Fonament de l'arc de Sant Martí

Aquest fenomen té lloc per la reflexió i la refracció de la llum del Sol a traves de les gotes d'aigua que es troben en suspensió en l'aire. L'arc de Sant Martí tant sols es pot veure en una determinada direcció. Això es pot explicar físicament pel fet que el joc de reflexions i refraccions de la llum natural té una direcció privilegiada que és la mateixa per a tots els feixos de llum incident

Withdrawal of maintenance therapy for cytomegalovirus retinitis in AIDS patients exhibiting immunological response to HAART

BACKGROUND: Before the introduction of highly active antiretroviral therapy (HAART), CMV retinitis was a common complication in patients with advanced HIV disease and the therapy was well established; it consisted of an induction phase to control the infection with ganciclovir, followed by a lifelong maintenance phase to avoid or delay relapses. METHODS: To determine the safety of CMV maintenance therapy withdrawal in patients with immune recovery after HAART, 35 patients with treated CMV retinitis, on maintenance therapy, with CD4+ cell count greater than 100 cells/mm³ for at least three months, but almost all patients presented these values for more than six months and viral load < 30000 copies/mL, were prospectively evaluated for the recurrence of CMV disease. Maintenance therapy was withdrawal at inclusion, and patients were monitored for at least 48 weeks by clinical and ophthalmologic evaluations, and by determination of CMV viremia markers (antigenemia-pp65), CD4+/CD8+ counts and plasma HIV RNA levels. Lymphoproliferative assays were performed on 26/35 patients. RESULTS: From 35 patients included, only one had confirmed reactivation of CMV retinitis, at day 120 of follow-up. No patient returned positive antigenemia tests. No correlation between lymphoproliferative assays and CD4+ counts was observed. CONCLUSION: CMV retinitis maintenance therapy discontinuation is safe for those patients with quantitative immune recovery after HAART

Você conhece esta síndrome? Do you know this syndrome?

A síndrome Leopard é distúrbio autossômico dominante de forte penetrância e expressividade variável. O epônimo Leopard foi criado em 1969 como regra mnemônica, ressaltando as características mais marcantes da síndrome: lentiginose, distúrbios de condução no ECG, hipertelorismo ocular, estenose pulmonar, anormalidade genital, retardo do crescimento e déficit auditivo sensorial. Relata-se o caso de uma menina de 15 anos com características da síndrome Leopard e discutem-se suas principais manifestações clínicas e genéticas.LEOPARD syndrome is a dominant autosomal anomaly, with high penetrance and markedly variable expression. The acronym LEOPARD was coined in 1969 as a mnemonic rule, highlighting the major features of this syndrome: lentigines, ECG conduction abnormalities, ocular hypertelorism, pulmonic stenosis, abnormal genitalia, retardation of growth, and sensorineural deafness. We report the case of a 15-year-old girl with characteristics of LEOPARD syndrome and further discuss the main clinical and genetical features of the disorder