Positive Feedback Keeps Duration of Mitosis Temporally Insulated from Upstream Cell-Cycle Events

Cell division is characterized by a sequence of events by which a cell gives rise to two daughter cells. Quantitative measurements of cell-cycle dynamics in single cells showed that despite variability in G1-, S-, and G2 phases, duration of mitosis is short and remarkably constant. Surprisingly, there is no correlation between cell-cycle length and mitotic duration, suggesting that mitosis is temporally insulated from variability in earlier cell-cycle phases. By combining live cell imaging and computational modeling, we showed that positive feedback is the molecular mechanism underlying the temporal insulation of mitosis. Perturbing positive feedback gave rise to a sluggish, variable entry and progression through mitosis and uncoupled duration of mitosis from variability in cell cycle length. We show that positive feedback is important to keep mitosis short, constant, and temporally insulated and anticipate it might be a commonly used regulatory strategy to create modularity in other biological systems

Peritubular Capillaries C4d Deposits in Renal Allograft Biopsies and Anti HLA I/II Alloantibodies Screening. Incidence and Clinical Importance

Aim: To characterise clinically the patients with C4d in peritubular capillaries deposits (C4dPTCD) and/or circulating anti-HLA class I/II alloantibodies. To determine the correlation between positive C4dPTCD and circulating anti-HLA class I/II alloantibodies during episodes of graft dysfunction. Subjects and Methods: C4d staining was performed in biopsies with available frozen tissue obtained between January 2004 and December 2006. The study was prospective from March 2005, when a serum sample was obtained at the time of biopsy to detect circulating anti-HLA class I/II alloantibodies. Results: We studied 109 biopsies in 86 cadaver renal transplant patients. Sixteen of these (14.7%) presented diffuse positive C4dPTCD. There was a 13.5% rate of +C4dPTCD incidence within the first six months of transplantation and 16% after six months (p>0.05). Half of the +C4dPTCD in the first six months was associated with acute humoral rejection. After six months, the majority of +C4dPTCD (n=7/8) was present in biopsies with evidence of interstitial fibrosis/tubular atrophy and/or transplant glomerulopathy. The C4dPTCD was more frequent in patients with positive anti-HCV antibodies(p<0.0001), a previous renal transplant (p=0.007), and with a panel reactivity antibody (PRA) ≥ 50%(p=0.0098). The anti-HCV+ patients had longer time on dialysis (p=0.0019) and higher PRA(p=0.005). Circulating anti-HLA I/II alloantibodies were screened in 46 serum samples. They were positive in 10.9% of samples, all obtained after six months post transplant. Circulating alloantibodies were absent in 92.5% of the C4d negative biopsies. Conclusion: We found an association between the presence of C4dPTCD and 2nd transplant recipients,higher PRA and the presence of anti-HCV antibodies. The presence of HCV antibodies is not a risk factor for C4dPTCD per se, but appears to reflect longer time on dialysis and presensitisation. In renal dysfunction a negative alloantibody screening is associated with a reduced risk of C4dPTCD (<10%)

Splenosis. A diagnosis to be considered

The term splenosis applies to the autotransplanted splenic tissue resulting from seeding in the context of past splenic trauma or surgery. We report a 42-year-old man with a history of splenectomy observed for an incidentally found retrovesical mass thought to be an ectopic testicle. The abdominal laparotomy revealed multiple focuses of pelvic splenosis. As splenosis can be diagnosed through specific imaging studies one should always consider it in differential diagnosis of a mass discovered years after splenic surgery or trauma

Amiloidose. Caracterização Epidemiológica, Clínica e Morfológica

Introdução: A amiloidose é uma doença sistémica, cujo diagnóstico cabe frequentemente ao nefrologista. O tipo de amiloidose varia de acordo com o grau de desenvolvimento do país, com maior prevalência de amiloidose AL nos países ricos. Material e métodos: Revisão retrospectiva de todas as biopsias de rim nativo avaliadas no serviço entre 1981 e 2008. Caracterização clínica dos doentes à data da biópsia. Avaliação morfológica qualitativa do tipo de substância amiloíde por imunofluorescência e imunoperoxidase. Avaliação semi-quantitativa do grau de depósitos de acordo com a sua localização; grau de glomeruloesclerose e fibrose tubulo -interstical. Resultados: Neste período de 28 anos, observámos 202 biópsias positivas para substância amiloíde (3,5% de 5797) num total de 197 doentes (54,4% homens vs 45,5 mulheres), com idade mediana de 59,5 ± 15,6 anos. A maioria (68%) dos doentes foi biopsada por síndrome nefrótico. A insuficiência renal e as alterações assintomáticas urinárias foram os outros principais motivos de biopsia em 15 % e 7% dos casos, respectivamente. Os doentes na altura da biopsia apresentavam proteinúria mediana de 5 g/dia ± 5,4 (n=144) e creatinina mediana de 1,3 ± 1,7 mg/dl (n=150). As amiloidoses foram classificadas como AA em 51% dos casos, AL em 31,6% (25,5% lambda e 5,9% kappa) e Polineuropatia Amiloidótica Familiar em 3,5%. Não foi possível a caracterização do tipo de amilóide, por dificuldade técnica, em 12,8% das biópsias. A amiloidose revelou-se a terceira causa de síndrome nefrótico nos doentes com mais de 65 anos. Os doentes com amiloidose primária são significativamente mais velhos do que aqueles com amiloidose secundária ou PAF (65,2 vs 53,7 vs 52,7 respectivamente, p <0,05).Verificámos uma diminuição da incidência das amiloidoses AA com aumento das AL, com inversão do predomínio das AA em relação as AL a partir de 1995. Em termos morfológicos, a maioria das biópsias caracteriza-se por deposição marcada de amilóide no glomérulo (30% com +++) e nos vasos (40% com +++), com escassa deposição a nível intersticial cortical (60% sem depósitos) e medular (50% sem depósitos). Estudámos as possíveis relações entre manifestações clínicas e morfologia renal. Verificámos uma correlação positiva entre creatinina e grau de fibrose e/ou grau de deposição intersticial. Não encontrámos relação entre proteinúria e grau/local de deposição de amilóide. Conclusões: Actualmente, em Portugal, predomina a amiloidose AL, que surge em doentes mais idosos e se manifesta mais frequentemente por sindrome nefrótico. A função renal a data da biópsia correlaciona-se com o grau de fibrose tubulo-interstical renal

Anti-MuSK-positive myasthenia gravis diagnosed during pregnancy: New challenges for an old disease

Myasthenia gravis is an autoimmune disorder affecting predominantly women in their reproductive age. The course of the disease during pregnancy is unpredictable, although it is more difficult to manage earlier in the gestation. Myasthenia gravis with antibodies against the muscle-specific receptor tyrosine kinase (anti-MuSK) has been described as a subtype of disease with more localised clinical features and a poorer response to treatment than acetylcholine receptor antibody (anti-AChR)-positive patients. Few cases have been reported in pregnant women, with deliveries being performed mainly by caesarean section. We report a successful case of vaginal delivery and describe our experience providing the first review of the management of this subtype of disease during pregnancy

Optical Coherence Tomography-Guided Full Plastic Jacket in Spontaneous Coronary Artery Dissection

info:eu-repo/semantics/publishedVersio

Fenómeno de Raynaud com isquémia acral – um caso de crioglobulinémia essencial

info:eu-repo/semantics/publishedVersio

Right Atrial Thrombus: a Rare Presentation of Plasminogen Activator Inhibitor Deficiency

A presença de trombos móveis na aurícula direita são fenómenos raros, mas associados a uma elevada mortalidade. Apesar de a ecocardiografia ter permitido avanços no seu diagnóstico, a sua abordagem continua a ser motivo de debate. Neste artigo apresentamos o caso de uma doente do sexo feminino, de 24 anos, com antecedentes de tabagismo, obesidade e sob terapêutica anovulatória que recorre ao serviço de urgência por cansaço fácil e tosse com expetoração hemoptoica. O ecocardiograma transtorácico revelou massa, móvel, multilobulada de grandes dimensões na aurícula direita, condicionando abertura da válvula tricúspide. Perante episódios recorrentes de embolia pulmonar, foi submetida a cirurgia cardíaca com exérese da massa, sendo o resultado anatomopatológico compatível com trombo organizado com calcificação. O estudo genético revelou homozigotia para a variante alélica PAI-1:-675G >A(4G/4G) do inibidor do ativador do plasminogénio e heterozigotia para a variante alélica MTHFR 1298 A/C da 5,10-metilenotetrahidrofolato redutase