Carbohydrate, protein and glycoprotein metabolism by the guinea-pig liver in chronic metribuzin poisoning

Male guinea-pigs weighing 400-600 g, 8 months old, were given metribuzin directly into the gastric lumen over a period of 30 days (20 animals) or 90 days (20 animals) 6 times a week. In the liver of the poisoned animals, the glycogen level and the AspAT and AlAT activities, while in the serum the total protein and the fractions albumin, alpha 1-globulin and gamma-globulin significantly decreased; serum glucose and the serum fractions alpha 2-globulin and beta-globulin, each showed an increase. The glycogen level in the liver, total protein, glucose as well as the alpha 1 and alpha 2 globulin fractions in the serum showed not appreciable difference between 30 and 90 days of intoxication. After 90 days of metribuzin treatment AspAT and AlAT dropped in the liver and rose in the serum, in comparison to the 30-day values. As to the parameters of glycoprotein metabolism, the intoxicated animals showed a significant decrease and increase in concentration of hexosamines and sialic acids in the liver and serum, respectively. Metribuzin intoxication also cause a significant decrease in activity of glucosamine phosphate isomerase and significant increase in activity of glycosidases in the liver. The results suggest that metribuzin disturbs the metabolism of carbohydrates, proteins and glycoproteins in the guinea-pig liver.     

Influence of endotoxin on experimental post-alcoholic liver injury.

The morphological and biochemical changes of the liver after endotoxin intake were analyzed in rats receiving 20% ethanol during 60 days. Besides morphological changes, concentration of serotonin and histamine in liver homogenates, the activity of asparagine and alanine aminotransferases (AspAT, ALAT), gamma-glutamyltranspeptidase (GGTP) and alcohol dehydrogenase (ADH) in blood serum were determined, too. The most extensive morphologic changes of the liver were seen in group of animals intoxicated with 20% ethanol during 60 days and single dose of endotoxin E. coli 0127:B8 intraperitoneally. These changes included necrosis most hepatocytes, focal steatosis of liver parenchyma, considerable hyperemia and parenchymatous degeneration of the liver cells. The cells lining liver sinuses showed considerable swelling as well as necrotic changes. Figures of cell division and haemorrhagic focuses were seen, too. The clusters of mononuclear cells, surrounding necrotically changed hepatocytes were seen in the central part of the liver lobule. Among the inflammatory mediators estimated in liver homogenate only serotonin reached a high level in the group of experimental animals receiving only endotoxin. Increased activity of aminotransferases AspAt and ALAT were associated with these morphologic and biochemical changes in liver tissue observed in animals receiving ethanol and endotoxin.     

Uptake and clearance of plutonium-238 from liver cells transplanted into fat pads of F344 rats

This research is directed toward understanding the role of liver cells and the liver environment in plutonium biokinetics. Animals injected with liver cells and control animals received a single intraperitoneal injection of 37 kBq (1 microCi) 238Pu citrate and were serially sacrificed 1, 5, 10, 15, 30, 60 or 70 days later. Uptake, retention and distribution of Pu in intact liver and in liver cells growing in fat pads were determined. From these measurements, it was observed that the cells of the intact liver took up about twice as much 238Pu as liver cells transplanted into the fat pads of the same animal. The retention half-life was 8.3 days for the total activity in the liver, 20 days using tracks/cell measurements in the liver and 16 days for the tracks/cell measurements in the liver cells translocated to fat pads. When the data on tracks/cell were standardized relative to the amount of Pu present at 5 days after the injection, there was no significant difference between the retention of Pu in liver cells from intact animals and liver cells transplanted into the fat pads. About 20 per cent of the 5-day Pu liver burden in both liver cells and liver cells transplanted into fat pads was retained at 70 days. The smaller retention and clearance for liver cells in different environments indicate that uptake and clearance of Pu from the body is dependent, to a major extent, upon hepatocyte function.     

Regeneration of beta cells in islets of Langerhans of pancreas of alloxan diabetic rats by acetone extract of Momordica charantia (Linn.) (bitter gourd) fruits

Acetone extract of whole fruit powder of M. charantia (bitter gourd) in doses 25, 50 and 75 mg/100 g body weight lowered the blood glucose from 13.30 to 50% after 8 to 30 days treatment in alloxan diabetic albino rats, confirming antihyperglycemic effect of this plant in diabetic animals and humans. Histological observations with acetone extract showed different phases of recovery of beta cells of the islets of Langerhans of pancreas, which in the untreated diabetic rats were less in number and showed varied degree of atrophy. The most important finding of the present study was observation of the presence of small scattered islets among the acinar tissue in some experimental animals, which may reflect neoformation of islets from pre-existing islet cells. The liver of alloxan diabetic rats showed hydropic degeneration, fatty change and necrosis at some places but liver of extract treated animals was normal. Glycogen localization in liver of diabetic rats was faint but after 30 days treatment with different doses of extract, normal to heavy glycogen localization was observed.     

Influence of metribuzin on the Rhizobium leguminosarum--lentil (Lens culinaris) symbiosis.

The effects of the triazine herbicide metribuzin (Sencor) on the lentil (Lens culinaris Medic.) - Rhizobium leguminosarum biovar viciae symbiosis were studied in Leonard jars and growth pouches. Lentils inoculated with Rhizobium leguminosarum strain 128C54 or 128C84, and noninoculated lentils grown in plant nutrient solution supplemented with 5 mM KNO3, had metribuzin applied to the plants at either 8 or 13 days after planting. When sprayed at 8 days, metribuzin had a significant (p less than or equal to 0.05) negative effect on plant weight, number of nodules, taproot growth, and acetylene reduction activity. Five to 10 days after spraying, the plants began to recover from the inhibitory effects. When spraying was delayed to 13 days after planting, metribuzin had little effect on plant growth. The R. leguminosarum strain used as inoculant affected the degree of inhibition of lentil growth and the rate of plant recovery. Less than 0.2% of foliarly applied metribuzin was translocated to the root. Thus the detrimental effects of metribuzin application to lentils were mainly due to direct effects on the plant, which resulted in indirect effects on nodulation and nitrogen fixation.     

Adsorption and Degradation of Metolachlor and Metribuzin in a No-Till System Under Three Winter Crop Covers

The objective of this study was to quantify adsorption and degradation of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1 -methylethyl) acetamide] and metribizun [4-amino-6-(1,1 -dimethylethyl)-3-(methylthio)-1,2,4-trazine-5(4H)-one] in a soil planted to winter covers clover (Trifolium sp.), vetch (Vicia villosa), and wheat (Triticum aestivum). Surface soil samples (0 to 5?cm) from Memphis silt loam (fine-silty, mixed, thermic Typic Hapludalf) were collected and equilibrated with herbicide at initial concentrations ranging from 0 to 20?mg L^?1 that were then applied for a batch experiment. Soils were treated either with a single herbicide or a mixture of the two herbicides. For the degradation experiments, herbicides at a concentration of 10?mg kg^?1 soil were applied and incubated for 21?d at ～23°C. Metolachlor and metribuzin adsorptions were described by the Freundlich isotherm. Average Freundlich distribution coefficient (K_f) for metolachlor was significantly higher (p≥0.05) than that of metribuzin in soils under the three crop covers irrespective of method of application. The K_f for metolachlor ranged from 18.38 to 11.18?L kg^?1, and K_f for metribuzin ranged from 1.80 to 0.93?L kg^?1. Average normalized distribution coefficient (K_oc) for metolachlor was significantly higher (p≥0.05) than average K_oc for metribuzin irrespective of crop cover. After 21 days of incubation, average half-life of metolachlor across soil under the three crop covers was significantly higher than the average half-life of metribuzin (p≥0.05). Half-life values ranged from 20.6 to 24.9 days for metolachlor, and 4.4 to 12.4 days for metribuzin. In soils treated with metribuzin, the half-life was highest for soil under wheat and lowest for soil under clover (p≥0.05).     

The origin of reactive cells in retrograde and wallerian degeneration

Summary In order to examine the possible haematogenous origin of phagocytes in anterograde and retrograde degeneration, rabbit peritoneal macrophages were labeled in vitro with ³H-DFP and injected intravenously into host animals. Four or five days prior to the injection, the facial nerve was avulsed and the sciatic nerve ligated in five recipients. The animals were killed 24 h after the injection of the macrophages. Labeled cells were found in that part of the sciatic nerve which was mechanically damaged and in the liver and spleen but not in areas with retrograde or Wallerian degeneration. The possible interpretation of these findings is discussed.The present experiments were performed by M.O. after suggestions by A.T. These studies were supported by a grant from the Deutsche Forschungsgemeinschaft     

Isolation and characterisation of metribuzin-resistant Chlamydomonas reinhardii cells

Chlamydomonas reinhardii cells were treated with 5-fluorodeoxyuridine and ethylmethanesulfonate to induce mutagenesis. The mutant cells were analyzed for resistance against metribuzin (4-amino-6-(t-butyl)-3-methylthio-1,2,4-triazine-5-one). Clones with normal growth were isolated and the mutant cells further characterized. The photosynthetic rates of the mutant cells were about 20% lower than those of wild-type cells. The mutant cells were not only resistant against metribuzin (pI₅₀ lowered from 6.65 to 3.41) but also against bromacil, atrazine, phenisopham and tolerant against 3-(3,4-dichlorophenyl)-1,1-dimethylurea. However, the mutant was more susceptible to phenolic electron-transport inhibitors like bromonitrothymol, ioxynil and i-dinoseb. 2,4-Dinitrophenyl-2′-iodo-3′-methyl-4′-nitro-6′-isopropyl phenyl ether inhibited the wild-type thylakoids more than the mutant. The analysis of the electron transport with artificial electron donors and acceptors showed that only Photosystem II was affected by the mutation and not Photosystem I. Binding experiments with isolated thylakoids of resistant and susceptible cells using [¹⁴C]metribuzin and [³H]-i-dinoseb revealed that metribuzin did not bind specifically to the thylakoids of the mutant cells, but that i-dinoseb did bind to the thylakoids of the mutant, and even better than to the thylakoids of the wild-type cells. Fluorescence studies confirmed these results.     

Herbicide tolerance in maize is related to increased levels of glutathione and glutathione-associated enzymes

Treatment of 10 days old maize seedlings with metribuzin and pretilachlor near the recommended field-dose resulted in differential reductions in shoot fresh and dry weights during the following 16 days. Metribuzin showed great and consistent reductions, however, the reduction induced by pretilachlor, mostly nullified by the end of the experiment. Moreover, there were differential accumulations of lipid peroxides, carbonyl groups and H₂O₂ in maize leaves; metribuzin caused the greatest accumulation. Meanwhile, levels of thiol forms and reduced glutathione (GSH) were much more induced by pretilachlor than metribuzin; the contrary was true regarding oxidized glutathione (GSSG). The ratio of GSH/GSSG was highest following pretilachlor treatment and least by metribuzin. On the other hand, activities of glutathione-S-transferases (GSTs, EC 2.5.1.18), γ-glutamyl-cysteine synthetase (γ-GCS, EC 6.3.2.2), glutathione synthetase (GS, EC 6.3.2.3), glutathione peroxidase (GPX, EC 1.15.1.1) and glutathione reductase (GR, EC 1.6.4.2) were more enhanced in maize leaves by pretilachlor than metribuzin. These findings suggest the occurrence of an oxidative stress differentially induced in maize by the herbicides, a state that was most pronounced with metribuzin. Pretilachlor was concluded to be the least phytotoxic to maize, while metribuzin was the most, this differential tolerance seemed to be related to the induction of GSH and GSH-associated enzymes.     

Entamoeba histolytica: diffuse liver inflammation in gerbils (Meriones unguiculatus) with experimentally induced amebic liver abscess

The histopathological changes that occur in the uninfected liver lobes of gerbils with a localized amebic liver abscess (left lobe) were studied from 5 to 60 days after inoculation. Early parenchymal changes (10 days) in the right and median liver lobes showed a lymphocytic infiltrate and bile duct proliferation in the portal areas. Maximum alterations occurred at 20 to 30 days after inoculation and were characterized by a dense portal infiltrate, hepatocyte degeneration, granulocytic infiltrate and marked glycogen depletion. In drug-treated infections with metronidazole, the diffuse liver inflammation was terminated. The results of this study suggest that the diffuse liver injury was directly or indirectly induced by the presence of a proliferating amebic liver abscess and that the pathology caused by amebic liver abscess is more extensive than previously thought.     

Entamoeba histolytica: Diffuse Liver Inflammation in Gerbils (Meriones unguiculatus) with Experimentally Induced Amebic Liver Abscess

The histopathological changes that occur in the uninfected liver lobes of gerbils with a localized amebic liver abscess (left lobe) were studied from 5 to 60 days after inoculation. Early parenchymal changes (10 days) in the right and median liver lobes showed a lymphocytic infiltrate and bile duct proliferation in the portal areas. Maximum alternations occurred at 20 to 30 days after inoculation and were characterized by a dense portal infiltrate, hepatocyte degeneration, granulocytic infiltrate and marked glycogen depletion. In drug-treated infections with metronidazole, the diffuse liver inflammation was terminated. The results of this study suggest that the diffuse liver injury was directly or indirectly induced by the presence of a proliferating amebic liver abscess and that the pathology caused by amebic liver abscess is more extensive than previously thought.     

Genetic damage in multiple organs of acutely exercised rats

The aim of this study was to investigate the effects of acute exercise on genomic damage in an animal model. Male adult Wistar rats were divided into the following groups: control and acute exercised (experimental). For this purpose, 15 animals were accustomed to running on a rodent treadmill for 15 min per day for 5 days (10–20 m min^?1; 08 grade). After 4 days at rest, active animals ran on the treadmill (22 m min^?1, 58 grade) till exhaustion. Cells from peripheral blood, liver, heart, and brain were collected after 0, 2, and 6 h after exercise. The results showed that acute exercise was able to induce genetic damage in peripheral blood cells after 2 and 6 h of exercise, whereas liver pointed out genetic damage for all periods evaluated. No genetic damage was induced either in brain or in heart cells. In conclusion, our results suggest that acute exercise could contribute to the genetic damage in peripheral blood and liver cells. It seems that liver is a sensitive organ to the genotoxic insult after acute exercise. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of continuous light and darkness on the eyes of the troglobitic salamander Typhlotriton spelaeus

Larval Typhlotriton spelaeus collected from five caves in Pulaski Co., Missouri, were kept as larvae or induced to transform in darkness or continuous fluorescent illumination. Larvae maintained in darkness for 215 and 279 days had smaller eyes, smaller rod inner and outer segments, and fewer metaphase figures in the genninative zone of the neural retina than comparable larvae maintained in light (258 lux). Except for visual cell size, differences were small and for each characteristic exceptions were observed. One larva kept in light showed early retinal degeneration comparable to that in transformed adults of T. spelaeus. All larvae exhibited optomotor behavior both before and after the experiment. Among animals induced to transform by L-thyroxin and maintained in darkness 111 to 366 days, visual cell and pigment epithelium degeneration was more extensive and more frequent than in animals kept for the same length of time in light (237-298 lux). In darkness the frequency of animals with retinal degeneration increased between 111 and 366 days. In light some animals exhibited pigment epithelium reduction with normal visual cells, and others had free, pigmented cells in the subretinal space. These effects were not comparable to degeneration in darkness. Eyelids covered the eyes of only a few animals in both light and dark treatments. The extent of eyelid encroachment over the eye was greater in darkness than in light. Most animals exhibited optomotor responses after experiments, but responses of animals kept in darkness were impaired in comparison to those of animals kept in light.     

Excessive reversible phenobarbital induced nuclear DNA-polyploidization in the growing mouse liver

Summary Phenobarbital was injected intraperitoneally into male white NMRI mice aged 0.5, 1, 1.5, 3, 6 and 12 months at a dose of 120 mg/kg body weight for 10 consecutive days. The 0.5 month-old mice did not tolerate the phenobarbital dose and died. The experimental animals and one of the controls were sacrificed 1, 3, 5, 10, 15 and 20 days after phenobarbital administration was started. Liver weights were recorded and liver cells were isolated. The number of nuclei per cell was determined and the DNA-content of each single nucleus was measured by Feulgen fluorescence cytophotometry. Liver weights showed an increase of 25–30% during phenobarbital treatment and returned slowly to lower values after cessation of drug application. The hepatic enlargement was accompanied by an excessive and likewise reversible nuclear and whole cell DNA-polyploidization, i.e. polyploidization beyond the physiological age-dependent ploidy level; for example, mean values of 7.7 c per nucleus (versus 4.2 c in the controls) and 14.3 c for whole liver cells (versus 7.5 c in the controls) were found in 3 months-old animals after 5 days of treatment. As with the induction of microsomal enzymes, the augmentation of smooth endoplasmic reticulum, and the increase of RNA- and protein-synthesis, excessive DNA-polyploidization of liver cell nuclei appears to be an expression of hepatocellular hypertrophy due to the functional or metabolic stress imposed upon the liver by large quantities of phenobarbital. After cessation of drug administration the abnormally high ploidy cells are eliminated-probably by necrobiosis — and the liver cells return to their normal age-dependent DNA-ploidy level. The liver cells of the one-month-old animals revealed the physiological polyploidization to be slightly inhibited. This is probably due to some toxic effect of phenobarbital. Phenobarbital did not alter the number of nuclei per liver cell.Supported by Deutsche Forschungsgemeinschaft, Grant No. Bo 395/5     

中海拔地区慢性暴露大鼠心肌及肝脏的光镜及电镜观察

目的 探讨中度海拔高度地区慢性低氧大鼠心肌、肝的组织学及超微结构变化。方法 本实验用Wistar大鼠20只,雌雄各半,六日内从海拔5米运至海拔3418米饲养,8周后断头处死大鼠,留取心肝组织作光电镜观察,同时高原暴露前后测定血RBC数及Hb含量。结果 心肝组织学改变主要为细胞水肿,即心肌颗粒变性,肝细胞疏松化,其次为心肌、肝细胞嗜酸性变。心肌组织有少量小灶状坏死,肝组织中未见坏死。超微结构主要有肌浆网扩张,线粒体肿胀,糖元颗粒减少,未见不可逆性损伤如线粒体出现杆状嵴、三膜嵴及核染色质边聚现象。毛细血管内皮细胞多有突起伸向管腔,胞质空泡变性,微饮泡较少。另外,高原暴露后RBC数及Hb含量明显升高。结论 该海拔地区慢性低氧大鼠心肌、肝组织及毛细血管的病变是可逆性的; 左右心室病变程度无显著性差异; 肝组织的病变程度明显轻于心肌组织。     

Structural and ultrastructural hepatic changes in experimental canine leishmaniasis

Six 4 month-old beagles were inoculated with Leishmania donovani infantum, three of them intraperitoneally (Group A) and the other three intravenously (Group B). The animals from Group A were killed 109, 433 and 592 days after inoculation and animals from Group B 109, 171 and 334 after inoculation. The liver of each of them was examined by means of light and electron microscopy. The lesions observed in both groups were very similar, but developed more rapidly in Group B. A chronic hepatitis appeared due to infection, characterized by the presence of multiple intralobular granulomas and portal inflammatory infiltrates consisting of lymphocytes, plasmocytes and macrophages with a variable number of amastigotes. The Kupffer cells were hyperplastic and contained parasites in their cytoplasm. Gradually the hepatocytes developed a progressive cellular swelling, which during the end-stages of the process showed itself with severe nuclear degeneration, disintegration of cytoplasmic organelles, enlargement of the cytoplasmic matrix and disruption of the plasma membranes, leading to cytolysis.     

Entamoeba histolytica: antibody responses and lymphoreticular changes in gerbils (Meriones unguiculatus) in response to experimental liver abscess and amebic extract infection

Antibody responses and histological changes in hepatic lymph nodes and spleen of gerbils (Meriones unguiculatus) during the course of experimental hepatic amebiasis (5-60 days), or in those injected with extracts of Entamoeba histolytica, are described. Lymph node and spleen responses in infected animals paralleled the proliferation of the amebic liver abscess. However, spleen follicle responses were similar in animals that received low or high doses of the amebic extract and differed histologically from those with amebic liver abscess. Liver abscesses, up to 30 days postinfection (pi), doubled in weight between 10 and 15 and between 20 and 30 days pi. Early changes (10 days pi) in the lymphoreticular tissues were characterized by increased size and weight of the organs, hyperplastic follicles, and blastogenesis in the T-dependent areas. At 20 and 30 days pi, the size of spleen follicles increased and there was depletion of lymphocytes from the periarterial area (PAA), as well as gross extension of the red pulp, accompanied by extramedullary erythropoiesis and megakaryocytosis. The paracortical areas (PCA) of lymph nodes were depleted of lymphocytes and histiocytosis throughout the organ, and there was intense plasma cell activity in the medulla. At 60 days pi, lymphocyte repopulation was noted in the PCA and PAA; germinal centers were depleted of blast cells and the spleen red pulp had contracted. Antiamebic antibody titers were low throughout the infection. Changes in the cellularity of the lymphoid organs are discussed in relation to the proliferation of the amebic liver abscesses in infected animals and in those which were injected with the amebic extract.     

Changes of hippocampal neurons after perinatal exposure to ethanol

The effect of ethanol on the structural development of the central nervous system was studied in offspring of Wistar rats, drinking 20 % ethanol during pregnancy and till the 28th day of their postnatal life. The structural changes in the hippocampus and dentate gyrus were analyzed at the age of 18, 35 and 90 days. A lower width of pyramidal and granular cell layers, cell extinction and fragmentation of numerous nuclei were found in all experimental animals compared to control animals. The extent of neural cell loss was similar in all monitored areas and in all age groups. At the age of 18 and 35 days, the degenerating cells were observed in the CA1 and CA3 area of the hippocampus and in the ventral and dorsal blade of the dentate gyrus. Numerous glial cells replaced the neuronal population of this region. Some degenerating cells with fragmented nuclei were observed at the age of 90 days. Our experiments confirmed the vulnerability of the developing central nervous system by ethanol intake during the perinatal period and revealed a long-lasting degeneration process in the hippocampus and dentate gyrus.     

The Liver Cells in Acute Starvation and Refeeding

A series of 52 young male white laboratory mice were starved for a maximum of five days, and 45 normally fed animals were used as controls. A group of experimental animals and a corresponding control group were sacrificed after two, three, and four days' starvation and after six, 12 and 17 days' refeeding. Even after two days the animals had lost weight, and the liver cells had diminished highly significantly. A return to the initial values was noted after 12 days' refeeding. In the experimental animals a strong negative correlation was noted between the cell count per field and body weight (r =–0.712, b =–7.520), while no such correlation was observed for the controls. The volume of the liver cells was reduced by 61.7 %, the volume of their nuclei by 16.2 % after four days' starvation. After two to three days' starvation the liver cells often showed a slight accumulation of fat. Mitoses were frequent in the liver cells during the stage of regeneration, when the cells had attained the same size as in the controls.     

Engraftment and differentiation of embryonic stem cell-derived neural progenitor cells in the cochlear nerve trunk: growth of processes into the organ of Corti

Hearing loss in mammals is irreversible because cochlear neurons and hair cells do not regenerate. To determine whether we could replace neurons lost to primary neuronal degeneration, we injected EYFP-expressing embryonic stem cell-derived mouse neural progenitor cells into the cochlear nerve trunk in immunosuppressed animals 1 week after destroying the cochlear nerve (spiral ganglion) cells while leaving hair cells intact by ouabain application to the round window at the base of the cochlea in gerbils. At 3 days post transplantation, small grafts were seen that expressed endogenous EYFP and could be immunolabeled for neuron-specific markers. Twelve days after transplantation, the grafts had neurons that extended processes from the nerve core toward the denervated organ of Corti. By 64-98 days, the grafts had sent out abundant processes that occupied a significant portion of the space formerly occupied by the cochlear nerve. The neurites grew in fasciculating bundles projecting through Rosenthal's canal, the former site of spiral ganglion cells, into the osseous spiral lamina and ultimately into the organ of Corti, where they contacted hair cells. Neuronal counts showed a significant increase in neuronal processes near the sensory epithelium, compared to animals that were denervated without subsequent stem cell transplantation. The regeneration of these neurons shows that neurons differentiated from stem cells have the capacity to grow to a specific target in an animal model of neuronal degeneration.