Correction of proton resonance frequency shift temperature maps for magnetic field disturbances using fat signal

PURPOSE: To improve the immunity of the proton resonance frequency shift (PRFS) method of MRI temperature mapping against magnetic field disturbances. Since PRFS is a phase-sensitive method, it misinterprets magnetic field disturbances as artifact temperature changes. If not corrected, the resulting temperature artifacts can completely obscure the true temperature estimation, especially if the temperature elevations are small. MATERIALS AND METHODS: Since the fat protons experience the same magnetic field disturbances as the water protons, but no temperature-related frequency shift, the fat signal has been used for correcting PRFS temperature maps for the disturbances. A simple correction method is proposed that has either better compensation capability than the phase correction methods previously reported or higher spatial and temporal resolution than the spectroscopic correction methods previously reported. The evaluated method is based on the utilization of several gradient and spin echoes acquired within one repetition interval with water- and fat-selective scans. RESULTS: In a series of phantom experiments, the improved method is shown to enable the reconstruction of accurate temperature maps in spite of interscan motion, suboptimal fat-water separation, and a wide range of magnetic field disturbances. CONCLUSION: Our approach can be used for the guidance of thermal therapies involving tissues containing fat or surrounded by fat.     

Thermal ablation of lung tumors

Thermal ablation can be applied to treat any thoracic malignancy: primary lung cancers, recurrent primary lung cancers, metastatic disease, chest wall masses, and painful, bony metastases. Since the first reported use of thermal ablation for lung cancer in 2000 there has been an explosive use of the procedure, and by 2010 the number of procedures to treat thoracic malignancy is expected to exceed 150,000 per year. Presently, thermal ablation is best used for patients with early-stage lung cancers in patients who are not surgical candidates, patients with small and favorably located pulmonary metastases, and patients in whom palliation of tumor-related symptoms is the goal. Radiofrequency ablation, microwave ablation, and cryoablation are novel treatment modalities for lung cancer and can safely accomplish tumor destruction and even complete eradication of tumor in patients who are not candidates for surgical resection. In this article, we discuss technical considerations for each modality and the periprocedure and postprocedure management of patients with this disease.     

Developing an interstitial ultrasound applicator for thermal ablation in liver: results of animal experiments

BACKGROUND: In this project, an interstitial ultrasound applicator was developed for the treatment of primary and secondary cancers of the liver. Experiments on animals were used to check the destructive capabilities of this probe within the hepatic parenchyma of the pig in vivo, with a study of the physical parameters of the ultrasound treatment. In parallel, the possibility of visualizing the lesions induced by means of ultrasound imaging was also studied. MATERIALS AND METHODS: Thirteen pigs were used in this project, which had received the prior approval of the ethics committee of Lyon Veterinary School. Ultrasound lesions were performed by varying the physical parameters of the treatment (acoustic intensity and shot time) with the aim of obtaining larger and larger areas of destruction. An operative device was developed to ensure precision in treatments. Two types of lesions were performed: elementary lesions corresponding to single shots at 40 degrees to 50 degrees rotation intervals, and cylindrical lesions obtained by a continuous rotary deployment of the probe. The effect of hepatic pedicle clamping on the size of ultrasound lesions was studied. The aspect and dimension of the lesions were analyzed by means of operative ultrasound imaging and macroscopic examination. Histological analysis showed the impact of the treatment on the hepatic parenchyma. RESULTS: This work made it possible to study the elementary ultrasound lesions produced by our probe. Seventy elementary ultrasound lesions were analyzed. Treatments could be performed on all pigs without any difficulty. There were no operative incidents. The ultrasound-induced elementary lesions showed complete necrosis, with lesion length of up to 37 mm obtained without resort to pedicle clamping; this must be considered as a radius of the final lesion obtained over a complete rotary deployment (360 degrees ), then a diameter of 7 cm of thermal ablation can theoretically be obtained. The effect of pedicle clamping was studied and showed improvement of the lesion length. Results of continuous rotary deployment of the probe were encouraging. Operative ultrasound imaging proved to be a simple tool for directing and positioning the applicator in the target zone on the one hand and which, on the other hand, enabled accurate, real-time visualization of the ultrasound lesions. On histological analysis, the ultrasound-induced necrosis was complete and well defined. CONCLUSION: This work shows that it is feasible to treat cancers of the liver using interstitial ultrasound probe. Thermal damage obtained on the hepatic parenchyma of pigs in vivo is complete and can be monitored using simple diagnostic ultrasound. The ultrasound parameters can be adapted to obtain destruction of variable size.     

Exposure of developing well-nourished and malnourished rats to environmental heating facilitates cortical spreading depression propagation at adulthood

Cortical spreading depression (CSD) is a brain electrical response related to neural activity and probably also related to diseases like migraine and epilepsy. Adverse conditions like malnutrition and exposure to a warm environment early-in-life can permanently alter brain development, changing electrophysiological features of the brain responses and rendering the brain prone to febrile seizures. Here we investigated the lasting effects of heat exposure on brain CSD propagation in well-nourished and malnourished developing rats. From postnatal days 10–29, rats were exposed to daily sessions (one session per day, five sessions per week during 3 weeks; total of 15 sessions) of a warm environment (40 ± 2 °C). At 30–40 days and 90–120 days of life (young and adult age-ranges, respectively), they were anesthetized (urethane + chloralose; 1000 + 40 mg/kg ip) and the electrocorticogram plus the slow potential change accompanying CSD were recorded on two parietal points for 4 h. Compared to controls (maintained on the normal environment temperature, 23 ± 2 °C), heat-exposed rats displayed higher CSD velocities of propagation (P < 0.05; ANOVA plus Tukey test) at both age-ranges and nutritional statuses. The mean ± S.D. CSD velocities (in mm/min) were: for control- and heat-exposed well-nourished rats, 3.75 ± 0.15 and 4.17 ± 0.19 (young groups), and 3.33 ± 0.06 and 3.88 ± 0.26 (adult); for the same control and heat exposure conditions in the malnourished rats, 4.30 ± 0.22 and 5.31 ± 0.46 (young), and 4.18 ± 0.20 and 4.88 ± 0.35 (adult). In contrast to early malnutrition, heat exposure did not affect body and brain weights. Data support the hypotheses that (1) early heat exposure long-lasting facilitates CSD propagation and (2) this effect is not modified by early malnutrition.     

The contributing role of CD14 in toll-like receptor 4 dependent neuropathic pain

We have previously demonstrated that CNS toll-like receptor 4 (TLR4) plays a key role in the development of behavioral hypersensitivity in a rodent model of neuropathic pain, spinal nerve L5 transection (L5Tx). TLR4 is a well-known receptor for lipopolysaccharide (LPS) in innate immune responses. In the current study, we further investigated the role of CD14, an accessory molecule in the LPS-TLR4 signaling pathway, in the development of L5Tx-induced neuropathic pain. CD14 knockout (KO) mice displayed significantly decreased behavioral sensitivity (mechanical allodynia and thermal hyperalgesia) as early as day 1 post-L5Tx, indicating a nociceptive role of CD14. By flow cytometric analyses, we observed significantly elevated microglial surface CD14 expression in the ipsilateral lumbar spinal cord 3 days post-L5Tx, as well as remarkable increases in microglial size (via forward scatter (FSC)) and granularity (via side scatter (SSC)). Further, intrathecal injection of soluble CD14 induced significantly greater mechanical hypersensitivity in wild type (C3H/HeN) mice compared with TLR4-deficient (C3H/HeJ) mice. Together, these data demonstrate that CD14 plays a contributing role in TLR4-dependent nerve injury-induced neuropathic pain.     

Host-dependent roles of the viral 5′ untranslated region (UTR) in RNA stabilization and cap-independent translational enhancement mediated by the 3′ UTR of Red clover necrotic mosaic virus RNA1

The genome of Red clover necrotic mosaic virus (RCNMV) consists of RNA1 and RNA2, both lacking a cap structure and a poly(A)tail. RNA1 has a translational enhancer element (3′TE-DR1) in the 3′ untranslated region (UTR). In this study, we analyzed the roles of 5′ and 3′ UTRs of RNA1 in 3′TE-DR1-mediated cap-independent translation in cowpea and tobacco BY-2 protoplasts using a dual-luciferase (Luc) reporter assay system. Most mutations introduced into RNA1 5′ UTR in reporter Luc mRNA abolished or greatly reduced cap-independent translation in BY-2 protoplasts, whereas those mutations had no or much milder effects if any on translational activity in cowpea protoplasts. Our results suggest that a stem-loop structure predicted in the 5′ proximal region of RNA1 plays important roles in both translation and RNA stability. We also show that 3′TE-DR1-mediated cap-independent translation relies on a ribosome-scanning mechanism in both protoplasts.     

Effect of seat surface inclination on postural stability and forward reaching efficiency in children with spastic cerebral palsy

The purpose of this study was to examine the effect of seat surface inclination on postural stability and forward reaching efficiency in 10 children with spastic cerebral palsy (CP) and 16 typically developing (TD) children. The children performed a static sitting and a forward reaching task while sitting on a height- and inclination-adjustable stool at flat, three anterior-inclined, and three posterior-inclined positions. Postural stability was expressed as normalized (with body weight) peak vertical ground reaction force, center of pressure displacement in the anterior/posterior directions (COP_AP), in the medial/lateral directions (COP_ML), and sway ratio (COP_AP/COP_ML). Reaching efficiency was expressed as reaction time and movement time of arm reaching forward to a target. The results showed that seat inclination affected children's postural stability and the effects were comparable for CP and TD children in all measures except for COP_ML. Children with CP presented much larger COP_ML than TD children at the posterior-inclined positions relative to the flat and the anterior-inclined positions. Seat inclination affected reaching efficiency for both groups of children equally. Efficiency was better at the anterior positions than the posterior positions. Anterior-inclined positions improved postural stability and reaching efficiency. Posterior positions posed greater postural challenge and the challenge was tougher for children with CP.     

Stability of symptoms across major depressive episodes in bipolar disorder

Objective: Some studies suggest that depressive subtypes, defined by groups of symptoms, have predictive or diagnostic utility. These studies make the implicit assumption of stability of symptoms across episodes in mood disorders, which has rarely been investigated. Methods: We examined prospective data from a cohort of 3,750 individuals with bipolar I or II disorder participating in the Systematic Treatment Enhancement Program for Bipolar Disorder study, selecting a subset of individuals who experienced two depressive episodes during up to two years of follow‐up. Across‐episode association of individual depressive or hypomanic/mixed symptoms was examined using the weighted kappa measure of agreement as well as logistic regression. Results: A total of 583 subjects experienced two prospectively observed depressive episodes, with 149 of those subjects experiencing a third. Greatest evidence of stability was observed for neurovegetative features, suicidality, and guilt/rumination. Loss of interest and fatigue were not consistent across episodes. Structural equation modeling suggested that the dimensional structure of symptoms was not invariant across episodes. Conclusion: While the overall dimensional structure of depressive symptoms lacks temporal stability, individual symptoms including suicidality, mood, psychomotor, and neurovegetative symptoms are stable across major depressive episodes in bipolar disorder and should be considered in future investigations of course and pathophysiology in bipolar disorder.     

Direct medical costs for patients seeking emergency care for losses of epilepsy control in a U.S. managed care setting

The objective of this retrospective claims database study was to compare the costs of care from a U.S. payer perspective before and after epilepsy treatment in emergent care settings and, secondarily, to describe the frequency of toxic effects and physical injuries occurring on the date of the emergent care. Nine and four-tenths percent of patients receiving emergent care for epilepsy (114/1213) had an injury or adverse antiepileptic drug effect on the same date. The majority of incidents were superficial injuries and contusions (28%), fractures (21%), open wounds or injury to blood vessels (19%), intracranial injury (10%), and/or medication toxicity (10%). Both non-epilepsy-related (US$12,745.56) and epilepsy-related (US$2013.62) direct medical costs of care pre-index were significantly different from those post-index (US$15,274.95 and US$7087.53, respectively). The cost of care for possible reestablishment of epilepsy control and treatment of co-occurring injuries is significant when compared with that for the period prior to seizure.     

螺钉数量对钢板螺钉内固定结构载荷的生物力学影响

背景：根据目前生物力学内固定要求的提出,课题根据临床中部分骨折区域或者多段骨折处无法固定螺钉的实际情况,探讨部分钢板的螺钉孔不固定螺钉后对钢板螺钉内固定结构的稳定性。 目的：观察螺钉数量对钢板螺钉结构稳定性的影响。 设计、时间及地点：随机分组设计,对比观察,于2007-03/2008-05在南昌大学医学院和南昌航空航天大学完成。 材料：24个新鲜尸体股骨标本,由南昌大学医学院解剖实验室提供。钛合金动力加压钢板24块,为康辉医疗器械有限公司产品。 方法：每个股骨模拟横断骨折,一块12孔的动力加压钢板对称性固定,每块钢板贴3个(分别编号ε1,ε2,ε3)应变计与钢板长轴平行。24个股骨骨折标本随机分为4组,每组6个标本。按下列分组连续进行测试：A组：1-2-6(1-2-6表示螺钉位置);B组：1-2-3-6;C组：1-2-3-4-6;D组：1-2-3-4-5-6。 主要观察指标：在材料实验机上分别进行平行矢状面方向的三点折弯实验,观察应力为200,400 N时各组钢板的应变、挠度;随后进行扭转实验,观测股骨的扭转角度为1.428°,2.142°时各组钢板的应变变化。 结果：①在三点折弯实验中,A组中骨折端的平均应变最大,D组中骨折端的平均应变最小。A组和C组,A组和D组,B组和D组之间钢板的平均应变差异均有显著性意义(P < 0.05),其余各组之间差异均无显著性意义(P > 0.05)。在200 N和400 N的压应力作用下,A、B、C、D各组间挠度变化值两两相比,差异均有显著性意义(P < 0.05)。与200 N压应力作用相比,400 N压应力作用挠度变化更大(P < 0.05)。②扭转角度在2.142°内,各组样本在钢板中央应变差异均有显著性意义(P < 0.05)。其中B组钢板应变最低,D组钢板应变最高,在钢板中央的应变与扭转角度呈正相关。 结论：螺钉数量对钢板螺钉内固定结构系统的稳定性有显著性影响,较少固定螺钉的数量,增加了钢板螺钉内固定结构的弹性形变能力。