Toxic and Drug-Induced Neuropathies

The Interplay Between Neuroinfections, the Immune System and Neurological Disorders: A Focus on Africa

Neurological disorders related to neuroinfections are highly prevalent in Sub-Saharan Africa (SSA), constituting a major cause of disability and economic burden for patients and society. These include epilepsy, dementia, motor neuron diseases, headache disorders, sleep disorders, and peripheral neuropathy. The highest prevalence of human immunodeficiency virus (HIV) is in SSA. Consequently, there is a high prevalence of neurological disorders associated with HIV infection such as HIV-associated neurocognitive disorders, motor disorders, chronic headaches, and peripheral neuropathy in the region. The pathogenesis of these neurological disorders involves the direct role of the virus, some antiretroviral treatments, and the dysregulated immune system. Furthermore, the high prevalence of epilepsy in SSA (mainly due to perinatal causes) is exacerbated by infections such as toxoplasmosis, neurocysticercosis, onchocerciasis, malaria, bacterial meningitis, tuberculosis, and the immune reactions they elicit. Sleep disorders are another common problem in the region and have been associated with infectious diseases such as human African trypanosomiasis and HIV and involve the activation of the immune system. While most headache disorders are due to benign primary headaches, some secondary headaches are caused by infections (meningitis, encephalitis, brain abscess). HIV and neurosyphilis, both common in SSA, can trigger long-standing immune activation in the central nervous system (CNS) potentially resulting in dementia. Despite the progress achieved in preventing diseases from the poliovirus and retroviruses, these microbes may cause motor neuron diseases in SSA. The immune mechanisms involved in these neurological disorders include increased cytokine levels, immune cells infiltration into the CNS, and autoantibodies. This review focuses on the major neurological disorders relevant to Africa and neuroinfections highly prevalent in SSA, describes the interplay between neuroinfections, immune system, neuroinflammation, and neurological disorders, and how understanding this can be exploited for the development of novel diagnostics and therapeutics for improved patient care.

Biochemical and histological alterations of doxorubicin-induced neurotoxicity in rats: Protective role of luteolin

Doxorubicin (DOX) is a chemotherapeutic drug used in the treatment of various cancer types. DOX toxic side effects include neuronopathy and memory deficits. We investigated the effect of the antioxidant luteolin (LUT: 50 or 100 mg/kg; per os) on DOX (2 mg/kg; intraperitoneal)-induced oxidative stress (OS), inflammation, and apoptosis in the brain of Wistar rats for 14 days. We observed that LUT reduced DOX-mediated increase in OS biomarkers-catalase, superoxide dismutase, glutathione-S-transferase, and glutathione peroxidase. LUT increased glutathione and total sulphydryl levels and alleviated DOX-induced increases in the levels of reactive oxygen and nitrogen species, lipid peroxidation, myeloperoxidase, nitric oxide, tumor necrosis factor-α, and interleukin-1β (IL-1β). Additionally, LUT suppressed caspase-3 activity, increased anti-inflammatory cytokine-IL-10 level, and reduced pathological lesions in the examined organs of rats cotreated with LUT and DOX. Collectively, cotreatment with LUT lessened DOX-induced neurotoxicity. Supplementation of LUT as a chemopreventive agent might be useful in patients undergoing DOX chemotherapy.

Voltammetric Methods Used in the Determination of Nucleoside Reverse Transcriptase Inhibitors

Background:

The Human Immunodeficiency Virus (HIV) has now been established as the causative agent of the Acquired Immunodeficiency Syndrome (AIDS) and exactly 25 antiretroviral drugs have been formally approved for clinical use in the treatment of AIDS. The life quality and duration of HIV-positive patients have increased with the usage of antiretroviral drugs in the treatment of AIDS. Nucleoside Reverse Transcriptase Inhibitors (NRTIs) are one of the subgroups of antiretroviral.

Objective:

The quantification of drugs is important, as they make positive contributions to dose adjustments in practice. Voltammetric methods are very powerful analytical methods used in the pharmaceutical industry because of the determination of therapeutic agents and/or their metabolites in clinical samples at extremely low concentrations (10-50 ng/ml).

Methods:

This review mainly includes the pharmacological properties and recent determination studies by voltammetric methods from pharmaceutical dosage forms and biological samples of eight NRTIs group antiretroviral drugs (zidovudine, abacavir, adefovir, entecavir, zalcitabine, didanosine, emtricitabine, lamivudine) that are used in the clinic and show electroactive properties, were performed.

Conclusion:

Due to the variety of working electrodes in voltammetric methods, it is possible to choose the electrode that best responds. In this way, the analysis of NRTIs was possible at lower concentrations in pharmaceuticals and biological samples with voltammetric methods in these studies without the necessity for the sample pre-treatment or time-consuming extraction steps. The voltammetric methods provide good stability, repeatability, reproducibility and high recovery for the analysis of the analyte. They could be used for the pharmacokinetic studies as well as for quality control laboratory studies.

4-Hydroxychalcone Induces Cell Death via Oxidative Stress in MYCN-Amplified Human Neuroblastoma Cells

Neuroblastoma is an embryonal malignancy that arises from cells of sympathoadrenal lineage during the development of the nervous system. It is the most common pediatric extracranial solid tumor and is responsible for 15% of childhood deaths from cancer. Fifty percent of cases are diagnosed as high-risk metastatic disease with a low overall 5-year survival rate. More than half of patients experience disease recurrence that can be refractory to treatment. Amplification of the MYCN gene is an important prognostic indicator that is associated with rapid disease progression and a poor prognosis, highlighting the need for new therapeutic approaches. In recent years, there has been an increasing focus on identifying anticancer properties of naturally occurring chalcones, which are secondary metabolites with variable phenolic structures. Here, we report that 4-hydroxychalcone is a potent cytotoxin for MYCN-amplified IMR-32 and SK-N-BE (2) neuroblastoma cells, when compared to non-MYCN-amplified SH-SY5Y neuroblastoma cells and to the non-neuroblastoma human embryonic kidney cell line, HEK293t. Moreover, 4-hydroxychalcone treatment significantly decreased cellular levels of the antioxidant glutathione and increased cellular reactive oxygen species. In addition, 4-hydroxychalcone treatment led to impairments in mitochondrial respiratory function, compared to controls. In support of this, the cytotoxic effect of 4-hydroxychalcone was prevented by co-treatment with either the antioxidant N-acetyl-L-cysteine, a pharmacological inhibitor of oxidative stress-induced cell death (IM-54) or the mitochondrial reactive oxygen species scavenger, Mito-TEMPO. When combined with the anticancer drugs cisplatin or doxorubicin, 4-hydroxychalcone led to greater reductions in cell viability than was induced by either anti-cancer agent alone. In summary, this study identifies a cytotoxic effect of 4-hydroxychalcone in MYCN-amplified human neuroblastoma cells, which rationalizes its further study in the development of new therapies for pediatric neuroblastoma.