Gastrointestinal absorption of metallic mercury

The absorption of mercury from the gastrointestinal systems of 7 subjects, of whom none had any amalgam fillings, was examined in this study. The authors obtained quantitative information about mercury concentration in plasma and duodenal fluid after the gastrointestinal systems of the subjects were exposed to liquid elemental mercury enclosed in rubber balloons (i.e., approximately 20 g of mercury), using a standard procedure followed for the sampling of bile. Plasma samples were collected prior to exposure, as well as up to 10 d following exposure, and duodenal fluid was collected 1 h, 2 h, 4 h, and 6 h during the intubation process. The authors studied the kinetics of dissolution in vitro by leaching elemental liquid mercury and mercuric chloride. The results of this study supported the hypothesis that metallic mercury is oxidized in the gastrointestinal tract. In addition, the authors determined that duodenal intubation, while using liquid metallic mercury in rubber bags, resulted in the diffusion of minor amounts of atomic elemental mercury through the rubber walls. The absorbed amount of mercury that reached the central circulation was comparable to a daily dose of mercury from dental amalgam in the amalgam-bearing population.     

Exposure and injury risk in Swedish elite football: a comparison between seasons 1982 and 2001

The long-term development of injury risk in Swedish male elite football was studied. Two prospective cohort studies from seasons 1982 and 2001 were compared with respect to exposure to football, injury incidence and injury severity. The mean number of training sessions during the season had increased by 68% between 1982 and 2001 (142 vs. 238, P<0.001), whereas teams played more matches in 1982 (49 vs. 41, P=0.02). The total exposure to football had increased by 27%. Three out of four players incurred an injury in both seasons. In 2001, players suffered more training injuries due to an increased training exposure. Accounting for risk exposure, there was no difference in injury incidence or severity between the two seasons. The incidence was 8.3 injuries/1000 h of total exposure (4.6 in training and 20.6 in matches) in 1982, compared to 7.8/1000 h-1 (5.2 in training and 25.9 in matches) in 2001. Major injuries accounted for 9% of all injuries, corresponding to an incidence of 0.8/1000 h of football, in both seasons. A trend from semi-professionalism to full professionalism in Swedish elite football was seen during the last two decades. The injury risk did not change over the same period.     

Two and a half-year outcome of caries-preventive programs offered to groups of children in the Solntsevsky district of Moscow

This study examined the 2.5-year outcome of preventive programs - based on the Nex? method - offered to three groups of children from Solntsevsky, a district of Moscow. Study group A consisted of 45 3-year-olds, study group B of 50 6-year-olds, and study group C of 50 11-year-olds. A similar number of children were selected as control groups and they followed the normal dental service provided by the local Health Service System in the district. The caries-preventive programs offered to the study groups were based on: (1) education of the child, parents and teachers in the caries disease, (2) training in toothbrushing. In addition, the children in study groups B and C were offered professional plaque removal, applications of sodium fluoride (2%) and sealant applications according to individual needs. The children in groups B and C were clinically examined in March 1994 (baseline) after 1 and 2.5 years, respectively. Because of the age of the children in group A, these children were only examined once, after the study had been completed. After 2.5 years the children in all three study groups had improved their oral health status significantly compared to the children in the control group. The caries experience among the children in study group A was about half of that observed among children in the control group (4.91 def-s versus 8.60 def-s). The program was highly effective in controlling dental caries in the permanent dentition among the children in the study groups, who finished with a mean DMF-S of 0.28 (group B) and 3.12 (group C) compared to 2.24 and 6.35 among the children in the corresponding control groups. Nearly all the children used fluoridated toothpaste. The mean number of visits to the clinic decreased from year 1 to year 2 (5 versus 3.4 in study group B and 4.5 versus 3.3 in study group C). In conclusion, the preventive programs were highly effective with regard to improving the level of oral hygiene, and thereby reducing or even controlling the plaque-induced disease activity.     

基因芯片技术在脑损伤研究中的应用

基因芯片技术是最近发展起来的新兴分子生物学技术,它的并行处理特点使大规模研究脑损伤后的基因改变成为切实可能。本文综述了新近用基因芯片技术在脑损伤后基因表达时序性改变及基因表达谱分析等研究中的应用。     

Results of randomized controlled trials of low-versus high-osmolality contrast media

The authors reviewed 100 randomized controlled trials (RCTs) conducted in humans to compare safety or efficacy of new low-osmolality contrast media (LOM) with that of high-osmolality contrast media (HOM). Findings of the 43 RCTs judged to be of the highest quality suggest that the efficacy of LOM in imaging is equal or superior to that of HOM for all routes of administration. Heat sensation occurred less often with LOM for all routes and pain occurred less often with LOM for intraarterial routes. No differences were seen in nephrotoxicity or in frequency of nausea, vomiting, urticaria, bronchospasm, laboratory test abnormalities, or neurologic events. Greater cardiovascular changes were seen with HOM, including increased or decreased heart rate, increased left ventricular end-diastolic pressure, decreased systolic pressure, and QT prolongation, depending on route of administration. To demonstrate whether a reduction in clinically significant adverse outcomes truly occurs with LOM, trials will need to enlist larger numbers of patients and employ appropriate outcome measures. Future trials should stratify patients according to their risk of adverse reactions to provide better information about benefits of LOM in low- versus high-risk patients.     

Isthmic spondylolysis of the lumbar spine: MR imaging at 1.5 T

The appearance on magnetic resonance (MR) images of the normal pars interarticularis in 13 patients was reviewed and contrasted with that of the pars in eight patients with spondylolysis. The pars defect usually had an intermediate signal intensity with all pulse sequences; however, this intensity was somewhat variable depending on the exact ratio of cartilage, fat, and fluid within each bone defect. The pars defect was best seen with spin-echo 600/20 (repetition time msec/echo time msec) images. In three cases, out-of-phase images showed the spondylolysis best, because of extension of fat to the borders of the defect. The sagittal view allowed one to separate spondylolysis from the joint space of posterior facets since the orientation of the defects is perpendicular to the facets; thus, a common pitfall encountered with cross-sectional axial imaging techniques is avoided. MR imaging poorly delineated bone fragments around the defect, which may produce nerve root impingement, but revealed other numerous complications that occur with spondylolysis, including spondylolisthesis and herniation of the disk above.     

Transabdominal versus endovaginal pelvic sonography: prospective study

Transabdominal and endovaginal pelvic sonograms were obtained in 108 nonpregnant patients referred for pelvic sonography. The studies were independently obtained by two radiologists and interpreted on the basis of identical clinical information. The sonograms were then compared for anatomic detail and abnormalities. A determination was made about which examination, if either, was superior. Follow-up was performed through a review of the medical records and follow-up studies. Overall, the endovaginal study was judged superior in 65 cases (60.2%), equal in 39 (36.1%), and inferior in four (3.7%). The authors conclude that the endovaginal examination can effectively replace the transabdominal examination as the initial approach for routine pelvic sonography.     

Morphometric analysis of occlusal groove-fossa-system in mandibular third molar

Based on serially cut 200-microns-thick sections from 21 human mandibular third molars, a quantitative characterization was made of the morphology in the mesial and distal interlobal groove. Two parameters were used: depth of interlobal groove and structure angle. The interlobal groove depth varied between 0.13 and 0.55, taken in relation to the maximum crown height. The structure angle varied between 2 degrees and 170 degrees. If the structure angle was less than or equal to 25 degrees, the interlobal groove was classified as a fissure; if the angle was greater than 25 degrees, the interlobal groove was classified as a groove. Only in 18% of the sections did the interlobal groove manifest itself as a fissure. The study demonstrates that it was possible unambiguously to describe the two-dimensional profile of interlobal grooves by groove depth and structure angle.     

Light and transmission-electron microscopy study of enamel organ cells in germectomized human third mandibular molars.

Using nine serially sectioned germectomized mandibular third molars it was possible to examine light microscopical (LM) and transmission-electron microscopical (TEM) features of maturing human enamel organ cells. The degree of enamel mineralization was estimated by quantitative imbibition studies in polarized light. It was possible to distinguish between three progressive stages of enamel mineralization. The most advanced stage was characterized by external enamel porosity. In the least advanced stages the enamel porosity appeared more extensive beneath a less porous surface layer. Ruffle- and smooth-ended ameloblasts were identified corresponding to the maturing enamel. Smooth-ended ameloblasts were the most frequently observed. However, no preferences for one of the two cell types could be observed in relation to the different stages of enamel mineralization. The maturing human enamel organ cells broadly revealed the same characteristics with respect to morphology features, intracellular organization, and junctional complexes as described in the maturation zone of the rat incisor enamel organ. Our findings therefore add to the view that the basic pattern of amelogenesis is identical in human and rat incisor enamel.