全胚胎体外培养方法筛查致畸原的应用

全胚胎体外培养技术是将孕第９．５天的大鼠胚胎从子宫移至体外培养，培养期间在培养基中加入不同的化合物，由于排除了母体和胎盘因素，可以观察到这些化合物对胚胎生长发育的直接影响。应用该技术研究了青霉素、敌枯双、放线菌素Ｄ和高浓度葡萄糖四种化合物对胚胎生长发育的直接影响，结果发现在体外培养时也可导致胚胎死亡、畸形和胚胎生长发育迟缓，所导致的畸形与在整体动物实验结果相同。同时发现化合物在导致胚胎死亡、畸形和生长发育迟缓方面具有明显的剂量－效应关系。通过比较这种化合物导致胚胎死亡、畸形和发育迟缓的剂量－效应曲线的关系，推测其导致胚胎畸形的可能性以及畸形胚胎存活的可能性，从而推测化合物在实际中真正致畸的可能性。     

心血管疾病基因治疗的基础研究Ⅵ．一种新的体内基因转移方法

将医用缝合线浸泡在质粒ＤＮＡ溶液中，然后缝合在大鼠股四头肌上，可以观察到外源基因在肌肉组织中高效、稳定地表达，其表达量高于磷酸钙共沉淀和ＤＮＡ沉淀块埋植法，较肌肉直接注射法表达量高１０倍左右。     

Analysis of magnetization transfer effects on T1-weighted spin-echo scans using a simple tissue phantom simulating gadolinium-enhanced brain lesions

The purpose of this study was to analyze the effect of several magnetization transfer (MT) pulse and T1-weighted spin-echo (SE) sequence parameters on lesion-to-background contrast, using a simple tissue phantom emulating the T1 relaxation and MT properties of gadolinium-enhanced brain lesions. Eggbeaters (Nabisco Inc., East Hanover, NJ) liquid egg product was doped with gadolinium in six concentrations from .0 to 1.0 mmol and cooked. The gadolinium-doped egg phantom and normal volunteer brains were studied using an SE sequence with TE = 20 msec and high power, pulsed, off-resonance MT saturation. The effects of MT pulse frequency offset (1,000–6,000 Hz), sequence repetition time (TR = 500–1,000 msec, with MT power held constant), and slice-select flip angle (60–120 degrees) on the magnetization transfer ratio (MTR) and the simulated lesion-to-background contrast were determined at the different “Intralesion” gadolinium concentrations. The MTR and lesion-to-background contrast of all materials were greatest at narrow MT pulse frequency offsets. There was an inverse relationship between gadolinium concentration and MTR and a positive correlation between the gadolinium concentration and lesion-to-background (L/B) contrast, a weak negative correlation between slice-select flip angle and L/B, and a negative correlation between TR and L/B. The relaxation properties and MT behavior of the egg phantom are close to that expected for enhancing brain lesions, allowing a rigorous analysis of several variables affecting lesion-to-background contrast for high MT power, T1-weighted SE sequences.     

Gap junction proteins exhibit early and specific expression during intramembranous bone formation in the developing chick mandible

The spatial and temporal expression of three closely related members of the connexin family of gap junction proteins (connexin42, Cx42; connexin43, Cx43; and connexin45, Cx45) was evaluated during bone formation in the mandibular process of the chick embryo. Mandibles of chick embryos from Hamburger and Hamilton stage 25 (approximately 5 days) through 19 days of development were dissected, serially sectioned and processed for immunocytochemical localization, employing site-specific anti-connexin antibodies. Our data revealed that (1) Cx43 was present throughout mandibular bone formation; (2) although it appeared to be associated with all bone cell types, Cx43 was concentrated in mesenchymal cells during the earliest stages in the osteogenic lineage; (3) most importantly, the localization of Cx43 at sites of bone formation appeared to precede the overt expression of the osteogenic phenotype; (4) by contrast, Cx45 was more restricted, spatially and temporally, in its distribution; (5) Cx42 expression was not detected in osteogenic tissue during mandibular bone formation. From all of the data obtained, Cx45 appeared to be associated with stages of bone formation characterized by the elaboration of matrix and the progressive expression of the differentiated osteogenic phenotype. Cx43 appeared to be associated with condensation of mesenchyme and the earliest stages of osteogenesis. Because of these associations, we propose that connexin expression may be necessary for the initiation of bone formation and the full expression of the osteogenic phenotype.     

Ventrally emigrating neural tube cells migrate into the developing vestibulocochlear nerve and otic vesicle

Virtually all cell types in the inner ear develop from the cells of the otic vesicle. The otic vesicle is formed by the invagination of non-neural ectodermal cells known as the otic placode. We investigated whether a recently described cell population, originating from the ventral part of the hindbrain neural tube known as the ventrally emigrating neural tube (VENT) cells, also contributes cells to the otic vesicle. The ventral hindbrain neural tube cells were labeled with the fluorescent vital dye DiI or replication-deficient retroviruses containing the LacZ gene in chick embryos on embryonic day 2, after the emigration of neural crest from this region. One day later, the labeled cells were detected only in the hindbrain neural tube. Shortly thereafter, the labeled cells began to appear in the eighth (vestibulocochlear) cranial nerve and otic vesicle. From embryonic day 3.5-5, the labeled cells were detected in the major derivatives of the otic vesicle, i.e. the endolymphatic duct, semicircular canals, utricle, saccule, cochlea, and vestibulocochlear ganglion. That the emigrated cells originated from the ventral part of the hindbrain neural tube was confirmed by focal application of DiI impregnated filter paper and with quail chimeras. It is concluded that, in addition to the otic placode cells, the otic vesicle also contains the ventrally emigrating neural tube cells, and that both cell populations contribute to the structures and cell types in the inner ear. It is well known that inductive signals from the hindbrain are required for the morphogenesis of the inner ear. The migration of the hindbrain neural tube cells into the otic vesicle raises the possibility that the inductive effect of the hindbrain might be mediated, at least in part, by the ventrally emigrating neural tube cells and that, therefore, a mechanism exists that involves cells rather than diffusible molecules only.     

关节镜下股骨单隧道与双隧道重建后十字韧带的疗效分析

目的分析比较关节镜下单束单隧道与双束股骨双隧道重建后十字韧带(PCL)术后的临床效果。方法1999年1月～2001年12月,采用单束前外束重建法重建PCL 18例,男14例,女4例;年龄18～50岁,平均35.5岁;右膝12例,左膝6例。移植物为骨-髌腱(中1/3)-骨的11例,半腱肌腱和股薄肌腱的7例。于PCL股骨附着点解剖中心的稍前方钻取股骨隧道,屈膝70°,拉紧并固定移植物。2000年1月～2002年12月,采用双束股骨双隧道法重建PCL12例,男10例,女2例;年龄21～47岁,平均33岁;右膝9例,左膝3例。移植物为半腱肌腱和股薄肌腱的7例,一端带髌骨块的股四头肌肌腱的5例。将肌腱编织分为两束。于股骨侧钻取双隧道。两束分别于屈膝70°和0°时拉紧并固定。结果采用前外束重建法的18例患者平均随访23个月,采用双束股骨双隧道重建法的12例患者平均随访17个月。前外束重建组与双束股骨双隧道重建组随访时的Lysholm评分分别为(92.4±3.7)分和(94.3±3.4)分,两组间差异无显著性(P>0.05)。屈膝0°和30°时,前外束重建组的胫骨后移距离是(5.9±0.4)mm和(6.2±0.5)mm,双束股骨双隧道重建组是(3.5±0.3)mm和(4.0±0.4)mm,两组间差异有显著性(P<0.05);屈膝60°和90°时,两组胫骨后移距离差异无显著性(P>0.05)。结论双束股骨双隧道重建PCL的方法优于前外     

Effects of opiates on the growth of neuron-enriched cultures from chick embryonic brain

Neuron-enriched cultures derived from 6-day-old chick embryo cerebral hemispheres were treated with morphine or methadone, 10(-5) M or 10(-6) M, on days 4-6 or 6-8 in culture and were evaluated morphologically and biochemically at day 9 using phase contrast microscopy and choline acetyltransferase activity (ChAT) as a cholinergic marker. The treatment of the cultures with morphine markedly affected their growth pattern; specifically, we observed an increased number of flat cells presumptively glia, and aggregates sided by flat cells and devoid of thick bundles of neuritic processes that normally characterize neuron-enriched cultures. These morphologic changes were reflected in a drastic decrease of ChAT activity in cultures treated from day 4 to day 6 but not from 6 to 8. In contrast to morphine, exposure to 10(-6) M methadone from day 4 to day 6 resulted in reduced ChAT activity but the growth pattern of the cultures remained morphologically intact. We suggest that morphine exerts a general neurotoxic effect whereas methadone may affect some specific cholinergic function.     

Anaesthesia monitoring: the human factors component of technology transfer

Resistance to change in monitoring practices from within the anaesthesiology community is a formidable obstacle, and coercive and exhortatory solutions are likely to be unsuccessful in some situations. An analysis of publications about technology transfer and professional obsolescence, and application of this data to the practice of anaesthesia, reveals various stresses that technology transfer from research areas to the workplace may induce in vulnerable anaesthesiologists and account for their attitudes. It is suggested that the invaluable pronouncements of high profile anaesthesiologist groups must be supplemented by supportive behaviour by physicians and administrators at an institutional level. The human factors issues to be addressed include: (i) Monitored data acquisition skills. (ii) Possibility of acting on monitored data. (iii) Assistance for personal insight into attitudinal difficulties that may be encountered. (iv) Data supporting the value of the device. (v) Ergonomically effective integration of the monitor into the work station.Alternatively the perceptions of potential users may accurately reflect changes in their status in the new work situation created by monitors, and decision making aids that may or may not be derived from them. Thus, plans to present job satisfaction in related clinical areas or to associate the proposed new system with evaluation of its effect on patient outcome will be necessary. In this way the clinician becomes involved in clinical research, a quality of personal and quality care development.     

人胚呼吸道上皮细胞非时序DNA合成

为研究和比较化学致癌物对人呼吸道上皮细胞和纤维母细胞的损伤及损伤后DNA修复合成的差异,作者用直接致癌物4-硝基喹啉-1-氧化物(4-NQO)和间接致癌物3,4-苯并芘(BaP)处理人胚鼻咽、气管上皮细胞和纤维母细胞,用放射自显影术测定这3种细胞的非时序脱氧核糖核酸合成(UDS)。用4-NQO处理后,这3种细胞的UDS均呈明显的剂量依赖(dose dePendency)关系,但气管和鼻咽上皮细胞UDS平均分别是纤维母细胞的3.0和2.4倍。用BaP处理后,气管和鼻咽上皮细胞UDS呈现明显的剂量依赖关系,而纤维母细胞未见这种关系。气管和鼻咽上皮细胞的UDS平均分别是纤维母细胞的8.6和3.0倍。     

Transfer of clonidine and dexmedetomidine across the isolated perfused human placenta

Background: The placental transfer of the a₂ receptor agonist clonidine, earlier used as an adjuvant in obstetric epidural analgesia, was compared with the transfer of the newer and more %-selective agonist dexmedetomidine.
Methods: Term placentas were obtained immediately after delivery with maternal consent and a 2-hour recycling perfusion of a single placental cotyledon was performed. Disappearance from the maternal circulation, accumulation in placental tissue and appearance in the fetal circulation of clonidine or dexmedetomidine with the reference compound antipyrine were followed in 4 experiments for both drugs.
Results: At 2 hours the percent dexmedetomidine found in the fetal circulation was 12.5 (SD 5.1)%, while 48.1 (SD 20.3)% was found in the perfused placental cotyledon. A higher mean clonidine than dexmedetomidine concentration was achieved in the fetal circulation (1.90 vs. 0.56 nmol/l, P <0.05). At 2 hours the percent clonidine found in the fetal circulation was 22.1 (SD 2.4)% ( P <0.05), while 11.3 (SD 3.3)% ( P <0.05) was re tained in the perfused placental cotyledon. The transfer indexes, describing maternal-to-fetal transfer of dexmedetomidine and clonidine normalized with the transfer of antipyrine, were 0.88 (SD 0.07) and 1.04 (SD 0.08) respectively ( P <0.05).
Conclusions: Dexmedetomidine disappeared faster than clonidine from the maternal circulation, while even less dexmedetomidine was transported into the fetal circulation. This was due to its greater placental tissue retention, the basis for which probably is the higher lipophilicity of dexmedetomidine.