Previous research has identified the nucleus accumbens (NAcb) as an important brain region underlying inter-individual variation in impulsive behavior. Such variation has been linked to decreased dopamine (DA) D2/3 receptor availability in the ventral striatum of rats exhibiting spontaneously high levels of impulsivity on a 5-choice serial reaction time (5-CSRT) test of sustained visual attention. This study investigated the involvement of DA D2/3 receptors in the NAcb core (NAcbC) and the NAcb shell (NAcbS) in impulsivity. We investigated the effects of a DA D2/3 receptor antagonist (nafadotride) and a DA D2/3 partial agonist (aripiprazole) infused directly into either the NAcbC or NAcbS of rats selected for high (HI) and low (LI) impulsivity on the 5-CSRT task. Nafadotride increased significantly the level of impulsivity when infused into the NAcbS, but decreased impulsivity when infused into the NAcbC of HI rats. By contrast, intraNAcb microinfusions of aripiprazole did not affect impulsivity. Systemic administration of nafadotride had no effect on impulsive behavior but increased the number of omissions and correct response latencies, whereas systemic injections of aripiprazole decreased impulsive and perseverative behavior, and increased the number of omissions and correct response latencies. These findings indicate an opponent modulation of impulsive behavior by DA D2/3 receptors in the NAcbS and NAcbC. Such divergent roles may have relevance for the etiology and treatment of clinical disorders of behavioral control, including attention-deficit hyperactivity disorder and drug addiction.

In a randomized, double-blind, controlled study, 28 patients with early scleroderma received dipyridamole (225 mg/day) and aspirin (975 mg/day) or placebo for 1-2 years. No significant clinical or objective laboratory improvement was noted in either group. Platelet survival time, plasma renin activity, and coagulation tests were not predictive of disease course. Biomechanical and vascular tests of the hands correlated with clinical extent of skin induration and presence of finger ulcers, respectively.The cause of systemic sclerosis (scleroderma) is unknown, and to date there is no effective therapy for it. A vascular hypothesis for its pathogenesis has been ~_ _ _ From the Mayo Clinic and Mayo Foundation, Rochester, Minnesota.

The calibrated spoon was the most accurate producing a mean volume of 5 ml, while the oral syringe had the smallest variance. The increased variability of calibrated or metal spoons may result in under or overdosing especially when administering drugs with a narrow therapeutic window. Health care professionals must make a case-by-case decision regarding which device is preferable depending on the medication in question. Parental education could improve measuring accuracy.

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