Detection of colonic cells in peripheral blood of colorectal cancer patients by means of reverse transcriptase and polymerase chain reaction

Circulating tumour cells play a central role in the metastatic process, but little is known about the relationship between this cellular subpopulation and the development of secondary disease. This study was aimed at assessing the presence of colonic cells in peripheral blood of patients with colorectal cancer in different evolutionary stages, by means of reverse transcriptase polymerase chain reaction (RT-PCR) targeted to carcinoembryonic antigen (CEA) mRNA. In vitro sensitivity was established in a recovery experiment by preparing serial colorectal cancer cell dilutions. Thereafter, 95 colorectal cancer patients and a control group including healthy subjects (n=11), patients with other gastrointestinal neoplasms (n=11) or inflammatory bowel disease (n=9) were analysed. Specific cDNA primers for CEA transcripts were used to apply RT-PCR to peripheral blood samples. Tumour cells were detected down to five cells per 10 ml blood, thus indicating a sensitivity limit of approximately one tumour cell per 10(7) white blood cells. CEA mRNA expression was detected in 39 out of 95 colorectal cancer patients (41.1%), there being a significant correlation with the presence of distant metastases at inclusion. None of the healthy volunteers and only 1 of 11 patients (9.1%) with other gastrointestinal neoplasms had detectable CEA mRNA in peripheral blood. By contrast, CEA mRNA was detected in five of the nine patients (55.6%) with inflammatory bowel disease. These results confirm that it is feasible to amplify CEA mRNA in the peripheral blood, its presence being almost certainly derived from circulating malignant cells in colorectal cancer patients. However, CEA mRNA detectable in blood of patients with inflammatory bowel disease suggests the presence of circulating non-neoplastic colonic epithelial cells.

Effects of increasing blood hemoglobin levels on systemic hemodynamics of acutely anemic cirrhotic patients

BACKGROUND/AIMS

In experimental portal hypertension, blood hemoglobin levels have been shown to influence the hyperdynamic circulatory state. The aim of this study was to assess the hemodynamic effects of increasing hemoglobin concentration in human portal hypertension.

METHODS

Sixteen cirrhotic patients recovering from a variceal bleeding episode were randomly assigned to receive two units of packed red cells or 500 ml of a protein solution. Systemic and portal hemodynamics, and rheological and hormonal parameters were measured at baseline and after expansion.

RESULTS

Both groups were similar with respect to the degree of liver failure, severity of the bleeding episode, activation of the endogenous vasopressor systems, and hemodynamic parameters. The administration of either erythrocytes or a protein solution prompted a similar increase in total blood volume and suppression of vasopressor systems. Both groups of patients experienced similar increases in wedged hepatic venous pressure. Hepatic venous pressure gradient was not significantly modified but tended to increase in erythrocyte-transfused patients. Cardiopulmonary pressures increased, but this increment was significant in the non-blood-transfused patients only. Cardiac output decreased in erythrocyte-transfused patients, while it increased in the group receiving a protein solution. Red blood cell transfusion resulted in an increase in systemic vascular hindrance (resistance/blood viscosity), whereas the administration of a protein solution prompted a decrease in this parameter, thus reflecting true vasoconstriction and vasodilation, respectively.

CONCLUSIONS

An increase in blood hemoglobin in acutely anemic cirrhotic patients attenuates their hyperdynamic circulation beyond viscosity-dependent changes, an effect which might be counteracted by the effects on portal venous pressure gradient.

Biopsy forceps disinfection technique does not influence Helicobacter pylori culture

OBJECTIVES

Culturing Helicobacter pylori (Hp) has a low sensitivity rate, and is affected by factors such as the number of biopsies, transport, and culture conditions. Hp detection is also influenced by omeprazole, antibiotics, bismuth salts, or benzocaine use. Disinfection procedures based on glutaraldehyde are highly effective in eliminating any Hp contamination of endoscopic equipment. However, the possibility that some residual glutaraldehyde present in biopsy forceps after decontamination could affect Hp viability has not yet been investigated.

METHODS

Antral specimens from 25 patients with active gastric or duodenal ulcer obtained with three forceps (sterilized with ethylene oxide, glutaraldehyde, or glutaraldehyde-phenolate) were streaked on appropriate media, and results of culture evaluated.

RESULTS

Helicobacter pylori was isolated in 17 patients. Positivity of culture was independent of the way the forceps were sterilized, and the number of colonies (mean +/- SD) was similar for the three types of forceps (475 +/- 312, 533 +/- 242, and 550 +/- 225 colony-forming units [CFUs] for ethylene oxide, glutaraldehyde, and glutaraldehyde-phenolate, respectively). Moreover, the incubation time since isolation was also similar (6.0 +/- 1.3, 5.8 +/- 1.2, and 5.7 +/- 1.2 days for ethylene oxide, glutaraldehyde, and glutaraldehyde-phenolate disinfected forceps, respectively).

CONCLUSION

The use of glutaraldehyde to sterilize biopsy forceps is not responsible for the false-negative results of Hp culture.

Port site metastases and recurrence after laparoscopic colectomy. A randomized trial

BACKGROUND

This study was performed to prospectively assess the impact of the laparoscopic approach to the patterns of port site metastases (PSM) and recurrence rate (RR) of resected colon carcinomas as compared with conventional colectomies.

METHODS

All patients were included in a prospective randomized trial comparing laparoscopic-assisted colectomy (LAC) versus open colectomy (OC) for colon cancer. The randomization was stratified for localization of the lesion. Patients with metastasic disease at time of the surgery were excluded. Follow-up in the outpatient clinic was done every 3 months for a minimum of 12 months. Endpoints for the study were metastasis at port site and laparotomy incision as well as recurrence rate.

RESULTS

Of 91 segmental colectomies performed from November 1993 to January 1996, there were 44 LAC and 47 OC. Patient data were similar in both groups (age, sex, Dukes stage, type of operation). Mean follow-up was 21.4 months, with a range of 13 to 41 months. There were no wounds or PSM in those series. RR was similar for both groups. For LAC, it was five of 31 (16.1%); for OC, it was six of 40 (15%).

CONCLUSIONS

The laparoscopic approach has a recurrence rate similar to that for open procedures for colon cancer. However, additional follow-up of these patients is needed before we can determine whether or not the laparoscopic approach influences overall survival.

Effects of steroid treatment on activation of nuclear factor kappaB in patients with inflammatory bowel disease

Nuclear factor kappB (NFkappaB) is a transcription factor that controls several genes important for immunity and inflammation. The aim of this study was to assess if activation of NFkappaB plays a role in the pathogenesis of inflammatory bowel disease (IBD), and whether steroid treatment affects NFkappaB activation. Activation of NFkappaB was analysed in colon biopsy samples of 13 patients with active IBD (8 Crohn's colitis, 5 ulcerative colitis) by electrophoretic mobility-shift assays, under basal conditions and 3 weeks after treatment with 0.75 mg kg(-1) day(-1) prednisolone. The presence of interleukin-8 mRNA in biopsies was assessed by RT-PCR. A specific NFkappaB band was present in all nuclear extracts from inflamed mucosa, whereas the band was barely detectable in uninflamed colonic mucosa. NFkappaB bands were super-shifted by antibodies against p50 subunit, whereas antibodies against p65, p52, c-Rel, or Rel B did not modify the mobility of the band. Increased interleukin-8 mRNA was detected at the same sites of NFkappaB activation. Steroid-induced healing of colonic inflammation was associated with disappearance of NFkappaB from nuclear extracts. These results support the notion that NFkappaB plays an important role in the pathogenesis of IBD, and that blockade of NFkappaB activation is one of the mechanisms by which steroids suppress the inflammatory cascade in IBD.

Value of postoperative surveillance after radical surgery for colorectal cancer: results of a cohort study

PURPOSE

Early detection of recurrence after curative resection for primary colorectal cancer should improve patients' prognosis. However, the usefulness of postoperative surveillance programs has not been clarified yet. The present cohort study was aimed at assessing the effectiveness of systematic follow-up in patients with colorectal cancer who were operated on for cure, regarding both rate of tumor recurrence amenable to curative-intent surgery and rate of survival.

METHODS

One hundred ninety-nine colorectal cancer patients who underwent radical primary surgery were followed according a well-defined postoperative surveillance program, which consisted of laboratory studies (including serum carcinoembryonic antigen assay) every three months, physical examination and abdominal ultrasound or computed tomography every six months, and chest radiograph and total colonoscopy once per year. Cohorts were defined according to patients' compliance with the proposed follow-up program. A multivariate regression model was constructed to predict survival.

RESULTS

One hundred forty patients were considered to be compliant with the surveillance program, whereas the remaining 59 patients occasionally attended follow-up investigations or did not comply at all. Although there were no differences in the overall recurrence rate (38 vs. 41 percent; P = 0.52), curative-intent reoperation was possible in 18 patients (34 percent) of those with tumor recurrence in the compliant cohort but in only 3 patients (12 percent) in the noncompliant cohort (P = 0.05). Similarly, the probability of survival was higher in the compliant cohort, both regarding overall (63 vs. 37 percent at 5 years; P < 0.001) and cancer-related (69 vs. 49 percent at 5 years; P < 0.02) rates. Cox regression analysis disclosed that only a more advanced TNM stage (odds ratio, 8.17; 95 percent confidence interval, 1.13-59.29) and noncompliance with the postoperative surveillance program (odds ratio, 2.32; 95 percent confidence interval, 1.50-3.60) had an independent negative impact on survival.

CONCLUSION

Systematic postoperative surveillance in patients with colorectal cancer who were operated on for cure increases both the rate of tumor recurrence amenable to curative-intent surgery and rate of survival.

Gastric intramucosal acidosis in mechanically ventilated patients: role of mucosal blood flow

OBJECTIVE

To investigate whether gastric intramucosal acidosis is associated with a decreased gastric mucosal blood flow in mechanically ventilated patients.

DESIGN

Prospective, clinical investigation.

SETTING

University hospital intensive care unit.

PATIENTS

Seventeen mechanically ventilated patients with stable hemodynamic status.

INTERVENTIONS

Gastric tonometry and endoscopic assessment of mucosal blood flow.

MEASUREMENTS AND MAIN RESULTS

Six patients had gastric intramucosal acidosis (intramucosal pH [pHi] of 7.24 +/- 0.06), whereas the remaining 11 patients had pHi values within the normal range (7.44 +/- 0.01). No differences were found between intramucosal acidotic and nonacidotic patients with respect to their general and hemodynamic characteristics. Patients with intramucosal acidosis had a lower gastric mucosal blood flow, as assessed by laser-Doppler flowmetry, than nonacidotic patients (1.4 +/- 0.1 vs. 2.1 +/- 0.2 volts, respectively; p < .05). Reflectance spectrophotometry disclosed that patients with low gastric pHi had also a significantly (p < .05) lower hemoglobin content index (61 +/- 4 arbitrary units) than patients with normal pHi (81 +/- 3 arbitrary units), whereas oxygen saturation index was similar for both groups.

CONCLUSION

Our results support the hypothesis that gastric mucosal hypoperfusion underlies the development of intramucosal acidosis in mechanically ventilated patients.

[Endoscopic ultrasonography in the staging of esophageal cancer. Therapeutic implications]

Endoscopic ultrasonography (EUS) provides accurate visualization of the different layers of the gastrointestinal wall and surrounding structures, allowing TN staging of tumors prior surgery. The aim of this study was to evaluate the sensitivity, specificity and accuracy of EUS in the staging of esophageal carcinoma as well as its applicability and usefulness in tumors with nontraversable stenoses. EUS was performed in 43 patients with esophageal carcinoma. The technique was carried out with a radial echoendoscope under sedation with i.v. midazolam. Both, the infiltration of the tumor through the layers of the esophageal wall (T staging) and the presence of lymph nodes in different areas (N and M staging) were determined. In cases with nontraversable stenoses, only the proximal tumor margin was assessed by means of EUS. EUS showed T1 stage in only one case and more advanced stages in the remaining patients: T2 (n = 12), T3 (n = 22) and T4 (n = 4). We know the outcome of 28 patients, 14 of whom underwent surgery. In these patients, the sensitivity for T and N staging was 86% and 92% respectively, and the accuracy 86% in both. Both, T and N, were overstaged in one case (7%) and understaged in another (7%). The tumor caused nontraversable stenoses in 59% of patients (n = 26). In 4 patients the staging could not be assessed with sufficient reliability. In the subgroup of patients with nontraversable stenoses who underwent surgery, the accuracy of EUS when comparing with histopathology was 80%. Endoscopic ultrasonography has a high sensitivity and accuracy in the staging of esophageal tumors even in cases with nontraversable stenoses.

[Chronic enteropathy of unknown etiology in patients with AIDS. An analysis of 40 cases]

BACKGROUND

Data about the etiology of chronic enteropathy in AIDS patients are scarce and are very dependent upon the geographical area. The aim of this study was to detect microorganisms potentially associated with chronic enteropathy in AIDS patients with diarrhoea for more than one month, and initial negative routine stool bacterial cultures and examinations for ova and parasites. The degrees of associated intestinal malabsorption and immunodeficiency were also analysed.

PATIENTS AND METHODS

Forty consecutive patients were recruited from January 1993 to December 1994. The following studies were performed: Intestinal absorption tests (d-xylose and 14C-triolein), CD4/CD8 cell counts, microbiological studies (standard stool cultures for detection of bacteria and examinations for ova and parasites including the detection of Enterocitozoon bieneusi spores by the Weber's stain), upper gastrointestinal endoscopy or colonoscopy with intestinal biopsies and blood cultures for CMV and mycobacteria.

RESULTS

The median duration of diarrhoea was 4 months and the mean weight loss was 8.4 kg. Ninety percent of patients had less than 0.1 x 10(9) CD4+ cells/l, with a mean CD4+ cell count of 0.035 x 10(9)/l. Malabsorption was found in 84% of patients. An etiological diagnosis of chronic enteropathy was reached in 60% of the patients. The yield of pathological examination was 37% and the microbiological test using samples of faeces and blood were positive in 45% and 20% of cases respectively. The most frequently identified microorganisms were CMV (10 cases), E. bieneusi (9), enterobacteria (8), Cryptosporidium parvum (5), Leishmania donovani (2). Patients with enteropathy caused by E. bieneusi had lower count of CD4 cells (p = 0.005) and with higher serum levels of alkaline phosphatase (p = 0.02) than patients with CMV enteropathy.

CONCLUSIONS

Stool Weber's stain and CMV and mycobacterial blood cultures should be added to the standard work-up diagnosis in patients with chronic diarrhoea and a CD4+cells count below 0.1 x 10(9) l. Upper and/or lower gastrointestinal endoscopies with intestinal biopsies should be performed only in patients with persistent diarrhea without microbiological diagnosis or a lack of response to treatment.

Gastric mucosal blood flow regulation in response to different stimuli

We compared changes in gastric mucosal blood flow (GMBF) and left gastric artery blood flow (LGABF) in response to pharmacological, physiological, and pathological stimuli. GMBF and LGABF were measured by the hydrogen gas clearance and perivascular ultrasonic transit time techniques, respectively, under baseline conditions and following intravenous infusion of vasopressin or pentagastrin, isovolemic hemodilution, or gastric perfusion with HCl-taurocholate. Blood flow changes following vasopressin or hemodilution were significantly larger in the left gastric artery than in the gastric mucosa. In contrast, the increment in blood flow associated with pentagastrin-stimulated acid secretion was significantly greater in the gastric mucosa than in the extramural artery. Barrier disruption with acid-taurocholate induced similar changes in both measurement sites. The gastric hyperemia induced by either mechanism was significantly attenuated by blockade of NO synthesis. These data demonstrate that although functional changes in GMBF are primarily supported by changes in blood flow at the extramural gastric arteries, the gastric mucosal microvasculature is also under the influence of independent local control mechanisms.

Platelet activation In mice and human Helicobacter pylori infection

Extracts of Helicobacter pylori (HP) have been shown to induce leukocyte adhesion in mesenteric venules, but the effects of HP infection on gastric microvessels are unknown. Inflammatory cell interactions in the gastric microcirculation were studied by intravital videomicroscopy in mice inoculated with either saline or fresh isolates of HP. Platelet aggregates were detected and quantified in murine portal blood, while endothelial P-selectin expression was determined using the dual radiolabeled mAb technique. Platelet activation and aggregation were studied in HP-infected patients and controls by measuring the platelet-aggregate ratio and platelet P-selectin expression. HP infection induced a marked increase in the flux of rolling leukocytes and the appearance of platelet and leukocyte- platelet aggregates in murine gastric venules. The HP-induced rolling and platelet aggregate formation was abrogated by mAbs against L- or P-, but not E- selectin. Endothelial cell expression of P-selectin was not altered, but platelet P-selectin expression was enhanced in HP-infected mice. Circulating platelet aggregates and activated platelets were also detected in HP-infected patients. These findings indicate that platelet activation and aggregation contribute to the microvascular dysfunction and inflammatory cell recruitment associated with HP infections.

Anemia worsens hyperdynamic circulation of patients with cirrhosis and portal hypertension

This retrospective cohort study was aimed at investigating the effects of anemia on the hemodynamic disturbances associated with portal hypertension. In all, 202 consecutive nontreated portal-hypertensive patients referred for evaluation to our Hepatic Hemodynamic Laboratory were included. Compared to the nonanemic patients, anemic cirrhotic patients had an increased cardiac output (7.9 +/- 1.9 vs 7.1 +/- 2 liters/min, P < 0.01), and a decreased mean arterial blood pressure (82 +/- 11 vs 94 +/- 13 mm Hg, P < 0.0001) and systemic vascular resistance (838 +/- 235 vs 1102 +/- 356 dyn/sec/cm5, P < 0.0001). Similar results were obtained when Child A or Child B-C patients were analyzed separately. Multivariate logistic regression disclosed that hemoglobin concentration, in addition to age, sex azygos blood flow, and albumin concentration, was an independent factor influencing the degree of systemic vasodilation in cirrhotic portal-hypertensive patients. This study discloses that anemia worsens the hyperdynamic circulation associated with portal hypertension. Since hemoglobin concentration may change with time, this parameter should be taken into account when evaluating hemodynamics in portal-hypertensive patients.

Portal Hypertensive gastropathy

The term portal hypertensive gastropathy (PHG) defines a wide spectrum of diffuse macroscopic lesions that appear in the gastric mucosa of patients with portal hypertension. Histologically, these lesions correspond to dilated vessels in the mucosa and submucosa in the absence of erosions or inflammation. Endoscopically, the lesions are classified as mild when mosaic pattern or superficial reddening are present, and severe when gastric mucosa appear with diffuse cherry red spots. Mild lesions are highly prevalent (65-90%), whereas severe lesions are present in only 10-25% of cirrhotic patients. The pathogenesis of PHG is not well known, but both venous congestion related with raised portal pressure and increased gastric blood flow seem to be crucial factors for its development. Variceal sclerosis may contribute to the development or aggravation of the lesions. Bleeding is the unique clinical manifestation of PHG, and occurs only in those patients with severe lesions. During a 5-year follow-up, the risk of overt bleeding or chronic bleeding, which induces anaemia, is 60 % and 90%, respectively, for patients with severe PHG. Propranolol is the only pharmacological treatment that has been proven useful in preventing bleeding from PHG. Porto-systemic shunts and liver transplantation are also effective.

Early changes in hemoglobin and hematocrit levels after packed red cell transfusion in patients with acute anemia

BACKGROUND

Equilibration of hemoglobin concentration after transfusion has been estimated to take about 24 hours, but some studies have shown that earlier measurements reflect steady-state values in persons who have not bled recently. This study was aimed at assessing the changes over time in hemoglobin concentration after transfusion in acutely anemic patients because of recent bleeding.

STUDY DESIGN AND METHODS

Thirty-two normovolemic patients recovering from an acute bleeding episode who were no longer thought to be bleeding and who received a 2-unit red cell transfusion were studied. At baseline and 15, 30, 60, and 120 minutes and 24 hours after transfusion, hemoglobin concentration and hematocrit values were measured.

RESULTS

The administration of 2 units of packed red cells elicited a 24-hour increase of 22.4 +/- 6.8 g per L in hemoglobin concentration. Hemoglobin values were not different at any of the defined posttransfusion times. Hematocrit levels experienced similar changes over time. Agreement between 15-minute and 24-hour values was excellent, as only 6 percent of patients exhibited a clinically significant difference (> 6 g/L) between the hemoglobin measurements.

CONCLUSION

Hemoglobin and hematocrit values rapidly equilibrate after transfusion in normovolemic patients who are recovering from an acute bleeding episode. This fact would allow a rapid assessment of the effects of transfusion and of the recurrence of bleeding in patients remaining at risk.

Gastric mucosal damage in experimental diabetes in rats: role of endogenous glutathione

BACKGROUND & AIMS

Spontaneous gastric damage occurs in diabetic rats, but the mechanism is unknown. The aim of this study was to assess the role of glutathione metabolism and gastric mucosal blood flow (GMBF) in the development of such spontaneous gastric damage.

METHODS

Mucosal damage, GMBF, glutathione metabolism, and lipid peroxidation were measured in the stomach of diabetic and control rats.

RESULTS

Spontaneous gastric damage occurred in fasted diabetic rats 4 weeks after streptozotocin administration or pancreatectomy. This was accompanied by a 50% decrement in mucosal content of glutathione; 48 hours after streptozotocin, the decrement of glutathione was only of 25% and no gastric damage was observed. Fed diabetic rats (4 weeks after streptozotocin) had normal glutathione levels and no damage; however, a 30% glutathione depletion achieved by buthionine-sulfoximine administration promoted significant damage. Gastric glutathione synthetic rate, levels of adenosine triphosphate, oxidized glutathione, and malonyldialdehyde were similar in all groups, whereas cysteine concentration was reduced in fasted diabetic animals. Exogenous cysteine attenuated the gastric damage. GMBF was not influenced by diabetes.

CONCLUSIONS

Spontaneous gastric damage in fasted diabetic rats seems to be related to glutathione depletion as a result of limited availability of cysteine and not to increased glutathione oxidation. GMBF changes are not involved.

Postoperative complications of laparoscopic-assisted colectomy

BACKGROUND

This study was performed to prospectively assess the complications of 118 consecutive patients who underwent laparoscopic assisted colorectal resections.

METHODS

The variables included were: indication for surgery, type of resection, duration of operation, duration of postoperative ileus, length of hospital stay, port-site recurrence, and complications in relation to the laparoscopic technique.

RESULTS

118 Laparoscopic-assisted procedures were performed between July 1992 and October 1995. Surgical indications were: 106 patients for colonic malignancy, six for diverticulitis, two for Crohn's disease, two for benign polyps, one for endometriosis, and one for ischemic colitis. Fifteen patients required conversion to open techniques for completion of the operations (12.7%). The mean operating time was 168.8 min. The amount of operative blood loss was 98 ml. The mean time for passing flatus was 36 +/- 16 h. Mean postoperative stay was 5.4 (range 3-13) days. Eight patients (6.8%) sustained complications: four unrelated to laparoscopy (three wound infection, one anastomotic leak); and four complications related to the laparoscopic approach: one small-bowel obstruction, one trocar injury, one rotation of the anastomosis, and one misdiagnosed synchronous adenocarcinoma.

CONCLUSIONS

We suggest that with the development of improved technical devices and more experience, the indications for laparoscopic colectomy should continue to expand. The low incidence of infectious complications suggests an important role for the laparoscopic approach to colorectal surgery.

[Chronic anemia protects against gastric damage by alcohol and aspirin. The role of the toxic radicals and lipid peroxidation]

The effects of chronic anemia on gastric damage induced by ethanol or aspirin have been investigated in rats. The role of free radicals and lipid peroxidation in that circumstance was also assessed. Chronic anemia was induced by replacement of 1.5 ml of blood by a plasma expander during 5 days. Under anesthesia, the stomach was perfused with 100% ethanol or acidified aspirin during 30 minutes. Thereafter, the rats were sacrificed, the stomachs removed and analyzed planimetrically for macroscopic damage. In addition, gastric tissue was collected and homogenized for assessment of toxic free radicals generation by chemoluminicense and lipid peroxidation by measuring reactive species of thiobarbituric acid (TBA-RS). Chronic anemia significantly protected against damage induced by ethanol or aspirin. The rate of toxic free radicals and the TBA-RS in the gastric mucosa was significantly reduced by anemia, either under ethanol or aspirin injury. It is concluded that anemia offers a general protection against gastric mucosal damage and that this protection is in part mediated by limitations on lipid peroxidation and toxic free radicals generation.

[Duodenal obstruction by biliary lithiasis (Bouveret's syndrome)]

The case of an 81-year-old woman admitted for abdominal pain, nausea and vomiting diagnosed with Bouveret syndrome is presented. This rare disease, consisting in obstruction of gastric emptying by gallstones located in the pylorus or the duodenal bulb predominates in elderly women and represents 2% of the cases of biliary ileum. Diagnosis is based on the clinical manifestations, the existence of aerobilia, visualization of lithiasis by radiography, echography or fiber gastroscopy and the demonstration of duodenal obstruction. The treatment of choice is surgery consisting in gastrotomy or enterotomy and extraction of the stone. The importance of diagnosis and early treatment is emphasized to improve prognosis.

Anatomical differences in responsiveness to vasoconstrictors in the mesenteric veins from normal and portal hypertensive rats

The present study evaluates the effects of pre-hepatic portal hypertension, induced in rats by partial portal vein ligation, on the responsiveness of rostral (proximal) and caudal (distal) rings from the mesenteric vein. The anatomical origin of the sample influenced the response to vasoconstrictors in sham-operated animals, and this pattern of reactivity was specifically modified in portal-ligated rats. In veins from sham-operated rats, contraction induced by a submaximal concentration of KCl (60 mM) was greater in proximal than in distal rings. Vasopressin and 5-hydroxytryptamine contracted mainly distal rings, methoxamine showed a greater effect on proximal rings, and endothelin-1 and angiotensin-II contracted vein rings independently of their anatomical origin. In veins from portal hypertensive rats, response to KCl (60 mM) were increased in distal rings, and all rings exhibited enhanced reactivity to vasopressin and 5-hydroxyptyptamine as well as attenuation of the response to methoxamine. Responses to endothelin-1 were decreased in proximal vein rings from portal hypertensive rats whereas responses to angiotensin-II were not influenced by the anatomical origin. Incubation with atropine, propranolol or indomethacin, did not modify the responses to vasopressin and 5-hydroxytryptamine in tissues from either sham-operated or portal hypertensive animals. Likewise, the hyporeactivity to methoxamine and endothelin-1 in rings from portal hypertensive rats persisted in the presence of the nitric oxide inhibitor NG-nitro-L-arginine methyl ester. These results suggest the physiological existence of anatomical differences in the responsiveness to vasoconstrictors throughout the mesenteric vein and that changes in the responsiveness of the mesenteric vein induced by portal hypertension are specific for each agonist and possibly result from individual variations at a receptor or post-receptor level.

Nitric oxide-mediated beta 2-adrenoceptor relaxation is impaired in mesenteric veins from portal-hypertensive rats

BACKGROUND & AIMS

beta-Adrenergic relaxation seems to be mediated by nitric oxide. The aim of this study was to evaluate changes induced by portal hypertension in beta 2-adrenergic vasorelaxation.

METHODS

Isolated rat mesenteric veins were relaxed by salbutamol, and nerve-mediated vasocontractions were induced by electrical field stimulation. Responses were evaluated in the presence of NG-nitro-L-arginine methyl ester (L-NAME) or tetrodotoxin. Immunocytochemical techniques were used for localization of neuronal NO synthase.

RESULTS

Salbutamol-induced relaxations were decreased in rings from portal-hypertensive animals. L-NAME reduced these relaxations, but its effects were more pronounced in sham-operated rats. Tetrodotoxin decreased the effect of salbutamol only in rings from sham-operated animals. Combination of L-NAME and tetrodotoxin did not exert a greater effect than either of these agents alone. Veins from portal-hypertensive animals were more sensitive to S-nitroso-N-acetyl penicillamine. L-NAME increased vasocontractions by electrical stimulation only in rings from sham-operated rats. Veins from portal-hypertensive animals exhibited a specific degeneration of NO-containing nerve endings.

CONCLUSIONS

beta 2-Adrenergic relaxation is impaired in mesenteric veins from portal-hypertensive rats, possibly as a result of a defective neuronal release of NO.