Establishment and evaluation of a monkey acute cerebral ischemia model

OBJECTIVES: Cerebral ischemia seriously threatens human health and is characterized by high rates of incidence, disability and death. Developing an ideal animal model of cerebral ischemia that reflects the human clinical features is critical for pathological studies and clinical research. The goal of this study is to establish a local cerebral ischemia model in rhesus macaque, thereby providing an optimal animal model to study cerebral ischemia. METHODS: Eight healthy rhesus monkeys were selected for this study. CT scans were performed before the operation to exclude cerebral vascular and intracranial lesions. Under guidance and monitoring with digital subtraction angiography (DSA), a microcatheter was inserted into the M1 segment of the middle cerebral artery (MCA) via the femoral artery. Then, autologous white thrombi were introduced to block blood flow. Immediately following embolization, multisequence MRI was used to monitor cerebrovascular and brain parenchymal conditions. Twenty-four hours after embolization, 2 monkeys were sacrificed and subjected to perfusion, fixation and pathological examination. RESULTS: The cerebral ischemia model was established in 7 rhesus monkeys; one animal died during intubation. DSA and magnetic resonance angiography (MRA) indicated the presence of an arterial occlusion. MRI showed acute local cerebral ischemia. HE staining revealed infarct lesions formed in the brain tissues, and thrombi were present in the cerebral artery. CONCLUSION: We established a rhesus macaque model of local cerebral ischemia by autologous thrombus placement. This model has important implications for basic and clinical research on cerebral ischemia. MRI and DSA can evaluate the models to ensure accuracy and effectiveness.

Prevalence of mitochondrial DNA mutations in sporadic patients with nonsyndromic sensorineural hearing loss / Prevalência de mutações no DNA mitocondrial em pacientes esporádicos com deficiência auditiva sensorioneural não sindrômica

ABSTRACT INTRODUCTION: Several mitochondrial DNA mutations have been reported to be associated with nonsyndromic hearing loss in several families. However, little is known about the prevalence of these mutations in sporadic patients with nonsyndromic sensorineural hearing loss. OBJECTIVE: The purpose of our study was to investigate the incidence of these mitochondrial DNA mutations in such population. METHODS: A total of 178 sporadic patients with nonsyndromic sensorineural hearing loss were enrolled in this study. Genomic DNA was extracted from the peripheral blood sample. We employed the SNaPshot(r) sequencing method to detect five mitochondrial DNA mutations, including A1555G and A827G in 12S rRNA gene and A7445G, 7472insC, and T7511C in tRNASerUCN gene. Meanwhile, we used polymerase chain reaction and sequenced the products to screen GJB2 gene mutations in patients carrying mitochondrial DNA mutations. RESULTS: We failed to detect the presence of A1555G mutation in 12S rRNA gene, and of A7445G, 7472insC, T7511C mutations in tRNASerUCN gene in our population. However, we found that 6 patients (3.37%) were carriers of a homozygous A827G mutation and one of them also carried homozygous GJB2 235delC mutation. CONCLUSION: Our findings in the present study indicate that even in sporadic patients with nonsyndromic sensorineural hearing loss, mitochondrial DNA mutations might also contribute to the clinical phenotype.

Resumo Introdução: Diversas mutações do DNA mitocondrial tem sido descritas, em diferentes famílias, associadas à deficiência auditiva não sindrômica. No entanto, pouco se sabe sobrea prevalência dessas mutações em pacientes esporádicos com deficiência auditiva sensorioneural não sindrômica. Objetivo: A finalidade do nosso estudo foi investigar a incidência dessas mutações no DNA mitocondrial nessa população. Método: No total, 178 pacientes esporádicos com deficiência auditiva sensorioneural não sindrômica foram recrutados para participação no estudo. O DNA genômico foi extraído de amostra, de sangue periférico. Utilizamos o método de sequenciamento SNaPshot(r) para detecção de cinco mutações do DNA mitocondrial: A1555G e A827G no gene 12S rRNA e A7445G, 7472insCe T7511C no gene tRNASerUCN. Paralelamente, utilizamos a reação de polimerase em cadeia e sequenciamos os produtos para triagem das mutações no gene GJB2 nos pacientes portadores de mutações no DNA mitocondrial. Resultados: Em nossa população, não conseguimos detectar a presença da mutação A1555G no gene 12S rRNA e nem as mutações A7445G, 7472insC e T7511C no gene tRNASerUCN. Entretanto, constatamos que seis pacientes (3,37%) eram portadores da mutação homozigota A827G; e um deles também portava a mutação homozigota GJB2 235delC. Conclusão: Nossos achados no presente estudo indicam que, mesmo em pacientes esporádicos com deficiência auditiva sensorioneural não sindrômica, as mutações do DNA mitocondrial também podem contribuir para o fenótipo clínico.