Tricuspid valve annular tilt for assessment of pre- and post-intervention right ventricular volume in patients undergoing transcatheter pulmonary valve replacement.

INTRODUCTION: Transcatheter pulmonary valve replacement serves as a successful alternative to surgical replacement of a right ventricle to pulmonary artery conduit. Guidelines for recommending transcatheter pulmonary valve replacement depend on MRI right ventricular volumes, which have been correlated to the echocardiographic measure of right ventricular annular tilt. We aim to assess whether right ventricular annular tilt can be a clinically useful alternative tool in the acute and long-term periods after transcatheter pulmonary valve replacement to assess right ventricular health. METHODS: We reviewed 70 patients who underwent transcatheter pulmonary valve replacement at a single institution. Echocardiographic measurements were obtained prior to transcatheter pulmonary valve replacement, immediately after transcatheter pulmonary valve replacement, and within 6 months to 1 year after transcatheter pulmonary valve replacement. Right ventricular annular tilt measures the angle of the tricuspid valve plane relative to the mitral valve plane at end-diastole in the apical four-chamber view. Right ventricular fractional area change, right ventricular systolic strain, tissue Doppler velocity, and tricuspid annular plane systolic excursion Z-scores were obtained using published methods. RESULTS: Right ventricular annular tilt decreased significantly immediately after transcatheter pulmonary valve replacement (p = 0.0004), and this reduction in right ventricular volume persisted at the mid-term follow-up (p < 0.0001). Fractional area change did not change significantly after transcatheter pulmonary valve replacement while right ventricular global strain improved at mid-term follow-up despite no significant difference immediately after transcatheter pulmonary valve replacement. CONCLUSIONS: Right ventricular annular tilt decreases both immediately after transcatheter pulmonary valve replacement and at mid-term follow-up. Right ventricular strain also improved after transcatheter pulmonary valve replacement, corresponding to the improved volume load. Right ventricular annular tilt can be considered as an additional echocardiographic factor to assess right ventricular volume and remodeling after transcatheter pulmonary valve replacement.

Two-dimensional van der Waals C60 molecular crystal.

Two-dimensional (2D) atomic crystals, such as graphene and transition metal dichalcogenides et al. have drawn extraordinary attention recently. For these 2D materials, atoms within their monolayer are covalently bonded. An interesting question arises: Can molecules form a 2D monolayer crystal via van der Waals interactions? Here, we first study the structural stability of a free-standing infinite C60 molecular monolayer using molecular dynamic simulations, and find that the monolayer is stable up to 600 K. We further study the mechanical properties of the monolayer, and find that the elastic modulus, ultimate tensile stress and failure strain are 55-100 GPa, 90-155 MPa, and 1.5-2.3%, respectively, depending on the stretching orientation. The monolayer fails due to shearing and cavitation under uniaxial tensile loading. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the monolayer are found to be delocalized and as a result, the band gap is reduced to only 60% of the isolated C60 molecule. Interestingly, this band gap can be tuned up to ±30% using strain engineering. Owing to its thermal stability, low density, strain-tunable semi-conducting characteristics and large bending flexibility, this van der Waals molecular monolayer crystal presents aplenty opportunities for developing novel applications in nanoelectronics.

Molecular mobility on graphene nanoribbons.

Graphene nanoribbons (GNRs) have been proposed to be used as nanoscale mass-conveyor highways. However, how factors such as edge confinement, edge rippling, ribbon twisting, and thermal fluctuations affect the mobility of admolecules on GNRs for such application remains unknown. Using molecular dynamics (MD) simulations, we address these issues by investigating the surface mobility of a physisorbed C60 admolecule on pristine GNRs. We show that the absorption energy and edge energy barrier of a GNR are able to keep and confine the admolecule motion only on one side of the GNR. The twisting of narrow GNRs in combination with thermal fluctuations causes the admolecule to move in a helical trajectory, and thus markedly affects its mobility. As the GNR width increases, its twisting is gradually inhibited, and the motion of the admolecule becomes planar. A comparison between the results from our MD simulations and those from the confined Langevin model indicates that the distinct behavior of molecular mobility on narrow GNRs is due to their twisting rather than geometrical confinement. These findings shed light on the important factors that control the characteristics of the GNR-based mass transport highways.

Separation, folding and shearing of graphene layers during wedge-based mechanical exfoliation.

We report, using molecular dynamics simulation studies, how and under what conditions graphene layers separate, fold and shear during a wedge-based mechanical exfoliation machining technique to produce few-layer graphene. Our previously reported experimental results using this novel technique have shown clear evidence of few-layer graphene being subjected to such phenomena. Molecular simulations of initial wedge engagement show that the entry location of the wedge tip vis-á-vis the nearest graphene layer plays a key role in determining whether layers separate or fold and which layers and how many of them fold. We also show that depending on this entry location several successive layers beneath the wedge undergo significant elastic bending, consuming energies requiring large vertical forces to be imposed by the moving wedge. The layer separation force itself is seen to be minimal and consistent with breaking up of van der Waals interactions. In addition, shearing of layers occurs mainly during wedge exit and depends largely on the wedge speed and also its depth of insertion. Understanding the conditions at which this separation, folding and shearing of the graphene layers takes place, one can control or tune the wedge-based exfoliation technique for particular kinds of graphene layers.

Patterned graphone--a novel template for molecular packing.

Precise positioning and packing of nanoscale building blocks is essential for the fabrication of many nanoelectro-mechanical devices. Carrying out such manipulations at the nanoscale still remains a challenge. Here we propose the use of graphone domain arrays embedded in a graphene sheet as a template to precisely position and pack molecules. Our atomistic simulations show that a graphone domain is able to adopt well-defined three-dimensional geometries, which in turn create 'energy wells' to trap molecules by means of physisorption. Using the C60 molecule as a model block, the stable trapping conditions are identified. The present work presents a novel route to position and pack molecules for nanoengineering applications.

Edge-stress-induced warping of graphene sheets and nanoribbons.

We show that edge stresses introduce intrinsic ripples in freestanding graphene sheets even in the absence of any thermal effects. Compressive edge stresses along zigzag and armchair edges of the sheet cause out-of-plane warping to attain several degenerate mode shapes. Based on elastic plate theory, we identify scaling laws for the amplitude and penetration depth of edge ripples as a function of wavelength. We also demonstrate that edge stresses can lead to twisting and scrolling of nanoribbons as seen in experiments. Our results underscore the importance of accounting for edge stresses in thermal theories and electronic structure calculations for freestanding graphene sheets.

Synthesis and Biological Screening of 5-{[(4,6-Disubstituted pyrimidine-2-yl)thio]methyl}-N-phenyl-1,3,4-thiadiazol-2-amines.

A number of substituted-α,ß-unsaturated carbonyl compounds (1a-i) were prepared by Claisen-Schmidt condensation of substituted acetophenone with selected araldehydes, which on cycloaddition with thiourea furnished 4,6-disubstituted pyrimidine-2-thiols (2a-i). Reaction of (2a-i) with ethyl chloroacetate followed by condensation with hydrazine hydrate yielded 2-[(4,6-disubstituted pyrimidine-2-yl) thio] acetohydrazides (4a-c). Condensation of compounds (4a-c) with phenyl isothiocyanate gave 2-{[(4,6-disubstituted pyrimidine-2-yl) thio] acetyl}-N-phenylhydrazinecarbothioamides (5a-c) which on treatment with concentrated sulphuric acid afforded titled compounds 5-{(4,6-disubstituted pyrimidine-2-yl) thio] methyl}-N-phenyl-1,3,4-thiadiazole-2-amines (6a-c). These compounds have been characterized on the basis of elemental analysis, IR, (1)H NMR and MS. Compounds have been evaluated for their anticancer and antioxidant activities. Compounds 2b, 2c and 6b exhibited significant antitumor activity against human breast cancer MCF 7 cell line. However, moderate antioxidant activity was observed with compounds 2c, 2d, 2g and 6b.

Characterization of an alternatively spliced AATYK mRNA: expression pattern of AATYK in the brain and neuronal cells.

The AATYK gene encodes a tyrosine kinase whose expression is up-regulated during the apoptosis and differentiation of 32Dcl3 myeloblastic cells. Because high levels of AATYK mRNA have also been detected in the brain, and because these transcripts differ in size from that observed in the 32Dcl3 cell line, it was of interest to determine whether this gene encodes mRNAs that are alternatively spliced and whether these mRNAs are expressed in a tissue-specific manner. We have isolated a novel, alternatively spliced AATYK mRNA using cDNA library screening and RT-PCR, whose expression is readily detected in the brain but not myeloid cells. Western blot analysis revealed that the AATYK protein was expressed in virtually all regions of the adult rat brain in which neurons are present, including olfactory bulb, forebrain, cortex, midbrain, cerebellum and pons. Immunohistochemical labeling of adult brain sections showed the highest levels of AATYK expression in the cerebellum and olfactory bulb. Expression of AATYK was also up-regulated as a function of RA-induced neuronal differentiation of p19 embryonal carcinoma cells, supporting a role for this protein in mature neurons and neuronal differentiation.

Autocrine secreted insulin-like growth factor-I stimulates MAP kinase-dependent mitogenic effects in human primitive neuroectodermal tumor/medulloblastoma.

Primitive neuroectodermal tumors/medulloblastoma (PNET/MB) have similarities to neuroectodermal progenitor cells of the developing CNS. Since insulin-like growth factor I (IGF-I) exerts pleiotrophic effects on cells in the developing CNS, we evaluated the production, mitogenic effects and signaling pathways of IGF-I in PNET/MB cells and found that IGF-I is an autocrine growth factor in human PNET/MB cell lines tested. Stimulation of DAOY cells by IGF-I led to phosphorylation of its cognate receptor (IGF-IR) and resulted in cell proliferation. These effects of IGF-I were suppressed by IGF-IR blocking antibodies and by PD 98059, MAP kinase pathway inhibitor. The results demonstrate the existence of an autocrine IGF-I/IGF-IR loop and indicate that IGF-I promotes proliferation via MAP kinase pathway.

ZPK inhibits PKA induced transcriptional activation by CREB and blocks retinoic acid induced neuronal differentiation.

Zipper Protein Kinase (ZPK) is a leucine zipper protein localized to the nucleus which exhibits serine-threonine kinase activity and is associated with the stress dependent signal transduction pathway. ZPK forms heterodimers with leucine zipper containing transcription factors such as the cyclic AMP responsive element binding protein (CREB) and Myc. Furthermore ZPK phosphorylates both Myc and CREB. Overexpression of ZPK in NTera-2 human teratocarcinoma cells results in inhibition of PKA induced transcriptional activation by CREB and prevents retinoic acid induced differentiation of the cells to neurons. Our results suggest that ZPK stifles neural differentiation of NT-2 cells partly due to its inhibitory effect on CREB function.

Metallothionein expression in carcinoma of the gallbladder.

AIMS: Metallothioneins (MT) are sulphur-rich, low molecular-weight, intracellular metal-binding proteins with a possible role in carcinogenesis of some human tumours. Metallothionein expression in gallbladder cancer has not been studied previously. METHODS AND RESULTS: Immunohistochemical expression of metallothionein was studied in 42 gallbladders (27 cases of carcinoma of the gallbladder, eight chronic cholecystitis and seven cases of normal gallbladder). Metallothionein expression was significantly higher in cases with carcinoma of the gallbladder (70.37%) as compared to chronic cholecystitis (25%) and normal gallbladders (0%). There was a trend suggestive of increasing MT expression with increasing histological dedifferentiation of carcinoma of the gallbladder. CONCLUSIONS: The increased expression of MT in cases of carcinoma of the gallbladder may represent an increased exposure to heavy metals, which are known carcinogens, and may have a role in gallbladder carcinogenesis. Metallothionein over-expression in carcinoma of the gallbladder may be relevant to the poor prognosis and chemoresistance seen in these cases.

cAMP-induced NF-kappaB (p50/relB) binding to a c-myb intronic enhancer correlates with c-myb up-regulation and inhibition of erythroleukemia cell differentiation.

During hexamethylene bisactamide (HMBA)-induced differentiation of murine erythroleukemia (MEL) cells erythroid genes are transcriptionally activated while c-myb and several other nuclear proto-oncogenes are down-regulated. Differentiation is inhibited by cAMP analogues and the adenyl cyclase-stimulating agent forskolin. We found that these drugs prevented the late down-regulation of c-myb which is known to be critical for MEL cell differentiation. Since the increase in c-myb mRNA levels was due to increased mRNA transcription, we examined the transcription factors NF-kappaB and AP-1 which have been implicated in the regulation of c-myb expression. Binding of MEL cell nuclear proteins to a NF-kappaB recognition sequence in c-myb intron I was strongly induced by 8-Br-cAMP or forskolin; induction was delayed and correlated with the up-regulation of c-myb. The cAMP-induced NF-kappaB complex contained p50 and RelB; in co-transfection assays, p50 and RelB transactivated a reporter construct containing the c-myb intronic NF-kappaB site upstream of a minimal promoter. 8-Br-cAMP and forskolin also increased the DNA binding activity of AP-1 complexes containing JunB, JunD and c-Fos in MEL cells which could cooperate with NF-kappaB. We conclude that inhibition of MEL cell differentiation by pharmacological doses of cAMP can be explained by the up-regulation of c-myb which is mediated, at least in part, by NF-kappaB p50/RelB heterodimers.

Association of interleukin-1-induced, NF kappa B DNA-binding activity with collagenase gene expression in human gingival fibroblasts.

During earlier examination of interleukin-1 (IL-1)-induced matrix metalloproteinase gene expression in human gingival fibroblasts a highly induced immediate early gene, I kappa B-alpha, a NF kappa B DNA-binding inhibitor, was identified. The aim now was to investigate whether recombinant (r)IL-1 beta induces the stimulation of NF kappa B and its inhibitor proteins in human gingival fibroblasts and to understand if inhibition of its activity affects collagenase gene expression. Primary gingival fibroblasts (human) were treated with rIL-1 beta to determine the effect on NF kappa B-like DNA-binding activity. IL-1 induced the production of steady-state mRNA levels of I kappa B-alpha in the cultured fibroblasts. Nuclear run-on transcription studies demonstrated that rIL-1 induction of I kappa B-alpha may be transcriptionally regulated. Using electrophoretic mobility gel-shift assays it was shown that rIL-1 activates NF kappa B-like, DNA-binding activity in these fibroblasts. NF kappa B-like DNA-binding activity was rapidly induced and turned over in gingival fibroblasts with peak activity at 30 min after rIL-1 treatment. Further, treatment with chymotrypsin protease inhibitor and antioxidant inhibitor prevented IL-1-induced, NF kappa B-like, DNA-binding activity and collagenase mRNA production. When coupled with the existence of NF kappa B consensus DNA-binding sites on the collagenase gene promoter, these findings suggest that the stimulation of NF kappa B in gingival fibroblasts by rIL-1 could play an important part in the regulation of their collagenase gene expression. The ability of IL-1 to stimulate this expression may define a pivotal role for this cytokine in the pathogenesis of periodontitis.

Cellular factors binding to a novel cis-acting element mediate steroid hormone responsiveness of mouse mammary tumor virus promoter.

Steroid hormone receptors regulate mouse mammary tumor virus (MMTV) gene expression by binding to hormone response DNA elements present in the long terminal repeat. Tissue-specific expression of MMTV is unlikely to be regulated by steroid hormone-receptor complex alone, and mammary cell-specific factors might play a role in the hormone-induced transcriptional activation. In this report we have investigated the function of a novel cis-acting element designated Kil (-204 to -188) which is located adjacent to the distal glucocorticoid response element, in steroid hormone-induced transcription of MMTV. Electrophoretic mobility shift assays indicate that cellular factors bind to the Kil element, and dexamethasone stimulation results in alterations in the binding pattern of proteins in this region. By transient transfection assays using wild type and deletion mutants of the Kil element, we show that this novel cis-acting element is necessary for hormone-induced transcription of MMTV and functions in mammary tumor cells but not in NIH/3T3 cells. Mutagenesis of the Kil sequence suggests that the entire Kil element functioning as one unit is necessary for hormone-induced transcription of MMTV. When placed in the context of heterologous promoters, neither Kil element nor glucocorticoid response element is able to induce significant hormone-induced transcription of MMTV. The presence of both the DNA elements in tandem results in optimal induction of transcription in the presence of steroid hormones. Our results also indicate that the Kil element functions in human breast carcinoma cell lines such as T47D and MCF-7. These results suggest that Kil element in combination with distal glucocorticoid response element functions as a mammary cell-specific enhancer to regulate MMTV transcription.

Oral candidal carriage in young insulin dependent diabetics.

Fifty patients with insulin-dependent diabetes mellitus (IDDM) in the age group of 5-20 years were assessed for oral candidal carriage state and other related oral manifestations. The control group showed 16% Candida carrier state, whereas the IDDM group showed 92% candida carrier state. The candidal count was significantly higher in the IDDM group. Other associated oral manifestations like dry mouth, burning sensation, and painful fissures were also observed in the IDDM subjects.

Keratins as markers in odontogenesis--an immunocytochemical experimental study in rats.

The expression and distribution of keratins within different layers of enamel organs of embryonic and neonatal rats studied by using indirect immunoperoxidase and immunofluorescent techniques in paraffin-embedded tissues employing specific antibodies revealed Keratin positivity in odontoblastic layer, oral epithelium and dental lamina in primitive stages; other odontogenic tissues showed negative reaction.

Regulation of human ornithine decarboxylase expression by the c-Myc.Max protein complex.

The presence of a CACGTG element within a region of the human ornithine decarboxylase (ODC) promoter located at -491 to -474 base pairs 5' to the start site of transcription suggested that the c-Myc.Max protein complex may play a role in the regulation of ODC expression during growth. Electrophoretic mobility shift assays and methylation interference analysis showed that the nuclei of WI-38 cells expressing ODC contained proteins that bound to this region of the ODC gene in a manner that correlated with growth-associated ODC expression. Also, use of antibodies against c-Myc and Max and purified recombinant c-Myc and Max protein in the electrophoretic mobility shift assay confirmed that these proteins can specifically bind this portion of the human ODC promoter. Transient transfection studies showed that increase in the level of c-Myc and/or Max led to a significant enhancement of expression of a human ODC promoter-CAT reporter construct. Moreover, treatment of actively growing WI-38 cells with an antisense oligomer to c-Myc reduced the amount of endogenous protein complex formed and the amount of endogenous ODC mRNA expressed. These studies show that the c-Myc.Max protein complex plays a role in the transcriptional regulation of human ODC in vivo.

Mutational analysis of Max: role of basic, helix-loop-helix/leucine zipper domains in DNA binding, dimerization and regulation of Myc-mediated transcriptional activation.

The Max protein forms a heterodimeric complex with the Myc family of proteins and binds to DNA in a sequence-specific manner. We investigated the role of the helix-loop-helix (HLH), leucine zipper (LZ) and basic domains of Max in protein complex formation, DNA-binding activity and transcriptional regulation. We mutagenized the basic, HLH and LZ domains of Max and studied the ability of the normal and mutant proteins to bind to DNA as both homo- and heterodimers and their ability to heterodimerize with Myc. Helix-1 and helix-2 regions of Max were found to be critical for homodimer formation and subsequent DNA binding, while the LZ was essential for heterodimer formation. In transient transfection assays the Myc protein functioned as a transcriptional activator while Max protein repressed the trans-activation observed with Myc.

The cellular proto-oncogene product Myb acts as transcriptional activator of the long terminal repeat of human T-lymphotropic virus type I.

The proto-oncogene c-myb encodes a nuclear transcription factor that binds to DNA in a sequence-specific manner and activates transcription of several viral and cellular genes. Expression of the c-myb gene is induced in mitogen- and/or antigen-stimulated T lymphocytes, which are also the preferential target cells of human T-lymphotropic virus type I (HTLV-I) in vivo and in vitro. We report here that Myb binds to the HTLV-I long terminal repeat (LTR) in four different regions in a sequence-specific manner. Electrophoretic mobility shift assay using labeled LTR fragments as well as labeled double-stranded oligonucleotides show that there are two high-affinity and two low-affinity Myb-binding sites present in the HTLV-I LTR. DNase I footprinting analysis and oligonucleotide competition experiments indicate that this binding is sequence specific. Cotransfection experiments in HeLa cells, using a Myb expression vector and chloramphenicol acetyltransferase reporter gene linked to the HTLV-I LTR, show that Myb activates HTLV-I LTR-mediated transcription by a factor of four-to sixfold. Thus, in HTLV-I-infected T cells, Myb protein binding to the HTLV-I LTR may constitute one of the signal that regulate HTLV-I transcription in vivo.

Myb protein binds to human immunodeficiency virus 1 long terminal repeat (LTR) sequences and transactivates LTR-mediated transcription.

The protooncogene c-myb encodes a nuclear transcription factor that binds to DNA in a sequence-specific manner and transactivates transcription of several viral and cellular genes. The expression of c-myb is induced in mitogen-stimulated peripheral blood lymphocytes and is constitutively expressed in several CD4+ T-cell and myeloid cell lines, all of which constitute excellent targets for human immunodeficiency virus (HIV) infection and replication. We looked for the presence of Myb-binding motifs in human retroviral long terminal repeats (LTRs) and tested for Myb binding to HIV-1 LTR sequences by using a highly purified recombinant Myb protein. Our results show that HIV-1 LTR contains one high-affinity Myb-binding site along with two or more low-affinity binding sites. DNase I protection analysis as well as oligonucleotide competition experiments indicate that this binding is sequence specific. Introduction of purified Myb protein directly into HeLa cells harboring HIV-1 LTR chloramphenicol acetyltransferase vectors indicates that Myb protein transactivates HIV-1 LTR-mediated transcription. Thus, Myb protein binding to HIV LTR sequences may constitute one of the signals that regulates HIV-1 transcription.