Detection of apoptosis by RT-PCR array in mefloquine-induced cochlear damage

Objective To investigate the occurrence and possible mechanisms of apoptosis in cochlear epithelium and spiral ganglion neurons after mefloquine treatment. Methods We used quantitative RT-PCR apoptosis-focused gene arrays （96-well, 84 apoptosis related genes） to assess changes of gene expression in the cochlear basilar membrane （hair cells-supporting cells） and spiral ganglion neurons of rat cochlear organotypic cultures treated with 100 IxM mefloquine for 3 h. Results Significant up-or down-regulation in gene expression was detected in 23 genes in the cochlear basilar membrane, and in 32 genes in the spiral ganglion neurons compared with time-matched controls. The responding genes could be classified as pro-or anti-apoptotic, and were mainly implicated in the Bcl-2, Caspase, Card, IAP, TNF ligand / TNF receptor, Death domain / Death effector domain, DNA damage / p53, and NF-kappa B families. Synthetic analysis suggested that these families could be revised to two major pathways mainly involved in t]he death receptor-mediated signaling pathway and apoptotic mitochondrial pathway. In addition, it was found that numerous anti-apoptotic genes such as Bcl2al, Birclb, Birc3, Birc4, Bnipl, Cflar, II10, Lhx4, Mcll, Nfkbl, Prlr, Prok2, and TNF were greatly up-regulated in the cochlear tissue, which might imply the co-existence of protective response in the ceils at the early stage of mefloquine-induced damage.

Epilepsy triggered by mefloquine in an adult traveler to Uganda

We report a case of a traveler who visited Uganda for 8 d, and took mefloquine one tablet/week for malaria prophylaxis. After the second dose, he suffered from two episodes of loss of consciousness with seizures, therefore mefloquine was discontinued. During the flight back after full recovery, seizures reoccurred while he was on board, he was disembarked in Addis Ababa and then transferred to Nairobi. After repatriation to Italy, he experienced four other similar episodes. The patient was still on full dose anticonvulsant therapy one year and a half after, as any attempt at reduced dose was unsuccessful. Currently, three agents(mefloquine, atovaquone/proguanil, and doxycycline) are recommended for malaria chemoprophylaxis, with similar efficacy but different adverse event profiles, regimens, and prices. Considering that mefloquine is associated with a higher risk of neurologic and psychiatric adverse events than the alternative regimens, we suggest considering mefloquine as a second line choice after atovaquone/progua-nil and doxycycline for short-term travelers.

Ototoxic effects of mefloquine in cochlear organotypic cultures

Mefloquine is a widely used anti-malarial drug. Some clinical reports suggest that mefloquine may be ototoxic and neurotoxic, but there is little scientific evidence from which to draw any firm conclusion. To evaluate the ototoxic and neurotoxic potential of mefloquine, we treated cochlear organotypic cultures and spiral ganglion cultures with various concentrations of mefloquine. Mefloquine caused a dose-dependent loss of cochlear hair cells at doses exceeding 0.01 mM. Hair cell loss progressed from base to apex and from outer to inner hair cells with increasing dose. Spiral ganglion neurons and auditory nerve fibers were also rapidly destroyed by mefloquine in a dose-dependent manner. To investigate the mechanisms underlying mefloquine-induced cell death, cochlear cultures were stained with TO-Pro-3 to identify morphological changes in the nucleus, and with carboxyfluorescein FAM-labeled caspase inhibitor 8, 9 or 3 to determine caspase-mediated cell death. TO-Pro-3-labeled nuclei in hair cells, spiral ganglion neurons and supporting cells were shrunken or fragmented, morphological features characteristic of cells undergoing apoptosis. Both initiator caspase 8 (membrane damage) and caspase 9 (mitochondrial damage), along with executioner caspase 3, were heavily expressed in cochlear hair cells and spiral ganglions after mefloquine treatment. These three caspases were also expressed in support cells, although labeling was less widespread and less intense. These results indicate that mefloquine damages both the sensory and neural elements in the postnatal rat cochlea by initially activating cell death signaling pathways on the cell membrane and in mitochondria.

Evidence for Neurotoxicity from Quinoline Antimalaria Drugs: Four Personal Accounts

Background: The adverse effects of mefloquine and other quinoline antimalaria drugs can be severe and long-lasting. We believe that the trigger for these effects may be drug-induced hepatocellular damage that causes, firstly, a spillage of retinoids into the circulation (and hence a direct toxic effect on the brain and other target organs), and secondly, disruption of the liver-thyroid axis (and hence a pattern of specific bipolar symptoms such as is often seen in thyroid disease). Methods: We sought recently-published lay accounts of adverse effects in users of quinoline antimalaria drugs, to test these lay descriptions against our hypothesis on the likely pathogenesis of these effects. Results: We found six lay accounts that described four different experiences of adverse effects arising from the prophylactic use of quinoline antimalaria drugs. All four travellers were healthy, at the start of travel. Two of the travellers experienced severe psychoses, and one had a mild psychosis. The fourth traveller, a serving US soldier, killed 16 unarmed Afghan civilians. Analysis of these accounts shows that, based on our hypothesis, all four travellers had at least one risk factor (most commonly, concurrent alcohol use), for developing a severe reaction to their quinoline antimalaria drug. Our hypothesis therefore predicted a severe adverse drug reaction in each of these four travellers. We also identified a hitherto unrecognized risk factor for developing a severe reaction to quinoline antimalaria drugs—namely, the concurrent use of anabolic steroids. Conclusions: Lay accounts of drug adverse effects can help initiate or further develop medical hypotheses of their pathogenesis. We advise that the quinoline class of antimalaria drugs should be prescribed cautiously, and that mefloquine should not now be prescribed for malaria prophylaxis, under any circumstances whatsoever. Where persistent adverse effects have resulted from the historical use of quinoline antimalaria drugs, we propose a five-point management strategy that we believe will in most cases cause symptoms to abate rapidly: 1) stop taking the quinoline drug;2) stop alcohol, and stop all other liver-damaging drugs, including anabolic steroids, hormonal contraception, hormone replacement therapy, recreational drugs, antidepressants, anxiolytics and hypnotics;3) maintain good hydration, using non-fluoridated drinking water;4) temporarily eliminate dietary vitamin A;as an additional and optional therapeutic measure, 5) lower the concentration of circulating retinoids through phlebotomy, plasmapheresis or hirudotherapy.

Repurposing of clinically approved drugs for treatment of coronavirus disease 2019 in a 2019-novel coronavirus-related coronavirus model

Background:Medicines for the treatment of 2019-novel coronavirus(2019-nCoV)infections are urgently needed.However,drug screening using live 2019-nCoV requires high-level biosafety facilities,which imposes an obstacle for those institutions without such facilities or 2019-nCoV.This study aims to repurpose the clinically approved drugs for the treatment of coronavirus disease 2019(COVID-19)in a 2019-nCoV-related coronavirus model.Methods:A 2019-nCoV-related pangolin coronavirus GX_P2V/pangolin/2017/Guangxi was described.Whether GX_P2V uses angiotensin-converting enzyme 2(ACE2)as the cell receptor was investigated by using small interfering RNA(siRNA)-mediated silencing of ACE2.The pangolin coronavirus model was used to identify drug candidates for treating 2019-nCoV infection.Two libraries of 2406 clinically approved drugs were screened for their ability to inhibit cytopathic effects on Vero E6 cells by GX_P2V infection.The anti-viral activities and anti-viral mechanisms of potential drugs were further investigated.Viral yields of RNAs and infectious particles were quantified by quantitative real-time polymerase chain reaction(qRT-PCR)and plaque assay,respectively.Results:The spike protein of coronavirus GX_P2V shares 92.2%amino acid identity with that of 2019-nCoV isolate Wuhanhu-1,and uses ACE2 as the receptor for infection just like 2019-nCoV.Three drugs,including cepharanthine(CEP),selamectin,and mefloquine hydrochloride,exhibited complete inhibition of cytopathic effects in cell culture at 10μmol/L.CEP demonstrated the most potent inhibition of GX_P2V infection,with a concentration for 50%of maximal effect[EC50]of 0.98μmol/L.The viral RNA yield in cells treated with 10μmol/L CEP was 15,393-fold lower than in cells without CEP treatment([6.48±0.02]×10-4vs.1.00±0.12,t=150.38,P<0.001)at 72 h post-infection(p.i.).Plaque assays found no production of live viruses in media containing 10μmol/L CEP at 48 h p.i.Furthermore,we found CEP had potent anti-viral activities against both viral entry(0.46±0.12,vs.1.00±0.37,t=2.42,P<0.05)and viral replication([6.18±0.95]×10-4vs.1.00±0.43,t=3.98,P<0.05).Conclusions:Our pangolin coronavirus GX_P2V is a workable model for 2019-nCoV research.CEP,selamectin,and mefloquine hydrochloride are potential drugs for treating 2019-nCoV infection.Our results strongly suggest that CEP is a wide-spectrum inhibitor of pan-betacoronavirus,and further study of CEP for treatment of 2019-nCoV infection is warranted.

Dependence of Generation of Hippocampal CAI Slow Oscillations on Electrical Synapses

Neuronal oscillations in the hippocampus are critical for many brain functions including learning and memory.The underlying mechanism of oscillation generation has been extensively investigated in terms of chemical synapses and ion channels.Recently,electrical synapses have also been indicated to play important roles,as reported in various brain areas in vivo and in brain slices.However,this issue remains to be further clarified,including in hippocampal networks.Here,using the completely isolated hippocampus,we investigated in vitro the effect of electrical synapses on slow CA1 oscillations(0.5 Hz-1.5 Hz)generated intrinsically by the hippocampus.We found that these oscillations were totally abolished by bath application of a general blocker of gap junctions(carbenoxolone)or a specific blocker of electrical synapses(mefloquine),as determined by whole-cell recordings in both CA1 pyramidal cells and fast-spiking cells.Our findings indicate that electrical synapses are required for the hippocampal generation of slow CA1 oscillations.