Search PubMed⌕ Search

Biomedical subjects

Mark Harris

Publications and source records attributed to Mark Harris.

14 recordsLinked to original sources
PubMed2003

The hepatitis C virus non-structural NS5A protein inhibits activating protein-1 function by perturbing ras-ERK pathway signaling.

The hepatitis C virus nonstructural 5A (NS5A) protein is a pleiotropic phosphoprotein that has been shown to associate with a wide variety of cellular signaling proteins. Of particular interest is the observation that a highly conserved C-terminal Class II polyproline motif within NS5A mediated association with the Src homology 3 domains of members of the Src family of tyrosine kinases and the mitogenic adaptor protein Grb2 (A. Macdonald, K. Crowder, A. Street, C. McCormick, and M. Harris, submitted for publication). In this study, we analyzed the consequences of NS5A expression on mitogenic signaling pathways within a variety of cell lines. Utilizing a transient luciferase reporter system, we observed that NS5A inhibited the activity of the mitogenic and stress-activated transcription factor activating protein-1 (AP1). This inhibition was dependent upon a Class II polyproline motif within NS5A. Using a combination of dominant active and negative mutants of components of the MAPK signaling pathways, selective inhibitors, together with immunoblotting with phospho-specific and phosphorylation-independent antibodies, we determined the signaling pathways targeted by NS5A to inhibit AP1. These studies demonstrated that in both stable NS5A-expressing cells and Huh-7-derived cells harboring subgenomic hepatitis C virus (HCV) replicons, this inhibition was mediated through the ERK signaling pathway. Importantly, a comparable inhibition of AP1 reporter activity was observed in hepatocyte-derived cell lines transduced with a baculovirus vector driving expression of full-length HCV polyprotein. In conclusion, these data strongly suggest a role for the NS5A protein in the perturbation of mitogenic signaling pathways in HCV-infected hepatocytes.

Amino Acid Motifs↗
PubMed2003

Iodine deficiency and goitre in schoolchildren in Melbourne, 2001.

OBJECTIVE: To assess iodine status and goitre prevalence in a sample of schoolchildren in Melbourne. DESIGN: Cross-sectional study of urinary iodine excretion and presence of goitre in a sample of schoolchildren from Years 5-12 attending two urban schools. PARTICIPANTS: 607 children aged 11-18 years consented to thyroid gland palpation and 577 provided a urine sample on the day of examination in August 2001. OUTCOME MEASURE: Iodine status of the study population, based on median urinary iodine values categorised as normal (> or = 100 microg/L), mild (50-99 microg/L) or moderate-severe (< 50 microg/L), and classified according to sex, school year and presence of goitre. RESULTS: 76% (439/577) of students had abnormal urinary iodine values, with 27% (156/577) having values consistent with moderate-severe deficiency. The median urinary iodine excretion for the total group was 70 microg/L, with values for school years 5-12 ranging from 62 microg/L (Year 12) to 76 microg/L (Year 9). The median urinary iodine value in girls was lower than that in boys (64 microg/L v 82 microg/L), and girls had significantly lower urinary iodine values overall (P < 0.002). There was no association between goitre grade and moderate-severe (< 50 microg/L; P = 0.39) or mild (50-99 microg/L; P = 0.07) urinary iodine deficiency. CONCLUSIONS: We found mild iodine deficiency in a cohort of schoolchildren in Melbourne. Our results support other data showing mild iodine deficiency in Sydney and Tasmania and the argument for a national study of iodine nutrition.

Adolescent↗
PubMed2003

HIV-1 Nef induces the release of inflammatory factors from human monocyte/macrophages: involvement of Nef endocytotic signals and NF-kappa B activation.

It has been recently reported that the endogenous expression of HIV-1 Nef in human monocyte/macrophages induces the release of chemokines and other as yet unidentified soluble factors leading to multiple effects of pathogenic significance, such as the recruitment and activation of quiescent lymphocytes. However, the description of underlying molecular mechanisms remained elusive. We recently demonstrated that human monocyte-derived macrophages (MDM) efficiently internalize soluble rNef, thereby inducing effects largely resembling those observed in cells endogenously expressing Nef. By exploiting the rNef/MDM model, we sought to gain more insights on the molecular mechanisms underlying the response of MDM to Nef. Array analysis for the detection of transcripts from a large number of monokines, chemokines, cytokines, and receptors thereof showed that MDM promptly responded to rNef treatment by increasing the transcription of genes for several inflammatory factors. Analysis of supernatants revealed that rNef treatment induced the release of macrophage inflammatory proteins 1alpha and 1beta, IL-1beta, IL-6, and TNF-alpha. Conversely, rNefs mutated in domains critical for the interaction with the endocytotic machinery (i.e., EE155-156QQ, and DD174-175AA) were ineffective. Interestingly, we found that the Nef-dependent release of inflammatory factors correlated with the activation of the NF-kappaB transcription factor, mainly in its p50/p50 homodimeric form, and in a de novo protein synthesis-independent manner. Our data add new hints supporting the idea that the presence of Nef is per se heavily detrimental for monocyte/macrophages and relative cross-talking cell types.

Adult↗
PubMed2003

Prostate cancer.

Explore the source record for details and available documents.

Aged↗
PubMed2002

Randomised controlled trial of home based care of patients with chronic obstructive pulmonary disease.

OBJECTIVES: To evaluate usefulness of limited community based care for patients with chronic obstructive pulmonary disease after discharge from hospital. DESIGN: Randomised controlled trial. SETTING: Liverpool Health Service and Macarthur Health Service in outer metropolitan Sydney between September 1999 and July 2000. PARTICIPANTS: 177 patients randomised into an intervention group (84 patients) and a control group (93 patients) which received current usual care. INTERVENTIONS: Home visits by community nurse at one and four weeks after discharge and preventive general practitioner care. MAIN OUTCOME MEASURES: Frequency of patients' presentation and admission to hospital; changes in patients' disease-specific quality of life, measured with St George's respiratory questionnaire, over three months after discharge; patients' knowledge of illness, self management, and satisfaction with care at discharge and three months later; frequency of general practitioner and nurse visits and their satisfaction with care. RESULTS: Intervention and control groups showed no differences in presentation or admission to hospital or in overall functional status. However, the intervention group improved their activity scores and the control group worsened their symptom scores. While intervention group patients received more visits from community nurses and were more satisfied with their care, involvement of general practitioners was much less (with only 31% (22) remembering receiving a care plan). Patients in the intervention group had higher knowledge scores and were more satisfied. There were no differences in general practitioner visits or management. CONCLUSIONS: This brief intervention after acute care improved patients' knowledge and some aspects of quality of life. However, it failed to prevent presentation and readmission to hospital.

Adult↗
PubMed2002

Xtrack - a web-based crystallographic notebook.

Xtrack is a web-based database-backed crystallographic notebook system that allows groups of workers to keep track of crystallographic project data from the crystallization stage through to data bank deposition. A working demonstration version is available from http://xray.bmc.uu.se/xtrack and the code is available for those who wish to set up their own databases.

Crystallography, X-Ray↗
PubMed2002

Age-related differences in vision and proprioception in a lower limb interceptive task: the effects of skill level and practice.

This study examined age-related differences in the role of visual proprioception during a lower limb interceptive action and how this varies as a function of skill and practice. In Experiment 1, skilled and less-skilled 8-, 10-, and 12-year-old boys controlled a soccer ball using their preferred foot under full vision and when sight of the effector was occluded. With the exception of the high-skilled 12-year-olds and low-skilled 8-year-olds, participants showed a decrement in peformance when denied access to visual proprioception. In Experiment 2, the effect of practicing under different informational constraints was examined for 12 year-old boys. Children performed varying amounts of practice under full vision, or in a condition where sight of the foot was occluded, before being transferred to the alternative viewing condition. Participants who practiced under occluded viewing conditions showed greater relative improvement in performance over practice and transfer sessions compared with a full vision control group. Some support is provided for the manipulation of visual informational constraints as an effective pedagogical approach to motor learning.

Age Factors↗
PubMed2002

Australian GPs are satisfied with their job: even more so in rural areas.

BACKGROUND: Australia has seen a constriction of the scope of practice and of professional prerogatives for GPs in the 1990s, which is said to have led to lower job satisfaction, particularly for rural GPs. OBJECTIVE: The aim of this study was to determine levels of job satisfaction and mental health in a rural and an urban sample of GPs, and to correlate population and practice characteristics with lower job satisfaction and morale. METHODS: A postal survey of GP members of two urban and four rural Divisions of General Practice in New South Wales was carried out using the Wall-Cook-Warr scale and the 12-item General Health Questionnaire (GHQ-12). The overall response rate was 74%. RESULTS: Both urban and rural Australian GPs were generally satisfied with their jobs; however, rural GPs had significantly higher job satisfaction scores. The highest levels of satisfaction were recorded for factors denoting autonomy. The lowest ranked factors were hours of work, income and government policy in general practice. GPs without psychological disturbance were significantly more satisfied with their work than those who were disturbed. Lower job satisfaction was significantly associated with urban GPs, GPs who worked full-time and those who used a language other than English during consultations. Poor mental health and working in an urban area were predictive of lower job satisfaction in men, and bulk-billing all patients (i.e. not charging patients a co-payment, but making a consolidated claim to the government funder Medicare) and working full-time were predictive of lower job satisfaction in women. CONCLUSIONS: Both urban and rural GPs derive a large measure of satisfaction from their job. In particular, rural GPs are satisfied, especially so with their autonomy. Poor mental health was the strongest predictor of lower job satisfaction. The high percentage of GPs with psychological disturbances raises the problem of their access to appropriate mental health services, in particular in rural areas.

Female↗
PubMed2002

Efficient delivery and regulable expression of hepatitis C virus full-length and minigenome constructs in hepatocyte-derived cell lines using baculovirus vectors.

Baculovirus vectors have been used as efficient delivery vehicles for constitutive gene expression in a variety of mammalian cells. We have further developed the system to allow for regulable expression by placing the gene of interest under the control of an inducible promoter, and complementing it with a second baculovirus vector providing the control elements necessary for promoter activity. We have used this system to express (a) the lacZ gene, (b) a 'minigenome' derived from hepatitis C virus (HCV) and carrying lacZ or (c) the full-length HCV viral genome, in human hepatocyte cell lines in an inducible fashion. Control systems that rely on either the absence of tetracycline or presence of ponasterone to induce gene expression were tested. Expression of lacZ was controlled by ponasterone, but beta-galactosidase activity was limited to 10-20% of cells. In contrast, the tetracycline-controlled expression system gave a low basal activity and was highly inducible in almost 100% of cells. Inducible expression was also obtained in almost 100% of cells infected with baculoviruses in which an HCV minigenome was placed downstream of the tetracycline-inducible promoter and upstream of either a hammerhead or hepatitis delta virus ribozyme. Northern blot analysis was consistent with accurate cleavage of the minigenome transcript by the hepatitis delta virus ribozyme. Finally, regulable transcript production and viral polypeptide processing could be demonstrated in HepG2 cells infected with baculoviruses bearing the full-length HCV genome. This system thus provides a novel tool for the analysis of HCV replication and host-cell interactions.

Animals↗
PubMed2002

Research capacity in general practice. Opinions from the field.

BACKGROUND: The Primary Health Care Research Evaluation and Development (PHCRED) Strategy includes funding for universities to build research capacity. As part of its implementation, the University of NSW consulted widely with Divisions of General Practice, GPs and representatives from Community Health Services to determine current research capacity. OBJECTIVE: We summarise the results of this consultation, and outline implications for the PHCRED Strategy. DISCUSSION: Divisions reported low research capacity, and welcomed the opportunity to develop it further. GPs with an interest in research were particularly focused on clinical areas, and saw their role in providing patients and collecting data, rather than initiating and developing ideas. Workers in Community Health Services were keen to be involved. There was considerable support and enthusiasm for the concept of capacity building and the activities proposed, despite perceived low levels of research skills. The overall aim of the PHC-RED Strategy may need to be clarified to successfully build on this enthusiasm.

Attitude of Health Personnel↗
PubMed2001

The inhibition of cAMP-dependent protein kinase by full-length hepatitis C virus NS3/4A complex is due to ATP hydrolysis.

Hepatitis C virus (HCV) is an important cause of chronic liver disease, but the molecular mechanisms of viral pathogenesis remain to be established. The HCV non-structural protein NS3 complexes with NS4A and has three enzymatic activities: a proteinase and a helicase/NTPase. Recently, catalytically inactive NS3 fragments containing an arginine-rich motif have been reported to interact with, and inhibit, the catalytic subunit of cAMP-dependent protein kinase (PKA C-subunit). Here we demonstrate that full-length, catalytically active NS3/4A, purified from recombinant baculovirus-infected insect cells, is also able to inhibit PKA C-subunit in vitro. This inhibition was abrogated by mutation of either the arginine-rich motif or the conserved helicase motif II, both of which also abolished NTPase activity. As PKA C-subunit inhibition was also enhanced by poly(U) (an activator of NS3 NTPase activity), we hypothesized that PKA C-subunit inhibition could be due to NS3/4A-mediated ATP hydrolysis. This was confirmed by experiments in which a constant ATP concentration was maintained by addition of an ATP regeneration system--under these conditions PKA C-subunit inhibition was not observed. Interestingly, the mutations also abrogated the ability of wild-type NS3/4A to inhibit the PKA-regulated transcription factor CREB in transiently transfected hepatoma cells. Our data are thus not consistent with the previously proposed model in which the arginine-rich motif of NS3 was suggested to act as a pseudosubstrate inhibitor of PKA C-subunit. However, in vivo effects of NS3/4A suggest that ATPase activity may play a role in viral pathology in the infected liver.

Adenosine Triphosphate↗
PubMedDate not supplied

Health inequalities in general practice.

The higher burden of disease associated with low socioeconomic status is an every day challenge faced in general practice. General practitioners can make an important difference to these inequalities in health by being aware of the importance of patients socioeconomic background, identifying groups of disadvantaged patients in their practice population and targeting efforts to improve preventive care coverage and quality chronic disease management to those groups. Divisions are important to this work. The profession also has an important role in advocating on behalf of disadvantaged communities, and joining with other health workers and professions in doing so.

Australia↗