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Bozeman WP, Morel BM, Black TD, Winslow JE.
Prehosp Emerg Care. 2012 Jul ;16(3):361-5.
PMID: 22510067
Abstract Background. Specially trained tactical emergency medical support (TEMS) personnel provide support to law enforcement special weapons and tactics (SWAT) teams. These programs benefit law enforcement agencies, officers, suspects, and citizens. TEMS programs are increasingly popular, but there are wide variations in their organization and operation and no recent data on their prevalence. Objective. We sought to measure the current prevalence and specific characteristics of TEMS programs in a comprehensive fashion in a single southeastern state. Methods. North Carolina emergency medical services (EMS) systems have county-based central EMS oversight; each system was surveyed by phone and e-mail. The presence and selected characteristics of TEMS programs were recorded. U.S. Census data were used to measure the population impact of the programs. Results. All of the 101 EMS systems statewide were successfully contacted. Thirty-three counties (33%) have TEMS programs providing medical support to 56 local law enforcement agencies as well as state and federal agencies. TEMS programs tend to be located in more populated urban and suburban areas, serving a population base of 5.9 million people, or 64% of the state's population. Tactical medics in the majority of these programs (29/33; 88%) are not sworn law enforcement officers. Conclusions. Approximately one-third of county-based EMS systems in North Carolina have TEMS programs. These programs serve almost two-thirds of the state's population base, using primarily nonsworn tactical medics. Comparison with other regions of the country will be useful to demonstrate differences in prevalence and program characteristics. Serial surveillance will help track trends and measure the growth and impact of this growing subspecialty field.
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Chen F.
J Theor Biol. 2012 Jun 7;302():18-28.
PMID: 22420947
The decision of individuals to engage in public avoidance during epidemics is modeled and studied using game theory. The analysis reveals that the set of Nash equilibria of the model, as well as how the equilibria compare to the social optimum, depend on the contact function that governs the rate at which encounters occur in public. If the contact ratio - defined to be the ratio of the contact rate to the number of people out in public - is increasing with the number of people out in public, then there exists a unique Nash equilibrium. Moreover, in equilibrium, the amount of public avoidance is too low with respect to social welfare. On the other hand, if the contact ratio is decreasing in the number of people out in public, then there can be multiple Nash equilibria, none of which is in general socially optimal. Furthermore, the amount of public avoidance in equilibrium with a decreasing contact ratio is too high in that social welfare can be increased if more susceptible individuals choose to go out in public. In the special case where the contact ratio does not vary with the number of people out in public, there is a unique Nash equilibrium, and it is also the socially optimal outcome.
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Huggins KN, Mathews TA, Locke JL, Szeliga KT, Friedman DP, Bennett AJ, Jones SR.
Alcohol. 2012 Jun ;46(4):371-6.
PMID: 22445804
Early childhood stress is a risk factor for the development of substance-abuse disorders. A nonhuman primate model of early life stress, social impoverishment through nursery-rearing rather than mother-rearing, has been shown to produce increased impulsive and anxiety-like behaviors, cognitive and motor deficits, and increased alcohol consumption. These behavioral changes have been linked to changes in cerebrospinal fluid (CSF) levels of 5-hydroxyindoleacetic acid (5-HIAA), a serotonin (5-HT) metabolite. The effects of different rearing conditions on ethanol drinking and three measures of 5-HT function in the central nervous system were evaluated, including CSF 5-HIAA levels and tissue levels of 5-HT and 5-HIAA in brain samples. Brain samples were taken from the dorsal caudate, putamen, substantia nigra (SN) pars reticulata, SN pars compacta and hippocampus. There was a clear effect of rearing condition on the 5-HT system. Overall 5-HIAA and 5-HIAA/5-HT ratio measures of 5-HT turnover were significantly lower in nursery reared compared to mother-reared animals. In addition, there was a strong within-subject correlation between CSF and brain tissue 5-HIAA levels. Ethanol drinking was greater in nursery reared monkeys, consistent with previous results. These findings show that CSF 5-HIAA measurements can be used to predict brain 5-HT activity that may be involved in behavioral outcomes such as anxiety and alcohol consumption. Thus, CSF sampling may provide a minimally invasive test for neurochemical risk factors related to alcohol abuse.
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Zakhem E, Raghavan S, Gilmont RR, Bitar KN.
Biomaterials. 2012 Jun ;33(19):4810-7.
PMID: 22483012
Intestinal tissue engineering is an emerging field due to a growing demand for intestinal lengthening and replacement procedures secondary to massive resections of the bowel. Here, we demonstrate the potential use of a chitosan/collagen scaffold as a 3D matrix to support the bioengineered circular muscle constructs maintain their physiological functionality. We investigated the biocompatibility of chitosan by growing rabbit colonic circular smooth muscle cells (RCSMCs) on chitosan-coated plates. The cells maintained their spindle-like morphology and preserved their smooth muscle phenotypic markers. We manufactured tubular scaffolds with central openings composed of chitosan and collagen in a 1:1 ratio. Concentrically aligned 3D circular muscle constructs were bioengineered using fibrin-based hydrogel seeded with RCSMCs. The constructs were placed around the scaffold for 2 weeks, after which they were taken off and tested for their physiological functionality. The muscle constructs contracted in response to acetylcholine (Ach) and potassium chloride (KCl) and they relaxed in response to vasoactive intestinal peptide (VIP). These results demonstrate that chitosan is a biomaterial possibly suitable for intestinal tissue engineering applications.
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Skardal A, Smith L, Bharadwaj S, Atala A, Soker S, Zhang Y.
Biomaterials. 2012 Jun ;33(18):4565-75.
PMID: 22475531
Despite recent advances in biomaterial science, there is yet no culture system that supports long-term culture expansion of human adult hepatocytes, while preserving continued function. Previous studies suggested that acellular liver extracellular matrix (ECM), employed as a substrate, improved proliferation and function of liver cells. Here we investigated whether extracts prepared from acellular liver ECM (liver ECM extract, LEE), or from whole (fresh) liver tissue (liver tissue extract, LTE), could be combined with collagen Type I, hyaluronic acid (HA), or heparin-conjugated HA (HP) hydrogels to enhance survival and functional output of primary human hepatocytes. The liver-specific semi-synthetic ECMs (sECMs) were prepared by incorporating LEE or LTE into the gel matrices. Subsequently, primary human hepatocytes were maintained in sandwich-style hydrogel cultures for 4 weeks. Progressive increase in hepatocyte metabolism was observed in all HA and HP groups. Hepatocytes cultured in HA and HP hydrogels containing LEE or LTE synthesized and secreted steady levels of albumin and urea and sustained cytochrome p450-dependent drug metabolism of ethoxycoumarin. Collectively, these results indicate that customized HA hydrogels with liver-specific ECM components may be an efficient method for expansion human hepatocytes in vitro for cell therapy and drug and toxicology screening purposes.
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Eskew EA, Price SJ, Dorcas ME.
Conserv Biol. 2012 Jun ;26(3):504-512.
PMID: 22519586
The natural flow regimes of rivers worldwide have been heavily altered through anthropogenic activities, and dams in particular have a pervasive effect on riverine ecosystems. Flow-regulation effects of dams negatively affect species diversity and abundance of a variety of aquatic animals, including invertebrates and fishes. However, the effects on semiaquatic animals are relatively unknown. We conducted anuran calling surveys at 42 study locations along the Broad and Pacolet Rivers in South Carolina to address the potential effects of flow regulation by damming on anuran occupancy and abundance. We estimated occupancy and abundance with Program PRESENCE. Models incorporated distance upstream and downstream from the nearest dam as covariates and urbanization pressure as an alternative stressor. Distance from dam was associated with occupancy of 2 of the 9 anuran species in our analyses and with abundance of 6 species. In all cases, distance downstream from nearest dam was a better predictor of occupancy and abundance than distance upstream from nearest dam. For all but one species, distance downstream from nearest dam was positively correlated with both occupancy and abundance. Reduced occupancy and abundance of anurans likely resulted from downstream alterations in flow regime associated with damming, which can lead to reduced area of riparian wetlands that serve as anuran breeding habitat. Our results showed that damming has a strong negative effect on multiple anuran species across large spatial extents and suggest that flow regulation can affect semiaquatic animals occupying riparian zones.
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Knovich MA, Farland A, Owen J.
Eur J Haematol. 2012 Jun ;88(6):518-25.
PMID: 22324373
Although significant advances in the understanding of TTP pathophysiology have been made in the last 15 yr, none have yet impacted the empiric treatment paradigm for this disease for which plasmapheresis is the mainstay. Laboratory assays for ADAMTS13 activity and inhibitors can be used to confirm a clinical diagnosis, but the assays are not routinely used to guide treatment. The routine availability of ADAMTS13 testing has allowed our group to tailor plasmapheresis and immunosuppressive therapy in patients under active treatment for TTP. In addition, the concept of establishing immune tolerance, similar to the eradication of a factor VIII inhibitor in patients with congenital or acquired hemophilia, has emerged as an important strategy to prevent early relapse of TTP. With the expected incorporation of recombinant ADAMTS13 into the treatment algorithm over the next several years, we anticipate that readily available ADAMTS13 testing will play an important role in individualized therapy that incorporates enzyme replacement and establishment of immune tolerance.
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Manoogian SJ, Bisplinghoff JA, Kemper AR, Duma SM.
J Biomech. 2012 Jun 1;45(9):1724-7.
PMID: 22542221
Given that automobile crashes are the largest single cause of death for pregnant females, scientists are developing advanced computer models of pregnant occupants. The purpose of this study is to quantify the dynamic material properties of the human uterus in order to increase the biofidelity of these models. A total of 19 dynamic tension tests were performed on pregnant human uterus tissues taken from six separate donors. The tissues were collected during full term Cesarean style deliveries and tested within 36h of surgery. The tissues were processed into uniform coupon sections and tested at 1.5strains/s using linear motors. Local stress and strain were determined from load data and optical markers using high speed video. The experiments resulted in a non-linear stress versus strain curves with an overall average peak failure true strain of 0.32±0.112 and a corresponding peak failure true stress of 656.3±483.9kPa. These are the first data available for the dynamic response of pregnant human uterus tissues, and it is anticipated they will increase the accuracy of future pregnant female computational models.
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Zhang J, Kelley KL, Marshall SM, Davis MA, Wilson MD, Sawyer JK, Farese RV, Brown JM, Rudel LL.
J Lipid Res. 2012 Jun ;53(6):1144-52.
PMID: 22460046
Acyl-CoA:cholesterol acyltransferase 2 (ACAT2) generates cholesterol esters (CE) for packaging into newly synthesized lipoproteins and thus is a major determinant of blood cholesterol levels. ACAT2 is expressed exclusively in the small intestine and liver, but the relative contributions of ACAT2 expression in these tissues to systemic cholesterol metabolism is unknown. We investigated whether CE derived from the intestine or liver would differentially affect hepatic and plasma cholesterol homeostasis. We generated liver-specific (ACAT2(L-/L-)) and intestine-specific (ACAT2(SI-/SI-)) ACAT2 knockout mice and studied dietary cholesterol-induced hepatic lipid accumulation and hypercholesterolemia. ACAT2(SI-/SI-) mice, in contrast to ACAT2(L-/L-) mice, had blunted cholesterol absorption. However, specific deletion of ACAT2 in the intestine generated essentially a phenocopy of the conditional knockout of ACAT2 in the liver, with reduced levels of plasma very low-density lipoprotein and hepatic CE, yet hepatic-free cholesterol does not build up after high cholesterol intake. ACAT2(L-/L-) and ACAT2(SI-/SI-) mice were equally protected from diet-induced hepatic CE accumulation and hypercholesterolemia. These results suggest that inhibition of intestinal or hepatic ACAT2 improves atherogenic hyperlipidemia and limits hepatic CE accumulation in mice and that depletion of intestinal ACAT2 is sufficient for most of the beneficial effects on cholesterol metabolism. Inhibitors of ACAT2 targeting either tissue likely would be beneficial for atheroprotection.
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Wood D, Wortman J.
J Pers. 2012 Jun ;80(3):665-701.
PMID: 22092250
Using data from 3 personality trait inventories and 7 samples, we show that trait items that have means near the scale midpoint and that vary more in their perceived desirability (e.g., items related to dominance, creativity, traditionalism, and organization) tend to be more stable over time, whereas items with means near the scale maximum or minimum and that vary less in their perceived desirability (e.g., items related to agreeableness, intellect, and reliability) tend to be less stable. Our findings indicate that items with means near the scale maximum or minimum have lower stabilities primarily due to having lower measurement dependability (i.e., short-term stabilities unlikely to reflect true change). However, items varying more in their desirability are more stable even after accounting for measurement dependability, consistent with the view that trait stability is facilitated in part by individuals actively working to develop in the direction they find desirable.
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Ferris MJ, Calipari ES, Mateo Y, Melchior JR, Roberts DC, Jones SR.
Neuropsychopharmacology. 2012 Jun ;37(7):1708-16.
PMID: 22395730
The dopamine transporter (DAT) is the primary site of action for psychostimulant drugs such as cocaine, methylphenidate, and amphetamine. Our previous work demonstrated a reduced ability of cocaine to inhibit the DAT following high-dose cocaine self-administration (SA), corresponding to a reduced ability of cocaine to increase extracellular dopamine. However, this effect had only been demonstrated for cocaine. Thus, the current investigations sought to understand the extent to which cocaine SA (1.5 mg/kg/inf × 40 inf/day × 5 days) altered the ability of different dopamine uptake blockers and releasers to inhibit dopamine uptake, measured using fast-scan cyclic voltammetry in rat brain slices. We demonstrated that, similar to cocaine, the DAT blockers nomifensine and bupropion were less effective at inhibiting dopamine uptake following cocaine SA. The potencies of amphetamine-like dopamine releasers such as 3,4-methylenedioxymethamphetamine, methamphetamine, amphetamine, and phentermine, as well as a non-amphetamine releaser, 4-benzylpiperidine, were all unaffected. Finally, methylphenidate, which blocks dopamine uptake like cocaine while being structurally similar to amphetamine, shared characteristics of both, resembling an uptake blocker at low concentrations and a releaser at high concentrations. Combined, these experiments demonstrate that after high-dose cocaine SA, there is cross-tolerance of the DAT to other uptake blockers, but not releasers. The reduced ability of psychostimulants to inhibit dopamine uptake following cocaine SA appears to be contingent upon their functional interaction with the DAT as a pure blocker or releaser rather than their structural similarity to cocaine. Further, methylphenidate's interaction with the DAT is unique and concentration-dependent.
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Martucci KT, Eisenach JC, Tong C, Coghill RC.
Pain. 2012 Jun ;153(6):1232-43.
PMID: 22503222
The mechanisms supporting temporal processing of pain remain poorly understood. To determine the involvement of opioid mechanisms in temporal processing of pain, responses to dynamic noxious thermal stimuli and offset analgesia were assessed after administration of naloxone, a μ-opioid antagonist, and on a separate day, during and after intravenous administration of remifentanil, a μ-opioid agonist, in 19 healthy human volunteers. Multiple end points were sampled from real-time computerized visual analog scale ratings (VAS, 1 to 10) to assess thermal sensitivity, magnitude and duration of offset analgesia, and painful after sensations. It was hypothesized that the magnitude of offset analgesia would be reduced by direct opioid antagonism and during states of acute opioid-induced hypersensitivity (OIH), as well as diminished by the presence of exogenous opioids. Surprisingly, the magnitude of offset analgesia was not altered after naloxone administration, during remifentanil infusion, or after the termination of remifentanil infusion. Because thermal hyperalgesia was observed after both drugs, 8 of the original 19 subjects returned for an additional session without drug administration. Thermal hyperalgesia and increased magnitude of offset analgesia were observed across conditions of remifentanil, naloxone, and no drug within this subset analysis, indicating that repeated heat testing induced thermal hyperalgesia, which potentiated the magnitude of offset analgesia. Thus, it is concluded that the mechanisms subserving temporal processing of nociceptive information are largely opioid-independent, but that offset analgesia may be potentiated by heat-induced thermal hyperalgesia in a proportion of individuals.
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Westwood BM, Chappell MC.
Peptides. 2012 Jun ;35(2):190-5.
PMID: 22490446
Evidence of endogenous angiotensin-(1-12) [Ang-(1-12)] may necessitate revision of the accepted view that Ang I is the immediate peptide product derived from the precursor protein angiotensinogen. As the processing of this peptide has not been fully elucidated, we characterized Ang-(1-12) metabolism in the serum and kidney of the mRen2.Lewis rat, a model of high circulating renin and ACE expression. A sensitive HPLC-based method to detect the metabolism ex vivo of low concentrations of (125)I-labeled Ang-(1-12) was utilized. Ang-(1-12) processing to serum did not reveal the participation of renin; however, serum ACE readily converted Ang-(1-12) to Ang I with subsequent metabolism to Ang II. Ang I and Ang II forming activities for serum ACE were 102±4 and 104±3fmol/ml/min serum (n=3), respectively, and both products were abolished by the potent ACE inhibitor lisinopril. The metabolism of Ang-(1-12) in renal cortical membranes also revealed the formation of Ang I; however, the main products were Ang-(1-7) and Ang-(1-4) at 129±9 and 310±12fmol/mg/min protein (n=4), respectively. Neprilysin inhibition abolished these products and substantially reduced the overall metabolism of Ang-(1-12). Incubation of Ang-(1-12) with either human or mouse neprilysin revealed identical products. We conclude that endogenous Ang-(1-12) may contribute to the expression of biologically active angiotensins through a renin-independent pathway. The preferred route for Ang-(1-12) metabolism likely reflects the relative tissue content of ACE and neprilysin.
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Simino J, Rao DC, Freedman BI.
Curr Opin Nephrol Hypertens. 2012 May 24. [Epub ahead of print]
PMID: 22614628
PURPOSE OF REVIEW: Modern molecular techniques are identifying pathways and genes involved in the pathogenesis of the complex disorder essential hypertension. This review provides an overview of genetic methodologies and recent results in the study of high blood pressure (BP), hypertension-attributed nephropathy, and related intermediate phenotypes. RECENT FINDINGS: Candidate gene studies have implicated aberrations in ion channels, ion channel regulation, aldosterone signaling, vasoconstriction and inflammation in essential hypertension; genome-wide association studies (GWAS) have detected more than 50 BP loci, most previously unsuspected in essential hypertension. Mapping by admixture linkage disequilibrium (MALD; or admixture mapping) recently led to a major breakthrough in hypertension-attributed kidney disease in African Americans, demonstrating the role of the apolipoprotein L1 (APOL1) and nonmuscle myosin heavy chain 9 (MYH9) genes in this primary kidney disease residing in the spectrum of focal segmental glomerulosclerosis. GWAS have detected associations between kidney function and UMOD and SHROOM3. SUMMARY: Genetic studies confirm that 'essential hypertension' consists of disparate mechanisms that ultimately lead to elevations in systemic BP. The cause of hypertension in the majority of cases remains unknown. It is anticipated that epigenetic phenomena, rare exonic mutations, and interactions with environmental factors make additional contributions.
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Keys T, Campeau L, Badlani G.
Urology. 2012 May 23. [Epub ahead of print]
PMID: 22626575
In light of the recent Food and Drug Administration public health notification regarding complications associated with transvaginally placed mesh for pelvic organ prolapse (POP) repair, we review recent literature to evaluate current outcomes and complication data, analyze the clinical need for mesh on the basis of genetic and biochemical etiologies of POP, and investigate trends of mesh use via an American Urological Association member survey. Mesh-based techniques show better anatomic results than traditional repair of anterior POP, but subjective outcomes are equivalent. Further research and Level I evidence are required before mesh-based repair of POP can be standardized. Adequate surgical training and patient selection should decrease complication rates.
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Quandt SA, Arcury-Quandt AE, Lawlor EJ, Carrillo L, Marín AJ, Grzywacz JG, Arcury TA.
Am J Ind Med. 2012 May 22. [Epub ahead of print]
PMID: 22618638
OBJECTIVES: This study uses qualitative data to describe the tasks performed by chicken catchers, their organization of work, and possible health and safety hazards encountered. METHODS: Twenty-one Latino immigrant chicken catchers for North Carolina poultry-processing plants were interviewed to obtain their perceptions of the job and its hazards. Interviews were recorded and transcribed (n = 10) or detailed notes recorded (n = 11). Transcripts and notes were subjected to qualitative analysis. RESULTS: Chicken catching takes place in a highly contaminated and hazardous work environment. The fast pace of work, low level of control over work intensity, and piece rate compensation all result in high potential for work-related injury and illness, including trauma, electrical shock, respiratory effects, musculoskeletal injuries, and drug use. Workers receive little safety or job training. CONCLUSIONS: Chicken catching is characterized by a work environment and organization of work that promote injury and illness. Am. J. Ind. Med. © 2012 Wiley Periodicals, Inc.
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Hvidtfeldt UA, Gunter MJ, Lange T, Chlebowski RT, Lane D, Farhat GN, Freiberg MS, Keiding N, Lee JS, Prentice R, Tjønneland A, Vitolins MZ, Wassertheil-Smoller S, Strickler HD, Rod NH.
Cancer Epidemiol Biomarkers Prev. 2012 May 22. [Epub ahead of print]
PMID: 22564867
BACKGROUND: Increased exposure to endogenous estrogen and/or insulin may partly explain the relationship of obesity, physical inactivity, and alcohol consumption and postmenopausal breast cancer. However, these potential mediating effects have not been formally quantified in a survival analysis setting.METHODS: We combined data from two case-cohort studies based in the Women's Health Initiative-Observational Study with serum estradiol levels, one of which also had insulin levels. A total of 1,601 women (601 cases) aged 50 to 79 years who were not using hormone therapy at enrollment were included. Mediating effects were estimated by applying a new method based on the additive hazard model.RESULTS: A five-unit increase in body mass index (BMI) was associated with 50.0 [95% confidence interval (CI), 23.2-76.6] extra cases per 100,000 women at-risk per year. Of these, 23.8% (95% CI, 2.9-68.4) could be attributed to estradiol and 65.8% (95% CI, 13.6-273.3) through insulin pathways. The mediating effect of estradiol was greater (48.8%; 95% CI, 18.8-161.1) for BMI when restricted to estrogen receptor positive (ER(+)) cases. Consuming 7+ drinks/wk compared with abstinence was associated with 164.9 (95% CI, 45.8-284.9) breast cancer cases per 100,000, but no significant contribution from estradiol was found. The effect of alcohol on breast cancer was restricted to ER(+) breast cancers.CONCLUSIONS: The relation of BMI with breast cancer was partly mediated through estradiol and, to a greater extent, through insulin.Impact: The findings provide support for evaluation of interventions to lower insulin and estrogen levels in overweight and obese postmenopausal women to reduce breast cancer risk. Cancer Epidemiol Biomarkers Prev; 1-10. ©2012 AACR.
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Rodriguez CJ.
Circulation. 2012 May 22. [Epub ahead of print]
PMID: 22619285
In 2010, the American Heart Association (AHA) declared 2020 health strategy goals to reduce deaths from cardiovascular disease and stroke by 20% and to improve the cardiovascular health (CVH) of all Americans by 20%.(1) The latter goal is aimed at helping everyone living in the United States (US) to achieve, or at least move toward ideal CVH by focusing on seven key health behaviors and risk factors - smoking, body mass-index, diet (based on the healthy diet score), participation in physical activity, and levels of blood pressure (<120/80 mm Hg), blood glucose (<100 mg/dL), and total cholesterol (<200 mg/dL).(2) What must not be forgotten is that this 2020 AHA strategy was instituted against the background of health disparities identified by the Institute of Medicine(3) in 2003 that are still present in our society today. In this issue, Dong et al.(4) describe a strong, graded relationship between the number of ideal CVH metrics and cardiovascular disease (CVD) risk (stroke, MI, and vascular death) among whites, blacks, and Hispanics living in the same community. Furthermore, the authors assessed stroke as a separate outcome event whereas prior studies(5-8) on ideal CV health either did not include stroke or treated stroke only as a component of a composite outcome. (SELECT FULL TEXT TO CONTINUE).
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Orlando G, García-Arrarás JE, Soker T, Booth C, Sanders B, Ross CL, De Coppi P, Farney AC, Rogers J, Stratta RJ.
Dig Liver Dis. 2012 May 21. [Epub ahead of print]
PMID: 22622201
The present review aims to illustrate the strategies that are being implemented in regenerative medicine to treat diseases that affect the digestive tract. Possible avenues are twofold: organ bioengineering, where cells are seeded on biological or synthetic scaffolding materials ex vivo and allowed to either mature in bioreactors or be implanted without undergoing any maturation; and regeneration per se, where the diseased tissue or organ is regenerated by recapitulation of its multi-step ontogenesis. This latter avenue may be induced either in vivo or ex vivo. While bioengineering technology has already manufactured segments of the digestive tract and sphincters, pure regeneration of any segment of the digestive tract has not yet been described. However, models of regeneration extrapolated from simple organisms are elucidating the complex yet fascinating mechanisms that regulate the ontogenesis of the digestive tract and are paving the way for the development of new regenerative technologies and methods.
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Andric T, Wright LD, Taylor BL, Freeman JW.
J Biomed Mater Res A. 2012 May 21. [Epub ahead of print]
PMID: 22615093
When traumatic injury, tumor removal, or disease results in significant bone loss, reconstructive surgery is required. Bone grafts are used in orthopedic reconstructive procedures to provide mechanical support and promote bone regeneration. In this study, we applied a heat sintering technique to fabricate 3D electrospun scaffolds that were used to evaluate effects of mineralization and fiber orientation on scaffold strength. We electrospun PLLA/gelatin scaffolds with a layer of PDLA and heat sintered them into three-dimensional cylindrical scaffolds. Scaffolds were mineralized by incubation in 10× simulated body fluid for 6, 24, and 48 h to evaluate the effect of mineralization on scaffolds compressive mechanical properties. The effects of heat sintering hydroxyapatite (HA) microparticles directly to the scaffolds on mineral deposition, distribution and mechanical properties of the scaffolds were also evaluated. We found that orientation of the fibers had little effect on the compressive mechanical properties of the scaffolds. However, increasing the mineralization times resulted in an increase in compressive mechanical properties. Also, the direct addition of HA microparticles had no effect on the scaffold mechanical properties, but had a significant effect on the mineral deposition on PLLA/gelatin scaffolds. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
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