White matter impairment in Rett syndrome: diffusion tensor imaging study with clinical correlations

BACKGROUND AND PURPOSE

RTT, caused by mutations in the methyl CPG binding protein 2 (MeCP2) gene, is a disorder of neuronal maturation and connections. Our aim was to prospectively examine FA by DTI and correlate this with certain clinical features in patients with RTT.

MATERIALS AND METHODS

Thirty-two patients with RTT underwent neurologic assessments and DTI. Thirty-seven age-matched healthy female control subjects were studied for comparison. With use of a 1.5T MR imaging unit, DTI data were acquired, and FA was evaluated to investigate multiple regional tract-specific abnormalities in patients with RTT.

RESULTS

In RTT, significant reductions in FA were noted in the genu and splenium of the corpus callosum and external capsule, with regions of significant reductions in the cingulate, internal capsule, posterior thalamic radiation, and frontal white matter. In contrast, FA of visual pathways was similar to control subjects. FA in the superior longitudinal fasciculus, which is associated with speech, was equal to control subjects in patients with preserved speech (phrases and sentences) (P = .542), whereas FA was reduced in those patients who were nonverbal or speaking only single words (P < .001). No correlations between FA values for tracts and clinical features such as seizures, gross or fine motor skills, and head circumference were identified.

CONCLUSIONS

DTI, a noninvasive technique to assess white matter tract pathologic features, may add specificity to the assessment of RTT clinical severity that is presently based on the classification of MeCP2 gene mutation and X-inactivation.

Serum IgA antibodies from patients with coeliac disease react strongly with human brain blood-vessel structures

BACKGROUND

Our objective was to determine the possible presence of IgA antibodies directed against human central nervous system (CNS) structures in sera from coeliac disease (CD) patients.

METHODS

Serum samples were collected from 4 patients with active CD on a gluten-containing diet, 11 biopsy-proven CD patients on a gluten-free diet (GFD), and 52 non-coeliac gastrointestinal controls. In all patients IgA antigliadin antibody (AGA) titres were determined with enzyme-linked immunoassay (ELISA), and IgA antiendomysium antibodies (EMA) with indirect immunofluorescence on human umbilical cord. Cryostat sections of human brain occipital cortex were incubated with the patients' sera and subsequently labelled with anti-human IgA fluorescein conjugate.

RESULTS

All sera from patients with active CD on a gluten-containing diet yielded positive results in both the IgG-AGA and EMA test and in indirect immunofluorescence on brain tissue, disclosing a strong fluorescence over blood-vessels structures. All sera from CD patients on a GFD and from non-coeliac gastrointestinal controls gave a negative result on both the EMA test and the immunofluorescence reaction on human brain.

CONCLUSIONS

Sera from patients with active CD contain IgA antibodies that react with human brain vessel structures, giving intense fluorescence. These antibodies are not present in sera from coeliac patients on a GFD or non-coeliac controls. This finding might be involved in the abnormal nervous system manifestations frequently described in association with coeliac disease.

Characterization of glycoinositolphosphoryl ceramide structure mutant strains of Cryptococcus neoformans

In fungi, glycoinositolphosphoryl ceramide (GIPC) biosynthetic pathway produces essential molecules for growth, viability, and virulence. In previous studies, we demonstrated that the opportunistic fungus Cryptococcus neoformans synthesizes a complex family of xylose-(Xyl) branched GIPCs, all of which have not been previously reported in fungi. As an effort to understand the biosynthesis of these sphingolipids, we have now characterized the structures of GIPCs from C. neoformans wild-type (KN99alpha) and mutant strains that lack UDP-Xyl, by disruption of either UDP-glucose dehydrogenase (NE321) or UDP-glucuronic acid decarboxylase (NE178). The structures of GIPCs were determined by a combination of nuclear magnetic resonance (NMR) spectroscopy, tandem mass spectrometry (MS), and gas chromatography-MS. The main and largest GIPC from wild-type strain was identified as an alpha-Manp(1 --> 6)alpha-Manp(1 --> 3)alpha-Manp[beta-Xylp(1 --> 2)]alpha-Manp(1 --> 4)beta-Galp(1 --> 6)alpha-Manp(1 --> 2) Ins-1-P-Ceramide, whereas the most abundant GIPC from both mutant strains was found to be an alpha-Manp(1 --> 3)alpha-Manp(1 --> 4)beta-Galp(1 --> 6)alpha-Manp(1 --> 2)Ins-1-P-Ceramide. The ceramide moieties of C. neoformans wild-type and mutant strains were composed of a C(18) phytosphingosine, which was N-acylated with 2-hydroxy tetra-, or hexacosanoic acid, and 2,3-dihydroxy-tetracosanoic acid. Our structural analysis results indicate that the C. neoformans mutant strains are unable to complete the assembly of the GIPC-oligosaccharide moiety due the absence of Xyl side chain.

Reference values for Doppler ultrasound parameters of the thyroid in a healthy iodine-non-deficient population

The aim of this study was to describe normal Doppler parameter values in the thyroid arteries in an iodine-replete region. 165 individuals were randomly selected in a community located in the south-east of Brazil. We obtained a clinical history on each subject and determined serum thyrotropin, antiperoxidase antibodies, thyrotropin receptor antibody (TRAb) and thyroid volumes through ultrasound. Subjects with thyroid disease and those under 20 years of age were excluded. 84 representative subjects (30 men and 54 women) remained. The systolic peak velocity (SPV), resistive index (RI) and pulsatility index (PI) in the superior and inferior thyroid arteries were measured using a 5-12 MHz linear probe. Except for the RI, the distribution of all Doppler parameters was non-gaussian. The median and mean references for the SPV, RI and PI were 24.80 cm s(-1) and 25.85 cm s(-1), 0.60 and 0.62, and 0.98 and 1.04, respectively, for superior thyroid arteries; these reference values for the inferior thyroid artery were 20.92 cm s(-1) and 21.50 cm s(-1), 0.57 and 0.57, and 0.84 and 0.88, respectively (p<0.001). Women had greater SPV values (p<0.01). We have determined reference thyroid Doppler parameter values in our iodine-non-deficient population and prepared tables by sex and age.

Differentiation between the two types of amiodarone-associated thyrotoxicosis using duplex and amplitude Doppler sonography

PURPOSE

To evaluate the usefulness of Doppler parameters in the differentiation between the two types of amiodarone-associated thyrotoxicosis (AAT).

MATERIAL AND METHODS

One hundred thirty-seven individuals were selected at our institution. They were divided into four groups: 84 normal subjects (N), 30 euthyroids taking amiodarone (A), 14 AAT type 1 patients (AAT1), and nine AAT type 2 patients (AAT2). Each AAT type was classified according to (131)I uptake and clinical outcome. Blindly, the resistance and pulsatility indexes (RI, PI), systolic peak velocity, and color pixel density (CPD) were calculated.

RESULTS

AAT1 had greater CPD than AAT2 (P = 0.02). The latter group had similar vascularization to the N and A groups (P = 0.45). The area under the receiver operating characteristic (ROC) curve showed that systolic peak velocity in the inferior thyroid arteries and CPD were the best parameters in the differentiation between AAT type 1 and AAT type 2 (Az = 0.83 and 0.84, respectively). Impedance indexes were useless.

CONCLUSION

Our results demonstrate that objective tests such as systolic peak velocities in the thyroid arteries and CPD are reliable parameters for differentiating between the two types of AAT.

The P450 oxidoreductase, RedA, controls development beyond the mound stage in Dictyostelium discoideum

BACKGROUND

NADPH-cytochrome-P450 oxidoreductase (CPR) is a ubiquitous enzyme that belongs to a family of diflavin oxidoreductases and is required for activity of the microsomal cytochrome-P450 monooxygenase system. CPR gene-disruption experiments have demonstrated that absence of this enzyme causes developmental defects both in mouse and insect.

RESULTS

Annotation of the sequenced genome of D. discoideum revealed the presence of three genes (redA, redB and redC) that encode putative members of the diflavin oxidoreductase protein family. redA transcripts are present during growth and early development but then decline, reaching undetectable levels after the mound stage. redB transcripts are present in the same levels during growth and development while redC expression was detected only in vegetative growing cells. We isolated a mutant strain of Dictyostelium discoideum following restriction enzyme-mediated integration (REMI) mutagenesis in which redA was disrupted. This mutant develops only to the mound stage and accumulates a bright yellow pigment. The mound-arrest phenotype is cell-autonomous suggesting that the defect occurs within the cells rather than in intercellular signaling.

CONCLUSION

The developmental arrest due to disruption of redA implicates CPR in the metabolism of compounds that control cell differentiation.