An exact noniterative linear method for locating sources based on measuring receiver arrival times.

In this paper an exact, linear solution to the source localization problem based on the time of arrival at the receivers is presented. The method is unique in that the source's position can be obtained by solving a system of linear equations, three for a plane and four for a volume. This simplification means adding an additional receiver to the minimum mathematically required (3+1 in two dimensions and 4+1 in three dimensions). The equations are easily worked out for any receiver configuration and their geometrical interpretation is straightforward. Unlike other methods, the system of reference used to describe the receivers' positions is completely arbitrary. The relationship between this method and previously published ones is discussed, showing how the present, more general, method overcomes nonlinearity and unknown dependency issues.

Palliative surgery for gastric cancer in elderly patients.

Poor survival rate of elderly patients affected by locally advanced or metastatic gastric cancer is related to primary tumour complications. Bleeding is the most important adverse event, other major complications are gastric outlet obstruction and nutritional deprivation. Rarely the patients will perforate the stomach cancer and there is a sudden end to their life; contamination of the ascites result in a rapid death. Thus, an aggressive approach toward palliation of this condition is resection: in this manner the expected survival is approximately one year. Derivation techniques or endoscopic treatments are applied in those patients whose operative risk is inacceptable; in these cases poor median survival is expected. The aim of this report in to refer about the experience in palliative surgery for gastric cancer in the Department of Geriatric Surgery of the University of Padua.

[Bleeding gastric lymphoma: report of two cases]. / Linfoma gastrico sanguinante: descrizione di due casi clinici.

We report two cases of bleeding gastric lymphoma. The stomach is the most common site of primary extranodal Non-Hodgkins Lymphomas. The best treatment for primary gastric lymphoma has not yet been defined. For many years the treatment of choice has been the gastric resection. Helicobacter pylori (H. pylori) has been associated with many gastric pathologies, including gastric lymphoma. Eradication of H. pylori is now considered essential for the treatment of this pathology, and usually consists of antibiotic therapy, combined with acid suppression by a proton pump inhibitor. This simple treatment in patients with low grade histology and tumor confined to the stomach can often obviate the need for surgical intervention. Surgery is a necessary treatment, independently of the grading and the staging of lymphoma, in the bleeding complication as the cases we showed.

[Surgical risk in the elderly]. / Il rischio operatorio nell'anziano.

In our Country 16% of population is over 65 years old and on 2010 a quarter of people will be over 70 years old. More over the percentage of patients over 70 years admitted in surgical departments is triple than 10 years ago and the percentage of octgenarian patients is ten times. In the last years new methods of diagnosis and care have been introduced to reduce morbility and mortality; the preoperative evaluation to define the risk factors is complex. The surgeon should respect some primary points: the patient interest, true surgical treatments, multimodal management, valid pain therapy, discharge as soon as possible, ambulatory or day hospital management, expecting and quality of life.

[Septic shock: surgical and medical problems in the elderly]. / Shock settico: problematiche chirurgiche e mediche nell'anziano.

The sepsis is a bacterial invasion of the organism producing many manifestations which are able to amplify themselves. In the United States of America there are 100,000 death per year and the incidence is among 300,000-500,000 cases. The major surgery in the elder (especially if it is in emergency) has a great percental of risk because the preoperative study isn't often complete. Fever, agitation, panting, bullation, abdominal splinting, enteroplegia, are signals of evolving inflammatory situation. Moreover there are disorders of biochemical values: leukocytosis, thrombocytopenia, increased levels of VES, PCR, amylase and biliribinaemia. The more common radiological examinations are the straight radiography of abdomen and horax, abdomen ultrasonography, CT or MRI. In the last years pro-calcitonin, interleukin-6 , C-reactive protein, and nitric oxide from endothelial and muscularis cells have been evaluated as prognostic factors in the septic shock.

[Treatment of the early form of rectal carcinoma in the elderly]. / Il trattamento delle forme iniziali di carcinoma rettale nell'anziano.

The early rectal cancer which needs conservative surgical treatment should present some pathological characters: intramucosal site without muscularis invasion (pT1), high or moderate differentiated grading (GI-G2), no lymph node metastasis or vascular invasion. Total mesorectal excision is the gold standard for these neoplasms and permits very low resection or colo-anal anastomosis with sphincter function preserving. However, this type of surgery has still a high percentage of postoperative morbidity and mortality (some authors report respectively 40% and 5%). Therefore the local excision in selected cases is able to preserve the sphincter function and to reduce the postoperative complications with high probability of recovery.

[Intestinal infarction in the elderly]. / L'infarto intestinale nell'anziano.

The bowel infarction is till affected by high mortality in spite of new diagnostic methods and therapy. In our experience was observed about 45 patients with bowel infarction by different etiology; fast diagnosis and therapy are necessary for a good prognosis. The arteriography, at the light of this experience, is the gold standard but it is still performed in a low number of patients. The laparoscopy, in the advanced pathologies, is able to avoid an ineffectual laparotomy and permits a better diagnosis in borderline cases.

[Therapeutic strategy in neoplasia of the pancreas and ampulla]. / Strategie terapeutiche nelle neoplasie del pancreas e dell'ampolla.

The major symptoms of periampullary neoplasia are jaundice, lowering of weight, abdominal pain extending behind; diabetes, pancreatitis or exocrine pancreatic failure are uncommon. In the last years, surgery has been considered as the gold standard of the therapy because new technologies are able to reduce morbility and mortality. In the too advanced neoplasia, palliative surgical care permits better survival and quality of life. The duodenopancreatectomy today has a low perioperative mortality (0-3%) and an acceptable survival (15.25%). Good results were found for palliative surgery in unresectable neoplasms while in the inoperable patients we consider endoscopic and radiological treatments better than chemotherapy because they are able to correct the jaundice, improving quality of life (but not survival).

Prevalence of intestinal metaplasia in the distal oesophagus, oesophagogastric junction and gastric cardia in symptomatic patients in north-east Italy: a prospective, descriptive survey. The Italian Ulcer Study Group "GISU".

BACKGROUND: Incidence of adenocarcinoma of distal oesophagus and gastric cardia, probably arising from areas of intestinal metaplasia, has been increasing rapidly. AIMS: To define prevalence of intestinal metaplasia of distal oesophagus, oesophagogastric junction and gastric cardia and to evaluate potential associated factors, by means of a prospective multicentre study including University and teaching hospitals, and primary and tertiary care centres. PATIENTS: Each of 24 institutions involved in study enrolled 10 consecutive patients undergoing first-time routine endoscopy for dyspeptic symptoms. METHODS: Patients answered symptom questionnaires and underwent gastroscopy Three biopsies were taken from distal oesophagus, oesophago-gastric junction and gastric cardia, and were stained with haematoxylin and eosin. Specimens were also evaluated for Helicobacter pylori infection. RESULTS: A total of 240 patients (124 male, 116 female; median age 56 years, range 20-90) were enrolled in study. Intestinal metaplasia affected distal oesophagus in 5, oesophago-gastric junction in 19 and gastric cardia in 10 patients. Low-grade dysplasia was found at distal oesophagus and/or oesophago-gastric junction of 3/24 patients with intestinal metaplasia vs 2/216 without intestinal metaplasia (p<0.05). A significant association was found between symptoms and presence of intestinal metaplasia, regardless of location, and between Helicobacter pylori infection and intestinal metaplasia at oesophago-gastric junction. CONCLUSIONS: Intestinal metaplasia of distal oesophagus, oesophagogastric-junction and gastric cardia is found in a significant proportion of symptomatic patients undergoing gastroscopy and is associated with dysplasia in many cases. Although prevalence of dysplasia seems to decrease when specialized columnar epithelium is found in short segment, or even focally in oesophago-gastric junction, these small foci of intestinal metaplastic cells may represent source of most adenocarcinomas of cardia.

Lidocaine-sensitive atrial tachycardia: lidocaine-sensitive, rate-related, repetitive atrial tachycardia: a new arrhythmogenic syndrome.

OBJECTIVES: The goal of this study was to report a variety of atrial tachycardia that might be caused by an unusual electrophysiologic substrate. BACKGROUND: The mechanism of atrial tachycardias is attributed to re-entry, abnormal automaticity or triggered activity, based on their electropharmacological responses. A rate-related and lidocaine-sensitive atrial tachycardia has not been reported. METHODS: Eight patients (3 women and 5 men, aged 14 to 60 years) with repetitive, uniform atrial tachycardias were studied. In six patients the arrhythmia had been refractory to at least three antiarrhythmic agents (class 1A and C sodium channel blockers, amiodarone, beta-adrenergic blocking agents, verapamil, digoxin). Conventional electrocardiograms, Holter recordings and B mode echocardiograms were performed in each patient. Intravenous lidocaine and verapamil were tested in the eight patients. Six patients underwent an electrophysiologic study. RESULTS: The baseline electrocardiogram showed nearly incessant runs of atrial tachycardia in all patients. The mean atrial ectopic cycle length ranged from 376 to 502 ms. In seven patients a progressive prolongation of the cycle length from the beginning to the end of the salvos was documented. The arrhythmia was suppressed by increments of sinus node rate and by atrial pacing at cycle lengths longer than that of the atrial tachycardia. In all patients the arrhythmia was abolished by intravenous lidocaine, whereas intravenous verapamil was ineffective. Four symptomatic patients were successfully treated with radiofrequency ablation of the ectopic focus, and two patients were treated with oral mexiletine. CONCLUSIONS: The peculiar electropharmacological responses of this arrhythmia suggest an uncommon underlying mechanism that remains to be elucidated.

Atrial tachycardia masquerading as atrial flutter following ablation of the subeustachian isthmus.

We report a case of atrial tachycardia masquerading as atrial flutter in a man who had previously undergone catheter ablation for atrial flutter. The recurrent arrhythmia was electrocardiographically almost identical to the prior atrial flutter; at repeat electrophysiologic study, although bidirectional conduction block was observed in the tricuspid annulus-inferior vena caval isthmus, the atrial arrhythmia was readily initiated. Activation mapping suggested typical atrial flutter, but entrainment techniques demonstrated intra-atrial reentry not involving the ablated isthmus. This case illustrates the need to apply entrainment techniques even in cases of apparent "typical" atrial flutter to confirm that putative ablation targets are necessary for tachycardia perpetuation.

[Usefulness of chromogranin A determination in the diagnosis of neuroendocrine neoplasia]. / Utilità del dosaggio della cromogranina A nella diagnosi delle neoplasie neuroendocrine.

Neuroendocrine gastroenteropancreatic tumor diagnosis is a very difficult and expensive procedure. This study compared Chromogranin A (CgA) to Neuron-specific enolase (NSE) in 55 patients affected by neuroendocrine tumors. Advanced local or metastatic neoplasia was found in 43 patients. Radical operation was performed in 12 patients. Seventeen cases of lung microcystoma, 23 cases of other intestinal tumors and 19 patients affected by irritable bowel syndrome were used as controls. CgA sampling demonstrated sensitivity of 73% and specificity of 66%, a positive predictive value of 77% and a negative predictive value of 61% while NSE sampling showed sensitivity of 100%, specificity of 36%, a positive predictive value of 15% and a negative predictive value of 100%. CgA values demonstrated a statistically significant difference between patients with neuroendocrine tumors and tumor-free resected patients (p = 0.0015), microcystoma patients (p = 0.0087), other types of neoplasia (p = 0.01) and irritable bowel syndrome patients (p = 0.0004). No significant difference was found among the same groups when NSE values were analyzed. The high diagnostic accuracy of CgA sampling renders it very useful in early neoplastic detection, even in cases of nonfunctioning neoplasms or absence of liver metastases. In addition, CgA sampling may be an effective screening test in patients with irritable bowel syndrome or with liver or lung metastases when there is no evidence of the primitive tumor.

Electromagnetic interference of digital and analog cellular telephones with implantable cardioverter defibrillators: in vitro and in vivo studies.

The present study examines the potential electromagnetic interference effects induced by cellular telephones on ICDs. We developed ad hoc protocols to conduct both in vitro and in vivo trials on most of the implantable cardioverter defibrillators available on the international market. Trials were conducted with three cellular telephones: two GSM (Global System for Mobile Communication) and one TACS (Total Access Communication System). A human trunk simulator was used to carry out in vitro observations on six ICDs from five manufacturers. In vivo tests were conducted on 13 informed patients with eight different ICD models. During the trials in air, GSM telephones induced interference effects on 4 out of the 6 cardioverter defibrillators tested. Specifically, pulse inhibition, reprogramming, false ventricular fibrillation, and ventricular tachycardia detections occurred, which would have entailed inappropriate therapy delivery had this been activated. Effects were circumscribed to the area closely surrounding the connectors. When the ICD was immersed in saline solution, no effects were observed. Three cases of just ventricular triggering with the interfering signal were observed in vivo.

Comparison of dobutamine ECG stress test with predischarge exercise test after acute myocardial infarction.

Exercise testing after acute myocardial infarction is commonly used, but in recent years alternative methods have been proposed. Standard exercise testing was compared with dobutamine electrocardiographic (ECG) stress testing in 100 patients after an acute initial myocardial infarction. Dobutamine ECG stress testing was performed in a standard manner at 5 +/- 1 days after the infarction and exercise testing was performed a mean of 10 +/- 2 days following the event. Agreement between both tests was observed in 91 cases (91%), P < .001, Fisher test kappa value, 0.79). The dobutamine test predicted the result of the exercise test with a sensitivity of 100% (95% confidence interval, 87-100) and a specificity of 88% (95% confidence interval 77-93) for a positive predictive value of 75% (95% confidence interval, 62-97) and a negative predictive value of 100% (95% confidence interval, 91-100). Dobutamine ECG stress testing is concluded to be an objective and reliable procedure, which accurately predicts the results of standard exercise testing. It is inexpensive, easy to perform, and although not yet confirmed, could be particularly useful in patients who cannot perform exercise.

Clinical evaluation and safety of loxiglumide (CCK-A receptor antagonist) in nonresectable pancreatic cancer patients. Italian Pancreatic Cancer Study Group.

The effects and safety of loxiglumide, a cholecystokinin-A (CCK-A) receptor antagonist, on advanced pancreatic cancer were investigated in humans. A perspective, controlled (2.4 g/day vs. placebo), randomized, double-blind, parallel-group study was performed in 64 patients affected by nonresectable histologically diagnosed pancreatic cancer. The patients were stratified according to sex and stage (A, T3/N0-N1/M0; B, T1-T2-T3/N0-N1/M1; C, relapse after surgical exeresis). Tumor size (by computed tomography scan) and mortality rate were evaluated as efficacy criteria. Clinical symptoms and physical signs, laboratory tests, and adverse reactions were checked every 6 weeks as efficacy/tolerability criteria. Forty-two male and twenty-two female patients were considered. A homogeneous distribution of the patients was demonstrated in the two treatment groups. Group C was not statistically evaluated for survival and tumor evolution because of its small number. Three patients dropped out for causes not related to the therapy. No toxic reactions to the drug were reported. Tumor size monitoring within groups A and B demonstrated a similar increase in both the loxiglumide and the placebo group. Survival in group A was higher than in group B (p = 0.0003). In group B, survival was lower in females (F) than in males (M) (F = 61.00 +/- 6.47 days, M = 140.44 +/- 22.15 days; p = 0.012), while survival by sex was similar in group A and in global analysis. Survival by treatment was similar for groups A and B. Survival by surgery was higher (p = 0.049) for surgical palliation than for nonoperated patients. The tumor grade affected survival but it did not vary by therapy. In conclusion, sure efficacy of loxiglumide in advanced pancreatic cancer was not demonstrated by our results. In consideration of its documented tumor growth inhibiting action, we suggest that loxiglumide be tested for recurrence prevention after resective surgery.

[Physiopathology of intestinal anastomoses and dehiscences]. / Fisiopatologia delle anastomosi intestinali e delle deiscenze.

A lot of mechanisms of healing of intestinal anastomoses has been explained. A leading role in the intestinal wall is made by the submucosal tunica, where collagen synthesis and degradation process take place, but local and systemic factors are present by a definite causal action. Technique of suture, materials and surgeon's experience are of fundamental importance for the success of operation, even if in some cases it is important to take in consideration the clinical situation: emergency or not, the patient's state and age, concomitant diseases, pharmacological or radiotherapeutic treatments. Nowadays surgical research tends towards biochemical and molecular field to identify the factors, that speed up the healing process to use them in suturing materials getting a quick healing as soon as possible.

[Breast cancer in elderly women]. / Il carcinoma della mammella nell'anziana.

Breast cancer represents an important epidemiological and clinical problem, and the elderly age represents a large proportion of women with breast cancer. In patients older than 65-year, the frequency of breast cancer is 50% and more. Early diagnosis and adequate therapy may play an important role also in the elderly. We performed a retrospective analysis of 146 women older than 65-year to determine the effect of age in management of the disease.