A3 adenosine receptors in human astrocytoma cells: agonist-mediated desensitization, internalization, and down-regulation.

A(3) adenosine receptor activation has been previously demonstrated to result in both neuroprotective and neurodegenerative effects, depending upon specific pathophysiological conditions. This dual effect may depend on receptor regulation mechanisms that are able to change receptor availability and/or function. In the present study, we investigated desensitization, internalization, and down-regulation of native A(3) adenosine receptors in human astrocytoma cells after exposure to the agonist 2-chloro-N6-(3-iodobenzyl)-N-methyl-5'-carbamoyladenosine (Cl-IBMECA). Cl-IBMECA induced a concentration-dependent inhibition of adenylyl cyclase activity with an EC(50) value of 2.9 +/- 0.1 nM. The effect was suggested to be mediated by A(3) adenosine receptor subtype by the use of selective adenosine receptor antagonists. Cell treatment with pertussis toxin abolished Cl-IBMECA-mediated inhibition of adenylyl cyclase activity, evidencing an A(3) receptor coupling to inhibitory G protein. Short-term exposure to the agonist Cl-IBMECA (100 nM) caused rapid receptor desensitization, within 15 min. Agonist-induced desensitization was accompanied by receptor internalization: A(3) adenosine receptor internalized with rapid kinetics, within 30 min, after cell exposure to 100 nM Cl-IBMECA. The localization of A(3) adenosine receptors on the plasma membrane and in intracellular compartments was directly revealed by immunogold electron microscopy. After desensitization, the removal of agonist led to the restoration of A(3) adenosine receptor functioning through receptor recycling to the cell surface within 120 min. Prolonged agonist exposure (1-24 h) resulted in a marked down-regulation of A(3) adenosine receptors that reached 21.9 +/- 2.88% of control value after 24 h. After down-regulation, the recovery of receptor functioning was slow (24 h) and associated with the restoration of receptor levels close to control values. In conclusion, our results demonstrated that A(3) receptors, in astrocytoma cells, are regulated after short- and long-term agonist exposure.

7-Nitrobenzofurazan (NBD) derivatives of 5'-N-ethylcarboxamidoadenosine (NECA) as new fluorescent probes for human A(3) adenosine receptors.

New fluorescent ligands for adenosine receptors (ARs), obtained by the insertion, in the N(6) position of NECA, of NBD-moieties with linear alkyl spacers of increasing length, proved to possess a high affinity and selectivity for the A(3) subtype expressed in CHO cells. In fluorescence microscopy assays, compound 2d, the most active and selective for human A(3)-AR, permitted visualization and localization of this human receptor subtype, showing its potential suitability for internalization and trafficking studies in living cells.

[The treatment of laparocele by means of a reticulo-laminar prosthesis (Composix Mesh). A technical note]. / Trattamento del laparocele mediano con protesi reticolo-laminare (Composix Mesh). Note di tecnica.

In this paper, the authors present a modified Rives' technique for the treatment of incisional hernias. This technique requires the use of a nonabsorbable prosthesis (Composix Mesh) made of a double-knit layer of monofilament polypropylene bonded with a single layer of low-porosity e-PTFE inserted behind the rectus muscles and fixed by metallic clips. The outer side (polypropylene) encourages complete host tissue incorporation to reduce recurrences, the inner side (e-PTFE) minimizes tissue attachment and, therefore, visceral complications.

Agonist-induced internalization and recycling of the human A(3) adenosine receptors: role in receptor desensitization and resensitization.

A(3) adenosine receptors have been proposed to play an important role in the pathophysiology of cerebral ischemia with a regimen-dependent nature of the therapeutic effects probably related to receptor desensitization and down-regulation. Here we studied the agonist-induced internalization of human A(3) adenosine receptors in transfected Chinese hamster ovary cells, and then we evaluated the relationship between internalization and signal desensitization and resensitization. Binding of N(6)-(4-amino-3-[(125)I]iodobenzyl)adenosine-5'-N-methyluronamide to membranes from Chinese hamster ovary cells stably transfected with the human A(3) adenosine receptor showed a profile typical of these receptors in other cell lines (K:(D) = 1.3+/-0.08 nM; B(max) = 400+/-28 fmol/mg of proteins). The iodinated agonist, bound at 4 degrees C to whole transfected cells, was internalized by increasing the temperature to 37 degrees C with a rate constant of 0.04+/-0.034 min(-1). Agonist-induced internalization of A(3) adenosine receptors was directly demonstrated by immunogold electron microscopy, which revealed the localization of these receptors in plasma membranes and intracellular vesicles. Moreover, short-term exposure of these cells to the agonist caused rapid desensitization as tested in adenylyl cyclase assays. Subsequent removal of the agonist led to restoration of the receptor function and recycling of the receptors to the cell surface. The rate constant of receptor recycling was 0.02+/-0.0017 min(-1). Blockade of internalization and recycling demonstrated that internalization did not affect signal desensitization, whereas recycling of internalized receptors was implicated in the signal resensitization.

Double synchronous occluding tumors of the large bowel: a report of three cases.

The development of acute large bowel obstruction secondary to colorectal cancer is very common and, while right hemicolectomy with a primary anastomosis is the accepted procedure for right-sided obstructing tumors, the different strategies performed for left-sided tumors, including staged procedures, Hartmann's procedure, and resection with anastomosis, remain a subject of controversy. We present herein the case reports of three patients who developed two synchronous occlusive tumors of the large bowel. Complete exploration of the entire colon is highly recommended to assess the most feasible therapeutic option in such cases, as the second occlusive tumor, often hidden within the bowel segments, can cause failure of limited resection or intestinal decompression.

[History of reconstruction following total gastrectomy]. / Storia della ricostruzione dopo gastrectomia totale.

Near a century after the first successful total gastrectomy for gastric cancer, the authors review the various technical proposals for digestive tract reconstruction following total gastrectomy. Following a classification based on duodenal circuit, on the viscerum employed and on the creation of pouches and/or anti-reflux mechanisms, pros and cons of the various classes of reconstructions are clearly depicted, suggesting the reasons that made Roux-en-Y esophago-jejunostomy and jejunal interposition the most used reconstructive procedure in worldwide clinical practice.

Colonic lesions in pancreatitis.

Lesions of the colon are generally considered to be uncommon sequelae of pancreatitis. They include: localized paralytic ileus (colon cut-off sign), necrosis, fistulae, stenosis and varices. On the basis of an extensive review of the literature (432 cases), it is suggested indeed that the real incidence is significant. The anatomic relationship of the large bowel to the pancreas is an important factor in the genesis and localization of the lesions. Enzymatic-inflammatory and ischemic processes are involved in the most highly supported theories. Colon cut-off sign is almost always spontaneously reversible and may represent an "alarm" for more serious complications. Massive necrosis develops during the early stage of severe pancreatitis and its mortality rate has been reported to be high. Fistulae are late complications of the disease, associated with a protracted course and probably a consequence of pancreatic suppuration or pseudocysts. Stenoses are the most interesting colonic complications following pancreatitis and caused by either acute obstruction of the colon due to an inflammatory mass or progressive obstruction due to pericolic fibrosis. In this case, the clinical picture may mimic carcinoma.

Is intraoperative ultrasonography useful in pancreatic cancer surgery?

Preoperative staging of pancreatic cancer represents a major challenge for a suitable surgical management of the disease. In a consistent number of patients laparotomy is still necessary in order to decide whether the tumor is resectable or not. In the present paper the Authors report their experience with intraoperative ultrasonography (IOU) in evaluating pancreatic cancer resectability. Very important data for intraoperative decision making were obtained in 37.9% of the patients, useful information in 31%, while in 31% IOU may be looked forward to as an important aid in decision making and for a safely guided dissection.

[Surgical treatment of 4th-stage hemorrhoids: the role of anatomical techniques]. / Trattamento chirurgico delle emorroidi al IV stadio: il ruolo delle tecniche anatomiche.

Surgical options for fourth-degree hemorrhoids are still matter of debate. The high incidence of the disease encouraged research and brought to technical improvements able to achieve a painless, reliable, harmless and well tolerated surgical treatment. The Authors report a retrospective study of 193 patients who underwent surgery for fourth-degree hemorrhoids. In these cases the Authors advise anatomic techniques using local anaesthesia with i.v. administration of sedatives, thus allowing a 24-hour hospitalization.

[Technique and immediate results of the Moreno Gonzalez-Carboni reconstruction after total gastrectomy]. / La tecnica ed i risultati immediati della ricostruzione secondo Moreno Gonzalez-Carboni dopo gastrectomia totale.

Reconstruction following total gastrectomy for gastric cancer is still matter of debate. The Roux-en-Y esophagojejunostomy and the interposed loop esophago-jejunoduodenostomy are the techniques commonly employed. The Authors describe their modification of Henley's jejunal interposition and report early results achieved in a series of 60 consecutive patients.

Low anterior resection versus abdominoperineal excision: a comparison of local recurrence after curative surgery for "very low" rectal cancer.

In the controversy regarding whether sphincter-saving resection (SSR) or abdominoperineal resection (APER) is more appropriate for the treatment of very low rectal cancer, local recurrence rates seem to play a fundamental role in patient outcome. In order to operate an effective patient selection, very low rectal cancer is defined herein as being located within 4.5 to 7.5 cm from the anal verge. This retrospective report investigates the incidence of local recurrence after curative surgery for very low rectal carcinoma in 24 consecutive patients treated by the same surgical team over a 15-year period using the above surgical procedures. In the APER group, the local recurrence rate was 45.5%, occurring in 5 of 11 cases; and in the SSR group 46.1%, occurring in 6 of 13 cases, with no significant difference between the two groups. Recurrence was found within one year of surgical treatment in all except one case. Despite the strict follow-up program, it was only possible to perform reoperation in two recurrent cases, both previously submitted to SSR and diagnosed by means of transanal ultrasonography and macrobiopsy. The high incidence of local recurrence in this series is explained by the advanced stage of disease in the majority of cases. Thus, as the choice between APER and SSR does not seem to affect the incidence of local recurrence, which is related more to tumor size, site, stage, and grading, preservation of the sphincters and restoration of digestive continuity should be achieved whenever technically possible.

[Occlusion caused by colo-rectal carcinoma: personal experience]. / L'occlusione da carcinoma colo-rettale: esperienza personale.

In the last 12 years 25 patients affected with obstruction from colorectal carcinoma were treated. Mortality following simple colostomy was not different from that of surgical resections (25% vs. 14% in Authors' experience). Major surgery (subtotal colectomy) registered a reasonable mortality rate (5-6%).

The microflora of the gastric juice after Billroth I and Billroth II partial gastrectomy.

Detailed analyses of biochemical and microbiological variables such as pH, nitrite concentration, total viable counts (TVC), nitrate reductase-positive bacterial counts (NRPBC), and identification of microorganisms were carried out on 76 fasting gastric juice samples obtained at endoscopy from 64 patients previously submitted to partial gastrectomy (22 end-to-end Billroth I, 42 Billroth II/Reichel-Polya) and from 12 normal controls. Samples from normal controls were sterile, but bacteria were detected in the juice from all the operated patients. Significantly higher mean pH values and nitrite levels (p less than 0.001) were found in partial gastrectomies than in normal controls. In relation to surgical methods, higher mean pH values (p less than 0.005), nitrite levels (p less than 0.01), TVC (p less than 0.01), and NRPBC (p less than 0.005) were observed in the juice of patients with Billroth II as compared with Billroth I gastrectomies. Anaerobic bacteria, typical of faecal flora, and particularly Escherichia coli (p less than 0.05) characterized Billroth II samples. All these data suggest that the presence of bacteria in the gastric juice of gastroresected patients can be considered a risk factor of gastric neoplasia and that the type of operation used for the reconstruction of digestive continuity may influence the magnitude of this risk.

[Surgical risk of the Oddi sphincterotomy. Results of an international survey (25541 cases)]. / Le risque opératoire de la sphinctérotomie Oddienne. Résultats d'une enquête internationale (25541 cas).

Operative risks of transduodenal sphincterotomy (T.D.S.) are the principal subject of discussion between those surgeons who practice the operation and those that condemn it. An international survey of 25, 541 cases treated by 130 surgeons showed that the incidence of specific complications such as acute pancreatitis (0.6 p. 100), hemorrhage (0,65 p. 100), and early cholangitis (0,5 p. 100), and relative mortality were lower than those usually reported by surgeons attributing an excessive operative risk to the procedure. Data was also obtained indicating that certain "risk factors" due to teh surgical technique were statistically significant (X2 test) and that knowledge of these enabled complications to be avoided. Morbidity and mortality of TDS could then be reduced to the level of those common to biliary tract surgery.

Occult gallbladder microlithiasis causing acute recurrent pancreatitis. A report of three cases.

Gallbladder microlithiasis may be a cause of acute recurrent pancreatitis. When this process cannot be detected with routine investigative procedures, a precise etiologic diagnosis cannot be formulated. In such circumstances, endoscopic collection of bile followed by microscopic examination for presence of cholesterol crystals constitutes a valid diagnostic tool. Three cases of acute recurrent pancreatitis are presented in which cholesterol crystals were found in the bile. The technique and advantages of the method are described and a useful diagnostic approach is proposed.