股骨远端骨折锁定钢板断裂原因分析及处理

目的探讨股骨远端骨折锁定钢板内固定失效的原因及防治措施。方法对2007年5月~2012年6月共14例应用锁定钢板固定失败的股骨远端骨折患者的临床资料进行分析,其中男9例,女5例,年龄27~68岁,平均39.2岁,骨折内固定术后1~8月(平均5.6个月)锁定钢板断裂。钢板断裂者均采用钢板螺钉取出术,5例予交锁髓内钉内固定,9例再次锁定钢板固定,均同时取自体髂骨移植植骨治疗。结果二次术后14例均获得随访,术后随访9~24月,平均14月,13例获得骨性愈合,1例二次锁定钢板固定患者于二次术后8月再次发生钢板断裂,予行钢板螺丝钉取出、交锁髓内钉固定治疗,再次手术后6月获骨性愈合。膝关节功能按Kolment评分标准:优4例,良9例,差1例。断裂原因具有多样性,5例钢板选择过短,9例存在螺钉置入密度过大,8例内侧皮质粉碎、缺失,4例因过早负重,2例因锻炼时摔伤而导致内固定失败。结论锁定钢板内固定失效的原因通常与对锁定钢板的适应证掌握不全,骨折端过度剥离、复位不良或内侧皮质存在缺损及术后功能锻炼不当有关。因此,选择合适的内固定物,注重植骨,加强术后康复指导、避免过早负重可有效预防及治疗股骨远端骨折钢板内固定失败。     

Enhanced mitochondrial degradation of yeast cytochrome c with amphipathic structures

The dispensable N-terminus of iso-1-cytochrome c (iso-1) in the yeast Saccharomyces cerevisiae was replaced by 11 different amphipathic structures. Rapid degradation of the corresponding iso-1 occurred, with the degree of degradation increasing with the amphipathic moments; and this amphipathic-dependent degradation was designated ADD. ADD occurred with the holo-forms in the mitochondria but not as the apo-forms in the cytosol. The extreme mutant type degraded with a half-life of approximately 12 min, whereas the normal iso-1 was stable over hours. ADD was influenced by the ⁺/^– state and by numerous chromosomal genes. Most importantly, ADD appeared to be specifically suppressed to various extents by deletions of any of the YME1, AFG3, or RCA1 genes encoding membrane-associated mitochondrial proteases, probably because the amphipathic structures caused a stronger association with the mitochondrial inner membrane and its associated proteases. The use of ADD assisted in the differentiation of substrates of different mitochondrial degradation pathways.     

Hyperbaric oxygenation mitigates focal cerebral injury and reduces striatal dopamine release in a rat model of transient middle cerebral artery occlusion

The usefulness of the administration of hyperbaric oxygen (HBO) in the treatment of acute focal cerebral ischemia remains debatable. A significant association exists between focal cerebral injury and an excessive release of extracellular dopamine (DA). In vivo microdialysis was used in the present study to examine the effect of HBO on DA release in the striatum during ischemia and reperfusion in rats. The histological changes occurring were also evaluated. Focal cerebral ischemia was induced by occlusion of the middle cerebral artery (MCA) using a surgically placed intraluminal filament. Control rats (n=8) were subjected to 1 h of ischemia, whilst the study rats (n=8) were in addition treated with HBO (2.8 atmospheres of absolute pressure 100% O₂) during ischemia. Both groups were returned to breathing room air at normal pressure during reperfusion. Microdialysis samples were continuously collected at 15 min intervals at 2 μl·min^–1. The [mean (SE)] increase in release of striatal DA attained significance after 30 min of occlusion of MCA [170 (24)%], and continued to increase [268 (26)% at 45 min] reaching a peak level at 60 min [672 (59)%] before returning to the baseline level during the late reperfusion phase. There was no significant change in the level of DA in HBO treated rats during the period of ischemia. A significant reduction in edema and neuronal shrinkage were observed by histological examination in HBO treated rats when compared to the control rats. The results showed that HBO, when administered during ischemia, offered significant neuroprotection in our experimental model of transient focal cerebral ischemia in the rat. The mechanism seems to imply, at least in part, a reduced level of DA. Electronic Publication     

T cell stimulation in the absence of exogenous antigen: a T cell signal is induced by both MHC-dependent and -independent mechanisms

Mature T cells residing in peripheral lymphoid organs have frequent contact with antigen presenting cells (APC). Such contact may be required for T cell survival, but the degree to which signals in mature T cells are induced by TCR recognition of self peptide/MHC complexes is unclear. We have used induction of the early growth response gene 1 (Egr1) as an indicator of signal transduction in 3.L2 (I-Ek-restricted) T cells interacting with APC in the absence of exogenous antigen. The data show that Egr1 can be induced in 3.L2 T cells by TCR recognition of self peptides presented by I-Ek. However, a more transient induction of Egr1 can be induced in 3.L2 T cells interacting with dendritic cells derived from class II/beta2m double-deficient mice. Egr1 induction after T cell-APC contact was also observed in a freshly isolated polyclonal CD4 T cell population. The data suggest that self peptide/MHC recognition by the TCR induces a signal in T cells and that dendritic cells can also induce a more transient T cell signal by an MHC-independent mechanism.     

心理弹性(resilience)研究综述

弹性（resilience）日益为心理学界所关注，已经成为心理学的一个重要研究领域。文章追溯了弹性研究的渊源，介绍了众多研究者对于弹性的认识，回顾了弹性领域研究的进展情况，对以往的研究进行了评价，对以后的研究进行了展望。     

The role of pulmonary CO2 flow in the control of the phase i ventilatory response to exercise in humans

To gain an insight into the origin of the phase I ventilatory response to exercise (ph I) in humans, pulmonary ventilation WE) and end-tidal partial pressures of oxygen and carbon dioxide (P _ETO₂ and P _ETCO₂, respectively) were measured breath-by-breath in six male subjects during constant-intensity exercise on the cycle ergometer at 50, 100 and 150 W, with eupnoeic normocapnia (N) or hyperpnoeic hypocapnia (H) established prior to the exercise test. Cardiac output (Q₂) was also determined beat-by-beat by impedance cardiography on eight subjects during moderate exercise (50 W), and the C0₂ flow to the lungs (Q₂·C_vCO₂ where C_vCO₂ is concentration of CO₂ in mixed veneous blood) was estimated with a time resolution of one breathing cycle. In N, the initial abrupt increase of PE during ph I (V_E approximately 18 l · min^–1 above rest) was followed by a transient fall. When P _ETCO₂ started to increase (and P _ETO₂ decreased) V_E increased again (phase II ventilatory response, ph II). In H, during ph I V_E was similar to that of N. By contrast, during ph II V_E kept gradually decreasing and started to increase only when P _ETCO₂ had returned to approximately 40 mmHg (5.3 kPa). Thus, as a result of the prevailing initial conditions (N or H) a temporal shift of the time-course of V_E during ph II became apparent. No correlation was found between C0₂ flow to the lungs and V_E during ph I. These results are interpreted as suggesting that an increased C0₂ flow to the lungs does not constitute an important factor for the initial hyperventilatory response to exercise. They are rather compatible with a neural origin of ph I, and would support the neurohumoral theory of ventilatory control during exercise.     

冠状病毒的分子生物学研究进展

冠状病毒是所有RNA病毒中基因组最大的病毒，具有胃肠道、呼吸道或神经系统嗜性，常引起人普通感冒或动物胃肠道、呼吸系统疾病，而SARS-CoV则引起人的严重急性呼吸道综合征。研究冠状病毒分子生物学特征对阐明其病毒粒子的发生、感染和致病机制有重要意义。本文就冠状病毒的分子生物学特征包括冠状病毒基因组特征，编码蛋白的结构及功能等方面的研究进展作一综述。     

Ventral specification and perturbed boundary formation in the mouse midbrain in the absence of Hedgehog signaling.

Although Hedgehog (HH) signaling plays a critical role in patterning the ventral midbrain, its role in early midbrain specification is not known. We examined the midbrains of sonic hedgehog (Shh) and smoothened (Smo) mutant mice where HH signaling is respectively attenuated and eliminated. We show that some ventral (Evx1+) cell fates are specified in the Shh-/- mouse in a Ptc1- and Gli1-independent manner. HH-independent ventral midbrain induction was further confirmed by the presence of a Pax7-negative ventral midbrain territory in both Shh-/- and Smo-/- mice at and before embryonic day (E) 8.5. Midbrain signaling centers are severely disrupted in the Shh-/- mutant. Interestingly, dorsal markers are up-regulated (Wnt1, Gdf7, Pax7), down-regulated (Lfng), or otherwise altered (Zic1) in the Shh-/- midbrain. Together with the increased cell death seen specifically in Shh-/- dorsal midbrains (E8.5-E9), our results suggest specific regulation of dorsal patterning by SHH, rather than a simple deregulation due to its absence.     

低频超声透皮给药的研究进展与应用

低频超声可以增强包括大分子药物在内的许多药物的透皮传输,其主要机制是超声的空化作用,大多数人认为是通过改变角质层角化细胞排列结构来提高皮肤渗透能力的.低频超声透皮给药已被人们用于离体实验和动物活体实验,到目前为止,无论是小分子透皮传输还是大分子透皮传输都有很多成功的例子.但是真正通过低频超声透皮导入药物进行治疗的临床应用报道很少,需要更进一步大量的临床试验以确定其安全性与实用价值.一旦其安全性得以证实,合适的低频超声透皮仪研制成功,低频超声快速透皮必将成为一种安全、有效、可控、经济的新型给药方式.     

On the mechanism of olefin polymerization by titanocene/MAO catalysts: Relationships between metathesis and addition polymerization

Ethylene polymerizations and norbornene oligomerizations catalysed by Cp₂Ti¹³CH₃Cl/MAO (Cp: cyclopentadienyl; MAO: methylaluminoxane) mixtures have been carried out at different temperatures (from -20°C to 20°C), in order to test the validity of carbene mechanisms in α-olefin polymerizations. Depending on the temperature, different ratios of the cationic species [Cp₂Ti¹³CH₃]⁺[Cl · MAO]^? and precursors of the alkylidene Cp₂Ti = ¹³CH₂ exist. The in situ polymerization of ¹³C enriched ethylene was monitored by ¹³C NMR spectroscopy. Moreover, catalytic activity was determined and polyethylene samples were analyzed by ¹³C NMR and gel permeation chromatography (GPC). The following evidence has been provided against the carbene mechanism in the α-olefin polymerization with titanocene based catalysts: (a) in the in situ ethylene polymerization experiments the appearance of polyethylene signals is concurrent with the decrease of cationic [Cp₂Ti¹³CH₃]⁺[Cl · MAO]^? signals and is not related to the intensity of the alkylidene Cp₂Ti = ¹³CH₂ signals; (b) from the ¹³C NMR analysis of polyethylene chain-end groups the ¹³C enrichment of Cp₂Ti¹³CH₃Cl has only been found in the methyl chain-end group and not in the methylene of the propyl chain-end group, as should have been the case if the carbene mechanism had been valid; (c) from norbornene oligomerization (at 0°C) the addition product 2-¹³C enriched methyl-norbornane has been identified. Moreover, the identification of a ¹³C enriched methylidene-norbornane dimer at higher temperatures has revealed the possibility of norbornene addition to titanium carbenes through the formation of titanacyclobutane without the opening of the norbornene ring. However, this process requires higher energies with respect to the Cossee type insertion.