Cell death in relation to DNA damage after exposure to the jellyfish Pelagia noctiluca nematocysts

Studies on the toxicity of Mediterranean jellyfish have gained attention owing to their weak toxic properties. Our research has been mainly performed on the Scyphomedusae. Pelagia noctiluca is a scyphozoan jellyfish which causes a danger to sea bathers and fishery damages in the Mediterranean Sea. To check whether the cytotoxicity of Pelagia noctiluca nematocysts was associated to DNA lesions, we have looked for DNA fragmentation by means of the Comet and chromosome aberration assays. To specify cell death pathway, we have investigated caspase‐3 activation. Our results have shown that nematocysts reduced cell viability and induced DNA fragmentation in a concentration‐dependent manner with a maximum effect at 150 000 nematocysts mL^?1. The high percentage of chromosome aberrations also emphasized the genotoxic character of Pelagia noctiluca nematocysts in Vero cells. This fragmentation was correlated to apoptosis induction which was confirmed by caspase‐3 activation. In conclusion, the present report has suggested that Pelagia noctiluca nematocysts were able to promote apoptosis in Vero cells and therefore may be useful in cancer therapy. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 337–344, 2014.     

A rapid and repeatable method for venom extraction from cubozoan nematocysts.

Various comparative studies into the biological activity and relative toxicity of cubozoan venoms have been investigated, in particular the venom from the potentially lethal cubozoan Chironex fleckeri. Efficient and reliable extraction of venom from nematocysts is essential before any research into venom toxicity can be conducted and previous cited methods of extraction have varied greatly, each with their own associated problems. A new standardised technique for the recovery of venom from nematocysts of cubozoans is investigated to decrease the variation displayed between authors due to differing extraction techniques. The use of a mini bead mill beater, as investigated in this trial, allows for the rapid extraction of venom from nematocysts and is devoid of the previously isolated problems experienced with other methods of venom isolation, such as excessive heat build up.     

Global distribution of ciguatera causing dinoflagellates in the genus Gambierdiscus

Dinoflagellates in the genus Gambierdiscus produce toxins that bioaccumulate in tropical and sub-tropical fishes causing ciguatera fish poisoning (CFP). Little is known about the diversity and distribution of Gambierdiscus species, the degree to which individual species vary in toxicity, and the role each plays in causing CFP. This paper presents the first global distribution of Gambierdiscus species. Phylogenetic analyses of the existing isolates indicate that five species are endemic to the Atlantic (including the Caribbean/West Indies and Gulf of Mexico), five are endemic to the tropical Pacific, and that two species, Gambierdiscus carpenteri and Gambierdiscus caribaeus are globally distributed. The differences in Gambierdiscus species composition in the Atlantic and Pacific correlated with structural differences in the ciguatoxins reported from Atlantic and Pacific fish. This correlation supports the hypothesis that Gambierdiscus species in each region produce different toxin suites. A literature survey indicated a >100-fold variation in toxicity among species compared with a 2 to 9-fold within species variation due to changing growth conditions. These observations suggest that CFP events are driven more by inherent differences in species toxicity than by environmental modulation. How variations in species toxicity may affect the development of an early warning system for CFP is discussed.     

Targeted inhibition of kinases in cancer therapy

With an understanding of the molecular changes that accompany cell transformation, cancer drug discovery has undergone a dramatic change in the past few years. Whereas most of the emphasis in the past has been placed on developing drugs that induce cell death based on mechanisms that do not discriminate between normal and tumor cells, recent strategies have emphasized targeting specific mechanisms that have gone awry in tumor cells. However, the identification of cancer-associated mutations in oncogenes and their amplification in tumors has suggested that inhibitors against such proteins might represent attractive substrates for targeted therapy. In the clinic, the success of imatinib (Gleevec?, STI571) and trastuzumab (Herceptin?), both firsts of their kind, spurred further development of new, second-generation drugs that target kinases in cancer. This review highlights a few important examples each of these types of therapies, along with some newer agents that are in various stages of development. Second-generation kinase inhibitors aimed at overriding emerging resistance to these therapies are also discussed.     

Immunomodulatory Effects of Triphala and its Individual Constituents: A Review

The role of plant extracts and Ayurvedic polyherbal preparations in treating various ailments has been acknowledged since time immemorial. Studies based on the effect of these extracts in treatment of different diseases have also been well documented. Indian medicinal literature also emphasizes the synergistic effect of polyherbal drugs in restoring and rejuvenating immune system. This review focuses on the immunomodulatory potential of the polyherbal preparation, Triphala and its three constituents, Terminalia bellerica, Terminalia chebula and Emblica officinalis. The role of Triphala and its extract has been emphasized in stimulating neutrophil function. Under stress condition such as noise, Triphala significantly prevents elevation of IL-4 levels as well as corrects decreased IL-2 and IFN-γ levels. Under the condition of inflammatory stress its immunosuppressive activity is attributed to its inhibitory action on complement system, humoral immunity, cell mediated immunity and mitogen-induced T-lymphocyte proliferation. The aqueous and alcoholic extracts of the individual constituents reportedly enhance especially the macrophage activation due to their free radical scavenging activity and the ability to neutralize reactive oxygen species. This study thus concludes the use of Triphala and its three individual constituents as potential immunostimulants and/or immunosuppressants further suggests them to be a better alternative for allopathic immunomodulators.     

The Leaves of Broussonetia kazinoki Siebold Inhibit Atopic Dermatitis-Like Response on Mite Allergen-Treated Nc/Nga Mice

Broussonetia kazinoki Siebold. (B. kazinoki) has long been used in the manufacture of paper in Asian countries. Although B. kazinoki leaves (BK) have been employed in dermatological therapy, use of BK has not been tested in patients with atopic dermatitis (AD). Using Nc/Nga mice, which are genetically predisposed to develop AD-like skin lesions, we confirmed the efficacy of BK in AD treatment. BK extract was applied topically to Dermatophagoides farinae-induced AD-like lesions in Nc/Nga mice, and the effects were assessed both clinically and by measuring skin thickness on the back and ears. We measured the effects of BK extract on plasma levels of IgE and IL-4. We also measured the ability of BK extract to inhibit the secretion of hTARC in HaCaT cells after stimulation by TNF-α and IFN-γ. We found that BK extract significantly reduced ear and dorsal skin thickness and the clinical signs of AD, as well as significantly down-regulating the plasma levels of IgE and IL-4 (p<0.01 for each comparison). Moreover, 500 μg/mL of BK extract inhibited hTARC secretion in HaCaT cells by activated TNF-α/IFN-γ by about 87%. These findings suggest that topical application of BK extract has excellent potential in the treatment of AD.     

Application of the threshold of toxicological concern approach for the safety evaluation of calendula flower (Calendula officinalis) petals and extracts used in cosmetic and personal care products

Calendula flower (Calendula officinalis) (CF) has been used in herbal medicine because of its anti-inflammatory activity. CF and C. officinalis extracts (CFE) are used as skin conditioning agents in cosmetics. Although data on dermal irritation and sensitization of CF and CFE’s are available, the risk of subchronic systemic toxicity following dermal application has not been evaluated. The threshold of toxicological concern (TTC) is a pragmatic, risk assessment based approach that has gained regulatory acceptance for food and has been recently adapted to address cosmetic ingredient safety. The purpose of this paper is to determine if the safe use of CF and CFE can be established based upon the TTC class for each of its known constituents. For each constituent, the concentration in the plant, the molecular weight, and the estimated skin penetration potential were used to calculate a maximal daily systemic exposure which was then compared to its corresponding TTC class value. Since the composition of plant extracts are variable, back calculation was used to determine the maximum acceptable concentration of a given constituent in an extract of CF. This paper demonstrates the utility and practical application of the TTC concept when used as a tool in the safety evaluation of botanical extracts.     

Managing skin damage induced by doxorubicin hydrochloride and daunorubicin hydrochloride

The pathophysiology and mechanisms of toxicity of anthracycline-induced skin damage are reviewed, and the various available therapeutic interventions are discussed. Skin ulcers caused by the vesicant antineoplastic agents doxorubicin hydrochloride and daunorubicin hydrochloride begin slowly, and the extent of the tissue damage produced is often underestimated. Within a week, untreated infiltrations of these agents can advance to serious indurations and ulcerations, causing extensive damage to underlying structures such as tendons and bones. Two theories have been proposed to explain the mechanism of action of anthrocycline-induced tissue damage; one holds that doxorubicin-DNA complexes form causing cell death, and the other holds that these agents are reduced to free radicals that can cause cell-membrane damage. Nonpharmacologic treatment of extravasation consists of stopping the infusion at the first sign of a problem and attempting to aspirate fluid and drug back through the same needle. The application of ice packs for the next 24-72 hours is recommended. A variety of pharmacologic approaches have been evaluated to ameliorate tissue damage. Corticosteroids, sodium bicarbonate, beta-adrenergic agents, and dimethyl sulfoxide have been used with some success. Patients who do not respond to initial conservative treatments should be referred to a plastic surgeon for skin grafting and reconstruction. The best treatment for anthracycline toxicity is prevention.     

Chemical biology of the mutualistic relationships of sea anemones with fish and crustaceans

Fish species of the genera Amphiprion and Premnas (Perciformes: Pomacentridae) as well as various crustaceans seek protection from predators among the tentacles of sea anemones, where they live essentially unharmed from stinging by the host's nematocysts. The mucous coats of anemonefish and crustaceans have been suggested as mechanisms that prevent the discharge of the nematocysts upon contact. Whereas some fish species seem to produce their own protecting mucous coating, others may acquire mucus from the sea anemone during an acclimation period, as crustaceans do. Whether the natural or acquired mucus layers contain components that inhibit nematocyst discharge or simply lack compounds stimulating the stinging cell's exocytosis is still unknown.     

Activation of the aryl hydrocarbon receptor by TCDD inhibits senescence: A tumor promoting event?

Activation of the aryl hydrocarbon receptor (AHR) by the agonist, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown to promote tumor formation in both liver and skin. In the liver, but not the skin, the AHR-mediated events that contribute to TCDD’s tumor promoting activities have been studied in some detail and are thought to involve perturbation of cell fate processes. However, studies performed using cultured cells have often resulted in apparent contradictory results indicating that the impact of TCDD on cell fate processes may be cell context dependent. We and others have shown that in primary cultured keratinocytes TCDD increases post-confluent proliferation and increases late differentiation. Further, our studies performed in these cells indicate that TCDD can also inhibit culture-induced senescence. While senescence, a permanent cell cycle arrest, is emerging as an important process regulated by oncogenes and considered to be of therapeutic importance, its role with respect to TCDD/AHR mediated tumor promotion has not been fully considered. The intent of this article is to focus primarily on senescence as a cell process relevant to skin tumorigenesis and explore the idea that the inhibition of senescence by TCDD could be an important mechanism by which it may exert its tumor promoting effects in the skin.     

Lack of promoting effect of titanium dioxide particles on ultraviolet B-initiated skin carcinogenesis in rats

Titanium dioxide (TiO₂) is used in sunscreens and cosmetics as an ultraviolet light screen. TiO₂ has carcinogenic activity in the rat lung, but its effect on the skin has not been reported. We examined the promoting/carcinogenic effect of nano-size TiO₂ particles using a two-stage skin model. c-Ha-ras proto-oncogene transgenic (Hras128) rats, which are sensitive to skin carcinogenesis, and their wild-type siblings were exposed to ultraviolet B radiation on shaved back skin twice weekly for 10 weeks; then the shaved area was painted with a 100 mg/ml TiO₂ suspension twice weekly until sacrifice. All rats were killed at week 52 except for female Hras128 rats which were sacrificed at week 16 because of early mammary tumor development. Skin tumors developed in male Hras128 rats and mammary tumors developed in both sexes of Hras128 rats and in wild-type female rats, but tumor incidence was not different from controls. TiO₂ particles were detected in the upper stratum corneum but not in the underlying skin tissue layers. TiO₂ particles also did not penetrate a human epidermis model in vitro. Our data suggest that TiO₂ does not cause skin carcinogenesis, probably due to its inability to penetrate through the epidermis and reach underlying skin structures.     

Risk assessment and risk communication

Newborn infants are regularly exposed to a wide variety of topical agents, including treatments for rashes, antimicrobial agents, solvents, and skin barriers or moisturizers. Premature and hospitalized infants are also exposed to topical iodine for antisepsis and to topical analgesic agents. The fact that most of these agents have not been specifically evaluated for use in infants has recently been recognized as a major public health concern. The epidermis of preterm infants is not fully developed, constituting an incomplete barrier to systemic absorption of topical agents. Thus, substances applied to the skin can have adverse systemic effects. Povidine–iodine and steroid creams have been associated with thyroid and hypothalamic–pituitary axis suppression, respectively, in premature infants. Application of topical EMLA (Eutectic Mixture of Local Anesthetics) for analgesia has been implicated in methemoglobinemia in premature infants. Exposure to natural latex in gloves and medical equipment may sensitize infants, leading to the development of airway hyperreactivity and other allergic manifestations. Therefore, it is advisable to limit skin exposure of premature infants to xenobiotics. Further work is required to define safe doses of common agents. In addition, transdermal administration of systemic medications, including methylxanthines, may be practical in premature infants.     

Stinging coral (Millepora tenera) toxin: a comparison of crude extracts with isolated nematocyst extracts

A method suitable for isolating Millepora tenera nematocysts free of extra-nematocyst material is described. The toxic material from the nematocysts had an ld₅₀ in mice of 40 μg protein per kg body weight and displayed hemolytic and dermonecrotic properties. Comparison of nematocyst extract and crude extract of whole specimens of M. tenera by electrophoresis and double diffusion tests indicated the toxin in crude extract is of nematocyst origin and not from extra-nematocyst material.     

The Long Search for Pharmacologically Useful Anti-Inflammatory Flavonoids and Their Action Mechanisms: Past,Present, and Future

Flavonoids are known to exert anti-inflammatory effects. Their pharmacological activities have been proved using various in vitro and in vivo models. Although their action spectrum and potencies are not adequate to alleviate acute inflammatory disorders, they have the potential to treat chronic inflammatory diseases. Recent investigations have revealed that inflammatory processes are involved in many disease processes and conditions. Some examples are skin disorders, cartilage diseases, metabolic inflammatory diseases, and aging. The effects of flavonoids on these disorders have been examined. Several possible application areas for flavonoids have been studied. Local treatment of these disorders with flavonoids is favorable to avoid systemic transformation. In this review, the findings based on the experimental results from my laboratory are summarized and the future possibility of using flavonoids clinically is discussed.     

Tetrodotoxin and Its Analogues in the Pufferfish Arothron hispidus and A. nigropunctatus from the Solomon Islands: A Comparison of Their Toxin Profiles with the Same Species from Okinawa,Japan

Pufferfish poisoning has not been well documented in the South Pacific, although fish and other seafood are sources of protein in these island nations. In this study, tetrodotoxin (TTX) and its analogues in each organ of the pufferfish Arothron hispidus and A. nigropunctatus collected in the Solomon Islands were investigated using high resolution LC-MS. The toxin profiles of the same two species of pufferfish from Okinawa, Japan were also examined for comparison. TTXs concentrations were higher in the skin of both species from both regions, and relatively lower in the liver, ovary, testis, stomach, intestine, and flesh. Due to higher TTX concentrations (51.0 and 28.7 µg/g at highest) detected in the skin of the two species from the Solomon Islands (saxitoxin was <0.02 µg/g), these species should be banned from consumption. Similar results were obtained from fish collected in Okinawa, Japan: TTX in the skin of A. hispidus and A. nigropunctatus were 12.7 and 255 µg/g, respectively, at highest, and saxitoxin was also detected in the skin (2.80 µg/g at highest) and ovary of A. hispidus. TTX, 5,6,11-trideoxyTTX (with its 4-epi form), and its anhydro forms were the most abundant, and 11-oxoTTX was commonly detected in the skin.     

Cnidocyst structure and the biomechanics of discharge

The cnidocyst is the defining organelle of the cnidarians, used for capture of prey and defense. It consists of a cylindrical capsule, which releases a long tubule upon triggering. Cnidocysts develop inside a giant post-Golgi vesicle by a sequential accumulation of proteins from the Golgi apparatus. Traditionally three types of cnidocysts are distinguished: nematocysts, spirocysts, and ptychocysts. Here we focus on nematocysts, the prototypic cnidocyst and by far most diverse group of cnidocysts in this phylum. The mature nematocyst capsule comprises a collagenous polymer with remarkable biophysical properties, able to withstand an osmotic pressure of 150 bar. Release of the capsule and discharge is probably initiated by classical exocytosis. High-speed studies revealed the kinetics of discharge to be as short as 700 ns, generating an acceleration of 5,400,000 × g and a pressure of 7.7 GPa at the site of impact of the spines onto the prey. Thus nematocysts comprise a powerful molecular spring mechanism releasing energy stored in the wall polymer in the nanosecond time range. During the last few years, genomic, biochemical and structural studies have helped to unravel the molecular composition of the nematocyst supra-structure. Here we summarize these findings and present an integrative view of mechanical and molecular aspects that have shaped the nematocyst during evolution.     

Antifolate Agents Against Wild and Mutant Strains of Plasmodium falciparum

Plasmodium falciparum dihydrofolate reductase is an important target for antimalarial chemotherapy. The emergence of resistance has significantly reduced the efficacy of the classic antifolate drugs cycloguanil and pyrimethamine. In this paper we report new dihydrofolate reductase inhibitors identified using molecular modelling principles with the goal of designing new antifolate agents active against both wild and tetramutant dihydrofolate reductase strains three series of trimethoprim analogues were designed, synthesised and tested for biological activity. Pyrimethamine and cycloguanil have been reported to loose efficacy because of steric repulsion in the active site pocket produced due to mutation in Plasmodium falciparum dihydrofolate reductase. The synthesised molecules have sufficient flexibility to withstand this steric repulsion to counteract the resistance. The molecules have been synthesised by conventional techniques and fully characterised by spectroscopic methods. The potency of these molecules was evaluated by in vitro enzyme specific assays. Some of the molecules were active in micromolar concentrations and can easily be optimised to improve binding and activity.     

Combinatorial compound libraries for drug discovery: an ongoing challenge

Almost 20 years of combinatorial chemistry have emphasized the power of numbers, a key issue for drug discovery in the current genomic era, in which it has been estimated that there might be more than 10,000 potential targets for which it would be desirable to have small-molecule modulators. Combinatorial chemistry is best described as the industrialization of chemistry; the chemistry has not changed, just the way in which it is now carried out, which is principally by exploiting instrumentation and robotics coupled to the extensive use of computers to efficiently control the process and analyse the vast amounts of resulting data. Many researchers have contributed to the general concepts as well as to the technologies in present use. However, some interesting challenges still remain to be solved, and these are discussed here in the context of the application of combinatorial chemistry to drug discovery.