Molecular findings in symptomatic and pre-symptomatic Alexander disease patients

BACKGROUND AND OBJECTIVE

Alexander disease is a slowly progressive CNS disorder that most commonly occurs in children. Until recently, the diagnosis could only be established by the histologic finding of Rosenthal fibers in brain specimens. Mutations in the glial fibrillary acidic protein (GFAP) gene have now been shown in a number of biopsy- or autopsy-proven patients with Alexander disease. A prospective study on patients suspected to have Alexander disease was conducted to determine the extent to which clinical and MRI criteria could accurately diagnose affected individuals, using GFAP gene sequencing as the confirmatory assay.

METHODS

Patients who showed MRI white matter abnormalities consistent with Alexander disease, unremarkable family history, normal karyotype, and normal metabolic screening were included in this study. Genomic DNA from patients was screened for mutations in the entire coding region, including the exon-intron boundaries, of the GFAP gene.

RESULTS

Twelve of 13 patients (approximately 90%) were found to have mutations in GFAP. Seven of those 12 patients presented in infancy with seizures and megalencephaly. Five were juvenile-onset patients with more variable symptoms. Two patients in the latter group were asymptomatic or minimally affected at the time of their initial MRI scan. The mutations were distributed throughout the gene, and all involved sporadic single amino acid heterozygous changes that changed the charge of the mutant protein. Four of the nine changes were novel mutations.

CONCLUSIONS

In symptomatic and asymptomatic patients with a predominantly frontal leukoencephalopathy by MRI, GFAP gene mutation analysis should be included in the initial diagnostic evaluation process for Alexander disease.

Subunits of the translation initiation factor eIF2B are mutant in leukoencephalopathy with vanishing white matter

Leukoencephalopathy with vanishing white matter (VWM) is an inherited brain disease that occurs mainly in children. The course is chronic-progressive with additional episodes of rapid deterioration following febrile infection or minor head trauma. We have identified mutations in EIF2B5 and EIF2B2, encoding the epsilon- and beta-subunits of the translation initiation factor eIF2B and located on chromosomes 3q27 and 14q24, respectively, as causing VWM. We found 16 different mutations in EIF2B5 in 29 patients from 23 families. We also found two distantly related individuals who were homozygous with respect to a missense mutation in EIF2B2, affecting a conserved amino acid. Three other patients also had mutations in EIF2B2. As eIF2B has an essential role in the regulation of translation under different conditions, including stress, this may explain the rapid deterioration of people with VWM under stress. Mutant translation initiation factors have not previously been implicated in disease.

Neuroimaging studies in Rett syndrome

Neuroimaging is a key instrument for determining structural and in vivo functional status of the brain, non-invasively. Multiple approaches can now determine aspects of anatomic and neurochemical changes in brain, and have been utilized effectively in Rett Syndrome patients to understand the biological basis of this neurodevelopmental disorder. Studies performed at our institute include volumetric analyses of MRI, magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI), cerebral blood flow measurements with MRI, and positron emission tomography scans (PET). These studies have provided considerable insight into mechanisms underlying the clinical features of this disease. Volumetric analyses suggest that decreased brain volume in RS results from global reductions in both gray and white matter of the brain. A selective vulnerability of the frontal lobes is evidenced by the preferential reduction of blood flow, increased choline and reduced n-acetyl aspartate (NAA) by MRS, and increased glucose uptake in these same regions as shown by ((18)F)-fluorodeoxyglucose (FDG) PET scans. We hypothesize that the increased glucose uptake relates to increased glutamate cycling in synapses. The resulting neuroexcitotoxic injury to the developing brain contributes to the seizures, behavioral disturbance and respiratory irregularities commonly seen in phases 1 and 2 of this disorder.

Neurobiology of Rett syndrome: a genetic disorder of synapse development

Rett syndrome is a developmental disorder that restricts brain growth beginning in the first year of life and evidence from neuropathology and neuroimaging indicates that axonodendritic connections are especially vulnerable. In a study of amino acid neurotransmitter receptors using receptor autoradiography in tissue slices of frontal cortex and the basal ganglia, we found a biphasic age-related pattern with relatively high receptor densities in young RS girls and lower densities at later time. Using microarray analysis of gene expression in frontal cortex, we found that some of the most prominent alterations occurred in gene products related to synapses, including the NMDA receptor NR1 subunit, the cytoskeletal protein MAP-2 and synaptic vesicle proteins. Using a new antibody that recognizes MeCP2, the transcription factor mutated in RS, we established that most neurons in the rodent brain express this transcription factor. We hypothesize that a major effect of mutations in the MeCP2 protein is to cause age-related disruption of synaptic proliferation and pruning in the first decade of life.

Gene expression profiling in postmortem Rett Syndrome brain: differential gene expression and patient classification

The identification of mutations in the transcriptional repressor methyl-CpG-binding protein 2 (MECP2) gene in Rett Syndrome (RTT) suggests that an inappropriate release of transcriptional silencing may give rise to RTT neuropathology. Despite this progress, the molecular basis of RTT neuropathogenesis remains unclear. Using multiple cDNA microarray technologies, subtractive hybridization, and conventional biochemistry, we generated comprehensive gene expression profiles of postmortem brain tissue from RTT patients and matched controls. Many glial transcripts involved in known neuropathological mechanisms were found to have increased expression in RTT brain, while decreases were observed in the expression of multiple neuron-specific mRNAs. Dramatic and consistent decreases in transcripts encoding presynaptic markers indicated a specific deficit in presynaptic development. Employing multiple clustering algorithms, it was possible to accurately segregate RTT from control brain tissue samples based solely on gene expression profile. Although previously achieved in cancers, our results constitute the first report of human disease classification using gene expression profiling in a complex tissue source such as brain.

Effects of housing density on mouse physiology and behavior in the NASA Animal Enclosure Module simulators

Space flight studies using the Animal Enclosure Module (AEM) make it possible to investigate the role of microgravity on animal physiology and behavior. In this study, we compared the health and well-being of mice housed at different densities in AEM simulators (AEMS), to vivarium shoebox (control) cages (VSBC). A stress assessment battery (SAB) of measures was developed to evaluate mouse health and well-being, and to determine if any of the population sizes resulted in a stressful environment. The SAB was based, in part, on recommendations of a NASA Workshop on Rodent Cage Sizing. It includes: 1) General assessment of appearance, 2) Behavioral assessment (video), 3) Food and water consumption, 4) Body weight changes, 5) Thymus, adrenal, spleen, heart and kidney weights, 6) Plasma corticosterone concentration, 7) Total plasma protein concentration, 8) Total blood leukocyte count, 9) Differential leukocyte count: neutrophil/lymphocyte ratio; eosinophil count, 10) Gastric histology.

Clinico-pathological study of causes of perinatal mortality in a developing country

Perinatal mortality rates are an important indicator of the overall obstetric and neonatal services available, and the socio-economic status of the community. These rates are also used to identify shortcomings in services provided. The aim of this study was to identify clinical causative factors of perinatal deaths (supported by post mortem evidence where possible). This was a prospective descriptive study. The total number of deliveries and perinatal deaths over a 6-month period were recorded and clinico-demographic data noted. Post mortem examination information, if available, was also recorded. There was a total of 7789 deliveries over the 6-month period and 460 perinatal deaths, giving a perinatal mortality rate of 59/1000 deliveries; 45% (n = 207) of the perinatal deaths had post mortem examinations. The mean age was 26 years; 84.8% were single mothers. One-third of the group were un-booked: the mean gestational age of fetal death was 31 weeks, and the mean birth weight was 1700 g. Two-thirds of the perinatal deaths were stillbirths. The leading obstetric causes of deaths were: abruptio placentae (25.3%), hypertension in pregnancy (24.9%), prematurity (17.4%), unexplained stillbirth (13.4%) and intrapartum asphyxia (9.2%). The perinatal mortality rate of 59/1000 deliveries is high. Although this is comparable with other developing countries, there is a need for improvement in organisation of obstetric and neonatal care, staffing levels and access to and effective utilisation of antenatal services. These will probably lead to a significant reduction of this relatively high perinatal mortality rate.

Guidelines for reporting clinical features in cases with MECP2 mutations

An international group recommends that papers relating phenotypes to genotypes involving mutations in the X chromosome gene MECP2 should provide a minimum data set reporting the range of disturbances frequently encountered in Rett Syndrome. A simple scoring system is suggested which will facilitate comparison among the various clinical profiles. Features are described which should prompt screening for MECP2 mutations.

MeCP2 mutations in children with and without the phenotype of Rett syndrome

BACKGROUND

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the X-linked methyl CpG binding protein 2 (MeCP2) gene.

METHODS

One hundred sixteen patients with classical and atypical RTT were studied for mutations of the MeCP2 gene by using DHPLC and direct sequencing.

RESULTS

Causative mutations in the MeCP2 gene were identified in 63% of patients, representing a total of 30 different mutations. Mutations were identified in 72% of patients with classical RTT and one third of atypical cases studied (8 of 25). The authors found 17 novel mutations, including a complex gene rearrangement found in one individual involving two deletions and a duplication. The duplication was identical to a region within the 3' untranslated region (UTR), and represents the first report of involvement of the 3' UTR in RTT. The authors also report the identification of MeCP2 mutations in two males; a Klinefelter's male with classic RTT (T158M) and a hemizygous male infant with a Xq27-28 inversion and a novel 32 bp frameshift deletion [1154(del32)]. Studies examining the relationship between mutation type, X-inactivation status, and severity of clinical presentation found significant differences in clinical presentation between different types of mutations. Mutations in the amino-terminus were significantly correlated with a more severe clinical presentation compared with mutations closer to the carboxyl-terminus of MeCP2. Skewed X-inactivation patterns were found in two asymptomatic carriers of MeCP2 mutations and six girls diagnosed with either atypical or classical RTT.

CONCLUSION

This patient series confirms the high frequency of MeCP2gene mutations causative of RTT in females and provides data concerning the molecular basis for clinical variability (mutation type and position and X-inactivation patterns).

Alexander disease: diagnosis with MR imaging

BACKGROUND AND PURPOSE

To date, the demonstration of Rosenthal fibers on brain biopsy or autopsy specimens is considered a prerequisite for a definitive diagnosis of Alexander disease. We initiated a multiinstitutional survey of MR abnormalities in both presumed and confirmed cases of Alexander disease to assess the possibility of an MR-based diagnosis.

METHODS

MR imaging studies in three patients with an autopsy-based diagnosis of Alexander disease were analyzed to define MR criteria for the diagnosis. These criteria were then applied to 217 children with leukoencephalopathy of unknown origin.

RESULTS

Five MR imaging criteria were defined: extensive cerebral white matter changes with frontal predominance, a periventricular rim with high signal on T1-weighted images and low signal on T2-weighted images, abnormalities of basal ganglia and thalami, brain stem abnormalities, and contrast enhancement of particular gray and white matter structures. Four of the five criteria had to be met for an MR imaging-based diagnosis. In a retrospective analysis of the MR studies of the 217 patients, 19 were found who fulfilled these criteria. No other essentially new MR abnormalities were found in these patients. In four of the 19 patients, subsequent histologic confirmation was obtained. The clinical symptomatology was the same in the patients with and without histologic confirmation and correlated well with the MR abnormalities. MR abnormalities were in close agreement with the known histopathologic findings of Alexander disease.

CONCLUSION

The defined criteria are sufficient for an in vivo MR imaging diagnosis of Alexander disease; only in atypical cases is a brain biopsy still necessary for a definitive diagnosis.

Pharmacodynamics of orally administered sustained- release hydromorphone in humans

BACKGROUND

The disposition kinetics of hydromorphone generally necessitates oral administration every 4 h of the conventional immediate-release tablet to provide sustained pain relief. This trial examined time course and magnitude of analgesia to experimental pain after administration of sustained-release hydromorphone as compared with that after immediate-release hydromorphone or placebo.

METHODS

Using a 4 x 4 Latin square double-blind design, 12 subjects were randomized to receive a single dose of 8, 16, and 32 mg sustained-release hydromorphone and placebo. The same subjects had received 8 mg immediate-release hydromorphone before this study. Using an electrical experimental pain paradigm, analgesic effects were assessed for up to 30 h after administration, and venous hydromorphone plasma concentrations were measured at corresponding times.

RESULTS

The hydromorphone plasma concentration peaked significantly later (12.0 h [12.0--18.0] vs. 0.8 h [0.8--1.0]; median and interquartile range) but was maintained significantly longer at greater than 50% of peak concentration (22.7 +/- 8.2 h vs. 1.1 +/- 0.7 h; mean +/- SD) after sustained-release than after immediate-release hydromorphone. Similarly, sustained-release hydromorphone produced analgesic effects that peaked significantly later (9.0 h [9.0--12.0] vs. 1.5 h [1.0--2.0]) but were maintained significantly longer at greater than 50% of peak analgesic effect (13.3 +/- 6.3 h vs. 3.6 +/- 1.7 h). A statistically significant linear relation between the hydromorphone plasma concentration and the analgesic effect on painful stimuli existed.

CONCLUSION

A single oral dose of a new sustained-release formulation of hydromorphone provided analgesia to experimental pain beyond 24 h of its administration.

Pharmacokinetics, pharmacodynamics, and relative pharmacokinetic/pharmacodynamic profiles of zaleplon and zolpidem

OBJECTIVE

This study compared the pharmacokinetics, pharmacodynamics, and pharmacokinetic/pharmacodynamic (PK/PD) profile of zaleplon, a new pyrazolopyrimidine hypnotic, with those of zolpidem and placebo.

METHODS

This was a double-blind, 5-period crossover study in which healthy volunteers with no history of sleeping disorder were randomized to 10- or 20-mg oral doses of zaleplon, 10- or 20-mg oral doses of zolpidem, or placebo. The pharmacokinetic characteristics of the active drugs were estimated using a noncompartmental method and NONMEM. Pharmacodynamic characteristics were determined using psychophysical tests, including measures of sedation, mood, mental and motor speed, and recent and remote recall. Results of these tests were used to compare the drugs' relative PK/PD profiles.

RESULTS

Ten healthy male and female volunteers, aged 23 to 31 years, took part in the study. The apparent elimination half-life of zaleplon (60.1+/-8.9 min) was significantly shorter than that of zolpidem (124.5+/-37.9 min) (P < 0.001). Zaleplon produced less sedation than zolpidem at the 2 doses studied (P < 0.001). The sedation scores of the zaleplon groups returned to baseline in less time than those of the zolpidem groups (4 vs 8 hours; P < 0.05). Zaleplon had no effect on recent or remote recall, whereas zolpidem had a significant effect on both measures (P < 0.05).

CONCLUSIONS

In this study in 10 young, healthy volunteers, zaleplon was eliminated more rapidly, produced no memory loss, and caused less sedation than zolpidem at the same doses.

MR imaging and proton MR spectroscopy in adult Krabbe disease

We present the MR imaging findings in four patients (two pairs of siblings from two unrelated families) with adult Krabbe disease. In the first family, clinical presentation mimicked familial spastic paraplegia. Their MR images showed selective, increased signal intensity on T2-weighted sequences along the corticospinal tracts, most prominently in the proband and barely detectable in her brother. Proton MR spectroscopy showed increased choline and myo-inositol in the affected white matter. In the second family, the clinical presentation differed in that the signs of pyramidal tract involvement were asymmetrical, with concomitant asymmetry on MR images in one. In adults, Krabbe disease may present on MR imaging with selective pyramidal fiber involvement.

Auditory brainstem response findings in Rett syndrome: stability over time

OBJECTIVE

To determine whether changes consistent with the presence of white matter neurodegenerative disease would be observed in the auditory brainstem response (ABR) in Rett syndrome in conjunction with age advancement.

STUDY DESIGN

Initial and follow-up ABR findings were analyzed in a sample of 27 female patients with Rett syndrome. The interval between ABR tests ranged from 1 to 9 years.

RESULTS

No significant group differences consistent with neurodegenerative disease were observed in the wave I-III, III-V, or I-V interpeak latency intervals between the initial and follow-up test sessions.

CONCLUSIONS

Rett syndrome is not a disorder characterized by progressive white matter degeneration affecting the integrity of the brainstem central auditory pathways.

Auditory brainstem responses in Rett syndrome: effects of hyperventilation, seizures, and tympanometric variables

This study examined the effects of tympanometric variables, stage of disease, hyperventilation, and seizures on the auditory brainstem response (ABR) in Rett syndrome (RS). Thirty-four female children with RS ranging in age from 2 years, 3 months to 15 years, 7 months participated in the study. ABRs and tympanograms were recorded from all of the subjects. When the ABR peaks were identifiable, interpeak latency intervals (IPLIs) for I-III, III-V, and I-V were computed for each waveform. The peaks (I, III, and V) and IPLIs were characterized as abnormal if either the peaks were absent or the latencies were greater than 2 SD from the normative data (obtained on female children). Analyses revealed significant prolongation of wave I latencies in Rett children with abnormal tympanograms. ABR wave III latencies were significantly affected by the presence of seizures and hyperventilation. The Pearson chi-square statistic revealed significant differences in the rate of wave III and V abnormalities due to the presence and degree of hyperventilation and the presence of seizures. Wave I abnormalities were also observed in the presence of normal middle ear function, suggesting the presence of sensorineural hearing impairment in some RS children. Clinical implications of these findings are discussed.

Quantitative 1H MR spectroscopic imaging in early Rett syndrome

OBJECTIVE

To determine cerebral regional concentrations of N-acetyl aspartate (NAA), total choline (Cho), and total creatine (Cr) in Rett syndrome (RS) using 1H magnetic resonance spectroscopic imaging (MRSI).

BACKGROUND

The biochemical defect underlying RS is unknown. Because in vivo MRSI can detect important cerebral metabolites, MRSI has a potential to reveal impairment of regional cerebral metabolism in RS noninvasively.

METHODS

High-resolution, multislice 1H MRSI was carried out in 17 girls with RS. The control group consisted of nine healthy children.

RESULTS

In patients with RS, average Cho concentration was 12% higher (p < 0.005) and average NAA concentration 11% lower (p < 0.0001) compared with the control group. Regional metabolic differences included significantly lower NAA concentration in the frontal gray and white matter, insula, and hippocampus in RS; no difference in regional Cho and Cr concentrations were found. A 20 to 38% higher Cho:NAA ratio in frontal and parietal gray and white matter, insular gray matter, and hippocampus (p < 0.05) and a 14 to 47% lower NAA:Cr ratio in frontal cortical gray matter, parietal and temporal white matter, insula, and putamen (p < 0.05) were found in subjects with RS compared with controls. Patients with seizures had higher average concentrations of Cho, Cr, and NAA compared with those without seizures (8-19%, p < 0.05).

CONCLUSION

Metabolic impairment in RS involves both gray and white matter and particularly involves frontal and parietal lobes and the insular cortex. Loss of NAA most likely reflects reduced neuronal and dendritic tree size; increased Cho concentration may result from gliosis.

Tibial and peroneal artery bypasses using polytetrafluoroethylene (PTFE) with an interposition vein cuff

The combined results of femoro-distal bypasses using prosthetic material with vein cuffs from two separate vascular units is presented.

METHOD

Over the last five years, 89 infrainguinal bypasses using polytetrafluoroethylene (PTFE) with a distal interposition vein cuff to a tibial artery have been performed in two centres. All operations were for critical limb ischaemia. The mean age was 72 years (47-90), there were 46 males and 43 females, 27 of whom were diabetic. Twenty-eight patients had a history of angina and/or previous myocardial infarct. The median follow-up was 12 months (0-68 months).

RESULTS

During the follow-up period there were 28 deaths, 35 major limb amputations and 44 graft failures. The graft patency rates at 12 and 24 months were 50 and 32%, and limb salvage rates were 53 and 44%, respectively. The patient survival rates were 66 and 61%, respectively.

CONCLUSION

The authors believe that the likely improvement in pain free quality of life the patient may enjoy with a successful bypass shifts the balance in some individuals towards bypass surgery using PTFE with a vein cuff to a tibial artery when such an option is possible.

Autosomal dominant diffuse leukoencephalopathy with neuroaxonal spheroids

OBJECTIVE

To provide clinical, MRI, and histopathologic findings in a rare white matter disorder with autosomal dominant inheritance, so-called hereditary diffuse leukoencephalopathy with spheroids (HDLS).

BACKGROUND

Progressive leukoencephalopathies often constitute a diagnostic dilemma in both children and adults. In some cases, histopathologic examination of brain tissue is required for a classifying diagnosis.

METHODS

Clinical history, MRI, and autopsy findings were reviewed in three patients with HDLS: a father, his daughter, and an unrelated patient.

RESULTS

Clinical history consisted of an adult-onset neurologic deterioration with signs of frontal lobe dysfunction, epilepsy, spasticity, ataxia, and mild extrapyramidal disturbances. MRI findings included cerebral atrophy and patchy white matter changes, most pronounced in the frontal and frontoparietal area with extension through the posterior limb of the internal capsule into the pyramidal tracts of the brainstem. Autopsy in two patients revealed a leukoencephalopathy with frontoparietal and frontal preponderance and numerous neuroaxonal spheroids in the abnormal white matter. The pyramidal tracts were affected throughout the brainstem.

CONCLUSION

Similar clinical and histopathologic findings have been reported in members of a Swedish pedigree. The homogeneity of the findings strongly suggests that HDLS is a distinct disease entity. In the absence of a biochemical or genetic marker, a definitive diagnosis requires histopathologic confirmation in one of the affected family members. Neuroaxonal spheroids.

Defining and categorizing leukoencephalopathies of unknown origin: MR imaging approach

PURPOSE

To categorize leukoencephalopathies of unknown origin into a few major groups by using magnetic resonance (MR) imaging criteria to facilitate further studies, and to assess the possibility of defining "new" (i.e., until now unknown) disease entities within these major groups.

MATERIALS AND METHODS

MR images of 92 patients (55 male, 37 female; mean age, 9.3 years) with a leukoencephalopathy were examined by using a scoring list of 68 items. Seven major categories were defined according to the predominant location of the white matter abnormalities. Statistical analysis was used to assess the validity of these seven categories.

RESULTS

Statistical analysis results showed that the seven categories could be well distinguished by either using the defining variables initially accepted as inclusion criteria or selecting a few other variables found to have discriminating value. The additional variables confirmed that the categories are essentially distinct and vary systematically with regard to items other than the inclusion criteria. The existence of two recently defined leukoencephalopathies was confirmed, but no consistent evidence of other new disease entities could be provided.

CONCLUSION

Establishing these seven categories helps in the interpretation of individual studies by demonstrating features that the patient has in common with other patients, and it may facilitate further research on homogeneous subgroups of patients and allow pooling of data across multiple centers.

The gene for leukoencephalopathy with vanishing white matter is located on chromosome 3q27

Leukoencephalopathy with vanishing white matter (VWM) is an autosomal recessive disorder with normal early development and, usually, childhood-onset neurological deterioration. At present, diagnosis of VWM is based on clinical examination and the results of repeat magnetic resonance imaging and magnetic resonance spectroscopy, which show that, with time, increasing amounts of the cerebral white matter vanish and are replaced by cerebrospinal fluid. We have performed a genome linkage screening of a panel of 19 families of different ethnic origins. Significant linkage to chromosome 3q27 was observed in a 7-cM interval between markers D3S3730 and D3S3592, with a maximum multipoint LOD score of 5.1 calculated from the entire data set. The results of genealogical studies have suggested that seven parents in four Dutch families with VWM may have inherited an allele for the disease from a common ancestor who lived at least eight generations ago. Analysis of these families provided further evidence for the localization of the gene for VWM to 3q27. The patients shared a haplotype spanning 5 cM between markers D3S1618 and D3S3592. In one family of a different ethnic background, the patient had, in the same region, homozygosity for 13 consecutive markers spanning at least 12 cM, suggesting consanguinity between the parents. A healthy sibling of this patient had the same homozygous haplotype, which suggests that the healthy sibling is presymptomatic for the disease.

Automated Talairach atlas-based parcellation and measurement of cerebral lobes in children

This study applied a Talairach-based automated parcellation method, originally proposed for adults, to the measurement of lobar brain regions in pediatric study groups. Manual measures of lobar brain regions in a sample of 15 healthy boys, girls and adults were used initially to revise the original Talairach-based grid to increase its applicability to pediatric brains. The applicability of the revised Talairach grid was then tested on an independent sample of five girls with Rett syndrome. As Tables 3 and 4 in the text demonstrate, sensitivity, specificity and positive predictive values either remained unchanged or increased as a result of revising the sectors to fit the brains of children. High levels of sensitivity and specificity were achieved for all revised Talairach-based calculations in relation to the manual measures. Both positive predictive values and intraclass correlations between volumetric measures produced by the revised automated and manual methods varied with the relative size of the brain region. Values were relatively low for smaller structures such as the brainstem and subcortical region, and high for lobar regions. These results suggest that the automated Talairach atlas-based parcellation method can produce sensitive and specific volumetric measures of lobar brain regions in both normal children and children with brain disorders. Accordingly, the method holds much promise for facilitating quantitative pediatric neuroimaging research.

Vascular surgical society of great britain and ireland: influence of contralateral stenosis on long-term mortality rate following carotid surgery

BACKGROUND: Recent evidence suggests that high-grade contralateral stenosis has an adverse effect on perioperative morbidity in carotid endarterectomy (CEA). The relationship between contralateral high-grade stenosis and long-term survival after CEA was examined. METHODS: Three hundred and twenty-seven patients undergoing 333 CEA operations were entered prospectively into a database and long-term follow-up was instituted. Cardiac and stroke risk factors were identified before operation and correlated with long-term survival and cause of death. RESULTS: Mean age at operation was 68 (range 42-86) years. Median follow-up was 2 (range 1-8) years. There were 45 deaths (seven perioperative), 17 myocardial, 16 from stroke (four perioperative), five from neoplasia, three respiratory and four others. The cumulative 5-year survival rate was 75 per cent. Patients with high-grade contralateral stenosis (greater than 80 per cent) had a significantly reduced life expectancy after CEA (P < 0. 05). CONCLUSION: Severe contralateral carotid disease is not only an adverse perioperative risk factor but also has negative implications for survival of the patient in the longer term. Following CEA, patients in general have a lower life expectancy than a normal age-matched population.

Altered development of glutamate and GABA receptors in the basal ganglia of girls with Rett syndrome

Rett syndrome (RS), a genetic disorder found almost exclusively in females, is associated with psychomotor regression and stereotyped hand movements. To determine whether a defect in basal ganglia amino acid neurotransmission plays a role in RS, NMDA-, AMPA-, kainate (KA)-, and metabotropic (mGluR)-type glutamate receptors (GluRs) and GABA receptors were labeled autoradiographically in the caudate, putamen, and globus pallidus of postmortem brain slices from 9 RS girls and 10 age-related controls. The cases were divided into younger (8 years or younger) and older age groups to study age-related changes in receptor binding density. We found significant reductions in AMPA and NMDA receptor density in the putamen and in KA receptor density in the caudate of older RS cases compared to controls. In contrast, mGluR density in the basal ganglia of RS patients was not altered significantly. The density of GluRs in control subjects generally showed more limited changes with age than in RS cases. In contrast to ionotropic GluRs, GABA receptor density was significantly increased in the caudate of young RS patients. The effects on GluR density in the putamen, which serves a primary motor function, were consistent with the motor deficits observed in RS, while those on amino acid transmitter receptors in the caudate may account for some cognitive features. Our studies demonstrate regional, receptor-subtype, and age-specific alterations in amino acid neurotransmitter receptors in the basal ganglia of RS girls. These changes may correlate with age-related clinical stages observed in RS.

Development of amino acid receptors in frontal cortex from girls with Rett syndrome

To determine whether a disorder of excitatory neurotransmission plays a role in the pathophysiology of Rett syndrome (RS), N-methyl-D-aspartate (NMDA), adenosine monophosphate acid (AMPA), kainate, and metabotropic types of glutamate receptors were labeled autoradiographically in the superior frontal gyrus (SFG) from 9 RS patients and 10 female controls. The results showed a trend for the densities of NMDA, AMPA, gamma-aminobutyric acid, and metabotropic glutamate receptors to be higher in younger patients than in controls and for densities in older patients to fall below those of controls. The age-related changes in SFG NMDA receptor density may be correlated with the shift from psychomotor regression and seizures in younger stage II/III RS girls to the less epileptic plateau stage in older girls.