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排序方式: 共有264条查询结果,搜索用时 31 毫秒
1.
Lina P Theodorakopoulou P Lionel Sadowsky Alex Jacobson William Lacefield 《American journal of orthodontics and dentofacial orthopedics》2004,125(3):329-336
The objectives of this study were to evaluate and compare the shear bond strengths and bond failure locations of 2 currently available orthodontic ceramic brackets. Forty polycrystalline ceramic brackets (Clarity, 3M Unitek, Monrovia, Calif) and 40 monocrystalline ceramic brackets (Inspire, Ormco, Orange, Calif) were bonded to 80 extracted premolars with the same bonding system. All bonded specimens were placed in distilled water for 42 hours at 37 degrees C followed by thermal cycling for 700 complete cycles. Forty ceramic brackets, 20 of each type, were tested on a universal testing machine to determine the shear force levels required to debond them. Forty ceramic brackets were removed with the debonding pliers recommended by the manufacturers. All teeth were examined under an optical microscope, and the adhesive remnant index was used to assess the bond failure locations. The mean shear bond strength of the Clarity brackets was 21.67 +/- 5.19 MPa, and the mean shear bond strength of the Inspire brackets was 20.32 +/- 8 MPa. The mean shear bond strengths of both brackets were higher than those considered clinically optimal. Most of the brackets (85% of Clarity and 75% of Inspire) tested on the machine failed at the bracket-adhesive interface. One premolar bonded with an Inspire bracket had enamel fracture upon debonding. Most of the brackets (90% of Clarity and 95% of Inspire) debonded with pliers failed at the bracket-adhesive interface. No enamel damage was evident in any specimen when the brackets were removed with the appropriate pliers. The results indicate that the safest way to remove ceramic brackets with respect to reducing the chance of enamel damage is to use the debonding technique specifically designed for each. 相似文献
2.
Global dendritic calcium spikes in mouse layer 5 low threshold spiking interneurones: implications for control of pyramidal cell bursting 总被引:1,自引:1,他引:1
Interneuronal networks in neocortex underlie feedforward and feedback inhibition and control the temporal organization of pyramidal cell activity. We previously found that lower layer neocortical interneurones can reach action potential threshold in response to the stimulation of a single presynaptic cell. To better understand this phenomenon and the circuit roles of lower layer neocortical interneurones, we combined two-photon calcium imaging with whole cell recordings and anatomical reconstructions of low threshold spiking (LTS) interneurones from mouse neocortex. In both visual and somatosensory cortex, LTS interneurones are somatostatin-positive, concentrated in layer 5 and possess dense axonal innervation to layer 1. Due to the LTS properties, these neurones operate in burst and tonic modes. In burst mode, dendritic T-type calcium channels boosted small synaptic inputs and triggered low threshold calcium spikes, while in tonic mode, sodium-based APs evoked smaller calcium influxes. In both modes, the entire dendritic tree of LTS interneurones behaved as a 'global' single spiking unit. This, together with the fact that synaptic inputs to layer 5 LTS cells are facilitating, and that their axons target the dendritic region of the pyramidal neurones where bursts are generated, make these neurones ideally suited to detect and control burst generation of individual lower layer pyramidal neurones. 相似文献
3.
BACKGROUND: Optical penalization (OP) has previously been shown to successfully maintain vision in amblyopic eyes of older children when patching compliance is poor and when vision decreases once patching is discontinued. This study shows that the final vision in optically penalized eyes is often better than the vision obtained after patching alone. SUBJECTS AND METHODS: During the 5-year period from January 1992 to February 1997, 28 children aged between 3.7 and 8.2 years (average age, 6.5+/-1.1 years) were optically penalized for an average of 1.5+/-0.75 years. The maximum length of penalization was 3.3 years, whereas the minimum time was 6 months. There were 21 children with strabismic amblyopia and 7 children with anisometropic amblyopia. All 28 children had worn a patch to achieve their best visual levels and then had shown a loss of best vision when occlusion was stopped. Patching was usually resumed and continued until the previous best vision was obtained; at this point OP was started to "maintain" vision. Eighteen of the 28 children have discontinued penalization and have been followed up an average of 1(1/2) years. RESULTS: Twenty-six (93%) of the 28 patients showed an increase in best vision from that found at the conclusion of patching, and 2 patients maintained their vision at the initial level. The average visual acuity at the start of penalization was 20/50 (0.42+/-0.11 logarithm of the minimum angle of resolution [log MAR]). Final average visual acuity was 20/27 (0.15+/-0.12 log MAR). The average increase in vision was nearly 3 lines or 0.27+/-0.12 log MAR. CONCLUSION: OP alone (without the use of pharmacologic agents such as atropine) not only maintains vision after patching therapy, but also appears to improve the final visual outcome. 相似文献
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目的:考察盐酸特拉唑嗪胶囊的稳定性。方法:通过影响因素(强光照射、高温、高温),加速和留样考察实验,以含量为测定指标,考察胶囊的含量变化。结果:在温度40℃、60℃、光照3500LX及RH75%等因素影响下,胶囊的含量无明显变化。结论:在25℃时,通过经典恒温加速试验推测盐酸特拉唑嗪胶囊的失效期为2年。 相似文献
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Schwann cells are glial cells of peripheral nervous system, responsible for axonal myelination and ensheathing, as well as tissue repair following a peripheral nervous system injury. They are one of several cell types that are widely studied and most commonly used for cell transplantation to treat spinal cord injury, due to their intrinsic characteristics including the ability to secrete a variety of neurotrophic factors. This mini review summarizes the recent findings of endogenous Schwann cells after spinal cord injury and discusses their role in tissue repair and axonal regeneration. After spinal cord injury, numerous endogenous Schwann cells migrate into the lesion site from the nerve roots, involving in the construction of newly formed repaired tissue and axonal myelination. These invading Schwann cells also can move a long distance away from the injury site both rostrally and caudally. In addition, Schwann cells can be induced to migrate by minimal insults (such as scar ablation) within the spinal cord and integrate with astrocytes under certain circumstances. More importantly, the host Schwann cells can be induced to migrate into spinal cord by transplantation of different cell types, such as exogenous Schwann cells, olfactory ensheathing cells, and bone marrow-derived stromal stem cells. Migration of endogenous Schwann cells following spinal cord injury is a common natural phenomenon found both in animal and human, and the myelination by Schwann cells has been examined effective in signal conduction electrophysiologically. Therefore, if the inherent properties of endogenous Schwann cells could be developed and utilized, it would offer a new avenue for the restoration of injured spinal cord. 相似文献
9.
Safety of sofosbuvir‐based regimens after liver transplantation: longitudinal assessment of renal function in the prospective ANRS CO23 CUPILT study
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R. Anty G. Favre A. Coilly E. Rossignol P. Houssel‐Debry C. Duvoux V. De Ledinghen V. Di Martino V. Leroy S. Radenne N. Kamar V. Canva L. D'Alteroche F. Durand J. Dumortier P. Lebray C. Besch A. Tran C. M. Canivet D. Botta‐Fridlund H. Montialoux C. Moreno F. Conti C. Silvain P. Perré F. Habersetzer A. Abergel M. Debette‐Gratien S. Dharancy V. L. M. Esnault C. Fougerou‐Leurent C. Cagnot A. Diallo A. Veislinger H. Danjou D. Samuel G.‐P. Pageaux J.‐C. Duclos‐Vallée the ANRS CO CUPILT Study Group 《Alimentary pharmacology & therapeutics》2018,47(12):1682-1689
10.
目的:检测维甲酸(Retinoic acid,RA)诱导小鼠胚胎腭裂模型中胎鼠舌体发育过程中肌相关 microRNAs(MyomiRs)、成肌调节因子(Myogenic regulatory factors,MRFs)以及 Pax 基因的表达变化,探究 MyomiRs 在舌肌分化过程中的调控作用,推测RA 致胎鼠腭裂伴发舌异常的可能机制。方法:建立 RA 诱导小鼠胚胎腭裂模型,分别在 E13.5、E14.5、E15.5收集胎鼠舌体组织,用 SYBR GreenⅠ实时定量 PCR 检测舌体中 MRFs 和 Pax 基因的表达;用 TaqMan 探针实时定量 PCR 检测舌体中 MyomiRs 的表达。结果:胎鼠舌体发育过程中,正常组 miR-1和 miR-206相对表达量均持续上升,RA 诱导组二者变化趋势与正常组相似,但相对表达量均低于正常组,miR-1的结果在 E14.5和 E15.5具有统计学意义(P <0.01),miR-206的结果在 E13.5具有统计学意义(P <0.05)。正常组和 RA 诱导组胎鼠舌体中 MyoD 和 Myf5相对表达量都在 E14.5达到峰值,随后下降。RA 诱导组 MyoD 的表达在 E14.5显著低于正常组(P <0.05),在 E15.5显著高于正常组(P <0.01);RA 诱导组 Myf5的表达在 E15.5显著低于正常组(P <0.05)。正常组和 RA 诱导组胎鼠舌体中 Pax3表达均在 E14.5达到峰值,Pax7表达均在 E15.5达到峰值。RA 诱导组 Pax3的表达在 E14.5显著高于正常组(P <0.05);Pax7的表达则在 E13.5显著高于正常组(P <0.01)。结论:在舌肌分化过程以及RA 诱导腭裂胎鼠的舌发育异常中,miR-1/miR-206与 Pax3/Pax7及 Myf5/MyoD 的表达趋势具有相关性。RA 可能通过下调 miR-1/miR-206而靶向上调 Pax3/Pax7,进而下调 MyoD /Myf5表达,从而抑制舌肌分化,导致舌肌发育异常。 相似文献