Effect of hydrazine sulfate on glucose-regulating enzymes in the normal and cancerous rat.

Glucokinase, hexokinase, fructose 1,6-bisphosphatase and phosphoenolpyruvate carboxykinase specific activities were monitored in liver cytosol from rats that had been made cancerous with 1,2-dimethylhydrazine and then treated with hydrazine sulfate. The presence of intestinal cancer, specifically, was confirmed by laparotomy and by histological analysis. Sustained changes in hexokinase and glucokinase specific activities were first evident during the latter weeks that the carcinogen was being administered. Upon subsequent treatment with hydrazine sulfate, glucokinase activity further decreased, and liver cytosolic phosphoenolpyruvate carboxykinase activity increased. Liver cytosolic hexokinase and fructose 1,6-bisphosphatase specific activities were not appreciably affected by the hydrazine sulfate treatment. These results indicate that hydrazine sulfate may influence carbohydrate metabolism at the level of selected liver enzymes not only with respect to gluconeogenesis, but also in terms of glucose uptake.

Development of normal tissue damage in the rat subsequent to thoracic irradiation and prior treatment with cancer chemotherapeutic agents.

The effect of combined modalities (radiotherapy-chemotherapy) on the development of long-term normal tissue damage was investigated in rats. Animals received single I.P. injections of Hank's balanced saline solution, adriamycin (ADR, 1.0 mg/kg), bleomycin (BLM, 10 units/kg), or dihydroxyanthraquinone (DHAQ, 3.0 mg/kg); and/or irradiation of the chest with 25 MV x-rays (12 Gy) at 0, 43, 93, or 199 days after drug treatment. Only animals treated with DHAQ displayed appreciable toxicity, with more animals dying at less than 200 days when radiation was added at 0 or 43 days. Although animals treated with BLM or radiation exhibited evidence of lung damage (histologically by 199 days and radiographically by 300 days), their survival was not compromised. The simultaneous administration of x-ray and BLM produced enhanced effects as compared to either agent alone. These results demonstrate an enhancement of normal tissue damage by combined treatment with radiation and chemotherapeutic agents, not only for acute toxicity but also for long-term effects. This damage was ultimately expressed as alteration of lung structure (histologically and radiographically) in the case of BLM, and as animal lethality in the case of DHAQ. In addition, there was a reduction in the degree of enhancement observed as a function of the separation in time between treatment with chemotherapeutic agents and subsequent irradiation. These factors should be considered when combined modality therapy is used for treatment of cancer in the thoracic region.

Time course of cadmium-induced ultrastructural changes in rat liver.

Ultrastructural changes in rat liver were studied 1, 2, 4, 6, 8, and 10 hr after administration of a single, high dose of Cd (3.9 mg Cd/kg, iv) or after repeated administration of a lower dose (0.5 mg Cd/kg, sc, 6 days/week for 6 months). These dosing regimens have been previously shown to produce hepatotoxicity and result in large accumulations of Cd in liver. In addition to light and electron microscopy, plasma enzyme activities indicative of liver injury, namely alanine (ALT) and aspartate (AST) aminotransferase, were determined at the aforementioned times. One hour after an acute dose of Cd, electron photomicrographs of liver showed dilation of the rough endoplasmic reticulum with concomitant loss of membrane-associated ribosomes, nucleolar condensation, and an increase in the number of perichromatin granules. At later times (4 and 6 hr), ultrastructural changes included mitochondrial swelling associated with matrical inclusions, further dilation and vesiculation of rough endoplasmic reticulum, and presence of a fibrillar material within cytoplasm. In contrast to changes observed after single administration of Cd, the predominant hepatic lesions in rats injected repeatedly with the metal over 6 months were interstitial fibrosis, nuclear enlargement, and an increase in number and predominance of nucleoli. Ultrastructural evidence of nuclear alterations included condensation of nucleoli and an increase in the number of perichromatin granules. These results indicate that Cd interferes with hepatic protein synthesis early after injection of a large dose, and that further degenerative changes occur later and possibly in response to protein inhibition. Although severe degenerative changes in liver were not evident in rats chronically exposed to the metal, Cd-induced changes in nuclei and nucleoli also indicate the likelihood of altered protein synthesis.

Ultrastructural evidence of cardiac damage resulting from thoracic irradiation and anthracyclines in the rat.

The effects of radiation combined with Adriamycin (ADR) or Dihydroxyanthraquinone (DHAQ, NSC 279836) on the induction of cardiomyopathy in the rat were investigated using electron microscopy. Rats were treated with ADR or DHAQ at 2.5, 5.0, or 10 mg/kg ip; thoracic irradiation at 12, 15, 18, 21, or 24 Gy of 25 MV X rays; or a combination of either drug at 5.0 mg/kg plus 15 Gy X rays. Survival times were observed to be linear, inverse functions of the dose of drug or radiation received. Combinations of ADR plus radiation produced an increased lethality while the combination of DHAQ and radiation produced similar lethality as DHAQ alone. Even for treatments that resulted in animal lethality, there was little histological evidence of abnormality observed in heart tissues by light microscopy. On the other hand, electron microscopic examination of cardiac tissues demonstrated dramatic decreases in mitochondrial number and destruction of mitochondrial structure. The treatments could be arranged in order of increasing severity of the damage produced as follows: 5 mg/kg ADR, 15 Gy X ray, 5 mg/kg DHAQ, 5 mg/kg ADR + 15 Gy X ray, 24 Gy X ray, and 5 mg/kg DHAQ + 15 Gy X ray. In several cases, mitochondrial abnormalities were sufficient so as to allow cardiomyopathy to be cited as the cause of death. These results indicate that electron microscopy can be used to document cellular changes that may only be functionally expressed as long-term normal tissue damage or animal lethality. The finding that DHAQ can produce significant cardiotoxicity, and that this cardiotoxicity is enhanced by concomitant thoracic irradiation, suggest caution while this drug is being investigated for clinical use.

Angiotensin-I-converting enzyme in cancer patients.

Serum levels of angiotensin-I-converting enzyme (ACE) were assayed before, during, and after radiation therapy in 209 patients receiving treatment for neoplastic disease. Daily fluctuations in the measured ACE levels were minimized by comparing all patient values to that of a simultaneously run sample from a standard source of serum obtained by pooling sera from young, healthy volunteers. Most of the patients tested presented with a normal to low ACE level, with the mean value for all patients being 70% of the standard value. More patients with primary lung cancer displayed values that were low (107 of 120) than did patients with disease outside the lung (44 of 78), this difference being statistically significant at p less than 0.001. In addition, more patients with lung cancer had values less than 70% of the standard than did patients with disease outside the lungs. These initial results suggest that monitoring of serum ACE levels may be useful in the management of patients with malignant disease in the lung.

Effect of dihydroxyanthraquinone (NSC 279836) and thoracic irradiation on long-term survival of rats.

Dihydroxyanthraquinone (DHAQ; NSC 279836) is a recently synthesized compound that is structurally similar to Adriamycin and produces greater antitumor effects in murine model systems. We compared DHAQ to Adriamycin in rats, with and without irradiation of the chest at various intervals after drug treatment. A single injection of Adriamycin (1 mg/kg i.p.) had little effect on animal survival, even if combined with radiation (12 Gy 25 MV X-rays), greater than 90% being alive at 1 year. A single injection of DHAQ (3 mg/kg i.p.) was equally uneffective up to 200 days after treatment (survival, greater than 90%). However, between 200 and 370 days after treatment, all animals died, producing a median survival time of 280 days. Further, when DHAQ was combined with radiation, there was an increase in animal deaths between Days 300 and 200. For animals irradiated on Days 0, 43, and 93 after DHAQ treatment, only 50, 75, and 80%, respectively, survived to Day 200. All animals that survived past Day 200 subsequently died by 1 year, displaying the same kinetics of lethality as those animals that had received DHAQ only. A repeat experiment using DHAQ at 1 mg/kg produced similar results. Based on these findings, we conclude that DHAQ produces a long-term (greater than 200 days) toxicity in rats that is not detectable by short-duration toxicity screening. In addition, radiation enhances short-term (less than 200 days) lethality, with the degree of enhancement decreasing as the interval between drug and radiation is increased.

Tumors in male rats fed ethyl chlorophenoxyisobutyrate, a hypolipidemic drug.

Clofibrate (ethyl chlorophenoxyisobutyrate, Atromid-S), because it contains a chlorinated phenoxy moiety and is the most commonly used hypolipidemic drug in the United States and Europe, was fed at a concentration of 0.5% in the diet of 25 male F344 rats for 72 to 97 weeks, and the animals were inspected for tumors up to a maximum of 129 weeks. Between 72 and 129 weeks, there were 10 rats with a total of 16 tumors. These included 4 hepatocellular carcinomas, an adenocarcinoma of the glandular stomach, papillary carcinoma of the urinary bladder, acinar cell carcinoma of the pancreas, lymphosarcoma involving pancreas, acinar cell adenomas of the pancreas, renal carcinoma, and sarcomas of the lung and parotid gland. Although the number of experimental animals was small, none of these tumors were present in 25 controls, and systematic examination of available literature dealing with spontaneous tumors in several thousand rats indicated that the tumors in clofibrate-fed rats were not spontaneous. A number of the tumors were transplanted through several generations. Clofibrate, like two other hypolipidemic drugs that are carcinogenic, causes peroxisome proliferation. It is speculated that some drugs that cause peroxisome proliferation may represent a new class of chemical carcinogens and that there may be a relationship between peroxisome proliferation and malignant transformation.

Unusual responses of rat hepatic and renal peroxisomes to RMI 14, 514, a new hypolipidemic agent.

RMI 14, 514 ([5-tetradecycloxy]-2-furancarboxylic acid) represents a new class of hypolipidemic agents which cause unusual ultrastructural changes in liver of male rats and in selected peroxisomal enzymes in liver and kidney of both sexes. Among the principal ultrastructural changes in peroxisomes of male rat liver were (a) cavitation and compartmentalization of the matrix, often giving the appearance of a peroxisome-within-a-peroxisome, and (b) narrow, dense extensions of canaliculi or cisterns from the periphery of the peroxisome, forming partial circlets or surrounding irregular areas of cytoplasm. The unusual enzyme responses were (a) elevation of catalase activity in liver and kidney in female rats, (b) increased activity of three hydrogen peroxide-producing oxidases (urate oxidase, L-alpha-hydroxy acid oxidase, and D-amino acid oxidase) in the liver of both sexes, and (c) elevation of activity of the last two oxidases in male kidney. The peculiar ultrastructural changes in liver peroxisomes combined with the responses of selected peroxisomal enzymes represent unusual modulations or adaptations of these organelles to a hypolipidemic agent, the effects of which have not been reported extensively.

Induction of liver tumors by aflatoxin B1 in the tree shrew (Tupaia glis), a nonhuman primate.

The epidemiological studies suggest that aflatoxins, the toxic metabolites of the ubiquitous mold Aspergillus flavus, may play a significant role in the evolution of hepatocellular carcinoma in man in certain geographic areas of the world. To ascertain their carcinogenicity in nonhuman primates, we have administered highly purified aflatoxin B1, intermittently in the diet at 2 ppm, to 10 female and 8 male tree shrews. The tree shrew (Tupaia glis) is a nonhuman primate occurring throughout Southeast Asia which can be reared easily in captivity. Of 12 animals that survived, 6 of 6 female (100%) and 3 of 6 male (50%) tree shrews developed hepatocellular carcinomas between 74 and 172 weeks after the beginning of the experiment. None of the 8 control animals developed liver cancers. The estimated total amount of aflatoxin B1 consumed by these animals ranged from 24 to 66 mg. The development of liver tumors did not follow a specific pattern; considerable variation in hepatocellular responses to aflatoxin B1 was noted in these animals. In 2 tree shrews, the liver tumors were associated with severe post necrotic scarring; in the other 7 tumor-bearing livers, only mild to moderate portal fibrosis was encountered. This individual variation in hepatocellular response and in the amount of aflatoxin B1 required to induce hepatocellular carcinomas is attributed to inherent differences in the susceptibility within a given species of outbred animals and suggests extreme caution in proposing the "permissible" or "safe" levels of contamination of carcinogens in the food-stuffs.

Pathology of the liver in Reye's syndrome.

A study of six patients with Reye's syndrome indicated that, by light microscopy, inflammation and necrosis of liver cells are especially prominent in fatal cases. Contrary to previous reports, electron microscopic examination indicated that, aside from loss of matrix dense granules, alterations in mitochondrial structure were minimal or absent. Although an increase in the number of liver cell microbodies has been reported, no such increase was apparent in the present study. The most unusual ultrastructural change in microbodies in the present study was the appearance of noncrystalline cores in the matrix. No ultrastructural features served to distinguish patients who died from those who survived. Although derangement of mitochondrial function may be important in the pathogenesis of Reye's syndrome, such derangement is not necessary reflected in the ultrastructure of mitochondria.

Pancreatic necrosis and regeneration induced by 4-hydroxyaminoquinoline-1-oxide in the guinea pig.

A single intravenous injection of 4-hydroxyaminoquinoline-1-oxide, in a dose of 22.5 mg. per kg., induced marked necrosis of exocrine pancreas in inbred strain 13 guinea pigs within 48 hours. The pancreatic acinar cell necrosis was dose-dependent and was associated with a significantly elevated serum amylase level and reduction in amylase activity in the pancreatic tissue. The maximal necrotic changes in the exocrine pancreas were observed at 48 hours. After the necrotic phase, a striking regenerative response of pancreatic acinar tissue ensued. 3-H-thymidine autoradiographic studies revealed a labeling index of 28 per cent cells in several pancreatic lobules 66 hours after 4-hydroxyaminoquinoline-1-oxide injection. The acinar cell repair, as well as formation of the new acini in many pancreatic lobules, was complete by 84 hours. In some pancreatic lobules, pseudoacinar or ductular transformation was noted. The regenerative response in pancreatic acinar tissue and ductal epithelium induced by 4-hydroxyaminoquinolone-1-oxide in the guinea pig appeared to be severalfold higher than that noted during ethionine regeneration.

Nafenopin-induced hepatic microbody (peroxisome) proliferation and catalase synthesis in rats and mice. Absence of sex difference in response.

Nafenopin (2-methyl-2[p-(1,2,3,4-tetrahydro-1-naphthyl)phenoxy]-propionic acid; Su-13437), a potent hypolipidemic compound, was administered in varying concentrations in ground Purina Chow to male and female rats, wild type (Cs(a) strain) mice and acatalasemic (Cs(b) strain) mice to determine the hepatic microbody proliferative and catalase-inducing effects. In all groups of animals, administration of nafenopin at dietary levels of 0.125% and 0.25% produced a significant and sustained increase in the number of peroxisomes. The hepatic microbody proliferation in both male and female rats and wild type Cs(a) strain mice treated with nafenopin was of the same magnitude and was associated with a two-fold increase in catalase activity and in the concentration of catalase protein. The increase in microbody population in acatalasemic mice, although not accompanied by increase in catalase activity, was associated with a twofold increase in the amount of catalase protein. The absence of sex difference in microbody proliferative response in nafenopin-treated rats and wild type mice is of particular significance, since ethyl-alpha-p-chlorophenoxyisobutyrate (CPIB)-induced microbody proliferation and increase in catalase activity occurred only in males. Nafenopin can, therefore, be used as an inducer of microbody proliferation and of catalase synthesis in both sexes of rats and mice. The serum glycerol-glycerides were markedly lowered in all the animals given nafenopin, which paralleled the increase in liver catalase. All the above effects of nafenopin were fully reversed when the drug was withdrawn from the diet of male rats. During reversal, several microbody nucleoids were seen free in the hyaloplasm or in the dilated endoplasmic reticulum channels resulting from a rapid reduction in microbody matrix proteins after the withdrawal of nafenopin from the diet. Because of microbody proliferation and catalase induction with increasing number of hypolipidemic compounds, additional studies are necessary to determine the interrelationships of microbody proliferation, catalase induction, and hypolipidemia.