Cost-effectiveness of combination peginterferon alpha-2a and ribavirin compared with interferon alpha-2b and ribavirin in patients with chronic hepatitis C

BACKGROUND: Sustained virological response (SVR) is the primary objective in the treatment of chronic hepatitis C (CHC). Results from a recent clinical trial of patients with previously untreated CHC demonstrate that the combination of peginterferon alpha-2a and ribavirin produces a greater SVR than interferon alpha-2b and ribavirin combination therapy. However, the cost-effectiveness of peginterferon alpha-2a plus ribavirin in the U.S. setting has not been investigated. METHODS: A Markov model was developed to investigate cost-effectiveness in patients with CHC using genotype to guide treatment duration. SVR and disease progression parameters were derived from the clinical trials and epidemiologic studies. The impact of treatment on life expectancy and costs were projected for a lifetime. Patients who had an SVR were assumed to remain virus-free for the rest of their lives. In genotype 1 patients, the SVRs were 46% for peginterferon alpha-2a plus ribavirin and 36% for interferon alpha-2b plus ribavirin. In genotype 2/3 patients, the SVRs were 76% for peginterferon alpha-2a plus ribavirin and 61% for interferon alpha-2b plus ribavirin. Quality of life and costs were based on estimates from the literature. All costs were based on published U.S. medical care costs and were adjusted to 2003 U.S. dollars. Costs and benefits beyond the first year were discounted at 3%. RESULTS: In genotype 1, peginterferon alpha-2a plus ribavirin increases quality-adjusted life expectancy (QALY) by 0.70 yr compared to interferon alpha-2b plus ribavirin, producing a cost-effectiveness ratio of $2,600 per QALY gained. In genotype 2/3 patients, peginterferon alpha-2a plus ribavirin increases QALY by 1.05 yr in comparison to interferon alpha-2b plus ribavirin. Peginterferon alpha-2a combination therapy in patients with HCV genotype 2 or 3 is dominant (more effective and cost saving) compared to interferon alpha-2b plus ribavirin. Results weighted by genotype prevalence (75% genotype 1; 25% genotype 2 or 3) also show that peginterferon alpha-2a plus ribavirin is dominant. Peginterferon alpha-2a and ribavirin remained cost-effective (below $16,500 per QALY gained) under sensitivity analyses on key clinical and cost parameters. CONCLUSION: Peginterferon alpha-2a in combination with ribavirin with duration of therapy based on genotype, is cost-effective compared with conventional interferon alpha-2b in combination with ribavirin when given to treatment-naive adults with CHC.

Canine and Feline Diabetes Mellitus: Nature or Nurture?

There is evidence for the role of genetic and environmental factors in feline and canine diabetes. Type 2 diabetes is the most common form of diabetes in cats. Evidence for genetic factors in feline diabetes includes the overrepresentation of Burmese cats with diabetes. Environmental risk factors in domestic or Burmese cats include advancing age, obesity, male gender, neutering, drug treatment, physical inactivity, and indoor confinement. High-carbohydrate diets increase blood glucose and insulin levels and may predispose cats to obesity and diabetes. Low-carbohydrate, high-protein diets may help prevent diabetes in cats at risk such as obese cats or lean cats with underlying low insulin sensitivity. Evidence exists for a genetic basis and altered immune response in the pathogenesis of canine diabetes. Seasonal effects on the incidence of diagnosis indicate that there are environmental influences on disease progression. At least 50% of diabetic dogs have type 1 diabetes based on present evidence of immune destruction of P-cells. Epidemiological factors closely match those of the latent autoimmune diabetes of adults form of human type 1 diabetes. Extensive pancreatic damage, likely from chronic pancreatitis, causes similar to28% of canine diabetes cases. Environmental factors such as feeding of high-fat diets are potentially associated with pancreatitis and likely play a role in the development of pancreatitis in diabetic dogs. There are no published data showing that overt type 2 diabetes occurs in dogs or that obesity is a risk factor for canine diabetes. Diabetes diagnosed in a bitch during either pregnancy or diestrus is comparable to human gestational diabetes.

The distribution of Tannerella forsythia in an adolescent and adult population

Background: The fact that Tannerella forsythia, an important periopathogen, is difficult to cultivate from mixed infections has impeded precise estimates of its distribution within a given population. In order to discern T. forsythia alone from the mixed infection of plaque, the use of sensitive 16S ribosomal RNA based polymerase chain reaction (PCR) detection is necessary. Objectives: The aim of the present study was to determine the distribution of T. forsythia in an adult and in an adolescent population. Materials and methods: Subgingival plaque samples were obtained from 498 Australian adults and from 228 adolescent subjects from Manchester, UK. Tannerella forsythia was detected using PCR and confirmed by restriction analysis. Semi-quantitation of the organisms was carried out using two specific primers of differing sensitivities. Results: In the adolescent population, 25% were found to carry T. forsythia, albeit in relatively low numbers. In the adult population, a total of 37.8% and 11% were found to carry the organism with primer 2 and primer 1, respectively, suggesting that around 27% had between 10(3) and 10(7) organisms. Although there was an apparent increased proportion of T. forsythia positive subjects in those aged >= 50 years, this was not statistical significant. However, T. forsythia positive male smokers showed increased disease severity compared with T. forsythia negative subjects. Conclusion: This study has shown that at least 25% of the adolescent population carry low numbers of T. forsythia, whereas at least 37% of adults carry the organism, with some 11% having relatively high numbers. The relationship between T. forsythia and disease progression in these populations, however, remains to be determined.

Psoriatic arthritis: epidemiology, clinical features, course, and outcome

Psoriatic arthritis (PsA) has been defined as a unique inflammatory arthritis associated with psoriasis. Its exact prevalence is unknown, but estimates vary from 0.3% to 1% of the population. The clinical features described initially are recognised by most experienced clinicians, although they are most distinct in early disease. Initially, PsA typically presents as an oligoarticular and mild disease. However, with time PsA becomes polyarticular, and it is a severe disease in at least 20% of patients. Patients with PsA who present with polyarticular disease are at risk for disease progression. In addition to progression of clinical and radiological damage, health related quality of life is reduced among patients with PsA. It important to note that patients included in recent drug trials resemble patients followed prospectively in a clinic.

CandiVF - Candida albicans virulence factor database

Candida albicans is a pathogen commonly infecting patients who receive immunosuppressive drug therapy, long-term catheterization, or those who suffer from acquired immune deficiency syndrome (AIDS). The major factor accountable for pathogenicity of C. albicans is host immune status. Various virulence molecules, or factors, of are also responsible for the disease progression. Virulence proteins are published in public databases but they normally lack detailed functional annotations. We have developed CandiVF, a specialized database of C. albicans virulence factors (http://antigen.i2r.a-star.edu.sg/Templar/DB/CandiVF/) to facilitate efficient extraction and analysis of data aimed to assist research on immune responses, pathogenesis, prevention, and control of candidiasis. CandiVF contains a large number of annotated virulence proteins, including secretory, cell wall-associated, membrane, cytoplasmic, and nuclear proteins. This database has in-built bioinformatics tools including keyword and BLAST search, visualization of 3D-structures, HLA-DR epitope prediction, virulence descriptors, and virulence factors ontology.

Guidelines for the prevention, detection and management of people with chronic heart failure in Australia 2006

* Chronic heart failure (CHF) is found in 1.5%–2.0% of Australians. Considered rare in people aged less than 45 years, its prevalence increases to over 10% in people aged ≥ 65 years. * CHF is one of the most common reasons for hospital admission and general practitioner consultation in the elderly (≥ 70 years). * Common causes of CHF are ischaemic heart disease (present in > 50% of new cases), hypertension (about two-thirds of cases) and idiopathic dilated cardiomyopathy (around 5%–10% of cases). * Diagnosis is based on clinical features, chest x-ray and objective measurement of ventricular function (eg, echocardiography). Plasma levels of B-type natriuretic peptide (BNP) may have a role in diagnosis, primarily as a test for exclusion. Diagnosis may be strengthened by a beneficial clinical response to treatment(s) directed towards amelioration of symptoms. * Management involves prevention, early detection, amelioration of disease progression, relief of symptoms, minimisation of exacerbations, and prolongation of survival.

Motor unit number estimation - A Bayesian approach

All muscle contractions are dependent on the functioning of motor units. In diseases such as amyotrophic lateral sclerosis (ALS), progressive loss of motor units leads to gradual paralysis. A major difficulty in the search for a treatment for these diseases has been the lack of a reliable measure of disease progression. One possible measure would be an estimate of the number of surviving motor units. Despite over 30 years of motor unit number estimation (MUNE), all proposed methods have been met with practical and theoretical objections. Our aim is to develop a method of MUNE that overcomes these objections. We record the compound muscle action potential (CMAP) from a selected muscle in response to a graded electrical stimulation applied to the nerve. As the stimulus increases, the threshold of each motor unit is exceeded, and the size of the CMAP increases until a maximum response is obtained. However, the threshold potential required to excite an axon is not a precise value but fluctuates over a small range leading to probabilistic activation of motor units in response to a given stimulus. When the threshold ranges of motor units overlap, there may be alternation where the number of motor units that fire in response to the stimulus is variable. This means that increments in the value of the CMAP correspond to the firing of different combinations of motor units. At a fixed stimulus, variability in the CMAP, measured as variance, can be used to conduct MUNE using the "statistical" or the "Poisson" method. However, this method relies on the assumptions that the numbers of motor units that are firing probabilistically have the Poisson distribution and that all single motor unit action potentials (MUAP) have a fixed and identical size. These assumptions are not necessarily correct. We propose to develop a Bayesian statistical methodology to analyze electrophysiological data to provide an estimate of motor unit numbers. Our method of MUNE incorporates the variability of the threshold, the variability between and within single MUAPs, and baseline variability. Our model not only gives the most probable number of motor units but also provides information about both the population of units and individual units. We use Markov chain Monte Carlo to obtain information about the characteristics of individual motor units and about the population of motor units and the Bayesian information criterion for MUNE. We test our method of MUNE on three subjects. Our method provides a reproducible estimate for a patient with stable but severe ALS. In a serial study, we demonstrate a decline in the number of motor unit numbers with a patient with rapidly advancing disease. Finally, with our last patient, we show that our method has the capacity to estimate a larger number of motor units.

Molecular classification of cutaneous malignant melanoma by gene expression profiling

The most common human cancers are malignant neoplasms of the skin(1,2). Incidence of cutaneous melanoma is rising especially steeply, with minimal progress in non-surgical treatment of advanced disease(3,4). Despite significant effort to identify independent predictors of melanoma outcome, no accepted histopathological, molecular or immunohistochemical marker defines subsets of this neoplasm(2,3). Accordingly, though melanoma is thought to present with different 'taxonomic' forms, these are considered part of a continuous spectrum rather than discrete entities(2). Here we report the discovery of a subset of melanomas identified by mathematical analysis of gene expression in a series of samples. Remarkably, many genes underlying the classification of this subset are differentially regulated in invasive melanomas that form primitive tubular networks in vitro, a feature of some highly aggressive metastatic melanomas(5). Global transcript analysis can identify unrecognized subtypes of cutaneous melanoma and predict experimentally verifiable phenotypic characteristics that may be of importance to disease progression.

Expression of prostate-specific antigen variant MRNA transcripts in prostate cancer and benign prostatic hyperplasia

Prostate-specific antigen (PSA) is important in tumour detection, monitoring disease progression and tumour recurrence. however, PSA is not a cancerspecific marker as levels can also be elevated in benign prostatic disease. A number of different mRNA transcripts of PSA have also been identified in prostatic tissue, but have not been fully characterized (PSA 424, PSA 525, Schulz transcript). Tissue specimens from transurethral resection of the prostate (TURP) or radical prostatectomy were obtained from 17 men with BPH and 15 men with prostate cancer. Total RNA was extracted, and reverse-transcriptionpolymerase chain reaction (RT-PCR) and Southern analysis carried out using transcript-specific primers and probes to determine which mRNA PSA transcripts were expressed. Real-time PCR was performed to determine transcript levels between the two groups using transcript-specific primers and SYBR green fluorescence. Values obtained were normalized to a standard housekeeping gene, B2-microglobulin. Transcripts amplified by RT-PCR and real-time PCR were confirmed by DNA sequencing. Our results show that the transcripts were present in some, but not all, BPH and cancer samples indicating that they are not specific to either BPH or cancer. Analysis of real-time PCR normalized values using a Student’s t -test, shows that there is a significant difference between the two groups for PSA 424, but not wild-type PSA, PSA 525 or the Schulz transcript. Although a larger cohort of samples is needed to further confirm these results, these findings suggest that mRNA levels of PSA 424 may have some utility as a diagnostic or prognostic marker in prostate cancer detection.

Articular cartilage glycosaminoglycans inhibit the adhesion of endothelial cells

Articular cartilage undergoes severe loss of proteoglycan and its constituent glycosaminoglycans (GAGs) in osteoarthritis. We hypothesize that the low GAG content of osteoarthritic cartilage renders the tissue susceptible to pathological vascularization. This was investigated using an in vitro angiogenesis model assessing endothelial cell adhesion to GAG-depleted cartilage explants. Bovine cartilage explants were treated with hyaluronidase to deplete GAG content and then seeded with fluorescently tagged human endothelial cells (HMEC-1). HMEC-1 adherence was assessed after 4 hr and 7 days. The effect of hyaluronidase treatment on GAG content, chondrocyte viability, and biochemical composition of the extracellular matrix was also determined. Hyaluronidase treatment reduced the GAG content of cartilage explants by 78 ± 3% compared with that of controls (p <0.0001). GAG depletion was associated with significantly more HMEC-1 adherence on both the surface (superficial zone) and the underside (deep zone) of the explants (both p <0.0001). The latter provided a more favorable environment for extended culture of HMEC-1 compared with the articulating surface. Hyaluronidase treatment altered the immunostaining for chondroitin sulfate epitopes, but not for lubricin. Our results support the hypothesis that articular cartilage GAGs are antiadhesive to endothelial cells and suggest that chondroitin sulfate and/or hyaluronan are responsible. The loss of these GAGs in osteoarthritis may allow osteochondral angiogenesis resulting in disease progression.

Protein and peptides in pictures:imaging with MALDI mass spectrometry

Imaging using MS has the potential to deliver highly parallel, multiplexed data on the specific localization of molecular ions in tissue samples directly, and to measure and map the variations of these ions during development and disease progression or treatment. There is an intrinsic potential to be able to identify the biomarkers in the same experiment, or by relatively simple extension of the technique. Unlike many other imaging techniques, no a priori knowledge of the markers being sought is necessary. This review concentrates on the use of MALDI-MS for MS imaging (MSI) of proteins and peptides, with an emphasis on mammalian tissue. We discuss the methodologies used, their potential limitations, overall experimental considerations and progress that has been made towards establishing MALDI-MSI as a routine technique for the spatially resolved measurement of peptides and proteins. As well as determining the local abundance of individual molecular ions, there is the potential to determine their identity within the same experiment using relatively simple extensions of the basic techniques. In this way MSI offers an important opportunity for biomarker discovery and identification.

Ceramide and reactive oxygen species (ROS) as signal transduction molecules in inflammation

Reactive oxygen species (ROS) and the sphingolipid ceramide are each partly responsible for the intracellular signal transduction of a variety of physiological, pharmacological or environmental agents. Furthermore, the enhanced production of many of these agents, that utilise ROS and ceramide as signalling intermediates, is associated with the aetiologies of several vascular diseases (e.g. atherosclerosis) or disorders of inflammatory origin (e.g. rheumatoid arthritis; RA). Excessive monocyte recruitment and uncontrolled T cell activation are both strongly implicated in the chronic inflammatory responses that are associated with these pathologies. Therefore the aims of this thesis are (1) to further elucidate the cellular responses to modulations in intracellular ceramide/ROS levels in monocytes and T cells, in order to help resolve the mechanisms of progression of these diseases and (2) to examine both existing agents (methotrexate) and novel targets for possible therapeutic manipulation. Utilising synthetic, short chain ceramide to mimic the cellular responses to fluctuations in natural endogenous ceramide or, stimulation of CD95 to induce ceramide formation, it is described here that ceramide targets and manipulates two discrete sites responsible for ROS generation, preceding the cellular responses of growth arrest in U937 monocytes and apoptosis in Jurkat T-cells. In both cell types, transient elevations in mitochondrial ROS generation were observed. However, the prominent redox altering effects appear to be the ceramide-mediated reduction in cytosolic peroxide, the magnitude of which dictates in part the cellular response in U937 monocytes, Jurkat T-cells and primary human peripheral blood resting or PHA-activated T-cells in vitro. The application of synthetic ceramides to U937 monocytes for short (2 hours) or long (16 hours) treatment periods reduced the membrane expression of proteins associated with cell-cell interaction. Furthermore, ceramide treated U937 monocytes demonstrated reduced adhesion to 5 or 24 hour LPS activated human umbilical vein endothelial cells (HUVEC) but not resting HUVEC. Consequently it is hypothesised that the targeted treatment of monocytes from patients with cardiovascular diseases with short chain synthetic ceramide may reduce disease progression. Herein, the anti-inflammatory and immunosuppressant drug, methotrexate, is described to require ROS production for the induction of cytostasis or cytotoxicity in U937 monocytes and Jurkat T-cells respectively. Further, ROS are critical for methotrexate to abrogate monocyte interaction with activated HUVEC in vitro. The histological feature of RA of enhanced infiltration, survivability and hyporesponsiveness of T-cells within the diseased synovium has been suggested to arise from aberrant signalling. No difference in the concentrations of endogenous T-cell ceramide, the related lipid diacylglycerol (DAG) and cytosolic peroxide ex vivo was observed. TCR activation following PHA exposure in vitro for 72 hours did not induced maintained perturbations in DAG or ceramide in T-cells from RA patients or healthy individuals. However, T-cells from RA patients failed to upregulate cytosolic peroxide in response to PHA, unlike those from normals, despite expressing identical levels of the activation marker CD25. This inability to upregulate cytosolic peroxide may contribute to the T-cell pathology associated with RA by affecting the signalling capacity of redox sensitive biomolecules. These data highlight the importance of two distinctive cellular pools of ROS in mediating complex biological events associated with inflammatory disease and suggest that modulation of cellular ceramides represents a novel therapeutic strategy to minimise monocyte recruitment.

Objective methods for anterior ocular grading

This thesis set out to develop an objective analysis programme that correlates with subjective grades but has improved sensitivity and reliability in its measures so that the possibility of early detection and reliable monitoring of changes in anterior ocular surfaces (bulbar hyperaemia, palpebral redness, palpebral roughness and corneal straining) could be increased. The sensitivity of the program was 20x greater than subjective grading by optometrists. The reliability was found to be optimal (r=1.0) with subjective grading up to 144x more variable (r=0.08). Objective measures were used to create formulae for an overall ‘objective-grade’ (per surface) equivalent to those displayed by the CCLRU or Efron scales. The correlation between the formulated objective verses subjective grades was high, with adjusted r2 up to 0.96. Determination of baseline levels of objective grade were investigated over four age groups (5-85years n= 120) so that in practice a comparison against the ‘normal limits’ could be made. Differences for bulbar hyperaemia were found between the age groups (p<0.001), and also for palpebral redness and roughness (p<0.001). The objective formulae were then applied to the investigation of diurnal variation in order to account for any change that may affect the baseline. Increases in bulbar hyperaemia and palpebral redness were found between examinations in the morning and evening. Correlation factors were recommended. The program was then applied to clinical situations in the form of a contact lens trial and an investigation into iritis and keratoconus where it successfully recognised various surface changes. This programme could become a valuable tool, greatly improving the chances of early detection of anterior ocular abnormalities, and facilitating reliable monitoring of disease progression in clinical as well as research environments.

Development of a multicellular co-culture model of normal and cystic fibrosis human airways in vitro

Cystic fibrosis (CF) is the most common lethal inherited disease among Caucasians and arises due to mutations in a chloride channel, called cystic fibrosis transmembrane conductance regulator. A hallmark of this disease is the chronic bacterial infection of the airways, which is usually, associated with pathogens such as Pseudomonas aeruginosa, S. aureus and recently becoming more prominent, B. cepacia. The excessive inflammatory response, which leads to irreversible lung damage, will in the long term lead to mortality of the patient at around the age of 40 years. Understanding the pathogenesis of CF currently relies on animal models, such as those employing genetically-modified mice, and on single cell culture models, which are grown either as polarised or non-polarised epithelium in vitro. Whilst these approaches partially enable the study of disease progression in CF, both types of models have inherent limitations. The overall aim of this thesis was to establish a multicellular co-culture model of normal and CF human airways in vitro, which helps to partially overcome these limitations and permits analysis of cell-to-cell communication in the airways. These models could then be used to examine the co-ordinated response of the airways to infection with relevant pathogens in order to validate this approach over animals/single cell models. Therefore epithelial cell lines of non-CF and CF background were employed in a co-culture model together with human pulmonary fibroblasts. Co-cultures were grown on collagen-coated permeable supports at air-liquid interface to promote epithelial cell differentiation. The models were characterised and essential features for investigating CF infections and inflammatory responses were investigated and analysed. A pseudostratified like epithelial cell layer was established at air liquid interface (ALI) of mono-and co-cultures and cell layer integrity was verified by tight junction (TJ) staining and transepithelial resistance measurements (TER). Mono- and co-cultures were also found to secrete the airway mucin MUC5AC. Influence of bacterial infections was found to be most challenging when intact S. aureus, B. cepacia and P. aeruginosa were used. CF mono- and co-cultures were found to mimic the hyperinflammatory state found in CF, which was confirmed by analysing IL-8 secretions of these models. These co-culture models will help to elucidate the role fibroblasts play in the inflammatory response to bacteria and will provide a useful testing platform to further investigate the dysregulated airway responses seen in CF.

Keratoconus:a review

Keratoconus is the most common primary ectasia. It usually occurs in the second decade of life and affects both genders and all ethnicities. The estimated prevalence in the general population is 54 per 100,000. Ocular signs and symptoms vary depending on disease severity. Early forms normally go unnoticed unless corneal topography is performed. Disease progression is manifested with a loss of visual acuity which cannot be compensated for with spectacles. Corneal thinning frequently precedes ectasia. In moderate and advance cases, a hemosiderin arc or circle line, known as Fleischer's ring, is frequently seen around the cone base. Vogt's striaes, which are fine vertical lines produced by Descemet's membrane compression, is another characteristic sign. Most patients eventually develop corneal scarring. Munson's sign, a V-shape deformation of the lower eyelid in downward position; Rizzuti's sign, a bright reflection from the nasal area of the limbus when light is directed to the limbus temporal area; and breakages in Descemet's membrane causing acute stromal oedema, known as hydrops, are observed in advanced stages. Classifications based on morphology, disease evolution, ocular signs and index-based systems of keratoconus have been proposed. Theories into the genetic, biomechanical and biochemical causes of keratoconus have been suggested. Management varies depending on disease severity. Incipient cases are managed with spectacles, mild to moderate cases with contact lenses and severe cases can be treated with keratoplasty. This article provides a review on the definition, epidemiology, clinical features, classification, histopathology, aetiology and pathogenesis, and management and treatment strategies for keratoconus.