Outcomes of gracilis muscle interposition for rectourethral fistulas caused by treatment of prostate cancer.

BACKGROUND: Gracilis muscle interposition (GMI) has been associated with favorable outcomes in treating complex perianal fistulas. Outcomes of GMI may vary according to the fistula etiology, particularly between rectovaginal fistulas in women and rectourethral fistulas (RUF) in men. The aim of this study was to assess the outcome of GMI to treat RUF acquired after prostate cancer treatment. METHODS: This retrospective cohort study included male patients treated with GMI for RUF acquired after prostate cancer treatment between January 2000 and December 2018 in the Department of Colorectal Surgery, Cleveland Clinic Florida. The primary outcome was the success of GMI, defined as complete healing of RUF without recurrence. Secondary outcomes were length of hospital stay and postoperative complications. RESULTS: This study included 53 male patients with a median age of 68 (range, 46-85) years. Patients developed RUF after treatment of prostate cancer with radiation (52.8%), surgery (34%), or transurethral resection of the prostate (TURP) (13.2%). Median hospital stay was 5 (IQR, 4-7) days. Twenty (37.7%) patients experienced 25 complications, the most common being wound infection and dehiscence. Primary healing after GMI was achieved in 28 (52.8%) patients. Fifteen additional patients experienced successful healing of RUF after additional procedures, for a total success rate of 81.1%. Median time to complete healing was 8 (range, 4-56) weeks. The only significant factor associated with outcome of GMI was wound dehiscence (p = 0.008). CONCLUSIONS: Although the initial success rate of GMI was approximately 53%, it increased to 81% after additional procedures. Complications after GMI were mostly minor, with wound complications being the most common. Perianal wound dehiscence was significantly associated with failure of healing of RUF after GMI.

Use of Computerized Microtomography, Energy Dispersive Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy to Monitor Effects of Adding Calcium to Bleaching Gels.

OBJECTIVES: The aim of this study was to evaluate the mineral content, expressed by calcium (Ca) and phosphate (P), in dental enamel exposed to bleaching agents using micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). METHODS: Sixty bovine dental enamel specimens were randomly divided into three groups (n=20): HP35ca (bleached using 35% hydrogen peroxide with Ca); HP35wca (bleached using 35% hydrogen peroxide without Ca); and control (without bleaching). Five specimens from each group were used for SEM and EDS analyses, 10 specimens were used for AFM analysis, and the remaining five specimens were used for micro-CT analysis. The pH of the gels was measured using a pH meter. The EDS and micro-CT data were analyzed using one-way ANOVA and Pearson's correlation test. The AFM data were analyzed using one-way ANOVA (α=0.05). RESULTS: The weight percentages of Ca and P obtained using EDS were similar between the bleached and control groups. Small, superficial changes were observed by SEM in the HP35wca group. The HP35ca group showed similar patterns to the control group. AFM results showed no significant changes in the enamel roughness in any of the tested groups. No significant difference in the volume or depth of structural enamel loss was found between gels with and without Ca. No mineral loss was observed in the dentin substrate. The EDS and micro-CT analysis data exhibited a high correlation (p<0.001). CONCLUSION: The addition of Ca to the bleaching gel had no beneficial effect on the bleached tooth enamel in terms of composition, mineral loss, and surface roughness. Micro-CT results exhibited a high correlation with the EDS results.

Stress during slaughter increases lipid metabolites and decreases oxidative stability of farmed rainbow trout (Oncorhynchus mykiss) during frozen storage.

The consequences of slaughter on the formation of lipid metabolites and oxidative stability of fish muscle during long term frozen storage (-10 °C) were evaluated using farmed rainbow trout killed by asphyxia in air or percussion. The level of major adenine nucleotides and their related compounds was determined in order to check the stress level during slaughter. Plasma lipid metabolites were studied through the determination of eicosanoids and docosanoids such as prostaglandins, leukotrienes, thromboxanes, isoprostanes, resolvins, hydroxides, hydroperoxides, coming from eicosapentaenoic (EPA), arachidonic (ARA), and docosahexaenoic (DHA) acids. In addition, lipid oxidative stability of fillets was monitored. Results revealed that stress during slaughter can greatly influence oxidative stress and oxidative stability of rainbow trout fillets. In fact, asphyxia, which was the most stressful, induced a higher production of some lipid mediators such as hydroperoxides and EPA-derived prostaglandins, such as 12-HpHEPE/15-HpHEPE and PGD3/PGE3. As a consequence, fillets derived from asphyxiated fish were less stable in terms of oxidative stability and showed lower shelf-life.

Suboptimal results after sphincteroplasty: another hazard of obesity.

BACKGROUND: This study aimed to investigate the outcomes of sphincteroplasty in obese patients. METHODS: Patients with fecal incontinence (FI) who underwent sphincter repair were identified and divided into obese [body mass index (BMI) ≥ 30 kg/m(2)] and nonobese (BMI < 30 kg/m(2)) groups. Cleveland Clinic Florida FI Score (CCFFIS: 0 best and 20 worst) and FI quality of life (FIQoL) score (mean global FIQoL: 4.11 best and 1 worst) were recorded. Wilcoxon and Mann-Whitney U tests compared quantitative variables; Fisher's exact test was used for categorical variables. RESULTS: Seventy-nine patients (78 females; mean age: 57 ± 15 years) were divided into obese (n = 15) and nonobese (n = 64) groups and were similar in age, etiology, physiologic parameters, and preoperative CCFFIS. Median follow-up was 64 (13-138) months. There were 3 (25 %) and 11 (17 %) complications in the obese and nonobese groups, respectively (p = 0.68), the most common being wound infection. Mean CCFFIS decreased from 16.0 ± 3.9 to 11.5 ± 6.5 in the obese (p < 0.001) and 16.2 ± 3.4 to 8.4 ± 5.0 in the nonobese groups (p < 0.001). Postoperative CCFFIS correlated with FIQoL (Spearman's correlation coefficient = -0.738, p < 0.001). Nonobese patients had significantly higher CCFFIS improvement (48 vs. 28 % p = 0.04) and a superior mean global FIQoL score (2.19 ± 0.9 vs. 2.93 ± 0.8, p < 0.01). Four (29 %) obese and 11 (17 %) nonobese patients required further surgery after failed sphincteroplasty (p = 0.45). CONCLUSIONS: Risk of complications and need of further continence surgery were similar between obese and nonobese patients. However, obese patients experienced less improvement after sphincteroplasty.

Inter-observer and intra-observer variability in the diagnosis of dysplasia in patients with inflammatory bowel disease: correlation of pathological and endoscopic findings.

AIM: Colonic epithelial dysplasia is deemed the precursor lesion of cancer arising in inflammatory bowel disease (IBD). It has been suggested that many dysplastic lesions could be endoscopically detected to obtain target biopsies, leading to better yield. However, the clinical impact of a diagnosis of dysplasia may be hampered by a significant degree of histological and endoscopic intra-observer and inter-observer variability. This study aimed to evaluate intra-observer and inter-observer variability in the microscopic diagnosis of dysplasia in IBD and correlate endoscopic and histological findings. METHOD: In total, 158 cases of ulcerative colitis and 14 of Crohn's disease with dysplasia were selected from a pathology database. Slides were blindly reviewed twice by two expert gastrointestinal pathologists. Results of endoscopic examinations were extracted from the reports. The degree of intra-observer and inter-observer variability was determined by kappa statistics. RESULTS: Overall, there was an excellent degree of histopathological inter-observer agreement (κ = 0.786). The lowest level of agreement in the dysplasia group was for indefinite dysplasia (κ = 0.251). Negative and high grade dysplasia diagnosis reached the highest level of agreement with κ values of 0.822 [95% confidence interval (CI) 0.673-0.971] and 1.00 (95% CI 0.850-1.149), respectively. Intra-observer agreement was good and increased during the latter period of the study (κ = 0.734, 95% CI 0.642-0.826). Endoscopic-histological correlation was poor among the negative endoscopies, as up to 43% of cases were diagnosed with at least focal high grade dysplasia. The endoscopic-histological correlation improved when evaluating suspicious endoscopic lesions. CONCLUSION: Dysplasia is reliably diagnosed by expert gastrointestinal pathologists but has poor correlation with an endoscopic diagnosis of dysplasia.

Local excision of T1 and T2 rectal cancer: proceed with caution.

AIM: This study aimed to compare the clinical outcome between local excision (LE) and total mesorectal excision (TME) for early rectal cancer. METHOD: After Institutional Review Board approval, charts of patients with T1 or T2 N0M0 rectal adenocarcinoma treated by curative LE or TME without preoperative radiotherapy from 2004 to 2012 were reviewed. Categorical and continuous variables were compared using chi-square analysis and the ANOVA test. Kaplan-Meier analysis compared survival rates. RESULTS: The study included 153 patients: 79 underwent TME and 74 LE. Postoperative infection was more common after TME (P = 0.009). There was tumour involvement of the margins in 13.5% after LE compared with 0% after TME (P = 0.001). Of the patients treated initially by LE, 13.5% had additional surgery for unfavourable histological findings and 4.1% had residual tumour. Median follow up was 35 (17-96) months. No deaths were recorded in 56 patients with a pT1 lesion. There was no significant difference in local recurrence (P = 0.332) or 3-year disease-free survival (DFS; P = 0.232) between patients having LE or TME. The 68 patients with a T2 lesion had higher local recurrence (P = 0.025) and lower DFS following LE compared with TME (P = 0.044). There was no difference in overall survival (P = 0.351). CONCLUSION: LE of early rectal cancer is associated with higher local recurrence and decreased DFS. These disadvantages are significant for T2 lesions.

Are postoperative complications more common following colon and rectal surgery in patients with chronic kidney disease?

AIM: According to National Kidney Foundation guidelines, early stages of chronic kidney disease (CKD) can be detected through the estimated glomerular filtration rate (eGFR). We assessed complications following colorectal surgery (CRS) in patients with CKD Stages 3 and 4, as defined by the eGFR. METHOD: Patients with CKD were identified within our database. Patients with an eGFR of 15-59 ml/min (CKD Stages 3 and 4) formed the CKD group and were compared with American Society of Anesthesiology (ASA) score-matched controls with an eGFR of ≥ 60 ml/min. Assessments included demographics, comorbidity, ASA score, operative details and 30-day postoperative outcome. RESULTS: Seventy patients in the CKD group were matched with 70 controls. ASA scores and length of stay did not differ significantly between the groups. CKD patients were older (mean age 76.5 years vs 71.1 years; P < 0.001) and had a lower mean body mass index (24.3 vs 28.2; P < 0.001) compared with controls. Compared with the CKD group, the mean operation time was longer in the control group (181.5 min vs 151.6 min; P = 0.02) and the estimated blood loss was greater (232 ml vs 165 ml; P = 0.004). Postoperative infection was more common in the CKD group (60%vs 40%; P = 0.01). There were no significant differences in reoperation rates, 30-day readmissions or the incidence of acute renal failure (ARF). CONCLUSION: Patients with CKD Stages 3 and 4 had a higher incidence of postoperative infections than matched controls after colorectal surgery. ARF developed in 18.6% of patients. Preoperative optimization should include adequate hydration and assessment of potentially nephrotoxic substances for bowel preparation, preoperative antibiotics and pain control.

Prophylactic ureteric catheters in laparoscopic colorectal surgery.

BACKGROUND: The purpose of this study was to evaluate the use of ureteric catheter placement in laparoscopic colorectal surgery and to assess the morbidity related to this procedure. METHODS: Between 1994 and 2001, 313 elective laparoscopic colorectal surgeries were performed. Patients with and without ureteric catheters were retrospectively analyzed. RESULTS: Catheter placement was attempted in 149 patients (catheter group) and was not attempted in 164 (controls). There were no significant differences between groups in the number of patients with prior colorectal resection (p=0.286) or other abdominal surgery (p=0.074). Crohn's disease and diverticulitis were more common in the catheter group than among controls (p<0.001). Concomitant intra-abdominal fistula or abscess was present in 29 patients (19.5%) in the catheter group vs. 14 (8.5%) in the control group (p=0.005). The duration of surgery was longer in the catheter group (p=0.001). There were no significant differences in conversion, duration of bladder catheter placement, or length of hospital stay. Urinary tract infection occurred in 3 patients (2.0%) in the catheter group and 7 (4.3%) in the control group (p=0.257) and urinary retention occurred in 3 patients (2.0%) and 11 patients (6.7%), respectively (p=0.045). No intraoperative ureteric injuries occurred in either group. CONCLUSION: Ureteric catheter placement was successful in most cases and was not associated with intraoperative injuries. The increased length of surgery in patients with ureteric catheter placement may attest to the increased severity of pathology in these patients.

Mouse macrophages release a neutrophil chemotactic mediator following stimulation by staphylococcal enterotoxin type A.

OBJECTIVE AND DESIGN: To examine the role of macrophages in the neutrophil migration induced by staphylococcal enterotoxin type A (SEA) in mice. MATERIALS AND METHODS: Peritoneal macrophages were harvested from male Swiss mice pre-treated with thioglycollate. After adhering to plastic tissue culture dishes, the cells were washed and incubated with RPMI or SEA (0.62-2.5 microg/ml) and washed again prior to further incubation with RPMI alone. The medium was then collected, sterilized and assayed for promigratory activity in the mouse peritoneal cavity. RESULTS: Mouse macrophage monolayers stimulated with SEA secreted a thermolabile neutrophil chemotactic component (MNCC-SEA) with a molecular mass >100 kDa (by ultrafiltration). This release was dose- and time-dependent and was inhibited by dexamethasone but not by indomethacin or BW755C. Dexamethasone, indomethacin, BWA4C, BW755C, BN52021, cimetidine and SR48968 had no effect on the neutrophil migration induced by MNCC-SEA while capsaicin and SR 140333 reduced this phenomenon. CONCLUSIONS: Macrophages play a key role in the neutrophil recruitment induced by SEA probably by releasing an MNCC-SEA that presumably induces neutrophil migration via a mechanism mediated by substance P.

Involvement of nitric oxide on the peritoneal neutrophil influx induced by staphylococcal enterotoxin B in mouse.

In this study, the role of nitric oxide (NO) on neutrophil migration induced by staphylococcal enterotoxin B (SEB) in the mouse peritoneal cavity was investigated. The NO synthase inhibitors L-NAME and aminoguanidine, as well as dexamethasone, markedly reduced SEB-induced neutrophil influx. In mice with an increased population of peritoneal macrophages, the inhibition of SEB-induced neutrophil influx by these agents was significantly lower. The in vivo treatment with aminoguanidine inhibited only the iNOS activity, whereas L-NAME inhibited both the cNOS and iNOS activities. In conclusion, NO modulates the neutrophil migration in response to SEB through the activity of an iNOS isoform.

Role of nitric oxide on the increased vascular permeability and neutrophil accumulation induced by staphylococcal enterotoxin B into the mouse paw.

The role of nitric oxide (NO) on the increase in vascular permeability and neutrophil migration induced by staphylococcal enterotoxin B (SEB; 25 microgram/paw) in the mouse was investigated in this study. The NO synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) [but not its inactive enantiomer N(omega)-nitro-D-arginine methyl ester (D-NAME)], given intravenously (25-100 micromol/kg) or subplantarly (0.25-1.0 micromol/paw), reduced SEB-induced paw oedema significantly. A similar response was observed with aminoguanidine, given either intravenously (200-600 micromol/kg) or subplantarly (2 micromol/paw). In contrast to paw oedema, the plasma exudation in response to SEB was not affected by the subplantar injection of L-NAME or aminoguanidine. The inhibition of oedema and plasma exudation by systemic treatment with L-NAME or aminoguanidine was reversed by co-injection of the vasodilator iloprost (0.3 nmol/paw). Subplantar injection of SEB (25 microgram/paw) increased by 69% the myeloperoxidase (MPO) activity of SEB-treated paws, indicating the presence of neutrophils. Intravenous (12.5-50 micromol/kg) or subplantar (0.125-0.5 micromol/paw) administration of L-NAME (but not of its inactive enantiomer, D-NAME) largely reduced the MPO activity in SEB-treated paws. Similarly, intravenous (200-600 micromol/kg) or subplantar (2 micromol/paw) administration of aminoguanidine significantly reduced the MPO values of the SEB-injected paws. The vasodilator iloprost (0.3 nmol/paw) completely reversed the inhibition by L-NAME or aminoguanidine of the MPO activity in SEB-injected paws. Our results show that the increased vascular permeability and neutrophil accumulation in response to subplantar injection of SEB in the mouse are inhibited by L-NAME and aminoguanidine by mechanisms probably involving reduction of local microvascular blood flow.

The hind paw edema produced by staphylococcal enterotoxin B in female mice is modulated by sex hormones.

This paper describes the involvement of sex hormones in the edematogenic response produced by staphylococcal enterotoxin B (SEB) in the mouse hindpaw. Both the paw weight variation and the protein exudate produced by the intraplantar administration of SEB (12.5 micrograms/paw) to intact, randomly cycling female (IRCF) mice were significantly attenuated when the animals were ovariectomized (OVX). The attenuation of SEB-induced paw swelling produced by OVX was not reversed by estradiol (OE2) reposition. Thus, 4 h after the injection of SEB the increase in paw weight in OVX-mice treated with OE2 (10 micrograms/kg in corn oil) was 15.0 +/- 0.9 mg, while the exudation corresponded to 2.1 +/- 0.3 micrograms of Evans blue dye/g of tissue. Neither of these values differed significantly from those obtained 4 h after the intraplantar injection of SEB (12.5 micrograms/paw) in non-treated OVX-mice (paw swelling, 14.0 +/- 0.8 mg; dye exudation, 2.0 +/- 0.3 micrograms/g, N = 6). Pretreating IRCF mice once a day for three days with human chorionic gonadotrophin (40 IU/kg, i.m.) reduced the paw edema produced by the toxin, thus indicating an involvement of gonadotrophins in this event. A pronounced decrease in paw weight variation (about 45%) and dye exudation (61%) was detected when IRCF mice were previously treated every 72 h with three injections of OE2 (10 micrograms/kg in corn oil, i.m.). Similar situations were also seen when the animals were pretreated at 72 h intervals with three injections of testosterone (10 mg/kg in corn oil, i.m.). We conclude that the paw edema induced by SEB in female mice is hormonally regulated. Our results also indicate that the HPA-immune axis is involved in this phenomenon.

The hyperinsulinemia produced by concanavalin A in rats is opioid-dependent and hormonally regulated.

The present study examines the effect of concanavalin A (Con A) on the blood insulin and glucose levels of rats. Male and female rats treated with Con A (62.5-500 micrograms/kg) for three days showed a dose- and time-dependent hyperinsulinemia that lasted more than 48 h. Male rats were more sensitive to Con A. Thus, 6 h after treatment with Con A the circulating insulin levels in male rats had increased by 85% (control: 10.2 +/- 0.9 mU/l and Con A-treated: 18.8 +/- 1 mU/l) compared to only 38% (control: 7.5 +/- 0.2 mU/l; Con A-treated: 10.3 +/- mU/l) in females. An identical response was seen after 12 h. Con A (250 micrograms/kg) produced time-dependent hypoglycemia in both sexes but more pronounced in males. There was no correlation between the hypoglycemia and hyperinsulinemia described above. The Con A-induced hyperinsulinemia in rats of both sexes was abolished in gonadectomized animals (intact males: +101 +/- 17% vs orchiectomized males: -5 +/- 3%; intact females: +86 +/- 23% vs ovariectomized females: -18 +/- 7.2%). Pretreating intact male and female rats with human chorionic gonadotropin also significantly inhibited the Con A-induced hyperinsulinemia. Estradiol (10 micrograms/kg,i.m.) significantly blocked the Con A-induced increase in circulating insulin in male rats (101 +/- 17% for controls vs 32 +/- 5.3% for estradiol-treated animals, P < 0.05) while testosterone (10 mg/kg, i.m.) had no similar effect on intact female rats. Pretreating Con A-injected rats with opioid antagonists such as naloxone (1 mg/kg, s.c.) and naltrexone (5 mg/kg, s.c.) blocked the hyperinsulinemia produced by the lectin in males (control: +101 +/- 17% vs naloxone-treated: +5 +/- 14%, or naltrexone-treated: -23 +/- 4.5%) and females (control: +86 +/- 23% vs naloxone-treated: +21 +/- 20%, or naltrexone-treated: -18 +/- 11%). These results demonstrate that Con A increases the levels of circulating insulin in rats and that this response is opioid-dependent and hormonally regulated.

Neutrophil migration induced by staphylococcal enterotoxin type A in mice: a pharmacological analysis.

Staphylococcal enterotoxin type A induced marked neutrophil migration into the mouse peritoneal cavity and was dependent on the number of resident macrophages. This migratory response was dose- (16-64 microg of staphylococcal enterotoxin type A/cavity) and time-dependent, peaking at 12 h and disappearing after 72 h. Dexamethasone (0.5 mg/kg) inhibited the neutrophil migration induced by staphylococcal enterotoxin type A (32 microg; 42% inhibition). A similar response was observed with the platelet-activating factor-acether receptor antagonist, BN 52021 (ginkgolide B, 3-(1,1-dimethylethyl)-hexahydro-1,4-7b-trihydroxy-8-methyl-9H-1,7alph a (epoxymethano-1H,6alphaH-cyclopenta (c) furo (2,3-b) furo (3', 2': 3,4) cyclopenta (1,2-d) furan-5, 9, 12 (4H)-trione); 10 mg/kg; 57% inhibition), the histamine H2 receptor antagonist, cimetidine (2 mg/kg; 31% inhibition), the lipoxygenase inhibitor, BWA4C (N-(3-phenoxycinnamyl) acetohydroxamic acid); 10 mg/kg; 73% inhibition), and capsaicin (trans-8-methyl-N-vanillyl-6-nonamide), a sensory C-fiber neuropeptide depletor. In contrast, indomethacin (5 mg/kg) had no effect on staphylococcal enterotoxin type A-induced chemotaxis. We conclude that the peritonitis induced by staphylococcal enterotoxin type A in mice is macrophage-dependent. The mechanism whereby staphylococcal enterotoxin type A stimulates macrophages to induce neutrophil recruitment remains to be elucidated.

The pharmacological profile of mouse hind paw inflammation induced by staphylococcal enterotoxin type A.

OBJECTIVE AND DESIGN: The present paper examines the possible pharmacological mediators involved in mouse hind paw inflammation induced by staphylococcal enterotoxin type A (SEA). MATERIALS AND METHODS: The edema and the Evans blue exudation were measured in male Swiss mice (20-25 g) using methods described by Levy and Griswold, respectively. RESULTS: SEA (32 micrograms/paw) produced a biphasic, long-lasting, dose- and time-dependent edematogenic response. The acute phase edema was pronounced while the chronic edema was of a low intensity. Exudate was the principal component of the edema. The edematogenic effect of SEA appears to involve cyclooxygenase products and was dose-dependently reduced by pretreating the mice with dexamethasone, indomethacin, BW755C, WEB2086, capsaicin, diphenhydramine or cimetidine. CONCLUSIONS: These results demonstrate that SEA-induced mouse hind paw inflammation is a useful model for studying SEA-mediated enterotoxemia and may be sufficiently sensitive to differentiate between the effects of SEA and those of SE type B (SEB).

Utilization of high molecular weight cytokeratin on prostate needle biopsies in an independent laboratory.

OBJECTIVES: Immunoperoxidase staining of prostate tissues with antibodies to high molecular weight cytokeratin, which selectively labels basal cells, has recently been shown to be useful in the diagnosis of prostate cancer in academic centers. A growing sector in pathology is large independent laboratories, where little is known regarding practice patterns. The following study evaluated the use of high molecular weight cytokeratin in an independent laboratory specializing in prostate needle biopsies. METHODS: In a 2-month period (July 1, 1994 to August 31, 1994), 4047 prostate needle biopsies were evaluated. RESULTS: Without the use of ancillary studies, 2710 (67%) were diagnosed as benign, 978 (24.1%) were diagnosed as cancer, and 23 (0.6%) were diagnosed as high-grade prostate intraepithelial neoplasia. The remaining 336 atypical cases (8.3%) were further evaluated with antibodies to higher molecular weight keratin. Of the 336 cases, 253 (6.2% of total) were resolved as diagnostic for cancer, 68 (1.7% of total) were diagnosed as benign, and 15 (0.4% of total) remained atypical. The cost of performing high molecular weight cytokeratin was approximately $5.00 per case, which was not passed on to the patient. CONCLUSIONS: The use of high molecular weight cytokeratin decreased the rate of an atypical prostate biopsy from 8.3% to 0.4% at a negligible cost to the pathologist and patient.

Intracerebroventricular administration of canatoxin to rats increases the circulating levels of luteinizing hormone.

Recent evidence has implicated the central nervous system as a target organ for canatoxin, a toxic protein present in Canavalia ensiformis seeds. This toxin activates the lipoxygenase pathway of arachidonic acid metabolism and can thus induce the release of substances mediated by lipoxygenase products. In the present study, the circulating levels of luteinizing hormone (LH) were measured by RIA in male Wistar rats (200-240 g) after the administration of canatoxin into the lateral cerebral ventricle. Canatoxin (0.5-2 micrograms in 2 microliters daily for 3 days) caused a dose- and time-dependent increase in the plasma levels of LH. The total dose of canatoxin used is subconvulsive. At 2, 4 and 24 h after 2 micrograms of canatoxin LH levels were increased by 10%, 43% and 61%, respectively, compared to vehicle-injected animals (0.18 +/- 0.03 ng/ml). This response to 2 micrograms of canatoxin was not attenuated by pretreatment with two different lipoxygenase inhibitors, nordihydroguaiaretic acid (NDGA, 125 mg/kg) or esculetin (ECLT, 125 mg/kg), ip, 1 h before each canatoxin (CNTX) injection; % increase in LH with CNTX alone: 61%; CNTX+NDGA: 54%; CNTX+ECLT:76%; N = 5/group. These data show that intracerebral injection of CNTX in rats increases circulating levels of LH via a mechanism that is independent of the lipoxygenase pathway.

Increased insulin circulating levels induced by canatoxin in rats.

Canatoxin, a proteic neurotoxin from Canavalia ensiformis seeds, raises circulating insulin levels and induces hypoglycemia in rats. The hyperinsulinemia produced by canatoxin (6 micrograms kg-1, 20 min; 108% of increase in female rats) was both time and dose dependent and lasted only about 30 min, while the fall in blood glucose levels (around 30%) was long lasting. The hyperinsulinemic response to canatoxin was greater in females (+108 +/- 18%) than males (+43 +/- 8%), but no difference was noted in the hypoglycemia. Pretreatment of rats with either naloxone, naltrexone, atropine or hexamethonium abolished both the hyperinsulinemia and the hypoglycemia. These data suggest that these phenomena are influenced by opioids and depend on parasympathetic stimulation.

Canatoxin triggers histamine secretion from rat peritoneal mast cells.

Canatoxin, a toxic protein present in the seeds of Canavalia ensiformis, induces the secretion of serotonin, dopamine and insulin through activation of the lipoxygenase pathway. The purpose of the present study was to verify if canatoxin causes histamine release from rat peritoneal mast cells and to perform a detailed study of this phenomenon. Our results indicate that canatoxin is capable of activating mast cells to release histamine. The process is time- and concentration-dependent, occurs without cell damage and requires metabolic energy as well as the presence of divalent cations (Ca2+ and Mg2+). Optimal release occurs at 37 degrees C and at physiological pH. Extremes of temperature (0 degree C and 45 degrees C) inhibit the process. We conclude that canatoxin induces histamine release from rat peritoneal mast cells by an active secretory process.

Further studies on the hypoxia produced by canatoxin in rats.

Canatoxin, a convulsant neurotoxin from the seeds of Canavalia ensiformis, induces lipoxygenase-dependent hypoxia in rats which is blocked by hexamethonium. The purpose of the present study was to examine the relationship between canatoxin-induced hypoxia and bronchoconstriction. Since several effects of the toxin are very similar to those described for morphine and opioid-like peptides, the effects of opioid antagonists were also investigated. Pretreatment of male, adult Wistar rats (200-250 g) with cyproheptadine (80 micrograms/kg, ip, N = 6) and isoproterenol (100 micrograms/kg, ip, N = 6) partially blocked (% variation of pO2: CNTX alone: -26.67 +/- 2.56, N = 6; with cyproheptadine: -16.15 +/- 2.97*, N = 6; with isoproterenol: -17.73 +/- 1.93*, N = 6; *P < 0.05 as compared to CNTX alone) the hypoxia but no effect was observed with diphenhydramine (2 mg/kg, ip, N = 6) or atropine (2 mg/kg, ip, N = 6). The hypoxemic effect of canatoxin (100 micrograms/kg, i.v., 20 min, N = 6) was also almost completely blocked with either naloxone (1 mg/kg, sc, N = 6) or naltrexone (5 mg/kg, sc, N = 6). The results presented here provide evidence suggesting that both opioid peptides and bronchoconstriction seem to play a role in the hypoxia caused by canatoxin.