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.     

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.     

Single visit root canal treatment: incidence of postoperative pain using three different instrumentation techniques

A clinical study was carried out on nonvital maxillary central incisors to evaluate the incidence of postoperative pain following single-visit root canal treatment using three different instrumentation techniques. Ninety teeth from 78 patients whose ages ranged from 14 to 63 years were selected and divided into three groups. Each group (30 teeth) was prepared by a different coronal-to-apical technique using different instrument movement depending upon the technique employed: modified double-flared, crown-downpressureless and balanced force techniques. No difference was observed in the incidence of postoperative pain among the groups.     

The relation between conduction velocity and axonal length

Motor evoked potentials (MEPs) obtained by electrical root stimulation and F waves were used to examine the proximal nerve conduction velocity (CV) to tibialis anterior (TA), extensor digitorum brevis (EDB), flexor carpi radialis (FCR), and abductor pollicis brevis (APB) muscles in 40 humans. By subtracting motor latencies obtained by stimulating the peripheral nerve at the same point from the F-wave and MEP latencies, we could measure the CV over identical proximal segments. It was found that proximal CV to TA and FCR was significantly higher than to EDB and APB, respectively. Combining the data of the proximal CV to all four muscles in relation with axonal length resulted in a highly significant inverse relationship (r² = 0.77). Thus the axonal length explained to a large extent the higher CV of the arm nerves and also the inverse relation between body height and CV. The distal CV was always lower than proximal CV; however, there was no support for an additional effect of this gradient in explaining the relationship between CV and height since it was constant for all body heights. © John Wiley & Sons, Inc.     

鸡后根神经节多巴胺细胞在体及体外培养中的免疫细胞化学观察

应用免疫细胞化学PAP法,研究了鸡胚和雏鸡后根神经节细胞内多巴胺递质的表现与胚胎发育过程中的变化,并在细胞培养条件下研究了周围靶组织——皮肤对后根节细胞胚胎发育的影响。鸡后根节细胞内多巴胺的免疫反应最先出现于E_(10),只占后根节细胞的0.8%,E_(18)时达5.6%,出壳后雏鸡为8.6%。在鸡后根节内,多巴胺免疫反应阳性细胞主要为较大的A类细胞,和极少较小的B类细胞。免疫反应阳性的周围神经末梢位于皮肤和交感干内。当取自E_9的鸡胚后根节细胞经7天培养后,部分神经细胞出现多巴胺免疫反应阳性;而取自E_6的鸡胚后根节细胞虽经10天培养后仍为免疫反应阴性;然而,将取自E_6后根节细胞与皮肤组织联合培养10天后,少量神经细胞及轴突出现多巴胺免疫阳性反应。作者认为:鸡后根节多巴胺细胞在胚胎时期的发育有赖于周围靶组织的作用。     

非悬滴开放式培养法在鸡胚背根节体外培养中的应用

本研究针对悬滴培养法在操作和应用上存在的问题和局限性，改用操作简便、适用范围广的非悬滴开放式培养法培养鸡胚背根节。将数个鸡胚背根节按一定间隔种植在内置生长基质盖玻片的35mm培养皿中，加人适量培养液，置于CO2。孵箱中进行培养。结果显示.从培养24h至60h各时期，培养皿中背根节生长状况均良好，神经突起明显增长，表明用非悬滴开放式培养法培养鸡胚背根节是可行且可靠的。     

Separation of temperature sensitive and temperature insensitive components of the postsynaptic potentials in the frog motoneurons

Intracellular measurements were made in the in situ spinal cord of the frog at temperatures below 5 degrees C. Responses to volleys in the sciatic nerve, in the descending fibres and in the motor axons were studied. About 30% of the motoneurons responded to sciatic volleys with 1-3 ms segmental latency, which was short enough to assume electrotonic mediation of these responses. Another group of motoneurons responded with 6-8 ms latency, i.e. with the expected delay at chemical synapses at low temperature. Latency distribution of the sciatic-evoked postsynaptic potentials was clearly bimodal in contrast with that found at higher temperatures. Postsynaptic discharges occurred with rather long latency and they were attributed to chemically-mediated excitation. Some of the postsynaptic potentials to descending volleys also occurred with quite short latency, indicating possible electrotonic transmission from supraspinal centres to motoneurons. Latency distribution of the action potentials evoked from the motor axons was bimodal, corresponding to the different, i.e. antidromic and recurrent facilitatory, mechanism of these spikes. Calculated Q10 ratios for the sciatic-evoked reflex discharges and the afferent fibre volleys were about 2.3 and 1.8, respectively. We concluded that cooling helps to separate postsynaptic potentials according to their electrotonic and chemical mediation and that electrotonic excitation does not seem to have a primary role in the generation of postsynaptic discharges initiated by dorsal root volleys in the frog.     

Cervical tissue uptake of all-trans-retinoic acid delivered via a collagen sponge-cervical cap delivery device in patients with cervical dysplasia

The present study was undertaken to evaluate the systemic absorption and cervical tissue uptake of all-transretinoic acid (TRA), delivered via a collagen spongecervical cap delivery device in patients with intraepithelial cervical dysplasia. Ten patients with histologically proven mild or moderate cervical dysplasia were included in this pharmacologic study. The two TRA concentrations (0.05% and 0.372%) selected for study represent the starting and maximally tolerated doses used in phase I clinical trial. All-trans-retinoic-11-³H acid (³H-TRA, 500 Ci) was used to facilitate cervical tissue uptake studies. Cervical biopsies and post-treatment blood samples were obtained from each patient after TRA exposure. The uptake of TRA into cervical tissues four hours after drug administration was significantly increased at the maximally tolerated TRA dose. There was a rapid decrease in cervical tissue concentration of TRA at the 0.372% dose between 4 and 24 h after drug exposure, suggesting a relatively short elimination half-life of TRA in cervical tissues. HPLC analysis of post-treatment blood samples indicate that there was no systemic absorption of TRA after local cervical administration.     

Non-adenomatous colorectal polyposis syndromes

Gastrointestinal polyps are common lesions that usually present singly or in small numbers. Although the term ‘multiple colorectal polyposis’ was originally applied to patients carrying at least 100 large intestinal adenomas, it has subsequently become broadened to include patients carrying multiple polyps regardless of their nature. Most of the non-adenomatous polyposis syndromes are hereditary. They can be classified according to the dominant type of polyp, their distribution in the gastrointestinal tract and their potential for the development of gastrointestinal cancers. This review summarises their main clinical, genetic and histopathological features.     

假鹰爪化学成分研究(Ⅱ)

目的：寻找番荔枝科假鹰爪属植物假鹰爪Ｄｅｓｍｏｓ ｃｈｉｎｅｎｓｉｓ抗肿瘤活性成分。方法：采用硅胶柱色谱分离化学成分。根据理化性质及波谱分析等方法鉴定结构。结果：从氯仿萃取物中分离鉴定了７个化合物,分别是ｕｎｏｎ－ａｌ（Ⅰ）,黄芩素－７－甲醚（Ⅱ）,去甲氧杜鹃花素（Ⅲ）,去甲氧杜鹃花素－７－甲醚（Ⅳ）,苯甲酸（Ⅴ）,β－谷甾醇（Ⅵ）和豆甾醇（Ⅶ）。结论：该种植中鉴定的黄酮类化合物均为β－环未取代,