Use of perfusion- and diffusion-weighted imaging in differential diagnosis of acute and chronic ischemic stroke and multiple sclerosis

OBJECTIVE: To investigate differences in lesions and surrounding normal appearing white matter (NAWM) by perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) in patients with acute and chronic ischemic stroke and multiple sclerosis (MS). METHODS: Study subjects included 45 MS patients, 22 patients with acute ischemic stroke and 20 patients with chronic ischemic stroke. All subjects underwent T2-weighted imaging (WI), flair attenuated inversion recovery (FLAIR), DWI and dynamic contrast enhanced PWI. Apparent diffusion coefficient (ADC) and mean transit time (MTT) maps were generated and values were calculated in the acute and chronic ischemic and demyelinating lesions, and in NAWM for distances of 5, 10 and 15 mm. Fifty-three acute ischemic and 33 acute demyelinating lesions, and 775 chronic ischemic and 998 chronic demyelinating lesions, were examined. Univariate, multivariate and data mining analyses were used to examine the feasibility of a prediction model between different lesion types. Correctly and incorrectly classified lesions, true positive (TP), false positive (FP) and precision rates were calculated. RESULTS: Patients with acute ischemic lesions presented more prolonged mean MTT values in lesions (p=0.002) and surrounding NAWM for distances of 5, 10 and 15 mm (all p<0.0001) than those with acute demyelinating lesions. In multinomial logistic regression analysis, 65 of 86 acute lesions were correctly classified (75.6%). The TP rates were 81.1% for acute ischemic lesions and 66.7% for acute demyelinating lesions. The FP rates were 33.3% for acute ischemic and 18.9% for acute demyelinating lesions. The precision was 79.6% for classification of acute ischemic lesions and 68.8% for prediction of acute demyelinating lesions. The logistic model tree decision algorithm revealed that prolonged MTT of surrounding NAWM for a distance of 15 mm (> or =7459.2 ms) was the best classifier of acute ischemic versus acute demyelinating lesions. Patients with chronic ischemic lesions presented higher mean ADC (p<0.0001) and prolonged MTT (p=0.013) in lesions, and in surrounding NAWM for distances of 5, 10 and 15 mm (all p<0.0001), compared to the patients with chronic demyelinating lesions. Data mining analyses did not show reliable predictability for correctly discerning between chronic ischemic and chronic demyelinating lesions. The precision was 56.7% for classification of chronic ischemic and 58.9% for prediction of chronic demyelinating lesions. DISCUSSION: We found prolonged MTT values in lesions and surrounding NAWM of patients with acute and chronic ischemic stroke when compared to MS patients. The use of PWI is a promising tool for differential diagnosis between acute ischemic and acute demyelinating lesions. The results of this study contribute to a better understanding of the extent of hemodynamic abnormalities in lesions and surrounding NAWM in patients with MS.     

Anovestibular fistula with normal anus

Purpose

The purpose of the study was to review a rare anomaly of anorectal malformations in girls, congenital anovestibular fistula (AVF) with normal anus, over a 12-year period.

Materials and Methods

A total of 24 female patients of AVF with normal anus were treated in the Department of Pediatric Surgery, Chittagong Medical College and Hospital, Chittagong, Bangladesh, from January 1994 to June 2006. Clinical features, operative findings, operative procedures, postoperative complications, and outcomes were analyzed.

Results

Age ranged from 1 day to 7 years (mean, 10.5 months). All 24 female patients presented with passage of stools through 2 perineal openings. In addition, vulvar abscesses were noted in 5 cases. Vestibular opening of the fistula was found behind the vagina in 18 patients, and the anal opening of the fistula was on the anterior anal wall above the dentate line in 20 cases. There were no associated abnormalities. After adequate bowel preparation, 22 patients underwent excision of the fistulous tract with reconstruction of anal wall without a diverting colostomy. All 5 patients with vulvar abscess experienced wound disruption and required reoperation. All 24 girls have normal bowel motions at follow-up.

Conclusions

In the management of AVF with normal anus, primary repair without colostomy is a safe option. In cases of abscess or infection, definitive operation should be deferred until adequate healing is achieved.     

Clinicopathologic Features and Long-Term Outcomes of 293 Phyllodes Tumors of the Breast

BACKGROUND: Phyllodes tumors (PT) are rare fibroepithelial neoplasms of the breast with unpredictable behavior. We reviewed our single institution experience with PT over 51 years to identify factors predictive of local recurrence (LR) and metastasis. METHODS: From 1954 to 2005, a total of 352 cases of PT were identified; 293 had follow-up. All available pathology slides (90%) were rereviewed for margins, borders, fibroproliferation in the surrounding breast tissue, stromal pattern, stromal cellularity, frequency of mitoses, and necrosis. RESULTS: All cases occurred in women, with a median age of 42, with 203 originally categorized as benign and 90 as malignant. Median follow-up was 7.9 years. A total of 35 patients developed LR at a median of 2 years. In univariate analyses, a higher actuarial LR rate was associated with positive margins (P = .04), fibroproliferation (P = .001), and necrosis (P = .006). PT classified as malignant did not have a higher risk of LR (P = .79). Five patients developed distant disease at a median of 1.2 years. These patients constituted 71% of the seven patients who had uniformly aggressive pathologic features, including large tumor size (>or=7.0 cm), infiltrative borders, marked stromal overgrowth, marked stromal cellularity, high mitotic count, and necrosis. CONCLUSIONS: Positive margins, fibroproliferation in the surrounding breast tissue, and necrosis are associated with a marked increase in LR rates. Efforts should be made to achieve negative surgical margins to reduce risk of LR. Death from PT is rare (2%), and only PT that demonstrate uniformly aggressive pathologic features seem to be associated with mortality.     

急性淋巴细胞白血病(上)

急性淋巴细胞白血病是淋巴前体细胞异常引起的恶性疾病,儿童与成人均可能发生。儿童发病高峰2～5岁。有效治疗的稳步进展使本病在儿童中的治愈率80％以上,同时为新的治疗方案提供了良机,新方案将保留我们在白血病无病生存病例中获得的治疗经验,同时减轻当前强化治疗方案中的毒副作用。     

神经外科中高渗盐注射液应用研究进展

控制脑水肿和颅内压(ICP)升高是神经外科围手术期治疗的重要组成部分.颅脑创伤、动脉梗塞、静脉高压/梗塞、大脑内出血、蛛网膜下腔出血、肿瘤和术后脑组织水肿的治疗过程中ICP的控制都是决定患者预后的关键因素.虽然利用渗透压脱水药物是控制ICP的最基础的工具,但却缺乏前瞻性研究以指导其运用,高渗盐被认为是甘露醇的替代物,早期的数据表明每种药的用药指征最终取决于ICP的病因.在这篇综述中,我们总结了有关高渗盐(HS)治疗颅内高压的相关数据,以及这些数据和我们有关HS的经验是如何指导目前的ICP治疗的.     

Hybrid braided 3-D scaffold for bioartificial liver assist devices

Three-dimensional ex vivo hepatocyte culture is a tissue-engineering approach to improve the treatment of liver disease. The extracorporeal bioartificial liver (BAL) assists devices that are used in patients until they either recover or receive a liver transplant. The 3-D scaffold plays a key role in the design of bioreactor that is the most important component of the BAL. Presently available 3-D scaffolds used in BAL have shown good performance. However, existing scaffolds are considered to be less than ideal in terms of high-density cultures of hepatocytes maintaining long-term metabolic functions. This study aims to develop a 3-D hybrid scaffold for a BAL support system that would facilitate high-density hepatocyte anchorage with long-term metabolic functions. The scaffolds were fabricated by interlacing polyethylene terephthalate (PET) fibers onto the polysulfone hollow fibers utilizing a modern microbraiding technique. Scaffolds with various pore sizes and porosities were developed by varying braiding angle which was controlled by the gear ratio of the microbraiding machine. The morphological characteristics (pore size and porosity) of the scaffolds were found to be regulated by the gear ratio. Smaller braiding angle yields larger pore and higher porosity. On the other hand, a larger braiding angle causes smaller pore and lower porosity. In hepatocyte culture it was investigated how the morphological characteristics (pore size and porosity) of scaffolds influenced the cell anchorage and metabolic functions. Scaffolds with larger pores and higher porosity resulted in more cell anchorage and higher cellular functions, like albumin and urea secretion, compared to that of smaller pores and lower porosity.     

Energy and material flows of megacities

Understanding the drivers of energy and material flows of cities is important for addressing global environmental challenges. Accessing, sharing, and managing energy and material resources is particularly critical for megacities, which face enormous social stresses because of their sheer size and complexity. Here we quantify the energy and material flows through the world’s 27 megacities with populations greater than 10 million people as of 2010. Collectively the resource flows through megacities are largely consistent with scaling laws established in the emerging science of cities. Correlations are established for electricity consumption, heating and industrial fuel use, ground transportation energy use, water consumption, waste generation, and steel production in terms of heating-degree-days, urban form, economic activity, and population growth. The results help identify megacities exhibiting high and low levels of consumption and those making efficient use of resources. The correlation between per capita electricity use and urbanized area per capita is shown to be a consequence of gross building floor area per capita, which is found to increase for lower-density cities. Many of the megacities are growing rapidly in population but are growing even faster in terms of gross domestic product (GDP) and energy use. In the decade from 2001–2011, electricity use and ground transportation fuel use in megacities grew at approximately half the rate of GDP growth.The remarkable growth of cities on our planet during the past century has provoked a range of scientific inquires. From 1900–2011, the world’s urban population grew from 220 million (13% of the world’s population) to 3,530 million (52% of the world’s population) (1, 2). This phenomenon of urbanization has prompted the development of a science of cities (3, 4), including interdisciplinary contributions on scaling laws (5, 6), networks (7), and the thermodynamics of cities (8, 9). The growth of cities also has been strongly linked to global challenges of environmental sustainability, making the study of urban energy and material flows, e.g., for determining greenhouse gas emissions from cities and urban resource efficiency (10–19), important.At the pinnacle of the growth of cities is the formation of megacities, i.e., metropolitan regions with populations in excess of 10 million people. In 1970, there were only eight megacities on the planet (SI Appendix, Fig. S1). By 2010, the number had grown to 27, and a further 10 megacities likely will exist by 2020 (20). In 2010, 460 million people (6.7% of the global population) lived in the 27 megacities. The sheer size and complexity of megacities gives rise to enormous social and environmental challenges. Megacities often are perceived to be areas of high global risk (i.e., threatened by economic, environmental, geopolitical, societal, and technological risks with potential impacts across entire countries) with extreme levels of poverty, vulnerability, and social–spatial fragmentation (21–24). To provide adequate water and wastewater services, many megacities require massive technical investment and appropriate institutional development (25, 26). Many inhabitants of megacities also suffer severe health impacts from air pollution (27). However, these factors present only one side; the megacities include some of the wealthiest cities in the world (albeit with large disparities between citizens). Even the poorer megacities are seen by some as potential centers of innovation, where high levels of resource efficiency might reduce global environmental burdens (21, 28, 29). Whether megacities can develop as sustainable cities depends to a large extent on how they obtain, share, and manage their energy and material resources.The aims of our study are first to quantify the energy and material flows for the world’s 27 megacities, based on 2010 population, and second to identify physical and economic characteristics that underlie these resource flows at multiple scales. This goal entailed developing a common data-collection process applied to all the megacities. The cities were identified based on Brinkhoff’s database of metropolitan regions (www.citypopulation.de/world/Agglomerations.html; SI Appendix, Fig. S2). The megacities are essentially common commuter-sheds of more than 10 million people; most are contiguous urban regions, but a contiguous area is not a requirement; for example, the London megacity includes a ring of commuter towns outside the Greater London area. Megacities can spread across political borders. They include large tracts of suburban regions, which can have higher per capita resource flows than central areas (30, 31). We quantify energy flows for the dominant direct forms of consumption in megacities. A wide and complex range of materials flow through cities; here the focus is on water, concrete, steel, and waste. We show how values of aggregate resource use of all megacities generally are consistent with the scaling laws that have been developed for cities (5, 6). We then analyze factors correlated with energy and material flow at macro- and microscales; discuss megacities with low, high, and efficient use of resources; and examine changes over time.