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Increased sinusoidal wall permeability and liver fatty change after two-thirds hepatectomy: An ultrastructural study in the rat
No full textAccumulation of lipids in the hepatocyte cytoplasm after partial hepatectomy (PH) has long been recognized, but the mechanism behind this phenomenon is still poorly understood. In this study, rats subjected to a standard two-thirds PH showed early and marked increase in portal venous pressure (P <.01). On scanning electron microscopy, the regenerating liver fixed by portal perfusion under hemodynamic conditions identical to that found in vivo during the first 24 hours showed a significant (P <.01) 10-fold increase in the sinusoidal wall porosity (percentage open area by fenestrations). This was paralleled by the disappearance of the sieve-plate arrangement of small fenestrations and by a significant decrease in the number of fenestrations per micrometers squared of sinusoidal surface at 6 (P <.01) and 12 hours (P <.05). In addition, there were major changes in the frequency and distribution of all three classes of fenestrations. At 6 and 12 hours, there was a marked decrease of small class 1 fenestrations and a marked increase of intermediate class 2 fenestrations and large class 3 fenestrations (P <.0001). A concurrent accumulation of lipid droplets in the hepatocyte cytoplasm produced a 20-fold increase in the hepatocyte total lipid volume. A statistically significant linear correlation (r = 0.907; P <.01) was found between the amount of intracellular lipids and the data quantitating the changes in porosity of liver sinusoids at 24 hours. It is concluded that an increased sinusoidal wall permeability to lipids may be the primum movens in the pathogenesis of transient liver fatty change after PH in the rat. © 1995
Haemodynamic and ultrastructural observations on the rat liver after two-thirds partial hepatectomy*
No full textRat liver ultrastructure was investigated after partial hepatectomy (PH), by scanning and transmission electron microscopy. Portal pressure was monitored before and after PH and, after killing performed at 6, 12, 24, 48 h and 10 d, regenerating livers were fixed by portal vein perfusion under haemodynamic conditions identical to those existing in vivo. An early and persistent increase in portal pressure after PH was found (P < 0.01 for normal vs sham-operated controls). Ultrastructural study showed sinusoid dilatation and disappearance of the sieve-plate arrangement of small endothelial pores, thus leaving the parenchymal liver cell surface directly exposed to portal blood. Widening of sinusoids, endothelial fenestrations, intercellular spaces and spaces of Disse, was accompanied by dilatation of bile canaliculi. At 10 d, liver ultrastructure had returned to normal. Our observations suggest that a rise in portal pressure, as a consequence of PH, may be related to the observed ultrastructural changes in the liver
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Growth of intraportally transplanted islets under liver regeneration stimulus and restoration of normoglycemia in streptozocin-diabetic rats
No full textBackground. Limitation of β-cell growth after intraportal islet transplantation plays an important role in graft failure. To induce transplanted β-cell proliferation, we studied the effect of compensatory liver growth in diabetic rats that had a subtherapeutic islet mass previously injected into the liver. Methods. Syngeneic rats were used as islet donors or recipients; diabetes was induced by streptozocin. Three groups of streptozocin-treated rats were studied. In group 1, 250 islets were selectively transplanted into the posterior liver lobes and 10 days later anterior portal branch ligation (PBL) was performed (n - 18); in group 2, 250 islets were transplanted into the posterior lobes and 10 days later sham PBL was performed (n = 13); in group 3, rats underwent a sham transplantation and PBL (n = 6). Nonfasting blood glucose levels and body weight were monitored. Six rats in groups 1 and 2 were killed 48 hours after PBL, liver sections were stained for proliferating cell nuclear antigen, and islet cell labeling index was calculated. The remaining rats were killed 30 days later. Liver compensatory growth or atrophy was calculated and morphometric determination of β-cell area was assessed on insulin-immunostained sections of the liver. Results. In group 1 rats killed 48 hours after PBl, islet cell labeling index was significantly higher than in group 2 (p < 0.0001). After PBL, we observed normalization of nonfasting blood glucose levels in 10 of 12 rats. At 30 days, posterior liver lobes showed compensatory growth (218.5% ± 18.6%) accompanied by atrophy of the anterior lobes; morphometric study of liver- engrated islets showed a significant increase of individual β-cell area, compared with group 2 (p < 0.0001). In groups 2 and 3, normoglycemia was not achieved. Conclusions. In streptozocin-diabetic rats, normoglycemia was restored after transplantation of a sub-therapeutic islet mass, followed by PBL-induced liver regeneration. Histologic and morphometric results indicating islet cell proliferation suggest that compensatory liver growth might have induced a hypertrophic/hyperplastic response in the intraportally transplanted β-cells
Serum bile acids in patients with acute liver failure supported with a bioartificial liver
No full textBACKGROUND: Serum bile acids are increased in liver failure, but the composition of the bile acid pool in this condition has not been studied in detail. This information is of interest because of dihydroxy bile acid toxicity.
METHODS: We measured serum bile acids by gas chromatography-mass spectrometry in 13 patients with fulminant liver failure and five patients with acute-on-chronic liver failure. Furthermore, serum bile acids were analysed in the same patients after 6 h of treatment with a bioartificial liver, consisting of a hollow-fibre cartridge with microcarrier-attached porcine hepatocytes and a charcoal column.
RESULTS: Pre-bioartificial liver serum bile acids demonstrated a high dihydroxy/trihydroxy ratio and were higher in patients with acute-on-chronic liver failure than in those with fulminant liver failure (452.8 +/- 98.6 vs. 182.1 +/- 39.7 micro mol/L; P < 0.05). Bioartificial liver treatment decreased significantly serum bile acids in patients with fulminant liver failure (-38.8%) and acute-on-chronic liver failure (-35.8%), with a decreased dihydroxy/trihydroxy ratio. In vitro, porcine hepatocytes in the bioreactor cleared most conjugated bile acid species from pooled patient plasma.
CONCLUSIONS: Acute liver failure is associated with very high serum levels of toxic bile acids that could contribute to the pathogenesis of the syndrome. Bioartificial liver treatment reduces both serum bile acid concentrations and the hydrophobicity of the bile acid pool
Pancreatic beta-cell replication in streptozotocin-diabetic rats: The effect of liver compensatory growth on intraportally engrafted islets
No full textEarly studies showed that compensatory liver growth after anterior portal branch ligation (aPBL) may restore normoglycemia in streptozotocin (STZ)-diabetic rats, in which a subtherapeutic islet mass was previously transplanted into the liver. We hypothesized that this effect could be related to islet regeneration at the graft site. This study was designed to characterize the proliferative response of the intraportally transplanted islets, shortly after aPBL. Male Wistar-Furth rats were used as syngeneic islet donors and/or recipients. STZ-diabetic rats were divided in four groups: groups 1 and 2 underwent selective 250-islet transplantation (Tx) into the posterior liver lobes, followed by aPBL 10 days later; rats were killed 24 h (n = 9) and 48 h (n = 10) after aPBL, respectively; groups 3 and 4 underwent selective 250-islet Tx into the posterior liver lobes, followed by sham aPBL 10 days later; rats were killed 24 h (n = 3) and 48 h (n = 3) after aPBL, respectively. Two hours before k..
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
In vitro morphological and functional characterization of isolated porcine hepatocytes for extracorporeal liver support: bile acid uptake and conjugation.
No full textRecently, researchers have focused on the use of bioartificial liver (BAL) to support patients with fulminant hepatic failure (FHF). We have developed a cell-based BAL, consisting of porcine hepatocytes in a hollow- fiber bioreactor. To better characterize BAL metabolic functions in vitro, bioreactors were inoculated with 48-h-cultured, microcarrier-attached hepatocytes and perifused with recirculating human plasma that contained either 1 μCi of [24-14C] plasma-enriched cholate or 1 μCi of [24-14C] plasma-enriched taurocholate. Bile acids were sampled hourly and separated into four fractions (unconjugated, glycoconjugated, tauroconjugated, and sulfated) for radioactivity determination. Following 3 h perifusion, the glycoconjugated and sulfated bile acid fractions in the bioreactor extrafiber space were significantly elevated when compared to the recirculating plasma. During perifusion with taurocholate-enriched plasma, a relative decrease in the tauroconjugated fraction and an increase..
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