IMPACT: a generic tool for modelling and simulating public health policy.

BACKGROUND: Populations are under-served by local health policies and management of resources. This partly reflects a lack of realistically complex models to enable appraisal of a wide range of potential options. Rising computing power coupled with advances in machine learning and healthcare information now enables such models to be constructed and executed. However, such models are not generally accessible to public health practitioners who often lack the requisite technical knowledge or skills. OBJECTIVES: To design and develop a system for creating, executing and analysing the results of simulated public health and healthcare policy interventions, in ways that are accessible and usable by modellers and policy-makers. METHODS: The system requirements were captured and analysed in parallel with the statistical method development for the simulation engine. From the resulting software requirement specification the system architecture was designed, implemented and tested. A model for Coronary Heart Disease (CHD) was created and validated against empirical data. RESULTS: The system was successfully used to create and validate the CHD model. The initial validation results show concordance between the simulation results and the empirical data. CONCLUSIONS: We have demonstrated the ability to connect health policy-modellers and policy-makers in a unified system, thereby making population health models easier to share, maintain, reuse and deploy.

Stability of fluconazole and amino acids in parenteral nutrient solutions.

The stability of fluconazole and amino acids in parenteral nutrient (PN) solutions was studied. Amino acids at three concentrations (1.0%, 2.5%, and 5.0%) with 25% dextrose injection were combined with a high (1.75 mg/mL) or a low (0.5 mg/mL) concentration of fluconazole to form six combinations of PN solution and fluconazole. The solutions were visually inspected for precipitate, color change, or gas formation and tested for pH. By using high-performance liquid chromatography, the solutions were assayed for fluconazole concentration at zero, one, and two hours after preparation. The PN solution containing fluconazole 1.75 mg/mL and 5.0% amino acids was assayed for 14 amino acids at the same time points. There was no visual evidence of incompatibility in any of the fluconazole and PN solutions, and the pH of the solutions did not vary appreciably throughout the study period. The mean percentage of initial fluconazole concentration remaining at one and two hours was greater than 97% for all of the solutions studied. The mean percentage of initial amino acid concentration remaining at one and two hours was greater than 93% for each of the 14 amino acids assayed. When fluconazole 0.5 mg/mL or 1.75 mg/mL is mixed with PN solution containing 1.0%, 2.5%, or 5.0% amino acids and 25% dextrose injection, both fluconazole and amino acids are stable for up to two hours.

Prevention of Lyme disease.

Lyme disease and the use of tick repellents and physical protective measures to prevent the disease are discussed. Lyme disease is a multiple-organ-system, immune-mediated inflammatory disorder transmitted by the bites of ixodid ticks infected with Borrelia burgdorferi. An individual is at greatest risk for infection when a tick has been attached to the skin for more than 24 hours. Lyme disease occurs in three stages and may affect the skin, nervous system, cardiac system, and joints. Antimicrobials used in management consist primarily of penicillins, cephalosporins, tetracyclines, and erythromycin. Tick repellents are divided into those applied to the skin and those applied to clothing. Skin repellents include N,N-diethyl-meta-toluamide (DEET), 2-ethyl-1,3-hexanediol, and dimethyl phthalate. Permethrin is by far the most effective clothing repellent. DEET plus a permethrin-containing clothing repellent offers the best overall protection. The adverse effects of repellents are minimal, but cases of hypersensitivity have been reported, especially in children. Physical measures to prevent tick bites include avoiding tick-infested areas, wearing light-colored clothing for easy identification of crawling ticks, regularly checking the body and pets for ticks, wearing protective garments and closed-toed shoes, and removing attached ticks promptly by using tweezers or forceps to apply a steady upward pull. A vaccine for the active immunization of humans against Lyme disease remains to be developed. Although antimicrobial therapy is available for persons with Lyme disease, the best approach for those who may be exposed to infected ticks is to apply topical skin or clothing repellents and to practice common-sense measures of physical protection.

Management of uremic bleeding.

The pathogenesis, clinical manifestations, and management of uremic bleeding are discussed, and the role of pharmacologic intervention in the treatment of this disorder is emphasized. Care of the patient with uremia is frequently complicated by spontaneous, life-threatening bleeding episodes. Although not completely elucidated, this bleeding tendency may be associated with ineffective binding of the von Willebrand Factor (a component of factor VIII) to platelet membranes, acquired storage-pool deficiency, and anemia. Uremic patients may develop a number of clinical manifestations, including epistaxis, purpura, and bleeding from the gastrointestinal tract. Dialysis, while frequently effective for the short term, does not completely correct platelet dysfunction. Red-blood-cell transfusions may partially reduce bleeding time; however, their use places the patient at risk for viral infection. Cryoprecipitate is often used in acute situations because of its short onset of action. Desmopressin is likewise effective when an immediate effect is desired. Conjugated-estrogen therapy appears beneficial for patients in whom a long-lasting effect is desired. Management of uremic bleeding may include dialysis, red-blood-cell transfusions, cryoprecipitate, desmopressin, and conjugated estrogens. Adverse effects, particularly the risk of viral infection, as well as duration of action, must be considered in therapy selection.

Genetical variation for enzyme activity in a population of Drosophila melanogaster. VI. Molecular variation in the control of alcohol dehydrogenase (ADH) activity.

Four characters, ADH activity at 25 degrees, immunologically determined ADH protein level, total protein and body weight were measured upon 72 hour old adult female and male Drosophila melanogaster from 16 highly inbred lines, derived from the laboratory population, "Texas" (established 1966). The highest levels of ADH activity and ADH protein level were observed in the 2 lined homozygous for the AdhF allele. Amongst the 14 AdhS/S lines variation for ADH protein level was associated with genetical variation for ADH activity (r = 0.6). The genetical association between ADH activity or ADH protein level and either body weight or total protein in the 16 inbred lines was not statistically significant. A study of ADH activity, ADH protein and total protein in 8 lines representing all homozygous combinations of chromosomes I, II and III and derived from two inbred AdhS/S lines, chosen for their respective high and low ADH activities, showed that ADH activity was considerably modified by a post-translational event controlled from chromosome III. Total protein was controlled by different chromosomal effects from those controlling ADH activity. Michaelis constants for crude fly extracts of the two AdhF/F and the above two AdhS/S lines showed clear differences in affinity for isopropanol.