[Refractory thrombotic thrombocytopenic purpura revealing an epiglotis neoplasia]. / Purpura thrombotique thrombocytopénique réfractaire révélant un cancer de l'épiglotte.

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy with neurological disorder which incidence is relatively rare. Since the discovery of the ADAMTS 13 in 1996 and the changes in the treatment (plasma exchanges and rituximab), the prognosis of the TTP has considerably improved. We report the case of a 60-year-old man with a refractory TTP. The subsequent discovery of an epiglottis neoplasia and its treatment saved the patient.

Functional determinants of the Epstein-Barr virus protease.

Herpesvirus proteases are essential for the production of progeny virus. They cleave the assembly protein that fills the immature capsid in order to make place for the viral DNA. The recombinant protease of the human gamma-herpesvirus Epstein-Barr virus (EBV) was expressed in Escherichia coli and purified. Circular dichroism indicated that the protein was properly folded with a secondary structure content similar to that of other herpesvirus proteases. Gel filtration and sedimentation analysis indicated a fast monomer-dimer equilibrium of the protease with a K(d) of about 60 microM. This value was not influenced by glycerol but was lowered to 1.7 microM in the presence of 0.5 M sodium citrate. We also developed an HPLC-based enzymatic assay using a 20 amino acid residue synthetic peptide substrate derived from one of the viral target sequences for the protease. We found that conditions that stabilised the dimer also led to a higher enzymatic activity. Through sequential deletion of amino acid residues from either side of the cleavage site, the minimal peptide substrate for the protease was determined as P5-P2'. This minimal sequence is shorter than that for other herpesvirus proteases. The implications of our findings are discussed with reference to the viral life-cycle. These results are the first ever published on the EBV protease and represent a first step towards the development of protease inhibitors.

How valid is emergency liver transplantation for acute liver necrosis in patients with multiple-organ failure?

Multiple-organ failure (MOF), defined as the failure of initially uninvolved organs, is the final step of definitive and massive liver necrosis. Emergency liver transplantation (ELT) has radically modified the outcome of acute liver failure and early primary graft failure, but the results of ELT in cases of MOF are unknown. From May 1988 to June 1993, 243 patients underwent a liver transplantation (LT). Thirty-seven patients (15.2%) who had an acute liver necrosis complicated by a MOF underwent an ELT. Twenty-one patients were children. An emergency retransplantation was performed in 16 patients. Three or 4 organ-system failures (OSF) were present in 13 patients. Before ELT, the mean Acute Physiology and Chronic Health Evaluation (APACHE) II score was 26.3 +/- 5.1. Six-month and 1-year survival rates were 37.8% and 25.9%, respectively, after ELT complicated by MOF, and 78% and 73.5%, respectively, in other cases of LT. Twenty-six patients had surgical complications (70%), whereas thirty-one patients had medical complications (84%). Twenty-two patients died during the postoperative period (60%). Before ELT, infection (P < .05), cardiovascular failure (P < .03), and more than two OSF (P < .05) were more frequent in patients who died after intervention. The APACHE II score (P < .05) and the length of stay in the intensive care unit before ELT (P < .05) were lower among survivors. In the context of liver allograft shortage, our results suggest that an ELT should not be performed in patients with cardiac failure, more than two OSF, or an APACHE II score higher than 30.

Structure of influenza virus ribonucleoprotein particles. II. Purified RNA-free influenza virus ribonucleoprotein forms structures that are indistinguishable from the intact influenza virus ribonucleoprotein particles.

Influenza virus nucleoprotein (NP) was purified from the virus and found to be virtually free from RNA. The morphology of the negatively stained NP was studied using electron microscopy. The monomer protein was found to be a small rod with dimensions of 62 by 35 A. However, most of the protein was found to exist in polymeric forms ranging from trimers to large structures that were morphologically indistinguishable from the intact viral RNP. Each monomer has two sites for NP-NP contacts at one extremity of the rod. The consequences of this finding for crystallization studies, for in vitro studies on NP-RNA interactions and the possible consequences for in vivo ribonucleoprotein particle assembly are discussed.

Metastatic endocrine tumors: is there a place for liver transplantation?

The authors describe their experience with liver transplantation (OLT) for metastatic endocrine tumors (MET) in order to determine reasonable indications for OLT in patients with this disease. Removal of the primary lesion and subsequent liver transplantation were performed in two separate procedures in all patients except one. Only those patients suffering from objective tumor progression and symptoms with no evidence of extrahepatic spread after complete work-up (including endoscopic ultrasonography (US) and 123I-labeled Tyr3-octreotide body scanning) underwent liver transplantation. Fifteen patients were referred for liver transplantation. Seven patients were excluded either because of stability of liver metastases (n = 3), extrahepatic spread, general contraindication (n = 2), or feasibility of aggressive surgical resection (n = 2). Liver transplantation was undertaken in eight patients with carcinoid tumor (n = 4), gastrinoma (n = 3) and glucagonoma (n = 1). Three patients did not survive the surgical procedure itself, whereas two additional patients died from chronic rejection or from recurrent disease. Three patients who received transplants for metastatic carcinoid tumor are alive without biochemical or imaging evidence of disease recurrence at 6, 15, and 52 months. The best indication for transplantation seems to be patients with metastases restricted to the liver and unresponsive to adjuvant therapy after aggressive surgical resection including excision of the primary lesion and reduction of hepatic metastases. In such highly-selected patients, liver transplantation remains a high-risk operation, but it can yield long-term survival.

Structure of influenza virus RNP. I. Influenza virus nucleoprotein melts secondary structure in panhandle RNA and exposes the bases to the solvent.

The influenza virus genome consists of eight segments of negative-sense RNA, i.e. the viral (v) RNA forms the template for the mRNA. Each segment is encapsidated by the viral nucleoprotein to form a ribonucleoprotein (RNP) particle and each RNP carries its own polymerase complex. We studied the interaction of purified nucleoprotein with RNA in vitro, by using a variety of enzymatic and chemical probes for RNA conformation. Our results suggest that the nucleoprotein binds to the vRNA backbone without apparent sequence specificity, exposing the bases to the outside and melting all secondary structure. In this way, the viral polymerase may transcribe the RNA without the need for dissociating the nucleoprotein and without being stopped by RNA secondary structure, and the viral RNPs are ready to start transcription as soon as they enter the host cell.

Dimerization of human immunodeficiency virus (type 1) RNA: stimulation by cations and possible mechanism.

The retroviral genome consists of two identical RNA molecules joined close to their 5' ends by the dimer linkage structure. Recent findings indicated that retroviral RNA dimerization and encapsidation are probably related events during virion assembly. We studied the cation-induced dimerization of HIV-1 RNA and results indicate that all in vitro generated HIV-1 RNAs containing a 100 nucleotide domain downstream from the 5' splice site are able to dimerize. RNA dimerization depends on the concentration of RNA, mono- and multivalent cations, the size of the monovalent cation, temperature, and pH. Up to 75% of HIV-1 RNA is dimeric in the presence of spermidine. HIV-1 RNA dimer is fairly resistant to denaturing agents and unaffected by intercalating drugs. Antisense HIV-1 RNA does not dimerize but heterodimers can be formed between HIV-1 RNA and either MoMuLV or RSV RNA. Therefore retroviral RNA dimerization probably does not simply proceed through mechanisms involving Watson-Crick base-pairing. Neither adenine and cytosine protonation, nor quartets containing only guanines appear to determine the stability of the HIV-1 RNA dimer, while quartets involving both adenine(s) and guanine(s) could account for our results. A consensus sequence PuGGAPuA found in the putative dimerization-encapsidation region of all retroviral genomes examined may participate in the dimerization process.

[Liver transplantation in adults: postoperative management and development during the first months]. / Transplantation hépatique chez l'adulte: prise en charge postopératoire et évolution au cours des premiers mois.

Recent improvements in the results of orthotopic liver transplantation (OLT) have made this a well-accepted treatment for patients with severe hepatic failure. Current problems encountered following OLT are discussed. Immediate complications comprise surgical bleeding, primary graft non-function, and graft failure due to hepatic artery occlusion. Secondary complications are frequent. Surgical ones include biliary and vascular (hepatic artery thrombosis most often) problems, as well as intra-abdominal abscesses associated with gastrointestinal perforation, biliary leak, graft ischaemia or an infected haematoma. 40% of patients having undergone OLT will be reoperated on, 2/3 of them within 3 months. Non-surgical complications are mostly pulmonary. The risk of pneumonitis is increased by prolonged mechanical ventilation; it is always potentially disastrous in the immunosuppressed, transplanted patient. Hypertension is also often seen in the early postoperative period; it requires prompt treatment. Early renal impairment after OLT is common, and of better prognosis than late onset renal failure, which is generally associated with shock, graft failure, sepsis or use of nephrotoxic agents. Seizures, usually only one, occur in about 10% of patients; recovery is complete. Encephalopathy with intracranial oedema related to fulminant hepatitis has a worse prognosis, but survival figures are quite encouraging. Three type of rejection are described after OLT: 1) severe accelerated rejection (very rare), 2) acute rejection encountered in about 70% of patients over the first 3 months, and 3) late rejection, which can lead to the vanishing bile duct syndrome (VBDS). Diagnosis of rejection is made by liver biopsy. Prophylactic immunosuppression includes cyclosporin, methylprednisolone and azathioprine. Cyclosporin toxicity and drug interactions are reviewed. Treatment of acute rejection episodes comprises an initial bolus of high doses of corticoid drugs; if there is no response, antilymphocyte globulin or monoclonal antibodies may have to be used. Infection is the main cause of death following OLT. Early infections, mostly intra-abdominal and pulmonary, are bacterial or fungal. Vital (especially CMV) and other opportunistic infections occur generally after the second week. Retransplantation, carried out in 10 to 25% of patients, may be urgent in case of primary graft failure, or hepatic artery thrombosis associated with graft failure, or hepatic artery thrombosis associated with graft failure. Other indications are early graft rejection with severe hepatic dysfunction, chronic rejection with severe VBDS, and recurrence of the initial disease.