RESUMO
Los niveles de bilirrubina sérica normal en el adulto varían entre 0,3 mg/dL y 1,2 mg/dL, y su valor está determinado por la tasa de captación hepática, conjugación y excreción. La ictericia se hace evidente cuando los niveles de bilirrubina sérica se elevan por encima de 2,5 mg/dL a 3 mg/dL, siendo un indicador de enfermedad subyacente. La bilis es producida por los hepatocitos y fluye desde los canalículos, canales de Hering, conductos biliares intrahepáticos, conductos hepáticos derechos e izquierdos hasta llegar al duodeno. A nivel histopatológico, cualquier entidad que lleve a la acumulación intrahepática de bilis por disfunción hepatocelular u obstrucción biliar genera colestasis, que se observa en la biopsia hepática como la acumulación de tapones de color marrón verdoso de pigmento biliar en los hepatocitos, y secundariamente se observan los canalículos dilatados. Las causas de colestasis intrahepática son diversas e incluyen enfermedades como colangitis biliar primaria, colangitis esclerosante primaria, hepatitis autoinmune, hepatitis virales y toxicidad medicamentosa. Esta revisión tiene como objetivo analizar algunos tipos de hiperbilirrubinemia, resaltando sus características histopatológicas.
Normal serum bilirubin levels in adults range from 0.3 mg/dL to 1.2 mg/dL, and its value is determined by the rate of hepatic uptake, conjugation, and excretion. Jaundice becomes apparent when serum bilirubin levels rise above 2.5 mg/dL to 3.5 mg/dL and is an indicator of underlying disease. Bile is produced by hepatocytes and flows from the canaliculi, Hering's canals, intrahepatic bile ducts, and right and left hepatic ducts to the duodenum. Pathologically, any condition that leadsto intrahepatic accumulation of bile due to hepatocellular dysfunction or biliary obstruction, generates cholestasis, which is observed in liver biopsy as the accumulation of greenish-brown deposits of bile pigment in hepatocytes, with dilated canaliculi. The causes of intrahepatic cholestasis are diverse and include diseases such as primary biliary cholangitis and primary sclerosing cholangitis, autoimmune hepatitis, viral hepatitis, and drug toxicity. This review aims to analyze some types of hyperbilirubinemia, highlighting their histopathological characteristics.
Assuntos
Humanos , Patologistas , Hiperbilirrubinemia , Icterícia , Bile , Ductos Biliares Intra-Hepáticos , Pigmentos Biliares , Bilirrubina , Biópsia , Colangite Esclerosante , Colestase , Colestase Intra-Hepática , Hepatite Autoimune , Hepatite , Fígado , Cirrose Hepática BiliarRESUMO
Red/far-red light-sensing bacteriophytochrome photoreceptor (BphP) pathways play key roles in bacterial physiology and ecology. These bilin-binding proteins photoswitch between two states, Pr (red absorbing) and Pfr (far-red absorbing). The isomerization of the chromophore and the downstream structural changes result in the light signal transduction. The agricultural pathogen Xanthomonas campestris pv. campestris (Xcc) code for a single bathy-like type BphP (XccBphP), previously shown to negatively regulate several light-mediated biological processes involved in virulence. Here, we generated three different full-length variants with single amino acid changes within its GAF domain that affect the XccBphP photocycle favouring its Pr state: L193Q, L193N and D199A. While D199A recombinant protein locks XccBphP in a Pr-like state, L193Q and L193N exhibit a significant enrichment of the Pr form in thermal equilibrium. The X-ray crystal structures of the three variants were solved, resembling the wild-type protein in the Pr state. Finally, we studied the effects of altering the XccBphP photocycle on the exopolysaccharide xanthan production and stomatal aperture assays as readouts of its bacterial signalling pathway. Null-mutant complementation assays show that the photoactive Pr-favoured XccBphP variants L193Q and L193N tend to negatively regulate xanthan production in vivo. In addition, our results indicate that strains expressing these variants also promote stomatal apertures in challenged plant epidermal peels, compared to wild-type Xcc. The findings presented in this work provide new evidence on the Pr state of XccBphP as a negative regulator of the virulence-associated mechanisms by light in Xcc.
Assuntos
Arabidopsis/microbiologia , Pigmentos Biliares/metabolismo , Fitocromo/química , Fitocromo/genética , Doenças das Plantas/microbiologia , Virulência , Xanthomonas campestris/fisiologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Cristalografia por Raios X , Luz , Modelos Moleculares , Mutagênese Sítio-Dirigida , Mutação , Fitocromo/metabolismoRESUMO
The bilin-binding proteins (BBP) from lepidopteran insects are members of the lipocalin family of proteins and play a special role in pigmentation through the binding of biliverdin IXγ. Lopap, a BBP-like protein from the venom of the toxic caterpillar Lonomia obliqua has been reported to act as a serine protease that activates the coagulation proenzyme prothrombin. Here we show that BBPLo, a variant of lopap from the same organism binds biliverdin IXγ, forming a complex that is spectrally identical with previously described BBP proteins. Although BBPLo is nearly identical in sequence to lopap, no prothrombinase activity was detected in our recombinant preparations using reconstituted systems containing coagulation factors Xa and Va, as well as anionic phospholipids. In addition to biliverdin, BBPLo was found to form a 1:1 complex with heme prompting us to examine whether the unusual biliverdin IXγ ligand of BBPs forms as a result of oxidation of bound heme in situ rather than by a conventional heme oxygenase. Using ascorbate or a NADPH(+)-ferredoxin reductase-ferredoxin system as a source of reducing equivalents, spectral changes are seen that suggest an initial reduction of heme to the Fe(II) state and formation of an oxyferrous complex. The complex then disappears and a product identified as a 5-coordinate carbonyl complex of verdoheme, an intermediate in the biosynthesis of biliverdin, is formed. However, further reaction to form biliverdin was not observed, making it unlikely that biliverdin IXγ is formed by this pathway.
Assuntos
Pigmentos Biliares/química , Endopeptidases/metabolismo , Proteínas de Insetos/metabolismo , Lepidópteros/enzimologia , Sequência de Aminoácidos , Animais , Pigmentos Biliares/farmacologia , Endopeptidases/química , Ferredoxina-NADP Redutase/química , Heme/análogos & derivados , Heme/química , Heme/farmacologia , Proteínas de Insetos/química , Ligantes , Dados de Sequência Molecular , Oxirredução , Ligação Proteica , Especificidade por SubstratoRESUMO
Sixty-five samples of propolis were collected from eleven regions of Cuba; methanolic extracts of propolis were prepared from all samples, and a classification method was developed using a combination of NMR, HPLC-PDA, and HPLC-ESI/MS techniques. The analysis of (1)H and (13)C NMR spectra and chromatographic profiles of all propolis extracts allowed the definition of three main types of Cuban propolis directly related to their secondary metabolite classes: brown Cuban propolis (BCP), rich in polyisoprenylated benzophenones, red Cuban propolis (RCP), containing isoflavonoids as the main constituents, and yellow Cuban propolis (YCP), probably with aliphatic compounds. Subsequently, the principal compounds of the brown and red types were characterized by HPLC-ESI/MS analysis. Instrumental techniques used are complementary; NMR was shown to be a quick and informative tool for the rapid analysis of crude propolis polar extracts and allowed the identification of the main class of secondary metabolites, while LC-PDA and LC-MS techniques were useful tools for qualitative and quantitative analysis of marker compounds of Cuban propolis.
Assuntos
Própole/química , Própole/classificação , Pigmentos Biliares , Cromatografia Líquida de Alta Pressão , Cuba , Espectroscopia de Ressonância Magnética , Especificidade da Espécie , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Hemoglobin digestion in the midgut of hematophagous animals results in the release of its prosthetic group, heme, which is a pro-oxidant molecule. Heme enzymatic degradation is a protective mechanism that has been described in several organisms, including plants, bacteria, and mammals. This reaction is catalyzed by heme oxygenase and results in formation of carbon monoxide, ferrous ion, and biliverdin IXalpha. During digestion, a large amount of a green pigment is produced and secreted into the intestinal lumen of Aedes aegypti adult females. In the case of another blood-sucking insect, the kissing-bug Rhodnius prolixus, we have recently shown that heme degradation involves a complex pathway that generates dicysteinyl-biliverdin IX gamma. The light absorption spectrum of the Aedes purified pigment was similar to that of biliverdin, but its mobility on a reverse-phase chromatography column suggested a compound less hydrophobic than biliverdin IXalpha. Structural characterization by ESI-MS revealed that the mosquito pigment is the alpha isomer of biliverdin bound to two glutamine residues by an amide bond. This biglutaminyl-biliverdin is formed by oxidative cleavage of the heme porphyrin ring followed by two subsequent additions of glutamine residues to the biliverdin IXalpha. The role of this pathway in the adaptation of this insect vector to a blood-feeding habit is discussed.
Assuntos
Aedes/metabolismo , Biliverdina/análogos & derivados , Heme/metabolismo , Animais , Pigmentos Biliares/química , Pigmentos Biliares/isolamento & purificação , Biliverdina/química , Biliverdina/metabolismo , Dengue , Proteínas de Insetos/metabolismo , Insetos Vetores , Modelos Moleculares , Dados de Sequência Molecular , Pigmentos Biológicos/química , Pigmentos Biológicos/isolamento & purificação , Pigmentos Biológicos/metabolismoRESUMO
Since the excretion of potentially toxic cholephilic organic anions (COAs) produced by the fetus, such as bile acids and biliary pigments, cannot be performed by the fetal liver alone, the placenta and the maternal liver must play a key role collaborating in this function. COAs are transported across the plasma membranes of fetal and maternal hepatocytes and trophoblastic cells via similar carrier proteins. OATPs (organic anion-transporting polypeptides), mainly OATP1B1 and OATP1B3 are involved in COA uptake across the basal membrane of adult hepatocytes and trophoblastic cells. Certain OATPs may also play a role in COA efflux from fetal hepatocytes toward the fetal blood and from the trophoblast to the maternal blood. Either unmodified or biotransformed during their transit across the placenta, COAs are transferred to the maternal blood by MRPs (multidrug resistance-associated proteins), such as MRP1, MRP2 and MRP3. BCRP (breast cancer resistance protein) may also be involved in this step. Under physiological circumstances, fetal COAs are taken up by the maternal liver, which eliminates them across the canalicular membrane via MRP2 and BSEP (bile salt export pump). However, when normal biliary excretion is not possible, the accumulation of COAs, in particular in the fetal liver, placenta and maternal liver trio, induces oxidative stress and apoptosis, which has noxious repercussions on normal fetal development and even challenges pregnancy outcome. Treatment of pregnant rats with ursodeoxycholic acid, even though maternal hypercholanemia is not corrected, prevents oxidative damage and the subsequent deleterious effects on the placenta and fetal liver.
Assuntos
Ácidos e Sais Biliares/metabolismo , Pigmentos Biliares/metabolismo , Fígado/embriologia , Fígado/metabolismo , Troca Materno-Fetal , Placenta/metabolismo , Animais , Feminino , Feto/metabolismo , Humanos , Troca Materno-Fetal/genética , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/metabolismo , Gravidez , RNA Mensageiro/metabolismo , RatosRESUMO
Hydrochlorous acid bleaches c-phycocyanin visible absorbance with a second-order rate constant (pH 7.4) of 1.3x10(3) M(-1) s(-1). In excess of protein, ca. 0.16 bilin moieties are disrupted by each reacted HOCl molecule. This indicates that the main reaction takes place at the apoprotein level, with a total rate constant (in monomeric units concentration) of 2.5x10(4) M(-1) s(-1). This rate constant is too low to provide protection to other biomolecules under physiological conditions. The reported antiinflammatory properties of phycocyanin are not then related to the removal of HOCl. On the other hand, the rather slow reaction rate with HOCI could be beneficial to its role as antiinflammatory agent since it will allow the protein to maintain its integrity at the inflammation locus.
Assuntos
Ácido Hipocloroso/química , Ficocianina/química , Pigmentos Biliares/química , Catalase/metabolismo , Cianobactérias/enzimologia , Cinética , Espectrofotometria , Análise EspectralRESUMO
Previously we have reported on the pigmentary lithogenic action of vitamin A in the form of retinol acetate. In the present work the possible lithogenic action of retinoic acid was tested, since this differs from retinol in several metabolic aspects, which can contribute to the understanding of the pathogenesis of the pigment cholelithiasis produced by vitamin A. Two experiments were performed in which the lithogenicity of retinol acetate added to a colony chow at the level of 25,000 IU%, was compared with that of 3 dietetic levels of all-trans retinoic acid. In the first experiment seric triglycerides were determined in order to establish whether there is a relation between the hypertriglyceridemic effect of retinoids and their lithogenicity; in the second experiment GPT and GOT were determined as indicators of hepatotoxicity. The results showed that the retinoic acid at levels of 24,000 and 35,000 IU% of diet, produced a cholelithiasis incidence similar to that of 25,000 IU% of retinol acetate, whereas the retinoic acid level of 12,000 IU% was not lithogenic. The dietetic retinoic acid produced a reduction of hepatic vitamin A, that was directly proportional to the level supplied. There was no relation between the hypertriglyceridemic effect of retinoids and its lithogenicity. The retinoids produced a light increase in GPT, which was higher with retinol acetate, whereas GOT had not significative changes. It is concluded that all-trans retinoic acid produces pigment gallstones in the hamster, with an incidence similar to that produced by retinol acetate.