Does residual microscopic disease after chemoradiotherapy for locally advanced rectal cancer translate into a good clinical outcome?

AIM: This study aimed to assess the progression-free and overall survival of patients with residual microscopic disease following neoadjuvant chemoradiotherapy and rectal resection for locally advanced rectal cancer. METHOD: Two-hundred and thirty-four consecutive rectal cancer patients who had neoadjuvant chemoradiotherapy followed by radical resection (from May 2000 to April 2012) were divided according to pathological tumour response: residual microscopic disease (MIC), complete response (pCR) and partial/no response (non-CR). Data on the neoadjuvant regime, treatment-to-surgery interval, final pathology, type of operation, operative time, postoperative complications, length of hospital stay, disease recurrence and mortality were compared between the groups. RESULTS: There were 13 (5.5%) MIC patients, 48 (20.5%) with pCR and 173 (73.9%) with non-CR group. The groups were demographically comparable. MIC patients had more retrieved lymph nodes compared with the non-CR and pCR patients (median 13 compared with 8 and 10, respectively, P = 0.0086). The 5-year overall survival rates were 93.4% for the pCR and MIC patients vs 82.1% for the non-CR patients (P = 0.0324). The 5-year progression-free survival was 85.2% for the pCR and MIC patients vs 73.8% for the non-CR patients (P = 0.086). CONCLUSION: We have identified and assessed a new pathological subgroup of rectal cancer patients who had residual microscopic disease after neoadjuvant therapy. The survival analysis aligned them closely with pCR patients.

Number of evaluated lymph nodes and positive lymph nodes, lymph node ratio, and log odds evaluation in early-stage pancreatic ductal adenocarcinoma: numerology or valid indicators of patient outcome?

BACKGROUND: We evaluated the prognostic significance and universal validity of the total number of evaluated lymph nodes (ELN), number of positive lymph nodes (PLN), lymph node ratio (LNR), and log odds of positive lymph nodes (LODDS) in a relatively large and homogenous cohort of surgically treated pancreatic ductal adenocarcinoma (PDAC) patients. METHODS: Prospectively accrued data were retrospectively analyzed for 282 PDAC patients who had pancreaticoduodenectomy (PD) at our institution. Long-term survival was analyzed according to the ELN, PLN, LNR, and LODDS. RESULTS: Of these patients, 168 patients (59.5 %) had LN metastasis (N1). Mean ELN and PLN were 13.5 and 1.6, respectively. LN positivity correlated with a greater number of evaluated lymph nodes; positive lymph nodes were identified in 61.4 % of the patients with ELN ≥ 13 compared with 44.9 % of the patients with ELN < 13 (p = 0.014). Median overall survival (OS) and 5-year OS rate were higher in N0 than in N1 patients, 22.4 vs. 18.7 months and 35 vs. 11 %, respectively (p = 0.008). Mean LNR was 0.12; 91 patients (54.1 %) had LNR < 0.3. Among the N1 patients, median OS was comparable in those with LNR ≥ 0.3 vs. LNR < 0.3 (16.7 vs. 14.1 months, p = 0.950). Neither LODDS nor various ELN and PLN cutoff values provided more discriminative information within the group of N1 patients. CONCLUSIONS: Our data confirms that lymph node positivity strongly reflects PDAC biology and thus patient outcome. While a higher number of evaluated lymph nodes may provide a more accurate nodal staging, it does not have any prognostic value among N1 patients. Similarly, PLN, LNR, and LODDS had limited prognostic relevance.

Clinical recurrence and re-resection rates after extensive vs. segmental colectomy in Crohn's colitis: a retrospective cohort study.

BACKGROUND: The aim of the present study was to document long-term clinical recurrence and re-resection rates of segmental and extended colectomy in patients with Crohn's colitis and to identify risk factors causing recurrence. METHODS: Records of patients with isolated colonic Crohn's disease who underwent colectomy between 1995 and 2013 and were followed at our medical center were identified. Data on age at diagnosis, gender, smoking, disease location at diagnosis, perianal and rectal disease, indication for surgery, preoperative disease duration, type of operation, primary anastomosis at first operation, length of resected specimen, recurrence of symptoms, postoperative medication, reoperation, and total follow-up time were retrieved. RESULTS: Thirty-five suitable patients (18 segmental colectomy, 17 extensive colectomy; 17 males; mean age at operation 36.6 years) were identified. Mean age at primary operation was 36 years. The mean preoperative disease duration was 121 months. Postoperative medical treatment was needed in 10 (56 %) patients undergoing segmental colectomy and in 16 (94 %) of those undergoing extensive colectomy (p = 0.01). There was longer reoperation-free survival in the segmental colectomy patient group (p = 0.02) and also a trend toward longer symptom-free survival compared to the extensive colectomy patient group (p = 0.105). There was no correlation between the length of resected bowel and recurrence. Patients operated on at a younger age did not have a higher rate of recurrence of symptoms. Shorter disease duration, smoking, and male gender were risk factors for clinical recurrence. CONCLUSIONS: Segmental resection with primary anastomosis can be safely performed in patients with limited Crohn's colitis with reasonable clinical recurrence rates.

Restorative proctocolectomy impairs fertility and pregnancy outcomes in women with ulcerative colitis.

AIM: The effect of restorative proctocolectomy (RPC) on fertility and pregnancy in women with ulcerative colitis (UC) was evaluated. METHOD: Post-RPC female patients with UC who were attempting to become pregnant filled out questionnaires on fertility and pregnancy. Demographic and pouch data of pregnancies ending with delivery were collected from a prospective database. RESULTS: Forty-one women, 44 ± 10 years of age, completed the questionnaires. The median follow-up period post-RPC was 167 (range, 20-352) months. Before RPC, 26 women had 70 pregnancies and 62 deliveries. After RPC, 17 women had 32 pregnancies and 26 deliveries (P = 0.0035). Post-RPC, 10 (37%) of 27 patients failed to conceive compared with 26/26 successful attempts before RPC (P = 0.0006). The number of offspring per patient was 2.38 ± 1.27 before, and 0.68 ± 0.93 after, RPC (P < 0.0001). A higher number of spontaneous pregnancies occurred before (56/62; 90%) than after (15/25; 60%) RPC (P = 0.0004). The time to conception was longer (5.0 ± 11.6 vs 16.3 ± 25.1 months; P = 0.039) and there were more in-vitro fertilization procedures (three vs six) post-RPC. The gestation period was similar, but after RPC more deliveries were by Caesarean section (12.9% vs 46.2%; P = 0.0007). Babies born before RPC weighed more than those born after RPC (3.16 ± 0.61 kg vs 2.79 ± 0.68 kg, respectively; P = 0.0327). CONCLUSION: RPC is associated with an increased risk of infertility, similar duration of gestation and lower birthweight. Female candidates for RPC who have not finished family planning should be counselled accordingly.

Risk factors for chronic pouchitis after ileal pouch-anal anastomosis: a prospective cohort study.

AIM: The association between various demographic, clinical and pathological parameters and the evolution of chronic pouchitis was evaluated. METHOD: All ulcerative colitis patients who underwent ileal pouch anal anastomosis (1981-2009) were followed prospectively in a comprehensive pouch clinic. We examined risk factors including the presence of appendiceal inflammation and backwash ileitis in the colonic specimen, gender, ethnicity, age at disease onset, disease duration, extent of colitis, presence of extraintestinal manifestations (e.g. primary sclerosing cholangitis), family history of inflammatory bowel disease, indication for surgery, medical treatment, age at operation, staged procedure, diverting ileostomy and length of follow-up. Univariate analysis was performed on all risk factors followed by logistic regression analysis. RESULTS: The 201 enrolled patients (106 women, age at surgery 35 ± 15 years) were followed for a mean of 108 months. One hundred and thirty-eight (69%) had either a normal pouch or episodes of acute pouchitis and 63 (31%) developed chronic pouchitis. On univariate analysis the presence of an ileostomy (P = 0.017), pancolitis (P = 0.008), shorter disease duration (P = 0.04) and longer follow-up (P = 0.01) were identified as risk factors for chronic pouchitis. Multivariate analysis showed that patients with pancolitis (OR 3.26, 95% CI 1.20-8.85) and longer follow-up (OR 1.09, 95% CI 1.01-1.18) were more likely to develop chronic pouchitis. There was also an association to disease duration but this did not reach a level of significance. CONCLUSIONS: Pancolitis and longer follow-up are directly related to the development of chronic pouchitis.

Colorectal carcinoma in inflammatory bowel disease: a comparison between Crohn's and ulcerative colitis.

AIM: The study assessed the clinicopathological features and survival rates of inflammatory bowel disease (IBD) patients with colorectal carcinoma (CRC), which accounts for ∼ 15% of all IBD associated death. METHOD: The medical records of patients operated on for CRC in three institutions between 1992 and 2009 were reviewed, and those with Crohn's colitis (CC) and ulcerative colitis (UC) were identified. Data on age, gender, disease duration, colitis severity, surgical procedure, tumour stage and survival were retrieved. RESULTS: Fifty-three patients (40 UC and 13 CC, 27 men, mean age at operation 54 years) were found. All parameters were comparable between the groups. Mean disease duration before CRC was 22.7 years for UC and 16.6 years for CC patients (P = 0.04). CRC was diagnosed preoperatively in 43 (81%) patients. Twenty-eight patients had colon cancer, 23 had rectal cancer and two patients had more than one cancer. All malignancies were located in segments with colitis. Over one-half were diagnosed at an advanced stage (36% stage III; 17% stage IV). At a mean follow up of 56 ± 65 months, 60% were alive (54% disease free) and 40% were dead from cancer-related causes. The 5-year survival rate was 61% for the UC and 37% for the CC patients (P = NS). CONCLUSION: CRC in IBD patients is frequently diagnosed at an advanced stage, a factor that contributes to poor prognosis. The risk of CRC in CC patients is comparable to those with UC. Long-term surveillance is recommended for patients with long-standing CC and UC.

Long-term outcome of loose seton for complex anal fistula: a two-centre study of patients with and without Crohn's disease.

OBJECTIVE: Complex anal fistulas traverse a significant portion of the external sphincter muscle, making their treatment a surgical challenge. Several surgical options are used with conflicting results. The aim of this study was to analyse the results of permanent loose seton in the management of high anal fistulas in Crohn's disease (CD) patients and two-stage seton fistulotomy in patients without CD. METHOD: We retrospectively reviewed the clinical records of 77 patients with complex anal fistula treated by loose seton over a 4-year period, in two medical centres. Recorded parameters included demographics, medical history, type of fistula, disease duration, previous surgery, morbidity, recurrence and mortality. RESULTS: Sixty patients without CD underwent 107 fistula-related surgical procedures, and 17 CD patients underwent 29 procedures. Early postoperative complications were recorded in eight (10%) patients. Perioperative complications, mainly local sepsis or bleeding, were recorded in eight (10%) patients. Long-term complications were observed in nine non-CD and four CD patients. During a median follow-up period of 24 months, the recurrence rate was 40% in CD patients and 47% in patients without CD. Five patients (four non-CD patients and one CD patient) developed some degree of faecal incontinence. CONCLUSION: The fistula recurrence rate following two-stage seton fistulotomy in non-CD patients was high. In CD patients the use of permanent loose seton is effective in controlling local sepsis in about half of patients and has low rates of subsequent incontinence.

Timing of colostomy reversal following Hartmann's procedure for perforated diverticulitis.

AIM: Hartmann's procedure is the surgical treatment of choice for perforated acute diverticulitis. Hartmann's reversal (HR) that is performed at a later stage may be challenging. The optimal timing for HR is still a subject for controversy. The aim of this study is to assess whether the timing of HR affects surgical outcome. PATIENTS AND METHODS: A retrospective-cohort multi-center study was conducted, including all patients who underwent HR for acute diverticulitis from January 2004 to June 2015 in 5 medical centers. Patient data included demographics, surgical data and post-operative outcome. RESULTS: One hundred and twenty-two patients were included in the database. Median time from Hartmann's procedure to reversal was 182.7 days, with the majority of patients (76 patients, 62.2%) operated 60 to 180 days from the Hartmann's procedure. Fifty-seven patients (46.7%) had post-operative complications, most commonly wound infections (27 patients, 22.1%). Receiver operating characteristic (ROC) curve and a propensity score match analysis (P=0.43) correlating between days to HR from the index procedure showed no specific cut-off point regarding post-operative complications (P=0.16), Major (Clavien-Dindo score of 3 or more) complications (P=0.19), Minor (Clavien Dindo 1-2) and no complications (P=0.14). Median length of stay was 10.9 days (range 3-90) and Pearson correlation failed to demonstrate a correlation between timing of surgical intervention and length of stay (P=0.4). CONCLUSION: Hartmann's Reversal is a complex surgical procedure associated with high rates of complications. In our series, timing of surgery did not affect surgical complications rate or severity or the length of hospital stay.

Is stapled ileal pouch anal anastomosis a safe option in ulcerative colitis patients with dysplasia or cancer?

PURPOSE: The purpose of this study was to investigate the oncological and clinical outcome of ulcerative colitis (UC) patients with coexisting colorectal cancer/dysplasia following stapled ileal pouch-anal anastomosis (IPAA). MATERIALS AND METHODS: One hundred eighty-five UC patients who underwent stapled IPAA were followed prospectively in a comprehensive pouch clinic. They were divided into three groups: colorectal cancer, dysplasia, and no cancer/dysplasia. Demographic parameters, clinical data, and oncological and functional outcome of the three groups were compared. RESULTS: Sixteen patients had cancer and 14 had dysplasia. Two of the three cancer patients who developed metastatic disease died. One patient who had rectal cancer was found to have cancer cells in the rectal cuff 10 years after IPAA. All other cancer/dysplasia patients were disease-free at 62 months (median). The 5-year survival rate was 87.5% for the cancer group and 100% for the others (p < 0.0001). Chemotherapy (nine patients) did not affect pouch function. Two rectal cancer patients who received radiotherapy did not maintain a functioning pouch. Overall pouch failure rates were 19%, 7%, and 6% for cancer, dysplasia, and no-cancer/dysplasia patients, respectively (p = 0.13). The mean frequency of bowel movements in 24 h was similar between the groups. CONCLUSIONS: Stapled IPAA is a reasonable option for UC patients with cancer/dysplasia. Chemotherapy is safe, but the effect of radiation on pouch outcome is worrisome. Close long-term follow-up for UC patients with cancer/dysplasia is recommended for early detection of possible recurrence.

Solid pseudopapillary neoplasm of the pancreas: Management and long-term outcome.

BACKGROUND: Solid pseudopapillary neoplasm (SPN) of pancreas is a rare pancreatic neoplasm with a low metastatic potential. Our aim was to study the clinical-pathological characteristics, and long-term outcome of this tumor. MATERIALS: Rretrospective single center study of patients operated for SPN of pancreas. Clinical and pathological data were collected. RESULTS: From 1995 to 2016, 1320 patients underwent pancreatic resection. SPN was confirmed in 32 cases (2.46%), including 29 (90.6%) female and three (9.4%) male, with a mean age of 28.4 ± 12.2 years. SPN was the most common pathology among female patients under age of 40 (72.4%). Abdominal pain was the most frequent presenting symptom (48%), whereas none of the patients presented with jaundice. Mean tumor diameter was 5.9 cm (range, 0.9-14 cm). All patients underwent margin-negative surgical resection. Two patients demonstrated gross malignant features, including liver metastases at presentation (n = 1), and adjacent organ and vascular invasion (n = 1). Microscopic malignant features were present in thirteen patients (40.6%). Recurrence occurred in the retroperitoneal lymph nodes (n = 1, 7 years post resection) and in the liver (n = 2, 1 and 5 years post resection). Mean follow-up was 49.2 months (range, 1-228 months). Five and 10-year disease-free survival was 96.5% and 89.6% respectively. CONCLUSIONS: SPNs are low-grade tumors with a good prognosis. Margin-negative surgical resection is curative in most patients. However, almost 15% of patients demonstrate malignant features including invasion of adjacent organs or metastatic disease. Patients with malignant disease are still expected to have long survival, and aggressive surgical approach is advocated.

Role of thromboxane in interleukin 2-induced lung injury in sheep.

Interleukin (IL)-2 administration leads to respiratory dysfunction due to increased vascular permeability. This study examines the role of thromboxane (Tx)A2 in IL-2 induced lung injury in sheep with chronic lung lymph fistulae. This preparation enables evaluation of permeability prior to the development of gross edema. IL-2, 10(5) units/kg (n = 6), or its excipient control (n = 5) was given as an i.v. bolus over 2 min. After 2 h of IL-2 administration, plasma TxB2 increased from 168 to 388 pg/ml (P less than 0.05) and lung lymph TxB2 from 235 to 694 pg/ml (P less than 0.05). Mean pulmonary artery pressure (MPAP) rose from 13 to 29 mm of Hg (P less than 0.05) at 30 min and remained elevated for 4 h while the pulmonary artery wedge pressure was unchanged at 4 mm of Hg. Arterial oxygen tension (PaO2) fell from 88 to 77 mm of Hg (P less than 0.05). Lung lymph flow (QL) rose from 2.2 to 3.8 ml/30 min (P less than 0.05) at 1 h and to 6.4 ml/30 min at 3 h. This rise coincided with an increase in the lymph/plasma (L/P) protein ratio from 0.67 to 0.77 (P less than 0.05). In contrast, the non-IL-2-infused sheep (n = 3) recruitment of the lung vasculature by left atrial balloon inflation led to a rise in QL from 2.4 to 8.2 ml/30 min, whereas the L/P ratio declined from 0.62 to 0.25, suggesting that the protein-rich lymph flow after IL-2 administration reflected increased microvascular permeability. In further proof of an increase in permeability, IL-2 administration into sheep (n = 2) with an inflated left atrial balloon led, after a pressure-independent L/P protein ratio had been achieved, to an increase in L/P protein ratio and decrease in protein reflection coefficient. At 2 h after IL-2, the blood leukocyte count fell from 8156 to 4375/mm3 (P less than 0.05) primarily due to a 73% drop in lymphocytes. The platelet count declined from 292 to 184 x 10(3)/mm3 (P less than 0.05). Body temperature rose from 38.9-40.3 degrees C (P less than 0.05), and shaking chills were common. Pretreatment with the Tx synthetase inhibitor OKY 046 (n = 7) lowered baseline plasma and lymph TxB2 levels to 22 and 52 pg/ml (P less than 0.05) and prevented the IL-2-induced increase in plasma and lung lymph TxB2 (P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Laparoscopic versus open liver resection for metastatic colorectal cancer.

BACKGROUND: Application of minimally invasive surgery for oncologic liver resection is still limited to expert centers. We describe our experience in laparoscopic liver resection (LLR) for colorectal liver metastases (CLM). PATIENTS AND METHODS: Between February 2010 and February 2015, 174 patients underwent resection of CLM. LLR was chosen according to surgeon's preferences. Data was retrieved from the institutes' electronic charts and retrospectively analyzed. RESULTS: LLR was performed in 42 patients (24.5%) and OLR in 132. Increased number of metastases were found in OLR (2.82 ± 2.81 versus 1.78 ± 1.16, P = 0.02), with no difference in maximal lesion size (33.1 ± 22 versus 34.9 ± 27.5 cm, P = 0.7). Altogether 55 patients underwent major hepatectomy, and 50 of the OLR group (37.8%, 37 right hepatectomy and 7 left hepatectomy) (P = 0.02). In 5 patients (11.6%) a conversion to open surgery was indicated. Operative time was longer in LLR. Estimated blood loss was decreased in laparoscopic minor resections. One OLR patient died during the postoperative period (0.7%). Eight patients in the OLR group had major complications, versus 1 in the LLR group (P = 0.0016). Reoperation within 30 days was performed in 4 OLR patients and none in the LLR group. Patients in the LLR group had shorter length of stay (LOS) (6.78 ± 2.75 versus 8.39 ± 5.64 days, P = 0.038). R0 resection was 88% in both groups. CONCLUSIONS: In selected patients with CLM, LLR is feasible, safe and may achieve shorter LOS without inferior oncologic outcome.

Isolation limb perfusion with tumor necrosis factor alpha and chemotherapy for advanced extremity soft tissue sarcomas.

The unique property of high dose recombinant tumor necrosis factor alpha (rTNF alpha) is to activate and selectively destroy the tumor-associated microvasculature. For the systemic application of rTNF alpha it has been shown that the maximum tolerated dose (MTD) is 10 times less than the effective dose in animals. The main toxicity corresponds to systemic inflammatory response syndrome with a decrease in vascular resistance and hypotension. We found that it is possible to administer rTNF alpha at 10 times the MTD in an isolated limb perfusion (ILP) system with heart-lung machine, for locally advanced extremity soft tissue sarcomas. One hundred forty patients received an ILP with high-dose TNF alpha. In 55 patients treated with the combination of high-dose rTNF alpha + interferon-gamma + melphalan an overall objective response rate of 87% with 36% complete responses was observed; it was 81% and 28%, respectively, in a group treated with TNF alpha and melphalan (n = 85). Angiographic and immunohistological studies showed the selective and early damage of the sarcoma-associated microvasculature preceded by the upregulation of adhesion molecules and intratumoral leak of von Willebrand factor. Tumor invasion by platelets and, in some cases, by polymorphonuclear cells, appeared within hours after the application of rTNFa long before the lysis of the tumor. Thus, ILP with high-dose TNF alpha and chemotherapy seems to act through a dual targeting: TNF hits the tumor associated vasculature, and chemotherapy attacks the tumor cells. Therefore, ILP with TNF is a new option in the management of locally advanced soft tissue sarcoma of the extremities.

Cumulative damaging effect of liver hypoperfusion and cyclosporine a on the peribiliary capillary plexus: a study in an isolated dually perfused rat model.

BACKGROUND: Cyclosporine (CsA) is an essential posttransplantation immunosuppressive drug. It may cause hepatotoxicity, mostly cholestasis, by unknown mechanism. CsA causes nephrotoxicity mainly by increased vascular resistance. We investigated the effects of CsA on the peribiliary capillary plexus, in an isolated, dually perfused (i.e., via the hepatic artery and the portal vein) rat liver preparation. METHODS: After 30 min of stabilization with optimal flow (4 ml/min/g liver), four liver groups were perfused (control, n=5 each) and four groups were hypoperfused (n=5 each, 1 ml/min/g) for 120 min. This was followed by a 30-min optimal reperfusion phase, during which the controls and the hypoperfused groups were injected (60 sec) via the hepatic artery with CsA at high (3 mg/kg body weight in 1 ml) or low dose (0.03 mg/kg), cremophore (130 mg/kg), or saline (1 ml). A ninth group (n=5) underwent 2-hr ischemia and 30-min reperfusion to standardize liver damage. Dark nonradioactive microspheres (approximately 10 microm diameter) were injected via the hepatic artery 15 min after drug or saline injection. RESULTS: Neither of the two CsA doses, nor cremophore controls, nor hypoperfusion alone caused entrapment of microspheres in the peribiliary circulation as assessed by light microscopy; perfusion pressures and resistances were also not altered. Significant arteriolar impaction and vasculature engorgement occurred in the hypoperfused plus high-dose CsA livers; hypoperfusion plus low-dose CsA or cremophore groups were minimally tainted. Vascular notable obstruction was associated with 15-40% increase in portal and arterial perfusion pressures and resistances, 50% decrease in oxygen extraction, and increase in lactate/pyruvate ratio, hepatocellular damage, and wet-to-dry weight ratio. Such findings were superior to those detected in the ischemic livers. CONCLUSIONS: Acute single high-dose CsA injection, but not low-dose or cremophore, if combined with decreased flow, alters hepatic microcirculatory resistance. Possible correlations between such changes and clinical implications in organ transplantation are discussed.

Crohn's disease isolated to the appendix: truths and fallacies.

Twenty-five cases of Crohn's disease confined to the appendix were reported in eight hospitals in Israel during a 15-year period. Review of the histologic slides confirmed the diagnosis in 22 cases. Re-evaluation of these 22 patients included physical examination and radiologic studies of the small and large bowel. Rectosigmoidoscopy was performed in 16 patients. Signs and symptoms of Crohn's disease at other sites in the gastrointestinal tract did not occur during follow-up periods of two to 15 years (mean, 6.4 years) after appendectomy. This study and a review of the literature indicate that in most cases (93 per cent) Crohn's disease initially limited to the appendix is not a predictor of subsequent involvement of another portion of the bowel. It is concluded that the so-called Crohn's disease isolated to the appendix is a form of chronic granulomatous and follicular appendicitis of unknown etiology that is unrelated nosologically in the majority of the cases to Crohn's disease proper.

Oxygen free radicals mediate ischemia-induced lung injury.

Lower torso ischemia leads during reperfusion to leukocyte (white blood cell)-dependent lung injury. This study tests the intermediary role of oxygen free radicals (OFRs) in mediating this event. Chronically instrumented anesthetized sheep underwent 2 hours of bilateral hindlimb ischemia. In untreated control animals (n = 7), 1 minute after tourniquet release, mean pulmonary artery pressure rose from 13 to 38 mm Hg (p less than 0.05), whereas pulmonary artery wedge pressure was unchanged from 4 mm Hg. The pulmonary hypertension was temporally related to an increase in plasma thromboxane (Tx) B2 levels from 211 to 735 pg/ml (p less than 0.05). At 30 minutes of reperfusion lung-lymph TxB2 levels rose from 400 to 1005 pg/ml (p less than 0.05). This coincided with an increase in lung-lymph flow from 4.3 to 8.3 ml/30 min (p less than 0.05), which remained elevated for 2 hours, an unchanged lymph/plasma protein ratio, and a rise in lymph protein clearance from 2.6 to 4.6 ml/30 min (p less than 0.05). These changes are consistent with increased lung microvascular permeability. White blood cell count fell during the first hour of reperfusion from 6853 to 3793/mm3 (p less than 0.05), and lung histologic findings showed marked leukosequestration relative to sham animals (n = 3). Pretreatment with the OFR scavengers, superoxide dismutase and catalase both conjugated to polyethylene glycol (n = 6) blunted the rise in mean pulmonary artery pressure to 19 mm Hg (P less than 0.05) and prevented the increase in plasma and lymph TxB2 lymph flow, and lymph protein clearance (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Oxygen free radicals are required for ischemia-induced leukotriene B4 synthesis and diapedesis.

Hind limb ischemia and reperfusion have been shown to result in high plasma levels of leukotriene B4 (LTB4) and polymorphonuclear neutrophil (PMN) sequestration in the pulmonary microvasculature. This study tests whether LTB4 is derived from PMNs and its role in mediating ischemic plasma-induced diapedesis. Plasma derived from rabbit hind limbs after 3 hours of tourniquet ischemia and 10 minutes of reperfusion (n = 6) showed an increased LTB4 level of 560 pg/ml, higher than sham plasma values of 106 pg/ml (p less than 0.05). Introduction of ischemic plasma in abraded skin chambers placed on the dorsum of normal rabbits (n = 6) led after 3 hours to PMN diapedesis of 1175 PMN/mm3, associated with a further increase in LTB4 levels to 820 pg/ml (both p less than 0.05). In contrast, ischemic plasma derived from neutropenic animals (n = 4; nitrogen mustard, 2 mg/kg; PMNs less than 30/mm3) contained lower levels of LTB4, 160 pg/ml (p less than 0.05). When introduced in skin chambers in normal rabbits (n = 4), this plasma induced accumulations of only 163 PMN/mm3, accompanied by a smaller increase in LTB4 levels in the blister fluid after 3 hours, 397 pg/ml (both p less than 0.05). A correlation was found between LTB4 levels in ischemic plasma and PMN accumulations in blister fluid (r = 0.92; p less than 0.05). Intravenous pretreatment of rabbits (n = 4) used in the blister chamber bioassay with the LT receptor antagonist FPL-55712, 40 micrograms/kg/hr, attenuated diapedesis induced by ischemic and ischemic-neutropenic plasma, 103 and 35 PMN/mm3, respectively (both p less than 0.05). Pretreatment with superoxide dismutase, 1500 units/kg, and catalase, 5000 units/kg, both conjugated to polyethylene glycol (n = 4), prevented ischemic plasma-induced LTB4 synthesis, as well as ischemic plasma-induced diapedesis, 12 PMN/mm3 (p less than 0.05). Finally, pretreatment with allopurinol, 25 mg/kg, was similarly effective in preventing LTB4 synthesis and PMN migration. These data suggest that oxygen free radicals are essential for ischemia-induced PMN synthesis of LTB4 that in turn mediates their diapedesis.

Thromboxane mediates the ischemia-induced neutrophil oxidative burst.

Indirect evidence exists that the reperfusion of ischemic tissue activates white blood cells. Thus local and systemic reperfusion injuries are prevented by making animals leukopenic or by inhibiting white blood cell lung entrapment by blocking thromboxane A2 generation. This study tests directly whether ischemia and reperfusion activates neutrophils, as measured by their oxidative burst, and whether thromboxane mediates this event. Anesthetized rats underwent 4 hours of bilateral hind limb tourniquet ischemia followed by 60 minutes of reperfusion. Plasma thromboxane B2 levels increased to 2750 pg/ml at 5 minutes of reperfusion, higher than the sham control (n = 36) value of 370 pg/ml (p less than 0.01). In untreated ischemic animals (n = 30) the intracellular H2O2 production of circulating neutrophils, as assayed flow cytometrically by dichlorofluorescein oxidation, increased from a preischemic value of 133 to a peak of 251 femtomoles dichlorofluorescein/neutrophil at 5 minutes of reperfusion (p less than 0.01). Treatment of neutrophils with phorbol myristate acetate (PMA) 10(-7) mol/L led to a 91% increase in neutrophil H2O2 production before ischemia, and 5 minutes after reperfusion there was an enhanced response to PMA of 222% (p less than 0.01). Pretreatment of animals with the thromboxane-synthetase inhibitor OKY 046 (n = 36) prevented ischemia-induced thromboxane generation, neutrophil H2O2 production (p less than 0.05), as well as the enhanced response to PMA stimulation (p less than 0.05). Treatment with the thromboxane-receptor antagonist SQ 29,548 (n = 36) did not affect the increase in plasma thromboxane levels after ischemia but was as effective as OKY 046 in preventing the ischemia-induced increase in neutrophil H2O2 production and the enhanced response to PMA stimulation. These data indicate that lower-torso ischemia leads to neutrophil activation, manifest by H2O2 production, an event mediated by thromboxane.

Ischemia-induced neutrophil activation and diapedesis is lipoxygenase dependent.

Ischemia and reperfusion lead to eicosanoid- and neutrophil (PMN)-dependent injury. This study tests the role of ischemia-induced lipoxygenase activity in mediating PMN activation and diapedesis. Anesthetized rabbits (n = 8) underwent 3 hours of bilateral hindlimb ischemia. At 10 minutes of reperfusion, leukotriene B4 (LTB4) levels in femoral venous effluent were 0.49 +/- 0.05 ng/ml compared with 0.04 +/- 0.07 ng/ml in sham-treated animals (n = 10) (p less than 0.05). Intracellular H2O2 production of circulating PMNs assayed flow cytometrically by dichlorofluorescein (DCF) oxidation, increased from a preischemic value of 74 +/- 14 femtomoles DCF/cell to 135 +/- 8 fmol DCF/cell (p less than 0.05). PMNs were treated with phorbol myristate acetate (PMA), 10(-7) mol/L. In contrast to a 162% increase in H2O2 production before ischemia, PMNs at 10 minutes of reperfusion had an enhanced response to PMA of 336% (p less than 0.05). Addition of authentic LTB4 (0.5 ng/ml) to PMN from sham-treated animals led to their activation, manifest by an oxidative burst, 127 +/- 12 fmol DCF/cell, and an enhanced response of 337% to PMA stimulation. To study diapedesis, plasma collected at 10 minutes of reperfusion was introduced into plastic chambers taped atop skin abrasions in rabbits (n = 8). After 3 hours, 1610 +/- 246 PMN/mm3 accumulated and LTB4 levels in blister fluid were 0.83 +/- 0.03 ng/ml, higher than values of 44 +/- 23 PMN/mm3 (p less than 0.05) and 0.04 +/- 0.03 ng LTB4/ml (p less than 0.05) with saline solution and 68 +/- 16 PMN/mm3 (p less than 0.05) and 0.19 +/- 0.02 ng/ml (p less than 0.05) with nonischemic plasma. The introduction of LTB4, 3.3 ng/ml, into the chambers resulted in an accumulation of 536 +/- 352 PMN/mm3 (p less than 0.05). Pretreatment of animals before hindlimb ischemia (n = 5) with the lipoxygenase inhibitor diethylcarbamazine abolished PMN activation (51 +/- 12 fmol DCF/cell) and ischemic plasma-induced diapedesis into the plastic chamber (38 +/- 18 PMN/mm3). Pretreatment of nonischemic animals (n = 13) used for the dermabrasion bioassay with diethylcarbamazine abolished diapedesis into the plastic chambers induced by ischemic plasma (n = 5) (32 +/- 24 PMN/mm3) or LTB4 (n = 3) (36 +/- 28 PMN/mm3). These data indicate that PMN activation after reperfusion of ischemic tissue is mediated by a lipoxygenase product, perhaps LTB4, and that both reperfusion plasma and authentic LTB4 induce diapedesis by stimulating de novo lipoxygenase activity.

Modulation of pulmonary permeability in vivo with agents that affect the cytoskeleton.

In vitro studies show that the cytoskeleton of the microvascular barrier moderates polymorphonuclear leukocyte (PMN) diapedesis and the transport of macromolecules. This in vivo study tests indirectly whether the cytoskeleton of the pulmonary microvasculature responds similarly to agents known to reorganize the cytoskeleton to alter diapedesis and permeability in vitro. One of four agents, saline solution, cytochalasin B (which promotes actin microfilament disassembly), leukotriene (LT) B4 (PMN chemoattractant), or phalloidin (which promotes and stabilizes F-actin polymerization) was introduced into the bronchus of the anterior segment of the left lung of anesthetized rats (n = 152) through a tracheostomy and fine-bore cannula. Twenty minutes later, saline solution, cytochalasin B, LTB4, or phalloidin was similarly introduced. PMN accumulations (x 10(4) cells/ml), protein concentration in bronchoalveolar lavage fluid, and lung wet/dry weight ratios were measured 3 hours later. When the initial and secondary treatments were saline solution, PMN accumulations were 3 +/- 1 cells/ml and the protein level was 274 +/- 48 micrograms/ml. Secondary treatment of the saline-treated group with cytochalasin B or LTB4 led to increases in PMN to 18 +/- 2 and 9 +/- 2 cells/ml and protein to 960 +/- 50 and 840 +/- 40 micrograms/ml (p less than 0.05); secondary treatment with phalloidin was similar to that with saline solution. With saline solution used for both treatments, the wet/dry ratio was 3.4 +/- 0.2. Primary saline solution and secondary treatments with either cytochalasin B or LTB4 led to a similar increase in wet/dry ratios to 3.9 +/- 0.1 (p less than 0.05), whereas phalloidin was without effect (3.5 +/- 0.3). Initial cytochalasin B treatment followed by LTB4 led to increased PMN diapedesis (43 +/- 6 cells/ml and wet/dry ratio 4.3 +/- 0.2) (p less than 0.05). Secondary phalloidin treatment attenuated the cytochalasin B effect with counts of 12 +/- 2 PMN/ml, protein levels of 460 +/- 30 micrograms/ml, and a lower wet/dry ratio of 3.7 +/- 0.1 (p less than 0.05). Even more striking, phalloidin as initial treatment further reduced the cytochalasin B effect to 7 +/- 1 PMN/ml, whereas protein level was 490 +/- 60 micrograms/ml and wet/dry ratio was 3.5 +/- 0.1 (p less than 0.05). Further, phalloidin, given initially, attenuated the effect of secondary treatment with LTB4, resulting in fewer cells (4 +/- 2 PMN/ml), a lower wet/dry ratio (3.4 +/- 0.1), and protein level of 650 +/- 20 micrograms/ml (p less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)