The Analysis of Personal Taxation and Social Security

This article describes research on the analysis of the consequences of changes in personal taxation and social security carried out as part of the SSRC Programme on Taxation, Incentives and the Distribution of Income. It shows how data from the Family Expenditure Survey can be used to see who gains and who loses from policy changes, illustrating this by an examination of proposals for a tax credit scheme. It discusses the incorporation of changes in behaviour, and the effect of taxes and benefits on incentives, including the ‘poverty trap’. Particular emphasis is placed on the accessibility of the analysis, and the last section describes a range of programs which are available for use on micro-computers.

Correction to: Assessing the effect of nitisinone induced hypertyrosinaemia on monoamine neurotransmitters in brain tissue from a murine model of alkaptonuria using mass spectrometry imaging

The original publication of this article contained an incorrect version that did not include some final reviewers' suggestions, was inadvertently received for production and published. The original article has been corrected.

Assessing the effect of nitisinone induced hypertyrosinaemia on monoamine neurotransmitters in brain tissue from a murine model of alkaptonuria using mass spectrometry imaging

OBJECTIVE

Nitisinone induced hypertyrosinaemia is a concern in patients with Alkaptonuria (AKU). It has been suggested that this may alter neurotransmitter metabolism, specifically dopamine and serotonin. Herein mass spectrometry imaging (MSI) is used for the direct measurement of 2,4-diphenyl-pyranylium tetrafluoroborate (DPP-TFB) derivatives of monoamine neurotransmitters in brain tissue from a murine model of AKU following treatment with nitisinone.

METHODS

Metabolite changes were assessed using MSI on DPP-TFB derivatised fresh frozen tissue sections directing analysis towards primary amine neurotransmitters. Matched tail bleed plasma samples were analysed using LC-MS/MS. Eighteen BALB/c mice were included in this study: HGD^-/- (n = 6, treated with nitisinone-4 mg/L, in drinking water); HGD^-/- (n = 6, no treatment) and HGD^+/- (n = 6, no treatment).

RESULTS

Ion intensity and distribution of DPP-TFB derivatives in brain tissue for dopamine, 3-methoxytyramine, noradrenaline, tryptophan, serotonin, and glutamate were not significantly different following treatment with nitisinone in HGD ^-/- mice, and no significant differences were observed between HGD^-/- and HGD^+/- mice that received no treatment. Tyrosine (10-fold in both comparisons, p = 0.003; [BALB/c HGD^-/- (n = 6) and BALB/c HGD^+/- (n = 6) (no treatment) vs. BALB/c HGD^-/- (n = 6, treated)] and tyramine (25-fold, p = 0.02; 32-fold, p = 0.02) increased significantly following treatment with nitisinone. Plasma tyrosine and homogentisic acid increased (ninefold, p = < 0.0001) and decreased (ninefold, p = 0.004), respectively in HGD^-/- mice treated with nitisinone.

CONCLUSIONS

Monoamine neurotransmitters in brain tissue from a murine model of AKU did not change following treatment with nitisinone. These findings have significant implications for patients with AKU as they suggest monoamine neurotransmitters are not altered following treatment with nitisinone.

A quinazoline-based HDAC inhibitor affects gene expression pathways involved in cholesterol biosynthesis and mevalonate in prostate cancer cells

Chronic inflammation can lead to the development of cancers and resolution of inflammation is an ongoing challenge. Inflammation can result from dysregulation of the epigenome and a number of compounds that modify the epigenome are in clinical use. In this study the anti-inflammatory and anti-cancer effects of a quinazoline epigenetic-modulator compound were determined in prostate cancer cell lines using a non-hypothesis driven transcriptomics strategy utilising the Affymetrix PrimeView® Human Gene Expression microarray. GATHER and IPA software were used to analyse the data and to provide information on significantly modified biological processes, pathways and networks. A number of genes were differentially expressed in both PC3 and DU145 prostate cancer cell lines. The top canonical pathways that frequently arose across both cell lines at a number of time points included cholesterol biosynthesis and metabolism, and the mevalonate pathway. Targeting of sterol and mevalonate pathways may be a powerful anticancer approach.

Creating the Cicerone Project: seeking closer engagement between livestock producers, research and extension

A unique project led by livestock producers, called the Cicerone Project, was undertaken on the Northern Tablelands region of New South Wales, Australia, following acknowledgement by those producers of a widening gap between them and research and extension information. The overall aim of the project was to co-learn, through a partnership between livestock producers, research, extension and other specialists, how to improve the profitability and sustainability of grazing enterprises in that region. It was hypothesised that closer engagement would help to guide relevant research efforts and also enhance the adoption of research findings. With the support of industry funding and the collaboration of key research, education and extension partners, the inaugural steering committee of the Cicerone Project commissioned a survey of over 300 land managers in the region to explore their research and adoption needs. The survey identified the most important issues and found a high level of commitment to the formation of this producer-led project. Negotiations between all collaborators led to the creation of a Business Plan prepared as the basis for an initial funding period of 5 years. Subsequent reviews of the project allowed for extensions with associated activities over an additional 4 years. In order to study the key farm management alternatives identified from the producer survey, the Cicerone Project Board decided to adopt an agricultural ecosystem approach which conducted studies using three whole-farmlet systems. The farmlet experiment compared three contiguous farmlets by measuring as many aspects of the farm systems as possible using an approach summarised in the motto adopted by the Cicerone Project of ‘compare–measure–learn–adopt’. A wide range of field days and seminars were held over the duration of the project to deliver the results to the producer members. This paper provides an introduction to a Special Issue containing 24 papers which report on the entirety of the project from planning, to execution, results, and reflections on the value obtained from the many research and extension activities, with particular emphasis on the farming systems trial conducted between 2000 and 2006.

Planning for whole-farm systems research at a credible scale: subdividing land into farmlets with equivalent initial conditions

Most research comparing different farming systems has been conducted on relatively uniform plots at small scales made necessary by the desire for sufficient replication of the systems and cost limitations. This paper describes an alternative approach to plan the allocation of land to three unreplicated whole-farm management systems such that each farmlet had equivalent starting conditions and yet was at a scale credible to both livestock producers and researchers. The paddocks of each farmlet were distributed across the landscape in a ‘patchwork quilt’ pattern after six iterations of a mapping exercise using a Geographic Information System. Allocation of paddocks took into account those variables of the landscape and natural resource capacity that were not able to be altered. An important benefit of the procedure was that it ensured that the farmlets were co-located with contiguous paddock boundaries so that all farmlets experienced the same climatic as well as biophysical conditions. An electromagnetic survey was conducted of the entire property and used in conjunction with a detailed soils map in order to classify areas into soil conductivity groupings. Equivalent areas of each soil type were allocated across the three farmlets. Similarly, land was distributed according to its topography so that no farmlet would be compromised by being allocated more low lying, flood-prone land than any other farmlet. The third factor used to allocate land to each farmlet was the prior fertiliser history of the original paddocks. This process ensured that each farmlet was objectively allocated equivalent areas of soil type, topography and fertiliser history thus avoiding initial bias among the farmlets. After the plan for all paddocks of each farmlet was finalised, new paddock boundaries were drawn and where necessary, fencing was removed, modified and added, along with re-arranged watering points. The farmlet treatments commenced in July 2000 when the first pasture establishment and differential fertiliser applications were carried out. Evidence from the electromagnetic survey and the Landsat imagery confirmed that the distribution of hydrologic soil conductivity and vegetation greenness were similar between all farmlets just before the commencement of the experiment.

Selection of experimental treatments, methods used and evolution of management guidelines for comparing and measuring three grazed farmlet systems

The Cicerone Project was a collaborative effort by livestock producers, researchers and extension specialists, which aimed to explore the profitability and sustainability of grazing enterprises on the Northern Tablelands of New South Wales, Australia. A major part of the Project was the creation of a moderate scale, unreplicated farmlet experiment. The process of selecting the farmlet treatments and the design of the experiment involved considerable negotiation over an extended period in order to achieve ‘ownership’ by all those involved. The farmlets were designed to compare a typical farmlet (B) as the control with a second farmlet (A), which received higher levels of pasture renovation and soil fertility, and a third (C), which employed intensive rotational grazing management with short graze and long rest periods. Management guidelines were developed for all soil, pasture, livestock and grazing management decisions on the three farmlets. Whole-farmlet data are presented for the pastures sown, fertiliser applied, supplement fed, the stocking rates attained and the pattern of graze and rest periods over the experimental period from July 2000 to December 2006. Over the first 4 years of the trial, pastures were renovated on 71% of farmlet A while 8% of each of farmlets B and C were renovated. The rates of fertiliser applied to the three farmlets varied according to soil test values and the different target values for soil phosphorus and sulfur. In the first year of the trial (2000–01), the annual average stocking rates on farmlets A, B and C were 9.5, 7.9 and 9.1 dry sheep eqivalents/ha, respectively, whereas by the fifth year (2005), the stocking rates were 11.2, 7.8 and 7.4 dry sheep equivalents/ha, respectively. This paper provides details of the general methods used in the farmlet trial, of relevance to a series of related papers which explore all aspects of the farmlet experiment and its findings. It also reports on the selection and definition of the farmlet treatments and describes how the guidelines evolved over the duration of the trial in response to the practical realities of conducting this complex, agroecosystem experiment.

Reflections on the concept, conduct and findings of the producer-led Cicerone Project

The Cicerone Project began as a producer-led partnership that sought, over a period of 8 years, to enhance the profitability and sustainability of livestock enterprises by improving the connection between those producers, research and extension. Following a detailed survey, the research and extension needs of livestock producers were identified and several applied investigations were conducted to meet those needs and delivered through a range of extension activities. This final paper of the Cicerone Special Issue reflects on the entire Project from a wide array of perspectives, including livestock producers, researchers, extension specialists and staff employed by the Project, all of whom are authors of this paper. A notable early successful outcome of the Project was the improved precision of footrot diagnosis, which has been of value to the entire sheep industry, and that flowed from a field investigation of benign and virulent footrot combined with detailed genetic investigations, which led to an improved testing regime. This paper also reflects on the findings of an unreplicated agricultural ecosystem research trial, which measured the impact of pasture renovation, increased soil fertility and grazing management on the profitability and sustainability of three different 53-ha farmlets. Valuable findings from this whole-farmlet trial included the need for a high quality feed supply for increasing stocking rate and animal liveweights; the ability and utility of satellite imagery to detect changes in pasture growth, composition and recent grazing pressure; the value of short grazing and long rest periods for controlling Barber’s pole worms of sheep; the impact of increased stocking rates on whole-farm profitability and risk; methods of optimising decisions relating to pasture renovation, fertiliser applications and grazing management; and an integrated analysis of all key measured components of the farmlet management systems. Collectively, these findings were powerful as they were demonstrated at a scale credible to livestock producers using the ‘compare – measure – learn – adopt’ approach, which was the key philosophy adopted by the Cicerone Project. By comparing and measuring different whole-farm systems, and by ensuring that producers had ownership of the trial process, the Project successfully delivered objective findings that producers trusted and which increased our understanding of important drivers of complex grazing enterprises under variable climatic conditions. Some of these drivers included: the influence of soil phosphorus on botanical composition and subsequent livestock production, the role of pasture renovation and soil fertility on herbage supply, herbage quality and stocking rate, and the improved gastrointestinal nematode control delivered by intensive rotational grazing. The beneficiaries of the Project included the 180 farmer members who participated in some 61 field days and workshops; the research and extension collaborators including four postgraduates who completed their research investigations in conjunction with the Project; and some 500 undergraduate and 300 technical students who benefited from coming to understand the applied field comparisons of the three whole-farmlet systems. Having livestock producers play a significant leadership role led to valuable outcomes achieved with research collaborators; this should encourage the development of other learning partnerships which aim to explore complex farming system issues.

Surveying the management practices and research needs of graziers in the New England region of New South Wales

The inaugural committee of the Cicerone Project commissioned a survey of livestock producers in the New England region to determine the research problems and production practices which were of greatest importance to graziers. In addition, an assessment was made of the level of interest livestock producers had in participating in a proposed producer-led research and adoption project. The survey was mailed to livestock producers in five districts across the New England region during October and November 1997. The survey results concerning land and pasture management issues suggested that a majority of livestock producers in the New England region found the challenges of dry seasons, fertiliser use, pasture composition and pasture persistence to be major problems. A further issue identified was the problem of resistance to drenches used for internal parasite control in sheep. It was clear that producers depend largely on pastures as the primary feed source due to the high cost of supplementary feed. There was considerable interest in learning how to fill gaps in the feed supply, and the management of the feed supply through droughts. Thus, one desired focus of future studies was to explore management systems that might improve the productivity, resilience, stability and longevity of pastures in the New England region. In addition, a focus on grazing management and its effects on pastures and on internal parasite control was suggested by survey respondents. Of the 316 responses to the survey, 76% expressed interest in becoming involved in the Cicerone Project, confirming the desirability of forming a producer-led research and adoption network within the New England region. One hundred and eighty-one respondents expressed an interest in becoming partner members, 100 respondents indicated they were interested in having their farm included in a network, while 139 people were interested in attending regional workshops where further details about the nature of the Cicerone Project would be developed. The survey was clearly of interest to commercial-scale livestock producers as the average size of respondents’ sheep flocks and cattle herds was over 5000 and 500, respectively. The results of this survey provided empirical evidence to support the formation of the Cicerone Project, which was created in 1998 following the approval of a business plan by the primary funding agency, the Woolmark Co.

Long-term follow-up of patients undergoing auto-SCT for advanced germ cell tumour: a multicentre cohort study

Failure of cisplatin-based chemotherapy in advanced germ cell tumour (GCT) is associated with a poor outcome. High-dose chemotherapy and auto-SCT is one therapeutic option, although the long-term outcome after this procedure is unclear. We conducted a multicentre cohort study of consecutive patients undergoing a single auto-SCT for GCT between January 1986 and December 2004. Of 71 subjects, median follow-up is 10.1 years. OS at 5 years is 44.7% (95% confidence interval (CI) 32.9-56.5%) and EFS is 43.5% (95% CI 31.4-55.1%). There were seven (10%) treatment-related deaths within 100 days of auto-SCT. Three (4.2%) patients developed secondary malignancies. Of 33 relapses, 31 occurred within 2 years of auto-SCT. Two very late relapses were noted 13 and 11 years after auto-SCT. In multivariate analysis, favourable outcome was associated with IGCCC (International Germ Cell Consensus Classification) good prognosis disease at diagnosis, primary gonadal disease and response to salvage chemotherapy. We conclude that auto-SCT results in successful outcome for a relatively large subgroup of patients with high-risk GCT. Late relapses may occur, a finding not previously reported.

Atrophy, but not necrosis, in rabbit skeletal muscle denervated for periods up to one year

Our understanding of the effects of long-term denervation on skeletal muscle is heavily influenced by an extensive literature based on the rat. We have studied physiological and morphological changes in an alternative model, the rabbit. In adult rabbits, tibialis anterior muscles were denervated unilaterally by selective section of motor branches of the common peroneal nerve and examined after 10, 36, or 51 wk. Denervation reduced muscle mass and cross-sectional area by 50-60% and tetanic force by 75%, with no apparent reduction in specific force (force per cross-sectional area of muscle fibers). The loss of mass was associated with atrophy of fast fibers and an increase in fibrous and adipose connective tissue; the diameter of slow fibers was preserved. Within fibers, electron microscopy revealed signs of ultrastructural disorganization of sarcomeres and tubular systems. This, rather than the observed transformation of fiber type from IIx to IIa, was probably responsible for the slow contractile speed of the muscles. The muscle groups denervated for 10, 36, or 51 wk showed no significant differences. At no stage was there any evidence of necrosis or regeneration, and the total number of fibers remained constant. These changes are in marked contrast to the necrotic degeneration and progressive decline in mass and force that have previously been found in long-term denervated rat muscles. The rabbit may be a better choice for a model of the effects of denervation in humans, at least up to 1 yr after lesion.

Implantable device for long-term electrical stimulation of denervated muscles in rabbits

Although denervating injuries produce severe atrophic changes in mammalian skeletal muscle, a degree of functional restoration can be achieved through an intensive regime of electrical stimulation. An implantable stimulator was developed so that the long-term effects of different stimulation protocols could be compared in rabbits. The device, which is powered by two lithium thionyl chloride batteries, is small enough to be implanted in the peritoneal cavity. All stimulation parameters can be specified over a wide range, with a high degree of resolution; in addition, up to 16 periods of training (10-180 min) and rest (1-42 h) can be set in advance. The microcontroller-based device is programmed through a bidirectional radiofrequency link. Settings are entered via a user-friendly computer interface and annotated to create an individual study protocol for each animal. The stimulator has been reliable and stable in use. Proven technology and rigorous quality control has enabled 55 units to be implanted to date, for periods of up to 36 weeks, with only two device failures (at 15 and 29 weeks). Changes in the excitability of denervated skeletal muscles could be followed within individual animals. Chronaxie increased from 3.24 +/- 0.54 ms to 15.57 +/- 0.85 ms (n = 55, p < 0.0001) per phase in the 2 weeks following denervation.

Stem cell transplantation for myelofibrosis: a report from two Canadian centers

We describe the course of 25 patients with myelofibrosis (MF) due to agnogenic myeloid metaplasia (n=19) or essential thrombocytosis (n=6) who underwent allogeneic stem cell transplantation (SCT) at one of two Canadian centers. The median age at transplantation was 48.7 (IQR 45.9-50.4) years and transplantation was carried out at a median of 10.7 (IQR 5.67-26.5) months after diagnosis. Granulocyte engraftment (absolute neutrophil count >0.5 x 109/l) occurred at a median of 20 days after transplantation for splenectomized patients, compared with 27.5 days for nonsplenectomized individuals (P=0.03). Increased risk of grade II-IV acute graft-versus-host disease (P=0.04) was noted in patients transplanted after splenectomy. Patients with MF received 0.264+/-0.189 U of packed red blood cells per day over the first 180 days after transplantation, and remained dependent on red blood cell transfusions for a median of 123 (IQR 48-205) days. Complete remission of MF was documented in 33% of evaluable patients. The 1 year cumulative nonrelapse mortality was 48.3%. Median survival for this group of patients was 393 (IQR 109-1014+) days, with a projected 2-year overall survival of 41%. We conclude that allogeneic SCT offers a reasonable chance for prolonged survival in patients with advanced MF, but this occurs at the cost of considerable toxicity and nonrelapse mortality.

A fluorescence-based method for measuring nitric oxide in extracts of skeletal muscle

We describe here a fluorescence assay for nitric oxide synthase activity in skeletal muscle based on a new indicator, 4,5-diaminofluorescein (DAF-2). The rapid and irreversible binding of DAF-2 to oxidized NO allows real-time measurement of NO production. The method is safer and more convenient than the usual citrulline radioassay and can be used with crude muscle extracts. Rabbit fast tibialis anterior (TA) muscle had a nitric oxide synthase (NOS) activity of 44.3 +/- 3.5 pmol/min/mg muscle. Addition of NOS blocker N(G)-allyl-L-arginine reduced this activity by 43%. Slow soleus muscle displayed NOS activity of 7.3 +/- 2.5 pmol/min/mg muscle, 16% that of the TA muscle. Continuous stimulation of TA muscle at 10 Hz for 3 weeks reduced NOS activity by 47% to an intermediate value consistent with the associated conversion of the muscle phenotype from fast to slow.

Dynamics of stimulation-induced muscle adaptation: insights from varying the duty cycle

We sought to gain insight into the dynamics of the signalling process that initiates adaptive change in mammalian skeletal muscles in response to chronic neuromuscular stimulation. Programmable miniature stimulators were implanted into rabbits and used to impose one of the following patterns on the dorsiflexors of one ankle: 10 Hz delivered in equal on/off periods of 30 s, 30 min, or 12 h (all equivalent in terms of aggregate impulse activity to continuous 5 Hz). Two further groups received continuous stimulation at 5 Hz or 10 Hz. In every case the stimulation pattern was maintained continuously for 6 weeks. Tibialis anterior muscles stimulated intermittently with equal on/off periods of 30 s, 30 min and 12 h had contractile characteristics that were significantly slower than the contralateral, unstimulated muscles but did not differ from those of muscles stimulated continuously at 5 Hz. Muscles stimulated continuously at 10 Hz were significantly slower than either contralateral muscles or muscles stimulated with any of the other patterns. Corresponding changes were seen in myosin heavy chain isoform composition. The fatigue index, defined as the fraction of tension remaining after 5 min of a standard fatigue test, was 0.4 for muscles in the contralateral group but equal to or greater than 0.85 for muscles of all the stimulated groups. These results were interpreted with the help of a simple model of the growth and decay of a putative signalling substance based on first order kinetics. The model suggests a rate constant for the accumulation of the signalling substance that is greater than 30 h(-1), and a rate constant for its removal that is greater than 50 h(-1).

Detection and clinical significance of human acute myeloid leukaemia progenitors capable of long-term proliferation in vitro

Acute myeloid leukaemia (AML) blasts within individual patients are heterogeneous in their surface antigen expression and proliferative ability suggesting that, subsequent to transformation, differentiation occurs creating a hierarchy of progenitors in AML. Cells that can produce AML colonies (colony forming units, CFU) in growth factor containing suspension cultures (SC) over 4-8 weeks have a phenotype similar to AML progenitors that engraft non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice, but different from bulk AML blasts, suggesting that these AML SC-initiating cells (SC-IC) may be early progenitors. In this study, we evaluated culture conditions that provide for optimal growth of AML progenitors capable of long-term proliferation. The frequency of CFU, both initially and after 2-4 weeks of SC, varied over four logs between individual patients and was not related to French-American-British subtype. Using limiting dilution, the proliferative potential of individual SC-IC varied from 1 to 480 CFU. The frequency of CFU from SC after > 4 weeks was prognostic for patient survival, and correlated with NOD/SCID engrafting ability. These results suggest the use of long-term culture as an assay for AML cells with leukaemia sustaining potential.

Ontario familial colon cancer registry: methods and first-year response rates

The Ontario Familial Colon Cancer Registry (OFCCR) is a novel registry that collects family history information, epidemiologic data, blood samples and tumour specimens from a population-based sample of colorectal cancer patients and their families. Families are classified as either high familial risk, intermediate familial/other risk or low (sporadic) risk for colorectal cancer. Obtaining high response rates in genetic family studies is especially challenging because of both the time commitment required and issues of confidentiality. The first-year response rate was 61%, resulting in 1,395 participating probands. In an attempt to assess potential response bias, we compared participants with non-participants. The age and sex of participants did not differ from non-participating probands; however, cases in rural areas were somewhat more likely to participate. To date, 57% of 1,587 relatives participated; females were more likely to participate, and relatives of low familial risk were least likely to participate. The OFCCR is an excellent resource that will facilitate the study of genetic and environmental factors associated with colorectal cancer.

Induction of a fatigue-resistant phenotype in rabbit fast muscle by small daily amounts of stimulation

We have shown that fatigue resistance can be induced in rabbit tibialis anterior (TA) muscles without excessive power loss by continuous stimulation at low frequencies, such as 5 Hz, and that the same result is obtained by delivering a 10-Hz pattern in equal on/off periods. Here we ask whether the same phenotype could be produced with daily amounts of stimulation that would be more appropriate for clinical use. We stimulated rabbit TA muscles for 6 wk, alternating fixed 30-min on periods of stimulation at 10 Hz with off periods of different duration. All patterns transformed fast-glycolytic fibers into fast-oxidative fibers. The muscles had fatigue-resistant properties but retained a higher contractile speed and power production than muscles transformed completely to the slow-oxidative type. We conclude that in the rabbit as little as one 30-min period of stimulation in 24 h can result in a substantial increase in the resistance of the muscle to fatigue.

Localization of a putative transcriptional regulator (ATRX) at pericentromeric heterochromatin and the short arms of acrocentric chromosomes

ATRX is a member of the SNF2 family of helicase/ATPases that is thought to regulate gene expression via an effect on chromatin structure and/or function. Mutations in the hATRX gene cause severe syndromal mental retardation associated with alpha-thalassemia. Using indirect immunofluorescence and confocal microscopy we have shown that ATRX protein is associated with pericentromeric heterochromatin during interphase and mitosis. By coimmunofluorescence, ATRX localizes with a mouse homologue of the Drosophila heterochromatic protein HP1 in vivo, consistent with a previous two-hybrid screen identifying this interaction. From the analysis of a trap assay for nuclear proteins, we have shown that the localization of ATRX to heterochromatin is encoded by its N-terminal region, which contains a conserved plant homeodomain-like finger and a coiled-coil domain. In addition to its association with heterochromatin, at metaphase ATRX clearly binds to the short arms of human acrocentric chromosomes, where the arrays of ribosomal DNA are located. The unexpected association of a putative transcriptional regulator with highly repetitive DNA provides a potential explanation for the variability in phenotype of patients with identical mutations in the ATRX gene.

The dose-related response of rabbit fast muscle to long-term low-frequency stimulation

Rabbit tibialis anterior muscles were stimulated continuously at 2.5 Hz, 5 Hz, or 10 Hz for 10 months. The resulting adaptive transformation was dose-related for contractile speed, myosin isoform composition, and enzyme activities. The "fast-oxidative" state produced by stimulation at 2.5 Hz was stable: even after 10 months, 84% of the fibers were of type 2A. Absence of a secondary decline in oxidative activity in these muscles provided strong evidence of a causal link between myosin transitions and metabolic adaptation. Significant fiber loss occurred only after prolonged stimulation at 10 Hz. The myosin isoform composition of individual muscles stimulated at 5 Hz resembled that of muscles stimulated at either the lower or the higher frequency, behavior consistent with a threshold for fiber type change. In clinical applications such as cardiomyoplasty, muscles could be used more effectively by engineering their properties to combine speed and power of contraction with the necessary resistance to fatigue.

Cost-utility analysis of paclitaxel in combination with cisplatin for patients with advanced ovarian cancer

The standard treatment for patients with advanced ovarian cancer (AOC) has been cyclophosphamide and cisplatin (CP). Recently, the results of a large randomized comparative trial demonstrated that the combination of paclitaxel and cisplatin (TP) provided a progression-free survival benefit of 5 months. In this study, a cost-utility analysis was performed from a Canadian health care system perspective to estimate the incremental cost-effectiveness of the TP combination. Twelve AOC patients who received treatment with TP were matched for age and disease stage on a 1-to-2 basis with a CP control. Total hospital resource consumption was then collected for all patients. Treatment preferences were estimated from a cohort of 20 patients and 40 healthy female volunteers using the time trade-off technique. The outcomes were then generated through a decision-analytic model. First-line treatment costs with TP were approximately fourfold greater on a per-cycle basis than the CP alternative (Can$1911 vs Can$459). When progression-free survival benefit and patient treatment preferences were incorporated into the analysis, the results of the decision model revealed an incremental cost between Can$12,000 and Can$24,000 per quality-adjusted progression-free year with the TP protocol. Even though the TP combination has a considerably higher drug acquisition cost, the results of the current analysis suggest that this new chemotherapy regimen does provide patients with substantial quality-adjusted progression-free survival benefit at a reasonable cost to the Canadian health care system.

New Ontario familial breast cancer registry to facilitate genetic and epidemiologic studies

Images

Variegated expression of a globin transgene correlates with chromatin accessibility but not methylation status

There are now many mammalian examples in which single cell assays of transgene activity have revealed variegated patterns of expression. We have previously reported that transgenes in which globin regulatory elements drive the lacZ reporter gene exhibit variegated expression patterns in mouse erythrocytes, with transgene activity detectable in only a sub-population of circulating erythroid cells. In order to elucidate the molecular mechanism responsible for variegated expression in this system, we have compared the chromatin structure and methylation status of the transgene locus in expressing and non-expressing populations of erythrocytes. We find that there is a difference in the chromatin conformation of the transgene locus between the two states. Relative to active transgenes, transgene loci which have been silenced exhibit a reduced sensitivity to general digestion by DNase I, as well as a failure to establish a transgene-specific DNase I hypersensitive site, suggesting that silenced transgenes are situated within less accessible chromatin structures. Surprisingly, the restrictive chromatin structure observed at silenced transgene loci did not correlate with increased methylation, with transgenes from both active and inactive loci appearing largely unmethylated following analysis with methylation-sensitive restriction enzymes and by sequencing PCR products derived from bisulphite-converted genomic DNA.

Fast-to-slow transformation in stimulated rat muscle

Several previous studies have failed to demonstrate changes due to chronic stimulation in contractile speed of innervated fast rat muscles, and it has been suggested that the adaptive capacity of skeletal muscle in this species is limited. We have reassessed this contention. Fast muscles of the rat hind limb were stimulated continuously at 10 or 20 Hz for 55-61 days. The maximum shortening velocity of the extensor digitorum longus muscles was reduced to 50% of the control value. The proportion of type 1 fibers increased from 4% in control muscle to 34% in stimulated muscles and there was a corresponding reduction in type 2B/D fibers. The proportion of type 2A fibers after stimulation was similar to that in control muscles. These results, taken together with our published analyses of myosin isoform composition of these muscles, show that the mechanisms that control gene expression in response to activity are not exclusive to larger mammals.

Induction of a fast-oxidative phenotype by chronic muscle stimulation: histochemical and metabolic studies

Chronic electrical stimulation of skeletal muscle at 10 Hz induces fast-to-slow fiber type transformation. Does a lower aggregate amount of activity lead to a less complete transformation, or does it produce the same transformation over a longer time course? We examined this question by subjecting adult rabbit tibialis anterior and extensor digitorum longus muscles to continuous stimulation at 2.5 Hz for 2-12 wk. Most of the fibers acquired the histochemical and immunocytochemical characteristics of type 2A, not type 1, fibers. There was a corresponding rise in oxidative activity, but this was accompanied by a marked decline in anaerobic glycolysis. The activities of hexokinase and 3-oxoacid CoA-transferase stopped increasing after 2 wk, glutamate oxaloacetate transaminase after 4 wk, and beta-hydroxyacyl-CoA dehydrogenase after 6 wk of stimulation. Succinate dehydrogenase, citrate synthase, lactate dehydrogenase, and creatine phosphokinase continued to change up to 12 wk of stimulation. Changes in enzyme activity were not as rapid or as marked as those observed for stimulation at 10 Hz, and none showed the typical two-phase response of oxidative enzyme activities to stimulation at 10 Hz. The latter may therefore be dependent on induction of type 1 myosin isoforms.

Induction of a fast-oxidative phenotype by chronic muscle stimulation: mechanical and biochemical studies

We studied changes in the mechanical properties and myosin isoform composition of rabbit tibialis anterior muscles that were subjected to continuous stimulation at 2.5 Hz for up to 12 wk. The effects of stimulation at 2.5 Hz were less profound than those observed for the same duration of stimulation at 10 Hz (12). Stimulation at 10 Hz for 12 wk induced complete transformation to a slow-contracting muscle homogeneous in slow myosin isoforms; stimulation for the same period at 2.5 Hz resulted in moderate changes in contractile speed and a very small increase in the synthesis of slow myosin isoforms. On the other hand, the fatigue resistance of muscles stimulated at 2.5 Hz was as great, in both isometric and dynamic fatigue tests, as that of the muscles stimulated at 10 Hz. Thus entire fast skeletal muscles can be transformed to a state in which fast myosin isoforms continue to be synthesized, but the oxidative capacity is sufficient to support sustained working at a higher power output than that associated with slow muscle.

A new polymorphic locus, D7S411, isolated by cloning from preparative pulse-field gels is close to the mutation causing cystic fibrosis

The mutation causing cystic fibrosis (CF) has been localized to the DNA sequence of 700 kb bounded by the loci identified by the markers pMP6d-9 (D7S399) and pJ3.11 (D7S8). A 560-kb fragment obtained after SacII digestion of DNA from a cell line containing this region of human chromosome 7 in a mouse background was separated using pulse-field gel electrophoresis and isolated from the gel. The DNA was digested with BamHI prior to cloning into lambda EMBL3. Approximately 0.1% of the resulting clones contained human repetitive sequences, and 24 such recombinants were studied. Of these, 23 are on chromosome 7; 8 clones were duplicated, and of the 15 different recombinants, 7 are between MET and INT1L1, and a further 7 are between INT1L1 and pMP6d-9, leaving a single marker, pG2, which is between pMP6d-9 and pJ3.11. pG2 recognizes an RFLP with XbaI. A cosmid walk from pG2 has generated a further marker, H80, which recognizes an RFLP with PstI. This new locus (D7S411) divides the remaining region between the CF flanking markers, thereby making it more accessible to fine pulse-field mapping and allowing the precise localization of further clones to this region. Although it is not possible to position the CF locus unequivocally with respect to D7S411, both polymorphic markers at this locus exhibit low but significant linkage disequilibrium with CF, placing the emphasis for the search for the gene on the D7S399 to D7S411 interval of 250 kb.

A randomized trial of two dose levels of cyclophosphamide, methotrexate, and fluorouracil chemotherapy for patients with metastatic breast cancer

This study was designed to assess the role of dosage of chemotherapy for treatment of metastatic breast cancer. One hundred thirty-three patients without prior chemotherapy for metastatic disease were randomly allocated to receive two different dose levels of cyclophosphamide (C), methotrexate (M), and fluorouracil (F), administered intravenously (IV) every 3 weeks. Patients were stratified by sites of disease (visceral, bone, or soft-tissue dominant) and by interval from primary surgery to first recurrence. Doses on the higher-dose arm were 600 mg/m2 (C,F) and 40 mg/m2 (M) with escalation if possible; doses on the lower-dose arm were 300 mg/m2 (C,F) and 20 mg/m2 (M) without escalation. Patients who failed to respond to lower-dose CMF were crossed over to the higher-dose arm. Patients randomized to the higher-dose arm had longer survival measured from initiation of chemotherapy (median survival, 15.6 months v 12.8 months, P = .026 by log-rank test), but the effect of dose was of borderline significance (P approximately 0.12) when adjusted for a chance imbalance between the two arms in the time from first relapse to randomization, using the Cox proportional hazards model. Response rates (International Union Against Cancer [UICC] criteria) for patients with measurable disease were higher-dose arm: 16/53 (30%) and lower-dose arm: 6/53 (11%), (P = .03). Only one of 37 patients responded on crossover from the lower- to the higher-dose arm. Patients experienced more vomiting, myelosuppression, conjunctivitis, and alopecia when receiving higher doses of chemotherapy. A series of 34 linear analogue self-assessment scales were used to make detailed quality of life assessments on a subset of 49 patients. These scales confirmed greater toxicity in the immediate posttreatment period, but also a trend to improvement in general health and some disease-related indices, in patients receiving higher-dose chemotherapy. This trial suggests that better palliation is achieved by using full-dose chemotherapy.

Eliciting preferences for alternative cancer drug treatments. The influence of framing, medium, and rater variables

In oncology there is increasing interest in the development of techniques to help patients choose between alternative therapies in ways that are consistent with their preferences. The purpose of this study was to examine some methodological problems associated with the elicitation of preferences. Preferences for alternative drug therapies were sought from 208 visitors to an open house at the Ontario Cancer Institute and from 216 university nursing students. Preferences were not significantly dependent on the sex, age or professional status of the respondents, nor on the medium used for elicitation of preferences (computer terminal versus pencil-and-paper questionnaire). In contrast, the importance of the way decision problems are framed was confirmed. Comparison of a positive frame (outcomes expressed as the probability of surviving) with a negative frame (outcomes expressed as the probability of dying) and a mixed frame (probabilities of surviving and dying were both given) pointed to the presence or absence of the word "survive" in the outcome description as the main source of framing bias. The framing effect was in the opposite direction to that hypothesized.

Letter: Gestational diabetes

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