Interrelationships between Cellular Density,Mosaic Patterning,and Dendritic Coverage of VGluT3 Amacrine Cells

Amacrine cells of the retina are conspicuously variable in their morphologies, their population demographics, and their ensuing functions. Vesicular glutamate transporter 3 (VGluT3) amacrine cells are a recently characterized type of amacrine cell exhibiting local dendritic autonomy. The present analysis has examined three features of this VGluT3 population, including their density, local distribution, and dendritic spread, to discern the extent to which these are interrelated, using male and female mice. We first demonstrate that Bax-mediated cell death transforms the mosaic of VGluT3 cells from a random distribution into a regular mosaic. We subsequently examine the relationship between cell density and mosaic regularity across recombinant inbred strains of mice, finding that, although both traits vary across the strains, they exhibit minimal covariation. Other genetic determinants must therefore contribute independently to final cell number and to mosaic order. Using a conditional KO approach, we further demonstrate that Bax acts via the bipolar cell population, rather than cell-intrinsically, to control VGluT3 cell number. Finally, we consider the relationship between the dendritic arbors of single VGluT3 cells and the distribution of their homotypic neighbors. Dendritic field area was found to be independent of Voronoi domain area, while dendritic coverage of single cells was not conserved, simply increasing with the size of the dendritic field. Bax-KO retinas exhibited a threefold increase in dendritic coverage. Each cell, however, contributed less dendrites at each depth within the plexus, intermingling their processes with those of neighboring cells to approximate a constant volumetric density, yielding a uniformity in process coverage across the population.SIGNIFICANCE STATEMENT Different types of retinal neuron spread their processes across the surface of the retina to achieve a degree of dendritic coverage that is characteristic of each type. Many of these types achieve a constant coverage by varying their dendritic field area inversely with the local density of like-type neighbors. Here we report a population of retinal amacrine cells that do not develop dendritic arbors in relation to the spatial positioning of such homotypic neighbors; rather, this cell type modulates the extent of its dendritic branching when faced with a variable number of overlapping dendritic fields to approximate a uniformity in dendritic density across the retina.     

Digital surface scanning in flap perfusion

Monitoring vascular perfusion of transferred tissue is essential in reconstructive surgery to recognize early flap failure. The aim of this study was to evaluate the ability of a digital surface scanner to detect vascular perfusion disorders through the monitoring of skin colour changes. A total of 160 surface scans of the forearm skin were performed with a TRIOS 3D scanner. Vascular compromise was simulated at different time-points by intermittent occlusion of the blood supply to the forearm skin (first the arterial blood supply and then the venous blood supply). Skin colour changes were examined according to the hue, saturation, and value colour scale. Colour differences were analysed with a paired t-test. Significant differences were observed between the colour of the normal skin and that of the vascular compromised skin (P < 0.01). The surface scanner could distinguish between arterial occlusion and venous congestion (P < 0.01). A digital surface scan is an objective, non-invasive tool to detect early vascular perfusion disorders of the skin.     

Tissue tracking of segmental strain as a predictor of provoked dynamic left ventricular outflow tract obstruction

BackgroundLeft ventricular outflow tract obstruction (LVOTO) is commonly observed in patients with hypertrophic cardiomyopathy (HCM) or left ventricular hypertrophy (LVH). Some patients develop LVOTO provoked by physical exertion, and hence termed dynamic LVOTO (DLVOTO). However, its precise prevalence and mechanism are still unclear.AimTwo-dimensional speckle tracking echocardiography (2D STE) seems to be helpful for the detection of early LV structural abnormalities. This study aimed to examine the possible role of segmental as well as global longitudinal strain in identifying DLVOTO non-HCM patients as detected by dobutamine stress echocardiography (DSE).Methods and resultsTwo hundred and fifty patients without structural heart disease had undergone conventional transthoracic echocardiography, 2D STE, and DSE. All patients with non-ischemic evidence were divided into two groups according to the DSE results; DLVOTO (+) and DLVOTO (?).Among 250 patients, 50 patients (36%) had shown DLVOTO after DSE (15 males, 35 females; mean age 55±7years). They were compared with 90 non -LVOTO obstruction patients (43 males, 47 females; mean age 57±6years). Based on multivariate logistic regression analysis, the independent predictors of provoked DLVOTO during DSE were resting basal septal longitudinal strain BS-LS _average (p < 0.001), resting LA reservoir strain (p < 0.001), and systolic LVOT diameter (p = 0.03). Resting BS-LS _average with cut-off - 17.5% was recognized as a critical indicator of DLVOTO, with sensitivity 78%, and specificity 95% (better than systolic LVOT diameter of sensitivity 76%, and specificity 15% and resting LA reservoir strain which showed poor AUC at ROC curve 0.007).ConclusionWe demonstrate that provoked LVOTO during DSE in non HCM symptomatic patients is directly correlated to resting regional LS, where the increased BS-LS of ≥ ?17.5% was a key determinant of LVOT gradient provocation. Assessment of baseline BS-LS _average might be a bedside simple tool for detection of patients with DLVOTO not able to do DSE.     

脊柱胸腰段骨折椎体的三维形态学分析

目的 通过三维骨折线分布图的大数据形态学分析，揭示脊柱胸腰段椎体（T₁₁~L₂）骨折的好发模式及骨折特点，从而指导临床决策。方法 回顾性分析2017年1月至2019年3月AO分型为A型的压缩性胸腰段椎体（T₁₁~L₂）骨折病人的临床资料。共纳入了257例研究对象，平均年龄为46岁，266个骨折椎体，其中T₁₁骨折15例，T₁₂骨折69例，L₁骨折95例，L₂骨折87例。把病人高分辨率CT数据导入到Mimics软件中，通过阈值分割，重建出骨折椎体模型。依次将各个骨折椎体的骨折线临摹到相应正常椎体模型上，获得各个椎体节段的3D骨折线分布图。结果 3D骨折线分布图揭示骨折线主要集中在椎体的上半部分以及椎体的外1/3部分，并且沿着椎体的前方和侧方呈环状楔形分布。结论 首次将骨折的Mapping技术应用到胸腰段骨折的分析研究中，骨折线分布图揭示了胸腰段骨折的好发模式及形态学特点，从流行病学及形态学方面提高了对胸腰段骨折的认识，有助于提升后续的科学研究及改善临床决策。     

CT引导下三管式腔内后装与腔内结合插植后装用于宫颈癌治疗的对比研究

目的:比较局部晚期宫颈癌采用标准三管施源器的腔内后装(tandem and ovoid)与腔内结合组织间插植后装的剂量学差异。方法:CT引导下的三维适形近距离治疗局部晚期宫颈癌患者20 例，间隔采用三管式腔内后装与腔内结合组织间插植共 72次。 按照施源器的不同分成 ２个组，每组 36 次，对靶区剂量、危及器官等进行比较。结果:在给予A点相同处方剂量的情况下，HR-CTV D90、D100在三管式腔内后装组与腔内结合组织间插植后装组中分别为（590.0±46.4）cGy、（471.2±66.2）cGy，（502.8±67.7）cGy、（335.9±46.0）cGy，P＜0．05)，膀胱、直肠、乙状结肠D2cc均相近（P=0.85、0.28、0.53）。结论:采用腔内结合插植后装治疗局部晚期宫颈癌比三管式腔内后装可获得更高的靶区剂量，但长期疗效及晚期反应仍需进一步研究。