A simulation of food-web interactions leading to rainbow smelt Osmerus mordax dominance in Sparkling Lake, Wisconsin.

A process-based simulation model was used to examine the nature and intensity of food-web interactions that allow Osmerus mordax to dominate invaded lakes. The model simulates food-web interactions among linked populations of O. mordax, Coregonus artedi and Sander vitreus. Simulations indicated that O. mordax dominate where: (1) adult O. mordax prey on young-of-the-year (YOY) C. artedi, (2) YOY O. mordax negatively affect YOY S. vitreus through competition and (3) adult S. vitreus experience moderate fishing mortality. Osmerus mordax dominated simulations across a broad range of variable values that regulated competition and predation, and displayed threshold responses to increasing angler harvest. Consequently, angler harvest should be carefully managed in lakes susceptible to O. mordax invasions because the alternative could lead to fishery collapse.

Analysis of Michigan Medicaid costs to treat HIV infection.

To obtain better understanding of the nature and cost of health care related to human immunodeficiency virus (HIV) infection, medical payment records were analyzed for 204 men, women, and children older than 60 months who had indications of HIV infection. The records were those of Michigan Medicaid, the General Assistance Medical Program, and the Resident County Hospitalization Program, with service dates on or after January 1, 1984, and which were processed by November 30, 1987. Patient payment records were coded according to whether the patient's condition was considered to be pre-HIV, HIV unrelated, possibly HIV related, or HIV related. Average monthly payments were found to be $150 for pre-HIV patient payment records, $114 for those HIV unrelated, $57 for those possibly related, and $1,213 for those related to HIV infection. HIV-related monthly payments rose from about $1,500 per month in the period 3 months prior to the patient's death to more than $8,000 in the last month of life. Men were found to have twice as many claims as women, and men's claims cost about three times as much. A higher percentage of women than men (91 percent versus 37 percent) received pre-HIV paid services, indicating a higher percentage of women were at least initially receiving Medicaid for reasons other than an HIV-related disability. Diagnostic categories that accounted for the bulk of the HIV-related health care utilization included infectious and parasitic diseases, acquired immunodeficiency syndrome, diseases of the respiratory system, and non-HIV-specific immunity disorders. Inpatient hospitalization accounted for more than 75 percent of the payments, followed by physician costs (11 percent), pharmacy costs (5 percent), and outpatient costs (3 percent). A total of 45, or about 22 percent of the recipients, received zidovudine (AZT) prescriptions at an average monthly cost of $404.

The Hopkins experience with lesions of the dorsal horn (Nashold's operation) for pain from avulsion of the brachial plexus.

Lesions of the dorsal horn (DREZ operation) have been reported to be useful in reducing pain secondary to avulsion of the brachial plexus. Ten patients had the DREZ operation for this condition at The Johns Hopkins Hospital by one of us (JNC) between 1981 and 1985. Radiofrequency heat lesions were made. The patients were interviewed 7-52 months after the operation by one of two individuals not involved in the procedure to assess pain relief and postoperative complications. The mean pain relief was 85%, and there were no significant complications. It is concluded that the DREZ operation is the treatment of choice for treatment of severe pain that results from avulsion of the brachial plexus.