NIR-Responsive injectable hydrogel cross-linked by homobifunctional PEG for photo-hyperthermia of melanoma, antibacterial wound healing, and preventing post-operative adhesion.

Current therapeutic approaches for skin cancer face significant challenges, including wound infection, delayed skin regeneration, and tumor recurrence. To overcome these challenges, an injectable adhesive near-infrared (NIR)-responsive hydrogel with time-dependent enhancement in viscosity is developed for combined melanoma therapy and antibacterial wound healing acceleration. The multifunctional hydrogel is prepared through the chemical crosslinking between poly(methyl vinyl ether-alt-maleic acid) and gelatin, followed by the incorporation of CuO nanosheets and allantoin. The synergistic inherent antibacterial potential of CuO nanosheets, the regenerative and smoothing effect of allantoin, the extracellular matrix-mimicking effect of gelatin, and the desirable swelling behavior of the hydrogel results in fast wound recovery after photothermal ablation of the tumor. Additionally, the hydrogel can serve as an alternative to sutures owing to its tissue adhesiveness ability, which can further render it the merits for accelerated repair of abdominal lesions while acting as a biocompatible barrier to prevent peritoneal adhesion.

A photoactive injectable antibacterial hydrogel to support chemo-immunotherapeutic effect of antigenic cell membrane and sorafenib by near-infrared light mediated tumor ablation.

Intravenously administered nanocarriers suffer from off-target distribution, pre-targeting drug leakage, and rapid clearance, limiting their efficiency in tumor eradication. To bypass these challenges, an injectable hydrogel with time- and temperature-dependent viscosity enhancement behavior and self-healing property are reported to assist in the retention of the hydrogel in the tumor site after injection. The cancer cell membrane (CCM) and sorafenib are embedded into the hydrogel to elicit local tumor-specific immune responses and induce cancer cell apoptosis, respectively. In addition, hyaluronic acid (HA) coated Bi2S3 nanorods (BiH) are incorporated within the hydrogel to afford prolonged multi-cycle local photothermal therapy (PTT) due to the reduced diffusion of the nanorods to the surrounding tissues as a result of HA affinity toward cancer cells. The results show the promotion of immunostimulatory responses by both CCM and PTT through the release of inflammatory cytokines from immune cells, which allows localized and complete ablation of the breast tumor in an animal model by a single injection of the hydrogel. Moreover, the BiH renders strong antibacterial activity to the hydrogel, which is crucial for the clinical translation of injectable hydrogels as it minimizes the risk of infection in the post-cancer lesion formed by PTT-mediated cancer therapy.

Metal-coordination synthesis of a natural injectable photoactive hydrogel with antibacterial and blood-aggregating functions for cancer thermotherapy and mild-heating wound repair.

Photothermal therapy (PTT) is a promising approach for treating cancer. However, it suffers from the formation of local lesions and subsequent bacterial infection in the damaged area. To overcome these challenges, the strategy of mild PTT following the high-temperature ablation of tumors is studied to achieve combined tumor suppression, wound healing, and bacterial eradication using a hydrogel. Herein, Bi2S3 nanorods (NRs) are employed as a photothermal agent and coated with hyaluronic acid to obtain BiH NRs with high colloidal stability. These NRs and allantoin are loaded into an injectable Fe3+-coordinated hydrogel composed of sodium alginate (Alg) and Farsi gum (FG), which is extracted from Amygdalus scoparia Spach. The hydrogel can be used for localized cancer therapy by high-temperature PTT, followed by wound repair through the combination of mild hyperthermia and allantoin-mediated induction of cell proliferation. In addition, an outstanding blood clotting effect is observed due to the water-absorbing ability and negative charge of FG and Alg as well as the porous structure of hydrogels. The hydrogels also eradicate infection owing to the local heat generation and intrinsic antimicrobial activity of the NRs. Lastly, in vivo studies reveal an efficient photothermal-based tumor eradication and accelerated wound healing by the hydrogel.

Betanin alleviates oxidative stress through the Nrf2 signaling pathway in the liver of STZ-induced diabetic rats.

BACKGROUND: Continuing hyperglycemia causes and exacerbate oxidative stress. Betanin as the principal pigment of red beet root has antioxidant, anti-inflammatory, and anti-diabetic properties. The purpose of this study was to investigate the potency of betanin on antioxidant defense in STZ-induced diabetic rats' livers. METHODS: STZ at a single dose of 60 mg/kg body weight was intraperitoneally injected and betanin (10, 20, and 40 mg/kg/day) was administered orally for 28 days. Malondialdehyde (MDA), total antioxidant capacity (TAC), protein carbonyl (PC) levels, and the enzyme activity of superoxide dismutase (SOD), catalases and glutathione peroxidases (GPx) were evaluated in the liver. Furthermore, gene expression of Nrf2 and mentioned antioxidant enzymes were measured by Real-time PCR. RESULTS: Betanin (10 and 20 mg/kg) significantly reduced PC levels and increased antioxidant enzyme activity in diabetic rats compared to the control diabetic group (P < 0.01). In comparison to the diabetic control group, all studied genes expression in diabetic rats were increased significantly with betanin at doses of 10 and 20 mg/kg (P < 0.02). The increase in gene expression at 20 mg/kg of betanin was significantly stronger than others (P < 0.015) except for the catalase (P = 0.201), that was almost the same. Moreover, treatment of diabetic rats with 20 mg/kg of betanin could significantly increase TAC levels (P < 0.05) and decrease MDA levels (P < 0.001) compared to diabetic control group. CONCLUSIONS: Betanin could increase the antioxidant capacity of liver tissue associated with the Nrf2-mediated pathway in a dose-dependent manner.

The anti-diabetic effects of betanin in streptozotocin-induced diabetic rats through modulating AMPK/SIRT1/NF-κB signaling pathway.

BACKGROUND: In the last few years, the effects of bioactive food components have received much attention because of their beneficial effects including decreasing inflammation, scavenging free radicals, and regulating cell signaling pathways. Betanin as a potent antioxidant has been previously reported to exhibit anti diabetic effects. The present study aimed to evaluate the effects of betanin on glycemic control, lipid profile, hepatic function tests, as well as the gene expression levels of 5' adenosine monophosphate­activated protein kinase (AMPK), sirtuin-1 (SIRT1), and nuclear factor kappa B (NF­κB) in streptozocin (STZ) induced diabetic rats. METHODS: Diabetes was induced in male Sprague-Dawley rats by intraperitoneal administration of STZ. Different doses of betanin (10, 20 and 40 mg/kg.b.w) was administered to diabetic rats for 28 days. Fasting blood glucose and serum insulin were measured. The histopathology of liver and pancreas tissue evaluated. Real-time PCR was performed to assess gene expression levels. RESULTS: Treatment of diabetic rats with betanin (10 and 20 mg/kg.b.w) reduced FBG levels compared to the control diabetic rats (P < 0.001). Betanin at the dose of 20 mg/kg.b.w was most effective in increasing serum insulin levels (P < 0.001) improving glucose tolerance test (GTT) as well as improvement in lipid profile and liver enzymes levels. According to histopathologic assay, different damages induced by STZ to liver and pancreas tissues was largely eliminated by treatment with 10 and 20 mg/kg.b.w of betanin. Betanin also significantly upregulated the AMPK and SIRT1 and downregulated the NF-κB mRNA expression compared to the diabetic control rats (P < 0.05). CONCLUSION: Betanin could modulate AMPK/SIRT1/NF-κB signaling pathway and this may be one of its anti-diabetic molecular mechanisms.

Protective Effects of Cydonia oblonga Mill. Fruit on Carbon Tetrachloride-induced Hepatotoxicity Mediated through Mitochondria and Restoration of Cellular Energy Content.

Quince (Cydonia oblonga Mill.) is one of the medicinal plant with a broad range of pharmacological activities such as hepatoprotective effect. The present study was conducted to evaluate the effect of aqueous extract of Cydonia oblonga Mill. fruit (ACOF) against carbon tetrachloride (CCl4)-induced liver damage in rats. Hepatotoxicity was induced by CCl4 and all tested group animals were treated with the plant extract at a dose of 75, 150, and 300 mg/kg orally for 5 days. Blood was collected for the assessment of serum marker enzymes (alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH)). Adenosine triphosphate (ATP) of liver mitochondria was also measured using a validated high performance liquid chromatography (HPLC) method. The antioxidant capacity of the extract resulted in the reduction of MDA and the restoration of GSH in the liver (P < 0.05). Free radical scavenging activity of the extract was evaluated by DPPH method and the IC50 value was found to be 568 µg/mL. Our results indicated that bioenergetic depletion occurred in the intoxicated rats as a consequence of mitochondrial dysfunction and ATP production collapse. ACOF markedly restored ATP contents that is a key step in liver regeneration. It can be concluded that the role of ACOF to improve liver function on CCl4-hepatoxicity could be attributed, at least partially, to its action at mitochondira by preventing the loss of ATP content.

Mechanically Strong Silica-Silk Fibroin Bioaerogel: A Hybrid Scaffold with Ordered Honeycomb Micromorphology and Multiscale Porosity for Bone Regeneration.

Due to the synergic feature of individual components in hybrid (nano)biomaterials, their application in regenerative medicine has drawn significant attention. Aiming to address all the current challenges of aerogel as a potent scaffold in bone tissue engineering application, we adopted a novel synthesis approach to synergistically improve the pore size regime and mechanical strength in the aerogel. The three-dimensional aerogel scaffold in this study has been synthesized through a versatile one-pot aqueous-based sol-gel hybridization/assembly of organosilane (tetraethyl orthosilicate) and silk fibroin (SF) biopolymer, followed by unidirectional freeze-casting of the as-prepared hybrid gel and supercritical drying. The developed ultralight silica-SF aerogel hybrids demonstrated a hierarchically organized porous structure with interesting honeycomb-shaped micromorphology and microstructural alignment (anisotropy) in varied length scales. The average macropore size of the hybrid aerogel lied in ∼0.5-18 µm and was systematically controlled with freeze-casting conditions. Together with high porosity (91-94%), high Young's modulus (∼4-7 MPa, >3 order of magnitude improvement compared to their pristine aerogel counterparts), and bone-type anisotropy in the mechanical compressive behavior, the silica-SF hybrid aerogel of this study acted as a very competent scaffold for bone tissue formation. The results of in vitro assessments revealed that the silica-SF aerogel is not only cytocompatible and nonhemolytic but also acted as an open porous microenvironment to trigger osteoblast cell attachment, growth, and proliferation on its surface within 14 days of incubation. Moreover, to support the in vitro results, in vivo bone formation within the aerogel implant in the bone defect site was studied. The X-ray radiology and microcomputed tomography analyses confirmed that a significant new bone tissue density formed in the defect site within 25 days of implantation. Also, in vivo toxicology studies showed a zero-toxic impact of the aerogel implant on the blood biochemical and hematological parameters. Finally, the study clearly shows the potential of aerogel as a bioactive and osteoconductive open porous cellular matrix for a successful osseointegration process.

Cancer chemoprevention by oleaster (Elaeagnus angustifoli L.) fruit extract in a model of hepatocellular carcinoma induced by diethylnitrosamine in rats.

Hepatocellular carcinoma (HCC) is a frequent and fatal human cancer with poor diagnosis that accounts for over half a million deaths each year worldwide. Elaeagnus angustifolia L. known as oleaster has a wide range of pharmacological activities. This study aimed to investigate the chemopreventive effect of aqueous extract of E. angustifolia fruit (AEA) against diethylnitrosamine (DEN)-induced HCC in rats. HCC was induced in rats by a single injection of DEN (200 mg/kg) as an initiator. After two weeks, rats were orally administered 2-acetylaminofluorene or 2-AAF (30 mg/kg) as a promoter for two weeks. Oleaster-treated rats were orally pretreated with the increasing doses of AEA two weeks prior to DEN injection that continued until the end of the experiment. In the current study, a significant decrease in serum biomarkers of liver damage and cancer, including alfa-fetoprotein (AFP), gamma glutamyl transpeptidase (GGT), alanine transaminase (ALT), and aspartate transaminase (AST) was observed in AEA-treated rats when compared to HCC rats. Furthermore, the oleaster extract exhibited in vivo antioxidant activity by elevating reduced glutathione (GSH) contents as well as preventing lipid peroxidation in the liver tissues of DEN-treated rats. The relative weight of liver, a prognostic marker of HCC, was also reduced in oleaster-treated rats. To conclude, our results clearly demonstrated that oleaster fruit possesses a significant chemopreventive effect against primary liver cancer induced by DEN in rats. It can be suggested that the preventive activity of oleaster against hepatocarcinogenesis may be mediated through the antioxidant, anti-inflammation, and antimutagenic effects of the fruit.

Cytoprotective Effects of Pumpkin (Cucurbita Moschata) Fruit Extract against Oxidative Stress and Carbonyl Stress.

Background Diabetes mellitus is a chronic endocrine disorder that is associated with significant mortality and morbidity due to microvascular and macrovascular complications. Diabetes complications accompanied with oxidative stress and carbonyl stress in different organs of human body because of the increased generation of free radicals and impaired antioxidant defense systems. In the meantime, reactive oxygen species (ROS) and reactive carbonyl species (RCS) have key mediatory roles in the development and progression of diabetes complications. Therapeutic strategies have recently focused on preventing such diabetes-related abnormalities using different natural and chemical compounds. Pumpkin (Cucurbita moschata) is one of the most important vegetables in the world with a broad-range of pharmacological activities such as antihyperglycemic effect. Methods In the present study, the cytoprotective effects of aqueous extract of C. moschata fruit on hepatocyte cytotoxicity induced by cumene hydroperoxide (oxidative stress model) or glyoxal (carbonylation model) were investigated using freshly isolated rat hepatocytes. Results The extract of C. moschata (50 µg/ml) excellently prevented oxidative and carbonyl stress markers, including hepatocyte lysis, ROS production, lipid peroxidation, glutathione depletion, mitochondrial membrane potential collapse, lysosomal damage, and cellular proteolysis. In addition, protein carbonylation was prevented by C. moschata in glyoxal-induced carbonyl stress. Conclusion It can be concluded that C. moschata has cytoprotective effects in oxidative stress and carbonyl stress models and this valuable vegetable can be considered as a suitable herbal product for the prevention of toxic subsequent of oxidative stress and carbonyl stress seen in chronic hyperglycemia.

Mitochondria as a Target for the Cardioprotective Effects of Cydonia oblonga Mill. and Ficus carica L. in Doxorubicin-Induced Cardiotoxicity.

Quince (Cydonia oblonga Mill.) and fig (Ficus carica L.) exhibit a broad spectrum of pharmacological activities. Regarding the cardiotoxic effect of doxorubicin (DOX) is mediated mainly through mitochondrial oxidative stress and dysfunction; the present study evaluated the cardioprotective effects of the aqueous extracts of Cydonia oblonga Mill. fruit (ACO) and Ficus carica L. fruit (AFC) against DOX-induced cardiotoxicity. Cardiomyocytes toxicity was induced in male Sprague Dawley rats by intraperitoneal (ip) injections of 2.5 mg/kg DOX 3 times per week for a period of 2 weeks. After heart failure was induced in the rats, the animals were decapitated and their hearts were immediately removed. Then, the cardiac mitochondria were isolated by differential ultracentrifugation, and the protective effects of each particular extract on mitochondrial oxidative stress and dysfunction were determined. ACO and AFC ameliorated mitochondrial dysfunction in the isolated mitochondria and prevented mitochondrial reactive oxygen species formation, membrane lipid peroxidation, mitochondrial swelling, mitochondrial membrane potential collapse (%ΔΨm), and cytochrome c release. Also, the extracts significantly increased reduced glutathione levels and succinate dehydrogenase activity. These results indicated that ACO and AFC have beneficial effects against DOX cardiotoxicity which mediated by attenuating mitochondrial dysfunction. Therefore, it can be suggested that quince and fig may increase the therapeutic index of DOX.

Mitochondrial oxidative stress and dysfunction induced by isoniazid: study on isolated rat liver and brain mitochondria.

Isoniazid (INH or isonicotinic hydrazide) is used for the treatment and prophylaxis of tuberculosis. Liver and brain are two important target organs in INH toxicity. However, the exact mechanisms behind the INH hepatotoxicity or neurotoxicity have not yet been completely understood. Considering the mitochondria as one of the possible molecular targets for INH toxicity, the aim of this study was to evaluate the mechanisms of INH mitochondrial toxicity on isolated mitochondria. Mitochondria were isolated by differential ultracentrifugation from male Sprague-Dawley rats and incubated with different concentrations of INH (25-2000 µM) for the investigation of mitochondrial parameters. The results indicated that INH could interact with mitochondrial respiratory chain and inhibit its activity. Our results showed an elevation in mitochondrial reactive oxygen species (ROS) formation, lipid peroxidation and mitochondrial membrane potential collapse after exposure of isolated liver mitochondria in INH. However, different results were obtained in brain mitochondria. Noteworthy, significant glutathione oxidation, adenosine triphosphate (ATP) depletion and lipid peroxidation were observed in higher concentration of INH, as compared to liver mitochondria. In conclusion, our results suggest that INH may initiate its toxicity in liver mitochondria through interaction with electron transfer chain, lipid peroxidation, mitochondrial membrane potential decline and cytochrome c expulsion which ultimately lead to cell death signaling.

A comparison of cardiomyocyte cytotoxic mechanisms for 5-fluorouracil and its pro-drug capecitabine.

1. 5-Fluorouracil (5-FU) and its prodrug capecitabine are key chemotherapeutic agents in the treatment of many gastrointestinal tract adenocarcinomas. In addition to their beneficial antitumor effects, they also possess undesired cardiac toxicity. In the present study, we investigated the cytotoxic mechanisms of 5-FU and capecitabine in freshly isolated rat cardiomyocytes. 2. 5-FU and capecitabine cytotoxicities were associated with reactive oxygen species (ROS) formation, lipid peroxidation and rapid glutathione depletion. Increased intracellular ROS could target mitochondria, and our findings confirmed that the cardiomyocytes mitochondrial membrane potential (ΔΨm) was rapidly decreased by 5-FU and capecitabine. Mitochondrial dysfunction subsequently initiates downstream events that trigger caspase-3 activation, and our results showed that 5-FU and capecitabine activated caspase-3 which leads to apoptosis or necrosis. However, 5-FU acted much more powerful than capecitabine at inducing several cytotoxicity markers in heart cardiomyocytes. In addition, 5-FU but not capecitabine caused lysosomal membrane leakiness when it was incubated with cardiomyocytes. All cytotoxicity markers were prevented by antioxidants, ROS scavengers, mitochondrial permeability transition (MPT) pore sealing agents and lysosomotropic agents. 3. Our findings showed that the cytotoxic action of 5-FU and capecitabine on cardiomyocytes are mediated by oxidative stress and subsequent mitochondrial dysfunction which causes caspase-3 activation and cell death.

A new approach on methamphetamine-induced hepatotoxicity: involvement of mitochondrial dysfunction.

1. Methamphetamine (METH) is a highly addictive stimulant that is among the most widely abused illicit drugs. Clinical evidence has shown that the liver is a target of METH toxicity. The exact cellular and molecular mechanisms involved in METH-induced hepatotoxicity have not yet been completely understood. 2. In this study, the cellular pathways involved in METH liver toxicity were investigated in freshly isolated rat hepatocytes. METH cytotoxicity was associated with reactive oxygen species (ROS) formation, lipid peroxidation and rapid glutathione (GSH) depletion which is a third marker of cellular oxidative stress. Our results showed that the hepatocyte mitochondrial membrane potential (ΔΨm) was rapidly decreased by METH, which was prevented by antioxidants and ROS scavenger, suggesting that mitochondrial membrane damage was a consequence of ROS formation. Incubation of hepatocytes with METH also caused release of cytochrome c from mitochondria into the cytosol before cell lysis ensued. 3. Our findings showed that cytotoxic action of METH is mediated by oxidative stress and subsequent changes in mitochondrial membrane conformation and cytochrome c release into the cytosol which causes mitochondrial collapse of ΔΨm.

Toxicity of valproic acid in isolated rat liver mitochondria.

Valproic acid (VPA), an anticonvulsant and mood-stabilizing drug, is widely used for the treatment of different types of seizures and myoclonic epilepsy. Several mechanisms have been suggested for VPA hepatotoxicity, and most of them are associated with oxidative stress. It seems that oxidative stress by VPA treatment has been associated with mitochondrial dysfunction. Therefore, this study investigated the mitochondrial toxicity mechanisms of VPA on freshly isolated rat mitochondria for better understanding pathogenesis of VPA in mitochondrial toxicity. Rat liver mitochondria were obtained by differential ultracentrifugation and were then incubated with different concentrations of VPA (25-200 µM). Our results showed that VPA could induce oxidative stress via rising in mitochondrial reactive oxygen species formation, lipid peroxidation, mitochondrial membrane potential collapse, mitochondrial swelling and finally release of cytochrome c. These effects were well inhibited by pretreatment of isolated mitochondria with cyclosporin A and butylated hydroxytoluene. Based on these results, it is clear that VPA exerts mitochondrial toxicity by impairing mitochondrial functions leading to oxidative stress and cytochrome c expulsion, which start cell death signaling.

Racemose hemangioma type 2: the first case report from the Middle East.

Retinal arteriovenous malformations are rare and most are reported to be asymptomatic. We report an 11-year-old boy who attended for blunt trauma to his eye. The first ophthalmologic examination was performed in Nikookari Hospital Eye Emergency Room. Visual acuity was 20/20 and relative afferent pupillary defect was negative in both eyes. Ophthalmoscopic examination revealed multiple massive dilated retinal vessels in the superior arcade of the right eye. The arteriovenous malformation was not associated with exudation, hemorrhage or abnormal pigmentation. The left eye examination was unremarkable. We performed fluorescein angiography and brain magnetic resonance imaging (MRI). In the right eye fluorescein angiography, the malformation was not associated with leak or edema. The left eye fluorescein angiography was unremarkable. Brain MRI was unremarkable. After 16 months follow-up, there were no symptoms. This is the first case report from the Middle East region. To the best of our knowledge, retinal arteriovenous malformation has rarely been reported in children. Previously published literature suggests that these malformations may become complicated in time. Brain MRI is strongly recommended because of the possibility of Wyburn-Mason syndrome.

Glutathione mediated reductive activation and mitochondrial dysfunction play key roles in lithium induced oxidative stress and cytotoxicity in liver.

Lithium preparations are commonly used drug in treating mental disorders and bipolar diseases, but metal's cytotoxic mechanisms have not yet been completely understood. In this study, we investigated the cytotoxic mechanisms of lithium in freshly isolated rat hepatocytes. Lithium cytotoxicity were associated with reactive oxygen species (ROS) formation and collapse of mitochondrial membrane potential and cytochrome c release into the hepatocyte cytosol. All of the mentioned lithium-induced cytotoxicity markers were significantly (P < 0.05) prevented by ROS scavengers, antioxidants, mitochondrial permeability transition pore sealing agents and adenosine triphosphate generators. Hepatocyte glutathione (GSH) was also rapidly oxidized and GSH-depleted hepatocytes were more resistant to lithium-induced oxidative stress markers. This suggests that lithium is activated by GSH. Our results also showed that CYP2E1 is involved in lithium oxidative stress mechanism. Lithium cytotoxicity was also associated with mitochondrial injuries initiated by increased ROS formation resulted from metal-CYP2E1 destructive interaction or metal-induced disruption of mitochondrial electron transfer chain. Methyl donors such as betaine, methionine, or folic acid prevented lithium cytotoxicity, and this suggests that this metal is detoxified by phase II metabolic methylation. In conclusion lithium-induced cytotoxicity could be attributed to oxidative stress and mitochondrial dysfunction.

A new approach on valproic acid induced hepatotoxicity: involvement of lysosomal membrane leakiness and cellular proteolysis.

Although valproic acid (VPA) a proven anticonvulsant agent thought to have relatively few side-effects VPA has been referred as the third most common xenobiotic suspected of causing death due to liver injury. In this study the cellular pathways involved in VPA hepatotoxicity were investigated in isolated rat hepatocytes. Accelerated cytotoxicity mechanism screening (ACMS) techniques using fluorescent probes including, ortho-phthalaldehyde, rhodamine 123 and acridine orange were applied for measurement of ROS formation, glutathione depletion, mitochondrial membrane potential and Lysosomal membrane damage, respectively. Our results showed that cytotoxic action of VPA is mediated by lysosomal membrane leakiness along with reactive oxygen species (ROS) formation and decline of mitochondrial membrane potential before cell lysis ensued. Incubation of hepatocytes with VPA also caused rapid hepatocyte glutathione (GSH) depletion which is another marker of cellular oxidative stress. Most of the VPA induced GSH depletion could be attributed to the expulsion of GSSG. Our results also showed that CYP2EI is involved in the mechanism of VPA cytotoxicity. We finally concluded that VPA hepatotoxicity is a result of metabolic activation by CYP2E1 and ROS formation, leading to lysosomal labialization, mitochondrial/lysosomal toxic cross-talk and finally general cellular proteolysis in the rat hepatocytes.

Mitochondrial/lysosomal toxic cross-talk plays a key role in cisplatin nephrotoxicity.

Cisplatin is widely used chemotherapeutic agent for the treatment of several human malignancies. Dose-related nephrotoxicity is the major adverse effect of cisplatin. The cellular and molecular mechanisms behind the cisplatin nephrotoxicity have not yet been completely understood. In this study, cytotoxic effect of cisplatin on renal proximal tubular (RPT) cells was evaluated. Our results showed that cytotoxic action of cisplatin on RPT cells is mediated by reactive oxygen species (ROS) formation, decline of mitochondrial membrane potential, increase in caspase-3 activity and lysosomal membrane leakiness before cell lysis ensued. All of the above mentioned cisplatin-induced oxidative stress cytotoxicity markers were significantly (p < 0.05) prevented by ROS scavengers, antioxidants, mitochondrial permeability transition (MPT) pore sealing agents, endocytosis inhibitors and adenosine triphosphate (ATP) generators. Our results also showed that CYP2E1 involves in cisplatin oxidative stress cytotoxicity mechanism and intracellular nitric oxide enhancement protects the RPT cells against the cisplatin-induced cytotoxicity. It seems that cisplatin nephrotoxicity is associated with mutual mitochondrial/lysosomal potentiation (cross-talk) of oxidative stress in RPT cells. This cross-talk finally results in release of lysosomal digestive proteases and phospholipases and mitochondrial MPT pore opening leading to cytochrome c release and activation of caspases cascade which signal apoptosis.

Involvement of mitochondrial/lysosomal toxic cross-talk in ecstasy induced liver toxicity under hyperthermic condition.

The initial objectives of this study were to evaluate the extent of 3, 4-methylenedioxymethamphetamine (MDMA) induced loss of cell viability (cytotoxicity), induction of reactive oxygen species formation and damage to sub-cellular organelles (e.g. mitochondria/lysosomes) in freshly isolated rat hepatocytes under normothermic conditions (37 degrees C) and to compare the results with the effects obtained under hyperthermic conditions (41 degrees C). MDMA induced cytotoxicity, reactive oxygen species formation, mitochondrial membrane potential decline and lysosomal membrane leakiness in isolated rat hepatocytes at 37 degrees C. A rise in incubation temperature from 37 degrees C to 41 degrees C had an additive/synergic effect on the oxidative stress markers. We observed variations in mitochondrial membrane potential and lysosomal membrane stability that are significantly (P<0.05) higher than those under normothermic conditions. Antioxidants, reactive oxygen species scavengers, lysosomal inactivators, mitochondrial permeability transition (MPT) pore sealing agents, NADPH P450 reductase inhibitor, and inhibitors of reduced CYP2E1 and CYP2D6 prevented all MDMA induced hepatocyte oxidative stress cytotoxicity markers. It is therefore suggested that metabolic reductive activation of MDMA by reduced cytochrome P450s and glutathione could lead to generation of some biological reactive intermediates which could activate reactive oxygen species generation and cause mitochondrial and lysosomal oxidative stress membrane damages. We finally concluded that hyperthermia could potentiate MDMA induced liver toxicity probably through a mitochondrial/lysosomal toxic cross-talk in freshly isolated rat hepatocytes.

A comparison of hepatocyte cytotoxic mechanisms for thallium (I) and thallium (III).

Thallium (Tl) is a highly toxic heavy metal though up to now its mechanisms are poorly understood. In this study, we comparatively investigated the cytotoxic mechanisms of Tl(I) and Tl(III) in isolated rat hepatocytes. Both Tl(I) and Tl(III) cytotoxicities were associated with reactive oxygen species (ROS) formation, lipid peroxidation, collapse of mitochondrial membrane potential, activation of caspases cascade, lysosomal membrane leakiness, and cellular proteolysis. Hepatocyte glutathione (GSH) was also rapidly oxidized. GSH-depleted hepatocytes were more resistant to Tl(I)-induced cytotoxicity, ROS formation and lipid peroxidation. This suggests that Tl(I) is reductively activated by GSH. On the other hand, GSH-depleted hepatocytes were much more sensitive to Tl(III)-induced cytotoxicity, ROS formation, and lipid peroxidation. This suggests that GSH only plays an antioxidant role against Tl(III) cytotoxicity. Our results also showed that CYP2E1 involves in Tl(I) and Tl(III) oxidative stress cytotoxicity mechanism and both cations detoxified via methylation. In conclusion, both Tl(I) and Tl(III) cytotoxicities were associated with mutual mitochondrial/lysosomal injuries (cross-talk) initiated by increased ROS formation resulted from metal-CYP2E1 destructive interaction or metal-induced disruption of mitochondrial electron transfer chain.