Cardiac calcifications are more prevalent in children receiving hemodialysis than peritoneal dialysis.

BACKGROUND: Children receiving maintenance dialysis exhibit high cardiovascular (CV) associated mortality. We and others have shown high prevalence of cardiac calcifications (CC) in children with endstage renal disease (ESRD). However, no pediatric study has examined modality difference in CC prevalence. The current study was conducted to assess for a difference in CC prevalence between hemodialysis (HD) and peritoneal dialysis (PD) in children with ESRD. METHODS: 38 patients (19 female, 19 male; mean age 15.5 ± 4.1 years) receiving dialysis (21 HD, 17 PD) were included in the study. CC were assessed by ultrafast gated CT and quantified by Agatston score. Patients received thrice weekly HD for 3 - 3.5 hours or daily continuous cycler PD (CCPD). FGF 23, IL-6, IL-8, and CRP levels were obtained at time of CT. Time-averaged (6 months prior to CT) serum Ca, P, Alb, iPTH, and cholesterol levels were obtained. Patients on aspirin, with evidence of infection, underlying collagen vascular disease were excluded. RESULTS: CC were present in 11/38 patients, but more prevalent in HD vs. PD (9/21 vs. 2/17, p = 0.04). Subjects with CC were older (p = 0.0003), had longer dialysis vintage (p = 0.02) and higher serum phosphorus (p = 0.02) and FGF 23 levels (p = 0.03). HD patients also had significantly higher phosphorus (p = 0.02), FGF 23 (p = 0.009), and IL-8 levels (p = 0.02) when compared to PD patients. Residual renal function was not different between modalities or patients with CC. On a multinomial regression model, modality, and age remained independent associations for CC prevalence. CONCLUSION: We have shown that pediatric patients receiving CCPD have lower CC prevalence conferring lower CV risk. The better control of mineral imbalance in patients receiving PD may play an important role in lower CC prevalence.

Multiple hypothalamic sites control the frequency of hippocampal theta rhythm.

Stimulation of a neural pathway originating in the brainstem reticular formation, with synapses in the medial hypothalamus, activates the hippocampal theta rhythm. The frequency of reticular-elicited theta is determined in the medial supramammillary nucleus (mSuM) completely in anaesthetised rats, but only partially when the animal is awake. We tested other medial hypothalamic sites for their capacity to control theta frequency in awake rats. Blockade of sodium channels (1 microl fast infusion of the local anaesthetic procaine, experiment 1) or increased inhibition by GABA (Chlordiazepoxide [CDP], experiment 2) was found to reduce or increase the frequency of reticular-elicited theta, depending on the precise site of injection, in the region of the dorsomedial hypothalamic nucleus (DMH) and the posterior hypothalamic nucleus (PH). A band of null sites for CDP was located in the region of the ventral border of PH and dorsal border of mSuM. Using 0.5 and 1 microl CDP, and slow infusions (experiment 3), it was found that effective PH sites were also separate from mSuM in the rostrocaudal direction. In experiment 4, the DMH/PH region was mapped with unilateral and bilateral slow infusions of 0.5 microl CDP. CDP significantly reduced frequency in medial (periventricular) and dorsal PH, but not DMH. Bilateral injections appeared to generally sum the usual effects of unilateral injection, producing effects of intermediate size. However, the absolute frequency change in any given site, or with any pair of sites, did not exceed 1 Hz, which is similar to what is seen with single injections in mSuM. Overall, it appears that at, any one time, theta frequency may be determined by a complex interplay between distinct but interacting modulatory regions in the medial hypothalamus.