Curtis C. Harris

Studies of Ultrastructure, Cytochemistry, and Organ Culture of Human Bronchial Epithelium

In these studies human bronchi removed at time of surgery of “immediate autopsy” from both cancer and non-cancer patients are studied by light and electron microscopy and cytochemistry and cultured in vitro with serial studies of morphology and metabolism. Segments removed from humans are cultured in CMRL 1066 containing insulin and hydrocortisone with or without 5% inactivated fetal calf serum and with or without addition of vitamin A. Segments have been stored at 0–4°C in L-15 medium for up to 2 days prior to successful culture. Cultures are carried out in plastic Petri dishes on rocking platforms in chambers gassed with 45% oxygen, 50% nitrogen, and 5% CO2. The epithelial preservation can be seen by both light and electron microscopy and cultured tissues show normal areas of metaplasia and dysplasia. Specimens have so far been maintained for as long as 4 months with good maintenance of ultrastructure.

A Non-Tumorigenic Human Liver Epithelial Cell Culture Model for Chemical and Biological Carcinogenesis Investigations

A new medium has been formulated that will support in vitro replication of normal human liver epithelial cells for 4 passages (12 population doublings). The replicating cells uniformly contain keratin 18, but keratin 19 is not detectable. In addition, albumin remains discernable in many of the cells throughout their culture life-span. The SV40 large T-antigen gene has been introduced into the genome of cells from six cultures that were initiated from both adult and neonatal donors. The life spans of two of these are indefinite whereas, the others have extended population doubling potentials. The transformed cells have near-normal karyotypes and, initially, they express cytokeratin 18, albumin, and cytochromes. With continued passaging, however, they became positive also for cytokeratin 19 and loose expression of most hepato-specific proteins. However, when incubated as roller cultures, the cells re-acquire the ability to metabolize benzo[a]pyrene, aflatoxin B1, and dimethylnitrosamine to electrophilic derivatives that form carcinogen-DNA adducts. Further, when co-cultured with fibroblasts or on extracted basement membrane material, the cells synthesize albumin and acute phase proteins.Therefore, by using appropriate culture conditions, the “immortalized” human liver epithelial cells may serve as a useful model for chemical and biological carcinogenesis studies.

A model for forecasting the economic and environmental impact of energy policy

Abstract A method for forecasting national energy output and emissions by detailed energy sector is developed by linking the INFORUM Model, the ESNS Network, and pollution coefficients. Consistency between the assumptions behind the parameters of the Network and those behind the INFORUM input—output coefficients are maintained through the adjustment of the latter coefficients. Pollution coefficients are linked to forecasts of national energy sector output to give emissions by sector; energy output and the resulting emissions forecasts change as the parameters of the network change. By use of the model, changes in energy policy, prices, or investments can be examined for their effects on economic, energy and environmental variables. Two applications are presented. The first attempts to show the impact of alternative input price forecasts on fuel substitution in electricity production and the resulting effects on the economy and the environment. The second examines the potential impacts of offshore oil discovery in the Middle Atlantic.

Induction of Atypical Squamous Metaplasia with Benzo[a]Pyrene in Cultured Hamster Tracheas

Areas of hyperplasia were produced in hamster tracheal epithelium maintained in vitro by exposure to a suspension of benzo[a]pyrene (BP) in gelatin. Typical and atypical epiodermoid metaplasia were seen by 2 weeks. In atypical areas, cell nuclei were enlarged with prominent nucleoli, the cytoplasm contained dense bundles of tonofilaments and the cells were joined by numerous desmosomes. The peak response to the carcinogen was reached 4 weeks after the application of BP and consisted of extensive atypical epidermoid metaplasia. Tracheas treated with gelatin alone maintained a columnar epithelium for 6 weeks of culture. The characteristics of the metaplastic changes in vitro are essentially identical to those described after exposure of the hamster tracheobronchial epithelium to benzo[a]pyrene-ferric oxide in vivo.

The Role of Economic Models in Evaluating Commercial Fishery Resources

Estimates of the value or changes in value of fish resources are necessary to address various issues related to the utilization, development, and management of these resources. Examples of issues for which such estimates are required are federal fishery research and development project planning, consideration of commercial/recreation or fish/petroleum conflicts, analysis of alternative management strategies for domestic fleets, and domestic/ foreign resource allocation decisions. The Fisheries Conservation and Management Act (FCMA) of 19761 set out the decision process for management of fish resources in the U.S. economic zone. The FCMA forms the legal basis for the establishment of quasigovernment Regional Fisheries Management Councils. Although the councils are required to develop management plans for all fish stocks within their jurisdiction, final authority for approving and implementing the plan rests with the Secretary of Commerce. This division of responsibility and authority along with the National Standards included in the FCMA almost assure that there will be conflicts and confusion with regard to consideration of national versus regional benefits. The Water Resources Council Principles and Standards (Water Resources Council) for evaluating waterand land-related resources will merely exacerbate these conflicts and confusion. In the absence of measures of utility, economists have used indirect approaches to estimate resource values. Two commonly used approaches are measures of consumers willingness-to-pay and measures of market values of economic activity. The typical methods of measuring willingness-to-pay are through producer and consumer surpluses derived from estimated supply and market or compensated demand curves; and surveys where consumers are asked directly what they are willing to pay to gain or prevent an action. Typical measures of market values have been the value of output, value added, and employment. The willingness-to-pay approach has received a great deal of attention in the economic literature. Conceptual and empirical applications and problems have been extensively addressed and we do not intend to review these discussions here. Rather, because the market-value approach has received little attention as related to fishery questions, and because the market-value approach may be uniquely suited to address certain important issues, we concentrate on the market-value approach in this paper. We discuss inputoutput models and dynamic econometric models but do not address the associated data and estimating problems. We assume that goods and bads in the economy can be dentified and an appropriate measure of net benefits can be derived from value-added data.2 In fisheries questions we assume excess labor and capital and nonproductive transactions costs resulting from the lack of resource property rights can be identified (McConnell and Norton).

Inducible Nitric Oxide Synthase as a Target for Chemoprevention

Nitric oxide (NO.) was first described as endothelium-derived relaxation factor (EDRF) in the 1980s (1–5). Since then, it has been shown to be a key signaling molecule that mediates both physiological and pathological processes, including vasodilation (6), neurotransmission (7), host defense, (8), platelet aggregation (9,10), and iron metabolism (11,12). Increasing evidence suggests that NO. is a pivotal mediator of inflammatory-associated carcinogenesis because of its impact on DNA damage, cell cycle, and modifications of cancer-related proteins (13–18).

Surpluses in Disequilibrium Urban Land Markets

It is unlikely that urban land markets are in equilibrium. If land markets are out of equilibrium, zones within an urban area would have residential location surpluses. This paper shows how to derive and estimate an index of income surplus by residential zone. The procedure is applied to the Baltimore Metropolitan Area for 1978. Households should be at attracted to zones with high surpluses. A comparison of the estimated location surpluses and growth rates for the Baltimore area show this correspondence. Copyright American Real Estate and Urban Economics Association.

Rail, truck, or small car-- Which is the energy saver?

The authors describe a forecasting model for allocating scarce resources. The model shows that efforts to conserve energy should emphasize smaller autos instead of modal switches.