Maternal levels of dichlorodiphenyl-dichloroethylene (DDE) may increase weight and body mass index in adult female offspring

OBJECTIVES

To investigate the effect of prenatal exposure to polychlorinated biphenyls (PCBs) and dichlorodiphenyl-dichloroethylene (DDE) on weight, height and body mass index (BMI) in adult female offspring of the Michigan fisheater cohort examined between 1973 and 1991.

METHODS

259 mothers from the Michigan fisheater cohort were studied. Prenatal exposure to PCBs and DDE was estimated by extrapolating maternal measurements to the time that the women gave birth. 213 daughters aged 20-50 years in 2000 were identified and 83% of them participated in at least one of two repeated investigations in 2001/02 (n = 151) and 2006/07 (n = 129). To assess the effect of prenatal PCB and DDE exposure on anthropometric measurements, generalised estimating equations nested for repeated measurements (2001/02 and 2006/07) and for sharing the same mother were used. We controlled for maternal height and BMI and for daughters' age, birth weight, having been breastfed and number of pregnancies.

RESULTS

Maternal height and BMI were significant predictors of the daughters' height, weight and BMI. Low birth weight (<2500 g) was significantly associated with reduced adult offspring weight and BMI. The weight and BMI of adult offspring were statistically significantly associated with the extrapolated prenatal DDE levels of their mothers. Controlling for confounders and compared to maternal DDE levels of <1.503 microg/l, offspring BMI was increased by 1.65 when prenatal DDE levels were 1.503-2.9 microg/l and by 2.88 if levels were >2.9 microg/l. Prenatal PCB levels showed no effect.

CONCLUSION

Prenatal exposure to the oestrogenic endocrine-disrupting chemical DDE may contribute to the obesity epidemic in women.

Degreasing and risk of non-Hodgkin lymphoma

OBJECTIVE

To investigate the relationship between selected solvent-related workplace tasks (degreasing, painting, gluing, stripping paint, staining) and risk of non-Hodgkin lymphoma (NHL).

METHODS

We analysed occupational data from a large population-based case-control study of NHL conducted in the USA. For participants reporting occupations with possible exposure to organic solvents, job-specific interview modules were administered to elicit in-depth information on solvent-related workplace tasks and other exposure-related factors (225 cases, 189 controls). Unconditional logistic regression models were fit to calculate odds ratios (ORs) and 95% CI for average frequency, maximal frequency and cumulative number of hours having performed each task. Individuals with jobs rated as unexposed to organic solvents in the workplace (180 cases, 213 controls) were used as a reference group.

RESULTS

We observed an increased risk of NHL among subjects in the highest category of maximal degreasing frequency (>520 h/year: OR 2.1, 95% CI 0.9 to 4.9, trend test p = 0.02). We found similar associations for the highest levels of average frequency and, among men, cumulative number of hours. Other solvent-related tasks were not associated with NHL.

CONCLUSION

Findings from this case-control analysis of solvent-related tasks suggest that frequent degreasing work may be associated with an elevated risk of NHL.

A preliminary model-based assessment of the cost-utility of a screening programme for early age-related macular degeneration

OBJECTIVES

To estimate the cost-effectiveness of screening for age-related macular degeneration (AMD) by developing a decision analytic model that incorporated and assessed all of the National Screening Committee criteria. A further objective was to identify the major areas of uncertainty in the model, and so inform future research priorities in this disease area.

DATA SOURCES

Major databases were searched in March 2004 and updated in January 2005.

REVIEW METHODS

Systematic literature reviews covered the epidemiology and natural history of AMD, the screening and treatment effectiveness and health-related quality of life relating to AMD. A hybrid cohort-individual sampling model was implemented to describe the range of pathways between the incidence of age-related maculopathy (ARM) and death via clinical presentation and treatment at different stages of the disease. As significant shortfalls in the data available from the literature were apparent, so a range of primary data sources were also used to populate the model. To obtain estimates for the value of parameters deemed to be within an expert's remit, data describing some parameters were elicited from relevant experts. The data identified informed probability distributions describing the uncertainty around the model parameters. To incorporate joint parameter uncertainty (i.e. correlations between parameters), the AMD natural history model was calibrated probabilistically. Randomly sampled sets of input parameters were assigned weights representing the accuracy of their predictions of a set of observed model outputs. The analysis of the AMD screening model estimated the costs, numbers of quality-adjusted life-years (QALYs) and cases of blindness in a general population sample of 50-year-olds over the remainder of their lifetime, for 16 alternative screening options (including no screening). The reference case analysis incorporated current treatment options of laser photocoagulation and photodynamic therapy. Sensitivity analyses describing six alternative sets of intervention strategies, based on horizon scanning of potential future treatments for AMD, were also undertaken.

RESULTS

There remains significant uncertainty about whether any form of screening for AMD is cost-effective. However, annual screening from age 60 years seems to provide the highest mean net benefits, but this is based on a cost-effectiveness estimate that has very poor precision (high levels of uncertainty). The probabilistic sensitivity analysis shows that the 95% credible interval for annual screening from age 60 years ranges from this option dominating the previous option to an incremental cost per QALY of over 0.5 million pounds sterling. Plotting a cost-effectiveness acceptability frontier shows that although annual screening from age 60 years has the highest net benefits at a value of QALY of 30,000 pounds sterling, the associated probability of this option being the most cost-effective option is only around 20%. The sensitivity analyses around potential future treatment options indicate that screening may become more cost-effective with the new treatments.

CONCLUSIONS

The conclusions focus on the interpretation of the results from the perspective of defining the major areas of uncertainty, which were defined as disease progression, rates of clinical presentation, screening test and optician effectiveness, treatment effectiveness, and costs of blindness. Future research may be best targeted at assessing how routine data may be used to describe clinical presentation rates of ARM. Other potential studies include a pilot study of the effectiveness of screening and opticians' referral patterns for AMD and a costing study of blindness as a continuum of association with deterioration in vision.

Macrophages detoxify the genotoxic and cytotoxic effects of surgical cobalt chrome alloy particles but not quartz particles on human cells in vitro

Particles of surgical cobalt chrome alloy are cytotoxic and genotoxic to human fibroblasts in vitro. In vivo orthopaedic patients are exposed to cobalt chrome particles as a result of wear of a joint replacement. Many of the wear debris particles that are produced are phagocytosed by macrophages that accumulate at the site of the worn implant and are disseminated to local and distant lymph nodes the liver and the spleen. In this study we have tested whether this process of phagocytosis could have altered the cytotoxic and genotoxic properties of the cobalt chrome particles. Quartz particles have been investigated as a control. Micron-sized particles of cobalt chrome alloy were internalised by either white cells of peripheral blood or by THP-1 monocytes for 1 week and 1 day, respectively. The particles were then extracted and presented at different doses to fibroblasts for 1 day. There was a reduction of the cytotoxicity and genotoxicity of the cobalt chrome particles after phagocytosis by white cells or THP-1 cells. Cobalt chrome particles that were internalised by fibroblasts also showed a reduction of their cytotoxicity but not their genotoxicity. In contrast the cytotoxicity and genotoxicity of quartz particles was increased after internalisation by THP-1 cells. The surface morphology of the cobalt chrome particles but not the quartz particles was changed after phagocytosis by THP-1 cells. This study suggests that the genotoxic and cytotoxic properties of particles that fall within the size range for phagocytosis may be highly complex in vivo and depend on the combination of material type and previous phagocytosis. These results may have relevance for particle exposure from orthopaedic implants and from environmental or industrial pollution.

The abundance threshold for plague as a critical percolation phenomenon

Percolation theory is most commonly associated with the slow flow of liquid through a porous medium, with applications to the physical sciences. Epidemiological applications have been anticipated for disease systems where the host is a plant or volume of soil, and hence is fixed in space. However, no natural examples have been reported. The central question of interest in percolation theory, the possibility of an infinite connected cluster, corresponds in infectious disease to a positive probability of an epidemic. Archived records of plague (infection with Yersinia pestis) in populations of great gerbils (Rhombomys opimus) in Kazakhstan have been used to show that epizootics only occur when more than about 0.33 of the burrow systems built by the host are occupied by family groups. The underlying mechanism for this abundance threshold is unknown. Here we present evidence that it is a percolation threshold, which arises from the difference in scale between the movements that transport infectious fleas between family groups and the vast size of contiguous landscapes colonized by gerbils. Conventional theory predicts that abundance thresholds for the spread of infectious disease arise when transmission between hosts is density dependent such that the basic reproduction number (R(0)) increases with abundance, attaining 1 at the threshold. Percolation thresholds, however, are separate, spatially explicit thresholds that indicate long-range connectivity in a system and do not coincide with R(0) = 1. Abundance thresholds are the theoretical basis for attempts to manage infectious disease by reducing the abundance of susceptibles, including vaccination and the culling of wildlife. This first natural example of a percolation threshold in a disease system invites a re-appraisal of other invasion thresholds, such as those for epidemic viral infections in African lions (Panthera leo), and of other disease systems such as bovine tuberculosis (caused by Mycobacterium bovis) in badgers (Meles meles).

Taxanes for the adjuvant treatment of early breast cancer: systematic review and economic evaluation

OBJECTIVES

To estimate the clinical effectiveness and cost-effectiveness of docetaxel and paclitaxel compared with non-taxane, anthracycline-containing chemotherapy regimens, for the adjuvant treatment of women with early-stage breast cancer.

DATA SOURCES

Major electronic databases were searched between October 2005 and February 2006.

REVIEW METHODS

A systematic review of the literature on adjuvant taxane versus anthracycline non-taxane chemotherapy for women with early breast cancer was undertaken. A mathematical model was developed to synthesise the available data on costs, disease-free survival and health-related quality of life (HRQoL) of patients receiving taxane-containing chemotherapy versus non-taxane-containing chemotherapy.

RESULTS

Eight of the 11 selected trials (six docetaxel and five paclitaxel) reported a significant improvement in disease-free survival (DFS) or time to recurrence (TTR) for taxanes over comparator regimens. Docetaxel was associated with more adverse events than paclitaxel, most notably febrile neutropenia. Taxanes produced cardiotoxicity, although this was not reported to be greater than for anthracycline comparator arms in all trials. Treatment-related deaths were uncommon. Where reported, all chemotherapy regimens caused HRQoL to deteriorate during treatment. Following treatment, there were no clinically significant differences between taxane and comparator treatment groups. There were few data available comparing licensed regimens of taxanes with chemotherapy regimens commonly used in the UK. The three trials selected as the basis for the economic analysis were those that used the taxanes in accordance with current UK marketing authorisation and had also reported in full. The estimated incremental cost-effectiveness ratio for docetaxel compared to FAC6, based on the BCIRG 001 study, is 12,000 pounds (7000-39,000 pounds) and for paclitaxel compared with Adriamycin/cyclophosphamide, based on the NSABP B28 and CALGB 9344 studies, is 43,000 pounds (16,000 pounds-dominated) and 39,000 pounds (12,000 pounds-dominated), respectively. However, the comparators used in these trials restrict the generalisability of the results, as they do not conform to current standard care in the UK, typically FEC6 and E4-CMF4. An exploratory indirect comparison shows that the benefits of taxane containing regimens compared to regimens in current use in the UK is subject to large uncertainty due to the lack of direct trial comparisons between these interventions. Assumptions regarding the benefits in the taxane arm after the trial follow-up period and the annual rate of recurrence in this period have the most significant influence on the ICER.

CONCLUSIONS

There is a large degree of heterogeneity in the evidence base for the effectiveness of taxane- compared with non-taxane-containing regimens in terms of the interventions, comparators and populations. Eight of the 11 trials providing effectiveness data reported a significant improvement in DFS or TTR for taxanes over comparator regimens. The remaining three trials found no significant differences between the groups in DFS/TTR. The cost-effectiveness results suggest that the cost per quality-adjusted life-year for taxane- compared with non-taxane-containing chemotherapy varies between 12,000 pounds and 43,000 pounds, depending on the taxane under consideration and the specific trial used as the basis of the analysis. However, the comparators used in these trials do not conform to current standard care in the UK. More research is needed, comparing taxanes used in line with their current UK marketing authorisation and with anthracycline-containing regimens commonly used in the UK. The on-going TACT trial is expected to provide useful data. There are currently few data on the effectiveness of taxanes for the over-70s. Further research is required into the long-term outcomes of taxane therapy, such as whether there are any long-term adverse events that significantly impact on overall survival or quality of life and whether the increases in DFS will translate into increases in overall survival.

Feeding difficulties and growth delay in children with hypoplastic left heart syndrome versus d-transposition of the great arteries

The objective of this study was to identify the incidence of feeding difficulties in infants with hypoplastic left heart syndrome (HLHS) and d-transposition of the great arteries (d-TGA). Congenital heart disease is a risk factor for growth failure. The etiologies include poor caloric intake, inability to utilize calories effectively, and increased metabolic demands. The goals of our study were to (1) identify feeding difficulties in infants with HLHS and d-TGA and (2) assess their growth in the first year of life. We performed a chart review of 27 consecutive infants with HLHS and 26 with d-TGA. Descriptive statistics were generated for demographic and clinical variables within each group and are presented as means +/- standard deviations. HLHS and d-TGA groups were compared on time to achieving nutritional goals using the log rank test, on complication rate using the chi-square test, and on weight using the t-test. A significance level of 0.05 was used for all tests. Birth weight was similar for both the HLHS and d-TGA groups (3.19 +/- 0.69 vs 3.35 +/- 0.65 kg, respectively; p = 0.38). Infants with HLHS weighed less than those with d-TGA at l month (3.29 +/- 0.58 vs 3.70 +/- 0.60 kg, respectively; p = 0.021), 6 months (6.27 +/- 1.06 vs 7.31 +/- 1.02 kg, p = 0.003), and 12 months of age (8.40 +/- 1.11 vs 9.49 +/- 1.01 kg, p = 0.006). Time to achieving full caloric intake (at least 100 kcal/kg/day) for the HLHS group (24 +/- 11.9 days) was significantly longer than for the d-TGA group (12.0 +/- 11.2 days, p < 0.001). In addition, infants with HLHS had a higher incidence of feeding-related complications that those with d-TGA (48 vs 4%, respectively; p = 0.001). Compared to the d-TGA group, infants with HLHS weighed less at follow-up, took longer to reach nutritional goals, and had a much higher incidence of feeding-related complications.

Meniscal tear and increased tibial plateau bone area in healthy post-menopausal women

OBJECTIVE

Meniscal tears detected using magnetic resonance imaging (MRI) have been identified as a risk factor for the development and progression of Osteoarthritis, however the prevalence and significance of meniscal tears in healthy, asymptomatic adults remains to be studied. We investigated the prevalence of meniscal tears in a healthy pain free population of post-menopausal women and whether meniscal tears in this population are associated with changes in cartilage volume and defects and tibial plateau bone area over 2 years.

METHODS

Fifty-seven post-menopausal women underwent MRI of their dominant knee at baseline line and approximately 2 years later to assess meniscal tears, cartilage volume, cartilage defects and tibial plateau bone area.

RESULTS

Forty-six percent of women had a meniscal tear in either the medial and/or lateral compartment. Women who had a tear were older (P=0.01) and had more lateral cartilage defects (P=0.02). Medial meniscal tear was associated with 103 mm(2) greater tibial plateau bone area within the medial [95% confidence of interval (CI) 6.2, 200.3; P=0.04] and a lateral meniscal tear with a 120 mm(2) greater area within the lateral compartment (95% CI 45.5, 195.2; P=0.002).

CONCLUSION

This study demonstrates that meniscal tears are common in asymptomatic post-menopausal women and that they become more common with age. Meniscal tears were also associated with greater tibial plateau bone area but not cartilage volume, providing support to the hypothesis that tibial plateau bone changes occur before significant pathological changes in cartilage. Whether increased tibial plateau bone area predisposes to an increased risk of degenerative meniscal tears or whether it is a consequence of altered biomechanical forces in relation to meniscal tear will need to be determined.

Antibiotic use and risk of non-Hodgkin's lymphoma: a population-based case-control study

Antibiotic use in 759 non-Hodgkin's lymphoma (NHL) patients and 589 controls was compared. Neither total antibiotic use (odds ratio=0.7, 95% confidence interval=0.5-1.2), nor antibiotic use by site, was associated with total NHL, or NHL subtypes. There were no trends with frequency or age at first use (P trend=0.23 and 0.26, respectively).

Comparison of broiler performance and carcass parameters when fed diets containing soybean meal produced from glyphosate-tolerant (MON 89788), control, or conventional reference soybeans

A 42-d floor pen study was conducted to compare broiler (Ross x Ross 308) performance and carcass measurements when fed diets containing meal produced from glyphosate-tolerant soybeans (MON 89788) with those of broilers fed diets containing meal produced from control soybean (A3244) that has similar genetic background to MON 89788. Soybean meal produced from 6 conventional soybean varieties was included in the study to provide comparison measurements for broilers fed meal derived from conventional soybeans. It has been found that MON 89788 produces the 5-enolpyruvylshikimate-3-phosphate synthase protein from Agrobacterium sp. strain CP4 (cp4 epsps), which confers tolerance to glyphosate, the active ingredient in Roundup agricultural herbicides. Broilers were fed starter diets (approximately 33% wt/wt dehulled soybean meal) from d 0 to 21 and grower-finisher diets (approximately 30% wt/wt dehulled soybean meal) from d 21 to 42. The study utilized a randomized complete block design with 8 dietary treatments assigned randomly within 5 blocks of 16 pens each (8 male and 8 female) with 10 birds per pen. There were 10 pens per treatment group (5 male and 5 female). No treatment differences (P > 0.05) were detected among dietary treatments for feed intake, weight gain, adjusted feed conversion, or any measured carcass and meat quality parameters. Comparison of all performance, carcass, and meat quality parameters measured showed no differences (P > 0.05) between birds fed the MON 89788 soybean meal diet and the population of birds fed the control and 6 conventional reference soybean meal diets. It is concluded that the diets containing soybean meal produced from MON 89788 were nutritionally equivalent to diets containing soybean meal produced from the control and conventional reference soybean varieties when fed to broilers.

A systematic review and economic evaluation of alendronate, etidronate, risedronate, raloxifene and teriparatide for the prevention and treatment of postmenopausal osteoporosis

OBJECTIVES

To establish the clinical effectiveness and cost-effectiveness of selective oestrogen receptor modulators, bisphosphonates and parathyroid hormone (subject to licensing) for the prevention and treatment of osteoporosis and the prevention of osteoporotic fractures in postmenopausal women.

DATA SOURCES

Electronic databases.

REVIEW METHODS

Studies that met the review's entry criteria were eligible for inclusion in the meta-analyses provided that they reported fracture incidence in terms of the number of patients suffering fractures. Meta-analysis was carried out using the random-effects model. A model was constructed to estimate the cost-effectiveness of osteoporosis interventions. The model calculated the number of fractures that occurred and provided the costs associated with osteoporotic fractures, and the quality-adjusted life-years (QALYs). In addition, the conditions of breast cancer and coronary heart disease (CHD) were modelled, as some interventions have been shown to affect the risk of these conditions.

RESULTS

Ninety randomised controlled trials (RCTs) met the inclusion criteria. They related to the five interventions (alendronate, etidronate, risedronate, raloxifene and teriparatide) and to five comparators (calcium, calcium plus vitamin D, calcitriol, hormone replacement therapy and exercise), as well as placebo or no treatment. All five interventions have been shown to reduce the risk of vertebral fracture in women with severe osteoporosis with adequate calcium intakes. However, none of these drugs has been demonstrated, by direct comparison, to be significantly more effective than either each other or the other active interventions reviewed in this report. The intervention costs of treating all osteoporotic women, for a period of 5 years, were in the region of pound 900-1500 million for alendronate, etidronate, risedronate and raloxifene. The cost per QALY ratios fell dramatically with age. Assuming the risks of a woman with severe osteoporosis at the threshold of osteoporosis, no treatment had a cost per QALY below pound 35,000 at 50 years of age. At 60 years of age, the cost per QALY of raloxifene was pound 26,000 assuming no impact on hip fractures, and pound 31,000 assuming an adverse effect. However, these results are driven by the effect on breast cancer and the assumptions made regarding this disease state. No other intervention had a cost per QALY below pound 35,000. When analyses were conducted assuming that the fracture risk is doubled at each site, alendronate and risedronate had cost per QALY ratios below pound 30,000 at all ages. For women at the threshold of osteoporosis, without a prior fracture and aged 70 years, the cost per QALY of the three bisphosphonates ranged from pound 34,000 to pound 41,000. Raloxifene had a cost per QALY of pound 23,000, assuming no effect on hip fracture, given assumptions regarding breast cancer. At 80 years of age, the cost per QALY of alendronate and risedronate was below pound 20,000. This was true for etidronate when incorporating observational data, but the value rose to pound 69,000 when only RCT data were used. No other intervention had a cost per QALY below pound 35,000. It was assumed that doubling the risk of fracture for women without a prior fracture would give results similar to patients at the threshold of osteoporosis with a prior fracture.

CONCLUSIONS

Of the five interventions, only raloxifene appeared to reduce the risk of vertebral fracture in postmenopausal women unselected for low bone mineral density (BMD). However, as the full data have not been made public, there is some uncertainty regarding this result. None of the five interventions has been shown to reduce the risk of non-vertebral fracture in women unselected for low BMD. All of the proposed interventions provided gains in QALYs compared with no treatment in women with sufficient calcium and vitamin D intakes. The size of the QALY gain for each intervention was strongly related to the age of the patient. The estimated costs varied widely for the interventions. These net costs were markedly different by age, with some interventions becoming cost-saving at higher age ranges in patients with a prior fracture. Areas for future research include: the evidence base for the efficacy of fracture prevention in the very elderly, reanalysis of raloxifene using a dedicated breast cancer and CHD model, and more trials considering the cost-effectiveness of teriparatide.

Empirical assessment of a threshold model for sylvatic plague

Plague surveillance programmes established in Kazakhstan, Central Asia, during the previous century, have generated large plague archives that have been used to parameterize an abundance threshold model for sylvatic plague in great gerbil (Rhombomys opimus) populations. Here, we assess the model using additional data from the same archives. Throughout the focus, population levels above the threshold were a necessary condition for an epizootic to occur. However, there were large numbers of occasions when an epizootic was not observed even though great gerbils were, and had been, abundant. We examine six hypotheses that could explain the resulting false positive predictions, namely (i) including end-of-outbreak data erroneously lowers the estimated threshold, (ii) too few gerbils were tested, (iii) plague becomes locally extinct, (iv) the abundance of fleas was too low, (v) the climate was unfavourable, and (vi) a high proportion of gerbils were resistant. Of these, separate thresholds, fleas and climate received some support but accounted for few false positives and can be disregarded as serious omissions from the model. Small sample size and local extinction received strong support and can account for most of the false positives. Host resistance received no support here but should be subject to more direct experimental testing.

Comparison of broiler performance and carcass parameters when fed diets containing combined trait insect-protected and glyphosate-tolerant corn (MON 89034 x NK603), control, or conventional reference corn

A 42-d floor pen study was conducted to compare broiler (Ross x Ross 308) performance and carcass measurements when fed diets containing lepidopteran-protected corn combined with glyphosate-tolerant corn (MON 89034 x NK603) with those of broilers fed diets containing corn grain from the conventional control (similar genetic background to the test corn) and 6 conventional corn hybrids. It has been found that MON 89034 produces the Cry1A.105 and Cry2Ab2 insecticidal proteins that protect corn plants from feeding damage caused by European corn borer (Ostrinia nubilalis) and other lepidopteran insect pests. In addition, NK603 produces the 5-enolpyruvylshikimate-3-phosphate synthase protein from Agrobacterium sp. strain CP4 (CP4 EPSPS), which confers tolerance to glyphosate, the active ingredient in Roundup agricultural herbicides. The traditional breeding of plants that express the individual traits produced MON 89034 x NK603. Broilers were fed starter diets (approximately 57% wt/wt corn grain) from d 0 to 21 and grower-finisher diets (approximately 59% wt/wt corn grain) from d 21 to 42. The study utilized a randomized complete block design with 8 dietary treatments assigned randomly within 5 blocks of 16 pens each (8 male and 8 female) with 10 birds per pen. There were 10 pens per treatment group (5 male and 5 female). Weight at d 0 and 42, feed intake, feed conversion, and all measured carcass and meat quality parameters were not different (P > 0.05) for birds fed MON 89034 x NK603 and control corn diets. In addition, comparisons of the MON 89034 x NK603 diet to the population of the control and 6 reference corn diets showed no difference (P > 0.05) in any performance, carcass, or meat quality parameter measured. In conclusion, the diets containing MON 89034 x NK603 were nutritionally equivalent to diets containing the control or conventional reference corn grain when fed to broilers.

Comparison of broiler performance when fed diets containing grain from second-generation insect-protected and glyphosate-tolerant, conventional control or commercial reference corn

Two 42-d floor pen studies were conducted to compare broiler (Ross x Ross 308) performance and carcass measurements when broilers were fed diets containing grain from either second-generation lepidopteran insect-protected corn (MON 89034; study 1) or second-generation lepidopteran combined with second-generation corn rootworm-protected and glyphosate-tolerant corn (MON 89034 x MON 88017; study 2) with those of diets containing corn grain from the conventional control and 4 conventional corn hybrids. In both studies, broilers were fed starter diets (approximately 55%, wt/wt, corn grain) from d 0 to 21 and grower-finisher diets (approximately 59%, wt/wt, corn grain) from d 21 to 42. Each study used a randomized complete block design with 6 dietary treatments assigned randomly within 5 blocks of 12 pens each (6 male and 6 female) and 10 pens per treatment group (5 male and 5 female). In study 1 (MON 89034), no treatment differences were detected among dietary treatments for feed intake, weight gain, or any measured carcass parameter. A significant difference was noted for adjusted feed conversion between MON 89034 and control birds; however, no differences were detected in individual treatment comparisons between the MON 89034 and 3 of the 4 commercial corn diets. In study 2 (MON 89034 x MON 88017), no treatment differences were observed for feed intake and most carcass parameters. When significant treatment differences were detected, no differences were observed between MON 89034 x MON 88017, its control, and 2 or more of the commercial corn diets. In each study, comparison of all parameters measured showed no differences between birds fed the test diet and the population of birds fed the control and 4 commercial corn diets. In conclusion, the test diets were nutritionally equivalent to diets containing the control and corn grain from commercial hybrids.

The effect of nano- and micron-sized particles of cobalt–chromium alloy on human fibroblasts in vitro

Wear debris from metal on polyethylene joint replacements causes asceptic loosening as a result of an inflammatory reaction of macrophages to micron-sized particles. Metal on metal implants, which generate nanoparticles, have been reintroduced into surgical practise in order to avoid this problem. There is a current concern about possible long-term effects of exposure to metal particles. In this study, the cytotoxic and genotoxic effects of nanoparticles and micron-sized particles of cobalt chrome alloy have been compared using human fibroblasts in tissue culture. Nanoparticles, which caused more free radicals in an acellular environment, induced more DNA damage than micron-sized particles using the alkaline comet assay. They induced more aneuploidy and more cytotoxicity at equivalent volumetric dose. Nanoparticles appeared to disintegrate within the cells faster than microparticles with the creation of electron dense deposits in the cell, which were enriched in cobalt. The mechanism of cell damage appears to be different after exposure to nanoparticles and microparticles. The concept of nanotoxicology is, therefore, an important consideration in the design of future surgical devices.

The effect of atopy, childhood crowding, and other immune-related factors on non-Hodgkin lymphoma risk

OBJECTIVE

Since adult immune responsiveness is influenced by early childhood exposures, we examined the role of family size, history of atopic disease, and other childhood immune-related exposures in a multi-center case-control study of NHL.

METHODS

Interviews were completed with 1,321 cases ascertained from population-based cancer registries in Seattle, Detroit, Los Angeles and Iowa, and with 1,057 frequency-matched controls, selected by random-digit dialing and from the Medicare files database. Multivariable logistic regression was used to estimate risk.

RESULTS

A history of any allergy (excluding drug allergies), decreased risk of all NHL (Odds Ratio [OR] = 0.7, 95% Confidence Interval [CI] = 0.6-1.0), diffuse large B-cell lymphoma [DLBCL] (OR = 0.6, 95% CI = 0.4-0.9), and follicular NHL (OR = 0.7, 95 CI = 0.5, 1.0). A similar effect was observed for hay fever. A history of eczema was associated with an increased risk of follicular lymphoma (OR = 1.9, 95% CI = 1.1-3.4), but not DLBCL (OR = 1.1, 95% CI = 0.6-2.0). Asthma did not affect risk. Youngest compared to oldest siblings had a 90% increased risk of DLBCL (95% CI = 1.2-3.1; p for trend with increasing birth order = 0.006), but not follicular lymphoma (OR = 1.1, 95% CI = 0.6-1.8).

CONCLUSIONS

We infer that some childhood and immune-related factors may alter NHL risk.

Glucocorticoid-induced osteoporosis: a systematic review and cost-utility analysis

OBJECTIVES

To determine whether strategies can be devised for the assessment and treatment of glucocorticoid-induced osteoporosis (GIO).

DATA SOURCES

Electronic databases were searched up to October 2002.

REVIEW METHODS

A systematic review of interventions was undertaken of all randomised controlled trials in which fracture was measured as an outcome. Effectiveness was compared with effectiveness in postmenopausal osteoporosis. The risk of osteoporotic fractures at any given T-score for bone mineral density (BMD) was determined from published meta-analyses of the relationship between BMD and fracture risk. The risk of an osteoporotic fracture in the presence of a prior osteoporotic fracture was computed from a published meta-analysis of the relationship between the prior occurrence of fracture of each type and the risk of a future fracture of each type. The additional risk due to exposure to glucocorticoids was determined by meta-analysis of prospectively studied population-based cohorts. The consequences of fracture on mortality were assessed for each fracture type. Costs and utilities were determined for osteoporosis in the UK by updating systematic reviews of the literature. A model was prepared that comprised an individual patient-based approach that simulated whether or not events occurred in each subsequent year for each patient. Effectiveness was populated from a systematic review of interventions in GIO and postmenopausal osteoporosis. Treatments were given for 5 years using a 5-year offset time (in this context, offset time is the duration for which an effect on fracture persists after the treatment stops). The analytic framework was set at 10 years. Because of the many uncertainties, extensive sensitivity analysis was undertaken.

RESULTS

Evidence of anti-fracture efficacy was confined to a minority of agents used in the management of GIO. Only risedronate (a bisphosphonate) and calcidiol (vitamin D) were shown to have significant effects on vertebral fracture risk, but neither had significant effects on non-vertebral fracture risk. In further meta-analyses, the effects of bisphosphonates in GIO were compared with effects combining all available data for bisphosphonates in GIO and in postmenopausal osteoporosis. Since calcidiol is not licensed for use in the UK, cost-effectiveness analysis was confined to risedronate and to a pooled bisphosphonate effect. Analysis of cost-effectiveness of risedronate using the empirical data in GIO showed better cost-effectiveness with increasing age, but at no age did cost-effectiveness ratios fall below the threshold value of 30,000 pounds per quality-adjusted life-year gained. When account was taken of BMD, cost-effectiveness was confined to less than 10% of patients with very low T-scores for BMD. Assuming that bisphosphonate efficacy on fracture risk was comparable to that observed with bisphosphonates in postmenopausal osteoporosis, cost-effectiveness was shown in patients with a prior fracture. In patients with no prior fracture, cost-effectiveness was observed in individuals aged 75 years or more. In younger patients without a prior fracture, cost-effective scenarios were found contingent upon a T-score for BMD that was 2.0 SD or less.

CONCLUSIONS

Cost-effective scenarios for risedronate in the management of GIO were identified, but only at the extremes of age and T-score, such that less than 10% of patients aged 50 years or more would be eligible for treatment. Greater cost-effectiveness was observed assuming that the effects of bisphosphonate in GIO were similar to those observed in postmenopausal osteoporosis, an assumption tested by meta-analysis. An assessment algorithm is proposed based on age, the presence of a prior fragility fracture and BMD tests in individuals aged 50 years or more with no fracture. The conclusions derived are conservative, mainly because of the assumptions that were made in the absence of sufficient data. Thus, conclusions that treatment scenarios are cost-effective are reasonably secure. By contrast, scenarios shown not to be cost-effective are less secure. As information in these areas becomes available, the implications for cost-effectiveness of interventions should be reappraised. Health economic assessment based on probability of fracture is an important area for further research. Other areas for further research arise from gaps in empirical knowledge on utilities and side-effects that are amenable to primary research. Further secondary research is recommended to evaluate more closely the impact of all vertebral fractures (rather than clinically overt vertebral fractures) on cost-effectiveness and methods of monitoring treatment.

Fluctuating rodent populations and risk to humans from rodent-borne zoonoses

The fluctuations in abundance of a wildlife reservoir are an attractive explanation for temporal variation in primary human cases of a zoonosis. This is because high abundance may lead to more contact between humans and animals, but also to outbreaks of disease within the reservoir population. We propose a mathematical framework that sets out the consequences of correlation between reservoir abundance and reservoir prevalence for how numbers of human cases are related to reservoir abundance. The fluctuations of rodent populations are well studied and often dramatic. A review of field studies of rodent reservoirs for plague, hantaviruses, and other zoonoses shows that, at a seasonal time scale, a positive correlation between host abundance and host prevalence is rarely observed. More commonly, there is an inverse relationship or negative correlation such that a seasonal increase in rodent abundance is not accompanied by a corresponding increase in the abundance of infectious animals. Seasonal changes in rodent abundance are hence unlikely to fully explain seasonal variation in primary human cases. The few longer field studies (>5 years) show a positive but delayed relationship between reservoir abundance and reservoir prevalence.

The cerebellar fastigial nucleus contributes to CO2-H+ ventilatory sensitivity in awake goats

The purpose of this study was to test the hypothesis that an intact cerebellar fastigial nucleus (CFN) is an important determinant of CO(2)-H(+) sensitivity during wakefulness. Bilateral, stainless steel microtubules were implanted into the CFN (N=9) for injection (0.5-10 microl) of the neurotoxin ibotenic acid. Two or more weeks after implantation of the microtubules, eupneic breathing and CO(2)-H(+) sensitivity did not differ significantly (P>0.10) from pre-implantation conditions. Injection of ibotenic acid (50 mM) did not significantly alter eupneic Pa(CO2) (P>0.10). The coefficient of variation of eupneic Pa(CO2) was 4.0+/-0.6 and 3.7+/-0.4% over the 2 weeks before and after the lesion, respectively. CO(2)-H(+) sensitivity expressed as inspired ventilation/Pa(CO2) decreased from 2.15+/-0.17 pre-lesion to 1.58+/-0.26 l/(min mmHg) 3-6 days post-lesion (P<0.02, -27%). There was no significant (P>0.10) recovery of sensitivity between 7 and 10 days post-lesion. The lesion also increased (P<0.05) the day-to-day variability of this index by nearly 100%. When CO(2) sensitivity was expressed as elevated inspired CO(2)/room air V (I), values at 7%, but not 3 and 5% inspired CO(2), were reduced and more variable (P<0.05) after the ibotenic acid injections. We conclude that during wakefulness, the CFN contributes relatively more to overall ventilatory drive at high relative to low levels of hypercapnia.

The clinical effectiveness and cost-effectiveness of strontium ranelate for the prevention of osteoporotic fragility fractures in postmenopausal women

OBJECTIVES

To estimate the clinical effectiveness and cost-effectiveness of strontium ranelate for the prevention of osteoporotic fractures in postmenopausal women, at different levels of absolute fracture risk. This considers secondary prevention in women who have sustained a previous fracture and primary prevention in those women without a previous fracture, as women with osteoporosis are asymptomatic until a fracture is sustained.

DATA SOURCES

Major electronic bibliographic databases were searched in September 2004 and updated in March 2005.

REVIEW METHODS

A systematic review was carried out to determine clinical effectiveness using the major electronic bibliographic databases and handsearching reference lists of relevant articles and sponsor submissions. Data from selected studies were assessed and included in the meta-analyses, if appropriate. The model used to calculate cost-effectiveness ratios was an updated version of Sheffield Health Economic Model for Osteoporosis that was populated with absolute risk of fractures using an algorithm being developed for the World Health Organization and supplied in confidence to the authors. The model calculated the number of fractures that occur and provided as output data the costs associated with osteoporotic fractures, and the quality adjusted life-years (QALYs) accrued by a cohort of 100 osteoporotic women, with each fracture being detrimental to health and incurring a cost. When the costs of the intervention were included, the incremental cost compared with no treatment was calculated and divided by the gain in QALYs to calculate cost-effectiveness measures. Treatment with strontium ranelate was calculated against a no-treatment option to evaluate whether it could be given cost-effectively. An incremental analysis against alendronate was also conducted to estimate the cost-effectiveness of strontium ranelate relative to a current standard treatment. The cost-effectiveness of strategies for identifying and treating women without a prior fracture used the risk of fracture as an input to the cost-effectiveness model.

RESULTS

Three trials were identified. Pooled data from two studies indicate that strontium ranelate therapy is associated with a reduction in the risk of vertebral fracture [relative risk (RR) compared with placebo 0.60, 95% confidence interval (CI) 0.53 to 0.69, p < 0.001] and non-vertebral fracture (RR 0.84, 95% CI 0.73 to 0.97, p = 0.01). In general, strontium ranelate therapy did not seem to be associated with an increased risk of adverse events. However, the risk of one rare but serious adverse event, venous thromboembolism (including pulmonary embolism), was found to be significantly higher in patients receiving strontium ranelate compared with placebo (RR 1.42, 95% CI 1.02 to 1.98, p = 0.036). Some nervous system disorders, including mental impairment, disturbed consciousness, memory loss and seizures, were also more common in patients randomised to strontium ranelate. Strontium ranelate provided gains in QALYs compared with no treatment in women with sufficient calcium and vitamin D intakes. The size of the QALY gain for each intervention was strongly related to the absolute risk of fracture. From the algorithm used, it is seen that strontium ranelate can be used cost-effectively in women at relatively high risk of osteoporotic fracture. However, the results of the probabilistic sensitivity analysis, using efficacy data from randomised controlled trials, suggest that it is not as cost-effective as alendronate, a comparator intervention from the bisphosphonate class. The use of strontium ranelate in women without a prior fracture will be dependent on identification algorithms being produced in conjunction with the National Institute for Health and Clinical Excellence Osteoporosis Guidelines Development Group.

CONCLUSIONS

Strontium ranelate was shown to be clinically effective in the prevention of osteoporotic fractures. Scenarios have been found where strontium ranelate can be used cost-effectively, however given the probabilistic sensitivity analyses conducted, this intervention appears to be less cost-effective than the bisphosphonate alendronate. The evidence base for the efficacy of fracture prevention for strontium ranelate needs to be strengthened, particularly for hip fractures, where there is currently a non-significant reduction. If it were believed that the efficacy of strontium ranelate is dependent on either age or absolute risk, this would need to be proven. The evidence base on the T-score by age of the general female population needs to be strengthened, particularly in women over the age of 80 years. The prevalence of risk factors associated with fracture rates, over and above that provided by bone mineral density, also needs to be significantly strengthened to ensure that the estimated number of women that could be cost-effectively treated is accurate.

Cultured skin fibroblast cells derived from bluetongue virus-inoculated sheep and field-infected cattle are not a source of late and protracted recoverable virus

A recent hypothesis to explain the recurrence of bluetongue disease after winter seasonal absences of the vector has suggested a role for persistent infection of sheep. This report presents combined independent work from two laboratories investigating the possible recovery of Bluetongue virus (BTV) over a protracted period after infection of both sheep and cattle. Prior to infection with either cell-culture-adapted or non-culture-adapted BTV, sheep were subjected to a preliminary exposure to Culicoides sp. insects, which reportedly facilitates recovery of virus from infected sheep several months post-infection (p.i.). A series of skin biopsies at different intervals p.i. was used to establish skin fibroblast (SF) cultures from which attempts were made to detect virus by isolation and by molecular and immunological methods. Also examined was the effect on virus recovery of additional exposure to Culicoides sp. prior to skin biopsy during the post-inoculation period. A herd of cattle sentinels for surveillance of natural BTV infection in northern Australia was monitored prospectively for seroconversion. Evidence of infection initiated attempted virus recovery by establishing SF cultures. It was found that in both cattle and sheep there was not a protracted period over which BTV could be recovered from SF cultures. The data do not support a general hypothesis that BTV persists in either sheep or cattle.

Plague metapopulation dynamics in a natural reservoir: the burrow system as the unit of study

The ecology of plague (Yersinia pestis infection) in its ancient foci in Central Asia remains poorly understood. We present field data from two sites in Kazakhstan where the great gerbil (Rhombomys opimus) is the major natural host. Family groups inhabit and defend burrow systems spaced throughout the landscape, such that the host population may be considered a metapopulation, with each occupied burrow system a subpopulation. We examine plague transmission within and between family groups and its effect on survival. Transmission of plague occurred disproportionately within family groups although not all gerbils became infected once plague entered a burrow system. There were no spatial patterns to suggest that family groups in close proximity to infected burrow systems were more at risk of infection than those far away. At one site, infection increased the chances of burrow-system extinction. Overall, it is useful to consider the burrow system as the unit of study within a much larger metapopulation.

Factors affecting tibial plateau expansion in healthy women over 2.5 years: a longitudinal study

OBJECTIVE

There is evidence for tibial bone area to increase in response to risk factors for knee osteoarthritis (OA) in healthy subjects and to increase over time in subjects with knee OA. We performed a cohort study to examine whether tibial plateau bone area changes over time in healthy subjects and identify factors influencing the change.

DESIGN

Eighty-one healthy women (age range 50-76 years) underwent magnetic resonance imaging (MRI) on their dominant knee at baseline and approximately 2.5 years later. Tibial plateau bone area was measured at baseline and follow-up. Risk factors assessed at baseline were tested for their association with change in tibial plateau bone area over time using multiple linear regression.

RESULTS

The mean tibial plateau bone area increased from 1733+/-209 to 1782+/-203 mm(2) for the medial, and from 1090+/-152 to 1109+/-152 mm(2) for the lateral over the study period, representing an annual average increase rate of 1.2% (95% CI 0.03%, 1.6%) and 0.8% (95% CI 0.7%, 1.8%), respectively. Baseline tibial plateau bone area was inversely associated with the increase rate of tibial plateau bone area. There was a trend for static knee alignment to be related to the increase rate of tibial plateau bone area.

CONCLUSION

In healthy women, tibial plateau bone area increases over time. Baseline tibial plateau bone area is the main factor affecting the rate of increase, with biomechanical factors, such as static anatomical alignment, likely to affect the expansion of tibial plateau. Further work will be needed to determine the effect of subchondral bone change in the pathogenesis of knee OA.

Using contrast sensitivity to estimate the cost-effectiveness of verteporfin in patients with predominantly classic age-related macular degeneration

AIMS

To re-evaluate the cost-effectiveness of photodynamic therapy with verteporfin (Visudyne, Novartis AG, Switzerland) in patients with predominantly classic and classic choroidal neovascularization (CNV) owing to age-related macular degeneration (AMD), using new evidence on the impact of contrast sensitivity on health status.

METHOD

A health economic model is used to synthesise the evidence on contrast sensitivity and treatment rates from the TAP Investigation with health state utilities and costs. Impairment of visual function is estimated using a Markov model to predict transitions between states of contrast sensitivity. Each state is associated with costs and a health state utility. Total expected costs and benefits for a cohort of patients over a defined number of cycles are calculated. The expected health state utility for each disease state was estimated using results from a study of 209 patients with AMD in Sheffield. The model includes the costs associated with treatment and monitoring in the verteporfin treatment arm and costs offset by delaying the deterioration of visual function.

RESULTS

Beyond 3 years, the annual costs of the verteporfin arm are estimated to be less than the annual costs of the control arm, owing to the cost associated with higher blindness prevalence in the control arm. Over time, the results show that both the incremental utility and cost decreases. By 10 years, the estimated incremental cost-effectiveness is approximately pound20 996 per Quality-Adjusted Life Years.

CONCLUSION

The results of this study suggest that the verteporfin therapy in the treatment for patients with predominantly classic and classic CNV owing to AMD is encouraging.