Infection or drug toxicity? Acute ataxia and encephalopathy after uncomplicated falciparum malaria and efavirenz dose adjustment

Acute ataxia in children is a rare clinical syndrome usually caused by an infectious, post-infectious, or toxin-related aetiology. Although infrequent, acute ataxia can be related to more common diseases and treatments in Southern African countries including side effects of efavirenz-based anti-retroviral therapy (ART) for HIV or the post-malaria neurologic syndrome (PMNS) after infection with falciparum malaria. We describe a case from Lilongwe, Malawi of a 16-year-old HIV-positive patient with viral load suppression who presented with acute ataxia, confusion, and diplopia. Although he was on efavirenz-based ART for many years, his dose was increased 6 weeks prior, and he was treated for uncomplicated falciparum malaria 5 weeks prior with resolution of symptoms. Studies including cerebrospinal fluid analyses were normal, and he had rapid improvement of symptoms following discontinuation of efavirenz-based ART. Several case series have described supratherapeutic levels of efavirenz leading to acute ataxia as well as the self-limiting PMNS after non-complicated falciparum malaria. Though rare, recognition of efavirenz and PMNS as causes of ataxia is important to inform prompt treatment for HIV patients with acute ataxia in Malawi and other similar settings.     

Neuromuscular disorders: a guide for the orthopaedic surgeon

Patients with neuromuscular conditions are frequently seen in final professional clinical examinations as they have good clinical signs, which often point towards the underlying diagnosis. This paper outlines some of the most common neuromuscular disorders that you are likely to come across in orthopaedic practise.     

WWOX,the common fragile site FRA16D gene product,regulates ATM activation and the DNA damage response

Genomic instability is a hallmark of cancer. The WW domain-containing oxidoreductase (WWOX) is a tumor suppressor spanning the common chromosomal fragile site FRA16D. Here, we report a direct role of WWOX in DNA damage response (DDR) and DNA repair. We show that Wwox deficiency results in reduced activation of the ataxia telangiectasia-mutated (ATM) checkpoint kinase, inefficient induction and maintenance of γ-H2AX foci, and impaired DNA repair. Mechanistically, we show that, upon DNA damage, WWOX accumulates in the cell nucleus, where it interacts with ATM and enhances its activation. Nuclear accumulation of WWOX is regulated by its K63-linked ubiquitination at lysine residue 274, which is mediated by the E3 ubiquitin ligase ITCH. These findings identify a novel role for the tumor suppressor WWOX and show that loss of WWOX expression may drive genomic instability and provide an advantage for clonal expansion of neoplastic cells.Genomic instability is a common characteristic of human cancers. The DNA damage response (DDR) maintains the integrity of the genome in response to DNA damage. DDR is a complex signaling process that results in cell cycle arrest followed by either DNA repair or apoptosis if the DNA damage is too extensive to be repaired (1–3). Key mammalian damage response sensors are ataxia telangiectasia-mutated (ATM), ATM and Rad3-related, and DNA-dependent PKs (4, 5). Disruption of the DDR machinery in human cells leads to genomic instability and an increased risk of cancer progression (6, 7).The WW domain-containing oxidoreductase (WWOX) gene spans the common fragile site (CFS) FRA16D (8, 9). Genomic alterations affecting the WWOX locus have been reported in several types of cancer and include homozygous and hemizygous deletions (10–13). Ectopic expression of WWOX in WWOX-negative cancer cells attenuates cell growth and suppresses tumor growth in immunocompromised mice (10, 11, 14). Importantly, targeted ablation of Wwox in mice results in higher incidence of spontaneous lesions resembling osteosarcomas and lung and mammary tumors (14–16). These findings suggest WWOX as a tumor suppressor. The WWOX protein contains two N-terminal WW domains mediating WWOX interaction with PP(proline)x(amino acid)Y(tyrosine)-containing proteins (11, 17) and a central short-chain deyhdrogenase/reductase domain that has been proposed to function in steroidogenesis (18). Recent characterization of WWOX domains revealed that they interact, mainly through the WW1 domain, with multiprotein networks (3). The mechanism by which WWOX suppresses tumorigenicity is, however, not well-known.In vitro, CFSs are defined as gaps or breaks on metaphase chromosomes that occur in cells treated with inhibitors of DNA replication (19, 20). In vivo, CFSs are preferential targets of replication stress in preneoplastic lesions (21), and emerging evidence suggests that they represent early warning sensors for DNA damage (22–24). Both genetic and epigenetic factors are thought to regulate the fragility of CFS (25, 26). Recent profiling studies of CFS provide evidence that the functional fragility of CFS is tissue-specific (27–29). High-throughput genomic analyses of 3,131 cancer specimens (12) and 746 cancer cell lines (13) have recently identified large deletions in CFSs, including the FRA16D/WWOX locus. Although these deletions have been linked to the presence of DNA replication stress (30), the molecular function of gene products of CFSs, including the WWOX protein, is poorly understood. Here, we identify a direct role of WWOX in the DDR and show that the WWOX gene product functions as a modulator of the DNA damage checkpoint kinase ATM.     

多系统萎缩老年患者早期临床特点分析

目的 探讨多系统萎缩(MSA)的早期的临床表现及发病特点,为早期诊断提供依据.方法 回顾性分析我院102例诊断“很可能”的MSA老年患者首发症状、临床特点及辅助检查等,结合文献进行复习. 结果 102例诊断为“很可能”的MSA老年患者,其中诊断为MSA-P亚型57例(55.9％),MSA-C亚型45例(44.1％).首发症状以自主神经功能障碍27例,在MSA-P亚型与MSA-C亚型中分别为15例(26.3％)和12例(26.6％),主要表现为排尿、排便障碍14例,直立性低血压11例,性功能障碍8例.首发症状以帕金森样症状49例,主要表现为步态异常24例,静止性震颤3例,肌强直16例,动作迟缓15例.首发症状以小脑症状33例,主要表现为步态、肢体共济失调27例,构音障碍6例,眼球震颤2例.首发锥体束征2例.早期发生误诊36例(35.3％). 结论 MSA早期表现多样,容易被误诊.注意临床表现和辅助检查,提高临床早期诊断的准确性.     

Cognitive characterization of SCAR10 caused by a homozygous c.132dupA mutation in the ANO10 gene

ABSTRACT

Autosomal recessive spinocerebellar ataxia type 10 (SCAR10) caused by a homozygous c.132dupA mutation in the anoctamin 10 gene is infrequent and little is known about its cognitive profile. Three siblings (1 male) with this mutation were assessed with a neuropsychological battery measuring multiple cognitive domains. The deficits observed in one patient were in executive functions whereas the other two patients showed deficits in practically all the functions. Cognitive impairment seems to be a characteristic of the SCAR10 produced by this mutation, with a range from mild impairment, especially involving prefrontal systems, to a severe cognitive impairment suggesting widespread cerebral involvement.     

脊髓小脑共济失调2型临床和神经影像学特征分析

研究背景脊髓小脑共济失调2型(SCA2)为常染色体显性遗传性疾病,是由致病基因ATXN2编码区胞嘧啶-腺嘌呤-鸟嘌呤(CAG)三核苷酸重复序列扩展突变引起,目前较公认的正常重复范围为13~31次,异常重复范围>34次。主要表现包括小脑共济失调、眼肌麻痹、慢眼动、腱反射减弱,可伴有动作性震颤、智力减退和周围性感觉神经病等;头部MRI显示脑干、小脑明显萎缩(典型的橄榄脑桥小脑萎缩改变)。本研究针对5例经基因检测明确诊断的SCA2家系先证者进行临床和影像学特点,以及表型与基因型相关性分析。方法对708例常染色体显性遗传性SCA家系的先证者和119例临床拟诊SCA的散发患者进行常规基因学检测,分析SCA1~3、6、7、17型和齿状核红核苍白球路易体萎缩致病基因CAG序列重复动态突变。采用聚合酶链反应扩增重复序列、琼脂糖凝胶电泳检测扩增产物,对于出现2个电泳条带的样品通过荧光标记毛细管电泳片段分析方法进行重复序列计数。结合基因学检测结果,对患者临床表型和神经影像学特征进行分析。结果其中45例患者携带SCA2基因CAG重复扩展突变,临床表现为小脑共济失调、眼肌麻痹、慢眼动、腱反射减弱或消失,部分患者可伴有动作性震颤,MRI均显示脑干、小脑明显萎缩。其中5例典型病例的临床表型均与其基因型相符。结论基因学检测可为SCA2的明确诊断提供依据,临床和神经影像学特征有助于诊断与鉴别诊断。对于携带中间重复等位基因个体的诊断,需结合临床和影像学特点以及家系上下代动态突变进行分析。     

Grasping without vision: Time normalizing grip aperture profiles yields spurious grip scaling to target size

The analysis of normalized movement trajectories is a popular and informative technique used in investigations of visuomotor control during goal-directed acts like reaching and grasping. This technique typically involves standardizing measures against the amplitude of some other variable – most typically time. Here, we show that this normalizing technique can lead to some surprising results. In the first of two experiments, we asked participants to grasp target objects without ever seeing them from trial to trial. In the second experiment, participants were given a brief preview of the target and were then cued 3 s later to pick it up while vision was prevented. Critically, on some trials during the delay period and unbeknownst to the participants, the previewed target was swapped for a new unseen one. The results of both experiments show that time-normalized measures of grip aperture during the closing phase of the movement appear to be scaled to target size well before the fingers make contact with the target – even though participants had no idea what the size of the target was that they were grasping. In contrast, a classical measure of anticipatory grip scaling, maximum grip aperture, did not show scaling to target size. As we demonstrate, however, in both experiments, movement time was longer for the larger target than the smaller ones. Thus, the comparisons of time-normalized grip aperture, particularly during the closing phase of the movements, were made across different points in real time. Taken together, the results of these experiments highlight a need for caution when investigators interpret differences in time-normalized dependent measures – particularly when the effect of interest is correlated with the dependent measure and a third variable (e.g., movement time) that is used to standardize the dependent measure.