Small bowel obstruction secondary to crab shell bezoar: A case report.

Small bowel obstruction is a common surgical condition that needs surgical intervention if conservative measures fail. Bezoar is a rare aetiology of small bowel obstruction with incidence of 4.5%. The bezoars can be grouped, according to the content, into four common types: phytobezoars, trichobezoars, pharmacobezoars, and lactobezoars. However, unusual bezoars like plastic bezoars and metal bezoars have been reported too. Herein, we report a case of an elderly lady who was treated for small bowel obstruction due to crab shell bezoar. This is the first case reported in literature. Ingestion of large intact pieces of crab shell should be avoided due to the potential of causing small bowel obstruction.

Pneumoperitoneum following an Endoscopic Retrograde Cholangiopancreatography (ERCP): A case report.

Post Endoscopic Retrograde Cholangiopancreatography (ERCP) pneumoperitoneum is commonly associated with perforated viscus but is rarely associated with benign causes. We present a case of 29 years old lady who underwent ERCP, who was found to have benign pneumoperitoneum subsequently. She was treated conservatively and recovered without complication. Although rare, post ERCP pneumoperitoneum of benign causes should be investigated as the course of treatment and outcome differ largely.

Improved carrier injection in GaN-based VCSEL via AlGaN/GaN multiple quantum barrier electron blocking layer.

In this report, the improved lasing performance of the III-nitride based vertical-cavity surface-emitting laser (VCSEL) has been demonstrated by replacing the bulk AlGaN electron blocking layer (EBL) in the conventional VCSEL structure with an AlGaN/GaN multiple quantum barrier (MQB) EBL. The output power can be enhanced up to three times from 0.3 mW to 0.9 mW. In addition, the threshold current density of the fabricated device with the MQB-EBL was reduced from 12 kA/cm2 (9.5 mA) to 10.6 kA/cm2 (8.5 mA) compared with the use of the bulk AlGaN EBL. Theoretical calculation results suggest that the improved carrier injection efficiency can be mainly attributed to the partial release of the strain and the effect of quantum interference by using the MQB structure, hence increasing the effective barrier height of the conduction band.

Photoelectrochemical hydrogen generation with linear gradient Al composition dodecagon faceted AlGaN/n-GaN electrode.

We demonstrated photoelectrochemical cells (PECs) with dodecagon faceted AlGaN/n-GaN heterostructure electrode for H(2) generation, where the AlGaN/n-GaN heterostructure has a linear gradient Al composition (LGAC). The separation efficiency of the photo-generated electron-hole pairs in the electrode performs a key function in the H(2) generation efficiency of PEC cells. The linear gradient Al composition, AlGaN, could create more internal field and light absorption because of the linear graded band gap. Therefore, the zero-bias photocurrent density of PEC cells with dodecagon facet LGAC AlGaN/n-GaN heterostructure electrode is around 5.9 times larger than that of dodecagon faceted n-GaN electrode.

BRCA mutations and outcome in epithelial ovarian cancer (EOC): experience in ethnically diverse groups.

BACKGROUND: Epithelial ovarian cancer (EOC) patients with BRCA mutations have better prognosis than nonhereditary cases matched for histology and stage and age at diagnosis, especially Ashkenazi Jews (AJ). MATERIALS AND METHODS: We retrospectively reviewed data on 700 highly ethnically heterogeneous patients diagnosed with stage Ic-IV EOC and evaluated for BRCA status between 1995 and 2009 in American, Israeli, and Italian medical centers. RESULTS: The ethnicities of the 190 patients (median age 55.5 years, range 31-83 years) were AJ, Jewish non-Ashkenazi, Caucasian, African-American, Hispanic, or unknown. Ninety were BRCA1/2 carriers (71 BRCA1 and 19BRCA2). The most common mutations in AJ and non-AJ origins were 185delAG and 6174delT. Non-Jewish Caucasians exhibited the widest variation (>20 mutation subtypes). BRCA carriers had significantly prolonged median overall survival (93.6 months) compared with noncarriers (66.6 months; 95% confidence interval 44.5-91.7, P = 0.0081). There was no difference in progression-free survival. CONCLUSIONS: Our data demonstrate a wide variety of BRCA mutations in a highly ethnically diverse EOC population, and confirm that EOC BRCA mutation carriers have better prognosis with longer median survival than patients with nonhereditary disease. The contribution of unclassified BRCA variants to cancer etiology remains undetermined.

InGaN working electrodes with assisted bias generated from GaAs solar cells for efficient water splitting.

Hydrogen generation through water splitting by n-InGaN working electrodes with bias generated from GaAs solar cell was studied. Instead of using an external bias provided by power supply, a GaAs-based solar cell was used as the driving force to increase the rate of hydrogen production. The water-splitting system was tuned using different approaches to set the operating points to the maximum power point of the GaAs solar cell. The approaches included changing the electrolytes, varying the light intensity, and introducing the immersed ITO ohmic contacts on the working electrodes. As a result, the hybrid system comprising both InGaN-based working electrodes and GaAs solar cells operating under concentrated illumination could possibly facilitate efficient water splitting.

Mn-doped GaN as photoelectrodes for the photoelectrolysis of water under visible light.

Hydrogen generation through direct photoelectrolysis of water was studied using photoelectrochemical (PEC) cells made of Mn-doped GaN photoelectrodes. In addition to its absorption of the ultraviolet spectrum, Mn-doped GaN photoelectrodes could absorb photons in the visible spectrum. The photocurrents measured from PEC cells made of Mn-doped GaN were at least one order higher than those measured from PEC cells made of undoped GaN-working electrodes. Under the visible light illumination and a bias voltage below 1.2 V, the Mn-doped GaN photoelectrodes could drive the water splitting reaction for hydrogen generation. However, hydrogen generation could not be achieved under the same condition wherein undoped GaN photoelectrodes were used. According to the results of the spectral responses and transmission spectra obtained from the experimental photoelectrodes, the enhanced photocurrent in the Mn-doped GaN photoelectrodes, compared with the undoped GaN photoelectrodes, was attributable to the Mn-related intermediate band within the band gap of GaN that resulted in further photon absorption.

Immersed finger-type indium tin oxide ohmic contacts on p-GaN photoelectrodes for photoelectrochemical hydrogen generation.

In this study, we demonstrated photoelectrochemical (PEC) hydrogen generation using p-GaN photoelectrodes associated with immersed finger-type indium tin oxide (IF-ITO) ohmic contacts. The IF-ITO/p-GaN photoelectrode scheme exhibits higher photocurrent and gas generation rate compared with p-GaN photoelectrodes without IF-ITO ohmic contacts. In addition, the critical external bias for detectable hydrogen generation can be effectively reduced by the use of IF-ITO ohmic contacts. This finding can be attributed to the greatly uniform distribution of the IF-ITO/p-GaN photoelectrode applied fields over the whole working area. As a result, the collection efficiency of photo-generated holes by electrode contacts is higher than that of p-GaN photoelectrodes without IF-ITO contacts. Microscopy revealed a tiny change on the p-GaN surfaces before and after hydrogen generation. In contrast, photoelectrodes composed of n-GaN have a short lifetime due to n-GaN corrosion during hydrogen generation. Findings of this study indicate that the ITO finger contacts on p-GaN layer is a potential candidate as photoelectrodes for PEC hydrogen generation.

Rotational positioning system adapted to atomic force microscope for measuring anisotropic surface properties.

The diverse atomic configurations induce the anisotropic surface properties. For investigating anisotropic phenomena, we developed a rotational positioning system adapted to atomic force microscope (AFM). This rotational positioning system is applied to revolve the measured sample to defined angular direction, and it composed of an inertial rotational stepper and a visual angular measurement. The inertial rotational stepper with diameter 30 mm and height 7.6 mm can be easily attached to the AFM-system built in any general optical microscope. Based on a clearance less bearing and the inertial driving method, its bidirectional angular resolution reaches 0.005° per step. For realizing a close-loop controlled angular positioning function, the visual measurement method is utilized. Through the feedback control, the angular positioning error is less than 0.01°. For verifying the system performance, we used it to investigate the anisotropic surface properties of graphite. Through a modified cantilever tip, the atomic-scale stick-slip, and the anisotropic friction phenomena can be distinctly detected.

Hydrogen gas generation using n-GaN photoelectrodes with immersed Indium Tin Oxide ohmic contacts.

An n-GaN photoelectrochemical (PEC) cell with immersed finger-type indium tin oxide (ITO) ohmic contacts was demonstrated in the present study to enhance the hydrogen generation rate. The finger-type ITO ohmic contacts were covered with SiO2 layers to prevent the PEC cell from generating leakage current. Using a 1M NaCl electrolyte and external biases, the typical photocurrent density and gas generation rate of the n-GaN working electrodes with ITO finger contacts were found to be higher than those with Cr/Au finger contacts. The enhancement in photocurrent density or gas generation rate can be attributed to the transparent ITO contacts which allowed the introduction of relatively more photons into the GaN layer. No significant corrosion was observed in the ITO layer after the PEC process compared with the Cr/Au finger contacts which were significantly peeled from the GaN layer. These results indicate that the use of n-GaN working electrodes with finger-type ITO ohmic contacts is a promising approach for PEC cells.

Note: Vector network analyzer-ferromagnetic resonance spectrometer using high Q-factor cavity.

A ferromagnetic resonance (FMR) spectrometer whose main components consist of an X-band resonator and a vector network analyzer (VNA) was developed. This spectrometer takes advantage of a high Q-factor (9600) cavity and state-of-the-art VNA. Accordingly, field modulation lock-in technique for signal to noise ratio (SNR) enhancement is no longer necessary, and FMR absorption can therefore be extracted directly. Its derivative for the ascertainment of full width at half maximum height of FMR peak can be found by taking the differentiation of original data. This system was characterized with different thicknesses of permalloy (Py) films and its multilayer, and found that the SNR of 5 nm Py on glass was better than 50, and did not have significant reduction even at low microwave excitation power (-20 dBm), and at low Q-factor (3000). The FMR other than X-band can also be examined in the same manner by using a suitable band cavity within the frequency range of VNA.

Gigantic jets between a thundercloud and the ionosphere.

Transient luminous events in the atmosphere, such as lighting-induced sprites and upwardly discharging blue jets, were discovered recently in the region between thunderclouds and the ionosphere. In the conventional picture, the main components of Earth's global electric circuit include thunderstorms, the conducting ionosphere, the downward fair-weather currents and the conducting Earth. Thunderstorms serve as one of the generators that drive current upward from cloud tops to the ionosphere, where the electric potential is hundreds of kilovolts higher than Earth's surface. It has not been clear, however, whether all the important components of the global circuit have even been identified. Here we report observations of five gigantic jets that establish a direct link between a thundercloud (altitude approximately 16 km) and the ionosphere at 90 km elevation. Extremely-low-frequency radio waves in four events were detected, while no cloud-to-ground lightning was observed to trigger these events. Our result indicates that the extremely-low-frequency waves were generated by negative cloud-to-ionosphere discharges, which would reduce the electrical potential between ionosphere and ground. Therefore, the conventional picture of the global electric circuit needs to be modified to include the contributions of gigantic jets and possibly sprites.

Murine cytomegalovirus is regulated by a discrete subset of natural killer cells reactive with monoclonal antibody to Ly49H.

Antiviral roles of natural killer (NK) cell subsets were examined in C57BL/6 mice infected with murine cytomegalovirus (MCMV) and other viruses, including lymphocytic choriomeningitis virus (LCMV), vaccinia virus (VV), and mouse hepatitis virus (MHV). Each virus vigorously induced an NK cell infiltrate into the peritoneal cavity and liver, causing some redistributions of NK cell subsets defined by monoclonal antibody (mAb) directed against Ly49A, C/I, D, and G2. Striking results were seen with a mAb (1F8) reactive with the positively signaling molecule Ly49H, present in MCMV-resistant C57BL/6 mice. mAb 1F8 also stains Ly49 C and I, but exclusion of those reactivities with mAb 5E6, which recognizes Ly49 C and I, indicated that Ly49H(+) cells infiltrated the peritoneal cavity and liver and were particularly effective at synthesizing interferon gamma. Depletion of 1F8(+) but not 5E6(+) cells in vivo by mAb injections enhanced MCMV titers by 20-1,000-fold in the spleen and approximately fivefold in the liver. Titers of LCMV or VV were not enhanced. These anti-MCMV effects were attributed to prototypical NK1.1(+)CD3(-) NK cells and not to NK1.1(+)CD3(+) "NK/T" cells. This is the first evidence that control of a virus infection in vivo is mediated by a distinct NK cell subset.

Monocyte membrane type 1-matrix metalloproteinase. Prostaglandin-dependent regulation and role in metalloproteinase-2 activation.

Membrane type 1-matrix metalloproteinase (MT1-MMP)-mediated activation of MMP-2 is thought to be important in the proteolysis of extracellular matrix in pathological events in which monocytes/macrophages are found. Here we report on the induction and regulation of human monocyte MT1-MMP and its role in MMP-2 activation. Activation of monocytes by lipopolysaccharide resulted in the induction of MT1-MMP mRNA and protein that was suppressed by inhibitors of prostaglandin synthesis (indomethacin), adenylyl cyclase (SQ 22536), and protein kinase A (Rp-cAMPs). Suppression of MT1-MMP by indomethacin and SQ 22536 was reversed by prostaglandin E(2) and dibutyryl cyclic AMP, respectively, demonstrating that induction of monocyte MT1-MMP is regulated through a prostaglandin-cAMP pathway. Functional analysis revealed that pro-MMP-2 in the supernatants from human bone marrow stromal fibroblasts, normal male-derived fibroblasts and melanoma cells (A2058) was converted to active MMP-2 when cultured with activated but not control monocytes. Antibodies against MT1-MMP blocked the activation of MMP-2. Tissue inhibitor of metalloproteinase-2 regulation of MMP-2 activation was shown through the addition of varying amounts of recombinant tissue inhibitor of metalloproteinase-2 with pro-MMP-2 to MT1-MMP-expressing monocytes. These findings demonstrate that activated monocytes express functionally active MT1-MMP that may play a significant role in the activation of MMP-2 produced by other cells and as such influence developmental and pathological conditions.

Ly49I NK cell receptor transgene inhibition of rejection of H2b mouse bone marrow transplants.

The Ly49 family of genes encode NK cell receptors that bind class I MHC Ags and transmit negative signals if the cytoplasmic domains have immunoregulatory tyrosine-based inhibitory motifs (ITIMs). 5E6 mAbs recognize Ly49C and Ly49I receptors and depletion of 5E6+ NK cells prevents rejection of allogeneic or parental-strain H2d bone marrow cell (BMC) grafts. To determine the function of the Ly49I gene in the rejection of BMC grafts, we transfected fertilized eggs of FVB mice with a vector containing DNA for B6 strain Ly49I (Ly49IB6). Ly49IB6 is ITIM+ and is recognized by 5E6 as well as Ly49I-specific 8H7 mAbs. Normal FVB H2q mice reject H2b but not H2d BMC allografts, and the rejection of H2b BMC was inhibited partially by anti-NK1.1 and completely by anti-asialo GM1, but not by anti-CD8, Abs. In FVB mice, NK1.1 is expressed on only 60% NK cells. FVB. Ly49IB6 hosts failed to reject H2d or H2b BMC, but did reject class I-deficient TAP-1-/- BMC, indicating that NK cells were functional. Nondepleting doses of anti-Ly49I Abs reversed the acceptance of H2b BMC by FVB.Ly49IB6 mice. FVB.Ly49IB6+/- mice were crossed and back-crossed with 129 mice-H2b, 5E6-, poor responders to H2d BMC grafts. While transgene-negative H2b/q F1 or first-generation back-crossed mice rejected H2b marrow grafts (hybrid resistance), transgene-positive mice did not. Thus B6 strain Ly49I receptors transmit inhibitory signals from H2b MHC class I molecules. Moreover, Ly49IB6 has no positive influence on the rejection of H2d allografts.

Molecular characterization of the rat NK cell receptor 2B4.

2B4 (CD244) is a cell surface glycoprotein of the immunoglobulin superfamily involved in the regulation of natural killer and T lymphocyte function. It is the high affinity counter-receptor for CD48. In mouse and human NK cells, crosslinking of 2B4 with a specific monoclonal antibody or with CD48 can trigger cell-mediated cytotoxicity, IFN-gamma secretion, phosphoinositol turnover and NK cell invasiveness. Recent reports of defective 2B4 signaling and NK cell function in X-linked lymphoproliferative syndrome suggest that this may contribute to the progression of this human disease. Here we describe the molecular characterization of the rat 2B4 gene. The cDNA encodes a protein of 395 amino acid residues that contain two Ig domains in the extracellular region and three unique tyrosine motifs (TxYxxV/I/A) in the cytoplasmic region. The predicted protein has 81 and 68% similarity with mouse 2B4 and human 2B4, respectively. Additionally, it has 94 and 89% similarity at the protein level with the recently reported rat 2B4 related genes, r2B4R-tm and r2B4R-se respectively. Northern blot analysis indicated the presence of multiple transcripts in rat LAK cells and RNK-16 cells. Immunoprecipitation and deglycosylation studies showed that rat 2B4 is glycosylated to similar extent as that of mouse and human 2B4. The cloning of r2B4 in the light of the availability of rat NK cell lines should facilitate in vitro and in vivo experiments to decipher the functional role of 2B4 in NK cell biology.

Cutting edge: expression of functional CD94/NKG2A inhibitory receptors on fetal NK1.1+Ly-49- cells: a possible mechanism of tolerance during NK cell development.

Fetal liver- and thymus-derived NK1.1+ cells do not express known Ly-49 receptors. Despite the absence of Ly-49 inhibitory receptors, fetal and neonatal NK1.1+Ly-49- cells can distinguish between class Ihigh and class Ilow target cells, suggesting the existence of other class I-specific inhibitory receptors. We demonstrate that fetal NK1. 1+Ly-49- cell lysates contain CD94 protein and that a significant proportion of fetal NK cells are bound by Qa1b tetramers. Fetal and adult NK cells efficiently lyse lymphoblasts from Kb-/-Db-/- mice. Qa1b-specific peptides Qdm and HLA-CW4 leader peptide specifically inhibited the lysis of these blasts by adult and fetal NK cells. Qdm peptide also inhibited the lysis of Qa1b-transfected human 721.221 cells by fetal NK cells. Taken together, these results suggest that the CD94/NKG2A receptor complex is the major known inhibitory receptor for class I (Qa1b) molecules on developing fetal NK cells.