Fractura de cadera por fragilidad en México: ¿En dónde estamos hoy? ¿Hacia dónde queremos ir? / Fragile hip fracture in Mexico: Where are we today? Where do we want to go?

Resumen: Introducción: La fractura de cadera (FC) se considera la consecuencia más grave de las caídas y la osteoporosis. Dieciocho por ciento de las mujeres sufrirán una FC y 25% muere en el primer año. Sólo 73% de los supervivientes caminará como lo hacía previamente. Conocemos poco de la asistencia y evolución de la FC en México. Objetivo: Revisar el estado actual de la literatura mexicana sobre FC, comparar estudios mexicanos entre sí y con los indicadores de calidad. Metodología: Se realizó una búsqueda de artículos mexicanos publicados entre 2000 y 2017 con las palabras clave: fractura de cadera, ancianos, México y hip fracture en las bases de datos PubMed, EBSCO y Bibliomed. Resultados: Se incluyeron 22 artículos. No se encontraron ensayos clínicos, informes de unidades multidisciplinarias, registros, ni metaanálisis. La media de edad fue de 76.9 años y 67.2% fueron mujeres. No se encontraron trabajos que reportaran indicadores de calidad. La comorbilidad se describe poco. Las complicaciones más frecuentes de la FC fueron delirium, neumonía y úlceras por presión. La mortalidad en la fase aguda fue de 0.97 a 12.5%. No se reportaron unidades ortogeriátricas. El costo de atención osciló entre 1,261 y 13,641 dólares estadounidenses (USD). Conclusiones: La información científica sobre FC en México es escasa, heterogénea y no permite obtener resultados concluyentes. Se requiere aumentar la cantidad y la calidad de la investigación en FC en México. Sería también conveniente difundir la utilidad de los equipos multidisciplinarios y registros de FC, lo que contribuiría a mejorar la atención.

Abstract: Introduction: Hip fracture is considered the most serious consequence of falls and osteoporosis. 18% of women will suffer one and 25% die in the first year. Only 73% of survivors will walk as they did previously. We know little about the assistance and evolution of it in Mexico. Our goal was to review the current state of Mexican literature on hip fracture, compare Mexican studies with each other and with quality indicators. Methods: We conducted a search of Mexican articles published between 2000-2017 with the key words: hip fracture, elderly, Mexico and hip fracture (in English) in the databases PubMed, EBSCO and Bibliomed. Results: Twenty-one articles were included. No clinical trials, multidisciplinary unit reports, records, or meta-analyses were found. The average age was 76.9 years and 67.2% were women. No papers were found to report quality indicators. Comorbidity is reported little. The most common complications of hip fractures were delirium, pneumonia and pressure ulcers. Mortality in the acute phase was 0.97 to 12.5%. Special units were not reported. The cost of care oscillated between 1,261 and 13,641 USD. Conclusions: The scientific information on hip fractures in Mexico is sparse, heterogeneous and does not allow for conclusive results. Increasing the amount and quality of research in hip fractures in Mexico is required. It would also be advisable to disseminate the usefulness of multidisciplinary teams and registry of hip fractures, which would help to improve attention.

Epidemiologic Study and Genotyping of BK Virus in Renal Transplant Recipients.

BK virus (BKV) infection occurs during childhood and remains latent in the urinary tract. The virus is reactivated in immunosuppressed patients, particularly in those with cellular immunity deficiency, allowing its detection in urine and blood. Nephropathy caused by the virus in renal transplantation recipients may lead to graft failure. The purpose of this study is to know the prevalence of BKV variables in renal transplantation recipients and to evaluate their clinical evolution through molecular methods of "in house" development. Urine and peripheral blood samples from 66 renal transplantation recipients from the province of Buenos Aires, Argentina, were systematically analyzed every 3 months as well as when there was graft dysfunction. Renal biopsies, which were included in the BKV detection study, were performed on those patients with graft dysfunction. Genotyping of 24 BKVs was performed, and the following distribution was found: 21 (87.5%) belonged to subtype I, 3 (12.5%) to subtype II. BKV belonging to subtypes III or IV were not found. As regards subtype I subgroups, the following were identified: 1 (4.76%) from Ia, 10 (47.61%) from Ib1 and 10 (47.61%) from Ib2. Presence of subgroup Ic was not shown. Viremia presented in 33.33% of cases, whereas 75% corresponded to subgroup Ib 1. Genotype Ib1 is prevailing in Southeast Asia, while Ib2 is prominent in Europe. Although an important proportion of the inhabitants of the province of Buenos Aires are European descendants, the prevailing genotype is Ib1, the Asian type. Genotyping might be related to the evolution of the disease in the recipient.

[Fragile hip fracture in Mexico: Where are we today? Where do we want to go?] / Fractura de cadera por fragilidad en México: ¿En dónde estamos hoy? ¿Hacia dónde queremos ir?

INTRODUCTION: Hip fracture is considered the most serious consequence of falls and osteoporosis. 18% of women will suffer one and 25% die in the first year. Only 73% of survivors will walk as they did previously. We know little about the assistance and evolution of it in Mexico. Our goal was to review the current state of Mexican literature on hip fracture, compare Mexican studies with each other and with quality indicators. METHODS: We conducted a search of Mexican articles published between 2000-2017 with the key words: hip fracture, elderly, Mexico and hip fracture (in English) in the databases PubMed, EBSCO and Bibliomed. RESULTS: Twenty-one articles were included. No clinical trials, multidisciplinary unit reports, records, or meta-analyses were found. The average age was 76.9 years and 67.2% were women. No papers were found to report quality indicators. Comorbidity is reported little. The most common complications of hip fractures were delirium, pneumonia and pressure ulcers. Mortality in the acute phase was 0.97 to 12.5%. Special units were not reported. The cost of care oscillated between 1,261 and 13,641 USD. CONCLUSIONS: The scientific information on hip fractures in Mexico is sparse, heterogeneous and does not allow for conclusive results. Increasing the amount and quality of research in hip fractures in Mexico is required. It would also be advisable to disseminate the usefulness of multidisciplinary teams and registry of hip fractures, which would help to improve attention.

INTRODUCCIÓN: La fractura de cadera (FC) se considera la consecuencia más grave de las caídas y la osteoporosis. Dieciocho por ciento de las mujeres sufrirán una FC y 25% muere en el primer año. Sólo 73% de los supervivientes caminará como lo hacía previamente. Conocemos poco de la asistencia y evolución de la FC en México. OBJETIVO: Revisar el estado actual de la literatura mexicana sobre FC, comparar estudios mexicanos entre sí y con los indicadores de calidad. METODOLOGÍA: Se realizó una búsqueda de artículos mexicanos publicados entre 2000 y 2017 con las palabras clave: fractura de cadera, ancianos, México y hip fracture en las bases de datos PubMed, EBSCO y Bibliomed. RESULTADOS: Se incluyeron 22 artículos. No se encontraron ensayos clínicos, informes de unidades multidisciplinarias, registros, ni metaanálisis. La media de edad fue de 76.9 años y 67.2% fueron mujeres. No se encontraron trabajos que reportaran indicadores de calidad. La comorbilidad se describe poco. Las complicaciones más frecuentes de la FC fueron delirium, neumonía y úlceras por presión. La mortalidad en la fase aguda fue de 0.97 a 12.5%. No se reportaron unidades ortogeriátricas. El costo de atención osciló entre 1,261 y 13,641 dólares estadounidenses (USD). CONCLUSIONES: La información científica sobre FC en México es escasa, heterogénea y no permite obtener resultados concluyentes. Se requiere aumentar la cantidad y la calidad de la investigación en FC en México. Sería también conveniente difundir la utilidad de los equipos multidisciplinarios y registros de FC, lo que contribuiría a mejorar la atención.

Kca3.1 Activation Via P2y2 Purinergic Receptors Promotes Human Ovarian Cancer Cell (Skov-3) Migration.

Disorders in cell signaling mediated by ATP or histamine, activating specific membrane receptors, have been frequently associated with tumorigenesis. Among the elements of response to purinergic (and histaminergic) signaling, ion channel activation controls essential cellular processes in cancer, such as cell proliferation, motility, and death. Here, we studied the effects that ATP had on electrical properties of human ovarian adenocarcinoma cells named SKOV-3. ATP caused increase in intracellular Ca2+ concentration ([Ca2+]i) and, concurrently, it evoked a complex electrical response with a conspicuous outward component. This current was generated through P2Y2 receptor activation and opening of K+ channels, KCa3.1, as indicated by electrophysiological and pharmacological analysis, as well as by immunodetection and specific silencing of P2Y2 or KCa3.1 gene by esiRNA transfection. Low µM ATP concentration increased SKOV-3 cell migration, which was strongly inhibited by KCa3.1 channel blockers and by esiRNA-generated P2Y2 or KCa3.1 downregulation. Finally, in human ovarian tumors, the P2Y2 and KCa3.1 proteins are expressed and co-localized in neoplastic cells. Thus, stimulation of P2Y2 receptors expressed in SKOV-3 cells promotes motility through KCa3.1 activation. Since P2Y2 and KCa3.1 are co-expressed in primary tumors, our findings suggest that they may play a role in cancer progression.

The P2RY2 Receptor Induces Carcinoma Cell Migration and EMT Through Cross-Talk With Epidermal Growth Factor Receptor.

Extracellular nucleotides are signaling elements present in the tumor microenvironment; however, their role in tumor growth is not completely understood. In the present study, we asked whether nucleotides regulate cell migration in ovarian carcinoma-derived cells. We observed that 100 µM UTP induced migration in SKOV-3 cells (1.57 ± 0.08 fold over basal), and RT-PCR showed expression of transcripts for the P2RY2 and P2RY4 receptors. Knockdown of P2RY2 expression in SKOV-3 cells (P2RY2-KD) abolished the UTP-induced migration. The mechanism activated by UTP to induce migration involves transactivation of the epidermal growth factor receptor (EGFR) since we observed that the EGFR kinase inhibitor AG1478 and the PI3K inhibitor Wortmannin inhibit this response (to 0.76 ± 0.23 and 0.46 ± 0.14 relative to the control, respectively). In agreement with these observations, UTP was able to modify the phosphorylation state of the EGFR; likewise, the induction of ERK1/2 phosphorylation promoted by UTP was abolished by a 30-60 min treatment with AG1478. Our data also suggested that the enhanced cell migration involves the epithelium to mesenchymal transition (EMT) process, since a 12 h stimulation of SKOV-3 cells with 100 µM UTP showed an increase in vimentin and SNAIL protein levels (459.8 ± 132.4% over basal for SNAIL). Interestingly, treatment with apyrase (10 U/mL) reduces the migration of control cells and induces a considerable enrichment of E-cadherin in the cell-cell contacts, favoring an epithelial phenotype and strongly suggesting that the nucleotides released by tumor cells and acting through the P2RY2 receptor are potential regulators of invasiveness.

Impaired localisation and transport function of canalicular Bsep in taurolithocholate induced cholestasis in the rat.

BACKGROUND: Taurolithocholate induced cholestasis is a well established model of drug induced cholestasis with potential clinical relevance. This compound impairs bile salt secretion by an as yet unclear mechanism. AIMS: To evaluate which step/s of the hepatocellular bile salt transport are impaired by taurolithocholate, focusing on changes in localisation of the canalicular bile salt transporter, Bsep, as a potential pathomechanism. METHODS: The steps in bile salt hepatic transport were evaluated in rats in vivo by performing pharmacokinetic analysis of (14)C taurocholate plasma disappearance. Bsep transport activity was determined by assessing secretion of (14)C taurocholate and cholyl-lysylfluorescein in vivo and in isolated rat hepatocyte couplets (IRHC), respectively. Localisation of Bsep and F-actin were assessed both in vivo and in IRHC by specific fluorescent staining. RESULTS: In vivo pharmacokinetic studies revealed that taurolithocholate (3 micro mol/100 g body weight) diminished by 58% canalicular excretion and increased by 96% plasma reflux of (14)C taurocholate. Analysis of confocal images showed that taurolithocholate induced internalisation of Bsep into a cytosolic vesicular compartment, without affecting F-actin cytoskeletal organisation. These effects were reproduced in IRHC exposed to taurolithocholate (2.5 micro M). Preadministration of dibutyryl-cAMP, which counteracts taurolithocholate induced impairment in bile salt secretory function in IRHC, restored Bsep localisation in this model. Furthermore, when preadministered in vivo, dibutyryl-cAMP accelerated recovery of both bile flow and bile salt output, and improved by 106% the cumulative output of (14)C taurocholate. CONCLUSIONS: Taurolithocholate impairs bile salt secretion at the canalicular level. Bsep internalisation may be a causal factor which can be prevented by dibutyryl-cAMP.

Inhibitory effect of short-term bile duct ligation on hepatic cytochrome P450 of bile acid-depleted rats.

In this study we analyzed the effect resulting from a short-term (1 h) bile duct obstruction in bile acid-depleted or taurocholate-replenished rats on liver cytochrome P450 enzyme system activity. Rats were depleted of endogenous bile acids and then subjected to a biliary obstruction for 1 h. Some of these depleted-obstructed rats were replenished previously to the obstruction with exogenous taurocholic acid (TC) and the others were treated with the solvent alone. To study the isolated effect of the bile acid, other rats were also previously depleted and then replenished with TC but they were obstructed briefly (20 min). CYP3A2-linked activity was evaluated in vivo with the aminopyrine breath test and in vitro by the measurement of nifedipine oxidase microsomal activity. The results suggested that bile flow suppression per se might inhibit this CYP-linked activity and that bile acid retention is not involved at least as a sole determinant.

Beneficial effects of silymarin on estrogen-induced cholestasis in the rat: a study in vivo and in isolated hepatocyte couplets.

The effect of silymarin (SIL) on 17alpha-ethynylestradiol (EE)-induced cholestasis was evaluated in rats. EE (5 mg/kg, subcutaneously, daily, for 5 days) decreased both the bile-salt-dependent and the bile-salt-independent fractions of the bile flow. The decrease in the former was associated to a reduction in the bile salt pool size (-58%), and this effect was completely prevented by SIL. This compound also counteracted the inhibitory effect induced by EE on HCO(3)(-) but not glutathione output, 2 major determinants of the bile-salt-independent bile flow. EE decreased the secretory rate maximum (SRM) of tauroursodeoxycholate, (-71%) and bromosulfophthalein (BSP; -60%), as well as the expression of the BSP canalicular carrier, mrp2; SIL failed to increase mrp2 expression, and had only a marginal beneficial effect on both tauroursodeoxycholate and BSP SRM values. However, the two-compartment model-based kinetic constant for BSP canalicular transfer was significantly improved by SIL (+262%). SIL decreased rather than increased CYP3A4, the cytochrome P450 isoenzyme involved in the oxidative metabolism of EE, and had no inhibitory effect on the UDP-glucuronosyltrasferase isoforms involved in the formation of its 17beta-glucuronidated, more cholestatic metabolite. Pretreatment of isolated rat hepatocyte couplets with silibinin, the major, active component of SIL, counteracted the estradiol 17beta-glucuronide-induced decrease in the percentage of couplets secreting apically the fluorescent bile acid analogue, cholyl-lysyl-fluorescein. These results show that SIL protects against EE-induced cholestasis by normalizing mainly the decrease in the bile salt pool size and HCO(3)(-) output, and probably by counteracting the cholestatic effect of its cholestatic, glucuronidated metabolite.

Effect of silymarin on biliary bile salt secretion in the rat.

The effect of the hepatoprotector silymarin on bile secretion, with particular regard to bile salt secretion, was studied in Wistar rats. Silymarin (25, 50, 100, and 150 mg/kg/day, i.p., for 5 days) induced a dose-dependent increase in bile flow and bile salt secretion, the maximal effect being reached at a dose of 100 mg/kg/day (+17 and +49%, for bile flow and bile salt output, respectively; P < 0.05). Assessment of bile salt composition in bile revealed that stimulation of the bile salt secretion was accounted for mainly by an increase in the biliary secretion of beta-muricholate and, to a lesser extent, of alpha-muricholate, chenodeoxycholate, ursodeoxycholate, and deoxycholate. The maximum secretory rate (T(m)) of bile salts, as assessed by infusing the non-hepatotoxic bile salt tauroursodeoxycholate i.v. at stepwise-increasing rates, was not influenced by silymarin. The flavonolignan also increased the endogenous bile salt pool size (+53%, P < 0.05) and biliary bile acid excretion after bile acid pool depletion (+54%, P < 0.05), a measure of de novo bile salt synthesis. These results suggest that silymarin increases the biliary excretion and the endogenous pool of bile salts by stimulating the synthesis, among others, of hepatoprotective bile salts, such as beta-muricholate and ursodeoxycholate.

Adaptive hepatic changes in mild stenosis of the common bile duct in the rat.

Adaptive hepatic changes were investigated in rats with mild stenosis of the common bile duct and in sham-operated controls. The studies were performed 24 h and 7-12 days postoperatively. A continuous intravenous infusion of taurocholic acid at stepwise-increasing rates was performed to explore the responses to bile acid effects. During the infusion, bile flow and the outputs of bile acids, phospholipids, cholesterol, alkaline phosphatase and gamma glutamyl transpeptidase were studied. At the end of the infusion, hepatic morphometric measurements were performed. In other experimental sets, biliary excretions of horseradish peroxidase, a marker of microtubule-dependent vesicular transport in the hepatocyte, and sulphobromophthalein, a well-known organic anion model, were studied. In other rats, bile acid pool size and composition were determined by depletion of bile. The results in rats with mild stenosis maintained for 24 h showed a greater susceptibility to the toxicity of taurocholic acid, as revealed by the abrupt decrement in bile flow at high rates of infusion, and increased outputs of phospholipids and canalicular enzymes. Conversely, rats with mild stenosis maintained for 7-12 days showed decreased bile acid maximum secretory rate and biliary outputs of phospholipids and canalicular enzymes, as well as hepatocyte hypertrophy. These findings may explain the limited hepatic and systemic repercussion of experimental mild stenosis of the common bile duct and help us to understand the early stages of constriction of the common bile duct in man.

Cl- currents activated via purinergic receptors in Xenopus follicles.

Ionic currents elicited via purinergic receptors located in the membrane of Xenopus follicles were studied using electrophysiological techniques. Follicles responded to ATP-activating inward currents with a fast time course (F(in)). In Ringer solution, reversal potential (Erev) of F(in) was -22 mV, which did not change with external substitutions of Na- or K+, whereas solutions containing 50 or 5% of normal Cl- concentration shifted Erev to about +4 and +60 mV, respectively, and decreased F(in) amplitude, indicating that F(in) was carried by Cl-.F(in) had an onset delay of approximately 400 ms, measured by application of a brief jet of ATP from a micropipette positioned near the follicle (50 microns). F(in) was inhibited by 50% in follicles pretreated with pertussis toxin. This suggests a G protein-mediated receptor channel pathway. F(in) was mimicked by 2-MeSATP and UTP, the potency order (half-maximal effective concentration) was 2-MeSATP (194 nM) > UTP (454 nM) > ATP (1,086 nM). All agonists generated Cl- currents and displayed cross-inhibition on the others. F(in) activation by acetylcholine also cross-inhibited F(in)-ATP responses, suggesting that all act on a common channel-activation pathway.

Does paracellular permeability play a role in cholephilic dye-induced cholestasis?

Changes in hepatic paracellular permeability were investigated during the development of cholephilic dye-induced cholestasis in rats. For this purpose, four dyes with different cholestatic potency (phenol red, sulfobromophthalein, bromcresol green and rose bengal) were infused at a high, potentially damaging dose (280 nmol/min per 100 g body wt., i.v.), and changes in paracellular permeability were continuously monitored by measuring the access into bile of the permeability probe -14C-sucrose. The cholestatic potency of the different dyes was: rose bengal > bromcresol green > sulfobromophthalein > phenol red. All dyes increased [14C]sucrose bile-to-plasma ratio, producing a displacement towards curves of higher permeability. The capability of the dyes to increase biliary permeability followed the same order as their respective cholestatic potencies. The possible implications of the present results for cholephilic dye-induced cholestasis are discussed.

Rat model of mild stenosis of the common bile duct.

Several techniques for developing incomplete obstruction of the common bile duct have been described but none of them properly represents a compression or constriction of the bile duct. In this study, a mild stenosis of the common bile duct was achieved in the rat by means of a double ligature including a cannula that could be easily slipped out of the ligatures. Sham-operated rats were used as controls. The studies, performed 7-10 days postoperatively, indicated that in ligated rats a duct constriction was produced, made evident by an increase of the biliary pressure, an upstream dilatation of the bile duct, an increase of the liver volume constituted by portal tracts, and ductular proliferation. Serum parameters were practically similar in ligated and control rats, except for a slight increase in serum bilirubin. Following intravenous injection of sodium taurocholate there were rapid increases of bile flow and bile salt output in both groups, but choleresis induced by sodium taurocholate was higher in ligated rats than in controls. The clearances of [14C]erythritol and [14C]sucrose suggested that ductular water contributing to bile flow and changes in biliary permeability were not involved in ligated rats. The limited repercussion of humoral effects and hepatic behaviour seen in ligated rats despite the morphological alterations induced make the mild stenosis of the bile duct a good model for the study of early stages of compression or constriction of the biliary tract.

Enhancement of intestinal bilirubin UDP-glucuronosyltransferase activity by modification of microsomal lipid composition.

Microsomal membranes from rat small intestine exhibit a higher cholesterol/phospholipid ratio and a lower phosphatidyl-choline/sphingomyelin ratio than those of the liver, which could negatively influence membrane-bound enzymes like bilirubin UDP-glucuronosyltransferase. To study the effect of in vitro modifications in the lipid composition of intestinal microsomes on bilirubin glucuronidating activity, two strategies were employed. On one hand, microsomal lipids were modified in order to mimic those of the liver tissue; on the other hand, cholesterol content of microsomal membranes was increased or decreased with respect to the normal value. Lipid changes were carried out by both an enzyme-mediated and a detergent-mediated procedure. Irrespective of the methodology employed, when a depletion in the cholesterol content was produced, enzyme activity increased about 40%, and when lipid composition approached that of the liver tissue, which not only decreased cholesterol but also modified phospholipid classes, enzyme activity increased about 80%. Both lipid modifications produced a 'fluidification' of microsomal membranes measured by fluorescence anisotropy of 1,6-diphenylhexatriene, being the effect of the approach to the liver higher than that of the decrease of cholesterol. In turn, the enrichment in cholesterol of microsomal membranes led to a decrease of enzyme activity of about 20% and to a 'rigidization' of the membranes. The present findings suggest that in rat intestine, bilirubin glucuronidation is strongly influenced by microsomal lipids. In particular, there seems to be an inverse association between enzyme activity and the cholesterol content of membrane.

Effect of cholephilic dyes on hepatic tight junctional permeability in the rat.

Changes in biliary permeability during cholephilic dye-induced choleresis, as assessed by measuring the movement into bile of two permeability probes, [14C]sucrose and horseradish peroxidase, were analyzed following an i.v. infusion (60 nmol/min per 100 g body wt) of the model cholephilic organic anion sulfobromophthalein in rats. Dye infusion led to a progressive increase of the [14C]sucrose bile-to-plasma ratio, which reached a maximum value after 100 min of dye infusion (+97%). Paracellular entry of horseradish peroxidase, as evaluated by the early peak of its biliary appearance curve, was also selectively increased (+69%), without changes in the later (transcytotic) access of the protein. Additional dose-response studies of biliary permeability to [14C]sucrose, using sulfobromophthalein and rose bengal, showed that this effect was dose-dependent and rapidly reversed by interruption of dye administration. The influence of hydrophobic/hydrophilic balance on this effect was also studied by infusing four dyes covering a broad range of hydrophobicity (phenol red, bromocresol green, sulfobromophthalein, and rose bengal), so as to attain a similar value of dye hepatic content at the end of the experiment (approximately 150 nmol/g liver wt). Under these conditions, a strong positive correlation was found between the increase in biliary permeability to [14C]sucrose and dye hydrophobicity. These results suggest that cholephilic dyes increase tight junctional permeability in a reversible and dose-dependent manner, and that this effect depends on the hydrophobic/hydrophilic balance of the dye.

Diastematomielia / Diastematomyelia

Se presenta el caso de un recién nacido que evidencia una formación quística en la línea media de la región lumbar. Se analiza la utilidad y complementariedad de los diversos métodos de diagnóstico por imágenes (Rx simple, ecografía lumbar y transfontanelar, TC, RM de columna lumbar), para mostrar como malformación subyacente una diastematomielia

Diastematomielia / Diastematomyelia

Se presenta el caso de un recién nacido que evidencia una formación quística en la línea media de la región lumbar. Se analiza la utilidad y complementariedad de los diversos métodos de diagnóstico por imágenes (Rx simple, ecografía lumbar y transfontanelar, TC, RM de columna lumbar), para mostrar como malformación subyacente una diastematomielia (AU)

Effect of oral administration of ursodeoxycholic acid on rat hepatic and intestinal UDP-glucuronosyltransferase.

The effect of oral administration of the bile acid ursodeoxycholic acid on rat hepatic and intestinal microsomal UDP-glucuronosyltransferase was studied. The bile acid was administered during 8 days at a daily dose of 500 mg/kg body weight. Enzyme activity was assessed in native and activated microsomes, using bilirubin and p-nitrophenol as substrates. Activation was achieved either by including UDP-N-acetylglucosamine in the incubation mixture or by preincubating native microsomes with an optimal concentration of Lubrol Px. Irrespective of activation status of the microsomes, ursodeoxycholic acid treatment increased enzyme activities toward both substrates in intestine, but not in liver. The analysis of the degree of activation by Lubrol Px revealed that, at least for bilirubin, ursodeoxycholic acid decreased the latency of the intestinal enzyme. The analysis of the lipid composition of microsomes showed several changes in response to ursodeoxycholic acid in intestine but not in liver. Thus, a decrease in cholesterol/phospholipid ratio and an increase in the unsaturation index of total-lipid fatty acids, which correlated well with a membrane "fluidification," were observed. These modifications appear to be related to the lower latency of bilirubin UDP-glucuronosyltransferase in intestine from treated rats and could be responsible, at least in part, for the improvement of enzyme activity in this group. Whatever the mechanism involved, the increment of intestinal UDP-glucuronosyltransferase activities toward both substrates may be relevant as a complement to the hepatic enzymes in those liver diseases in which ursodeoxycholic acid is used as a therapeutic agent.

Hepatic transport of organic anions in taurolithocholate-induced cholestasis in rats.

The hepatic transport of organic anions was evaluated in taurolithocholate-induced cholestasis in rats. Taurolithocholate (3 mumol per 100 g body wt., i.v.) diminished bile flow by 61%, whereas biliary excretion of bile salts was normalized after 80 min. Tm studies of sulfobromophthalein revealed reduced biliary excretion (-58%) and increased hepatic content of the dye (+75%). Conjugation pattern in bile showed that free sulfobromophthalein was increased by 57%, suggesting that hepatic conjugation was also impaired. This finding, however, could not fully explain the reduced sulfobromophthalein excretion since Tm of its non-metabolizable analog phenol-3,6-dibromophthalein was also decreased (-41%). Compartmental analysis of plasma decay of both dyes revealed that, whereas hepatic uptake was unaltered, canalicular excretion was reduced and reflux from the liver into plasma was increased by the cholestatic agent. Studies on transport of phenol-3,6-dibromophthalein by isolated hepatocytes showed that while uptake was unaffected, the treatment reduced (-36%) the release from hepatocytes preloaded with the dye. Neither glutathione S-transferase activity nor binding of sulfobromophthalein to cytosolic proteins was altered when evaluated in vitro, suggesting that reduced conjugation and enhanced sinusoidal reflux were not due to an irreversible effect of taurolithocholate on this enzyme. In conclusion, taurolithocholate impairs the hepatic transport of organic anions by impairing canalicular excretion and intrahepatic conjugation, as well as by increasing transfer from the liver into the plasma.