多索茶碱及其片剂的高效液相色谱分析

多索茶碱及其片剂的高效液相色谱分析刘春胜，何秀峰，王云萍，谷士杰，周同惠（中国医学科学院、中国协和医科大学药物研究所，北京１０００５０）多索茶碱（ｄｏｘｏｆｙｌｌｉｎｅ）是用于治疗支气管哮喘合并支气管痉挛的慢性阻塞性肺部疾病的新一代黄嘌吟衍生物，其药...     

Asbestos-related focal lung masses: manifestations on conventional and high-resolution CT scans

In 260 asbestos-exposed individuals evaluated by means of computed tomography (CT), 43 unsuspected pulmonary masses were found in 27 individuals. The masses included fissural pleural plaques (n = 10), dense fibrotic bands (n = 3), round atelectasis (n = 11), carcinomas (n = 3), and other presumed benign masses (n = 16). The most helpful features in the diagnosis of rounded atelectasis with CT were (a) contiguity to areas of diffuse pleural thickening, (b) a lentiform or wedge-shaped outline, (c) evidence of volume loss in the adjacent lung, and (d) a characteristic "comet tail" of vessels and bronchi sweeping into the margins of the mass. Less advanced areas of focal atelectasis had fewer classic features. Intrafissural pleural plaques were readily identified with high-resolution CT. In asbestos-related masses, the demonstration of stability over time is necessary. Careful interpretation of CT and high-resolution CT features and close surveillance can obviate the need for biopsy in the majority of instances.     

Facilitating acquisition and transfer of a continuous motor task in healthy older adults and patients with Alzheimer's disease

This study examined the acquisition and transfer of a fine motor skill, namely the rotary pursuit, in 99 patients with Alzheimer's disease (AD) and 100 normal controls (NCs). To identify optimal learning strategies, the authors had participants practice the rotary pursuit under constant, blocked, random, or no training conditions. Transfer was assessed using speeds that were different from those practiced during acquisition. AD patients and NCs receiving constant practice outperformed their peers in the blocked and random conditions during acquisition. Whereas all 3 types of practice facilitated transfer in the NCs, AD patients only benefited from constant practice. The inability of the AD patients to benefit from variable practice suggests that these individuals may have difficulty accessing and/or forming motor schemas.     

An iterative approach to the beam hardening correction in cone beam CT

In computed tomography (CT), the beam hardening effect has been known to be one of the major sources of deterministic error that leads to inaccuracy and artifact in the reconstructed images. Because of the polychromatic nature of the x-ray source used in CT and the energy-dependent attenuation of most materials, Beer's law no longer holds. As a result, errors are present in the acquired line integrals or measurements of the attenuation coefficients of the scanned object. In the past, many studies have been conducted to combat image artifacts induced by beam hardening. In this paper, we present an iterative beam hardening correction approach for cone beam CT. An algorithm that utilizes a tilted parallel beam geometry is developed and subsequently employed to estimate the projection error and obtain an error estimation image, which is then subtracted from the initial reconstruction. A theoretical analysis is performed to investigate the accuracy of our methods. Phantom and animal experiments are conducted to demonstrate the effectiveness of our approach.     

Molecular characterization of severe α-Thalassemias causing hydrops fetalis in Taiwan

α-Thalassemia hydrops fetalis is a common disorder in Taiwan. The condition causes perinatal death and many maternal obstetrical complications. In order to determine the molecular defects of this condition in Chinese, 87 unrelated families with this disorder were collected in the past 4 years. The molecular defects were studied by Southern blotting and DNA hybridization with φζ1-globin gene and LO (a 0.4 kb BamHI/EcoRI fragment in the 5′ flanking region of the ζ2-globin gene) probes. Eighty-one (93.1%) fetuses had homozygous Southeast Asian deletion (– –^SEA/– –^SEA). Five (5.7%) fetuses were compound heterozygotes for the Southeast Asian deletion and Thailand deletion (– –^SEA/– –^THAI). The remaining fetus was a compound heterozygote for the Southeast Asian deletion and an uncharacterized nondeletional defect (– –^SEA/(αα)Th). The molecular defects of α-thalassemia hydrops fetalis in Chinese are heterogeneous. This fact has important implications for genetic counseling and prenatal diagnosis.     

Model for Intravital Microscopic Evaluation of the Effects of Arterial Occlusion-caused Ischemia in Bone

An in vivo model has been developed for chronic observation of the effects of ischemia on cortical bone remodeling and perfused vascularity. Diaphragm occluders were implanted around the right common iliac artery of four rabbits and inflated to produce 10 h of ischemia to the limb. Microcirculation was monitored with intravital microscopy of injected fluorescent microspheres and FITC-Dextran 70 through a bone window, the tibial bone chamber implant (BCI). Bone resorption and apposition in the BCI were indicated with mineralization dyes. Between 2 and 12 h following release of the occluder, secondary ischemia/no-reflow and other evidence of reperfusion injury were observed. Vessel damage was suggested by abnormally high leakage of FITC-D70 from the few vessels perfused during secondary ischemia. In the weeks following occluder release perfused vasculature increased beyond pre-occlusion levels. Net bone resorption reached a maximum when vascularity passed normal levels. In order to further validate the arterial occlusion model for osteonecrosis, techniques for (1) confirming bone death and (2) detecting increased leukocyte adherence to endothelial cells were added. The dead cell stain Ethidium homodimer-1 was used to tag dead osteocytes immediately after occlusion and produced a measure designated osteonecrosis index. To detect leukocytes adhering to vessel walls, carboxyfluorescein diacetate, succinimidyl ester was injected at occluder release. An increase in the number of adherent leukocytes was detected. © 1999 Biomedical Engineering Society. PAC99: 8764Rr, 8717-d, 8719Tt     

Changes of lymphoproliferative responses of T cell subsets to allergen and mitogen after hyposensitization in asthmatic children

The cellular basis for the mechanism of hyposensitization was studied by examining the changes in the numbers and proliferative responses to house dust and phytohemagglutinin (PHA) of T cell subsets of 25 house dust-sensitive asthmatic children before and 1 yr after hyposensitization. The results demonstrated (1) No difference was observed in the mean percentages of OKT3+ cells and OKT8+ cells between normal subjects and patients both before and after hyposensitization, but the absolute numbers of both types of cells in untreated patients were much higher than in the normal subjects or treated patients because of relative lymphocytosis in the untreated patients, (2) While the mean percentage of OKT4+ cells of the untreated patients was lower than that of the normal subjects (40.8 +/- 4.7% vs 44.8 +/- 4.5%, p less than 0.007), the absolute number was higher in the former than that in the latter because of the same reason. After hyposensitization, the mean percentage of the OKT4+ cells was slightly increased, and (3) Hyposensitization was able to restore the proliferative capability to PHA and depress the sensitivity to specific allergen of OKT4+ cells on the one hand and augment the proliferative responses to both PHA and allergen of OKT8+ cells on the other. Taken together, these immunologic changes may explain partly the suppressed IgE-antibody production and decreased lymphoproliferative response to specific allergen after hyposensitization.