Regional cerebral blood flow in children from 3 to 5 months of age

BACKGROUND AND PURPOSE

Understanding the relationship between brain and behavior in early childhood requires a probe of functional brain development. We report the first large study of regional CBF by use of arterial spin-labeling in young children.

MATERIALS AND METHODS

Cerebral blood flow by use of arterial spin-labeling was measured in 61 healthy children between the ages of 3 and 5 months. Blood flow maps were parcellated into 8 broadly defined anatomic regions of each cerebral hemisphere.

RESULTS

There was no sex effect; however, group analysis demonstrated significantly greater CBF in the sensorimotor and occipital regions compared with dorsolateral prefrontal, subgenual, and orbitofrontal areas (P < .0001). A significant age effect was also identified, with the largest increase in blood flow between 3 and 5 months occurring in the following regions: orbitofrontal (P < .009), subgenual (P < .002), and inferior occipital lobe (P = .001).

CONCLUSIONS

These results are consistent with prior histologic studies demonstrating regional variation in brain maturation and suggest that arterial spin-labeling is sensitive to regional as well as age-related differences in CBF in young children.

Oestradiol differentially influences feeding behaviour depending on diet composition in female rhesus monkeys

In females, cyclical changes in the ovarian hormone oestradiol are known to modulate feeding behaviour. However, what is less clear is how these behavioural effects of oestradiol are modified by the macronutrient content of a diet. In the present study, we report data showing that oestradiol treatment results in both significantly smaller meals and a reduced total calorie intake in ovariectomised, socially-housed female rhesus macaques when only chow diet is available. Conversely, during a choice dietary condition where both palatable and chow options are available, oestradiol treatment had no observable, attenuating effect on calorie intake. During this choice dietary phase, all animals consumed more of the palatable diet than chow diet; however, oestradiol treatment appeared to further increase preference for the palatable diet. Finally, oestradiol treatment increased snacking behaviour (i.e. the consumption of calories outside of empirically defined meals), regardless of diet condition. These findings illustrate how oestradiol differentially influences feeding behaviour depending on the dietary environment and provides a framework in which we can begin to examine the mechanisms underlying these observed changes.

Development and validation of an equine nerve block simulator to supplement practical skills training in undergraduate veterinary students

Lameness is the most common presenting complaint in equine practice. Performing diagnostic nerve blocks is an integral part of any lameness work-up, and is therefore an essential skill for equine practitioners. However, the opportunities for veterinary students to practice this skill are limited. The aim of this study was to design and validate an equine nerve block simulator. It was hypothesised that the simulator would improve students' ability and enhance their confidence in performing nerve blocks. A simulator was built using an equine forelimb skeleton and building foam. Wire wool targets were placed under the foam in the positions corresponding to the anatomical location of the most palmar digital, abaxial and low four-point nerve blocks and attached to an electrical circuit. The circuit became complete when the operator placed a needle in the correct position and immediate audible feedback with a buzzer was provided. To validate the simulator, it was compared with two established teaching methods: cadaver training and theoretical training with a hand-out. Cadaver-trained students achieved the best results (73 per cent correct blocks), compared with simulator-trained students (71 per cent correct blocks), and a hand-out trained group (58 per cent correct blocks). Feedback obtained with a questionnaire showed that students enjoyed simulator training more, and that they felt more confident in performing diagnostic nerve blocks than the other two groups. The equine nerve block simulator provides a safe, cost-effective method to supplement the teaching of diagnostic analgesia to undergraduate veterinary students.

Deafness in children: a national survey of aetiological investigations

OBJECTIVE

The aim of this study was to obtain national data regarding adherence to national guidelines for aetiological investigations for hearing loss in children and highlight any variations in practice. Information was also collected on possible factors affecting lack of adherence.

DESIGN

An online questionnaire based on the national guidelines for aetiological investigations for deafness was designed.

SETTING

The questionnaire was distributed to the leads of all the Newborn Hearing Screening Programme (NHSP) sites across England through the Medical Research Council Hearing & Communication Group.

PARTICIPANTS

The questionnaire was sent to 100 recipients; from this 52 responses were obtained.

OUTCOME MEASURES

Variability in the investigations offered for hearing loss.

RESULTS

There was a 52% response rate. Analysis of the responses showed that audiovestibular physicians and paediatricians in audiology were more likely than other specialists to request level 1 investigations (investigations that are recommended to be offered in all cases). Respondents from London and the North West were more likely to request level 1 investigations compared with those from other regions. In all, 14 of the 19 audiovestibular physicians and paediatricians in audiology requested level 1 investigations routinely, but only 11 of 33 from other specialties did likewise. Of the 20 respondents from London and the Northwest, 15 requested level 1 investigations routinely, whereas only 10 of the 32 respondents from the other regions did the same. The difference was statistically significant in both cases. The geographical variation was specially marked for family audiograms and MRI.

CONCLUSIONS

There is significant variation from the national guidelines in requesting aetiological investigations for permanent hearing impairment (PHI) in children, depending on the specialty of the clinician and the geographical region, these variations appear partly to be due to the availability of local resources but also due to lack of awareness of the importance of some investigations.

Regulation of prefrontal excitatory neurotransmission by dopamine in the nucleus accumbens core

Interactions between dopamine and glutamate signalling within the nucleus accumbens core are required for behavioural reinforcement and habit formation. Dopamine modulates excitatory glutamatergic signals from the prefrontal cortex, but the precise mechanism has not been identified. We combined optical and electrophysiology recordings in murine slice preparations from CB1 receptor-null mice and green fluorescent protein hemizygotic bacterial artificial chromosome transgenic mice to show how dopamine regulates glutamatergic synapses specific to the striatonigral and striatopallidal basal ganglia pathways. At low cortical frequencies, dopamine D1 receptors promote glutamate release to both D1 and D2 receptor-expressing medium spiny neurons while D2 receptors specifically inhibit excitatory inputs to D2 receptor-expressing cells by decreasing exocytosis from cortical terminals with a low probability of release. At higher cortical stimulation frequencies, this dopaminergic modulation of presynaptic activity is occluded by adenosine and endocannabinoids. Glutamatergic inputs to both D1 and D2 receptor-bearing medium spiny neurons are inhibited by adenosine, released upon activation of NMDA and AMPA receptors and adenylyl cyclase in D1 receptor-expressing cells. Excitatory inputs to D2 receptor-expressing cells are specifically inhibited by endocannabinoids, whose release is dependent on D2 and group 1 metabotropic glutamate receptors. The convergence of excitatory and inhibitory modulation of corticoaccumbal activity by dopamine, adenosine and endocannabinoids creates subsets of corticoaccumbal inputs, selectively and temporally reinforces strong cortical signals through the striatonigral pathway while inhibiting the weak, and may provide a mechanism whereby continued attention might be focused on behaviourally salient information.

Juvenile ALS with basophilic inclusions is a FUS proteinopathy with FUS mutations

BACKGROUND

Juvenile amyotrophic lateral sclerosis (ALS) with basophilic inclusions is a form of ALS characterized by protein deposits in motor neurons that are morphologically and tinctorially distinct from those of classic sporadic ALS. The nosologic position of this type of ALS in the molecular pathologic and genetic classification of ALS is unknown.

METHODS

We identified neuropathologically 4 patients with juvenile ALS with basophilic inclusions and tested the hypothesis that specific RNA binding protein pathology may define this type of ALS. Immunohistochemical findings prompted us to sequence the fused in sarcoma (FUS) gene.

RESULTS

Motor symptoms began between ages 17 and 22. Disease progression was rapid without dementia. No family history was identified. Basophilic inclusions were strongly positive for FUS protein but negative for TAR DNA binding protein 43 (TDP-43). Granular and compact FUS deposits were identified in glia and neuronal cytoplasm and nuclei. Ultrastructure of aggregates was in keeping with origin from fragmented rough endoplasmic reticulum. Sequencing of all 15 exons of the FUS gene in 3 patients revealed a novel deletion mutation (c.1554_1557delACAG) in 1 individual and the c.1574C>T (P525L) mutation in 2 others.

CONCLUSION

Juvenile ALS with basophilic inclusions is a FUS proteinopathy and should be classified as ALS-FUS. The FUS c.1574C>T (P525L) and c.1554_1557delACAG mutations are associated with this distinct phenotype. The molecular genetic relationship with frontotemporal lobar degeneration with FUS pathology remains to be clarified.

Greater loss of axons in primary progressive multiple sclerosis plaques compared to secondary progressive disease

The pathological substrate of progressive disability in multiple sclerosis is hypothesized to be axonal loss. Differences in the demographic, pathological and radiological features of patients with primary progressive compared with secondary progressive multiple sclerosis raise the question as to whether they actually represent separate clinical entities. So far, large pathological studies comparing axonal damage between primary progressive and secondary progressive multiple sclerosis have not been reported. In this clinico-pathological study we examined the cervical spinal cord in patients with primary and secondary progressive multiple sclerosis. Human cervical spinal cord was derived at autopsy from 54 patients (17 primary progressive, 30 secondary progressive and 7 controls). Tissue was stained immunohistochemically and examined to determine: (i) the number of surviving corticospinal tract axons; (ii) the extent of grey and white matter demyelination; (iii) the degree of inflammation inside and outside of lesions; and (iv) the relationship between demyelination and axonal loss. Associated clinical data was used to calculate expanded disability status scale for each patient preceding death. Motor disability in the primary progressive and secondary progressive groups was similar preceding death. Secondary progressive multiple sclerosis patients showed considerably more extensive demyelination of both the white and grey matter of the cervical spinal cord. The total number of corticospinal axons was equally low in primary progressive and secondary progressive multiple sclerosis groups versus controls. The reduction of axonal density in demyelinated regions compared to normal appearing white matter was significantly more extensive in primary progressive versus secondary progressive patients (33% reduction versus 16% reduction, P < 0.001). These findings suggest axonal loss is the pathological substrate of progressive disability in both primary progressive and secondary progressive multiple sclerosis with a common plaque-centred mechanism. More extensive axonal loss within areas of demyelination in primary progressive multiple sclerosis could explain high levels of axonal loss observed in these patients despite low levels of demyelination.