Two distinct neuronal networks mediate the awareness of environment and of self

Evidence from functional neuroimaging studies on resting state suggests that there are two distinct anticorrelated cortical systems that mediate conscious awareness: an "extrinsic" system that encompasses lateral fronto-parietal areas and has been linked with processes of external input (external awareness), and an "intrinsic" system which encompasses mainly medial brain areas and has been associated with internal processes (internal awareness). The aim of our study was to explore the neural correlates of resting state by providing behavioral and neuroimaging data from healthy volunteers. With no a priori assumptions, we first determined behaviorally the relationship between external and internal awareness in 31 subjects. We found a significant anticorrelation between external and internal awareness with a mean switching frequency of 0.05 Hz (range: 0.01-0.1 Hz). Interestingly, this frequency is similar to BOLD fMRI slow oscillations. We then evaluated 22 healthy volunteers in an fMRI paradigm looking for brain areas where BOLD activity correlated with "internal" and "external" scores. Activation of precuneus/posterior cingulate, anterior cingulate/mesiofrontal cortices, and parahippocampal areas ("intrinsic system") was linearly linked to intensity of internal awareness, whereas activation of lateral fronto-parietal cortices ("extrinsic system") was linearly associated with intensity of external awareness.

Effects of lip revision surgery in cleft lip/palate patients

The decision for lip revision surgery in patients with repaired cleft lip/palate is based on surgeons' subjective evaluation of lip disability. An objective evaluation would be highly beneficial for the assessment of surgical outcomes. In this study, the effects of lip revision on circumoral movements were objectively quantified. The hypothesis was that lip revision increases scarring and impairment. The study was a non-randomized clinical trial that included patients with cleft lip who had revision, patients with cleft lip who did not, and non-cleft control individuals. Three-dimensional facial movements were measured. Revision patients were measured before and after surgery. Other individuals were measured at similar intervals. Regression models were fit to summary measurements, and changes were modeled. Patients with repaired cleft lip/palate had fewer mean movements than control individuals. Lip revision did not worsen mean movements; however, individual patients' movements varied from 'improvement' to 'no change' to 'worse' relative to those of control individuals.

Long-term stability of adolescent versus adult surgery for treatment of mandibular deficiency

In mandibular deficient patients, mandibular growth is not expected after the adolescent growth spurt, so mandibular advancement surgery is often carried out at 13 years. To test if the long-term stability for younger patients is similar to that for adult patients, the authors compared cephalometric changes from 1-year postsurgery (when changes due to the surgery should be completed) to 5-year follow up. 32 patients who had early mandibular advancement with or without simultaneous maxillary surgery (aged up to 16 for girls and 18 for boys), and 52 patients with similar surgery at older ages were studied. Beyond 1-year postsurgery, the younger patients showed significantly greater change in the horizontal and vertical position of points B and pogonion, the horizontal (but not vertical) position of gonion, and mandibular plane angle. 50% of younger patients had 2-4mm backward movement of Pg and another 25% had >4mm. 15% of older patients had 2-4mm change and none had >4mm. Long-term changes in younger patients who had two-jaw surgery were greater than for mandibular advancement only. Changes in younger groups were greater than for adult groups. Satisfaction with treatment and perception of problems were similar for both groups.

Functional connectivity in the default network during resting state is preserved in a vegetative but not in a brain dead patient

Recent studies on spontaneous fluctuations in the functional MRI blood oxygen level-dependent (BOLD) signal in awake healthy subjects showed the presence of coherent fluctuations among functionally defined neuroanatomical networks. However, the functional significance of these spontaneous BOLD fluctuations remains poorly understood. By means of 3 T functional MRI, we demonstrate absent cortico-thalamic BOLD functional connectivity (i.e. between posterior cingulate/precuneal cortex and medial thalamus), but preserved cortico-cortical connectivity within the default network in a case of vegetative state (VS) studied 2.5 years following cardio-respiratory arrest, as documented by extensive behavioral and paraclinical assessments. In the VS patient, as in age-matched controls, anticorrelations could also be observed between posterior cingulate/precuneus and a previously identified task-positive cortical network. Both correlations and anticorrelations were significantly reduced in VS as compared to controls. A similar approach in a brain dead patient did not show any such long-distance functional connectivity. We conclude that some slow coherent BOLD fluctuations previously identified in healthy awake human brain can be found in alive but unaware patients, and are thus unlikely to be uniquely due to ongoing modifications of conscious thoughts. Future studies are needed to give a full characterization of default network connectivity in the VS patients population.

Hallux rigidus: a cross-sectional study to evaluate clinical parameters

BACKGROUND

Hallux rigidus (HR) is a common condition with history and physical examination used to help evaluate pathology, grade clinical changes and to inform treatment.

METHOD

A cross-sectional study was undertaken to evaluate the demographics of and clinical parameters encountered in HR. In 110 subjects (180 feet) aged 18-70 years (mean 52 years) a standardized history and physical examination was undertaken. Clinical parameters associated with HR were evaluated. The Foot Health Status Questionnaire (FHSQ) was used to measure health-related quality-of-life dimensions.

RESULTS

Seventy (64%) subjects had bilateral HR and 73 (66%) were female. Mean HR onset was 44 (14-68 years) years and median HR duration 6 years (1-33 years). A history of 1st MTPJ trauma presented in 22% of subjects; 74% of whom had unilateral HR. Eighty-four (47%) feet had pes planus based on a positive Foot Posture Index. A correlation between pes planus and 1st MTPJ pain was found (r=0.84, p=0.05). In 74% of feet, hallux abductus interphalangeus angle (HAI degrees ) was greater than normal (< or =10 degrees ). A correlation between HAI and reduced 1st MTPJ ROM was found (r=0.92, p=0.05). Second toe length was the same as the hallux in 111 feet (62%). A correlation between valgus hallucal rotation and 1st MTP joint pain in HR was found (r=.78, p=.05). A positive relationship was found between 2nd toe length and 1st MTPJ pain (p=0.001<0.05). A correlation between hallucal interphalangeal joint (IPJ) hyperextension and 1st MTPJ pain was found (r=0.78, p=0.01). A positive relationship was found between lesser MTPJ pain and supination at propulsion (p<0.001). There was no evidence of Achilles tendon contracture. The FHSQ results concur with clinical findings.

CONCLUSIONS

HR was associated with female gender, bilateral involvement, older age groups, increased HAI degrees, 2nd toe length similar to hallux, hallucal IPJ hyperextension, lesser MTP joint pain, flat foot and certain gait alterations. HR was not associated with Achilles tendon tightness or footwear. The content validity of clinical parameters of HR needs to be established by formal research prior to their inclusion in a classification of HR.

Selecting forward models for MEG source-reconstruction using model-evidence

We investigated four key aspects of forward models for distributed solutions to the MEG inverse problem: 1) the nature of the cortical mesh constraining sources (derived from an individual's MRI, or inverse-normalised from a template mesh); 2) the use of single-sphere, overlapping spheres, or Boundary Element Model (BEM) head-models; 3) the density of the cortical mesh (3000 vs. 7000 vertices); and 4) whether source orientations were constrained to be normal to that mesh. These were compared within the context of two types of spatial prior on the sources: a single prior corresponding to a standard L2-minimum-norm (MNM) inversion, or multiple sparse priors (MSP). The resulting generative models were compared using a free-energy approximation to the Bayesian model-evidence after fitting multiple epochs of responses to faces or scrambled faces. Statistical tests of the free-energy, across nine participants, showed clear superiority of MSP over MNM models; with the former reconstructing deeper sources. Furthermore, there was 1) no evidence that an individually-defined cortical mesh was superior to an inverse-normalised canonical mesh, but 2) clear evidence that a BEM was superior to spherical head-models, provided individually-defined inner skull and scalp meshes were used. Finally, for MSP models, there was evidence that the combination of 3) higher density cortical meshes and 4) dipoles constrained to be normal to the mesh was superior to lower-density or freely-oriented sources (in contrast to the MNM models, in which free-orientation was optimal). These results have practical implications for MEG source reconstruction, particularly in the context of group studies.

Medium-to-long term DEXA analysis of an uncemented (AML) femoral component

We present medium-to-long-term bone mineral density studies assessing bone resorption and remodelling around the cementless femoral component of a total hip arthroplasty (Depuy AML prosthesis). Bone mineral densities were compared with the unoperated side at a time interval of eight years between scans using dual energy X-ray absorptiometry. Initial proximal stress shielding is known but we show that this response continues into the medium to long term in relative terms. We have also found an overall trend for bone mineral density to increase around the prosthesis with the greatest changes occurring distally. The greatest real increase in bone mineral density occurred in Gruen zones 2, 3 and 5 with smaller increases in zones 1, 4, 6 and 7. However, when compared with the contralateral unoperated femur (thus considering systemic changes in bone mineral density), we found these changes only reached statistical significance in Gruen zones 5, 6 and 7.

Bispectral index correlates with regional cerebral blood flow during sleep in distinct cortical and subcortical structures in humans

The relationship between the Bispectral Index (BIS), an EEG-based monitor of anesthesia, and brain activity is still unclear. This study aimed at investigating the relationship between changes in BIS values during natural sleep and regional cerebral blood flow (rCBF) variations, as measured by Positron Emission Tomography (PET). Data were obtained from six young, healthy, right-handed, male volunteers (20-30 years old) using the H2(15)O infusion method. PET scans were performed both during waking and various stages of sleep. BIS values were monitored continuously and recorded during each PET scan. Positive correlations were detected between BIS and rCBF values in dorsolateral prefontal, parietal, anterior and posterior cingulate, precuneal, mesiofrontal, mesiotemporal and insular cortices. These areas belong to a frontoparietal network known to be related to awareness of self conscious sensory perception, attention and memory. BIS values also positively correlated with activity in brainstem and thalami, both structures known to be involved in arousal and wakefulness. These results show that BIS changes associated with physiological sleep depth co-vary with the activity of specific cortical and subcortical areas. The latter are known to modulate arousal, which in turn allows sustained thalamo-cortical enhancement of activity in a specific frontoparietal network known to be related to the content of consciousness. Thus, although mainly derived from frontal EEG, BIS could represent a wider index of cerebral activity.

Cross-sectional study to evaluate radiological parameters in hallux rigidus

BACKGROUND

Hallux rigidus (HR) is a common condition with X-rays used to evaluate its pathology, grade joint changes and to inform treatment.

METHOD

A cross-sectional study was undertaken to evaluate radiological foot parameters in HR. In 110 subjects (180 feet) aged 18-70 years (mean 52 years) standard weight-bearing X-rays were examined using dorsal plantar and lateral views.

RESULTS

Seventy (64%) subjects had bilateral HR and 73 (66%) were female. The mean onset of HR (denoted by first metatarsophalangeal (MTP) joint restriction/pain) was 44 (14-68 years) years and median HR duration was 6 years (1-33 years). Flat or chevron-shaped metatarsal heads presented in 131 (73%) feet and a history of first MTP joint trauma in 22% (74% of whom had unilateral HR). In 74% of feet hallux abductus interphalangeus angle (HAI degrees) was greater than normal (< or =10 degrees). Correlations between first MTP joint narrowing and sclerosis (r=0.76, p=0.01) and increased HAI degrees and first MTP joint narrowing (r=0.34, p=0.01) was found. The mean hallux equinus angle of 11 degrees was outside the normal range (16-18 degrees). Abnormal sesamoid morphology presented in 117 (65%) feet (30% irregular or hypertrophic). Proximal sesamoid displacement was greater than that seen in non-HR. Metatarsus primus elevatus was within normal range (< or =8 mm) in 160 (89%) feet. The first metatarsal was longer than the second metatarsal in 66 (37%) feet although the first metatarsal was longer than the third metatarsal in 131 (73%) feet and may be responsible for altered forefoot function in HR.

CONCLUSIONS

HR was associated with female gender, bilateral involvement, older age groups, flat or chevron-shaped metatarsal head, longer proximal phalanx, increased HAI degrees and a first metatarsal longer than the third metatarsal. For radiological parameters to be considered valid for inclusion in a classification of HR their content validity needs to be established by formal research.

The mechanism of action of a citrus oil blend against Enterococcus faecium and Enterococcus faecalis

AIMS

The aim was to explore the mechanisms by which a blend of orange (Citrus sinensis) : bergamot (Citrus bergamia) (1 : 1 v/v) EO (essential oil) (2% v/v) and its vapour (15 mg l(-1) air) brings about its antimicrobial effect against Enterococcus faecium and Enterococcus faecalis.

METHODS AND RESULTS

Cells were exposed to the blend in oil or vapour form in a sealed unit. Membrane permeability was measured using an NPN assay and intra and extracellular ATP concentrations were assessed using luminescence. Assays using 3,3-dipropylthiacarbocyanine and carboxyfluorescein diacetate succinimidyl ester measured membrane potential and intracellular pH changes. TEM images of treated cells indicate morphological differences and show the possible uptake of the EO into the cell. After cells were exposed to EO or vapour, cell permeability increased by x2 and x40 respectively. A decrease of 1.5 in intracellular pH, 20 a.u. in membrane potential and 18 pmol mg(-1) protein of intracellular ATP occurred.

CONCLUSIONS

The EO blend affects the cell membrane and cell homeostasis resulting in inhibition of growth or cell death.

SIGNIFICANCE AND IMPACT OF THE STUDY

Understanding the mechanisms by which EOs bring about their antibacterial effect could lead to an alternative to chemical-based bactericides for use against Enterococcus sp.

Genetic variability of the SNPforID 52-plex identification-SNP panel in Central West Colombia

A set of autosomal single nucleotide polymorphism (SNP) loci was analyzed using the 52-plex assay previously described by Sanchez et al. [J.J. Sanchez, C. Phillips, C. Borsting, K. Balogh, M. Bogus, M. Fondevila, C.D. Harrison, E. Musgrave-Brown, A. Salas, D. Syndercombe-Court, P.M. Schneider, A. Carracedo, N. Morling, A multiplex assay with 52 single nucleotide polymorphisms for human identification, Electrophoresis 27 (2006) 1713-1724] in 140 samples of unrelated individuals born in the Colombian regions of, Risaralda, Caldas, Quindio, Antioquia, Tolima and Valle, and 164 samples of unrelated individuals with declared Native American ancestry from Colombia. Allele frequencies and statistical parameters of forensic interest are presented for the 52 SNPs. All loci were in agreement with Hardy-Weinberg equilibrium while comparisons with population samples of Argentina, Portugal, Spain, Mozambique, and Taiwan revealed significant differences in allele frequency distributions.