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The influenza virus hemagglutinin (HA) fusion protein has long been viewed as a "spring-loaded" fusion machine whereby activation at low pH initiates a rapid and irreversible cascade of conformational changes that drives the membrane fusion reaction. This mechanism has shaped our understanding of how type 1 viral fusion proteins function as a whole. Experimental limitations have hindered efforts to expand our mechanistic and structural understanding of viral membrane fusion. Here, we used pulse-labeling hydrogen/deuterium exchange mass spectrometry and cryo-electron tomography to monitor and characterize the structural dynamics of HA during fusion activation on intact virions. Our data reveal how concurrent reorganizations at the HA1 receptor binding domain interface and HA2 fusion subunit produce a dynamic fusion intermediate ensemble in full-length HA. The soluble HA ectodomain transitions directly to the postfusion state with no observable intermediate.

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AIM: To compare short and long-term results of pediatric liver transplantation (LT), utilizing segmental grafts from living donors (LD) vs. cadaveric (CAD) reduced size or split grafts. METHODS: A retrospective analysis of a single center experience (1993-2000), comparing the surgical outcome, the graft function and the survival rates between these groups. RESULTS: Of 195 LTs in pediatric recipients (age < 18), 48 (25%) were with LD grafts and 47 (24%) with CAD grafts (reduced size, n = 27, or split, n = 20). The mean age and weight of the LD recipients were 1.8 +/- 3 yrs and 9.0 +/- 8.1 kg vs. 3.5 +/- 4 yrs. and 15.2 +/- 14.5 kg in the CAD group. The distribution of etiologies was comparable (EHBA, 54% vs. 49%; inborn errors in metabolism, 12.5% vs. 12%; acute idiopathic hepatic failure, 12.5% vs. 14.2%). The severity of pretransplant disease and the fraction of acute hepatic failure cases were also comparable, although less LD grafts were used for urgent re-transplantation due to primary non-function or vascular complications (1 case in the LD group vs. 6 in the CAD group). The median warm ischemia time was similar (43 min; range, 28-87 min vs. 45 min; range 12-82 min), but the median cold ischemia time was significantly different (60 min; range 43-298 in LD vs. 637 min; range, 342-1102 in CAD grafts). Both patient and graft survival in 3 months, 1 and 5 years were significantly superior in the LD group (patient survival, 97%, 91% and 89% vs. 82%, 70% and 62%, p < 0.001; graft survival, 92%, 89% and 77% vs. 66%, 59% and 52%, p < 0.005). The incidence of vascular complications (hepatic artery or portal vein thrombosis) and biliary complications (leak of stricture) was comparable (vascular, 10% vs. 7%, biliary, 16% vs. 9%). The incidence of poor early graft function (6% vs. 21%) and primary non-function (2% vs. 18%) was significantly lower in the LD group. CONCLUSION: Although presenting similar surgical complexity, the outcome of segmental grafts from LD is better than of reduced size or split cadaveric grafts.

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BACKGROUND & AIMS: Disturbances in thyroid function in humans and experimental animal models have been associated with alterations in liver function and portal circulation. We have previously shown that hypothyroidism can significantly reduce portal pressure in portal vein ligated rats as well as inhibit the development of cirrhosis and fulminant hepatic failure following toxic liver injury. The aim of this study was to determine the effects of increased and decreased thyroid function on portal pressure in rats with normal liver histology and portal circulation. METHODS: Three groups of 12 Wistar rats each were studied over a 30 day period: euthyroid (Group 1), hyperthyroid (Group 2) and hypothyroid (Group 3). Hyperthyroidism was induced by subcutaneous injection of triiodothyronine (400 microg/100g body weight) every ten days during the study period. Hypothyroidism was induced by methimazole (0.04% in drinking water) from 2 weeks prior to and throughout the 30 day study. Serum triiodothyronine (T3) and thyroid stimulating hormone (TSH) levels were determined to confirm the induction of hyper- and hypothyroidism. Portal pressure was assessed by direct catheterization of the portal vein prior to sacrifice. Indirect confirmation of changes in portal circulation was obtained by determining splenic weight at the time of sacrificing the animals. Animals were sacrificed at 10 day intervals throughout the 30 day study. RESULTS: Triiodothyronine treated rats were hyperthyroid compared to controls, with an elevation in serum T3 levels (3.8+/-0.9 mmol/L vs 1.3+/-0.4 mmol/L, p<0.05). In rats treated with methimazole, hypothyroidism was confirmed by a 7-fold increase in serum TSH compared to controls (1.8+/-0.4 vs 0.24+/-0.04 mmol/L, p<0.01). Portal pressure was significantly higher in the triiodothyronine treated rats compared to controls (12.8+/-1.7 and 9.6+/-0.75 cm H2O, p<0.001). Splenic weights in hyperthyroid rats were significantly higher than in controls (579+/-44 vs 478+/-46 mg, p<0.01). Portal pressure was significantly lower in the methimazole treated group compared to the control group (8.13+/-0.68 vs 9.6+/-0.75 cm H2O, p<0.01) as were splenic weights (400+/-33 vs 478+/-46 mg, p<0.01). CONCLUSION: These studies demonstrate that disturbed thyroid function exerts significant hemodynamic effects on the portal circulation in normal rats and complements results from previous similar studies in cirrhotic animals.

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Chordoma of base of skull is a rare tumor in children. The case reported was atypical by its slow course, the initial clinical signs resulting from the development of the tumoral process in the posterior fossa at the level of the petrous and pontocerebellar angle. Neuro-ophthalmologic manifestations appeared at a late stage only.

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During seven years, 212 small bowel examinations are made on patients with suspected small bowel obstruction by barium infusion. We find all the main small bowel pathology: Crohn's disease (16.5%), carcinomatosis (14.6%), neoplasia (10.3%), vascular disease (17.8%), actinic enteritis (9.5%) and miscellanous (18%). The small bowel infusion is normal in 15%. Surgery is avoided in 51% of the cases. There is non complications associated with the examination but in 12% of the cases, the examination is unsuccessful.

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Thirty two patients with confirmed Crohn's disease were examined from october 1983 to may 1985 by ultrasound (42 examinations) and by Conventional Contrast Radiology (Barium Contrast Studies). The well-know "target" pattern is the most frequent feature (88%) which is characteristic of the thickening bowel wall. The thickening is more important for the small bowel wall than the large bowel wall. But the "target" pattern is not the single pattern of inflammation involving the bowel. We also find a "rosette" pattern. This third ring is hypo or hyperechogenic or more complex. Other infrequent features are noted: solid abdominal masses, distended loops, luminal narrowing, fistula and stiffness. Because sonography is noninvasive and simple to perform without radiation exposure, it must often be used as the initial diagnostic tool and as the follow-up test for young people.

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The authors report their findings in a series of 51 patients suffering from typical cervical radiculopathy. With the aid of the CT scanner and intravenous injection of a contrast medium, the quality and resolution of the resulting images allowed neurosurgical intervention in 42 patients in whom the symptomatology alone was not sufficiently informative to allow successful treatment. In most cases the CT images allowed an accurate diagnosis and revealed a free fragment that had torn the common posterior vertebra ligament.

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