Silymarin ameliorates cisplatin-induced hepatotoxicity in rats: histopathological and ultrastructural studies.

The benefit of silymarin, a plant extract with strong antioxidant activity against hepatotoxicity induced by cisplatin in rats was investigated in this study. Cisplatin is one of the most effective chemotherapeutic drugs, yet it alone does not achieve a satisfactory therapeutic outcome and at high doses it can produce undesirable side effects. Five equal-sized groups (18 rats each) of male Sprague Dawley rats [control, vehicle; cisplatin; silymarin 2 h after cisplatin injection; and silymarin 2 h before cisplatin injection] were used. Histopathological and ultrastructural observation of livers were carried out using light and electron microscopy. Results documented that cisplatin produced behavioral, external features animal changes, as well as hazard pathological picture changes in liver where most hepatocytes appeared diminutive with vacuolated cytoplasm, sinusoids dilated and organelle disorganized. These results revealed that cisplatin may be toxic and terminates in complex liver damage. Administrations of silymarin 2 h after cisplatin, significantly increase the body weight returning it to normal, yet it failed in complete protection against the pathological alteration caused by cisplatin. Pretreatment with silymarin 2 h before cisplatin significantly decreased the pathological changes induced by cisplatin and appeared highly protective. These results suggested that silymarin possess protective effects against cisplatin hepatotoxic action in animal models. Since, no significant toxicity of silymarin is reported in human studies, this plant extract can be used as a dietary supplement by patients taking anticancerous medications and might serve as a novel combination agent with cisplatin since it plays a significant role in reducing its toxicity.

Induction of leukaemia in chloramphenicol-treated toads.

Chloramphenicol has been associated with the development of aplastic anaemia. As it is still widely used in Egypt, we studied its effect on 100 Egyptian toads (Bufo regularis) given a dose of chloramphenicol of 5 mg/40 g body weight for 12 weeks. We found it induced numerous, severe ultrastructural changes in almost all types of leukocytes. These changes were similar to those induced by the chemical carcinogen 7,12-dimethylbenz(a)anthracene in 100 toads used as the carcinogen control group, and similar to those in leukocytes reported in humans with leukaemia. We recommend regulations be applied on the use of this antibiotic in countries where it is still widely used.

Ultrastructural criteria that prove the similarities between amphibian and human tumors.

Toads fed with 0.5 mg 7,12-dimethylbenz(a)anthracene twice a week for 12 weeks displayed liver tumors in 27 out of 100 cases. Electron micrographs of liver tumors showed some criteria of malignancy, such as the presence of nuclear pockets, pseudoinclusions, dilatation of the cisternae of rough endoplasmic reticulum and loss of cell junctions. These features are closely similar to those of true malignancy described in humans and other mammals.

The use of toads (Bufo regularis) in a new biological assay for screening chemicals or drugs which induce leukaemia in man.

Injection of Egyptian toads Bufo regularis, with adriamycin subcutaneously in the dorsal lymph sac at a dose level of 0.1 mg/toad, once every 3 weeks for 3 months induced pronounced alterations in the blood cells. These alterations were more or less similar to the criteria reported in human leukaemia. These changes were all comparable to those observed after the treatment of the experimental animals with the chemical carcinogen 7,12-dimethylbenz(a)anthracene. It is speculated that toads (Bufo regularis) can be used as biological test animals for screening chemicals or drugs which induce leukaemia in man.

Pathological-changes of the blood-cells in griseofulvin treated toads.

Griseofulvin is a valuable oral antifungal drug, used extensively in the treatment of superficial fungal infections of man and animals. Electron microscopical studies of peripheral blood of toads force-fed with griseofulvin revealed pronounced alterations of the blood cells more or less similar to the criteria of monocytic leukaemia and were all comparable to those observed after the administration of the carcinogenic chemical 7,12 dimethylbenz(a)anthracene.

The ultrastructure of the neural plexus in the foot musculature of the desert snail Eremina ehrenbergi.

The foot of the desert snail, Eremina ehrenbergi, is supplied by branches of the pedal nerves which enter a coarse-meshed peripheral neural plexus. Light and electron microscopic preparations revealed the presence of ganglionic knots embedded in the foot musculature. In these knots the neural cell bodies are found to be situated on the periphery of neuropile. Cross sections through the neuropile demonstrate the presence of many synaptic junctions of the axo-axonic type. In some axon profiles light and dense synaptic vesicles are observed. Some of the axons which constitute the terminal plexus enter into close apposition with muscle cells and definite areas where synaptic transmission in thought to occur are well observed. On the basis of these results it can be concluded that the neural plexus may be involved in the production of the patterned pedal activity in Eremina ehrenbergi.

A comparative ultrastructural study of the cardiac and skeletal striated muscles of the skink.

Ultrastructural differences between cardiac and striated muscle fibres observed in the ocellated skink (Chalcides ocellatus ocellatus) indicate that functional differences have a structural correlate in the muscle cells. Although the myofibrils of both the cardiac and skeletal muscles displayed the same typical band pattern, differences in mean nuclear diameter and sarcomere length and in the A, I, Z, H, and M bands (discs) were observed. In addition, differences were found in the number, size and distribution of the mitochondria in the two types of muscle fibres. The Golgi complex was indistinguishable in skeletal muscles, but small Golgi vesicles could (with difficulty) be identified in cardiac muscle fibres. Skeletal striated muscle fibres were also found to contain significantly more glycogen granules, smooth sarcoplasm vesicles and heterochromatin than cardiac muscles. Three types of junctional complexes were identified in the cardiac muscles.

Effect of acrylamide toxicity on the ultrastructure of a single cell model Nyctotheroides puytoraci.

Acrylamide (ACR), a widely used vinyl monomer, is well known as a neurotoxin to both laboratory animals and man. The experiment reported has demonstrated that ACR induces ultrastructural changes in the parasitic ciliate Nyctotheroides puytoraci, after injecting the host Bufo regularis with 1 mg ACR per toad (single dose). After 1 week of ACR injection, alterations in both nuclear and cytoplasmic organelles were observed. An increase in the number of cisternae of the Golgi complex was visualized which may be due to its division and hence activation. Acrylamide also appeared to cause fusion of mitochondria in the treated trophozoites. Thus trophozoites of these specimens showed a decreased number of irregularly shaped mitochondria with dense matrix and indistinct outer and inner membranes. Such changes may be attributed to a disturbance in mitochondrial protein synthesis. Also, rough endoplasmic reticulum and lysosomes increased in number. The basal cell bodies were degenerated at some sites.

Effects of split fast neutron doses on the liver cells of albino Swiss mice.

The effect of neutron doses from a D-T compact neutron generator on the liver cells of adult male and female albino Swiss mice was investigated. Fast neutrons (14.5 MeV) were delivered to the whole body in a single dose or in two, four, six or eight equal doses separated by 3-day intervals. The lowest dose, 100 rem, was given for an exposure time of 6 hours and was then steadily raised to 912 rem for an exposure time of 48 hours. During exposure the neutron flux was controlled by the activation foil technique. Animals were killed for testing after each irradiation. Histological examination of the hepatocytes in the light microscope showed marked degenerative changes only after the longer irradiation periods (24, 36 and 48 h). Electron microscopy showed cytological (cytoplasmic and nuclear) changes in the hepatocytes after only 12 hours' irradiation. Densitometric scans of electron micrographs of control and 12 h-irradiated livers indicated that the control hepatocyte interphase nucleus contains approximately 72% heterochromatin, while the irradiated nucleus contains only 64% heterochromatin.

The use of cytoenzymological changes in certain parasitic protozoans for screening the carcinogenicity of chemicals.

Cytoenzymological changes were observed in parasitic ciliates (Nyctotheroides puytoraci) and flagellates (Opalina sudafricana and Protoopalina sp.) after injection of their host, Bufo regularis, with a single dose of 0.5 mg beta-naphthylamine (BNA) per toad. The experiment was carried out during the host's pre-breeding season. Trophozoites of the given parasites were examined 21 days after the injection. The localization of the mitochondria and the relative intensity of succinic dehydrogenase (SDH) and deoxyribonucleic acid (DNA) activity in the control and BNA-treated trophozoites were compared. The results could prove useful for screening the carcinogenicity of chemicals by means of these parasitic protozoans.