Voxel-Based Morphometry-from Hype to Hope. A Study on Hippocampal Atrophy in Mesial Temporal Lobe Epilepsy

BACKGROUND AND PURPOSE

Automated volumetry of the hippocampus is considered useful to assist the diagnosis of hippocampal sclerosis in temporal lobe epilepsy. However, voxel-based morphometry is rarely used for individual subjects because of high rates of false-positives. We investigated whether an approach with high dimensional warping to the template and nonparametric statistics would be useful to detect hippocampal atrophy in patients with hippocampal sclerosis.

MATERIALS AND METHODS

We performed single-subject voxel-based morphometry with nonparametric statistics within the framework of Statistical Parametric Mapping to compare MRI from 26 well-characterized patients with temporal lobe epilepsy individually against a group of 110 healthy controls. The following statistical threshold was used: P < .05 corrected for multiple comparisons with family-wise error over the region of interest right and left hippocampus.

RESULTS

The sensitivity for the detection of atrophy related to hippocampal sclerosis was 0.92 (95% CI, 0.67-0.99) for the right hippocampus and 0.60 (0.31-0.83) for the left, and the specificity for volume changes was 0.98 (0.93-0.99). All clusters of decreased hippocampal volumes were correctly lateralized to the seizure focus. Hippocampal volume decrease was in accordance with neuronal cell loss on histology reports.

CONCLUSIONS

Nonparametric voxel-based morphometry is sensitive and specific for hippocampal atrophy in patients with mesial temporal lobe epilepsy and may be useful in clinical practice.

Ciprofloxacin intercalated in fluorohectorite clay: identical pure drug activity and toxicity with higher adsorption and controlled release rate

We present the use of the synthetic clay fluorohectorite (Fh) as a drug delivery system of the antibiotic ciprofloxacin. The adsorption capacity is very high, and Fh promotes controlled drug release without changing drug effectiveness and toxicity.

Developmental changes in gamma-aminobutyric acid levels in attention-deficit/hyperactivity disorder

While the neurobiological basis and developmental course of attention-deficit/hyperactivity disorder (ADHD) have not yet been fully established, an imbalance between inhibitory/excitatory neurotransmitters is thought to have an important role in the pathophysiology of ADHD. This study examined the changes in cerebral levels of GABA+, glutamate and glutamine in children and adults with ADHD using edited magnetic resonance spectroscopy. We studied 89 participants (16 children with ADHD, 19 control children, 16 adults with ADHD and 38 control adults) in a subcortical voxel (children and adults) and a frontal voxel (adults only). ADHD adults showed increased GABA+ levels relative to controls (P = 0.048), while ADHD children showed no difference in GABA+ in the subcortical voxel (P > 0.1), resulting in a significant age by disorder interaction (P = 0.026). Co-varying for age in an analysis of covariance model resulted in a nonsignificant age by disorder interaction (P = 0.06). Glutamine levels were increased in children with ADHD (P = 0.041), but there was no significant difference in adults (P > 0.1). Glutamate showed no difference between controls and ADHD patients but demonstrated a strong effect of age across both groups (P < 0.001). In conclusion, patients with ADHD show altered levels of GABA+ in a subcortical voxel which change with development. Further, we found increased glutamine levels in children with ADHD, but this difference normalized in adults. These observed imbalances in neurotransmitter levels are associated with ADHD symptomatology and lend new insight in the developmental trajectory and pathophysiology of ADHD.

Coupling between resting cerebral perfusion and EEG

While several studies have investigated interactions between the electroencephalography (EEG) and functional magnetic resonance imaging BOLD signal fluctuations, less is known about the associations between EEG oscillations and baseline brain haemodynamics, and few studies have examined the link between EEG power outside the alpha band and baseline perfusion. Here we compare whole-brain arterial spin labelling perfusion MRI and EEG in a group of healthy adults (n = 16, ten females, median age: 27 years, range 21-48) during an eyes closed rest condition. Correlations emerged between perfusion and global average EEG power in low (delta: 2-4 Hz and theta: 4-7 Hz), middle (alpha: 8-13 Hz), and high (beta: 13-30 Hz and gamma: 30-45 Hz) frequency bands in both cortical and sub-cortical regions. The correlations were predominately positive in middle and high-frequency bands, and negative in delta. In addition, central alpha frequency positively correlated with perfusion in a network of brain regions associated with the modulation of attention and preparedness for external input, and central theta frequency correlated negatively with a widespread network of cortical regions. These results indicate that the coupling between average EEG power/frequency and local cerebral blood flow varies in a frequency specific manner. Our results are consistent with longstanding concepts that decreasing EEG frequencies which in general map onto decreasing levels of activation.

[Propionic acidemia and sensorineural hearing loss: is there a connection at the molecular genetics level?]

CURRENT KNOWLEDGE

Propionic acidemia is caused by a gene defect leading to malfunction of the enzyme propionyl-CoA carboxylase (PCC) and in turn to a pathologic accumulation of propionic acid. Many mutations have been found at the molecular genetic level over the past 20 years, and their implications for the limitation of enzyme activity of PCC in propionic acidemia are discussed.

SCIENTIFIC QUESTION AND AIMS OF THE STUDY

As an elevated incidence of deafness has been observed in patients with propionic acidemia, the question arises of whether mutations primarily responsible for this disease could also be the underlying cause for a genetic form of deafness.

METHODS AND RESULTS

As well as a standard pure tone audiogram, a pedigree was elaborated and DNA isolated for each family concerned. In one family several subjects displayed mutations of both the PCCA and the PCCB -subunits; these included only one girl whose phenotype was affected, however.

CONCLUSIONS

Mutation of the PCCB subunit p.R113X has not previously been mentioned in the literature. According to our present knowledge no connection can be assumed between either of the two mutations and the severe sensorineural hearing loss.

[The influence of the Tübingen soft palate plate and early cleft closure on swallowing and Eustachian tube function in children with Pierre Robin sequence]

CURRENT KNOWLEDGE

Children with Pierre Robin sequence (PRS) typically have difficulty with bolus transport and swallowing. Due to velopharyngeal insufficiency caused by the cleft palate, a high percentage of the children affected also have impaired Eustachian tube function.

AIMS OF THE STUDY

In the literature, substantial information may be obtained on conductive hearing loss in PRS patients; however, no study has yet been performed to investigate whether wearing a soft palate plate and relatively early surgical cleft palate closure positively influence Eustachian tube function. In the present study this question was investigated.

METHODS AND RESULTS

A total of 41 PRS children, 27 girls and 14 boys, were included in the study and were examined for hearing ability prior to and after surgical cleft palate closure. All of the children had been wearing a Tübingen soft palate plate until surgical cleft palate closure, which occurred at an age of 3-13 months (mean age 7.3 months). Based on data obtained prior to surgery by BERA, otoacoustic emissions and tympanometry, a hearing loss of more than 30 dB was diagnosed in 68.4% of the children. After 3-6 months, normal hearing ability was found in 70%.

CONCLUSIONS

Wearing the Tübingen soft palate plate, and the improved swallowing function resulting from this, as well as early surgical cleft palate closure had a very positive impact on the hearing ability of the children included in the study.

[Factors influencing rehabilitation of sensorineural hearing loss with hearing aids]

BACKGROUND

A large proportion of older as well as younger patients do not use their hearing aids. Of the younger hearing impaired population, this occurs in the majority of those who do not benefit sufficiently from their hearing aids and, consequently, they face difficulties in their working and social life.

SCIENTIFIC QUESTION

Our aim was to evaluate whether a classical hearing aid adjustment is of sufficient predictive value to determine whether adequate rehabilitation in everyday and professional life will occur.

METHODS AND RESULTS

A questionnaire was returned by 197 adult hearing impaired patients. Only 108 were using their hearing aids all the time; 57 rarely and 32 never. The main reason for this low rehabilitation rate proved to be inadequate amplification. At the workplace, insufficient speech discrimination came into play. Another important factor was dysacusis induced by specific noise signals. There was an intolerable acoustic feedback in 40% which could not be sufficiently alleviated. Taking these results into account, only about a third of patients were sufficiently rehabilitated.

CONCLUSIONS

Proof of effectiveness in a typical audiological testing situation is an important but not a fully reliable predictor for effectiveness in everyday life. Even when hearing aids are shown to be effective with such testing, their application in particular everyday or work situations may be insufficient of even impossible.

African origin of human T-lymphotropic virus type 2 (HTLV-2) supported by a potential new HTLV-2d subtype in Congolese Bambuti Efe Pygmies

We identified a potential new subtype within human T-cell lymphotropic virus type 2 (HTLV-2), HTLV-2d, present in members of an isolated Efe Bambuti Pygmy tribe. Two of 23 Efe Pygmies were HTLV-2 seropositive, with HTLV-2 Western blot and enzyme-linked immunosorbent assay reactivities. From one of them the entire genome of the HTLV-2 strain Efe2 could be amplified and sequenced. In all gene regions analyzed, this strain was the most divergent HTLV-2 strain, differing by 2.4% (tax/rex) to 10.7% (long terminal repeat) from both subtypes HTLV-2a and HTLV-2b, yet major functional elements are conserved. The similarity between the HTLV-2 Efe2 Gag and Env proteins and the corresponding HTLV-2a and -2b proteins is consistent with the observed serological reactivity. In the proximal pX region, one of the two alternative splice acceptor sites is abolished in HTLV-2 Efe2. Another interesting feature of this potential new subtype is that it has a Tax protein of 344 amino acids (aa), which is intermediate in length between the HTLV-2a Tax protein (331 aa) and the HTLV-2b and -2c Tax proteins (356 aa) and similar to the simian T-cell lymphotropic virus type 2 (STLV-2) PP1664 Tax protein. Together these two findings suggest a different phenotype for the HTLV-2 Efe2 strain. Phylogenetic analyses confirmed that the Pygmy Efe2 strain potentially belonged to a new and quite divergent subtype, HTLV-2d. When the STLV-2 bonobo viruses PP1664 and PanP were used as an outgroup, it was clear that the Pygmy HTLV-2 Efe2 strain had the longest independent evolution and that HTLV-2 evolution is consistent with an African origin.

Adriamycin-induced chronic proteinuria: a structural and functional study

Focal, segmental glomerulosclerosis is frequently associated with chronic proteinuria and progressively declining renal function in humans as well as in experimental models of glomerular disease. Although little is known regarding the pathogenesis of this lesion, persistent, massive proteinuria has been associated with a poor prognosis. The administration of adriamycin to rats results in proteinuria of glomerular origin. We used this model to study the glomerular functional and structural alterations associated with proteinuria of 4 to 5 weeks duration. Studies of single nephron function revealed a 34% reduction in nephron plasma flow and a 50% decline in the glomerular ultrafiltration coefficient in rats given adriamycin. Single nephron glomerular filtration rate, however, was only modestly reduced (27%), because of an 8.0 mm Hg elevation of mean transcapillary hydraulic pressure difference (P less than 0.05). Morphologically, glomeruli of adriamycin-treated rats demonstrated significantly increased mesangial matrix and cellularity. In addition, glomerular capillaries frequently appeared enlarged, and epithelial cell bleb formation was evident. Focal glomerulosclerosis, however, was only rarely seen. The functional and morphologic characteristics of chronic adriamycin nephrosis are different from those associated with chronic proteinuria induced by repetitive administration of aminonucleoside of puromycin. Comparison of the two models suggests that the development of focal glomerulosclerosis can be dissociated from proteinuria and elevations of intraglomerular hydraulic pressures.