Total Number Of Intersections Research Articles

Dose-dependent modulation of microglia activation in rats after penetrating traumatic brain injury (pTBI) by transplanted human neural stem cells.

Traumatic brain injury (TBI) often results in long-lasting patterns of neurological deficits including motor, sensory, and cognitive abnormalities. Cranial gunshot survivors are among the most disabled TBI patients and face a lifetime of disability with no approved strategies to protect or repair the brain after injury. Recent studies using a model of penetrating TBI (pTBI) have reported that human neural stem cells (hNSCs) transplantation can lead to dose and location-dependent neuroprotection. Evidence for regional patterns of microglial activation has also been reported after pTBI with evidence for microglial cell death by pyroptosis. Because of the importance of injury-induced microglial activation in the pathogenesis of TBI, we tested the hypothesis that dose-dependent hNSC mediated neuroprotection after pTBI was associated with reduced microglial activation in pericontusional cortical areas. To test this hypothesis, quantitative microglial/macrophage Iba1 immunohistochemistry and Sholl analysis was conducted to investigate the arborization patterns using four experimental groups including, (i) Sham operated (no injury) + low dose (0.16 million cells/rat), (ii) pTBI + vehicle (no cells), (iii) pTBI + low dose hNSCs (0.16 million/rat), and (iv) pTBI + high dose hNSCs (1.6 million cells/rat). At 3 months post-transplantation (transplants at one week after pTBI), the total number of intersections was significantly reduced in vehicle treated pTBI animals versus sham operated controls indicating increased microglia/macrophage activation. In contrast, hNSC transplantation led to a dose-dependent increase in the number of intersections compared to pTBI vehicle indicating less microglia/macrophage activation. The peak of Sholl intersections at 1 μm from the center of the microglia/macrophages ranged from ~6,500-14,000 intersections for sham operated, ~250-500 intersections for pTBI vehicle, ~550-1,000 intersections for pTBI low dose, and ~2,500-7,500 intersections for pTBI high dose. Plotting data along the rostrocaudal axis also showed that pericontusional cortical areas protected by hNSC transplantation had increased intersections compared to nontreated pTBI animals. These studies using a non-biased Sholl analysis demonstrated a dose-dependent reduction in inflammatory cell activation that may be associated with a neuroprotective effect driven by the cellular transplant in perilesional regions after pTBI.

Exercise Intervention Modulates Synaptic Plasticity by Inhibiting Excessive Microglial Activation via Exosomes.

BackgroundExosomes can activate microglia to modulate neural activity and synaptic plasticity by phagocytosis of neural spines or synapses. Our previous research found that an early 4-week exercise intervention in middle cerebral artery occlusion (MCAO) rats can promote the release of exosomes and protect the brain. This study intended to further explore the intrinsic mechanism of neuroprotection by exosome release after exercise.MethodsRats were randomly divided into four groups: the sham operation (SHAM), middle cerebral artery occlusion (MCAO) with sedentary intervention (SED-MCAO), MCAO with exercise intervention (EX-MCAO), and MCAO with exercise intervention and exosome injection (EX-MCAO-EXO). Modified neurological severity score (mNSS), cerebral infarction volume ratio, microglial activation, dendritic complexity, and expression of synaptophysin (Syn) and postsynaptic density protein 95 (PSD-95) were detected after 28 days of intervention.Results(1) The exercise improved body weight and mNSS score, and the survival state of the rats after exosome infusion was better. (2) Compared with the SED-MCAO group, the EX-MCAO (P = 0.039) and EX-MCAO-EXO groups (P = 0.002) had significantly lower cerebral infarct volume ratios (P < 0.05), among which the EX-MCAO-EXO group had the lowest (P = 0.031). (3) Compared with the SED-MCAO group, the EX-MCAO and EX-MCAO-EXO groups had a significantly decreased number of microglia (P < 0.001) and significantly increased process length/cell (P < 0.01) and end point/cell (P < 0.01) values, with the EX-MCAO-EXO group having the lowest number of microglia (P = 0.036) and most significantly increased end point/cell value (P = 0.027). (4) Compared with the SED-MCAO group, the total number of intersections and branches of the apical and basal dendrites in the EX-MCAO and EX-MCAO-EXO groups was increased significantly (P < 0.05), and the increase was more significant in the EX-MCAO-EXO group (P < 0.05). (5) The expression levels of Syn and PSD-95 in the EX-MCAO (PSyn = 0.043, PPSD−95 = 0.047) and EX-MCAO-EXO groups were significantly higher than those in the SED-MCAO group (P < 0.05), and the expression levels in the EX-MCAO-EXO group were significantly higher than those in the EX-MCAO group (P < 0.05).ConclusionEarly exercise intervention after stroke can inhibit the excessive activation of microglia and regulate synaptic plasticity by exosome release.

Nano-MgO composites containing plasmid DNA to silence SNCA gene displays neuroprotective effects in Parkinson's rats induced by 6-hydroxydopamine

Parkinson's disease (PD) always causes dyskinesia and cognitive impairments. The alpha-synuclein (α-syn) accumulation, one of the main pathological characteristics of PD, may impair synaptic structural and synaptic functions. Nano-MgO composites has been reported to interfere α-syn expression. The present study is aim to investigate the roles of nano-MgO composites on cognitive impairments in PD rats. PD rats were formed by 6-hydroxydopamine (6-OH DA) and α-syn expression were evaluated by Western blot. Hippocampal dendritic morphology was examined by Golgi staining. Morris water maze (MWM) test was applied to evaluate learning and memory abilities and population spike was recorded by electrophysiological records in vivo. The results showed that: 6-OH DA-treated up-regulated α-syn levels in striatum and hippocampus and increased the rotational times by APO, but nano-MgO composites could down-regulated α-syn levels. The overall length of dendritic and the total number of intersections were reduced by 6-OH DA, accompanied by the decrease of the dendritic spine density in hippocampal CA1, CA3 and DG regions. Interestingly, nano-MgO composites could alleviate the morphological damages of dendrites. In the MWM test, the escape latencies and the swimming distances in PD rats were increased as compared to the sham group, and nano-MgO composites could reduce the escapes latencies and the swimming distances. Furthermore, 6-OH DA reduced the amplitudes of long-term potentiation (LTP) in hippocampal CA1 region, and 6 mg/kg nano-MgO composites could improve LTP amplitudes. In conclusion, the current findings would be helpful to explore the roles of nano-MgO composites on neuroprotection in PD.

Macroscopic spatial analysis of pedestrian and bicycle crashes

This study investigates the effect of spatial correlation using a Bayesian spatial framework to model pedestrian and bicycle crashes in Traffic Analysis Zones (TAZs). Aggregate models for pedestrian and bicycle crashes were estimated as a function of variables related to roadway characteristics, and various demographic and socio-economic factors. It was found that significant differences were present between the predictor sets for pedestrian and bicycle crashes. The Bayesian Poisson-lognormal model accounting for spatial correlation for pedestrian crashes in the TAZs of the study counties retained nine variables significantly different from zero at 95% Bayesian credible interval. These variables were – total roadway length with 35mph posted speed limit, total number of intersections per TAZ, median household income, total number of dwelling units, log of population per square mile of a TAZ, percentage of households with non-retired workers but zero auto, percentage of households with non-retired workers and one auto, long term parking cost, and log of total number of employment in a TAZ. A separate distinct set of predictors were found for the bicycle crash model. In all cases the Bayesian models with spatial correlation performed better than the models that did not account for spatial correlation among TAZs. This finding implies that spatial correlation should be considered while modeling pedestrian and bicycle crashes at the aggregate or macro-level.

Aggregate nonparametric safety analysis of traffic zones

Exploring the significant variables related to specific types of crashes is vitally important in the planning stage of a transportation network. This paper aims to identify and examine important variables associated with total crashes and severe crashes per traffic analysis zone (TAZ) in four counties of the state of Florida by applying nonparametric statistical techniques such as data mining and random forest. The intention of investigating these factors in such aggregate level analysis is to incorporate proactive safety measures in transportation planning. Total and severe crashes per TAZ were modeled to provide predictive decision trees. The variables which carried higher weight of importance for total crashes per TAZ were – total number of intersections per TAZ, airport trip productions, light truck productions, and total roadway segment length with 35mph posted speed limit. The other significant variables identified for total crashes were total roadway length with 15mph posted speed limit, total roadway length with 65mph posted speed limit, and non-home based work productions. For severe crashes, total number of intersections per TAZ, light truck productions, total roadway length with 35mph posted speed limit, and total roadway length with 65mph posted speed limit were among the significant variables. These variables were further verified and supported by the random forest results.

Effects of exercise training on dendritic morphology in the cardiorespiratory and locomotor centers of the mature rat brain

It has been shown that dendritic branching in neural cardiorespiratory and locomotor centers can be attenuated with exercise training (ET) initiated immediately after weaning. The purpose of this study was to determine whether neuroplastic changes occur within cardiorespiratory and locomotor centers due to ET after maturation. Male Sprague-Dawley rats (21 days old, n=28) were individually housed in standard cages. At 91 days of age, animals were divided into two groups: untrained (UN; n=14) and trained (TR; n=14). The TR group exercised spontaneously for 50 days on running wheels. ET indexes were obtained, including maximal O2 consumption, percent body fat, resting heart rate, and heart weight-to-body weight ratios. The brain was processed with a modified Golgi-Cox procedure. Impregnated neurons from the periaqueductal gray (PAG), posterior hypothalamic area (PH), nucleus of the tractus solitarius (NTS), cuneiform nucleus (CnF), rostral ventrolateral medulla, nucleus cuneatus, and cerebral cortex were examined. Neurons were traced and analyzed using the Sholl concentric ring analysis of dendritic branching. The mean total number of dendritic intersections with the concentric rings per neuron per animal were compared between UN and TR groups. There were significant differences between UN and TR groups in the PH, PAG, CnF, and NTS in the total number of intersections per animal. In some areas, the effect size was smaller when ET was initiated in mature animals, possibly related to their relatively reduced activity levels. In conclusion, the adult rat brain remains dynamic and adapts to chronic ET. However, some brain areas appear to be more affected if ET is initiated in early postnatal development.

Mef2-mediated transcription of the miR379–410 cluster regulates activity-dependent dendritogenesis by fine-tuning Pumilio2 protein levels

Neuronal activity orchestrates the proper development of the neuronal circuitry by regulating both transcriptional and post-transcriptional gene expression programmes. How these programmes are coordinated, however, is largely unknown. We found that the transcription of miR379–410, a large cluster of brain-specific microRNAs (miRNAs), is induced by increasing neuronal activity in primary rat neurons. Results from chromatin immunoprecipitation and luciferase reporter assays suggest that binding of the transcription factor myocyte enhancing factor 2 (Mef2) upstream of miR379–410 is necessary and sufficient for activity-dependent transcription of the cluster. Mef2-induced expression of at least three individual miRNAs of the miR379–410 cluster is required for activity-dependent dendritic outgrowth of hippocampal neurons. One of these miRNAs, the dendritic miR-134, promotes outgrowth by inhibiting translation of the mRNA encoding for the translational repressor Pumilio2. In summary, we have described a novel regulatory pathway that couples activity-dependent transcription to miRNA-dependent translational control of gene expression during neuronal development.

Iterating the number of intersection points of the diagonals of irregular convex polygons, or C(n,4) the hard way !

Counting the number of internal intersection points made by the diagonals of irregular convex polygons where no three diagonals are concurrent is an interesting problem in discrete mathematics. This paper uses an iterative approach to develop a summation relation which tallies the total number of intersections, and shows that this total can be expressed as a simple sum of products. This iterative approach also motivates solutions for the number of internal regions and number of line segments produced by the diagonals

Reversibility of exercise-induced dendritic attenuation in brain cardiorespiratory and locomotor areas following exercise detraining

It has been shown previously that dendritic branching in cardiorespiratory and locomotor brain areas can be attenuated with exercise training (ET). It was not known whether this process was reversible. Twenty-three (n = 23) male Sprague-Dawley rats were individually caged and divided into two groups: untrained (UN; n = 11) and detrained (DTR; n = 12). DTR were provided with a running wheel at 21 days of age and exercised spontaneously. After 120 days (70 days of ET followed by 50 days of detraining), ET indexes were obtained, including maximal oxygen uptake, percent body fat, resting heart rate, and heart weight-to-body weight ratios. The brain was processed according to a modified Golgi-Cox procedure. Impregnated neurons from the periaqueductal gray (PAG), posterior hypothalamic area (PH), nucleus of the tractus solitarius (NTS), and cuneiform nucleus (CfN) were examined in coronal sections. Neurons were traced using a camera lucida technique and analyzed using the Sholl concentric ring analysis of dendritic branching. t-Tests compared the mean number of intersections per neuron by grouping inner rings, outer rings, and total number of intersections per animal. There were no significant differences between UN and DTR in PH, PAG, CfN, and NTS in the inner rings, outer rings, and total number of intersections per animal. A separate group of animals was used to show that a training effect in the CfN and NTS was present at 56 days of ET. Our results show that dendritic attenuation resulting from 70 days of ET in PH, PAG, CfN, and NTS is completely reversed with 50 days of detraining.

Non-destructive, stereological estimation of plant root lengths, branching pattern and diameter distribution

The total length of a linear structure contained in an unbounded, transparent reference space can be estimated from ‘total vertical projections’ obtained by rotating the linear structure about an arbitrary ‘vertical’ axis, and projecting the linear structure onto a plane parallel to the axis of rotation. The total number of intersections between cycloid arcs with their minor axis perpendicular to the axis of rotation and the projected linear structure then provides an unbiased estimator of the total length of the structure. In this study, a stereological procedure based on the method of ‘total vertical projections’ was used to non-destructively estimate total root length, number of branches, diameter distribution and mean root diameter of crested wheatgrass plants (Agropyron cristatum L.) growing in a transparent medium. Root lengths, diameters, and number of branching points of various orders were determined at 3-day intervals over a 4-week growing period. The length estimator was very robust and efficient with sampling coefficients of error usually less than 5% for a total of 50–150 grid intersection counts over two projection directions per plant. Biological coefficients of variance for total length were between 30–70%, and were largely related to variation in the extent of branching.

Efficient algorithms for counting and reporting pairwise intersections between convex polygons

Let S be a set of convex polygons in the plane with a total of n vertices, where a polygon consists of the boundary as well as the interior. Efficient algorithms are given for counting and for reporting output-sensitively the I pairs of polygons that intersect. The algorithm for the counting problem takes O(n 4 3 + ε ) time and the algorithm for the reporting problem takes O(n 4 3 + ε + I ) time, where ε >0 is an arbitrarily small constant. The result is based on an interesting characterization of the intersection of two convex polygons in terms of the intersection of certain trapezoids from their trapezoidal decomposition. The problem is interesting and challenging because the output size, I, can be much smaller than the total number of intersections between the polygons and because the number of polygons and their sizes can depend on n.

Intersection of Curves and Crossing Number of C m × C n on Surfaces

Let $({\cal K}_1, {\cal K}_2)$ be two families of closed curves on a surface ${\cal S}$ , such that $|{\cal K}_1| = m$, $|{\cal K}_2| = n$, $m_0 \leq m \leq n$ , each curve in ${\cal K}_1$ intersects each curve in ${\cal K}_2$ , and no point of ${\cal S}$ is covered three times. When ${\cal S}$ is the plane, the projective plane, or the Klein bottle, we prove that the total number of intersections in ${\cal K}_1 \cup {\cal K}_2$ is at least 10mn/9 , 12mn/11 , and mn+10 -13 m 2 , respectively. Moreover, when m is close to n , the constants are improved. For instance, the constant for the plane, 10/9 , is improved to 8/5 , for n ≤ 5(m-1)/4 . Consequently, we prove lower bounds on the crossing number of the Cartesian product of two cycles, in the plane, projective plane, and the Klein bottle. All lower bounds are within small multiplicative factors from easily derived upper bounds. No general lower bound has been previously known, even on the plane.

Contact sites between the inner and outer mitochondrial membranes in stunned versus hibernating myocardium

This study characterizes the energy state and the influence of calcium on myocardial stunning and chronic hibernation via the quantification of a calcium-sensitive phenomenon known as mitochondrial contact sites. For stunning, the left anterior descending artery of mongrel dogs was occluded for 15 minutes, followed by a 150-minute reperfusion; for chronic hibernation, we used human biopsies obtained during coronary artery bypass graft (CABG) from viable (positron emission tomography-controlled) asynergic areas. Both sample groups were processed for electron microscopy, and the ratio of surface densities of contact sites to mitochondrial membranes was quantified with morphometry. Therefore a cycloidal pattern was superimposed on the electron micrographs, and the ratio between the total number of intersections between cycloids and contact sites and the total number of intersections between cycloids and mitochondrial membranes is the ratio of surface densities ( S s ). In stunned cells, S s = 0.46 ± 0.06, which is significantly higher than the ratio in the normokinetic cells, S s = 0.355 ± 0.003, although the general ultrastructure of the subcellular compartments is practically identical to those in the normoxic area. The distinction between cells affected by chronic hibernation and normal cells was based on structural criteria. The ratio of surface densities, expressed S s = 0.27 ± 0.05, was significantly lower than the ratio in the normoxic area ( S s = 0.356 ± 0.005). The high ratio of surface densities in the stunned cells lends credibility to the notion that stunning implies an increased intracellular calcium content and energy demand, whereas hibernation might be a kind of low demand-low supply situation with a low intracellular calcium level.

An efficient output-sensitive hidden-surface removal algorithm for polyhedral terrains

In this paper, we present an algorithm for hidden surface removal for a class of polyhedral surfaces which have a property that they can be ordered relatively quickly. For example, our results apply directly to terrain maps. A distinguishing feature of our algorithm is that its running time is sensitive to the actual size of the visible image, rather than the total number of intersections in the image plane which can be much larger than the visible image. The time complexity of this algorithm is O(( k + n) log 2 n) where n and k are, respectively, the input and the output sizes. Thus, in a significant number of situations this will be faster than the worst case optimal algorithms which have running time of Ω(n 2) irrespective of the output size.

Measurement of lacunar volume in bone using a stereological grid counting method evolved for the scanning electron microscope.

SUMMARYA stereological grid method has been evolved for scanning electron microscopy using a self‐generated superimposed grid which compensates for the non‐linearity of the CRT image. The method was applied to determine the volume proportion of lacunae in monkey humerus cortical bone. Flat cut specimens of bone were prepared and photographed with a superimposed grid, and the number of lacunae on intersections of the grid were counted and compared with the total number of intersections on bone matrix. The lacunar volume proportion was 1.06% ± 0.50%.