Thermodynamic study of nanometals for different shapes and sizes

Thermodynamic analytic model has been discussed to study the size as well as shape effect on thermodynamic parameters of nanometals. Thermodynamic properties like melting temperature, cohesive energy, vacancy formation energy and Debye temperature of Al, Ag, Au, In and Sn nano metals for spherical and non spherical nanoparticles (i.e. tetrahedral, hexahedral, octahedral and disc like) with different size have been studied. Present study shows that spherical and nonspherical nanoparticles behave in different manner due to the difference in their shape factor. It has been found that these thermal properties show decreasing trend with decrement in size of the nanomaterial due to the change in surface to volume ratio. The obtained results also reveal that shape of the nanoparticle plays a vital role to affect the thermodynamic properties of small sized nanoparticles because of change in surface area with shape for fixed volume. Theoretical results obtained for melting temperature, cohesive energy, vacancy formation energy and Debye temperature have been discussed in the light of available simulated and experimental data which supports the validity of present model

IN VITRO MODELS FOR INHALED CORTICOSTEROID (ICS) AEROSOLS: A STUDY OF THEIR BIOPHARMACEUTICS AND PHARMACOLOGY

Lung cellular disposition and anti-inflammatory pharmacology of inhaled corticosteroids (ICSs) is complex, comprised of a cascade of aerosol deposition and dissolution, followed by cellular uptake for local pharmacological action. This project hypothesized that the kinetics of dissolution for certain ICS aerosols generated from inhaler products were kinetically rate-determined for their cellular uptake and local pharmacological action. A novel dissolution testing system was developed to determine the dissolution kinetics for the ICS aerosols. A total of 5 ICSs aerosols generated from 6 inhaler products were collected in 2.1-3.3 or 4.7-5.8 µm of aerodynamic diameters at 0.7-19.8 µg on filter membranes by impaction using the Andersen cascade impactor. The filter membrane was then placed on the donor side of the transwell insert, with its face down, and the ICS dissolution in the limited 40 µL of the donor fluid was monitored over time. The dissolution kinetics overall conformed to the rank order of the aqueous solubility, while also being affected by ICS aerosol’s mass, size, formulation and dosage forms. For the readily soluble triamcinolone acetonide (TA), the kinetics was first-order, reaching ≥89 % dissolution in 5 h. In contrast, for the least soluble fluticasone propionate (FP), the kinetics was zero-order, reaching only 3 % dissolution in 10 h. The project then developed an air-interface culture of human bronchial epithelial cell line, Calu-3. Well-differentiated monolayers were formed with sufficiently “tight” barrier for restrictive solute diffusion while their mucosal surface was maintained semi-dry with 39.7±12.1 µL of the mucosal lining fluid in the 4.5 cm2 transwells. These monolayers were transfected with reporter plasmid of pNFκB-Luc to assess in vitro anti-inflammation via repression of pro-inflammatory NFκB by direct FP or TA aerosol deposition. The FP aerosols at 0.9 µg successfully exhibited significant 35.7±6.3 % repression. Notably, however, an identical ~0.5 µg of FP and TA aerosols caused comparable 15.5±2.2 and 10.4±2.6 % repression, respectively, despite FP’s 10-fold greater “intrinsic” anti-inflammatory potency over TA, reported in the literature. This was attributed to FP’s slow dissolution resulting in only 4.7 % cellular uptake, compared to 32.6 % for the TA aerosols. Hence, the FP aerosols were shown to be rate-determined by dissolution on the lung cell surface, resulting in reduced anti-inflammatory actions, which was not the case for the readily soluble TA aerosols

Identifikation FLT3-Aktivität regulierender Protein Tyrosin Phosphatasen und FLT3 ITD regulierter PTPs

Die Akute Myeloische Leukämie (AML) ist eine der am häufigsten vorkommenden Formen der Leukämie. Etwas 90% der Erkrankten sind Erwachsene, während Kinder seltener von der Erkrankung betroffen sind. AML entsteht durch das klonale Wachstum myeloischer Zellen, welche stark proliferieren, aber nicht terminal differenzieren können. Dadurch akkumulieren sich unreife Zellen verschiedener myeloischer Differenzierungslinien. Rezeptortyrosinkinasen (RTK) sind wichtige Moleküle für die Regulation von Zellaktivitäten, und deshalb auch kritisch für die normale Zellentwicklung. Fms like tyrosine kinase-3 (FLT3) ist ein Mitglied der Klasse-III RTK Familie, und hat eine wichtige Funktion bei der normalen Differnzierung von Monozyten und B-Zellen. Mutationen im FLT3-kodierenden Gen, darunter Punktmutationen in der Tyrosinkinase-Domäne (TKD), oder interne Tandemduplikationen (ITD) vor allem in der Juxtamembran-Domäne, führen zur konstitutiven Aktivierung von FLT3. FLT3-Mutationen stellen den zweithäufigsten Typ genetischer Läsionen bei der AML dar. Über die Signaltransduktion von FLT3 und seiner mutierten Versionen ist schon viel bekannt. Wildtyp FLT3 aktiviert den RAS-MAPK- und den PI3K-AKT Signalweg, und FLT3 ITD aktiviert außerdem STAT5, was entscheidend für die Zelltransformation ist. Wie die FLT3 Aktivität im Detail reguliert wird, ist jedoch noch weitgehend unklar. Protein-Tyrosinphosphatasen (PTPs) sind Enzyme, die mit Tyrosinkinasen kooperieren, und die RTK Aktivität durch Dephosphorylierung regulieren können. Deshalb spielen sie wahrscheinlich eine wichtige Rolle für normale Zellfunktionen. Um potentielle Regulatoren der FLT3-Aktivität zu identifizieren, wurde ein shRNA-Screen für PTPs auf der Basis shRNA-kodierender lentiviraler Partikel durchgeführt. Der „Knockdown“ der Expression von PTPs wurde mittels shRNAs für 20 verschiedene PTP-Gene in murinen, myeloiden Zellen, sogenannten 32D-Zellen durchgeführt, welche Wildtyp FLT3 exprimierten. Die FLT3-Ligand (FL)-stimulierte Aktivität von ERK wurde als Messparameter für die Beeinflussung der FLT3-Aktivität benutzt. DEP-1 wurde in dem Screen als eine der potentiell die FLT3-Aktivität beeinflussenden PTPs identifiziert. Unterschiede in der FLT3-Signaltransduktion zwischen Zellen, die mit Kontroll-shRNA- exprimierenden Konstrukten transduziert worden waren, und solchen mit DEP-1 Knockdown wurden analysiert. Es wurde der Screeningbefund bestätigt, dass DEP-1-Depletion die FL-stimulierte ERK-Aktivierung erhöht. Ebenso war die Proliferation der Zellen erhöht. Weiterhin resultierte die DEP-1-Depletion in einer schwachen STAT5-Aktivierung und einer Hyperphosphorylierung von FLT3. Bemerkenswerterweise wurde eine Hyperphosphorylierung der Phosphotyrosin-Reste pY589 und pY591 nach DEP-1- Depletion beobachtet. Diese Phosphorylierungsstellen sind an der Aktivierung von STAT5 beteiligt. Die transiente Depletion von DEP-1 in der humanen AML-Linie THP-1 verursachte auch eine erhöhte FLT3-Phosphorylierung, in diesem Fall an den Phosphotyrosinen 589 und 599, und führte auch zu einer schwach erhöhten Aktivierung von ERK. DEP-1-depletierte 32D Zellen, welche Wildtyp FLT3 exprimierten, waren in der Lage zur FL-induzierten Koloniebildung in halbflüssigem Medium. Die FL-Abhängigkeit ist dabei ein klares Indiz für die Rolle der FLT3-Aktivität in diesem Prozess. Der Knockdown von DEP-1 war jedoch nur partiell transformierend. So löste die Injektion der DEP-1-depletierten Zellen in syngene Mäuse keine myeloproliferative Erkrankung aus. Zusammengenommen zeigen diese Daten, dass DEP-1 die FLT3- Aktivität negativ reguliert. Der Verlust von DEP-1 könnte zur Transformation bei der AML beitragen, würde aber höchstwahrscheinlich kooperierende Mutationen erfordern, um zur Transformation in vivo zu führen. Ein weiterer Teil dieser Dissertation beschäftigte sich mit der Identifikation von PTPs, die möglicherweise im Rahmen der AML durch FLT3 ITD reguliert werden. Zu diesem Zweck wurde cDNA aus humanen AML-Blasten gewonnen, die entweder Wildtyp FLT3 oder FLT3 ITD exprimierten. Das Expressionsmuster von 92 humanen PTPs wurde für diese Zellen sowie auch für humane Zelllinien, die entweder Wildtyp FLT3 (EOL-1, THP-1 und RS4-11) oder FLT3 ITD (MV4-11) exprimierten, analysiert. 10 PTPs wurden für eine weitergehende Analyse ausgewählt, basierend auf Expressionsdifferenzen zwischen Wildtyp FLT3- oder FLT3 ITD-exprimierenden Blasten, oder auf Grundlage generell sehr hoher mRNA-Expression. Das mRNA-Expressionsprofil dieser 10 PTPs wurde in einem zweiten Set von AML-Blasten analysiert, sowie in 32D Zellen, die entweder kein FLT3, oder die beiden unterschiedlichen Versionen von FLT3 exprimierten. Aus diesen Untersuchungen wurde klar, dass FLT3 ITD die dualspezifische PTP DUSP6 in der Expression stimulieren kann. Auch die DUSP6 Proteinspiegel waren in 32D Zellen, die FLT3 ITD exprimierten, erhöht. Die FLT3 Kinase-Inhibitoren AG1295 und 1020 hemmten die DUSP6-Expression in den FLT3 ITD-exprimierenden murinen 32D-Zellen und humanen MV4-11-Zellen fast vollständig. Dies zeigte, dass die DUSP6-Expression in der Tat von der konstitutiven FLT3 ITD-Signalaktivität abhängig ist. Pharmakologische Inhibitoren des RAS-MAPK-Weges, des PI3K-AKT-Weges und von STAT5 wurden benutzt, um die Beteiligung dieser Signalwege an der DUSP6-Induktion zu prüfen. Während U0126, ein MEK-Inhibitor, die DUSP6-Expression stark verringerte, hatten Wortmannin und ein niedermolekularer STAT5-Inhibitor nur schwache Effekte. Die zusätzliche Analyse eines größeren Satzes von Affimetrix mRNA-Expressionsdaten, die in einer unabhängigen Studie in Rotterdam erhalten worden waren, zeigte, dass noch eine andere dualspezifische PTP, TNS1, offenbar durch FLT3 ITD reguliert wird. In diesem Fall war die Expression in Anwesenheit von FLT3 ITD verringert. Dieser Befund konnte in murinen 32D und Ba/F3-Zellen rekapituliert werden. Die beobachteten Veränderungen in der Expression bestimmter PTPs in Anwesenheit von FLT3 ITD könnten auf eine Rolle dieser Phänomene im Transformationsprozess hinweisen. Diese Möglichkeit wird gegenwärtig untersucht

CitE Enzymes Are Essential for Mycobacterium tuberculosis to Establish Infection in Macrophages and Guinea Pigs

Bacterial citrate lyase activity has been demonstrated in various eukaryotes, bacteria and archaea, underscoring their importance in energy metabolism of the cell. While the bacterial citrate lyase comprises of three different subunits, M. tuberculosis genome lacks CitD and CitF subunits of citrate lyase complex but encodes for 2 homologs of CitE subunits, Rv2498c and Rv3075c. Using temperature sensitive mycobacteriophages, we were able to generate both single and double citE mutant strains of M. tuberculosis. The survival experiments revealed increased susceptibility of the double mutant strain to oxidative stress in comparison to the parental strain. Also, simultaneous deletion of both citE1 and citE2 in M. tuberculosis genome resulted in impairment of intracellular replication in macrophages. The double mutant strain displayed reduced growth in lungs and spleens of guinea pigs. This is the first study demonstrating that M. tuberculosis critically requires CitE subunits of citrate lyase for pathogenesis. Taken together, these findings position these enzymes as potential targets for development of anti-tubercular small molecules

Comparative characterization of small RNAs derived from an emaravirus and a geminivirus infecting pigeonpea

Not AvailableHigh throughput sequencing technologies, supported by bioinformatics tools are employed to retrieve small RNA sequence information derived from the nucleic acids of plant infecting viruses. In addition to characterization of the small RNAs to understand the biology of the virus, the small RNA sequence can be assembled to reconstitute viral genome sequence. For the first time the semiconductor based Ion Proton sequencing technology is used to sequence the small RNAs from pigeonpea (Cajanus cajan) plants infected by two distinct viruses with RNA and DNA as their genomes. The reconstitution of the viral genome sequence revealed that the pigeonpea plant from Kalaburagi (erstwhile Gulbarga, Karnataka state) was infected by an emaravirus species Pigeonpea sterility mosaic emaravirus 1 (PPSMV-1) and another plant from New Delhi was infected by a begomovirus species Mungbean yellow mosaic India virus (MYMIV). Characterization and comparison of small RNA sequences derived from both the viruses showed vast differences in their pattern of accumulation and their size classes. In the case of PPSMV-1, the 21 nt sized siRNAs accumulated at far greater levels followed by 22 and 24 nt siRNAs. Whereas in MYMIV, the proportion of accumulation of each size class of siRNAs was similar. Further the distribution of small RNAs across the genomes of PPSMV-1 and MYMIV was mapped and the density of small RNA accumulation showed a positive correlation with the GC content of viral sequence.Not Availabl

A Mysterious Cause of Gastrointestinal Bleeding Disguising Itself as Diverticulosis and Peptic Ulcer Disease: A Review of Diagnostic Modalities for Aortoenteric Fistula

An 81-year-old male with a history of hypertension, hyperlipidemia, smoking, and peptic ulcer disease (PUD) presented with 2 episodes of maroon stools for 3 days and was found to be orthostatic. His PUD was thought to have accounted for a previous upper gastrointestinal (GI) bleed. A colonoscopy revealed 3 polyps and a few diverticuli throughout the colon that were considered to be the source of the bleeding. Two months later, the patient had massive lower GI bleeding and developed hypovolemic shock with a positive bleeding scan in the splenic flexure; however, angiography was negative. A repeat colonoscopy revealed transverse/descending colon diverticular disease and the patient was scheduled for a left hemicolectomy for presumed diverticular bleeding. Intraoperatively, an aortoenteric (AE) fistula secondary to an aorto-bi-iliac bypass graft placed during an abdominal aortic aneurysm (AAA) repair 14 years prior was discovered and was found to be the source of the bleeding. The patient had an AE fistula repair and did well postoperatively without further bleeding. AE fistulas can present with either upper GI or lower GI bleeding, and are universally deadly if left untreated. AE fistulas often present with a herald bleed before life-threatening bleeding. A careful history should always be elicited in patients with risk factors of AAAs such as hypertension, hyperlipidemia and a history of smoking. Strong clinical suspicion in the setting of a scrupulous patient history is the most important factor that allows for the diagnosis of an AE fistula. There are numerous diagnostic modalities for AE fistula, but there is not one specific test that universally diagnoses AE fistulas. Nuclear medicine scans and angiography should not be completely relied on for the diagnosis of AE fistulas or other lower GI bleeds for that manner. Although the conventional paradigm for evaluating lower GI bleeds incorporates nuclear medicine scans and angiography, there is evidence that early endoscopy with enteroscopy may have a better role in severe lower GI bleeding

Influence of Size, Shape, and Scattering on Electrical Resistivity of Metal Nanowires

300-306A simple quantitative model has been proposed for exploring the combined effect of size, shape, and electron scattering on the electrical resistivity of metallic nanowires. In the present model, the effect of different cross-sectional shapes of nanowires has been comprised on the surface and grain boundary scattering. For understanding electrical behavior at the nanolevel, the incorporation of specularity parameter (p) with different cross-sectional shapes of nanowires is essential. It is responsible for the reduction in the mean free path of electrons; which generates the favorable condition for enhancing the surface scattering, consequently contributing to increment of electrical resistivity. The applicability of the proposed model has been investigated for copper, nickel, silver, and aluminum metallic nanowires of four different cross-sectional shapes (rectangular, triangular, square, and spherical) along with different values of reflection coefficient (R). Calculated results have been compared with the available experimental data and it is observed that the results are in close agreement, which proves the validity of the proposed model. The proposed model shows the collective effect of size, scattering, and crosssectional shape factor (δ) on electrical resistivity in a very simple and straightforward manner and able to reduce the complexity of existing models up to great extent

EFFECT OF CYTOKININ ANALOGUES ON CYTOKININ METABOLISM AND STRESS RESPONSIVE GENES UNDER OSMOTIC STRESS IN WHEAT

Osmotic stress induced by conditions like drought, salinity and heat etc. impairs plant growth and development by affecting plant physiological processes. Present study was conducted in laboratory to understand the role cytokinin analogues (TDZ and BAP) in osmotic stress amelioration and their relative efficiency in inducing stress tolerance. Twenty days old wheat seedlings were treated 20% PEG-6000 to induce osmotic stress (-0.491 MPa). Exogenous application of cytokinin analogues enhanced endogenous cytokinin levels by up-regulating expression of IPT (isopentenyl transferase) and down-regulating CKX (cytokinin oxidase) gene expression under osmotic stress. Further, increase in relative water content (30%), membrane stability (15%) and nitrogen assimilation was observed along with delayed leaf senescence in cytokinin treated seedlings under osmotic stress. The current finding suggested that application of TDZ was found to be more effective as compared to BAP even at lower concentrations

A fine balance:epigenetic control of cellular quiescence by the tumor suppressor PRDM2/RIZ at a bivalent domain in the cyclin a gene

Adult stem cell quiescence is critical to ensure regeneration while minimizing tumorigenesis. Epigenetic regulation contributes to cell cycle control and differentiation, but few regulators of the chromatin state in quiescent cells are known. Here we report that the tumor suppressor PRDM2/RIZ, an H3K9 methyltransferase, is enriched in quiescent muscle stem cells in vivo and controls reversible quiescence in cultured myoblasts. We find that PRDM2 associates with &gt;4400 promoters in G0 myoblasts, 55% of which are also marked with H3K9me2 and enriched for myogenic, cell cycle and developmental regulators. Knockdown of PRDM2 alters histone methylation at key promoters such as Myogenin and CyclinA2 (CCNA2), and subverts the quiescence program via global de-repression of myogenesis, and hyper-repression of the cell cycle. Further, PRDM2 acts upstream of the repressive PRC2 complex in G0. We identify a novel G0-specific bivalent chromatin domain in the CCNA2 locus. PRDM2 protein interacts with the PRC2 protein EZH2 and regulates its association with the bivalent domain in the CCNA2 gene. Our results suggest that induction of PRDM2 in G0 ensures that two antagonistic programs-myogenesis and the cell cycle-while stalled, are poised for reactivation. Together, these results indicate that epigenetic regulation by PRDM2 preserves key functions of the quiescent state, with implications for stem cell self-renewal.</p

Hemobilia caused by a ruptured hepatic cyst: a case report

<p>Abstract</p> <p>Introduction</p> <p>Hemobilia is a rare cause of upper gastrointestinal bleeding. More than 50% of hemobilia cases are related to iatrogenic trauma from hepatobiliary procedures, and needle biopsy of the liver represents the most common cause. A minority of hemobilia cases are due to hepatobiliary disorders such as cholangitis, hepatobiliary cancers, choledocholithiasis, and vascular abnormalities in the liver. The classic presentation of hemobilia is the triad of right upper quadrant (biliary) pain, obstructive jaundice, and upper gastrointestinal bleeding. We report a rare case of hemobilia caused by a spontaneous hepatic cyst rupture, where our patient presented without the classical symptoms, in the absence of therapeutic or pathological coagulopathy, and in the absence of spontaneous or iatrogenic trauma.</p> <p>Case presentation</p> <p>A 91-year-old African-American woman was referred to our out-patient gastroenterology clinic for evaluation of mild epigastric pain and intermittent melena. An abdominal computed tomography scan was remarkable for multiple hepatic cysts. Esophagogastroduodenoscopy revealed multiple blood clots at the ampulla of Vater. Endoscopic retrograde cholangiopancreatography showed a single 18 mm-sized filling defect in the common hepatic duct wall at the junction of the right and left hepatic duct, adjacent to one of the hepatic cysts. The ruptured hepatic cyst communicated to the bile ducts and was the cause of hemobilia with an atypical clinical presentation.</p> <p>Conclusion</p> <p>Hemobilia is an infrequent cause of upper gastrointestinal bleeding and rarely occurs due to hepatic cyst rupture. To the best of our knowledge, this is only the second case report in the literature that describes hemobilia due to hepatic cyst rupture. However, it is the first case in the literature of hemobilia due to hepatic cyst rupture in the absence of iatrogenic or spontaneous trauma, and in the absence of a spontaneous or pathological coagulopathy.</p