Aortic root dilatation may alter the dimensions of the valve leaflets

Objective: Valve-sparing surgery can be used in patients with dilated aortic roots and aortic insufficiency (AI) but has not become a common practice, in part because the spared valve may be incompetent. Our goal was to study how the dimensions of the aortic root and leaflets have changed in such patients. Methods: Fourteen patients with dilated aortic root and AI were examined by transesophageal echocardiography. The annulus diameter, sinotubular junction (STJ) diameter, sinus height, leaflet free-edge length, and leaflet height were measured. Correlations among these dimensions and with the AI grades were explored. Measurements were also made in 19 normal human aortic valves from silicone molds. Results: There was no evident change in the average diameter of the annulus between the normal valves and those in the dilated aortic roots. The STJ diameter was obviously increased in the dilated aortic roots; the aortic sinuses also appeared to be taller and the leaflets larger than normal. The leaflet free-edge length, the leaflet height, and the sinus height were found to increase with the dilated STJ diameter. The degree of AI was not found to correlate well with any of the dimensions measured. Conclusions: The dimensions of the leaflets may change parallel to aortic root dilatation with AI. Therefore, during valve sparing, it may be necessary to correct both the dilatation of the root and the leaflet free-edge length to achieve a competent valve.     

Microcystin-LR affects cytoskeleton and morphology of rabbit primary whole embryo cultured cells in vitro

Microcystin-LR is the most frequently studied cyclic heptapeptide produced by different genera of cyanobacteria and is hepatotoxic to livestock and human populations. The adverse effects of microcystin-LR on morphology and cytoskeletal elements in different stages of early embryonal development have been studied in vitro. Embryos and whole embryo cultures have been exposed to microcystin-LR (10–100 μM). Actin filaments were visualized by fluorescence staining and the microtubular network labelled by immunostaining. Growth, development and cytoskeleton organization of the embryos embedded in zona pellucida are not affected by microcystin-LR in concentrations up to 100 μM, while whole embryo cell cultures are affected by the presence of microcystin-LR in the culture medium. High microcystin-LR concentrations (100 μM) cause cells to be detached and destroyed, while lower concentrations (10–20 μM) profoundly affect actin and microtubule organization. These effects are confirmed also by the presence of transformed microcystin-LR in all the media at the lowest concentrations. It seems that the changes to the cells are far more serious than that expressed in cell morphology. From our experiments we conclude that the presence of zona pellucida is an effective way of embryo protection against xenobiotics like microcystin-LR.     

Topical application of fluorides on teeth

Abstract Prevention of caries in exposed root surfaces constitutes an important clinical problem. It is thus important that clinicians involved with periodontology have an insight into fluoride prophylaxis. The understanding of the cariostatic mechanism of fluoride has improved during recent years. The aim of the present review is to give a short account of the present concept. Calcium fluoride appears to be the only product which is formed on enamel, dentin or cementum during brief topical treatments with fluoride or use of toothpaste containing fluoride. This calcium fluoride is stable in the oral environment: this is contrary to what was believed until recently. The calcium fluoride constitutes a pH-dependant reservoir of fluoride which releases fluoride when pH drops. The practical consequences of this concept is discussed.     

Differential effects of the pyrethroid tetramethrin on tetrodotoxin-sensitive and tetrodotoxin-resistant single sodium channels

The differential effects of the pyrethroid tetramethrin on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) single sodium channel currents in rat dorsal root ganglion (DRG) neurons were investigated using the outside-out configuration of patch-clamp technique. Channel conductances were 10.7 and 6.3 pS for TTX-S and TTX-R sodium channels, respectively, at a room temperature of 24–26°C. The single-channel current of TTX-S sodium channels at the test potential of −30 mV was −1.27 ± 0.25 pA, and was not changed after exposure to 10 μM tetramethrin (−1.28 ± 0.23 pA). The open time histogram of TTX-S single-channel currents could be fitted by a single exponential function with a time constant of 1.27 ms. After exposure to 10 μM tetramethrin, the open time histogram could be fitted by the sum of two exponential functions with time constants of 1.36 ms (τ_fast) and 5.73 ms (τ_low). The percentage of contribution of each component to the population was 62% for the fast component representing the normal channels and 38% for the slow component representing the tetramethrin modified channels. The amplitudc of TTX-R single-channel currents was slightly changed from −0.72 ± 0.14 to −0.83 ± 0.07 pA by 10 μM tetramethrin. The open time histogram of TTX-R single-channel currents could be fitted by a single exponential function with a time constant of 1.92 ms. In the presence of 10 μM tetramethrin, the open time histogram could be fitted by the sum of two exponential functions with time constants of 2.07 ms (τ_fast) and 9.75 ms (τ_slow). The percentage of contribution of each component was 15% for the fast, unmodified component and 85% for the slow, modified component. Differential effects of tetramethrin on the open time distribution of single sodium channel currents explains the differential sensitivity of TTX-S and TTX-R sodium channels.     

Concomitant intrusive luxation and root fracture of a central incisor - report of a case

Abstract A case of a 9-year-old boy who presented with intruded maxillary central incisors, one of which had also sustained a middle third root fracture, is reported. The root fracture was diagnosed after orthodontic extrusion was started, which resulted in separation of the apical and coronal fragments. The hypermobile coronal fragment was stabilised by passing a K file through a palatal access cavity into the root canal of the apical fragment. Orthodontic alignment was completed and the fractured incisors were restored with the file left in situ. At a 10-year follow-up, the incisors were clinically healthy and continued to satisfy aesthetic and functional demands.     

Abnormalities in visceral evoked potentials from the anal canal in children with chronic constipation

The integrity of the sensory nervous system in the anal canals of chronically constipated children was investigated using evoked potential techniques examining cerebral and spinal evoked potentials from the lower extremities and anal canal. Stimulation of the posterior tibial nerve produced no significant difference in the parameters of spinal and cerebral evoked potentials between 18 controls and 12 chronically constipated chidren. However, stimulation of the anal canal resulted in evoked potentials related to the age and/or consciousness level of the control children. Reproducible cerebral responses were obtained only from nine of these control children, all aged over 4 years, who were examined while awake without sedatives. A typical response was characterized by a polyphasic wave occurring with an onset latency of 79.4± 27.7ms (mean ±SD). In the 12 chronically constipated children, the 5 sedated patients examined while asleep did not show any reproducible potential, as in the controls. However, in the remaining 7 children examined while awake, the occurrence of the anal canal evoked potential was significantly reduced, and only two exhibited a cerebral response. These findings suggest that rectal mucosal perception of the intraluminal stimuli might be disturbed in some children with chronic constipation.     

经前路颈椎多节段椎管扩大术的实验研究

目的设计颈椎前路椎管扩大术式并探讨该术式的可行性,为颈椎管多节段狭窄症提供新的手术方法。方法标本实验:选用4具C1～T1尸体颈椎标本,去除前方肌肉,保留后侧肌肉及固有韧带,解剖出横突孔,沿椎动脉走行,穿入直径3mm橡胶管,注入造影剂。沿C4～6椎体前正中纵行劈开,依次横向撑开3、6、9、12mm,并用木块填塞,三维CT下观察椎管前后径、横径、截面积、两侧椎动脉的直径、间距,神经根管变化。动物实验:用4只成年绵羊,麻醉后暴露出C3,4颈椎前方,将C3,4椎体纵向劈开,横向撑开9mm,取同侧胫骨9mm×9mm×15mm骨块植入撑开区。术后观察四肢运动恢复情况。结果标本在撑开3、6、9mm后,椎管前后径平均增加1.14%、3.53%、5.15%,横径增加7.92%、14.62%、22.74%,截面积增加8.52%,17.99%,25.01%;在撑开3、6、9mm时,两侧椎动脉走行间距平行,撑开12mm时,在C3,4和C6,7椎间椎动脉间距相差2mm,但走行无折屈、受压。撑开前后神经根管各径及长度无变化。标本在撑开3、6、9mm时未见骨折,撑开12mm时2具左侧、1具右侧椎板靠近棘突部骨折,均为裂纹骨折,无移位。4只绵羊术后第2d四肢可以自由行走,无神经、血管损伤征兆。结论经前路颈椎体纵向劈开扩大术,可以增加椎管容积、不影响脊柱三柱稳定结构。动物实验表明椎体横向撑开一定范围内(≤9mm)对颈髓及周围组织无损伤迹象。实验结果初步证实经前路颈椎椎管扩大术安全有效。     

Transmission electron microscopy of early microbial colonization of human enamel and root surfaces in vivo

Abstract – This study describes the early microbial colomization of teeth by the use of light-and transmission electron microscopy. Six dental students carried a total of 60 test pieces of unerupted enamel and root surface in intraoral acrylic appliances for 4, 8, 12, 24 and 48 h, during which periods oral hygiene was abandoned. Pronounced variations were recorded in structure and thickness of the pellicle across the individual surfaces of both dental tissues. Bacterial single-cell colonization increased the electron density of the adjoining pellicle. Micro-colonies of bacteria were observed in relation to enamel surface irregularities such as perikymata, while the distribution on root surfaces appeared incidental. Root surfaces were generally colonized by thicker deposits than homologous enamel surfaces although the structural composition of the microbiota was similar. Gram-positive bacteria with thick cell walls appeared in coccoid or rod-shaped configurations depending on the age of the bacterial deposit. These bacteria were further characterized by selective invasion between collagen fibers. After 48 h the complexity of the microbiota was increased by the establishment of new bacterial species in the superficial layer. It is concluded that the pattern and composition of the early microbiota on teeth is more complex and variable than hitherto assumed.     

25例产道血肿及其预后的临床分析

目的：探讨产道血肿形成的病因，临床处理及预后。方法：选取2001年8月至2006年8月阴道分娩的4000例产妇，其中25例发生产道血肿，对其进行回顾性分析，通过分析其病因，临床处理及转归，对该病的预防，诊治经验和教训进行总结评价。结果：产道血肿的发生率为0．625％，经过积极有效的处理，25例发生产道血肿的产妇均痊愈。结论：分娩过程中，应仔细询问产妇病史，对存在有可能发生出血倾向的高危孕妇应严密观察，争取做到早发现；而已发生血肿的产妇，应针对不同病因早治疗，以改善产妇的预后。     

神经根变异与特殊型椎间盘突出症

回顾5例由于神经根变异或特殊类型椎间盘突出引起的腰腿痛病人,对其病理及术中处理做了介绍,认为由于神经根的解剖变异,更容易受到椎间盘突出的卡压。手术中如临床症状符合椎间盘突出症,而预定探查间隙未发现突出物,或与临床症状不符者,应根据神经根激惹及松紧程度,扩大探查范围,查明造成疼痛的原因,避免二次手术。