It is generally accepted that angiogenesis is delayed in aging. To define the effects of age on the neovascular response, polyvinyl alcohol sponges were implanted SC in young (6-8 months old, n ϭ 11) and aged (23-25 months old, n ϭ 13) mice and sampled at 14 and 19 days. Angiogenic invasion was significantly delayed in aged mice at 14d relative to young at 14d (% area of invasion 9.0 Ϯ 3.7 vs 19.0 Ϯ 5.6; p ϭ 0.02). Although microvessel morphology and basement membrane composition were similar between the age groups, a significant decrease in capillary density was noted in aged tissues at 14d (7.5 Ϯ 4.1) and 19d (12.1 Ϯ 2.8) relative to young at 14d (18.7 Ϯ 2.3) (p Ͻ 0.01 A14d vs Y14d). In comparison to young at 14d, the inflammatory response was decreased by 43 Ϯ 2.9% and 36 Ϯ 7.8% in aged mice at 14d and 19d, respectively. Tissues of aged mice showed less newly deposited collagen. There was a lack of expression of transforming growth factor-␤ 1 (TGF-␤ 1) and vascular endothelial growth factor (VEGF) in aged mice at 14d (0.63 Ϯ 0.3) and 19d (1.14 Ϯ 0.5) vs young at 14d (1.92 Ϯ 0.5) (p Յ 0.01 A14d vs Y14d for VEGF). However, similar production of VEGF receptor2 was observed. In contrast to young mice, there was significantly increased expression of thrombospondin-2 (TSP-2) in aged mice from 14d (14.6 ϫ 10 3 Ϯ 7.3 ϫ 10 3) to 19d (34.9 ϫ 10 3 Ϯ 17 ϫ 10 3). We conclude that angiogenesis in aging is not merely delayed, but is altered due to multiple impairments.

This article considers the precision positioning problem associated with high-speed operation of the Atomic Force Microscope (AFM), and presents an inversion-based control approach to achieve precision positioning. Although AFMs have high (nanoscale) spatial resolution, a problem with current AFM systems is that they have low temporal resolution, i.e., AFM imaging is slow. In particular, current AFM imaging cannot be used to provide three-dimensional, time-lapse images of fast processes when imaging relatively-large, soft samples. For instance, current AFM imaging of living cells takes 1-2 minutes (per image frame) -such imaging speeds are too slow to study rapid biological processes that occur in seconds, e.g., to investigate the rapid movement of cells or the fast dehydration and denaturation of collagen. This inability, to rapidly image fast biological processes, motivates our current research to increase the operating speed of the AFM. We apply an inversionbased feedback/feedforward control approach to overcome positioning problems that limit the operating speed of current AFM systems. The efficacy of the method, to achieve high-speed AFM operation, is experimentally evaluated by applying it to image collagen samples.

Qatar has a high burden of chronic diseases including obesity, cardiovascular disease and type 2 diabetes mellitus. Low serum vitamin D levels have been implicated in the development and progression of a range of these chronic conditions. The prevalence of vitamin D insufficiency or deficiency in the general population of Qatar has still not been investigated. The aim of this study was to carry out a systematic review of published studies documenting the prevalence of vitamin D insufficiency or deficiency in the Qatari population. A search strategy was developed for online databases (PubMed, Ovid MEDLINE, Embase and Embase Classic) between 1980 to the last week of August 2012, and bibliographies of the included studies were further searched for additional reports. Search terms used were QATAR and VITAMIN D. Studies reporting the serum levels of vitamin D in several Qatari sub-populations were identified. Weighted-average vitamin D serum levels and prevalence of low vitamin D status (<75 nmol/L) were calculated. Subgroup analysis was carried out by age. The quality of each study was evaluated according to four criteria: national representativeness, representation of males and females, the sample size, and the sampling protocol. A total of 16 relevant publications were identified, and 8 of these (reporting from 7 unique studies) met our inclusion and exclusion criteria with a total number of 1,699 Qatari subjects. The pooled sample size weighted-average vitamin D concentration (±SD) was 45.3±14.3 nmol/L (95% CI: 44.6-46.0; range 29.2-66.9 nmol/L). The weighted-average prevalence of low vitamin D status was 90.4% (95% CI: 90.1-91.0; range 83%-91%). Age was inversely correlated with vitamin D levels and directly with its insufficiency/deficiency prevalence. There have only been a few studies on the prevalence of low vitamin D in Qatar a very high prevalence of vitamin D insufficiency/deficiency in Qatar that increases with age has been suggested. The present report underlines the need to develop a nationally representative study to further evaluate vitamin D status in Qatar. Given the growing evidence of the role of vitamin D in chronic disease, this study could help develop public health strategies for disease prevention in Qatar.

ABSTRACTΤhe extreme weather conditions in Middle East Area led to the construction of tightly sealed, air conditioned buildings, characterized by indoor air quality deterioration. This study presents the results of chemical characterization of outdoor and indoor PM 2.5 and PM 10 in Doha city, over a two-month period including normal days and dust events, aiming at identifying the factors affecting the indoor air of an office building. The WHO guideline values were exceeded in 100% of the outdoor measurements. 49% of the days of the sampling campaign were characterized as non-dusty (PM 10 < 200 µg m ). The contribution of both dust and anthropogenic emissions sources is depicted in particles' mass and chemical composition. The elevated -especially outdoor-levels of carbonate carbon indicate the presence of crustal matter originating from the surrounding crustal material. OC/EC values reveal possible combined contribution from secondary organic aerosol, trafficrelated sources and re-suspended dust. The influence of anthropogenic emissions is implied by the predominance of nitrate and sulfate ions, which constitute a substantial percentage of the particle mass. The crustal origin of particles is also depicted in metals. However, the higher enrichment factor values which may imply anthropogenic activities of both the outdoor and indoor environment were determined sequentially for Cd, Pb, As, Cu and Zn, suggesting the role of infiltration. Concluding, the indoor to outdoor relationship is significantly influenced by particles infiltration and penetration into the building mainly through the ventilation system and to a lesser extent, through windows or cracks in the building envelope. Although the low indoor to outdoor ratio underlies the predominance of outdoor levels compared to the indoor ones, there is positive correlation between indoor and outdoor PM, during the days that the building was open to the public and employees.

Factors responsible for age-associated impairment of angiogenesis are poorly understood. We observed that in aged mice, new fibrovascular tissue within subcutaneous polyvinyl alcohol sponges expressed more tissue inhibitor of metalloproteinases (TIMP)-2 than did corresponding tissue from young mice. In complementary studies in vitro, we utilized young and aged human microvascular endothelial cell lines (hmEC36 and hmEC90, respectively) and compared their morphogenetic capacity within three-dimensional collagen. HmEC90 exhibited poor formation of tubular, capillary-like structures in vitro, diminished expression of active matrix metalloproteinase (MMP)-2, and similar or lesser amounts of MT1-MMP relative to hmEC36. Correspondingly, the MMP inhibitor GM6001 decreased tubulogenesis by hmEC36 to levels observed for hmEC90. In vitro, hmEC90 expressed similar quantities of TIMP-1, but more TIMP-2 than did hmEC36. Accordingly, purified TIMP-2 inhibited tubulogenesis by hmEC36. Collectively, our studies indicate that elevated levels of TIMP-2 modulate decreased angiogenesis in aged tissues, most likely via TIMP-2-mediated inhibition of MMP-2 and MT1-MMP.