Apoptosis and necrosis in toxicology: a continuum or distinct modes of cell death?

Ferulic acid alleviates carp brain damage and growth inhibition caused by avermectin by modulating the Nrf2/Keap1 and NF-κB signaling pathways

The increasing concern over environmental pollution caused by the pesticide avermectin used in aquaculture has attracted significant attention. The use of avermectin, a neurotoxic pesticide, in aquatic environments leads to toxic effects on non-target organisms, particularly causing harm to fish. The phenolic compound ferulic acid possesses excellent anti-inflammatory and antioxidant capabilities. This study was conducted by establishing a chronic exposure experiment to avermectin, proposes the use of ferulic acid as a dietary additive to protect the carp brain from damage caused by exposure to avermectin. Furthermore, it investigates the anti-inflammatory and antioxidant effects of ferulic acid in the carp brain under chronic exposure to avermectin. The experimental results demonstrate that ferulic acid can alleviate brain tissue inflammation and oxidative stress by modulating the Nrf2/Keap1 and NF-κB signaling pathways. It protects the carp brain from chronic avermectin-induced damage, preserves the integrity of the carp blood-brain barrier, enhances the levels of feeding factors, and thereby alleviates carp growth inhibition. These findings provide new therapeutic strategies and a theoretical foundation for the sustainable development of carp aquaculture.

Nature-Inspired Bioactive Compounds: A Promising Approach for Ferroptosis-Linked Human Diseases?

Ferroptosis is a type of cell death driven by iron overload and lipid peroxidation. It is considered a key mechanism in the development of various diseases such as atherosclerosis, Alzheimer, diabetes, cancer, and renal failure. The redox status of cells, such as the balance between intracellular oxidants (lipid peroxides, reactive oxygen species, free iron ions) and antioxidants (glutathione, glutathione Peroxidase 4), plays a major role in ferroptosis regulation and constitutes its principal biomarkers. Therefore, the induction and inhibition of ferroptosis are promising strategies for disease treatments such as cancer or neurodegenerative and cardiovascular diseases, respectively. Many drugs have been developed to exert ferroptosis-inducing and/or inhibiting reactions, such as erastin and iron-chelating compounds, respectively. In addition, many natural bioactive compounds have significantly contributed to regulating ferroptosis and ferroptosis-induced oxidative stress. Natural bioactive compounds are largely abundant in food and plants and have been for a long time, inspiring the development of various low-toxic therapeutic drugs. Currently, functional bioactive peptides are widely reported for their antioxidant properties and application in human disease treatment. The scientific evidence from biochemical and in vitro tests of these peptides strongly supports the existence of a relationship between their antioxidant properties (such as iron chelation) and ferroptosis regulation. In this review, we answer questions concerning ferroptosis milestones, its importance in physiopathology mechanisms, and its downstream regulatory mechanisms. We also address ferroptosis regulatory natural compounds as well as provide promising thoughts about bioactive peptides.

Histopathological, ultrastructural, and biochemical traits of apoptosis induced by peroxisomicine A1 (toxin T-514) from Karwinskia parvifolia in kidney and lung

Peroxisomicine A1 (PA1) is a toxin isolated from the Karwinskia genus plants whose target organs are the liver, kidney, and lung. In vitro studies demonstrated the induction of apoptosis by PA1 in cancer cell lines, and in vivo in the liver. Apoptosis has a wide range of morphological features such as cell shrinkage, plasma membrane blistering, loss of microvilli, cytoplasm, and chromatin condensation, internucleosomal DNA fragmentation, and formation of apoptotic bodies that are phagocytized by resident macrophages or nearby cells. Early stages of apoptosis can be detected by mitochondrial alterations. We investigated the presence of apoptosis in vivo at the morphological, ultrastructural, and biochemical levels in two target organs of PA1: kidney and lung. Sixty CD-1 mice were divided into three groups (n = 20): untreated control (ST), vehicle control (VH), and PA1 intoxicated group (2LD50). Five animals of each group were sacrificed at 4, 8, 12, and 24 h post-intoxication. Kidney and lung were examined by morphometry, histopathology, ultrastructural, and DNA fragmentation analysis. Pre-apoptotic mitochondrial alterations were present at 4 h. Apoptotic bodies were observed at 8 h and increased over time. TUNEL positive cells were detected as early as 4 h, and the DNA ladder pattern was observed at 12 h and 24 h. The liver showed the highest value of fragmented DNA, followed by the kidney and the lung. We demonstrated the induction of apoptosis by a toxic dose of PA1 in the kidney and lung in vivo. These results could be useful in understanding the mechanism of action of this compound at toxic doses in vivo.

Pulegone and Eugenol Oral Supplementation in Laboratory Animals: Results from Acute and Chronic Studies

Essential oils are natural compounds used by humans for scientific purposes due to their wide range of properties. Eugenol is mostly present in clove oil, while pulegone is the main constituent of pennyroyal oil. To guarantee the safe use of eugenol and pulegone for both humans and animals, this study addressed, for the first time, the effects of these compounds, at low doses (chronic toxicity) and high doses (acute toxicity), in laboratory animals. Thirty-five FVB/n female mice were randomly assigned to seven groups (n = 5): group I (control, non-additive diet); group II (2.6 mg of eugenol + 2.6 mg of pulegone); group III (5.2 mg of eugenol + 5.2 mg of pulegone); group IV (7.8 mg of eugenol + 7.8 mg of pulegone); group V (7.8 mg of eugenol); group VI (7.8 mg of pulegone); and group VII (1000 mg of eugenol + 1000 mg of pulegone). The compounds were administered in the food. Groups I to VI were integrated into the chronic toxicity study, lasting 28 days, and group VII was used in the acute toxicity study, lasting 7 days. Animals were monitored to assess their general welfare. Water and food intake, as well as body weight, were recorded. On the 29th day, all animals were euthanized by an overdose of ketamine and xylazine, and a complete necropsy was performed. Blood samples were collected directly from the heart for microhematocrit and serum analysis, as well as for comet assay. Organs were collected, weighed, and fixed in formaldehyde for further histological analysis and enzymatic assay. Eugenol and pulegone induced behavioral changes in the animals, namely in the posture, hair appearance and grooming, and in mental status. These compounds also caused a decrease in the animals’ body weight, as well as in the food and water consumption. A mortality rate of 20% was registered in the acute toxicity group. Both compounds modulated the serum levels of triglycerides and alanine aminotransferase. Eugenol and pulegone induced genetic damage in all animals. Eugenol increased the activity of the CAT enzyme. Both compounds increased the GR enzyme at the highest dose. Moreover, pulegone administered as a single compound increased the activity of the GST enzyme. Histopathological analysis revealed inflammatory infiltrates in the lungs of groups II, III, and IV. The results suggest that eugenol and pulegone may exert beneficial or harmful effects, depending on the dose, and if applied alone or in combination.

The environment and female reproduction: Potential mechanism of cadmium poisoning to the growth and development of ovarian follicle

Cadmium (Cd) is ubiquitous in our environment and can easily bioaccumulate into the organism after passage through the respiratory and digestive tracts. Long-term exposure to Cd can result in the significant bioaccumulation in organism because of its long biological high-life (10-30 years), which exerts irreversible damages on the health of animals and humans. Although there are increased evidence of impeding the normal function of female reproduction resulted from Cd exposure, the mechanism of the negative action of Cd on the growth and development of ovarian follicle remains enigmatic. Thus, the purpose of the presented study is to summarize available literature which describing Cd-related toxicity involved in the adverse effects on the growth and development of the ovarian follicle. In conclusion, it is suggested that Cd causes damage to the folliculogenesis of mammalians, which results in the decline in the number and quality of ovulated oocytes and the failure in the fertilization. The mechanism behinds that may be linked to the interference to the production of reproductive hormones and the augment of reactive oxygen species (ROS). Furthermore, the enhanced ROS, in turn, impairs various molecules including proteins, lipids and DNA, as well as the balance of the antioxidant defense system, mitochondrial homeostasis, endoplasmic reticulum, autophagy and epigenetic modification. This review is expected to elaborate the toxic mechanism of Cd exposure to the growth and development of ovarian follicles and provide essential remediation strategies to alleviate the damage of Cd to female reproductive health.

Mitoquinone mitigates paraquat-induced A549 lung epithelial cell injury by promoting MFN1/MFN2-mediated mitochondrial fusion

Paraquat (PQ) poisoning often leads to severe lung injuries, in which the mitochondria damage plays a critical role. Mitoquinone (MitoQ), a newly designed mitochondria-targeted antioxidant, has been proved for its benefit in mitochondria protection. However, the role of MitoQ in PQ-induced lung injury remains unclear. Thus, this study was performed to investigate the effect of MitoQ on PQ-induced lung injury and its underlying mechanisms. Our work showed that PQ caused the inhibition of A549 lung epithelial cell viability in a dose-dependent manner, while MitoQ remarkably mitigated the PQ-induced cell viability suppression. Besides this, PQ-mediated apoptosis of A549 cells was significantly attenuated by MitoQ, as indicated by the TUNEL assay and mitochondria membrane potential assay. Moreover, the intracellular reactive oxygen species (ROS) production was also dramatically suppressed when cotreated MitoQ with PQ. This could be ascribed to enhanced mitochondrial fusion mediated by Mitofusin 1 (MFN1)/Mitofusin 2 (MFN2), because MitoQ preserved mitochondrial network integrity, as reflected by MitoTracker staining, and MitoQ also increased the expression of MFN1/MFN2 in A549 cells after PQ treatment. Our data suggested MitoQ mitigated PQ-induced lung epithelial cell injury by promoting MFN1/MFN2-mediated mitochondrial fusion, and MitoQ might be a potential candidate drug for the treatment of PQ-induced lung injury.

Evaluation of the Cytotoxicity and Apoptotic Induction in Human Liver Cell Lines Exposed to Three Food Additives

BACKGROUND

Rapid lifestyle, especially among people living in urban areas, has led to increasing reliance on the processed food market. Unfortunately, harmful effects caused by the excessive use of food additives in such type of industry are often neglected.

OBJECTIVE

This proposal investigates in vitro cytotoxic and apoptotic effects of three food preservatives commonly consumed in daily meals; sodium sulphite, boric acid, and benzoic acid.

METHODS

The effect of the three preservatives on cell viability was tested on two different cell lines; normal liver cell line THLE2 and human hepatocellular carcinoma cancer cell line HepG2 using MTT assay. Cell cycle arrest was measured using flow cytometry by propidium iodide. Measurement of expression levels of two central genes, p53 and bcl-2 that play key roles in cell cycle and apoptosis was carried out in HepG2 cells using real time-PCR.

RESULTS

Although the effect was more significantly realized in the HepG2 cell line, the viability of both cell lines was decreased by all of the three tested compounds. Flow cytometric analysis of HepG2 cells treated with sodium sulphite, boric acid, and benzoic acid has revealed an increase in G2/M phase cell cycle arrest. In Sodium sulphite and boric acid-treated cells, expression levels of p53 were up-regulated, while that of the Bcl2 was significantly down-regulated. On the other hand, Benzoic acid has shown an anti-apoptotic feature based on the increased expression levels of Bcl-2 in treated cells.

CONCLUSION

In conclusion, all of the tested compounds have decreased the cell line viability and induced both cell cycle arrest and apoptotic events indicating their high potential of being cytotoxic and genotoxic materials.

Cytostatic and Antiproliferative Activities of F5 Fraction of Crinum amabile Leaf Chloroform Extract Showed Its Potential as Cancer Chemotherapeutic Agent

Medicinal plants have been considered as promising sources of drugs in treating various cancers. Crinum amabile (C. amabile), a plant species from the Amaryllidaceae family, is claimed to be a potential source for cancer chemotherapeutic compounds. Here, we aimed to investigate the potential of C. amabile as an anticancer agent. Dried leaves of C. amabile were serially extracted and our findings showed that chloroform extract (CE) was shown to exhibit cytotoxic effect against all cancer cell lines used. This active extract was further fractionated in which F5 fraction was shown to possess the highest cytotoxicity among all fractions. F5 fraction was then tested in-depth through Annexin V/FITC apoptosis and DNA fragmentation assays to determine its apoptotic effect on MCF-7 cells. Results revealed that F5 fraction only showed induction of cell apoptosis starting at 72-hour treatment while DNA fragmentation was not detected at any of the concentrations and treatment periods tested. Meanwhile, cell proliferation assay revealed that F5 fraction was able to inhibit normal cell proliferation as well as VEGF-induced cell proliferation of normal endothelial cell (HUVECs). In conclusion, F5 fraction from C. amabile leaf CE was able to exhibit cytostatic effect through antiproliferation activity rather than induction of cell apoptosis and therefore has the potential to be further investigated as an anticancer agent.

Cytotoxic and Apoptotic Effects on Hepatocytes of Secondary Metabolites Obtained from Lichens

There are a large number of species of Antarctic lichens, and several studies describing the secondary metabolites present in these lichens, as well as the advances in understanding the chemistry of these metabolites, have been reported. In addition, some derivatives displaying interesting antibacterial effects have been described. The cytotoxic and apoptotic effects of 15 secondary metabolites (depsides, depsidones and usnic acid) obtained from Continental (Chilean) and Antarctic lichens were evaluated in primary cultures of rat hepatocytes. Intracellular lactate dehydrogenase release, caspase 3 activation and DNA fragmentation were measured. In this study, we have evaluated a set of markers associated with pivotal steps in the execution phase of apoptosis, in order to detect compounds with apoptotic effects on hepatocytes before significant necrosis takes place. Flow cytometric analysis of DNA fragmentation revealed an increase in apoptotic nuclei with sub-diploid DNA content after the exposure of hepatocytes to sub-cytotoxic concentrations of the compounds. Among these, salazinic acid, stictic acid and psoromic acid displayed significant apoptotic activities. Divaricatic acid showed only moderate apoptotic effects at sub-cytotoxic concentrations.

Nanocatalysts-Augmented and Photothermal-Enhanced Tumor-Specific Sequential Nanocatalytic Therapy in Both NIR-I and NIR-II Biowindows

The tumor microenvironment (TME) has been increasingly recognized as a crucial contributor to tumorigenesis. Based on the unique TME for achieving tumor-specific therapy, here a novel concept of photothermal-enhanced sequential nanocatalytic therapy in both NIR-I and NIR-II biowindows is proposed, which innovatively changes the condition of nanocatalytic Fenton reaction for production of highly efficient hydroxyl radicals (•OH) and consequently suppressing the tumor growth. Evidence suggests that glucose plays a vital role in powering cancer progression. Encouraged by the oxidation of glucose to gluconic acid and H₂ O₂ by glucose oxidase (GOD), an Fe₃ O₄ /GOD-functionalized polypyrrole (PPy)-based composite nanocatalyst is constructed to achieve diagnostic imaging-guided, photothermal-enhanced, and TME-specific sequential nanocatalytic tumor therapy. The consumption of intratumoral glucose by GOD leads to the in situ elevation of the H₂ O₂ level, and the integrated Fe₃ O₄ component then catalyzes H₂ O₂ into highly toxic •OH to efficiently induce cancer-cell death. Importantly, the high photothermal-conversion efficiency (66.4% in NIR-II biowindow) of the PPy component elevates the local tumor temperature in both NIR-I and NIR-II biowindows to substaintially accelerate and improve the nanocatalytic disproportionation degree of H₂ O₂ for enhancing the nanocatalytic-therapeutic efficacy, which successfully achieves a remarkable synergistic anticancer outcome with minimal side effects.

Mathematical Models of Cell Response Following Heating

The cells of the cardiovascular system can experience temperature excesses of a few degrees during a diseased state or of tens of degrees during a thermal therapy treatment. These raised temperatures may be acute or of long duration. The multiple cell lines that compose each tissue then react, in approximate order of increasing thermal insult, by expressing heat shock proteins, undergoing apoptosis, or suffering necrosis. Mathematical models of the response of cells could aid in planning and designing thermal therapies. The multi-factor nature of the cell response makes it challenging to develop such models. The models most used clinically are mathematically simple and based on the response of representative tissues. The model that might provide the most fundamental understanding of the biochemical response of cells requires many parameters, some of which are difficult to measure. None of the semi-empirical models that provide improved prediction of cell fate have been widely accepted to plan therapies. There remain great opportunities for developing mathematical models cell response.

Investigation of antioxidant and anticancer potential of fucoidan from Sargassum polycystum

The present study was aimed to evaluate the antioxidant and anticancer potential of fucoidan isolated from Sargassum polycystum. The isolated fucoidan was successfully purified by DEAE cellulose-ion exchange chromatography and dialysis. Totally four active fractions (F1-F4) were collected and explored its chemical constitution by calorimetric assays. Among them, fraction 2 (F2) showed the higher yield percentage, fucose and sulphate content. Further, monosaccharide composition, structural and functional properties of the F2 was analyzed by HPLC, FTIR and NMR. F2 shows highest DPPH radical scavenging activity (55.94 ± 0.69%), reducing power (0.33 absorbance rate), hydrogen peroxide scavenging activity (71.76 ± 2.14%) and nitric oxide radical scavenging activity (51.81 ± 1.04%) at 1000 μg/ml. The cell viability of MCF-7 and HCT-15 cell lines was proportionate to the concentration of F2 with an estimated IC50 was 20 and 50 μg/ml respectively. The fluorescence and confocal laser scanning microscopic analysis demonstrated the apoptotic morphological changes and cell mediated death in F2 treated cancer cells. Higher amount of LDH release was found in the F2 treated cancer cells than the control group. Thus, the present finding proved that the isolated F2 encompasses significant antioxidant and anticancer property.

NAC ameliorates dental composite-induced DNA double-strand breaks and chromatin condensation

Released (co)monomers from dental composite components can induce DNA damage of which DNA double-strand breaks (DSBs) threaten genome integrity. Here, we tested whether the administration of the antioxidant N-acetylcysteine (NAC) is able to reduce the dental composite-induced DSBs in primary human gingiva fibroblasts. The dental composites Bis-GMA (bisphenol-A-glycerolate dimethacrylate), GMA (glycidyl methacrylate), HEMA (2-hydroxyethyl methacrylate) and TEGDMA (triethyleneglycol dimethacrylate) were found to induce co-localizing microscopic nuclear foci numbers of the DSB markers γ-H2AX and 53BP1 per cell in the order: GMA>Bis-GMA>TEGDMA>HEMA. Supplementation of (co)monomer-containing culture medium with NAC led to a significant reduction of resin-induced DSBs as well as to an amelioration of dental monomer-induced nuclear chromatin condensation in gingival fibroblasts. Thus, antioxidant treatment can reduce radical-induced chromatin and DNA damage and open avenues to mitigate genotoxic effects of dental composite compounds.

Maltodextrin modified liposomes for drug delivery through the blood-brain barrier

Central nervous system acting drugs, when administered intravenously, cannot show their effect in the brain due to the difficulty in crossing the blood-brain barrier (BBB). Levodopa is one of those drugs that are used to treat Parkinson's disease. In this study, a new liposomal levodopa delivery system that is modified with maltodextrin was developed in order to target and enhance transport through the BBB. An antioxidant, glutathione, was co-loaded in liposomes as a supportive agent and its effect on liposome stability and delivery was investigated. Glutathione co-loading had a positive effect on the viabilities of 3T3 and SH-SY5Y cells. Maltodextrin targeted liposomes showed high in vitro levodopa passage in the parallel artificial membrane permeability assay and had superior binding to MDCK cells. Results suggest that maltodextrin modification of liposomes is an effective way of targeting the BBB and the developed liposomal formulation would improve brain delivery of central nervous system agents.

Copper induced apoptosis in Caco-2 and Hep-G2 cells: Expression of caspases 3, 8 and 9, AIF and p53

Copper (Cu) is an essential trace metal needed to ensure cell function. However, when present at high concentrations it becomes toxic to organisms. Cell death, induced by toxic levels of copper, was previously observed in in vitro studies. However, there is no consensus about the cell death pathway induced by Cu and it is still not known whether this occurs as a result of the direct action of the metal or by indirect effects. In the present work, we intend to identify the influence of different Cu concentrations in the induction of apoptosis and to explore the potential signaling pathways, using two different in vitro cell culture models (Caco-2 and Hep-G2). Cells were exposed, during 6, 12, 24 and 48h, to Cu concentrations corresponding to IC50 and 1/8 of IC50, according to the viability assays. Then, considering the different apoptosis pathways, the expression of caspases 3, 8 and 9, apoptosis inducing factor (AIF) and p53 genes was analyzed by quantitative real time PCR. The results suggested that different Cu concentrations could trigger different apoptotic pathways, at different times of exposure. In both cell lines, apoptosis seems to be initiated by caspase independent pathway and intrinsic pathway, followed by extrinsic pathway. In conclusion, this study demonstrates that Cu induces the activation of apoptosis through caspase dependent and independent pathways, also suggesting that apoptosis activation mechanism is dependent on the concentration, time of exposure to Cu and cell type.

Necrotic pyknosis is a morphologically and biochemically distinct event from apoptotic pyknosis

Classification of apoptosis and necrosis by morphological differences has been widely used for decades. However, this usefulness of this method has been seriously questioned in recent years, mainly due to a lack of functional and biochemical evidence to interpret the morphology changes. To address this matter, we devised genetic manipulations in Drosophila to study pyknosis, a process of nuclear shrinkage and chromatin condensation that occurs in apoptosis and necrosis. By following the progression of necrotic pyknosis, we surprisingly observed a transient state of chromatin detachment from the nuclear envelope, followed by the nuclear envelope completely collapsing onto chromatin. This phenomenon led us to discover that phosphorylation of barrier-to-autointegration factor (BAF) mediates this initial separation of nuclear envelope from chromatin. Functionally, inhibition of BAF phosphorylation suppressed necrosis in both Drosophila and human cells, suggesting that necrotic pyknosis is conserved in the propagation of necrosis. In contrast, during apoptotic pyknosis the chromatin did not detach from the nuclear envelope and inhibition of BAF phosphorylation had no effect on apoptotic pyknosis and apoptosis. Our research provides the first genetic evidence supporting a morphological classification of apoptosis and necrosis through different forms of pyknosis.

A novel class of ethacrynic acid derivatives as promising drug-like potent generation of anticancer agents with established mechanism of action

The well-known diuretic Ethacrynic acid (EA, Edecrin), showing low anti-proliferative activities, was chemically modified at different positions. The new EA derivatives have been tested in vitro in anti-proliferative assays on both tumor KB (epidermal carcinoma) and leukemia HL60 (promyelocytic) cells suitable targets for anticancer activity. Reduction of the α-β double bond of EA completely abolished anti-cancer activities, whereas introduction of either 2-(4-substituted phenyl)ethanamine (series A) or 4-(4-substituted phenyl)piperazine (series B) moieties generated compounds showing moderate to strong anti-proliferative activities against human cancer cell lines. Several substitutions on the phenyl of these two moieties are tolerated. The mechanism of action of the EA derivatives prepared in this study is more complex than the inhibition of glutathione S-transferase π ascribed as unique effect to EA and might help to overcome tumor resistances.

Experimental models of hepatotoxicity related to acute liver failure

Acute liver failure can be the consequence of various etiologies, with most cases arising from drug-induced hepatotoxicity in Western countries. Despite advances in this field, the management of acute liver failure continues to be one of the most challenging problems in clinical medicine. The availability of adequate experimental models is of crucial importance to provide a better understanding of this condition and to allow identification of novel drug targets, testing the efficacy of new therapeutic interventions and acting as models for assessing mechanisms of toxicity. Experimental models of hepatotoxicity related to acute liver failure rely on surgical procedures, chemical exposure or viral infection. Each of these models has a number of strengths and weaknesses. This paper specifically reviews commonly used chemical in vivo and in vitro models of hepatotoxicity associated with acute liver failure.

Shinzami Korean purple-fleshed sweet potato extract prevents ischaemia-reperfusion-induced liver damage in rats

BACKGROUND

This study was designed to investigate the hepatoprotective effect of an extract from Shinzami, a variety of purple sweet potato, in rats injured by hepatic ischaemia-reperfusion (I/R).

RESULTS

Pretreatment with Shinzami extract decreased the aspirate aminotransferase and alanine aminotransferase serum levels in our hepatic I/R rat model. The glutathione level and superoxide dismutase activity level were significantly higher in the rats pretreated with the Shinzami extract compared with the hepatic I/R rats, and the glutathione peroxidase activity level was higher in pretreated rats. The total anthocyanins extracted from Shinzami, however, only increased the superoxide dismutase activity level in the hepatic I/R rats. Rats pretreated with the Shinzami extract or anthocyanins demonstrated attenuated hepatic pathological changes, such as hepatic distortion, haemorrhage, necrosis and inflammatory cell infiltration compared with the hepatic I/R control rats.

CONCLUSION

Shinzami extract and anthocyanins have a hepatoprotective effect on the liver damage induced by hepatic I/R by improving antioxidant status. Furthermore, the Shinzami extract may have a more potent effect on the antioxidant status compared with the Shinzami anthocyanins alone.

Application of a quantitative histological health index for Antarctic rock cod (Trematomus bernacchii) from Davis Station, East Antarctica

A quantitative Histological Health Index (HHI) was applied to Antarctic rock cod (Trematomus bernacchii) using gill, liver, spleen, kidney and gonad to assess the impact of wastewater effluent from Davis Station, East Antarctica. A total of 120 fish were collected from 6 sites in the Prydz Bay region of East Antarctica at varying distances from the wastewater outfall. The HHI revealed a greater severity of alteration in fish at the wastewater outfall, which decreased stepwise with distance. Gill and liver displayed the greatest severity of alteration in fish occurring in close proximity to the wastewater outfall, showing severe and pronounced alteration respectively. Findings of the HHI add to a growing weight of evidence indicating that the current level of wastewater treatment at Davis Station is insufficient to prevent impact to the surrounding environment. The HHI for T. bernacchii developed in this study is recommended as a useful risk assessment tool for assessing in situ, sub-lethal impacts from station-derived contamination in coastal regions throughout Antarctica.

Measurement of Apoptotic and Necrotic Cell Death in Primary Hepatocyte Cultures

Hepatotoxicity, including drug-induced liver injury, is frequently accompanied by cell death. The latter is typically driven by apoptosis or necrosis, which substantially differ based upon biochemical and morphological criteria. This chapter describes two commonly used methods to probe apoptotic and necrotic activities in adherent monolayer cultures of primary hepatocytes. The apoptosis assay uses a prototypical substrate of caspase 3, the main executor of apoptotic cell death, which can be cleaved, yielding a product that can be measured fluorimetrically. The second assay relies on the disruption of the cell plasma membrane, which typically occurs in necrotic cell death and that results in the extracellular release of cytoplasmic enzymes, such as lactate dehydrogenase. The latter can be indirectly assessed by spectrophotometrically measuring the consumption of reduced nicotinamide adenine dinucleotide.

Prix Fixe: Efferocytosis as a Four-Course Meal

During development, stress, infection, or normal homeostasis, billions of cells die on a daily basis, and the responsibility of clearing these cellular corpses lies with the phagocytes of innate immune system. This process, termed efferocytosis , is critical for the prevention of inflammation and autoimmunity , as well as modulation of the adaptive immune response. Defective clearance of dead cells is characteristic of many human autoimmune or autoinflammatory disorders, such as systemic lupus erythematosus (SLE), atherosclerosis, and diabetes. The mechanisms that phagocytes employ to sense, engulf, and process dead cells for an appropriate immune response have been an area of great interest. However, insight into novel mechanisms of programmed cell death , such as necroptosis, has shed light on the fact that while the diner (or phagocyte) is important, the meal itself (the type of dead cell) can play a crucial role in shaping the pursuant immune response.

Establishment and Characterization of an In Vitro Model of Fas-Mediated Hepatocyte Cell Death

Fas-mediated apoptosis underlies a plethora of liver pathologies and toxicities. As a consequence, this process is a major research topic in the field of experimental and clinical hepatology. The present chapter describes the setup of an in vitro model of hepatocellular apoptotic cell death. In essence, this system consists of freshly isolated hepatocytes cultured in a monolayer configuration, which are exposed to a combination of Fas ligand and cycloheximide. This in vitro model has been characterized by using a set of well-acknowledged cell death markers. This experimental system allows the study of the entire course of Fas-mediated hepatocellular cell death, going from early apoptosis to secondary necrosis, and hence can serve a broad range of in vitro pharmaco-toxicological purposes.

Direct evidence of histopathological impacts of wastewater discharge on resident Antarctic fish (Trematomus bernacchii) at Davis Station, East Antarctica

During the 2009/2010 summer, a comprehensive environmental impact assessment (EIA) of the wastewater discharge at Davis Station, East Antarctica was completed. As part of this, histological alteration of gill and liver tissue in Antarctic Rock-cod (Trematomus bernacchii) from four sites along a spatial gradient from the wastewater outfall were assessed. All fish within 800 m of the outfall exhibited significant histological changes in both tissues. Common pathologies observed in fish closest to the outfall include proliferation of epithelial cells with associated secondary lamellar fusion in the gills and multifocal granulomata with inflammation and necrosis as well as cysts in the liver. Fish from sites >800 m from the outfall also exhibited alterations but to a lesser degree, with prevalence and severity decreasing with increasing distance from the outfall. This study highlights the value of histopathological investigations as part of EIAs and provides the first evidence of sub-lethal alteration associated with wastewater discharge in East Antarctica.

Gamma-tocotrienol and hydroxy-chavicol synergistically inhibits growth and induces apoptosis of human glioma cells

Background

Gamma-tocotrienol (GTT), an isomer of vitamin E and hydroxy-chavicol (HC), a major bioactive compound in Piper betle, has been reported to possess anti-carcinogenic properties by modulating different cellular signaling events. One possible strategy to overcome multi-drug resistance and high toxic doses of treatment is by applying combinational therapy especially using natural bioactives in cancer treatment.

Methods

In this study, we investigated the interaction of GTT and HC and its mode of cell death on glioma cell lines. GTT or HC alone and in combination were tested for cytotoxicity on glioma cell lines 1321N1 (Grade II), SW1783 (Grade III) and LN18 (Grade IV) by [3-(4,5-dimethylthiazol-2- yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)- 2H- tetrazolium, inner salt] MTS assay. The interactions of each combination were evaluated by using the combination index (CI) obtained from an isobologram.

Results

Individually, GTT or HC displayed mild growth inhibitory effects against glioma cancer cell lines at concentration values ranging from 42–100 μg/ml and 75–119 μg/ml respectively. However, the combination of sub-lethal doses of GTT + HC dramatically enhanced the inhibition of glioma cancer cell proliferation and exhibited a strong synergistic effect on 1321N1 with CI of 0.55, and CI = 0.54 for SW1783. While in LN18 cells, moderate synergistic interaction of GTT + HC was observed with CI value of 0.73. Exposure of grade II, III and IV cells to combined treatments for 24 hours led to increased apoptosis as determined by annexin-V FITC/PI staining and caspase-3 apoptosis assay, showing caspase-3 activation of 27%, 7.1% and 79% respectively.

Conclusion

In conclusion, combined treatments with sub-effective doses of GTT and HC resulted in synergistic inhibition of cell proliferation through the induction of apoptosis of human glioma cells in vitro.

Primary hepatocytes and their cultures in liver apoptosis research

Apoptosis not only plays a key role in physiological demise of defunct hepatocytes, but is also associated with a plethora of acute and chronic liver diseases as well as with hepatotoxicity. The present paper focuses on the modelling of this mode of programmed cell death in primary hepatocyte cultures. Particular attention is paid to the activation of spontaneous apoptosis during the isolation of hepatocytes from the liver, its progressive manifestation upon the subsequent establishment of cell cultures and simultaneously to strategies to counteract this deleterious process. In addition, currently applied approaches to experimentally induce controlled apoptosis in this in vitro setting for mechanistic research purposes and thereby its detection using relevant biomarkers are reviewed.

Navigation to the graveyard-induction of various pathways of necrosis and their classification by flow cytometry

Apoptosis and necrosis reflect the program of cell death employed by a dying cell and the final stage of death, respectively. Whereas apoptosis is defined as a physiological, highly organized cell death process, necrosis is commonly considered to be accidental and uncontrolled. Physiological and weak pathological death stimuli preferentially induce apoptosis, while harsh non-physiological insults often immediately instigate (primary) necrosis. If an apoptosing cell transits into a phase of plasma membrane disintegration, this stage of death is referred to as secondary or post-apoptotic necrosis.Here, we present several conditions that stimulate primary and/or secondary necrosis and show that necrosis displays considerably different time courses. For subclassification of necrotic phenotypes we employed a flow cytometric single-tube 4-color staining technique including annexin A5-FITC, propidium iodide, DiIC1(5), and Hoechst 33342.

Apigenin induces apoptosis through mitochondrial dysfunction in U-2 OS human osteosarcoma cells and inhibits osteosarcoma xenograft tumor growth in vivo

The cytostatic drug from natural products has acted as a chemotherapeutic agent used in treatment of a wide variety of cancers. Apigenin, a type of flavonoid, exhibits anticancer actions, but there is no report to show that apigenin induced apoptosis in osteosarcoma cells. The aim of this study was to investigate the effects of apigenin on U-2 OS human osteosarcoma cells and clarify that the apigenin-induced apoptosis-associated signals. The cytotoxic effects of apigenin were examined by culturing U-2 OS cells with or without apigenin. The percentage of viable cells via PI staining, apoptotic cells, productions of ROS and Ca²⁺, and the level of mitochondrial membrane potential (ΔΨm) were assayed by flow cytometry. The levels of apoptosis-related proteins were measured by immunoblotting. Results indicated that apigenin significantly decreased cell viability. Apigenin effectively induced apoptosis through the activations of caspase-3, -8, -9, and BAX and promoted the release of AIF in U-2 OS cells. In nude mice bearing U-2 OS xenograft tumors, apigenin inhibited tumor growth. In conclusion, apigenin has anticancer properties for induction of cell apoptosis in U-2 OS cells and suppresses the xenograft tumor growth. These findings offer novel information that apigenin possibly possesses anticancer activity in human osteosarcoma.

Computational modeling of apoptotic signaling pathways induced by cisplatin

Background

Apoptosis is an essential property of all higher organisms that involves extremely complex signaling pathways. Mathematical modeling provides a rigorous integrative approach for analyzing and understanding such intricate biological systems.

Results

Here, we constructed a large-scale, literature-based model of apoptosis pathways responding to an external stimulus, cisplatin. Our model includes the key elements of three apoptotic pathways induced by cisplatin: death receptor-mediated, mitochondrial, and endoplasmic reticulum-stress pathways. We showed that cisplatin-induced apoptosis had dose- and time-dependent characteristics, and the level of apoptosis was saturated at higher concentrations of cisplatin. Simulated results demonstrated that the effect of the mitochondrial pathway on apoptosis was the strongest of the three pathways. The cross-talk effect among pathways accounted for approximately 25% of the total apoptosis level.

Conclusions

Using this model, we revealed a novel mechanism by which cisplatin induces dose-dependent cell death. Our finding that the level of apoptosis was affected by not only cisplatin concentration, but also by cross talk among pathways provides in silico evidence for a functional impact of system-level characteristics of signaling pathways on apoptosis.

The endocannabinoid N-arachidonoyl dopamine (NADA) selectively induces oxidative stress-mediated cell death in hepatic stellate cells but not in hepatocytes

The endocannabinoid system is a crucial regulator of hepatic fibrogenesis. We have previously shown that the endocannabinoid anandamide (AEA) is a lipid mediator that blocks proliferation and induces death in hepatic stellate cells (HSCs), the main fibrogenic cell type in the liver, but not in hepatocytes. However, the effects of other endocannabinoids such as N-arachidonoyl dopamine (NADA) have not yet been investigated. The NADA-synthesizing enzyme tyrosine hydroxylase was mainly expressed in sympathetic neurons in portal tracts. Its expression pattern stayed unchanged in normal or fibrotic liver. NADA dose dependently induced cell death in culture-activated primary murine or human HSCs after 2-4 h, starting from 5 μM. Despite caspase 3 cleavage, NADA-mediated cell death showed typical features of necrosis, including ATP depletion. Although the cannabinoid receptors CB1, CB2, or transient receptor potential cation channel subfamily V, member 1 were expressed in HSCs, their pharmacological or genetic blockade failed to inhibit NADA-mediated death, indicating a cannabinoid-receptor-independent mechanism. Interestingly, membrane cholesterol depletion with methyl-β-cyclodextrin inhibited AEA- but not NADA-induced death. NADA significantly induced reactive oxygen species formation in HSCs. The antioxidant glutathione (GSH) significantly decreased NADA-induced cell death. Similar to AEA, primary hepatocytes were highly resistant against NADA-induced death. Resistance to NADA in hepatocytes was due to high levels of GSH, since GSH depletion significantly increased NADA-induced death. Moreover, high expression of the AEA-degrading enzyme fatty acid amide hydrolase (FAAH) in hepatocytes also conferred resistance towards NADA-induced death, since pharmacological or genetic FAAH inhibition significantly augmented hepatocyte death. Thus the selective induction of cell death in HSCs proposes NADA as a novel antifibrogenic mediator.

Induction of apoptosis in sea bream fibroblasts by Vibrio harveyi haemolysin and evidence for an anti-apoptotic role of heat shock protein 70

In this study, we exposed black sea bream, Mylio macrocephalus (Basilewsky), fibroblast (BSF) and silver sea bream, Sparus sarba Forsskål, fibroblast (SSF) cell lines to a recombinant Vibrio harveyi haemolysin (VHH) and investigated mechanisms involved in apoptosis. A decrease in mitochondrial membrane potential, followed by an increase in caspase 3 activity, occurred within 2-8 h of VHH exposure, in both cell lines; however, VHH did not alter cellular levels of reactive oxygen species. As heat shock protein 70 (HSP70) is known to prevent the onset of apoptosis in certain mammalian cells, we aimed to test whether such a protective effect is operative in VHH-exposed fibroblasts. The amounts of HSP70 were elevated in SSF and BSF via an acute heat shock or an acute heat shock followed by a 6 h recovery. It was found that the VHH-mediated reduction in mitochondrial membrane potential was suppressed in cells that had a 6 h post-heat shock recovery, and the protective effect of heat shock-induced HSP70 was attenuated following treatment of cells with the HSP70 inhibitor, quercetin. This study demonstrates how haemolysin causes cell death via induction of apoptosis and provides evidence as to the role of HSP70 as an anti-apoptotic factor.

Development of an in vitro model of myotube ischemia

Critical limb ischemia causes severe damage to the skeletal muscle. This study develops a reproducible model of myotube ischemia by simulating, in vitro, the critical parameters that occur in skeletal muscle ischemia. Monolayers of C2C12 myoblasts were differentiated into mature myotubes and exposed to nutrition depletion, hypoxia and hypercapnia for variable time periods. A range of culture media and gas mixture combinations were used to obtain an optimum ischemic environment. Nuclear staining, cleaved caspase-3 and lactate dehydrogenase (LDH) release assay were used to assess apoptosis and myotube survival. HIF-1α concentration of cell lysates, pH of conditioned media as well as partial pressures of oxygen (PO₂) and carbon dioxide (PCO₂) in the media were used to confirm ischemic simulation. Culturing myotubes in depleted media, in a gas mixture containing 20% CO+80% N₂ for 6-12 h increased the PCO₂ and decreased the pH and PO₂ of culture media. This attempts to mimic the in vivo ischemic state of skeletal muscle. These conditions were used to study the potential tissue-protective effects of erythropoietin (EPO) in C2C12 myotubes exposed to ischemia. EPO (60 ng/ml) suppressed LDH release, decreased cleaved caspase-3 and reduced the number of apoptotic nuclei, suggesting significantly decreased ischemia-induced apoptosis in myotubes (P<0.01) and a potential role in tissue protection. Additional therapeutic agents designed for tissue protection can also be evaluated using this model.

CdTe quantum dots with daunorubicin induce apoptosis of multidrug-resistant human hepatoma HepG2/ADM cells: in vitro and in vivo evaluation

Cadmium telluride quantum dots (Cdte QDs) have received significant attention in biomedical research because of their potential in disease diagnosis and drug delivery. In this study, we have investigated the interaction mechanism and synergistic effect of 3-mercaptopropionic acid-capped Cdte QDs with the anti-cancer drug daunorubicin (DNR) on the induction of apoptosis using drug-resistant human hepatoma HepG2/ADM cells. Electrochemical assay revealed that Cdte QDs readily facilitated the uptake of the DNR into HepG2/ADM cells. Apoptotic staining, DNA fragmentation, and flow cytometry analysis further demonstrated that compared with Cdte QDs or DNR treatment alone, the apoptosis rate increased after the treatment of Cdte QDs together with DNR in HepG2/ADM cells. We observed that Cdte QDs treatment could reduce the effect of P-glycoprotein while the treatment of Cdte QDs together with DNR can clearly activate apoptosis-related caspases protein expression in HepG2/ADM cells. Moreover, our in vivo study indicated that the treatment of Cdte QDs together with DNR effectively inhibited the human hepatoma HepG2/ADM nude mice tumor growth. The increased cell apoptosis rate was closely correlated with the enhanced inhibition of tumor growth in the studied animals. Thus, Cdte QDs combined with DNR may serve as a possible alternative for targeted therapeutic approaches for some cancer treatments.

A mechanism of apigenin-induced apoptosis is potentially related to anti-angiogenesis and anti-migration in human hepatocellular carcinoma cells

Apigenin (APG) has been shown to have a strong anti-cancer effect on various cancer models via a programmed cell death, apoptosis. However, the fundamental mechanisms of these effects are still unclear. In the present study, we examined the question of whether or not APG can inhibit proliferation of hepatocellular carcinoma (HCC), huh-7 cells, resulting in apoptosis. In APG-treated cells, we observed typical features of apoptosis. To identify the proteins related to APG-induced apoptosis, we performed two-dimensional electrophoresis analysis and identified differentially expressed proteins. Among these proteins, we focused on vimentin, which plays a physiological role, such as cell migration and adhesion. We validated expression of vimentin in both mRNA and protein levels, verifying its decrease. In addition, we observed that APG down-regulated the expression levels of type I collagen, which collaborated with vimentin in cell migration and decreased the releasing amounts of VEGF and MMP-8, which are closely relevant to angiogenic activity. Finally, we confirmed the decreased capacity of cell migration due to down-regulation of vimentin, type I collagen, VEGF, and MMP-8 induced by APG. Based on the overall results, we suggested that vimentin was potentially associated with APG-induced apoptosis, as a key regulator in angiogenesis and migration.

Characterization of spontaneous cell death in monolayer cultures of primary hepatocytes

Monolayer cultures of primary hepatocytes, isolated from freshly removed livers, represent widely used in vitro tools in the area of liver physiology and pathology, pharmacology and toxicology. However, a major shortcoming of these systems is that they cope with dedifferentiation, which is accompanied by spontaneous cell death. The goal of the present study was to elucidate the mechanisms that drive the process of self-generated cell demise in primary hepatocyte cultures. For this purpose, isolated rat hepatocytes were cultivated under conventional conditions, and the occurrence of apoptosis and necrosis was monitored during 4 days by performing a set of acknowledged cell death assays. These included examination of cell morphology by light microscopy, quantification of apoptotic and necrotic cell populations by Hoechst 33342 and propidium iodide in situ staining, assessment of apoptotic and necrotic activities by measuring caspase 3-like activity and extracellular leakage of lactate dehydrogenase, and studying the expression of apoptosis regulators through immunoblot analysis. In essence, two cell death peaks were observed, namely shortly after cell seeding and in the final stages of the cultivation period, both involving apoptotic and necrotic actions. The outcome of this study not only sheds new light onto the molecular processes that underlie spontaneous cell death in primary hepatocyte cultures, but also opens perspectives for the establishment of strategies to increase cell survival in these popular in vitro systems.

Testate amoebae examined by confocal and two-photon microscopy: implications for taxonomy and ecophysiology

Testate amoebae (TA) are a group of free-living protozoa, important in ecology and paleoecology. Testate amoebae taxonomy is mainly based on the morphological features of the shell, as examined by means of light microscopy or (environmental) scanning electron microscopy (SEM/ESEM). We explored the potential applications of confocal laser scanning microscopy (CLSM), two photon excitation microscopy (TPEM), phase contrast, differential interference contrast (DIC Nomarski), and polarization microscopy to visualize TA shells and inner structures of living cells, which is not possible by SEM or environmental SEM. Images captured by CLSM and TPEM were utilized to create three-dimensional (3D) visualizations and to evaluate biovolume inside the shell by stereological methods, to assess the function of TA in ecosystems. This approach broadens the understanding of TA cell and shell morphology, and inner structures including organelles and endosymbionts, with potential implications in taxonomy and ecophysiology.

Mitochondrial and Cell Death Mechanisms in Neurodegenerative Diseases

Alzheimer’s disease (AD), Parkinson’s disease (PD) and amyotrophic lateral sclerosis (ALS) are the most common human adult-onset neurodegenerative diseases. They are characterized by prominent age-related neurodegeneration in selectively vulnerable neural systems. Some forms of AD, PD, and ALS are inherited, and genes causing these diseases have been identified. Nevertheless, the mechanisms of the neuronal cell death are unresolved. Morphological, biochemical, genetic, as well as cell and animal model studies reveal that mitochondria could have roles in this neurodegeneration. The functions and properties of mitochondria might render subsets of selectively vulnerable neurons intrinsically susceptible to cellular aging and stress and overlying genetic variations, triggering neurodegeneration according to a cell death matrix theory. In AD, alterations in enzymes involved in oxidative phosphorylation, oxidative damage, and mitochondrial binding of Aβ and amyloid precursor protein have been reported. In PD, mutations in putative mitochondrial proteins have been identified and mitochondrial DNA mutations have been found in neurons in the substantia nigra. In ALS, changes occur in mitochondrial respiratory chain enzymes and mitochondrial cell death proteins. Transgenic mouse models of human neurodegenerative disease are beginning to reveal possible principles governing the biology of selective neuronal vulnerability that implicate mitochondria and the mitochondrial permeability transition pore. This review summarizes how mitochondrial pathobiology might contribute to neuronal death in AD, PD, and ALS and could serve as a target for drug therapy.

Site-specific protein adducts of 4-hydroxy-2(E)-nonenal in human THP-1 monocytic cells: protein carbonylation is diminished by ascorbic acid

The protein targets and sites of modification by 4-hydroxy-2(E)-nonenal (HNE) in human monocytic THP-1 cells after exogenous exposure to HNE were examined using a multipronged proteomic approach involving electrophoretic, immunoblotting, and mass spectrometric methods. Immunoblot analysis using monoclonal anti-HNE antibodies showed several proteins as targets of HNE adduction. Pretreatment of THP-1 cells with ascorbic acid resulted in reduced levels of HNE-protein adducts. Biotinylation of Michael-type HNE adducts using an aldehyde-reactive hydroxylamine-functionalized probe (aldehyde-reactive probe, ARP) and subsequent enrichment facilitated the identification and site-specific assignment of the modifications by LC-MS/MS analysis. Sixteen proteins were unequivocally identified as targets of HNE adduction, and eighteen sites of HNE modification at Cys and His residues were assigned. HNE exposure of THP-1 cells resulted in the modification of proteins involved in cytoskeleton organization and regulation, proteins associated with stress responses, and enzymes of the glycolytic and other metabolic pathways. This study yielded the first evidence of site-specific adduction of HNE to Cys-295 in tubulin alpha-1B chain, Cys-351 and Cys-499 in alpha-actinin-4, Cys-328 in vimentin, Cys-369 in D-3-phosphoglycerate dehydrogenase, and His-246 in aldolase A.

Biochemical characterisation of an in vitro model of hepatocellular apoptotic cell death

This study was set up to critically evaluate a commonly-used in vitro model of hepatocellular apoptotic cell death, in which freshly isolated hepatocytes, cultured in a monolayer configuration, are exposed to a combination of Fas ligand and cycloheximide for six hours. A set of well-acknowledged cell death markers was addressed: a) cell morphology was studied by light microscopy; b) apoptotic and necrotic cell populations were quantified by in situ staining with Annexin-V, Hoechst 33342 and propidium iodide (PI); c) apoptotic and necrotic activities were monitored by probing caspase 3-like activity and measuring the extracellular leakage of lactate dehydrogenase (LDH), respectively; and d) the expression of apoptosis regulators was investigated by immunoblotting. The initiation of apoptosis was evidenced by the activation of caspase 8 and caspase 9, and increased Annexin-V reactivity. Progression through the apoptotic process was confirmed by the activation of caspase 3 and Bid, the enhanced expression of Bax, and the occurrence of nuclear fragmentation. Late transition to a necrotic appearance was demonstrated by an increased number of PI-positive cells and augmented extracellular release of LDH. Thus, the in vitro model allows the study of the entire course of Fas-mediated hepatocellular apoptotic cell death, which is not possible in vivo. This experimental system can serve a broad range of in vitro pharmaco-toxicological purposes, thereby directly assisting in the reduction of animal experimentation.

Renal cell apoptosis induced by nephrotoxic drugs: cellular and molecular mechanisms and potential approaches to modulation

Apoptosis plays a central role not only in the physiological processes of kidney growth and remodeling, but also in various human renal diseases and drug-induced nephrotoxicity. We present in a synthetic fashion the main molecular and cellular pathways leading to drug-induced apoptosis in kidney and the mechanisms regulating it. We illustrate them using three main nephrotoxic drugs (cisplatin, gentamicin, and cyclosporine A). We discuss the main regulators and effectors that have emerged as key targets for the design of therapeutic strategies. Novel approaches using gene therapy, antisense strategies, recombinant proteins, or compounds obtained from both classical organic and combinatorial chemistry are examined. Finally, key issues that need to be addressed for the success of apoptosis-based therapies are underlined.

Cellular stress reactions assessed by gender and species in spiders from areas variously polluted with heavy metals

In the funnel web spider Agelena labyrinthica (Agelenidae; A. l.), sheet web spider Linyphia triangularis (Linyphiidae; L. t.) and wolf spider Xerolycosa nemoralis (Lycosidae; X. n.) from two differently polluted meadow sites in southern Poland, we studied the relations between antioxidant parameters (glutathione, GSH; glutathione peroxidases, GPOX, GSTPx; catalase, CAT; stress proteins-Hsp70, metallothioneins Mts), the intensity of apoptosis and necrosis, and heavy metal burdens of the midgut gland. Cellular reactions against stress caused by pollutants seemed to be sex-dependent. The concentrations of Zn and Cu in the midgut glands of male A. l. and X. n. were more than double that of the females, from both study sites. In male spiders from the heavily polluted site, both negative correlations (activity of caspase-3-like proteins vs Cu, Zn concentration; number of depolarized mitochondria vs Cu concentration) and positive correlations (number of necrotic cells vs Cu concentrations; activity of CAT vs Zn ) were noted. The defense of males against high metal content and its prooxidative effects is based mainly on GSH and CAT. In females the antioxidative reactions are species-specific and depend mainly on high peroxidase activity and on stress protein level. The increase in the number of apoptotic cells in the midgut gland of female spiders from the heavily polluted site suggests the defensive role of this process in maintaining the proper functioning of this organ.