Search

The Italian INFN-Grid Project is committed to set-up, run and manage an unprecedented nation-wide Grid infrastructure. The implementation and use of this INFN-Grid Testbed is presented and discussed. Particular care and attention are devoted to those activities, relevant for the management of the Testbed, carried out by the INFN within international Grid Projects.

We briefly describe the authorization requirements, focusing on the framework of the DataGrid and DataTAG Projects and illustrate the architecture of a new service we have developed, the Virtual Organization Membership Service (VOMS), to manage authorization information in Virtual Organization scope.

International audience; This article discusses the authentication and the authorization aspects of security in grid environments spanning multiple administrative domains. Achievements in these areas are presented using the EU DataGrid project as an example implementation. It also gives an outlook on future directions of development.

U ltrasunography has become the standard approach for investigating suspected urinary tract obstruction because of its safety and high sensitivity.lJ However, it is important to understand that ultrasonography does not detect obstruction directly, but rather its usual consequence: dilatation of the renal collecting system. Unforhmately, urinary tract obstruction is not always accompanied by detectable dilatation36 In these unusual cases of nondilated obstructive uropathy, the results of conventional ultrasonography will be falsely negative, thereby misleading the physician and possibly delaying diagnosis and therapy. Most previously reported cases have been the result of retroperitoneal or pelvic malignancy or fibrosis, or have followed pelvic surgery.56 Here we report a case of nondilated obstructive uropathy caused by a ureter-al calculus in order to alert physicians to the possibility that on occasion, even obstruction due to a urinary stone may be missed by ultrasonography. While this presentation has been noted previously by radiologists,5~7-~ it has not been emphasized in the general medical literature.

In the new generation of very low bit rate speech coding models, multiband excitation (MBE) represents one of the most promising techniques. The paper proposes a new low-complexity two-band coding scheme capable of producing good speech quality at 2.4 kbit/s. Two new solutions are proposed to guarantee pitch continuity and establish the frequency of transition between the voiced and unvoiced portions of band. During informal listening tests we have seen that the speech coder proposed maintains a natural quality, perfect intelligibility and speaker identity. Finally, to demonstrate the simplicity of the algorithms proposed, the paper presents an evaluation of the speech coder complexity for a real-time implementation on a single low-cost digital signal processor.

In the grid world, users expect to be able to log into a grid-enabled machine without the need of having a personal account on the machine itself. To this end, users have organized themselves into Virtual Organizations (VOs) and access to the machines is (excepting differences in local policy, like for example the banning of a specific user) generally granted on the bases of VO membership. Up to now, users who are members of more than a Virtual Organization (VO) (or different subgroups of a single VO) have had no way to specify this while logging into the grid. This paper describes a possible solution to this problem.

Two patients are described who presented with complete urinary obstruction secondary to nonopaque uric acid stones. They were treated with percutaneous nephrostomy for urinary diversion and urinary alkalinization by local irrigation and oral sodium bicarbonate therapy with complete dissolution of the stone after 16 and 21 days of therapy. Percutaneous nephrostomy with urinary alkalinization is a reasonable, relatively safe alternative to surgical stone removal for patients with obstructing uric acid stones.

A double-blind clinical trial was performed in 60 patients to compare Hexabrix (ioxaglate meglumine and ioxaglate sodium) and Renografin-60 (diatrizoate meglumine and diatrizoate sodium). Use of Hexabrix produced higher urinary iodine concentrations, lower urine volumes at 30 minutes, and excretory urograms significantly better in diagnostic quality, as rated by four independent observers. There was no difference in nephrogram quality between contrast agents. Patients receiving Hexabrix had less of an increase in heart rate and demonstrated a slight rise in mean arterial blood pressure, rather than the biphasic rise then fall seen with Renografin-60. There was no significant change for up to 96 hours after urography in results of hematology, clinical chemistry, or urinalysis, except for an increase of 0.005 in urine specific gravity with Renografin-60. Patients reported significantly less body heat, heat in the injection arm, and overall discomfort with Hexabrix. There was a similar amount of nausea and vomiting in the two groups. Hexabrix also caused histaminic-type reactions in three patients.

The effect of .3 cc of 1:1000 epinephrine on iodine concentration, total iodine content, fluid volume and radiographic quality was evaluated in knee arthrograms in dogs. With the addition of epinephrine the iodine concentration and total iodine content were significantly higher initially and remained significantly higher than in controls over a one hour period. The fluid volume in the knee was significantly lower with epinephrine. Initially both contrast absorption and dilution have major effects in decreasing iodine concentration. With increasing time the effect of contrast absorption becomes the major factor, having a two of three times greater effect on decreasing iodine concentration. With epinephrine radiographs were judged significantly better early and while the quality deteriorated rapidly in the controls the enhanced quality with epinephrine persisted up to one hour. Epinephrine is a very useful adjunct in enhancing the quality of knee arthrography.

In equivalent doses for intravenous urograms conventional ionic contrast agents give iodine concentrations in the urine of approximately 30 mg iodine/ml, nonionic contrast media provide approximately 50 mg iodine/ml, and the ionic dimer Hexabrix approximately 70 mg iodine/mL. These new low osmolality, contrast media provide significantly higher urinary iodine concentrations than conventional ionic contrast media, provide better diagnostic quality excretory urograms, better patient tolerance, and fewer adverse side-effects and serious reactions. These new low osmolality, contrast media have significant advantages in intravenous urography in both safety and efficacy when compared to conventional higher osmolality contrast media.

A spectrum of rare urachal abnormalities in the adult is described, including urachal cyst, infected urachal cyst and abscess, and urachal carcinoma. The clinical and radiographic features are presented, and diagnosis using ultrasound, computed tomography, and needle aspiration is discussed. Treatment of infected urachal cysts with percutaneous catheter drainage is described.

Growing concern about acute renal failure as the result of contrast agents prompted an investigation into the renal effects of intravenous contrast materials in euvolemic and dehydrated dogs. Bolus injection of hypertonic agents induced marked reductions in filtration fraction and glomerular filtration rate in both groups of animals; however, these changes were transient, returning to near-base-line values within 30 minutes after injection. The most striking differences between euvolemic and dehydrated animals appeared to be related to prerenal factors such as hypovolemia and contrast-induced hypotension.

Investigations into the nature of severe and fatal reactions to contrast media have been severely limited by their unpredictable occurrence in the clinical setting and the absence of suitable laboratory models. The authors report their experience with a canine dehydration model. Intravenous administration of 2 ml/kg of 76% sodium methylglucamine diatrizoate resulted in vomiting, shock, inappropriate slowing of the heart rate, and death. ECG findings indicated suppression of sinoatrial node automaticity, a decrease in the rate of atrioventricular conduction, and depression of myocardial contractility. These results suggest two possible mechanisms: (a) enhanced vagal tone as the result of stimulation of the vasomotor center of the medulla or (b) accentuation of direct contrast-induced myocardial toxicity.

The pharmacokinetics and urinary excretion characteristics of sodium diatrizoate, the new low-osmolality contrast medium iopamidol, a nonionic monomer, and ioxaglate, a monoacidic dimer, were compared. Using rabbits, experimental urography was performed at a dose of 450 mg I/kg. The lowosmolality co

The incidence and cause of urinary tract obstruction in 100 consecutive patients with polycystic renal disease are reported. Because of nonspecific symptoms, poor renal function, and calyceal distortion, obstruction may be difficult to detect. A number of patients had infundibular obstruction caused by a calculus, clot, or inflammation and edema of the pel-vocalyceal wall.

Experimental evidence suggests that the pharmacokinetic properties of several recently introduced contrast media differ from each other and from the conventionally used ionic monomers, which vary from each other as well. Gardeur et al. [4] observed that tissue distribution volume of ioxithalamate in dogs is higher than that of diatrizoate, ioxaglate, iocarmate, or metrizamide. In rat experiments the nonionic agents had a lower tissue distribution volume than the ionic agents [2]. Blood concentration measurements in man suggest that equal doses of ioxithalamate result in lower blood concentrations than those of ioxaglate and iocarmate [4].

In deciding to use a new intravascular contrast medium, the considerations should be patient safety, Imaging efficacy, and cost. Balancing these factors, use can be estimated. With the new low-osmolality contrast media, particularly the nonionic media, the expected increased patient safety must be balanced against the much higher cost.

Experience with percutaneous drainage in four cases of splenic abscess is presented. Percutaneous drainage and antibiotics were curative in three of four cases. The one case not adequately treated by antibiotics and percutaneous drainage was also complicated by ascites and multilocular collections. Percutaneous drainage in this case did not adversely affect subsequent curative surgery. Percutaneous catheter drainage of splenic abscess under radiologic guidance can be a safe, effective treatment.

Urografin 60, iopamidol and Hexabrix were studied in patients undergoing body CT scans to examine the pharmacodynamics of these contrast agents. Immediately following rapid injection, the lower osmolality media, Hexabrix and iopamidol, gave greater aortic concentration of iodine in addition to higher concentrations in the liver and spleen. These two agents also provided significantly better renal enhancement than Urografin 60, with Hexabrix giving higher levels than iopamidol. The higher early vascular concentrations of Hexabrix and iopamidol and the relative absence of side effects due to hyperosmolality and decreased toxicity may have advantages in dynamic CT scanning.

Computed tomography can aid in the distinction of calculi from both tumors and clots in the urinary tract. Its availability, simplicity of interpretation, and noninvasiveness establish it as an important diagnostic modality in selected cases when calculus is in the differential diagnosis of upper urinary tract filling defects.

The commonly accepted criteria for colon malignancy were investigated in malignant and benign polyps smaller than 3 cm in diameter. It was found that most small tumors, both benign and malignant, were sessile and smooth in outline. It was only when the polyps increased in size that their outlines became lobulated or irregular. A stalk was not seen in polyps smaller than 1 cm in diameter. Retraction at the base of a cancer was likewise not seen in these small lesions. The typical malignant characteristics became apparent only when the polyp had grown to 2 to 3 cm in diameter.

New low-osmolality ratio-3 contrast media have been shown to have less toxicity than currently used contrast media. In intravenous excretory urography, these agents give significantly higher urinary iodine concentrations, produce less diuresis, and are better tolerated by patients because of fewer unpleasant side effects. These newer low-osmolality contrast media have significant advantages in intravenous urography.

The authors present an overview of the current status of hysterosalpingography, discussing the advantages and disadvantages of various cannulas, contrast media, and methods of contrast medium introduction. Thirty-two figures illustrate a variety of abnormal findings including among others: intravasation of contrast medium, salpingitis isthmica nodosa, manifestations of pelvic inflammatory disease, the effects of DES exposure, Ascherman's syndrome, adenomyosis, carcinoma, polyps, myomata and developmental uterine abnormalities.

Milk-of-calcium renal cysts, which when asymptomatic need no treatment, sometimes pose diagnostic problems by conventional radiography. Two such cases are here reported. The first case was further evaluated by ultrasonography only, the second case also by computed tomography and cyst puncture, because of an irregularity in the cyst wall. Both imaging modalities added valuable information.

Thirty-two cases of proved pineal tumor were analyzed. Calcification was seen in 75%. The size, character, and position of the calcification were useful indicators of abnormality on plain-film evaluation. Fray's cranioangle method was more sensitive than Oon's method in determining abnormal position of the calcified pineal tumor on the lateral skull film. Most calcifications were displaced postero-inferiorly or inferiorly, which can be explained by obstructive hydrocephalus or direct tumor expansion.

Ninety-seven patients who were undergoing excretory urography for suspected genitourinary tract abnormalities were continuously monitored for systemic blood pressure and pulse rates before (control) and after rapid intravenous injections of contrast material (1.5 ml/kg meglumine iothalamate, 60%) using a Bard pressure monitor. We report the systemic responses observed. Clinically obvious reactions to contrast medium were recorded and compared with the blood pressure and pulse rate responses. The most common response to rapid infusion of contrast medium was a transient hypotension. An increase in systemic pressure had a high association with nausea and vomiting. Significant hypotension (mean blood pressure less than 60 mm Hg) was observed in six patients (6%), but no overt clinical manifestations were present.

A case of a rare acquired form of aqueductal stenosis and hydrocephalus developing as a late sequela of mumps virus infection of the central nervous system is presented. The experimental studies of mumps induced aqueductal stenosis in hamsters and mice and the four previously reported cases in the literature are reviewed.

A technique to extrude small obstructing ureteral stones with a catheter through a percutaneous nephrostomy tract is described. The technique was successfully used to extrude obstructing ureteral stones in three patients who had ileal loop urinary diversions and who were poor operative risks, and in one patient who had had no previous urinary tract surgery. In these four patients, ureteral stones were dislodged and removed without complication. The technique may have advantages over previously described techniques, particularly in patients with ileal conduits in whom established retrograde cystoscopic techniques are difficult to perform, and in patients who are poor operative risks.

Twenty-three cases of polycystic disease were reviewed. All were easily detected by computed tomography. All manifested diffuse, bilateral renal cystic disease, and 74% had demonstrable hepatic cystic disease. Computed tomography is more accurate than other conventional modalities in diagnosing renal cysts, and its simplicity of operation and ease of interpretation are unmatched.

Excretory urography of a patient with an early stage of medullary cystic disease demonstrated an inhomogeneous, streaky nephrogram confined to the medulla, presumably due to accumulation of contrast material in dilated tubules. This was seen best one to two hours after contrast injection and may represent a specific urographic finding which does not appear to have been described previously in this condition.

To the Editor.— The article by Eason et al (240:670, 1978) describes the usefulness of alkalinization of the urine in the dissolution of uric acid stones. The efficacy of this treatment is now well documented. The difficulty is, as noted by Eason and colleagues, when the patient has obstruction of the collecting system. Retrograde catheterization has been used in such patients, and those references were quoted by the authors. An alternative approach is available for the obstructed patient with uric acid lithiasis. This involves the use of percutaneous nephrostomy for urinary diversion associated with the conservative medical treatment already well described. We have published an article describing this technique and the results in two patients, 1 which appeared after the article by Eason and co-authors. The use of percutaneous nephrostomy has increased as its safety and efficacy have been proved. 2 A two-catheter technique can also be used with percutaneous