Comparison of the effects of an organic and an inorganic form of selenium on a mammary carcinoma cell line

The development of new compounds with greater cancer inhibitory activity and that are well tolerated continues to be a priority in chemoprevention research involving selenium. One compound, 1,-4-phenylene-bis(methylene)selenocyanate (p-XSC), is representative of a series of organoselenium compounds with these characteristics. In this study, the effects of p-XSC on a mouse mammary carcinoma cell line were compared to those of sodium selenite, which has been shown to be growth inhibitory. Treatment with p-XSC caused a 3- to 6-fold greater accumulation of selenium within cells than did treatment with equivalent amounts of selenite and cells were able to better tolerate higher cellular levels of selenium derived from p-XSC. Both compounds resulted in a dose-dependent reduction in cell number after 24 h of exposure. Selenite and p-XSC also caused a dose-dependent increase in cell death by apoptosis. This effect was observed within 5 h of treatment. The effect of p-XSC on apoptosis was more pronounced than that of selenite, especially at the 20 microM level of exposure. The induction of apoptosis by selenium compounds may partially account for their chemopreventive activity.

Human L-ficolin: plasma levels, sugar specificity, and assignment of its lectin activity to the fibrinogen-like (FBG) domain

Ficolins are characterised by the presence of collagen-like and fibrinogen-like (FBG) sequences. Human L-ficolin is synthesised in the liver and secreted into blood circulation. In previous studies, it was shown to bind to N-acetyl-D-glucosamine (GlcNAc). In the present study, its detailed sugar specificity and binding site have been investigated. It was found to bind to GlcNAc and GalNAc (N-acetyl-D-galactosamine) while showing no significant affinity for the precursor sugars. The structure in these molecules which is recognised by L.-ficolin has been deduced to include an amide (-CO-NH-) or similar group. L-Ficolin was digested with collagenase and the collagenase resistant FBG domain was shown to bind to GlcNAc. Its levels in adult and cord blood-derived human plasma were also determined and showed that adult plasma contains approximately three times more L-ficolin than that of newborn babies.

Dextran sulfate sodium-induced colonic histopathology, but not altered epithelial ion transport, is reduced by inhibition of phosphodiesterase activity

Inhibition of phosphodiesterase (PDE) activity is beneficial in models of arthritis and airway inflammation. Here we assessed the ability of PDE inhibitors to modulate colitis by exposing mice to 4% (w/v) dextran sulfate sodium (DSS) drinking water for 5 days with or without rolipram, an inhibitor of PDE type 4, or the nonselective PDE inhibitor, pentoxifylline (both at 5 mg/kg, i.p., twice daily). Controls received saline, vehicle, or drug only. Colonic histology, myeloperoxidase (MPO) and tumor necrosis factor-alpha (TNF-alpha) levels, and epithelial ion transport (baseline and stimulated by electrical nerve stimulation, carbachol, and forskolin) were examined. DSS-treated mice displayed a variable diarrhea, significant histopathology in the mid-distal colon, elevated MPO activity, and reduced (>50%) responses to all three pro-secretory stimuli. Treatment with rolipram, and to a lesser extent pentoxifylline, significantly reduced the severity of the colonic histopathology and MPO levels. Neither PDE inhibitor had any affect on the diminished ion transport events caused by DSS-induced colitis. However, although stimulated ion transport events were still reduced 3 days after DSS treatment, colonic segments from DSS + rolipram-treated mice displayed enhanced recovery in their secretory responsiveness, particularly to carbachol. These findings indicate that specific PDE4 inhibition can significantly reduce the tissue damage that accompanies colitis and enhance recovery of normal colonic function.

Mo2Ga2C: a new ternary nanolaminated carbide

We report the discovery of a new hexagonal Mo₂Ga₂C phase, wherein two Ga layers – instead of one – are stacked in a simple hexagonal arrangement in between Mo₂C layers.

A hierarchy of SSB protomers in replication protein A

Replication Protein A (RPA) is a heterotrimeric single-stranded DNA-binding protein (SSB) found in all eukaryotic cells. RPA is known to be required for many of the same reactions catalyzed by the homotetrameric SSB of bacteria, but its origin, subunit functions, and mechanism of binding remain a mystery. Here we show that the three subunits of yeast RPA contain a total of four domains with weak sequence similarity to the Escherichia coli SSB protomer. We refer to these four regions as potential ssDNA-binding domains (SBDs). The p69 subunit, which is known to bind ssDNA on its own, contains two SBDs that together confer stable binding to ssDNA. The p36 and p13 subunits each contain a single SBD that does not bind stably, but corresponds to the minimal region required for viability in yeast. Photocross-linking of recombinant protein to ssDNA indicates that an SBD consists of approximately 120 amino acids with two centrally located aromatic residues. Mutation of these aromatic residues inactivates ssDNA binding and is a lethal event in three of the four domains. Finally, we present evidence that the p36 subunit binds ssDNA, as part of the RPA complex, in a salt-dependent reaction similar to the wrapping of ssDNA about E. coli SSB. The results are consistent with the notion that RPA arose by duplication of an ancestral SSB gene and that tetrameric ssDNA-binding domains and higher order binding are essential features of cellular SSBs.

The human fibroblast growth factor receptor genes: a common structural arrangement underlies the mechanisms for generating receptor forms that differ in their third immunoglobulin domain

To determine the mechanisms by which multiple forms of fibroblast growth factor (FGF) receptors are generated, we have mapped the arrangement of exons and introns in the human FGF receptor 1 (FGFR 1) gene (flg). We found three alternative exons encoding a portion of the third immunoglobulin (Ig)-like domain of the receptor. One of these alternatives encodes a sequence that is part of a secreted form of FGFR 1. The other two encode sequences that are likely part of transmembrane forms of FGFR 1. One of these forms has not been previously reported in published cDNAs. Also, we have determined the structural organization of a portion of the human FGFR 2 gene (bek) and found a similar arrangement of alternative exons for the third Ig-like domain. The arrangement of these genes suggests that there are conserved mechanisms governing the expression of secreted FGF receptors as well as the expression of at least two distinct membrane-spanning forms of the FGF receptors. The diverse forms appear to be generated by alternative splicing of mRNA and selective use of polyadenylation signals.

The basic helix-loop-helix transcription factor capsulin controls spleen organogenesis

Formation of numerous internal organs involves reciprocal epithelial-mesenchymal signaling and subsequent patterning and growth of the organ primordium. Capsulin is a basic helix-loop-helix transcription factor expressed in mesenchymal cells that encapsulate the epithelial primordia of internal organs, including the kidney and lung, as well as the epicardium, which gives rise to the coronary arteries. Capsulin is also expressed in the mesothelium that gives rise to the spleen. We demonstrate that mice homozygous for a capsulin null mutation fail to form a spleen. The homeobox genes Hox11 and Bapx1, shown previously to be essential regulators of spleen organogenesis, and a lacZ reporter introduced into the capsulin locus, were expressed in the early splenic primordium, derived from the splanchnic mesoderm, of homozygous mutant embryos. However, this primordium failed to develop beyond an initial group of precursor cells and underwent rapid apoptosis. The phenotype of capsulin mutant mice demonstrates that capsulin acts within a subpopulation of splanchnic mesodermal cells to control an essential early step in spleen organogenesis that is likely to represent a point of regulatory convergence of the capsulin, Hox11, and Bapx1 genes.

Cell and molecular biology of intervertebral disc degeneration: current understanding and implications for potential therapeutic strategies

Intervertebral disc degeneration (IDD) is a chronic, complex process associated with low back pain; mechanisms of its occurrence have not yet been fully elucidated. Its process is not only accompanied by morphological changes, but also by systematic changes in its histological and biochemical properties. Many cellular and molecular mechanisms have been reported to be related with IDD and to reverse degenerative trends, abnormal conditions of the living cells and altered cell phenotypes would need to be restored. Promising biological therapeutic strategies still rely on injection of active substances, gene therapy and cell transplantation. With advanced study of tissue engineering protocols based on cell therapy, combined use of seeding cells, bio-active substances and bio-compatible materials, are promising for IDD regeneration. Recently reported progenitor cells within discs themselves also hold prospects for future IDD studies. This article describes the background of IDD, current understanding and implications of potential therapeutic strategies.

Mortality from traumatic brain injury

It is the general sense that mortality has been decreasing in recent years compared to earlier studies described by the NIH traumatic coma data bank. We studied mortality during the period of 1984 to 1996 to determine if indeed mortality from severe traumatic brain injury was decreasing and to identify factors which might account for the reduction. The study population (N = 1839) consisted of severely head injured patients extracted retrospectively from the TCDB (635), MCV (382), and 822 patients from clinical trial databases conducted in the United States. Mortality was obtained from each of the databases for the age range form 16 to 65. Penetrating injury and treatment groups in the clinical trial databases were excluded. Mortality in the year 1984 equaled 39% and gradually decreased to a level of 27% in 1996. When adjusting for age, motor score and pupil reaction, the mortality of the period from 1984 to 1987 was significantly higher (p < 0.05) than that of the period 1988 to 1996. During the period 1984 through 1996, mortality from severe brain injury steadily declined. Factors other than age, motor score and pupil reactivity over time are responsible for this reduction. This reduction over time is an important factor for prognostic modeling of TBI.

Monomethyl selenium--specific inhibition of MMP-2 and VEGF expression: implications for angiogenic switch regulation

Previous work suggested that antiangiogenic activity may be a novel mechanism contributing to the cancer chemopreventive activity of selenium (Se). Because methylselenol has been implicated as an in vivo active chemopreventive Se metabolite, experiments were conducted to test the hypothesis that this metabolite pool might inhibit the expression of matrix metalloproteinase-2 (MMP-2) by vascular endothelial cells and of vascular endothelial growth factor (VEGF) by cancer epithelial cells, two proteins critical for angiogenesis and its regulation. In human umbilical vein endothelial cells (HUVECs), zymographic analyses showed that short-term exposure to methylseleninic acid (MSeA) and methylselenocyanate (MSeCN), both immediate methylselenol precursors, decreased the MMP-2 gelatinolytic activity in a concentration-dependent manner. In contrast, Se forms that enter the hydrogen selenide pool lacked any inhibitory effect. The methyl Se inhibitory effect on MMP-2 was cell dependent because direct incubation with Se compounds in the test tube did not result in its inactivation. Immunoblot and enzyme-linked immunosorbent assay analyses showed that a decrease of the MMP-2 protein level largely accounted for the methyl Se-induced reduction of gelatinolytic activity. The effect of MSeA on MMP-2 expression occurred within 0.5 h of exposure and preceded MSeA-induced reduction of the phosphorylation level of mitogen-activated protein kinases (MAPKs) 1 and 2 (approximately 3 h) and endothelial apoptosis (approximately 25 h). In addition to these biochemical effects in monolayer culture, MSeA and MSeCN exposure decreased HUVEC viability and cell retraction in a three-dimensional context of capillary tubes formed on Matrigel, whereas comparable or higher concentrations of selenite failed to exert such effects. In human prostate cancer (DU145) and breast cancer (MCF-7 and MDA-MB-468) cell lines, exposure to MSeA but not to selenite led to a rapid and sustained decrease of cellular (lysate) and secreted (conditioned medium) VEGF protein levels irrespective of the serum level (serum-free medium vs. 10% fetal bovine serum) in which Se treatments were carried out. The concentration of MSeA required for suppressing VEGF expression was much lower than that needed for apoptosis induction. Taken together, the data support the hypothesis that the monomethyl Se pool is a proximal Se for inhibiting the expression of MMP-2 and VEGF and of angiogenesis. The data also indicate that the methyl Se-specific inhibitory effects on these proteins are rapid and primary actions, preceding or independent of inhibitory effects on mitogenic signaling at the level of MAPK1/2 and on cell growth and survival.

Requirement for cell-to-cell contact in Epstein-Barr virus infection of nasopharyngeal carcinoma cells and keratinocytes

Two nasopharyngeal carcinoma (NPC) cell lines and one keratinocyte cell line could be infected with Epstein-Barr virus (EBV) by cocultivation with virus-producing cells but not by cell-free virus. Using porous culture inserts to manipulate the cell-to-cell contact, we demonstrated that contact between EBV donor B cells and EBV recipient epithelial cells was required for the infection. Cell-to-cell contact not only provided a CR2-independent route of infection but also enhanced CR2-mediated infection in a synergistic manner. Activity of two EBV promoters (Cp and Wp) and expression of EBNA2 were detected in the infected population. A small proportion of the infected cells spontaneously entered an EBV lytic state, which could be induced prominently by chemical treatment. This study provides information on how EBV may infect epithelial cells in vivo, such as at the onset of NPC development.

Localization of the K(+)-Cl(-) cotransporter, KCC3, in the central and peripheral nervous systems: expression in the choroid plexus, large neurons and white matter tracts

Na(+)-independent K(+)-Cl(-) cotransporters function in the regulation of cell volume, control of CNS excitability and epithelial ion transport. Several K(+)-Cl(-) cotransporter isoforms are expressed in the nervous system, and KCC3 in particular is expressed at significant levels in both the brain and spinal cord. The cellular localization of this transporter has, however, not been determined. In this study, we generated a polyclonal antibody against the KCC3 cotransporter in order to characterize and localize this protein in the brain. Western blot analysis of mouse kidney and brain demonstrated KCC3 proteins of different size, 150 and 170kDa, respectively; this disparity remained after deglycosylation. Northern blot confirmed the presence of two distinct forms of KCC3, KCC3a and KCC3b, generated by the inclusion of different first coding exons. KCC3a predominates in the brain, whereas KCC3b is more abundant in the kidney. Western blots with membrane protein from dissected mouse brain revealed abundant expression in all brain regions examined: the cerebral cortex, hippocampus, diencephalon, brainstem and cerebellum. The spinal cord showed the highest levels of KCC3 expression, whereas peripheral nerves did not contain immunoreactive KCC3 protein. Western blot analysis of whole brain from rats of various ages indicated increasing expression in the postnatal period, concurrent with CNS maturation and myelination. Immunofluorescence studies demonstrated strong signal in myelinated tracts of the spinal cord, consistent with individual myelin sheaths. Brain sections also showed white matter enhancement, but also cellular signal consistent with pyramidal neurons and Purkinje cells. The base of the choroid plexus epithelium was also strongly labeled. These data demonstrate the specificity and diversity of KCC3 expression in the mouse CNS.

Gliadin-dependent neuromuscular and epithelial secretory responses in gluten-sensitive HLA-DQ8 transgenic mice

Celiac disease is a gluten intolerance caused by a T-cell response against human leukocyte antigen (HLA)-DQ2 and DQ8-bound gluten peptides. Some subjects experience gastrointestinal symptoms in the absence of villous atrophy. Here we investigate the potential mechanisms of gut dysfunction in gluten-sensitive HLA-DQ8 transgenic mice. HLA-DQ8 mice were sensitized and gavaged with gliadin 3x/wk for 3 wk (G/G). Controls included 1) nonsensitized mice gavaged with rice (C); 2) gliadin-sensitized mice gavaged with rice (G/R); and 3) BSA-sensitized mice gavaged with BSA (BSA/BSA). CD3(+) intraepithelial lymphocyte, macrophage, and FOX-P3-positive cell counts were determined. Acetylcholine release, small intestinal contractility, and epithelial ion transport were measured. Gut function was investigated after gluten withdrawal and in HLA-DQ6 mice. Intestinal atrophy was not observed in G/G mice. Recruitment of intraepithelial lymphocyte, macrophages, and FOX-P3+ cells were observed in G/G, but not in C, G/R, or BSA/BSA mice. This was paralleled by increased acetylcholine release from the myenteric plexus, muscle hypercontractility, and increased active ion transport in G/G mice. Changes in muscle contractility normalized in DQ8 mice after a gluten withdrawal. HLA-DQ6 controls did not exhibit the abnormalities in gut function observed in DQ8 mice. Gluten sensitivity in HLA-DQ8 mice induces immune activation in the absence of intestinal atrophy. This is associated with cholinergic dysfunction and a prosecretory state that may lead to altered water movements and dysmotility. The results provide a mechanism by which gluten could induce gut dysfunction in patients with a genetic predisposition but without fully evolved celiac disease.

An anatomic study of the thickness of the occipital bone. Implications for occipitocervical instrumentation

STUDY DESIGN

The authors measured the thickness and quality of occipital bone regions to determine screw placement during occipitocervical fusion and described the projection of the posterior dural venous sinuses.

OBJECTIVE

This study provides anatomic data relevant to areas of screw placement into the occiput during occipitocervical fixation.

SUMMARY OF BACKGROUND DATA

Few reports exist regarding the morphometrics of the occipital bone and intracranial structures relevant to occipitocervical fusion.

METHOD

The thickness of the posterior inferior occipital bone was measured relative to a 10 x 5 cm grid. Sections were evaluated grossly and histologically. The projections of the posterior dural venous sinuses were determined by direct measurements.

RESULTS

The maximum thickness of the occipital bone, which ranged from 11.5 to 15.1 mm in males and from 9.7 to 12.0 mm in females, was at the level of the external occipital protuberance. The occipital bone was thicker than 8 mm in an area extending laterally from the external occipital protuberance for 23 mm and consisted of dense cortical bone with little or no diploic bone. The projection of most of the torcula on the external surface of the occipital bone was located superior to the center of the external occipital protuberance (mean, 12.6 mm superior and 4.7 mm inferior to external occipital protuberance), whereas that of the transverse sinus was distributed more evenly above and below the external occipital protuberance (mean, 7.3 mm superior and 6.5 mm inferior).

CONCLUSIONS

Screws that are 8-mm long may be inserted in the region of the superior nuchal line (Level 0) extending 2 cm laterally from the center of the external occipital protuberance, 1 cm from the midline at a level 1 cm inferior to the external occipital protuberance (Level 1), and 0.5 cm from the midline at a level 2 cm inferior to the external occipital protuberance (Level 2). The major dural venous sinuses are situated immediately beneath the thickest regions of the occiput and are at risk of penetrative injury during screw placement.

PATRIC: the VBI PathoSystems Resource Integration Center

The PathoSystems Resource Integration Center (PATRIC) is one of eight Bioinformatics Resource Centers (BRCs) funded by the National Institute of Allergy and Infection Diseases (NIAID) to create a data and analysis resource for selected NIAID priority pathogens, specifically proteobacteria of the genera Brucella, Rickettsia and Coxiella, and corona-, calici- and lyssaviruses and viruses associated with hepatitis A and E. The goal of the project is to provide a comprehensive bioinformatics resource for these pathogens, including consistently annotated genome, proteome and metabolic pathway data to facilitate research into counter-measures, including drugs, vaccines and diagnostics. The project's curation strategy has three prongs: ‘breadth first’ beginning with whole-genome and proteome curation using standardized protocols, a ‘targeted’ approach addressing the specific needs of researchers and an integrative strategy to leverage high-throughput experimental data (e.g. microarrays, proteomics) and literature. The PATRIC infrastructure consists of a relational database, analytical pipelines and a website which supports browsing, querying, data visualization and the ability to download raw and curated data in standard formats. At present, the site warehouses complete sequences for 17 bacterial and 332 viral genomes. The PATRIC website () will continually grow with the addition of data, analysis and functionality over the course of the project.

Detection and characterization of an early folding intermediate of T4 lysozyme using pulsed hydrogen exchange and two-dimensional NMR

Two-dimensional 1H-15N NMR techniques combined with pulsed hydrogen-deuterium exchange have been used to characterize the folding pathway of T4 lysozyme. In the unfolded state, there is little differential protection of the various amides from hydrogen exchange. In the native folded structure, 84 amides of the 164 residues are sufficiently spectrally resolved and protected from solvent exchange to serve as probes of the folding pathway. These probes are located in both the N-terminal and C-terminal domains of the native folded structure of the protein. The studies described here show that at least one intermediate is formed early during refolding at low denaturant concentrations. This intermediate (or intermediates) forms very rapidly (within the 10-ms temporal resolution of our mixing device) under the conditions used and is completed at least 10 times faster than the overall folding event. The intermediate(s) protect(s) from exchange a subset of amides in the N-terminal and C-terminal regions of the protein. In the final folded states these protected regions correspond to two alpha-helices and a beta-sheet region. These amides are protected from exchange by factors between 20 and 200 as compared to the fully unfolded protein. Protection of this magnitude is consistent with the formation of somewhat exposed secondary structure in these regions and could represent a "molten globule"-like or a "framework"-like structure for the intermediate(s) in which specific parts of the sequence form isolated secondary structures that are not stabilized by extensive tertiary interactions.

A model of a segmental oscillator in the leech heartbeat neuronal network

We modeled a segmental oscillator of the timing network that paces the heartbeat of the leech. This model represents a network of six heart interneurons that comprise the basic rhythm-generating network within a single ganglion. This model builds on a previous two cell model (Nadim et al., 1995) by incorporating modifications of intrinsic and synaptic currents based on the results of a realistic waveform voltage-clamp study (Olsen and Calabrese, 1996). Due to these modifications, the new model behaves more similarly to the biological system than the previous model. For example, the slow-wave oscillation of membrane potential that underlies bursting is similar in form and amplitude to that of the biological system. Furthermore, the new model with its expanded architecture demonstrates how coordinating interneurons contribute to the oscillations within a single ganglion, in addition to their role of intersegmental coordination.

Origin, nature, and some functional considerations of intraventricular macrophages, with special reference to the epiplexus cells

Intraventricular macrophages encompass the supraependymal, free-floating, and epiplexus (Kolmer) cells; the supraependymal cells lie in close apposition to the ventricular ependyma, the epiplexus cells are closely associated with the choroid plexus epithelium, and the free-floating cells are at a variable distance from the epithelial surface. Although the three cell types are regarded as one cellular entity, the epiplexus cells preponderate. On scanning electron microscopy, the epiplexus cells display diverse morphological forms, ranging from round to bipolar to stellate, and bear a variable number of cytoplasmic processes. Transmission electron microscopy shows the presence of large numbers of lysosomes. The phagocytic nature of epiplexus cells is shown by their intense staining for nonspecific esterase and active uptake of tracers, e.g., horseradish peroxidase and rhodamine isothiocynate, administered intravenously or intraperitoneally. The mode of entry of these tracers in the cerebral ventricles is by way of transepithelial transport. In rats, the population of intraventricular macrophages increases steadily after birth until 17 days of age; thereafter, their cell population remains relatively unchanged. The early upsurge is attributed to proliferation of residential cells and/or influx of circulating monocytes/stromal macrophages through the process of "emperipolesis." The immunophenotypic features of intraventricular macrophages are consistent with other mononuclear phagocytes being immunoreactive for OX-42, OX-18, OX-6, and OX-1 and ED1 for the detection of CR3 receptors, MHC class I and II antigens, leucocyte common antigen, and macrophage antigen, respectively. The expression of these antigens is noticeably enhanced following the injection of lipopolysaccharide (LPS) into postnatal rats. Remarkably, the intraventricular macrophages are induced to express MHC class II (Ia) antigen after LPS or interferon-gamma injections. Furthermore, the expression of transferrin receptors as detected with OX-26 is also upregulated after these treatments. Epiplexus cells are also elicited to display a de novo expression of nitric oxide synthase-like immunoreactivity following intracerebral injection of LPS. They also respond vigorously to a single nonpenetrative blast. Results of our series of studies suggest that, besides their primary function as scavenger cells, the intraventricular macrophages partake in possible immunological responses and iron regulation in the ventricular system or the brain as a whole.

Downregulation of miR-221/222 enhances sensitivity of breast cancer cells to tamoxifen through upregulation of TIMP3

Aberrantly expressed microRNAs (miRNAs) are involved in breast tumorigenesis. It is still unclear if and how miRNAs-221/222 are implicated in breast cancer and the resistance to estrogen receptor modulator tamoxifen. We investigated the roles and mechanisms of miR-221/222 in breast cancer cells, particularly in modulating response to tamoxifen therapy. MCF-7 and MDA-MB-231 breast cancer cells were transfected with antisense oligonucleotides AS-miR-221 and AS-miR-222 and their expression of miR-221 and miR-222 was assessed. The correlation of miR-221/222 with tissue inhibitor of metalloproteinase-3 (TIMP3) expression was investigated by fluorescence quantitative PCR and western blotting analysis. The therapeutic sensitivity of these cells, transfected and untransfected, to tamoxifen was determined. Transfection of AS-miR-221 and AS-miR-222 dramatically inhibited expression of miR-221 and miR-222, respectively, in both MCF-7 and MDA-MB-231 cells (P<0.05-0.01). Downregulation of miR-221/222 significantly increased the expression of TIMP3 compared with controls (P<0.05-0.01). The viability of estrogen receptor (ER)-positive MCF-7 cells transfected with AS-miR-221 or/and AS-miR-222 was significantly reduced by tamoxifen (P<0.05-0.01). We have demonstrated for the first time that suppression of miRNA-221/222 increases the sensitivity of ER-positive MCF-7 breast cancer cells to tamoxifen. This effect is mediated through upregulation of TIMP3. These findings suggest that upregulation of TIMP3 via inhibition of miRNA-221/222 could be a promising therapeutic approach for breast cancer.

Subcellular localization of the alpha and beta subunits of the acute myeloid leukemia-linked transcription factor PEBP2/CBF

Each of the two human genes encoding the alpha and beta subunits of a heterodimeric transcription factor, PEBP2, has been found at the breakpoints of two characteristic chromosome translocations associated with acute myeloid leukemia, suggesting that they are candidate proto-oncogenes. Polyclonal antibodies against the alpha and beta subunits of PEBP2 were raised in rabbits and hamsters. Immunofluorescence labeling of NIH 3T3 cells transfected with PEBP2 alpha and -beta cDNAs revealed that the full-size alpha A1 and alpha B1 proteins, the products of two related but distinct genes, are located in the nucleus, while the beta subunit is localized to the cytoplasm. Deletion analysis demonstrated that there are two regions in alpha A1 responsible for nuclear accumulation of the protein: one mapped in the region between amino acids 221 and 513, and the other mapped in the Runt domain (amino acids 94 to 221) harboring the DNA-binding and the heterodimerizing activities. When the full-size alpha A1 and beta proteins are coexpressed in a single cell, the former is present in the nucleus and the latter still remains in the cytoplasm. However, the N- or C-terminally truncated alpha A1 proteins devoid of the region upstream or downstream of the Runt domain colocalized with the beta protein in the nucleus. In these cases, the beta protein appeared to be translocated into the nucleus passively by binding to alpha A1. The chimeric protein containing the beta protein at the N-terminal region generated as a result of the inversion of chromosome 16 colocalized with alpha A1 to the nucleus more readily than the normal beta protein. The implications of these results in relation to leukemogenesis are discussed.

Distribution, isolation, host specificity, and diversity of cyanophages infecting marine Synechococcus spp. in river estuaries

The abundance of cyanophages infecting marine Synechococcus spp. increased with increasing salinity in three Georgia coastal rivers. About 80% of the cyanophage isolates were cyanomyoviruses. High cross-infectivity was found among the cyanophages infecting phycoerythrin-containing Synechococcus strains. Cyanophages in the river estuaries were diverse in terms of their morphotypes and genotypes.

Characterization and stability of hydroxyapatite coatings prepared by an electrodeposition and alkaline-treatment process

Hydroxyapatite (HA) coatings on titanium alloy substrates were prepared by an alkaline treatment of electrodeposited precursors. The structure, residual stress, and bond strength of the coatings were investigated. Test results showed that the coatings processed in this study exhibited fairly low tensile residual stress, high crystallinity, and were free of an amorphous phase. The bond strength of the coatings increased with the decrease of current density in the range of 0.2-15 mA/cm(2), and reached 14 MPa at 0.2 mA/cm(2). Evaluation of the coatings was performed together with the evaluation of the plasma-sprayed HA coatings immersed in distilled water. It was revealed that the dissolution and bond strength degradation of the coatings were much lower than those of the plasma-sprayed HA coatings.