Acute Neurotoxicity Research Articles

OATP1B2 deficiency protects against paclitaxel-induced neurotoxicity.

Paclitaxel is among the most widely used anticancer drugs and is known to cause a dose-limiting peripheral neurotoxicity, the initiating mechanisms of which remain unknown. Here, we identified the murine solute carrier organic anion-transporting polypeptide B2 (OATP1B2) as a mediator of paclitaxel-induced neurotoxicity. Additionally, using established tests to assess acute and chronic paclitaxel-induced neurotoxicity, we found that genetic or pharmacologic knockout of OATP1B2 protected mice from mechanically induced allodynia, thermal hyperalgesia, and changes in digital maximal action potential amplitudes. The function of this transport system was inhibited by the tyrosine kinase inhibitor nilotinib through a noncompetitive mechanism, without compromising the anticancer properties of paclitaxel. Collectively, our findings reveal a pathway that explains the fundamental basis of paclitaxel-induced neurotoxicity, with potential implications for its therapeutic management.

Midazolam Efficacy Against Acute Hydrogen Sulfide-Induced Mortality and Neurotoxicity

Hydrogen sulfide (H2S) is a colorless, highly neurotoxic gas. It is not only an occupational and environmental hazard but also of concern to the Department of Homeland Security for potential nefarious use. Acute high-dose H2S exposure causes death, while survivors may develop neurological sequelae. Currently, there is no suitable antidote for treatment of acute H2S-induced neurotoxicity. Midazolam (MDZ), an anti-convulsant drug recommended for treatment of nerve agent intoxications, could also be of value in treating acute H2S intoxication. In this study, we tested the hypothesis that MDZ is effective in preventing/treating acute H2S-induced neurotoxicity. This proof-of-concept study had two objectives: to determine whether MDZ prevents/reduces H2S-induced mortality and to test whether MDZ prevents H2S-induced neurological sequelae. MDZ (4 mg/kg) was administered IM in mice, 5 min pre-exposure to a high concentration of H2S at 1000 ppm or 12 min post-exposure to 1000 ppm H2S followed by 30 min of continuous exposure. A separate experiment tested whether MDZ pre-treatment prevented neurological sequelae. Endpoints monitored included assessment of clinical signs, mortality, behavioral changes, and brain histopathological changes. MDZ significantly reduced H2S-induced lethality, seizures, knockdown, and behavioral deficits (p < 0.01). MDZ also significantly prevented H2S-induced neurological sequelae, including weight loss, behavior deficits, neuroinflammation, and histopathologic lesions (p < 0.01). Overall, our findings show that MDZ is a promising drug for reducing H2S-induced acute mortality, neurotoxicity, and neurological sequelae.

Evaluation of multiwalled carbon nanotubes toxicity in two fish species

Carbon Nanotubes are among the most promising materials for the technology industry. Their unique physical and chemical proprieties may reduce the production costs and improve the efficiency of a large range of products. However, the same characteristics that have made nanomaterials interesting for industry may be responsible for inducing toxic effects on the aquatic organisms. Since the carbon nanotubes toxicity is still a controversial issue, we performed tests of acute and subchronic exposure to a commercial sample of multiwalled carbon nanotubes in two fish species, an exotic model (Danio rerio) and a native one (Astyanax altiparanae). Using the alkaline version of the comet assay on erythrocytes and the piscine micronucleous, also performed on erythrocytes, it was verified that the tested carbon nanotubes sample did not generate apparent genotoxicity by means of single/double DNA strand break or clastogenic/aneugenic effects over any of the species, independently of the exposure period. Although, our findings indicate the possibility of the occurrence of CNTs-DNA crosslinks. Apparently, the sample tested induces oxidative stress after subchronic exposure as shown by activity of superoxide dismutase and catalase. The data obtained by the activity levels of acetylcholinesterase suggests acute neurotoxicity in Astyanax altiparanae and subchronic neurotoxicity in Danio rerio.

QSAR Modeling of Acute Neurotoxicity of Some Organic Solvents with Respect to Rodents

Using literature data analysis, the regression models of acute sublethal neurotoxicity of 47 organic solvents with respect to rats and mice have been developed. To construct the models, we used linear regression, random forest and support vector machines approaches. The linear regression equations were selected as the best models. They are designed on the basis of four molecular descriptors: polarizability, sum of positive atom charges, sum of proton acceptor descriptors and dipole moment. The developed models have good descriptive and predictive ability and clear physicochemical interpretation.

Propofol Alters Long Non-Coding RNA Profiles in the Neonatal Mouse Hippocampus: Implication of Novel Mechanisms in Anesthetic-Induced Developmental Neurotoxicity

Background: Propofol induces acute neurotoxicity (e.g., neuroapoptosis) followed by impairment of long-term memory and learning in animals. However, underlying mechanisms remain largely unknown. Long non-coding RNAs (lncRNAs) are found to participate in various pathological processes. We hypothesized that lncRNA profile and the associated signaling pathways were altered, and these changes might be related to the neurotoxicity observed in the neonatal mouse hippocampus following propofol exposure. Methods: In this laboratory experiment, 7-day-old mice were exposed to a subanesthetic dose of propofol for 3 hours, with 4 animals per group. Hippocampal tissues were harvested 3 hours after propofol administration. Neuroapoptosis was analyzed based on caspase 3 activity using a colorimetric assay. A microarray was performed to investigate the profiles of 35,923 lncRNAs and 24,881 messenger RNAs (mRNAs). Representative differentially expressed lncRNAs and mRNAs were validated using reverse transcription quantitative polymerase chain reaction. All mRNAs dysregulated by propofol and the 50 top-ranked, significantly dysregulated lncRNAs were subject to bioinformatics analysis for exploring the potential mechanisms and signaling network of propofol-induced neurotoxicity. Results: Propofol induced neuroapoptosis in the hippocampus, with differential expression of 159 lncRNAs and 100 mRNAs (fold change ± 2.0, P< 0.05). Bioinformatics analysis demonstrated that these lncRNAs and their associated mRNAs might participate in neurodegenerative pathways (e.g., calcium handling, apoptosis, autophagy, and synaptogenesis). Conclusion: This novel report emphasizes that propofol alters profiles of lncRNAs, mRNAs, and their cooperative signaling network, which provides novel insights into molecular mechanisms of anesthetic-induced developmental neurodegeneration and preventive targets against the neurotoxicity.

Endothelial Activation and Blood-Brain Barrier Disruption in Neurotoxicity after CD19 CAR-T Cell Immunotherapy

CD19 chimeric antigen receptor (CAR)-modified T cell therapy has produced impressive results in patients (pts) with CD19+B cell malignancies; however, treatment can be complicated by neurologic adverse events (AEs). The presentation and pathogenesis of neurotoxicity (NT) are incompletely understood.We report a clinical and pathologic study evaluating NT in 133 B-ALL, NHL and CLL pts treated with lymphodepletion chemotherapy and CD19 CAR-T cells (NCT01865617). Neurologic AEs were observed in 53 of 133 pts (40%; 19% grade [gr] 1-2; 16% gr 3; 2% gr 4; 3% gr 5). Most neurologic AEs were reversible. Delirium, headache, and language disturbances were the most frequently observed neurologic AEs, presenting in 66%, 55%, and 34% of pts with NT, respectively. Multivariable analysis showed that higher burden of malignant B cells in marrow, lymphodepletion with cyclophosphamide and fludarabine, and higher infused CAR-T cell dose were associated with increased risk of NT and cytokine release syndrome (CRS).The severity of NT correlated with higher peak concentrations of cytokines that may activate endothelial cells (EC), such as IL-6, IFN-γ, and TNF-α. Pts who developed gr ≥3 NT had more severe CRS with higher CAR-T cell counts in blood and evidence of vascular dysfunction. In severe NT, hypofibrinogenemia with elevated PT, aPTT, and d-dimer were consistent with EC activation. We confirmed in vivo EC activation during NT by demonstrating high concentrations of serum angiopoietin-2 (Ang-2) and von Willebrand Factor (VWF), which are released from Weibel-Palade bodies on EC activation. In vitro, serum from pts with NT induced activation and VWF release from human umbilical vein ECs (HUVECs), which suggests that the finding of a reduced fraction of high molecular weight VWF multimers in vivo during gr ≥4 NT results from consumption on platelets and sequestration on activated EC. Consistent with this explanation, we found reduced activity of the VWF-cleaving protease ADAMTS13 relative to VWF levels and more severe thrombocytopenia in pts with gr ≥4 NT.We considered that cytokine-induced EC activation might alter the integrity of the blood-brain barrier (BBB) during NT. During severe NT, CSF analyses demonstrated increased permeability of the BBB to protein and leukocytes, including CAR-T cells. The gradient between serum and CSF cytokines observed before lymphodepletion was lost during acute NT, consistent with inability of the BBB to shield the CNS from high concentrations of plasma cytokines. Brain vascular pericytes (BVP) play a critical role in vascular and BBB support, and when exposed to high TNF-α or IFN-γ concentrations BVP exhibited stress (increased cleaved caspase-3 and reduced PDGFRβ) and secreted IL-6 and VEGF, further promoting EC activation and BBB permeability.Neuropathologic examination of the brain of a patient with fatal NT demonstrated disrupted endothelium by CD31 immunohistochemistry and EC activation was confirmed by intravascular VWF binding and CD61+ platelet microthrombi. Further evidence of breach of the BBB included red blood cell extravasation from multiple vessels, vascular lesions with karyorrhexis, perivascular CD8+ T cell infiltration, and fibrinoid vessel wall necrosis. CAR-T cells were detected in the CNS.We investigated strategies to reduce the risks of severe NT. Logistic probability curves demonstrated that reduction in CAR-T cell dose to reduce the peak in vivo CAR-T cell blood count was associated with reduced risk of NT, but that the narrow therapeutic index of this approach would lead to loss of anti-tumor efficacy. To maintain CAR-T cell peak counts in blood, we developed a strategy to identify pts early after CAR-T cell infusion who might be at risk of subsequent severe NT and could be candidates for early intervention. Classification tree modeling demonstrated that in the first 36 hours after CAR-T cell infusion pts with fever ≥38.9°C, serum IL-6 ≥16 pg/mL, and MCP-1 ≥1343.5 pg/mL were at high risk of subsequent gr ≥4 NT (sensitivity 100%; specificity 94%). We also investigated whether pts with pre-existing endothelial activation were at higher risk of NT. Before lymphodepletion, pts who developed gr ≥4 NT had higher Ang-2:Ang-1 ratios than those with gr ≤3 NT, indicating that endothelial activation before lymphodepletion or CAR-T cell infusion may be a risk factor for NT that identifies pts who would benefit from a modified treatment regimen. DisclosuresTurtle:Adaptive Biotechnologies: Other: Advisory board; Bluebird Bio: Other: Advisory board; Gilead Sciences: Other: Advisory board; Precision Biosciences: Other: Advisory board; Celgene: Other: Advisory board; Juno Therapeutics: Other: Advisory board, Patents & Royalties, Research Funding. Liles:Juno Therapeutics: Consultancy, Other: Advisory board. Li:Juno Therapeutics: Employment, Equity Ownership. Yeung:Gilead: Research Funding. Riddell:Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding. Maloney:Celgene: Other: Advisory board; Kite Pharmaceuticals: Other: Advisory board; Juno Theraapeutics: Other: Advisory board, Patents & Royalties, Research Funding; Roche/Genetech: Other: Advisory board.

Occurrence of cyclic imines in European commercial seafood and consumers risk assessment

Cyclic imines constitute a quite recently discovered group of marine biotoxins that act on neural receptors and that bioaccumulate in seafood. They are grouped together due to the imino group functioning as their common pharmacore, responsible for acute neurotoxicity in mice. Cyclic imines (CIs) have not been linked yet to human poisoning and are not regulated in the European Union (EU), although the European Food Safety Authority (EFSA) requires more data to perform conclusive risk assessment for consumers. Several commercial samples of bivalves including raw and processed samples from eight countries (Italy, Portugal, Slovenia, Spain, Ireland, Norway, The Netherlands and Denmark) were obtained over 2 years. Emerging cyclic imine concentrations in all the samples were analysed on a LC-3200QTRAP and LC-HRMS QExactive mass spectrometer. In shellfish, two CIs, pinnatoxin G (PnTX-G) and 13-desmethylspirolide C (SPX-1) were found at low concentrations (0.1–12µg/kg PnTX-G and 26–66µg/kg SPX-1), while gymnodimines and pteriatoxins were not detected in commercial (raw and processed) samples. In summary, SPX-1 (n: 47) and PnTX-G (n: 96) were detected in 9.4% and 4.2% of the samples, respectively, at concentrations higher than the limit of quantification (LOQ), and in 7.3% and 31.2% of the samples at concentrations lower than the LOQ (25µg/kg for SPX-1 and 3µg/kg for PnTX-G), respectively. For the detected cyclic imines, the average exposure and the 95th percentile were calculated. The results obtained indicate that it is unlikely that a potential health risk exists through the seafood diet for CIs in the EU. However, further information about CIs is necessary in order to perform a conclusive risk assessment.

Axonal excitability changes and acute symptoms of oxaliplatin treatment: In vivo evidence for slowed sodium channel inactivation

ObjectiveNeurotoxicity is the most frequent dose-limiting side effect of the anti-cancer agent oxaliplatin, but the mechanisms are not well understood. This study used nerve excitability testing to investigate the pathophysiology of the acute neurotoxicity. MethodsQuestionnaires, quantitative sensory tests, nerve conduction studies and nerve excitability testing were undertaken in 12 patients with high-risk colorectal cancer treated with adjuvant oxaliplatin and in 16 sex- and age-matched healthy controls. Examinations were performed twice for patients: once within 3 days after oxaliplatin treatment (post-infusion examination) and once shortly before the following treatment (recovery examination). ResultsThe most frequent post-infusion symptoms were tingling paresthesias and cold allodynia. The most prominent nerve excitability change was decreased superexcitability of motor axons which correlated with the average intensity of abnormal sensations (Spearman Rho = 0.80, p < .01). The motor nerve excitability changes were well modeled by a slowing of sodium channel inactivation, and were proportional to dose/m2 with a half-life of about 10d. ConclusionsOxaliplatin induces reversible slowing of sodium channel inactivation in motor axons, and these changes are closely related to the reversible cold allodynia. However, further studies are required due to small sample size in this study. SignificanceNerve excitability data provide an index of sodium channel dysfunction: an objective biomarker of acute oxaliplatin neurotoxicity.

Neurotoxicité aiguë secondaire au méthotrexate et « pseudo-stroke » syndrome

Treatment of acute lymphoblastic leukemia requires high-dose systemic and/or intrathecal methotrexate to prevent and/or treat central nervous system disorders. Acute neurotoxicity of methotrexate, of unknown etiopathogenesis, is characterized by the polymorphism of clinical manifestations, responsible for a potentially harmful diagnostic delay in these immunosuppressed patients. We describe five episodes of transient acute leukoencephalopathy mimicking a stroke, reported in the literature as "pseudo-stroke syndrome". Neurologic symptoms occurred 3-10days after IV or IT methotrexate and manifested as aphasia and alternating sensorimotor deficit. The fluctuating symptomatology regressed completely within a few days. Brain MRI, which is essential for diagnosis, demonstrated early white matter diffusion restriction in the affected cerebral area. These anomalies disappeared in oneweek, while hyperintense T2FLAIR signals developed in the corresponding brain areas. The long-term progression of these pseudo-stroke patients was favorable, without any therapeutic modification. Nevertheless, the involvement of transient acute leukoencephalopathy episodes in the progressive onset of neuro-cognitive disorders is discussed.

A comparative study of anticonvulsant effect of phenytoin and lamotrigine in albino mice

Background: The anticonvulsant activity of lamotrigine has been extensively studied and its role is established. Lamotrigine have shown recently to be useful in various epileptic seizures. Since antiepileptic drugs are used for longer duration, so less toxic drugs should be chosen. So, in the present study the Lamotrigine has been chosen to compare the anticonvulsant action, effectiveness, toxicity and lethal dose of the drug used in the study keeping the phenytoin as a standard drug.Methods: The present study has been carried out in the Department of Pharmacology, Darbhanga Medical College, Laheriasarai. Induction of seizure with the help of electro-convulsiometer in albino mice was done followed by the observation of the anti-convulsant activity of lamotrigine in comparison with phenytoin sodium was made. Side effects or toxicity of the drugs used (Acute neurotoxicity) was observed.Results: Lamotrigine caused lower mortality in comparison to phenytoin for the same dose ranges. The anticonvulsant properties of Lamotrigine were compared with phenytoin and the effect has been found to be satisfactory. Lamotrigine protected experimentally induced grand mal seizure and was observed to be ineffective against experimentally induced petit mal seizure. The ED 50 of Lamotrigine was found to be higher and the toxic dose was also higher in comparision with standard drugs. The protective index of lamotrigine was found to be less than that of phenytoin. Margin of safety of the drug was found to be more due to their shorter protective index than that of phenytoin.Conclusions: Lamotrigine can be used clinically as anticonvulsant in Grandmal type of epilepsy but not in Petitmal epilepsy, and has equivocal anticonvulsant effect but slightly less toxicity to phenytoin but further elaborate screening of the drug by various experiments is needed to come to a precise conclusion.

Modelling acrylamide acute neurotoxicity in zebrafish larvae

Acrylamide (ACR), a type-2 alkene, may lead to a synaptopathy characterized by ataxia, skeletal muscles weakness and numbness of the extremities in exposed human and laboratory animals. Currently, only the mildly affected patients undergo complete recovery, and identification of new molecules with therapeutic bioactivity against ACR acute neurotoxicity is urgently needed. Here, we have generated a zebrafish model for ACR neurotoxicity by exposing 5 days post-fertilization zebrafish larvae to 1 mM ACR for 3 days. Our results show that zebrafish mimics most of the pathophysiological processes described in humans and mammalian models. Motor function was altered, and specific effects were found on the presynaptic nerve terminals at the neuromuscular junction level, but not on the axonal tracts or myelin sheath integrity. Transcriptional markers of proteins involved in synaptic vesicle cycle were selectively altered, and the proteomic analysis showed that ACR-adducts were formed on cysteine residues of some synaptic proteins. Finally, analysis of neurotransmitters profile showed a significant effect on cholinergic and dopaminergic systems. These data support the suitability of the developed zebrafish model for screening of molecules with therapeutic value against this toxic neuropathy.

Long-Term Clinical Safety of High-Dose Proton Radiation Therapy Delivered With Pencil Beam Scanning Technique for Extracranial Chordomas and Chondrosarcomas in Adult Patients: Clinical Evidence of Spinal Cord Tolerance

To assess the radiation dose tolerance of the spinal cord by reviewing our institutional experience regarding the incidence of radiation-induced spinal cord toxicity after high-dose pencil beam scanning proton therapy (PBSPT). Seventy-six patients (median age 53years; range, 23-79years) treated for spinal chordoma (n=55) or chondrosarcoma (n=21) met the following criteria and were retrospectively analyzed: PBSPT only, no reirradiation or concomitant chemotherapy, maximum dose (Dmax) to the spinal cord of ≥45Gy(relative biological effectiveness [RBE]), ≥18years of age, and follow-up of ≥12months. The delivered dose was 59.4 to 75.2Gy(RBE) [median 73.9Gy(RBE)] delivered with conventional fractionation between 2000 and 2014. The Dmax, D2%, and V40-V60 of the surface (sSC) and center (cSC) of the spinal cord were recorded. Toxicity was scored according to the Common Terminology Criteria for Adverse Events, version 4.03. Median follow-up was 65.5months (range, 13-173months). Patients received a mean Dmax and D2% to the sSC of 59.0 (median 58.7; range, 48.3-75.9) and 55.3 (median 52.7; range, 43.1-73.8) Gy(RBE), respectively. The corresponding values for the cSC were 52.3 (median 52.7; range, 32.3-73.3) and 51.1 (median 52.0; range, 25.3-73.1) Gy(RBE), respectively. Four patients (5%) developed acute radiation-induced neurotoxicity (grade [G] 1, n=1; G2, n=3). Twelve patients (16%) experienced late neurologic toxicities (G1, n=7; G2, n=4; G4, n=1). One patient with a history of pre-PBSPT symptomatic spinal cord compression redeveloped tetraplegia (G4) after receiving a Dmax of 57.8Gy(RBE) to the sSC and 54.1Gy(RBE) to the cSC. No significant correlation was found between sSC Dmax and D2%, cSC Dmax and D2%, or the length of CTV and toxicity. High-dose conformal PBSPT may be delivered safely in close proximity to the spinal cord with minimal neurotoxicity. Dose constraints of 64Gy(RBE) as D2% for the sSC and 54Gy(RBE) for the cSC seem appropriate for clinical use.

The Neurological Sequelae of Neonatal Hyperbilirubinemia: Definitions, Diagnosis and Treatment of the Kernicterus Spectrum Disorders (KSDs).

Despite its lengthy history, the study of jaundice, hyperbilirubinemia and kernicterus suffers from a lack of clarity and consistency in the key terms used to describe both the clinical and pathophysiological nature of these conditions. For example, the term Bilirubin-induced Neurological Dysfunction (BIND) has been used to refer to all neurological sequelae caused by exposure to high levels of bilirubin, to only mild neurological sequelae, or to scoring systems that quantitate the progressive stages of Acute Bilirubin Encephalopathy (ABE). We seek to clarify and simplify terminology by introducing, defining, and proposing new terms and diagnostic criteria for kernicterus. We propose a systematic nomenclature based on pathophysiological and clinical criteria, presenting a logical argument for each term. Acknowledging observations that kernicterus is symptomatically broad and diverse, we propose the use of the overarching term Kernicterus Spectrum Disorders (KSDs) to encompass all the neurological sequelae of bilirubin neurotoxicity including Acute Bilirubin Neurotoxicity (ABE). We further suggest subclassification of KSDs based on the principal disabling features of kernicterus (motor, auditory). Finally, we suggest the term subtle KSD to designate a child with a history of significant bilirubin neurotoxicity with mild or subtle developmental delays. We conclude with a brief description of the limited treatments currently available for KSD, thereby underscoring the importance of further research. We believe that adopting a systematic nomenclature for the spectrum of clinical consequences of hyperbilirubinemia will help unify the field and promote more effective research in both prevention and treatment of KSDs.

Design, synthesis and evaluation of newer 5,6-dihydropyrimidine-2(1H)-thiones as GABA-AT inhibitors for anticonvulsant potential

Several new 5,6-dihydropyrimidine-2(1H)-thione derivatives have been prepared and investigated for their potencies for anticonvulsant activity against maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) test in mice. The acute neurotoxicity was measured by rotarod test. Compounds 3c and 3l were found active in both of the animal models. Further, in vitro GABA-AT enzyme activity assay was carried out to investigate the possible mechanism of action through GABA-AT inhibition. The most potent compounds 3c and 3l showed inhibitory potency (IC50) of 18.42μM and 19.23μM, respectively. The molecular modeling was performed for all the synthesized compounds. The docking results were found in concordant with the observed animal studies.

Chronic neuropathic pain following oxaliplatin and docetaxel: A 5-year follow-up questionnaire study

Abstract Background Adjuvant chemotherapy with docetaxel and oxaliplatin increases survival in patients with high-risk breast and colorectal cancer, respectively, but may induce acute and chronic neurotoxicity. This study is a 5-year follow-up of chronic chemotherapy-induced peripheral neuropathy (CIPN). Methods In 2011–2012, 74 patients with high-risk colorectal cancer and 100 patients with high-risk breast cancer answered a questionnaire before, during and one year after receiving adjuvant chemotherapy with oxaliplatin and docetaxel, respectively. In 2016, a 5-year follow-up with the same questionnaire was performed in survivors. Results Fifty-two (36.5% women) of 74 patients (91%) treated with oxaliplatin and 80 (100% women) of 100 patients (85%) treated with docetaxel answered the questionnaire. The most common symptoms of CIPN were tingling in the hands (44.2% in the oxaliplatin (CI 95% 30.5; 58.7) and 36.3% in the docetaxel group (CI 95% 25.8; 47.8)) and feet (52.0% in the oxaliplatin (CI 95% 37.6; 66.0) and 37.5% (CI 95% 29.9; 49.0) in the docetaxel group) and numbness in the feet (34.6% in the oxaliplatin (CI 95% 22.0; 49.1) and 17.5% (CI 95% 9.9; 27.6) in the docetaxel group). Pain was present in the hands or feet in 28.9% of patients treated with oxaliplatin (CI 95% 17.12; 43.0) and 31.3% of patients treated with docetaxel (CI 95% 21.3; 42.6). Conclusions The results showed no major change in symptoms of neuropathy or pain from 1 to 5 years after chemotherapy. Symptoms of neuropathy were more common in patients treated with oxaliplatin.

Factors associated with the development and severity of oxaliplatin-induced peripheral neuropathy: a systematic review.

Oxaliplatin is a platinum-derivative chemotherapeutic agent used for colorectal cancer in the adjuvant and metastatic setting in combination with folinic acid and 5-fluorouracil. Oxaliplatin causes an acute cold-induced neurotoxicity and a chronic cumulative neuropathy, which can require dose modification and impact quality of life. To date, no prevention and treatment strategies have proved effective thus reinforcing the importance of identifying at-risk patients in order to maximize therapeutic benefit while minimizing neurotoxicity. Here we reviewed studies on risk and prognostic factors associated with the development and severity of oxaliplatin-induced peripheral neuropathy. A systematic search was conducted in MEDLINE and Embase, and studies investigating clinical and patient-related factors associated with oxaliplatin-induced peripheral neuropathy as their primary focus were identified, and quantitative data were extracted when available. We identified 15 studies, of which only three were prospective. Notable factors were acute neurotoxicity symptoms predicting chronic neuropathy, baseline laboratory findings, patient demographics such as age and gender, comorbidities, and environmental factors. No factor was consistently identified across multiple studies other than the association with oxaliplatin dose. Further investigation into these factors may yield insight into potential neuropathy prevention and treatment strategies.

Occurrence of commonly used pesticides in personal air samples and their associated health risk among paddy farmers

Tanjung Karang, Selangor, is widely known for its paddy cultivation activity and hosts the third largest paddy field in Malaysia. Pesticides contamination in agriculture fields has become an unavoidable problem, as pesticides are used to increase paddy productivity and reduce plant disease. Human exposure to agrichemicals is common and could results in both acute and chronic health effects, such as acute and chronic neurotoxicity. This study aims to determine the concentrations of commonly used pesticides (azoxystrobin, buprofezin, chlorantraniliprole, difenoconazole, fipronil, imidacloprid, isoprothiolane, pretilachlor, propiconazole, pymetrozine, tebuconazole, tricyclazole, and trifloxystrobin) in personal air samples and their associated health risks among paddy farmers. Eighty-three farmers from Tangjung Karang, Selangor were involved in this study. A solid sorbent tube was attached to the farmer's breathing zone with a clip, and an air pump was fastened to the belt to collect personal air samples. Pesticides collected in the XAD-2 resin were extracted with acetone, centrifuged, concentrated via nitrogen blowdown and reconstituted with 1mL of 3:1 ultrapure water/HPLC-grade methanol solution. The extract was analyzed using ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The target compounds were detected with a maximum concentration reaching up to 462.5ngm−3 (fipronil). The hazard quotient (HQ) was less than 1 and the hazard index (HI) value was 3.86×10−3, indicating that the risk of pesticides related diseases was not significant. The lifetime cancer risk (LCR) for pymetrozine was at an acceptable level (LCR<10−6) with 4.10×10−8. The results reported in this study can be beneficial in terms of risk management within the agricultural community.

Impacts of triclosan exposure on zebrafish early-life stage: Toxicity and acclimation mechanisms

Triclosan (TCS) is a broad spectrum antibacterial agent widely used in personal care products and present in most aquatic ecosystems. This study investigated the occurrence of triclosan acclimation and the biological mechanisms underlying the stress response triggered in early-life stage of zebrafish. Zebrafish eggs were first exposed to four different sublethal concentrations of TCS (2, 20, 50 and 100μg/L) for 7days following fertilization and subsequently exposed to a lethal concentration of TCS (1000μg/L). During the time-to-death exposure (TTD), mortality was continuously recorded to evaluate if increased resistance occurred. Overall, larvae exposed to 50μg/L of TCS demonstrated higher sensitivity, with delayed hatching and increased mortality during the sub-lethal exposure and significant lower mean time-to-death (TTD) value compared to the other groups. Interestingly, fish exposed to the highest concentration of TCS (100μg/L) presented a similar mean TTD value as controls and a significantly better survival in comparison with embryos exposed to 50μg/L, suggesting that acclimation process has been triggered at this concentration.Proteomic and enzymatic analyses were conducted on 7days post fertilization (dpf) larvae exposed to 50μg/L and 100μg/L of TCS giving insights into the functional changes triggered at those specific concentrations. TCS seemed to affect proteins involved in cytoskeleton, stress response, eyes and neuronal development. This was endorsed by the enzymatic results, which suggest impairment in glutathione metabolism and acute neurotoxicity. A significant 2.5-fold and 3-fold increase of AChE activity was observed following TCS exposure. Moreover, GPx activity was significantly increased whereas a significant inhibition of GR activity was observed, suggesting that de novo synthesis of reduced GSH might occur in order to maintain the ratio between reduced and oxidized GSH. Proteomic results revealed possible candidate protein involved in the acclimation process of larvae exposed to 100μg/L of TCS. Our integrative analysis revealed complex non-monotonic concentration-related effects on zebrafish early-life stages with increased resistance between 50 and 100μg/L exposures. This research highlighted oxidative stress and neurotoxicity as major toxicity mechanisms of TCS during development.

Severe vincristine-induced polyneuropathy in a teenager with anaplastic medulloblastoma and undiagnosed Charcot-Marie-Tooth disease

Severe neuropathy is a known adverse effect of vincristine in patients with Charcot-Marie-Tooth disease (CMT). We present the case of a 16-year-old girl with anaplastic medulloblastoma treated with gross total...

Bruxism as a consequence of chemotherapy?

IntroductionBruxism is a syndrome with uncertain etiology but with proposed factors: psychosocial, peripheral and central. Treatment is also controversial and one of the options focuses in GABA theory and regularization of ion channels. Xelox (capecitabine + oxaliplatin) and bevacizumad is indicated for metastatic colorectal cancer, being oxaliplatin the most neurotoxic agent (acute syndrome and/or a chronic sensory neuropathy). Acute neurotoxicity is very frequent and it is a sensory and/or a motor toxicity (as tongue tingling or jaw spams). The proposed pathogenesis – neuronal hyperexcitability due to alterations of voltage-gated ion channels – is supported by mechanism of action of some treatments.Objectives and AimsReview different causes of bruxism.MethodsDescription of a clinical case.ResultsThis is a story of 76-years-old man in treatment for metastatic colon cancer that developed toxicity: nauseas (treated with haloperidol), bruxism and gingival atrophy. He was referred to psycho-oncology by involuntary movements of mouth and trunk. The patient complained of sadness, anhedonia and insomnia since recurrence of cancer and related the movements with CT. At observation he was anxious, tearfulness and agitated. He was treated for a depressive episode, but the doubt remained about involuntary movements: haloperidol was a confounding factor for oxaliplatin acute neurotoxicity, also aggravated by psychic and peripheral factors.ConclusionsThe authors believe that bruxism is linked to CT in a very complex relation that includes psychic, peripheral and central factors. Psychiatrists need to keep attention to the patient as a whole, not being seduced by easy answers like psychosocial factors.Disclosure of interestThe authors have not supplied their declaration of competing interest.