Ultrastructural and molecular changes in the developing small intestine of the toad Bufo regularis.

The ontogenetic development of the small intestine of the toad Bufo regularis was investigated using twofold approaches, namely, ultrastructural and molecular. The former has been done using transmission electron microscope and utilizing the developmental stages 42, 50, 55, 60, 63, and 66. The most prominent ultrastructural changes were recorded at stage 60 and were more evident at stage 63. These included the appearance of apoptotic bodies/nuclei within the larval epithelium, the presence of macrophages, swollen mitochondria, distorted rough endoplasmic reticulum, chromatin condensation, and irregular nuclear envelop, and the presence of large vacuoles and lysosomes. The molecular investigation involved examining DNA content and fragmentation. The results showed that the DNA content decreased significantly during the metamorphic stages 60 and 63 compared with both larval (50 and 55) and postmetamorphic (66) stages. The metamorphic stages (60 and 63) displayed extensive DNA laddering compared with stages 50, 55, and 66. The percentage of DNA damage was 0.00%, 12.91%, 57.26%, 45.48%, and 4.43% for the developmental stages 50, 55, 60, 63, and 66, respectively. In conclusion, the recorded remodeling of the small intestine represents a model for clarifying the mechanism whereby cell death and proliferation are controlled.

Successful fibrinolytic treatment of prosthetic heart valve thrombosis using streptokinase.

OBJECTIVES: This study aims to evaluate the clinical outcome of fibrinolytic treatment of prosthetic valve thrombosis (PVT) with 'streptokinase' as a first line treatment for these cases. METHODS: The study group was 20 consecutive patients (10 females) diagnosed with PVT. The protocol for streptokinase administration was either accelerated (intravenous infusion of 0.5 million IU over 30 minutes followed by 0.15 million IU/h) or conventional (intravenous infusion of 0.25 million IU over 30 minutes followed by 0.15 million IU/h). Success of fibrinolytic therapy was defined as complete restoration of valve function in the presence or absence of complications. RESULTS: Eighteen patients (90%) had mitral PVT and two (10%) had aortic PVT. Thrombolytic therapy with streptokinase was successful in all but one case, with a total mortality of four cases (20%). In PVT episodes, before streptokinase therapy, the prosthetic valve areas (in all cases, mitral and aortic positions) were 0.82 ± 0.21, 0.83 ± 0.21, and 0.73 ± 0.18 cm²; and the peak and mean transvalvular gradients were 38.7 ± 16.7 and 25.4 ± 8.7, 34.1 ± 8.8 and 23.2 ± 5.4, and 80.0 ± 14.1 and 45.0 ± 7.1 mmHg, respectively. After streptokinase therapy, the prosthetic valve area and peak and mean transvalvular gradients improved significantly (for all cases, mitral and aortic positions: valve area 2.17 ± 0.58, 2.21 ± 0.61, and 1.85 ± 0.07 cm², peak gradient 18.7 ± 11.0, 16.4 ± 7.7, and 39.0 ± 18.4, and mean gradient 9.6 ± 7.1, 8.2 ± 5.3, and 22.0 ± 11.3 mmHg, respectively; paired t-test, P<0.001 for pre- versus post-streptokinase infusion for all variables). CONCLUSION: Fibrinolytic therapy using streptokinase was an effective therapeutic strategy for the management of PVT and is a reasonable alternative to surgery.

Induction of skin papillomas in the rabbit, Oryctologus cuniculus, by bites of a blood-sucking insect, Cimex lectularius, irradiated by gamma rays.

Bed bugs, Cimex lectularius, irradiated with gamma rays were allowed to suck blood from shaved areas of the skin of rabbits, Oryctolagus cuniculus, 2 times/week for 5 months and then once weekly for another 5 months. This significantly induced the formation of skin papillomas and sweat gland hyperplasia in five out of nine experimental animals. It is speculated that the saliva of the irradiated bugs was activated by gamma rays and was responsible for the induction of skin papillomas. Because bed bugs play a significant role in the transmission of virus, it is also speculated that there is a virus in the saliva of bugs; this virus may be activated by gamma radiation and causes the development of papillomas in the skin.

Effect of vitamin A acid on papillomas induced by irradiated bed bugs in rabbit skin.

The preventive effect of vitamin A acid (13-cis-retinoic acid) on skin papillomas induced in rabbits (Oryctolagus cuniculus) by the bite of bed bugs (Cimex lectularius) pre-irradiated with gamma rays was investigated. Painting the papillomas with an oily 13-cis-retinoic acid suspension twice a week in a dose of 25 mg/kg body weight leads to significant regression of these structures.

A freeze-fracture study on the effect of neopybuthrin on the intestinal epithelial cells of Tilapia nilotica.

Freeze-fracture replicas of the plasma membrane and tight junctions (Tj) of intestinal epithelial cells were studied in Tilapia nilotica fish exposed to the pyrethroid insecticide, neopybuthrin. Exposing fishes to different repeated concentrations of 1/2 LC50 of neopybuthrin caused a significant decrease in the population density of IMPs in P- and E-faces. Tight junctions were also affected by neopybuthrin treatment. They appeared fragmented and discontinued, and their strands were fewer in number as compared with controls. Since the structure and number of Tj are major determinants of epithelial permeability, it is postulated that neopybuthrin treatment may affect the intestinal permeability of T. nilotica.

Aflatoxin-B1 inhibition of spermatogenesis in the toad Bufo regularis.

Aflatoxin-B1 was injected in a dose of 0.01 mg/50 g body weight into the dorsal lymph sac of male toads (Bufo regularis) to evaluate its effect on the testes. After three and six weeks' treatment the diameters of the seminiferous tubules were significantly reduced. Furthermore, spermatogenic cells were almost completely absent. The histological evidence also showed complete suppression of spermatogenesis. It is suggested that one or several AFB1 metabolites may be responsible for suppression of spermatogenesis in the given toads, through inhibition of testicular androgenic activity.

Induction of neoplasms in the Egyptian toad Bufo regularis by gibberellin A3.

Force feeding the Egyptian toads (Bufo regularis) with gibberellin A3 (10 ppm) twice a week for 5 months induced neoplasms in 8 out of 50 (16%) experimental animals. Primary tumours developed in the liver (hepatocellular carcinomas). Two secondary tumours in the kidneys and another 2 in the ovaries of toads developed due to metastases from the hepatocellular carcinomas. The results show that gibberellic acid (gibberellin A3) has a carcinogenic effect in the Egyptian toads.

The induction of neoplastic lesions by aflatoxin-B1 in the Egyptian toad (Bufo regularis).

The carcinogenic activity of aflatoxin-B1, the metabolic product of the mold Aspergillus flavus (a commonly occurring contaminant of groundnuts and other foodstuffs), was tested using the Egyptian toad (Bufo regularis). Injecting the toads with aflatoxin-B1 at a dose level of 0.01 mg/50 g body wt in 1 ml corn oil once a week for 15 weeks induced hepatocellular carcinomas in 19% of the experimental toads. Four toads developed tumors in the kidney due to metastases from the primary hepatocellular carcinomas.

Induction of neoplasms in Egyptian toads Bufo regularis by oil of chenopodium.

Feeding the Egyptian toad Bufo regularis with oil of the chenopodium plant induced hepatocellular carcinomas in 23% of the animals, and metastases of the primary liver tumors appeared in the kidneys of 6 toads. The earliest evidence of tumors appeared after 3 months of treatment. The average latent period of tumor induction was 3.6 +/- 0.4 months. It is speculated that oil of chenopodium may be one of the constituents of Chenopodium ambrosoides which is responsible for tumor induction in the toads B. regularis.

The carcinogenicity of some antimalarial drugs using the Egyptian toad Bufo regularis as a biological test animal.

Feeding Egyptian toads (Bufo regularis) with chloroquine and primaquine separately induced tumor formation in 14% and 19% of the animals, respectively. When chloroquine and primaquine were given in combination, the tumor incidence increased to 23.5%. Chloroquine feeding resulted in tumors located in the liver (lymphosarcomas) and primaquine in tumors in the kidney (histiocytic sarcomas). Toads fed chloroquine plus primaquine developed tumors in the liver, kidney, lung, and urinary bladder, and all the tumors were diagnosed as histiocytic sarcomas. It is speculated that one or more metabolites of chloroquine and primaquine (e.g., quinone) may be responsible for tumor induction in the toads.

Enhancement of hepatic tumors induced by N-nitrosodimethylamine in female toads Bufo regularis by oestrone.

The effect of oestrone on hepatic tumours induced in the female toads Bufo regularis by N-nitrosodimethylamine (DMNA) was evaluated. Injecting the toads with DMNA induced hepatocellular carcinomas in 17% comparable with 23% in toads injected with DMNA plus oestrone. These results show that oestrone insignificantly enhanced the tumour formation. Oestrone alone induced hepatic tumours in only 4 cases and was considered as a weak initiator.

Carcinogenic effect of biscuits made of flour infested with Tribolium castaneum in Bufo regularis.

Biscuits made of flour infested with Tribolium castaneum induced the formation of hepatocellular carcinomas (22%) when force-fed to toads (Bufo regularis) at a dose level of 200 mg/50 g 3 times a week. Maximal time of exposure and observation was 16 weeks. Some metastatic deposits from the primary liver tumours were found in the kidneys. Thus, the carcinogenic potency of the biscuits was almost the same as that of the flour previously reported by the authors indicating that the temperature of the oven in which the biscuits were baked did not alter the carcinogenicity of the infested flour.

Carcinogenicity of flour infested with Tribolium castaneum using the Egyptian toad Bufo regularis as a biological test animal.

Feeding the Egyptian toad Bufo regularis for 14 weeks with flour infested for 1 year with Tribolium castaneum, at a dose level of 200 mg/50 g body weight, induced neoplasms in 22 out of 100 toads. These neoplasms comprise 22 primary hepatocellular carcinomas and 6 tumours in the kidney due to metastases from the primary hepatocellular carcinoma. It is speculated that the carcinogenicity of the flour used in this work is due to quinone derivatives secreted by the defensive glands of T. castaneum.

Carcinogenic effect of gibberellin A3 in Swiss albino mice.

Gibberellin A3 is a plant growth regulator used in many countries, including Egypt, to increase the growth of fruits and vegetables. The carcinogenic effect of gibberellin A3 was investigated in this study with Swiss albino mice. Administration of gibberellin A3 by gavage for 22 months induced a significant increase in their body weights. Tumors were induced in 18% of the males and 36% of the females and were located in the skin of the axillary region (sebaceous adenomas), breast (adenocarcinomas), and lung (adenocarcinomas and secondary metastatic deposits from breast tumors). Bronchocentric granulomas were induced in animals exposed to gibberellin A3 for 14 months. These results indicate that gibberellin A3 was carcinogenic in mice.

Effect of diazinon on freeze-fracture images of microvilli of intestinal epithelial cells of Tilapia nilotica.

The effect of the organophosphate insecticide, diazinon on the intramembranous particles (IMPs) of the microvilli of the intestinal epithelial cells of Tilapia nilotica fish was studied using freeze-fracture technique. Exposing fish to different repeated concentrations of diazinon (1/2LC50) caused a significant decrease in population density of IMPs in P- and E-faces. IMPs of microvilli found in intestinal epithelial cells are thought to represent many kinds of proteins including enzymes. In the present work, it is suggested that diazinon induced a reduction in enzymatic content of the membrane which was accompanied by a decrease in IMPs density of the microvilli.

Preventive action of garlic on aflatoxin B1-induced carcinogenesis in the toad Bufo regularis.

The action of fresh minced garlic and garlic oil on aflatoxin B1- (AFB1) induced carcinogenesis in the toad Bufo regularis was studied. Feeding toads with AFB1 induced tumors in 19% of the animals. Animals given AFB1 together with fresh garlic or garlic oil showed a significant reduction in tumor incidence. The tumor incidences were 3% and 9% in animals given AFB1 plus garlic and AFB1 plus garlic oil, respectively. In all three groups, the tumors were located in the liver (hepatocellular carcinomas), in addition to the kidney in animals treated with AFB1 alone and together with garlic. The kidney tumors were diagnosed as metastatic deposits from the primary liver tumors. It is speculated that one or more constituents of garlic may be responsible for inhibition of AFB1-induced carcinogenesis in B. regularis.

Flour infested with Tribolium castaneum, biscuits made of this flour, and 1,4-benzoquinone induce neoplastic lesions in Swiss albino mice.

The carcinogenic effect of flour infested with beetles (Tribolium castaneum), biscuits made of this flour, and 1,4-benzoquinone (a quinoid secretion of this beetle) was investigated using Swiss albino mice. Force feeding flour infested with T. castaneum induced liver and spleen tumors (lympholeukemia) in 35.2% of the animals. The tumor incidence was 29% in mice force fed biscuits made of infested flour, and the tumors were located in the liver (lympholeukemia) and breast (adenocarcinoma type A). In animals fed 1,4-benzoquinone, the tumor incidence was 33.6%, and the tumors were located in the liver and spleen (lympholeukemia). It is speculated that 1,4-benzoquinone, alone or in combination with other quinoid secretions of the beetles present in the flour, may be responsible for tumor induction in the organs of mice.

Effect of adriamycin on the morphology of the erythrocytes and blood parameters of the toad Bufo regularis.

The effect of the anticancer drug adriamycin on the morphology of the erythrocytes as well as some blood parameters were studied in the Egyptian toad Bufo regularis. Injecting the toads subcutaneously in the dorsal lymph sac with adriamycin at a dose level of 2 mg/kg body weight once every three weeks for 12 weeks induced the formation of abnormalities in the cytoplasm and nuclei of the erythrocytes. Its administration also caused severe anaemia, since the number of red blood corpuscles, haemoglobin content and haematocrit values were obviously decreased throughout the whole experimental period. The total leucocytic count was also diminished. On the other hand, the erythrocyte sedimentation rate was increased all over the experiment.

Carcinogenicity testing of black pepper (Piper nigrum) using the Egyptian toad (Bufo regularis) as a quick biological test animal.

Milled black pepper (Piper nigrum) force-fed to Egyptian toads as a suspension in amphibian saline or injected subcutaneously in the dorsal lymph sac as an ethanol extract, induced primary tumours in the liver and secondary tumours in other organs (kidney and spleen). When applied to the skin of experimental animals as an ethanol extract, black pepper induced primary tumours in the liver and secondary tumours in the ileum and stomach. Tumours of the liver were diagnosed as hepatocellular carcinomas and those of the other organs as metastases of the primary liver tumours. It is speculated that one or more constituents of black pepper may be responsible for tumour induction in the organs of the Egyptian toad Bufo regularis.

Adriamycin-induced neoplastic lesions in the Egyptian toad Bufo regularis.

Injecting adult toads (Bufo regularis) subcutaneously in the dorsal lymph sac with adriamycin at a dose of 2 mg/kg body weight, once every 3 weeks for 20 weeks, induced hepatocellular carcinomas in 20 out of 100 animals. Metastases of the primary liver tumors appeared in the kidneys of 7 toads.