Bouveret Syndrome - An Exceptional Complication of a Very Frequent Disease

The Bouveret syndrome is an exceptional complication of the gallbladder lithiasis. Hereby it is described the case of a patient with a history of gallstones complicated on the long-term outcome with gastric outlet obstruction, due to a large gallstone of the duodenum, migrated via a cholecysto-duodenal fistula. The clinical, radiological features and the patient management are described.

Alternative ileal flap for bladder augmentation if mesentery is short

PURPOSE

To date the clam ileocystoplasty is the preferred method of bladder augmentation in children when the urodynamic problem is non-compliance and/or detrusor overactivity. The key to this technique is the incision of the bladder wall deep into the pelvis down to the trigone in order to avoid a diverticulum like neobladder and to provide adequate margin for augmentation. The detubularised ileum flap therefore has to reach to the bottom of the divided bladder on a reliable vascular pedicle without significant tension. A short ileal mesentery caused by previous surgery, peritonitis, peritoneal dialysis or ventriculo-peritoneal shunt may complicate surgery and compromise outcome. We hypothesized we can rely on the communication of the intramural vessels within the intestine and can detubularise the ileum adjacent to the mesentery rather than along the antimesenteric line and this could be combined with ligation of some vasa recta (VR) in order to create alternative ileum flaps, which reach further into the pelvis. Our aim was to assess the viability of the alternative flaps detubularised along the paramesenteric line and measure how many VR could be sacrificed beyond the tertiary arcades.

MATERIALS AND METHODS

After ethical approval adjacent ileal segments were detubulirased along the antimesenteric line (Group 1) and along the paramesenteric line (Group 2) in 5 minipigs in general anaesthesia. Ligation of 0,1,2,3 and 4 VR has been performed starting from the free end of the segments. The length of the ileal flaps was recorded. The microcirculation of flap edges was detected by in vivo microscopy using orthogonal polarising spectral imaging (Cytoscan A/R Cytometrics, PA, USA). Clam ileocystoplasty was performed with the ileum detubularised along the paramesenteric line without ligation of VR. Specimens of the augmented bladder were obtained after 4 weeks and stained with Hematoxilin + Eosin.

RESULTS

No alteration in capillary red blood cell velocity (RBCV) and perfusion rate (PR) was observed after paramesenteric detubularisation. The flaps in Group 2 reached 20.25 ± 0.5 mm longer vs.

CONTROL

This is 98% of the mean bowel width (20.5 ± 0.57 mm) measured in the animals. Ligation of each VR further increased the length of both flaps (mean: 10.59 ± 3.18 mm) however ligation of more than 2 VR gradually decreased the microcirculation in both groups. All animals augmented with alternative flap survived, there was no urine leak or suture break down. Histology confirmed viable bowel flaps.

CONCLUSION

Paramesenteric detubularisation of the ileum is fully tolerated and results in longer reaching ileal flap vs.

CONTROL

Only limited ligation of VR is tolerated.

DISCUSSION

This study showed the first time that clam ileocystoplasty is feasible with ileal flap detubularised along the paramesenteric line. The use of the animal model and the relative short postoperative observation are the main limitations of this study.

Exhaled methane concentration profiles during exercise on an ergometer

Exhaled methane concentration measurements are extensively used in medical investigation of certain gastrointestinal conditions. However, the dynamics of endogenous methane release is largely unknown. Breath methane profiles during ergometer tests were measured by means of a photoacoustic spectroscopy based sensor. Five methane-producing volunteers (with exhaled methane level being at least 1 ppm higher than room air) were measured. The experimental protocol consisted of 5 min rest--15 min pedalling (at a workload of 75 W)--5 min rest. In addition, hemodynamic and respiratory parameters were determined and compared to the estimated alveolar methane concentration. The alveolar breath methane level decreased considerably, by a factor of 3-4 within 1.5 min, while the estimated ventilation-perfusion ratio increased by a factor of 2-3. Mean pre-exercise and exercise methane concentrations were 11.4 ppm (SD:7.3) and 2.8 ppm (SD:1.9), respectively. The changes can be described by the high sensitivity of exhaled methane to ventilation-perfusion ratio and are in line with the Farhi equation.

Inflammatory activation after experimental cardiac tamponade

BACKGROUND/PURPOSE

Cardiac tamponade is a medical emergency situation associated with a high rate of life-threatening complications, even after immediate interventions. Our aim was to characterize the acute inflammatory consequences of this event in a clinically relevant large animal model.

METHODS

Cardiac tamponade was induced for 60 min in anesthetized, ventilated and thoracotomized minipigs by intrapericardial fluid administration, the mean arterial pressure (MAP) being maintained in the interval of 40-45 mm Hg (n = 8). A further group (n = 7) served as sham-operated control. The global macrohemodynamics, including the right- and left-heart end-diastolic volumes (RHEDV and LHEDV), the pulmonary vascular resistance index (PVRI) and the superior mesenteric artery (SMA) flow, were monitored for 240 min, and the intestinal microcirculatory changes (pCO2 gap) were evaluated by indirect tonometry. Blood samples were taken for the determination of cardiac troponin T and vasoactive inflammatory mediators, including histamine, nitrite/nitrate, big-endothelin, superoxide and high-mobility group box protein-1 levels in association with intestinal leukocyte and complement activation.

RESULTS

The cardiac tamponade induced significant decreases in MAP, cardiac output, LHEDV and SMA flow, while the PVRI and the pCO2 gap increased significantly. After the removal of fluid from the pericardial sac, the MAP and the LHEDV were decreased, while the PVRI and the pCO2 gap remained elevated when compared with those in the sham-operated group. In the posttamponade period, the abrupt release of inflammatory mediators was accompanied by a significant splanchnic leukocyte accumulation and complement activation.

CONCLUSIONS

The macrocirculatory and splanchnic microcirculatory disturbances were accompanied by a significant proinflammatory reaction; endothelin and the complement system may be significant components of the inflammatory cascade that is activated in this porcine model of pericardial tamponade.

Pulmonary mechanical responses to intestinal ischaemia-reperfusion and endotoxin preconditioning

During intestinal ischaemia-reperfusion, endotoxin can be translocated. Pretreatment with sublethal doses of endotoxin develops tolerance to ischaemia-reperfusion in different organs; however, the tolerance to intestinal ischaemia-reperfusion in the lung has rarely been investigated. Our aim was to study the role of endotoxin pretreatment in the mechanical responses and inflammatory activation induced by intestinal ischaemia-reperfusion in the lung. Wistar rats were preconditioned with a sublethal dose of endotoxin on day -3 or -1. On day 0, anesthetized, paralyzed and mechanically ventilated rats were subjected to a 60-min occlusion of the superior mesenteric artery and a subsequent 240-min reperfusion. The low-frequency forced oscillation technique was employed to characterize the separate mechanical responses of the airways and respiratory tissues. Intestinal ischaemia-reperfusion caused a significant decrease in airway resistance and increases in tissue resistance and elastance, nitric oxide synthase and myeloperoxidase activities. Pretreatment with endotoxin modified both the pulmonary mechanical responses and the inflammatory markers in the lung during intestinal ischaemia-reperfusion. We conclude that endotoxin or the endotoxin-induced processes (and humoral mediators) have significant roles in the pathomechanism of the remote pulmonary effect of intestinal ischaemia-reperfusion.

The perspective of the vascular surgery trainee on new ACGME regulations, fatigue, resident training, and patient safety

OBJECTIVE

To assess the opinions of vascular surgery trainees on the new Accreditation Council for Graduate Medical Education (ACGME) guidelines.

METHODS

A questionnaire was developed and electronically distributed to trainee members of the Society for Vascular Surgery.

RESULTS

Of 238 eligible vascular trainees, 38 (16%) participated. Respondents were predominantly 30 to 35 years of age (47%), male (69%), in 2-year fellowship (73%), and at large academic centers (61%). Trainees report occasionally working while fatigued (63%). Fellows were more likely to report for duty while fatigued (P = .012) than integrated vascular residents. Respondents thought further work-hour restrictions would not improve patient care or training (P < .05) and may not lead to more sleep or improved quality of life. Respondents reported that duty hours should vary by specialty (81%) and allow flexibility in the last years of training (P < .05).

CONCLUSIONS

Vascular surgery trainees are concerned about further duty-hour restrictions on patient care, education, and training and fatigue mitigation has to be balanced against the need to adequately train vascular surgeons.

Successful surgical intervention in a case of spontaneous chylothorax in an infant unresponsive to conservative therapy

We report a case of an infant with spontaneous chylothorax due to the congenital malformation of a small lymph vessel of the chest wall. Conservative therapy with omitting long-chain fatty acids from the diet, fat-free nutrition, total parenteral nutrition and intravenous somatostatin did not result in the decrease of pleural effusion. Thoracic surgical intervention performing thoracic duct ligation and using fibrin sealants was applied after 10 days of unsuccessful conservative therapy, and resulted in the complete recovery of the patient. Our experience support the already existing observations, that in cases where the daily loss of chyle exceeds 100 ml per age years and/or lasts longer than 2 weeks, early surgical intervention is recommended.

N-Methyl-D-aspartate receptor antagonism decreases motility and inflammatory activation in the early phase of acute experimental colitis in the rat

BACKGROUND

Inflammatory bowel diseases are accompanied by severe motility disorders. The aim of our study was to investigate whether the blockade of peripheral N-methyl-D-aspartate (NMDA)-sensitive glutamate receptors (NMDA-Rs) alters motility changes in chemically induced acute colitis and how this modulation is accomplished.

METHODS

The inflammatory and motility changes in 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis were studied in anaesthetized Wistar rats following treatment with the natural NMDA-R antagonist kynurenic acid (KynA) or SZR-72, a blood-brain barrier-permeable synthetic KynA analogue. The macrohaemodynamics, serosal microcirculation (visualized by intravital videomicroscopy), plasma levels of tumour necrosis factor alpha (TNF-alpha), inflammatory enzyme activities (xanthine oxidoreductase (XOR), myeloperoxidase (MPO) and nitric oxide synthase (NOS)), and colonic motility (with a strain-gauge technique) were evaluated 17 h after colitis induction and compared with the control conditions.

KEY RESULTS

The TNBS enema induced a systemic hyperdynamic circulatory reaction, increased the serosal capillary blood flow, significantly elevated the mucosal XOR, MPO and NOS activities and augmented the colonic motility relative to the controls. The NMDA-R antagonist treatment with KynA or SZR-72 significantly reduced the XOR, NOS and MPO activities, decreased the motility and increased the tone of the colon.

CONCLUSIONS & INFERENCES

These data demonstrate a potential modulatory mechanism of NMDA-R in altered colonic motility in TNBS colitis. Inhibition of the enteric NMDA-Rs may provide a therapeutic option via which to influence intestinal hypermotility, microcirculatory changes and inflammatory activation simultaneously.

Strategies to convert to resectability the initially unresectable colorectal liver metastases

BACKGROUND/AIMS

Because only 25% of colorectal liver metastases (CRLM) are initially resectable, we used several therapeutic strategies to convert to resectability some of the initially unresectable CRLM. Our results are presented herein.

METHODOLOGY

The therapeutical strategies were: (A) Liver resection after portal vein ligation--10 patients; (B) Staged liver resection with portal vein ligation--3 patients; (C) Staged liver resection without portal vein ligation--3 patients; (D) Resection after "do wn-sizing" of CRLM by conversion chemotherapy--3 patients; (E) Resection associated with radiofrequency ablation--9 patients.

RESULTS

The resectability rate was 60% (6/10) in group A and 66% (2/3) in groups B and C. For the entire series, the morbidity and mortality rates were 50% (11/22 patients) and 4.5% (1/22 patients), respectively. The overall one-, two-, and three-year survival rates of the entire group of patients rendered to resectability were 80.1%, 44.8% and 35.9%, respectively.

CONCLUSIONS

In selected patients with initially unresectable CRLM, "two-stage" hepatectomies (with/without PVE/PVL) can be performed safely, achieving long-term survival. Liver resection may be achieved safely after conversion chemotherapy in some previously unresectable patients, with considerable survival benefit. RFA could be associated with liver resection to increase the number of patients eligible for complete removal and ablation of their CRLM.

Modulation of cardiac contractility through endothelin-1 release and myocardial mast cell degranulation

The aim of this study was to outline the consequences of a hypertonic saline-dextran-40 (HSD) infusion-induced peripheral flow stimulus on the ventricular function in closed-chest, pentobarbital-anesthetized dogs. We hypothesized that HSD-induced elevation in endothelin-1 (ET-1) and nitric oxide (NO) release can have a role in myocardial contractile responses; and that cardiac mast cells (MC) degranulation may be involved in this process. The consequences of disodium cromoglycate (a MC stabilizer) or ETR-p1/fl peptide (an endothelin-A receptor antagonist) treatment were evaluated. A 4 ml/kg iv HSD40 infusion significantly increased cardiac index and myocardial contractility, and resulted in a decreased peripheral resistance. The postinfusion period was characterized by significant plasma NO and ET-1 elevations, these hemodynamic and biochemical changes being accompanied by a decreased myocardial ET-1 content, NO synthase activity and enhanced myocardial MC degranulation. Disodium cromoglycate treatment inhibited the HSD40-induced elevations in myocardial contractility and MC degranulation, and similar hemodynamic changes were noted after treatment with ETR-p1/fl peptide, together with a normalized myocardial myocardial ET-1 content, NO synthesis and a significant reduction in MC degranulation. These results indicate that peripheral NO and ET-1 release modulates the cardiac contractility through myocardial ET-A receptor activation and MC degranulation.

Gallbladder adenoma with focal adenocarcinoma

The majority of polypoid lesions of the gallbladder are cholesterolosis pseudopolyps. True neoplastic GB polyps are represented mainly by adenomas. The case of a 52-year old male patient with an adenomatous polyp of the GB with focal adenocarcinoma is presented.

Isolated resection of the caudate lobe: indications, technique and results

BACKGROUND/AIMS

This paper reports a series of 24 isolated caudate lobe resections (ICLR), performed for 13 benign tumors (10 hemangiomas, 2 focal nodular hyperplasias, 1 adenoma) and 11 malignant tumors (3 hepatocarcinomas, 1 peripheral cholangiocarcinoma and 7 metastatic - 5 colorectal carcinomas, 1 breast carcinoma, 1 adrenal carcinoma). Klatskin tumors were excluded.

METHODOLOGY

There were 10 hemangioma enucleations, 7 Spiegel lobe resections and 7 high dorsal resections. Total vascular exclusion was performed in 7 cases. Vascular resection with reconstruction was necessary in 5 cases.

RESULTS

Complications occurred in 7 cases (3 bile leaks, 3 abdominal fluid collections and one liver failure leading to death). From the 10 patients with malignant tumors who survived the operation, 7 developed recurrences: 2 intrahepatic, 1 retroperitoneal, 4 systemic. Five patients are alive (3 without recurrence). One patient died of multiple complications after a repeat hepatectomy and colectomy. Three patients died from generalized disease. Another patient, with generalized disease, was lost from follow-up.

CONCLUSIONS

ICLR is a difficult operation, especially with malignant tumors. Total vascular exclusion of the liver is routinely recommended in high dorsal resection. Malignant tumors located in the caudate lobe have a poor prognosis; local and, especially, distant metastases are frequent. Aggressive chemotherapy and follow-up are recommended.

Kynurenic acid inhibits intestinal hypermotility and xanthine oxidase activity during experimental colon obstruction in dogs

Kynurenic acid (KynA), an endogenous antagonist of N-methyl-d-aspartate (NMDA) glutamate receptors, protects the central nervous system in excitotoxic neurological diseases. We hypothesized that the inhibition of enteric glutamate receptors by KynA may influence dysmotility in the gastrointestinal tract. Group 1 of healthy dogs served as the sham-operated control, in group 2, the animals were treated with KynA, while in groups 3 and 4 mechanical colon obstruction was maintained for 7 h. Group 4 was treated with KynA at the onset of ileus. Hemodynamics and motility changes were monitored, and the activities of xanthine oxidoreductase (XOR) and myeloperoxidase (MPO) were determined from tissue samples. Colon obstruction induced a hyperdynamic circulatory reaction, significantly elevated the motility index and increased the mucosal leucocyte accumulation and the XOR activity. The KynA treatment augmented the tone of the colon, permanently decreased the motility index of the giant colonic contractions and reduced the increases in XOR and MPO activities. These effects were concomitant with the in vitro inhibition of XOR activity. In conclusion, KynA antagonizes the obstruction-induced motility responses and XOR activation in the colon. Inhibition of enteric NMDA receptors may provide an option to influence intestinal hypermotility and inflammatory changes.

Simultaneous adeno- and squamous cell carcinoma with different phenotypic profiles in a rat model of chronic gastroesophageal reflux

The aim of our study was to investigate the incidence of duodeno-gastroesophageal reflux-induced malignant transformation in a series of duodeno-esophageal anastomosis operations in rats. This surgical method provides a model for reflux-induced esophageal pathologies, without carcinogen administration. The study design included the follow-up of 31 cases. Thirty weeks of duodeno-gastroesophageal reflux disease significantly increased the risk of the development of Barrett's esophagus, and reflux-induced esophageal adenocarcinoma formation was evident in four animals. In one of these particular cases, a superficial squamous cell cancer was noted in close vicinity to the adenocarcinoma formation. For further analysis, a detailed immunohistochemical staining protocol was used. The immunophenotypes revealed cyclin D1 expression (nuclear positivity in 35% of all the squamous cells), p53 protein accumulation (50% nuclear positivity), with a low expression of cox-2, and negative c-erbB2 staining in the squamous carcinoma cells. The specialized intestinal metaplasia and mucinous adenocarcinoma cells exhibited exclusively diffuse cox-2 positivity (90% of all glandular cells) and weak focal c-erbB2 (5%) staining, without cyclin D1 expression or p53 protein accumulation. Real-time polymerase chain reaction was applied to quantify the abundance of p53, cyclin D1 and cox-2 mRNAs in this biopsy. The most dramatic changes were observed in the level of expression of cyclin D1 (a 9.08-fold expression as compared with the non-treated esophagus samples), while the p53 and cox-2 gene expressions were increased by 1.61 and 2.45-fold, respectively, relative to the non-treated samples. The results afford evidence of the simultaneous activation of more than one possible carcinogenetic pathway in experimental gastroesophageal reflux disease. Synchronous neoplasm formation with different growth pattern characteristics is a rarity in humans, and this phenomenon suggests that the presented model is a suitable means of mimicking the whole spectrum of human gastroesophageal reflux disease pathology.

Early Microcirculatory Changes after Ischemic Preconditioning and Small Bowel Autotransplantation

BACKGROUND/AIMS

Ischemia-reperfusion injury contributes to the high complication rate of small bowel transplantation (SBTX). Ischemic preconditioning (IPC) protects against reperfusion injury in several organs, but the IPC-induced microcirculatory reaction in the intestine is unknown.

METHODS

We examined the effects of IPC on the macrohemodynamics and graft microcirculation in a canine model of SBTX during a 4-hour reperfusion period. In group 1 SBTX was performed, in group 2 IPC was induced before graft harvesting (ischemia 3 times for 5 min, followed by 10 min of reperfusion). Cardiac index and mesenteric blood flow were measured, and the mucosal microcirculation, villus epithelial thickness and functional capillary density were monitored by orthogonal polarization spectral imaging. Leukocyte-endothelial cell interactions were monitored in the postcapillary venules, with intravital fluorescence microscopy.

RESULTS

Reperfusion decreased cardiac index and mesenteric blood flow during reperfusion; IPC significantly improved these changes. Reperfusion was accompanied by decreased functional capillary density and epithelial thickness of the villi and increased leukocyte-endothelial cell interactions. IPC increased functional capillary density, prevented epithelial narrowing and reduced leukocyte rolling and adherence.

CONCLUSION

IPC improves the macrohemodynamics and the intestinal microcirculation and reduces leukocyte-mediated tissue injury during reperfusion. IPC can be an effective tool to limit reperfusion injury during SBTX.

Gastrointestinal stromal tumors: retrospective analysis of the computer-tomographic aspects

PURPOSE

To describe the computer-tomographic (CT) aspects of gastrointestinal stromal tumors (GISTs) in correlation to their histology.

MATERIAL AND METHODS

The medical records of all patients at our hospital with a histologic diagnosis of GIST between January 2002 and June 2006, and investigated before surgery by CT, were reviewed. Two radiologists with knowledge of the diagnosis reviewed the CT findings.

RESULTS

Amongst 15 cases of GISTs, 9 cases involved the stomach and 4 cases the small intestine. Location of the primary tumor could not be determined for 2 of 15 tumors, because of the presence of extensive peritoneal metastases. Most primary tumors were predominantly extraluminal (13 cases) while two were clearly endoluminal. The mean diameter of the primary tumor was 8 cm. The tumor margin was well defined in 12 patients and irregular in 3 cases. Central fluid attenuation was present in 11 tumors, while central gas was seen in two cases. Metastases were seen in 2 cases at presentation and in another 2 patients during follow-up. Spread was exclusive to the liver or peritoneum. Visceral obstruction was absent even in extensive peritoneal metastatic disease. Ascites was an unusual finding.

CONCLUSIONS

CT plays an important role not only in the detection and the localization but also in the evaluation of the extension and follow-up of theses tumors. Using only CT aspects, we can only suspect the diagnosis to GISTs. Often other soft-tissue tumors with gastrointestinal involvement can mimic GISTs. In all cases histological diagnosis is essential.

Methods for syntheses of N-methyl-DL-aspartic acid derivatives

A novel practical method for the synthesis of N-methyl-DL-aspartic acid 1 (NMA) and new syntheses for N-methyl-aspartic acid derivatives are described. NMA 1, the natural amino acid was synthesized by Michael addition of methylamine to dimethyl fumarate 5. Fumaric or maleic acid mono-ester and -amide were regioselectively transformed into beta-substituted aspartic acid derivatives. In the cases of maleamic 11a or fumaramic esters 11b, the alpha-amide derivative 13 was formed, but hydrolysis of the product provided N-methyl-DL-asparagine 9 via base catalyzed ring closure to DL-alpha-methylamino-succinimide 4, followed by selective ring opening. Efficient methods were developed for the preparation of NMA-alpha-amide 13 from unprotected NMA via sulphinamide anhydride 15 and aspartic anhydride 3 intermediate products. NMA diamide 16 was prepared from NMA dimethyl ester 6 and methylamino-succinimide 4 by ammonolysis. Temperature-dependent side reactions of methylamino-succinimide 4 led to diazocinone 18, resulted from self-condensation of methylamino-succinimide via nucleophyl ring opening and the subsequent ring-transformation.

Adrenalectomy for metastases from hepatocellular carcinoma - a single center experience

BACKGROUND

Adrenal metastases (AM) from hepatocellular carcinoma (HCC) are rarely seen in clinical practice. The treatment is not standardized, the indications and efficacy of different therapeutic approaches being still controversial.

PATIENTS

Between January 1995 and December 2005, 174 patients underwent liver resection for HCC in our center. AM were detected in four patients (2.3%): three of them had HCC and synchronous AM, and the remaining one developed AM 10 months after liver resection. All the patients with AM were treated by adrenalectomy (simultaneously with liver resection in synchronous metastases), followed by systemic chemotherapy. Non-resectable multifocal liver recurrences occurred in two patients, one of them having also a contralateral adrenal metastasis; these two patients are presently alive 26 and 43 months after adrenalectomy, respectively. Another patient died by liver recurrence 27 months postoperatively. The fourth patient is disease-free at 17 months after the initial operation.

CONCLUSIONS

Adrenalectomy for AM from HCC should be performed whenever the primary tumor is well therapeutically controlled and the patient has a good performance status. Adrenalectomy offers the chance of more than 2 years survival in many patients. However, once AM are detected, the prognosis remains poor.

Pathophysiology of ischemia-reperfusion injury

Our studies characterized the intestinal microcirculatory changes in canine models of intestinal hypoperfusion (hemorrhagic shock) or ischemia-reperfusion (small bowel autotransplantation). The villus microcirculatory parameters (functional capillary density, mean red blood cell velocity) were observed by intravital microscopy using orthogonal polarization spectral imaging. The leukocyte reaction (rolling and firm adherence) in the mesentery was quantified by using conventional fluorescence videomicroscopy. The investigations were aimed at determining whether the compromised intestinal villus perfusion could be influenced by endothelin-A receptor inhibition, volume resuscitation, or ischemic preconditioning. The results demonstrated the pathophysiological significance of endothelin-A receptor activation in ischemia-reperfusion-induced microcirculatory changes. Second, it was shown that colloid fluid therapy with hydroxyethyl-starch effectively ameliorated the microcirculatory consequences of hypovolemia, which correlated with a lower endothelin release. Third, ischemic preconditioning when applied 60 minutes before ischemia, inhibited the reperfusion-induced superoxide production, improved capillary perfusion, and attenuated leukocyte activation within the intestinal graft. Among the examined therapeutic strategies aimed at improving the outcome of intestinal microcirculatory dysfunction, endothelin-A receptor antagonist pretreatment and ischemic preconditioning are promising tools to decrease the harmful consequences of ischemia/reperfusion.

Two-stage hepatectomy: an analysis of a single center's experience

Hepatic resection remains the only potential curative treatment for either primary or secondary liver tumors. In order to increase the resectability of initially unresectable tumors and to decrease the posthepatectomy morbidity and mortality, ligation and section of a portal branch with consecutive hepatic resection is recommended. Between September 1st 1999 and January 1st 2006, in the Department of General Surgery and Liver Transplantation of Clinical Institute Fundeni (Bucharest), the ligation of a portal branch was performed in 15 patients with gross hepatic tumors: hepatocellular carcinoma (2 cases), peripheral cholangiocarcinoma (6 cases) and hepatic metastases for colorectal cancer (7 cases). Two-stage hepatectomy was performed in 8 cases. The interval between the two operations ranged between 4 weeks and 2 months (except one case that returned to us only after 6 months, when was reevaluated and resected). Hepatic resection could not be performed in 7 cases due to the local and regional progression of the disease (4 cases) or to the absence of the hypertrophy-atrophy process (3 cases). In the 8 resected cases, hepatic failure occurred posthepatectomy in 2 patients, resulting in the death of one patient; that means a mortality of 12.5%. Other two patients died at 4 and 10 months respectively, as a result of distant metastases. The rest of 5 patients are alive, free of recurrence; two of them have more than 5 years from the operation. CONCLUDING: portal vein ligation can be performed in selected cases of unresectable gross hepatic tumors. Two-staged hepatectomy is not always feasible. Moreover, the hypertrophy of the contralateral lobe does not always prevent the postoperative hepatic failure. For the cases that can be resected, both survival and quality of life are significantly improved.

Surgical treatment of intercostal hernia with implantation of polypropylene mesh

The intercostal hernia of the lung is a very rare extraordinary disease that requires operation because of the complaints and potential complications. The authors review cases of their operations and analyze the subsequence and treatment. Three patients have been treated for intercostal lung hernia in our treatment. The causes of this disease were a previous thoracotomy in one case and fits of coughing in the other two cases. The diagnosis was set up on the grounds of the specific clinical symptoms, thoracic X-ray and CT scan. The hernia was dissolved with percostal stitches and with the suture of the thoracic musculature in two cases. Plastic operation of the thoracic wall by implanting a polypropylene surgical mesh (Prolen, Ethicon, Johnson & Johnson) was performed in the case of the third patient and later in the first two patients due to recrudescence. In one case the authors were constrained to resect the dystelectasial lung in the hernial sac. The three patients had been operated five times. Relapse of hernia was detected in two patients, in whom the intercostal space had been reconstructed with percostal stitches. We did not detect any relapsing in those two patients at 33 and 66 months after the second operation with mesh implantation. The third patient who got mesh implant immediately did not relapse 12 months after the operation. Intercostal lung hernia is an indication of operation. A plastic operation of the thoracic wall combined with the implantation of a surgical mesh is recommended to close the hernial orifice, which is suitable for treating both primary and relapsed hernias. Recurrence is rare in those patients treated with this method.

Esophageal ATP synthase and keratinocyte growth factor gene expression changes after acid and bile-induced mucosal damage

OBJECTIVE AND DESIGN

Intramural gene expression changes may be critically involved in tissue damage, defense and repair after esophageal regurgitation. The aims were to characterize the consequences of short-term exposure to luminal bile, acid, or bile mixed with acid on the beta-ATPase, keratinocyte growth factor 1 (KGF-1) and KGF receptor (KGF-R) expressions within the mucosa and the muscle layer in a large animal model.

MATERIALS AND SUBJECTS

Esophageal segments of anesthetized dogs were exposed to saline (n = 3), diluted canine bile (n = 6), hydrochloric acid (n = 5) or bile + hydrochloric acid (n = 5), and tissue biopsies were taken at the end of the 180-min observation period. Semiquantitative reverse transcriptase polymerase chain reactions were carried out and the degree of histological damage was evaluated on the 0-16-grade Geisinger scoring scale.

RESULTS

Acid exposure was followed by a significant decrease in the level of beta-ATPase expression in the mucosa, and parallel increases in KGF-1 and KGF-R expression. Corresponding changes in the muscle layer were not significant. Bile alone evoked more severe tissue damage, with significantly decreased beta-ATPase levels in both the mucosa and the muscle, whereas the KGF-1 expression did not change significantly. The bile + acid treatment induced an intermediate state, with significant beta-ATPase transcription level decreases in both layers, while the mucosal KGF-1 expression was lower than that following acid treatment alone.

CONCLUSIONS

The acid-induced transcriptional level downregulation of mucosal beta-ATPase gene expression in the smooth muscle layer was exacerbated by bile, but the concomitant KGF and KGF-R gene expression changes may indicate the start of a consecutive repair process.

Heterogeneous Microcirculation in the Rat Small Intestine during Hemorrhagic Shock: Quantification of the Effects of Hypertonic-Hyperoncotic Resuscitation

PURPOSE

In the event of a spatial or temporal microvascular perfusion heterogeneity conventional methods are often inadequate to describe the microcirculatory changes. Our aim was to use a new formula to characterize and compare the microcirculatory reactions in the mucosa and longitudinal muscle of the rat small intestine in response to hypertonic/hyperoncotic and normotonic resuscitation strategies.

METHODS

Intravital videomicroscopy with an orthogonal polarization spectral (OPS) imaging technique was utilized. Microcirculatory variables were recorded during hemorrhagic shock (HS; 50 mm Hg mean arterial pressure for 60 min) and fluid replacement with 0.9% saline or with 7.2% saline containing 10% hydroxyethylstarch 200/0.5 (Osmohes; 4 ml/kg). Due to the temporal perfusion variability, microcirculatory changes were described using the calculation of the average red blood cell velocity (A-RBCV), while the spatial changes were calculated as a function of the size of the perfused capillary network.

RESULTS

During HS and the late phase of resuscitation, perfusion was characterized by capillary flow motion (i.e. variability in time) in the villi, and by spatial flow heterogeneity in the longitudinal muscle layer. The approximately 40% decrease in the calculated villus A-RBCV during HS was only partially affected by 0.9% saline, whereas Osmohes completely restored A-RBCV by increasing both the red blood cell velocity and the duration of high-flow periods at the onset of resuscitation in the villi. The approximately 60% reduction in A-RBCV in the muscle layer during HS was not followed by an appreciable recovery in either group, but Osmohes significantly increased A-RBCV in the late resuscitation phase.

CONCLUSIONS

The hypertonic/hyperoncotic solution induces a considerable microcirculatory improvement in two distinct layers of the small intestine after HS. This positive effect is related to the amelioration of the intestinal microcirculatory heterogeneity.

Effect of pulmonary edema on changes in lung mechanics in rats

Because of similar pathophysiologic changes, oleic acid (OA)-induced pulmonary edema has been well established as an experimental model of certain types of ARDS. Data in the literature indicate changes mostly in global pulmonary mechanical parameters (lung resistance and compliance) during permeability-type edema. Therefore, we designed this study (1) to separate the OA-induced mechanical responses into airway and parenchymal components, and (2) to examine the relationship between the mechanical parameters and the degree of edema. Anaesthetized, paralyzed, mechanically ventilated rats were given iv. OA in doses of 0 (C n=9), 0.05 (OA0.05 n=8), 0.1 (OA0.1 n=10) and 0.3 (OA0.3 n=5) ml/kg. Respiratory system impedance was measured with a wave-tube low-frequency forced oscillation technique, and a model fitting was used to estimate airway (Raw) and lung tissue parameters (G, parenchymal damping; H, elastance). Pulmonary edema was quantified by gravimetric analysis (WW/DW, wet-to-dry weight ratio). In the OAL0.05 group, transient, but significant increase in Raw, only slight increase in H, and no response in G was observed. Different responses were obtained in OA0.1: significant Raw, G, and H values in survivors; rapid and significantly higher responses in all three parameters in non-survivors. Extremely large parameter values were measured in OA0.3. We found that OA caused dose-related increases in WW, DW and WW/DW. Highly significant correlations were found between the degree of edema and G or H, but not Raw. This study demonstrates that low dose of OA had only transient lung mechanical effects; however, it resulted in mild edema. The higher dose elicited significant airway and tissue changes (smaller responses in survivors than in non-survivors), and severe edema. The strong correlation between lung tissue parameters and the degree of edema suggests that the OA-induced acute lung injury is manifested primarily in the alterations in parenchymal mechanics.

Microcirculatory dysfunction during intestinal ischemia-reperfusion

Oxido-reductive stress is a crucial factor of the tissue response during ischemia-reoxygenation injuries. Reperfusion affects primarily the microvasculature in a manner consistent with an acute inflammatory reaction. In this respect, the salient data suggest an important connection between endothelial cell-derived humoral mediators and the perivascular mast cell system. Increased endothelin-1 and decreased nitric oxide formation, mast cell degranulation and leukocyte accumulation coexist in gastrointestinal ischemia-reperfusion syndromes too. Constitutively produced nitric oxide inhibits, while increasingly formed endothelin-1 significantly enhances the degranulation of the intestinal mast cells. The endothelin-A receptor-dependent mast cell degranulation per se plays a secondary role in reperfusion-induced structural injury, but contributes significantly to leukocyte recruitment into the reperfused intestinal mucosa. It is conceivable therefore, that the nitric oxide--endothelin-1--mast cell cycle is involved in the mechanism of ischemia-reperfusion-induced endothelial cell-leukocyte interactions, where mast cells act to amplify the process of leukocyte sequestration. The alteration in the balance between endothelial cell-derived proadhesive vasoconstrictor and antiadhesive vasodilator factors exerts a significant influence on the mucosal integrity, and the antagonism of endothelin-A receptor activation in this setting tips the equilibrium toward tissue salvage.

The role of the glucocorticoid-dependent mechanism in the progression of sodium taurocholate-induced acute pancreatitis in the rat

The effects of glucocorticoids on acute pancreatitis (AP) have remained contradictory. The aim of this study was to investigate the time courses of the effects of the exogenous glucocorticoid agonists dexamethasone (DEX) and hydrocortisone (HYD) and a glucocorticoid antagonist (RU-38486) and to characterize the local and systemic responses in AP in rats. The glucocorticoid antagonist and agonists were administered just before AP induction. Serum amylase activity determinations, IL-6 bioassays, pancreatic weight/body weight ratio measurements, and survival analysis were performed. Liver and lung injuries were assessed via neutrophil leukocyte infiltration in myeloperoxidase (MPO) assays, tissue adenosine triphosphate (ATP) level determinations, and histology. In the glucocorticoid agonist groups, the survival rate increased, while the serum amylase level, the IL-6 activity, and the pancreatic weight/body weight ratio decreased significantly as compared with the control and RU-treated groups. AP resulted in significant decreases in tissue ATP levels in both the liver and the lung. In the DEX- or HYD-treated groups, the liver ATP levels were significantly elevated, while both the liver and the lung MPO levels were attenuated as compared with the AP and RU-treated groups. These results suggest that glucocorticoids may play important roles in mitigating the progression of the inflammatory reaction during the early phases of AP.

Microcirculatory changes in the canine oesophageal mucosa during experimental reflux oesophagitis: comparison of the effects of acid and bile

BACKGROUND

The response of the oesophageal microcirculation to luminal damaging agents may play an important role in reflux-induced mucosal injury. We characterized the microcirculatory consequences of exposure to bile with or without hydrochloric acid, and determined the changes in the constitutive nitric oxide synthase and inducible nitric oxide synthase activities in a canine model of acute reflux oesophagitis.

METHODS

Group 1 served as a saline-treated control, while groups 2-4 were exposed for 3 h to bile alone, to hydrochloric acid, or to bile + hydrochloric acid, respectively. The mucosal microcirculation was observed continuously by means of intravital videomicroscopy with an orthogonal polarization spectral imaging technique. Myeloperoxidase, constitutive and inducible nitric oxide synthase activities were measured via tissue biopsies, while the degree of mucosal damage was evaluated histologically.

RESULTS

Bile evoked deep tissue damage and leucocyte accumulation in the mucosa and muscle layer. The capillary red blood cell velocity and the relative vessel area increased significantly (P < 0.05). The constitutive NO synthase activity was decreased, and the inducible NO synthase activity was increased significantly. In the hydrochloric acid-treated group the functional capillary density decreased, the mucosal damage was less severe, the constitutive NO synthase activity did not change, whereas the inducible NO synthase activity was increased significantly. The constitutive NO synthase activity did not change after the bile + hydrochloric acid treatment either.

CONCLUSION

Reflux components induce characteristic microcirculatory alterations. The structural damage and leucocyte invasion are accompanied by bile-induced constitutive NO synthase inhibition when hydrochloric acid production is suppressed.

Kupffer cell phagocytosis blockade decreases morbidity in endotoxemic rats with obstructive jaundice

OBJECTIVE AND DESIGN

The consequences of Kupffer cell phagocytosis blockade were studied in endotoxemic rats with obstructive jaundice.

MATERIAL OR SUBJECTS

159 male Wistar rats.

TREATMENT

Obstructive jaundice was induced by bile duct ligation (BDL). Gadolinium chloride (1 mg/100 g iv) was given 6 days after BDL to inhibit Kupffer cell activity and the animals were challenged with 1 microg/g endotoxin 24 h later.

METHODS

Endotoxin sensitivity, tumor necrosis factor-alpha and interleukin-6 production were studied, liver and lung injury were assessed by neutrophil infiltration assay, tissue adenosine triphosphate, aspartate aminotransferase, alanine aminotransferase level determinations and histology, respectively. For statistics non-parametric methods were used.

RESULTS

BDL sensitized the animals to endotoxin, increased endotoxin-induced tumor necrosis factor-alpha and interleukin-6 production and reduced ATP contents of the liver and the lung. Kupffer cell blockade significantly increased the resistance against endotoxin, diminished the inflammatory cytokine release and reduced endotoxin-induced tissue injury in BDL animals.

CONCLUSION

Attenuation of Kupffer cell function decreases endotoxin-induced lethality and morbidity in obstructive jaundice.

[Use of crystal conversion reactions in the synthesis of pentacyclic alkaloid analogues]

During investigation of substitution of debenzorutaecarpine derivatives thermal cyclization reactions was observed to produce new fused heterocyclic systems. The optimal temperature of cyclizations was determined by differential calorimetric measurements of crystals of intermediate products. The thermolysis of 2-azido-3-formil-debenzorutaecarpine gave, after elimination nitrogen, izooxazolo-debenzorutaecarpine in good yield. The cyclization of the 2-azido-3-nitroso-debenzorutaecarpine readily led to oxadiazolo E-ring analogue of rutaecarpine. The thermal cyclization of 2-hydroxy-debenzorutaecarpines gave 2-oxo- and 4-oxo-pyrano E-ring analogues of rutaecarpine. The structure of substances was confirmed by spectroscopic methods. The synthesised compounds are considered as first representatives of new heterocyclic ring systems.

Betaine-palmitate reduces acetylsalicylic acid-induced gastric damage in rats

BACKGROUND

Acetylsalicylic acid (ASA)-induced gastric injury is reduced when ASA is administered along with phosphatidylcholine. The hydrolysis of endogenous phosphatidylcholine leads to the production of betaine, which may participate in the maintenance of cellular homeostasis. The present aims were to investigate the effects of exogenous betaine and its palmitic acid complex (betaine-palmitate) in the protection of the gastric mucosa in ASA-induced subacute damage.

METHODS

Repeated doses of ASA were given intragastrically to male Wistar rats. Control rats were given vehicle only, while treated animals were challenged with ASA or with ASA along with betaine, palmitic acid or betaine-palmitate. The gastric mucosa was examined after 3 days and the nature of any microscopic mucosal injury was assessed by histology. The extent of macroscopic damage, changes in permeability (assessed by Evans blue method) and tissue ATP concentrations were determined in separate series.

RESULTS

ASA induced a significant fall in the ATP content of the mucosa, which was not affected by the other drugs used in the study. However, the ASA-induced mucosal permeability increase could be completely reversed by betaine-palmitate supplementation. The extent of severity of the macroscopic and microscopic lesions was 33% and 2.45, respectively, for ASA, as compared with 15% and 2.2 for betaine, 14% and 1.9 for palmitic acid and 3% and 1.4 for betaine-palmitate.

CONCLUSIONS

Betaine-palmitate affords a significant protective effect against ASA-induced injury, without influencing the ATP synthesis, and this suggests that the defence is due to its ability to prevent secondary damage.

[Methods for in vivo investigation of human microcirculation]

Microcirculatory disorders play a major role in the development of organ failure in a variety of conditions. Perfusion changes may be visualized by static and dynamic methods, with direct and indirect techniques. Orthogonal polarization spectral imaging is a novel method of imaging the human microcirculation. The technique employs reflected light without fluorescent dyes and allows clinical assessment of the dynamic of the microvascular network of internal solid organs. Principles of the technique and indications of use are briefly discussed.

Electrophilic methyl groups present in the diet ameliorate pathological states induced by reductive and oxidative stress: a hypothesis

Reductive stress, characterised by an increased NADH:NAD+ ratio, may be as common and as important a consequence of redox imbalance as oxidative stress. It may also be an important predisposing cause of the generation of reactive oxygen species. Considerable experimental and indirect clinical evidence suggests that protection against reductive stress depends on biomolecules with electrophilic methyl groups (EMG) such as S-adenosylmethionine, betaine, carnitine and phosphatidylcholine. Pathological processes leading to reductive stress and their relief by such protective agents is reviewed and the proposed molecular mechanism is outlined. These and other EMG-containing biomolecules are part of the daily diet and may represent an important control system for redox balance.

Endothelin-1-induced airway and parenchymal mechanical responses in guinea-pigs: the roles of ETA and ETB receptors

Endothelin-1 (ET-1) has been shown to have a constrictor effect on the airways and parenchyma; however, the roles of the ETA and ETB receptors in the ET-1-induced changes in the airway and tissue compartments have not been fully explored. Low-frequency pulmonary impedance (ZL) was measured in anaesthetized, paralysed, open-chest guinea-pigs. ZL spectra were fitted by a model to estimate airway resistance (Raw) and inertance (Iaw), and coefficients of tissue damping (G) and elastance (H), and hysteresivity (eta = G/H). Two successive doses of ET-1 (0.05 and 0.2 nmol x kg(-1)) each evoked significant dose-related increases in Raw, G, H and eta. Pretreatment with 20 nmol x kg(-1) BQ-610 (a highly selective ETA receptor antagonist) resulted in a significantly decreased elevation only in H after the lower dose of ET-1. However, all parameters changed significantly less on the administration of ET-1 after pretreatment with 80 nmol-kg(-1) BQ-610, with 20 nmol x kg(-1) ETR-P1/fl (a novel ETA receptor antagonist) or with 20 nmol x kg(-1) IRL 1038 (an ETB receptor antagonist). The results of the separate assessments of the airway and tissue mechanics demonstrate that endothelin-1 induces airway and parenchymal constriction via stimulation of both receptor types in both compartments.

Bile-induced adenosine triphosphate depletion and mucosal damage during reflux esophagitis

BACKGROUND

This study was designed to investigate the role of bile in a large animal model of acute esophageal reflux disease.

METHODS

An agar electrode was used to measure the transmucosal potential difference of the esophagus in anaesthetized dogs. The vascular permeability index and the epithelial permeability index of the mucosa were evaluated by means of the Evans blue and the sodium-fluorescein clearance method, respectively. The tissue adenosine triphosphate (ATP) level and the myeloperoxidase activity were determined from tissue biopsies, while the degree of mucosal damage was evaluated histologically on a grade 0-100 scale. Group 1 (n = 8) served as saline-treated control; groups 2 (n = 8), 3 (n = 5) and 4 (n = 5) were exposed for 4 h to canine bile alone, to hydrochloric acid + bile, or to hydrochloric acid alone, respectively.

RESULTS

In Groups 2, 3 and 4 the degree of mucosal damage was significantly increased, and a 4-fold elevation in myeloperoxidase activity was observed. The transmucosal potential difference was decreased significantly below the control level, while the vascular and epithelial permeability indices were significantly increased compared with the control values. Bile, but not hydrochloric acid, evoked a significant (40%) decrease in the ATP level of the esophageal tissue.

CONCLUSIONS

We propose that mucosal dysfunction, structural damage and leukocyte invasion during hydrochloric acid-induced esophageal injury are exacerbated by bile-induced changes in tissue ATP concentrations during experimental esophageal reflux disease.

Intravital microscopic assessment of pressure induced microcirculatory changes after enterocystoplasty in rats

PURPOSE

Chronic over distention may lead to enterocystoplasty rupture. It is hypothesized that pressure induced microvascular derangement and subsequent ischemia of the enterocystoplasty intestinal patch may have a role in this process. We describe distention induced microcirculatory alterations in a chronic rat model of enterocystoplasty using intravital video microscopy.

MATERIALS AND METHODS

Microcirculation in the muscle layer of the intact bladder and intestine, and in the enterocystoplasty 90 days after surgery were examined at greater and less than urethral sphincter closure pressure. Microcirculatory changes were recorded during stepwise increments of intraluminal pressure up to 80 mm. Hg or when 20 mm. Hg was continuously maintained for 60 minutes.

RESULTS

The enterocystoplasty components of intestine and bladder displayed baseline microcirculatory characteristics similar to those observed in the intact organs. As evidenced by microcirculatory flow and functional capillary density measurements in the intact intestine and the ileal portion of enterocystoplasty, intraluminal pressure elevation to greater than 25 or 30 mm. Hg significantly compromised capillary perfusion by approximately 50% and 75%, respectively. Lower intraluminal pressure did not cause microcirculatory disturbance even when maintained for a longer period. In the intact bladder and bladder portion of enterocystoplasty only pressure increases to greater than 80 mm. Hg affected tissue perfusion.

CONCLUSIONS

Intravital microscopy in the augmented rat bladder is a sensitive and suitable means of assessing clinically relevant microcirculatory changes. These experiments demonstrate the significance of distention induced microcirculatory impairment in the intact bowel and the intestinal site of enterocystoplasty even at less than urethral closure pressure.

[The role of nitric oxide synthase, and of granulocytes, in endotoxin-induced early myocardial depression]

The aim of our study was to investigate the role of endothelial and inducible nitric oxide synthase (eNOS and iNOS) and granulocytes during hyperdynamic endotoxemia, and to study the cardiovascular effects of the non-selective NOS-inhibitor N-omega-nitro L-arginine methylester (L-NAME) and the selective iNOS-inhibitor mercaptoethylguanidine (MEG) in the early myocardial depression.

METHODS

Endotoxemia was induced in anesthetized dogs. Mean arterial pressure, cardiac output and peripheral vascular resistance was monitored, left ventricular contractility was calculated. Myocardial eNOS and iNOS activities and myeloperoxidase (MPO) activity, as the marker of granulocyte infiltration were determined from tissue biopsy samples.

RESULTS

Endotoxemia was accompanied by a short hyperdynamic circulatory reaction, hypotension and myocardial depression. We observed an early increase in eNOS and a late increase in iNOS activity. MPO activity increased significantly after 8 hr endotoxemia, suggesting considerable granulocyte-extravasation. Non-selective NOS-inhibition prevented hypotension, exerted positive inotropic effect, but induced a rise in peripheral vascular resistance and a further increase in myocardial MPO activity. MEG treatment stabilized myocardial contractility on the control level, increased cardiac output and attenuated tissue granulocyte infiltration.

CONCLUSIONS

The increased activity of eNOS and granulocyte infiltration may be responsible for the early cardiac depression during endotoxemia. Non-selective NOS-inhibition has beneficial effects, but is also induces side-effects by disturbing vasoregulation. Selective iNOS-inhibition has no significant hemodynamic effects during early endotoxemia, but restores cardiac efficacy probably through attenuating granulocyte-associated myocardial dysfunction.

Endothelin-1 induces mucosal mast cell degranulation in the rat small intestine

The enhanced production of endothelial cell-derived vasoactive mediators and the activation of mast cells (MCs) have been implicated in the pathogenesis of mucosal damage during ischemia and reperfusion injuries. The first objective of our study was to define the in vivo relation between endothelin-1 (ET-1) and the MC system. Secondly, we determined whether pretreatment with ET receptor antagonists would attenuate MC responses to exogenous ET-1. In the first series of experiments, increasing doses of ET-1 (0. 1, 1 and 3 nmol/kg i.v.) were administered to anesthetized rats. In the second series, the animals were pretreated with equimolar doses of the ET-A receptor antagonist BQ-610 or ETR-P1/fl peptide, and the ET-B receptor antagonist IRL-1038. Intestinal perfusion changes and macrohemodynamics were recorded, and the proportion of degranulated MCs was determined in ileal biopsies. The average mucosal thickness was recorded with an image analysis system. ET-1 induced dose-dependent alterations in the hemodynamic and morphological parameters and caused pronounced mucosal injury, with a significant reduction in villus height. The ratio of degranulated MCs was similar in all ET-treated groups (77%, 82% and 86%) to that observed in animals subjected to 15-min ischemia and 60-min reperfusion (85% degranulation). Pretreatment with BQ-610 and ETR-P1/fl peptide attenuated the ET-1 induced alterations in the hemodynamic parameters and decreased structural injury to the mucosa. ET-induced MC degranulation was significantly inhibited by the ET-A receptor antagonists, but not by IRL-1038. These results indicate that elevated levels of circulating ET-1 might induce intestinal mucosal tissue injury and MC degranulation via activation of ET-A receptors, and raise the possibility that ET-A receptor antagonist administration could exert a potentially beneficial effect through a mechanism other than the blockade of vasoconstriction in pathologies associated with an increased ET-1 release.

Prevention of early myocardial depression in hyperdynamic endotoxemia in dogs

In our study the pathomechanism of sepsis-induced early myocardial depression was investigated. We determined the effects of the inducible nitric oxide synthase inhibitor and free radical scavenger mercaptoethylguanidine (MEG) on the myocardial contractility, the endothelial and inducible nitric oxide synthase (eNOS and iNOS) activities, and the activation and tissue accumulation of polymorphonuclear leukocytes in hyperdynamic endotoxemia in dogs. Group 1 served as endotoxemic control. Mean arterial pressure and cardiac output were measured, myocardial contractility was estimated from the end-systolic pressure-diameter relationship. The eNOS, iNOS and myeloperoxidase activities were determined on myocardial biopsy samples, and the free radical-producing capacity of granulocytes was measured from separated cells. The effect of MEG on the in vitro free radical production of isolated granulocytes was measured by chemiluminometry. Endotoxin induced a hyperdynamic circulatory reaction and significant myocardial depression. The myocardial eNOS activity was significantly increased 4 h after induction of endotoxemia and remained elevated, the iNOS activity was increased only 8 h after endotoxemia induction. The free radical-producing capacity and the myocardial accumulation of the granulocytes were significantly increased. In group 2, MEG treatment selectively inhibited the iNOS activity, prolonged the hyperdynamic circulatory reaction, prevented myocardial depression and decreased the activation and tissue accumulation of granulocytes. The compound dose-dependently decreased the in vitro activation of previously resting granulocytes. Our study demonstrates that iNOS do not contribute to the early cardiac failure in endotoxemia. MEG selectively inhibits iNOS in vivo, but its beneficial effects are rather related to the decreases in leukocyte and free radical-mediated myocardial dysfunction during early endotoxemia.

Endothelin-A receptor antagonism improves small bowel graft perfusion and structure after ischemia and reperfusion

BACKGROUND

We hypothesized that endothelin-A (ET-A) receptor activation plays a central role in intestinal ischemia-reperfusion-induced hemodynamic changes and may trigger the process of mucosal barrier destruction. Our aims were to investigate and compare the effects of systemic and intragraft ET-A receptor antagonist therapy during the early revascularization phase of small bowel transplants.

METHODS

In Groups 1, 2, and 3 orthotopic small bowel autotransplants were performed in anesthetized dogs. Group 4 served as sham-operated control. Group 2 was treated i.v. with the ET-A receptor antagonist ETR-p1/fl peptide at the onset of reperfusion. In Group 3, intragraft infusion of the ETR-p1/fl peptide was applied during cold ischemia. The mucosal myeloperoxidase activity and the free radical-producing capacity of the granulocytes passing the intestinal graft were determined, and the systemic hemodynamic features were recorded. The extent of the mucosal injury was determined from tissue biopsies taken after 4 hr of reperfusion.

RESULTS

Reperfusion progressively decreased the mesenteric blood flow, increased the mesenteric vascular resistance, and enhanced the accumulation and free radical production capacity of the leukocytes. These changes were significantly inhibited in Group 2 with systemic (i.v.) administration of the ET-A receptor antagonist. The local, intragraft treatment improved the mesenteric hemodynamic changes and decreased the accumulation but not the activation of the circulating leukocytes. The structural injury of the graft was prevented in both treated groups.

CONCLUSIONS

Endothelins are involved in the hemodynamic events leading to structural injury of the intestinal graft after ischemia-reperfusion. The antagonism of intestinal ET-A receptors by a combination of local and systemic drug delivery offers a rational treatment modality in these conditions.

Effects of selective nitric oxide synthase inhibition in hyperdynamic endotoxemia in dogs

OBJECTIVES

Our aims were to investigate the systemic hemodynamic effects of constitutive endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS) inhibitors in hyperdynamic endotoxemia.

PATIENTS AND METHODS

Group 1 comprised sham-operated controls, while in group 2, 3 and 4, a hyperdynamic circulatory reaction was elicited by a 2-hour infusion of Escherichia coli endotoxin (ETX) in a dose of 5.3 microg/kg. The animals in group 3 were treated with 12. 5 mg/kg nonselective NOS inhibitor N-omega-nitro-L-arginine methyl ester (L-NAME), and those in group 4 with 2 mg/kg of the specific iNOS inhibitor S-methyl-isothiourea (SMT). Mean arterial pressure (MAP), cardiac output (CO) and myocardial contractility (MC) were measured, and total peripheral resistance (TPR) was calculated. The eNOS and iNOS activities were determined in myocardial biopsy samples taken after 8 h of endotoxemia.

RESULTS

ETX induced significant decreases in TPR and MAP, a transient myocardial depression, and increased the myocardial eNOS and iNOS activities. L-NAME decreased the activities of both isoenzymes, increased MC but induced a fall in CO. SMT inhibited iNOS by 60%, without influencing the eNOS activity, increased MAP and contractility in the early phase of endotoxemia, and induced only a slight decrease in CO.

CONCLUSIONS

Nonselective NOS inhibition restores the arterial pressure and exerts a positive inotropic effect, but decreases CO. SMT selectively decreases the iNOS activation without disturbing the vasoregulatory function of the eNOS-derived nitric oxide in hyperdynamic endotoxemia in the dog.

Mast cell degranulation prior to ischemia decreases ischemia-reperfusion injury in the canine small intestine

OBJECTIVE

To determine the impact of previous mast cell degranulation on intestinal ischemia-reperfusion-induced mucosal damaged.

MATERIALS

The hemodynamic and morphological consequences of complete arterial occlusion were evaluated in anesthetized dogs. The mast cell degranulator Cremophor-E1 (n = 5) and Compound 48/80 (n = 5) were used to investigate the involvement of gastrointestinal mast cells in ischemia-reperfusion-induced tissue reactions. Seven dogs subjected to complete segmental arterial occlusion served as controls. Intestinal biopsies taken at the end of 120-min ischemia and after 120 min of reperfusion were evaluated histologically.

METHODS

The number of mast cells was determined and the degree of mucosal damage was evaluated according to the 5 grade Chiu scale. Mucosal histidine decarboxylase activity was measured in tissue samples and the rate of release of histamine was determined from the venous effluent of the ileal segment.

RESULTS

In the control group, 120-min reperfusion significantly increased the plasma histamine level, and induced a severe tissue injury. In the compound 48/80 and Cremophor-E1-pretreated groups, the reduction in the baseline number of mast cells in the villi was 37% and 53%, respectively, and the ischemia-reperfusion-induced release of histamine was significantly decreased. In these groups, the basal mucosal histidine decarboxylase activity was significantly increased and the degree of damage of the intestinal mucosa was significantly reduced.

CONCLUSION

It is proposed that mast cell degranulation prior to ischemia may induce a potentially protective mechanism in the small bowel mucosa and decreases ischemia-reperfusion injury in the dog.

The role of mast cell degranulation in ischaemia-reperfusion-induced mucosal injury in the small intestine

The role of the intestinal mast cell system in the pathophysiology of postischaemic mucosal lesions is not understood. The present goals were to investigate the contributions of mast cells and mast cell-derived vasoactive mediators to mucosal injury caused by arterial occlusion. We evaluated the intestinal ischaemia-reperfusion-induced local morphological changes in mast cell-depleted anesthetized dogs. Animals subjected to complete segmental intestinal ischaemia and reperfusion served as controls. The selective mucosal-type mast cell degranulator Cremophor-El and the nonselective mast cell depleter Compound 48/80 were used to investigate the involvement of mast cells in reperfusion-induced tissue reactions. Ileal biopsies taken at the end of 120 min of ischaemia and after 120 min of reperfusion were evaluated histologically. The number of mast cells was determined and the degree of mucosal damage was evaluated according to the 0 to 5-grade Chiu scale. Mucosal histidine decarboxylase activity was measured in tissue biopsies and the rate of release of histamine was determined from the venous effluent of the segment. In the control group, 120 min reperfusion induced a severe tissue injury. In the Compound 48/80 and Cremophor-El-pretreated groups, the reduction in the baseline number of mast cells was 37% and 53%, respectively, and the basal mucosal histidine decarboxylase activity was significantly increased. In these groups, the ischaemia-reperfusion-induced release of histamine was significantly decreased, and the degree of damage of the intestinal mucosa was significantly reduced. Mucosal mast cell degranulation plays an important role in the initiation of tissue injury after intestinal ischaemia-reperfusion. Depletion of mast cells prior to ischaemia decreases the severity of mucosal damage, probably in consequence of the stimulation of mucosal histidine decarboxylase activity.