牙体牙弓颌骨阻力中心及其临床意义

牙体、牙弓及颌骨的阻力中心在正畸矫治力系统中具有重要的意义,也是正畸学领域争论较多的一个问题。Dermaut等研究表明,当力作用于物体阻力中心时,物体将发生平动,否则将发生平动和转动的复合运动。目前,国内外多数学者认为牙体、牙弓及颌骨存在阻力中心,但其位置存在争议。本文就牙体、牙弓及颌骨的阻力中心及其临床意义作一综述。     

Hazards and complications of endoscopic transurethral ureterolithotripsy and lithoextraction and means of prevention

Complications related to ureterolithotomy and ultrasonic ureterolithotripsy performed under the control of visual endoscope were analyzed in 86 ureterolithiasis patients, methods of their prevention discussed. All the aforementioned complications were distributed into three groups: inapplicability of surgery due to anatomic and functional defects of lower and upper urinary tracts, intraoperative, and postoperative complications. The commonest ones were ureteral abruption and perforation, acute pyelonephritis, temporary vesicoureteral reflux. Their control measures were considered as relative methods of treatment: immediate surgical intervention in case of ureteral abruption, renal catheterization in patients with insignificant ureteral perforation or acute pyelonephritis. Adequate ureteroscopy, careful consideration of pro- and contraindications, catheterization of renal pelvis and urinary bladder performed within 2-3 days after the surgery and adequate antibacterial therapy are the most decisive steps in the control of aforementioned complications.     

Characterisation and differentiation of chondroblastomas and chondromyxoidfibromas - presence and expression of collagen types I and II

AIM: Chondroblastomas and chondromyxoidfiibromas are rare benign skeletal neoplasms with reported overlapping histology. Aim of this study was to analyse the biochemical composition of the matrix of these tumour entities in order to further characterise the cellular phenotypes of these neoplasms using typical cell biological marker genes. METHODS: The matrix compositions of chondroblastomas and chondromyxoidfibromas were analyzed by HE-histology, histochemistry, and immunolocalization techniques. Cellular gene expression patterns were detected by mRNA in situ hybridization. RESULTS: Chondroblastomas are rich in collagen type I and show foci of an osteoid-like matrix, whereas collagen type II as a typical marker of chondrocytic differentiation was not detected in any of the specimens. Chondromyxoidfiibromas had foci of chondroid appearance with chondroblastic cellular differentiation characterised by collagen type II expression. CONCLUSION: These results characterise chondroblastomas and chondromyxoidfiibromas as skeletal neoplasms that have a different biology and which can be distinguished by matrix protein expression products: collagen type II, the typical marker of chondroblast differentiation, could only be detected in chondromyxoidfibromas, but not in chondroblastomas. Thus, both neoplasms are clearly different on the cell biological level.     

Histochemical and contractile properties of striated muscles of urethra and levator ani of dogs and sheep

AIMS: To understand their possible importance in long- and short-term control of continence, some properties of the striated muscles of the urethra and pelvic floor (levator ani) of dogs and sheep were investigated, especially fiber types and contractile characteristics. MATERIALS AND METHODS: Striated muscles of urethra and levator ani of 29 male and 6 female dogs and 11 male and 6 female sheep were removed and cut into strips. Some strips were frozen and stained for ATPase at pH 9.4 and 4.3 for fiber typing; others were set up in an organ bath to study contractile responses to nerve stimulation. RESULTS: All muscles contained both type I (slow) and type II fibers, ranging from 97% type II in female greyhound urethra to 60% in female sheep levator ani. For each muscle, there were fewer type II muscles in sheep than in dog. The diameters of the urethral fibers were about 60% of the levator ani in dogs and 34% in sheep. Contraction of the urethral muscle was faster than for levator ani and declined to about 80% of the peak, 500 msec after the beginning of stimulation at 20 Hz. The levator ani contraction rose to a steady level as long as stimulation continued. CONCLUSIONS: Both the levator ani and urethral striated muscles contain slow and fast fiber types. The levator ani muscles are capable of sustained contraction with rapid onset which will produce long-term closure of the urethra. The circular urethral muscle contraction was faster but less well maintained.     

Effect of smoking and abstention on oxidative burst and reactivity of neutrophils and monocytes

BACKGROUND: Smoking is associated with surgical wound infections, impaired wound healing, and tissue-destructive disorders. The mechanisms are largely unknown, but changes in the function and activity of inflammatory cells may be involved. METHODS: Seventy healthy volunteers (54 smokers and 16 never smokers) were included. The smokers were studied while they smoked and after 20 days of abstinence. After the first 10 days of abstinence, they were randomized to double-blind treatment with transdermal nicotine patch 25 mg per day or placebo. Venous blood neutrophils and monocytes were sampled and isolated. In 22 randomly selected smokers and in all never smokers, the oxidative burst and chemotaxis were determined by a chemiluminescence response assay and a modified Boyden chamber technique, respectively. Stimulants were opsonized zymosan, formyl-Met-Leu-Phe, and zymosan-activated serum. RESULTS: The neutrophil and monocyte oxidative burst was 50% and 68% lower, respectively, in smokers compared to never smokers (P < .05). Neutrophil chemotaxis was 93% higher in smokers (P < .05). Monocyte chemotaxis was lower in smokers compared to never smokers (P < .05). After 20 days of abstinence, neutrophil oxidative burst increased to the level of never smokers (P < .05); monocyte oxidative burst increased by 50% (P < .05). Chemotaxis was only marginally affected. The changes induced by abstinence were less pronounced in the transdermal nicotine patch group compared to the placebo group. CONCLUSIONS: Smoking attenuates the oxidative burst of inflammatory cells and increases chemotaxis. Three weeks of abstinence normalize the oxidative burst, but affect chemotaxis only marginally.     

Incorporation and release of85Sr and14C-proline-hydroxyproline in mineral and collagen of bone and incisor teeth of growing rats

The extent to which exchange and reutilization processes of mineral tracers affect skeletal mineral accretion and resorption measurements was evaluated by comparing the rates of appearance and disappearance of⁸⁵Sr and¹⁴C-proline-hydroxyproline in bones and teeth in growing rats for 12 days following simultaneous parenteral injection of these tracers. Expressions for the relative rates of collagen synthesis and breakdown, which unlike mineral metabolism are considered not to be complicated by exchange phenomena, were based on¹⁴C-proline conversion to¹⁴C-hydroxyproline; the specific activity of the latter was determined. Both the mineral and the collagen specific activities reflected the rates and patterns of growth of the samples assayed; rapid growth and a short interval of time between formation and resorption of tissue in themetaphyseal bone which contains the cartilagineous growth plate, slow growth and an interval of time between formation and resorption of tissue indiaphyseal bone and incisor teeth which is longer than the 12 days of the experiment. However, in metaphyseal bone the specific activity collagen/mineral ratio dropped by one half during the 4–12 day interval in contrast to diaphyseal bone and incisor teeth in which no change in this ratio was observed during this period of time. The data indicate that collagen in the metaphyseal growth zone is removed by resorption before it has become fully mineralized, and that exchange is a relatively unimportant factor in the long term kinetics of bone mineral.

---

Zusammenfassung Das Ausmaß, bis zu welchem Austausch- und Wiederverwendungsprozesse der mineralen Tracer die Messungen des mineralen Skelett-Auf- und Abbaues beeinflussen können, wurde ausgewertet; zu diesem Zweck wurde die Geschwindigkeit des Auftretens und Verschwindens von⁸⁵Sr und von¹⁴C-Prolin-Hydroxyprolin in Knochen und Zähnen von wachsenden Ratten während der 12 auf die simultane parenterale Injektion dieser Tracer folgenden Tage verglichen.Der Ausdruck für die relative Geschwindigkeit des Kollagen-Auf- und Abbaues, bei welchem im Gegensatz zum Mineralmetabolismus kein Mitwirken des Austauschphänomens vermutet wird, basiert auf der Umwandlung von¹⁴C-Prolin zu¹⁴C-Hydroxyprolin; die spezifische Aktivität des letzteren wurde bestimmt.Aus der spezifischen Aktivität des Minerals sowie jener des Kollagens konnten die Geschwindigkeit und die Art des Wachstums der untersuchten Proben ersehen werden, d.h.schnelles Wachstum und ein kurzes Zeitintervall zwischen Bildung und Resorption des Gewebes imKnochen der Metaphyse, die auch die knorpelige Wachstumsplatte enthält, und andererseitslangsames Wachstum und längeres Zeitintervall (länger als die 12 Tage des Experimentes) zwischen Bildung und Resorption des Gewebes imKnochen der Diaphyse und in den Schneidezähnen. Immerhin fiel die spezifische Aktivität des Kollagen/Mineral-Anteils im Knochen der Metaphyse während dem 4–12tägigen Zeitintervall auf die Hälfte, im Gegensatz zum Knochen der Diaphyse und der Schneidezähne, bei welchen während dieser Zeitspanne kein Unterschied in diesem Verhältnis beobachtet wurde.Diese Ergebnisse zeigen, daß Kollagen in der Wachstumszone der Metaphyse durch Resorption verschwindet, bevor es ganz mineralisiert ist, und daß der Austausch ein relativ unwichtiger Faktor in der Kinetik auf lange Sicht des Knochenminerals ist.

     

Quality of life and cognitive and functional performance of octogenarians and nonagenarians undergoing hemodialysis

International Urology and Nephrology - To evaluate the quality of life, cognitive and functional capacity of older adult patients undergoing hemodialysis who are 80&nbsp;years of age or older...     

Use of bisphosphonates and raloxifene and risk of deep venous thromboembolism and pulmonary embolism

Summary  

Prior studies have associated raloxifene and strontium ranelate with deep venous thromboembolism and pulmonary embolism. In a cohort study, we observed an increased risk also with the bisphosphonates. However, the increase was present already before the start of bisphosphonates pointing at an effect of the underlying condition.     

Instrumented ligamentotaxis and stabilization of compression and burst fractures of dorsolumbar and mid-lumbar spines

Background:

Controversy continues regarding the best treatment for compression and burst fractures. The axial distraction reduction utilizing the technique employing the long straight rod or curved short rod without derotation to reduce fracture are practised together with short segment posterolateral fusion (PLF). Effects of the early postoperative mobilization without posterolateral fusion on reduction maintenance and fracture consolidation were not evaluated so far. The present prospective study is designed to assess the effectiveness of i) reduction and restoration of sagittal alignment, ii) no posterolateral fusion on the reduced, fractured vertebral body and injured disc, iii) fracture consolidation and iv) the fate of the unfused cephalad and caudal injured motion segments of the fractured vertebra.

Materials and Methods:

The study includes 15 Denis burst and two Denis type D compression fractures between T₁₂ and L₃. The lordotic distraction technique was used for ligamentotaxis utilizing the contoured short rods and pedicle screw fixator. Three vertebrae including the fractured one were fixed. The patients after surgery were braced for ten weeks with activity restriction for 2-4 weeks. The patients were evaluated for change in vertebral body height, sagittal curve, reduction of retropulsion, improvement in neural deficit. The unfused motion segments, residual postoperative pain and bone and metal failure were also evaluated.

Results:

The preoperative and postreduction percentile vertebral heights at, zero (immediate postoperative), at three, six and 12 months followup were 62.4, 94.8, 94.6, 94.5 and 94.5%, respectively. The percentages of the intracanal fragment retropulsion at preoperative, and postoperative at zero, 3, 6 and 12 months followup were 59.0, 36.2,, 36.0, 32.3, and 13.6% respectively.The preoperative and postreduction percentile loss of the canal dimension and at zero, three, six and 12 months were 52.1, 45.0, 44.0, 41.0 and 29% respectively suggesting that the under-reduced fragment was being resorbed gradually by a remodeling process. The mean initial kyphosis of 33° became mean 2° immediately after reduction and mean 3° at the final followup. The fractured vertebral bodies consolidated in an average period of ten weeks (range 8-14 weeks). The restored disc heights were relatively well maintained throughout the observation period. All paraparetic patients recovered neurologically. There were no postoperative complications.

Conclusion:

Instrument-aided ligamentotaxis for compression and burst fractures utilizing the short contoured rod derotation technique and the instrumented stabilization of the fractured spine are found to be effective procedures which contribute to the fractured vertebral body consolidation without recollapse and maintain the motion segment function.     

Physiology and pharmacology of nausea and vomiting

Nausea and vomiting are both very unpleasant experiences. The physiology is poorly understood; however, understanding what we do know is key to tailoring a preventative or therapeutic antiemetic regime. There are two key sites in the central nervous system implicated in the organization of the vomiting reflex: the vomiting centre and the chemoreceptor trigger zone. There are five key neurotransmitters involved in afferent feedback to these areas. These are histamine (H₁ receptors), dopamine (D₂), serotonin (5-HT₃), acetyl choline (muscarinic) and neurokinin (substance P). Postoperative nausea and vomiting will occur in around one-third of elective patients who have no prophylaxis. This can result in many detrimental effects including patient dissatisfaction, unplanned admission and prolonged recovery. It is therefore essential that clinicians understand how they can prevent and treat nausea and vomiting using either a single agent or a combination of antiemetics to target relevant receptors. Commonly used drugs include antihistamines, dopamine antagonists, serotonin antagonists and steroids. More novel agents are being developed such as aprepitant, a neurokinin receptor antagonist, palonosetron, a 5HT₃ receptor antagonist and nabilone, a synthetic cannabinoid.     

Physiology and pharmacology of nausea and vomiting

The physiology of nausea and vomiting is poorly understood. The initiation of vomiting varies and may be due to motion, pregnancy, chemotherapy, gastric irritation or postoperative causes. Once initiated, vomiting occurs in two stages, retching and expulsion. The muscles responsible for this sequence of events are controlled by either a vomiting centre or a central pattern generator, probably in the area postrema and the nearby nucleus tractus solitarius. Drugs which induce vomiting include ipecacuanha, a gastric irritant, and apomorphine, a dopamine-receptor agonist. Opioid drugs also induce vomiting, but opioid antagonists are not useful to treat nausea and vomiting. Anti-emetic drugs consist of a variety of neurotransmitter antagonists and may act in the periphery, the central nervous system or both sites. The most important drugs are antagonists at muscarinic, dopamine D₂, 5-HT₃, histamine H₁ and neurokinin NK₁ receptors. These drugs are discussed with particular attention to post-operative nausea and vomiting (PONV).     

���׼�������������

诺贝尔奖获得者Ｆｅｙｎｍｅｎ早在 195 9年就指出 ,在设定的空间内人们可以利用特定的技术逐个原子地制造物质。 1984年Ｇｌｅｉｔｅｒ等[1] 首次用惰性气体蒸发原位加热成功制备具有清洁表面的纳米材料。目前 ,人们正广泛地探索新型纳米材料 ,系统研究纳米材料的性能、微观结构、谱学特征及应用前景 ,取得了大量具有理论意义和重要应用价值的结果。纳米材料已成为材料科学和凝聚态物理领域中的热点 ,是当前国际上的前沿研究课题之一。现将纳米技术在肿瘤防治方面的研究进展作一介绍。1　纳米的相关概念和特征纳米是一种长度单位 ,1纳米 (…