Validation and application of a liquid-chromatographic/enzymatic assay for individual bile acids in the serum of rats

A liquid-chromatographic technique with a post-column enzymatic reaction and fluorescence detection was validated for analysis of individual bile acids in the serum of rats. Extraction recoveries averaged 91.1% (SD 6.9%) for all bile acids. The assay was sensitive (minimum detection of 16.8 pmol per 100-microL injection), linear (r greater than 0.999 for concentrations ranging between 45 and 112,500 pmol per 100-microL injection), and reproducible (mean CVs for three different concentrations of standards and a serum pool ranged from 4.4% to 12.2%). In rats treated for three days with either neomycin, carbon tetrachloride, alpha-naphthylisothiocyanate, or total bile-duct ligation (five animals per group), total concentrations of bile acids were significantly increased (P less than 0.004). Concentrations of 16 of 17 individual bile acids differed significantly between groups (P less than 0.04). Examination of the relative concentrations (percent of total) of individual bile acids by canonical discriminant analysis placed each animal into the appropriate treatment or control group. Use of this technique in toxicological studies can help detect and identify specific types of disruptions in the enterohepatic circulation of bile acids.     

Rapid active transport of immunoglobulin A from blood to bile

Immunoglobulins were isolated from the serum or ascitic fluid of Lou/Wsl rats bearing plasmacytomas and labeled with 125I. When labeled IgA was injected i.v. it disappeared from the blood serum much more rapidly than IgG2 so that after 3 h less than 10% remained. This rapid disappearance of the injected IgA was not seen in rats with ligated bile ducts. In rats with cannulated bile ducts, the labeled IgA appeared rapidly in the bile so that 25% of the injected dose was recovered in 3 h; at the peak of this biliary excretion the specific radioactivity of the bile (cpm/milligram protein) was about 200 times greater than that of the blood serum. Thus much of the IgA which finds its way into the blood is rapidly and actively transported across the liver so that it enters the gut lumen via the biliary tract.     

Periportal localization of lorazepam glucuronidation in the isolated perfused rat liver

The relative effects of pretreatment with allyl alcohol and carbon tetrachloride on oxidative and glucuronide metabolism of lorazepam have been compared in the isolated perfused rat liver. Livers from rats pretreated for 24 hr with allyl alcohol (1.8 ml/kg, 1:50 solution, to induce pericentral hepatic necrosis), carbon tetrachloride (0.8 mg/kg in corn oil, to induce perivenular hepatic necrosis), or vehicle were perfused with 20% rat blood, 80% Krebs bicarbonate buffer at 20 ml/min. After 300 micrograms of lorazepam had been added to the reservoir, perfusate concentrations of lorazepam were measured in the perfusate at timed intervals. After 180 min, lorazepam and lorazepam glucuronide were measured in perfusate, bile, and liver homogenate. Allyl alcohol and carbon tetrachloride lowered lorazepam clearance by 47% and 77%, respectively. Recovery of lorazepam glucuronide after 180 min was lowered by 35% by treatment with allyl alcohol and increased 73% by treatment with carbon tetrachloride. Glucuronide recovery permitted estimation of fractional glucuronide vs. nonglucuronide clearance. In control rats, glucuronide clearance accounted for 25% of total clearance. Allyl alcohol caused a 64% reduction in glucuronide clearance but only a 39% reduction in nonglucuronide clearance. In contrast, carbon tetrachloride caused a 60% reduction in glucuronide clearance but an 83% reduction in nonglucuronide clearance. The differences in ratios of the changes in glucuronide and nonglucuronide clearance provide further circumstantial evidence that is consistent with the hypothesis of predominant periportal localization of glucuronidation and pericentral localization of oxidative metabolism of lorazepam.     

Cholestatic effect of carmustine in rats

A single i.p. dose of 20 mg/kg of carmustine [1,3-bis-(2-chloroethyl)-1-nitrosourea; BCNU] caused intrahepatic cholestasis in rats within 48 hr of administration. Cholestasis was characterized by a selective reduction of the bile salt independent fraction of bile flow. Increased plasma K+ and decreased plasma Na+ concentrations, consistent with this effect, were observed. Because bile: plasma osmolality and biliary bile salt concentrations were elevated, increased permeability to bile salts and other osmotically active solutes between bile and plasma is unlikely. Bile salt excretion was normal despite the reduced bile flow because biliary bile salt concentration was increased. In contrast, the treated rats were unable to concentrate bromosulfophthalein in bile before, during and after the onset of cholestasis. Because no reduction in hepatic perfusion was observed in vivo in BCNU-treated rats, reduced xenobiotic organic anion excretion may be a selective effect of the drug. The cholestatic effects of BCNU appear to be different from either alpha-naphthylisothiocyanate or estrogenic steroids.     

Disruption of mitochondrial calcium homeostasis after chronic alpha-naphthylisothiocyanate administration: relevance for cholestasis.

BACKGROUND: Hepatocyte dysfunction caused by impaired mitochondrial function has been pointed out as a probable leading cause of cholestatic liver injury. The aim of this study was to evaluate liver mitochondrial bioenergetics that followed repeated in vivo administration of alpha-naphthylisothiocyanate, a known cholestatic agent. METHODS: Serum markers of liver injury and endogenous adenine nucleotides were measured in alpha-naphthylisothiocyanate-treated rats (intraperitoneally, 100 mg/Kg/wk x 6 wk). Changes in membrane potential, mitochondrial respiration, as well as alterations in mitochondrial calcium homeostasis were monitored. RESULTS: In rats injected with alpha-naphthylisothiocyanate, liver injury with cholestasis developed within 48 hours, as indicated by both serum enzyme activities and total bilirubin concentration. However, 1 week after the last injection, serum enzyme activity returned to control levels. In addition, after chronic alpha-naphthylisothiocyanate administration, no alterations in mitochondrial respiratory function and membrane potential were observed. Associated with these parameters, mitochondria from treated animals exhibited increased susceptibility to disruption of mitochondrial calcium homeostasis by calcium phosphate and by bile acids, which was probably caused by induction of permeability transition pore. CONCLUSIONS: Our data suggest that chronic cholestasis in rats leads to impaired mitochondrial function due to the disruption of mitochondrial calcium homeostasis. The initiating event is the induction of a cyclosporine A-sensitive release of calcium. This event may be an important determinant of the progression of cholestatic liver injury and associated liver cirrhosis. In addition, in the present study we observed that impairment of mitochondrial function is potentiated by chenodeoxycholate, a bile acid that is known to be toxic. Ursodeoxycholate (the beta- epimer of chenodeoxycholate) is approved for the treatment of chronic cholestatic liver disease. Interestingly, we show that the susceptibility to the cyclosporine A-sensitive release of calcium was increased by the combination of both bile acids. These results indicate that the reported improvement of biochemical parameters in cholestatic patients treated with ursodeoxycholate would not prevent the associated mitochondrial dysfunction. This may explain the progression of the histological stage and the maintenance of symptoms during cholestasis.     

Laboratory tests to exclude IgA deficiency in the investigation of suspected anti-IgA transfusion reactions

Four methods were compared as to their suitability for excluding IgA deficiency in the investigation of suspected anti-IgA transfusion reactions. The methods were radial immunodiffusion, passive hemagglutination inhibition, sandwich enzyme-linked immunosorbent assay, and membrane enzyme immunoassay. Parallel testing was performed on sera from 40 patients or blood donors previously found to have anti- IgA and low or undetectable levels of IgA. All test methods identified the 40 sera as having abnormally low IgA levels. The membrane enzyme immunoassay required 10 minutes or less for testing, as compared to 3 hours for passive hemagglutination inhibition, 4 hours for sandwich enzyme-linked immunosorbent assay, and 48 hours for radial immunodiffusion. The membrane enzyme immunoassay offers the potential for a rapid, instrument-free screen of IgA levels and therefore may be useful in identifying those patients with suspected anti-IgA anaphylactic transfusion reactions who are not IgA deficient and do not require IgA-deficient blood components for additional transfusions.     

Plasma alkaline phosphodiesterase I in intrahepatic cholestasis induced by alpha-naphthylisothiocyanate in rats

1. Administration of alpha-naphthylisothiocyanate (ANIT) to rats produced dose-dependent increases in plasma bile acid and bilirubin concentrations. Similar increases in plasma bile acid and bilirubin concentrations were evident in bile duct ligated rats, indicating that the severity of cholestasis is almost identical in both models. 2. Plasma alkaline phosphodiesterase I was increased by only 50-80% while alkaline phosphatase was increased more than threefold after ANIT administration. This is in contrast to an earlier study [S. R. Simpson, K. Rahman & D. Billington (1984) Clinical Science 67, 647-652] where, after bile duct ligation, serum alkaline phosphodiesterase I was elevated sixfold before any increase in alkaline phosphatase activity became apparent. Thus, plasma alkaline phosphodiesterase I does not offer as sensitive a marker of intrahepatic cholestasis (induced by ANIT) as it does of extrahepatic cholestasis (induced by bile duct ligation). 3. Hepatic alkaline phosphodiesterase I was unaffected by ANIT pretreatment while hepatic alkaline phosphatase was increased up to seven times. It is suggested that raised plasma alkaline phosphodiesterase I is due to regurgitation of the biliary enzyme rather than overspill of the enzyme from liver into blood. 4. Gel filtration showed that 24 h and 96 h after ANIT administration, rat serum contained a high molecular weight form of alkaline phosphodiesterase I, suggesting a different isoenzyme profile.     

Reduced hepatic clearance of propranolol induced by chronic carbon tetrachloride treatment in rats

Effect of liver injury induced by chronic treatment with carbon tetrachloride for 1 to 4 months on hepatic clearance of propranolol was investigated in male Wistar rats. Plasma propranolol level after i.v. and p.o. dosing (1.0 mg/kg) was always higher in the rats which were treated for 2 and 4 months than in control (sham-injected) rats. The chronic treatment reduced hepatic clearance of propranolol significantly, yielding only approximately 30 to 50% of the control clearance value. Distribution volume of this drug was also significantly reduced by the chronic treatment but seemed to be less sensitive to the treatment than the hepatic clearance. Accordingly, the elimination rate constant was decreased slightly in the rats treated longer than 2 months. The chronic treatment for 2 and 4 months also reduced intrinsic hepatic clearance substantially. The hepatic clearance estimated for both these control and chronically treated rats was significantly dependent on the liver blood flow. Furthermore, propranolol was eliminated much more slowly in the injured liver of the rat which was treated for 2 or 4 months than in the control liver when perfused in in vitro technique. It is, therefore, suggested that the metabolic dysfunction induced by chronic treatment with carbon tetrachloride may be directly related to substantial changes in anatomical arrangement of the hepatic circulation (portasystemic shunting), which may be due to a fibrosis of the tissue.     

激动素（Kinetin）对四氯化碳肝纤维化大鼠疗效的研究

目的观察Kinetin对四氯化碳大鼠肝纤维化作用的影响。方法用四氯化碳、猪油拌玉米粉、酒精诱导大鼠肝纤维化模型。6周后对肝纤维化大鼠给予3种不同剂量的激动素进行治疗,并与模型对照组和干扰素α-2b治疗组比较,观察各组肝脏炎症活动度、肝纤维化计分和胶原纤维体视学的变化。结果各Kinetin治疗组与同期模型对照组肝脏炎症活动度、纤维化计分和胶原纤维体视学比较均明显减少(P<0.05),与同期干扰素α-2b治疗组比较无明显差异(P>0.05)。各Kinetin组随剂量增大存在明显显效关系。结论激动素能抑制四氯化碳肝纤维化大鼠肝内胶原纤维的形成,其抑制性作用与其剂量有关。     

Selective transport of polymeric immunoglobulin A in bile. Quantitative relationships of monomeric and polymeric immunoglobulin A, immunoglobulin M, and other proteins in serum, bile, and saliva.

In 17 adults, serum, hepatic bile, and saliva samples were analyzed for their sedimentation profile of IgA and secretory component (SC), and for their concentrations of albumin, orosomucoid, transferrin, IgG, IgA, alpha 2-macroglobulin (alpha 2M), IgM, and SC. Polymeric IgA(p-IgA) averaged 13% (50-700 micrograms/ml) of total IgA in serum, 70% (43-88%) in bile, and 93% (74-98%) in saliva. Most of the p-IgA in bile sedimented with SC, which also occurred free (8-44%), and with IgM. In bile, albumin (155-1,485 micrograms/ml) was the predominant protein, followed by IgG (32-480 micrograms/ml), and total IgA (37-209 micrograms/ml). In saliva, p-IgA (72-902 micrograms/ml) predominated, followed by albumin (16-385 micrograms/ml) and IgG (9-178 micrograms/ml). Secretion-to-serum albumin-relative concentration ratios (S/S-ARCR = 1 for albumin) in bile averaged 22 for p-IgA, 1.91 for IgM, 1.28 for monomeric IgA (m-IgA), 0.70 for IgG, and 0.57 for alpha 2M, indicating for p-IgA, IgM, and to a lesser extent for m-IgA, a selective excretion into bile. In saliva, a 16-fold greater selective excretion of p-IgA (mean S/S-ARCR = 354) was found. Labeled m- and p-IgA were injected intravenously into five patients. Specific activities indicated that for p-IgA 50% was serum derived in bile, as compared with 2% in saliva, and to 85% for m-IgA in bile. In the patient with the highest excretion of 125I-p-IgA in bile, only 2.8% of the injected dose was recovered in bile within 24 h after injection. Compared with rats and rabbits, the serum-to-bile transport of p-IgA in humans is much smaller.     

Effect of CO2-induced hyperventilation on carbon tetrachloride (CCl4) levels following acute CCl4 poisoning

To study under standardized experimental conditions the effect of a CO2-induced hyperventilation therapy on carbon tetrachloride (CCl4) levels following acute CCl4 poisoning, rats received 2.5 ml CCl4/kg BW by gastric intubation and were subsequently either treated by CO2-induced hyperventilation or kept in an atmosphere containing air. Peak levels of CCl4 were observed in the fat, liver and blood 3-6 h after the intoxication and were found to be considerably lower in animals treated by CO2-induced hyperventilation compared to their respective controls. These data therefore strongly support the efficacy of the CO2-induced hyperventilation therapy for CCl4 intoxication.     

Hyperammonemia induced in rats by inhalation anesthesia with ether

Transient hyperammonemia was observed in rats after inhalation anesthesia with ether. The elevation of blood ammonia concentration induced by ether anesthesia was greatest in carbon tetrachloride injured and indomethacin-treated rats, but not observed in phenobarbital-treated rats. The results suggest interaction between ether metabolism and ammonia metabolism in the liver.     

IgA肾病大鼠模型的建立

目的通过改良IgA肾病(IgAN)大鼠模型的制备方法,建立更安全、可靠、成功率更高的IgAN模型。方法牛血清白蛋白(BSA)400 mg/kg隔天灌胃8周;每周1次皮下注射四氯化碳(CCl4)0.1 ml+蓖麻油0.3 ml,共9周;第6周尾静脉注射0.05 mg脂多糖(LPS)。在建模过程观察血尿、蛋白尿、血生化、肾组织病理I、gA沉积情况。结果 (1)模型组在第6周末出现血尿、蛋白尿,渐增多(均P<0.01);(2)模型组大鼠肾组织在第8周末后出现系膜增生,在第4周末起见足突融合;(3)模型组大鼠肾组织有IgA沉积。结论改良方法建立的IgAN大鼠模型更安全、可靠,其临床指标、病理改变均接近人类IgAN。     

骨髓间充质干细胞在IgA肾病大鼠肾脏中的定位与分布

背景：由于骨髓间充质干细胞缺乏特异性表面抗原,常根据其贴壁生长、成骨成脂分化等生物学特点来鉴定。目的：观察骨髓间充质干细胞在IgA肾病大鼠肾脏中的定位与分布情况。方法：以牛血清白蛋白＋葡萄球菌肠毒素B＋皮下注射四氯化碳的改良法建立SD大鼠IgA肾病模型。造模成功分别经尾静脉移植大鼠骨髓间充质干细胞或生理盐水,并设立不造模的正常对照组。移植后1,4周观察各组大鼠的尿蛋白、肾功能、肾脏病理变化、IgA荧光沉积变化,并通过免疫组织化学观察BrdU标记的骨髓间充质干细胞在肾组织中的分布情况。结果与结论：移植后1周,骨髓间充质干细胞组尿蛋白、血肌酐明显低于生理盐水组;移植后4周,骨髓间充质干细胞组肾脏病理变化、IgA荧光沉积与生理盐水组比较差异有显著性意义。提示骨髓间充质干细胞输注可促进大鼠IgA肾病的修复,并可定位于肾小球系膜区及少数肾小管间质区,但随时间延长,BrdU标记的髓间充质干细胞在肾组织中分布却逐渐减少。     

Inaccurate measurement of a polymeric IgA myeloma protein by nephelometric and fluorometric instrumentation

The concentration of IgA in a serum was 5.99 g/L as assayed nephelometrically with reagent from one company, but varied between 5 and 3 g/L (for sixfold and 36-fold dilutions, respectively) without giving a definitive answer when assayed with reagent from another source. Immunofixation electrophoresis indicated an IgA lambda monoclonal protein of 45 g/L. Radial immunodiffusion showed two components, having a total concentration of 41 g/L. By fluorometry the IgA was 3.1 g/L. Increasing the dilution caused the (dilution-corrected) lower values to increase. Although the most frequent cause of such discrepant findings is an IgA2 myeloma, which occurs in about one of every 100 myeloma cases, Ouchterlony double diffusion indicated the major component to be IgA1. A polymer, Mr 670,000, was identified by column chromatography. Contrary to the usual behavior of polymers assayed with radial immunodiffusion, which underestimates their concentration, this polymer reached equivalency in agreement with its true concentration as assayed by the Mancini-Heremans technique.     

人类脐血间充质干细胞在急性肝坏死大鼠体内分化潜能的实验研究

目的探索人类脐血间充质干细胞在急性肝坏死大鼠体内肝样细胞自主分化的潜能。方法体外分离培养人类脐血间充质干细胞。CC l4橄榄油溶液腹腔注射SD大鼠建立急性肝坏死大鼠模型。造模24 h后肝脏局部注射移植人类脐血间充质干细胞给急性肝坏死大鼠模型,造模后1周、2周和4周分别处死6只模型鼠,取肝脏切片做免疫组织化学检测人类特异性ALB、AFP、HepPar的表达,实时荧光RT-PCR检测人类特异性ALB、AFP、CK19、CK18的表达,测序扩增产物。结果体外分离培养的脐血来源细胞符合人类脐血间充质干细胞的生物学特性。处死移植模型鼠,肝脏免疫组织化学检测显示:人类特异性ALB、AFP、HepPar在接受移植的模型鼠体内呈阳性表达;实时荧光RT-PCR检测显示:人类特异性ALB、AFP、CK19、CK18在接受移植的模型鼠体内呈阳性表达,扩增产物序列与GENEBANK对应序列一致。结论无外部诱导干预,人类脐血间充质干细胞在急性肝坏死大鼠体内已具有肝样细胞自主分化潜能。     

Comparison of immunoglobulin determinations in pathological sera by radial immunodiffusion and laser nephelometry.

Immunoglobulins G, A, and M were measured by radial immunodiffusion and by laser nephelometry in sera from 33 patients and in a preparation of purified colostral IgA. In general the results agreed for the two methods, with some exceptions attributed to the physicochemical characteristics of the immunoglobulins assayed: low-molecular-weight (monomeric) IgM gives falsely high values and IgA proteins (consisting predominantly of polymeric molecules) give falsely low values when assayed by radial immunodiffusion. Results from laser nephelometry apparently are not affected by the molecular-size characteristics of the proteins assayed.     

Secretory component as the receptor for polymeric IgA on rat hepatocytes

Rat hepatocytes in short-term monolayer cultures bound radiolabeled polymeric rat IgA but not IgG. The binding of 125I-IgA was inhibited equally well by unlabeled polymeric IgA and by antiserum to rat secretory component (SC). The antibody to SC, after specific purification and radiolabeling, was bound to hepatocytes as effectively as the IgA. These results indicate that SC acts as the receptor for polymeric IgA on rat hepatocytes as it does on human gut epithelia, and that the transport of IgA from blood to bile in rats across the liver is analogous to that of IgA across human enterocytes.     

AN INTRACELLULAR DEFECT IN PROTEIN SYNTHESIS INDUCED BY CARBON TETRACHLORIDE

The morphological and certain metabolic effects of carbon tetrachloride intoxication were studied in the rat with emphasis on liver alterations. Morphological changes were investigated by histological and electron microscopical means. Functional changes were investigated using histochemical and amino acid incorporation, techniques. The liver constituents were examined chemically. Plasma volume alterations were measured using dye and homologous protein dilution techniques. The histological appearance of the liver of treated animals included cellular swelling, dispersal of the cytoplasmic basophilia, and necrosis. Electron micrographs showed an early (3 hours following carbon tetrachloride administration) and widespread dislocation of the ribonucleoprotein particles from the membranes of the rough endoplasmic reticulum, but no apparent alteration in the mitochondrial structure. Histochemical examination of two mitochondrial enzyme systems, α-ketoglutarate dehydrogenase and succinic dehydrogenase, revealed no alterations in activities until a later time (6 to 12 hours following carbon tetrachloride administration). ATPase showed a gross quantitative decrease in activity at 6 and 12 hours, but not earlier. There was a decreased amino acid incorporation into two liver-produced proteins, viz., albumin and fibrinogen. This decrease is not explicable on the basis of the inability of the liver to take up the amino acid, an altered dilution volume into which the amino acid or formed protein is placed, or an impaired capacity of the liver to excrete protein once formed. It is concluded that the decreased amino acid incorporation rate reflects depressed synthesis of protein by the liver. Other pathological changes in the liver, including necrosis, fatty change, and mitochondrial alterations may be dependent upon severe impairment of protein synthesis.