Cellular response to conditional expression of the hepatitis B virus precore and core proteins in cultured hepatoma (Huh-7) cells

BACKGROUND

The expression of the hepatitis Be antigen (HBeAg) is one of several strategies used by hepatitis B virus (HBV) to ensure persistence. The HBeAg may function as a toleragen in utero and has been shown to regulate the host's immune response.

AIM

The aim of this study was to examine the effect of the HBV precore and core protein on cellular gene expression in the hepatoma cell line Huh-7.

STUDY DESIGN

Huh-7 cells with tight regulated expression of the HBV core or precore protein were produced using the Tet-Off tetracycline gene expression system. Changes in cellular gene expression in response to core/precore expression compared to Huh-7 cells not expressing the proteins were determined using a commercial high-density oligonucleotide array (Affymetrix Hu95A GeneChip) containing probes for 12,626 full-length human genes.

RESULTS

Analysis of differential mRNA gene expression profiles at 7 days post precore and core expression revealed 45 and 5 genes, respectively, with mRNA changes greater than three-fold. The most striking feature was in Huh-7 cells expressing the precore protein in which 43/45 genes were downregulated 3-11-fold. These included genes that encoded products that regulate transcription/DNA binding proteins, cell surface receptors, cell-cycle/nucleic acid biosynthesis and intracellular signalling and trafficking. The only known gene, which was upregulated encoded a cytoskeletal protein. For the core cell line, 4/5 genes were downregulated 3-15-fold upon core induction and included genes that encoded products that affect intermediary metabolism, cell surface receptors and intracellular signalling. The one gene, which was upregulated was a cytokine gene.

CONCLUSION

The results of this study show that HBV precore protein has a much greater effect on cellular gene expression in comparison to the core protein, suggesting that core and precore proteins may have diverse effects on cellular functions and equally different roles in modulating HBV pathogenesis.

The pathophysiology of HOX genes and their role in cancer

The HOM-C clustered prototype homeobox genes of Drosophila, and their counterparts, the HOX genes in humans, are highly conserved at the genomic level. These master regulators of development continue to be expressed throughout adulthood in various tissues and organs. The physiological and patho-physiological functions of this network of genes are being avidly pursued within the scientific community, but defined roles for them remain elusive. The order of expression of HOX genes within a cluster is co-ordinated during development, so that the 3' genes are expressed more anteriorly and earlier than the 5' genes. Mutations in HOXA13 and HOXD13 are associated with disorders of limb formation such as hand-foot-genital syndrome (HFGS), synpolydactyly (SPD), and brachydactyly. Haematopoietic progenitors express HOX genes in a pattern characteristic of the lineage and stage of differentiation of the cells. In leukaemia, dysregulated HOX gene expression can occur due to chromosomal translocations involving upstream regulators such as the MLL gene, or the fusion of a HOX gene to another gene such as the nucleoporin, NUP98. Recent investigations of HOX gene expression in leukaemia are providing important insights into disease classification and prediction of clinical outcome. Whereas the oncogenic potential of certain HOX genes in leukaemia has already been defined, their role in other neoplasms is currently being studied. Progress has been hampered by the experimental approach used in many studies in which the expression of small subsets of HOX genes was analysed, and complicated by the functional redundancy implicit in the HOX gene system. Attempts to elucidate the function of HOX genes in malignant transformation will be enhanced by a better understanding of their upstream regulators and downstream target genes.

The fate and removal of triclosan during wastewater treatment

This work examines the variation in removal efficiency of triclosan in wastewater treatment works in the United Kingdom between November 2003 and April 2004. Concentrations of triclosan were measured at set points within three different types of wastewater treatment works: rotating biological contactors, trickling filters, and activated sludge. Overall removal of triclosan through these plants ranged from 58 to 96% (rotating biological contactors), 86 to 97% (trickling filter), and 95 to 98% (activated sludge).

Rounded atelectasis in an asbestos exposed worker

The case history is presented of a 51-year-old electrical power worker with a history of asbestos exposure presenting with rounded atelectasis. No other radiological markers of asbestos exposure were present. A documented history of asbestos exposure and exclusion of other causes of rounded atelectasis led to the diagnosis of asbestos related rounded atelectasis. It is important to understand that rounded atelectasis can be an isolated finding due to asbestos exposure. This facilitates investigation of lung masses of unknown etiology and initiation of appropriate follow up of patients at risk for future development of more debilitating asbestos related pathology.

Patient, carer and health service outcomes of nurse-led early discharge after breast cancer surgery: a randomised controlled trial

Patients with breast cancer who require axillary clearance traditionally remain in hospital until their wound drains are removed. Early discharge has been shown to improve clinical outcomes, but there has been little assessment of the psychosocial and financial impact of early discharge on patients, carers and the health service. This study aimed to evaluate the effectiveness of a nurse-led model of early discharge from hospital. Main outcome measures were quality of life and carer burden. Secondary outcomes included patient satisfaction, arm morbidity, impact on community nurses, health service costs, surgical cancellations and in-patient nursing dependency. A total of 108 patients undergoing axillary clearance with mastectomy or wide local excision for breast cancer were randomised to nurse-led early discharge or conventional stay. Nurse-led early discharge had no adverse effects on quality of life or patient satisfaction, had little effect on carer burden, improved communication between primary and secondary care, reduced cancellations and was safely implemented in a mixed rural/urban setting. In total, 40% of eligible patients agreed to take part. Nonparticipants were significantly older, more likely to live alone and had lower emotional well being before surgery. This study provides further evidence of the benefits of early discharge from hospital following axillary clearance for breast cancer. However, if given the choice, most patients prefer to stay in hospital until their wound drains are removed.

Non spiral and spiral (helical) flow patterns in stenoses. In vitro observations using spin and gradient echo magnetic resonance imaging (MRI) and computational fluid dynamic modeling

AIM

Physiological blood flow patterns are themselves poorly understood despite their impact on arterial disease. Stable spiral (helical) laminar flow (SLF) has been observed in normal subjects. The purpose of the present study is to develop a method of magnetic resonance (MR) flow pattern visualization and to analyze spiral and non-spiral flow patterns with and without luminal narrowing in vitro. The flow conditions were then modeled using computational fluid dynamics (Star-CD).

METHODS

Laminar integrity was examined in a flow-rig using spin and gradient echo magnetic resonance imaging (MRI) in non-stenosed and stenosed conduits in the presence of non-spiral and spiral flow.

RESULTS

No difference was observed in a non-stenosed conduit between non-spiral and spiral flow. In the presence of a stenosis spiral flow preserves flow velocity coherence whereas non-spiral flow increasingly lost coherence beginning proximal to the stenosis. Computational fluid dynamic modeling of the in vitro experiment showed marked differences between the 2 flow patterns. Non-spiral flow produced greater inwardly directed forces just beyond the stenosis and greater outward pressures at more distal sites. The near wall turbulent energy was up to 700% less with spiral flow over non-spiral flow beyond the stenosis.

CONCLUSIONS

Spiral flow appears to offer clear flow profile stabilizing advantages over non-spiral flow, by significantly reducing the turbulence caused by a stenosis. Spiral flow also produces lower forces acting on the vessel wall.

Thrombopoietin, flt3-ligand and c-kit-ligand modulate HOX gene expression in expanding cord blood CD133 cells

Haemopoietic stem/progenitor cell (HSPC) development is regulated by extrinsic and intrinsic stimuli. Extrinsic modulators include growth factors and cell adhesion molecules, whereas intrinsic regulation is achieved with many transcription factor families, of which the HOX gene products are known to be important in haemopoiesis. Umbilical cord blood CD133+ HSPC proliferation potential was tested in liquid culture with 'TPOFLK' (thrombopoietin, flt-3 ligand and c-kit ligand, promoting HSPC survival and self-renewal), in comparison to 'K36EG' (c-kit-ligand, interleukins-3 and -6, erythropoietin and granulocyte colony-stimulating factor, inducing haemopoietic differentiation). TPOFLK induced a higher CD133+ HSPC proliferation (up to 60-fold more, at week 8) and maintained a higher frequency of the primitive colony-forming cells than K36EG. Quantitative polymerase chain reaction analysis revealed opposite expression patterns for specific HOX genes in expanding cord blood CD133+ HSPC. After 8 weeks in liquid culture, TPOFLK increased the expression of HOX B3, B4 and A9 (associated with uncommitted HSPC) and reduced the expression of HOX B8 and A10 (expressed in committed myeloid cells) when compared to K36EG. These results suggest that TPOFLK induces CD133+ HSPC proliferation, self-renewal and maintenance, up-regulation of HOX B3, B4 and A9 and down-regulation of HOX B8 and A10 gene expression.

Phototransposition reactions of arylboronate esters in acetonitrile and 2,2,2-trifluoroethanol

The phototransposition (para, meta, ortho) reactions of the arylboronate esters 4-, 3-, and 2-(4',4',5',5'-tetramethyl-1',3',2'-dioxaborolanyl)toluenes (1, 2, and 3, respectively) in both acetonitrile and 2,2,2-trifluoroethanol (TFE) using 254 nm irradiation have been examined. The irradiations resulted in steady-state compositions of para (5%), meta (19%), and ortho (76%) isomers in acetonitrile starting from the ortho isomer and para (12%), meta (54%), and ortho (35%) isomers in TFE starting from the para isomer. Analysis of the (13)C NMR spectrum of the product mixture obtained from the photochemistry of the para isomer selectively deuterated at C3 and C5 (1d(2)()) revealed that the boron-substituted carbon is the active one in the phototransposition reactions in both acetonitrile and TFE. Similar results were observed for irradiations of 1 in cyclohexane. Fluorescence spectra, singlet-state lifetimes, and Stern-Volmer quenching of fluorescence with 2,3-dimethyl-1,3-butadiene indicated that the excited singlet states of these three isomers were spectroscopic minima and that the excited singlet state was the reactive one for 3 in acetonitrile.

Structure determination of the extracellular xylanase from Geobacillus stearothermophilus by selenomethionyl MAD phasing

Xylanases are hemicellulases that hydrolyze the internal beta-1,4-glycoside bonds of xylan. The extracellular thermostable endo-1,4-beta-xylanase (EC 3.2.1.8; XT6) produced by the thermophilic bacterium Geobacillus stearothermophilus T-6 was shown to bleach pulp optimally at pH 9 and 338 K and was successfully used in a large-scale biobleaching mill trial. The xylanase gene was cloned and sequenced. The mature enzyme consists of 379 amino acids, with a calculated molecular weight of 43 808 Da and a pI of 9.0. Crystallographic studies of XT6 were performed in order to study the mechanism of catalysis and to provide a structural basis for the rational introduction of enhanced thermostability by site-specific mutagenesis. XT6 was crystallized in the primitive trigonal space group P3(2)21, with unit-cell parameters a = b = 112.9, c = 122.7 A. A full diffraction data set for wild-type XT6 has been measured to 2.4 A resolution on flash-frozen crystals using synchrotron radiation. A fully exchanged selenomethionyl XT6 derivative (containing eight Se atoms per XT6 molecule) was also prepared and crystallized in an isomorphous crystal form, providing full selenium MAD data at three wavelengths and enabling phase solution and structure determination. The structure of wild-type XT6 was refined at 2.4 A resolution to a final R factor of 15.6% and an R(free) of 18.6%. The structure demonstrates that XT6 is made up of an eightfold TIM-barrel containing a deep active-site groove, consistent with its 'endo' mode of action. The two essential catalytic carboxylic residues (Glu159 and Glu265) are located at the active site within 5.5 A of each other, as expected for 'retaining' glycoside hydrolases. A unique subdomain was identified in the carboxy-terminal part of the enzyme and was suggested to have a role in xylan binding. The three-dimensional structure of XT6 is of great interest since it provides a favourable starting point for the rational improvement of its already high thermal and pH stabilities, which are required for a number of biotechnological and industrial applications.

Differential expression of 11beta-hydroxysteroid dehydrogenase types 1 and 2 mRNA and glucocorticoid receptor protein during mouse embryonic development

Accumulating evidence suggests that the actions of glucocorticoids in target tissues are critically determined by the expression of not only the glucocorticoid receptor (GR) but also the glucocorticoid-metabolizing enzymes, known as 11beta-hydroxysteroid dehydrogenase types 1 and 2 (11beta-HSD1 and 11beta-HSD2). To gain insight into the role of glucocorticoids in fetal development, the expression patterns of the two distinct 11beta-HSD isozymes and GR were studied in the mouse embryo from embryonic day 12.5 (E12.5, term = E19) to postnatal day 0.5 (P0.5) by in situ hybridization and immunohistochemistry, respectively. 11beta-HSD1 mRNA was detected in the heart as early as E12.5 and maintained thereafter. In the lung and liver, 11beta-HSD1 mRNA was first detected between E14.5 and E16.5, increased to high levels towards term and maintained after birth. Relatively low levels of 11beta-HSD1 mRNA were also detected in the kidney, adrenal glands and gastrointestinal tract at E18.5. However, the mRNA for 11beta-HSD1 was undetectable in all other embryonic tissues including the brain. In contrast, kidney was the only organ that expressed appreciable levels of 11beta-HSD2 mRNA during embryonic life. The level of 11beta-HSD2 mRNA in the kidney increased dramatically in the newborn, which coincided with expression of 11beta-HSD2 mRNA in the whisker follicle, tooth and salivary gland. Distinct from the profiles of 11beta-HSD1 and 11beta-HSD2 mRNA, GR protein was detectable in all tissues at all ages studied except for the thymus, salivary gland, and bone. Taken together, the present study demonstrates that tissue- and developmentally-stage specific expression of 11beta-HSD1 and 11beta-HSD2 as well as GR occurs in the developing mouse embryo, thus highlighting the importance of these two enzymes and GR in regulating glucocorticoid-mediated maturational events in specific tissues during murine embryonic development.

The benefits of support group participation to lung cancer survivors--an evaluation

It has been known for some time that participation in support groups is beneficial for most cancer survivors. Despite this, and even though lung cancer causes more deaths than breast, prostate, and colorectal cancers combined, the number of support groups formed for lung cancer survivors is surprisingly very small. In an effort to understand the lack of lung cancer specific support groups, the Alliance for Lung Cancer Advocacy, Support, and Education (ALCASE) conducted a survey of the facilitators of the lung cancer support groups then known to be in existence in the United States, in addition to a follow-up focus group with the facilitators via teleconference. The results of the survey and the focus group provide a very preliminary look at the value to lung cancer survivors of participating in support groups organized specifically for them. However, much more research is required, not only with the participants of these groups, but also with lung cancer survivors who do not participate, to fully gauge the effects of support group participation on the progress of their disease and on their quality of life.

Adjuvant and neoadjuvant therapy for gastric cancer using epirubicin/cisplatin/5-fluorouracil (ECF) and alternative regimens before and after chemoradiation

Chemoradiation is now used more commonly for gastric cancer following publication of the US Intergroup trial results that demonstrate an advantage to adjuvant postoperative chemoradiotherapy. However, there remain concerns regarding the toxicity of this treatment, the optimal chemotherapy regimen and the optimal method of radiotherapy delivery. In this prospective study, we evaluated the toxicity and feasibility of an alternative chemoradiation regimen to that used in the Intergroup trial. A total of 26 patients with adenocarcinoma of the stomach were treated with 3D-conformal radiation therapy to a dose of 45 Gy in 25 fractions with concurrent continuous infusional 5-fluorouracil (5-FU). The majority of patients received epirubicin, cisplatin and 5-FU (ECF) as the systemic component given before and after concurrent chemoradiation. The overall rates of observed grade 3 and 4 toxicities were 38 and 15%, respectively. GIT grade 3 toxicity was observed in 19% of patients, while haematologic grade 3 and 4 toxicities were observed in 23%. Our results suggest that this adjuvant regimen can be delivered safely and with acceptable toxicity. This regimen forms the basis of several new studies being developed for postoperative adjuvant therapy of gastric cancer.

Amylase-binding proteins A (AbpA) and B (AbpB) differentially affect colonization of rats' teeth by Streptococcus gordonii

Streptococcus gordonii produces two alpha-amylase-binding proteins, AbpA and AbpB, that have been extensively studied in vitro. Little is known, however, about their significance in oral colonization and cariogenicity (virulence). To clarify these issues, weanling specific pathogen-free Osborne-Mendel rats, TAN : SPFOM(OM)BR, were inoculated either with wild-type strains FAS4-S or Challis-S or with strains having isogenic mutations of abpA, abpB, or both, to compare their colonization abilities and persistence on the teeth. Experiments were done with rats fed a sucrose-rich diet containing low amounts of starch or containing only starch. The mutants and wild-types were quantified in vivo and carious lesions were scored. In 11 experiments, S. gordonii was a prolific colonizer of the teeth when rats were fed the sucrose (with low starch)-supplemented diet, often dominating the flora. Sucrose-fed rats had several-fold higher recoveries of inoculants than those eating the sucrose-free, starch-supplemented diet, regardless of inoculant type. The strain defective in AbpB could not colonize teeth of starch-only-eating rats, but could colonize rats if sucrose was added to the diet. Strains defective in AbpA surprisingly colonized better than their wild-types. A double mutant deficient in both AbpA and AbpB (abpA/abpB) colonized like its wild-type. Wild-types FAS4-S and Challis-S had no more than marginal cariogenicity. Notably, in the absence of AbpA, cariogenicity was slightly augmented. Both the rescue of colonization by the AbpB- mutant and the augmentation of colonization by AbpA- mutant in the presence of dietary sucrose suggested additional amylase-binding protein interactions relevant to colonization. Glucosyltransferase activity was greater in mutants defective in abpA and modestly increased in the abpB mutant. It was concluded that AbpB is required for colonization of teeth of starch-eating rats and its deletion is partially masked if rats eat a sucrose-starch diet. AbpA appears to inhibit colonization of the plaque biofilm in vivo. This unexpected effect in vivo may be associated with interaction of AbpA with glucosyltransferase or with other colonization factors of these cells. These data illustrate that the complex nature of the oral environment may not be adequately modelled by in vitro systems.