Electric-field-induced phase transitions in bent-core mesogens determined by x-ray diffraction.

The changes in the x-ray diffraction diagram induced by an electric field have been studied in four bent-core liquid crystals. Two of the compounds present columnar B1 phases and the other two show dark conglomerate (DC) structures. In the B1 materials the electric field gives rise to switchable phases whose diffraction pattern is that of the smectic C polar (SmCP) phase. In the DC structures the positions of the Bragg reflections remain essentially unaltered, but in one of the compounds the peaks become narrower under field, indicating that the correlation length of the smectic order increases. A slight enhancement of the smectic spacing is found in the DC phases upon field application.

Electric-field-induced B1-B2 transition in bent-core mesogens.

We report experimental results on two bent-shaped mesogens showing the B1 phase. Contrary to the conventional B1 structures, we have found that our compounds display a clear electro-optic effect in this phase. Under the influence of a 100-Hz square-wave electric field of moderate amplitude, an increase of the birefringence is observed. However, no switching current is detected, indicating that the materials remain antiferroelectric. For high enough fields, a drastic change in the texture occurs. This change is a phase transition to a B2 phase, and shows the typical antiferroelectric switching of this phase. The induced B2 phase has been identified to be homochiral. Upon removal of the field, the B1 structure is recovered. Our study is based on differential scanning calorimetry, x-ray, electro-optics, polarization reversal, and dielectric measurements.

[Infrequent left renal pseudomass: ectopic spleen]. / Pseudomasa renal izquierda infrecuente: ectopia esplénica.

Ectopic splenic tissue is uncommon in clinical practice, usually asymptomatic and generally unsuspected diagnosed. Interest from urological point of view is due to the possibility of mimicking left renal, adrenal and retroperitoneal tumours; as well as intrapelvic, inguinal and genital masses. We report a 42-years-old female patient with pseudotumoral upper pole left kidney mass with final diagnosis of ectopic spleen. Ethiopathogenic, diagnostic and therapeutical aspects are briefly reviewed in literature. We emphasized opportunity to include ectopic splenic tissue in differential diagnosis of left renal, adrenal and retroperitoneal masses. We recommend imaging studies as CT and MRI, complemented if necessary with liver/spleen radionuclide scan. We advocate for non-aggressive attitude in selected cases with asymptomatic extrapelvic ectopic spleen under confirmed diagnosis, deferring splenectomy in symptomatic instances or secondary portal hypertension cases.

[Epistaxis as initial manifestation of disseminated renal adenocarcinoma]. / Epístaxis como primera manifestación de un adenocarcinoma renal diseminado.

Peculiar renal carcinoma tendency to unusual distant metastases suggest this primary neoplasm to be accounted in differential diagnosis of metastases as first clinical symptom of cancer. Renal cell carcinoma present metastases in 26-30% of cases at the time of diagnosis. Head and neck metastases from renal carcinoma are said to be present in 8% (6-15.2%) of patients, and half of them are asented on paranasal sinuses. We report a 70-years-old patient with recurrent epistaxis as first clinical sign of a nasosinusal metastases from renal disseminated carcinoma, who precised selective embolization. Epidemyologic, diagnostic and therapeutical aspects are briefly reviewed in literature. Nasosinusal metastases are uncommon in clinical practice. We emphasized the need of primary tumor investigation in the organs most often responsible for these metastasic deposits as: kidney (50%), lungs, breast, gastrointestinal tract, urogenital ridge and thyroid gland. Individualized treatment depends on leasions number and localization. On routine follow up of hipernephroma nephrectomized patients a high suspect index has to be considered as paranasal metastases can eventually occur.

[Metachronous contralateral Leydig cell tumor of the testis: conservative treatment]. / Tumor testicular de células de Leydig contralateral metacrónico: tratamiento conservador.

Leydig cell tumors are the primary nongerm cell tumors of the testis, comprising approximately 1 to 3% of all testicular neoplasms. These tumors are bilateral in 5 to 10% of cases. Hypoechoic testicular nodule associated to a child virilising syndrome or adult gynecomastia with negative testis tumor markers (AFP, B-HCG) show a high index suspicion for this entity. We report a case of metachronous contralateral Leydig cell tumor in a 32 years old man with a 9 year interval between presentations, in which we performed local excision of the lesion. Diagnostic an therapeutic aspects are reviewed in literature. Since preoperative diagnosis of Leydig cell tumors in difficult and clinical course unpredictible, radical orchiectomy has been the standard treatment. Emphasis is made on conservative management opportunity in patients with only one testis, small tumors (less than 2.5 cm) with biopsies from tumor bed negative and wishes to remain fertile and/or refuses androgen supplementation. Follow-up is mandatory by performing scrotal ultrasounds. CT scan, Chest X-Ray, tumor markers and hormone determinations (testosterone, estradiol, progesterone, LH and FSH).

[Large renal leiomyoma]. / Leiomioma renal voluminoso.

Renal leiomyomas are uncommon between renal tumors, and they have a benign mesenchymatous origin. Because of their low incidence, unspecific symptomatology an not well-defined iconographic semiology, they often raise problems with differential diagnosis from kidney masses, although they are often big size lessions. We report a patients with incidentally diagnosis of big solid left renal mass, who underwent radical nephrectomy resulting kidney pelvis leiomyoma. Diagnostic, histological and therapeutic aspects are briefly review in literature. Emphasis is made on the relevance of a high index suspicion considering big solid asymptomatic renal masses in middle-age women. Specially in renal tumors with well-defined limits and abscence of locoregional and systemic dissemination. We emphasized usefulness of Magnetic Angioresonance, immunohystochemical test and conservative surgery opportunity in small renal leiomyomas preoperatively confirmed.

[Giant inguinoscrotal bladder hernia associated with a bladder tumor]. / Hernia vesical inguinoescrotal gigante asociada a tumor vesical.

Inguinoscrotal bladder hernias are uncommon clinical facts more predominant in males aged between 50 and 70. This entity has no specific clinical character and diagnosis usually happens in the course of surgical repair of inguinal hernia. In about 3%-10% cases, it appears associated to inguinal hernia. Discussion of two case-reports of patients with giant inguinoscrotal bladder hernia; one patient with synchronous association to bladder transitional carcinoma. The literature on the clinical, diagnostic and therapeutic aspects is revised. The high index of suspicion for making a pre-operative diagnosis, specially in aged patients with inguinal hernia and expanded prostate signs and symptoms is highlighted. Emphasis is placed on the need for surgical hernia repair prior to prostate and/or bladder transurethral surgery.

[Testicular epidermoid cysts. Report of 2 cases]. / Quistes epidermoides testiculares. A propósito de dos observaciones.

Testicular epidermoid cysts are benign tumours which account for less than 1% of all testicular tumours. Their uncertain histogenesis, difficult pre-operative diagnosis and controversial therapeutic approach are at the base of this paper. Report on two patients, 20- and 21-year old, with testicular epidermoid cysts treated by inguinal radical orchiectomy and tumorectomy, respectively. Literature review focused on the diagnostic and therapeutic aspects. Emphasis on the relevance of ultrasound for pre-operative diagnosis. We also advocate for a conservative management if their presence is suspected or in the presence of negative tumoral markers.

[Pyourachal cyst. A diagnosis to keep in mind]. / Quiste piouracal. Un diagnóstico a tener en cuenta.

Urachal conditions are relatively exceptional, cystic formations being the most commonly reported. Urachal cysts remain silent and are not diagnosed except for the presence of associated complications such as: infection, lithiasis, re-permeabilization and malignant degeneration. This paper presents one patient with an infected urachal cyst (pyourachal) which required surgical exeresis. A literature revision is made of the clinical, diagnostic and therapeutic aspects. Emphasis is made on the relevance of a high index of suspicion considering its small incidence, the absence of specific clinical sings and the possibility of mimicking different abdominal pictures. Also the usefulness of ultrasound and computerized axial tomography in the diagnosis, and the need for surgical exeresis, including a vesical cup rim, are emphasised.

[Synchronous association of Bellini collecting ducts and pyelic transitional cell carcinoma]. / Asociación sincrónica de carcinoma de los conductos colectores de Bellini y carcinoma transicional pielico.

Bellini's collecting ducts carcinoma represent a subgroup within renal carcinoma with an incidence of 0.4 to 2% of all renal tumours. The collecting ducts share their embryological origin in Wölf's duct with the calices, renal pelvis and ureter. This common embryological origin could justify the association of carcinoma originated in the collecting ducts with transitional urothelial carcinoma. This paper contributes two patients with Bellini's collecting ducts carcinoma associated to "in situ" carcinoma and transitional papillar carcinoma in the adjacent renal pelvis respectively. The authors review the diagnostic, pathoanatomical and therapeutical aspects found in the literature. A high index of suspicion is required to diagnose a case of Bellini's carcinoma in the face of predominantly central-medullar renal solid lesions, with infiltrating growth that causes morphological changes in the excretory system without deforming the external renal outline. The authors highlight the value of immunohistochemical studies to reach a diagnosis, considering the natural history and the sombre prognosis of this uncommon renal neoplasia.

[Symptomatic renal leiomyoma]. / El leiomioma renal sintomático.

Symptomatic leiomyoma of the kidney is an uncommon, large, solitary, benign mesenchymatous tumor that must be distinguished from renal cell carcinoma. However, the diagnostic imaging techniques currently available do not permit determining the benign nature of the lesion with precision and radical excision of the compromised kidney is warranted, as in the case described herein.

Hemodynamic and electrophysiological actions of cocaine. Effects of sodium bicarbonate as an antidote in dogs.

BACKGROUND: Cocaine abuse has been implicated as a cause of death due to sudden cardiac arrest. METHODS AND RESULTS: We examined the hemodynamic and electrophysiological effects of cocaine administered as a series of 5-mg/kg i.v. boluses coupled with a continuous infusion in anesthetized dogs. Sodium bicarbonate (50 meq i.v.) was administered as a potential antidote in 11 of 15 dogs, and intravenous 5% dextrose was given in the remaining four. In a dose-dependent fashion, cocaine significantly decreased blood pressure, coronary blood flow, and cardiac output; increased PR, QRS, QT, and QTc intervals and sinus cycle length; and increased ventricular effective refractory period and dispersion of ventricular refractoriness. No afterdepolarizations were noted in the monophasic action potential recording. Nonsustained monomorphic ventricular tachycardia occurred spontaneously in two dogs, and sustained ventricular tachycardia could be induced by programmed stimulation at the end of the dosing protocol in five of 11 animals. Sodium bicarbonate promptly decreased cocaine-induced QRS prolongation to nearly that measured at baseline but had no effect on the other electrocardiographic or hemodynamic variables. In one dog, sodium bicarbonate administration was associated with reversion of ventricular tachycardia to sinus rhythm. CONCLUSIONS: We conclude that high-dose cocaine possesses negative inotropic and potent type I electrophysiological effects. Sodium bicarbonate selectively reversed cocaine-induced QRS prolongation and may be a useful treatment of ventricular arrhythmias associated with slowed ventricular conduction in the setting of cocaine overdose.

Long-term follow-up in patients with incessant ventricular tachycardia.

Seventeen patients with coronary artery disease, idiopathic dilated cardiomyopathy or no organic heart disease who presented with incessant ventricular tachycardia (VT) were studied and followed for a mean period of 51 +/- 35 months. In these patients the incessant VT included greater than or equal to 3 episodes of sustained VT at a rate of greater than or equal to 120 beats/min and frequent episodes of nonsustained VT over a 24-hour period. No patient had electrolyte disorder, prolonged QT interval, drug-induced arrhythmia or myocardial infarction less than 2 weeks old. Six patients died within 27 months of follow-up; 4 from sudden death and 2 from acute myocardial infarction. Three of the 11 surviving patients had remission of their VT within 1 week after the diagnosis of incessant VT. In 3 other patients in whom antiarrhythmic drugs were discontinued during follow-up because of adverse effects of the drugs or other medical reasons, 2 were found in remission. In the remaining 5 alive patients, deliberate attempts were made to discontinue the antiarrhythmic drugs; 4 of these patients were found in remission when the drugs were discontinued. Thus, 9 of these patients (53%) with incessant VT had remission over a mean follow-up of 55 +/- 34 months after discontinuation of the antiarrhythmic drugs. The probability of remission in patients surviving incessant VT warrants trials of discontinuation of antiarrhythmic drugs in these patients.

The predictive value of electrophysiologic studies in untreated patients with Wolff-Parkinson-White syndrome.

The ability of invasive electrophysiologic studies to predict future arrhythmic events in patients with minimally symptomatic Wolff-Parkinson-White syndrome is not known. To assess this ability, 42 patients with evidence of atrioventricular (AV) pre-excitation on the surface electrocardiogram underwent electrophysiologic studies and were then followed up as outpatients taking no medications. The patients were classified into three groups on the basis of prestudy symptoms: group I, 15 asymptomatic patients; group II, 10 patients with infrequent symptoms but no documented arrhythmias; and group III, 17 patients with one documented episode of supraventricular tachycardia or atrial fibrillation, or both. At electrophysiologic study, the number of patients with short anterograde accessory pathway effective refractory periods and rapid ventricular responses during induced atrial fibrillation did not differ statistically among the three groups. During a mean follow-up period of 7.5 +/- 4.9 years, 11 of the 42 patients had documented arrhythmias: 2 patients from group II and 2 patients from group III had supraventricular tachycardia and 7 patients from group III had atrial fibrillation. All nine patients from group III with subsequent arrhythmias had had clinical atrial fibrillation before study. No patient from group I had an arrhythmia during follow-up. There were no episodes of ventricular fibrillation or sudden cardiac death during follow-up in any of the patients. The only predischarge variables that correlated with the subsequent occurrence of arrhythmias were a history of documented arrhythmias before electrophysiologic study (p less than 0.01) and inducible supraventricular tachycardia at electrophysiologic study (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Worsening of ventricular tachycardia by amiodarone.

The details of worsening of ventricular tachycardia in 8 (4.1%) of 194 patients receiving treatment with amiodarone are reported. Two forms of amiodarone-induced tachycardia were recognized: first, the development of new tachycardias (three patients) and second, a change in the pattern of recurrence of clinical tachycardia (five patients). In retrospect, the time from the initiation of amiodarone to the initial documentation of worsening ranged from 1 to 23 days (mean +/- SD, 9.4 +/- 8.2 days) and the time from the initiation of therapy to the recognition of worsening ranged from 6 to 26 days (14.6 +/- 10.1 days). Seven patients survived the worsening of tachycardia and one died. The total dose of amiodarone received and the duration of administration did not correlate with time to manifestation or time to resolution of worsening. This report emphasizes that worsening of ventricular tachycardia as a result of amiodarone is often difficult to differentiate from inadequate drug loading or early recurrence of 2 patient's clinical tachycardia. Further, because of the pharmacokinetics of the drug, the manifestations of worsening may be prolonged. In the cases reported, it ranged from 2 to 26 days (7.9 +/- 8.3 days), which is longer than previously reported. Because of the potential for amiodarone to cause life-threatening worsening of ventricular tachycardia and in accordance with current results, a period of in-hospital monitoring of at least 10 days at the start of therapy with amiodarone is recommended.

Interaction of steady-state procainamide with H2-receptor antagonists cimetidine and ranitidine.

This study was designed to compare the effects of equivalent therapeutic doses of two H2 antagonists, cimetidine and ranitidine, on steady-state procainamide pharmacokinetics. Six healthy men were given 500 mg sustained-release procainamide every 6 h, for a total of 13 doses, on three occasions. Subjects were randomly assigned to three treatments by a Latin-square design: cimetidine 1,200 mg/day, ranitidine 300 mg/day, and no H2-receptor antagonist (control) for 4 days. Cimetidine significantly increased the procainamide area under the serum concentration-time curve by 43%, decreased renal clearance by 36%, and decreased the ratio of systemic clearance of procainamide to bioavailability by 28%. Ranitidine did not significantly alter procainamide steady-state pharmacokinetics.

Flecainide-induced sustained ventricular tachycardia successfully treated with lidocaine.

A 69-year-old man had new sustained ventricular tachycardia caused by flecainide which promptly responded to intravenous lidocaine therapy. Discontinuation of the lidocaine infusion resulted in the reappearance of ventricular tachycardia which again immediately terminated after lidocaine was given. In this case, lidocaine effectively reversed the proarrhythmic effects of flecainide.