Intensity‐based masking: A tool to improve functional connectivity results of resting‐state fMRI

Seed‐based functional connectivity (FC) of resting‐state functional MRI data is a widely used methodology, enabling the identification of functional brain networks in health and disease. Based on signal correlations across the brain, FC measures are highly sensitive to noise. A somewhat neglected source of noise is the fMRI signal attenuation found in cortical regions in close vicinity to sinuses and air cavities, mainly in the orbitofrontal, anterior frontal and inferior temporal cortices. BOLD signal recorded at these regions suffers from dropout due to susceptibility artifacts, resulting in an attenuated signal with reduced signal‐to‐noise ratio in as many as 10% of cortical voxels. Nevertheless, signal attenuation is largely overlooked during FC analysis. Here we first demonstrate that signal attenuation can significantly influence FC measures by introducing false functional correlations and diminishing existing correlations between brain regions. We then propose a method for the detection and removal of the attenuated signal (“intensity‐based masking”) by fitting a Gaussian‐based model to the signal intensity distribution and calculating an intensity threshold tailored per subject. Finally, we apply our method on real‐world data, showing that it diminishes false correlations caused by signal dropout, and significantly improves the ability to detect functional networks in single subjects. Furthermore, we show that our method increases inter‐subject similarity in FC, enabling reliable distinction of different functional networks. We propose to include the intensity‐based masking method as a common practice in the pre‐processing of seed‐based functional connectivity analysis, and provide software tools for the computation of intensity‐based masks on fMRI data. Hum Brain Mapp 37:2407–2418, 2016. © 2016 Wiley Periodicals, Inc .     

Serum folate concentration,cognitive impairment,and DNA damage among elderly individuals in Malaysia

The notion that dietary factors affect cognitive function and subsequently the risk of dementia has increased over the years from a global viewpoint. Because low folate intake has been described to impair cognitive function, we tested the hypothesis that low serum folate concentration is associated with cognitive impairment and an attenuated increase in DNA damage. We investigated the relationship between serum folate concentration, cognitive impairment, and DNA damage among elderly people attending health clinics in Klang Valley, an urban area in Malaysia. Two hundred thirty-two participants, composed of 115 men (49.6%) and 117 women (50.4%), were involved; none of the patients were diagnosed with neuropsychiatric problems, nor where they terminally ill. Sociodemography and health variables were assessed through face-to-face interview. Cognitive impairment review was conducted through an Elderly Cognitive Assessment Questionnaire. The estimation of dietary intake, serum folate concentration, and DNA damage was individually analyzed using validated Dietary History Questionnaires, immunoassay methods, and an Alkaline Comet Assay study (10 mL of peripheral venous blood), respectively. Results indicated that more men had cognitive impairment (33.0%) and DNA damage (27.0% for percentage DNA in tail, 22.6% tail moment) compared with women (25.6%, 15.4%, and 15.4%, respectively) (P < .05 for all parameters), recording an average folate deficiency value of 13.9% (0.2% higher than women). Multivariate binary logistic regression analysis outlined the association of cognitive impairment with older age (odds ratio [OR], 2.74; 95% confidence interval [CI], 1.35-5.57), smoking habits (OR, 5.12; 95% CI, 2.48-10.57), poor serum folate concentration (OR, 3.46; 95% CI, 1.26-9.52), and DNA damage (percentage DNA in tail) (OR, 13.70; 95% CI, 1.36-138.29). In conclusion, this study highlighted the important role of serum folate concentration for cognitive function and provided a concise picture regarding the elevated levels of oxidative DNA damage in peripheral lymphocytes.     

肝细胞生长因子诱导实验性视网膜脱离的病理机制研究

目的 观察肝细胞生长因子（HGF）对视网膜色素上皮（RPE）细胞屏障功能的影响以及RPE内过度表达HGF导致视网膜脱离（RD）的病理机制。 方法 编码HGF（AdCMV.HGF）、绿色荧光蛋白（Ad CMV.GFP）的E1/E3缺失的腺病毒载体，以5×10⁴ 噬斑形成单位（pfu）/眼注射到成年有色兔的视网膜下。检查注射后3、7、14、28 d时的眼底及组织病理变化,利用免疫组织化学和酶联免疫吸附试验（ELISA）方法检测HGF在视网膜和玻璃体的表达水平。 结果 对照组注射Ad CMV.GFP眼显示GFP几乎仅表达于PRE单核细胞层，AdCMV.HGF注射眼在注射点处的PRE细胞出现强的HGF免疫阳性反应。玻璃体内HGF的表达水平在注射7 d后达到最高峰、28 d后降低到基础水平。在HGF的表达期内AdCMV.HGF注射眼出现慢性RD和脉络膜慢性炎症。在RD区域，视网膜下的空间内可见增生性的RPE细胞，部分实验兔眼还产生多层的细胞膜结构。 结论 RPE内过度表达的HGF能引发慢性浆液性RD，同时伴有视网膜下RPE增生。提示HGF可能作为治疗RD的作用靶点。(中华眼底病杂志，2007，23：193-197)     

视觉空间搜索任务:计算机评估和训练程序

本文的双重研究目的:第一,介绍一个关于视觉搜索任务(VISSTA)的计算机平台的现有软件包和它在很多传统项目中的应用潜能。第二,展示该基本软件包在脑卒中患者和对照健康人群中的应用结果。研究方法:测试者包括39名健康个体;25名患有单侧空间忽略症(USN)的后右半脑损伤者(RHD);27名无单侧空间忽略症的后右半脑损伤者和20名后左半脑损伤者。所有参与者进行了无纸笔的计算机化VISSTA测试。脑卒中病人也进行了ADL查检表测试和FIM测试。研究结果:结果表明VISSTA是一款有效的视觉搜索能力评估软件,它可以显著地区分脑卒中患者和健康人以及脑卒中病人中的不同亚群。USN病人表现出视觉搜索条件障碍和明显的大脑单侧偏爱(当目标物体呈现在电脑屏幕的左边时),这点从成功率与反应时间方面可得到证实,但无USN的RHD病人比有USN的RHD病人做的稍好。然而,和健康人相比,他们的视觉搜索注意能力和目标探测(包括左右两边)注意能力方面仍然有损伤。结论:就精确度和反应时间而言,VISSTA工具对视觉空间注意水平是敏感的。结果表明,替代传统的纸笔测试和以随机的、复杂的方式提供精确度和RT参数的工具进行的行为测试是非常重要的。因其平台的灵活性,VISSTA同样也适合于脑卒中病人的治疗。     

Stimulatory effect of prolactin on human placental progesterone secretion at term in vitro: possible inhibitory effect on oestradiol secretion

Maternal and fetal circulating prolactin (PRL) increases 10-fold compared with the non-pregnant state. We examined the effect of PRL upon placental steroidogenesis. It had a significant (P less than 0.05) time-dependent stimulatory effect upon placental explants/P4 accumulation and secretion into the medium. The maximal stimulatory effect (two-fold) in dose-dependent experiments was found to be 200 ng/ml. The effect of PRL upon oestradiol secretion was mainly inhibitory. This inhibition was most pronounced at 200 ng/ml. In conclusion, placental steroid secretion is modulated by PRL. This effect occurs mainly at concentrations seen in the placenta at term, suggestive of its physiologic role.     

Breast feeding as prophylaxis for atopic eczema: a controlled study of 368 cases

The present study was undertaken in an attempt to draw data whether breast-feeding is beneficial in prevention of atopic eczema. Three-hundred and sixty-eight babies given different feeding modalities were examined for the presence of atopic eczema at the age of three and six months. Seven percent of breast-fed infants developed eczema compared to 10% of formulae-fed and 6% of mixed breast and formulae-fed infants. No difference in the severity of atopic eczema was recorded in the three study groups. Our experience demonstrates the absence of a protective effect of breast-feeding against the development and severity of atopic eczema.     

Pre-excitation syndrome in infants and children. Effect of digoxin,verapamil, and amiodarone.

Clinical and electrocardiographic findings for 30 patients with the pre-excitation syndrome are described together with details of treatment. Nineteen (63%) were younger than 2 years, 14 of whom were under 2 months. Sixteen infants and 7 children (77%) presented with paroxysmal supraventricular tachycardia, 14 (61%) of whom had the electrocardiographic pattern of type A Wolff-Parkinson-White (WPW) syndrome. During paroxysmal bouts the QRS complex was normal in 21 patients and wide in two. Six (20%) patients had congenital heart disease often associated with WPW syndrome type B. Seventeen patients were treated with either digoxin or verapamil intravenously to stop tachyarrhythmias. Verapamil was more effective due to the immediate response and lack of adverse effects. The tachyarrhythmias resolved in all the patients and in some of them the WPW pattern resolved later indicating maturation of the conduction tissue with loss of the accessory pathways. Verapamil provides a rapid and safe form of treatment for conversion of tachyarrhythmias since it has no effect on the accessory pathways. Oral amiodarone prevents recurrent tachyarrhythmias resistant to other treatment.     

The learning effect in visual field testing of healthy subjects using frequency doubling technology

PURPOSE: To evaluate the presence, duration and magnitude of a learning effect in serial visual field (VF) testing, using the commercially available frequency doubling technology (FDT) instrument. PATIENTS AND METHODS: 21 healthy adults with no prior VF experience underwent 6 serial VF tests, using the full-threshold C-20 program of the Zeiss-Humphrey FDT analyzer, on one randomly chosen eye. Tests were spaced at least two days apart. RESULTS: The average mean sensitivity was 32.37 +/- 2.6 dB; the average mean deviation (MD) was 1.22 +/- 1.8 dB. The MD at the first examination (0.28 +/- 2.1 dB) was significantly poorer than at any of the other testing sessions (p<0.003). Similarly, the mean sensitivity at the first examination (31.16 +/- 3.0 dB) was significantly lower than any other testing session (p<0.004). The proportion of improvement from the first to the second session was 63% and 65% of the total improvement, for mean sensitivity and MD, respectively. Mean test duration showed a modest reduction, from 4.40 +/- 0.3 minutes in the first session to 4.17 +/- 0.4 minutes in the last session (p = 0.023). A sub-analysis comparison of the different VF segments showed a more prominent learning effect in the peripheral and nasal visual segments (p<0.0001). CONCLUSION: Baseline measurements should best rely on the second testing session, since MD and mean sensitivity are somewhat poorer when subjects with no prior VF experience are first tested on the FDT instrument. This may be especially true for the purpose of following patients over time.