Nano-structure fabrication of GaAs using AFM tip-induced local oxidation method: different doping types and plane orientations

In this study, we have fabricated nano-scaled oxide structures on GaAs substrates that are doped in different conductivity types of p- and n-types and plane orientations of GaAs(100) and GaAs(711), respectively, using an atomic force microscopy (AFM) tip-induced local oxidation method. The AFM-induced GaAs oxide patterns were obtained by varying applied bias from approximately 5 V to approximately 15 V and the tip loading forces from 60 to 180 nN. During the local oxidation, the humidity and the tip scan speed are fixed to approximately 45% and approximately 6.3 μm/s, respectively. The local oxidation rate is further improved in p-type GaAs compared to n-type GaAs substrates whereas the rate is enhanced in GaAs(100) compared to and GaAs(711), respectively, under the identical conditions. In addition, the oxide formation mechanisms in different doping types and plane orientations were investigated and compared with two-dimensional simulation results

Metal work-function-dependent barrier height of Ni contacts with metal-embedded nanoparticles to 4H-SiC

Metal, typically gold [Au], nanoparticles [NPs] embedded in a capping metal contact layer onto silicon carbide [SiC] are considered to have practical applications in changing the barrier height of the original contacts. Here, we demonstrate the use of silver [Ag] NPs to effectively lower the barrier height of the electrical contacts to 4H-SiC. It has been shown that the barrier height of the fabricated SiC diode structures (Ni with embedded Ag-NPs) has significantly reduced by 0.11 eV and 0.18 eV with respect to the samples with Au-NPs and the reference samples, respectively. The experimental results have also been compared with both an analytic model based on Tung's theory and physics-based two-dimensional numerical simulations

FK228 Analogues Induce Fetal Hemoglobin in Human Erythroid Progenitors

Fetal hemoglobin (HbF) improves the clinical severity of sickle cell disease (SCD), therefore, research to identify HbF-inducing agents for treatment purposes is desirable. The focus of our study is to investigate the ability of FK228 analogues to induce HbF using a novel KU812 dual-luciferase reporter system. Molecular modeling studies showed that the structure of twenty FK228 analogues with isosteric substitutions did not disturb the global structure of the molecule. Using the dual-luciferase system, a subgroup of FK228 analogues was shown to be inducers of HbF at nanomolar concentrations. To determine the physiological relevance of these compounds, studies in primary erythroid progenitors confirmed that JMA26 and JMA33 activated HbF synthesis at levels comparable to FK228 with low cellular toxicity. These data support our lead compounds as potential therapeutic agents for further development in the treatment of SCD

The Possible Role of Nitric Oxide on Enteric Nerves-Mediated Relaxation of the Gastric Smooth Muscle of the Guinea Pig

The influence of the enteric nerves stimulation on the contractility of gastric circular muscle was studied in guinea pig stomachs. The enteric nerves were activated by electric field stimulation(EFS; 90 V, 1 rns, 32 Hz square pulses for 1 s), EFS produced initial transient contraction followed by relaxation and slow recovery. The initial contraction was sensitively blocked by treatment with atropine. The following relaxation still occurred in nonadrenergic noncholinergidNANC) state. EFSinduced relaxation was reduced by LG-nitro-L-arginine(L-NNA), a nitric oxide(NO) synthase inhibitor. The relaxation was restored from the suppressed state after the application of L-arginine(L-arg), a substrate of nitric oxide synthase. With conventional intracellular recording, slow wave and inhibitory junction potential(IJP) were recorded. L-NNA had no effect on IJP, while apamin blocked it. In conclusion, it is suggested that NO may playa major role in EFS-induced relaxation. The exact mechanism of this relaxation is unknown, but the relaxation does not result from the IJP induced by the activation of apamin-sensitive potassium channels

Identification of a Novel Mutation of CFTR Gene in a Korean Patient with Cystic Fibrosis

Cystic fibrosis (CF) is the most common lethal autosomal recessive disease in Caucasians, but rare in Asians. The mutations of cystic fibrosis transmembrane conductance regulator (CFTR) gene are responsible for CF. To date, less than 5 cases of CF have been reported and a few of them diagnosed based on the genotype of the CFTR gene in Korea. We encountered a 4-month-old Korean infant with CF and the diagnosis was confirmed by CFTR gene mutation analysis. The patient underwent surgical operation, due to meconium ileus at birth. He suffered by recurrent respiratory infections, failure to thrive, fatty liver with hepatomegaly, and cholestasis. The mutations of the CFTR gene were identified in the patient and his parents. The patient was a compound heterozygote with a nonsense mutation of c.263T>G, resulting in an amino acid change of p.Leu88X in exon 3. It was previously described in a Korean patient with CF. The other is a novel mutation; c.2089-2090insA mutation (p.Arg697LysfsX33) in exon 13. The mutation c.263T>G was inherited from his father, and the c.2089-2090insA mutation from his mother. Respiratory infection was recovered by supportive care, and cholestasis was improved slowly with sufficient feeding and supplementation of pancreatic exocrine enzymes. He is 19-month old now and shows catch-up growth. We report a novel CFTR mutation in a Korean infant with CF

X-linked Opitz G/BBB Syndrome: Identification of a Novel Mutation and Prenatal Diagnosis in a Korean Family

X-linked Opitz G/BBB syndrome (XLOS; MIM 300000) is a rare multiple congenital anomaly disorder that is characterized by facial anomalies, laryngeal/tracheal/esophageal defects and genitourinary abnormalities. XLOS is caused by mutations in the MID1 gene which encodes a microtubule-associated RING-Bbox-Coiled-coil (RBCC) protein. We recently found a four-year Korean male patient who was suspected of having XLOS. Mutation analysis of the MID1 gene in the patient and his mother demonstrated that the patient had a novel insertion mutation (c.1798_1799insC), and his mother was a heterozygous carrier of the mutation. After identification of the causative mutation in this family, prenatal diagnosis of two consecutive fetuses were successfully undertaken. This is the first report on a genetically confirmed case of XLOS in Korea

Retropharyngeal abscess coinfected with and after rhinoviral infection in a 1-month-old infant

A retropharyngeal abscess is a rare disease entity in young infants but can develop after nasopharyngeal viral infection. Group B Streptococcus and Staphylococcus aureus are the most common pathogens in young infants, however, Mycobacterium tuberculosis is very rare. We report the case of retropharyngeal abscess and coinfection with S. aureus and M. tuberculosis in a very young infant presenting with respiratory symptoms due to upper airway obstruction. Usually tuberculous retropharyngeal abscesses are caused by the direct invasion of the bacteria from the spine via anterior longitudinal ligament of the spine. However, in this case, no associated spinal disease was observed

The Distinct Metabolic Phenotype of Lung Squamous Cell Carcinoma Defines Selective Vulnerability to Glycolytic Inhibition

Adenocarcinoma (ADC) and squamous cell carcinoma (SqCC) are the two predominant subtypes of non-small cell lung cancer (NSCLC) and are distinct in their histological, molecular and clinical presentation. However, metabolic signatures specific to individual NSCLC subtypes remain unknown. Here, we perform an integrative analysis of human NSCLC tumour samples, patient-derived xenografts, murine model of NSCLC, NSCLC cell lines and The Cancer Genome Atlas (TCGA) and reveal a markedly elevated expression of the GLUT1 glucose transporter in lung SqCC, which augments glucose uptake and glycolytic flux. We show that a critical reliance on glycolysis renders lung SqCC vulnerable to glycolytic inhibition, while lung ADC exhibits significant glucose independence. Clinically, elevated GLUT1-mediated glycolysis in lung SqCC strongly correlates with high 18F-FDG uptake and poor prognosis. This previously undescribed metabolic heterogeneity of NSCLC subtypes implicates significant potential for the development of diagnostic, prognostic and targeted therapeutic strategies for lung SqCC, a cancer for which existing therapeutic options are clinically insufficient

Oral food challenges in children

Many patients assume that allergic reactions against foods are responsible for triggering or worsening their allergic symptoms. Therefore, it is important to identify patients who would benefit from an elimination diet, while avoiding unnecessary dietary restrictions. The diagnosis of food allergy depends on the thorough review of the patients's medical history, results of supplemented trials of dietary elimination, and in vivo and in vitro tests for measuring specific IgE levels. However, in some cases the reliability of such procedures is suboptimal. Oral food challenges are procedures employed for making an accurate diagnosis of immediate and occasionally delayed adverse reactions to foods. The timing and type of the challenge, preparation of patients, foods to be tested, and dosing schedule should be determined on the basis of the patient's history, age, and experience. Although double-blind, placebo-controlled food challenges(DBPCFC) are used to establish definitively if a food is the cause of adverse reactions, they are time-consuming, expensive and troublesome for physician and patients. In practice, An open challenge controlled by trained personnel is sufficient especially in infants and young children. The interpretation of the results and follow-up after a challenge are also important. Since theses challenges are relatively safe and informative, controlled oral food challenges could become the measure of choice in children