The Demarcation of Land and the Role of Coordinating Institutions

This paper examines the economic effects of the two dominant land demarcation systems, metes and bounds (MB) and the rectangular system (RS). Under MB property is demarcated by its perimeter as indicated by natural features and human structures and linked to surveys within local political jurisdictions. Under RS land demarcation is governed by a common grid with uniform square shapes, sizes, alignment, and geographically-based addresses. In the U.S. MB is used principally in the original 13 states, Kentucky, and Tennessee. The RS is found elsewhere under the Land Ordinance of 1785 that divided federal lands into square-mile sections. We develop an economic framework for examining land demarcation systems and draw predictions. Our empirical analysis focuses on a 39-county area of Ohio where both MB and RS were used in adjacent areas as a result of exogenous historical factors. The results indicate that topography influences parcel shape and size under a MB system; that parcel shapes are aligned under the RS; and that the RS is associated with higher land values, more roads, more land transactions, and fewer legal disputes than MB, all else equal. The comparative limitations of MB appear to have had negative long-term effects on land values and economic activity in the sample area.

The Demarcation of Land and the Role of Coordinating Institutions

This paper examines the origins and economic effects of the two dominant land demarcation systems: metes and bounds (MB) and the rectangular system (RS). Under MB property is demarcated by its perimeter as indicated by natural features and human structures and linked to surveys within local political jurisdictions. Under RS land demarcation is governed by a common grid with uniform square shapes, sizes, alignment, and geographically-based addresses. In the U.S. MB largely is used in the original 13 states, Kentucky, and Tennessee. The RS is found elsewhere under the Land Ordinance of 1785 that divided federal lands into square-mile sections. We develop an economic framework for examining land demarcation systems and draw predictions. Our empirical analysis focuses on a 39-county area of Ohio where both MB and RS were used in adjacent areas as a result of exogenous historical factors. The results indicate that topography influences parcel shape and size under a MB system; that parcel shapes are aligned under the RS; and that the RS is associated with higher land values, more roads, more land transactions, and fewer legal disputes than MB, all else equal. The comparative limitations of MB appear to have had negative long-term effects on land values and economic activity in the sample area.

Evaluation of Portable Multi-Gas Analyzers for use by Safety Personnel

During confined space entry operations as well as Shuttle-safing operations, United Space Alliance (USA)/National Aeronautics and Space Administration (NASA) safety personnel use a variety of portable instrumentation to monitor for hazardous levels of compounds such as nitrogen dioxide (N%), monomethylhydrazine (NMM), FREON 21, ammonia (NH3), oxygen (O2), and combustibles (as hydrogen (H2)). Except for O2 and H2, each compound is monitored using a single analyzer. In many cases these analyzers are 5 to 10 years old and require frequent maintenance. In addition, they are cumbersome to carry and tend to make the job of personnel monitoring physically taxing. As part of an effort to upgrade the sensor technology background information was requested from a total of 27 manufacturers of portable multi-gas instruments. A set of criteria was established to determine which vendors would be selected for laboratory evaluation. These criteria were based on requests made by USA/NASA Safety personnel in order to meet requirements within their respective areas for confined-space and Shuttle-safing operations. Each of the 27 manufacturers of multi-gas analyzers was sent a copy of the criteria and asked to fill in the appropriate information pertaining to their instrumentation. Based on the results of the sensor criteria worksheets, a total of 9 vendors out of 27 surveyed manufacturers were chosen for evaluation. Each vendor included in the final evaluation process was requested to configure each of two analyzers with NO2, NH3, O2, and combustible sensors. A set of lab tests was designed in order to determine which of the multi-gas instruments under evaluation was best suited for use in both shuttle and confined space operations. These tests included linearity/repeatability, zero/span drift response/recovery, humidity, interference, and maintenance. At the conclusion of lab testing three vendors were selected for additional field testing. Based on the results of both the lab and field evaluations a single vendor was recommended for use by NASA/IJSA Safety personnel. Vendor selection criteria, as well as the results from both laboratory and field testing of the multi-gas analyzers, are presented as part of this paper

Complement increases release of proinflammatory and proangiogenic mediators by retinal pigment epithelial cells

Objectives. A mutation in complement factor H (CFH) gene, leading to augmented complement activation, is correlated with development of age-related macular degeneration (AMD). Therefore, the influence of complement on retinal pigment epithelial (RPE) cells was examined concerning their production of proinflammatory and proangiogenic mediators relevant in AMD. Methods. ARPE-19 cells were cultured with human or fetal calf serum (FCS). Therefore, complement containing native serum as well as the heat-inactivated form with inoperable complement was used. Further, RPE cells were treated with zymosan, a complement activating yeast particle. Serum and zymosan in combination was also tested. Levels of interleukin (IL)-6, -8 and vascular endothelial growth factor (VEGF) in supernatants were examined by ELISA. Results. Untreated RPE cells produced IL-6, -8 and VEGF constitutively. FCS or human serum led to a concentration dependent release of all mediators. Thereby, FCS increased the cytokine production stronger than human serum, native serum stronger than heat-inactivated. Zymosan only intensified IL-6 and -8 secretion. Combined treatment with serum and zymosan resulted in an additive release of IL-8 and VEGF. In contrast, secretion of IL-6 was synergistic. Conclusion. The enhanced expression of IL-6, -8 and VEGF by RPE after exposure to complement might explain the correlation between augmented complement production and inflammatory processes accompanying AMD. IL-6 production was strongly increased due to activation of complement within the serum by zymosan. Thus, complement activation could stimulate inflammatory processes by activated RPE cells leading to AMD

Retinal pigment epithelial cells respond to complement by an augmented production of vitronectin

Objectives: Genetic studies have demonstrated the role of activated complement on the alternative pathway during the development of age-related macular degeneration (AMD). The extracellular matrix component vitronectin can protect against activated complement. Drusen appear in the retina between the retinal pigment epithelial (RPE) cell layer and Bruch’s membrane. Drusen are hallmarks of early and late AMD and contain high amounts of vitronectin. Therefore this study addressed the influence of complement on the vitronectin production by RPE cells. Methods: ARPE-19 cells as model for RPE cells were cultivated with increasing amounts of human serum as complement source in its naïve and heat (and thereby complement) inactivated form. In another series of experiments zymosan as an activator of the alternative pathway of complement was tested alone and in combination with naïve human serum. Vitronectin was assayed in situ by immunohistochemistry, on protein level by western blot and by PCR after reverse transcription of total RNA. Results: A constitutive production of vitronectin by RPE cells was detected by all three tests. With naïve human serum increased vitronectin protein was found by immunohistochemistry and western blot while the number of mRNA transcripts was not significantly altered. The vitronectin production was further enhanced with the combination of zymosan and naïve human serum while heat inactivated serum showed lesser effect. Conclusion: Activated complement lead to an augmented vitronectin production by RPE cells on post-transcriptional level. Enhanced complement activation during AMD might also contribute in vivo to an enhanced production of vitronectin by RPE cells. On the one hand this can cause protection against activated complement but on the other hand the increased retinal vitronectin might contribute to thickening of Bruch’s membrane and may facilitate the development of drusen

How islands stir and fertilize the upper ocean

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Large Scale Institutional Changes: Land Demarcation Within the British Empire

This paper examines the economics of large scale institutional change by studying the adoption of the land demarcation practices within the British Empire during the 17th through 19th Centuries. The advantages of systematic, coordinated demarcation, such as with the rectangular survey, relative to individualized, haphazard demarcation, such as with metes and bounds, for reducing transaction costs were understood by this time and incorporated into British colonial policy. Still, there was considerable variation in the institutions adopted even though that the regions had similar legal structures and immigrant populations. We study the determinants of institutional change by developing an analytical framework, deriving testable implications, and then analyzing a data set that includes U.S., Canadian, Australian, and New Zealand temperate colonies using GIS data. We find that a simple framework that outlines the costs and benefits of implementing the demarcation systems can explain the different institutions that are observed. Once in place, these institutions persist, indicating a strong institutional path dependence that can influence transaction costs, the extent of land markets, and the nature of resource use. The agricultural land institutions that we examine remain in force today, in some cases over 300 years later. In this regard, institutions of land are durable, much as are other institutions, such as language and law.

Selective transport of neurotransmitters and modulators by distinct volume-regulated LRRC8 anion channels

In response to swelling, mammalian cells release chloride and organic osmolytes through VRAC volume-regulated anion channels. VRACs are heteromers of LRRC8A and other LRRC8 isoforms (B-E) which are co-expressed in HEK293 and most other cells. The spectrum of VRAC substrates and its dependence on particular LRRC8 isoforms remains largely unknown. We show that besides the osmolytes taurine and myo-inositol, LRRC8 channels transport the neurotransmitters glutamate, aspartate and GABA and the co-activator D-serine. HEK293 cells engineered to express defined subsets of LRRC8 isoforms were used to elucidate the subunit-dependence of transport. Whereas LRRC8D was crucial for the translocation of overall neutral compounds like myo-inositol, taurine and GABA and sustained the transport of positively charged lysine, flux of negatively charged aspartate was equally well supported by LRRC8E. Disruption of LRRC8B or LRRC8C failed to decrease transport rates of all investigated substrates, but their inclusion into LRRC8 heteromers influenced VRAC's substrate preference. This suggested that individual VRACs can contain three or more different LRRC8 subunits, a conclusion confirmed by sequential co-immunoprecipitations. Our work suggests a composition-dependent role of VRACs in extracellular signal transduction

The ratio of pro- and anti-angiogenic cytokines produced by retinal pigment epithelial cells is shifted to support angiogenesis by complement

Purpose The complement system of age-related macular degeneration (AMD) patients is marginally but chronically over-activated. Retinal pigment epithelial (RPE) cells and photoreceptor cells undergo cell death during the development of this potentially blinding eye disease. In this study the balance between the pro-angiogenic vascular endothelial growth factor (VEGF) and the anti-angiogenic pigment epithelium-derived factor (PEDF) by RPE cells in response to complement serum was analysed. Methods Increasing concentrations of complement competent human serum were incubated with human RPE cells. Controls with the addition of zymosan to activate the complement cascade, zymosan alone, and heat-treated serum with inoperative complement were included. The secretion of VEGF and PEDF was measured by sandwich ELISA. Immunocytochemistry was performed for the in situ detection of VEGF and PEDF. The experiments were supplemented by RT-PCR expression analysis and Western Blot detection of both antagonists. Results Human complement competent serum stimulated the RPE cells to produce enhanced amounts of VEGF while unspecific stimuli showed no influence on the secretion of VEGF. The combination of complement competent serum and zymosan was revealed as the most effective treatment for an increased VEGF production. The PEDF-specific staining of RPE cells decreased with augmented concentrations of complement competent serum. PCR data showed an enhanced amount of VEGF-encoding transcripts and an unaltered or lower amount of PEDF-specific transcripts. Western Blots confirmed the shift in favour of VEGF when compared to PEDF after complement treatment of RPE cells. Conclusions Activated complement may shift the balance between VEGF and PEDF produced by RPE cells towards the blood vessel chemoattractant VEGF. This finding may reveal a mechanism how enhanced complement activation might contribute to a pro-angiogenic retinal environment supporting neovascularisation during the late stage of exsudative AMD