西宁地区健康小儿窦房结功能测定的初步探讨

应用食道心房调博缩测定健康小儿窦房结功能，以了解西宁地区正常数值与平原地区进行对比。选择２７例健康小儿，将Ｆ６二级电极导管从鼻腔送入，定位地食道心电图最大正负双相Ｐ波处，采用苏州东方电子仪器厂生产的ＤＦ－３Ａ型心脏电生理治疗仪进行检查，从而作出诊断。     

Modification of DiFrancesco-Noble equations to simulate the effects of vagal stimulation onin vivo mammalian sinoatrial node electrical activity

We present a new mathematical model for vagal control of rabbit sinoatrial (SA) node electrical activity based on the DiFrancesco-Noble equations. The original equations were found to be unstable, resulting in progressive cycle by cycle depletion or accumulation of ions in intra- and extracellular compartments. This problem was overcome by modifying the maximum Na−K pump current and the time constant for uptake of intracellular calcium. We also included a formulation for the acetylcholine (ACh)-activated potassium current which was consistent with experimental data. This formulation was based on kinetics first proposed by Osterrieder and later modified by Yanagihara. The resulting model exhibits cycle-cycle ionic stability, and includes an ACh-activated potassium current which accurately reproduces experimentally observed effects of vagal stimulation on both the membrane potential and its timederivative. Simulations were performed for both brief-burst and prolonged vagal stimulation using simplified square wave profiles for the concentration of ACh in the synaptic cleft space. This protocol permits the isolation of cardiac period dynamics caused by changes in membrane potential and intra- and extracellular ionic concentrations from those caused by other mechanisms including the dynamics of ACh release, diffusion, hydrolysis and washout. Simulation results for the effects of brief-burst single cycle stimulation on the cardiac period agree closely with experimental data reported in the literature, accurately reproducing changes in membrane potential and the phasic dependency of the response to the position of vagal stimulus bursts within the cycle. Simulation of the effects of prolonged vagal stimulation accurately reproduced the steady-state characteristics of heart period response, but did not yield the complex multimodal dynamics of the recovery phase, or the pronounced post vagal tachycardia observed experimentally at the termination of the stimulus. Our results show that the major chronotropic effects of vagal stimulation on the SA cell membrane can be explained in terms of the ACh-activated potassium current. The effects of this membrane current however are generally fast acting and cannot contribute to any long lasting dynamics of the cardiac period response. The modified DiFrancesco-Noble model presented in this article provides a valuable theoretical tool for further analysis of the dynamics of vagal control of the cardiac pacemaker.     

Metastatic Behavior and Tumorigenicity of a Human Melanoma Cell Line (MM-RU) after Injection into Nude Mice

The ability of the human amelanotic melanoma cell line MM-RU to produce experimental metastases and to grow tumors at subcutaneous inoculation sites in 4-week-old nude mice was examined. After i.v. inoculation of 10⁶ cells, all injected mice (n=21) developed consistent numbers of metastatic pulmonary colonies within 32 days. The coefficients of variation for the number of colonies were between 17%–23% in three independent experiments. Survival time after i.v. inoculation was 63 ± 7 days (mean ± SD) (n=20). Within 20 days, subcutaneous inoculation of 5 × 10⁶ cells resulted in tumor growths of 13 ± 3 mm (mean ± SD) at the inoculation sites in all nude mice (n=12). The MM-RU cell line seems to be a simple, fast vehicle for testing the effect of melanoma growth modulators on experimental pulmonary metastases as well as on subcutaneously growing melanoma.     

Intraoperative frozen section examination of axillary sentinel lymph nodes in breast cancer

The study presents the results from intraoperative frozen section assessment of axillary sentinel lymph nodes (SLNs) in breast cancer. Routine histological frozen sections from one level were used, two sections stained with haematoxylin and eosin. Immunohistochemistry for cytokeratins was applied to the permanent SLN paraffin sections only. Axillary dissection was performed on all SLN-positive cases regardless of the size of the metastatic deposits. With a detection rate of 83%, 272 patients entered the study over a period of 46 months. A total of 61 cases were SLN positive by frozen section analysis. The paraffin sections gave an additional 23 SLN-positive cases. The false-negative rate for frozen sections was then 27% (23/84). Micrometastases were found in 28 of 84 cases, and macrometastases in 56. The false-negative rate of frozen sections for micrometastases was 71% (20/28), and for macrometastases 5% (3/56). A total of 73% (61/84) of the patients underwent axillary surgery as a one-step procedure.     

Non-redundancy of cytidine deaminases in class switch recombination

Class switch recombination (CSR), somatic hypermutation, and gene conversion are immunoglobulin diversification mechanisms that are strictly dependent on the activity of the activation-induced cytidine deaminase (AID). The precise role and substrate(s) of AID in these processes remain to be well defined. The closest homologue of AID is APOBEC-1, a bona fide mRNA-editing enzyme, which shares with AID the ability to deaminate cytidines within single-stranded DNA in vitro and in prokaryotic cells. To determine whether APOBEC-1 can therefore substitute for AID in activated B cells, we expressed human AID, a catalytic mutant thereof, and rat APOBEC-1 in AID-deficient murine B cells. Whereas AID rescued CSR, neither the inactive mutant nor APOBEC-1 could complement AID deficiency. This indicates that cytidine deaminase activity is necessary but not sufficient to initiate CSR, and suggests that AID is specifically targeted to its cognate substrate, the immunoglobulin genes or a distinct mRNA, by an as-yet-unknown mechanism.     

结核性淋巴结炎的“结节病”样变型

对１２例经病理学专家会诊、从病变上认定的淋巴结“结节病”石蜡包埋组织，应用结核杆菌ＤＮＡ特异性序列片段的聚合酶链反应（Ｍ．ＴＢ－ＰＣＲ）技术、ＢＣＧ免疫组化（ＢＣＧ－ＩＨＣ）技术和抗酸染色（ＡＦ）进行了分支杆菌／结核杆菌检测。在这１２例考虑为“结节病”的病例中：有１例呈ＢＣＧ－ＩＨＣ和Ｍ。ＴＢ－ＰＣＲ两项阳性；另１例呈ＡＦ、ＢＣＧ－ＩＨＣ和Ｍ．ＴＢ－ＰＣＲ三项阳性。研究结果提示：（１）某些结核性淋巴结炎可呈结节病样病变；（２）淋巴结结节病很可能与分支杆菌／结核杆菌感染有关。     

The proliferative capacities of popliteal lymph node lymphocytes and of their functionally distinct T-cell subpopulations from young-adult and old mice

Young adult and old mice were immunized by footpad injection of dinitrophenyl-conjugated bovine gamma-globulin (DNP-BGG) in complete Freund's adjuvant. A comparison of lymph node weight and total number of nucleated cells per lymph node as a function of time after antigen injection demonstrated a significantly greater absolute increase in lymph node weight and peak number of nucleated cells per lymph node in young-adult than in old animals. However, as judged by this increase in total nucleated cells, other than being delayed in old mice, the magnitude of these in situ proliferative responses appeared comparable for young-adult and old mice. That is, the antigen-stimulated to non-stimulated cell ratio did not differ significantly between young-adult and old animals. This was because lymph nodes from old animals prior to antigen injection always weighed less and had fewer numbers of nucleated cells compared with young-adult animals. Therefore, the in vitro cellular proliferative response of three T-cell-enriched lymphocyte subpopulations from young-adult and old mice was further characterized. This was done by measuring [3H]thymidine incorporation following antigen- (DNP-BGG)- or mitogen-[phytohemagglutinin (PHA) or Concanavalin A (Con A)]-induced proliferation and assessing their quantitative and/or qualitative requirements for macrophages. In contrast to the markedly reduced proliferation of the two T-cell subpopulations from popliteal lymph nodes which respond to PHA and Con A in old animals primed 21-days earlier with DNP-BGG, antigen-induced in vitro cellular proliferation of the small T-cell subset in old mice specifically responsive to the immunizing antigen DNP-BGG always responded as well as, if not better than, cells from young-adult mice.     

Plasticity of innervation of the medulla of axillary lymph nodes in the rat after antigenic stimulation

The purpose of this investigation was to test the hypothesis that activation of the immune system in rats will lead to changes in the density of innervation in lymph nodes. In order to reduce the variability between animals, the rats were reared under sterile conditions and immunostimulation was effected by subcutaneous application of bovine albumin in a region draining to the axillary lymph nodes of both sides. Control animals received an equivalent application of sterile physiological saline. The animals were sacrificed 10 days and 27 days and 4 months after immunostimulation. The nerves in the axillary lymph nodes were quantified by light microscopy in silver impregnated sections and at the ultrastructural level on ultrathin sections. The survival times were chosen so that the first group was in the ascending phase of antibody production, the second group at the peak, and the third group in the declining phase. Both at the light and ultrastructural levels, there were statistically significant differences in the density of innervation of medulla between the groups, with a particularly pronounced increase in the group 4 months after immunostimulation. At the ultrastructural level, there was also an increase in the density of incompletely ensheathed axonal profiles in the parenchyma of the medulla, while the nerves associated with blood vessels were not increased. We conclude that immunostimulation leads to morphological changes in the innervation of the medulla of axillary lymph nodes, that are consistent with the concept of functional activation of the autonomic nervous system through the immune system. © 1994 Wiley-Liss, Inc.     

大鼠肠系膜淋巴结高内皮微静脉与淋巴迷路之间的网状纤维支架的研究

目的 研究大鼠肠系膜淋巴结内高内皮微静脉与淋巴迷路之间淋巴细胞归巢的通路.方法 用镀银染色光镜观察法和冻裂割断扫描电镜观察法观察健康、成熟Wistar大鼠肠系膜淋巴结的基质网状结构.结果 位于高内皮微静脉和淋巴迷路周围有网状纤维支架,在二者相临近部位有密集交织的网状纤维网.结论 淋巴结内高内皮微静脉和淋巴迷路之间密集交织的网状纤维网,为细胞的居留和迁移提供结构支持和适宜的微环境,可能是淋巴细胞归巢的重要通路.