局部注射VEGF对大鼠正畸牙齿移动的影响

目的：观察局部注射重组鼠的血管内皮生长因子(rrVEGF)对大鼠正畸牙齿移动的影响，探讨VEGF在正畸牙齿移动中的作用机制。方法：45只雄性SD大鼠，牵引其上颌第一磨牙近中移动，实验中分别将rrVEGF及生理盐水注射入实验组及对照组大鼠右侧上颌第一磨牙腭侧的骨粘膜下，于实验前3天开始注射，每3天一次。分别在加力l、3、7、14、2l天后记录上颌第一磨牙移动距离。然后将各组动物处死，用HE染色观察牙周组织变化情况并采用免疫组织化学方法对组织中表达的VEGF进行分析。结果：实验组大鼠压力侧破骨细胞教和成骨细胞数在实验全过程中均多于对照组，而且，实验组大鼠牙齿移动距离明显大于对照组。结论：进一步证实VEGF作为旁分泌因子，参与了牙齿移动过程中的牙周组织改建，内源性VEGF和注射VEGF都使牙齿移动量显著增加。因此，VEGF在正畸牙齿移动的机制中具有重要意义。     

Changes in EEG order in neuroleptically treated normal volunteers during a voluntary movement task

Summary 15 normal volunteers were treated over three weeks with haloperidol (HAL) and in the third week additionally with biperidene (BIP). The order of the EEG spectra at different topographical locations and in different frequency bands during a movement task was analyzed using uncertainty analysis (UA), a multivariate analysis technique based on informationtheoretical methods. Different patterns of drug-induced changes were found. HAL decreases the theta and alpha band order at the fronto-central lateral areas but increases it at the fronto-central midline in the theta band and at the parietal areas in the alpha band. With the exception of the fronto-central midline locations, BIP more or less counterbalances the effect of HAL. Volunteers felt unwell and had motor disturbances during HAL and felt well again during HAL + BIP. Reaction time values were increased during HAL and normalized during HAL + BIP.     

Neurons in the Primate Superior Colliculus are Active Before and During Arm Movements to Visual Targets

The activity of single neurons in the superior colliculus was recorded while a rhesus monkey made arm movements to visual targets located on a screen in front of him. It was found that the activity of a subpopulation of cells was clearly related to these arm movements. The neurons began to discharge either with the onset of the movement, during the movement period, or well before the onset of electromyogram (EMG) activity and movement, and could be active for the entire duration of EMG activity. While the discharge pattern of some of these'reach'neurons was not different for movements to different target positions, other cells showed graded changes in activity depending on the direction of movement. The peak discharge rate could rise to > 100 impulses/s. Some units received somatosensory input; other reach cells exhibited a visual response and/or presaccadic activity. It is likely that the primate superior colliculus is not only involved in the initiation and control of orientating movements of the eyes but also in reaching movements of the arms.     

92例跟骨骨折后足部畸形功能障碍治疗探讨

本文对92例106足波及距下关节的跟骨骨折治疗后1～6年遗留足畸形、功能障碍的病例(PALey:舌型17足,中央压陷型53足,严重粉碎型36足)进行了分析和总结。作者强调解剖复位、牢靠固定、一期植骨、早期关节持续被动运动及不过早负重是预防跟骨骨折众多并发症的重要措施。     

Chorea as a presenting feature of variant Creutzfeldt-Jakob disease.

We report on a patient with pathologically proven variant Creutzfeld-Jakob disease in whom chorea was a presenting feature of the disease, and was unaccompanied by the typical prodrome of psychiatric disturbance or sensory symptoms.     

Shoulder strain in keyboard workers and its alleviation by arm supports

Summary Keyboard work consists mostly of dynamic contractions of the small muscles of the forearms and hands. This is accompanied by continuous activity in the arm, shoulder and neck muscles keeping the head and hand in the correct position. Eliminating the weight from the arm by means of support and the position of the arms influences the electrical activity of shoulder muscles when working at a keyboard. We studied the influence of elbow angle, as well as that of different arm supports, on electrical activity of upper trapezius muscle during keyboard work in healthy workers and persons suffering from shoulder pains. The measurements were carried out in the laboratory. EMG activities, which where measured as mean square root (RMS)-values at every 100-millisecond period in trapezius muscle when working, were lower, the greater the elbow angle. Furthermore electrical activity decreased when subjects used arm supports while working. It is evident that the static load to shoulder muscles can be lowered significantly in keyboard work, when the forearms are at an angle of at least 100 degrees and by using arm supports. The most convienient and ergonomic working position can also be found individually be the method used here.     

The effects of orthodontic tooth movement on the glycosaminoglycan components of gingival crevicular fluid

Abstract In this study, gingival crevicular fluid (GCF) was collected from around a canine tooth, in children, before and during orthodontic tooth movement. The aim was to identify and quantify the glycosaminoglycan (GAG) components of GCF and relate them to tooth movement, gingival inflammation, plaque accumulation, pocket probing depth and GCF volume recorded at the site of sampling. GAG in GCF samples, collected for a 15-min period into microcapillary tubes, were separated electrophoretically, stained with Alcian blue and quantified using a laser densitometer. 2 GAG components of hyaluronic acid (HA) and chondroitin sulphate (CS) were identified. The increase in GCF volume during orthodontic tooth movement was only partly due to increased gingival inflammation, GAG levels varied with different types of orthodontic tooth movement. In GCF, levels of CS, in particular, may reflect the changes in the deeper periodontal tissues which could be monitored during orthodontic tooth movements.     

Modulation of cutaneous reflexes in arm muscles during walking: further evidence of similar control mechanisms for rhythmic human arm and leg movements

Stimulation of cutaneous nerves innervating the hand evokes prominent reflexes in many arm muscles during arm cycling. We hypothesized that the mechanisms controlling reflex modulation during the rhythmic arm swing of walking would be similar to that documented during arm cycling. Thus, we expected cutaneous reflexes to be modulated by position in the walking cycle (phase dependence) and be different when walking compared to contraction while standing (task dependence). Subjects performed static postures similar to those occurring during walking and also walked on a treadmill while the superficial radial nerve was electrically stimulated pseudorandomly throughout the step cycle. EMG was recorded bilaterally from upper limb muscles and kinematic recordings were obtained from the elbow and shoulder joints. Step cycle information was obtained from force-sensing insoles. Analysis was conducted after averaging contingent upon the occurrence of stimulation in the step cycle. Phase-dependent modulation of cutaneous reflexes at early (~50–80 ms) and middle (~80–120 ms) latencies was observed. Coordinated bilateral reflexes were seen in posterior deltoid and triceps brachii muscles. Task dependency was seen in that reflex amplitude was only correlated with background EMG during static contraction (75% of comparisons for both early and middle latency reflexes). During walking, no significant relationship between reflex amplitude and background EMG level was found. The results show that cutaneous reflex modulation during rhythmic upper limb movement is similar to that seen during arm cycling and to that observed in leg muscles during locomotion. These results add to the evidence that, during cyclical movements of the arms and legs, similar neural mechanisms observed only during movement (e.g. central pattern generators) control reflex output. Electronic Publication     

The breakdown of Fitts' law in rapid,reciprocal aiming movements

According to Fitts' law, there is speed-accuracy trade-off in a wide variety of discrete aiming movements. However, it is unknown whether the same law applies to cyclic aiming movements. In the present study, a comparison is made between discrete versus cyclic aiming movements. A group of 24 healthy participants made graphical pen movements in 12 different aiming tasks in which successive finger and wrist movements were emphasized, consecutively executed as discrete and cyclic movements and varying in three target widths. In the cyclic condition, aiming movements consisted of back-and-forth movements that were performed in immediate succession for 20 s. In the discrete condition, back-and-forth aiming movements were drawn as 20 single strokes, starting after a go signal and stopping after reaching the target area. The targets had various levels of spatial accuracy and the movements had different directions (from lower left to upper right; from lower right to upper left) elicit either predominantly wrist or finger movements. The amount of information processed per unit of time (bits per second; index of performance, IP), tangential velocity, the pen pressure, and the ratio of peak-over-mean velocity were studied to gain understanding about the differences in control between discrete and cyclic movements. It was found that the IP and movement velocity were almost twice as large in cyclic versus discrete movements. In contrast, the axial pen pressure and the ratios of peak-over-mean velocity were much lower in cyclic movements (1.24 N versus 0.94 N; 2.26 N versus 1.81 N). The results of our study indicate that the predicted constant IP does not hold for rapid cyclic aiming movements and that speed-accuracy trade-off is different. It is concluded that cyclic movements exploit the energetic and physiological properties of the neuromotor system. Expected differences in brain activity related to discrete and cyclic aiming movements are discussed as well as several neurophysiological mechanisms, which predict more economic force recruitment and information processing in cyclic than in discrete movements.     

Retinal slip during active head motion and stimulus motion

Gaze control in various conditions is important, since retinal slip deteriorates the perception of 3-D shape of visual stimuli. Several studies have shown that visual perception of 3-D shape is better for actively moving observers than for passive observers watching a moving object. However, it is not clear to what extent the improved percept of 3-D shape for active observers has to be attributed to corollary discharges to higher visual centers or whether the improved percept might be due to improved gaze stabilization during active head movements. The aim of this study was to measure binocular eye movements and to make a quantitative comparison of retinal slip for subjects instructed to fixate a visual stimulus in an active condition (subject makes an active head movement, object is stationary) and in a passive condition (the stimulus moves, the subject is stationary) for various movement frequencies, viewing distances, and stimulus diameters. Retinal slip remains below the acuity threshold of about 4 deg/s in active conditions, except for the highest frequency tested in this study (1.5 Hz) for nearby targets (0.25 cm). Retinal slip exceeds this threshold for most passive conditions. These results suggest that the enhanced performance in the visual perception of 3-D shape during active head movements can, at least partly, be explained by better fixation by actively moving observers.