RESUMO
BACKGROUND: Decrease in oral intake, weight loss, and muscular weakness in the last phases of a terminal illness, particularly in the context of the cachexia-anorexia syndrome, can be an important source of anxiety for the triad of patient, family, and health staff. METHODS: The present literature review examines the emotional impact of reduced oral intake as well as perceptions and attitudes toward assisted nutrition and hydration for terminally ill patients(1) at the end of life, among patients, family, and health care staff. We have identified the ways in which emotional and cultural factors influence decision-making about assisted nutrition and hydration. RESULTS: Lack of information and misperceptions of medically assisted nutrition and hydration can play a predominant role in the decision to begin or suspend nutritional or hydration support. CONCLUSIONS: Our literature review reveals that these social, emotional, and clinical misperception elements should be considered in the decision-making processes to help the triad develop functional forms of care at this final stage of life. Copyright © 2011 John Wiley & Sons, Ltd.
Assuntos
Hidratação , Neoplasias/terapia , Estado Nutricional , Cuidados Paliativos/métodos , Assistência Terminal/psicologia , Atitude do Pessoal de Saúde , Atitude Frente a Saúde , Tomada de Decisões , Emoções , Família/psicologia , Humanos , Neoplasias/psicologia , Cuidados Paliativos/psicologia , Participação do Paciente , PercepçãoRESUMO
This issue of the Revista brings two articles relayed to gallbladder cancer (GC), a highly prevalent cancer among Chileans. The first papaer relates to therapy for Stage II NO GC. Authors from Universidad de la Frontera corroborate the bad results usually obatined with adjunct chemotheraphy and radiotheraphy, associated to a second operation. The second paper discusses the negative influences that the new Xth Edition of the International Classification of Diseases might have on GC control. This cancer appears now with a dramatic 100% decrease in mortality rate in the last 3 years, associated to a simultaneous increase of the digit related to biliary tract cancer of "undefined orgin", which in the great majority of cases truly corresponds to GC throughout the world. This involuntary bias could have a strong negative effect on health policy makers, because health resources will not be derived to perform more cholecystectomies needed to significantly decrease the number of gallbladders at risk. This is a major issue for the Chilean health system, since GC represents the first cause of deaths due to cancer among Chilean women.
Assuntos
Neoplasias da Vesícula Biliar , Chile/epidemiologia , Colecistectomia , Feminino , Neoplasias da Vesícula Biliar/epidemiologia , Neoplasias da Vesícula Biliar/terapia , Humanos , Masculino , PrevalênciaRESUMO
Gallbladder cancer is usually associated with gallstone disease, late diagnosis, unsatisfactory treatment, and poor prognosis. We report here the worldwide geographical distribution of gallbladder cancer, review the main etiologic hypotheses, and provide some comments on perspectives for prevention. The highest incidence rate of gallbladder cancer is found among populations of the Andean area, North American Indians, and Mexican Americans. Gallbladder cancer is up to three times higher among women than men in all populations. The highest incidence rates in Europe are found in Poland, the Czech Republic, and Slovakia. Incidence rates in other regions of the world are relatively low. The highest mortality rates are also reported from South America, 3.5-15.5 per 100,000 among Chilean Mapuche Indians, Bolivians, and Chilean Hispanics. Intermediate rates, 3.7 to 9.1 per 100,000, are reported from Peru, Ecuador, Colombia, and Brazil. Mortality rates are low in North America, with the exception of high rates among American Indians in New Mexico (11.3 per 100,000) and among Mexican Americans. The main associated risk factors identified so far include cholelithiasis (especially untreated chronic symptomatic gallstones), obesity, reproductive factors, chronic infections of the gallbladder, and environmental exposure to specific chemicals. These suspected factors likely represent promoters of carcinogenesis. The main limitations of epidemiologic studies on gallbladder cancer are the small sample sizes and specific problems in quantifying exposure to putative risk factors. The natural history of gallbladder disease should be characterized to support the allocation of more resources for early treatment of symptomatic gallbladder disease in high-risk populations. Secondary prevention of gallbladder cancer could be effective if supported by cost-effective studies of prophylactic cholecystectomy among asymptomatic gallstone patients in high-risk areas.
Assuntos
Neoplasias da Vesícula Biliar/epidemiologia , Neoplasias da Vesícula Biliar/genética , Colelitíase/complicações , Colelitíase/genética , Neoplasias da Vesícula Biliar/patologia , Neoplasias da Vesícula Biliar/prevenção & controle , Humanos , Fatores de RiscoRESUMO
BACKGROUND & AIMS: Sterol carrier protein 2 (SCP-2) enhances sterol cycling and facilitates cholesterol translocation between intracellular organelles and plasma membrane in cultured cells, including hepatocytes. We examined the role of SCP-2 in hepatic cholesterol and lipid trafficking through the sinusoidal and canalicular secretory pathways of the liver in vivo. METHODS: Recombinant adenovirus-mediated SCP-2 gene transfer was used to obtain hepatic overexpression of SCP-2 in C57BL/6 mice. RESULTS: SCP-2 overexpression in the mouse liver resulted in an 8-fold increase of SCP-2 protein levels and determined various effects on lipid metabolism. It decreased high-density lipoprotein cholesterol and increased low-density lipoprotein (LDL) cholesterol concentrations. The expressions of hepatic LDL receptor, apolipoprotein (apo) A-I, apoB, and apoE were decreased. SCP-2 overexpression also increased hepatic cholesterol concentration, associated with decreased cholesterol neosynthesis. Increased biliary cholesterol and bile acid secretion, bile acid pool size, and intestinal cholesterol absorption were also observed. CONCLUSIONS: These results indicate that modulation of SCP-2 expression in the liver determines important modifications on lipoprotein metabolism, hepatic cholesterol synthesis and storage, biliary lipid secretion, bile acid metabolism, and intestinal cholesterol absorption.
Assuntos
Proteínas de Transporte/farmacologia , Metabolismo dos Lipídeos , Circulação Hepática/efeitos dos fármacos , Fígado/metabolismo , Proteínas de Plantas , Esteróis/sangue , Animais , Apolipoproteínas/metabolismo , Bile/metabolismo , Ácidos e Sais Biliares/metabolismo , Proteínas de Transporte/genética , Colesterol/metabolismo , Técnicas de Transferência de Genes , Absorção Intestinal/efeitos dos fármacos , Lipoproteínas LDL/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
The mitochondrial DNAs (mtDNAs) from individuals belonging to three Chilean tribes, the Mapuche, the Pehuenche, and the Yaghan, were studied both by RFLP analysis and D-loop (control region) sequencing. RFLP analysis showed that 3 individuals (1.3%) belonged to haplogroup A, 19 (8%) to haplogroup B, 102 (43%) to haplogroup C, and 113 (47.7%) to haplogroup D. Among the 73 individuals analyzed by D-loop sequencing, we observed 37 different haplotypes defined by 52 polymorphic sites. Joint analysis of data obtained by RFLP and sequencing methods demonstrated that, regardless of the method of analysis, the mtDNA haplotypes of these three contemporary South American aborigine groups clustered into four main haplogroups, in a way similar to those previously described for other Amerindians. These results further revealed the absence of haplogroup A in both the Mapuche and Yaghan as well as the absence of haplogroup B in the Yaghan. These results suggest that the people of Tierra del Fuego are related to tribes from south-central South America.
Assuntos
DNA Mitocondrial/química , Indígenas Sul-Americanos/genética , Sequência de Bases , Chile , Humanos , Dados de Sequência Molecular , Filogenia , Polimorfismo Genético , Polimorfismo de Fragmento de Restrição , Análise de Sequência de DNARESUMO
BACKGROUND & AIMS: Because apolipoprotein E (apoE) is a key cholesterol transport molecule involved in the hepatic uptake of chylomicron cholesterol, it may play a critical role in controlling bile cholesterol elimination and cholesterol gallstone formation induced by dietary cholesterol. To test this hypothesis, we studied biliary lipid secretion and gallstone formation in apoE-deficient mice fed cholesterol-rich diets. METHODS: Bile lipid outputs and gallstone sequence events were analyzed in apoE-deficient mice fed a high-cholesterol diet or a lithogenic diet compared with control animals. RESULTS: A high-cholesterol diet increased biliary cholesterol secretion and gallbladder bile cholesterol concentration in wild-type mice; the increase in bile cholesterol secretion was significantly attenuated in apoE-deficient mice. ApoE knockout mice fed a high-cholesterol lithogenic diet had a markedly lower frequency of gallbladder bile cholesterol crystal and gallstone formation than wild-type mice, which was most likely a result of the decreased cholesterol saturation index found in gallbladder bile of apoE-deficient mice. CONCLUSIONS: These results show that apoE expression is an important factor for regulating both biliary secretion of diet-derived cholesterol as well as diet-induced cholesterol gallstone formation in mice.
Assuntos
Apolipoproteínas E/deficiência , Bile/metabolismo , Colelitíase/prevenção & controle , Colesterol na Dieta/administração & dosagem , Colesterol/metabolismo , Animais , Apolipoproteínas E/genética , Apolipoproteínas E/fisiologia , Ácidos e Sais Biliares/metabolismo , Colelitíase/etiologia , Colesterol/sangue , Colesterol na Dieta/farmacologia , Dieta , Vesícula Biliar/metabolismo , Metabolismo dos Lipídeos , Lipoproteínas/sangue , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout/genéticaRESUMO
These studies were undertaken to characterize the role of plasma membrane cholesterol in canalicular secretory functions and hepatocyte integrity against intravenous taurocholate administration. Cholesterol and sphingomyelin concentrations and cholesterol/phospholipid ratios were significantly increased in canalicular membranes of diosgenin-fed rats, suggesting a more resistant structure against solubilization by taurocholate. During taurocholate infusion, control rats had significantly decreased bile flow, whereas diosgenin-fed animals maintained bile flow. Maximal cholesterol output increased by 176% in diosgenin-fed rats, suggesting an increased precursor pool of biliary cholesterol in these animals. Maximal phospholipid output only increased by 43% in diosgenin-fed rats, whereas bile salt output remained at control levels. The kinetics of glutamic oxalacetic transaminase, lactic dehydrogenase, and alkaline phosphatase activities in bile showed a significantly faster release in control than in diosgenin-fed rats. After 30 min of intravenous taurocholate infusion, necrotic hepatocytes were significantly increased in control animals. Preservation of bile secretory functions and hepatocellular cytoprotection by diosgenin against the intravenous infusion of toxic doses of taurocholate was associated with an increased concentration of cholesterol and sphingomyelin in the canalicular membrane. The increase of biliary cholesterol output induced by diosgenin was correlated to the enhanced concentration of cholesterol in the canalicular membrane.
Assuntos
Ácidos e Sais Biliares/toxicidade , Membrana Celular/metabolismo , Colesterol/metabolismo , Fígado/patologia , Esfingomielinas/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Aspartato Aminotransferases/metabolismo , Bile/efeitos dos fármacos , Bile/metabolismo , Fracionamento Celular , Diosgenina/farmacologia , Modelos Animais de Doenças , L-Lactato Desidrogenase/metabolismo , Lipídeos/análise , Masculino , Fosfolipídeos/metabolismo , Ratos , Ratos Sprague-Dawley , Ácido Taurocólico/toxicidadeRESUMO
Common bile duct stones are a common cause of morbidity and mortality in adults. An increasing number of surgical and medical therapies are available to manage them, with different success rates reported. The various medical treatment strategies were developed during the last decade, but these medical modalities should not be contemplated as a first-line alternative of treatment. A consensus from experts is that there is no primary indication to use solvents on common bile duct stones because they have a relatively high rate of adverse effects and their success is limited compared with lithotripsy. However, there is a subgroup of patients in whom invasive or surgical treatment is risky or may fail. In these patients stone dissolution by solvent may constitute a plausible therapeutic alternative or may help reduce the size of the stones sufficiently to facilitate subsequent endoscopic extraction. Solvents may also be indicated in settings where endoscopic techniques or lithotripsy are not available and the patient has a T-tube in the common bile duct. Even in this condition, however, it is probably quicker and more effective to refer the patient to a center with expertise and technologic support to practice stone removal.
Assuntos
Cálculos Biliares/tratamento farmacológico , Glicerídeos/uso terapêutico , Solventes/uso terapêutico , Caprilatos , Fármacos Gastrointestinais/uso terapêutico , Humanos , Éteres Metílicos/uso terapêutico , Ácido Ursodesoxicólico/uso terapêuticoRESUMO
BACKGROUND & AIMS: The etiology of cholesterol gallstones is multifactorial, with interactions of genes and the environment. The hypothesis that aborigine cholesterol lithogenic genes are widely spread among Chileans, a population with a high prevalence of gallstones, was tested. METHODS: Medical history and anthropometric measurements were obtained and abdominal ultrasonography was performed in 182 Mapuche Indians, 225 Maoris of Easter Island, and 1584 Hispanics. Blood groups, DNA, lipids, and glucose were analyzed. The Amerindian Admixture Index and mitochondrial DNA (mtDNA) assessed the ethnicity and degree of racial admixture. RESULTS: Amerindian Admixture Index was 0.8 in Mapuches and 0.4 in Hispanics. All Mapuches, 88% of Hispanics, but none of Maoris had Amerindian mtDNA haplotypes. Age- and sex-adjusted global prevalence of gallstone disease was higher in Mapuches (35%) than in Hispanics (27%) and Maoris (21%). Compared with Hispanics, the youngest group of Mapuches had the greatest corrected risk of gallstones: odds ratios of 6.0 in women and 2.3 in men. In contrast, the gallstone risk in Maoris was lower compared with Hispanics: odds ratios of 0.6 for women and 0.5 for men. CONCLUSIONS: Cholesterol lithogenic genes appear widely spread among Chilean Indians and Hispanics. They could determine the early formation of gallstones and explain the high prevalence of gallbladder diseases among some South American populations.
Assuntos
Colelitíase/etnologia , Colelitíase/genética , Colesterol/metabolismo , Hispânico ou Latino/estatística & dados numéricos , Indígenas Sul-Americanos/estatística & dados numéricos , Havaiano Nativo ou Outro Ilhéu do Pacífico/estatística & dados numéricos , Adulto , Chile/epidemiologia , Colelitíase/metabolismo , Feminino , Hispânico ou Latino/genética , Humanos , Indígenas Sul-Americanos/genética , Masculino , Pessoa de Meia-Idade , Havaiano Nativo ou Outro Ilhéu do Pacífico/genética , Polinésia/epidemiologiaRESUMO
BACKGROUND & AIMS: Biliary proteins are promoters of cholesterol crystallization in artificial model bile. However, their pathogenic importance for cholesterol precipitation in native gallbladder bile (GB) is uncertain. The aim of this study was to evaluate the significance of biliary lipids and proteins on cholesterol crystal detection time (ChCDT) of GB in patients with gallstones. METHODS: ChCDT and concentrations of lipids, albumin, mucins, aminopeptidase N, alpha1-acid glycoprotein, haptoglobin, and immunoglobulins (Igs) were measured in GB of 92 patients, 52 of whom had cholesterol gallstones. RESULTS: ChCDT was markedly reduced in gallstone patients. Compared with patients without gallstones, they had a significant increase in cholesterol saturation and total protein, albumin, mucin, and IgG biliary concentrations. In univariate analysis, ChCDT of GB was significantly correlated with cholesterol saturation and total lipid, protein, Ig, aminopeptidase N, and alpha1-acid glycoprotein concentrations. However, stepwise logistic regression analysis showed that only cholesterol saturation independently correlated to ChCDT. Gallbladder inflammation correlated with the concentration of Igs, but subtraction of IgG from GB did not modify the ChCDT. CONCLUSIONS: Biliary cholesterol transport and saturation, but not proteins, appear critical for the cholesterol crystallization abnormality observed in native bile from patients with gallstones.
Assuntos
Bile/metabolismo , Colesterol/metabolismo , Vesícula Biliar/metabolismo , Colecistite/metabolismo , Cristalização , Feminino , Glicoproteínas/metabolismo , Humanos , Imunoglobulina G/metabolismo , Metabolismo dos Lipídeos , Masculino , Pessoa de Meia-Idade , Análise de Regressão , Fatores de TempoRESUMO
BACKGROUND: Patients with acute pancreatitis (AP) and a normal gallbladder by standard echographic evaluation may have "occult" gallbladder disease or microlithiasis with recurrent episodes of AP. AIM: To conduct a prospective evaluation of patients with the diagnosis of non-biliary AP in order to detect "occult" gallbladder disease and to compare its clinical presentation with that of biliary AP. PATIENTS AND METHODS: Patients admitted with the diagnosis of AP to a clinical hospital were included in the study. According to an abdominal ultrasound study, patients were classified as having or not cholelithiasis. A duodenal biliary drainage was performed in 15 patients with AP and without gallbladder stones. RESULTS: Patients without cholelithiasis had recurrent AP more often than patients with biliary AP (53 and 3.3% respectively). Excessive alcohol ingestion did not rule out the possibility of biliary etiology. In 6 patients, the analysis of duodenal bile showed cholesterol crystals, and cholecystectomy confirmed the existence of gallbladder disease in 5. All of them remained asymptomatic during a follow-up period of four years. One patient refused surgery, with subsequent development of gallstones and recurrent episodes of AP. In other 4 patients, gallbladder disease was confirmed by percutaneous gallbladder puncture or during cholecystectomy. No recurrence of AP were observed during the follow-up CONCLUSIONS: Microlithiasis or "occult" gallbladder disease accounts for at least 67% of the original "non-biliary" AP. Duodenal bile analysis is a useful and necessary technique for the evaluation of patients with "non-biliary" acute pancreatitis. Careful clinical and echographic follow-up of this subgroup of patients with AP is mandatory.
Assuntos
Colelitíase/complicações , Pancreatite/complicações , Doença Aguda , Adulto , Idoso , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Pancreatite/sangue , Estudos Prospectivos , Fatores de Risco , Cálculos da Bexiga Urinária/complicaçõesRESUMO
Biliary cholesterol represents one of the two major excretory pathways for sterol elimination from the body and plays a central role in cholesterol gallstone formation. Biliary cholesterol originates from a precursor pool of preformed and newly synthesized free cholesterol. Although it has been suggested that newly synthesized and preformed biliary cholesterol are secreted by independent pathways, the specific cellular and molecular mechanisms are unknown. We used male Wistar rats to study the time-course of the appearance of newly synthesized cholesterol, phosphatidylcholine and protein into bile. The specific role of sterol carrier protein-2 (SCP-2) in the transport of newly synthesized biliary cholesterol was evaluated by an in vivo antisense oligonucleotide approach. In contrast to [14C]phosphatidylcholine and [35S]proteins, the time-course of [14C]cholesterol appearance into bile was rapid, and microtubule- and Golgi-independent. In vivo SCP-2 antisense treatment reduced and delayed the appearance of biliary [14C]cholesterol. Furthermore, hepatic SCP-2 expression increased more than 3-fold over control values in rats that had been treated with diosgenin to increase biliary secretion of newly synthesized cholesterol. These results suggest that SCP-2 is necessary for the rapid transport of newly synthesized cholesterol into bile and that hepatocytes can induce SCP-2 expression according to the rate of biliary secretion of newly synthesized cholesterol.
Assuntos
Bile/metabolismo , Proteínas de Transporte/metabolismo , Colesterol/metabolismo , Fígado/efeitos dos fármacos , Proteínas de Plantas , Animais , Sequência de Bases , Transporte Biológico , Proteínas de Transporte/genética , Colchicina/farmacologia , Diosgenina/administração & dosagem , Diosgenina/farmacologia , Cinética , Fígado/metabolismo , Masculino , Dados de Sequência Molecular , Monensin/farmacologia , Oligonucleotídeos Antissenso/farmacologia , Fosfatidilcolinas/metabolismo , Proteínas/metabolismo , Ratos , Ratos WistarRESUMO
The cellular mechanism of cholesterol transport from the endoplasmic reticulum to the plasma membrane is currently unknown. To assess the possibility that sterol carrier protein-2 (SCP-2) is involved in this transport, we studied the time course of newly synthesized cholesterol incorporation in the plasma membrane of normal and SCP-2-deficient (Zellweger syndrome) human fibroblasts. Cholesterol transfer was rapid, cytoskeleton-independent, and Golgi-independent in normal cells, but it was slower, cytoskeleton-dependent, and Golgi-dependent in SCP-2-deficient cells. After SCP-2 antisense oligonucleotides treatment of normal fibroblasts, the rapid transport was reduced by 81% with a simultaneous increase of the slower one. These results suggest that in normal fibroblasts the major fraction of newly synthesized cholesterol is transported to the plasma membrane by a SCP-2-dependent mechanism. In contrast, in SCP-2-deficient cells, newly synthesized cholesterol leaves the endoplasmic reticulum by a cytoskeleton/Golgi-dependent mechanism.
Assuntos
Proteínas de Transporte/fisiologia , Membrana Celular/metabolismo , Colesterol/metabolismo , Retículo Endoplasmático/metabolismo , Proteínas de Plantas , Sequência de Bases , Células Cultivadas , Colchicina/farmacologia , Citoesqueleto/metabolismo , Fibroblastos/metabolismo , Complexo de Golgi/metabolismo , Humanos , Dados de Sequência Molecular , Oligonucleotídeos Antissenso/farmacologiaRESUMO
We have shown that patients with previous acute pancreatitis (AP) may have an abnormal catabolism of chylomicron remnants (CMR). Because apoprotein E (Apo E) genetic polymorphism has an important influence on CMR clearance, we compared frequency distribution of Apo E phenotypes in 52 patients with AP, 109 patients with gallstones, and 110 control subjects. Apo E phenotypes were detected by isoelectric focusing and immunoblotting. After adjusting for differences in age and gender, fasting triglyceride level was comparable between the study groups. The frequency distribution of Apo E phenotypes was not different between the three study groups and it was in Hardy-Weinberg equilibrium. The gene frequency for Apo E2 was 0.212, 0.273, and 0.243 in AP, gallstone, and control group, respectively. For Apo E3 it was 0.701, 0.627, and 0.674, and for Apo E4 0.090, 0.100, and 0.083 in the same groups, respectively. Differences were not statistically significant (chi 2). In conclusion, the abnormal catabolism of CMR in patients with AP is not attributable to Apo E polymorphism. An alternative explanation may be sought in the activity of the recently identified hepatocytic Apo E receptor [LDL-related receptor protein (LRP)].
Assuntos
Apolipoproteínas E/genética , Pancreatite/genética , Polimorfismo Genético , Doença Aguda , Adulto , Alelos , HDL-Colesterol/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pancreatite/sangue , alfa-Macroglobulinas/metabolismoRESUMO
Feeding a 0.5% diosgenin plus 0.02% simvastatin diet to rats increases biliary cholesterol concentration and saturation to levels generally found in human native supersaturated bile. By using preparative ultracentrifugation, gel filtration chromatography, and electron microscopy, we isolated, purified, and identified lamellar structures (unilamellar vesicles and multilamellae) as a major biliary cholesterol transport in supersaturated human and rat bile. It was estimated that more than 60% of biliary cholesterol is transported in these lamellar carriers, which were identified by transmission electron microscopy as unilamellar vesicles and multilamellar bodies within bile canaliculi of rats with cholesterol supersaturated bile. By SDS-PAGE, a characteristic and constant protein profile was found associated to the purified lamellar carriers. One of these proteins, a 130-kDa protein, was isolated from human biliary lamellae and used for preparation of a rabbit polyclonal antibody, which cross-reacted with the homologous rat protein. By Western blotting, it was established that the purified low density fraction of bile-Metrizamide gradients, containing lamellae, was enriched with the 130-kDa protein. The 130-kDa protein was characteristically detected at the canalicular membrane by Western blotting of hepatic subcellular fractions and by immunohistochemistry of rat and human liver biopsies. Amino acid sequencing of the amino terminus of the 130-kDa protein demonstrated a complete identity with aminopeptidase N, a canalicular transmembrane hydrophobic glycoprotein. These studies show that biliary lipids may acquire an ordered multilamellar structure that is present in the canaliculi of rats with supersaturated bile. These biliary lamellae are similar to lamellar bodies and surfactant-like material frequently found in other epithelia, suggesting common biogenetic, structural, and functional properties. The identification of aminopeptidase N associated with biliary lamellae is consistent with the involvement of the canalicular membrane in the secretory mechanism of biliary lipids.
Assuntos
Aminopeptidases/análise , Bile/química , Proteínas de Transporte/análise , Colesterol/metabolismo , Sequência de Aminoácidos , Aminopeptidases/química , Aminopeptidases/isolamento & purificação , Animais , Bile/metabolismo , Antígenos CD13 , Proteínas de Transporte/química , Proteínas de Transporte/isolamento & purificação , Centrifugação com Gradiente de Concentração , Diosgenina/farmacologia , Humanos , Immunoblotting , Imuno-Histoquímica , Fígado/química , Fígado/efeitos dos fármacos , Fígado/metabolismo , Lovastatina/análogos & derivados , Lovastatina/farmacologia , Masculino , Metrizamida , Microscopia Eletrônica , Dados de Sequência Molecular , Proteínas/metabolismo , Coelhos , Ratos , Ratos Wistar , SinvastatinaRESUMO
Different hydrophobic glycoproteins are associated to native biliary vesicles, which are the major carrier of biliary cholesterol. Some of these proteins promote cholesterol crystallization, a key step in cholesterol gallstone formation. This study was specifically conducted to identify the 130 kDa biliary vesicle-associated glycoprotein and to determine its in vitro effect on the cholesterol crystal formation time. The 130 kDa vesicular glycoprotein was identified as aminopeptidase-N by amino acid sequencing and specific enzymatic assay. Polyclonal antibodies raised against aminopeptidase-N allowed us to determine its concentration in human hepatic bile, which varied from 17.3 to 57.6 micrograms/ml. Aminopeptidase-N showed a concentration-dependent cholesterol crystallization activity when it was added to supersaturated model bile at a concentration range usually found in native bile. Because of this promoting effect on in vitro cholesterol crystal formation, we suggest that biliary aminopeptidase-N may play a critical role in the pathogenesis of cholesterol gallstone disease.
Assuntos
Aminopeptidases/metabolismo , Bile/enzimologia , Colesterol/química , Lipídeos/análise , Sequência de Aminoácidos , Aminopeptidases/química , Animais , Bile/química , Antígenos CD13 , Colesterol/metabolismo , Cristalização , Glicoproteínas/análise , Glicoproteínas/química , Glicoproteínas/metabolismo , Humanos , Rim/enzimologia , Dados de Sequência Molecular , Desnaturação Proteica , SuínosRESUMO
Cholesterol is transported both in unilamellar phosphatidylcholine vesicles and in bile salts-mixed micelles in native bile. The vesicular carrier of biliary lipids apparently has a well defined protein profile with a potent cholesterol crystallization-promoting activity. This study was conducted to identify and further characterize these vesicular proteins and to test the effect of isolated vesicular proteins on the cholesterol crystal formation in supersaturated model bile. The results confirmed that proteins are a constant component of highly purified biliary vesicles both in hepatic and gallbladder bile. Immunoglobulins (IgA, IgG and IgM) and albumin are associated to the purified hepatic biliary vesicles. Furthermore, four different hydrophobic glycoproteins with a molecular mass of 130, 114, 86, and 62-67 kDa were isolated. These glycoproteins showed no reactivity with anti-human whole serum or anti-immunoglobulin antibodies, suggesting that these proteins are biliary-specific. Isolated 130, 114 and 62-67 kDa vesicular glycoproteins significantly decreased the cholesterol nucleation time in artificial model bile. We concluded that some, but not all, vesicular-bound hydrophobic glycoproteins have cholesterol pronucleating activity and they may be involved in the pathogenesis of cholesterol gallstone disease.
Assuntos
Bile/metabolismo , Colesterol/metabolismo , Glicoproteínas/isolamento & purificação , Western Blotting , Colelitíase/metabolismo , Cromatografia Líquida , Cristalização , Eletroforese em Gel de Poliacrilamida , Glicoproteínas/metabolismo , HumanosRESUMO
The knowledge of the epidemiology of cholesterol gallstones is mainly descriptive in Chile. Prevalence data has been gathered from several autopsy studies. The prevalence in these studies is similar to the prevalence determined in a cholecystographic study in a sample of the population of Santiago: 51% of women and 17% of men harbor gallstones, or have been cholecystectomized. The risk factors of the disease are well known and include sex, age, obesity, pregnancy, female sex hormones and hypotriglyceridemic drugs, there is scarce data on the natural history of gallstone disease. In this article we review the present knowledge of both the epidemiology and natural history of gallstones. In addition, we present some specific questions related to the potential identification of environmental and genetic risk factors in epidemiological studies. It is stressed that the knowledge of the natural history of gallstone disease is critical for the appropriate rational management of silent gallstones.
Assuntos
Colelitíase , Colelitíase/epidemiologia , Colelitíase/etiologia , Colelitíase/terapia , Feminino , Humanos , Masculino , Fatores de RiscoRESUMO
1. Cholesterol nucleation is a critical step in the formation of cholesterol gallstones. This nucleation takes place after aggregation and fusion of cholesterol-rich biliary vesicles, a process probably modulated by biliary proteins. The present study was conducted to identify specific proteins associated with native cholesterol-rich biliary vesicles and to explore their effect on the cholesterol-nucleation time of supersaturated artificial bile. 2. Hepatic bile was obtained from six patients with cholesterol gallstone disease. Biliary vesicles were isolated by ultracentrifugation and were purified by gel filtration chromatography. A small amount of protein (less than 1% by weight) remained associated with the purified cholesterol-rich biliary vesicles. The electrophoretic profile of these proteins was remarkably similar in all six patients, showing the presence of at least six polypeptides (of molecular mass from 52 to 200 kDa), five of them having carbohydrate residues (except the 52 kDa one). The effect of reconstituted biliary vesicle solutions, containing their specific vesicular proteins, on cholesterol-nucleation time was studied by mixing the vesicle solution with artificial supersaturated bile. A potent cholesterol-pronucleating activity, reflected in a 20-70% reduction in nucleation time, was present in the biliary vesicle solutions compared with control solutions having a similar lipid composition. The pronucleating activity disappeared on heating and was not detected in the micellar fraction containing the major proportion of biliary proteins. 3. These results indicate that cholesterol-rich biliary vesicles containing a unique and defined glycoprotein profile can be isolated and purified from human hepatic bile. The potent cholesterol-pronucleating activity of the biliary vesicles from patients with gallstones was unrelated to their lipid composition or cholesterol content.(ABSTRACT TRUNCATED AT 250 WORDS)