Expression of Met protein in thyroid tumours.

Met protein is a transmembrane 190 kD heterodimer with tyrosine kinase activity, encoded by c-MET oncogene. It serves as a high affinity receptor for hepatocyte growth factor (HGF)/scatter factor (SF), a cytokine which stimulates cell proliferation, motility, and invasion. Expression of Met protein was investigated in 116 thyroid tumours using an anti-Met mouse monoclonal antibody (DQ-13) active on paraffin-embedded material. Reactivity for DQ-13 was observed in 77 per cent of papillary carcinomas, in 70 per cent of Hürthle cell tumours, and rarely in other tumours. The staining was either uniformly present throughout the tumour or limited to nests of infiltrating tumour cells. In some Hürthle cell tumours, prominent accumulation of the protein was observed in the Golgi area. Reactivity for Met protein was decreased or absent in poorly differentiated tumours and was not influenced by tumour size, presence of lymph node metastases, or age of the patient. Immunostaining for Ki-67 revealed that cytoplasmic accumulation of Met protein was not associated with enhanced proliferation of tumour cells. Overexpression of Met protein in thyroid papillary carcinoma may result in increased motility of tumour cells, which in turn may account for intraglandular multifocal dissemination and early lymph node metastasis

Prosthetic valve endocarditis after transcatheter aortic valve implantation: the incidence in a single-centre cohort and reflections on clinical, echocardiographic and prognostic features

Aims: Transcatheter aortic valve implantation (TAVI) has recently developed into an accepted alternative to conventional surgery in high-risk patients. According to current data, post-TAVI prosthetic valve endocarditis (PVE) seems to occur very rarely. Methods and results: We followed the first 180 consecutive patients who underwent TAVI at our institution to assess safety and efficacy of the procedure. During follow-up (median, 319 days), PVE was seen more frequently than expected. By applying modified Duke criteria five cases could be confirmed (four early-onset and one late-onset PVE, four cases with "definite diagnosis" and one with "possible diagnosis") representing an estimated PVE incidence of 3.4% at one year. Two patients died subsequently. Clinical summaries of all cases are reported and compared to previously published case reports. Conclusions: According to our hypothesis, PVE might be particularly difficult to diagnose after TAVI, whereas TAVI-specific elderly patients might be exceptionally vulnerable. There exists little experience of TEE interpretation in post-TAVI endocarditis which should possess unique characteristics regarding, e.g., valve dehiscence or abscess formation. Therefore, echocardiography as a diagnostic tool often remains initially inconclusive. Because of incongruence between prosthetic device and calcified native aortic valve, some degree of paravalvular leak is common after TAVI. These paravalvular leaks as a nidus for infection, advanced age and abundant comorbidities might predispose TAVI patients for infective endocarditis