Perceptions of classroom goal structures, personal achievement goal orientations, and learning strategies

We examined the relations among students' perceptions of classroom goal structures (mastery and performance goal structures), students' achievement goal orientations (mastery, performance, and work-avoidance goals), and learning strategies (deep processing, surface processing and self-handicapping strategies). Participants were 323 5th and 6th grade students in elementary schools. The results from structural equation modeling indicated that perceptions of classroom mastery goal structures were associated with students' mastery goal orientations, which were in turn related positively to the deep processing strategies and academic achievement. Perceptions of classroom performance goal stractures proved associated with work avoidance-goal orientations, which were positively related to the surface processing and self-handicapping strategies. Two types of goal structures had a positive relation with students' performance goal orientations, which had significant positive effects on academic achievement. The results of this study suggest that elementary school students' perceptions of mastery goal structures are related to adaptive patterns of learning more than perceptions of performance goal structures are. The role of perceptions of classroom goal structure in promoting students' goal orientations and learning strategies is discussed.     

Functional links between nuclear structure, gene expression, DNA replication, and methylation

Over the last decades it became clear that mammalian nuclei are highly organized. Nuclear processes like DNA replication and RNA metabolism take place in distinct subnuclear foci, which are enriched for enzymes involved in the corresponding biochemical reactions. This colocalization of functions with their respective factors is often referred to as functional organization of the nucleus. This organization is achieved by assembly of different enzymes and regulatory factors into high-molecular-weight complexes that are tethered to insoluble nuclear structures. Recently, several links between nuclear structure, gene expression, DNA replication, and methylation have been described that illustrate the interrelation of higher-order structures and nuclear functions. New insights into the functional organization of the nucleus and how it could explain the high precision and overall coordination of nuclear processes are discussed.     

Sequence, structure, function, immunity: structural genomics of costimulation

Summary:  Costimulatory receptors and ligands trigger the signaling pathways that are responsible for modulating the strength, course, and duration of an immune response. High-resolution structures have provided invaluable mechanistic insights by defining the chemical and physical features underlying costimulatory receptor:ligand specificity, affinity, oligomeric state, and valency. Furthermore, these structures revealed general architectural features that are important for the integration of these interactions and their associated signaling pathways into overall cellular physiology. Recent technological advances in structural biology promise unprecedented opportunities for furthering our understanding of the structural features and mechanisms that govern costimulation. In this review, we highlight unique insights that have been revealed by structures of costimulatory molecules from the immunoglobulin and tumor necrosis factor superfamilies and describe a vision for future structural and mechanistic analysis of costimulation. This vision includes simple strategies for the selection of candidate molecules for structure determination and highlights the critical role of structure in the design of mutant costimulatory molecules for the generation of in vivo structure–function correlations in a mammalian model system. This integrated 'atoms-to-animals' paradigm provides a comprehensive approach for defining atomic and molecular mechanisms.     

Unusual crystalline structures in photoreceptors of Lonchoplanella axi (Plathelminthes, Rhabdocoela, 'Typhloplanoida'): functional aspects and phylogenetic implications

Lonchoplanella axi has a pair of small dot-like pigment-cup ocelli. Each eye is composed of a single cup cell and two sensory cells of the rhabdomeric type. The most conspicuous differentiations in the sensory cells are spindle-shaped crystalline structures accompanying the nuclei. These structures flank the dorsolateral, respectively ventrolateral side of the nucleus. It is supposed that these 'spindles' serve rather as an additional shading device than as dioptrics. Since such structures in photoreceptors have hitherto not been reported for representatives of the Plathelminthes, it is concluded that the spindle-shaped crystalline bodies in the eyes of Lonchoplanella axi are an autapomorphic feature of this species or even an autapomorphy of the taxon Mariplanellinae.     

High Resolution Localization of Rab5, EEA1, and Nectin‐3 to Tubulobulbar Complexes in the Rat Testis

Tubulobulbar complexes are clathrin/actin‐based structures that internalize intercellular junctions in the testis. They resemble coated pits with extremely long necks that are cuffed by dendritic actin networks. As the structures mature, a swollen region or bulb develops near the end of each complex. The bulbs lack actin cuffs and are closely associated with cisternae of endoplasmic reticulum. The bulbs expand and are internalized and enter endocytic compartments of the Sertoli cell. Previous immunofluorescence studies have demonstrated that markers for early endosomes (Rab5 and EEA1) are associated with tubulobulbar complexes and are localized at or near the ends of the structures. Here we use a pre‐embedding immunoelectron microscopic technique to accurately localize these markers to apical tubulobulbar complexes that occur at junctions between Sertoli cells and spermatids. Staining for Rab5 occurs at bulbs, identified by the presence of two plasma membranes and a close association with cisternae of endoplasmic reticulum. EEA1 is associated with large vesicles that lack an association with the endoplasmic reticulum. Labeling for nectin‐3, an adhesion junction protein in the spermatid plasma membrane, occurs at junctions, TBC bulbs, and in associated double membrane vesicles. Our results suggest that Rab5 associates with junction protein containing bulbs prior to their internalization and that EEA1 associates with the structures later and after internalization. We conclude that at tubulobulbar complexes in Sertoli cells of the seminiferous epithelium, the identity of ‘bulbs’ as putative early endosomes begins to be established prior to their undergoing scission or budding from their parent structures. Anat Rec, 300:1160–1170, 2017. © 2017 Wiley Periodicals, Inc.     

Acute mediastinitis,mediastinal granuloma,and chronic fibrosing mediastinitis: A review

Acute mediastinitis is a rare infection that carries high morbidity and mortality. They are complications seen most often with deep sternal wound infections from surgeries with median sternotomies, oropharyngeal and odontogenic infections and esophageal perforations. These conditions should be promptly recognized and treated. Mediastinal granulomas are focal, mass-like lesions commonly resulting from prior granulomatous infections. They are regarded as benign, self-resolving lesions however can cause complications by compression of adjacent mediastinal structures. Chronic fibrosing mediastinitis is a rare, diffuse fibroinflammatory process most often seen with granulomatous infections and carries a worse prognosis than mediastinal granulomas especially when adjacent mediastinal structures are compromised. In this review, we discuss the epidemiology, etiology, clinical presentation, treatment and prognosis of acute mediastinitis, mediastinal granulomas, and chronic fibrosing mediastinitis.     

Catecholamine-containing, dopamine-beta-hydroxylase-immunoreactive perivascular nerve specializations in the rat kidney

Fluorescence histochemical visualization of catecholamines and immunolabeling of dopamine beta hydroxylase (DBH) were employed to study noradrenergic nerve terminals and perivascular nerve specializations in the rat kidney. Plexuses of catecholamine-containing and dopamine-beta-hydroxylase-immunoreactive nerves innervate the intrarenal arterial tree and larger intrarenal veins. Some perivascular nerve bundles have specialized segments composed of clusters of axonal enlargements that are immunoreactive for DBH and fluoresce intensely in ultraviolet light after fixation in a solution of formaldehyde and glutaraldehyde or treatment with glyoxylic acid. No fluorescent neural structures were found in denervated rat kidney sections treated with glyoxylic acid. Many such structures are associated with arteriolar branches of interlobar, arcuate, and interlobular arteries and are composed, in part, of axonal enlargements that contain mitochondria, microtubules, and one or more clusters of synaptic vesicles. These perivascular nerve specializations may be sites of axoaxonal interactions between noradrenergic axons or between these axons and other types of autonomic or sensory axons. The synaptic vesicles evidently store large amounts of catecholamine, but there is no evidence whether it is released into the surrounding tissue. These structures may be involved in changes in intrarenal innervation patterns which may occur as the rat ages. Regardless of the autonomic or sensory nature of intrarenal neural structures, close association of most such structures with arterioles suggests some neurovascular interaction.     

Energy, structure, conformation, and heart failure

The problem of heart failure is analyzed from the point of view of conformation changes in submolecular cardiomyocyte structures. The development of heart failure as a consequence of abnormal function of contractile myocardial proteins is discussed. The properties of actin and the role of structural changes in actin molecules in the impairment of ATP energy utilization and generation of contractile force by actomyosin complexes are studied. Experiments on animal models and autopsy samples showed that conformation changes precede disturbances in energy utilization by myofibrils, abnormal functioning of the energy-producing and Ca²⁺-transporting systems during the development of heart failure. It is proposed that rigid recombinations of submolecular structures in contracile proteins underlie impairment of myocardial contractility and resistance of the myocardium to regulatory factors and drugs (immobilization). Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 128, No. 8, pp. 124–140, August, 1999     

Polymerization of methylenecyclobutane,synthesis of an isopolyisoprene

The polymerization of methylenecyclobutane¹ in presence of LEWIS acids, and in presence of catalyst systems prepared from compounds of transition metals of Groups IV, V, VI, and VIII of the Periodic Table is discussed. The polymers obtained contained both mixed and unmixed cyclic and ethylenic structures. In cationic polymerization, cyclobutane structures predominate and coexist with structures comparable to those of a cyclised polyisoprene. With ZIEGLER-NATTA catalysts, the predominant structures are of the cyclised or uncyclised polyene type. It is only with certain transition metals of Groups IV, V, and VI, and especially with vanadium and chromium, that the polymers possess an isorubber structure, in which the C?C double bonds are in the exo position with respect to the chain. This isorubber cannot be obtained directly from an acyclic ethylenic monomer. It is also true that this isorubber is not obtained by simple opening of the small methylenecyclobutane ring; the exo methylene group of the monomer is different from that which appears in the structural unit of the polymer, because a ?non-classical”? alkyl bicyclobutonium ion takes part in the polymerization process.     

Analogy and solution scattering modelling: new structural strategies for the multidomain proteins of complement, cartilage and the immunoglobulin superfamily

Summary: Many immunologically relevant proteins possess multidomain structures. Molecular structures both at the level of the individual domain and that of the intact protein are required for a full appreciation of function and control. Two recently developed structural approaches are reviewed here. Analogy modelling methods are based on the current understanding of many protein structures, and make possible the identification of folds for superfamilies of unknown structures. An integrated multidisciplinary predictive approach has been successfully applied to the von Willebrand factor type A, proteoglycan tandem repeat and factor I/membrane attack complex domains. The available experimental and predictive evidence is assembled in order to identify a known three-dimensional structure related to the unknown one of interest. Neutron and X-ray scattering curve modelling provides information on the full multidomain structure in solution. As scattering curves can be calculated from known atomic structures, the present availability of structures for many domains in conjunction with tight constraints based on these structures and the covalent connections between them results in a small family of allowed best-fit structures for a given scattering curve. The curve-fit procedure can be automated, and whole multidomain structures can be determined to a positional precision of the order of 0.2–1 nm. Such models are informative on the steric accessibility of each domain and their functional activity, and this is illustrated for antibody, cell-surface and complement proteins.     

Ultrastructural,histochemical, and freeze-fracture evaluation of multilamellated structures in human pulmonary alveolar proteinosis

Ultrastructural, histochemical, and freeze-fracture studies of material recovered by bron-choalveolar lavage from patients with pulmonary alveolar proteinosis revealed four types (A, B, C, and D) of multilamellated structures (MS). Type A, the major component, consisted of concentric, trilaminar structures which were composed of two electron-dense layers and a central lucent layer (5.7–7.5 nm in overall width) alternating with wider (25–30 nm) electron-lucent intervening layers. Type B MS were formed by concentric lamellae with a 5–5.3-nm periodicity. Type C MS were composed of wavy, electron-dense lamellae with a 4–4.5-nm periodicity. Type D MS were conglomerated masses of intricately arranged double or triple electron-dense layers (7.5–13.5 nm wide) alternating with wider (30–40-nm) electron-lucent layers. The electron-dense lamellae of type A, type C, and type D MS were stained with ruthenium red, the Thiéry method, and concanavalin A, indicating the presence of carbohydrate components. Freeze-fracture studies revealed smooth inner and outer surfaces in type A MS, with the fracture planes passing through the central parts of the trilaminar structures; the intervening layers contained 10-nm particles, which probably are proteins. Type B MS had smooth surfaces, and type C MS had slightly particulate surfaces; while type D MS showed tubular or polygonal structures, 350 nm wide, with rows of particles 7–8 nm in diameter. It is concluded that type A and type D MS contain proteins and carbohydrates, probably in the form of glycoproteins, as well as phos-pholipids, and are related to tubular myelin. Type B and type C MS are considered to contain mainly phos-pholipids; type C MS are also considered to contain carbohydrates and to be related to lamellar bodies of type II alveolar epithelial cells.     

Histamine in the rabbit eye: Distribution,synthesis, catabolism,and changes by light stimulation

Histamine (HI) is present in all studied ocular (retina, choroid, optic nerve) and brain structures of the albino rabbit. HI levels in neural eye elements (retina and optic nerve) are relatively low, i.e 70–140 ng/g tissue, and comparable with those found in the brain; a typical vascular tissue, i.e. choroid, contained approximately 10 times more HI. Histadine decarboxylase (HD) activity was found only in brain tissue, while histamine-methyltransferase (HMT) activity was present in all the eye and brain structures. Light stimulation produced changes in HI content only in the retina (decrease) and in the optic nerve (increase).     

Clamp ultrastructure of the basal monogenean Chimaericola leptogaster (Leuckart, 1830) (Polyopisthocotylea: Chimaericolidae)

The ultrastructure of the haptoral clamps of the chimaericolid monogenean Chimaericola leptogaster, a basal polyopisthocotylean from the gills of a holocephalan fish, is described. These clamps are characterized by the presence of two muscle blocks interrupted mid-anteriorly and mid-posteriorly and different kinds of hard structures: a single median and paired lateral sclerites embedded in the clamp wall; six spine-like structures directed towards the clamp lumen; and electron dense surface structures along the internal surface of the anterior clamp lips and along the luminal surface of the tegument of the clamp lumen. The lateral sclerites are situated deep within muscular tissue and are closely bounded by radial myofibrils, possessing a uniform electron dense matrix within which are hollow areas of different sizes. The median sclerite occupies an area between the clamp wall myofibrils and the luminal epithelium, is surrounded by a basement lamina and is composed of a heterogeneous matrix comprising two different morphological layers related to variations in the type and concentration of fibrils. Four of the spine-like structures are extensions of the margins of the two spindle-like muscle blocks in the clamps, i.e. the two anterior and two posterior structures, and the two others are situated at the lateral constrictions of the left and right muscle blocks. The electron dense surface structures are derivations of the clamp tegument or, to be more precise, its outer, densely fibrous region. These results are discussed in relation to the evidence that the haptoral clamps of C. leptogaster are apparently ancient origin.     

甲壳类动物4种过敏原的序列分析、抗原表位预测及三维结构建模

目的探明甲壳类动物各种过敏原之间是否存在相似性,以期深入研究甲壳类食品过敏原的构效关系。方法应用生物信息学方法,分析预测了甲壳类动物的4种过敏原—原肌球蛋白(TM)、精氨酸激酶(AK)、肌球蛋白轻链(MLC)和肌质钙结合蛋白(SCP)的二级结构、亲水性、可塑性、抗原性、表面可及性、线性抗原表位和三维结构等。结果 TM为超螺旋结构,而AK、MLC和SCP均为复合蛋白,含有较多的Turn和Coil结构;TM、AK、MLC和SCP 4种过敏原的亲水性区域均在60%以上,可塑性区域约为50%,抗原性区域均在60%以上。TM、AK、MLC和SCP分别有11、10、4和4个线性抗原表位。TM、AK、MLC和SCP的三维结构建模结果与相应的二级结构预测结果一致,基本能够反映此4种过敏原的空间构象。结论通过生物信息学方法分析,同时获得了甲壳类动物4种过敏原TM、AK、MLC和SCP的分子特征、抗原表位及部分三维结构,可望为进一步采用实验方法研究其构效关系奠定理论基础。     

The engineering of patient-specific,anatomically shaped,digits

It is now recognized that geometric structures of scaffolds at several size levels have profound influences on cell adhesion, viability, proliferation and differentiation. This study aims to develop an integrated process to fabricate scaffolds with controllable geometric structures at nano-, micro- and macro-scales. A phase-separation method is used to prepare interconnected poly(l-lactide) (PLLA) nanofibrous (NF) scaffolds. The pore size of the NF scaffold at the scale of several hundred micrometers is controlled by the size of porogen, paraffin spheres. At millimeter scale and above, the overall shape of the scaffold is defined by a wax mold produced using a three-dimensional printer. The printer utilizes a stereo lithographic file generated from computed tomographic files retrieved from the National Library of Medicine's Visual Human Project. NF PLLA scaffolds with a human digit shape are successfully prepared using this process. Osteoblast cell line MC3T3-E1 cells are then seeded and cultured in the prepared scaffolds. Cell proliferation, differentiation and biomineralization are characterized to demonstrate the suitability of the scaffolds for the digit bone tissue engineering application.     

Hidradenitis Suppurativa of the Perineum, Scrotum, and Gluteal Area: Presentation, Complications, and Treatment

Hidradenitis suppurativa is an infrequent inflammatory process that begins as an infection in the apocrine sweat glands. From an initial focus, the infection spreads to involve other tissues of the skin and adjacent structures. When inadequately treated or neglected, the disease becomes chronic with suppuration, sinus formation, invasion of adjacent organs, and occasional malignant degeneration. Social and occupational dislocations are the rule. The peak incidence of the disease is in the third and fourth decades. Blacks and women are most often affected.     

Effect of psychotropic drugs (chlorpromazine,majeptil, trisedil) on protein synthesis in various parts of the rat brain

Incorporation of methionine-S³⁵ into total proteins isolated from various parts of the brain after a single injection of chlorpromazine, majeptil, and trisedil was investigated in experiments on rats. Generalized depression of protein synthesis in all structures except the medulla was observed 1 and 3 h after injection of chlorpromazine. In most experiments majeptil gave a stimulant effect. The action of trisedil was accompanied by reduced incorporation of methionine-S³⁵ into proteins of most brain structures and increased incroporation in the olfactory lobes. It is postulated that changes in protein synthesis in individual brain structures are an important step in the mechanism of action of psychotropic drugs.     

Photochemical cross-linking for collagen-based scaffolds: a study on optical properties, mechanical properties, stability, and hematocompatibility

Collagen presents an attractive biomaterial for tissue engineering because of its excellent biocompatibility and negligible immunogenicity. However, some intrinsic features related to the mechanical stability and thrombogenicity limit its applications in orthopedic and vascular tissue engineering. Photochemical cross-linking is an emerging technique able to stabilize tissue grafts and improve the physicochemical properties of collagen-based structures. However, other important properties of collagen-based structures and the effect of processing parameters on these properties have not been explored. In this study, we aim to investigate the dose dependence of tensile and swelling properties on two parameters, namely, laser energy fluence and rose Bengal photosensitizer concentration. We also study the compression properties using cyclic compression test, long-term stability using subcutaneous implantation, and hematocompatibility using platelets adhesion test, of cross-linked collagen structures. Moreover, because limited optical penetration in turbid media is the major obstacle for light-based techniques, we also characterize the optical properties, which partially determine the effective optical penetration depth in collagen gel samples, during photochemical cross-linking. Laser energy fluence and rose Bengal concentration are important parameters affecting the cross-linking efficiency, which was characterized as the mechanical and the swelling properties, in a dose-dependent manner. Under the experimental conditions in this study, the peak fluence was 12.5 J/cm2 and the minimal rose Bengal concentration for effective cross-linking was >0.00008% (0.786 micromol). Photochemical cross-linking also enhanced the compression strength and long-term stability of collagen structures without compromising the tissue compatibility. Furthermore, photochemical cross-linking reduced platelet adhesion and abolished fibrin mesh formation, thereby improving the hematocompatibility of collagen structures. These results suggest the feasibility of using the photochemically cross-linked collagen structures for orthopedic and vascular tissue engineering. Finally, the effective optical penetration depth in collagen gel samples is wavelength and rose Bengal concentration dependent, and was approximately 12 mm at 514 nm at 0.001% (9.825 micromol), the rose Bengal concentration mostly used in this study.