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1.
The reference standards methyl 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate (10a), methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate (10b) and corresponding precursors 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylic acid (11a), methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylic acid (11b) were synthesized from methyl crotonate and 3-amino-4-methylbenzoic acid in multiple steps with moderate to excellent yields. The target tracer [11C]methyl 4-(2-methyl-5-(methoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate ([11C]10a) and [11C]methyl 4-(2-methyl-5-(ethoxycarbamoyl)phenylamino)-5-methylpyrrolo[2,1-f][1,2,4]triazine-6-carboxylate ([11C]10b) were prepared from their corresponding precursors with [11C]CH3OTf under basic condition through O-[11C]methylation and isolated by a simplified solid-phase extraction (SPE) method in 50–60% radiochemical yields at end of bombardment (EOB) with 185–555 GBq/μmol specific activity at end of synthesis (EOS).  相似文献   
2.
The last 20 years have seen incredible advances in electron microscopy (EM). Cryoelectron microscopy can now resolve protein structures to a previously unimaginable resolution but the advances in cellular EM are just as significant. I will take this opportunity to briefly summarize some of the new developments in cellular EM.  相似文献   
3.
3,4‐Methylenedioxymethamphetamine (MDMA, ecstasy) use may have long‐term neurotoxic effects. In this study, positron emission tomography with the tracer alpha‐[11C]methyl‐l ‐tryptophan (11C‐AMT) was used to compare human brain serotonin (5‐HT) synthesis capacity in 17 currently drug‐free MDMA polydrug users with that in 18 healthy matched controls. Gender differences and associations between regional 11C‐AMT trapping and characteristics of MDMA use were also examined. MDMA polydrug users exhibited lower normalized 11C‐AMT trapping in pre‐frontal, orbitofrontal, and parietal regions, relative to controls. These differences were more widespread in males than in females. Increased normalized 11C‐AMT trapping in MDMA users was also observed, mainly in the brainstem and in frontal and temporal areas. Normalized 11C‐AMT trapping in the brainstem and pre‐frontal regions correlated positively and negatively, respectively, with greater lifetime accumulated MDMA use, longer durations of MDMA use, and shorter time elapsed since the last MDMA use. Although the possibility of pre‐existing 5‐HT alterations pre‐disposing people to use MDMA cannot be ruled out, regionally decreased 5‐HT synthesis capacity in the forebrain could be interpreted as neurotoxicity of MDMA on distal (frontal) brain regions. On the other hand, increased 5‐HT synthesis capacity in the raphe and adjacent areas could be due to compensatory mechanisms.

  相似文献   

4.
We evaluate the non-linear characteristics of the human lung via image registration-derived local variables based on volumetric multi-detector-row computed tomographic (MDCT) lung image data of six normal human subjects acquired at three inflation levels: 20% of vital capacity (VC), 60% VC and 80% VC. Local variables include Jacobian (ratio of volume change) and maximum shear strain for assessment of lung deformation, and air volume change for assessment of air distribution. First, the variables linearly interpolated between 20% and 80% VC images to reflect deformation from 20% to 60% VC are compared with those of direct registration of 20% and 60% VC images. The result shows that the linearly-interpolated variables agree only qualitatively with those of registration (P<0.05). Then, a quadratic (or linear) interpolation is introduced to link local variables to global air volumes of three images (or 20% and 80% VC images). A sinusoidal breathing waveform is assumed for assessing the time rate of change of these variables. The results show significant differences between two-image and three-image results (P<0.05). The three-image results for the whole lung indicate that the peak of the maximum shear rate occurs at about 37% of the maximum volume difference between 20% and 80% VC, while the peaks for the Jacobian and flow rate occur at 50%. This is in agreement with accepted physiology whereby lung tissues deform more at lower lung volumes due to lower elasticity and greater compliance. Furthermore, the three-image results show that the upper and middle lobes, even in the recumbent, supine posture, reach full expansion earlier than the lower lobes.  相似文献   
5.
Novel conical beam CT-scanners offer high resolution imaging of knee structures with i.a. contrast media, even under weight bearing. With this new technology, we aimed to determine cartilage strains and meniscal movement in a human knee at 0, 1, 5, and 30 min of standing and compare them to the subject-specific 3D finite element (FE) model. The FE model of the volunteer?s knee, based on the geometry obtained from magnetic resonance images, was created to simulate the creep. The effects of collagen fibril network stiffness, nonfibrillar matrix modulus, permeability and fluid flow boundary conditions on the creep response in cartilage were investigated. In the experiment, 80% of the maximum strain in cartilage developed immediately, after which the cartilage continued to deform slowly until the 30 min time point. Cartilage strains and meniscus movement obtained from the FE model matched adequately with the experimentally measured values. Reducing the fibril network stiffness increased the mean strains substantially, while the creep rate was primarily influenced by an increase in the nonfibrillar matrix modulus. Changing the initial permeability and preventing fluid flow through noncontacting surfaces had a negligible effect on cartilage strains. The present results improve understanding of the mechanisms controlling articular cartilage strains and meniscal movements in a knee joint under physiological static loading. Ultimately a validated model could be used as a noninvasive diagnostic tool to locate cartilage areas at risk for degeneration.  相似文献   
6.
Intramuscular fat (IMF) % contributes positively to the juiciness and flavour of lamb and is therefore a useful indicator of eating quality. A rapid, non-destructive method of IMF determination like computed tomography (CT) would enable pre-sorting of carcasses based on IMF% and potential eating quality. Given the loin muscle (longissimus lumborum) is easy to sample, a single measurement at this site would be useful, providing is correlates well to other muscles. To determine the ability of CT to predict IMF%, this study used 400 animals and examined 5 muscles from three sections of the carcass: from the fore-section the m. supraspinatus and m. infraspinatus, from the saddle-section the m. longissimus lumborum and from the hind-section the m. semimembranosus and m. semitendinosus. The average CT pixel density of muscle was negatively associated with IMF% and can be used to predict IMF% although precision in this study was poor. The ability of CT to predict IMF% was greatest in the m. longissimus lumborum (slope −0.07) and smallest in the m. infraspinatus (slope −0.02). The correlation coefficients of IMF% between the five muscles were variable, with the highest correlation coefficients evident between muscles of the fore section (0.67 between the m. supraspinatus and the m. infraspinatus) and the weakest correlations were between the muscle of the fore and hind section. The correlation between the m. longissimus lumborum to the other muscles was fairly consistent with values ranging between 0.34 and 0.40 (partial correlation coefficient). The correlation between the proportion of carcass fat and the IMF% of the five muscles varied and was greatest in the m. longissimus lumborum (0.41).  相似文献   
7.
In pancreatic adenocarcinoma, initial imaging is essential to better select patients for surgery. Recent literature analysis of F18-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET) in pancreatic adenocarcinoma is summarized in the present article. Performances of FDG PET in the fields of lymph node involvement, metastatic involvement and therapeutic efficacy assessment are described for its correct use in pancreatic adenocarcinoma.  相似文献   
8.
Tyrosine kinase inhibitors for epidermal growth factor receptor (EGFR-TKIs) are used as molecular targeted therapy for non-small cell lung cancer (NSCLC) patients. The therapy is applied to the patients having EGFR-primary L858R mutation, but drug tolerance caused by EGFR-secondary mutation is occurred within one and half years. For the non-invasive detection of the EGFR-TKIs treatment positive patients by positron emission tomograpy (PET) imagaing, fluorine-18 labeled thienopyrimidine derivative, [18F]FTP2 was newly synthesized. EGFR inhibition assay, cell uptake study, and blocking study indicated [18F]FTP2 binds with high and selective affinity for EGFR with L858R mutation, and not with L858R/T790M dual mutations. On animal PET study using tumor bearing mice, H3255 cells expressing L858R mutated EGFR was more clearly visualized than H1975 cells expressing L858R/T790M dual mutated EGFR. [18F]FTP2 has potential for detecting NSCLC which is susceptible to EGFR-TKI treatment.  相似文献   
9.
目的:探讨血流剪切力对支架内新生粥样硬化斑块形成的影响。方法:在6只新西兰白兔右髂动脉植入金属裸支架,术后高脂喂养8周。将支架按长度均等分为近中远3段,应用多普勒超声测量各支架段血管的血流速度和血管内径,根据Poiseuille定律计算出术后即刻及术后8周时各支架段的平均血流剪切力。应用光学相干断层成像技术(optical coherence tomography,OCT)检测术后8周支架内新生内膜的生长情况及特性。结果:成功建立支架内斑块动物模型。术后即刻近中远支架段的血流剪切力分别为4.25±0.92,2.49±1.07,1.67±0.49Pa(P0.05);术后8周近中远支架段血流剪切力分别为20.40±6.07,11.09±1.74,7.97±0.26Pa(P0.05),均较术后即刻明显升高(P0.001);术后8周近中远支架段的内膜异质性发生率分别为86.67%,53.33%,41.12%(P0.05);术后8周近中远支架段OCT检测的富含脂质斑块的发生率分别为53.3%,20%,0%(P0.05)。结论:支架内新生粥样硬化斑块的发生可能与较高的血流剪切力相关。  相似文献   
10.
Solving the evolutionary relationships of the acanthodians is one of the key problems in reconstructing ancestral anatomical conditions for the jawed vertebrates (gnathostomes). Current debate concerns whether acanthodians are an assemblage of stem chondrichthyans, or a more generalized grade encompassing some early stem osteichthyans. The skull anatomy of Acanthodes bronni has been pivotal in these debates, owing to tension between chondrichthyan- and osteichthyan-like models of reconstruction. We use computed tomography scanning and traditional palaeontological techniques to resolve the long-standing debate about the anatomy of the jaw suspension. We establish the correct length of the hyomandibula and show that it attaches to a process on the ventrolateral angle of the braincase below the jugular vein groove. This condition corresponds precisely to that in chondrichthyans. This character represents an unambiguously optimized synapomorphy with chondrichthyans given current gnathostome phylogenies, corroborating the growing consensus of the chondrichthyan affinity of acanthodians.  相似文献   
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