Sterol regulatory element binding protein-1a transactivates 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase gene promoter

6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB)catalyzes the synthesis and degradation of fructose-2,6-bisphosphate, a key modulator of glycolysis-gluconeogenesis. To gain insight into the molecular mechanism behind hormonal and nutritional regulation of PFKFB expression, we have cloned and characterized the proximal promoter region of the liver isoform of PFKFB (PFKFB1) from gilthead sea bream (Sparus aurata). Transient transfection of HepG2 cells with deleted gene promoter constructs and electrophoretic mobility shift assays allowed us to identify a sterol regulatory element (SRE) to which SRE binding protein-1a (SREBP-1a)binds and transactivates PFKFB1 gene transcription. Mutating the SRE box abolished SREBP-1a binding and transactivation. The in vivo binding of SREBP-1a to the SRE box in the S. aurata PFKFB1 promoter was confirmed by chromatin immunoprecipitation assays. There is a great deal of evidence for a postprandial rise of PFKB1 mRNA levels in fish and rats. Consistently, starved-to-fed transition and treatment with glucose or insulin increased SREBP-1 immunodetectable levels, SREBP-1 association to PFKFB1 promoter, and PFKFB1 mRNA levels in the piscine liver. Our findings demonstrate involvement of SREBP-1a in the transcriptional activation of PFKFB1, and we conclude that SREBP-1a may exert a key role mediating postprandial activation of PFKFB1 transcription.

Liver Glucokinase A456V induces potent hypoglycemia without dyslipidemia through a paradoxical induction of the catalytic subunit of glucose-6-phosphatase

Recent reports point out the importance of the complex GK-GKRP in controlling glucose and lipid homeostasis. Several GK mutations affect GKRP binding, resulting in permanent activation of the enzyme. We hypothesize that hepatic overexpression of a mutated form of GK, GKA456V, described in a patient with persistent hyperinsulinemic hypoglycemia of infancy (PHHI) and could provide a model to study the consequences of GK-GKRP deregulation in vivo. GKA456V was overexpressed in the liver of streptozotocin diabetic mice. Metabolite profiling in serum and liver extracts, together with changes in key components of glucose and lipid homeostasis, were analyzed and compared to GK wild-type transfected livers. Cell compartmentalization of the mutant but not the wild-type GK was clearly affected in vivo, demonstrating impaired GKRP regulation. GKA456V overexpression markedly reduced blood glucose in the absence of dyslipidemia, in contrast to wild-type GK-overexpressing mice. Evidence in glucose utilization did not correlate with increased glycogen nor lactate levels in the liver. PEPCK mRNA was not affected, whereas the mRNA for the catalytic subunit of glucose-6-phosphatase was upregulated ~4 folds in the liver of GKA456V-treated animals, suggesting that glucose cycling was stimulated. Our results provide new insights into the complex GK regulatory network and validate liver-specific GK activation as a strategy for diabetes therapy.

Management of varices and variceal hemorrhage in cirrhosis.

Variceal hemorrhage is a lethal complication of cirrhosis, particularly in patients in whom clinical decompensation (i.e., ascites, encephalopathy, a previous episode of hemorrhage, or jaundice) has already developed. Practice guidelines for the management of varices and variceal hemorrhage1 in cirrhosis are mostly based on evidence in the literature that has been summarized and prioritized at consensus conferences...

Non-invasive diagnostic and prognostic evaluation of liver cirrhosis and portal hypertension.

Cirrhosis is the ���nal stage of most of chronic liver diseases, and is almost invariably complicated by portal hypertension, which is the most important cause of morbidity and mortality in these patients. This review will focus on the non-invasive methods currently used in clinical practice for diagnosing liver cirrhosis and portal hypertension. The ���rst-line techniques include physical examination, laboratory parameters, transient elastography and Doppler-US. More sophisticated imaging methods which are less commonly employed are CT scan and MRI, and new technologies which are currently under evaluation are MR elastography and acoustic radiation force imaging (ARFI). Even if none of them can replace the invasive measurement of hepatic venous pressure gradient and the endoscopic screening of gastroesophageal varices, they notably facilitate the clinical management of patients with cirrhosis and portal hypertension, and provide valuable prognostic information.

Estudo prospectivo de 100 casos de "core" bi��psia dirigida por ultra-som e revis��o da literatura

OBJETIVO: Mostrar a efic��cia do m��todo para evitar bi��psias excisionais, verificar suas dificuldades t��cnicas, definir entre seguimento e bi��psia excisional nos n��dulos categoria IV do BI-RADS™ e agilizar o procedimento cir��rgico nos casos de n��dulos altamente suspeitos de malignidade (categoria V). MATERIAIS E M��TODOS: As pacientes foram submetidas a exame cl��nico de rotina, mamografia e ultra-som. A "core" foi feita com pistola autom��tica e agulha n��mero 14, e foram colhidas de quatro a oito amostras. RESULTADOS: Das 100 les��es estudadas, 47 foram submetidas �� cirurgia, al��m da "core", e diagnosticaram-se 34 carcinomas (34,0%). Das 23 les��es classificadas como categoria III, identificou-se apenas um carcinoma (4,34%); das 43 classificadas como categoria IV, sete (16,28%); e das 34 classificadas como categoria V, 26 (76,47%). Evitou-se a bi��psia excisional em 53 casos (53,0%). Identificou-se dificuldade no m��todo da "core" em sete casos (7,0%), devido a material insuficiente, risco para malignidade envolvendo les��es esclerosantes complexas e discord��ncia entre imagem e histologia. As 33 les��es com resultados de malignidade �� pun����o bi��psia por agulha grossa foram confirmadas ap��s a bi��psia cir��rgica. Em um caso o diagn��stico pela "core" foi de hiperplasia ductal at��pica e ap��s a bi��psia cir��rgica da pe��a diagnosticou-se carcinoma, correspondendo a um resultado falso-negativo. N��o houve nenhum resultado falso-positivo.

Bi��psia pulmonar percut��nea guiada por tomografia computadorizada: dados de um hospital

OBJETIVO: Apresentar a experi��ncia do servi��o de radiologia do Hospital Santa Cec��lia, S��o Paulo, SP, no manejo das bi��psias pulmonares por aspira����o atrav��s de agulha fina e bi��psias por fragmentos guiadas por tomografia computadorizada e a an��lise de sua import��ncia e associa����o com suas complica����es. MATERIAIS E M��TODOS: Foram analisadas 168 bi��psias guiadas por tomografia, sendo 84 em homens e 84 em mulheres. Utilizou-se a t��cnica de bi��psia por aspira����o por agulha fina em 64 pacientes, a t��cnica de bi��psia por fragmento em 68 pacientes e ambas as t��cnicas em 36 pacientes. RESULTADOS: Pneumot��rax ocorreu em 38 pacientes e a hemorragia pulmonar, em dez pacientes. As dimens��es das les��es biopsiadas variaram de 0,5 cm at�� 15 cm. O diagn��stico foi realizado na primeira tentativa em 132 casos e na segunda tentativa em dez casos. CONCLUS��O: A acur��cia das bi��psias aspirativas por agulha fina e por fragmento de les��es pulmonares depende do tamanho da les��o e da colabora����o do paciente. Essas t��cnicas s��o relativamente seguras e t��m acur��cia diagn��stica elevada quando feitas por um profissional experiente.

Educa����o a dist��ncia mediada pela internet: "Linfonodo sentinela, preven����o, diagn��stico precoce e bi��psia - nova t��cnica de abordagem do c��ncer de mama"

OBJETIVO: O objetivo deste estudo �� o desenvolvimento e a aplica����o de um curso na modalidade "Educa����o a dist��ncia mediada pela internet". MATERIAIS E M��TODOS: Foi utilizado o curso "Linfonodo sentinela, preven����o, diagn��stico precoce e bi��psia - nova t��cnica de abordagem do c��ncer de mama" como modelo de aplica����o. O material did��tico para a modalidade "Educa����o a dist��ncia" foi elaborado visando a um p��blico composto por m��dicos envolvidos com o tratamento do c��ncer de mama. O curso foi estruturado em ambiente virtual de aprendizagem, um espa��o virtual que permitiu a intera����o entre os participantes. RESULTADOS: A dura����o do curso foi de 12 semanas. Iniciou-se com nove participantes, m��dicos ginecologistas com pelo menos oito anos de experi��ncia profissional. Todos os alunos participaram de alguma forma, dois realizaram exerc��cios e interagiram. O alcance do curso pelo m��todo atingiu quatro estados e oito munic��pios. N��o ocorreu ades��o integral dos alunos, apesar de a maioria permanecer at�� o fim do curso. Possivelmente, n��o houve motiva����o suficiente para participa����o nas atividades propostas. CONCLUS��O: Os resultados mostram que �� necess��rio quebrar as barreiras da falta de cultura relacionada a esta forma de aprendizagem. �� fundamental a participa����o facilitadora do coordenador para integra����o e mobiliza����o dos participantes.

Effects of heparin on the uptake of lipoprotein lipase in rat liver

BACKGROUND: Lipoprotein lipase (LPL) is anchored at the vascular endothelium through interaction with heparan sulfate. It is not known how this enzyme is turned over but it has been suggested that it is slowly released into blood and then taken up and degraded in the liver. Heparin releases the enzyme into the circulating blood. Several lines of evidence indicate that this leads to accelerated flux of LPL to the liver and a temporary depletion of the enzyme in peripheral tissues. RESULTS: Rat livers were found to contain substantial amounts of LPL, most of which was catalytically inactive. After injection of heparin, LPL mass in liver increased for at least an hour. LPL activity also increased, but not in proportion to mass, indicating that the lipase soon lost its activity after being bound/taken up in the liver. To further study the uptake, bovine LPL was labeled with 125I and injected. Already two min after injection about 33 % of the injected lipase was in the liver where it initially located along sinusoids. With time the immunostaining shifted to the hepatocytes, became granular and then faded, indicating internalization and degradation. When heparin was injected before the lipase, the initial immunostaining along sinusoids was weaker, whereas staining over Kupffer cells was enhanced. When the lipase was converted to inactive before injection, the fraction taken up in the liver increased and the lipase located mainly to the Kupffer cells. CONCLUSIONS: This study shows that there are heparin-insensitive binding sites for LPL on both hepatocytes and Kupffer cells. The latter may be the same sites as those that mediate uptake of inactive LPL. The results support the hypothesis that turnover of endothelial LPL occurs in part by transport to and degradation in the liver, and that this transport is accelerated after injection of heparin.

Dysregulation of apoptosis in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a major health problem, being the sixth most common cancer world-wide. Dysregulation of the balance between proliferation and cell death represents a pro-tumorigenic principle in human hepatocarcinogenesis. This review updates the recent relevant contributions reporting molecular alterations for HCC that induce an imbalance in the regulation of apoptosis. Alterations in the expression and/or activation of p53 are frequent in HCC cells, which confer on them resistance to chemotherapeutic drugs. Many HCCs are also insensitive to apoptosis induced either by death receptor ligands, such as FasL or TRAIL, or by transforming growth factor-beta (TGF-beta). Although the expression of some pro-apoptotic genes is decreased, the balance between death and survival is dysregulated in HCC mainly due to overactivation of anti-apoptotic pathways. Indeed, some molecules involved in counteracting apoptosis, such as Bcl-XL, Mcl-1, c-IAP1, XIAP or survivin are over-expressed in HCC cells. Furthermore, some growth factors that mediate cell survival are up-regulated in HCC, as well as the molecules involved in the machinery responsible for cleavage of their pro-forms to an active peptide. The expression and/or activation of the JAK/STAT, PI3K/AKT and RAS/ERKs pathways are enhanced in many HCC cells, conferring on them resistance to apoptotic stimuli. Finally, recent evidence indicates that inflammatory processes, as well as the epithelial-mesenchymal transitions that occur in HCC cells to facilitate their dissemination, are related to cell survival. Therefore, therapeutic strategies to selectively inhibit anti-apoptotic signals in liver tumor cells have the potential to provide powerful tools to treat HCC.

Growth factor- and cytokine-driven pathways governing liver stemness and differentiation.

Liver is unique in its capacity to regenerate in response to injury or tissue loss. Hepatocytes and other liver cells are able to proliferate and repopulate the liver. However, when this response is impaired, the contribution of hepatic progenitors becomes very relevant. Here, we present an update of recent studies on growth factors and cytokine-driven intracellular pathways that govern liver stem/progenitor cell expansion and differentiation, and the relevance of these signals in liver development, regeneration and carcinogenesis. Tyrosine kinase receptor signaling, in particular, c-Met, epidermal growth factor receptors or fibroblast growth factor receptors, contribute to proliferation, survival and differentiation of liver stem/progenitor cells. Different evidence suggests a dual role for the transforming growth factor (TGF)-�� signaling pathway in liver stemness and differentiation. On the one hand, TGF-�� mediates progression of differentiation from a progenitor stage, but on the other hand, it contributes to the expansion of liver stem cells. Hedgehog family ligands are necessary to promote hepatoblast proliferation but need to be shut off to permit subsequent hepatoblast differentiation. In the same line, the Wnt family and ��-catenin/T-cell factor pathway is clearly involved in the maintenance of liver stemness phenotype, and its repression is necessary for liver differentiation during development. Collectively, data indicate that liver stem/progenitor cells follow their own rules and regulations. The same signals that are essential for their activation, expansion and differentiation are good candidates to contribute, under adequate conditions, to the paradigm of transformation from a pro-regenerative to a pro-tumorigenic role. From a clinical perspective, this is a fundamental issue for liver stem/progenitor cell-based therapies.

Avalia����o de um dispositivo port��til para bi��psia v��cuo-assistida de microcalcifica����es mam��rias

OBJETIVO: A bi��psia v��cuo-assistida �� a forma percut��nea de bi��psia de microcalcifica����es que obt��m a menor taxa de subestima����o, por��m, seu custo �� alto, havendo interesse em se conseguir formas mais baratas de bi��psia v��cuo-assistida. O objetivo deste trabalho foi testar um dispositivo port��til de bi��psia v��cuo-assistida que apresenta custo menor. MATERIAIS E M��TODOS: Foram biopsiadas 35 pacientes que apresentavam agrupamentos de microcalcifica����es BI-RADS�� 4 ou 5. Foram testados a representatividade dos fragmentos colhidos, as dificuldades na reintrodu����o da c��nula e o n��mero de ciclos de colheita. RESULTADOS: Houve obten����o de calcifica����es representativas em todas as pacientes. N��o houve discord��ncia anatomorradiol��gica, dificuldade na reintrodu����o da c��nula ou complica����es graves. CONCLUS��O: Os dados permitem concluir que o sistema apresenta boa efic��cia na obten����o das amostras e com rela����o de custo-benef��cio favor��vel em rela����o a outros sistemas para a bi��psia de microcalcifica����es, achados em concord��ncia com outras publica����es da literatura.

Bi��psia transtor��cica de n��dulos e massas pulmonares dirigida por tomografia computadorizada

Bi��psia percut��nea dirigida por tomografia computadorizada tem sido amplamente utilizada como um procedimento efetivo e seguro para obten����o de diagn��stico histol��gico em muitas situa����es cl��nicas e em diversos ��rg��os. No pulm��o, a bi��psia percut��nea tornou-se uma das principais escolhas para investiga����o de n��dulos e massas. Sua versatilidade permite o acesso de les��es nas diversas localiza����es do pulm��o, podendo ser utilizada para les��es perif��ricas e profundas mesmo de pequenas dimens��es. Discutiremos as indica����es, os aspectos t��cnicos do procedimento e os ��ndices esperados de sucesso e complica����o das bi��psias percut��neas de n��dulos e massas pulmonares.