Behavior and neurocognitive performance in children aged 5-10 years who snore compared to controls

Sleep disordered breathing in children is a common but largely underdiagnosed problem. It ranges in severity from primary snoring to obstructive sleep apnea syndrome (OSAS). Preliminary evidence suggests that children with severe OSAS show reduced neurocognitive performance, however, less is known about children who snore but do not have severe upper airway obstruction. Participants included 16 children referred to the Ear, Nose and Throat/Respiratory departments of a Children's Hospital for evaluation of snoring and 16 non-snoring controls aged 5-10 years. Overnight polysomnography (PSG) was carried out in 13 children who snored and 13 controls. The PSG confirmed the presence of primary snoring in seven and very mild OSAS (as evidenced by chest wall paradox) in eight children referred for snoring while controls showed a normal sleep pattern. To test for group differences in neurocognitive functioning and behavior, children underwent one day of testing during which measures of intelligence, memory, attention, social competency, and problematic behavior were collected. Compared to controls, children who snored showed significantly impaired attention and, although within the normal range, lower memory and intelligence scores. No significant group differences were observed for social competency and problematic behavior. These findings suggest that neurocognitive performance is reduced in children who snore but are otherwise healthy and who do not have severe OSAS. They further imply that the impact of mild sleep disordered breathing on daytime functioning may be more significant than previously realized with subsequent implications for successful academic and developmental progress.

UNCL, the mammalian homologue of UNC-50, is an inner nuclear membrane RNA-binding protein

We isolated a mammalian homologue of the C. elegans gene unc-50 that we have named UNCL. The 777 kb rat UNCL cDNA encodes a 259 amino acid protein that is expressed in a wide variety of tissues with highest mRNA levels in brain, kidney and testis. Hydropathy plot analysis and in vitro translation experiments with microsomal membranes indicate that UNCL is a transmembrane protein. Hemagglutinin tagged UNCL was stably transfected into SaOS-2 osteosarcoma cells and exhibited a nuclear rim staining pattern which was retained following extraction with 1% Triton X-100, suggesting that UNCL localizes to the inner nuclear membrane. UNCL-HA was extractable in 350 mM NaCl, suggesting that UNCL is not associated with the nuclear matrix. Homopolymer RNA-binding assays performed on in vitro translated UNCL protein and 'structural modeling by homology' suggest that UNCL binds RNA via an amino-terminal RNA Recognition-like Motif. Since unc-50 is required for expression of assembled muscle-type nicotinic receptors in the nematode we investigated whether UNCL had a similar function for mammalian nicotinic receptors. When UNCL was co-expressed with neural nicotinic receptors in Xenopus oocytes or COS cells it increased expression of functional cell surface receptors up to 1. 6-fold. We conclude that UNCL is a novel inner nuclear membrane protein that associates with RNA and is involved in the cell-surface expression of neuronal nicotinic receptors. UNCL plays a broader role because UNCL homologues are present in two yeast and a plant species, none of which express nicotinic receptors and it is also found in tissues that lack nicotinic receptors.

Cerebral mucormycosis: proton MR spectroscopy and MR imaging

Proton magnetic resonance spectroscopy (MRS) was integrated with magnetic resonance imaging (MRI) in the evaluation of a case of cerebral mucormycosis. MRS showed markedly elevated lactate, depleted N-acetyl aspartate and metabolite resonances attributable to succinate and acetate. The spectroscopy profile is essentially similar to that of bacterial abscess but without the commonly seen resonances of the amino acids valine, leucine and isoleucine. Our extensive literature review did not yield any reports of MRS findings on cerebral mucormycosis. MRS prospectively limited the differential diagnoses given the otherwise nonspecific and complex MR imaging findings in our immunosuppressed patient.

The effect of short-term treatment with micronized estradiol on bone turnover and gonadotrophins in older men

Evidence for the role of estrogen in male bone metabolism has been confirmed by studies on a man with a genetic defect in the estrogen receptor as well as men with aromatase defects. All exhibited tall stature, delayed epiphysial closure, decreased bone density and increased bone turnover. Estrogen is likely to affect bone turnover in men throughout life; therefore, we hypothesized that older men would show decreased bone resorption in response to estrogen therapy. To test our hypothesis, fourteen community-dwelling men with osteopenia of the femoral neck were treated for 9 weeks with micronized estradiol, 1 mg/d, a dose which is effective in postmenopausal women. Each subject served as his own control. Markers of bone resorption, N-terminal collagen crosslinks (NTX) and C-terminal collagen crosslinks (CTX) and markers of bone formation, osteocalcin (OC) and bone specific alkaline phosphatase (BSAP) were measured every 3 weeks during a 9-week treatment period and 9 weeks post-treatment. Sex hormones, gonadotrophins and calciotropic hormones were measured at baseline, 9 weeks on treatment and 9 weeks post- treatment. After 9 weeks of treatment, estradiol and estrone levels increased significantly by greater than 6-fold and 15-fold, respectively. SHBG levels increased significantly by 17%. Testosterone and free testosterone levels decreased significantly by 27% and 34%, respectively. Markers of bone resorption showed wide variation at baseline and while on treatment. There was no correlation between changes in bone markers and changes in estrogen levels. During treatment, 11 patients showed a decrease of NTX or CTX, but three showed an increase. These three and one other subject had high initial levels of FSH and LH, suggesting some degree of primary gonadal failure, which decreased during estrogen therapy. Thus, the change in NTX (and CTX) after 9 weeks of E2 treatment was correlated with initial FSH (r= -.66, p= .01) and LH (r= -.73, p= .003) values. In addition, the largest decrease in free testosterone at 9 weeks was correlated with the higher values for NTX, CTX and BAP (r=-0.66, -0.68, -0.70 respectively; p< or =.01 for each of the markers). Treatment was generally well tolerated. Side effects of treatment were minimal, and included breast tenderness and decreased libido which reversed after treatment. We conclude that it is feasible to give low dose estrogen to healthy older men, but that the effects on bone turnover are not consistent. Changes in central feedback and in endogenous sex hormone production may alter the response of bone turnover to exogenous estrogen in this population.

A rapid and sensitive reporter gene that uses green fluorescent protein expression to detect chemicals with estrogenic activity

A reporter gene sequence was constructed within a eukaryotic expression vector. The altered plasmid contained 2 sequential estrogen response elements (ERE) coupled to a human phosphoglycerate kinase (PGK) promoter inserted upstream from a cDNA sequence encoding enhanced green fluorescent protein (GFP) with a 3'-polyadenylation signal. The plasmid was linearized and transfected into MCF-7 cells, a human breast cancer-derived line that expresses the estrogen receptor (ER). No selectable marker was present in the plasmid, requiring stably transfected cells to be selected by fluorescence-activated cell sorting based on GFP expression after the cells were treated with 10(-9) M 17beta-estradiol (E2). Stably transfected MCF-7 cells (MCF7-ERE) exhibited 2000-3000 times more fluorescence at 488 nm excitation and 512 nm emission than non-transfected cells. MCF7-ERE cells exhibited a linear increase in GFP expression induced over a range of 10(-12) M E2, a concentration giving 2 times the background expression, to maximal expression at 3 x 0(-10) M E2. From the maximal level, GFP expression plateaued, and then declined when E2 was increased to the highest concentration tested, 10(-7) M. 4-Hydroxytamoxifen (TFN-OH) treatment of cells produced a dose-dependent inhibition of E2-induced GFP expression, indicating the interaction of ER in the regulation of GFP gene expression. A series of estrogenic chemicals were evaluated for their capacity to induce GFP expression in MCF7-ERE cells, showing induced expression of GFP at concentrations 2-4 log units higher than the E2 concentration giving maximal GFP expression. The ERE-PGK-GFP reporter gene system is capable of rapid GFP expression in the presence of low concentrations of E2, and of quantifying estrogenicity of chemicals compared with a standard curve of the natural ligand, 17beta-estradiol.

Inverted duplication of the distal short arm of chromosome 3 associated with lobar holoprosencephaly and lumbosacral meningomyelocele

A fetus with lobar holoprosencephaly and lumbosacral meningomyelocele associated with duplication of the short arm of chromosome 3 is reported. The anomalies were detected on fetal ultrasound at 20 weeks' gestation and the autopsy findings correlated well with the prenatal findings. The fetal karyotype was 46,XY,der(3)del(3)(p26) dup(3)(p26p21.3). The association of holoprosencephaly with duplication 3p is well known, but to the best of our knowledge this is the first reported association of meningomyelocele with 3p duplication. These findings suggest that a gene or genes with a crucial role in central nervous system development are located on the short arm of chromosome 3.

Interaction of Pex5p, the type 1 peroxisome targeting signal receptor, with the peroxisomal membrane proteins Pex14p and Pex13p

Pex5p, a receptor for peroxisomal matrix proteins with a type 1 peroxisome targeting signal (PTS1), has been proposed to cycle from the cytoplasm to the peroxisomal membrane where it docks with Pex14p and Pex13p, the latter an SH3 domain-containing protein. Using in vitro binding assays we have demonstrated that binding of Pex5p to Pex14p is enhanced when Pex5p is loaded with a PTS1-containing peptide. In contrast, Pex5p binding to Pex13p, which involves only the SH3 domain, occurs at 20-40-fold lower levels and is reduced when Pex5p is preloaded with a PTS1 peptide. Pex14p was also shown to bind weakly to the Pex13p SH3 domain. Site-directed mutagenesis of the Pex13p SH3 domain attenuated binding to Pex5p and Pex14p, consistent with both of these proteins being binding partners for this domain. The SH3 binding site in Pex5p was determined to lie within a 114-residue peptide (Trp(100)-Glu(213)) in the amino-terminal region of the protein. The interaction between this peptide and the SH3 domain was competitively inhibited by Pex14p. We interpret these data as suggesting that docking of the Pex5p-PTS1 protein complex at the peroxisome membrane occurs at Pex14p and that the Pex13p SH3 domain functions as an associated component possibly involved in sequestering Pex5p after relinquishment of the PTS1 protein cargo to components of the translocation machinery.

Association between parental perception of children's vulnerability to illness and management of children's asthma

This study examined the relationship between asthma management strategies used by parents and parental perception of children's vulnerability to illness. Home interviews were conducted with 101 parents of children previously hospitalized with asthma. The child vulnerability scale (CVS) was employed to assess parents' perception of their children's vulnerability to illness. The asthma severity index (ASI) was used to measure the frequency and intensity of asthma symptoms experienced by children in the preceding 12 months. Five markers of parental asthma management were assessed: (i) school absences; (ii) visits to the general practitioner (GP); (iii) visits to the emergency room (ER); (iv) hospitalizations; and (v) whether children are using a regular preventer. After controlling for the frequency and intensity of children's asthma symptoms, parents who perceived that their children were more vulnerable to medical illness were significantly more likely to keep their children home from school (P = 0.01), were more likely to take their children to the GP for acute asthma care (P = 0.02), and were more likely to be giving their children regular preventer medication (P = 0.02). In contrast, the use of tertiary pediatric care services was not significantly associated with parental perceptions of their children's vulnerability. The results suggest that parental attitudes and beliefs about the vulnerability of their children to illness were associated with greater use of GP services by parents and more frequent school absences for children. The use of hospital services by parents appeared to be more strongly associated with the actual level of children's asthma symptoms than their vulnerability to illness.

Comparison of serum and urine assays for biochemical markers of bone resorption in postmenopausal women with and without hormone replacement therapy and in men

Biochemical markers of bone resorption have been used to characterize metabolic bone disease and assess therapeutic response. Most studies have used the urinary measurement of collagen crosslinks, but serum assays have recently been developed that may have less analytic and biologic variability. In the present study, we measured urine and serum N- and C-terminal crosslinked telopeptides of type I collagen (NTX and CTX) and serum bone sialoprotein (BSP) in postmenopausal women with or without hormone replacement therapy (HRT) and in men of similar age. In these populations, the variability of serum and urine markers was similar, except that serum NTX showed somewhat lower variability in postmenopausal women. Urine and serum assays correlated well with one another and were significantly lower in postmenopausal women on HRT compared with untreated women. The difference in women on HRT was similar for sNTX, uNTX and BSP (35-40%) and greater for sCTX and uCTX (52-53%). There was an inverse correlation between markers and bone mineral density, largely attributable to the high correlation in women not on HRT. Fractional excretion of NTX and CTX were estimated at 0.20+/-0.07 and 0.44+/-0.11, respectively. These values were independent of the concentration of the marker or of creatinine in the urine. We conclude that serum markers are useful measures of bone resorption in these populations, in whom the use of such markers is likely to be helpful in the management of osteoporosis.

Thalamic and amygdala-hippocampal volume reductions in first-degree relatives of patients with schizophrenia: an MRI-based morphometric analysis

BACKGROUND

Schizophrenia is characterized by subcortical and cortical brain abnormalities. Evidence indicates that some nonpsychotic relatives of schizophrenic patients manifest biobehavioral abnormalities, including brain abnormalities. The goal of this study was to determine whether amygdala-hippocampal and thalamic abnormalities are present in relatives of schizophrenic patients.

METHODS

Subjects were 28 nonpsychotic, and nonschizotypal, first-degree adult relatives of schizophrenics and 26 normal control subjects. Sixty contiguous 3 mm coronal, T1-weighted 3D magnetic resonance images of the brain were acquired on a 1.5 Tesla magnet. Cortical and subcortical gray and white matter and cerebrospinal fluid (CSF) were segmented using a semi-automated intensity contour mapping algorithm. Analyses of covariance of the volumes of brain regions, controlling for expected intellectual (i.e., reading) ability and diagnosis, were used to compare groups.

RESULTS

The main findings were that relatives had significant volume reductions bilaterally in the amygdala-hippocampal region and thalamus compared to control subjects. Marginal differences were noted in the pallidum, putamen, cerebellum, and third and fourth ventricles.

CONCLUSIONS

Results support the hypothesis that core components of the vulnerability to schizophrenia include structural abnormalities in the thalamus and amygdala-hippocampus. These findings require further work to determine if the abnormalities are an expression of the genetic liability to schizophrenia.

Safe use of valproic acid during pregnancy

QUESTION

I have an epileptic patient who plans pregnancy. It took us years to control her seizures, and valproic acid seems to be the only way to control them. What is the risk to her fetus?

ANSWER

Neural tube defects (NTDs) are the most common of the major anomalies associated with in utero exposure to valproic acid. About 1% to 2% of exposed fetuses suffer adverse effects.

Retinoic acid-dependent upregulation of mouse folate receptor-alpha expression in embryonic stem cells, and conservation of alternative splicing patterns

The action of retinoic acid (RA) in normal development and differentiation is mediated by changes in the expression of RA-responsive target genes. We used differential display reverse transcriptase polymerase chain reaction (RT-PCR) to identify RA-responsive genes expressed in embryonic stem (ES) cells and found that murine folate receptor-alpha (FR-alpha) expression is rapidly induced by RA treatment. The observed increase in FR-alpha expression occurs within 3h, is independent of protein synthesis and does not occur when ES cells are differentiated by removal of leukaemia inhibitory factor (LIF), evidence that the response to RA is both direct and specific. Two messenger RNA (mRNA) isoforms of FR-alpha featuring novel sequence in the 5' untranslated region (UTR) were cloned, and both were found to be upregulated by RA. Other splice variants in both the 5' UTR and 3' UTR of FR-alpha mRNA were also identified. There is a striking similarity between these splicing patterns and those reported for human FR-alpha, which also generates multiple isoforms by alternative splicing in the 5' and 3' UTR. The conservation of these splicing patterns in the non-coding regions of the FR-alpha gene between mouse and human suggests that these regions, and in particular the 5' UTR, play an important role in regulating expression of this gene.

Non-ionic bulky Gd(III) DTPA-bisamide complexes as potential contrast agents for magnetic resonance imaging

A series of new diethylene triamine pentaacetic acid (DTPA)-bisamide chelates containing bulky alkyl and aryl side chains have been prepared and characterized. Nuclear magnetic relaxation dispersion profiles were measured for the neutral gadolinium [Gd(III)] DTPA-bisamide complexes in water solution, and their chemical exchange times (tau(m)) were found to be in the range of 1.4 to 4.9 micros. Significant enhancements of solvent proton relaxation rates were observed between 10 and 50 MHz for one of the complexes of the series [Gd(III)-DTPA-bis-2-ethylhexylamide] in human serum albumin (HSA) solution, indicating the formation of a paramagnetic macromolecular adduct. The binding association constant K(A) of the complex and the albumin 5.7 x 10(3) M(-1) was obtained, and the relaxivity of the fully bound adduct was determined to be 13.8 mM(-1) s(-1) at 20 MHz and 25 degrees C. The high value of K(A) makes the above derivative a good potential blood pool contrast agent at the physiological HSA concentration.

Pregnancy outcome following gestational exposure to organic solvents: a prospective controlled study

CONTEXT

Numerous women of childbearing age are exposed occupationally to organic solvents. Previous retrospective studies have reported conflicting results regarding teratogenic risk.

OBJECTIVE

To evaluate pregnancy and fetal outcome following maternal occupational exposure to organic solvents.

DESIGN

A prospective, observational, controlled study.

SETTING

An antenatal counseling service in Toronto, Ontario.

PATIENTS

One hundred twenty-five pregnant-women who were exposed occupationally to organic solvents and seen during the first trimester between 1987 and 1996. Each pregnant woman who was exposed to organic solvents was matched to a pregnant woman who was exposed to a nonteratogenic agent on age (+/-4 years), gravidity (+/-1), and smoking and drinking status.

MAIN OUTCOME MEASURE

Occurrence of major congenital malformations.

RESULTS

Significantly more major malformations occurred among fetuses of women exposed to organic solvents than controls (13 vs 1; relative risk, 13.0; 95% confidence interval, 1.8-99.5). Twelve malformations occurred among the 75 women who had symptoms temporally associated with their exposure, while none occurred among 43 asymptomatic exposed women (P<.001). (One malformation occurred in a woman for whom such information was missing.) More of these exposed women had previous miscarriage while working with organic solvents than controls (54/117 [46.2%] vs 24/125 [19.2%]; P<.001). However, exposed women who had a previous miscarriage had rates of major malformation that were similar to exposed women who had no previous miscarriage.

CONCLUSIONS

Occupational exposure to organic solvents during pregnancy is associated with an increased risk of major fetal malformations. This risk appears to be increased among women who report symptoms associated with organic solvent exposure. Women's exposure to organic solvents should be minimized during pregnancy. Symptomatic exposure appears to predict higher fetal risk for malformations.

Perception of first- and second-order motion: separable neurological mechanisms?

An unresolved issue in visual motion perception is how distinct are the processes underlying "first-order" and "second-order" motion. The former is defined by spatiotemporal variations of luminance and the latter by spatiotemporal variations in other image attributes, such as contrast or depth. Here we describe two neurological patients with focal unilateral lesions whose contrasting perceptual deficits on psychophysical tasks of "first-order" and "second-order" motion are related to the maps of the human brain established by functional neuroimaging and gross anatomical features. We used a relatively fine-grained neocortical parcellation method applied to high-resolution MRI scans of the patients' brains to illustrate a subtle, yet highly specific dissociation in the visual motion system in humans. Our results suggest that the two motion systems are mediated by regionally separate mechanisms from an early stage of cortical processing.

Identification of a mouse orthologue of the human ras-GAP-SH3-domain binding protein and structural confirmation that these proteins contain an RNA recognition motif

Human ras-GTPase-activating protein (GAP120) SH3-domain-binding protein (G3BP) has recently been identified on the basis of its specific binding to the GAP120 SH3 binding domain. Here we report the identification of a mouse G3BP cDNA and the confirmation by three dimensional modelling of an RNA recognition motif (RRM) in the encoded protein. Mouse G3BP also contains an RGG domain, an acid-rich amino acid domain, and several SH3 domain-binding consensus sequences, indicating that mammalian G3BPs represent a new family of signal transduction proteins which connect tyrosine kinase-linked receptors to cellular RNA metabolism.