Transferrin is not involved in the entry of 67Ga into hepatocytes from regenerating liver of partially hepatectomized rats.

Ever since the first observation of 67Ga accumulation in tumors and inflammatory lesions, 67Ga has been used to detect various tumors and inflammations. The aims of this study were to clarify whether or not transferrin is involved in the uptake of 67Ga by the regenerating liver after partial hepatectomy. The uptake of 67Ga by the liver of rats reached a maximum 2 d after partial hepatectomy. In order to inhibit the binding of 67Ga to transferrin in the blood, FeCl3 was administered 5 min before the injection of 67Ga. The administration of FeCl3 decreased the uptake of 67Ga by the liver of the partially hepatectomized rats, suggesting that transferrin is involved in the uptake by the liver. However, 67Ga was taken up only slightly by hepatocytes obtained from the liver of these rats. We conclude that transferrin is involved in the uptake of 67Ga by the liver tissue of partially hepatectomized rats but is not involved in its entry into the hepatocytes. Only a slight amount of gallium-67 enters the hepatocytes, and may accumulate primarily in the extracellular matrix of the liver tissue of these rats.     

The entering of indium-111 and iron-59 into the hepatocytes from partially hepatectomized rats differ from that of gallium-67

We recently suggested that the transferrin (Tf)-gallium-67 (67Ga) complex dissociated on the surface of the hepatocytes after partial hepatectomy and free 67Ga bound to heparan sulfate in the extracellular matrix. In the present study, we investigated whether the entering of indium-111 (111In) and iron-59 (59Fe) with high affinity to transferrin differed from the entering of 67Ga by the hepatocytes after partial hepatectomy. 111In was almost taken by the plasma and little taken by the red blood cell. On the other hand, the uptake of 59Fe by the red blood cell was higher than plasma. The uptake of 59Fe by the bone marrow was significantly higher than that of 111In. The uptake of 111In and 59Fe by the liver tissue was reached a maximum 2 d after partial hepatectomy but the uptake ratio of 111In was lower than that of 59Fe. We suspected that the uptake of 59Fe by the liver tissue was the highest because of the high binding affinity of Tf-59Fe to Tf-receptor. The entering of 111In and 59Fe into the hepatocytes was also reached a maximum 2 d after partial hepatectomy but the ratio of 59Fe was slightly lower than that of 111In. These results suggested that the binding affinity to Tf could have played a crucial role in the differences of the entering of 111In, 59Fe and 67Ga into the hepatocytes of partially hepatectomized rats.     

The effect of phenobarbital on protein metabolism of liver. results with isolated hepatocytes

A technique has been devised which makes use of an amino acid alternatively labeled with either [¹⁴C]or [³H], and permits the simultaneous evaluation of synthesis, catabolism and secretion by the same sample of isolated rat liver cells during the same time-period of incubation. This technique has been used to study protein metabolism of liver cells isolated from rats treated with 4 doses of phenobarbital (8 mg/100 g body weight) given in the 4 days before killing the animals. Total protein synthesis and secretion do not change in phenobarbital-treated rats; albumin represents 40% of secreted protein in both normal and treated rats. On the contrary, the parameters which indicate protein degradation are lower in phenobarbital-treated than in normal rats, showing that protein catabolism is appreciably reduced in the liver cells obtained from rats treated with phenobarbital     

The effect of blood decrease on (67)Ga uptake by the liver in partially hepatectomized rats

As (67)Ga is injected into the blood, (67)Ga is immediately bound to transferrin (Tf) and transported to various tissues and the Tf-(67)Ga complex binds to Tf receptor on various tissues. In partial hepatectomy (PH) a part of blood in circulation is lost together with removed liver tissues, consequently the amounts of blood cells and Tf in circulation decrease. In order to investigate the effect of those decreases on (67)Ga uptake by the liver, we compared the uptake in partially hepatectomized rats with that in venesectioned rats in which only a part of blood in circulation decreased. A two-thirds PH was performed. Two milliliters of blood was venesectioned. Each treated rat was intraveneously injected with (67)Ga. The changes of erythrocyte and reticulocyte contents after PH did not differ from those after venesection (VS) at all. But (67)Ga uptake by reticulocytes significantly increased after VS but did not after PH. On the other hand, (67)Ga uptake by the liver significantly increased after PH but did not after VS. These differences must be related to the different expression of Tf receptors on the liver after PH and VS.     

Penicillin spikes in rats. Limitations of a simple model for the study of anticonvulsants

Direct GABA agonists that suppress spikes induced by penicillin in cats failed to do so in rats. Phenytoin and large doses of THIP increased the rate of spiking activity of the penicillin focus. Only progabide caused marked, initial, short-lasting suppression and a modest reduction of frequency of spikes for 1 hr. Homotaurine (3APS) reduced the amplitude and changed the morphology of the contralateral "mirror" spike. Antagonism of penicillin-induced spikes in rats is considered to be an unsuitable parameter for the screening of anticonvulsant agents.     

青蒿琥酯影响大鼠异位内膜血管生成的实验研究

目的:探讨青蒿琥酯对大鼠子宫内膜异位病灶的抗血管生成作用和机制.方法:建立Wistar大鼠子宫内膜异位症动物模型,6周后将建模成功的大鼠随机分为空白对照、青蒿琥酯10mg/kg·d、青蒿琥酯50mg/kg·d、青蒿琥酯100mg/kg·d,采用灌胃法连续给药15d,观察各组异位子宫内膜体积,免疫组化法测定血管内皮生长因子(VEGF)的表达,并通过CD34标记异位子宫内膜血管,测定其微血管密度(MVD).结果:(1)各给药组大鼠第3次剖腹种植物体积缩小,与第2次剖腹时相比,差异有显著性意义(P＜0.05),与对照组第3次剖腹时相比,差异亦有显著性意义(P＜0.05).(2)青蒿琥酯治疗后各组的大鼠异位组织中VEGF表达和MVD数量与同时间的空白组比较差异均有显著性(P<0.05).(3)随着青蒿琥酯剂量的增加,各组种植物体积、VEGF表达和MVD数量与同时间的空白组相比明显减少.(4) 青蒿琥酯各治疗组异位内膜MVD数量与VEGF表达呈直线正相关关系(P＜0.05).(5)空白对照组异位内膜MVD数量与VEGF表达无相关关系(P＞0.05).结论:青蒿琥酯能明显缩小子宫内膜异位症大鼠模型的种植物体积、抑制异位子宫内膜VEGF蛋白表达及减少MVD数目,证实它可能是通过抑制VEGF表达实现其对异位病灶的血管生成抑制作用的,有望成为EMs抗血管生成治疗新药.     

Choline administration: Lack of effect on plasma catecholamines in rats

Choline chloride (35 or 70 mg/kg, IP) or saline was administered daily for 3 consecutive days to adult male Sprague-Dawley rats. Before and 30, 60 and 120 minutes after the third injection of choline chloride or saline, blood samples were collected from a chronic tail artery catheter and later analyzed for levels of norepinephrine (NE) and epinephrine (EPI). Plasma levels of both catecholamines did not differ between choline- and saline-injected rats at either of the four sampling points. When insulin (10 IU/kg, SC) was administered to stimulated the sympathetic-adrenal medullary system reflexy, plasma levels of NE and EPI increased significantly above basal values but were similar for choline- and saline-injected rats. These findings do not support a role for choline availability in the regulation of catecholamine secretion from the adrenal medulla.     

Effect of chlorpropamide and phenformin on rat liver: the effect on plasma membrane-bound enzymes and cyclic AMP content of hepatocytes in vitro.

Chlorpropamide and phenformin inhibited (Na+ - K+)-ATPase and stimulated a high affinity cyclic AMP-phosphodiesterase of isolated liver plasma membrane when tested in vitro. In addition, the two drugs decreased the intracellular cyclic AMP content of isolated hepatocytes without being effective on plasma membrane-bound adenylate cyclase. The results suggest that the plasma membrane plays an important role in the mechanism of action of the two hypoglycemic drugs, but do not exclude the presence of intracellular targets.     

Adrenal origin of plasma catecholamines after decapitation: a study in normal and diabetic rats.

The concentrations of catecholamines and the activities of dopamine-beta-hydroxylase were measured in blood obtained from decapitated diabetic and aged-matched control rats. The activity of dopamine-beta-hydroxylase in blood from diabetic rats was much greater (5 fold) than that seen for control rats. For both diabetic and control rats, decapitation was accompanied by an increase in levels of adrenaline and noradrenaline with no change in the activity of plasma dopamine-beta-hydroxylase. The results are consistent with a predominantly adrenal origin of catecholamines and extra-adrenal origin of dopamine-beta-hydroxylase. The high activity of dopamine-beta-hydroxylase in diabetes indicates either an increased activity of the sympathetic nervous system or changes in dopamine-beta-hydroxylase turnover.     

Primary cultures of human hepatocytes as a tool in cytotoxicity studies: cell protection against model toxins by flavonolignans obtained from Silybum marianum

The aim of this study was to evaluate the cytoprotective effects upon primary human hepatocytes of silymarin extract and its main flavonolignans following exposure to the cytotoxic actions of model toxins. The conditions for the hepatocyte intoxication were optimised for allyl alcohol, carbon tetrachloride, D-galactosamine and paracetamol. Silymarin extract, silychristin and silydianin did not exert cytotoxicity (10-100 microM), whereas silybin and isosilybin at higher concentrations and after longer incubation periods were cytotoxic. All main flavonolignans of silymarin tested displayed concentration-dependent cytoprotection against the toxic effects of both allyl alcohol and carbon tetrachloride but neither paracetamol nor galactosamine. The best protection was achieved by silydianin and silychristin and to a lesser degree by silymarin, while silybin and isosilybin were less effective. It is concluded that these differing outcomes result from the varying abilities of the Silybum marianum substances tested to stabilize the cell membrane, exert antioxidant properties and exhibit intrinsic toxicity.     

Chronically administered risperidone did not change the number of hepatocytes in rats: a stereological and histopathological study

Risperidone, an antipsychotic agent, has been used in the therapy of patients with acute and chronic schizophrenia. The strategy in the choice of antipsychotic agent should take into account the hepatic tolerance. The aim of the present study was to analyse whether or not the chronic administration of risperidone has a toxic effect on rat livers. Rats were divided into three groups. Low dose (n = 5) and high dose (n = 5) groups that were given 0.5 and 1 mg/kg intraperitoneal doses of risperidone daily for 6 weeks, respectively. The control group received distilled water as a vehicle. At the end of the experiment, the rats were killed, and livers were dissected out immediately and transferred into the fixation solution. Both conventional light and transmission electron microscopic tissue preparation procedures were applied to liver tissues and they were evaluated using stereological and histopathological methods; in this respect, this is the first study using stereological methods for searching the effects of risperidone on liver. There were no significant differences about the total hepatocyte number and their numerical density of rat liver between groups (P > 0.05). Stereological results were also confirmed by the histopathological findings that come from both structural and ultrastructural levels examination. The results of the current study indicate that neither low nor high doses of risperidone resulted in damage to the rat livers at cellular level. In conclusion, we did not find any evidence for hepatotoxicity of risperidone rats. Larger-scale, prospective studies are needed in order to confirm these findings.     

Curative effect of picroliv on primary cultured rat hepatocytes against different hepatotoxins: an in vitro study.

Picroliv, the standardized active principle from the plant Picrorhiza kurrooa showed significant curative activity in vitro in primary cultured rat hepatocytes against toxicity induced by thioacetamide (200 microg/mL), galactosamine (400 microg/mL), and carbon tetrachloride (3 microl/mL). Activity was assessed by determining the change in hepatocyte viability and rate of oxygen uptake and other biochemical parameters (GOT, GPT, and AP). The toxic agents alone produced a 40-62% inhibition of cell viability and a reduction of biochemical parameters after 24 h of incubation at 37 degrees C which (on removal of the toxic agents) was reversed after further incubation for 48 h. Incubation of damaged hepatocytes with picroliv exhibited a concentration- (1-100 microg/mL) dependent curative effect in restoring altered viability parameters. The results warrant the use of this in vitro system as an alternative for in vivo assessment of hepatoprotective activity of new agents.     

咽炎清滴丸对急性咽炎大鼠模型抗炎机理研究

目的：观察咽炎清滴丸的抗炎作用以及对急性咽炎模型大鼠血清白细胞介素－1β、白细胞介素－6、肿瘤坏死因子－α表达的影响。方法采用二甲苯制备小鼠耳肿胀模型、鸡蛋清制备大鼠足趾肿胀模型,考察咽炎清颗粒的抗炎作用;采用15％的氨水复制急性咽炎动物模型,给药后观察咽炎模型大鼠血清白细胞介素－1β、白细胞介素－6、肿瘤坏死因子－α含量的变化。结果咽炎清滴丸可以显著对抗二甲苯导致的小鼠耳肿胀,显著抑制鸡蛋清导致的大鼠足趾肿胀,降低急性咽炎模型大鼠血清白细胞介素－1β、白细胞介素－6、肿瘤坏死因子－α的含量。结论咽炎清滴丸对急性咽炎模型大鼠具有良好的治疗作用,这是其发挥临床疗效的重要基础。     

An ultrasensitive competitive binding assay for the detection of toxins affecting protein phosphatases.

An ultrasensitive assay is described for microcystin-LR and other substances (microcystins, nodularin, okadaic acid, calyculin A, tautomycin) which block the active site of protein phosphatases (PP) 1 and 2A. The assay is based on competition between the unknown sample and [125I]microcystin-YR for binding to the catalytic subunit of PP2A. The PP2A-bound [125I]microcystin-YR was stable (half-time of dissociation = 1.8 h), allowing non-bound [125I]microcystin-YR to be removed by Sephadex G-50 size-exclusion chromatography. Compared to current assays based on inhibition of protein phosphatase activity the present assay was more robust against interference (from fluoride, ATP, histone, and casein), and had an even better sensitivity. The detection limit was below 50 pM (2.5 fmol) for nodularin and microcystin-LR, and below 200 pM (10 fmol) for okadaic acid. The method was used successfully to detect extremely low concentrations of either microcystin or nodularin in drinking water or seawater, and okadaic acid in shellfish extract.