The impact of pediatric obesity on biomechanical differences across the gait cycle at three walking speeds.

BACKGROUND: Obesity impacts a child's ability to walk with resulting biomechanical adaptations; however, existing research has not comprehensively compared differences across the gait cycle. We examined differences in lower extremity biomechanics across the gait cycle between children with and without obesity at three walking speeds. METHODS: Full gait cycles of age-matched children with obesity (N = 10; BMI: 25.7 ± 4.2 kg/m2) and without obesity (N = 10; BMI: 17.0 ± 1.9 kg/m2) were analyzed at slow, normal, and fast walking speeds. Main and interaction effects of group and speed across hip, knee, and ankle joint angles and moments in sagittal, frontal, and transverse planes were analyzed using one-dimensional statistical parametric mapping. FINDINGS: Compared to children without obesity, children with obesity had greater hip adduction during mid-stance, while also producing greater hip extensor moments during early stance phase, abductor moments throughout most of stance, and hip external rotator moments during late stance. Children with obesity recorded greater knee flexor, knee extensor and knee internal rotator moments during early stance, and knee external rotator moments in late stance than children without obesity; children with obesity also demonstrated greater ankle plantarflexor moments throughout mid and late stance. Interaction effects existed within joint kinetics data; children with obesity produced greater hip extensor moments at initial contact and toe-off when walking at fast compared to normal walking speed. INTERPRETATION: While few kinematic differences existed between the two groups, children with obesity exhibited greater moments at the hip, knee, and ankle during critical periods of controlling and stabilizing mass.

A versatile laser-based apparatus for time-resolved ARPES with micro-scale spatial resolution.

We present the development of a versatile apparatus for 6.2 eV laser-based time and angle-resolved photoemission spectroscopy with micrometer spatial resolution (time-resolved µ-ARPES). With a combination of tunable spatial resolution down to ∼11 µm, high energy resolution (∼11 meV), near-transform-limited temporal resolution (∼280 fs), and tunable 1.55 eV pump fluence up to 3 mJ/cm2, this time-resolved µ-ARPES system enables the measurement of ultrafast electron dynamics in exfoliated and inhomogeneous materials. We demonstrate the performance of our system by correlating the spectral broadening of the topological surface state of Bi2Se3 with the spatial dimension of the probe pulse, as well as resolving the spatial inhomogeneity contribution to the observed spectral broadening. Finally, after in situ exfoliation, we performed time-resolved µ-ARPES on a ∼30 µm flake of transition metal dichalcogenide WTe2, thus demonstrating the ability to access ultrafast electron dynamics with momentum resolution on micro-exfoliated materials.

Serial assessment of somatic and cardiovascular development in patients with single ventricle undergoing Fontan procedure.

BACKGROUND: The palliation of patients with single ventricle (SV) undergoing Fontan procedure led to improved long-term survival but is still limited due to cardiovascular complications. The aim of this study was to describe the somatic and cardiovascular development of Fontan patients until adolescence and to identify determining factors. METHODS: We retrospectively assessed somatic growth, vascular growth of pulmonary arteries, and cardiac growth of the SV and systemic semilunar valve from 0 to 16 years of age using transthoracic echocardiography. The Doppler inflow pattern of the atrioventricular valve was quantified by E-, A-wave and E/A ratio. All data were converted to z-scores and analyzed using linear mixed effect models to identify associations with age at Fontan procedure, gender, and ventricular morphology. RESULTS: 134 patients undergoing Fontan procedure at a median age of 2.4 (IQR 2.12 to 2.8) years were analyzed. A catch-up of somatic growth after Fontan procedure until school age was found, with lower body height and weight z-scores in male patients and patients with systemic right ventricles. An early time of Fontan procedure was favorable for somatic growth, but not for vascular growth. Cardiac development indicated a decrease of SV end-diastolic diameter z-score until adolescence. Despite a trend towards normalization, E-wave and E/A ratio z-scores were diminished over the entire period. CONCLUSIONS: There is a catch-up growth of somatic, vascular and cardiac parameters after Fontan procedure, which in our cohort depends on the time of Fontan procedure, ventricular morphology, and gender. Beside other factors, diastolic function of the SV remains altered.

Association of the serotonin transporter-linked polymorphic region genotype with lower bone mineral density.

The serotonin transporter-linked polymorphic region (5-HTTLPR) of the serotonin transporter gene (SLC6A4) S allele is linked to pathogenesis of depression and slower response to selective serotonin reuptake inhibitors (SSRIs); depression and SSRIs are independently associated with bone loss. We aimed to determine whether 5-HTTLPR was associated with bone loss. This cross-sectional study included psychiatric patients with both 5-HTTLPR analysis and bone mineral density (BMD) assessment (hip and spine Z-scores if age <50 years and T-scores if ⩾50 years). BMD association with 5-HTTLPR was evaluated under models with additive allele effects and dominant S allele effects using linear regression models. Patients were stratified by age (<50 and ⩾50 years) and sex. Of 3016 patients with 5-HTTLPR genotyping, 239 had BMD assessments. Among the younger patients, the S allele was associated with lower Z-scores at the hip (P=0.002, dominant S allele effects; P=0.004, additive allele effects) and spine (P=0.0006, dominant S allele effects; P=0.01, additive allele effects). In sex-stratified analyses, the association of the S allele with lower BMD in the younger patients was also significant in the subset of women (P⩽0.003 for both hip and spine BMD under the additive allele effect model). In the small group of men younger than 50 years, the S allele was marginally associated with higher spine BMD (P=0.05). BMD T-scores were not associated with 5-HTTLPR genotypes in patients 50 years or older. The 5-HTTLPR variants may modify serotonin effects on bone with sex-specific effects.

Metabolic Differences Between Shod and Barefoot Walking in Children.

Footwear affects the biomechanics of children's gait; however, there has been less research addressing the energetics of walking with and without shoes. This study investigated the effects of barefoot and shod walking on metabolic parameters in children. 25 children (9.7±1.4 years) walked at a self-selected pace for 5 min on an instrumented treadmill under 2 footwear conditions (barefoot, running shoe). Vertical oscillations of centre of mass were calculated from ground reaction forces. Expired gases were collected in the last minute of each trial. Paired t-tests revealed significantly higher oxygen consumption (17.6±2.5 ml.kg(-1).min(-1) vs. 16.3±3.1 ml.kg(-1).min(-1)), energy expenditure (3.25±0.86 kcal.min(-1) vs. 2.97±0.68 kcal.min(-1)), and economy (298.2±47.5 ml.kg(-1).km(-1) vs. 275.9±56.9 ml.kg(-1).km(-1)) during the shod condition. There was no difference in substrate utilization between conditions. The barefoot condition elicited a smaller centre of mass vertical displacement (1.24±0.14 cm vs. 1.34±0.17 cm). At a natural walking speed, barefoot walking is more economical than shod walking at the same velocity in children. The higher energy cost of shod walking should be considered when evaluating the use of footwear by children.

Feasibility of investigating differential proteomic expression in depression: implications for biomarker development in mood disorders.

The objective of this study was to determine whether proteomic profiling in serum samples can be utilized in identifying and differentiating mood disorders. A consecutive sample of patients with a confirmed diagnosis of unipolar (UP n=52) or bipolar depression (BP-I n=46, BP-II n=49) and controls (n=141) were recruited. A 7.5-ml blood sample was drawn for proteomic multiplex profiling of 320 proteins utilizing the Myriad RBM Discovery Multi-Analyte Profiling platform. After correcting for multiple testing and adjusting for covariates, growth differentiation factor 15 (GDF-15), hemopexin (HPX), hepsin (HPN), matrix metalloproteinase-7 (MMP-7), retinol-binding protein 4 (RBP-4) and transthyretin (TTR) all showed statistically significant differences among groups. In a series of three post hoc analyses correcting for multiple testing, MMP-7 was significantly different in mood disorder (BP-I+BP-II+UP) vs controls, MMP-7, GDF-15, HPN were significantly different in bipolar cases (BP-I+BP-II) vs controls, and GDF-15, HPX, HPN, RBP-4 and TTR proteins were all significantly different in BP-I vs controls. Good diagnostic accuracy (ROC-AUC⩾0.8) was obtained most notably for GDF-15, RBP-4 and TTR when comparing BP-I vs controls. While based on a small sample not adjusted for medication state, this discovery sample with a conservative method of correction suggests feasibility in using proteomic panels to assist in identifying and distinguishing mood disorders, in particular bipolar I disorder. Replication studies for confirmation, consideration of state vs trait serial assays to delineate proteomic expression of bipolar depression vs previous mania, and utility studies to assess proteomic expression profiling as an advanced decision making tool or companion diagnostic are encouraged.

Reduction of spectral interferences using ultraclean gold nanowire arrays in the LDI-MS analysis of a model peptide.

The surface chemistry of gold nanowires (AuNWs) has been systematically assessed in terms of contamination and cleaning processes. The nanomaterial's surface quality was correlated to its performance in the matrix-free laser desorption ionization mass spectrometry (LDI-MS) analysis of low molecular weight analytes. Arrays of AuNWs were deposited on glass slides by means of the lithographically patterned nanowire electrodeposition technique. AuNWs were then characterized in terms of surface chemical composition and morphology using X-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. AuNWs were subjected to a series of well-known cleaning procedures with the aim of producing the best performing surfaces for the LDI-MS detection of leucine enkephalin, chosen as a model analyte with a molar mass below 1,000 g/mol. Prolonged cyclic voltammetry in 2 M sulfuric acid and, most of all, oxygen plasma cleaning for 5 min provided the best results in terms of simpler (interference-free) and more intense mass spectrometry spectra of the reference compound. The analyte always ionized as the sodiated adduct, and leucine enkephalin limits of detection of 0.5 and 2.5 pmol were estimated for the positive and negative analysis modes, respectively. This study points out the tight correlation existing between the chemical status of the nanostructure surface and the AuNW-assisted LDI-MS performance in terms of reproducibility of spectra, intensity of analyte ions and reduction of interferences.

Hypovitaminosis D in psychogeriatric inpatients.

OBJECTIVES: This study investigated the rate of hypovitaminosis D in psychogeriatric inpatients and explored whether any associations exist between vitamin D levels, cognitive function, and psychiatric diagnoses. DESIGN: Retrospective medical record review from November 2000 through November 2010. SETTING: Geriatric psychiatric ward of an academic tertiary care hospital. PARTICIPANTS: Psychiatric inpatients aged 65 years or older. MEASUREMENTS AND ANALYSIS METHODS: Serum 25-hydroxyvitamin D [25(OH)D] levels were measured at admission. Associations between 25(OH)D levels, Mini-Mental State Examination (MMSE) scores were analyzed using Spearman correlations, and psychiatric diagnoses were analyzed using logistic regression models and Fisher's exact tests. RESULTS: In 141 subjects (mean age, 77.8 years; 86 [61%] female; 135 [96%] white), the most frequent diagnoses were major depressive disorder in 81 patients (57%), dementia in 38 (27%), delirium in 13 (9%), anxiety in 12 (8.5%), and bipolar disorder in 11 (8%). Mean MMSE score was 24±6.4 (range, 3-30). Forty-three subjects (30.4%) had mild to moderate vitamin D deficiency [25(OH)D, 10-24 ng/mL], and 6 (4.2%) had severe deficiency [25(OH)D <10 ng/mL]. CONCLUSIONS: Hypovitaminosis D was common in elderly psychiatric inpatients. No associations were found between vitamin D levels and global cognitive function or psychiatric diagnoses.

The osteoinductive effect of chitosan-collagen composites around pure titanium implant surfaces in rats.

BACKGROUND AND OBJECTIVE: The enhancing effects of chitosan on activation of platelets and differentiation of osteoprogenitor cells have been demonstrated in vitro. The purpose of this study was to evaluate the in vivo osteoinductive effect of chitosan-collagen composites around pure titanium implant surfaces. MATERIAL AND METHODS: Chitosan-collagen composites containing chitosan of different molecular weights (450 and 750 kDa) were wrapped onto titanium implants and embedded into the subcutaneous area on the back of 15 Sprague-Dawley rats. The control consisted of implants wrapped with plain collagen type I membranes. Implants and surrounding tissues were retrieved 6 wks after surgery and identified by Alizarin red and Alcian blue whole mount staining. The newly formed structures in the test groups were further analyzed by Toluidine blue and Masson-Goldner trichrome staining, and immunohistochemical staining with osteopontin and alkaline phosphotase. The bone formation parameters of the new bone in the two test groups were measured and compared. RESULTS: New bone formed ectopically in both chitosan-collagen groups, whereas no bone induction occurred in the negative control group. These newly formed bone-like structures were further confirmed by immunohistochemical staining. Comparison of bone parameters of the newly induced bone revealed no statistically significant differences between the 450 and 750 kDa chitosan-collagen groups. CONCLUSION: Our results demonstrated that chitosan-collagen composites might induce in vivo new bone formation around pure titanium implant surfaces. Different molecular weights of chitosan did not show significantly different effects on the osteoinductive potential of the test materials.

Synthesis of PbTe nanowire arrays using lithographically patterned nanowire electrodeposition.

We describe the preparation by electrodeposition of arrays of lead telluride (PbTe) nanowires using the lithographically patterned nanowire electrodeposition (LPNE) method. PbTe nanowires had a rectangular cross-section with adjustable width and height ranging between 60-400 nm (w) and 20-100 nm (h). The characterization of these nanowire arrays using X-ray diffraction, transmission electron microscopy and electron diffraction, scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy (XPS) is reported. PbTe nanowires were electrodeposited using a cyclic electrodeposition-stripping technique that produced polycrystalline, stoichiometric, face-centered cubic PbTe with a mean grain diameter of 10-20 nm. These nanowires were more than 1 mm in length and two additional processing steps permitted their suspension across 25 microm air gaps microfabricated on these surfaces. The LPNE synthesis of lithographically patterned PbTe nanowires was carried out in unfiltered laboratory air. Nanowires with lengths of 70-100 microm showed an electrical resistivity comparable to bulk PbTe. XPS reveals that exposure of PbTe nanowires to air causes the formation on the nanowire surface of approximately one monolayer of a mixed lead oxide and tellurium oxide within a few minutes.

Epidermoid cysts associated with thoracic meningocele.

Intraspinal tumours of cutaneous origin associated with various spinal dysraphisms have been well documented in the literature. However, the metachronous development of intra- and extra-medullary tumours in conjunction with dorsal meningocele is rare. The authors report a patient with a thoracic dorsal meningocele and congenital intradural extramedullary epidermoid tumour. The patient developed an intramedullary epidermoid growth 12 years later. Subtotal resection of the tumour predisposed to a later recurrence. Meningocele is not always an isolated clinical entity but the concurrent occult lesions are usually veiled by the more conspicuous surface anomaly. Thorough magnetic resonance imaging of the whole neural axis helps to identify associated pathologies. Delicate intradural exploration by a microsurgical approach is necessary to achieve appropriate treatment.

Genetic and antigenic analyses of enterovirus 71 isolates in Taiwan during 1998-2005.

Enterovirus 71 (EV71) infections can lead to devastating clinical outcomes in children, with an increasing number of severe cases worldwide. The genetic and antigenic variability of EV71 strains isolated in Taiwan in 1998-2005 was evaluated using partial nucleotide sequence analysis of the VP1 gene and the neutralisation assay. Phylogenetic analyses revealed that most EV71 isolates from the 1998 epidemic belonged to sub-genogroup C2, with a minority belonging to sub-genogroup B4. Between 1999 and 2003, isolates belonging to sub-genogroup B4 predominated, followed by a change to sub-genogroup C4 in 2004 and 2005. Antibodies raised in rabbits or collected from infected patients were able to neutralise EV71 virus stocks at high dilutions, regardless of the sub-genogroup of the virus being challenged. The presence of phylogenetically distinct yet antigenically similar populations of EV71 in Taiwan is of concern in the context of herd immunity and vaccine development.

Isolation of polyhydroxyalkanoates-producing bacteria using a combination of phenotypic and genotypic approach.

AIMS: To develop an efficient approach using a combination of phenotypic and genotypic methods for isolation of environmental bacteria that produce mid-chain-length polyhydroxyalkanoates (mcl-PHAs). METHODS AND RESULTS: A viable-colony staining method using Nile red was used to screen for PHA-producing bacteria followed by a polymerase chain reaction (PCR) screen using primers to amplify the partial nucleic acid sequence of the phaC1 synthase gene for confirmation. Microbes containing lipophilic storage compounds isolated from environmental samples could readily be detected by the colony staining method. They were further examined by Sudan Black staining to highlight the inclusions inside the cells. These isolates were subsequently subjected to PCR analysis. As a result, more than a hundred strains were identified as PHA-positive isolates from this screening approach. CONCLUSIONS: These results conclusively demonstrate that environmental bacterial strains able to accumulate the PHAs could readily be obtained by this screening method. SIGNIFICANCE AND IMPACT OF THE STUDY: We propose a polyphasic approach using a combination of phenotypic and genotypic screening method to rapidly screen and identify bacteria able to produce significant amounts of mcl-PHAs from environment. This approach can be adopted as a rapid screen for micro-organisms able to accumulate PHAs to be used for potential manufacture and other industrial applications.

Aortic dissection in an accident and emergency department in Hong Kong.

OBJECTIVES: To compare the clinical characteristics of aortic dissection in Hong Kong with the International Registry of Aortic Dissection, and to evaluate the sensitivity of the Accident and Emergency Department in diagnosing aortic dissection and its role in aortic dissection management. DESIGN: Retrospective observational study. SETTING: Regional public hospital, Hong Kong. PATIENTS: Newly diagnosed aortic dissection patients attending the Accident and Emergency Department from 2002 to 2005 inclusive. MAIN OUTCOME MEASURES: Correct diagnosis in Accident and Emergency Department, tertiary unit transfer, and in-patient mortality. RESULTS: Twenty-eight patients were found to have aortic dissection, with an estimated annual incidence of 2.1 per 100,000 inhabitants. The sensitivity of Accident and Emergency Department in diagnosing aortic dissection was 54%; 11% of the patients were diagnosed at postmortem examination. Compared to the International Registry of Aortic Dissection, the patients in this Tseung Kwan O Hospital study had less abrupt and less severe pain, less chest pain, and a lower proportion were operated on. Higher mortality was associated with age 70 years or older (odds ratio=6.4), female gender (21.0), known hypertension (3.8), systolic blood pressure below 100 mm Hg (6.0), aortic dissection not diagnosed in the Accident and Emergency Department (3.2), and the patient not reaching tertiary unit (33.8). The hourly cumulative mortality rate was 1.32%. The group of aortic dissections diagnosed in the Accident and Emergency Department had 55.1% more transfer to tertiary unit (95% confidence interval, 14.4-79.1%; P=0.006), 84.5 hours less transfer time (95.3-263.6 hours; P=0.232), and 27.2% lower mortality (12.6-58.6%; P=0.246). The yield rate of contrast computed tomography of thorax was 43%. CONCLUSIONS: Diagnosing aortic dissection in the Accident and Emergency Department enabled optimal disposition and lower in-patient mortality.

The effectiveness of thymectomy on seronegative generalized myasthenia gravis: comparing with seropositive cases.

OBJECTIVES: To investigate the efficacy of thymectomy between patients with seronegative myasthenia gravis (SNMG) and seropositive myasthenia gravis (SPMG). METHODS: We present here the first Taiwanese retrospective paired cohort study comparing the effectiveness of thymectomy among 16 seronegative and 32 seropositive MG patients after matching for age-of-onset and time-to-thymectomy, and following up over a mean of 35 +/- 20 (7-86) months. Clinical characteristics and complete stable remission (CSR) rates were compared and analyzed between the groups. RESULTS: There were no major clinical differences between the two groups except for our finding of a lower percentage of SNMG receiving preoperative plasmapheresis or human immunoglobulin than SPMG (31% for SNMG vs 72% for SPMG, P = 0.007). CSR rates calculated using the Kaplan-Meier method were similar in the two groups (38% for SNMG vs 50% for SPMG, P = 0.709). The median time for CSR was 47.4 months for SNMG and 48.2 months for SPMG. Thymic hyperplasia were the most common pathology (69% for SNMG vs 88% for SPMG, P = 0.24). During the follow-up period, we found no group difference on prednisolone or pyridostigmine dosages. Significant postoperative dosage reductions on pyridostigmine, but not on prednisolone, were found in both groups. CONCLUSIONS: Thymectomy has a comparable response among SNMG and SPMG in our study. Thymic hyperplasia is prevalent in our SNMG patients and thymectomy may also be a therapeutic option to increase the probability of remission or improvement in SNMG. More prospective controlled trial will be helpful in the future.

Elephantiasis neuromatosa in neurofibromatis type I. MRI findings with review of the literature.

We report the case of a patient with NF-1 who presented with gross elephantiasis neuromatosa of her right leg. Prior to plastic surgery, Magnetic Resonance Imaging and Angiography (MRI and MRA) were performed to provide a detailed assessment of the extension as well as the vascular and muscular involvement of the neurofibroma.

Multi-metric and multi-substructure biclustering analysis for gene expression data.

A good number of biclustering algorithms have been proposed for grouping gene expression data. Many of them have adopted matrix norms to define the similarity score of a bicluster. We shall show that almost all matrix metrics can be converted into vector norms while preserving the rank equivalence. Vector norms provide a much more efficient vehicle for biclustering analysis and computation. The advantages are two folds: ease of analysis and saving of computation. Most existing biclustering algorithms have also implicitly assumed the use of univariate (i.e., single metric) evaluation for identifying biclusters. Such an approach however overlooks the fundamental principle that genes (even though they may belong to the same gene group) (1) may be subdivided into different substructures; and (2) they may be co-expressed via a diversity of coherence models (a gene may participate in multiple pathways that may or may not be co-active under all conditions). The former leads to the adoption of a multi-substurcture analysis, while the latter to the multivariate analysis. This paper will show that the proposed multivariate and multi-subscluster analysis is very effective in identifying and classifying biologically relevant groups in genes and conditions. For example, it has successfully yielded highly discriminant and accurate classification based on known ribosomal gene groups.

Synthesis and characterization of taper- and rodlike si nanowires on Si(x)Ge(1-x) substrate.

Taper- and rodlike Si nanowires (SiNWs) are synthesized successfully on Si and Si(0.8)Ge(0.2) substrates. The growth mechanisms of taper- and rodlike SiNWs are proposed to be oxide-assisted growth (OAG) and vapor-liquid-solid (VLS) growth, respectively. For taperlike SiNWs annealed at 1200 degrees C for 3 h, the emission peaks are found at 772, 478, and 413 nm. On the other hand, for rodlike SiNWs annealed at 1200 degrees C for 4 h, emission peaks are found at 783, 516, and 413 nm. From the field-emission measurements, the taperlike Si nanowires exhibit superior field-emission behavior with a turn-on field of 6.3-7.3 V/mum. The field enhancement, beta, has been estimated to be 700 and 1000 at low and high fields, respectively. The excellent field-emission characteristics are attributed to the perfect crystalline structure and the taperlike geometry of the Si nanowires.