大鼠黑质多巴胺能神经元衰老性变化的多项参数测量

目的:探讨大鼠中脑黑质多巴胺能神经元的衰老性变化规律,为进一步揭示黑质病变的病因提供客观依据。方法:实验于2005-07/2006-07在贵阳医学院解剖学教研室完成。选择健康SD大鼠32只,雌雄各半,按随机数字表法分为幼年组(1～2个月龄)、青年组(4～5个月龄)、中年组(11～12个月龄)、老年组(≥24个月龄)4组,每组8只。取中脑组织常规石蜡包埋,行中脑黑质连续冠状切片,焦油紫染色、酪氨酸羟化酶免疫组织化学染色,图像分析仪测量酪氨酸羟化酶免疫阳性产物的吸光度值和酪氨酸羟化酶免疫反应阳性神经元的胞面积、体密度、数密度、圆球度。结果:32只大鼠均进入结果分析。①中脑黑质焦油紫染色形态学观察:幼年组与青年组大鼠黑质神经元胞体大,细胞排列密集,形状规则,细胞成椭圆形或锥体形,胞浆丰富,每个细胞有清晰的胞核,核仁清楚可见,尼氏体粗大而染色深,中年组和老年组大鼠神经元胞浆染色较淡,尼氏体较分散,细胞散在,数量少,可见软化灶形成。幼年组、青年组、中年组、老年组计数单位面积焦油紫染色细胞数分别为(48.00±9.10),(65.00±8.73),(20.00±4.10),(13.25±1.83)个/40倍视野,各组间比较差异有显著性意义(F=3.79,P<0.05)。②中脑黑质酪氨酸羟化酶免疫反应阳性神经元:光镜下,酪氨酸羟化酶免疫反应阳性神经元成群分布,胞浆内阳性产物以幼年组和青年组为显著,中年组和老年组胞浆内酪氨酸羟化酶阳性反应颗粒明显减少,部分神经元丧失大多角形或锥体形形状,胞体变大,排列不规则,数量减少。幼年组、青年组、中年组、老年组胞浆内酪氨酸羟化酶免疫反应阳性产物吸光度值分别为0.1993±0.0711,0.2428±0.1729,0.1978±0.0687,0.1671±0.1018,各组间比较差异有显著性意义(F=1.87,P<0.05)。中年组、老年组酪氨酸羟化酶免疫反应阳性神经元体密度、数密度低于青年组,差异有显著性意义[体密度分别为(2.57±0.02),(2.36±0.01),(3.22±0.01)×10-2μm-3,t=0.66,1.78,P<0.05;数密度分别为(0.91±0.04),(0.59±0.03),(1.20±0.09)×10-5μm-3,t=7.02,2.25,P<0.05]。幼年组平均截面积低于青年组,差异有显著性意义[分别为(27.30±5.56),(30.40±1.08)×101μm2,t=1.47,P<0.05]。幼年组、中年组、老年组平均体积低于青年组,差异有显著性意义[分别为(9.67±0.40),(5.85±0.42),(5.20±0.33),(11.53±0.90)×102μm3,t=1.60,2.93,0.18,P<0.05]。老年组神经元圆球度低于幼年组、青年组、中年组,差异有显著性意义(分别为0.74±0.18,0.91±0.01,0.92±0.05,0.90±0.03,t=0.68,0.99,1.02,P<0.05,0.001)。结论:黑质多巴胺能神经元随年龄增长而出现衰老性变化,可能是黑质病变的原因之一。     

Monocyte-platelet interaction in immune and nonimmune thrombocytopenia

Platelets from 24 patients with immune thrombocytopenia resistant to standard therapy (refractory ITP), 35 patients with nonimmune thrombocytopenia (non-ITP), and 32 normal donors were studied in regard to platelet surface-bound IgG (PBIgG) and the ability of these platelets to be bound by human monocytes in vitro (monocyte-platelet rosette assay). Fourteen (58%) of the platelet samples from refractory ITP patients but none (0%) from the non-ITP or control donors had PBIgG greater than 800 molecules IgG/platelet. Seventeen of 24 (71%) of the ITP patients had platelets which demonstrated increased monocyte- platelet rosette formation [rosette index (RI) greater than 2], whereas only four (11%) of the non-ITP patients had such platelets. There was a direct correlation between PBIgG and rosette index for the platelets from resistant ITP patients. There was no correlation of severity of thrombocytopenia with PBIgG or rosette index. Monocyte-platelet interaction in the presence of elevated PBIgG is mediated through the monocyte Fc-receptor. Platelets from five of ten refractory ITP patients with PBIgG less than 800 molecules IgG/platelet had increased rosette formation. Monocyte-platelet interaction in the absence of increased PBIgG may be due to small amounts of platelet surface IgG which are still able to mediate monocyte Fc-receptor interaction or to alternate membrane receptor interaction through the monocyte C3 receptor. Our data underscore the pathophysiologic relevance of monocyte/macrophage-mediated interaction in immune platelet destruction syndromes.     

组织胺通过H2受体抑制前列腺素E2刺激家兔十二指肠碳酸氢的分泌

十二指肠粘膜分泌的碳酸氢（ＨＣＯ３）是重要的“防御因子”之一。前列腺素Ｅ２（ＰＧＥ２）强烈刺激十二指肠ＨＣＯ３的分泌。本实验示，组织胺可抑制家兔近端十二指肠由ＰＧＥ２刺激引起的ＨＣＯ３－分泌（从０．４０±０．０３至０．０８±０．０ｌμｏｌ／ｃｍ２·ｈ，Ｐ＜０．０１）。此抑制作用可被神经毒素（ＴＴＸ）及Ｈ２受体拮抗剂一西咪替丁阻断（分别为０．３７±０．０６，０．４４±０．０２μｍｏｌ／ｃｍ２·ｈ），但不能被Ｈ１及Ｈ３受体拮抗剂所阻断。提示十二指肠肥大细胞、组织胺参与其ＨＣＯ３－分泌的调节，具体环节可能通过十二指肠神经丛的Ｈ２受体。     

Cromolyn sodium is effective in adult chronic asthmatics

We studied 68 chronic asthmatic patients, 18 to 76 yr of age, with a percent predicted FEV1 between 33 and 81, comparing cromolyn sodium with placebo. We used a double-blind, comparative group trial design. A 4-wk baseline period was followed by 3 months of active treatment or placebo. Patients recorded symptom severity and frequency of study drug and concomitant medication usage on daily diary cards. At each clinic visit, patients independently assessed the effectiveness of the test medication in controlling their asthma. Physicians also assessed the severity of the patients' symptoms, pulmonary function, and effectiveness of test medication at monthly intervals. Methacholine challenges were done pre- and post-treatment. Use of concomitant therapy was reduced according to a specified schedule. There was significant improvement in the severity of daytime asthma, nighttime asthma, and cough as assessed by the patients in the cromolyn sodium group. Mean use of concomitant medications decreased significantly in cromolyn sodium patients. Despite the reductions in the use of bronchodilators, pulmonary function (FEV1, FVC, FEF25-75) improved significantly in the cromolyn sodium group. Similar improvements did not occur in the control group. The physicians' assessments of symptoms showed significant improvement in favor of the cromolyn sodium group. Both physicians and patients judged cromolyn sodium to be moderately or very effective for 61% of the patients as compared to 27% (by physicians) and 24% (by patients) in the placebo group. There was no significant difference in methacholine response between the two groups, although the mean value for methacholine sensitivity in the cromolyn sodium group was significantly less at the end of the study than at baseline.(ABSTRACT TRUNCATED AT 250 WORDS)     

Existence of both fast and slow channel activity during the early stages of ventricular fibrillation.

Although sodium channels have been reported to be inactive after 5-10 minutes of ventricular fibrillation (VF), their state during early VF is unknown. In 12 open-chest dogs, a floating glass microelectrode was used to record intracellular action potentials from the right ventricle during pacing and during electrically induced VF. Before any drug was administered, an initial episode of VF was continuously recorded for at least 20 seconds followed by defibrillation. Recordings were made during VF episodes after superfusion for 15 minutes around the microelectrode site by low (2.8 x 10(-5) M) and high (10(-4) M) concentrations of tetrodotoxin (TTX) in five dogs, or by low (4 microM) and high (100 microM) concentrations of verapamil in another four dogs. In three dogs, VF was induced without drugs three times to determine if the effects observed in the previous dogs were caused by the drugs or by successive episodes of VF. Ten consecutive action potentials were analyzed at the onset and after 5, 10, 15, and 20 seconds of VF. Action potential amplitude and duration during paced rhythm or VF were not changed by the local perfusion of either TTX or verapamil. In the TTX group, the maximum upstroke rate of depolarization of an action potential (Vmax) during paced rhythm was 104 +/- 14 V/sec for control cycles before any drug was given, 86 +/- 15 V/sec for the low TTX concentration, and 55 +/- 14 V/sec for the high TTX concentration (p less than 0.05 versus other two). Vmax decreased from 55 +/- 32 V/sec at the beginning of VF to 37 +/- 27 V/sec after 20 seconds of VF for predrug VF, from 39 +/- 20 V/sec to 18 +/- 11 V/sec for low-dose TTX VF, and from 18 +/- 13 V/sec to 12 +/- 7 V/sec for high-dose TTX VF (p less than 0.05 among the three groups). In the dogs receiving verapamil, VF was still inducible with Vmax not significantly different from predrug VF at the onset and after 5 or 20 seconds of VF but with Vmax smaller (p less than 0.05) for verapamil than for predrug VF after 10 or 15 seconds of VF. In three dogs, Vmax was not significantly different during three successive episodes of VF when no drug was given between the episodes.(ABSTRACT TRUNCATED AT 400 WORDS)     

The sensitivity to cytosine arabinoside of the blast progenitors of acute myeloblastic leukemia

Two culture methods are available for the study of the blast cells of acute myeloblastic leukemia (AML). One is an assay for clonogenic precursors; it depends on their ability to form blast colonies in culture in the presence of methylcellulose and suitable growth factors. The other assesses the growth of blast cells in suspension culture, where growth is measured by increasing numbers of clonogenic cells. We have compared the two methods as assays for the cytotoxic effects of the chemotherapeutic drug cytosine arabinoside (Ara-C). Marked patient- to-patient variation was found using either method; however, the slopes of the dose-response curves were usually greater when cells were exposed to drug in suspension rather than in methylcellulose. Control experiments showed that the difference could not be explained by drug carry-over from the suspension cultures to the methylcellulose plates when clonogenic cells in the suspensions were assessed. Further, the survival curves for Adriamycin were very similar, regardless of which assay was used. No correlation was found between D10 Ara-C values measured in suspension or in methylcellulose. However, a significant association with outcome was found between D10 Ara-C in suspension and response to treatment with a regimen in which Ara-C was the only chemotherapeutic agent used. No such association was detected when the D10 values obtained with the clonogenic assay were compared with outcome for the same group of 15 patients. Finally, a feasibility experiment was performed in which blast cells were exposed to Ara-C repeatedly during exponential growth over 238 days. A dose-related inhibition of growth was observed; no evidence was seen of emerging drug-resistant cells. Nor did the morphology of the cells change as a result of drug exposure. We conclude that drug sensitivities of AML blast cells in culture are dependent on measurement methods, even when techniques affecting cell proliferation are compared. Measurements of drug sensitivity in culture may best be interpreted when the bases of the assay systems are understood.