Both systemic and central administration of theophylline and caffeine produced a dose‐dependent rise in rectal temperature at ambient temperatures of 8, 22 and 30°C. The hyperthermia in response to either xanthine was brought about by an increase in metabolic heat production. In addition, their administration produced behavioral excitation, cutaneous vasodilation (as estimated by an increase in the foot and tail skin temperatures) and diuresis. There was no change in respiratory evaporative heat loss. Probably, the hyperthermia induced by the two drugs was due to behavioral excitation leading to an increased metabolism at the ambient temperatures studied. Furthermore, either destruction of central catecholaminergic nerve fibres (with 6‐hydroxydopamine) or blockade of α‐adrenergic and dopaminergic (with phentolamine and haloperidol) receptors antagonized the xanthine‐induced hyperthermia. The data suggest that these xanthines elicit a central activation of both adrenergic and dopaminergic receptors via release of endogenous catecholamines that leads to behavioral excitation and hyperthermia in rats.

The introduction of highly active antiretroviral therapy has proven highly effective in treating patients with HIV/AIDS. However, the high cost of the advanced antiretroviral therapy has led to increased financial constraints on both patients and payers. From business firms'perspective, especially those with operations in developing countries, it is crucial to determine the long-term economic cost implications of alternative employment and benefit policies for HIV-infected workers or those at high risk for the disease. A simulation model is developed to predict the comprehensive lifetime economic costs of HIV-infected workers to an employer. This model employs age,CD4(+) cell counts,and plasma HIV-1 RNA level as major predictors of the disease progression and patient survival in the determination of various cost functions. Major cost components considered include direct expenses on health insurance premium,life insurance premium, short-term disability benefits, long-term disability benefits, hiring/training expenses, and indirect costs resulting from reduced or lost productivity at work. An individual model and a group model are derived to estimate the costs of an individual and a group of HIV-infected patients, respectively. Over a 10-year period, following the nonadvanced antiretroviral treatment regimen, the group model predicts that the total lifetime cost of an HIV-infected worker can be as high as U.S. 90,000 dollars to his/her employer, of which 60,000 dollars would be various explicit costs and 30,000 dollars lost work productivity. Sensitivity analysis further demonstrated that changes in the initial level of age,CD4(+) cell count, HIV-1 RNA viral load,CD4(+) cell decline rate, and the costs of medical care influence the dynamics of the cost functions. HIV infection can result in sizable economic costs to an employer over the lifetime course of an infected employee if not treated with the advanced antiretroviral therapy. These cost estimates provide a rational economic basis for an employer to optimally assess the longrun costs and benefits of alternative employment and insurance policies in the care of employees with HIV infection.