Effects of chronic occupational exposure to anaesthetic gases on the rate of neutrophil apoptosis among anaesthetists

BACKGROUND AND OBJECTIVE

Volatile anaesthetic agents are known to influence neutrophil function. The aim was to determine the effect of chronic occupational exposure to volatile anaesthetic agents on the rate of neutrophil apoptosis among anaesthetists. To test this hypothesis, we compared the rate of neutrophil apoptosis in anaesthetists who had been chronically exposed to volatile anaesthetic agents with that in unexposed volunteers.

METHODS

Venous blood (20 mL) was withdrawn from 24 ASA I-II volunteers, from which neutrophils were isolated, and maintained in culture. At 1, 12 and 24 h in culture, the percentage of neutrophil apoptosis was assessed by dual staining with annexin V-FITC and propidium iodide.

RESULTS

At 1 h (but not at 12 and 24 h) in culture, the rate of neutrophil apoptosis was significantly less in the anaesthetists--13.8 (12.9%) versus 34.4 (12.1%) (P = 0.001).

CONCLUSIONS

Chronic occupational exposure to volatile anaesthetic agents may inhibit neutrophil apoptosis. This may have implications for anaesthetists and similarly exposed healthcare workers in terms of the adequacy of their inflammatory response.

Vascular endothelial growth factor stimulates bone repair by promoting angiogenesis and bone turnover

Several growth factors are expressed in distinct temporal and spatial patterns during fracture repair. Of these, vascular endothelial growth factor, VEGF, is of particular interest because of its ability to induce neovascularization (angiogenesis). To determine whether VEGF is required for bone repair, we inhibited VEGF activity during secondary bone healing via a cartilage intermediate (endochondral ossification) and during direct bone repair (intramembranous ossification) in a novel mouse model. Treatment of mice with a soluble, neutralizing VEGF receptor decreased angiogenesis, bone formation, and callus mineralization in femoral fractures. Inhibition of VEGF also dramatically inhibited healing of a tibial cortical bone defect, consistent with our discovery of a direct autocrine role for VEGF in osteoblast differentiation. In separate experiments, exogenous VEGF enhanced blood vessel formation, ossification, and new bone (callus) maturation in mouse femur fractures, and promoted bony bridging of a rabbit radius segmental gap defect. Our results at specific time points during the course of healing underscore the role of VEGF in endochondral vs. intramembranous ossification, as well as skeletal development vs. bone repair. The responses to exogenous VEGF observed in two distinct model systems and species indicate that a slow-release formulation of VEGF, applied locally at the site of bone damage, may prove to be an effective therapy to promote human bone repair.

Tumor lysis syndrome following endoscopic radiofrequency interstitial thermal ablation of colorectal liver metastases

Radiofrequency interstitial thermal ablation (RITA) provides a palliative option for patients suffering from metastatic liver disease. This procedure can be performed using a laparoscopic approach with laparoscopic ultrasound used to position the RITA probe. We describe a case of laparoscopic RITA performed for colorectal liver metastasis that was complicated by tumor lysis syndrome (TLS) following treatment. We consider RITA to be a safe procedure, as supported by the literature, but where intracorporal tumor lysis is the treatment goal we believe that the systemic release of tumor products can overwhelm the excretory capacity; therefore, TLS is an inevitable consequence in some patients.

Hypoxia upregulates Bcl-2 expression and suppresses interferon-gamma induced antiangiogenic activity in human tumor derived endothelial cells

BACKGROUND

Hypoxia in solid tumors potentially stimulates angiogenesis by promoting vascular endothelial growth factor (VEGF) production and upregulating VEGF receptor expression. However, it is unknown whether hypoxia can modulate the effect of anti-angiogenic treatment on tumor-derived endothelium.

METHODS

Human tumor-derived endothelial cells (HTDEC) were freshly isolated from surgically removed human colorectal tumors by collagenase/DNase digestion and Percol gradient sedimentation. Cell proliferation was assessed by measuring BrdU incorporation, and capillary tube formation was measured using Matrigel. Cell apoptosis was assessed by flow cytometry and ELISA, and Bcl-2 expression was detected by Western blot analysis.

RESULTS

Under aerobic culture conditions (5% CO2 plus 21% O2) HTDEC expressed less Bcl-2 and were more susceptible to IFN-gamma-induced apoptosis with significant reductions in both cell proliferation and capillary tube formation, when compared with normal human macrovascular and microvascular EC. Following exposure of HTDEC to hypoxia (5% CO2 plus 2% O2), IFN-gamma-induced cell apoptosis, and antiangiogenic activity (i.e. an inhibition in cell proliferation and capillary tube formation) in HTDEC were markedly attenuated. This finding correlated with hypoxia-induced upregulation of Bcl-2 expression in HTDEC.

CONCLUSIONS

These results indicate that hypoxia can protect HTDEC against IFN-gamma-mediated cell death and antiangiogenic activity, and suggest that improvement of tumor oxygenation may potentiate the efficacy of anti-cancer therapies specifically targeting the inhibition of tumor angiogenesis.

Antiseptic wick: does it reduce the incidence of wound infection following appendectomy?

The role of prophylactic antibiotics is well established for contaminated wounds, but the use of antiseptic wound wicks is controversial. The aim of this work was to study the potential use of wound wicks to reduce the rate of infection following appendectomy. This prospective randomized controlled clinical trial was conducted at a university hospital in the department of surgery. The subjects were patients undergoing appendectomy for definite acute appendicitis. They were randomized by computer to primary subcuticular wound closure or use of an antiseptic wound wick. For the latter, ribbon gauze soaked in povidone-iodine was placed between interrupted nylon skin sutures. Wicks were soaked daily and removed on the fourth postoperative day. All patients received antibiotic prophylaxis. They were reviewed while in hospital and 4 weeks following operation for evidence of wound infection. The main outcome measures were wound infection, wound discomfort, and cosmetic result. The overall wound infection rate was 8.6% (15/174). In patients with wound wicks it was 11.6% (10/86) compared to 5.6% (5/88) in those whose wounds were closed by subcuticular sutures (p = NS). We concluded that the use of wound wicks was not associated with decreased wound infection rates following appendectomy. Subcuticular closure is therefore appropriate in view of its greater convenience and safety.

Lung injury in acute pancreatitis: mechanisms, prevention, and therapy

Lung injury is the most pertinent manifestation of extra-abdominal organ dysfunction in pancreatitis. The propensity of this retroperitoneal inflammatory condition to engender a diffuse and life-threatening lung injury is significant. Approximately one third of patients will develop acute lung injury and acute respiratory distress syndrome, which account for 60% of all deaths within the first week. The variability in the clinical course of pancreatitis renders it a vexing entity and makes demonstration of the efficacy of any specific intervention difficult. The distinct pathologic entity of pancreatitis-associated lung injury is reviewed with a focus on etiology and potential therapeutic maneuvers.

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.

Sulfate-reducing bacteria colonize pouches formed for ulcerative colitis but not for familial adenomatous polyposis

PURPOSE

Ileal pouch-anal anastomosis remains the "gold standard" in surgical treatment of ulcerative colitis and familial adenomatous polyposis. Pouchitis occurs mainly in patients with a background of ulcerative colitis, although the reasons for this are unknown. The aim of this study was to characterize differences in pouch bacterial populations between ulcerative colitis and familial adenomatous pouches.

METHODS

After ethical approval was obtained, fresh stool samples were collected from patients with ulcerative colitis pouches (n = 10), familial adenomatous polyposis (n = 7) pouches, and ulcerative colitis ileostomies (n = 8). Quantitative measurements of aerobic and anaerobic bacteria were performed.

RESULTS

Sulfate-reducing bacteria were isolated from 80 percent (n = 8) of ulcerative colitis pouches. Sulfate-reducing bacteria were absent from familial adenomatous polyposis pouches and also from ulcerative colitis ileostomy effluent. Pouch Lactobacilli, Bifidobacterium, Bacteroides sp, and Clostridium perfringens counts were increased relative to ileostomy counts in patients with ulcerative colitis. Total pouch enterococci and coliform counts were also increased relative to ileostomy levels. There were no significant quantitative or qualitative differences between pouch types when these bacteria were evaluated.

CONCLUSIONS

Sulfate-reducing bacteria are exclusive to patients with a background of ulcerative colitis. Not all ulcerative colitis pouches harbor sulfate-reducing bacteria because two ulcerative colitis pouches in this study were free of the latter. They are not present in familial adenomatous polyposis pouches or in ileostomy effluent collected from patients with ulcerative colitis. Total bacterial counts increase in ulcerative colitis pouches after stoma closure. Levels of Lactobacilli, Bifidobacterium, Bacteroides sp, Clostridium perfringens, enterococci, and coliforms were similar in both pouch groups. Because sulfate-reducing bacteria are specific to ulcerative colitis pouches, they may play a role in the pathogenesis of pouchitis.

Quality of life after ileal pouch-anal anastomosis: an evaluation of diet and other factors using the Cleveland Global Quality of Life instrument

PURPOSE

Although functional results after ileal pouch-anal anastomosis are excellent, imperfections of function do occur. In this setting, quality-of-life assessment is an invaluable tool in determining overall therapeutic efficacy. We evaluated the impact of dietary restrictions, preoperative diagnosis (ulcerative colitis vs. familial adenomatous polyposis), and pregnancy (after pouch insertion) on quality of life.

METHODS

After ethical approval, 64 patients were reviewed (mean age, 31 (range, 15-54) years). Long-term quality of life in patients after ileal pouch-anal anastomosis was assessed using the Cleveland Global Quality of Life instrument or Fazio score. The Cleveland Global Quality of Life score is a novel quality-of-life instrument specifically designed for patients with ileal pouches. Stool frequency and continence were recorded to establish the functional status of this group.

RESULTS

Sixty-one patients (95.3 percent) complained of some form of dietary restriction and adopted a fixed dietary regimen. All such patients felt that a breach of this regimen would impinge significantly on their quality of life. Late eating and alcohol were associated with diarrhea, whereas smoking was not. Constipation was infrequently reported. The mean Cleveland Global Quality of Life score of patients with ulcerative colitis (0.81 +/- 0.13) was greater than that of patients with ulcerative colitis and a background of pouchitis (0.78 +/- 0.16; P = 0.042). Whereas postoperative stool frequency in patients with familial adenomatous polyposis was always higher than the preoperative level (4 vs. 2 movements per day; P = 0.04), the Cleveland Global Quality of Life score of this group was lower than that of ulcerative colitis patients (0.77 vs. 0.81; P = 0.047). The Cleveland Global Quality of Life score of females who had had pregnancies after pouch formation was 0.70, significantly lower (P = 0.039) than that of ulcerative colitis patients, although pouch function was similar to the general group (7 vs. 6 daily bowel movements with full continence in all parous patients).

CONCLUSIONS

Most patients suffered dietary restrictions, forcing them to adopt a fixed dietary regimen. Breach of this regimen would impact on their quality of life. Hence composition of diet and timing of intake are important determinants of quality of life after ileal pouch formation. Patients with familial adenomatous polyposis and those with a history of pouchitis had poorer Cleveland Global Quality of Life scores than ulcerative colitis patients without a background of pouchitis. This indicates that they also had poorer quality of life. Parous patients had the lowest Cleveland Global Quality of Life scores, indicating the poorest quality of life. These differences did not correlate with poorer pouch function, highlighting the influence of non-pouch-related factors in quality of life after ileal pouch formation.

Desmoid tumours

Desmoid tumours exhibit fibroblastic proliferation and arise from fascial or musculoaponeurotic structures. Despite their benign microscopic appearance, and their negligible metastatic potential, the propensity of desmoid tumours for local infiltration is potentially significant in terms of deformity, morbidity and mortality due to pressure effects and obstruction of vital structures and organs. The rarity of desmoid tumours, coupled with the variability in their clinical course, renders these lesions a vexing entity, and makes demonstration of the efficacy of any specific intervention difficult. Failure to recognize the potential for malignant behaviour in this tumour renders desmoids susceptible to inadequate treatment. This distinct pathological entity is reviewed with a specific focus on aetiology and treatment.

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.

Minimally invasive, radioguided surgery for primary hyperparathyroidism

BACKGROUND

Primary hyperparathyroidism affects 1 in 700 individuals in the United States. A single adenoma is responsible in over 85% of cases. Surgery remains the most effective treatment. This study was designed to assess the feasibility of minimally invasive radioguided parathyroidectomy (MIRP) with confirmation of excision by ex vivo radioactivity alone.

METHODS

Seventy-five consecutive patients with primary hyperparathyroidism were prospectively studied. Following sestamibi scan, patients underwent unilateral neck exploration guided by a handheld gamma probe, which was also used to measure ex vivo radioactivity of excised tissue.

RESULTS

The sestamibi scan was positive in 88% of the patients. A small incision (mean, 3.2+/-0.3 cm) was sufficient. Ectopic gland sites were localized in five patients with positive scans and single adenomas. Mean operative time was 48 minutes (range, 15-125 minutes), with shorter procedures after the initial 20 cases (mean, 24 vs. 72 minutes; P < .01). Radioguided parathyroidectomy was successful in 97%, with a mean follow-up of 11 months (range, 1-26 months). As noted previously, adenomatous parathyroid glands contained more than 20% of the background radioactivity.

CONCLUSIONS

MIRP is a feasible alternative to bilateral dissection with the advantages of guided dissection and rapid confirmation, and may become the procedure of choice for primary hyperparathyroidism.

Bacterial wall products induce downregulation of vascular endothelial growth factor receptors on endothelial cells via a CD14-dependent mechanism: implications for surgical wound healing

INTRODUCTION

Vascular endothelial growth factor (VEGF) is a potent mitogenic cytokine which has been identified as the principal polypeptide growth factor influencing endothelial cell (EC) migration and proliferation. Ordered progression of these two processes is an absolute prerequisite for initiating and maintaining the proliferative phase of wound healing. The response of ECs to circulating VEGF is determined by, and directly proportional to, the functional expression of VEGF receptors (KDR/Flt-1) on the EC surface membrane. Systemic sepsis and wound contamination due to bacterial infection are associated with significant retardation of the proliferative phase of wound repair. The effects of the Gram-negative bacterial wall components lipopolysaccharide (LPS) and bacterial lipoprotein (BLP) on VEGF receptor function and expression are unknown and may represent an important biological mechanism predisposing to delayed wound healing in the presence of localized or systemic sepsis.

MATERIALS AND METHODS

We designed a series of in vitro experiments investigating this phenomenon and its potential implications for infective wound repair. VEGF receptor density on ECs in the presence of LPS and BLP was assessed using flow cytometry. These parameters were assessed in hypoxic conditions as well as in normoxia. The contribution of CD14 was evaluated using recombinant human (rh) CD14. EC proliferation in response to VEGF was quantified in the presence and absence of LPS and BLP.

RESULTS

Flow cytometric analysis revealed that LPS and BLP have profoundly repressive effects on VEGF receptor density in normoxic and, more pertinently, hypoxic conditions. The observed downregulation of constitutive and inducible VEGF receptor expression on ECs was not due to any directly cytotoxic effect of LPS and BLP on ECs, as measured by cell viability and apoptosis assays. We identified a pivotal role for soluble/serum CD14, a highly specific bacterial wall product receptor, in mediating these effects. The decreased VEGF receptor density on ECs accruing from the presence of bacterial wall products resulted in EC hyporesponsiveness to rhVEGF and significant abolition of VEGF-directed EC proliferation.

CONCLUSION

These findings suggest that the well-recognized relationship between bacterial sepsis and attenuated wound healing may be due, in part, to the directly suppressive effects of bacterial wall components on EC VEGF receptor expression and, consequently, EC proliferation.

Tourniquet-induced systemic inflammatory response in extremity surgery

BACKGROUND

Tourniquet-induced reperfusion injury in animals produces significant systemic inflammatory effects. This study investigated whether a biologic response occurs in a clinically relevant model of tourniquet-induced reperfusion injury.

METHODS

Patients undergoing elective knee arthroscopy were prospectively randomized into controls (no tourniquet) and subjects (tourniquet-controlled). The effects of tourniquet-induced reperfusion on monocyte activation state, neutrophil activation state, and transendothelial migration (TEM) were studied. Changes in the cytokines implicated in reperfusion injury, tumor necrosis factor-alpha, interleukin (IL)-1beta, and IL-10 were also determined.

RESULTS

After 15 minutes of reperfusion, neutrophil and monocyte activation were significantly increased. Pretreatment of neutrophils with pooled subject (ischemia-primed) plasma significantly increased TEM. In contrast, TEM was not significantly altered by ischemia-primed plasma pretreatment of the endothelial monolayer. Significant elevation of tumor necrosis factor-alpha and IL-1beta were observed in subjects compared with controls after 15 minutes of reperfusion. There was no significant difference in serum IL-10 levels between the groups at all the time points studied.

CONCLUSION

These results indicate a transient neutrophil and monocyte activation after tourniquet-ischemia that translates into enhanced neutrophil transendothelial migration with potential for tissue injury.

The angiogenic response to skeletal injury is preserved in the elderly

Angiogenesis is essential for normal bone formation and repair. Avascularity characterizes aberrant fracture union in the elderly, while angiogenic mechanisms during cutaneous wound repair are attenuated in aged humans. We hypothesized that skeletal injury results in local (circulating) and systemic (fracture site) 'angiogenic' responses and that these reparative mechanisms are attenuated with advanced patient age. This prospective study examined peripheral blood and fracture hematoma from 32 patients, 16 under 40 years and 16 over the age of 75, undergoing emergent surgery for isolated fracture. The angiogenic cytokines vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) were assayed. Endothelial cell cultures were supplemented with patient plasma and fracture hematoma and angiogenesis determined in vitro by measuring cell proliferation and blood vessel tube formation. Angiogenesis was determined in vivo using a murine dorsal wound pocket model and quantification of new blood vessel formation after 7 days. We found that all injured patients, irrespective of age, have elevated plasma and fracture hematoma levels of VEGF and PDGF. These elevated cytokine concentrations translate into biologically significant angiogenic effects, in vitro and in vivo. These effects are primarily VEGF mediated and are not dependent on patient age. The biological activity of these growth factors does not diminish with advanced age. Thus skeletal injury does result in local and systemic angiogenic responses whereby angiogenic cytokine availability and activity is preserved in the aged suggesting alternative mechanisms for the development of avascularity in delayed and fracture non-union in the elderly.

Nasogastric intubation causes gastroesophageal reflux in patients undergoing elective laparotomy

BACKGROUND

The routine use of nasogastric tubes in patients undergoing elective abdominal operation is associated with an increased incidence of postoperative fever, atelectasis, and pneumonia. Previous studies have shown that nasogastric tubes have no significant effect on the incidence of gastroesophageal reflux or on lower esophageal sphincter pressure in healthy volunteers. We hypothesized that nasogastric intubation in patients undergoing laparotomy reduces lower esophageal sphincter pressure and promotes gastroesophageal reflux in the perioperative period.

METHODS

A prospective randomized case-control study was undertaken in which 15 consenting patients, admitted electively for bowel surgery, were randomized into 2 groups. Group 1 underwent nasogastric intubation after induction of anesthesia, and Group 2 did not. All patients had manometry and pH probes placed with the aid of endoscopic vision at the lower esophageal sphincter and distal esophagus, respectively. Nasogastric tubes, where present, were left on free drainage, and sphincter pressures and pH were recorded continuously during a 24-hour period. Data were analyzed with 1-way analysis of variance.

RESULTS

The mean number of reflux episodes (defined as pH < 4) in the nasogastric tube group was 137 compared with a median of 8 episodes in the group managed without nasogastric tubes (P =.006). The median duration of the longest episode of reflux was 132 minutes in Group 1 and 1 minute in Group 2 (P =.001). A mean of 13.3 episodes of reflux lasted longer than 5 minutes in Group 1, with pH less than 4 for 37.4% of the 24 hours. This was in contrast to Group 2 where a mean of 0.13 episodes lasted longer than 5 minutes (P =.001) and pH less than 4 for 0.2% of total time (P =.001). The mean lower esophageal sphincter pressures were lower in Group 1. CONCLUSIONS. These findings demonstrate that patients undergoing elective laparotomy with routine nasogastric tube placement have significant gastroesophageal reflux in the perioperative period and a reduced ability to clear refluxed acid from the distal esophagus. Due to the associated risk of postoperative pulmonary complications, we recommend that nasogastric intubation be performed on a selective rather than routine basis.

Synchronous high-risk melanoma and lymphoid neoplasia

Large population-based studies have shown a significant association between melanoma and lymphoid neoplasia, particularly non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukaemia (CLL), that is independent of any treatment received for the initial tumour. This study examines the presentation, diagnosis, treatment and progress of three patients who developed advanced melanoma concurrently with a lymphoid neoplasm (one NHL, two CLLs), in order to illustrate their association, discuss common aetiological factors and examine possible therapeutic options. As it is the melanoma rather than the lymphoid neoplasm that represents the bigger threat to overall survival, initial treatment should be targeted towards this cancer. However, because of the interplay between the diseases and the possible side-effects of the various treatments, the choice of adjuvant therapy requires careful consideration. Immunosuppression associated with chemotherapy may permit a more aggressive course for the melanoma, while locoregional radiotherapy is contraindicated following lymph node dissections. As immunotherapy is of benefit in the treatment of melanoma and has also been recently shown to be effective in the management of lymphoid neoplasia, we instituted interferon-alpha as adjuvant therapy for these patients, thereby utilizing a single agent to treat the dual pathologies. The three patients have now been followed-up for 6 months without evidence of disease recurrence or progression.

Inosine attenuates tourniquet-induced skeletal muscle reperfusion injury

BACKGROUND

Adenosine attenuates skeletal muscle reperfusion injury, but its short half-life in vivo limits potential therapeutic benefits. The aim of this study was to ascertain whether inosine, a stable adenosine metabolite, modulates skeletal muscle reperfusion injury.

MATERIALS AND METHODS

C57BL/6 mice were randomized (8-10 per group) to six groups: time controls; inosine (100 mg/kg) before anesthesia; 2 h of bilateral tourniquet hindlimb ischemia; I/R (2 h of bilateral tourniquet hindlimb ischemia, 3 h of reperfusion); inosine (100 mg/kg) before I/R; drug vehicle before I/R. Serum tumor necrosis factor (TNF)-alpha and macrophage inflammatory protein (MIP)-2 were measured before ischemia and at the end of reperfusion. Tissue edema was determined by wet/dry weight ratios. Tissue leucosequestration was assessed by the myeloperoxidase (MPO) content.

RESULTS

At the end of reperfusion, inosine pretreatment resulted in lower MPO levels in muscle (P = 0.02) and lung (P = 0.0002) than saline pretreatment. Similarly, muscle (P = 0.04) and lung (P = 0.02) wet/dry ratios were significantly reduced with inosine but not with saline pretreatment. At the end of reperfusion, serum proinflammatory cytokine levels (TNF-alpha and MIP-2) were significantly reduced (P < 0.05) compared to preischemia levels following inosine pretreatment but not saline pretreatment. Ischemia alone did not alter any of the parameters assessed.

CONCLUSIONS

These findings demonstrate that pretreatment with inosine attenuates the local and systemic proinflammatory responses associated with skeletal muscle reperfusion injury.

The effect of lidocaine on neutrophil respiratory burst during induction of general anaesthesia and tracheal intubation

BACKGROUND AND OBJECTIVE

Respiratory burst is an essential component of the neutrophil's biocidal function. In vitro, sodium thiopental, isoflurane and lidocaine each inhibit neutrophil respiratory burst. The objectives of this study were (a) to determine the effect of a standard clinical induction/tracheal intubation sequence on neutrophil respiratory burst and (b) to determine the effect of intravenous lidocaine administration during induction of anaesthesia on neutrophil respiratory burst.

METHODS

Twenty ASA I and II patients, aged 18-60 years, undergoing elective surgery were studied. After induction of anaesthesia [fentanyl (2 microg kg-1), thiopental (4-6 mg kg-1), isoflurane (end-tidal concentration 0.5-1.5%) in nitrous oxide (66%) and oxygen], patients randomly received either lidocaine 1.5 mg kg-1 (group L) or 0.9% saline (group S) prior to tracheal intubation. Neutrophil respiratory burst was measured immediately prior to induction of anaesthesia, immediately before and 1 and 5 min after lidocaine/saline.

RESULTS

Neutrophil respiratory burst decreased significantly after induction of anaesthesia in both groups [87.4 +/- 8.2% (group L) and 88.5 +/- 13.4% (group S) of preinduction level (P < 0.01 both groups)]. After intravenous lidocaine (but not saline) administration, neutrophil respiratory burst returned towards preinduction levels, both before (97.1 +/- 23.6%) and after (94.4 +/- 16.6%) tracheal intubation.

CONCLUSION

Induction of anaesthesia and tracheal intubation using thiopentone and isoflurane, inhibit neutrophil respiratory burst. This effect may be diminished by the administration of lidocaine.

A prospective comparison of pedal ergometry with conventional treadmill testing in the investigation of lower extremity pain

BACKGROUND

Investigation of lower extremity pain is compromised by comorbid disorders that may interfere with conventional testing.

AIMS

To compare pedal ergometry with conventional treadmill testing.

METHODS

A prospective study was performed where patients presenting with a diagnosis of intermittent claudication were assessed by both methods of testing.

RESULTS

Of 78 patients studied with both tests, no exercise-induced ankle pressure changes occurred in 26, two were unable to complete either test despite normal pressure measurements, while 24 had exercise-induced pressure drop detected by both tests. Of patients who completed pedal ergometry, 21 were unable to complete the treadmill test, 14 of whom had negative ergometry, while seven had a pressure drop detected by pedal ergometry. Three had pressure changes with pedal ergometry, but not with treadmill testing and two had pressure changes on the treadmill not reproduced by pedal ergometry.

CONCLUSIONS

Pedal ergometer is more sensitive than treadmill testing in detecting arterial insufficiency, as indicated by a 20% or greater fall in ankle pressure, and more suitable in a subgroup of patients unable to tolerate conventional treadmill testing.

Upregulation of Fas-Fas-L (CD95/CD95L)-mediated epithelial apoptosis--a putative role in pouchitis?

INTRODUCTION

Ileal pouch-anal anastomosis (IPAA) remains the gold standard for patients with refractory ulcerative colitis. Pouchitis causes considerable morbidity in 40% of patients with IPAA. This study examined the role of increased epithelial apoptosis in the etiology of pouchitis.

METHODS

Following ethical approval pouch biopsies taken from patients with a history of pouchitis were compared with age-matched controls from patients who were pouchitis free. Apoptosis was detected immunohistochemically using a monoclonal antibody (M30) and terminal deoxyribonucleotidyl transferase (TDT)-mediated dUTP-digoxigenin end labeling (TUNEL). Villous atrophy was assessed histologically and correlated with levels of apoptosis. Epithelial Fas-ligand (L) was also assessed immunohistochemically.

RESULTS

A significant increase in TUNEL staining was seen at the epithelial but not at the lamina propria level for known pouchitis patients versus controls (0.091 vs 0.035; P < 0.01). Similarly, epithelial M30 immunoreactivity (0.225 vs 0.082; P < 0.05) and villous atrophy (0.035 vs 0.10; P < 0.05) were significantly increased in pouches with previous pouchitis when compared with normal pouches. Upregulation of Fas-L expression was characteristic of this epithelium. Mononuclear cells were strongly positive for Fas-L. Increased epithelial levels of apoptosis correlated with increased levels of villous atrophy.

CONCLUSIONS

Our data suggest a role for elevated Fas-Fas-L (CD95-CD95L)-mediated epithelial apoptosis in the etiology of pouchitis. Increased levels of villous atrophy may result from increased apoptosis and thereby predispose to infection by otherwise apathogenic organisms.

Activated human neutrophils release hepatocyte growth factor/scatter factor

BACKGROUND

Hepatocyte growth factor or scatter factor (HGF/SF) is a pleiotropic cytokine that has potent angiogenic properties. We have previously demonstrated that neutrophils (PMN) are directly angiogenic by releasing vascular endothelial growth factor (VEGF). We hypothesized that the acute inflammatory response can stimulate PMN to release HGF.

AIMS

To examine the effects of inflammatory mediators on PMN HGF release and the effect of recombinant human HGF (rhHGF) on PMN adhesion receptor expression and PMN VEGF release.

METHODS

In the first experiment, PMN were isolated from healthy volunteers and stimulated with tumour necrosis factor-alpha (TNF-alpha), lipopolysaccharide (LPS), interleukin-8 (IL-8), and formyl methionyl-leucyl-phenylalanine (fMLP). Culture supernatants were assayed for HGF using ELISA. In the second experiment, PMN were lysed to measure total HGF release and HGF expression in the PMN was detected by Western immunoblotting. Finally, PMN were stimulated with rhHGF. PMN CD 11a, CD 11b, and CD 18 receptor expression and VEGF release was measured using flow cytometry and ELISA respectively.

RESULTS

TNF-alpha, LPS and fMLP stimulation resulted in significantly increased release of PMN HGF (755+/-216, 484+/-221 and 565+/-278 pg/ml, respectively) compared to controls (118+/-42 pg/ml). IL-8 had no effect. Total HGF release following cell lysis and Western blot suggests that HGF is released from intracellular stores. Recombinant human HGF did not alter PMN adhesion receptor expression and had no effect on PMN VEGF release.

CONCLUSIONS

This study demonstrates that pro-inflammatory mediators can stimulate HGF release from a PMN intracellular store and that activated PMN in addition to secreting VEGF have further angiogenic potential by releasing HGF.

Proinflammatory effects of bacterial lipoprotein on human neutrophil activation status, function and cytotoxic potential in vitro

Bacterial lipoprotein (BLP) is the most abundant protein in gram-negative bacterial cell walls, heavily outweighing lipopolysaccharide (LPS). Herein we present findings demonstrating the potent in vitro effects of BLP on neutrophil (PMN) activation status, function, and capacity to transmigrate an endothelial monolayer. PMNs are the principal effectors of the initial host response to injury or infection and constitute a significant threat to invading bacterial pathogens. The systemic inflammatory response syndrome (SIRS) is characterised by significant host tissue injury mediated, in part, by uncontrolled regulation of PMN cytotoxic activity. We found that BLP-activated human PMN as evidenced by increased CD11b/CD18 (Mac-1) expression. Up-regulation of PMN Mac-1 in response to BLP occurred independently of membrane-bound CD14 (mCD14). A similar up-regulation of intercellular adhesion molecule-1 (ICAM-1) on endothelial cells was observed whilst E-Selectin expression was unaffected. PMN transmigration across a human umbilical vein endothelial cell (HUVEC) monolayer was markedly increased after treating either PMN's or HUVEC independently with BLP. This increased transmigration did not occur as a result of any direct effect of BLP on HUVEC monolayer permeability, assessed objectively using the passage of FITC-labeled Dextran-70. BLP primed PMN for enhanced respiratory burst and superoxide anion production in response to PMA, but did not influence phagocytosis of opsonized Escherichia coli. BLP far exceeds LPS as a gram-negative bacterial wall component, these findings therefore implicate BLP as an additional putative mediator of SIRS arising from gram-negative infection.

Role of taurine in preventing acetaminophen-induced hepatic injury in the rat

Acetaminophen overdose causes acute liver injury in both humans and animals. This study was designed to investigate the potential role of the conditionally essential amino acid taurine in preventing acetaminophen-induced hepatotoxicity. Male Sprague-Dawley rats were administered acetaminophen (800 mg/kg) intraperitoneally. Taurine (200 mg/kg) was given 12 h before, at the time of, and 1 or 2 h after acetaminophen injection. Acetaminophen treatment increased the plasma levels of aspartate transaminase, alanine aminotransferase, and alkaline phosphatase and caused hepatic DNA fragmentation and hepatocyte necrosis. Taurine administered before, simultaneously with, or 1 h after acetaminophen resulted in significant improvement in hepatic injury as represented by decrease of hepatocellular enzyme release and attenuation of hepatocyte apoptosis and necrosis, and this correlated with taurine-mediated attenuation of hepatic lipid peroxidation. These results indicate that taurine possesses prophylactic and therapeutic effects in acetaminophen-induced hepatic injury.

Tumor cell adhesion to endothelial cells is increased by endotoxin via an upregulation of beta-1 integrin expression

BACKGROUND

Recent studies have demonstrated that metastatic disease develops from tumor cells that adhere to endothelial cells and proliferate intravascularly. The beta-1 integrin family and its ligand laminin have been shown to be important in tumor-to-endothelial cell adhesion. Lipopolysaccharide (LPS) has been implicated in the increased metastatic tumor growth that is seen postoperatively. We postulated that LPS increases tumor cell expression of beta-1 integrins and that this leads to increased adhesion.

METHODS

The human metastatic colon cancer cell line LS174T was labeled with an enhanced green fluorescent protein (eGFP) using retroviral transfection. Cell cultures were treated with LPS for 1, 2, and 4 h (n = 6 each) and were subsequently cocultured for 30 or 120 min with confluent human umbilical vein endothelial cells (HUVECs), to allow adherence. Adherent tumor cells were counted using fluorescence microscopy. These experiments were carried out in the presence or absence of a functional blocking beta-1 integrin monoclonal antibody (4B4). Expression of beta-1 integrin and laminin on tumor and HUVECs was assessed using flow cytometric analysis. Tumor cell NF-kappaB activation after incubation with LPS was measured.

RESULTS

Tumor cell and HUVEC beta-1 integrin expression and HUVEC expression of laminin were significantly (P < 0.05) enhanced after incubation with LPS. Tumor cell adhesion to HUVECs was significantly increased. Addition of the beta-1 integrin blocking antibody reduced tumor cell adhesion to control levels. LPS increased tumor cell NF-kappaB activation.

CONCLUSIONS

Exposure to LPS increases tumor cell adhesion to the endothelium through a beta-1 integrin-mediated pathway that is NF-kappaB dependent. This may provide a target for immunotherapy directed at reducing postoperative metastatic tumor growth.

Gallstones and laparoscopic cholecystectomy in hepatitis C patients

Our aims were to determine the incidence of gallstones in a cohort of patients infected with hepatitis C for 20 years, and to analyse the outcome of all patients infected with hepatitis C undergoing laparoscopic cholecystectomy. A hepatitis C screening programme in place in Ireland since 1994 identified 965 patients with hepatitis C antibodies out of 62,667 patients screened. The hepatology unit of Cork University Hospital has 318 patients with hepatitis C. Of patients identified by screening, 201 were post partum women infected via contaminated Anti-D immunoglobulin administered in 1977. Thirty-five (17.4%) of two hundred and one patients with hepatitis C since 1977 had developed gallstones after twenty years. A total of 34 patients with hepatitis C underwent laparoscopic cholecystectomy. One patient required conversion to open cholecystectomy. There were no complications and no mortality. There was a low rate of cirrhosis (11%) on examining liver histology. The incidence of gallstones in a cohort of patients infected with hepatitis C for twenty years approximates to that of the general population. The low rate of cirrhosis in this group may be related to a low consumption of alcohol. Laparoscopic cholecystectomy is a safe procedure in patients with mild chronic liver disease caused by hepatitis C.

Human neutrophils facilitate tumor cell transendothelial migration

Tumor cell extravasation plays a key role in tumor metastasis. However, the precise mechanisms by which tumor cells migrate through normal vascular endothelium remain unclear. In this study, using an in vitro transendothelial migration model, we show that human polymorphonuclear neutrophils (PMN) assist the human breast tumor cell line MDA-MB-231 to cross the endothelial barrier. We found that tumor-conditioned medium (TCM) downregulated PMN cytocidal function, delayed PMN apoptosis, and concomitantly upregulated PMN adhesion molecule expression. These PMN treated with TCM attached to tumor cells and facilitated tumor cell migration through different endothelial monolayers. In contrast, MDA-MB-231 cells alone did not transmigrate. FACScan analysis revealed that these tumor cells expressed high levels of intercellular adhesion molecule-1 (ICAM-1) but did not express CD11a, CD11b, or CD18. Blockage of CD11b and CD18 on PMN and of ICAM-1 on MDA-MB-231 cells significantly attenuated TCM-treated, PMN-mediated tumor cell migration. These tumor cells still possessed the ability to proliferate after PMN-assisted transmigration. These results indicate that TCM-treated PMN may serve as a carrier to assist tumor cell transendothelial migration and suggest that tumor cells can exploit PMN and alter their function to facilitate their extravasation.

Adenosine inhibits neutrophil vascular endothelial growth factor release and transendothelial migration via A2B receptor activation

The effects of adenosine on neutrophil (polymorphonuclear neutrophils; PMN)-directed changes in vascular permeability are poorly characterized. This study investigated whether adenosine modulates activated PMN vascular endothelial growth factor (vascular permeability factor; VEGF) release and transendothelial migration. PMN activated with tumour necrosis factor-alpha (TNF-alpha, 10 ng/mL) were incubated with adenosine and its receptor-specific analogues. Culture supernatants were assayed for VEGF. PMN transendothelial migration across human umbilical vein endothelial cell (HUVEC) monolayers was assessed in vitro. Adhesion molecule receptor expression was assessed flow cytometrically. Adenosine and some of its receptor-specific analogues dose-dependently inhibited activated PMN VEGF release. The rank order of potency was consistent with the affinity profile of human A2B receptors. The inhibitory effect of adenosine was reversed by 3,7-dimethyl-1-propargylxanthine, an A2 receptor antagonist. Adenosine (100 microM) or the A2B receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA, 100 microM) significantly reduced PMN transendothelial migration. However, expression of activated PMN beta2 integrins and HUVEC ICAM-1 were not significantly altered by adenosine or NECA. Adenosine attenuates human PMN VEGF release and transendothelial migration via the A2B receptor. This provides a novel target for the modulation of PMN-directed vascular hyperpermeability in conditions such as the capillary leak syndrome.

Ingested foreign bodies in the paediatric patient

BACKGROUND

Paediatric foreign body (FB) ingestion is a common problem and while most can be managed conservatively, a sub-population require intervention.

AIMS

To establish clear guidelines for management of paediatric FB ingestion.

METHODS

A retrospective chart review analysing all paediatric admissions with FB ingestion over a 10-year period from 1990 to 1999.

RESULTS

Of 339 patients presenting to the accident and emergency department with FB ingestion, 59 required admission. Ingestion was accidental in 93.0% of patients. The reasons for admission were as follows: large FBs; dangerous FBs; and living far from the hospital. Nineteen patients (32.2%) were discharged without intervention. Thirty-seven (62.7%) required endoscopic retrieval. In two, the FB was not identified at endoscopy. Only three (5%) required surgery.

CONCLUSION

Conservative management of FB ingestion in the paediatric population is possible in the majority of cases. However, a minority require intervention. While guidelines for intervention are ill-defined, definitive indications include symptomatic patients, or dangerous objects.

Sodium hyaluronate enhances colorectal tumour cell metastatic potential in vitro and in vivo

BACKGROUND

Sodium hyaluronate has been used intraperitoneally to prevent postoperative adhesions. However, the effect of sodium hyaluronate on tumour growth and metastasis in vitro and in vivo is still unknown.

METHODS

Human colorectal tumour cell lines SW480, SW620 and SW707 were treated with sodium hyaluronate (10-500 microg/ml) and carboxymethylcellulose (0.125-1 per cent), and tumour cell proliferation and motility were determined in vitro. For the in vivo experiments male BD IX rats were randomized to a sodium hyaluronate group (n = 11; intraperitoneal administration of 0.5 x 10(6) DHD/K12 tumour cells and 5 ml 0.4 per cent sodium hyaluronate) or a phosphate-buffered saline group (n = 11; 0.5 x 10(6) DHD/K12 tumour cells and 5 ml phosphate-buffered saline intraperitoneally). Four weeks later the intraperitoneal tumour load was visualized directly.

RESULTS

In vitro sodium hyaluronate increased tumour cell proliferation and motility significantly. Sodium hyaluronate-induced tumour cell motility appeared to be CD44 receptor dependent, whereas sodium hyaluronate-induced tumour cell proliferation was CD44 receptor independent. In vivo there was a significantly higher total tumour nodule count in the peritoneal cavity of the sodium hyaluronate-treated group compared with the control (P = 0.016).

CONCLUSION

Sodium hyaluronate enhances tumour metastatic potential in vitro and in vivo, which suggests that use of sodium hyaluronate to prevent adhesions in colorectal cancer surgery may also potentiate intraperitoneal tumour growth. Presented to the Patey Prize Session of the Surgical Research Society and the annual scientific meeting of the Association of Surgeons of Great Britain and Ireland, Brighton, UK, 4-7 May 1999

The effect of the anaesthetic agent isoflurane on the rate of neutrophil apoptosis in vitro

BACKGROUND

Volatile anaesthetic agents influence neutrophil function, and potentially, the inflammatory response to surgery.

AIM

The objective of this study was to determine the effect of isoflurane (1-4%) on human polymorphonuclear neutrophil apoptosis in vitro.

METHODS

Venous blood from 12 healthy volunteers was exposed to 0, 1, and 4% isoflurane delivered via a 14G Wallace flexihub internal jugular cannula, at a fresh gas flow of 0.51/min for 5 minutes. Isolated neutrophils were assessed for apoptosis at 1, 12, and 24 hours in culture using dual staining with annexin V-FITC and propidium iodide (Annexin-V FITC assay). Data were analysed using paired, one-tailed Student's t-tests. p<0.05 was considered significant.

RESULTS

At 1 hour apoptosis was inhibited in the 1% (5.1 [6.8]%; p=0.017) and 4% (4.8 [4.5]%; p=0.008) isoflurane groups compared to control (11.3 [6.9]%). At 12 and 24 hours, a dose-dependent inhibition of apoptosis was demonstrated, i.e. 4% > 1% > 0%.

CONCLUSION

Human neutrophil apoptosis is inhibited in a concentration-dependent manner in vitro by isoflurane in clinical concentrations.

Biological behaviour and clinical implications of micrometastases

BACKGROUND

The most important prognostic determinant in cancer is the identification of disseminated tumour burden (metastases). Micrometastases are microscopic (smaller than 2 mm) deposits of malignant cells that are segregated spatially from the primary tumour and depend on neovascular formation (angiogenesis) to propagate.

METHODS

The electronic literature (1966 to present) on micrometastases and their implications in malignant melanoma and epithelial cancers was reviewed.

RESULTS

Immunohistochemical techniques combined with serial sectioning offer the best accuracy for detection of nodal micrometastases. Molecular techniques should be reserved for blood samples or bone marrow aspirates. Detection of micrometastases in regional lymph nodes and/or bone marrow confers a poor prognosis in epithelial cancers. The concept of sentinel node biopsy combined with serial sectioning and dedicated screening for micrometastases may improve staging procedures. Strategies against angiogenesis may provide novel therapies to induce and maintain micrometastatic dormancy.

CONCLUSION

The concept of micrometastases has resulted in a paradigm shift in the staging of epithelial tumours and our overall understanding of malignant processes.

Thromboprophylaxis using a low molecular weight heparin delays fracture repair

Low molecular weight heparins are significantly superior to unfractionated heparin or warfarin in the prevention of thromboembolic episodes associated with orthopaedic surgery. Therapeutic doses of heparin and warfarin have been shown to delay bone repair in a rabbit model. The current study investigated the effect of prophylactic administration of a low molecular weight heparin, enoxaparin, on the healing of a closed rabbit rib fracture. Fracture healing was assessed using histomorphometric, histologic, and immunohistochemical methods at 3, 7, and 14 days, and biomechanical testing with torsional loading was assessed after 21 days. Bone repair was significantly attenuated at all times in animals receiving subcutaneous enoxaparin compared with that of the control animals. Numerous putative mechanisms for this phenomenon are discussed, and additional studies are proposed to elucidate the effects of this pharmacologically diverse group of compounds on all aspects of bone physiology and repair.

Taurolidine inhibits tumor cell growth in vitro and in vivo

BACKGROUND

Taurolidine, a derivative of the amino acid taurine, exhibits antiendotoxin, antibacterial, and antiadherence activity. We hypothesized that Taurolidine may inhibit tumor cell growth, both in an in vitro and in vivo setting. Our aim was to examine the effect of Taurolidine on the growth of a rat metastatic colorectal tumor cell line (DHD/K12/TRb) in vitro and in vivo.

METHODS

In the in vitro experiments, DHD/K12/TRb cells were incubated with 5, 10, 15, 25, microg/ml of Taurolidine. Cells incubated in culture medium alone were used as controls. Cell proliferation, cell viability, cell death, and cell apoptosis were measured using commercially available techniques. In the in vivo experiment, BD IX rats were randomized into two groups (n = 10/group). Group A (control) underwent laparotomy and instillation of DHD/K12/TRb tumor cells intraperitoneally followed by phosphate buffered saline (PBS). Group B received Taurolidine (100 mg/kg) instead of PBS. Animals were killed after 24 days and tumor burden assessed by counting the number of tumor nodules in the peritoneal cavity.

RESULTS

Incubation of the tumor cells with Taurolidine resulted in a 4-fold decrease in proliferation rates (25+/-4% vs. 100+/-28% for controls) and a 4-fold increase in cell necrosis as demonstrated by the increase in LDH release (403+/-28% vs. 100+/-26% for controls), at a Taurolidine concentration of 25 microg/ml. A dose-dependent decrease in cell viability was also observed. In the in vivo study, local Taurolidine administration resulted in significant decreases in tumor burden (3+/-1 nodules in Group B animals vs. 649+/-101 nodules in Group A animals).

CONCLUSIONS

Taurolidine inhibits the growth of a rat metastatic colorectal tumor cell line in vitro and in vivo and thus may have potential in the prevention of peritoneal metastases.

Hypertonic saline attenuates end-organ damage in an experimental model of acute pancreatitis

BACKGROUND

Hypertonic saline (HTS) has been noted previously to reduce neutrophil activation. The aim of this study was to elucidate the effect of hypertonic resuscitation on the development of end-organ damage in an animal model of pancreatitis.

METHODS

Pancreatitis was induced in Sprague-Dawley rats by intraperitoneal injection of 20 per cent L-arginine. Animals were randomized into four groups (each n = 8): controls; pancreatitis without intervention; pancreatitis plus intravenous resuscitation with normal saline (0.9 per cent sodium chloride 2 ml/kg) at 24 and 48 h; or HTS (7.5 per cent sodium chloride 2 ml/kg) at these time points. Pulmonary endothelial leakage was assessed by measurement of lung wet : dry ratios, bronchoalveolar lavage protein and myeloperoxidase activity.

RESULTS

Animals that received HTS showed less pancreatic damage than those resuscitated with normal saline (1.0 versus 3.0; P = 0.04). Lung injury scores were also significantly diminished in the HTS group (1.0 versus 3.5; P = 0.03). Pulmonary neutrophil sequestration (myeloperoxidase activity 1.80 units/g) and increased endothelial permeability (bronchoalveolar lavage protein content 1287 microgram/ml) were evident in animals resuscitated with normal saline compared with HTS (1.22 units/g and 277 microgram/ml respectively; P < 0.02).

CONCLUSION

HTS resuscitation results in a significant attenuation of end-organ injury following a systemic inflammatory response to severe pancreatitis.

Dopamine attenuates the chemoattractant effect of interleukin-8: a novel role in the systemic inflammatory response syndrome

Activated neutrophil (PMN) adherence to vascular endothelium comprises a key step for both transendothelial migration and initiation of potentially deleterious release of PMN products. The biogenic amine, dopamine (DA), has been used for several decades in patients to maintain hemodynamic stability. The effect of dopamine on PMN transendothelial migration and adhesion receptor expression and on the endothelial molecules, E-selectin and ICAM-1, was evaluated. PMN were isolated from healthy controls, stimulated with lipopolysaccharide (LPS), and tumor necrosis factor-alpha (TNF-alpha) and treated with dopamine. CD 11b and CD 18 PMN adhesion receptor expression were assessed flow cytometrically. In a separate experiment, the chemoattractant peptide, IL-8, was placed in the lower chamber of transwells, and PMN migration was assessed. Human umbilical vein endothelial cells (HUVEC) were stimulated with LPS/TNF-alpha and incubated with dopamine. ICAM-1 and E-selectin endothelial molecule expression were assessed flow cytometrically. There was a significant increase in transendothelial migration in stimulated PMN compared with normal PMN (40 vs. 14%, P < 0.001). In addition, PMN CD11b/CD18 was significantly upregulated in stimulated PMN compared with normal PMN (252.4/352.4 vs. 76.7/139.4, P < 0.001) as were endothelial E-selectin/ICAM-1 expression compared with normal EC (8.1/9 vs. 3.9/3.8, P < 0.05). After treatment with dopamine, PMN transmigration was significantly decreased compared with stimulated PMN (8% vs. 40%, P < 0.001). Furthermore, dopamine also attenuated PMN CD11b/CD18 and the endothelial molecules E-selectin and ICAM-1 compared with stimulated PMN/EC that were not treated dopamine (174/240 vs. 252/352, P < 0.05 and 4/4.4 vs. 8.1/9, P < 0.05. respectively). The chemoattractant effect of IL-8 was also attenuated. These results identify for the first time that dopamine attenuates the initial interaction between PMN and the endothelium, and consequently, modulates PMN exudation. Thus, biogenic amines, including dopamine, may function as anti-inflammatory cytokines.

Is human fracture hematoma inherently angiogenic?

This study attempts to explain the cellular events characterizing the changes seen in the medullary callus adjacent to the interfragmentary hematoma during the early stages of fracture healing. It also shows that human fracture hematoma contains the angiogenic cytokine vascular endothelial growth factor and has the inherent capability to induce angiogenesis and thus promote revascularization during bone repair. Patients undergoing emergency surgery for isolated bony injury were studied. Raised circulating levels of vascular endothelial growth factor were seen in all injured patients, whereas the fracture hematoma contained significantly higher levels of vascular endothelial growth factor than did plasma from these injured patients. However, incubation of endothelial cells in fracture hematoma supernatant significantly inhibited the in vitro angiogenic parameters of endothelial cell proliferation and microtubule formation. These phenomena are dependent on a local biochemical milieu that does not support cytokinesis. The hematoma potassium concentration is cytotoxic to endothelial cells and osteoblasts. Subcutaneous transplantation of the fracture hematoma into a murine wound model resulted in new blood vessel formation after hematoma resorption. This angiogenic effect is mediated by the significant concentrations of vascular endothelial growth factor found in the hematoma. This study identifies an angiogenic cytokine involved in human fracture healing and shows that fracture hematoma is inherently angiogenic. The differences between the in vitro and in vivo findings may explain the phenomenon of interfragmentary hematoma organization and resorption that precedes fracture revascularization.

General versus regional anaesthesia for cataract surgery: effects on neutrophil apoptosis and the postoperative pro-inflammatory state

At clinically relevant concentrations, volatile anaesthetic agents influence neutrophil function. Our hypothesis was that sevoflurane would inhibit neutrophil apoptosis and consequently influence the postoperative pro-inflammatory state. In order to identify selectively the effect of the anaesthetic agent sevoflurane, we studied patients undergoing minimally stimulating (cataract) surgery randomly allocated to receive either sevoflurane (n = 11) or local anaesthesia (n = 12). Venous blood samples were taken immediately prior to anaesthesia and at 1, 8 and 24 h thereafter. The rate of neutrophil apoptosis, plasma concentration of cytokines and differential white cell count were measured. The rates of neutrophil apoptosis and plasma concentrations of IL-1beta, TNF-alpha and IL-8 at each time point were similar in the two groups. IL-6 concentrations increased significantly and to a similar extent compared to preanaesthetic levels at 8 and 24 h. This study demonstrates that sevoflurane does not influence the rate of neutrophil apoptosis, cytokine concentrations and neutrophil count following cataract surgery.

Neutrophil-induced transmigration of tumour cells treated with tumour-conditioned medium is facilitated by granulocyte-macrophage colony-stimulating factor

OBJECTIVE

To investigate the effect of different cytokines that are present in tumour-conditioned medium on human neutrophil (PMN)-induced tumour cell transmigration.

DESIGN

Laboratory study.

SETTING

University hospital, Ireland.

MATERIAL

Isolated human PMN and cultured human breast tumour cell line, MDA-MB-231.

INTERVENTIONS

Human PMN treated with either tumour-conditioned medium or different media neutralised with monoclonal antibodies (MoAb), and MDA-MB-231 cells were plated on macrovascular and microvascular endothelial monolayers in collagen-coated transwells to assess migration of tumour cells.

MAIN OUTCOME MEASURES

Cytokines present in tumour-conditioned medium, PMN cytocidal function and receptor expression, and tumour cell transmigration.

RESULTS

tumour-conditioned medium contained high concentrations of granulocyte-macrophage colony-stimulating factor (GM-CSF), vascular endothelial growth factor (VEGF), and interleukin 8 (IL-8), but not granulocyte colony-stimulating factor (G-CSF) and interleukin 3 (IL-3). Anti-GM-CSF MoAb significantly reduced PMN-induced transmigration of tumour cells treated with tumour-conditioned medium (p < 0.05), whereas anti-VEGF and anti-IL-8 MoAbs did not affect their migration. In addition, anti-GM-CSF MoAb, but not anti-VEGF or anti-IL-8 MoAb, reduced PMN CD11b and CD18 overexpression induced by tumour-conditioned medium (p < 0.05).

CONCLUSION

These results indicate that the GM-CSF that is present in tumour-conditioned medium may be involved, at least in part, in alterations in PMN function mediated by the medium and subsequently PMN-induced transmigration of tumour cells.

The role of endotoxin/lipopolysaccharide in surgically induced tumour growth in a murine model of metastatic disease

Surgical removal of a primary tumour is often followed by rapid growth of previously dormant metastases. Endotoxin or lipopolysaccharide, a cell wall constituent of Gram-negative bacteria, is ubiquitously present in air and may be introduced during surgery. BALB/c mice received a tail vein injection of 10(5) 4T1 mouse mammary carcinoma cells. Two weeks later, animals were subjected to surgical trauma or an intraperitoneal injection of endotoxin (10 microg per animal). Five days later, animals which underwent open surgery, laparoscopy with air sufflation or received an endotoxin injection displayed increased lung metastasis compared to anaesthetic controls. These increases in metastatic tumour growth were reflected in increased tumour cell proliferation and decreased apoptosis within lung metastases. Circulating levels of the angiogenic cytokine, vascular endothelial growth factor (VEGF), were also elevated in these groups and correlated with increased plasma levels of endotoxin. Endotoxin treatment for 18 h (>10 ng ml(-1)) directly up-regulated VEGF production by the 4T1 tumour cells in vitro. Metastatic tumour growth in mice undergoing carbon dioxide laparoscopy, where air is excluded, was similar to anaesthetic controls. These data indicate that endotoxin introduced during surgery is associated with the enhanced growth of metastases following surgical trauma, by altering the critical balances governing cellular growth and angiogenesis.

Proinflammatory mediators stimulate neutrophil-directed angiogenesis

BACKGROUND

Vascular endothelial growth factor (VEGF; vascular permeability factor) is one of the most potent proangiogenic cytokines, and it plays a central role in mediating the process of angiogenesis or new blood vessel formation. Neutrophils (PMNs) recently have been shown to produce VEGF.

HYPOTHESIS

The acute inflammatory response is a potent stimulus for PMN-directed angiogenesis.

METHODS

Neutrophils were isolated from healthy volunteers and stimulated with lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), and anti-human Fas monoclonal antibody. Culture supernatants were assayed for VEGF using enzyme-linked immunosorbent assays. Culture supernatants from LPS- and TNF-alpha-stimulated PMNs were then added to human umbilical vein endothelial cells and human microvessel endothelial cells and assessed for endothelial cell proliferation using 5-bromodeoxyuridine labeling. Tubule formation was also assessed on MATRIGEL basement membrane matrix. Neutrophils were lysed to measure total VEGF release, and VEGF expression was detected using Western blot analysis.

RESULTS

Lipopolysaccharide and TNF-alpha stimulation resulted in significantly increased release of PMN VEGF (532+/-49 and 484+/-80 pg/mL, respectively; for all, presented as mean +/- SEM) compared with control experiments (32+/-4 pg/mL). Interleukin 6 and Fas had no effect. Culture supernatants from LPS- and TNF-alpha-stimulated PMNs also resulted in significant increases (P<.005) in macrovascular and microvascular endothelial cell proliferation and tubule formation. Adding anti-human VEGF-neutralizing polyclonal antibody to stimulated PMN supernatant inhibited these effects. Total VEGF release following cell lysis and Western blot analysis suggests that the VEGF is released from an intracellular store.

CONCLUSION

Activated human PMNs are directly angiogenic by releasing VEGF, and this has important implications for inflammation, capillary leak syndrome, wound healing, and tumor growth.

Nitric oxide synthetase and Helicobacter pylori in patients undergoing appendicectomy

BACKGROUND: This study was designed to determine whether Helicobacter pylori forms part of the normal microenvironment of the appendix, whether it plays a role in the pathogenesis of acute appendicitis, and whether it is associated with increased expression of inducible nitric oxide synthetase (iNOS) in appendicular macrophages. METHODS: Serology for H. pylori was performed on 51 consecutive patients undergoing emergency appendicectomy. Appendix samples were tested for urease activity, cultured and stained for H. pylori, graded according to the degree of inflammatory infiltrate, and probed immunohistochemically for iNOS expression. RESULTS: The mean age of the patients was 21 (range 7-51) years. Seventeen patients (33 per cent) were seropositive for H. pylori but no evidence of H. pylori was found in any appendix specimen. However, an enhanced inflammatory cell infiltration was observed in seropositive patients (P < 0.04) and the expression of macrophage iNOS in the mucosa of normal and inflamed appendix specimens was increased (P < 0.01). CONCLUSION: H. pylori does not colonize the appendix and is unlikely to be a pathogenic stimulus for appendicitis. Priming effects on mucosal immunology downstream from the foregut may occur after infection with H. pylori.

Taurine prevents high-glucose-induced human vascular endothelial cell apoptosis

Elevated blood glucose in uncontrolled diabetes is causally correlated with diabetic microangiopathy. Hyperglycemia-triggered accelerated endothelial cell apoptosis is a critical event in the process of diabetes-associated microvascular disease. The conditionally semiessential amino acid taurine has been previously shown to protect against human endothelial cell apoptosis. Therefore, this study was designed to investigate the role of taurine in the prevention of high-glucose-mediated cell apoptosis in human umbilical vein endothelial cells (HUVEC) and the mechanisms involved. Exposure of HUVEC to 30 mM glucose for 48 h (short-term) and 14 days (long-term) resulted in a significant increase in apoptosis, compared with normal glucose (5.5 mM; P < 0.05). High-glucose-induced DNA fragmentation preferentially occurred in the S phase cells. Mannitol (as osmotic control) at 30 mM failed to induce HUVEC apoptosis. Taurine prevented high-glucose-induced HUVEC apoptosis, which correlates with taurine attenuation of high-glucose-mediated increased intracellular reactive oxygen species (ROS) formation and elevated intracellular Ca(2+) concentration ([Ca(2+)](i)) level. Antioxidants, DMSO, N-acetyl cysteine, and glutathione, only partly attenuated high-glucose-induced HUVEC apoptosis. Glucose at 30 mM did not cause HUVEC necrosis. However, both glucose and mannitol at 60 mM caused HUVEC necrosis as represented by increased lactate dehydrogenase release and cell lysis. Taurine failed to prevent hyperosmolarity-induced cell necrosis. These results demonstrate that taurine attenuates hyperglycemia-induced HUVEC apoptosis through ROS inhibition and [Ca(2+)](i) stabilization and suggest that taurine may exert a beneficial effect in preventing diabetes-associated microangiopathy.

Inhibition of neutrophil apoptosis after elective surgery

BACKGROUND

Neutrophils play a crucial role in host defense against infections, but their inappropriate infiltration and activation within tissues can cause host tissue damage through release of reactive oxygen metabolites, metalloproteinases, and proinflammatory cytokines. The termination of a neutrophil-mediated inflammatory response is effected through programmed cell death or apoptosis. Delayed neutrophil apoptosis is associated with proinflammatory diseases, such as the systemic inflammatory response syndrome. Surgery induces a profound inflammatory response; therefore, neutrophil apoptosis of patients undergoing elective surgery was investigated.

METHODS

Nonseptic patients undergoing elective orthopedic surgery while under epidural anesthesia had neutrophils and platelet-poor isolated from whole venous blood harvested at 4 time points: pre-epidural, 45 minutes postepidural but before surgical intervention, 1 hour postsurgical incision, and 24 hours postsurgery. Neutrophil apoptosis was quantified at 1, 12, and 24 hours in culture by immunofluorescence flow cytometry of annexin V and propidium iodide staining and confirmed by TUNEL (terminal deoxynucleotidyl transferase nick end labeling) assay for DNA strand breaks. Serum cytokines were quantified by specific enzyme-linked immunosorbent assay.

RESULTS

Spontaneous neutrophil apoptosis after elective surgery was significantly (P < .001) inhibited with an effect evident within an hour of surgical incision and persisting at 24 hours postsurgery. The addition of patients' 24 hour postoperative plasma to healthy neutrophils markedly (P < .01) reduced neutrophil apoptosis, whereas plasma taken an hour after surgical incision was ineffective. Interleukin (IL)-6 was notably increased (1395 +/- 196 pg/mL, P < .01) 24 hours postsurgery and at this postoperative concentration inhibited (P < .01) apoptosis of normal neutrophils. Levels of other inflammatory mediators (IL-1 beta, tumor necrosis factor alpha, granulocyte-macrophage colony-stimulating factor, soluble Fas, soluble Fas ligand) were unaltered. The anti-inflammatory cytokine IL-10 was only slightly increased 24 hours postsurgery (8.32 +/- 2.99 pg/mL); however, the addition of recombinant human IL-10 (10 ng/mL) counteracted (P < .05) inhibition of neutrophil apoptosis induced by IL-6 and post-surgery plasma.

CONCLUSIONS

These results identify marked inhibition of neutrophil apoptosis after elective surgery and suggest that the inhibition of neutrophil apoptosis in the postoperative period is, at least in part, a result of soluble circulating factors. The marked imbalance favoring proinflammatory over anti-inflammatory cytokine release in the immediate postoperative period mediates the overwhelmingly antiapoptotic net capacity of postsurgery plasma.