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).     

纤维分体桩高嵌体修复低牙合龈距后牙残冠的临床评价

目的:评价含有纤维分体桩的钴铬合金烤瓷高嵌体以及二氧化锆全瓷高嵌体修复低龈距后牙残冠的临床效果。方法:用含纤维分体桩的钴铬合金烤瓷高嵌体、二氧化锆全瓷高嵌体以及金合金分体桩高嵌体修复低龈距后牙残冠90个,修复后2周、6个月、24个月随访,对解剖形态、边缘适合性、边缘着色、表面质地、继发龋等临床修复效果进行评价。结果:3种分体桩高嵌体之间以及每种分体桩高嵌体于修复后2周、6个月、24个月之间在各评价项目上均无明显统计学差异(P≥0.05)。结论:应用含纤维分体桩的钴铬合金烤瓷高嵌体及二氧化锆全瓷高嵌体对低龈距后牙残冠进行修复,可获得与金合金分体桩高嵌体一样良好的临床修复效果;而且烤瓷和全瓷高嵌体更加美观,可适应不同层次的修复需求。     

Cryptorchidism and endocrine disrupting chemicals

Prospective clinical studies have suggested that the rate of congenital cryptorchidism has increased since the 1950s. It has been hypothesized that this may be related to environmental factors. Testicular descent occurs in two phases controlled by Leydig cell-derived hormones insulin-like peptide 3 (INSL3) and testosterone. Disorders in fetal androgen production/action or suppression of Insl3 are mechanisms causing cryptorchidism in rodents. In humans, prenatal exposure to potent estrogen diethylstilbestrol (DES) has been associated with increased risk of cryptorchidism. In addition, epidemiological studies have suggested that exposure to pesticides may also be associated with cryptorchidism. Some case-control studies analyzing environmental chemical levels in maternal breast milk samples have reported associations between cryptorchidism and chemical levels. Furthermore, it has been suggested that exposure levels of some chemicals may be associated with infant reproductive hormone levels.     

Electrochemical Assay of Heparin to Monitor Anticoagulation Action in Cardiovascular Patients

Complications in anticoagulation therapy and long term consequences of the post thrombotic syndromes requires a fast and powerful therapy such as heparin therapy (anticoagulation) to minimize the thrombotic effects in patients. Thus, a simple approach via electrochemical method: Differential pulse polarography (DPP) has been developed for heparin analysis as a powerful clinical tool to monitor anticoagulation action in-patient undergoing heparin therapy. The method has been standardized for determination of heparin activity over the existing methods and a very well defined characteristic reduction peak at −1.25 V in 2 M NaOH was observed for heparin. A linear relation was observed with a regression equation as y = 0.3117x + 0.8069, for 0.1 to 2.0 units/ml heparin. The developed DPP method was observed with excellent precision, accuracy and recovery in human blood plasma samples and in pharmacological formulations. The limit of detection (LOD) and limit of quantification (LOQ) noticed to be 2.04 and 6.8 units/ml respectively. The DPP results compared with pharmacological screening through average thrombin time (TT) and applied to monitor invitro anticoagulation action of heparin in healthy human subjects. Statistical analysis done to validate developed DPP method for heparin analysis and its probable clinical use to monitor anticoagulation action to treat patients suffering from various cerebrovascular disorders (CVD) by proper dosing of heparin.     

房间隔缺损封堵术后应用重组人脑钠尿肽的疗效观察

目的:探讨重组人脑钠尿肽(recombinant human brain natriuretic peptide,rhBNP)对房间隔缺损(ASD)并发肺动脉高压封堵术后的肺动脉高压的影响。方法:选择56例房间隔缺损并发中重度肺动脉高压患者封堵成功患者,将其随机分为术后静脉点滴rhBNP患者为处理组(30例),未应用的为对照组(26例),比较两组术前、术后48 h及术后6个月肺动脉压、6分钟步行试验距离(six minute walking distance,6MWD)、血浆内皮素(endothelin,ET)水平的变化。结果:在术后48 h和术后6个月,两组患者肺动脉压及ET水平术后明显降低(P<0.05);两组患者6MWD较术前显著增加(P<0.05);术后48 h和术后6个月处理组较对照组显著降低肺动脉压及ET水平(P<0.01),显著增加6MWD(P<0.01)。结论:封堵术后静脉点滴rhBNP可进一步降低肺动脉压及ET水平,增加6MWD。     

125Ⅰ粒子植入术后密切接触者辐射剂量的监测及防护

目的 探讨125Ⅰ粒子植入术后密切接触者受照射的有效剂量及其警戒时间、安全距离.方法 术后24h内,采用袖珍辐射仪监测30例患者距粒子植入部位垂直距离30、50、60、70、80、90、100、110、120、130、140、150 cm处(模拟密切接触者)受照剂量率,并根据公式计算各人群各距离受照有效剂量、警戒时间及安全距离.结果 与患者同床成人、同事、同住未成人及孕妇、同住成人的警戒时间分别为108、78、55、0d.相对应者安全距离及此距离的有效剂量分别为:60 cm和(3.22±1.97) mSv、140 cm和(0.516 ±0.225) mSv、120 cm和(0.612±0.306) mSv、100 cm和(0.938±0.509) mSv.结论 3.5个月内各人群与术后患者接触则需采取时间、距离等防护措施;3.5个月之后不必采用防护措施.     

The NORwegian study on DIstrict treatment of ST-Elevation Myocardial Infarction (NORDISTEMI)

Objectives. Thrombolysis is the treatment of choice for patients with ST-elevation myocardial infarction (STEMI) living in rural areas with long transfer delays to percutaneous coronary intervention (PCI). This trial compares two different strategies following thrombolysis: to transfer all patients for immediate coronary angiography and intervention, or to manage the patients more conservatively. Design. The NORwegian study on DIstrict treatment of STEMI (NORDISTEMI) is an open, prospective, randomized controlled trial in patients with STEMI of less than 6 hours of duration and more than 90 minutes expected time delay to PCI. A total of 266 patients will receive full-dose thrombolysis, preferably prehospitally, and then be randomized to either strategy. Our primary endpoint is the one year combined incidence of death, reinfarction, stroke or new myocardial ischaemia. The study is registered with ClinicalTrials.gov, number NCT00161005. Results. By April 2006, 109 patients have been randomized. Thrombolysis has been given prehospitally to 52% of patients. The median transport distance from first medical contact to catheterization laboratory was 155 km (range 90–396 km). Results of the study are expected in 2008.

Trial registration: ClinicalTrials.gov identifier: NCT00161005.     

Continuum beliefs and stigmatizing attitudes towards persons with schizophrenia,depression and alcohol dependence

Separation is a central step in the process of stigmatizing persons with mental disorders. We examine whether belief in a continuum of symptoms from mental health to mental illness is associated with less stigmatizing attitudes. In a representative population survey in Germany (n=3642), using case-vignettes of persons suffering from schizophrenia, depression or alcohol dependence, we measured belief in a continuity of symptoms, emotional reactions and desire for social distance related to the person described in the vignette. While 42% of respondents agreed in symptom continuity for depression, this percentage was 26% for schizophrenia and 27% for alcohol dependence. Continuum beliefs were associated in general with more positive emotional reactions and less desire for social distance. This relationship was strongest for schizophrenia, followed by alcohol dependence. Continuum beliefs thus seem to be associated with less stigmatizing attitudes, particularly regarding schizophrenia and alcohol dependence. Educational information on the continuous nature of most psychopathological phenomena could usefully be integrated in anti-stigma messages.     

Interval data clustering using self-organizing maps based on adaptive Mahalanobis distances

The self-organizing map is a kind of artificial neural network used to map high dimensional data into a low dimensional space. This paper presents a self-organizing map for interval-valued data based on adaptive Mahalanobis distances in order to do clustering of interval data with topology preservation. Two methods based on the batch training algorithm for the self-organizing maps are proposed. The first method uses a common Mahalanobis distance for all clusters. In the second method, the algorithm starts with a common Mahalanobis distance per cluster and then switches to use a different distance per cluster. This process allows a more adapted clustering for the given data set. The performances of the proposed methods are compared and discussed using artificial and real interval data sets.     

Associations between intrauterine exposure to polychlorinated biphenyls on neonatal ano-genital distance

Polychlorinated Biphenyls (PCBs) are widespread environmental contaminants. PCBs have endocrine disrupting properties which raises concerns regarding their effect on the developing fetus.This study aimed to examine the association between prenatal exposure to PCBs and anogenital distance (AGD) in newborns.Serum concentrations of PCB congeners -118, -138, -153 and -180 were measured in 175 pregnant women presenting to the delivery room. AGD was measured in their newborns. Regression models were used to estimate associations between maternal PCB exposure and infant anogenital measurements, controlling for possible confounding variables.Mean maternal serum concentrations were 2.95 ± 2.18 ng/g, 4.62 ± 3.54 ng/g, 7.67 ± 6.42 ng/g and 5.10 ± 3.91 ng/g for congeners -118, -138, -153 and -180, respectively. Higher maternal concentrations of PCBs were associated with reduced AGD measures in male infants. Higher maternal concentrations of PCB-138 and PCB-153 were associated with reduced ano-scrotal distances and higher maternal concentrations of all four PCB congeners were associated with reduced ano-penile distances. No significant associations were found between any PCB congener and any AGD measure in female newborns.This study demonstrates that intrauterine exposure to PCBs may be associated with reduced AGD in male newborns. More research is needed to reveal the implications for adult reproductive health.