冠状动脉运动规律的磁共振电影成像研究

目的利用磁共振电影成像研究冠状动脉的运动规律.方法选取不同心率的志愿者35例,使用电影成像序列显示冠状动脉断面的运动轨迹,以5% R-R间期为标准化时间单位(NTU),分析冠状动脉运动轨迹和速度的特征.结果冠状动脉各分支的运动轨迹存在个体差异.当心率小于75 bpm时,RCA和LCX在ECG触发延迟75% R-R的舒张中期和40% R-R的收缩末期运动速度小于3 mm/NTU,LAD在整个心动周期运动速度基本都小于3 mm/NTU.结论心率小于75 bpm时,建议选择舒张中期进行冠状动脉的断层采样或者重建.     

正常舟月韧带厚度超声与MRI研究

目的提供舟月韧带厚度(SLLT)超声测量正常值,评价超声测量舟月韧带厚度的准确性.方法用超声高频探头探查200只正常手腕,与MRI测量其中的30人60只手腕比较.记录超声和MRI图像上SLLT测值.结果舟月韧带在背侧部正中位声像图最清晰.男、女性舟月韧带背侧部厚度(SLLTd)分别为(2.18±0.35) mm和(1.99±0.23) mm.超声与MRI在测量SLLT相关性比较呈直线相关(P<0.01).结论超声能够清晰显示并准确测量舟月韧带的厚度.     

大鼠脂肪和骨髓来源间充质干细胞基本生物学特征的比较

目的:分离大鼠脂肪和骨髓来源的间充质干细胞,比较两种间充质干细胞的生物学特征。方法:实验于2003-09/2006-11在广州市第一人民医院、湘雅医院中心实验室完成。取SD大鼠的股骨、胫骨、肱骨及腹股沟处脂肪垫进行骨髓间充质干细胞与脂肪间充质干细胞的分离。将骨髓间充质干细胞和脂肪间充质干细胞在含10%血清,1%双抗的低糖DMEM培养基,37℃、体积分数为0.05的CO2条件下进行培养。在细胞达到80%～90%融合时,使用0.25%胰酶消化传代。传代至第3代使用倒置显微镜观察骨髓和脂肪两种不同来源细胞的传代后的形态、贴壁、生长增殖、集落等情况。取消化传3代的两种细胞分别制成单细胞悬液进行细胞贴壁率的检测,贴壁率=贴壁细胞总数/接种细胞总数×100%。取第2代和第5代骨髓间充质干细胞和脂肪间充质干细胞以1×107L-1密度培养。每天同一时间,随机抽取5孔细胞,加入5%噻唑兰20μL/孔,培养4～6h,吸出孔内液体,每孔加150μL二甲基亚砜震荡10min,酶联免疫测定仪测定波长490nm处的吸光度,取5孔吸光度的均值,以时间为横坐标,吸光度值为纵坐标,绘制生长曲线。采用流式细胞仪检测细胞表面CD29、CD34、CD44标记,免疫化学检测细胞CD29、CD34、CD44。结果:①在单位质量骨髓和脂肪组织中获得的间充质干细胞数量相当。两种细胞形态均为条索样,呈成纤维细胞形态。②应用直线相关分析,考察骨髓贴壁率与脂肪贴壁率之间的关系,相关系数r=0.999,决定系数r2=0.997(F=5862.949,P<0.001),两贴壁率之间有直线相关关系,不同的时间点两种细胞的贴壁率相似,并且有同向变化的趋势。③脂肪间充质干细胞的增殖能力与骨髓间充质干细胞相当。④脂肪间充质干细胞和骨髓间充质干细胞表面表达CD29、CD44,不表达CD34。结论:自大鼠脂肪中可提取出与骨髓间充质干细胞生物学特征类似的脂肪间充质干细胞。     

Coordinate glycosylation and cell surface expression of glycophorin A during normal human erythropoiesis

The expression of two epitopes on glycophorin A (GPA) during erythroid development was examined on normal human bone marrow using quantitative flow cytometry. The highly correlated binding of two monoclonal antibodies, one sensitive and the other insensitive to glycosylation, indicated that the two epitopes were coordinately expressed during erythroid development. Both antigens reached a maximum expression during the early normoblast stage and were maintained at a constant amount per cell throughout further maturation to erythrocytes. These data suggest that glycosylation of GPA, as detected by antibodies recognizing blood group (M) and (N) antigens, does not increase during erythroid maturation.     

Long-term culture-initiating cell expansion is dependent on frequent medium exchange combined with stromal and other accessory cell effects

Despite considerable effort, the expansion of long-term culture- initiating cells (LTC-ICs) in cultures of purified hematopoietic cells has not yet been achieved. In contrast, LTC-IC expansion has been attained in cultures of bone marrow mononuclear cells (MNC) using frequent medium exchange. The use of frequent medium exchange was, therefore, examined in cultures of CD34-enriched cells. In stromal- free, CD34-enriched cell cultures, medium exchange intervals ranging from 2 days to no feeding for 14 days gave similar results. Six different growth factor combinations, reported by other groups to give optimal expansion of CD34-enriched cells, were tested in comparison with the control combination of IL-3/GM-CSF/Epo/SCF. None of the combinations resulted in improved colony-forming unit-granulocyte macrophage (CFU-GM) expansion or LTC-IC maintenance, although two were equivalent. All stromal-free cultures resulted in loss of LTC-IC to half of input. Because of the limited effect of medium exchange and growth factor variations on CD34-enriched cell cultures, the effect of preformed stroma was next examined. Preformed stroma increased cell (3- fold), CFU-GM (5-fold), and LTC-IC (3-fold) output, but only when the medium was exchanged every other day. Under these conditions, the number of LTC-IC was maintained near input level. The lack of LTC-IC expansion in CD34-enriched cell cultures prompted experiments to examine the effect of cell purification. Parallel cultures were performed at CD34+lin- cell purities of 20%, 40%, 70%, and 95%, with each well containing exactly 4,000 CD34+lin- cells in addition to the CD34- accessory cells required to give the desired percentage. Also, MNC from the same source (approximately 2% CD34+lin-) were cultured at a concentration to give 4,000 CD34+lin- cells per well. As CD34+lin- cell purity was decreased from 95% to 2%, the output of cells, CFU-GM, and LTC-IC increased by threefold to fivefold. The loss of culture performance with purification was likely due to the removal of important accessory cells, because the levels of endogenously produced leukemia inhibitory factor and IL-6 were found to decline significantly with increasing CD34+lin- cell purity. In summary, preformed stroma abrogated the decrease in cell and CFU-GM output from cultured CD34- enriched cells and led to LTC-IC maintenance. In contrast, MNC inocula resulting in a growing stromal layer during the culture led to LTC-IC expansion (3.2-fold).(ABSTRACT TRUNCATED AT 400 WORDS)     

Thalidomide as salvage therapy for chronic graft-versus-host disease

Thalidomide has been reported to be an effective agent for treatment of chronic graft-versus-host disease (CGVHD). To determine the efficacy of this agent in patients with refractory CGVHD a total of 80 patients who failed to respond to prednisone (PSE) or PSE and cyclosporine (CSA) were treated with thalidomide. Sixteen patients (20%) had a sustained response, 9 with a complete remission and 7 with a partial response. Twenty-nine patients (36%) had thalidomide discontinued because of side effects, which included sedation, constipation, neuritis, skin rash, and neutropenia. Side effects were reversible with drug discontinuation except for mild residual neuritis in one case. Rashes and neutropenia have not previously been reported as thalidomide side effects when used for CGVHD treatment. We conclude thalidomide is immunosuppressive and active in the treatment of CGVHD. A high incidence of reversible side effects limited dose intensity and reduced the number of patients who could benefit from treatment.     

Effect of cholecystokinin on lower oesophageal sphincter pressure and transient lower oesophageal sphincter relaxations in humans.

The effect of cholecystokinin (CCK) on the lower oesophageal sphincter (LOS) pressure, frequency of transient LOS relaxations, and the number of reflux episodes was investigated in six healthy subjects. LOS pressure was recorded on four separate occasions during continuous intravenous infusion of either saline or CCK-33 in doses of 0.25, 0.5, or 1.0 Ivy Dog units per kg body weight per hour (IDU.kg-1.h-1) for 90 minutes. Plasma CCK concentrations did not change during saline infusion, but increased significantly from 2.5 (0.3) pmol/l to steady state levels of 4.0 (0.4) pmol/l, 6.1 (0.4) pmol/l, and 9.3 (0.9) pmol/l respectively starting from 30 minutes. LOS pressure did not change significantly during infusion of saline or of CCK-33 at doses of 0.25 or 0.5 IDU.kg-1.h-1. However, a significant (p < 0.05) reduction in LOS pressure to a minimum level of 12 (4) mm Hg at 30 minutes compared with basal level (18 (4) mm Hg) and compared with saline was observed during infusion of CCK-33 at a dose of 1.0 IDU.kg-1.h-1. In addition, oesophageal motility and pH were recorded simultaneously in these six subjects on two separate occasions one hour before (fasting) and three hours during administration of a gastric load (dextrose 5%, pH 3) combined with continuous intravenous infusion of saline or CCK-33 at a dose of 1.0 IDU,kg-1.h-1. Plasma CCK concentrations did not change during the gastric load combined with saline, but increased significantly to a steady state level of 10.8 (0.8) pmol/l during intravenous infusion of CCK. The number of transient LOS relaxations increased significantly in the first hour during administration of the gastric load compared with fasting levels, both during saline infusion (fasting: 1.7 (0.6)/h, 1st hour: 4.3 (1.2)/h) and during CCK infusion (fasting: 1.7 (0.5)/h, 1st hour: 3.8 (0.7)/h). In the second and third hours the number of transient LOS relaxations fell to fasting levels in both experiments. No significant differences were observed in the number and type of transient LOS relaxations, mechanism of gastro-oesophageal reflux, or duration of acid exposure between the two experiments. It is concluded that in healthy subjects infusion of CCK-33 in a dose of 1.0 IDU.kg-1.h-1 significantly reduces LOS pressure but does not affect the frequency of transient LOS relaxations or acid exposure time during a continuous liquid gastric load.     

Myeloperoxidase: an enzyme involved in intrinsic vincristine resistance in human myeloblastic leukemia

One of the differences between acute myeloblastic leukemia (AML) and acute lymphoblastic leukemia (ALL) is their sensitivity to vincristine. Although vincristine plays an important role in chemotherapeutic regimens for ALL, it does not possess clinically significant activity in AML. Horseradish peroxidase, a heme-centered peroxidase, oxidatively degrades Vinca derivatives and thereby abrogates their cytotoxic activity. This finding suggested that myeloperoxidase (MPO), a heme- centered peroxidase characteristically found in AML and not in ALL, might also degrade vincristine. We first examined the effects of MPO on vincristine in a cell-free system and demonstrated that this enzyme is capable of catalyzing vincristine's oxidative breakdown. We also observed that vincristine is more rapidly degraded in tissue culture by MPO-positive HL-60 cells than by a MPO-negative HL-60 subclone. The degree of MPO activity in these cell lines correlated in a positive manner with their degree of resistance to vincristine's cytotoxic activity. Moreover, the differential resistance to vincristine observed between these cell lines could be increased by increasing the concentration of H2O2 available to the enzyme. These data support the hypothesis that MPO-mediated oxidation of vincristine accounts in part for this drug's lack of activity in AML.     

B-cell homotypic adhesion through exon-A restricted epitopes of CD45 involves LFA-1/ICAM-1, ICAM-3 interactions, and induces coclustering of CD45 and LFA-1

Lymphocyte interactions with other leukocytes and other cell types, as well as with components of the extracellular matrix, are one of the key steps in the immune response. Three novel monoclonal antibodies (MoAbs) have been produced and selected for their ability to induce intercellular adhesion in B cells. These three MoAbs immunoprecipitated a polypeptide of 220 kD, displaying specific phosphotyrosine phosphatase activity that has been identified as CD45. These MoAbs recognize epitopes located on the alternative spliced exon-A-encoded region of CD45. These epitopes are of polypeptidic nature, but they can be masked by addition of carbohydrate during CD45 biosynthesis. Interestingly enough, CD45 epitopes recognized by these MoAbs appeared to be selectively expressed on both peripheral blood and tonsillar B lymphocytes as well as on peripheral blood natural killer (NK) cells. CD45-mediated intercellular adhesion was abrogated upon incubation with anti-leukocyte function-associated antigen 1 (anti-LFA-1), intercellular cell adhesion molecule 1 (ICAM-1), and ICAM-3 MoAbs, thus indicating that this phenomenon involved both LFA-1/ICAM-1 and LFA- 1/ICAM-3 cell adhesion pathways. Moreover, CD45-mediated cell aggregation was also inhibited by preincubation with some conventional anti-CD45 MoAbs. Interestingly, the triggering of cell aggregation through CD45 induced membrane surface relocation of CD45 and LFA-1 molecules, with both of them colocalizing at cell-cell contact areas of B-cell aggregates. Studies with inhibitors of both phosphotyrosine phosphatase and tyrosine kinase activities suggest that CD45 phosphotyrosine phosphatase activity could be involved in CD45-mediated cell aggregation. Taken together, these results support the notion that CD45 is a key molecule in the regulation of LFA-1-mediated cell-cell interactions.