Eutrophication of lakes cannot be controlled by reducing nitrogen input: results of a 37-year whole-ecosystem experiment.

Lake 227, a small lake in the Precambrian Shield at the Experimental Lakes Area (ELA), has been fertilized for 37 years with constant annual inputs of phosphorus and decreasing inputs of nitrogen to test the theory that controlling nitrogen inputs can control eutrophication. For the final 16 years (1990-2005), the lake was fertilized with phosphorus alone. Reducing nitrogen inputs increasingly favored nitrogen-fixing cyanobacteria as a response by the phytoplankton community to extreme seasonal nitrogen limitation. Nitrogen fixation was sufficient to allow biomass to continue to be produced in proportion to phosphorus, and the lake remained highly eutrophic, despite showing indications of extreme nitrogen limitation seasonally. To reduce eutrophication, the focus of management must be on decreasing inputs of phosphorus.

Cost per service differentials in local health departments.

An emerging issue in health care is the relative efficiency with which local health departments provide their services. The problem is complicated by the fact that many factors may contribute to variations in efficiency. We have developed a framework for analyzing such variations across departments, using cost per service (CPS) as the measure of efficiency. The approach is illustrated with data from all 82 county or district health departments in North Carolina. CPS levels can be differentially affected by selected uncontrollable characteristics of the serviced population. Thus, when used to evaluate departmental performance, or to determine reimbursement rates, the CPS must be adjusted for relevant exogenous factors. Our method of cluster analysis accounts "naturally" for these factors, thereby allowing for development of policy decisions more responsive to actual health department circumstances.

Leukemia and lymphoma in childhood.

The leukemias and lymphomas together account for over 40% of the malignant disorders in childhood. Radiologists who deal with these patients must understand some aspects of the biology, natural history, and clinical manifestations of the disease in order to provide useful imaging consultative services. This article summarizes these issues briefly, gives an overview of the common imaging appearances, and recommends imaging studies to be utilized in the initial staging evaluation of newly presenting patients.

Use of tissue plasminogen activator for femoral artery thrombosis following transcatheter coil occlusion of patent ductus arteriosus.

Femoral artery thrombosis is an uncommon but potentially serious complication following pediatric cardiac catheterization. Management options include heparin infusion, thrombolytic therapy, and surgical thrombectomy. The use of thrombolytic agents following coil occlusion of shunts, collaterals, and patent ductus arteriosus (PDA) may be successful in resolving the femoral arterial thrombosis but may also reopen the device-occluded vessel. We report the successful use of tissue plasminogen activator for management of femoral artery thrombosis in a child following transcatheter PDA coil occlusion in which the PDA remained occluded.

A measure of the effects of competition in the U.S. health care sector during the 1980s.

For some years now, health planning and management efforts have been assigning greater importance to the values and preferences of patients as consumers of health care services. A key objective of this 'marketing orientation' has been to effect responsible change in the way health services are designed, priced, advertised, and delivered. Implementation of such a philosophy--inconceivable just a few years ago--was originally motivated by the emergence of competitive market forces in the hospital and health care sector. In the current paper, a perspective on the precursors and facilitating factors that gave rise to these forces is presented. With this perspective, the review of two relevant books, one published at the beginning of the 1980s and one towards the end of the decade, will serve as a measure of the large and increasing impact of competition in the U.S. health care sector during the 1980s.

Statistical and other data-analytic techniques for the evaluation researcher: an identification, classification, and description of methods and resources.

The goal of any social/health intervention program is to improve the lot of the people it is designed to serve. Of critical importance is the development and implementation of programs able to achieve such a goal is evaluation research (ER)--a process representing an interface between the generic notion of evaluation and the rigor of social research methodology. The evaluation researcher should be familiar with, and be capable of using, any of a number of (statistical and non-statistical) data-analytic techniques. The objectives of this discussion, therefore, are to (1) identify, categorize, and briefly describe statistical and other data-analytic techniques of potential use to the evaluation researchers; and (2) identify currently available resources, i.e., texts, books of readings, monographs, etc., that offer discussions and analyses of these techniques. It is hoped that such an exposition will lead to a wider understanding, acceptance, and use of these procedures, which can only enhance the quality of subsequent program policy- and decisionmaking.

Quantitative decision techniques for the health/public sector policy-maker: an analysis and classification of resources.

Policy problems in the health and public sectors are quickly assuming a new level of complexity. Thus, the health/public sector analyst is being confronted with the task of identifying, formulating, evaluating, and making choices among larger and more complicated sets of decision alternatives. Given the context of such decisions, less-than-effective choices could adversely affect the health and social well-being of whole sections of a population. What seems to be needed, therefore, is an approach that would provide system and objectivity to the policy-making process. The use of quantitative techniques, so long applied to problems in the private and industrial sectors, would be the mainstay of such an approach. It is the goal of this article, therefore, to identify, classify, and briefly describe elements of the emerging set of materials (texts, edited readings, and monographs) which offer discussions of these techniques as they apply to problems in the health and public sectors. It is hoped that such a presentation will hasten the application of available analytic decision tools to the policy/decision problems of the public sector.

Pyelocalyceal diverticula in the Beckwith-Wiedemann syndrome.

A case of pyelocalyceal diverticula in a patient with the Beckwith-Wiedemann syndrome is presented. The abnormalities were first identified on screening ultrasound and confirmed at excretory urography. The diverticula in this syndrome are likely secondary to hereditary embryopathy of the kidneys.

Juvenile xanthogranuloma of the kidney.

Juvenile xanthogranuloma is a benign histiocytosis of infancy and childhood characteristically involving the skin, the eye, and, rarely, the lungs, liver and mesothelial structures. This report documents the first known case of renal involvement which is demonstrated by ultrasound and computed tomography.

Histiocytosis X: rate and pattern of resolution of osseous lesions.

Resolution rate and qualitative characteristics of healing were studied in 71 osseous lesions of histiocytosis X. Rates of healing, as assessed planimetrically and by vertebral body-height measurement, did not differ significantly among lesions that were treated with chemotherapy alone, chemotherapy plus radiation, radiation alone, or those that received no treatment. Lesions of Letterer-Siwe disease, Hand-Schuller-Christian disease, multiple eosinophilic granuloma, and solitary eosinophilic granuloma resolved at comparable rates. A trend toward more rapid healing was noted in younger children. Lesions treated with radiation alone showed a greater tendency to resolve with sclerosis, but radiographic healing characteristics did not strictly depend upon specific mode of therapy. These results support the concept of osseous histiocytosis X as a benign self-limited disorder when systemic disease is absent, and they encourage therapeutic conservatism.

Primary coccidioidomycosis in children presenting with massive pleural effusion.

Large pleural effusion as the presenting feature of coccidioidomycosis in childhood has not previously been reported and may cause significant diagnostic difficulty. Three children are described who required prolonged hospitalization and therapy with amphotericin B. Primary coccidioidomycosis should be included in the differential diagnosis of large pleural effusions in pediatric patients who have been in the endemic area. Such effusions suggest a severe form of the disease and may represent evidence of acute dissemination.

Improving the selection of family medicine residents through development of multi-dimensional policy models.

The annual cost of training a single family medicine resident may now exceed $50,000. This, together with the fact that normally only a small fraction of those applying for family medicine residency is selected for admission, creates a decision problem of enormous import to affected institutions. Despite these considerations, the applicant evaluation and selection process remains relatively subjective, with results often disappointing. In the current paper, a preference-based approach is proposed that first models the evaluation/selection process on the basis of well-defined cognitive and noncognitive criteria. It is suggested that validation of this model be based on future performance levels of both the accepted and rejected cohorts during and following their residencies. Discrepancies between future success levels and predicted outcomes may then be translated into appropriate control actions designed: (1) improve the definition/measurement of selection criteria; (2) enhance the evaluation/selection policies and decisions of the admissions committee; and (3) better inform potential applicants of the department's program and selection philosophies. The approach is applied to two recent, accepted cohorts of the University of North Carolina Department of Family Medicine. Preliminary results indicate that the procedure is capable of improving the in-residency success levels of selected applicants, and that these levels can be better predicted than when no formal, i.e., analytic, process is followed.

Structuring information systems for more effective disease control programs.

The design of effective health programs involves a complex set of information flows needed to support the planning, implementation, and evaluation of alternative intervention strategies. While several information system models are available, few have actually been applied to specific disease cycles. The objective of this paper is to consider the design of information systems in terms of organizational contextual factors and user/decision-maker preferences relevant to the structure and operation of such information systems. A heuristic procedure is developed and applied to the design of information systems responsible for supporting effective parasitic disease control efforts. Recent research based on this application indicates substantial technical advantages to an intersectoral, multidimensional approach to parasitic disease control. In particular, analysis reveals that information system designs can significantly enhance the effectiveness of disease intervention through a higher level of sensitivity to such factors as disease etiology, socioeconomic conditions, and population health beliefs and perceptions.

Heuristic approaches to decision-making in the delivery of primary health care within developing regions.

The delivery of primary health care (PHC) services is now recognized as a crucial element in the development of low-income regions. Effective delivery of these services requires the ability to solve a variety of policy decision problems. Research has demonstrated the utility of operations research/management science (OR/MS) models and methodologies in the analysis and solution of such problems. However, this approach may be limited in some regions by the data and computational requirements of the models. Intuitive approaches in the spirit of OR/MS models, termed heuristics, can provide an effective alternative in such cases. The current paper proposes a general heuristic procedure for solving problems of PHC delivery in developing regions. The heuristic is applied, in detail, to the problem of identifying "best" community financing schemes for PHC services in low-income sections of Rio de Janeiro, Brazil.

Renal oxypurine deposition in Lesch-Nyhan syndrome: sonographic evaluation.

Lesch-Nyhan syndrome is a rare X-linked recessive disorder of purine metabolism associated with a virtually complete deficiency of the enzyme hypoxanthine-guanine phosphoribosyl-transferase (HPRT). The disease is characterized by hyperuricemia, self-multilation, choreoathetosis, spasticity, and mental retardation. The abnormalities of purine metabolism are present at birth and may lead to uric acid crystalluria and stone formation early in life. Radiographic findings described in Lesch-Nyhan syndrome include faintly radio-opaque stones on abdominal radiographs or, if renal disease is present, small kidneys with poor function on intravenous urogram. Radiolucent stones are usually composed of uric acid; however, several cases of xanthine and hypoxanthine-containing calculi in Lesch-Nyhan patients receiving allopurinl therapy have also been described. Oxypurine is the collective name for the compounds hypoxanthine, xanthine, and uric acid, and all may be radiolucent. We report a case of Lesch-Nyhan syndrome with presumed renal parenchymal oxypurine deposition demonstrated readily by ultrasonography but not detected on standard radiographs or intravenous urograms.