC-236 and indomethacin treated mice. Microvessel density was reduced and tumor cell apoptosis increased in the primary tumour of mice treated with either the selective or non-selective cyclo-oxygenase inhibitor. In vitro, cyclo-oxygenase inhibition decreased vascular endothelial growth factor production and increased apoptosis of tumour cells. Our results suggest that cyclo-oxygenase inhibitors will be of value in the treatment of both primary and metastatic breast cancer.

Diethylmaleate, a pro-oxidant, attenuates experimental ischaemia-reperfusion-induced lung injury

BACKGROUND

Systemic ischaemia-reperfusion (IR) injury is in part an oxidant injury mediated by neutrophils. Diethylmaleate (DEM), an intracellular pro-oxidant agent, has been shown to alleviate neutrophil-mediated tissue injury. The aim of this study was to evaluate whether DEM could have a protective effect on neutrophil-mediated lung injury in an animal model of lower-torso IR.

METHODS

Sprague-Dawley rats (seven per group) were randomized into three groups. The control group underwent midline laparotomy only; the IR group underwent laparotomy and clamping of the infrarenal abdominal aorta for 30 min followed by 2 h of reperfusion; and the third group was pretreated with DEM 6 mmol/kg intraperitoneally 1 h before the IR insult.

RESULTS

IR resulted in a significant increase in both microvascular leakage and pulmonary neutrophil infiltration as measured by bronchoalveolar lavage protein concentration and pulmonary myeloperoxidase activity respectively. Pretreatment with DEM significantly attenuated both microvascular leakage and neutrophil infiltration.

CONCLUSION

Preconditioning with DEM protected against IR-induced lung injury. This protective effect raises the possibility of using pro-oxidants to prevent inflammatory injury.

Potentiation of the therapeutic index of interleukin-2 immunotherapy by combination with taurine in a syngeneic murine tumour model

BACKGROUND

Administration of interleukin-2 (IL-2) is limited by the induction of the vascular leak syndrome (VLS).

AIMS

To examine the effect of taurine on the toxicity and antitumour activity of IL-2 in a B16 melanoma pulmonary metastases model.

METHODS

B16 melanoma cells were injected into female C57BL/6 mice. Macroscopic melanoma pulmonary foci were established by day 10 in untreated mice. Treated mice were randomised into treatment by rIL-2 alone, rIL-2 plus taurine or taurine alone. Control animals received saline. Mice were sacrificed on day 18. Lung metastases were counted in a blinded fashion with the aid of a dissecting microscope. Wet to dry lung weight was measured following lung removal. In another experiment animals were treated as above (n = 15 per group) and survival following treatment monitored.

RESULT

Treatment with IL-2 and taurine significantly reduced lung nodules compared with IL-2 alone. Host survival was significantly enhanced. The wet to dry (w/d) ratios of lung weights in the group receiving IL-2/taurine were significantly less than IL-2 alone. Bronchoalveolar lavage protein fluid was reduced indicating reduced pulmonary injury.

CONCLUSION

These findings indicate that the combination of taurine with IL-2 augments the efficacy of this immunotherapy while reducing its associated dose-limiting toxicity.

Taurolidine improves survival by abrogating the accelerated development and proliferation of solid tumors and development of organ metastases from circulating tumor cells released following surgery

BACKGROUND

Surgical trauma is partly responsible for enhancing tumor growth through a variety of mechanisms that are still not fully elucidated. The use of perioperative immunostimulants may modulate these effects. This study examined the effect of administration of taurolidine after laparotomy or laparoscopy on the growth of solid tumor, the establishment of hepatic and lung metastases, and effects on natural killer (NK) and lymphokine-activated killer (LAK) cell function.

METHODS

B16 melanoma right flank tumors were established in mice (n = 180). These animals underwent anesthesia only (control) or laparotomy or laparoscopy (n = 60 per group) and were randomized to receive either saline or taurolidine (n = 30 per group) at specific time points. Survival was determined in each group, and in a further 90 mice tumor growth was followed over 10 days postoperatively. The experiment was repeated in 540 mice, which underwent one of the three procedures and were treated with either saline or taurolidine. NK and LAK cell cytotoxicity (NKCC, LAKCC) was determined at several time points postoperatively. In a further experiment, B16 melanoma tumor cells were delivered via tail vein injection (n = 180) and intrasplenic injection (n = 180). The effect of saline or taurolidine administration on survival after the establishment of metastases was determined, and again in a further 180 mice the establishment of metastatic deposits in the liver or lungs was determined after 8 days.

RESULTS

Survival appeared to be significantly decreased in both the solid-tumor model and the metastatic models undergoing laparotomy compared to laparoscopy and controls (P < 0.0001) and to a lesser extent in the laparoscopy group compared to controls (P < 0.001). Flank tumor growth and metastatic tumor formation were more significant in laparotomy groups compared to laparoscopy groups and controls, but also to a lesser extent in laparoscopy groups compared to controls (P </= 0.05). NKCC and LAKCC were significantly decreased in the same patterns (P < or = 0.03). However, treatment with taurolidine abolished these effects, restoring NKCC and LAKCC (P < or = 0.04) and laparoscopy groups (P < or = 0.001).

CONCLUSION

It appears that changes that occur after the trauma of laparotomy, and to a lesser extent, after laparoscopy, significantly enhance the growth of primary tumors as well as the development of metastases from circulating tumor cells and are associated with a suppression of host antitumor surveillance mechanisms. This not only affected tumor progression in the immediate postoperative period, but also ultimately affected survival. Taurolidine, a known immunostimulant, appears to abrogate the effects of surgical trauma on primary and metastatic tumor growth and also enhances survival. This may have significant value in the management of tumor-bearing patients undergoing resection.