The development of cerebral aneurysmal arteriopathy in childhood AIDS tends to occur after a prolonged delay and is usually followed by death in a short period of time. The etiology for the vasculitis is unknown. Varicella zoster virus may be the etiology in some of the cases because of its potential to cause this pathology and the striking unilateral arterial involvement found in Case 5. HIV vasculitis is also a possibility, as suggested by the detection of HIV protein or genomic material in two of the four autopsy cases.

Band heterotopia is a severe form of neuronal migration disorder associated with intractable epilepsy and neurologic impairment. Surgical treatment of seizures associated with this malformation has not been reported previously. We report a patient with band heterotopia and poorly controlled atonic seizures causing falls and injury. The patient was treated with anterior corpus callosotomy, with significant postoperative decrease in seizure frequency. Corpus callosotomy is a reasonable alternative to consider in management of patients with cortical heterotopia and intractable seizures.

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In the present review, we summarize the principles governing the transport of fluid and electrolytes across the peritoneum during continuous ambulatory peritoneal dialysis (CAPD) in "average" patients and during ultrafiltration failure (UFF), according to the three-pore model of peritoneal transport. The UF volume curves as a function of dwell time [V(t)] are determined in their early phase by the glucose osmotic conductance [product of the UF coefficient (L p S) and the glucose reflection coefficient (σ σ σ σ σ g )] of the peritoneum; in their middle portion by intraperitoneal volume and glucose diffusivity; and in their late portion by the L p S, Starling forces, and lymph flow. The most common cause of UFF is increased transport of small solutes (glucose) across the peritoneum, whereas the L p S is only moderately affected. Concerning peritoneal ion transport, ions that are already more or less fully equilibrated across the membrane at the start of the dwell, such as Na + (Cl -), Ca 2+ , and Mg 2+ , have a convection-dominated transport. The removal of these ions is proportional to UF volume (approximately 10 mmol/L Na + and 0.12 mmol/L Ca 2+ removed per deciliter UF in 4 hours). The present article examines the impact on fluid and solute transport of varying concentrations of Ca 2+ and Na + in peritoneal dialysis solutions. Particularly, the effect of "ultralow" sodium solutions on transport and UF is simulated and discussed. Ions with high initial concentration gradients across the peritoneum, such as K + , phosphate, and bicarbonate, display a diffusion-dominated transport. The transport of these ions can be adequately described by non-electrolyte equations. However, for ions that are in (or near) their diffusion equilibrium over the peritoneum (Na + , Ca 2+ , Mg 2+ ), more complex ion transport equations need to be used. Due to the complexity of these equations, however, non-electrolyte transport formalism is commonly employed, which leads to a marked underestimation of mass transfer area coefficients (PS). This can be avoided by determining the PS when transperitoneal ion concentration gradients are steep. Perit Dial Int 2004; 24:10-27 www.PDIConnect.com

FK506-induced leukoencephalopathy is a well-known entity in adult organ transplant patients. The neurotoxicity of FK506 immunosuppression is frequently reversible, with either reduction or cessation of the drug. This neurologic syndrome is not well documented in children. We report the clinical and radiologic features in four pediatric cases of FK506 leukoencephalopathy. In two of the four patients this syndrome was reversible.