The spacing of rhesus monkey troops changes when a few group members receive delta 9THC or D-amphetamine

Free ranging troops of 18--25 rhesus macaques were housed in large enclosures where a few higher-ranking monkeys were given psychotropic agents (delta 9THC: 4 mg/kg or d-amphetamine: 2 mg/kg). Measures of group spacing were (1) mean distance between all animals. (2) daily variance in mean distance, (3) nearest neighbor distance, (4) daily variance in nearest neighbor distance, (5) index of clumping (S2/mean ratio), (6) % touching, and (7) % movement/2 sec. When 3--4 animals were drugged, the entire group moved closer together and distances were more variable. Acute changes after the first week of delta 9THC and effects after delta 9THC withdrawal were seen in two experiments. Chronic behavioral changes were found for d-amphetamine and in one delta 9THC experiment.     

Influence of preparation design and spacing parameters on the risk of chipping of crowns made with Cerec Bluecam before cementation

Purpose

To evaluate the influence of the preparation design and spacing parameters on the risk of chipping of crowns made by CEREC Bluecam before cementation.

水凝胶在肿瘤放射治疗中的间隔与保护作用研究进展

放射治疗是肿瘤治疗的主要方法之一, 但周围的健康组织由于也受到一定剂量的照射, 可能造成放射性损伤, 甚至个别患者程度较为严重。可注射的水凝胶有望通过将邻近器官与肿瘤部位实现"间隔(Spacing)", 提高靶区的放射剂量, 降低放疗期间周围健康组织和器官受到辐射损伤的风险, 从而提高患者的生存质量, 是降低放疗相关不良反应潜在的有效治疗策略。本文对水凝胶在不同肿瘤放射治疗中发挥间隔和保护作用的最新进展进行综述。     

Descriptive epidemiology of dental malocclusion in Najran patients seeking orthodontic treatment

BackgroundUntreated malocclusion can lead to compromised aesthetic function, depression, and low self-esteem. The aim of this study was to evaluate dental malocclusion in Najran, Saudi Arabia as no data existed before.MethodThis was a retrospective study analyzing the casts of all patients in Najran, Kingdom of Saudi Arabia, seeking orthodontic management for malocclusion between 2017 and 2019.MeasurementsThe consultant orthodontist is the single investigator involved in collecting the details of demographics followed by molar relationships, overjet, overbite, crowding and spacing using digital caliper on each dental cast. Data were analyzed using IBM SPSS Statistics for IOS Version 25 (Armonk, NY: IBM Corp.ResultsA total of 326 patients sought treatment for different types of malocclusion. There were 143 males and 183 females with an M:F ratio of 1:1.3. Age ranged from 6 to 55 years with a mean SD of 22.6 ± 8.98. The prevalence for Class I, II and III malocclusions at 95% CI was (0.76 (0.757, 0.774)), 0.251 (0.243, 0.260) and 0.529 (0.519, 0.539) respectively. Fifty-one (15.6%) patients had reversed overjet, 65 (19.9%) reduced overjet, and 86 (26.4%) increased overjet. One hundred and sixty-four (50.3%) cases of reduced overbite and 99 (30.4%) cases of deep overbite were also observed. Tooth size arch length discrepancy were noticed with crowding and spacing in 83 (26.4%) and 71 (21.8%) patients, respectively.ConclusionsThis study has shown the prevalence of Class I, Class II, and Class III malocclusion to be 72.7%, 11.6% and 15.6% respectively. Increased over jet and crowding was demonstrated in more patients, though it is not statistically significant.     

引导电极间距对蟾蜍坐骨神经干动作电位时程的影响

目的:研究引导电极间距对蟾蜍坐骨神经干动作电位(AP)时程的影响。方法:采用细胞外记录法,记录和观察不同间距的引导电极引导动作电位的时程变化。结果:引导电极间距从5mm增加到35mm时,能显著延长负相波和正相波的时程(P0.05)。结论:在一定范围内,增大引导电极间距,双相动作电位负相波和正相波时程均延长,而且负相波和正相波时程要达到最大,所需的电极间距是一样的。     

Therapeutic strategy for rheumatoid arthritis patients who have achieved remission

Once remission or low disease activity (LDA) is attained in established rheumatoid arthritis (RA) patients, attempting disease-modifying anti-rheumatic drug (DMARD) tapering appears to be a viable option to avoid patient overtreatment. Potential benefits include reduction in the treatment burden and the risk of adverse events, although the latter has not been demonstrated convincingly. The feasibility of DMARD discontinuation has been tested in numerous studies or trials. All have revealed a high risk of relapse, ranging from 56%–87% at one year. Although remission/LDA can usually be re-established by re-initiation of the previous treatment, the associated risk appears to be more harmful than beneficial. DMARD tapering, either by dose reduction or by injection spacing, is conceptually more acceptable and two superiority randomized controlled trials (RCTs) comparing half-dose etanercept to full-dose continuation demonstrated no significant difference at one year. By contrast, two equivalence RCTs that tested disease activity-guided dose optimization by progressive etanercept and adalimumab injection spacing versus continuation revealed an increased risk of acute flare. Interestingly, one of these also demonstrated the equivalence of increasing injection spacing and standard of care in terms of recurrent flare and overall disease activity over the 18-month follow-up period. The risk of structural damage progression was minimal or null. Reintroduction of DMARD at the previous dose was associated with remission being achieved in the majority of patients who flared. Tapering strategies that adhere to the Tight Control and Treat-to-Target principles appear to be suitable options for RA patients who have achieved sustained remission or low disease activity.     

Cellular basis for volume related wall thickness changes in the rat left ventricle

Nine arrested rat hearts fixed by glutaraldehyde perfusion of the coronary arteries were studied in vertical cross-sections of the left ventricle by phase contrast microscopy. The number of fibers per unit area in the wall and the number of fibers between the epicardium and endocardium were measured and correlated with ventricular volume and wall thickness. Average center to center fiber separation was derived from these measurements.Increasing ventricular volume is associated with a decrease in wall thickness and fiber diameter which follows theoretical predictions. The relationship between these measurements, however, presents a dimensional paradox in that the decreases in wall thickness are 3 to 4 times greater than the decrease observed in separation of fiber centers. Thus, an increase in fixation volume from 0.03 to 0.60 ml results in a 68% decrease in wall thickness, while center to center fiber separation decreases only 20%. Changes in wall thickness are therefore mainly accounted for by internal rearrangement of the disposition of fibers composing the ventricular wall. A mechanism for such rearrangements is illustrated by low magnification cross-sections of the ventricular wall which demonstrate open spaces or sliding planes between groups of muscle fibers. A volume related alteration in the orientation of these sliding planes is noted.     

Learning and interlimb transfer of new gait patterns are facilitated by distributed practice across days

BackgroundPrevious studies have shown that the extent to which learning with one limb transfers to the opposite, untrained limb (i.e., interlimb transfer) is proportional to the amount of prior learning (or skill acquisition) that has occurred in the training limb. Thus, it is likely that distributed practice—a training strategy that is known to facilitate learning—will result in greater interlimb transfer than massed practice.Research questionTo evaluate the effects of massed and distributed practice on acquisition and interlimb transfer of leg motor skills during walking.MethodsForty-five subjects learned a new gait pattern that required greater hip and knee flexion during the swing phase of gait. The new gait pattern was displayed as a foot trajectory in the sagittal plane and participants attempted to match their foot trajectory to this template. Subjects in the massed practice group (n = 20) learned the task on a single day, whereas subjects in the distributed practice group (n = 25) learned the task that was spaced over two consecutive days (training phase). Following completion of training, subjects in both groups practiced the task with their untrained, opposite leg to evaluate interlimb transfer (transfer phase).ResultsResults indicated that the amount of skill acquisition (i.e., reductions in tracking error) on the training leg was significantly higher (P < 0.05) in the distributed practice group when compared with the massed practice group. Similarly, the amount of interlimb transfer was also significantly higher (P < 0.05) in the distributed practice group both at the beginning and end of the transfer phase.SignificanceThe findings indicate that acquisition and interlimb transfer of leg motor skills are significantly greater when the task was learned using distributed practice, which may have implications for gait rehabilitation in individuals with unilateral deficits, such as stroke.     

Stratégies d’arrêt ou de réduction des biomédicaments dans la polyarthrite rhumatoïde en rémission

The arrival of new drugs and new therapeutic strategies allowed to reach sustained remission in an increasing number of patients with rheumatoid arthritis. The study of biologic disease-modifying anti-rheumatic drugs (bDMARDs) adaptation strategies is a need to optimize the benefit/risk balance and cost/effectiveness ratio of these molecules. Current recommendations such as EULAR 2016 propose tapering bDMARDs, especially when combined with a csDMARD, when the patient is in remission after stopping persistent glucocorticoids. The analysis of literature comprising 22 studies shows that a bDMARD adaptation is possible in established rheumatoid arthritis when clinico-biological and ultrasound remission is maintained over six months. Priority should be given to a progressive tapering strategy doses controlled by disease activity while maintaining “tight control” to identify and effectively treat a relapse, a retreatment being usually favorable.     

Stimulus-driven incidental episodic retrieval involves activation of the left posterior parietal cortex

Recent reviews have highlighted the important role that the posterior parietal cortex (PPC) serves during episodic memory retrieval. A handful of studies have also noted that the PPC is active when old information is present on tasks that do not require overt episodic retrieval. Based on this observation, we examined whether incidental study-phase retrieval, cued by the repeated presence of stimuli, was sufficient to activate the PPC and whether this activation would be modulated by the lag between the initial and repeated presentation of those stimuli. Blood flow was measured with positron emission tomography (PET) while subjects classified pictures that were either new, repeated following a short lag, or repeated following a long lag. Activity in the left inferior parietal lobule (IPL, BA 40), amongst other regions, was greater for repeated than new pictures, and was greater following a long lag than a short lag, even though intentional retrieval was not required. These results suggest that the presence of repeated stimuli is sufficient to initiate left PPC mediated episodic retrieval.