(WP 2007-02) Valuing Environmental Quality: A Space-based Strategy

This paper develops and applies a space-based strategy for overcoming the general problem of getting at the demand for non-market goods. It focuses specifically on evaluating one form of environmental quality, distance from EPA designated environmental hazards, via the single-family housing market in the Puget Sound region of Washington State. A spatial two stage hedonic price analysis is used to: (1) estimate the marginal implicit price of distance from air release sites, hazardous waste generators, hazardous waste handlers, superfund sites, and toxic release sites; and (2) estimate a series of demand functions describing the relationship between the price of distance and the quantity consumed. The analysis, which represents a major step forward in the valuation of environmental quality, reveals that the information needed to identify second-stage demand functions is hidden right in plain site — hanging in the aether of the regional housing market

(WP 2010-02) The Demand for Historic Preservation

Historic preservation is commonly used to protect old buildings and neighborhoods from deterioration. In 1981, the City of Milwaukee established a historic preservation commission to develop and maintain a local register of places with historical importance to the area. The commission also reviews all applications for historic status as well as any requests for exterior alterations. As such, there are numerous rules and restrictions that are imposed on property owners once it has been declared a historic site. Thus, while historic designation can serve to internalize the externalities in neighborhoods with historic buildings, it also imposes costs on homeowners who wish to make improvements to their homes. This paper uses a hedonic model to estimate the impact of historic preservation on the sale price of a single family home in the Milwaukee area. Preliminary results show that the impact of historic preservation is positive when it is significant, with the average impact at 26.6%. However, there was significant variation between districts, with the impact significantly positive in 13 of 22 districts used in the sample. Specifically, the positive impact ranged between 11% and 65%, holding other factors constant. None of the 22 districts had a negative and significant impact. An evaluation of spillover effects reveal that just over one third of them displayed positive and significant spillover effects, whereas 21% had negative and significant spillover effects. The remainder were insignificant. An important question is what factors influence this variability in historic preservation effects. The eventual goal of this research is to extend our preliminary analysis to two stages using a recently developed method that employs spatial econometric methods to solve the unique identification problems inherent in hedonic models (Carruthers and Clark, forthcoming in Journal of Regional Science). This will permit us to determine the specific factors that influence these premiums. While the spatial estimates presented in this preliminary work do not permit a two-stage model, we did explore whether implicit prices appear to be correlated with the household income and racial makeup of the neighborhoods in which they are located. The findings show little evidence that the implicit values of historic districts are correlated, but the implicit price associated with historic district spillovers was positively correlated with both neighborhood measures

(WP 2010-11) The Benefits of Environmental Improvement: Estimates From Space-time Analysis

This paper develops estimates of environmental improvement based on a two-stage hedonic price analysis of the single family housing market in the Puget Sound region of Washington State. The analysis — which focuses specifically on several EPA-designated environmental hazards and involves 226,918 transactions for 177,303 unique properties that took place between January 2001 and September 2009 — involves four steps: (i) ten hedonic price functions are estimated year-by-year, one for each year of the 2000s; (ii) the hedonic estimates are used to compute the marginal implicit price of distance from air release, superfund, and toxic release sites; (iii) the marginal implicit prices, which vary through time, are used to estimate a series of implicit demand functions describing the relationship between the price of distance and the quantity consumed; and, finally (iv) the demand estimates are compared to those obtained in other research and then used evaluate the potential scale of benefits associated with some basic environmental improvement scenarios. Overall, the analysis provides further evidence that it is possible to develop a structural model of implicit demand within a single housing market and suggests that the benefits of environmental improvement are substantial

The Demand for Historic Preservation

Historic preservation is commonly used to protect old buildings and neighborhoods from deterioration. In 1981, the City of Milwaukee established a historic preservation commission to develop and maintain a local register of places with historical importance to the area. The commission also reviews all applications for historic status as well as any requests for exterior alterations. As such, there are numerous rules and restrictions that are imposed on property owners once it has been declared a historic site. Thus, while historic designation can serve to internalize the externalities in neighborhoods with historic buildings, it also imposes costs on homeowners who wish to make improvements to their homes. This paper uses a hedonic model to estimate the impact of historic preservation on the sale price of a single family home in the Milwaukee area. Preliminary results show that the impact of historic preservation is positive when it is significant, with the average impact at 26.6%. However, there was significant variation between districts, with the impact significantly positive in 13 of 22 districts used in the sample. Specifically, the positive impact ranged between 11% and 65%, holding other factors constant. None of the 22 districts had a negative and significant impact. An evaluation of spillover effects reveal that just over one third of them displayed positive and signficant spillover effects, whereas 21% had negative and significant spillover effects. The remainder were insignificant. An important question is what factors influence this variability in historic preservation effects. The eventual goal of this research is to extend our preliminary analysis to two stages using a recently developed method that employs spatial econometric methods to solve the unique identification problems inherent in hedonic models (Carruthers and Clark, forthcoming in Journal of Regional Science). This will permit us to determine the specific factors that influence these premiums. While the spatial estimates presented in this preliminary work do not permit a two-stage model, we did explore whether implicit prices appear to be correlated with the household income and racial makeup of the neighborhoods in which they are located. The findings show little evidence that the implicit values of historic districts are correlated, but the implicit price associated with historic district spillovers was positively correlated with both neighborhood measures.Hedonic housing model, historic preservation district, Milwaukee

The Impact of Transit Corridors on Residential Property Values

Most of the literature on transit corridors, such as superhighways and tunnels, focuses on the positive externality of transit access (e.g., interstate access, transit station) and fails to isolate the negative externality of the corridor itself. This empirical study examines two situations: one with both access benefits and negatives, and another without the access benefit. The findings reveal that proximity to the transit corridor alone without direct access conveys a negative impact on nearby housing values.

The Benefits of Environmental Improvement: Estimates From Space-time Analysis

This paper develops estimates of environmental improvement based on a two-stage hedonic price analysis of the single family housing market in the Puget Sound region of Washington State. The analysis — which focuses specifically on several EPA-designated environmental hazards and involves 226,918 transactions for 177,303 unique properties that took place between January 2001 and September 2009 — involves four steps: (i) ten hedonic price functions are estimated year-by-year, one for each year of the 2000s; (ii) the hedonic estimates are used to compute the marginal implicit price of distance from air release, superfund, and toxic release sites; (iii) the marginal implicit prices, which vary through time, are used to estimate a series of implicit demand functions describing the relationship between the price of distance and the quantity consumed; and, finally (iv) the demand estimates are compared to those obtained in other research and then used evaluate the potential scale of benefits associated with some basic environmental improvement scenarios. Overall, the analysis provides further evidence that it is possible to develop a structural model of implicit demand within a single housing market and suggests that the benefits of environmental improvement are substantial.Hedonic housing model, benefits, environmental improvement

Small-molecule inhibition of a depalmitoylase enhances Toxoplasma host-cell invasion.

Although there have been numerous advances in our understanding of how apicomplexan parasites such as Toxoplasma gondii enter host cells, many of the signaling pathways and enzymes involved in the organization of invasion mediators remain poorly defined. We recently performed a forward chemical-genetic screen in T. gondii and identified compounds that markedly enhanced infectivity. Although molecular dissection of invasion has benefited from the use of small-molecule inhibitors, the mechanisms underlying induction of invasion by small-molecule enhancers have never been described. Here we identify the Toxoplasma ortholog of human APT1, palmitoyl protein thioesterase-1 (TgPPT1), as the target of one class of small-molecule enhancers. Inhibition of this uncharacterized thioesterase triggered secretion of invasion-associated organelles, increased motility and enhanced the invasive capacity of tachyzoites. We demonstrate that TgPPT1 is a bona fide depalmitoylase, thereby establishing an important role for dynamic and reversible palmitoylation in host-cell invasion by T. gondii

Birmingham Behçet’s service: classification of disease and application of the 2014 International Criteria for Behçet’s Disease (ICBD) to a UK cohort

BACKGROUND: This study reports on the analysis of the application and diagnostic predictability of the revised 2014 ICBD criteria in an unselected cohort of UK patients, and the ensuing organ associations and patterns of disease. METHODS: A retrospective cohort study was conducted using a database of electronic medical records. Three categories were recognised: clinically defined BD, incomplete BD and rejected diagnoses of BD. We applied the ISG 1990 and ICBD 2014 classification criteria to these subgroups to validate diagnostic accuracy against the multidisciplinary assessment. RESULTS: Between 2012 and 2015, 281 patients underwent initial assessment at an urban tertiary care centre: 190 patients with a confirmed diagnosis of BD, 7 with an incomplete diagnosis, and 84 with a rejected diagnosis. ICBD 2014 demonstrated an estimated sensitivity of 97.89% (95% CI: 94.70 to 99.42) and positive likelihood ratio of 1.21 (1.10 to 1.28). The strongest independent predictors were: Central nervous lesions (OR = 10.57, 95% CI: 1.34 to 83.30); Genital ulceration (OR = 9.05, 95% CI: 3.35 to 24.47); Erythema nodosum (OR = 6.59, 95% CI: 2.35 to 18.51); Retinal vasculitis (OR = 6.25, 95% CI: 1.47 to 26.60); Anterior uveitis (OR = 6.16, 95% CI: 2.37 to 16.02); Posterior uveitis (OR = 4.82, 95% CI: 1.25 to 18.59). CONCLUSIONS: The ICBD 2014 criteria were more sensitive at picking up cases than ISG 1990 using the multidisciplinary assessment as the gold standard. ICBD may over-diagnose BD in a UK population. Patients who have an incomplete form of BD represent a distinct group that should not be given an early diagnostic label. Behçet’s disease is a complex disease that is best diagnosed by multidisciplinary clinical assessment. Patients in the UK differ in their clinical presentation and genetic susceptibility from the original descriptions. This study also highlights an incomplete group of Behçet’s patients that are less well defined by their clinical presentation

The C-Terminus of Toxoplasma RON2 Provides the Crucial Link between AMA1 and the Host-Associated Invasion Complex

Host cell invasion by apicomplexan parasites requires formation of the moving junction (MJ), a ring-like apposition between the parasite and host plasma membranes that the parasite migrates through during entry. The Toxoplasma MJ is a secreted complex including TgAMA1, a transmembrane protein on the parasite surface, and a complex of rhoptry neck proteins (TgRON2/4/5/8) described as host cell-associated. How these proteins connect the parasite and host cell has not previously been described. Here we show that TgRON2 localizes to the MJ and that two short segments flanking a hydrophobic stretch near its C-terminus (D3 and D4) independently associate with the ectodomain of TgAMA1. Pre-incubation of parasites with D3 (fused to glutathione S-transferase) dramatically reduces invasion but does not prevent injection of rhoptry bulb proteins. Hence, the entire C-terminal region of TgRON2 forms the crucial bridge between TgAMA1 and the rest of the MJ complex but this association is not required for rhoptry protein injection

Eimeripain, a Cathepsin B-Like Cysteine Protease, Expressed throughout Sporulation of the Apicomplexan Parasite Eimeria tenella

The invasion and replication of Eimeria tenella in the chicken intestine is responsible for avian coccidiosis, a disease that has major economic impacts on poultry industries worldwide. E. tenella is transmitted to naïve animals via shed unsporulated oocysts that need contact with air and humidity to form the infectious sporulated oocysts, which contain the first invasive form of the parasite, the sporozoite. Cysteine proteases (CPs) are major virulence factors expressed by protozoa. In this study, we show that E. tenella expresses five transcriptionally regulated genes encoding one cathepsin L, one cathepsin B and three cathepsin Cs. Biot-LC-LVG-CHN2, a cystatin derived probe, tagged eight polypeptides in unsporulated oocysts but only one in sporulated oocysts. CP-dependant activities were found against the fluorescent substrates, Z-FR-AMC and Z-LR-AMC, throughout the sporulation process. These activities corresponded to a cathepsin B-like enzyme since they were inhibited by CA-074, a specific cathepsin B inhibitor. A 3D model of the catalytic domain of the cathepsin B-like protease, based on its sequence homology with human cathepsin B, further confirmed its classification as a papain-like protease with similar characteristics to toxopain-1 from the related apicomplexan parasite, Toxoplasma gondii; we have, therefore, named the E. tenella cathepsin B, eimeripain. Following stable transfection of E. tenella sporozoites with a plasmid allowing the expression of eimeripain fused to the fluorescent protein mCherry, we demonstrated that eimeripain is detected throughout sporulation and has a punctate distribution in the bodies of extra- and intracellular parasites. Furthermore, CA-074 Me, the membrane-permeable derivative of CA-074, impairs invasion of epithelial MDBK cells by E. tenella sporozoites. This study represents the first characterization of CPs expressed by a parasite from the Eimeria genus. Moreover, it emphasizes the role of CPs in transmission and dissemination of exogenous stages of apicomplexan parasites