'Designer' tumors in mice

We have developed and tested successfully a general method based on Cre-mediated recombination that can be used for ubiquitous or tissue-specific expression of protein products, including tumor-inducing oncoproteins. Depending on the specificity of a chosen promoter driving cre expression, tumors develop by design in bitransgenic mouse progeny derived by crossing Cre-producing mice with partners carrying a dormant oncogenic transgene (targeted into the 3' noncoding region of the cytoplasmic beta-actin locus) that becomes functional after excision of a 'floxed' DNA segment. To provide proof-of-principle, we have used as models transgenes encoding the polyomavirus middle T antigen (PVMT) and the T antigens of the SV40 early region (SVER). Cre-dependent activation of widespread SVER expression resulted in hyperplasias or invasive tumors affecting particular visceral smooth muscles, whereas Cre-dependent, mammary gland-specific expression of PVMT-induced adenocarcinomas, according to plan. Unexpectedly, we also encountered spontaneous (Cre-independent) oncogene expression occurring as a rare event, which simulates the initiation of sporadic tumors and leads to PVMT-induced hemangiomas and mammary carcinomas or SVER-induced disseminated sarcomas, thus, revealing particular tissue susceptibilities to the actions of these oncoproteins.     

Technology insight: targeting of biological molecules for evaluation of high-risk atherosclerotic plaques with magnetic resonance imaging

Identification of high-risk atherosclerotic lesions prone to rupture and thrombosis may greatly decrease the morbidity and mortality associated with atherosclerosis. The development of magnetic resonance imaging contrast agents that specifically target components of the atherosclerotic plaque might enable non-invasive detection of high-risk lesions. This review discusses a variety of molecules present in atherosclerotic plaque that could serve as targets for specific contrast agents. Ultimately, such agents may allow the identification of high-risk atherosclerotic lesions in patients and enable treatment of these patients before lesion progression and complications.     

Defining interferon beta response status in multiple sclerosis patients

IFN-beta is effective in reducing relapses and magnetic resonance imaging (MRI) lesions in multiple sclerosis (MS). It is assumed that individual therapeutic responses vary, but methods to identify IFN-beta responsiveness have not been validated. Our objective was to evaluate methods to classify IFN-beta responder status using relapses and MRI lesions. Data was analyzed from 172 patients who were followed up in a placebo-controlled clinical trial of IFN-beta1a for 2 years. Patients were classified as responders or nonresponders using (1) the number of relapses during the 2-year trial; (2) the number of new T2 lesions after 2 years; and (3) the number of gadolinium-enhancing lesions at year 1 and year 2 on study. Outcomes included 2-year change in the Expanded Disability Status Scale, Multiple Sclerosis Functional Composite, and brain parenchymal fraction. We found that subgroups with high on-study relapse numbers had more disease progression, differences between responder subgroups were similar in the IFN-beta1a and placebo arms. In contrast, subgroups with high numbers of new MRI lesions had significantly more disease progression only in the IFN-beta1a arm. Baseline characteristics failed to account for differential outcome. New MRI lesion activity during IFN-beta1a treatment correlates with poor response to IFN-beta1a. MRI classification may facilitate rational therapeutic decisions, better clinical trial designs, and studies correlating biomarkers with therapeutic response.     

Double depression in an Australian population

Abstract. Background: Double depression, or dysthymia with superimposed major depression, is a major public health issue that imposes considerable burden on the community. Double depression and its associated morbidity have not previously been delineated in an Australian population. Methods: A random and representative sample of the South Australian population was assessed by trained interviewers. The mood module of the Primary Care Evaluation of Mental Disorders (PRIME-MD), the Short-Form Health Status Questionnaire (SF-36), and Assessment of Quality of Life (AQoL) instruments were administered, and data related to treatment use and role functioning were collated. Results: Double depression was present in 2.2% of the population. This group reported high levels of treatment-seeking behaviour with 90% seeking treatment in the last month and 42.4 % taking antidepressants. They also had a highly significantly poorer quality of life than did others in the community. Conclusions: The 2.2% of the population with double depression reported high use of services with poor functioning and health-related quality of life. More effective intervention strategies are required.     

Prevalence, severity, and co-occurrence of chronic physical health problems of persons with serious mental illness

OBJECTIVES: This study examined Medicaid claims forms to determine the prevalence, severity, and co-occurrence of physical illness within a representative sample of persons with serious mental illness (N=147). METHODS: Representativeness of health problems in the study sample was established through comparison with a larger sample of persons with serious mental illness enrolled in Medicaid within the same state. Standardized annual costs were then assigned to Medicaid claims diagnoses, and individual health problem severity was measured as the sum of estimated treatment costs for diagnosed conditions. RESULTS: Seventy-four percent of the study sample (N=109) had been given a diagnosis of at least one chronic health problem, and 50 percent (N=73) had been given a diagnosis of two or more chronic health problems. Of the 14 chronic health conditions surveyed, chronic pulmonary illness was the most prevalent (31 percent incidence) and the most comorbid. Persons with chronic pulmonary illness were second only to those with infectious diseases in average annual cost of treatment ($8,277). Also, 50 percent or more of participants in eight other diagnostic categories had chronic pulmonary illness. A regression analysis identified age, obesity, and substance use disorders as significant predictors of individual health problem severity. CONCLUSIONS: Risk adjustment for physical health is essential when setting performance standards or cost expectations for mental health treatment. Excluding persons with chronic health problems from mental health service evaluations restricts generalizability of research findings and may promote interventions that are inappropriate for many persons with serious mental illness.     

Genome-wide scan of reading ability in affected sibling pairs with attention-deficit/hyperactivity disorder: unique and shared genetic effects

Attention-deficit/hyperactivity disorder (ADHD) and reading disability (RD) are common highly heritable disorders of childhood, which frequently co-occur. Data from twin and family studies suggest that this overlap is, in part, due to shared genetic underpinnings. Here, we report the first genome-wide linkage analysis of measures of reading ability in children with ADHD, using a sample of 233 affected sibling pairs who previously participated in a genome-wide scan for susceptibility loci in ADHD. Quantitative trait locus (QTL) analysis of a composite reading factor defined from three highly correlated reading measures identified suggestive linkage (multipoint maximum lod score, MLS>2.2) in four chromosomal regions. Two regions (16p, 17q) overlap those implicated by our previous genome-wide scan for ADHD in the same sample: one region (2p) provides replication for an RD susceptibility locus, and one region (10q) falls approximately 35 cM from a modestly highlighted region in an independent genome-wide scan of siblings with ADHD. Investigation of an individual reading measure of Reading Recognition supported linkage to putative RD susceptibility regions on chromosome 8p (MLS=2.4) and 15q (MLS=1.38). Thus, the data support the existence of genetic factors that have pleiotropic effects on ADHD and reading ability--as suggested by shared linkages on 16p, 17q and possibly 10q--but also those that appear to be unique to reading--as indicated by linkages on 2p, 8p and 15q that coincide with those previously found in studies of RD. Our study also suggests that reading measures may represent useful phenotypes in ADHD research. The eventual identification of genes underlying these unique and shared linkages may increase our understanding of ADHD, RD and the relationship between the two.     

Clinical verification of the superiority of the current International Union Against Cancer staging criteria in an Australian population of patients with nasopharyngeal carcinoma

The purpose of this study is to assess the prognostic abilities of the fourth and fifth edition International Union Against Cancer (UICC) staging systems for nasopharyngeal carcinoma (NPC) in Australian patients. All patients planned for curative treatment at the Peter MacCallum Cancer Centre from April 1985 to December 1999 were included in this study. There were 181 patients eligible for this study. The median follow up was 7.6 years. Histological subgroups were World Health Organization (WHO) 1 (23), WHO 2 (12), and WHO 3 (146). Presentation with stage IV disease was 83% by UICC fourth edition staging and 34% by UICC fifth edition staging. The 5 years failure-free survival (FFS) rates for stage 1, 2, 3 and 4 disease by the fourth edition was 77, 100, 93, and 49% respectively,and by the fifth edition was 85, 76, 57 and 36%, respectively. The 5 years overall survival (OS) for stage 1, 2, 3, and 4 disease by the fourth edition was 77, 100, 100 and 61%; respectively, and by the fifth edition was 85, 82, 67 and 53%, respectively. Stage 4 patients by the fourth edition were reclassified as stages 2, 3 and 4 by the fifth edition with hazard ratios of 0.77, 1.01 and 1.79, respectively. In multifactor analysis, the fifth edition staging system was significantly related to FFS and OS after allowing for the fourth edition (FFS: P = 0.002; OS: P = 0.005), but the fourth edition was not significantly related to FFS or OS after allowing for the fifth edition (FFS: P = 0.96; OS: P = 0.96). This study confirms the prognostic superiority of the fifth edition UICC staging system over the fourth edition staging system in an Australian NPC population.