Flt3 Signaling in B Lymphocyte Development and Humoral Immunity

The Class III receptor tyrosine kinase Flt3 and its ligand, the Flt3-ligand (FL), play an integral role in regulating the proliferation, differentiation, and survival of multipotent hematopoietic and lymphoid progenitors from which B cell precursors derive in bone marrow (BM). More recently, essential roles for Flt3 signaling in the regulation of peripheral B cell development and affinity maturation have come to light. Experimental findings derived from a multitude of mouse models have reinforced the importance of molecular and cellular regulation of Flt3 and FL in lymphohematopoiesis and adaptive immunity. Here, we provide a comprehensive review of the current state of the knowledge regarding molecular and cellular regulation of Flt3/FL and the roles of Flt3 signaling in hematopoietic stem cell (HSC) activation, lymphoid development, BM B lymphopoiesis, and peripheral B cell development. Cumulatively, the literature has reinforced the importance of Flt3 signaling in B cell development and function. However, it has also identified gaps in the knowledge regarding Flt3-dependent developmental-stage specific gene regulatory circuits essential for steady-state B lymphopoiesis that will be the focus of future studies.     

Identification of Structural and Molecular Signatures Mediating Adaptive Changes in the Mouse Kidney in Response to Pregnancy

Pregnancy is characterized by adaptations in the function of several maternal body systems that ensure the development of the fetus whilst maintaining health of the mother. The renal system is responsible for water and electrolyte balance, as well as waste removal. Thus, it is imperative that structural and functional changes occur in the kidney during pregnancy. However, our knowledge of the precise morphological and molecular mechanisms occurring in the kidney during pregnancy is still very limited. Here, we investigated the changes occurring in the mouse kidney during pregnancy by performing an integrated analysis involving histology, gene and protein expression assays, mass spectrometry profiling and bioinformatics. Data from non-pregnant and pregnant mice were used to identify critical signalling pathways mediating changes in the maternal kidneys. We observed an expansion of renal medulla due to proliferation and infiltration of interstitial cellular constituents, as well as alterations in the activity of key cellular signalling pathways (e.g., AKT, AMPK and MAPKs) and genes involved in cell growth/metabolism (e.g., Cdc6, Foxm1 and Rb1) in the kidneys during pregnancy. We also generated plasma and urine proteomic profiles, identifying unique proteins in pregnancy. These proteins could be used to monitor and study potential mechanisms of renal adaptations during pregnancy and disease.     

Electrodeposition of copper into high aspect ratio PCB micro-via using megasonic agitation

This paper presents the use of micro-particle imaging velocimetry (micro-PIV) to analyse fluid flow and hence ion replenishment in PCB micro-via during the electroplating process. The cross section of a PCB via is fabricated in PMMA to allow optical access to the sample. Fluid flow within two 1:1 aspect ratio blind micro-vias, one with straight side walls and the other with tapered side walls were compared. Flow is also analysed in a 1:1 aspect ratio through via. Flow rates measured using micro-PIV are used to validate simulated flow models. The results show that there are increased flow rates within the blind via with tapered side walls. This goes some way to explaining the improved electroplating results obtained in industry when tapered vias are used. Initial experimental results using megasonic streaming to remove bubbles from blind micro-via and promote ion transportation within high aspect ratio PCB micro-via to enhance electrodeposition are also reported.     

Examining Factors That Influence the Effectiveness of Learning Objects in Mathematics Classrooms

Abstract

Learning objects are interactive online tools that support the acquisition of specific concepts. Limited research has been conducted on factors that affect the use of learning objects in K–12 mathematics classrooms. The current study examines the influence of student characteristics (gender, age, computer comfort level, subject comfort level, and mathematics grade), instructional design (structured vs. open ended), and teaching strategy (teacher led vs. student based) on student attitudes toward the use of learning objects and learning performance. Data in the form of surveys and pre- and posttests were collected from 286 middle and secondary school students. Higher computer and subject area comfort ratings were significantly correlated with more positive student attitudes about learning objects. Older students in higher grades learned more than younger students in lower grades after using learning objects. Learning performance was significantly higher for students who used structured (vs. open-ended) learning objects and participated in teacher-led (vs. student-based) lessons. It is speculated that younger students might need more scaffolding when using mathematics-based learning objects.     

Rat behavior in go/no-go and two-alternative choice odor discrimination: Differences and similarities.

To elucidate the cognitive structures of animals, neuroscientists use several behavioral tasks. Therefore, it is imperative to have a firm understanding of each task's behavioral parameters in order to parse out possible task effects. We compare two operant discrimination tasks (Go/No-Go: GNG; Two-Alternative Choice: TAC) that are commonly used in olfactory research. Past research has suggested that solving the two tasks requires divergent cognitive strategies. One hypothesis is that the two tasks differ in how an animal optimizes reward rate by means of a speed–accuracy trade-off (SAT). If this is true, then changing tasks could give researchers an additional tool to understand animal cognition. However, no study has systematically analyzed the two tasks in parallel using odor stimuli. Using standardized training protocols, we test GNG and TAC in parallel. Our protocols allow us to isolate the stimulus sampling period from a general reaction time period. We find that the two tasks do not differ with regard to the stimulus sampling period and conclude that the two tasks do not differ in the amount of time it takes an animal to perform a discrimination. Instead, tasks differ in the time it takes to make an overt behavioral response, with GNG showing shorter periods than TAC. We also find no evidence of rats using either task-specific or intertrial interval-dependent SAT schema in order to optimize reward rate. We show that similarities between dependent variables, with the possible exception of response delay, appear to be under experimenter control. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Project affinity: the role of emotional attachment in construction projects

Although a wide range of human and organizational factors have been found to be important in the operation of projects, those determined by cultural variables are less well defined. One such influence concerns the notion of ‘project affinity’, the commitment and attachment by stakeholders and participants to projects and their outcomes. The temporal nature and transient involvement context provided by construction projects arguably presents a climate in which many participants are less likely to display commitment to its goals. This note is concerned with the issue of whether an attachment to a project's goals or to the completed product can lead to improved commitment among those involved. The concept of project affinity was developed in the course of a case study investigation in which operatives' attitudes towards the construction of a cancer research facility were explored. Because of the contribution of the facility to the future care of cancer sufferers, the concept of project affinity proved helpful in understanding a factor that appeared to be influencing the commitment of those involved. The results suggest a complementary concept to that of ‘project chemistry’ (c.f. Nicolini, 2002 Nicolini, D. 2002. In search of ‘project chemistry’.. Construction Management and Economics, 20: 167–77.  ).     

Photo-vulcanization using thiol-ene chemistry: Film formation,morphology and network characteristics of UV crosslinked rubber latices

The photo-vulcanization with versatile thiol-ene chemistry represents an innovative approach to crosslink diene-rubber materials both in latex and in solid film state. In this work, the structure of elastomer-based thiol-ene networks and the morphology after film formation are studied in detail using electron microscopic techniques, atomic force microscopy and multiple-quantum solid-state NMR spectroscopy. Additionally, film formation properties and corresponding macroscopic properties of photo-vulcanized natural rubber (NR) latex and its synthetic counterpart, isoprene rubber (IR) latex, are determined in dependence on the curing procedure (pre- and post-vulcanization). The results reveal that thiol-ene cured elastomers comprise homogenously distributed crosslinks with a low amount of short chain defects. Whilst photochemically pre-cured NR latex particles provide coherent films, the film formation and mechanical properties of IR are strongly governed by the crosslink density of the latex particles. In film state, photo-vulcanization promotes narrow crosslink distributions and excellent tensile properties of both NR and IR.     

Anthocyanins remain stable during commercial blackcurrant juice processing

Abstract: It remains important to establish the stability of anthocyanins throughout commercial processing in order to maintain the bioactivity of the processed food/s. The present study aimed to assess the recovery and formation of anthocyanins and their free phenolic acid degradation products during the commercial processing of blackcurrant juice concentrate. A bench‐scale processing model was also established to allow for alteration of predefined parameters to identify where commercial processes could be modified to influence anthocyanin yield. No significant loss in anthocyanins was observed throughout the commercial processing of blackcurrants, from whole berry through milling, to pectin hydrolysis and sodium bisulphite addition (P ≥ 0.7). No significant loss in anthocyanins was observed following the subsequent processing of pressed juice, through pasteurization, decantation, filtration, and concentration (P ≥ 0.9). Similarly, the bench‐scale model showed no significant losses in anthocyanin content except during pasteurization (22%± 0.7%, P < 0.001). In the full‐factorial Design of Experiment model analysis, only sodium bisulphite concentration had an impact on anthocyanin recovery, which resulted in an increase (23% to 27%; P < 0.001) in final anthocyanin concentration. No phenolic degradation products (free protocatechuic acid or gallic acid derived from cyanidin and delphinin species, respectively) were identified in any processed sample when compared to authentic analytical standards, analyzed by ultra‐performance liquid chromatography DAD. Practical Application: This article provides crucial data directly applicable to commercial juice processing, such as improving anthocyanin yield and practical considerations for anthocyanin stability and degradation. This aspect is particularly pertinent considering the current commercial interest in anthocyanin‐derived phenolic acids and their health‐related benefits. Further research and development targets in the area of commercial juice product development are identified.