Modulation of persistent current in graphene quantum rings.

We investigate the effect of long-range impurity potentials on the persistent current of graphene quantum rings in the presence of an uniform perpendicular magnetic field. The impurity potentials are modeled as finite regions of the ring with a definite length. We show that, due to the relativistic and massless character of the charge carriers in graphene, the effect of such non-uniform potentials on the energy spectrum and on the persistent current of the rings can be reliably modeled by assuming a non-perturbed ring and including an additional phase due to the interaction of the charge carriers with the potential. In addition, the results show the presence of localized states in the impurity regions. Moreover, we show that for the case of a potential created by a p-n-p junction, the persistent current can be modulated by controlling the voltage at the junction.

Optical conductivity of curved graphene.

We compute the optical conductivity for an out-of-plane deformation in graphene using an approach based on solutions of the Dirac equation in curved space. Different examples of periodic deformations along one direction translates into an enhancement of the optical conductivity peaks in the region of the far- and mid-infrared frequencies for periodicities ∼100 nm. The width and position of the peaks can be changed by dialling the parameters of the deformation profiles. The enhancement of the optical conductivity is due to intraband transitions and the translational invariance breaking in the geometrically deformed background. Furthermore, we derive an analytical solution of the Dirac equation in a curved space for a general deformation along one spatial direction. For this class of geometries, it is shown that curvature induces an extra phase in the electron wave function, which can also be explored to produce interference devices of the Aharonov-Bohm type.

Effects of surgical removal of mandibular third molar on the periodontium of the second molar.

OBJECTIVE: The effects on periodontal tissues of adjacent second molars after semi-impacted mandibular third molar surgery were evaluated. The influence of flap design was studied. METHODS: Twenty volunteers randomly underwent the three-cornered flap technique (group A) or the distal wedge flap technique (group B). The periodontal probing depth was measured by using a 'Williams'-type probe just prior to surgery and three months post-operatively. Six sites, mesio-buccal, buccal, disto-buccal, disto-lingual, lingual and mesio-lingual, around the second molar were selected for measurement. Kruskal-Wallis test and Dunn test (post hoc) were used. Significance level was set at 5%. RESULTS: There were no complications (oedema, alveolitis, etc.) in any of the patients of the study. The results showed that both methods caused shallow pocket depth (P > 0.05) and there were no statistically significant differences between the flap techniques (P > 0.05). Flap design was not an important factor affecting the periodontal status of the second molar. CONCLUSION: The decision to use any of the various flap designs for access to mandibular third molars should be based on operator preference rather than on the assumption that periodontal health of the adjacent second molar will be improved.

Leiomioma cutáneo zosteriforme. Tratamiento satisfactorio con doxazosina oral / Zosteriform cutaneous leiomyoma. Satisfactory treatment with oral doxazosine

Describimos el caso de un paciente varón de 50 años de edad que presentaba leiomioma cutáneo zosteriforme de región facial izquierda, intensamente doloroso, y que obtuvo mejoría clínica espectacular tras la administración diaria de 4 mg de doxazosina oral. Este tratamiento fue bien tolerado y no presentó ningún efecto adverso asociado. En la literatura médica de habla inglesa se han publicado sólo dos casos tratados con doxazosina que demostraron excelente resultado terapéutico

We report a 50-year-old man that presented a zosteriform cutaneous leiomyoma in the left facial region, intensely painful, that showed great improvement after the administration of a daily dose of 4 mg of oral doxasozine. The therapy was well tolerated and did not present any associated adverse effect. In the English medical literature only two cases successfully treated with doxasozine have been reported

[Zosteriform cutaneous leiomyoma. Satisfactory treatment with oral doxazosin]. / Leiomioma cutáneo zosteriforme. Tratamiento satisfactorio con doxazosina oral.

We report a 50-year-old man that presented a zosteriform cutaneous leiomyoma in the left facial region, intensely painful, that showed great improvement after the administration of a daily dose of 4 mg of oral doxasozin. The therapy was well tolerated and did not present any associated adverse effect. In the English medical literature only two cases successfully treated with doxasozin have been reported.

Liquen escrofulosorum y tuberculosis osteomuscular multifocal / Lichen scrofulosorum and multifocal osteomuscular tuberculosis

El liquen escrofulosorum es una forma infrecuente de tubercúlides caracterizada por pequeñas pápulas liquenoides en tronco y extremidades que surgen fundamentalmente en niños y adultos jóvenes con tuberculosis ósea o ganglionar.Hemos estudiado un caso de liquen escrofulosorum que apareció dos años después de una tuberculosis osteomuscular multifocal. La tinción de Ziehl-Neelsen, el cultivo y la PCR para Mycobacterium tuberculosis en fresco fueron negativas, descartándose la pérdida de sensibilidad de la PCR relacionada con la inclusión en parafina. El cuadro respondió en pocas semanas al tratamiento antituberculoso, si bien, aconsejamos completar la pauta de la Sociedad Torácica Americana. (AU)

Granuloma inguinal. Descripción de un caso / Inguinal granuloma. Report of a case

El granuloma inguinal o donovanosis es una infección granulomatosa crónica producida por calymmatobacterium granulomatis, considerada enfermedad venérea clásica, típica de zonas tropicales o subtropicales y excepcional en nuestro país. Es un proceso poco contagioso que evoluciona de forma crónica con elementos vegetantes en zona genital y/o perigenital, sin adenopatías regionales. El agente etiológico puede demostrarse en el estudio dermatopatológico, comprobándose los cuerpos de Donovan mediante las tinciones de Giemsa o Whartin-Starry.El caso de granuloma inguinal que justifica este trabajo apareció en varón caucásico que mantuvo contacto sexual con mujer procedente de las Antillas Holandesas. Se le realizaron múltiples tratamientos antibióticos hasta llegar a la curación aunque posteriormente requirió tratamiento quirúrgico para resolver la fibrosis y el linfoedema residual (AU)

Percutaneous handling of coronary lesions >20mm through stents. Is there a first choice strategy?

OBJECTIVE - This study compared the early and late results of the use of one single stent with those of the use of multiple stents in patients with lesions longer than 20mm. METHODS - Prospective assessment of patients electively treated with stents, with optimal stent deployment and followed-up for more than 3 months. From February '94 to January '98, 215 patients with lesions >20mm were treated. These patients were divided into 2 groups as follows: Group A - 105 patients (49%) with one stent implanted; Group B - 110 patients (51%) with multiple stents implanted. RESULTS - The mean length of the lesions was 26mm in group A (21-48mm) versus 29mm in group B (21-52mm) (p=0.01). Major complications occurred in one patient (0.9%) in group A (subacute thrombosis, myocardial infarctionand death) and in 2 patients (1.8%) in group B (one emergency surgery and one myocardial infarction) (p=NS). The results of the late follow-up period (>6 months) were similar for both groups (group A = 82% vs group B = 76%; p=NS), and we observed an event-free survical in 89% of the patients in group A and in 91% of the patients in group B (p=NS). Angina (group A = 11% vs group B = 7%) and lesion revascularization (group A = 5% vs group B = 6%; p=NS) also occurred in a similar percentage. No infarction or death was observed in the late follow-up period; restenosis was identified in 33% and 29% of the patients in groups A and B, respectively (p=NS). CONCLUSION - The results obtained using one stent and using multiple stents were similar; the greater cost-effectiveness of one stent implantation, however, seems to make this strategy the first choice.

[Influence of the clinical presentation on immediate and long-term results after rotational atherectomy]. / Influência do quadro clínico nos resultados imediatos e tardios após aterectomia rotacional.

PURPOSE: To analyse the influence of unstable coronary syndromes (UCS) in the early and late prognosis after rotational atherectomy (RA). METHODS: We treated 236 patients with RA between Aug/1992 and May/1996. Patients were divided into two groups: A) stable coronary syndromes 120 (51%) patients; B) UCS: 116 (49%) patients. DEFINITIONS: 1) procedure success (PS)--lesion success in all locations were RA use was attempted, without a major complication; 2) late coronary events (LCE)--angina, MI, additional revascularization or death. RESULTS: There was a significant predominance of age > 70 (A = 14% x B = 24%, p = 0.03) in B and previous MI (A = 32% x B = 11%, p = 0.0001) in A. Other characteristics were similar in both groups, including complex lesions (type B2/C), which were observed in 77% A stenosis and 80% B lesions. PS was 95% in A and 92% in B (p = NS). In-hospital major complications were observed in 2.5% A and 4.3% B patients, (p = NS). One patient died in each group. A and B patients had similar time of follow-up. LCE occurred in 25% A and 39% B patients (p = 0.002). Recurrence of angina (36% x 23%; p = 0.01) and target lesion revascularization (29% x 18%; p = 0.03) were also more frequently required in B cases. CONCLUSION: This study suggests that UCS (group A) does not implicate in worse acute results after RA. However, UCS patients present greater incidence of late coronary events, particularly recurrence of angina and target-lesion revascularization.

[Inefficacy of diltiazem in restenosis prevention after coronary angioplasty]. / Ineficácia do diltiazem na prevenção da reestenose após angioplastia coronária.

PURPOSE: To evaluate the efficacy of diltiazem in preventing restenosis after balloon angioplasty (PTCA). METHODS: Eighty-nine patients who were undergone to successful PTCA, were divided them in 2 groups (G): A) 44 patients (50%) who received diltiazem (180 mg tid) immediately after PTCA and were kept on it for 6 months); B) 45 patients (50%) who received placebo. Fifty two lesions were dilated in GA and 54 in GB. Patients were excluded from analysis for several reasons, including: necessity of diltiazem or others calcium channel blockers use; heart failure, bradicardia, AV block of any degree, PTCA to chronic total occlusion, ostial lesions and AMI less than 30 days prior to PTCA. Patients were randomized to either the active drug or placebo in a double blind fashion. Restenosis was defined as a 50% lesion. Patients underwent late angiography either at 6 months or sooner if clinically indicated. RESULTS: Both G were similar to age > 70 years (A = 7% vs B = 4%-p = NS), sex (A = 13% vs B = 11%-p = NS), stable angina (A = 43% vs B = 51%), unstable angina (A = 57% vs B = 49%-p = NS) and single vessel (A = 91% vs B = 87%-p = NS) or multivessel (A = 9% vs B = 13%-p = NS) PTCA. We studied 39/44 (89%) patients in GA and 43/45 (96%) in GB (p = NS). We observed restenosis in 17/39 (43%) in GA and 16/43 (37%) in GB (p = NS). The restenosis rate per lesion was 39% in GA and 31% in GB (p = NS). CONCLUSION: Diltiazem was ineffective in the prevention of restenosis following PTCA.

[Heparin in coronary angioplasty. Randomized study in cases with low risk of acute occlusion]. / Heparina na angioplastia coronária. Estudo randomizado em casos com baixo risco para lclusão aguda.

PURPOSE: To assess the efficacy of heparin in preventing the abrupt closure after coronary angioplasty in low risk patients for this phenomenon. METHODS: In the last 4 years, 525 patients successfully dilated were randomized to receive intravenous heparin (n = 264) or not (n = 261) after the angioplasty. The excluding criteria were contraindications for heparin and risk for abrupt closure (refractory unstable angina, primary coronary angioplasty in acute myocardial infarction, evidence of intracoronary thrombus, intimal tear after the procedure and cases of chronic total occlusions). Both heparin and non heparin groups were similar in respect to female sex (15% x 17%; p = NS), age over 70 years old (7% x 9%; p = NS), previous myocardial infarction (26% x 24%; p = NS), multi-vessel procedures (4% x 7%; p = NS, stable angina (40% x 46%; p = NS), unstable angina (52% x 48%; p = NS) and angioplasty after thrombolytic therapy (8% x 6%; p = NS). RESULTS: The overall incidence of abrupt closure was 2/525 (0.4%), with one case (0.4%) in each group. The in-hospital mortality was 1/525 (0.2%), which occurred in a non-heparin patient, due to a anterior myocardial infarction. Major complications occurred similarly in heparin and non-heparin groups (0.4%). Bleeding complications were observed more frequently in the heparin group (7% x 2%; p = 0.002). All of them were in the catheterization site and none required blood transfusion. Severe systemic bleeding were not observed. CONCLUSION: In patients regarded as low risk for abrupt closure, the incidence of this complication was really low (0.4%) and heparin probably do not prevent it.

[Outpatient heart catheterization. An analysis of experience accumulated over 10 months]. / Cateterismo cardíaco ambulatorial. Análise da experiência acumulada em 10 meses.

PURPOSE: To identify patients suitable for outpatient cardiac catheterization strategy, based on social aspects, risks and complications, for a 24 hour period. METHODS: In a series of 2.126 cases submitted to cardiac catheterization at the Instituto Dante Pazzanese de Cardiologia, between September 1990 and June 1991, were excluded: a) those over 75 years of age; b) the acute ischemic syndromes; c) those in NYHA functional class IV; d) patients who used 7 or 8 French femoral angiographic catheters; e) patients who had undergone general anesthesia, electrophysiological study or endomyocardial biopsy. After the procedure, the patients were observed for a 3 hour period and in the absence of any complication, they were discharged from the hospital, returning the next day for clinical evaluation. If any complication occurred it was registered. RESULTS: In a cohort of 719 eligible patients, 68% were male, with a mean age of 55.3 years. Sixty one per cent were in NYHA functional class I and most of them (80.8%) were studied by the brachial approach. Eighty-three per cent of the patients were submitted to coronary angiography, with 52% of them having coronary artery disease. Four hundred and fourteen patients were not discharged on the same day: 217 did not have their procedures finish after 6 p.m., 111 for social-economical reasons, 23 because of their physician's refuse, 8 because of left main coronary disease, 55 because of any kind of complication. All the 305 patients who were discharged on the same day, did not have shown any complication in the next day evaluation. CONCLUSION: Outpatient cardiac catheterization is a safe technique in selected patients, making possible the accomplishment of a greater number of procedures improving bed utilization and decreasing hospital costs.