α-Fe2O3 nanotubes-reduced graphene oxide composites as synergistic electrochemical capacitor materials

We present a facile approach for the fabrication of a nanocomposite comprising α-Fe(2)O(3) nanotubes (NTs) anchored on reduced graphene oxide (rGO) for electrochemical capacitors (ECs). The hollow tubular structure of the α-Fe(2)O(3) NTs presents a high surface area for reaction, while the incorporation of rGO provides an efficient two-dimensional conductive pathway to allow fast, reversible redox reaction. As a result, the nanocomposite materials exhibit a specific capacitance which is remarkably higher (~7 times) than α-Fe(2)O(3) NTs alone. In addition, the nanocomposites show excellent cycling life and large negative potential window. These findings suggest that such nanocomposites are a promising candidate as negative electrodes in asymmetrical capacitors with neutral electrolytes.

Tracking hydrogen/deuterium exchange at glycan sites in glycoproteins by mass spectrometry

Hydrogen/deuterium exchange coupled to mass spectrometry (HDX-MS) has emerged as a technique for studying glycoproteins, which are often refractory to classical methods. Glycan chains are generally assumed to exchange protons very rapidly, making them invisible to this technique. Here, we show that under conditions commonly used for HDX-MS, acetamido groups within glycan chains retain a significant amount of deuterium. Using mono- and polysaccharide standards along with glycopeptides from a panel of glycoproteins, we demonstrate that N-acetyl hexosamines, along with modified Asn side chains, are responsible for this effect. Model compounds for sialic acid also displayed similar exchange kinetics, but terminal sialic acids in the context of an entire glycan chain did not contribute to deuterium retention. Furthermore, the presence of sialic acid appears to enhance the exchange rate of the nearby N-acetyl glucosamines. The ability to detect deuterium exchange at the glycan level opens the possibility of applying HDX-MS to monitor glycan interactions and dynamics.

Development of polymer lab-on-a-chip (LOC) for oxidation-reduction potential (ORP) measurement

Reverse osmosis (RO) desalination has been recognized as a promising method to solve the water shortage problem. Nevertheless, since it is energy intensive and has many problems associated with biofouling/fouling of RO membranes in RO plants, its commercial acceptance is still slow. Especially, as high levels of oxidizing agents negatively affect RO membrane efficiency and life span. So, there is a need to develop sensitive, selective, portable and rapid methods to determine oxidation-reduction potential (ORP) in feed solution. For developing a polymer ORP lab-on-a-chip (LOC), a microchannel patterned on a polymer substrate was successfully filled with 800 nm diameter silica beads using self-assembly bead packing technology. The measured ORPs using the three kinds of redox potential solutions were typically slightly lower than those of the nominal redox potential. But, all of the measurements should be deemed acceptable. The ORP LOC has also a much shorter response time than the conventional potentiometric sensor.

High rate of increased carotid intima-media thickness and atherosclerotic plaques in Chinese asymptomatic subjects with central obesity

Both central obesity and increased carotid intima-media thickness (IMT) are markers of atherosclerosis and associated with cardiovascular diseases (CVD). Information of IMT in Chinese subjects with central obesity is limited. This study was performed to assess the rate of atherosclerosis and abnormal IMT in asymptomatic Chinese subjects with central obesity, and to investigate the association between IMT values and CVD risk factors including hypertension, hyperglycaemia and dyslipidaemia. We studied 122 centrally obese adults who had good past health. IMT measurements on carotid arteries were performed and fasting blood taken for plasma glucose and lipid profiles. Abnormal IMT was defined as > 0.9 mm. Atherosclerosis was defined as the presence of one or more visible plague. Of the 122 subjects, the mean (±SD) age was 59.4 ± 5.8 years (median [range]: 59.0 [45-75] years). The median IMT value was 0.70 mm (range: 0.53-1.19 mm) [men vs. women: 0.74 mm vs. 0.66 mm, P-value: < 0.001]. IMT values and the rate of atherosclerosis increased with age and the number of CVD risk factors (P-value for trend: < 0.05). Using binary logistic regression to predict the presence of atherosclerosis with the presence of abnormal IMT, age, gender, and other CVD risk factors as independent variables, age (OR [95% CI] = 1.13 [1.03, 1.23], P = 0.009) and abnormal IMT (OR [95% CI] = 4.05 [1.09, 15.03], P = 0.037) were independently associated with atherosclerosis. In conclusion, among Hong Kong Chinese asymptomatic subjects with central obesity, there was a high rate of CVD risk factors. We found that 19% of these subjects had carotid atherosclerotic plaques and 10% of them had abnormal IMT (>0.9 mm). Carotid IMT study may serve as an appropriate screening tool to diagnose atherosclerosis in the centrally obese middle-aged population.

Problems of the acetylene reduction technique applied to water-saturated paddy soils

The acetylene reduction assay for the measurement of N(2) fixation in a water-saturated paddy soil is limited by the slow diffusion of acetylene and ethylene. In laboratory incubation tests, vigorous shaking after the assay period is needed to release ethylene into the gas within the assay vials. Shaking prior to the incubation is also effective for dissolving acetylene in the water-saturated soil. However, a water-saturated soil depth of less than 10 mm during incubation is recommended. In field assays, some amounts of ethylene remain in the water-saturated soil phase of the acetylene reduction assay chamber, but stirring the water-saturated soil before sampling reduces the amount of ethylene remaining in soil. Evidence of a downward movement of acetylene and an upward movement of ethylene through rice plants was obtained. Because of the rapid transfer of acetylene to rice plant roots, an in situ acetylene reduction assay covering a rice hill is likely to detect nitrogen fixation in the proximity of roots where acetylene is easily accessible. Acetylene introduction to the water-saturated soil phase prior to assay did not greatly increase the acetylene reduction rate. Carbon dioxide enrichment in the assay chamber did not enhance nitrogen fixation in a paddy including rice and algae during a 1-day cycle.

[18F] fluorodeoxyglucose-positron-emission tomography and MR imaging coregistration for presurgical evaluation of medically refractory epilepsy

Epilepsy is a chronic disorder affecting approximately 1% of the population of the world. Approximately one third of patients with epilepsy remain refractory to medical therapy. For these patients, surgery is a curative option. In order for surgery to be considered, precise localization of the structural abnormality is needed. When MR imaging findings are normal, more sensitive techniques such as positron-emission tomography (PET) can help find the abnormality. Combining MR imaging and PET information increases the sensitivity of the presurgical evaluation. In this review, we discuss the clinical applications of coregistration of [(18)F] fluorodeoxyglucose (FDG)-PET with MR imaging for medically refractory epilepsy. Because FDG-PET/MR imaging coregistration has been a routine component of the presurgical evaluation for patients with epilepsy at our institution since 2004, we also included cases from our data base that exemplify the utility of this technology to obtain better postsurgical outcomes.

Surgical techniques according to anatomic variations in living donor liver transplantation using the right lobe

OBJECTIVES

In living donor liver transplantation, the right lobe has many anatomic variations in the vascular tree, which could lead to surgical complications. We need to define surgical technique according to anatomy.

METHODS

From January 2000 to September 2007, 310 living donor liver transplantations using the right lobe were performed in patients with end-stage liver disease. The vascular trees were evaluated preoperatively with computed tomography and magnetic resonance angiography. We classified anatomic points for safe harvest in the hepatic artery, portal vein, and hepatic vein and described technical points based on anatomic variations.

RESULT

There were many anatomic variations in the hepatic vasculature. Hepatic artery variations were observed in 16.8% of cases. Double hepatic artery was observed in 14 cases (4.5%). Of these 14 cases, reconstruction as a single artery was performed in 6 and dual reconstruction was performed in 8 cases. Portal vein variation was observed in 45 cases (14.5%): Dual anastomosis to right and left portal vein was performed in type III (n = 20; 6.4%) and type IV (n = 3; 1.0%) variations. There were 70 cases of portal vein thrombosis. In 8 of the 70, a jump or interposition graft with iliac vein was utilized. Of the middle hepatic vein variant, segment V vein only was reconstructed in 188 (60.6%) cases. In 21 (6.8%) cases, segment VIII vein only was reconstructed, and in 43 (13.9%) cases, both segment V and segment VIII veins were reconstructed using the recipient's portal vein, a cryopreserved iliac vein, or a prosthetic graft. The most common variation of right inferior hepatic vein was type II (n = 141; 45.5%), which has 1 right inferior hepatic vein.

CONCLUSION

Living donor liver transplantation using the right lobe can be performed safely, but there is a potential operative risk because of various anatomic variations. To minimize operative complications, anatomic variations should be kept in mind to ensure a safe and successful operation.

[Cloning of rat TARC cDNA and analysis of tissue-specific mRNA expression]

Thymus and activation-regulated chemokine (TARC) is one that selectively controls the migration of type 2-helper T lymphocytes into inflammatory lesions. TARC is a CC chemokine, and plays an essential role in recruiting CC chemokine receptor 4-positive Th2 cells to allergic lesions. We cloned TARC cDNA from rat thymus using RT-PCR. The rat TARC clone contained a full-length open reading frame encoding 93 amino acids that showed 83% and 66% homology with mouse and human homologs, respectively. The expression of TARC mRNA was mainly in the lymphoid organs, for example, the thymus, spleen, and lymph node. The recombinant TARC was expressed in Escherichia coli and purified in an active form. In addition, the purified rat TARC with S-tagged specifically binds to human CCR4 in CD4.CCR4-transfected HOS cells by Cell-binding assay using flow-cytometry. The TARC cDNA clones obtained in this study will be valuable for future studies on allergic diseases in rats.

Barbiturate therapy for patients with refractory intracranial hypertension following severe traumatic brain injury: its effects on tissue oxygenation, brain temperature and autoregulation

The aim of this study was to explore the effects of barbiturate coma on cerebral tissue oxygen tension and cerebrovascular pressure reactivity (PRx), as an index of cerebral autoregulation in severe head injury patients. This was a prospective observational clinical study of 12 patients with severe traumatic brain injury, carried out at a tertiary-level neurosurgical intensive care unit between April 2002 and May 2005. All patients received standard neurosurgical intensive care and monitoring. Probes for intracranial pressure (ICP), brain temperature (BT) and brain tissue oxygenation (PTiO2) were inserted into (noncontused) normal-looking white matter. Cerebrovascular PRx was measured as a moving correlation between ICP and arterial blood pressure. Barbiturate coma was instituted when ICP became refractory (ICP>20 mmHg). All data from the multimodal monitoring were digitally extracted and statistically analysed. The mean ICP decreased with barbiturate coma in eight of the 12 patients (75% of the patients), but only four achieved a value below 20 mmHg. Of eight patients with prebarbiturate PTiO2 levels above 10 mmHg, six had a further improvement in oxygenation. Thus, concordant favourable changes in ICP, PRx and PTiO2 with barbiturate coma were seen in those who survived. Effective response to barbiturates can be detected by improved PTiO2 and autoregulation (PRx) in severe head injury patients.

Temporal changes in cerebral tissue oxygenation with cerebrovascular pressure reactivity in severe traumatic brain injury

OBJECTIVE

To investigate the temporal relationship between cerebrovascular pressure reactivity and brain tissue oxygenation in patients with severe head injury.

METHODS

In 40 patients, brain tissue oxygenation and intracranial pressure were monitored. Time-averaged values for intracranial pressure (ICP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP) and brain tissue oxygenation (PtiO2) were computed. The pressure reactivity index (PRx) was calculated. The mean values of the variables were obtained at the 6-h and 72-h post-injury time points, and the difference between the two time points for each of the variables was denoted as delta (delta).

RESULTS

Of the 40 patients, 32 were survivors and 8 were non-survivors. Statistically significant differences were present between these two groups with regard to deltaMAP (p = 0.013), ICP at 6 h (p = 0.027), CPP at 72 h (p = 0.018), deltaCPP (p = 0.033), PRx at 6 h (p = 0.029), PRx at 72 h (p = 0.002), PtiO2 at 72 h (p < 0.0005) and deltaPtiO2 (p = 0.023) values, reflecting an improvement with time in survivors and a deterioration with time in non-survivors. In non-survivors, the magnitude of change in PtiO2 and CPP with time correlated in a negative linear fashion (p = 0.042 and 0.029, respectively) with the change in PRx with time, whereas no such relationship was seen in survivors.

CONCLUSION

The severity of brain tissue oxygenation derangement correlates with increasing cerebrovascular dysautoregulation in patients succumbing to severe head injury, supporting the utility of PRx as a monitoring variable and the rationale for a target-driven approach to head injury management.

Domenico solution--is it valid?

The Domenico solution is widely used in several analytical models for simulating ground water contaminant transport scenarios. Unfortunately, many textbook as well as journal article treatments of this approximate solution are full of empirical statements that are developed without mathematical rigor. For this reason, a rigorous analysis of this solution is warranted. In this article, we present a mathematical method to derive the Domenico solution and explore its limits. Our analysis shows that the Domenico solution is a true analytical solution when the value of longitudinal dispersivity is zero. For nonzero longitudinal dispersivity values, the Domenico solution will introduce a finite amount of error. We use an example problem to quantify the nature of this error and suggest some general guidelines for the appropriate use of this solution.

Menstruation among adolescent girls in Malaysia: a cross-sectional school survey

INTRODUCTION

The onset of menstruation is part of the maturation process. However, variability in menstrual cycle characteristics and menstrual disorders are common. The purpose of this study was to determine the menstrual characteristics of adolescent females and factors associated with it.

METHODS

This is a cross-sectional descriptive study carried out on 2,411 secondary school adolescent females in Negeri Sembilan, Malaysia. Data were collected using a self-administered structured questionnaire on menstruation in Bahasa Malaysia.

RESULTS

Abnormal cycle length (menstrual cycle longer than 35 days or cycle length between 14 to 20 days or irregular pattern) was common and affected 37.2 percent of subjects. The majority (74.6 percent) experienced premenstrual syndrome and 69.4 percent had dysmenorrhoea. About 18 percent reported excessive menstrual loss (use two pads at a time to prevent blood from soaking through or confirmed by doctor to be anaemic due to heavy menstrual flow). Only 11.1 percent of schoolgirls seeked medical consultation for their menstrual disorders. Mothers remained the most important source of information (80 percent). Menstrual disorders were significantly more common in female adolescents who smoke and have suicidal behaviours (p-value is less than 0.05).

CONCLUSION

Menstrual problems among adolescent female are common. They are influenced by certain modifiable factors.

Premarital sexual intercourse among adolescents in Malaysia: a cross-sectional Malaysian school survey

INTRODUCTION

Sexual intercourse among Malaysian adolescents is a major concern, especially with the worry of HIV/AIDS. This study was done to determine the prevalence of sexual intercourse among secondary school students aged 12 to 19 years in Negeri Sembilan, Malaysia.

METHODS

This is a cross-sectional school survey conducted on 4,500 adolescent students based on a structured questionnaire. Data were collected using the self-administered questionnaire (translated version of the Youth Risk Behaviour Surveillance in Bahasa Malaysia).

RESULTS

The study showed that 5.4 percent of the total sample were reported to have had sexual intercourse. The proportion among male students who had had sex was higher (8.3 percent) compared with female students (2.9 percent). The mean age at first sexual intercourse was 15 years. One percent of students reported that they had been pregnant or had made someone else pregnant. Adolescent sexual intercourse was significantly associated with (1) socio-demographical factors (age, gender); (2) environmental factors (staying with parents); and (3) substance use (alcohol use, cigarette smoking, drug use), even after adjustment for demographical factors. The survey showed that 20.8 percent of respondents had taken alcohol, 14.0 percent had smoked cigarettes, 2.5 percent had tried marijuana, 1.2 percent had tried ecstasy pills, 2.6 percent had tried glue sniffing, 0.7 percent had tried heroin, and 0.7 percent had intravenous drugs.

CONCLUSION

Prevalence of sexual intercourse among Malaysian adolescents was relatively low compared to developed countries. However, certain groups of adolescents tend to be at higher risk of engaging in sexual intercourse. This problem should be addressed early by targeting these groups of high-risk adolescents.

Demographical profiles of adult severe traumatic brain injury patients: implications for healthcare planning

INTRODUCTION

In Singapore, severe traumatic brain injury (TBI) continues to be a major public health problem and devastating condition, with significant mortality and morbidity. By understanding the incidence, prevalence and implications of severe TBI in Singapore, strategic plans to meet the unique needs of these patients in the local context may be developed.

METHODS

The demographical profiles of the adult severe TBI patients in Singapore were studied in this retrospective review of 528 patients admitted to the National Neuroscience Institute (NNI) from January 1999 to December 2003.

RESULTS

There were 420 male and 108 female patients, age ranging from 15 to 96 years old, with a mean and standard deviation (SD) of 44.6 +/- 19.9 years, admitted to NNI during the study period. Motor vehicle and fall-related accidents were the leading causes of severe TBI. Three high-risk groups identified were young adults, elderly, and foreign workers.

CONCLUSION

Preventive measures targeting at these high-risk groups are important to reduce the incidence of severe TBI.

Effects of Qi therapy (external Qigong) on symptoms of advanced cancer: a single case study

The aim of this study was to examine the effectiveness of Qi therapy (external Qigong) in the management of symptoms of advanced cancer in a man. We used a single case study design to evaluate the effectiveness of Qi therapy (external Qigong) in a 35-year-old man with advanced cancer (Stage IV) involving metastases in the stomach, lung and bone (Karnofsky performance scale: KPS, 40: requires special care and assistance, disabled). Treatment involved six days of pre-assessment, eight treatment sessions on alternate days over 16 days, and a two-week follow-up phase. A visual analogue scale (VAS) was used to assess the patient's self-reported symptoms of cancer over the intervention and follow-up periods. Following treatment, VAS scores' analysis revealed beneficial effects on pain, vomiting, dyspnoea, fatigue, anorexia, insomnia, daily activity and psychological calmness. These improvements were maintained over the two-week follow-up phase. After the first Qi therapy session, the patient discontinued medication and could sit by himself; after the fourth session, the patient was able to walk and use the toilet without assistance (improvement in KPS: 70: care for self, unable to perform normal activity or to do active work). Although limited by the single case study approach, our results support previous studies on this topic and provide reasons to conduct controlled clinical trials.

Proteomic analysis of chromatin-modifying complexes in Saccharomyces cerevisiae identifies novel subunits

Epigenetics is the alteration of phenotype without affecting the genotype. An underlying molecular mechanism of epigenetics is the changes of chromatin structure by covalent histone modifications and nucleosome reorganization. In the yeast, Saccharomyces cerevisiae, two of the most well-studied macromolecular complexes that perform these epigenetic changes are the ATP-dependent Swi/Snf chromatin-remodelling complex and the SAGA histone acetyltransferase complex. To understand fully the mechanism by which these large protein complexes perform their functions in the cell, it is crucial that all the subunits of these complexes are identified. In an attempt to identify new subunits associated with SAGA and Swi/Snf, we used tandem affinity purification, followed by a multidimensional protein identification technology to analyse the subunit composition. Our analysis identified two novel proteins, one associated with SAGA, YPL047W (Sgf11), and another associated with Swi/Snf, Rtt102.

Brain tissue oxygenation monitoring in acute brain injury

Cerebral ischemia is one of the most important causes of secondary insults following acute brain injury. While intracranial pressure monitoring in the intensive care unit constitutes the cornerstone of neurocritical care monitoring, it does not reflect the state of oxygenation of the injured brain. The holy grail of neuromonitoring is a modality that would reflect accurately real time the status of oxygenation in the tissue of interest, is robust, artefact free and that which provides information that can be used for therapeutic interventions and to improve outcome. Such a device could conceivably be used to augment the sensitivity of current multi-modality monitoring systems in the neurocritical management of brain injured patients. This article examines the availability of data in the literature to support clinical use of local tissue oxygen probes in intensive care.

Effects of laminectomy and facetectomy on the stability of the lumbar motion segment

A ligamentous, nonlinear, sliding contact, three-dimensional finite element (FE) model of L2-L3 complex was developed to investigate the biomechanical effect of laminectomy with and without facetectomy. The L2-L3 FE model was validated against experimental study under various physiological loadings and found to match well with the experimental data. Four iatrogenic models (unilateral laminectomy, unilateral laminectomy with unilateral facetectomy, unilateral laminectomy with bilateral facetectomy and total bilateral laminectomy) were evaluated under flexion, extension, torsion, lateral bending, anterior and posterior shear load vectors to determine alterations in kinematics and annulus stress. Results show that total laminectomy with facetectomy induces considerable increase in motion and annulus stress, except for lateral bending, whereas unilateral laminectomy shows the least increases.

Poroelastic Analysis of Lumbar Spinal Stability in Combined Compression and Anterior Shear

OBJECTIVE

A three-dimensional poroelastic finite element (FE) L2-L3 model was developed to study lumbar spinal instability and intrinsic parameters in the intervertebral disc (IVD).

METHODS

The FE model took into consideration poroelasticity of the IVD and viscoelasticity of the annulus fibers and ligaments to predict the time-dependent behavior. To simulate a holding task, the motion segment was subjected to a combined loading of constant compressive load (1600 N) and anterior shear (200 N) for 2 hours, and the role of facet joints and ligaments in the biomechanical response was investigated by removal of unilateral/bilateral facets, posterior ligaments (supraspinous and interspinous), and facets and ligaments.

RESULTS

The results show the stabilizing role of the facets and ligaments in resisting anterior shear and sagittal rotation under combined loading over time. The main pathway of fluid movement was found to permeate through the central region of the endplate, and the fluid diffusion occurred earlier at the posterior nucleus than the anterior nucleus. The fluid loss from the nucleus dictated the time-dependent motion under the sustained loading, whereas the intrinsic properties of ligaments/annulus fibers played a role only in the early stage of the loading.

CONCLUSION

The predicted results using poroelastic elements provide new insight into the IVD in providing the spinal stiffness under combined loading.

Finite-Element Analysis for Lumbar Interbody Fusion Under Axial Loading

A parametric study was conducted to evaluate axial stiffness of the interbody fusion, compressive stress, and bulging in the endplate due to changes in the spacer position with/without fusion bone using an anatomically accurate and validated L2-L3 finite-element model exercised under physiological axial compression. The results show that the spacer plays an important role in initial stability for fusion, and high compressive force is predicted at the ventral endplate for the models with the spacer and fusion bone together. By varying the positioning of the spacer anteriorly along anteroposterior axis, no significant change in terms of axial stiffness, compressive stress, and bulging of the endplate are predicted for the implant model. The findings suggest that varying the spacer position in surgical situations does not affect the mechanical behavior of the lumbar spine after interbody fusion.

The Biomechanics of Lumbar Graded Facetectomy Under Anterior-Shear Load

In this paper, an anatomically accurate three-dimensional finite-element (FE) model of the human lumbar spine (L2-L3) was used to study the biomechanical effects of graded bilateral and unilateral facetectomies of L3 under anterior shear. The intact L2-L3 FE model was validated under compression, tension, and shear loading and the predicted responses matched well with experimental data. The gross external (translational and coupled) responses, flexibilities, and facet load were delineated for these iatrogenic changes. Results indicted that unilateral facetectomy of greater than 75% and bilateral facetectomy of 75% or more resection markedly alter the translational displacement and flexibilities of the motion segment. This study suggests that fixation or fusion to restore strength and stability of the lumbar spine may be required for surgical intervention of greater than 75% facetectomy.