Salah A. Sheweita

Relationship between schistosomiasis and bladder cancer.

SUMMARY Carcinoma of the urinary bladder is the most common malignancy in the Middle East and parts of Africa where schistosomiasis is a widespread problem. Much evidence supports the association between schistosomiasis and bladder cancer: this includes the geographical correlation between the two conditions, the distinctive patterns of gender and age at diagnosis, the clinicopathological identity of schistosome-associated bladder cancer, and extensive evidence in experimentally infected animals. Multiple factors have been suggested as causative agents in schistosome-associated bladder carcinogenesis. Of these, N-nitroso compounds appear to be of particular importance since they were found at high levels in the urine of patients with schistosomiasis-associated bladder cancer. Various strains of bacteria that can mediate nitrosation reactions leading to the formation of N-nitrosamines have been identified in the urine of subjects with schistosomiasis at higher intensities of infection than in normal subjects. In experimental schistosomiasis, the activities of carcinogen-metabolizing enzymes are increased soon after infection but are reduced again during the later chronic stages of the disease. Not only could this prolong the period of exposure to activated N-nitrosamines, but also inflammatory cells, sitmulated as a result of the infection, may induce the endogenous synthesis of N-nitrosamines as well as generating oxygen radicals. Higher than normal levels of host cell DNA damage are therefore anticipated, and they have indeed been observed in the case of alkylation damage, together with an inefficiency in the capacity of relevant enzymes to repair this damaged DNA. In experimental schistosomiasis, it was also found that endogenous levels of host cell DNA damage were related to the intensity of infection. All of these factors could contribute to an increased risk of bladder cancer in patients with schistosomiasis, and in particular, the gene changes observed may have potential for use as biomarkers in the early detection of bladder cancer that may assist in alleviating the problem.

Carbon tetrachloride-induced changes in the activity of phase II drug-metabolizing enzyme in the liver of male rats : role of antioxidants

Glutathione S-transferases and glutathione play an important role in the detoxification of most toxic agents. In the present study, the protective effects of some antioxidants (L-ascorbic acid (AA), vitamin E (VE) or garlic) on carbon tetrachloride-induced changes in the activity of alanine amino transferase (ALT), aspartate amino transferase (AST), glutathione S-transferase (GST), and the level of glutathione (GSH) and thiobarbituric acid reactive substances (TBARS) were studied. The activities of ALT, and AST were assayed in plasma, whereas the activity of GST and the levels of GSH and TBARS were determined in the livers of rats. The current study included two experiments. In the first experiment, animals received single oral dose of CCl4 (400 mg/kg body weight) after administration of AA (100 mg/kg b.w.), VE (100 mg/kg b.w.) or garlic (800 mg/kg b.w.) as single oral doses. In the second experiment, rats received repeated oral doses of antioxidants for 12 consecutive days followed by a single oral dose of CCl4 on the 13th day and killed after that by 24 h. Treatment of male rats with CCl4 significantly increased the activity of ALT and AST in plasma, and the levels of both GSH and TBARS in the liver. On the other hand, CCl4 inhibited the activity of GST after single dose treatment. Single-dose treatments of rats with AA, VE or garlic prior to the administration of CCl4 could not restore the alterations in the activity of ALT and AST caused by CCl4 to the normal control level. However, repeated dose treatments with these agents restored such alterations to the normal level. We observed that VE is more effective than AA and garlic in restoring the inhibition of GST activity caused by CCl4 to the normal level after single dose treatments. On the other hand, AA and VE are more effective than garlic in restoring the induced TBARS level caused by CCl4 to the normal control level after repeated dose treatments. It has been observed that the tested antioxidants were able to antagonize the toxic effects of CCl4, and such counteracting effects were more pronounced when they were administered as repeated doses prior to administration of CCl4.

Biochemical study on the effects of some Egyptian herbs in alloxan-induced diabetic rats

The present study was carried out to investigate the effects of Lupinus albus, L. (Lupinus termis), family L. leguminosae, Cymbopogon proximus, (Halfa barr), family Gramineae, and Zygophyllum coccineum L. (Kammun quaramany), family L. Zygophyllacae on biochemical parameters in alloxan-induced diabetic rats. A dose of 1.5 ml of aqueous suspension of each herb/100 g body weight (equivalent to 75 mg/100 g b.wt.) was orally administered daily to alloxan-diabetic rats for 4 weeks. The levels of glucose, urea, creatinine and bilirubin were significantly (P<0.05) increased in plasma of alloxan-diabetic rats compared with the control group. In contrast, total protein and albumin were significantly decreased by 25 and 46%, respectively, versus control. Treatment of the diabetic rats with repeated doses of any one of the three herb suspensions could restore the changes of the above parameters to their normal levels after 4 weeks of treatment. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (AlP) activities were significantly (P<0.05) increased in the plasma of alloxan-diabetic rats. However, acetylcholinesterase activity was significantly (P<0.05) decreased in the plasma compared with the control group, whereas, such activity did not change in brain. The activities of AST, ALT and LDH were significantly (P<0.05) decreased in the liver of alloxan-diabetic rats by 58, 21 and 40%, respectively, and such activities increased in testes by 39, 26 and 26%, respectively, compared with the control group. Also, brain LDH was significantly (P<0.05) increased. Treatment of the diabetic rats with the aqueous suspension of the tested herbs restored the activities of the above enzymes to their normal level in plasma, liver and testes. The present results showed that the herb suspensions exerted antihyperglycemic effects and consequently may alleviate liver and renal damage caused by alloxan-induced diabetes.

Carbon tetrachloride changes the activity of cytochrome P450 system in the liver of male rats: role of antioxidants

The cytochrome P-450 enzymes are responsible for the oxidation of xenobiotic chemicals including drugs, pesticides, and carcinogens. These enzymes include cytochrome P450, cytochrome b(5), arylhydrocarbon (benzo[a]pyrene) hydroxylase (AHH), NADPH-cytochrome C reductase and dimethylnitrosamine N-demethylase I (DMN-dI). Changes in the activities of the above mentioned enzymes were studied in the liver microsomes of rats treated with antioxidants (ascorbic acid (AA), DL-a-tocopherol (vitamin E, VE), garlic) as single- and repeated doses prior to the administration of a single dose of CCl(4). Pretreatment of rats with single doses of AA, VE, or garlic prior to the administration of CCl(4) was found to decrease the hepatic content of cytochrome P450, and the activities of DMN-dI and AHH. On the other hand, these treatments induced the hepatic content of cytochrome b(5) and the activity of NADPH-cytochrome c reductase. Pretreatment of rats with repeated doses of AA, VE, or garlic for 12 consecutive days prior to the administration of CCl(4) as single dose was potentially decreased the activities of cytochrome P450, DMN-dI and NADPH-cytochrome c reductase. Also, the activity of AHH decreased after treatments of rats with repeated doses of garlic prior to the administration of CCl(4). It was noted that repeated doses of antioxidants are more effective than single dose in decreasing the activity of drug-metabolizing enzymes. It is concluded that repeated doses of antioxidants or garlic could reduce the toxic effects exerted by CCl(4) upon the liver, and probably other organs, through inhibition of cytochrome P450 system that activates CCl(4) into its active metabolite, trichloromethyl radical. Moreover, inhibition of cytochrome P450 system could also reduce the toxic and carcinogenic effects of chemical carcinogens such as benzo(a)pyrene and dimethylnitrosamine. The mechanisms of antioxidant protection were discussed in the text.

Effect of some hypoglycemic herbs on the activity of phase I and II drug-metabolizing enzymes in alloxan-induced diabetic rats

Polycyclic aromatic hydrocarbons (PAHs) and N-nitrosamines (NNA) are mainly activated by cytochrome P450s, and their associated enzyme activities such as aryl hydrocarbon (benzo(a)pyrene) hydroxylase (AHH), N-nitrosdimethylamine N-demethylase I (NDMA-dI), NADPH-cytochrome C reductase, and detoxified by glutathione S-transferase (GST) and glutathione (GSH). The present study shows the influence of Cymbopogon proximus (Halfa barr), Zygophyllum coccineum L. (Kammun quaramany), Lupinus albus (Termis) as herbs capable of inducing hypoglycemia on the activity of the above mentioned enzymes in the liver of diabetic rats. Alloxan was administered as a single dose (120 mg/kg body weight) to induce diabetes and the herbs were administered to diabetic rats as repeated doses for 4 weeks. Alloxan-induced diabetes significantly increased the blood glucose level by 93% compared to the control level. On the other hand, repeated-dose treatments of diabetic rats with Cymbopogon proximus and Lupinus albus are more effective than Zygophyllum coccineum in restoring the elevated blood glucose level to the normal level. Alloxan treatment increased the hepatic activity of cytochrome P450, NADPH-cytochrome C reductase, AHH, NDMA-dI, GST and GSH by 112, 122, 82, 99, 64 and 26%, respectively. These herbs decreased the activity of above mentioned enzymes in the liver of diabetic rats compared to alloxan-treated rats. We conclude that alloxan increased the activity of cytochrome P450 system and that such herbs reduced these activities. The toxic effects of PAHs (e.g. benzo(a)pyrene) and NNA (e.g. N-nitrosdimethylamine) could be increased in the liver of diabetic rats through induction of their corresponding bioactivating enzymes. On the other hand, hypoglycemic herbs could alleviate the deleterious effects of these carcinogens in the liver of diabetic rats since these herbs reduced the hepatic content of cytochrome P450 and other associated enzyme activities compared to the diabetic group. Such alterations in the activity of phase I and II drug-metabolizing enzymes should be considered when therapeutic drugs are administered to diabetic patients since most of drugs are metabolized mainly by the cytochrome P450 system.

Development of immunization trials against Pasteurella multocida

Pasteurellosis is one of the most important respiratory diseases facing economically valuable farm animals such as poultry, rabbit, cattle, goats and pigs. It causes severe economic loss due to its symptoms that range from primary local infection to fatal septicemia. Pasteurella multocida is the responsible pathogen for this contagious disease. Chemotherapeutic treatment of Pasteurella is expensive, lengthy, and ineffective due to the increasing antibiotics resistance of the bacterium, as well as its toxicity to human consumers. Though, biosecurity measures played a role in diminishing the spread of the pathogen, the immunization methods were always the most potent preventive measures. Since the early 1950s, several trials for constructing and formulating effective vaccines were followed. This up-to-date review classifies and documents such trials. A section is devoted to discussing each group benefits and defects.

N-nitrosamines and their effects on the level of glutathione, glutathione reductase and glutathione S-transferase activities in the liver of male mice

The present study investigates the influence of different chemical structure of N-nitroso compounds on the hepatic level of reduced glutathione (GSH), glutathione reductase (GSH-R) and glutathione S-transferase (GST) activities in the liver of male Balb/C mice after treatment with 20 mg/kg body weight of each compound for 1 h as a single dose. The level of reduced glutathione decreased significantly between 37 and 70% after the treatment of male mice with ethylbutylnitrosamine (-37%), diphenylnitrosamine (-50%), propylbutylnitrosamine (-52%), diethylnitrosamine (-54%), ethylmethylnitrosamine (-55%), and dibutylnitrosamine (-70%), whereas, methylpropylnitrosamine increased the level of GSH by 71%. All the N-nitrosamine compounds tested increased the activity of glutathione reductase except ethylmethylnitrosamine had no effect. The activity of glutathione S-transferase activity was inhibited after treatment of the male mice with diphenylnitrosamine (-60%), dibutylnitrosamine (-60%), and methylpropylnitrosamine (-81%), while, ethylmethylnitrosamine and ethylbutylnitrosamine had no effect on such activity. On the other hand, diethylnitrosamine increased the activity of glutathione S-transferase by 50%. It can be postulated from this study that the chemical structure of N-nitrosamines plays a significant role in the alteration of GSH level and GSH metabolizing enzymes, since the substitution of different groups on the nitroso group was found to be capable of causing an alteration in such activities.

ALTERATIONS OF LIPID PROFILE IN PLASMA AND LIVER OF DIABETIC RATS: EFFECT OF HYPOGLYCEMIC HERBS

The effect of three species of hypoglycemic herbs (Termis, Halfa barr, or Kammun Quaramany) on the lipid profile was investigated in plasma and liver tissues of diabetic and herbs-treated diabetic rats. This profile includes total lipids (TL), triglycerides (TG), cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL). A dose of 1.5 ml of aqueous suspension of each herb/100 g body weight (equivalent to 75 mg/100 g body weight) was orally administered daily to alloxan-diabetic rats for four weeks. The present study showed 2-fold increase (p<0.05) in the plasma glucose level of diabetic rats, which received alloxan as a single dose of 120 mg/kg body weight, relative to the mean value of control group. This elevated glucose level was restored to its normal level after treatment with any one of the three herbs. Furthermore, the levels of TL, TG, cholesterol, LDL and VLDL were significantly (p<0.05) increased in the plasma and the liver tissues of diabetic rats compared to the control group, whereas HDL level was significantly (p<0.05) decreased. The plasma levels of all above parameters were normalized after treatment of the diabetic rats with Kammun Quaramany. Treatment of diabetic rats with Termis normalized TG, cholesterol, LDL and VLDL levels, but Halfa barr restored the induced levels of plasma cholesterol, LDL and HDL to their normal levels. On the other hand, treatment with any of the three herbal suspensions could not restore the concentrations of the all tested parameters in the liver. These data demonstrated that the glycemic control of any of the three herbal suspensions was associated with their hypocholesterolemic effects on the hypercholesterolemia of the alloxan-induced diabetic rats. Moreover, the Kammun Quaramany showed the most potent effect.

Changes in the expression of cytochrome P450 2E1 and the activity of carcinogen-metabolizing enzymes in Schistosoma haematobium-infected human bladder tissues

The bioactivation of N-nitrosamines and polycyclic aromatic hydrocarbons (PAHs) is mediated primarily by the mixed-function oxidase system, which includes dimethylnitrosamine N-demethylase I, arylhydrocarbon [benzo(a)pyerne] hydroxylase, cytochrome P450, cytochrome b(5), and ethoxycoumarin deethylase. Most of carcinogens and xenobiotics are conjugated and detoxified by phase II drug-metabolizing enzymes such as glutathione S-transferase. The present study showed the influence of Schistosoma haematobium on the activity of the above-mentioned enzymes in 13 schistosome-infected human bladder tissues compared with those of 15 schistosome-free samples. The contents of cytochrome P450 and cytochrome b(5) were increased in the bladder tissues by 48 and 69%, respectively. Moreover, the activities of dimethylnitrosamine N-demethylase I and arylhydrocarbon hydroxylase, ethoxycoumarin O-deethylase, ethoxyresourfin O-deethylase, and pentoxyresorufin O-pentoxyresorufin were increased by 75, 159, 49, 63 and 44%, respectively. The signal intensity for cytochrome P450 2E1 was greatly increased over the control. Also, the activity of glutathione S-transferase was increased by 89%. On the other hand, the activity of glutathione reductase and the level of reduced glutathione were decreased by 40 and 57%, respectively. Interestingly, the level of free radical, thiobarbituric acid reactive substance, was increased in the schistosome-infected human bladder tissues by 125%. The present study clearly demonstrated that S. haematobium changes the activity of carcinogen-metabolizing enzymes. We conclude that S. haematobium could enhance the carcinogenicity of polycyclic aromatic hydrocarbons (e.g. benzo(a)pyrene) and N-nitrosamines (e.g. dimethylnitrosamine) through induction of their corresponding bioactivating enzymes in human bladder tissues.

Superiority of aromatase inhibitor and cyclooxygenase-2 inhibitor combined delivery: Hyaluronate-targeted versus PEGylated protamine nanocapsules for breast cancer therapy

Despite several reports have revealed the beneficial effect of co-administration of COX-2 inhibitors with aromatase inhibitors in managing postmenopausal breast cancer; no nanocarriers for such combined delivery have been developed till now. Therefore, protamine nanocapsules (PMN-NCs) have been developed to co-deliver letrozole (LTZ) that inhibits aromatase-mediated estrogen biosynthesis and celecoxib (CXB) that synergistically inhibits aromatase expression. Inspired by the CD44-mediated tumor targeting ability of hyaluronate (HA), we developed HA-coated PMN-NCs (HA-NCs) via electrostatic layer-by-layer assembly. Moreover, multi-compartmental PEGylated phospholipid-CXB complex bilayer enveloping PMN-NCs (PEG-NCs) were designed for conferring biphasic CXB release from the phospholipid corona and oily core as well as enabling passive-targeting. The NCs demonstrated excellent stability, prolonged circulation and could be scaled up with the aid of spray-drying technology. Hemolysis, serum stability and cytotoxicity studies confirmed the superiority of combined LTZ-CXB nano-delivery. Mechanistically, the NCs especially HA-NCs and PEG-NCs demonstrated precious anti-tumor effects in vivo revealed as reduction in the tumor volume and aromatase level, increased apoptosis, as well as inhibition of VEGF, NF-κB and TNF-α augmented by histopathological and immunohistochemical studies. Overall, our approach provided for the first time a potential strategy for targeted LTZ-CXB combined therapy of hormone-dependent breast cancer via singular nanocapsule delivery system.