Chlordecone-induced potentiation of carbon tetrachloride hepatotoxicity: a light and electron microscopic study

Previous studies have shown that a chlorinated pesticide, chlordecone (Kepone), greatly potentiates carbon tetrachloride (CCl4) hepatotoxicity and lethality (Curtis, L.R., Williams, W.L., and Mehendale, H.M. (1979). Toxicol. Appl. Pharmacol. 51, 283-293; Curtis, L.R., and Mehendale, H.M. (1980). Drug Metab. Dispos. 8, 23-27). The present study describes sequential morphologic changes which occurred in livers of rats given a "nontoxic" level of chlordecone (10 ppm for 15 days) followed by a single injection of CCl4 (0.1 ml/kg). The hepatic alterations were examined 1 to 36 hr after exposure of the rats to CCl4. Those changes were compared to hepatic alterations which occurred in rats that received the same dose of chlordecone (10 ppm for 15 days) or a single injection of CClr (0.1 ml/kg) alone. The only change noted in livers from rats that received chlordecone alone was focal increase in smooth endoplasmic reticulum (SER) of hepatocytes at 24 hr and continuing throughout the time course of the experiment. Livers from animals that received CCl4 alone showed morphologic changes at 6 hr consisting of glycogen loss, increase in SER, and dilatation of rough endoplasmic reticulum (RER) in pericentral hepatocytes. Accumulation of small lipid droplets was also noted in midzonal hepatocytes. After 6 hr, there was no further increase in severity of injury. At 12 hr recovery was noticeable and, by 36 hr, livers from the CCl4 group appeared normal. Prior administration of chlordecone greatly potentiated pathologic changes in livers of animals that received CCl4. By 4 hr, there was total loss of glycogen in hepatocytes throughout the entire lobule. Small lipid droplets were present in pericentral, midzonal and periportal hepatocytes. Hepatocytes with extremely dilated RER were randomly scattered throughout the entire lobule. At 6 hr, there was further accumulation of lipid in the form of large droplets in hepatocytes. Focal, necrotic cells surrounded by polymorphonuclear leukocytes were randomly distributed throughout the lobule. The number of necrotic foci had progressively increased at the 12- and 24-hr intervals. By 36 hr, confluent areas of necrosis in pericentral and midzonal areas were observed in livers of some animals. This study indicates that although the combination of chlordecone and CCl4 produces much greater hepatic injury resembling damage due to a massive dose of CCl4, histologically, some differences in the progression and distribution of hepatocellular damage within the lobular architecture of the liver are evident.     

Acute toxic effects of paraquat on ultrastructure of rat liver

Paraquat was administrated to pathogen-free male rats orally, and the livers were studied by light and electron microscope at intervals of 6 hours to 5 days. Congestion and hepatocellular injury (degeneration and/or fatty metamorphosis) were seen by light microscope. Electron microscope showed that degranulation of RER, proliferation of SER, decreasing of glycogen particles and mitochondrial swelling occurred in the cytoplasm of the hepatocytes within 2 layers around the central vein at 6 hours. After 12 hours the liver cells throughout the centrolobular area were injured. Degranulation of RER, proliferation of SER, and decreasing of glycogen particles became prominent, and mitochondria showed swelling and transformation. In the midzonal and periportal areas, numerous lipid droplets were seen in the cytoplasm of the hepatocytes. From the result of ultrastructural findings, it is considered that detoxication and biotransformation of paraquat occur in the hepatocytes within 2 layers around the central vein at an early stage, and spread to the hepatocytes throughout centrolobular area later.     

Rubratoxin B mycotoxicosis in the Syrian hamster: ultrastructural alterations

Rubratoxin B was given to Syrian hamsters as a single intraperitoneal dose of 0.4 mg/kg. Hamsters were killed at 1, 2, 4, and 6 hr after dosing, and the kidneys and liver were fixed by intravascular perfusion. Renal ultrastructural alterations were evident at 1 hr after treatment and were limited to the straight portion of the proximal tubule. The most prominent alterations were brush border disruption, dilation of smooth endoplasmic reticulum, mitochondrial swelling, cytoplasmic rarefaction, myelin figure formation, and swelling of basal interdigitating processes. Renal alterations were suggestive of damage to membrane structure and/or transport functions and interference with cellular bioenergetics. Hepatic alterations were not seen in the rubratoxin B-treated hamsters of this study.     

Rapid alterations induced by insulin in hepatocyte ultrastructure and glycogen levels

The speed with which insulin alters hepatocyte ultrastructure and glycogen levels in insulin-deficient rats has been studied. Insulin deficiency was induced with alloxan, followed by insulin treatment with regular and NPH insulin. Rats were killed at various times after the insulin injection, blood samples were obtained, plasma glucose levels were determined, and liver samples were prepared for electron microscopy and glycogen determinations. Plasma glucose levels in insulin-deficient rats declined to normal values by 4 hours post insulin, returning to insulin-deficient levels by 8 hours post insulin. Hepatic glycogen was considerably reduced in the insulin-deficient rats. By 1 hour post insulin hepatic glycogen increased, reached maximal levels by 8 hours, then declined to insulin-deficient levels by 36 hours. The ultrastructural appearance of both centrilobular and periportal hepatocytes from insulin-deficient rats showed abundant vesicular smooth endoplasmic reticulum (SER), decreased rough endoplasmic reticulum (RER), and enlarged RER intracisternal spaces. One-half hour post insulin, centrilobular hepatocytes were unchanged. In periportal hepatocytes, however, vesicular SER was no longer visible, the RER intracisternal spaces appeared normal, and the amount of RER had increased. By 1 hour post insulin the centrilobular hepatocytes showed similar ultrastructural changes. These changes became more pronounced in the next few hours and remained through 24 hours. By 36 hours both centrilobular and periportal hepatocytes appeared similar to those in the insulin-deficient rat. These results demonstrate the rapid and lobular-specific effects insulin has on the hepatocyte.     

Ultrastructural changes in the liver in heatstroke.

The ultrastructural changes in the human liver 24 to 96 hours after an attack of heatstroke are described. The alterations are most obvious along the vascular pole of the hepatocytes. These consist of degenerative changes or desquamation of sinusoidal lining cells, ballooning or flattening of microvilli, breaks in hepatocyte outer membranes, and electron-lucent vacuoles along the sinusoidal border. Also noteworthy is the appearance, in a number of cases, of basement membranes or ill-defined electron-dense material which may be of basement membrane character. Sinusoidal elements, such as erythrocytes, are found in hepatocytes, and hepatocellular debris appears in sinusoids. The membranes of hepatocytes and sinusoidal lining cells thus seem to be the prime targets of the hepatic injury in heatstroke. Other changes in the hepatocytes include vesiculation of endoplasmic reticulum, detachment of ribosomes, and alterations of mitochondria. Morphologic evidence of intravascular coagulation of intravascular hemolysis is often encountered. A comparison between the findings described here and those in experimental hyperthermia suggests that many of the hepatic changes seen in heatstroke are due to an excessively high tissue temperature per se but that some of the alterations are probably a consequence of complicating factors such as hypoxia, intravascular hemolysis, or disseminated intravascular coagulation.     

Apoptosis--the mechanism of cell death in dimethylnitrosamine-induced hepatotoxicity

Dimethylinitrosamine (DMN) induces an acute haemorrhagic centrilobular necrosis when given as a single dose to rats. In this study, the progression of the lesion was studied at the ultrastructural level in order to elucidate the precise mechanisms of hepatic injury. Within 3 h of a single dose of DMN there was disruption of endothelial lining cells. In areas of endothelial cell loss, the exposed hepatocyte sinusoidal membranes became simplified and flattened. In the centrilobular area, hepatocytes became apoptotic and by 16 h apoptotic bodies, formed from degenerate hepatocytes, were engulfed by intact hepatocytes or by circulating macrophages. This progressive degeneration of hepatocytes and endothelial cells gave rise, by 24 h, to the classically recognized centrilobular haemorrhagic necrosis. The damage to the endothelial cells was concurrent with, or in some areas prior to, significant morphological changes in adjacent hepatocytes. This contrasts with other hepatotoxins such as carbon tetrachloride where the primary target is the hepatocyte, giving rise to hydropic degeneration and coagulative necrosis. DMN, however, results in apoptosis, a mechanism of cell death not normally associated with chemically induced injury.     

Acute ischemic changes in intestinal muscularis.

A chronologic study of ischemic changes in the mouse intestinal muscularis was done to delineate the morphologic alterations occurring within 24 hours of ischemia. The muscle cells initially contracted with segmental condensation of myofilaments. Subsequently, increasing degeneration and lysis of myofilaments resulted in the formation of dense degenerative bands and nodules alternating with clear segments in the muscle cells. Eventually, the myofilaments disintegrated. Mitochondria were initially swollen and subsequently condensed, shrunken, and fragmented. The plasma membrane showed progressive dissolution and eventually disappeared. These ultrastructural changes were represented by discernible changes in the histologic sections.     

ULTRASTRUCTURE OF HUMAN HEPATOCELLULAR CARCINOMA

Twelve human hepatocellular carcinomas (HCC) were studied ultramicros-copically. In the aspects of development of cytoplasmic organelles, well differentiated cancer cells were similar to the normal hepatocytes. On the other hand, poorly differentiated HCC cells contained little cytoplasmic organel-le except for relatively developed rER and ribosomes. HCC cells showed not only several differentiations but also many degenerative changes, such as fatty metamorphosis, "dark" and "clear" cells, "fingerprint" formation and myelin-like figure, and the ultrastructural alterations of the vessels among HCC cells could play one of the most important roles in causing these degenerative changes in human HCC cells.     

Ultrastructural changes of mouse brain neurons infected with Japanese encephalitis virus

Ultrastructural changes of mouse brain neurons infected intracerebrally with Japanese encephalitis (JE) virus were studied. JE virus selectively infected the neurons, causing ultrastructural changes in association with viral replication in the cellular secretory system, principally involving rough endoplasmic reticulum (RER) and the Golgi apparatus. In the early phase of infection, RER of infected neurons showed hypertrophic changes, containing assembling virions within its dilated cisternae. In the later phase, the RER became cystic and degenerative and dissolved into the cytoplasm. The Golgi apparatus also contained in its saccules multiple virions, presumably transported from the RER cisternae, which were then released into the cytoplasm within coated vesicles for secretory-type exocytosis. In the process, the Golgi apparatus also fragmented and degenerated through vesiculation, vacuolation, and dispersion. Thus, the JE virus infection of neurons resulted in obliteration of RER and the Golgi apparatus, leaving behind the rarefied cytoplasm devoid of these organelles. However, destruction of the neurons themselves was not prominent and infected neurons in the later phase of infection showed some regenerative changes of these membranous organelles. The cause of death of infected animals, therefore, appeared to be extensive neuronal dysfunction rather than neuronal destruction in the CNS.     

Chlordecone-induced potentiation of carbon tetrachloride hepatotoxicity: a morphometric and biochemical study

The present study, conducted over a time course of 36 hr after CCl4 administration, describes sequential morphometric and biochemical changes which occur in livers of rats exposed to a combination of low levels of chlordecone (10 ppm for 15 days) and a single ip injection of CCl4 (0.1 ml/kg). Those changes were compared to hepatic alterations which occur in rats that received the same dose of chlordecone or CCl4 alone. Biochemical studies showed only trivial increases in levels of glutamic-pyruvic transaminase (GPT), glutamic-oxalacetic transaminase (GOT), and moderate but temporary increases in isocitrate dehydrogenase (ICD) after CCl4 alone. The combination of chlordecone and CCl4 resulted in significantly greater elevations of all three serum enzymes at all time intervals examined. Morphometric data showed no difference between normal diet controls and animals exposed to chlordecone alone as far as numerical density of hepatocytes or volume densities of hepatocytes with glycogen, lipid, dilated rough endoplasmic reticulum (RER), pyknosis, or mitoses. Morphometric analysis of livers from animals that received CCl4 alone showed decreases in numerical density, temporary decrease in percentage of hepatocytes containing glycogen, an increase in hepatocytes containing lipid, temporary increase in hepatocytes with dilated RER, and temporary increases in pyknotic nuclei. Soon after the initial hepatic injury was histologically evident between 4 and 6 hr, the number of mitoses increased dramatically and this progressed until complete recovery from CCl4 damage. From all indices of damage, complete recovery was evident by 36 hr after CCl4 administration.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ultrastructural changes induced by Solanum incanum aqueous extract on HCT 116 colon cancer cells

Medicinal plants have recently gained increasing scientific interest as an important source of molecules with different therapeutic potentials. Accordingly, the present study was carried out to investigate ultrastructural changes induced by the aqueous extract of Solanum incanum (SI) fruit on human colorectal carcinoma cell line (HCT 116 cells). Examination of SI-treated HCT 116 cells with transmission electron microscopy (TEM) demonstrated numerous ultrastructural changes in the form of loss of the surface microvilli, mitochondrial damage and dilatation of cristae, and formation of autophagic vacuoles and increasing numbers of lipid droplets. Also, majority of the treated cells showed nuclear shrinkage with chromatin condensation and nucleolar changes. Moreover, some cells showed focal areas of cytoplasmic degeneration associating with formation of myelin figures and fatty globules. In conclusion, TEM was able to verify cytotoxicity of SI aqueous extract against HCT 116 colon cancer cells.     

Role of alpha-lipoic acid in ameliorating Cyclosporine A-induced pancreatic injury in albino rats: A structural,ultrastructural, and morphometric study

The aim of this study was to investigate the effectiveness of alpha-lipoic acid (α-LA) against cyclosporine A (CsA)-induced pancreatic toxicity in rats. Thirty-two male albino rats were divided into four equal groups. Group I treated orally (per os, p.o.) with vehicles and served as control; Group II received α-LA (100 mg/kg b.w. /day, p.o.) for 21 days; Group III received CsA (25 mg/kg b.w./day, p.o.) for 21 days; and Group IV received α-LA 1 hr before oral treatment by CsA for 21 days. Histological examination of the pancreas of CsA-treated rats showed marked changes represented by wide interlobular septae that contained congested blood vessels, cytoplasmic vacuolation of some acinar cells, and distortion of the other cells. Most of the islets of Langerhans showed vacuolation, degenerative changes, and loss of uniform cellular distribution. Some of the islets appeared shrunken with few cells. In the CsA group, the immunohistochemical and morphometric study demonstrated a decrease in the number of insulin-secreting β-cells and also a reduction in islet diameters, with statistically significant difference (p < 0.001 and p = 0.004), respectively, compared with the control group. Ultrastructure of the exocrine and endocrine pancreatic cells of the CsA-treated group confirmed the light microscopic observation and showed dilated rough endoplasmic reticulum, decreased zymogen and secretory granules, damaged mitochondria, and abnormal nuclei. However, α-LA administration simultaneously with CsA resulted in some sort of regression of the previously mentioned effects. Conclusion: α-LA attenuated CsA-induced structural and ultrastructural changes in pancreatic cells, which were nearly reverted to their normal structure.     

Primary ornithine transcarbamylase deficiency. A case report and electron microscopic study

Histological and ultrastructural findings obtained upon examination of a liver biopsy specimen from a 2-year-old girl with primary ornithine transcarbamylase (OTC) deficiency are presented. The OTC activity in the hepatic tissue of the patient was 7% that of the normal level. Light microscopic observation showed diffusely swollen hepatocytes with pale or empty cytoplasm due to accumulation of glycogen. Neither fat degeneration nor necrosis was evident. Electron microscopy revealed strikingly abnormal hepatocyte mitochondria, which showed marked polymorphism with elongation and enlargement, ring- or dumbbell-shaped configurations, and irregular distribution and shortening of the cristae. Mitochondria showing degenerative alterations such as swelling and rarefaction, which have been reported in cases of Reye's syndrome, were present, but their number was very small. Other organelles showed no remarkable change. It is suggested that the mitochondrial changes seen in OTC deficiency are essentially different from those in Reye's syndrome, which otherwise is clinically and biochemically very similar to OTC deficiency.     

Ultrastructure of the pinealocytes in rats exposed to light and radiation

Changes in pinealocytes (PC) were analysed using quantitative electron microscopy in 240 adult male rats from first minutes up to 180 days after their continuous exposure to bright light (CLE) for 48 hours, X-ray irradiation (XRI) or their combination (CE). After CLE early changes of PC included the reduction of rough endoplasmic reticulum (RER), Golgi complex and synaptic ribbons. At 24 hours and 10 days PC secretory activity was increased, while their ultrastructural organization was normalized by 30-180 days. 10 days after XRI degenerative changes were detected in PC that included dilation, fragmentation and vacuolization of RER cisterns, mitochondrial swelling, appearance of large vacuoles and osmiophilic inclusions, increase in lysosome content. Volume density of mitochondria and RER was lower, while that of Golgi complex was higher than in control. PC ultrastructure was restored 30-180 days after XRI. Following CE, the changes in PC ultrastructural organization were more significant at all time interval studied than after the action of single factors. The results obtained indicate that CLE increased the extent of postradiation changes in PC ultrastructural organization during the early time intervals after XRI and at the peak of radiation sickness development.     

Trypanosoma lewisi: Ultrastructural changes in rat liver

Summary Host responses to infection were examined by observing the ultrastructural changes in liver from rats infected withTrypanosoma lewisi from day 1 to day 49 of infection. Trypanosomes were present in large numbers in the sinusoids on the 7th day of infection. By day 14, trypanosomes were seen in kupffer cells. The endoplasmic reticulum showed distended cisternae from day 4 of infection to day 14 of infection. Mitochondria in liver from infected rats increased in number and were swollen only on day 7 of infection. The hepatocytes showed focal areas of lipid from day 7 to day 28 of infection. Residual lysosomes in kupffer cells were found from the 14th to 21st day of infection. Initially, glycogen was dispersed but as the infection advanced, it became aggregated by day 7 of infection. By the 49th day of infection, glycogen again appeared dispersed. At the 35th, 42nd and 49th days of infection, the appearance of the liver was similar in general to that of normal liver.     

Cocaine hepatotoxicity in mice: histologic and enzymatic studies

The severity of hepatotoxicity in CF-1 mice given 5 daily doses of 5, 10, and 20 mg cocaine/kg body weight and sacrificed 24 hr after the last injection appeared to be dose-dependent. Using light microscopy, the hallmark of cocaine early toxicity was manifested by pallor and ballooning of the hepatocytes in the midzonal and then in the centrilobular areas. Degeneration and necrosis of the liver cells in the same zones were encountered while the hepatocytes in the periportal areas remained intact. When examined under the electron microscope, such pallor and ballooning of the hepatocytes appeared to to be due to dilation of the rough endoplasmic reticulum (RER) profiles which often revealed a significant loss of their ribosomes. Dilation of the smooth endoplasmic reticulum (SER) was also common and moderate proliferation of peroxisomes was frequently seen. In the degenerating hepatocytes, the 2 forms of endoplasmic reticulum were difficult to recognize and the peroxisomes appeared sparse. Cocaine treatment elevated the level of glutamic pyruvic transaminase and glutamic oxaloacetic transaminase in a dose-dependent manner. Although hepatic cytochrome P450 was slightly increased in the low dose groups, a reduction in the enzyme activity was noticed in the group treated with 20 mg cocaine/kg. However, hepatic reduced glutathione content manifested a significant increase in the group which received 20 mg cocaine/kg.     

Histopathological and ultrastructural alterations of induced Yersinia enterocolitica infection in mice

Yersinia enterocolitica is an enteric bacterium and infections by this organism are mostly foodborne. It has been implicated to cause enterocolitis, terminal ilitis. diarrhoea, mesenteric lymphadenitis and arthritis in man. Due to paucity of information regarding histopathological and specially ultrastructural alterations in tissues affected, this study was planned with mice as the experimental model. Nine pathogenic Y.enterocoliticaisolates were used to infect 80 albino mice by oral and intraperitoneal route. Pathological alterations were studied by light and electron microscopy. Histopathological examination of intestines showed severe edema, purulent enteritis, goblet cell hyperplasia infiltration of mononuclear cells, thickening of mucosa and necrosis of the tips of villi. Liver showed congestion, hepatocellular degeneration and necrosis, atrophy of hepatocytes and microabcesses. The lungs revealed congestion, edema, haemorrhage and purulent ronchopneumonia, while kidneys showed mild necrotic changes and bacterial emboli in glomeruli. Ultrastructural changes were indicative of mitochondrial degeneration and their loss in kidneys, membranous degeneration with formation of myelin figures in lungs and disorganization, disruption and bleb formation of microvilli in intestines. Y.enterocolitica caused significant histopathological and ultrastructural alterations in experimentally infected mice. Variation in pathogenicity of different strains of Y.enterocolitica was also observed.     

Primary Ornithine Transcarbamylase Deficiency A Case Report and Electron Microscopic Study

Histological and ultrastructural findings obtained upon examination of a liver biopsy specimen from a 2 year old girl with primary ornithine transcarbamylase (OTC) deficiency are presented. The OTC activity in the hepatic tissue of the patient was 7% that of the normal level. Light microscopic observation showed diffusely swollen hepatocytes with pale or empty cytoplasm due to accumulation of glycogen. Neither fat degeneration nor necrosis was evident. Electron microscopy revealed strikingly abnormal hepatocyte mitochondria, which showed marked polymorphism with elongation and enlargement, ring or dumbbell shaped configurations, and irregular distribution and shortening of the cristae. Mitochondria showing degenerative alterations such as swelling and rarefaction, which have been reported in cases of Reye's syndrome, were present, but their number was very small. Other organelles showed no remarkable change. It is suggested that the mitochondrial changes seen in OTC deficiency are essentially different from those in Reye's syndrome, which otherwise is clinically and biochemibcally very similar to OTC deficiency. Acta Pathol Jpn 39: 451 456, 1989.     

Primary demyelination in Theiler's virus infection. An ultrastructural study.

Theiler's virus infection in SJL/J mice was studied ultrastructurally at subsequent intervals after intracerebral inoculation. Extensive spinal cord lesions consisting of leptomeningeal and white matter mononuclear cell infiltrates with concomitant primary demylination were seen by 15 days. Stripping of myelin lamellae by invading mononuclear cell processes and vesicular disruption of myelin were demonstrated to be the patterns of myelin breakdown. Oligodendrocytes in the vicinity of demyelinating lesions never showed degenerative changes, and viral inclusions could not be found in any cells in the central nervous system. Remyelinating axons, first detected 21 days after infections, were more frequently seen in the late phase of the disease when conspicuous gliosis was also present. Active demyelination could still be observed as late as one year after infection at which time inflammation was decreased. However, plasma cells were relatively more numerous at later times after infection. These ultrastructural findings are similar to experimental allergic encephalomyelitis, and suggest an immune-mediated mechanism of demyelination in Theiler's virus infection.     

Ultrastructure of early changes in circumscribed cryonecrosis of the liver

Introduction: The changes occurring during the initial phase of a circumscribed cryonecrosis of the liver were systematically observed.Material and Methods: Circumscribed necroses were produced in the liver with a copper cryoprobe (Grünenthal, Model H 29, Φ 3,2 mm, operating at ?196°C), applied for 30 sec. For light- and electronmicroscopic investiagtions, tissue samples from the frozen area and its surroundings were taken immediately after freezing and at certain time intervals until 24 hours later.Results and Discussion: No important changes were observed immediately after freezing. After 2 to 3 minutes, the frozen tissue had thawed. Considerable stasis occurred within the sinusoids and veins of the affected area. After 2 minutes, the sinusoidal endothelial cells showed a shift towards the lumen and ruptures of their plasma membranes; after 30 minutes, these cells were almost completely fragmented and surrounded by fibrin precipitates. After 30 minutes, hepatocytes showed “optically empty” vacuoles in the cytoplam, swelling of mitochondria (matrix type), disorganization, fragmentation, vesiculation and degranulation of the rough endoplasmic reticulum and pyknosis and karyorrhexis of the nuclei. After 2 hours, the sinusoidal endothelial cells and the hepatocytes bore marks of irreversible lesions and necrosis. At the periphery of the necrotic area there was a narrow zone of hepatocytes with well-preserved nuclear structure, some fatty change, and slight swelling of mitochondria. Simultaneously, a leukocytic infiltrate was present around the damaged tissue, from which leukocytes had penetrated into the necrotic area. After 18 and 24 hours, the peripheral zone with degenerative changes in the hepatocytes showed single cell necroses. The ultrastructural changes described are not specific in themselves; collectively, however — i.e. by the pattern of lesion — they are characteristic and differ from other lethal liver injuries, mainly by the very early necrosis of sinusoidal endothelial cells and the uniformity in degree and extent of the hepatocellular lesions. It is assumed that the most important pathogenetic factor is the formation of relatively large ice crystals within cells and the extracellular area due to recrystallization during thawing. Hypoxemia due to stasis appears to be of minor importance.