电离辐射对大鼠咬肌细胞ATP酶活性的影响

目的观察电离辐射对大鼠咬肌细胞ATP酶活性的影响,为放射性骨骼肌损伤的机制提供理论依据。方法一次性20 Gy X射线局部照射大鼠咬肌区,化学比色法检测照射后大鼠咬肌Na＋-K＋-ATP酶、Ca2＋-ATP酶、Mg2＋-ATP酶和Ca2＋-Mg2＋-ATP酶等活性的变化。结果照射后3天大鼠咬肌Na＋-K＋-ATP酶、Ca2＋-ATP酶、Mg2＋-ATP酶和Ca2＋-Mg2＋-ATP酶等活性分别降低了15.3%、15.1%、31.1%和16.4%,照射后30天分别降低了36.9%、35%、48.8%和36.9%。照射后30天,照射组大鼠咬肌ATP酶活性与对照组有显著性差异。结论 ATP酶活性降低,肌细胞离子代谢紊乱与放射性骨骼肌损伤有关。     

电离辐射对大鼠咬肌细胞超微结构及糖原含量的影响

目的观察电离辐射对大鼠咬肌形态学和糖原含量的影响。方法28只雄性SD大鼠,照射组16只,对照组12只。照射组大鼠腹腔注射2%盐酸氯胺酮麻醉后,一次性20GyX射线局部照射咬肌区。对照组只麻醉,但不照射。记录大鼠体重变化,H＆E染色、PAS染色、电镜观察形态学变化,蒽酮法测定肌糖原含量变化。结果照射组大鼠体重暂时性降低,持续到第11天。照射后第12天,照射组大鼠体重开始同对照组一样增长。照射后大鼠咬肌没有明显炎症细胞浸润,没有明显肌纤维溶解破坏等。照射后部分肌浆网肿胀扩张,部分线粒体空泡性变明显。照射后3天,照射组大鼠咬肌糖原含量减少约25%,与对照组有显著性差异。照射后30天,照射组与对照组没有显著性差异。结论照射后大鼠咬肌形态和代谢发生了变化。     

电离辐射对大鼠咬肌钙泵活性和表达的短期影响

-ATP酶本身功能异常造成的.     

Regional differences in blood flow variation in rat masseter muscle

Regions of a belly in a masseter muscle have been suggested to be activated independently in order to enable complex jaw-movements. However a regional difference of the masseter blood flow (MBF) is still unclear although the blood flow is one of the most important factors during activation of the muscle. The present study examined regional differences in blood flow in rat masseter muscle by comparing blood flow values at the inferior, centre, superior, anterior, and posterior regions of the muscle belly using a laser speckle imaging flowmeter with or without sympathetic and parasympathetic stimulation. Regional differences in blood flow levels were observed in each region of the masseter muscle belly during rest. Additionally, amplitudes of blood flow changes evoked by electrical stimulation of parasympathetic and sympathetic nerves differed among regions. These results demonstrate the regional differences in hemodynamics during rest, sympathetic vasoconstriction (including the recovery phase), and parasympathetic vasodilatation in rat masseter muscle.     

人咬肌肌梭的分布及体视学分析

目的 :查明人咬肌肌梭的形态和分布特征 ,探讨其在下颌运动中的神经生物学作用。方法 :对 10侧人咬肌的肌梭作形态学观察 ,并用图像分析仪对测量数据进行分析和量化处理。结果 :咬肌肌梭分布不均匀 ,多成簇的分布于特定的区域 ,且形态多样 ,以单个体和联合体形式存在 ,联合体多存在于咬肌深层 ,与浅层比较有显著差异。深、浅两层肌梭的体积和梭内肌数目比较均无显著性差异。咬肌深层有较多肌梭分布 ,且密集于肌腱和颞下颌关节处 ;而浅层肌梭较少 ,两层之间有显著性差异。结论 :咬肌肌梭分布呈现异质性 ,深层肌梭密度高 ,浅层低。在咬肌收缩中 ,其肌梭的感觉传入冲动主要来源于咬肌深层。     

人咬肌和颞肌的肌构筑及生物学特性

目的：查明人咬肌和颞肌的肌构筑特征，分析两肌各部的生物力学属性，探讨其生理功能，方法：对人10侧咬肌和颞肌的构筑指数作测算和量化分析，结果：咬肌和颞肌均属多羽肌范畴，尤其是咬肌浅部内存在有多层腱板，肌纤维以浅-深两面附着于腱板上，对咬肌浅，深两部，颞肌前，后两部的肌构筑指数分别作两两比较，其构筑指数在各部间均有明显不同，其中，颞肌后部肌质量值最大，咬肌浅部次之，咬肌深部最轻，而生理横切面积则是咬肌浅部最大，依次为颞肌后部，颞肌前部，咬肌浅部和颞肌前部相近，最低者为颞肌后部，颞肌后部肌纤维最长，咬肌深部肌纤维最短，以上比较均有显著性差异。结论：咬肌深部属力量型肌，咬肌浅部和颞肌前部兼备力量和速度，而颞肌后部相对倾向于速度型肌，咬肌深部和颞肌前部在维持下颌位置和平衡中起重要作用，咬肌浅部和颞肌后部是产生咬合力和下颌快速移位的主体。     

力增强对大鼠牙周组织IL-6 mRNA表达影响的研究

目的 :检测不同牙合力状态下 ,大鼠牙周膜成纤维细胞和牙槽骨成骨细胞中IL - 6mRNA的动态表达 ,探讨IL - 6在牙周组织改建过程中的分子机制。方法 :选用Wistar大鼠建立正常牙合力、牙合力增强的动物模型 ,采用原位杂交的方法 ,观察成纤维细胞和成骨细胞中IL - 6mRNA表达的动态变化。结果 :牙合力增强诱导成纤维细胞和成骨细胞中IL - 6mRNA表达较正常牙合力时明显增强。结论 :牙合力增强 ,促使牙周组织中的成纤维细胞和成骨细胞产生IL - 6mRNA明显增多 ,且出现一定的规律性变化 ,提示IL - 6在牙合力影响牙周组织改建的过程中起着重要的调节作用。     

He力增强对大鼠牙周组织IL—6mRNA表达影响的研究

目的：检测不同He力状态下，大鼠牙周膜成纤细胞和牙槽骨成骨细胞中IL－6mRNA的动态表达，探讨IL－6在牙周组织改建过程中的分子机制。方法：选用Wistar大鼠建立正常He力、He力增强的动物模型，采用原位杂交的方法，观察成纤细胞和成骨细胞中I-6mRNA表达的动态变化。结果：He力增强诱导成纤维细胞和成骨细胞中IL-6mRNA表达较正常He力时明显增强。结论：He力增强，促使牙周组织中的成纤维细胞和成骨细胞产生IL－6mRNA明显增多，且出现一定的规律性变化，提示IL－6在He力影响牙周组织改建的过程中起着重要的调节作用。     

Intramuscular lipoma in the masseter muscle: a case report

This is the first report to our knowledge of an intramuscular lipoma that arose in the masseter muscle. Excision biopsy under general anaesthesia showed that the mass could easily be separated from the surrounding soft tissues on the lateral side, but was firmly adherent to the muscle on the medial side, so complete excision required resection of part of the masseter. Histopathological examination showed that it was an intramuscular lipoma. Two years and 6 months postoperatively there was no evidence of recurrence.     

Changes in masseter muscle blood flow during voluntary isometric contraction in humans

The effect of jaw clenching on local blood flow in the masseter muscle was measured using the hydrogen clearance method in 13 healthy subjects. Sustained isometric masseter-muscle contraction levels of 25 and 50% of maximum voluntary contraction (MVC) were investigated. The blood flow at 25% MVC before contraction, during contraction and after contraction was 12.3 +/- 10.9, 19.2 +/- 12.1 and 78.8 +/- 63.9 mL min(-1) (100 g)(-1) (mean +/- s.d.), respectively. At 50% MVC, it was 14.2 +/- 12.9, 18.6 +/- 10.0 and 80.1 +/- 61.8, respectively. The volume of blood flow was significantly greater after contraction as compared with before contraction at both levels (P < 0.0001) and there was no significant difference between before and during contraction periods (P = 0.17: 25% MVC; P = 0.38: 50% MVC). At 50% MVC blood flow before contraction and the difference in blood flow before and during contraction showed significant negative correlation (r = -0.636, P < 0.02). When the volume of blood flow was low before contraction it tended to increase during contraction and decreased when it was high before contraction. These findings indicate that blood flow in the masseter muscle during sustained isometric contraction is affected by the condition of contraction and may be influenced by the muscle region. It was also indicated that the blood flow during high level contraction was influenced by the volume of blood flow before contraction. Clinically, our findings may help to understand pathological changes which may lead to chronic masticatory muscle pain.     

汉族和哈萨克族慢性牙周炎的严重程度与 IL-6和 IL-17相关性分析

纳入新疆木垒地区慢性牙周炎（CP）患者116例,62例汉族组,54例哈萨克族组。以口腔健康的50例汉族,45例哈萨克族为对照。ELISA 检查血液和唾液中 IL-6、IL-17水平。血清与唾液 IL-6和 IL-17水平病例组高于对照组（P ＜0．05）,随 CP 严重程度而升高（P ＜0．05）,哈萨克族病例高于汉族病例组（P ＜0．05）。     

Idiopathic hypoplasia of the masseter muscle: A case report

Objective and importance: Hypoplasia of the masseter muscle is a rare condition, described as partial or total, associated with congenital malformations or pathologies. Rare cases are those with no genetic alterations in their familiar picture. The authors present a case of an idiopathic masseter muscle hypoplasia in the absence of other pathologies.

Clinical presentation: The case report involved a patient who presented to the consultant clinic complaining of facial asymmetry. The patient underwent several exams to confirm the diagnosis of masseter muscle hypoplasia, which included an X-ray, magnetic resonance of the temporomandibular articulation, and electromyography.

Intervention: The patient was treated with a customized functional appliance and fixed orthodontic treatment with satisfactory functional and esthetic results.

Conclusion: The case presented highlights the possibility of finding a hypoplasia of the masseter muscle even in the absence of other pathologies and without specific clinical symptoms, and how to plan an appropriate treatment with functional appliance and fixed orthodontic therapy.     

Bilateral effect of a unilateral occlusal splint on the expression of myosin heavy-chain isoforms in rat deep masseter muscle

Many studies have shown that various myosin isoforms are involved in muscle contraction. A search for specific antibodies directed against the myosin heavy chain (MHC) resulted in the identification of at least two main classes, referred to as MHC type I and type II. In this study, immunohistology and gel electrophoresis were used to determine the proportion of MHC isoforms in rat deep masseter muscle at different times after the insertion of an unilateral occlusal splint. An increasing proportion of MHC type I isoforms was found in both deep masseters soon after splinting, and this trend continued until 7 days after splint insertion. The type I fibres were clearly distributed on either side of the central axis of the muscle. At 15 days, a significant decrease in the percentage of the type IIb MHC isoform was observed on the occlusal splint side compared to the contralateral side. After 30 days of unilateral splinting, the proportion of type IIb fibres on the splint side returned to baseline whereas on the contralateral side there was an increase in the proportion of this type. The results suggest an initial adaptation after the unilateral occlusal disturbance in which muscles of both sides react in the same way; later, the muscles of each side adapt their expression of MHC isoforms according to altered functional demand.     

Fatigue and damage to the masseter muscle by prolonged low-frequency stimulation in the rat

This study aimed to examine peripheral fatigue and the resultant damage to the masseter muscle due to prolonged low-frequency stimulation. Thirty male rats were divided into S1, S2, S4, Dantr and Sham groups. The left masseters were used as experimental muscles. A pair of stimulation electrodes was placed on the left masseter. A stimulating session included rectangular electric pulses of 18 Hz (5 mA, 18 V, 0.7 ms) for 2 h with a 3 min rest period between sessions. One session was given to the S1 group, two sessions to the S2 group and four sessions to the S4 group. Four sessions were given to the Dantr group with administration of dantrolene to determine any artifacts of the electrical current. No electric stimulation was given to both side masseters in the Sham group or to the control (right) masseters in the other groups. In each session, jaw-closing force increased to a peak within 1 min and attenuated to the steady force. The peak force decreased as the session advanced in each group. Both side masseters were dissected after the stimulations and examined histologically. The experimental masseter was significantly heavier than that of the controls in the S1, S2 and S4 groups, and the muscle fibres showed irregularity of size and shape with enlargement of interstitial space and infiltration of mononuclear cells into the fibres. However, no such histological change was observed in the Dantr and Sham groups. It was confirmed that fatigue and damage to muscle fibres could be induced in masticatory muscles by prolonged low-frequency stimulation.     

种植体型功能矫治器矫治过程中Beagle犬咬肌肌纤维类型的变化

目的:观察种植体型功能矫治器引导Beagle犬下颌骨前移治疗过程中咬肌MyHC-Ⅰ表达量的变化,探讨种植体型功能矫治器矫治过程中咀嚼肌的适应性改建,为矫形治疗提供理论依据.方法:8只7个月龄雄性Beagle犬分别在安装矫治器治疗后4、8、12周及拆除矫治器后4周(即16周)处死,取咬肌浅层中部组织做切片,用SABC法检测MyHC-Ⅰ在Beagle犬咬肌中的表达,采用SPSS 11.5软件包对数据进行统计学分析.结果:MyHC-Ⅰ在对照组咬肌中的阳性表达率为7.61％,在4周实验组咬肌中的阳性表达率为20.43％(P＜0.01),8周时达到最大,而后逐渐减少.拆除矫治器后,咬肌中MyHC-Ⅰ的表达逐渐减少,直至与对照组水平接近.结论:种植体型功能矫治器前移下颌过程中咬肌MyHC-Ⅰ的表达出现明显变化,种植体型功能矫治器能明显促进咀嚼肌的适应性改建.     

咬合力增强对大鼠牙周组织白细胞介素-6表达影响的研究

目的：检测咬合力在正常及增强状态下,大鼠牙周细胞ＩＬ－６的动态表达,初探ＩＬ－６在牙周组织改建中作用的分子机别。方法：采用免疫组化的方法,观察牙周形态变化以及牙周组织中ＩＬ－６蛋白表达。结果：咬合力增强引起牙周膜增宽、牙槽骨新骨形成。牙周细胞中ＩＬ－６表达较正常咬合力时明显增强。结论：咬合力增强,促使牙周组织产生ＩＬ－６明显增多,诱发了破骨功能;同时,还激活了成骨功能。     

Patterns of masseter muscle activities during sleep in guinea pigs

Basic neurophysiological mechanisms for sleep bruxism remain unknown. Analyses of masseter muscle activity during sleep in guinea pigs have shown that the duration and activity of masseter bursts differ between non-rapid eye movement (NREM) and rapid eye movement (REM) sleep and that some repetitive burst episodes do occur. Furthermore, masseter bursts occurred in association with a transient heart rate increase. These results suggest that various patterns of masseter bursts occur in association with transient arousal activity during sleep in guinea pigs.     

青年女性浅层咬肌B超形态与颅颌面形态关系的研究

目的:了解浅层咬肌形态及功能与颅颌面形态之间相互作用关系及作用模式,探讨错畸形的形成机制。方法:采用超声成像技术测量31例正常青年女性浅层咬肌横截面的周长、面积、横径、平均厚度及纵截面的长度,并将其与头影测量指标进行统计相关分析。结果:浅层咬肌纵截面的长度与下颌升支与SN平面的前下交角、下颌体长度、下颌综合长度、前下面高、全前面高、磨牙区牙槽高成正相关关系。浅层咬肌横截面的平均厚度和最大厚度与上颌骨长度、下颌升支高度、后面高成正相关关系。结论:浅层咬肌的厚度、长度对颅颌面垂直向形态有显著影响,同时浅层咬肌厚度也影响面中份深度。