Hypoxia reveals posterior thalamic, cerebellar, midbrain, and limbic deficits in congenital central hypoventilation syndrome.

Congenital central hypoventilation syndrome (CCHS) patients show deficient respiratory and cardiac responses to hypoxia and hypercapnia, despite apparently intact arousal responses to hypercapnia and adequate respiratory motor mechanisms, thus providing a model to evaluate functioning of particular brain mechanisms underlying breathing. We used functional magnetic resonance imaging to assess blood oxygen level-dependent signals, corrected for global signal changes, and evaluated them with cluster and volume-of-interest procedures, during a baseline and 2-min hypoxic (15% O(2), 85% N(2)) challenge in 14 CCHS and 14 age- and gender-matched control subjects. Hypoxia elicited significant (P < 0.05) differences in magnitude and timing of responses between groups in cerebellar cortex and deep nuclei, posterior thalamic structures, limbic areas (including the insula, amygdala, ventral anterior thalamus, and right hippocampus), dorsal and ventral midbrain, caudate, claustrum, and putamen. Deficient responses to hypoxia included no, or late, changes in CCHS patients with declining signals in control subjects, a falling signal in CCHS patients with no change in controls, or absent early transient responses in CCHS. Hypoxia resulted in signal declines but no group differences in hypothalamic and dorsal medullary areas, the latter being a target for PHOX2B, mutations of which occur in the syndrome. The findings extend previously identified posterior thalamic, midbrain, and cerebellar roles for normal mediation of hypoxia found in animal fetal and adult preparations and suggest significant participation of limbic structures in responding to hypoxic challenges, which likely include cardiovascular and air-hunger components. Failing structures in CCHS include areas additional to those associated with PHOX2B expression and chemoreceptor sites.

Sorption of traces of silver ions onto polyurethane foam from acidic solution.

The sorption of traces of silver ions onto polyurethane foam (PUF) has been investigated in detail. Maximum sorption of silver (K(d)=6109 cm(3) g(-1), %sorption>97.5%) has been achieved from 1 M nitric acid solution after equilibrating silver ions with approximately 29 mg PUF for 20 min. The kinetics and thermodynamics of the sorption of silver ions onto PUF have also been studied. The sorption of silver ions onto PUF follows a first-order rate equation, which results as 0.177 min(-1). The variation of sorption with temperature yields the values of DeltaH=-56.1+/-3.2 kJ mol(-1), DeltaS=-159.7+/-10.5 J mol(-1) K(-1) and DeltaG=-8.68+/-0.09 kJ mol(-1) at 298 K with a correlation factor gamma=0.9919. The sorption data were subjected to different sorption isotherms. The sorption follows Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The values of Langmuir isotherms Q=65.4+/-1.5 mumol g(-1) and b=(4.79+/-1.16)x10(4) dm(3) mol(-1) have been evaluated for Langmuir sorption constants, whereas the Freundlich sorption isotherm gives the value 1/n=0.12+/-0.02 and A=0.15+/-0.03 mmol g(-1). The D-R parameters computed were beta=-0.000817+/-0.000206 mol(2) kJ(-2), X(m)=76.8+/-8.7 mumol g(-1) and E=24.7+/-3.2 kJ mol(-1). The influence of common ions on the sorption was also examined. It is observed that Hg(II), thiourea, Al(III), thiocyanate and thiosulphate reduce the sorption, whereas Cu(II), citrate and acetate ions enhance the sorption significantly. It can be concluded that PUF may be used to remove traces of silver ions from its very dilute solutions or for its preconcentration from aqueous acidic solutions.

Should children with suspected obstructive sleep apnea syndrome and normal nap sleep studies have overnight sleep studies?

STUDY OBJECTIVES: Overnight polysomnography (ONP) is the "gold standard" for the diagnosis of sleep-disordered breathing, but it is expensive and time-consuming. Thus, daytime nap studies have been used as screening tests. If the findings of a nap study are normal or mildly abnormal, should ONP be performed? Do specific abnormalities in nap studies predict abnormal findings in ONP? To answer these questions, we conducted this study. DESIGN: Retrospective chart review. SETTING: Children's hospital. PARTICIPANTS: One hundred forty-three children with suspected obstructive sleep apnea syndrome secondary to isolated adenotonsillar hypertrophy, who had normal or mildly abnormal nap studies, and underwent ONP. MEASUREMENTS AND RESULTS: We compared daytime nap and overnight polysomnograms in 143 children (52 girls; mean [+/- SD] age, 5.6 +/- 3.1 years). Total sleep time was 1 h in daytime nap, and 5.1 +/- 1.3 h in ONP. The interval between the two studies was 5.9 +/- 4.8 months. The findings of 59% of the nap studies were mildly abnormal, while 66% of overnight studies were abnormal. No individual nap study parameter (including short obstructive apneas, hypopneas, hypoxemia, hypoventilation, snoring, paradoxical breathing, gasping, retractions) had good sensitivity at predicting abnormal overnight polysomnograms, but most had good specificity and positive predictive value. CONCLUSIONS: We conclude that individual nap study parameters are not very sensitive in predicting abnormal ONP findings. However, when nap study parameters are abnormal, the chance of obstructive sleep apnea syndrome is high.

Prognosis in pediatric idiopathic pulmonary hemosiderosis.

STUDY OBJECTIVES: Previously, IPH patients have been reported to have an average survival of 2.5 years. However, at our institution, many IPH patients have survived longer than that. Therefore, we conducted this study to determine the clinical course and current mortality of pediatric IPH patients treated with immunosuppressants. DESIGN: Retrospective chart review. SETTING: Children's hospital. PARTICIPANTS: Seventeen patients in whom IPH was diagnosed between 1972 and 1998. MEASUREMENTS AND RESULTS: Mean age at diagnosis was 4.5 +/- 3.5 years, and 12 patients were female. At diagnosis, all patients had anemia and pulmonary infiltrates; 85% had hypoxemia, 65% had hemoptysis, and 70% had fever. The diagnosis was made by open lung biopsy in 13 patients (76%), hemosiderin-laden macrophages in BAL fluid in 1 patient (6%), hemosiderin-laden macrophages in gastric aspirate in 2 patients (12%), or by clinical presentation alone in 1 patient (6%). The mean duration of follow-up for all patients was 3.6 +/- 3.4 years (range, 0.7 to 10.2). Initial treatment consisted of prednisone only in 14 patients (82%), and prednisone and hydroxychloroquine in two patients (12%). Thirteen patients (76%) required long-term corticosteroids because of recurrent hemoptysis. Eight patients (47%) required other immunosuppressants (hydroxychloroquine or azathioprine) in addition to prednisone to control their hemoptysis. One patient who was not treated with prednisone remained asymptomatic for 1.8 years. Three patients (17%) died of acute massive pulmonary hemorrhage (4.1 +/- 5.0 years postdiagnosis). CONCLUSION: Five-year survival for IPH patients in our study was 86% (by Kaplan-Meier method). We conclude that these IPH patients who received long-term treatment had a better outcome than those previously reported who were not treated with extended courses of immunosuppressive therapy. We speculate that long-term immunosuppression therapy may improve the prognosis in IPH.