Hypertension and Cognitive Functioning: A Perspective in Historical Context

Our objective is to characterize the development of the literature on hypertension and cognitive functioning from a historical perspective. This goal was stimulated by the review on “Historical Trends and Milestones in Hypertension Research” in the October 2012 issue of Hypertension. Our specific aims are threefold: (1) to trace and describe the history of this area of research; (2) to identify milestones in knowledge and methods; and (3) to discuss briefly how this literature translates into patient care. The topic is of major relevance to research and practice because hypertension is a well-known risk factor for decline in cognitive performance within the normal range of cognitive functioning, mild cognitive impairment (MCI) and dementia. It is important to emphasize 3 features of the review: (1) it is not designed as a critical review of the literature, but rather to describe the historical influences on our current knowledge base (poor, mediocre and outstanding papers from the past have all shaped our present); (2) word-count limitations require that we omit statistical detail except to emphasize effect sizes in pivotal papers; and (3) each milestone topic is addressed by noting the earliest work then followed by examples of papers representing pivotal events. A number of comprehensive re- views of this literature are available, including a seminal paper summarizing the formative years of this research. Please see http://hyper.ahajournals.org for citations to additional reviews of the literature and papers published in Hypertension. We recognize the importance of the emerging literature on hypotension and cognitive function, but refer the readers to previous reviews which include this topic

Nutrition Education Resources in North Carolina–Based Head Start Preschool Programs: Administrator and Teacher Perceptions of Availability and Use

Objective: The purpose of this study was to provide new insight into common barriers to the availability and use of nutrition education (NE) resources in Head Start preschool programs based on administrator and teacher perceptions. Methods: In-depth, semistructured phone interviews (n = 63) were conducted with administrators (n = 31) and teachers (n = 32) from North Carolina–based Head Start programs. Interviews were audio-recorded and transcribed verbatim. Data were analyzed qualitatively using content analysis to identify common themes. Results: Five emergent themes were identified within the areas of NE resource availability and use and barriers to NE resource availability and use. Participants expressed desire for greater organization of existing NE material resources, increased community support, and professional development opportunities for teachers specific to NE. Funding and time constraints were reported as affecting NE resources. Conclusions and Implications: Creative strategies for addressing NE resource availability and use and barriers (e.g., NE integration with educational standards) in Head Start are needed

Molecular Signatures of Proliferation and Quiescence in Hematopoietic Stem Cells

Stem cells resident in adult tissues are principally quiescent, yet harbor enormous capacity for proliferation to achieve self renewal and to replenish their tissue constituents. Although a single hematopoietic stem cell (HSC) can generate sufficient primitive progeny to repopulate many recipients, little is known about the molecular mechanisms that maintain their potency or regulate their self renewal. Here we have examined the gene expression changes that occur over a time course when HSCs are induced to proliferate and return to quiescence in vivo. These data were compared to data representing differences between naturally proliferating fetal HSCs and their quiescent adult counterparts. Bioinformatic strategies were used to group time-ordered gene expression profiles generated from microarrays into signatures of quiescent and dividing stem cells. A novel method for calculating statistically significant enrichments in Gene Ontology groupings for our gene lists revealed elemental subgroups within the signatures that underlie HSC behavior, and allowed us to build a molecular model of the HSC activation cycle. Initially, quiescent HSCs evince a state of readiness. The proliferative signal induces a preparative state, which is followed by active proliferation divisible into early and late phases. Re-induction of quiescence involves changes in migratory molecule expression, prior to reestablishment of homeostasis. We also identified two genes that increase in both gene and protein expression during activation, and potentially represent new markers for proliferating stem cells. These data will be of use in attempts to recapitulate the HSC self renewal process for therapeutic expansion of stem cells, and our model may correlate with acquisition of self renewal characteristics by cancer stem cells

Reversible binding of platelet-derived growth factor-AA, -AB, and -BB isoforms to a similar site on the "slow" and "fast" conformations of alpha 2-macroglobulin.

The mechanism by which the platelet-derived growth factor (PDGF)-binding protein, alpha 2-macroglobulin (alpha 2M), modulates PDGF bioactivity is unknown, but could involve reversible PDGF-alpha 2M binding. Herein we report that greater than 70% of 125I-PDGF-BB or -AB complexed to alpha 2M was dissociated by SDS-denaturation followed by SDS-polyacrylamide gel electrophoresis, i.e. most of the binding was noncovalent. Reduction of the PDGF.alpha 2M complex following denaturation dissociated the cytokine from alpha 2M by greater than 90%, suggesting covalent disulfide bond formation. Approximately 50% of the growth factor was dissociated by lowering the pH from 7.5 to 4.0. 125I-PDGF-BB bound alpha 2M in a time-dependent manner (t1/2 = approximately 1 h), reaching equilibrium after 4 h. The 125I-PDGF.BB/alpha 2M complex dissociated more slowly (t1/2 = approximately 2.5 h). "Slow" and "fast" alpha 2M bound nearly equal amounts of PDGF-AB or -BB. Trypsin treatment converted PDGF-BB/alpha 2M complex to the fast conformation but did not release bound 125I-PDGF-BB. All PDGF-isoforms (AA, -AB, and -BB) competed for binding with 125I-PDGF-BB binding to slow alpha 2M and fast alpha 2M-methylamine by 65-80%. Other cytokines that bind alpha 2M (transforming growth factor-beta 1 and -beta 2, tumor necrosis factor-alpha, basic fibroblast growth factor, interleukin -1 beta, and -6) did not compete for 125I-PDGF-BB binding slow alpha 2M, but transforming growth factor-beta 1 and basic fibroblast growth factor inhibited 125I-PDGF-BB binding alpha 2M-methylamine by 30-50%. The reversible nature of the PDGF.alpha 2M complex could allow for targeted PDGF release near mesenchymal cells which possess PDGF receptors

Macroalgal meadow habitats support fish and fisheries in diverse tropical seascapes

Ecosystems are linked by the movement of organisms across habitat boundaries and the arrangement of habitat patches can affect species abundance and composition. In tropical seascapes many coral reef fishes settle in adjacent habitats and undergo onto-genetic habitat shifts to coral reefs as they grow. Few studies have attempted to measure at what distances from nursery habitats these fish migrations (connectivity) cease to exist and how the abundance, biomass and proportion of nursery species change on coral reefs along distance gradients away from nursery areas. The present study examines seascape spatial arrangement, including distances between habitats, and its con-sequences on connectivity within a tropical seascape in Mozambique using a seascape ecology approach. Fish and habitat surveys were undertaken in 2016/2017 and a thematic habitat map was created in ArcGIS, where cover and distances between habitat patches were calculated. Distance to mangroves and seagrasses were significant predictors for abundance and biomass of most nursery species. The proportions of nursery species were highest in the south of the archipelago, where mangroves were present and decreased with distance to nurseries (mangroves and seagrasses). Some nursery species were absent on reef sites farthest from nursery habitats, at 80 km from mangroves and at 12 km from seagrass habitats. The proportion of nursery/non-nursery snapper and parrotfish species, as well as abundance and biomass of seagrass nursery species abruptly declined at 8 km from seagrass habitats, indicating a threshold distance at which migrations may cease. Additionally, reefs isolated by large stretches of sand and deep water had very low abundances of several nursery species despite being within moderate distances from nursery habitats. This highlights the importance of considering the matrix (sand and deep water) as barriers for fish migration

Thresholds in seascape connectivity: the spatial arrangement of nursery habitats structure fish communities on nearby reefs

Ecosystems are linked by the movement of organisms across habitat boundaries and the arrangement of habitat patches can affect species abundance and composition. In tropical seascapes many coral reef fishes settle in adjacent habitats and undergo ontogenetic habitat shifts to coral reefs as they grow. Few studies have attempted to measure at what distances from nursery habitats these fish migrations (connectivity) cease to exist and how the abundance, biomass and proportion of nursery species change on coral reefs along distance gradients away from nursery areas. The present study examines seascape spatial arrangement, including distances between habitats, and its consequences on connectivity within a tropical seascape in Mozambique using a seascape ecology approach. Fish and habitat surveys were undertaken in 2016/2017 and a thematic habitat map was created in ArcGIS, where cover and distances between habitat patches were calculated. Distance to mangroves and seagrasses were significant predictors for abundance and biomass of most nursery species. The proportions of nursery species were highest in the south of the archipelago, where mangroves were present and decreased with distance to nurseries (mangroves and seagrasses). Some nursery species were absent on reef sites farthest from nursery habitats, at 80 km from mangroves and at 12 km from seagrass habitats. The proportion of nursery/non-nursery snapper and parrotfish species, as well as abundance and biomass of seagrass nursery species abruptly declined at 8 km from seagrass habitats, indicating a threshold distance at which migrations may cease. Additionally, reefs isolated by large stretches of sand and deep water had very low abundances of several nursery species despite being within moderate distances from nursery habitats. This highlights the importance of considering the matrix (sand and deep water) as barriers for fish migration

Seascape configuration leads to spatially uneven delivery of parrotfish herbivory across a Western Indian Ocean seascape

Spatial configuration of habitat types in multihabitat seascapes influence ecological function through links of biotic and abiotic processes. These connections, for example export of organic matter or fishes as mobile links, define ecosystem functionality across broader spatial scales. Herbivory is an important ecological process linked to ecosystem resilience, but it is not clear how herbivory relates to seascape configuration. We studied how herbivory and bioerosion by 3 species of parrotfish were distributed in a multi-habitat tropical seascape in the Western Indian Ocean (WIO). We surveyed the abundance of three species with different life histories—Leptoscarus vaigiensis (seagrass species), Scarus ghobban (juvenile-seagrass/adults-reefs) and Scarus rubroviolaceus (reef species) —in seagrass meadows and on reefs and recorded their selectivity of feeding substrate in the two habitats. Herbivory rates for L. vaigiensis and S. ghobban and bioerosion for S. rubroviolaceus were then modelled using bite rates for different size classes and abundance and biomass data along seascape gradients (distance to alternative habitat types such as land, mangrove and seagrass). Bioerosion by S. rubroviolaceus was greatest on reefs far from seagrass meadows, while herbivory rates by S. ghobban on reefs displayed the opposite pattern. Herbivory in seagrass meadows was greatest in meadows close to shore, where L. vaigiensis targeted seagrass leaves and S. ghobban the epiphytes growing on them. Our study shows that ecological functions performed by fish are not equally distributed in the seascape and are influenced by fish life history and the spatial configuration of habitats in the seascape. This has implications for the resilience of the system, in terms of spatial heterogeneity of herbivory and bioerosion and should be considered in marine spatial planning and fisheries management

Enhancement of perfluoropolyether boundary lubrication performance: I. Preliminary results

A ball bearing simulator operating under starved conditions was used to evaluate the boundary lubrication performance of a perfluoropolyether (PFPE) Krytox 143 AB. Several approaches to enhance boundary lubrication were studied. These included: (1) soluble boundary additives, (2) bearing surface modifications, (3) 'run-in' surface films, and (4) ceramic bearing components. In addition, results were compared with two non-perfluorinated liquid lubricant formulations. Based on these preliminary tests, the following tentative conclusions can be made: (1) substantial improvements in boundary lubrication performance were observed with a beta-diketone boundary additive and a tricresyl phosphate (TCP) liquid surface pretreatment; (2) the use of rough Si3N4 balls (Ra = 40 micro-in) also provided substantial improvement but with concomitant abrasive wear; (3) marginal improvements were seen with two boundary additives (a phosphine and a phosphatriazine) and a neat (100%) fluid (a carboxylic acid terminated PFPE); and surface pretreatments with a synthetic hydrocarbon, a PTFE coating, and TiC coated 440C and smooth Si3N4 balls (R(sub a) less than 1 micro-in); and (4) two non-PFPE lubricant formulations (a PAO and a synthetic hydrocarbon) yielded substantial improvements

A bibliometric review of financial market integration literature

We undertake a meta-literature review on the topic of financial market integration (FMI), covering 260 articles from 1981 to 2021. Our review consists of quantitative analysis of bibliometric citations concomitant with qualitative analysis of content, towards a goal of identifying primary research streams and proposing directions for future research. We identify five research groups: (1) portfolio diversification with financial market integration; (2) general equity market integration; (3) financial market linkage with respect to crises and events; (4) time-varying financial market integration; and (5) co-movements and spillovers between commodities and financial markets; as well as present a wide array of future research directions. We conduct an extensive review of FMI literature, answering several questions: (1) What is the domain of FMI research?; (2) What are the influential aspects of top journals and authors, and the characteristics of the most studied topics?; (3) What are the past and current key research streams in FMI literature?; and (4) What are the substantial future relevant research questions to explore regarding FMI? Given the ongoing attention on financial market integration by both academicians and policy makers, our results should be of great interest