Myelination as assessed by conventional MR imaging is normal in young children with idiopathic developmental delay

BACKGROUND AND PURPOSE: A common isolated reported finding in brain imaging studies on developmentally delayed children is delayed myelination. We hypothesized that brain MR imaging scans of these children would show delayed subcortical myelination of white matter with specific involvement of the subcortical U-fibers as these represent terminal zones of myelination and are the last areas to myelinate. MATERIALS AND METHODS: A total of 93 children (31 controls, 62 with idiopathic developmental delay [IDD]) aged 17 to 46 months were identified on the basis of having brain MR imaging for evaluation of IDD (cases) or for another condition (controls). Children with diseases that primarily affect white matter or overt intracranial lesions or malformations were excluded. IDD was defined as psychomotor retardation without a clear cause on the basis of history, physical, genetic, metabolic, and neuroimaging examinations. Developmental quotients (DQs) were calculated for all children with IDD on the basis of clinical history, examination, and psychometric testing. Three board-certified pediatric neuroradiologists examined axial T2-weighted brain images and used a published scoring system to rate the extent of myelination in the frontal, temporal, parietal, and peritrigonal brain regions. In addition, subcortical U-fibers in the frontal, temporal, and parietal lobes were scored separately. Data were analyzed at both the intraobserver and interobserver levels, and scores were compared between groups and tested for interactions with age and DQ. RESULTS: There were no differences in the timing or extent of myelination in the control and IDD groups at any age in any brain region. In the IDD group, there was no relationship between myelination scores and DQ or developmental domain. CONCLUSIONS: Our findings did not support the hypothesis that there is a correlation between IDD and the maturity of myelination, including the terminal zones, as seen on conventional brain MR imaging. Neuroimaging evaluation of maturity of subcortical myelination is not a marker of IDD in young children, and the isolated "finding" of delayed myelination should be interpreted with caution.     

MR lymphography of abdominal and retroperitoneal lymphatic vessels

OBJECTIVE: The abdominal and retroperitoneal lymphatic system is characterized by numerous anatomic variations. Our objective is to review MR lymphographic features of normal anatomy and abnormal conditions. CONCLUSION: MR lymphography is a noninvasive technique that is well suited for the examination of abdominal and retroperitoneal lymphatic vessels.     

High prevalence of chronic kidney disease in Iran: a large population-based study

Background  

Chronic kidney disease (CKD) is a global public health threat, associated with an alarming increase in morbidity and mortality. The importance is the worldwide increase in its incidence and prevalence.     

Serum nitric oxide metabolites in subjects with metabolic syndrome

ObjectivesEvidence are available showing that higher nitric oxide production is associated with metabolic disorders. The aim of this study was to determine serum nitric oxide metabolites (NO_x) concentration in subjects with metabolic syndrome (MetS).Design and methodsIn a cross-sectional study, NO_x was measured in 3505 subjects, aged 20–94 years, using the Griess reaction. After excluding subjects taking medications for hypertension and dyslipidemia, data for 3148 subjects were analyzed.ResultsThere was a direct association between the numbers of metabolic risk factors and serum NO_x values in both genders (p for trend < 0.05). After multivariable adjustment, serum NO_x concentration was significantly higher in subjects with MetS [(31.9 (29.4–34.6) vs. 29.8 (27.6–32.1), p < 0.01) or type 2 diabetes (34.6 (31.3–38.2) vs. 30.2 (27.9–32.6), p < 0.001) as compared to their corresponding controls.ConclusionsHigher NO_x concentrations in subjects with MetS and type 2 diabetes support the existing hypothesis that NO overproduction affects insulin's metabolic actions.     

Reference values for serum nitric oxide metabolites in an adult population

ObjectivesTo determine reference values for serum nitric oxide metabolites (nitrite + nitrate = NO_x) concentrations in adult subjects.Design and methodsSerum NO_x concentration was measured, using the Griess method, in 694 non-smoking apparently healthy subjects, randomly selected from a population-based study. The International Federation of Clinical Chemistry guidelines and the robust method were used for determining reference values.ResultsThe 95% reference values for serum NO_x concentration and serum NO_x/creatinine ratio were 11.5 to 76.4 μmol/L and 0.111 to 0.729 in men and 10.1 to 65.6 μmol/L and 0.121 to 0.777 in women, respectively. With increasing body mass index, upper limits of serum NO_x and the NO_x/creatinine ratio increased in women and decreased in men. Serum NO_x levels above upper limits predicted both diabetes and metabolic syndrome in women.ConclusionsThis study reports the first set of reference values for serum NO_x concentration and NO_x/creatinine ratio in a relatively large healthy non-smoking population.     

The pontocerebellar system in the rat: An HRP study. II. Hemispheral components

The projection of basilar pontine neurons to the cerebellar hemispheres was studied in pigmented rats by means of the retrograde transport of horseradish peroxidase. Injections of horseradish peroxidase were restricted to the lateral aspects of the lobulus simplex (11 cases), crus I (26 cases), crus II (23 cases), and paramedian lobule (18 cases). The main focus of labeled neurons following lobulus simplex injections of horseradish peroxidase was located in the ventral pons, at rostral levels. Interestingly, the majority of labeled cells were distributed ipsilateral to the injection site. After crus I injections, however, labeled neurons were most evident contralaterally, although labeled ipsilteral cells were conspicuous rostrally. The majority of labeled cells were characteristically distributed along the medial, ventral, and lateral perimeters of the pontine gray. This pattern of labeling contrasts with that in cases of crus II injections, in which the main focus of labeled somata occupied more central regions of medial and ventral portions of the pons. Similarly, the pattern of labeling following injections into the paramedian lobule largely avoided the medial and lateral perimeters of the pontine gray, while numerous labeled somata occupied the central region of the pons. In addition to the pontine regions described above, labeled cells were observed in various cases in the dorsal peduncular region, the lateral and dorsolateral areas, and the nuclear reticularis tegmenti pontis (NRTP) where three separate zones of labeling could be discerned in various cases. Several general organizational features were derived from these studies. Although specific quantitation procedures were not applied, the number of ipsilaterally labeled neurons was impressive in some cases, as was the mirror-image location of certain ipsi- and contra-lateral cell clusters. It was also noted that certain, similarly located clusters of labeled pontine neurons were present in cases in which injections were made into different cerebellar lobules, at least raising the possibility that some pontine neurons might give rise to divergent projections to multiple cerebellar locations. Moreover, it was evident that the location of certain clusters of labeled neurons was congruent with terminal zones of various pontine afferent systems, particularly those of the sensorimotor cortex. Combining the latter finding with the preceeding notion regarding pontocerebellar divergence suggests a mechanism by which sensorimotor information might be transmitted to several different cerebellar locations.