Unitary step of gliding machinery in Mycoplasma mobile

Among the bacteria that glide on substrate surfaces, Mycoplasma mobile is one of the fastest, exhibiting smooth movement with a speed of 2.0–4.5 μm⋅s⁻¹ with a cycle of attachment to and detachment from sialylated oligosaccharides. To study the gliding mechanism at the molecular level, we applied an assay with a fluorescently labeled and membrane-permeabilized ghost model, and investigated the motility by high precision colocalization microscopy. Under conditions designed to reduce the number of motor interactions on a randomly oriented substrate, ghosts took unitary 70-nm steps in the direction of gliding. Although it remains possible that the stepping behavior is produced by multiple interactions, our data suggest that these steps are produced by a unitary gliding machine that need not move between sites arranged on a cytoskeletal lattice.The fastest of the Mycoplasma species is Mycoplasma mobile (M. mobile); they glide with a speed of 2.0–4.5 μm⋅s⁻¹ (1, 2). Under an optimal-growth condition, cultivated single M. mobile cells are flask-shaped (Fig. 1A) and glide smoothly across a substrate covered with surface-immobilized sialylated oligosaccharides (3) in the direction of protrusion at a constant speed (Movie S1). Genomic sequencing and analysis have revealed that the mechanism must differ from other forms of motor protein systems and bacterial motility, because M. mobile lacks genes encoding conventional motor proteins in eukaryotes, such as myosin, kinesin, and dynein, in addition to lacking other motility structures in bacteria, such as flagella and pili (4). So far, three proteins have been identified as a part of the gliding machinery (Fig. 1B, Bottom): Gli123 (5), Gli521 (6), and Gli349 (7). The machinery units localize around the cell neck, and their number has been estimated to be ∼450 (2, 5, 8). Gli349 extends out from the cell membrane and shows a rod structure, ∼100 nm in total, with two flexible hinges when isolated (9). Notably, the machinery is driven by hydrolysis of ATP to ADP and inorganic phosphate, caused by an unknown ATPase (10). Because of the large size and characteristic structure of Gli349, and a series of studies with mutants and inhibitory antibodies (2, 11), it has been hypothesized that Gli349 works as a “leg” by binding to and releasing from a substrate covered with randomly arranged sialylated oligosaccharides (2) consuming the chemical energy of ATP. In addition, the pivoting movement of an elongated cell suggests that there are units working not simultaneously but rather independently to propel the cell forward (12). To test this hypothesis and identify conformational changes of a key part of the gliding machinery, we here designed an assay to detect the movement of M. mobile by high precision colocalization microscopy. In the presence of an excess number of binding targets in the solution, which decreased the number of active legs, stepwise displacement was shown for the first time, to our knowledge, to occur in gliding bacteria.Open in a separate windowFig. 1.Nanometer-scale tracking of Mycoplasma gliding. (A) A dark-field image of M. mobile. The image was captured with center-stop optics to maintain the high numerical aperture of the objective, which enabled a high spatial resolution (35). (Scale bar: 1 μm.) (B, Upper) Illustration of the fluorescent ghost. The gliding machinery was distributed around the neck portion, but only the active machinery bound to the glass is shown for simplicity. (Bottom) A construction model of the gliding machinery comprising three proteins: Gli123, Gli521, and Gli349. See the review by Miyata (2) for more detail. (C) A fluorescent image of the labeled ghost was acquired with a time resolution of 2 ms. (Scale bar: 1 μm; pixel size: 240 nm.) (D) The intensity profile of C. The XY area is 5 × 5 μm. (E) Gaussian fitting to D. Nanometer-scale tracking is achieved by positioning the peak of the 2D Gaussian function fitting to the intensity profile of the ghost. (F, Left) The speed of gliding ghosts at different [ATP]s in the solution (n = 129). The cyan curve shows a fit with Michaelis–Menten kinetics; Vmaxspeed and K_m are 2.6 µm⋅s⁻¹ and 61 µM, respectively. The dotted cyan curve shows a fit with the kinetics including the Hill coefficient; Vmaxspeed, [ATP₅₀] and n are 2.2 µm⋅s⁻¹, 43 µM, and 2.4, respectively. (Right) The speed of living cells with no ATP in the solution (2.1 ± 0.1 µm⋅s⁻¹; n = 22). (G) Effect of SL on the gliding velocity of the ghost at saturated [ATP]s, 0.3–1.0 mM (n = 50).     

Single whole‐leg compression ultrasound for exclusion of deep vein thrombosis in symptomatic ambulatory patients: a prospective observational cohort study

International guidance has recently recommended serial proximal compression ultrasound (CUS) as first line imaging for suspected deep vein thrombosis (DVT). Single whole‐leg CUS is a routine alternative diagnostic strategy that can reduce repeated attendances and identify alternative pathology. We conducted a prospective observational cohort study. Consecutive ambulatory, adult patients with suspected DVT and negative or inconclusive whole‐leg CUS had anticoagulation withheld and were followed for 3 months. The primary outcome was a predefined clinically relevant adverse event rate. Secondary outcomes included technical failure, alternative diagnoses and all cause mortality. 212 patients agreed to participate and completed follow up. One patient was subsequently diagnosed with an isolated distal DVT. The adverse event rate was thus 1/212, 0·47% (95% confidence interval [CI] 0·08–2·62). Technical imaging failure occurred in 11·3% of cases (95% CI 7·7–16·3). Several potential predictors of an inconclusive result were identified on multivariate analysis. 150 (70·8%) patients were provided with a documented alternative diagnosis. Patients who have anticoagulation withheld following a negative or inconclusive whole‐leg CUS for suspected DVT have a low rate of adverse events. Technical failure remains an issue: several factors were significantly associated with inconclusive results and may warrant an alternative diagnostic approach.     

结肠孤立性溃疡的诊断及治疗

结肠孤立性溃疡是一种可发生在不同年龄阶段的少见结肠疾病。结肠镜及组织学检查是诊断该病的重要手段。本文就结肠孤立性溃疡的相关问题作一综述。     

腰腿痛患者报告结局量表的应用分析

目的:检验腰腿痛患者报告结局量表的信度、效度及反应度.方法:2010年8月至2012年1月,纳入住院腰椎间盘突出症及腰椎管狭窄症患者患者200例,男93例,女107例;年龄22～65岁,平均50.3岁;腰椎间盘突出症144例,腰椎管狭窄症56例 应用腰腿痛患者报告结局量表对患者进行测评,并对量表进行信度、效度、反应度分析.结果:39例病情无变化患者两次评分无显著性差异(P＞0.05),且有显著相关性(r＞0.9);该量表同Oswestry功能障碍指数问卷(ODI)对患者评分结果具有显著相关性(r＞0.8);该量表总体克朗巴赫α系数为0.931,总体Guttman折半系数为0.912;该量表KMO统计量为0.919,Bartlett球形检验卡方值l 882.975(P＜0.01),因子分析方法提取特征根值＞1的3个公因子,累计贡献率为64.364％;43例病情有好转患者两次评分结果分别为34.80±9.00和28.77±8.73,两者差异有统计学意义(P＜0.01).结论:腰腿痛患者报告结局量表有较好的信度、效度及反应度,可作为腰腿痛患者临床疗效的评价工具.     

单侧发育性髋关节脱位下肢长度的放射学观察

[目的]观察骨骼发育成熟的单侧发育性髋关节完全脱位(unilateral developmental dislocation of the hip,UDDH)的患者脱位侧下肢长度与膝关节畸形的变化特点.[方法]通过骨盆正位X线片及站立位双下肢全长X线片对骨骼发育成熟的UDDH(HartofilakidisⅡ或Ⅲ型)进行脱位侧股骨头上移距离、双侧下肢骨骼长度、小粗隆至内踝长度的测量,同时测量双侧膝关节外翻角.[结果] 28位UDDH患者符合研究标准.平均年龄29.80岁(13.4 ～66.2岁).脱位侧股骨头均上移,上移距离为4.6～60.9 mm,平均30.9 mm.脱位侧下肢骨骼长度延长者20例,占71.43％;最长延长距离为25 mm,平均延长9.4mm;双侧对比有显著性差异,P=0.022.小粗隆至内踝尖的距离延长者24例,占85.71％;最长延长距离为29.3mm,平均延长12.1 mm;双侧对比有显著性差异,P=0.000.脱位侧下肢骨骼长度延长5 mm以上者12例,占42.86％.脱位侧大于3°的膝外翻畸形12例,膝内翻1例;而非脱位侧大于3°的膝内翻畸形15例,膝外翻畸形1例;双侧对比有显著性差异,P =0.000.[结论]本研究通过骨盆正位及双下肢全长正位X线片显示UDDH患者脱位侧股骨头均明显上移;脱位侧骨骼长度较非脱位侧延长的比例高达70％,若以小粗隆为参考标志,脱位侧延长比例高达85.71％.脱位侧出现膝外翻畸形的发生率较高,而非脱位侧膝内翻的发生率高.     

主穿支皮神经营养血管皮瓣一期修复小腿及足踝部高能损伤创面

目的 探讨主穿支供血型小腿皮神经营养血管皮瓣一期修复小腿及足踝部创面的方法及效果.方法 回顾性分析2003年7月至2011年2月,对收治的39例高能损伤导致的小腿及足踝部损伤,单独或组合选择腓动脉主穿支供血游离或穿支蒂腓肠神经营养血管皮瓣、外踝上穿支蒂腓浅神经营养血管皮瓣、胫后动脉主穿支供血游离或穿支蒂隐神经营养血管皮瓣进行一期修复.结果 39例44处创面,采用腓动脉主穿支供血腓肠神经营养血管皮瓣32块(穿支蒂27块、游离5块),胫后动脉主穿支供血隐神经营养血管皮瓣6块(穿支蒂5块、游离1块),外踝上穿支蒂腓浅神经营养血管皮瓣6块,最大切取面积22 cm×10 cm.术后皮瓣均全部成活,平均住院23 d(12～36 d).术后随访6～15个月,皮瓣质地优良,外形与足踝功能恢复满意,吻合神经者两点辨距觉2.5～5 cm,未吻合神经者术后1年以上均存在保护性感觉.结论 上述3种主穿支皮神经营养血管皮瓣血供确切,合理个体化选择应用可修复不同类型小腿及足踝部创面;一期修复解剖清晰、血管条件好、手术设计灵活,可减少感染机会及肉芽瘢痕,利于功能恢复并缩短治疗周期.     

Leg Edema Due to a Mass in the Pelvis After a Large-Diameter Metal-On-Metal Total Hip Arthroplasty

We report the case of a patient with leg edema after large-diameter metal-on-metal total hip arthroplasty. At 1 year and 2 months after primary left large-diameter metal-on-metal total hip arthroplasty, the patient complained of left leg edema. At first, we suspected deep venous thrombosis. However, deep venous thrombosis was not detected by venous ultrasonographic examination. Computed tomography imaging revealed a mass in front of the iliac fossa. The mass compressed the left iliac artery and vein. We therefore believed that this lesion was the cause of the leg edema and performed resection of the mass. The resected mass consisted of necrotic tissue infiltrating inflammation cells, so it was diagnosed as pseudotumor. Unilateral leg edema disappeared gradually after the resection.     

Chronic Leg Ulceration Associated with Polycythemia Vera Responding to Ruxolitinib (Jakafi®)

We present the case of a 63-year-old white male with bilateral chronic leg ulcers due to polycythemia vera and hydroxyurea therapy who demonstrated dramatic healing of his wounds in response to ruxolitinib (Jakafi^®, Novartis), a novel Janus kinase-1 and -2 inhibitor. This patient's wound had previously been refractory to multiple surgical interventions and immunosuppression. After the initiation of ruxolitinib, the patient underwent successful split-thickness skin grafting, with resultant healing of his wounds. He was stable without prednisone and other immunosuppressant therapy and had healed at 6 months. Ruxolitinib therapy could represent a novel option for patients who develop persistent inflammatory wounds in the setting of polycythemia vera and hydroxyurea therapy.     

胸脐皮瓣在小腿软组织缺损中的应用和受区血管位置临床分型及意义

目的讨论小腿大面积皮肤缺损时,根据小腿损伤动脉不同应用胸脐皮瓣覆盖创面的设计及临床效果。方法2007年9月-2011年1月、根据小腿大面积皮肤缺损时,损伤胫前、胫后动脉不同及是否应用远端蒂、近端蒂或对侧小腿的胫后动脉,分别采用胸脐皮瓣修复7例,皮瓣面积最大20cm×11cm．最小10cm×6cm。结果7例皮瓣全部成活,创面一期愈合,术后随访5～24个月,皮瓣颜色质地好,外形及功能满意。结论将小腿皮肤缺损处胫前及胫后动脉损伤情况分析后给予分型,然后再分析应用远端蒂、近端蒂还是对侧小腿的胫后动脉来决定胸脐皮瓣的设计。