Showing papers by "University of Florida published in 2002"

A second-generation reactive empirical bond order (REBO) potential energy expression for hydrocarbons

Abstract: A second-generation potential energy function for solid carbon and hydrocarbon molecules that is based on an empirical bond order formalism is presented. This potential allows for covalent bond breaking and forming with associated changes in atomic hybridization within a classical potential, producing a powerful method for modelling complex chemistry in large many-atom systems. This revised potential contains improved analytic functions and an extended database relative to an earlier version (Brenner D W 1990 Phys. Rev. B 42 9458). These lead to a significantly better description of bond energies, lengths, and force constants for hydrocarbon molecules, as well as elastic properties, interstitial defect energies, and surface energies for diamond.

Conditional value-at-risk for general loss distributions

Abstract: Fundamental properties of conditional value-at-risk (CVaR), as a measure of risk with significant advantages over value-at-risk (VaR), are derived for loss distributions in finance that can involve discreetness. Such distributions are of particular importance in applications because of the prevalence of models based on scenarios and finite sampling. CVaR is able to quantify dangers beyond VaR and moreover it is coherent. It provides optimization short-cuts which, through linear programming techniques, make practical many large-scale calculations that could otherwise be out of reach. The numerical efficiency and stability of such calculations, shown in several case studies, are illustrated further with an example of index tracking.

Voriconazole versus Amphotericin B for Primary Therapy of Invasive Aspergillosis

Abstract: Background Voriconazole is a broad-spectrum triazole that is active against aspergillus species. We conducted a randomized trial to compare voriconazole with amphotericin B for primary therapy of invasive aspergillosis. Methods In this randomized, unblinded trial, patients received either intravenous voriconazole (two doses of 6 mg per kilogram of body weight on day 1, then 4 mg per kilogram twice daily for at least seven days) followed by 200 mg orally twice daily or intravenous amphotericin B deoxycholate (1 to 1.5 mg per kilogram per day). Other licensed antifungal treatments were allowed if the initial therapy failed or if the patient had an intolerance to the first drug used. A complete or partial response was considered to be a successful outcome. Results A total of 144 patients in the voriconazole group and 133 patients in the amphotericin B group with definite or probable aspergillosis received at least one dose of treatment. In most of the patients, the underlying condition was allogeneic hematop...

Bone marrow cells adopt the phenotype of other cells by spontaneous cell fusion

Abstract: Recent studies have demonstrated that transplanted bone marrow cells can turn into unexpected lineages including myocytes, hepatocytes, neurons and many others. A potential problem, however, is that reports discussing such 'transdifferentiation' in vivo tend to conclude donor origin of transdifferentiated cells on the basis of the existence of donor-specific genes such as Y-chromosome markers. Here we demonstrate that mouse bone marrow cells can fuse spontaneously with embryonic stem cells in culture in vitro that contains interleukin-3. Moreover, spontaneously fused bone marrow cells can subsequently adopt the phenotype of the recipient cells, which, without detailed genetic analysis, might be interpreted as 'dedifferentiation' or transdifferentiation.

Effects of Cognitive training interventions with older adults. A randomized controlled trial

Abstract: ContextCognitive function in older adults is related to independent living and need for care. However, few studies have addressed whether improving cognitive functions might have short- or long-term effects on activities related to living independently.ObjectiveTo evaluate whether 3 cognitive training interventions improve mental abilities and daily functioning in older, independent-living adults.DesignRandomized, controlled, single-blind trial with recruitment conducted from March 1998 to October 1999 and 2-year follow-up through December 2001.Setting and ParticipantsVolunteer sample of 2832 persons aged 65 to 94 years recruited from senior housing, community centers, and hospital/clinics in 6 metropolitan areas in the United States.InterventionsParticipants were randomly assigned to 1 of 4 groups: 10-session group training for memory (verbal episodic memory; n = 711), or reasoning (ability to solve problems that follow a serial pattern; n = 705), or speed of processing (visual search and identification; n = 712); or a no-contact control group (n = 704). For the 3 treatment groups, 4-session booster training was offered to a 60% random sample 11 months later.Main Outcome MeasuresCognitive function and cognitively demanding everyday functioning.ResultsThirty participants were incorrectly randomized and were excluded from the analysis. Each intervention improved the targeted cognitive ability compared with baseline, durable to 2 years (P<.001 for all). Eighty-seven percent of speed-, 74% of reasoning-, and 26% of memory-trained participants demonstrated reliable cognitive improvement immediately after the intervention period. Booster training enhanced training gains in speed (P<.001) and reasoning (P<.001) interventions (speed booster, 92%; no booster, 68%; reasoning booster, 72%; no booster, 49%), which were maintained at 2-year follow-up (P<.001 for both). No training effects on everyday functioning were detected at 2 years.ConclusionsResults support the effectiveness and durability of the cognitive training interventions in improving targeted cognitive abilities. Training effects were of a magnitude equivalent to the amount of decline expected in elderly persons without dementia over 7- to 14-year intervals. Because of minimal functional decline across all groups, longer follow-up is likely required to observe training effects on everyday function.

A Review of IPO Activity, Pricing, and Allocations

Abstract: We review the theory and evidence on IPO activity: why firms go public, why they reward first-day investors with considerable underpricing, and how IPOs perform in the long run. Our perspective is threefold: First, we believe that many IPO phenomena are not stationary. Second, we believe research into share allocation issues is the most promising area of research in IPOs at the moment. Third, we argue that asymmetric information is not the primary driver of many IPO phenomena. Instead, we believe future progress in the literature will come from nonrational and agency conf lict explanations. We describe some promising such alternatives. From 1980 to 2001, the number of companies going public in the United States exceeded one per business day. The number of initial public offerings ~IPOs! has varied from year to year, however, with some years seeing fewer than 100 IPOs, and others seeing more than 400. These IPOs raised $488 billion ~in 2001 dollars! in gross proceeds, an average of $78 million per deal. At the end of the first day of trading, their shares traded on average at 18.8 percent above the price at which the company sold them. For an investor buying shares at the first-day closing price and holding them for three years, IPOs returned 22.6 percent. Still, over three years, the average IPO underperformed the CRSP value-weighted market index by 23.4 percent and underperformed seasoned companies with the same market capitalization and book-to-market ratio by 5.1 percent. In a nutshell, these numbers summarize the patterns in issuing activity, underpricing, and long-run underperformance, which have been the focus of a large theoretical and empirical literature. We survey this literature, focusing on recent papers. Space constraints force us to take a U.S.-centric point of view and to omit a description of the institutional aspects of going public. The interested reader can consult Ellis, Michaely, and O’Hara ~2000!,

Resilience Management in Social-ecological Systems: a Working Hypothesis for a Participatory Approach

Abstract: Approaches to natural resource management are often based on a presumed ability to predict probabilistic responses to management and external drivers such as climate. They also tend to assume that the manager is outside the system being managed. However, where the objectives include long-term sustainability, linked social-ecological systems (SESs) behave as complex adaptive systems, with the managers as integral components of the system. Moreover, uncertainties are large and it may be difficult to reduce them as fast as the system changes. Sustainability involves maintaining the functionality of a system when it is perturbed, or maintaining the elements needed to renew or reorganize if a large perturbation radically alters structure and function. The ability to do this is termed "resilience." This paper presents an evolving approach to analyzing resilience in SESs, as a basis for managing resilience. We propose a framework with four steps, involving close involvement of SES stakeholders. It begins with a stakeholder-led development of a conceptual model of the system, including its historical profile (how it got to be what it is) and preliminary assessments of the drivers of the supply of key ecosystem goods and services. Step 2 deals with identifying the range of unpredictable and uncontrollable drivers, stakeholder visions for the future, and contrasting possible future policies, weaving these three factors into a limited set of future scenarios. Step 3 uses the outputs from steps 1 and 2 to explore the SES for resilience in an iterative way. It generally includes the development of simple models of the system's dynamics for exploring attributes that affect resilience. Step 4 is a stakeholder evaluation of the process and outcomes in terms of policy and management implications. This approach to resilience analysis is illustrated using two stylized examples.

Walking compared with vigorous exercise for the prevention of cardiovascular events in women.

Abstract: Background The role of walking, as compared with vigorous exercise, in the prevention of cardiovascular disease remains controversial. Data for women who are members of minority racial or ethnic groups are particularly sparse. Methods We prospectively examined the total physical-activity score, walking, vigorous exercise, and hours spent sitting as predictors of the incidence of coronary events and total cardiovascular events among 73,743 postmenopausal women 50 to 79 years of age in the Women's Health Initiative Observational Study. At base line, participants were free of diagnosed cardiovascular disease and cancer, and all participants completed detailed questionnaires about physical activity. We documented 345 newly diagnosed cases of coronary heart disease and 1551 total cardiovascular events. Results An increasing physical-activity score had a strong, graded, inverse association with the risk of both coronary events and total cardiovascular events. There were similar findings among white women and bl...

2001 Consensus Guidelines for the Management of Women With Cervical Cytological Abnormalities

Abstract: ObjectiveTo provide evidence-based consensus guidelines for the management of women with cervical cytological abnormalities and cervical cancer precursors.ParticipantsA panel of 121 experts in the diagnosis and management of cervical cancer precursors, including representatives from 29 professional organizations, federal agencies, and national and international health organizations, were invited to participate in a consensus conference sponsored by the American Society for Colposcopy and Cervical Pathology (ASCCP).Evidence and Consensus ProcessGuidelines for the management of women with cervical cytological abnormalities were developed through a multistep process. Starting 6 months before the conference, working groups developed draft management guidelines based on formal literature reviews of English-language articles published in 1988-2001, as well as input from the professional community at large, obtained using interactive Internet-based bulletin boards. On September 6-8, 2001, the ASCCP Consensus Conference was held in Bethesda, Md. Guidelines with supporting evidence were presented and underwent discussion, revision, and voting.ConclusionsManagement of women with atypical squamous cells (ASC) depends on whether the Papanicolaou test is subcategorized as of undetermined significance (ASC-US) or as cannot exclude high-grade squamous intraepithelial lesion (HSIL) (ASC-H). Women with ASC-US should be managed using a program of 2 repeat cytology tests, immediate colposcopy, or DNA testing for high-risk types of human papillomavirus (HPV). Testing for HPV DNA is the preferred approach when liquid-based cytology is used for screening. In most instances, women with ASC-H, low-grade squamous intraepithelial lesion, HSIL, and atypical glandular cells should be referred for immediate colposcopic evaluation.

A Review of IPO Activity, Pricing and Allocations

Abstract: We review the theory and evidence on IPO activity: why firms go public, why they reward first-day investors with considerable underpricing, and how IPOs perform in the long run. Our perspective on the literature is three-fold: First, we believe that many IPO phenomena are not stationary. Second, we believe research into share allocation issues is the most promising area of research in IPOs at the moment. Third, we argue that asymmetric information is not the primary driver of many IPO phenomena. Instead, we believe future progress in the literature will come from non-rational and agency conflict explanations. We describe some promising such alternatives.

Why Don’t Issuers Get Upset About Leaving Money on the Table in IPOs?

Abstract: One of the puzzles regarding initial public offerings (IPOs) is that issuers rarely get upset about leaving substantial amounts of money on the table, defined as the number of shares sold times the difference between the first-day closing market price and the offer price. The average IPO leaves $9.1 million on the table. This number is approximately twice as large as the fees paid to investment bankers and represents a substantial indirect cost to the issuing firm. We present a prospect theory model that focuses on the covariance of the money left on the table and wealth changes. Our reasoning also provides an explanation for a second puzzling pattern: much more money is left on the table following recent market rises than after market falls. This results in an explanation of hot issue markets. We also offer a new explanation for why IPOs are underpriced. Copyright 2002, Oxford University Press.

Human cortical glial tumors contain neural stem-like cells expressing astroglial and neuronal markers in vitro.

Abstract: Neural stem cells from neurogenic regions of mammalian CNS are clonogenic in an in vitro culture system exploiting serum and anchorage withdrawal in medium supplemented with methyl cellulose and the pleiotropic growth factors EGF, FGF2, and insulin. The aim of this study was to test whether cortical glial tumors contain stem-like cells capable, under this culture system, of forming clones showing intraclonal heterogeneity in the expression of neural lineage-specific proteins. The high frequencies of clone-forming cells (about 0.1-10 x 10(-3)) in clinical tumor specimens with mutated p53, and in neurogenic regions of normal human CNS, suggest that the ability to form clones in this culture system is induced epigenetically. RT-PCR analyses of populations of normal brain- and tumor-derived sister clones revealed transcripts for nestin, neuron-specific enolase, and glial fibrillary acidic protein (GFAP). However, the tumor-derived clones were different from clones derived from neurogenic regions of normal brain in the expression of transcripts specific for genes associated with neural cell fate determination via the Notch-signaling pathway (Delta and Jagged), and cell survival at G2 or mitotic phases (Survivin). Moreover, the individual glioma-derived clones contain cells immunopositive separately for GFAP or neuronal beta-III tubulin, as well as single cells coexpressing both glial and neuronal markers. The data suggest that the latent critical stem cell characteristics can be epigenetically induced by growth conditions not only in cells from neurogenic regions of normal CNS but also in cells from cortical glial tumors. Moreover, tumor stem-like cells with genetically defective responses to epigenetic stimuli may contribute to gliomagenesis and the developmental pathological heterogeneity of glial tumors.

Voriconazole compared with liposomal amphotericin B for empirical antifungal therapy in patients with neutropenia and persistent fever

Abstract: Background Patients with neutropenia and persistent fever are often treated empirically with amphotericin B or liposomal amphotericin B to prevent invasive fungal infections. Antifungal triazoles offer a potentially safer and effective alternative. Methods In a randomized, international, multicenter trial, we compared voriconazole, a new second-generation triazole, with liposomal amphotericin B for empirical antifungal therapy. Results A total of 837 patients (415 assigned to voriconazole and 422 to liposomal amphotericin B) were evaluated for success of treatment. The overall success rates were 26.0 percent with voriconazole and 30.6 percent with liposomal amphotericin B (95 percent confidence interval for the difference, –10.6 to 1.6 percentage points); these rates were independent of the administration of antifungal prophylaxis or the use of colony-stimulating factors. There were fewer documented breakthrough fungal infections in patients treated with voriconazole than in those treated with liposomal a...

Microglia as neuroprotective, immunocompetent cells of the CNS

Abstract: The role of glial cells is to support and sustain proper neuronal function and microglia are no exception to this. This viewpoint article emphasizes the fundamental interdependence of microglia and neurons and takes a look at the possibility of what could happen if microglial cells became dysfunctional as a result of aging, genetics, or epigenetics. Could microglial senescence be a factor in the pathogenesis of Alzheimer's and other neurodegenerative diseases? The cautious answer to that question is 'yes'. Future studies along these lines may provide novel insights into microglial involvement in neurodegenerative disease pathogenesis.

Osmolyte accumulation: can it really help increase crop yield under drought conditions?

Abstract: Osmolyte accumulation (OA) is frequently cited as a key putative mechanism for increasing yields of crops subjected to drought conditions. The hypothesis is that OA results in a number of benefits that sustain cell and tissue activity under water-deficit conditions. It has been proposed as an effective tolerance mechanism for water deficits, which could be enhanced in crops by traditional plant breeding, marker-assisted selection or genetic engineering, to generate drought-tolerant crops. However, field studies examining the association between OA and crop yield have tended to show no consistent benefit. The few, often-cited, investigations with positive associations were obtained under severe water deficits with extremely low yields or conditions with special water-supply scenarios when much of the benefit is plant survival. Under conditions where water deficits threaten crop survival, yields are so low that even large fractional yield gains offer little practical benefit to growers. Indeed, the often-cited benefit of turgor maintenance in cells is likely to result in crop behaviour that is exactly opposite to what is beneficial to crops. The one clear mechanism identified in this review for beneficial yield responses to OA is in the maintenance of root development in order to reach water that may be available deeper in the soil profile.

Neck Dissection Classification Update: Revisions Proposed by the American Head and Neck Society and the American Academy of Otolaryngology–Head and Neck Surgery

Abstract: Since the first description of the radical neck dissection by George Crile almost a century ago, many variations and modifications of the procedure have been added. These include the functional neck dissection, the modified radical neck dissection, and various selective neck dissections. In response to the need for an organized approach in describing these operations, the Committee for Head and Neck Surgery and Oncology of the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) in 1988 initiated an effort to develop a standardized classification system for neck dissection (Table 1). During this process, input was obtained from the Education Committee of the American Society for Head and Neck Surgery (ASHNS) and its Council. The final product, endorsed by the ASHNS and the AAO-HNS, was published in the ARCHIVES 1 and as a monograph 2 by the AAO-HNS in 1991.

Exchange-biased quantum tunnelling in a supramolecular dimer of single-molecule magnets

Abstract: Various present and future specialized applications of magnets require monodisperse, small magnetic particles, and the discovery of molecules that can function as nanoscale magnets was an important development in this regard. These molecules act as single-domain magnetic particles that, below their blocking temperature, exhibit magnetization hysteresis, a classical property of macroscopic magnets. Such 'single-molecule magnets' (SMMs) straddle the interface between classical and quantum mechanical behaviour because they also display quantum tunnelling of magnetization and quantum phase interference. Quantum tunnelling of magnetization can be advantageous for some potential applications of SMMs, for example, in providing the quantum superposition of states required for quantum computing. However, it is a disadvantage in other applications, such as information storage, where it would lead to information loss. Thus it is important to both understand and control the quantum properties of SMMs. Here we report a supramolecular SMM dimer in which antiferromagnetic coupling between the two components results in quantum behaviour different from that of the individual SMMs. Our experimental observations and theoretical analysis suggest a means of tuning the quantum tunnelling of magnetization in SMMs. This system may also prove useful for studying quantum tunnelling of relevance to mesoscopic antiferromagnets.

Psychometric and clinimetric validity of the 20-Item Sino-Nasal Outcome Test (SNOT-20)

Abstract: A valid measure of rhinosinusitis health status and quality of life is required for the complete assessment of treatment effectiveness. The purpose of this study was to analyze the psychometric and clinimetric validity of the 20-Item Sino-Nasal Outcome Test (SNOT-20), a disease-specific, health-related quality-of-life measure for rhinosinusitis. The SNOT-20 is a modification of the 31-Item Rhinosinusitis Outcome Measure, and it contains 20 nose, sinus, and general items. To complete the instrument, patients indicate how much they are affected in each area and identify the 5 most important items. The SNOT-20 was completed by 102, 72, and 46 patients at the initial visit and at 6 months and 1 year after treatment commencement, respectively. Cronbach's alpha was 0.9; test-retest scores were highly correlated (r = 0.9). Patients who were more affected had greater SNOT-20 scores (P < 0.002), and patients who had improved had greater change scores (P < 0.04). Items identified as important had greater scores (P < 0.0001) and showed greater change scores (P < 0.0002). The SNOT-20 is a valid outcome measure for patients with rhinosinusitis; it describes the health burden and is sensitive to clinical change.

Preferential transformation of human neuronal cells by human adenoviruses and the origin of HEK 293 cells.

Abstract: The 293 cell line was derived by transformation of primary cultures of human embryonic kidney (HEK) cells with sheared adenovirus (Ad)5 DNA. A combination of immunostaining, immunoblot, and microarray analysis showed that 293 cells express the neurofilament (NF) subunits NF-L, NF-M, NF-H, and a-internexin as well as many other proteins typically found in neurons. Three other independently derived HEK lines, two transformed by Ad5 and one by Ad12, also expressed NFs, as did one human embryonic retinal cell line transformed with Ad5. Two rodent kidney lines transformed with Ad12 were also found to express NF proteins, although several rodent kidney cell lines transformed by Ad5 DNA and three HEK cell lines transformed by the SV40 early region did not express NFs. These results suggest that human Ads preferentially transform human neuronal lineage cells. We also demonstrate that the widely used HEK293 cells have an unexpected relationship to neurons, a finding that may require reinterpretation of many previous studies in which it was assumed that HEK293 cells resembled more typical kidney epithelial cells.

Microbial source tracking: current methodology and future directions.

Abstract: Maintenance of the microbiological quality and safety of water systems used for drinking, for recreating, and in the harvesting of seafood is imperative, as contamination of these systems can exact high risks to human health as well as result in significant economic losses due to closures of beaches

Invasions by insect vectors of human disease

Abstract: Nonindigenous vectors that arrive, establish, and spread in new areas have fomented throughout recorded history epidemics of human diseases such as malaria, yellow fever, typhus, and plague. Although some vagile vectors, such as adults of black flies, biting midges, and tsetse flies, have dispersed into new habitats by flight or wind, human-aided transport is responsible for the arrival and spread of most invasive vectors, such as anthropophilic fleas, lice, kissing bugs, and mosquitoes. From the fifteenth century to the present, successive waves of invasion of the vector mosquitoes Aedes aegypti, the Culex pipiens Complex, and, most recently, Aedes albopictus have been facilitated by worldwide ship transport. Aircraft have been comparatively unimportant for the transport of mosquito invaders. Mosquito species that occupy transportable container habitats, such as water-holding automobile tires, have been especially successful as recent invaders. Propagule pressure, previous success, and adaptations to human habits appear to favor successful invasions by vectors.

Waiting time on dialysis as the strongest modifiable risk factor for renal transplant: Outcomes a paired donor kidney analysis

Abstract: Background. Waiting time on dialysis has been shown to be associated with worse outcomes after living and cadaveric transplantation. To validate and quantify end-stage renal disease (ESRD) time as an independent risk factor for kidney transplantation, we compared the outcome of paired donor kidneys, destined to patients who had ESRD more than 2 years compared to patients who had ESRD less than 6 months. Methods. We analyzed data available from the U.S. Renal Data System database between 1988 and 1998 by Kaplan-Meier estimates and Cox proportional hazards models to quantify the effect of ESRD time on paired cadaveric kidneys and on all cadaveric kidneys compared to living-donated kidneys. Results. Five- and 10-year unadjusted graft survival rates were significantly worse in paired kidney recipients who had undergone more than 24 months of dialysis (58% and 29%, respectively) compared to paired kidney recipients who had undergone less than 6 months of dialysis (78% and 63%, respectively; P<0.001 each). Ten-year overall adjusted graft survival for cadaveric transplants was 69% for preemptive transplants versus 39% for transplants after 24 months on dialysis. For living transplants, 10-year overall adjusted graft survival was 75% for preemptive transplants versus 49% for transplants after 24 month on dialysis. Conclusions. ESRD time is arguably the strongest independent modifiable risk factor for renal transplant outcomes. Part of the advantage of living-donor versus cadaveric-donor transplantation may be explained by waiting time. This effect is dominant enough that a cadaveric renal transplant recipient with an ESRD time less than 6 months has the equivalent graft survival of living donor transplant recipients who wait on dialysis for more than 2 years.

The snowmass Points and slopes: benchmarks for SUSY searches

Abstract: The ”Snowmass Points and Slopes” (SPS) are a set of benchmark points and parameter lines in the MSSM parameter space corresponding to different scenarios in the search for Supersymmetry at present and future experiments. This set of benchmarks was agreed upon at the 2001 ”Snowmass Workshop on the Future of Particle Physics” as a consensus based on different existing proposals.

Vapour undersaturation in primitive mid-ocean-ridge basalt and the volatile content of Earth's upper mantle

Abstract: The analysis of volatiles in magmatic systems can be used to constrain the volatile content of the Earth’s mantle and the influence that magmatic degassing has on the chemistry of the oceans and the atmosphere. But most volatile elements have very low solubilities in magmas at atmospheric pressure, and therefore virtually all erupted lavas are degassed and do not retain their primary volatile signatures. Here we report the undersaturated pre-eruptive volatile content for a suite of mid-ocean-ridge basalts from the Siqueiros intra-transform spreading centre. The undersaturation leads to correlations between volatiles and refractory trace elements that provide new constraints on volatile abundances and their behaviour in the upper mantle. Our data generate improved limits on the abundances of carbon dioxide, water, fluorine, sulphur and chlorine in the source of normal mid-oceanridge basalt. The incompatible behaviour of carbon dioxide, together with the CO2/Nb and CO2/Cl ratios, permit estimates of primitive carbon dioxide and chlorine to be made for degassed and chlorine-contaminated mid-ocean-ridge basalt magmas, and hence constrain degassing and contamination histories of mid-ocean ridges.

Macroeconomic Factors Do Influence Aggregate Stock Returns

Abstract: Stock market returns are significantly correlated with inflation and money growth. The impact of real macroeconomic variables on aggregate equity returns has been difficult to establish, perhaps because their effects are neither linear nor time invariant. We estimate a GARCH model of daily equity returns, where realized returns and their conditional volatility depend on 17 macro series' announcements. We find six candidates for priced factors: three nominal (CPI, PPI, and a Monetary Aggregate) and three real (Balance of Trade, Employment Report, and Housing Starts). Popular measures of overall economic activity, such as Industrial Production or GNP are not represented. Copyright 2002, Oxford University Press.

Adult hematopoietic stem cells provide functional hemangioblast activity during retinal neovascularization

Abstract: Adults maintain a reservoir of hematopoietic stem cells that can enter the circulation to reach organs in need of regeneration. We developed a novel model of retinal neovascularization in adult mice to examine the role of hematopoietic stem cells in revascularizing ischemic retinas. Adult mice were durably engrafted with hematopoietic stem cells isolated from transgenic mice expressing green fluorescent protein. We performed serial long-term transplants, to ensure activity arose from self-renewing stem cells, and single hematopoietic stem-cell transplants to show clonality. After durable hematopoietic engraftment was established, retinal ischemia was induced to promote neovascularization. Our results indicate that self-renewing adult hematopoietic stem cells have functional hemangioblast activity, that is, they can clonally differentiate into all hematopoietic cell lineages as well as endothelial cells that revascularize adult retina. We also show that recruitment of endothelial precursors to sites of ischemic injury has a significant role in neovascularization.

Justice in teams: antecedents and consequences of procedural justice climate

Abstract: This study examined antecedents and consequences of procedural justice climate (Mossholder, Bennett, & Martin, 1998; Naumann & Bennett, 2000) in a sample of manufacturing teams. The results showed that climate level (i.e., the average procedural justice perception within the team) was significantly related to both team performance and team absenteeism. Moreover, the effects of climate level were moderated by climate strength, such that the relationships were more beneficial in stronger climates. In addition, team size and team collectivism were significant antecedents of climate level, and team size and team demographic diversity predicted climate strength.

Parkinson-like neurodegeneration induced by targeted overexpression of alpha-synuclein in the nigrostriatal system.

Abstract: Recombinant adeno-associated viral vectors display efficient tropism for transduction of the dopamine neurons of the substantia nigra. Taking advantage of this unique property of recombinant adeno-associated viral vectors, we expressed wild-type and A53T mutated human α-synuclein in the nigrostriatal dopamine neurons of adult rats for up to 6 months. Cellular and axonal pathology, including α-synuclein-positive cytoplasmic inclusions and swollen, dystrophic neurites similar to those seen in brains from patients with Parkinson9s disease, developed progressively over time. These pathological alterations occurred preferentially in the nigral dopamine neurons and were not observed in other nondopaminergic neurons transduced by the same vectors. The degenerative changes were accompanied by a loss of 30–80% of the nigral dopamine neurons, a 40–50% reduction of striatal dopamine, and tyrosine hydroxylase levels that was fully developed by 8 weeks. Significant motor impairment developed in those animals in which dopamine neuron cell loss exceeded a critical threshold of 50–60%. At 6 months, signs of cell body and axonal pathology had subsided, suggesting that the surviving neurons had recovered from the initial insult, despite the fact that α-synuclein expression was maintained at a high level. These results show that nigral dopamine neurons are selectively vulnerable to high levels of either wild-type or mutant α-synuclein, pointing to a key role for α-synuclein in the pathogenesis of Parkinson9s disease. Targeted overexpression of α-synuclein in the nigrostriatal system may provide a new animal model of Parkinson9s disease that reproduces some of the cardinal pathological, neurochemical, and behavioral features of the human disease.