Outer Transition Zone Research Articles

Changes in the physiological activity of parenchyma cells in Dalbergia odorifera xylem and its relationship with heartwood formation

BackgroundThe formation of a tree’s heartwood gives the wood properties such as natural decay resistance and aesthetic color, and often directly determines the value of wood products. Regulating the quantity and quality of heartwood is of great importance to the use of wood. However, the mechanism of heartwood formation has been poorly understood.ResultsUsing Dalbergia odorifera as the study species, the number of starch grains, the morphology of the nuclei, the changes in the content of water and secondary metabolites were observed continuously in the radial direction of the xylem. The results show that from the outer toward inner sapwood, the starch grains are abundant, the length to diameter ratio of the nuclei is decreasing, and the morphology changes from elongated elliptical and then to round. In the outer transition zone, the starch grains begin to decrease abruptly and the nuclei shrink at a slower rate, with a radial width of approximately 2 mm. In the inner transition zone, the heartwood color begins to appear, the starch grains disappear and a few nuclei with reduced fluorescence are present, with a radial width of approximately 1 mm. Heartwood formation after complete disappearance of the nuclei. The moisture content of the heartwood is higher than that of the sapwood, and the inner transition zone is where the content rises. The secondary metabolites of the heartwood begin to accumulate in large quantities in the inner transition zone.ConclusionBased on the physiological changes of parenchyma cells in the xylem, the radial width of the transition zone of Dalbergia odorifera is clearly defined as approximately 3 mm. Both the water and secondary metabolite abrupt changes occur at the final stage of programmed cell death, and neither is a direct cause of programmed cell death in parenchyma cells.

Assessing the Relationship between Ecological Water Demand of Haloxlon ammodendron and Its Wind Erosion Prevention Effect

Desert vegetation in the outer transition zone of an arid oasis serves as a protective barrier against wind and sand, safeguarding the oasis ecosystem. However, intensive agricultural water usage within the oasis has led to water depletion, posing a threat to the survival and growth of desert vegetation, as well as the associated increase in wind and sand phenomena. To ensure the sustainable distribution of water resources and maintain the stability of the oasis peripheral ecosystem, this study aimed to investigate the relationship between the ecological water demand of desert vegetation and its effectiveness in preventing wind erosion. Through a combination of field sample tests, field pit tests, and data analysis, this research focused on Haloxlon ammodendron, the most prevalent species on the oasis periphery, to explore the intricate relationship between its ecological water demand and resistance to wind erosion. The results showed that medium-vegetation-coverage soils exhibited a higher soil moisture content (7.02%) compared to high-vegetation-coverage soils (1.57%) and low-vegetation-coverage soils (3.41%). As the soil water content decreased, the growth rate of H. ammodendron’s plant height, new branches, and crown width decelerated. The ecological water requirement of H. ammodendron during its growth period was 70.95 mm under medium-vegetation-coverage conditions, exhibiting a significant increase of 14.6% and 12.3% compared to high- and low-vegetation-coverage conditions, respectively. Meanwhile, H. ammodendron exhibits remarkable wind erosion prevention effects in moderate coverage conditions, resulting in a significant reduction in surface sand collection and sand transport by 53.15% and 51.29%, respectively, compared to low vegetation coverage; however, no significant difference was observed when compared to high vegetation coverage. The SEM model results revealed that soil water content had an indirect effect on sand transport (R2 = 0.90) and sand collection (R2 = 0.96) through three pathways of action, namely: volatile water content–crown growth rate–wind speed–sediment discharge; volatile water content–plant height growth rate–vegetation coverage–wind speed–sediment discharge; and volatile water content–plant height growth rate–vegetation coverage–sediment accumulation. This study provides valuable insights for the scientific formulation and implementation of strategies aimed at protecting desert vegetation.

High Cortico-Trabecular Transitional Zone Porosity and Reduced Trabecular Density in Men and Women with Stress Fractures.

To determine whether stress fractures are associated with bone microstructural deterioration we quantified distal radial and the unfractured distal tibia using high resolution peripheral quantitative computed tomography in 26 cases with lower limb stress fractures (15 males, 11 females; mean age 37.1 ± 3.1 years) and 62 age-matched healthy controls (24 males, 38 females; mean age 35.0 ± 1.6 years). Relative to controls, in men, at the distal radius, cases had smaller cortical cross sectional area (CSA) (p = 0.012), higher porosity of the outer transitional zone (OTZ) (p = 0.006), inner transitional zone (ITZ) (p = 0.043) and the compact-appearing cortex (CC) (p = 0.023) while trabecular vBMD was lower (p = 0.002). At the distal tibia, cases also had a smaller cortical CSA (p = 0.008). Cortical porosity was not higher, but trabecular vBMD was lower (p = 0.001). Relative to controls, in women, cases had higher distal radial porosity of the OTZ (p = 0.028), ITZ (p = 0.030) not CC (p = 0.054). Trabecular vBMD was lower (p = 0.041). Distal tibial porosity was higher in the OTZ (p = 0.035), ITZ (p = 0.009), not CC. Stress fractures are associated with compromised cortical and trabecular microstructure.

Distribution of Living Ray Parenchyma Cells and Major Bioactive Compounds During the Heartwood Formation of Taiwania cryptomerioides Hayata

The heartwood of Taiwania (Taiwania cryptomerioides Hayata) has the excellent decay resistance and fascinating color qualities due to the accumulation of bioactive compounds. However, limited information was addressed to the heartwood formation of this species. In this study, we established the distribution of the living ray parenchyma cells and profiled the major bioactive compounds across and along the Taiwania stem. The ray parenchyma cells would die within 1–2 annual rings of the transition zone, which occurs around 8–13 annual rings counted from the cambium. The gradual loss of the starch grains accompanied with the deposition of the colored materials into the cell lumens started from the outer transition zone. The radial distribution of the extractive contents and its signature bioactive compounds across Taiwania stems gradually increased from the transition zone toward the heartwood tissues. The aforementioned properties did not show specific trends along the vertical direction of the Taiwania stems.

Denosumab Reduces Cortical Porosity of the Proximal Femoral Shaft in Postmenopausal Women With Osteoporosis.

Hip fractures account for over one-half the morbidity, mortality, and cost associated with osteoporosis. Fragility of the proximal femur is the result of rapid and unbalanced bone remodeling events that excavate more bone than they deposit, producing a porous, thinned, and fragile cortex. We hypothesized that the slowing of remodeling during treatment with denosumab allows refilling of the many cavities excavated before treatment now opposed by excavation of fewer new resorption cavities. The resulting net effect is a reduction in cortical porosity and an increase in proximal femur strength. Images were acquired at baseline and 36 months using multidetector CT in 28 women receiving denosumab and 22 women receiving placebo in a substudy of FREEDOM, a randomized, double-blind, placebo-controlled trial involving women with postmenopausal osteoporosis. Porosity was quantified using StrAx1.0 software. Strength was estimated using finite element analysis. At baseline, the higher the serum resorption marker, CTx, the greater the porosity of the total cortex (r = 0.34, p = 0.02), and the higher the porosity, the lower the hip strength (r = -0.31, p = 0.03). By 36 months, denosumab treatment reduced porosity of the total cortex by 3.6% relative to baseline. Reductions in porosity relative to placebo at 36 months were 5.3% in total cortex, 7.9% in compact-appearing cortex, 5.6% in outer transitional zone, and 1.8% in inner transitional zone (all p < 0.01). The improvement in estimated hip integral strength of 7.9% from baseline (p < 0.0001) was associated with the reduction in total porosity (r = -0.41, p = 0.03). In summary, denosumab reduced cortical porosity of the proximal femoral shaft, resulting in increased mineralized matrix volume and improved strength, changes that may contribute to the reduction in hip and nonvertebral fractures reported with denosumab therapy. © 2016 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research (ASBMR).

SAT0457 Reduced Hip Cortical Porosity with Denosumab (DMAB) Treatment in Women with Osteoporosis

BackgroundCortical mass and structure (i.e., porosity, thickness, area) influence bone strength, and contribute to nonvertebral fracture risk. Cortical porosity, a reflection of the degree of structural decay associated with exponential...

Quantifying Local Stiffness Variations in Radiofrequency Ablations With Dynamic Indentation

Elastographic imaging can be used to monitor ablation procedures; however, confident and clear determination of the ablation boundary is essential to ensure complete treatment of the pathological target. To investigate the potential for ablation boundary representation on elastographic images, local variations in the viscoelastic properties in radiofrequency-ablated regions that were formed in vivo in porcine liver tissue were quantified using dynamic indentation. Spatial stiffness maps were then correlated to stained histology, the gold standard for the determination of the ablation periphery or boundary. Regions of interest in 11 radiofrequency ablation samples were indented at 18-24 locations each, including the central zone of complete necrosis and more peripheral transition zones including normal tissue. Storage modulus and the rate of stiffening were both greatest in the central ablation zone and decreased with radial distance away from the center. The storage modulus and modulus contrast at the ablation outer transition zone boundary were 3.1 ± 1.0 kPa and 1.6 ± 0.4, respectively, and 36.2 ± 9.1 kPa and 18.3 ± 5.5 at the condensation boundary within the ablation zone. Elastographic imaging modalities were then compared to gross pathology in ex vivo bovine liver tissue. Area estimated from strain, shear-wave velocity, and gross pathology images were 470, 560, and 574 mm(2), respectively, and ablation widths were 19.4, 20.7, and 23.0 mm. This study has provided insights into spatial stiffness distributions within radiofrequency ablations and suggests that low stiffness contrast on the ablation periphery leads to the observed underestimation of ablation extent on elastographic images.

Chemical differences between sapwood and heartwood of Chamaecyparis obtusa detected by ToF-SIMS

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to investigate the distribution of elements, Na, Mg, Al, K, and Ca, and lignin, in the contiguous growth rings including the sapwood/heartwood boundary in Hinoki cypress ( Chamaecyparis obtusa). Lignin was distributed almost uniformly from sapwood to heartwood. The concentrations of most of the elements showed a drastic increase or decrease in the transition zone between sapwood and heartwood. The ToF-SIMS mapping analysis showed that most of the elements predominantly localized in the ray parenchyma cells in the inner transition zone and heartwood, while the elements showed no localization and distributed almost uniformly in the outer transition zone near sapwood. The result suggests that the ray parenchyma cells play a role in behaviors of elements during the transition from sapwood to heartwood.

Bifurcation Model for Characterization of Pulmonary Architecture

A flexible mathematical model of an asymmetric bronchial airway bifurcation is presented. The bifurcation structure is automatically determined after the user specifies geometric parameters: radius of parent airway, radii of daughter airways, radii of curvature of the daughter branch toroids, bifurcation angles, and radius of curvature of carina ridge. Detailed shape in the region where the three airways merge is defined by several explicit functions and can be changed with ease in accordance with observed lung structure. These functions take into account the blunt shape of the carina, the smooth transition from the outer transition zone to the inner one, and the shift in carinal ridge starting position as a function of bifurcation asymmetry. We validated the bifurcation model by comparing it to a computed tomography image of a rat lung cast. Three-dimensional representations of the bifurcation geometry can be viewed at http://mae.ucdavis.edu/wexler/lungs/bifurc.htm.

Aging and Sinoatrial Node Dysfunction

In the century since the discovery by Keith and Flack of the sinoatrial node in the mole heart, a detailed mosaic of its cellular, anatomic, and electrophysiological properties has emerged. The human sinus node has been found to be anatomically constant and well localized, occupying an approximately 10-mm subepicardial region on the sulcus terminalis at the superior cavo–atrial junction.1 Histologically, its ultrastructure of central P cells (likely corresponding to the leading pacemaker site) and outer transitional zone merging with surrounding atrial myocardium have been well characterized.1 Great progress also has been made in defining the ionic mechanisms responsible for the sinoatrial action potential and its spontaneous pacemaker activity, including important contributory roles for I Ca,L, I k, and the funny current, I f.1 This morphologically discrete, unifocal sinus node is not the exclusive force behind clinical sinus rhythm, however. Detailed animal and human mapping has demonstrated that normal cardiac pacemaker activity is widely distributed in the right atrium. In the human atrium, the pacemaker complex extends for up to 75 mm along the long axis of the sulcus terminalis and precaval band.2 At times, even left atrial pacemakers may be active during normal sinus rhythm.2 Graduated differential sensitivity to adrenergic and vagal inputs exists along the integrated pacemaker complex such that superior sites tend to dominate during periods of sympathetic drive, whereas inferior sites are activated by increased parasympathetic tone. Increasing the complexity, each sinus beat may have multicentric origin, and the nature of conduction out of the node also seems to be variable in response to autonomic tone.2 The presence of a diffuse pacemaker complex …

Modelling and Study of Smear Zones Around Band Shaped Drains

ABSTRACT Plastic drains generally band or strip shaped, are often installed in square or triangular arrays. The horizontal coefficient of permeability measured in situ from around a plastic board drain indicated three distinct zones, viz., an inner smear zone consisting of highly remolded soil, an outer transition zone, and soil unaffected by the drain installation. Thus, the plastic drain treated soil is modelled as a two dimensional consolidation problem consisting of these three distinct zones. The resulting equations are solved numerically to obtain the degree of consolidation versus time factor curves. The extent and the value of the coefficient of permeability of the inner smear zone are shown to be the primary factors controlling the consolidation behavior of the soil. Based on the results from this study, it is recommended that the response of plastic drain treated soil can be improved by reducing the mandrel size and/or modifying the shape of the drain to a circle or an ellipse, rather than by having only a closer spacing of the drain.

Severed nerve stumps around a laser-irradiated locus in the deep muscular plexus of the guinea-pig small intestine.

Small foci of photocoagulation necrosis (diameter about 0.5 mm) were produced in the wall of the guinea-pig small intestine by argon laser irradiation applied to the serosal surface. Features of the nerve elements around the necrotic masses were examined by immunocytochemistry, scanning electron microscopy, and transmission electron microscopy. The severed ends of nerve strands were examined at various intervals from 10 to 60 h after the laser irradiation, and the acute cytological responses of the nerve terminals, glial cells and connective tissue cells were studied. The laser irradiated foci in the deep muscular plexus (plexus muscularis profundus: CAJAL, 1911) had concentric configuration: 1) central necrotic area, 2) inner transitional zone, 3) outer transitional zone, and 4) normal area. In the necrotic area, there were inflammatory cells such as neutrophile leukocytes and macrophages. Contours of the smooth muscle cells and nerve strands were well preserved in spite of the damage to their subcellular structures. In the inner transitional area, individual nerve fibers gathered to form bundles. Some of these nerve bundles were devoid of a glial cell framework. In the outer transitional zone, there were swollen nerve terminals with a strong immunoreactivity for methionine-enkephalin-Arg6-Gly7-Leu6. In transmission electron microscopy, some of these swollen nerve fibers contained many large cored vesicles. Glial cells in the outer transitional zone exhibited an S-100b protein-like immunoreactivity. Scanning electron microscopy revealed gatherings of fibroblast-like (FBL) cells in the outer transitional zone. Two subtypes of these were distinguished: the first subtype (FBL I) was characterized by short, blunt cytoplasmic processes; the second subtype (FBL II), possessing long, slender dendritic processes, assembled to form a dense network which intermeshed with that of the nerve strands. The enteric nerve plexuses severed by laser-irradiation affords a unique experimental model in the cytological investigation of the plasticity of the peripheral autonomic nervous system.

Accretion by rotating magnetic neutron stars. III - Accretion torques and period changes in pulsating X-ray sources

The solutions of the two-dimensional hydromagnetic equations are used to calculate the torque on a magnetic neutron star accreting from a Keplerian disk. It is found that the magnetic coupling between the star and the plasma in the outer transition zone is appreciable; that as a result, the spin-up torque on fast rotators is substantially less than that on slow rotators, and that for sufficiently high stellar angular velocities or sufficiently low mass accretion rates, the rotation of the star can be braked while accretion continues. These results are applied to pulsating X-ray sources, revealing that at high luminosities a star of given spin period rotating in the same direction as the disk can experience either spin-up or spin-down, depending on its luminosity. Also considered are the general problem of interpreting period changes in pulsating X-ray sources, and the dipole magnetic moments of nine pulsating X-ray sources are estimated by fitting the theoretical spin-up equation to estimates of the average luminosity and spin-up rate of each source.

Histology and Sensory Innervation of Transitional and Mucosal Parts of the Lip of Monkey

The lip of monkey is not different from the human counterpart in that it can be divided into the cutaneous, the transitional and the mucous parts and that the transitional part can be subdivided into the outer and the inner zones. The cutaneous part is covered by a common haired skin with sinus-hairs. The epithelium of the outer transitional zone is considerably thicker than the epidermis of the cutaneons part, is only very weakly hornified on its surface and is intruded by conspicuous papillae growing out of the propria. In this zone of the human lip sebaceous glands without hairs are frequently found, but in the simian lip, such glands are more often found provided with hairs, suggesting that this zone is not derived only from the mucous membrane but also from the haired skin as well. In the inner transitional zone, the epithelium is even thicker and the papillae are better developed, but the boundary between the inner and the outer zones is rather blurred in adult monkey. The epithelium in the mucous part is indeed still well developed, but the papillae are thinner and shorter and are arranged rather irregularly.The development of the sensory fibres distributed in the transitional and the mucous parts of the lip of monkey shows a parallelism with that of the papillae, as was the case with human lips. Namely, the sensory fibres are developed in the inner zone of the transitional part where the papillae are in strongest development, followed by its outer zone where the epithelium is relatively poorer in development but the papillae are still powerfully formed, while in the mucous part with papillae reduced in size and length only in spite of the thick epithelium, the sensory fibres are in poorest development.The sensory fibres coming into the outer transitional zone always end in the papillae in various types of terminations, as follows: 1. Unbranched and branched terminations formed by mediumsized fibres. The branched terminations are usually of simple type but somewhat more complex ones are not rare either. Their terminal fibres mostly end subepithelially, but frequently enough some are found to end in intraepithelial terminations. 2. Unbranched and branched terminations of peculiar form. In these the terminal fibres show the characteristics of conspicuous swelling and fibrillar expansion, markedly winding courses and blunt end points beneath the epithelium. 3. Glomerular terminations, mostly uncapsulated but more rarely covered by a thin connective tissue capsule. 1-3 sensory fibres are found running into the bulb containing a small number of specific nuclei, and their terminal fibres often show glomerular arrangement, but on many occasions they are found to end in fibrillar arrangement resembling that in MEISSNER's tactile bodies. The fibres forming such arrangement frequently show fibrillar expansions in their courses, 4. MEISSNER's tactile bodies found in the outer transitional zone in the portion adjacent to the inner zone. The very fine terminal fibres in such a body often show fibrillar expansions while running parallel to the epithelial surface or spiral-wise. The ellipsoid or spindle-form specific cell nuclei of limited number in the inner bulb also are arranged parallel to the fibres.The sensory terminations in the inner transitional zone are even better developed than in the outer zone. Here the MEISSNER's tactile bodies are particularly well developed. The unbranched and branched terminations here originate in thick fibres, but the latter are comparatively simply branched and the terminations of Type II above with swollen ends of the terminal fibres are found here too. The intraepithelial fibres are less frequent than in the outer zone.In the mucous part, the sensory fibres decrease abruptly in number and their terminations comprise only unbranched and simple branched ones, corpuscular terminations and intraepithelial fibres being found no more.