Multiple Toxic Effects Research Articles

Research Advances on Pathways of Nickel-Induced Apoptosis.

High concentrations of nickel (Ni) are harmful to humans and animals. Ni targets a number of organs and produces multiple toxic effects. Apoptosis is important in Ni-induced toxicity of the kidneys, liver, nerves, and immune system. Apoptotic pathways mediated by reactive oxygen species (ROS), mitochondria, endoplasmic reticulum (ER), Fas, and c-Myc participate in Ni-induced cell apoptosis. However, the exact mechanism of apoptosis caused by Ni is still unclear. Understanding the mechanism of Ni-induced apoptosis may help in designing measures to prevent Ni toxicity.

Nickel chloride (NiCl2)-caused inflammatory responses via activation of NF-κB pathway and reduction of anti-inflammatory mediator expression in the kidney

Nickel (Ni) or Ni compounds target a number of organs and produce multiple toxic effects. Kidney is the major organ for Ni accumulation and excretion. There are no investigations on the Ni- or Ni compounds-induced renal inflammatory responses in human beings and animals at present. Therefore, we determined NiCl2-caused alteration of inflammatory mediators, and functional damage in the broiler's kidney by the methods of biochemistry, immunohistochemistry and quantitative real-time polymerase chain reaction (qRT-PCR). Dietary NiCl2 in excess of 300 mg/kg caused the renal inflammatory responses that characterized by increasing mRNA expression levels of the pro-inflammatory mediators including tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8) and interleukin-18 (IL-18) via the activation of nucleic factor κB (NF-κB), and decreasing mRNA expression levels of the anti-inflammatory mediators including interleukin-2 (IL-2), interleukin-4 (IL-4) and interleukin-13 (IL-13). Concurrently, NiCl2 caused degeneration, necrosis and apoptosis of the tubular cells, which was consistent with the alteration of renal function parameters including elevated alkaline phosphatase (AKP) activity, and reduced activities of sodium-potassium adenosine triphosphatase (Na(+)/K(+)-ATPase), calcium adenosine triphosphatase (Ca(2+)-ATPase), lactic dehydrogenase (LDH), succinate dehydrogenase (SDH) and acid phosphatase (ACP) in the kidney. The above-mentioned results present that the activation of NF-κB pathway and reduction of anti-inflammatory mediator expression are main mechanisms of NiCl2-caused renal inflammatory responses and that the renal function is decreased or impaired after NiCl2-treated.

Histone Deacetylase Inhibitors Inhibit Rhabdomyosarcoma by Reactive Oxygen Species-Dependent Targeting of Specificity Protein Transcription Factors.

The two major types of rhabdomyosarcoma (RMS) are predominantly diagnosed in children, namely embryonal (ERMS) and alveolar (ARMS) RMS, and patients are treated with cytotoxic drugs, which results in multiple toxic side effects later in life. Therefore, development of innovative chemotherapeutic strategies is imperative, and a recent genomic analysis suggested the potential efficacy of reactive oxygen species (ROS)-inducing agents. Here, we demonstrate the efficacy of the potent histone deacetylase (HDAC) inhibitors, panobinostat and vorinostat, as agents that inhibit RMS tumor growth in vivo, induce apoptosis, and inhibit invasion of RD and Rh30 RMS cell lines. These effects are due to epigenetic repression of cMyc, which leads to decreased expression of cMyc-regulated miRs-17, -20a, and -27a; upregulation of ZBTB4, ZBTB10, and ZBTB34; and subsequent downregulation of Sp transcription factors. We also show that inhibition of RMS cell growth, survival and invasion, and repression of Sp transcription factors by the HDAC inhibitors are independent of histone acetylation but reversible after cotreatment with the antioxidant glutathione. These results show a novel ROS-dependent mechanism of antineoplastic activity for panobinostat and vorinostat that lies outside of their canonical HDAC-inhibitory activity and demonstrates the potential clinical utility for treating RMS patients with ROS-inducing agents.

Lead accumulation, oxidative damage and histopathological alteration in testes and accessory glands of freshwater crab, Sinopotamon henanense, induced by acute lead exposure

Lead (Pb) is one of the most toxic environmental pollutants and known to exert multiple toxic effects including gonadotoxic and spermiotoxic effects. In order to understand toxic mechanisms of lead (Pb) on the testes and the accessory glands of crabs, we investigated Pb accumulation in testes and accessory glands and the survival rate of sperms of freshwater crab, Sinopotamon henanense. The tissue damaging effects of Pb was also investigated by histopathological examination and analyses of antioxidant enzymes as well as lipid peroxidation. Crabs were exposed to different Pb concentrations (0, 3.675, 7.35, 14.7, 29.4 and 58.8mg/L) for 3, 5 and 7 days. The results showed that Pb levels in testes and accessory glands increased significantly following Pb exposure for 5 and 7 days in almost all treated groups, and survival rate of sperm decreased with increasing Pb concentrations at 5 and 7 days. Morphological changes identified histologically were discovered in testes, including a disordered arrangement of germ cells, a decreased number of sperm in the lumina of the seminiferous tubules, extensive necrosis in the germinal layer of the seminiferous tubules, etc. At the same time, histological abnormalities were discovered in accessory glands, the wall cells were separated from the basement membrane, and wall cells were missing partly. The activities of SOD, GPx and CAT in testes showed no statistically significant changes compared to the control for 3 days, and initially increased and subsequently decreased with increasing Pb concentrations at 5 and 7 days. The antioxidant enzyme activities in accessory glands initially increased and subsequently decreased with increasing Pb concentrations and Pb exposure. This was accompanied with an increase in malondialdehyde (MDA) content in a concentration-dependent manner. These results showed that acute Pb exposure led to a reduction of survival rate of sperm and harmful effects at the cellular level of crab testes and accessory glands, which are most likely linked to Pb-induced oxidative stress.

Efficacy of propranolol in infantile hemangioma

Hemangiomas, are the most common benign tumors of infancy. Despite their selflimited course, infantile capillary hemangiomas can cause local complications e.g. pain, ulceration, bleeding etc. The usual treatments include oral/intralesional steroids, alpha interferon, cytotoxins, pulsed dye laser and cosmetic surgery resection. These treatments are not free of multiple complications and toxic side effects. We report our experience with the use of propranolol in 2 children with haemangiomas along with review of relevant literature. Both the hemangioma cases promptly responded to low-dose oral propranolol. DOI: http://dx.doi.org/10.3329/bmjk.v47i1-2.22561 Bang Med J (Khulna) 2014; 47 : 32-35

Mechanism of antibacterial activity of copper nanoparticles

In a previous communication, we reported a new method of synthesis of stable metallic copper nanoparticles (Cu-NPs), which had high potency for bacterial cell filamentation and cell killing. The present study deals with the mechanism of filament formation and antibacterial roles of Cu-NPs in E. coli cells. Our results demonstrate that NP-mediated dissipation of cell membrane potential was the probable reason for the formation of cell filaments. On the other hand, Cu-NPs were found to cause multiple toxic effects such as generation of reactive oxygen species, lipid peroxidation, protein oxidation and DNA degradation in E. coli cells. In vitro interaction between plasmid pUC19 DNA and Cu-NPs showed that the degradation of DNA was highly inhibited in the presence of the divalent metal ion chelator EDTA, which indicated a positive role of Cu2+ ions in the degradation process. Moreover, the fast destabilization, i.e. the reduction in size, of NPs in the presence of EDTA led us to propose that the nascent Cu ions liberated from the NP surface were responsible for higher reactivity of the Cu-NPs than the equivalent amount of its precursor CuCl2; the nascent ions were generated from the oxidation of metallic NPs when they were in the vicinity of agents, namely cells, biomolecules or medium components, to be reduced simultaneously.

7,12-Dimethylbenz(a)anthracene-Induced Myelotoxicity Differs in Mice Selected for High or Low Acute Inflammatory Response

Polycyclic aromatic hydrocarbons, such as 7,12-dimethylbenz(a)anthracene (DMBA), are environmental pollutants that exert multiple toxic and carcinogenic effects. Studies showed that these effects are mediated by activation of the aryl hydrocarbon receptor (AhR) and modulated by allelic variants of Ahr gene. Here, we investigated the effects of DMBA treatment in the inflammatory response and bone marrow (BM) hematopoietic function of maximal acute inflammatory response (AIRmax) and minimal acute inflammatory response (AIRmin) heterogeneous mouse lines selected for high and low acute inflammatory responsiveness, respectively. The phenotypic selection resulted in the segregation of the Ahr(d) and Ahr(b1) alleles that confer low and high receptor ligand-binding affinity, respectively, in AIRmax and AIRmin mice. We observed a reduction in BM mature granulocyte population in AIRmin mice 24 hours after DMBA treatment while both blast and immature myeloid cells were increased. Proliferation and differentiation of BM myeloid cells in response to in vitro granulocyte-macrophage colony-stimulating factor stimulus were impaired in AIRmin-treated mice. These DMBA effects on myeloid BM cells (BMCs) affected the in vivo leukocyte migration to an inflammatory site induced by polyacrylamide beads (Biogel P-100, Bio-Rad, France) injection in AIRmin mice. On the other hand, these alterations were not observed in DMBA-treated AIRmax mice. These data indicate that DMBA affects myeloid cell differentiation and inflammatory response and Ahr(b1) allele in the genetic background of AIRmin mice contributes to this effect.

Cyclosporine Toxicity and Toxicokinetics Profiles in Renal Transplant Recipients

Background: Cyclosporine is the backbone of immunosuppression in kidney transplantation. However, it leads to multiple toxic effects, most of which are dose-dependent. In this respect, the quality of renal functions is undoubtedly linked to cyclosporine drug levels. Objective: To evaluate the association among cyclosporine trough-peak levels, dosage and its toxic effects. Methods and materials: In 102 kidney transplant recipients, serum cyclosporine trough-peak levels, serum creatinine, blood urea, blood urea and nitrogen, serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase were measured periodically from the beginning of May, 2011 until the end of July, 2012. The relationships among previous laboratory parameters were detected in relation to the prevalence of toxic cyclosporine effects. Results: Consequently, the patients are with renal transplantations; concentrations of cyclosporine trough that can get lowered safely towards the range of 150-200 ng/ml, added by minimal toxic cyclosporine effects without increased risk for graft rejection. Conclusion: The findings of this study showed the detrimental toxic effects of high cyclosporine concentrations and the efficiency of low cyclosporine trough/peak levels in maintaining of an efficient immunosuppressive effect plus a minimal toxic cyclosporine effects and positive therapeutic outcomes in the renal transplant patients.

Effects of tris(1,3-dichloro-2-propyl) phosphate and triphenyl phosphate on receptor-associated mRNA expression in zebrafish embryos/larvae

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and triphenyl phosphate (TPP) are frequently detected in biota, including fish. However, knowledge of the toxicological and molecular effects of these currently used flame retardants is limited. In the present study, an in vivo screening approach was developed to evaluate effects of TDCPP and TPP on developmental endpoints and receptor-associated expression of mRNA in zebrafish embryos/larvae. Exposure to TDCPP or TPP resulted in significantly smaller rates of hatching and survival, in dose- and time-dependent manners. The median lethal concentration (LC50) was 7.0mg/L for TDCPP and 29.6mg/L for TPP at 120 hour post-fertilization (hpf). Real-time PCR revealed alterations in expression of mRNAs involved in aryl hydrocarbon receptors (AhRs)-, peroxisome proliferator-activated receptor alpha (PPARα)-, estrogenic receptors (ERs)-, thyroid hormone receptor alpha (TRα)-, glucocorticoid receptor (GR)-, and mineralocorticoid receptor (MR)-centered gene networks. Exposure to positive control chemicals significantly altered abundances of mRNA in corresponding receptor-centered gene networks, a result that suggests that it is feasible to use zebrafish embryos/larvae to evaluate effects of chemicals on mRNA expression in these gene networks. Exposure to TDCPP altered transcriptional profiles in all six receptor-centered gene networks, thus exerting multiple toxic effects. TPP was easily metabolized and its potency to change expression of mRNA involved in receptor-centered gene networks was weaker than that of TDCPP. The PPARα- and TRα-centered gene networks might be the primary pathways affected by TPP. Taken together, these results demonstrated that TDCPP and TPP could alter mRNA expression of genes involved in the six receptor-centered gene networks in zebrafish embryos/larvae, and TDCPP seemed to have higher potency in changing the mRNA expression of these genes.

Heavy metal-induced oxidative damage, defense reactions, and detoxification mechanisms in plants

Heavy metal (HMs) contamination is widespread globally due to anthropogenic, technogenic, and geogenic activities. The HMs exposure could lead to multiple toxic effects in plants by inducing reactive oxygen species (ROS), which inhibit most cellular processes at various levels of metabolism. ROS being highly unstable could play dual role (1) damaging cellular components and (2) act as an important secondary messenger for inducing plant defense system. Cells are equipped with enzymatic and non-enzymatic defense mechanisms to counteract this damage. Some are constitutive and others that are activated only when a stress-specific signal is perceived. Enzymatic scavengers of ROS include superoxide dismutase, catalase, glutathione reductase, and peroxidase, while non-enzymatic antioxidants are glutathione, ascorbic acid, α-tocopherol, flavonoids, anthocyanins, carotenoids, and organic acids. The intracellular and extracellular chelation mechanisms of HMs are associated with organic acids such as citric, malic and oxalic acid, etc. The important mechanism of detoxification includes metal complexation with glutathione, amino acids, synthesis of phytochelatins and sequestration into the vacuoles. Excessive stresses induce a cascade, MAPK (mitogen-activated protein kinase) pathway and synthesis of metal-detoxifying ligands. Metal detoxification through MAPK cascade and synthesis of metal-detoxifying ligands will be of considerable interest in the field of plant biotechnology. Further, the photoprotective roles of pigments of xanthophylls cycle under HMs stress were also discussed.

Toxicity burden score: a novel approach to summarize multiple toxic effects

Toxicity data from cancer trials are summarized into a single outcome, dose-limiting toxicity (DLT), which does not account for multiple lower grade toxic effects nor differentiates between toxicity types and gradations within DLT. Toxicity data were summarized into a toxicity burden score (TBS) using a weighted sum. The severity weights were estimated via regression using historical data. We demonstrated the method using historical data from a bortezomib trial and illustrated the advantages of defining DLT based on TBS in a simulated dose-finding trial. The estimated weights were 0.17, 0.40 and 0.85 for grade 1/2, grade 3 and grade 4 platelets, respectively; 0.19, 0.64, 1.03 and 2.53 for grade 1, 2, 3 and 4 neuropathy, respectively and 0.17 for each grade 3 or higher nonhematologic toxic effects unrelated to treatment. In the simulated trial, the probability of selecting doses above the maximum tolerated dose decreased when using the DLT defined based on TBS. TBS is a feasible approach to summarize toxicity. It includes information from the grades and types of multiple toxic effects and can be applied in all phases of drug development. Further efforts should focus on validating the method in a large prospective study before applying it in practice.

Molecular Mechanisms of Environmental Organotin Toxicity in Mammals

Organotins such as tributyltin are suspected of having multiple toxic effects in mammals, in addition to their endocrine-disrupting function. Endogenous organotin concentrations in human blood range from a few to a few hundred nM. In this review, we summarize recent findings on the mechanisms of toxicity of environmental organotins such as tributyltin (TBT) and triphenyltin (TPT) in mammals. TBT and TPT are potent inhibitors of mitochondrial ATP synthase, and a recent study suggests that TBT binds directly to ATP synthase. Organotins disturb steroid biosynthesis and degradation. TBT and TPT are dual agonists of retinoid X receptor (RXR) and peroxisome proliferator-activated receptor γ (PPARγ); they also induce the differentiation of adipocytes in vitro and in vivo, probably through PPARγ activation, suggesting that they may work as obesogens. Environmental organotins are also neurotoxic; they induce behavioral abnormality and are toxic to the developing central nervous system. In vitro studies have shown that organotins induce intracellular Ca(2+) elevation and glutamate excitotoxicity. Recently, it was reported that endogenous levels of TBT decrease expression of 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic acid (AMPA) receptor subunit GluR2, leading to neuronal vulnerability. Most of the experimental studies have employed organotins at concentrations of µM order, and it remains important to clarify the molecular mechanisms of events induced by endogenous levels of environmental organotins.

Sodium arsenite and cadmium chloride induction of proteasomal inhibition and HSP accumulation in Xenopus laevis A6 kidney epithelial cells

Sodium arsenite (NA) and cadmium chloride (CdCl2) are relatively abundant environmental toxicants that have multiple toxic effects including carcinogenesis, dysfunction of gene regulation and DNA and protein damage. In the present study, treatment of Xenopus laevis A6 kidney epithelial cells with concentrations of NA (20–30μM) or CdCl2 (100–200μM) that induced HSP30 and HSP70 accumulation also produced an increase in the relative levels of ubiquitinated protein. Actin protein levels were unchanged in these experiments. In time course experiments, the levels of ubiquitinated protein and HSPs increased over a 24h exposure to NA or CdCl2. Furthermore, treatment of cells with NA or CdCl2 reduced the relative levels of proteasome chymotrypsin (CT)-like activity compared to control. Interestingly, pretreatment of cells with the HSP accumulation inhibitor, KNK437, prior to NA or CdCl2 exposure decreased the relative levels of ubiquitinated protein as well as HSP30 and HSP70. A similar finding was made with ubiquitinated protein induced by proteasomal inhibitors, MG132 and celastrol, known to induce HSP accumulation in A6 cells. However, the NA- or CdCl2-induced decrease in proteasome CT-like activity was not altered by KNK437 pretreatment. This study has shown for the first time in poikilothermic vertebrates that NA and CdCl2 can inhibit proteasomal activity and that there is a possible association between HSP accumulation and the mechanism of protein ubiquitination.

Oral propranolol as a new treatment for facial infantile hemangioma: case report

Hemangiomas are the most common benign tumors of infancy. Despite their self-limited course, infantile capillary hemangiomas can impair vital or sensory functions as vision and cause cosmetic deformity. The usual treatments include oral/intralesional steroids, alpha interferon, cytotoxins, pulsed dye laser and cosmetic surgery resection. These treatments are not free of multiple complications and toxic side effects. This report describes the case of a 3-month-old female baby with progressively increasing hemangioma of the left upper eyelid impinging over the visual field. The hemangioma promptly responded to low-dose oral propranolol. A clinical response was noticed few days after the beginning of the treatment, with regression to 1/4 of its original size in 45 days of treatment, and to less than 1/10 after 8 months, free of any major side effects.

Copper-induced oxidative damage, antioxidant response and genotoxicity in Lycopersicum esculentum Mill. and Cucumis sativus L.

Adequate copper (Cu(2+)) concentrations are required for plants; however, at higher concentrations it can also cause multiple toxic effects. In the present study, lipid peroxidation, hydrogen peroxide levels as well as ascorbate peroxidase (APX: EC 1/11/1/11) and catalase (CAT: EC 1.11.1.6) activities were determined in Lycopersicum esculentum Mill. and Cucumis sativus L. seedlings after 7-day exposure to copper sulfate. In addition, DNA damage in these two crops was assessed by measuring micronucleus (MN) frequency and tail moments (TM) as determined by Comet assay. Inhibitory copper concentrations (EC(50): 30 and 5.5ppm for L. esculentum and C. sativus, respectively) were determined according to dose-dependent root inhibition curves, and EC(50) and 2×EC(50) were applied. Malondialdehyde (MDA) and H(2)O(2) levels significantly increased in all groups studied. CAT activity increased in treatment groups of C. sativus. APX activity increased in L. esculentum seedlings due to 2×EC(50) treatment. Reductions in mitotic indices (MI) represented Cu(2+)dependent root growth inhibition in all treatment groups studied. According to TMs and MN frequencies, copper exposure induced significant DNA damage (p<0.05) in all study groups, whereas the DNA damage induced was dose dependent in C. sativus roots. In conclusion, Cu(2+)induced oxidative damage, elevations in H(2)O(2) levels and alterations in APX and CAT activities, as well as significant DNA damage in nuclei of both study groups. To our knowledge, this is the first comparative and comprehensive study demonstrating the effects of copper on two different plant species at relevant cytotoxic concentrations at both biochemical and genotoxicity levels with multiple end points.

Membrane Biophysics and Mechanics in Alzheimer's Disease

Alzheimer's disease is a chronic neurodegenerative disorder characterized by neuronal loss, cerebrovascular inflammation, and accumulation of senile plaques in the brain parenchyma and cerebral blood vessels. Amyloid-beta peptide (Abeta), a major component of senile plaques, has been shown to exert multiple toxic effects to neurons, astrocytes, glial cells, and brain endothelium. Oligomeric Abeta can disturb the structure and function of cell membranes and alter membrane mechanical properties, such as membrane fluidity and molecular order. Much of these effects are attributed to their capability to trigger oxidative stress and inflammation. In this review, we discuss the effects of Abeta on neuronal cells, astrocytes, and cerebral endothelial cells with special emphasis on cell membrane properties and cell functions.

Toxicity of lindane (γ-hexachloroxiclohexane) in Sparus aurata, Crassostrea angulata and Scrobicularia plana

The purpose of the present study was to research the sublethal and/or lethal effects produced by the exposure of fish and shellfish to the γ isomer of lindane, γ-hexachlorocyclohexane (γ-HCH). The teleostean fish Sparus aurata and the shellfish Crassostrea angulata and Scrobicularia plana, were exposed to 16 μ g/L of lindane for 15 days. Samples of different fish (liver, kidney and gills) and shellfish (gills, gut, digestive gland and mantle) tissues were extracted and processed for histopathological observations. Although mortality was not detected during the bioassay, sublethal effects (histopathological alterations) were observed. Vacuolization in the liver cells and lamellar fusion in gills from exposed fish were observed. Disorganization of normal gill structure, epithelial desquamation with the disappearance of apical ciliature in intestine, and inflammatory response in mantle from exposed shellfish were also observed. Thus, it can be concluded that the lindane concentration employed in the present research did not produce lethal effects in the exposed organisms but it caused sublethal effects. Lindane has time-dependent multiple toxic effects in S. aurata, C. angulata and S. plana, which were more severe at the end of the experimental time. The toxicological implications arising from these results are subjects for further multiconcentration tests dealing with lethal responses (mortality) or with sublethal responses (cellular/molecular biomarkers) of the aforementioned species.

S16-02 Effects of smoking, alcohol and illicit drug misuse on maternal and child outcomes and acute management of treatment

Smoking, alcohol and illicit drug misuse during pregnancy lead to toxic harmful consequences for mother and especially for the fetus, neonate or child. In case of misuse of illicit substances pregnant women mostly suffer from polytoxicomania (3 substances and more) and the misuse of illicit substances is often accompanied by severe smoking and drinking of alcohol. Therefore it is often difficult to methodologically differentiate the single toxic effects. Basing on this knowledge in the presentation a view on the single toxic and /or chronic effects of addictive drugs will be given.1.To clarify single toxic effects of the addictive drugs diagnostic procedure about regulary and/ or ecstatical consume and the diagnose of abuse or dependence acc. to DSMIV or ICD 10 and the analysis of relapse behaviour for each substance should be done.2.The toxic effects of the different substances in pregnancy will be reported. Nearly al addictive substances (nicotine (+CO, +tar), alcohol, THC, psychostimulants, heroine) go into placenta and thereby have multiple toxic effects like f.e. decreased perfusion and infarct of the placenta leading f.e. to intrauterine retardation of growth, premature detaching of placenta, premature birth, to deformities, various later heavy postpartal effects (lung and breath diseases, sudden death, fetal alcohol syndrome, neurological dysdevelopment, cardial malformations, learning disturbances, ADHD etc). The toxic effects of the various substances will be differentiated so far it is possible.3.The different therapeutic approach of the various addictive drugs during pregnany (withdrawl treatment, opioid substitution) will be discussed.

Multiple toxic effects of low-dose methotrexate in a patient treated for psoriasis

A case of toxicity encountered with low-dose methotrexate therapy is discussed. A 59-year-old African American woman receiving long-term therapy for psoriasis came to the hospital with painful ulcers, difficulty swallowing, cutaneous lesions, and acute renal failure. Her medical history included type 2 diabetes mellitus, hypertension, coronary artery disease, morbid obesity, and psoriasis. On admission, the patient looked ill and had a low-grade fever; maculopapular skin lesions; and bullae and vesicles in her mouth and on her hands, legs, groin, and buttocks. With the exception of carvedilol, all home medications, including methotrexate, were discontinued. A complete medication history revealed that the patient had been taking methotrexate 2.5 mg daily, instead of 2.5 mg three times weekly as prescribed. This error translated into an estimated cumulative dose of 360 mg, nearly twice the prescribed amount. There were no clinically significant drug-drug interactions noted among her prescribed medications; however, the patient did report increased ibuprofen use secondary to the painful ulcerations in the previous few months. Leucovorin 15 mg i.v. every six hours was initiated along with additional supportive care. Skin and mucosal lesions, as well as her pain, had dramatically improved on day 5 of hospitalization. The patient was discharged after a six-day hospitalization and was provided with leucovorin 15 mg orally ever day for seven additional days until rheumatology follow-up. The patient was instructed to avoid any future methotrexate therapy. A patient who erroneously took oral methotrexate daily rather than thrice weekly for psoriasis developed multiple manifestations of methotrexate toxicity.

Presenilin 1/γ-Secretase Is Associated with Cadmium-Induced E-Cadherin Cleavage and COX-2 Gene Expression in T47D Breast Cancer Cells

Cadmium is a heavy metal that has multiple toxic effects on human health and has been classified as a human carcinogen. E-cadherin is a major target of cadmium; however, the roles of E-cadherin and cadmium and the mechanisms of tumor progression remain to be defined. Here, we demonstrate that cadmium increases E-cadherin processing via a gamma-secretase in the T47D breast cancer cell lines. This presenilin 1 (PS1)/gamma-secretase-dependent cleavage of E-cadherin was accompanied by changes in reactive oxygen species or calcium. E-cadherin cleavage was blocked by a PS1 dominant-negative mutant, gamma-secretase inhibitors [N-[N-(3,5-Difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester (DAPT) and L-685,486], antioxidants (N-acetylcysteine and Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachloride), or a calcium chelating drug 1,2-bis(o-Aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl) ester. Immunofluorescence analysis confirmed the disappearance of E-cadherin staining at the cell surface. Those inhibitors attenuated cadmium-induced cytotoxicity. Additionally, cadmium treatment increased cell motility and invasion ability, which was abated by DAPT. Interestingly, cyclooxygenase-2 (COX-2) expression induced by cadmium was also inhibited by DAPT. The cadmium-induced cell motility and invasion ability were inhibited by a COX-2 inhibitor, NS398. Our data indicate a novel molecular mechanism that links cytotoxicity of cadmium and disrupted E-cadherin processing to adherens junctions; cadmium induces COX-2 expression via gamma-secretase, which increases cell motility and invasion ability. Understanding the downstream signaling cascades of cadmium that promote tumor progression might be a key to the development of novel therapeutic strategies.