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Biomedical subjects

Robert Steele

Publications and source records attributed to Robert Steele.

11 recordsLinked to original sources
PubMed2026

Colonoscopy and fecal immunochemical testing versus usual care in diagnostic colorectal cancer screening: the SCREESCO randomized controlled trial.

There is a need to quantify the benefits and harms of colorectal cancer (CRC) screening using primary colonoscopy or fecal immunochemical testing (FIT) compared with usual care with no screening. Guidelines recommend screening in individuals aged 50-75 years using colonoscopy or FIT, and many screening programs use one-sample biennial FIT. Here we compare incidence of diagnosed CRCs and gastrointestinal and cardiovascular events between screening and usual care during the diagnostic phase of the SCREESCO trial. A randomized block method (no masking) assigned 278,280 individuals aged 60 years to once-only colonoscopy, 2 rounds of two-stool FIT with a low cutoff (10 μg g-1 feces) or usual care (control group) in a ratio of 1:6 for colonoscopy versus control and 1:2 for FIT versus control. In the analysis, 31,113 individuals were in the primary colonoscopy arm and 60,267 were in the FIT arm, and there were 186,671 primary colonoscopy controls, of whom 120,521 were also controls for comparison with the FIT arm. After a median follow-up of 4.8 years, the incidence rate of CRC was 107.9 in the colonoscopy arm and 99.9 in controls per 100,000 person-years (incidence rate ratio (IRR): 1.08, 95% confidence interval (CI): 0.91-1.28) and 96.0 in the FIT arm and 103.9 in controls (IRR: 0.92, 95% CI: 0.81-1.05). Rates of stage I-II CRC were higher in the colonoscopy arm (IRR: 1.38, 95% CI: 1.09-1.74) and in the FIT arm (IRR: 1.19, 95% CI: 0.99-1.43) versus controls. Rates of cardiovascular and gastrointestinal events were slightly higher in the intervention arms during the first year and were subsequently more similar to controls. Our findings of an increase in CRC detection implies a benefit of screening while the increase in adverse events suggests some initial harm. ClinicalTrials.gov: NCT02078804 .

Humans↗
PubMed2003

Modulation of human luteinizing hormone beta gene transcription by MIP-2A.

MIP-2A was recently identified as a MBP-1 interacting cellular protein. We have shown previously that MBP-1 acts as a transcriptional repressor. Functional association between MIP-2A and MBP-1 suggests that MIP-2A can act as a cofactor and relieves MBP-1-mediated transcriptional repression. In this study, we report the tissue-specific expression of MIP-2A and its role in the regulation of gene transcription. RNA dot blot analysis of human multiple tissue expression array suggested that MIP-2A is highly abundant in right cerebellum, pituitary, adrenal, and testis but barely detectable in skeletal muscle. Predominant expression of MIP-2A in pituitary tissue led us to investigate whether MIP-2A can transcriptionally regulate luteinizing hormone beta (LHbeta), a pituitary-specific hormone synthesized and secreted from gonadotropic cells. The LHbeta promoter is regulated by the orphan nuclear receptor SF-1 and homeodomain protein Ptx1. Although each factor enhances the LHbeta promoter, coexpression of both results in a strong synergistic activation. Therefore, we examined whether MIP-2A can modulate SF-1- and Ptx1-mediated transcriptional activation. Our results suggested that MIP-2A expression inhibits SF-1- and Ptx1-mediated transactivation of LHbeta promoter. Subsequent analysis demonstrated that MIP-2A physically interacts with both SF-1 and Ptx1, thereby inhibiting transactivation of the LHbeta promoter. Taken together, our results indicate that MIP-2A preferentially expresses in certain tissues, including the pituitary gland, and negatively regulates the LHbeta gene transcription.

Binding Sites↗
PubMed2003

Modulation of interferon expression by hepatitis C virus NS5A protein and human homeodomain protein PTX1.

Hepatitis C virus (HCV) NS5A protein transcriptionally modulates a number of cellular genes. Since there is no evidence of binding of NS5A protein to DNA, it is likely to exert its activity in concert with cellular factor(s). In this study, we have identified a specific interaction of HCV NS5A with homeodomain protein PTX1 of human origin by a yeast two-hybrid interacting cloning system. The authenticity of this interaction was verified by mammalian two-hybrid assay, in vivo co-immunoprecipitation analysis, and from a colocalization study. Recently, murine PTX1 (mPTX1) has been shown to repress virus-induced murine interferonA4 promoter activity. Interferon-à alone or together with ribavirin is the only available therapy for HCV-infected patients. Therefore, we examined whether coexpression of NS5A and human PTX1 (hPTX1) proteins modulate human IFN-à promoter activity. An in vitro reporter assay by transfection of HepG2 cells with NS5A suggested an activation of IFN-à promoter to approximately 20-fold upon Newcastle disease virus (NDV) infection. Under similar experimental conditions, hPTX1-activated IFN-à prompter to approximately sevenfold, unlike mPTX1. However, cotransfection of NS5A and hPTX1 displayed a lower interferon promoter activity, probably for physical association between these two proteins. Subsequent study demonstrated that activation of IFN promoter by NS5A is associated with an increased expression of IRF-3. Further analysis revealed that ectopic expression of NS5A in HepG2 cells enhances endogenous IFN-à secretion and MxA expression upon induction with NDV. However, exogenous expression of hPTX1 did not significantly alter NS5A-mediated function in the stable transfectants. Taken together, these results suggested that the level of endogenous hPTX1 is not sufficient to block the function of NS5A for augmentation of virus-mediated IFN activity in HepG2 cells.

Cell Line↗
PubMed2003

Inhibition of hepatitis C virus protein expression by RNA interference.

Hepatitis C virus (HCV) is a serious human pathogen and an estimated 170 million people are infected worldwide. Current therapeutic regimens have shown limited efficacy against selected genotypes of the virus. The phenomenon of RNA interference can be used to selectively block homologous genes post-transcriptionally, and has revolutionized approaches to study gene function. In this report, we have demonstrated that small interfering RNAs (siRNAs) targeted against NS5A of HCV genotype 1a specifically inhibit NS5A RNA and protein expression in a human hepatoma (HepG2) cell line. Expression of endogenous alpha-actin and the ds-RNA activated serine/threonine kinase-PKR were unaltered, demonstrating that the inhibitory effect observed from siRNA was specific to the HCV NS5A protein. We next examined whether siRNA directed against NS5A could inhibit core protein expression, the first gene product synthesized in virus infected cells due to its localization at the 5' end of the HCV polyprotein. For this purpose, a full-length cDNA clone from HCV (H77, genotype 1a) was used, and results indicated that the introduction of NS5A targeted siRNA resulted in an inhibition of NS5A and core protein expression. Moreover, we observed that this siRNA effectively inhibited NS5A mediated activation of the IL-8 promoter. Taken together, our results demonstrated that siRNA was effective in inhibiting HCV protein expression, and may have therapeutic potential to limit HCV replication in chronically infected patients.

Gene Expression Regulation, Viral↗
PubMed2002

MBP-1 mediated apoptosis involves cytochrome c release from mitochondria.

MBP-1, a cellular factor, appears to be involved in multiple functions, including transcriptional modulation, apoptosis and cell growth regulation. In this study, we have investigated the signaling pathway involved in MBP-1 mediated apoptotic cell death. Human carcinoma cells infected with a replication deficient adenovirus expressing MBP-1 (AdMBP-1) induced apoptosis, when compared with cells infected by replication-defective adenovirus (dl312) as a negative control. Transduction of MBP-1 in carcinoma cells releases cytochrome c from mitochondria into the cytosol leading to activation of procaspase-9, procaspase-3 and PARP cleavage. We previously observed that MBP-1 mediated apoptosis can be protected by Bcl-2, although MBP-1 does not share a homology with the BH domain of the Bcl-2 family member of proteins. To further understand the mechanism of MBP-1 mediated apoptosis, we examined whether MBP-1 modulates the Bcl-2 gene family. Our results demonstrated that human breast carcinoma cells infected with AdMBP-1 selectively reduced Bcl-xL mRNA and protein expression when compared with dl312 infected negative control cells. An in vitro transient reporter assay also suggested repression of the Bcl-x promoter activity by MBP-1. Additional studies indicated that MBP-1 modulates Ets family protein function, thereby downregulating Bcl-xL expression. Taken together, our results suggest that MBP-1 selectively represses Bcl-xL expression in MCF-7 cells and induces mitochondrial involvement in the apoptotic process.

3T3 Cells↗
PubMed2002

Hepatitis C virus NS5A protein impairs TNF-mediated hepatic apoptosis, but not by an anti-FAS antibody, in transgenic mice.

Hepatitis C virus (HCV) is a major etiologic agent of chronic hepatitis worldwide and may lead to the development of hepatocellular carcinoma. However, the mechanism of development of chronic hepatitis or hepatocarcinogenesis by HCV remains unclear. In the present study, we have investigated the effect of nonstructural protein 5A (NS5A) on TNF- and Fas-mediated apoptosis in the liver of transgenic mice. For this purpose, transgenic mice were generated by targeting the HCV NS5A genomic region cloned under the control of a liver-specific apoE promoter. The transgenic animals were phenotypically similar to their normal littermates and did not exhibit a detectable histological change in the liver at 8-12 weeks of age. Intraperitoneal injection of recombinant TNF induced hepatic injury and apoptosis in normal mice. In contrast, transgenic mice expressing NS5A protein were protected against hepatic apoptosis after injection of TNF. However, injection of anti-Fas antibody into transgenic mice did not significantly influence hepatic apoptosis compared to the normal littermates. These results suggested distinct effects of TNF and anti-Fas antibody in transgenic mice expressing NS5A. We subsequently investigated the effect of NS5A in signaling pathways involved in these two cytokine-mediated apoptosis. A physical association between NS5A and TRADD was observed by pull-down assay, coimmunoprecipitation, and colocalization experiments. Furthermore, NS5A prevented the association between TRADD and FADD and blocked TRADD-mediated NF-kappaB activation. Together, our results suggest that NS5A impairs TNF-mediated apoptosis by interfering upstream of the signal transduction pathway and may play a role in HCV-mediated pathogenesis.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Distinct functional role of Hepatitis C virus core protein on NF-kappaB regulation is linked to genomic variation.

Hepatitis C virus (HCV) often causes a prolonged and persistent infection. Sequence divergence in the HCV genome indicates several genotypes and a series of subtypes for this virus. The core protein of HCV has many intriguing functional properties and is implicated as a factor in virus mediated pathogenesis. Nuclear factor kappaB (NF-kappaB), a transcription factor, responds to inflammatory signals, activates the expression of inflammatory mediators, and plays a role in cell proliferation process. In this study, we have investigated NF-kappaB regulation by HCV core protein cloned from three isolates of different genotypes. Our results suggest that core protein from HCV genotype 1a represses NF-kappaB activation, unlike two other core genomic regions from HCV genotype 1b (BK or Taiwan). However, missense mutations in positions (K(9) to R or N(11) to T) of HCV genotype 1a relieve repression of NF-kappaB regulation by core protein. Interestingly, in vitro translation studies suggested that amino acid substitution at position 11 (N-->T) in HCV genotype 1a generated a primary protein product of approximately 17 kDa, smaller than the major approximately 21 kDa protein band apparent in the parental sequence or with one carrying mutation at amino acid position 9 (K-->R). However, the approximately 17 kDa protein did not appear to be involved in NF-kappaB regulation. Taken together, our present data suggest that genomic variation in the core protein determines a distinct functional regulation of NF-kappaB, which may modulate immunnoregulatory molecules early in viral infection.

Amino Acid Sequence↗
PubMed2002

Randomized controlled trial to assess the effectiveness of a primary health care liaison worker in promoting shared care for opiate users.

BACKGROUND: Recent national guidelines emphasize the requirement for all general practitioners to manage drug users within a shared care scheme and suggest that a primary health care liaison worker (PHCLW) may facilitate these arrangements. We undertook a group-randomized, randomized controlled trial to determine the effectiveness of a PHCLW in promoting shared care. METHODS: Primary health care teams in Stockport Health Authority, North West England, were randomly allocated to either an intervention arm, who were offered the services of a PHCLW, or to a control arm, who were offered standard support from the community drug team (CDT). The proportion of CDT clients with a history of regular opiate misuse who were in shared care 12 months after randomization was compared across study arms. RESULTS: Eighteen (24.0 per cent) of the 75 CDT clients in the intervention arm but none of the 80 CDT clients in the control arm were in shared care at 12 months (chi2 = 9.37, df = 1, p < 0.01; 95 per cent confidence interval 8.6-39.4 per cent). CONCLUSION: A PHCLW can significantly increase the number of CDT clients in shared care arrangements.

Adult↗