A Canadian cost-effectiveness analysis of SAPIEN 3 transcatheter aortic valve implantation compared with surgery, in intermediate and high-risk severe aortic stenosis patients

Background and objectives: The treatment of severe aortic stenosis requires replacement of the defective native valve. Traditionally, this has been done via surgery, but in the last 10 years, transcatheter techniques have emerged. Transcatheter aortic valve implantation (TAVI) is a less invasive option compared to surgical aortic valve replacement (SAVR), and this study evaluates the cost-effectiveness of TAVI versus SAVR in intermediate and high surgical risk patients in Canada. Methods: A Markov model was used to project the costs and quality-adjusted life years (QALYs) gained for TAVI using the SAPIEN 3 valve and SAVR over a 15-year time horizon. The PARTNER I and II studies were used to populate the model in terms of survival, clinical event rates and quality of life over time. The costs of TAVI with SAPIEN 3 and SAVR as well as the costs associated with events included in the model were derived from Canadian administrative and literature data. Costs were expressed in 2018 Canadian dollars and all future costs and QALYs were discounted at a rate of 1.5% annually. Probabilistic and one-way sensitivity analyses were conducted. Results: The incremental cost-effectiveness ratios of TAVI using the SAPIEN 3 valve compared to surgery were $28,154 per QALY gained in intermediate risk patients and $17,237 per QALY gained in high-risk patients. The results of the probabilistic analyses indicated that at willingness-to-pay threshold of $50,000 per QALY gained, the probability of TAVI to be cost-effective was greater than 0.9 in both intermediate-risk and high-risk patients. Sensitivity analyses showed the results were most sensitive to the time horizon used. Conclusion: TAVI using the SAPIEN 3 valve is highly likely to be cost-effective in Canadian patients with severe aortic stenosis who are at intermediate and high surgical risk.

Cost-effectiveness analysis of the SAPIEN 3 TAVI valve compared with surgery in intermediate-risk patients

OBJECTIVE

Transcatheter aortic valve implantation (TAVI) has become the therapy of choice for treating severe aortic stenosis in patients at high-risk for surgery or where it is considered too risky to attempt. This uptake varies across geographies however, and its cost or value has frequently been cited as the reason for this. We sought to evaluate the potential cost and clinical impact of TAVI in intermediate risk patients from a French collective perspective.

MATERIALS AND METHODS

The analysis was performed using a novel Markov model with data derived from the PARTNER II randomized controlled trial for survival, clinical event rates, and quality-of-life. The simulated time horizon was 15 years, costs were from French sources and presented in 2016 Euros. Discounting of all outcomes was at 4% annually and the effect of uncertainty in model parameters was explored by deterministic and probabilistic sensitivity analysis (PSA).

RESULTS

In comparison to surgery, TAVI resulted in improved clinical outcomes (life expectancy and quality-adjusted life expectancy) and lower costs over a lifetime time horizon. The base case results showed increases of 0.42 years and 0.41 QALYs with lifetime cost savings of €439 for TAVI compared to surgery. PSA results showed a >50% likelihood of cost-effectiveness at €0 willingness-to-pay and a 100% likelihood at ∼€15,000.

LIMITATIONS

Clinically, survival projections are based on limited follow-up data and introduce uncertainty into the outcomes from the model. Economically, procedure costs are derived from a heterogeneous mix of patient risk groups, although this is much more likely to bias against TAVI and under-estimate overall cost savings.

CONCLUSIONS

In our analyses of intermediate risk patients, TAVI is associated with superior clinical outcomes compared to surgery and is cost saving. It could be expected that cost savings are conservative and likely to increase over time.

The Burden and Impact of Vertigo: Findings from the REVERT Patient Registry

OBJECTIVE

Despite the high prevalence of vertigo globally and an acknowledged, but under-reported, effect on an individual's wellbeing, few studies have evaluated the burden on healthcare systems and society. This study was aimed to quantitatively determine the impact of vertigo on healthcare resource use and work productivity.

METHODS

The economic burden of vertigo was assessed through a multi-country, non-interventional, observational registry of vertigo patients: the Registry to Evaluate the Burden of Disease in Vertigo. Patients included were those with a new diagnosis of Meniere's disease, benign paroxysmal positional vertigo, other vertigo of peripheral vestibular origin, or peripheral vestibular vertigo of unknown origin.

RESULTS

A total of 4,294 patients at 618 centers in 13 countries were included during the registry. Of the 4,105 patients analyzed, only half were in employment. Among this working patient population, 69.8% had reduced their workload, 63.3% had lost working days, and 4.6% had changed and 5.7% had quit their jobs, due to vertigo symptoms. Use of healthcare services among patients was high. In the 3 months preceding Visit 1, patients used emergency services 0.4 ± 0.9 times, primary care consultations 1.6 ± 1.8 times, and specialist consultations 1.4 ± 2.0 times (all mean ± SD). A mean of 2.0 ± 5.4 days/patient was also spent in hospital due to vertigo.

CONCLUSION

In addition to the negative impact on the patient from a humanistic perspective, vertigo has considerable impact on work productivity and healthcare resource use.

Abstract P5-04-04: Significance of PELP1/HDAC2/microRNA-200 regulatory network in EMT and metastasis of breast cancer

Tumor metastasis remains a significant clinical problem and is the leading cause of death among breast cancer patients. Estrogen receptor (ER)-coregulators play an essential role in cancer progression and metastatic tumors express increased levels of coregulators. Proline glutamic acid rich protein (PELP1) is an ER coregulator, its expression is upregulated during breast cancer progression to metastasis and is an independent prognostic predictor of shorter survival of breast cancer patients. MicroRNA (miR) mediated regulation of tumorigenesis is emerging as a new paradigm in cancer biology and widespread misexpression of miRs has been reported in breast cancer. The objective of this study is to examine the mechanism and therapeutic significance of PELP1 regulation of miRs leading to breast cancer metastasis. We have used both ER+ve (ZR75, MCF7) and ER-ve (MDAMB231, MDAMB468) models that either stably overexpress PELP1 or PELP1shRNA. Boyden chamber, and invasion assays demonstrated that PELP1 down regulation significantly affect migration of both ER+ve and ER-ve cells. Epithelial to Mesenchymal Transition (EMT) real time qPCR Array studies identified PELP1 modulate expression of EMT genes Snail, Twist, ZEB1, ZEB2, Vimentin and MMPs. Importantly, whole genome microRNA array analysis using PELP1 model cells revealed that miR200a and miR141 were significantly upregulated in cells expressing PELP1-shRNA compared to control cells. Accordingly, over expression of PELP1 in low metastatic model cells decreased expression of miR200a and miR141. PELP1 regulation of miRs was further confirmed by ZEB1 and ZEB2 3′ UTR luciferase reporter assays. ChIP analysis revealed recruitment of PELP1 to the proximal promoter region of miR-200a and miR141 and promoter reporter assays further confirmed PELP1 regulation of miRs. Interestingly, PELP1 down regulated expression of miR200a and miR141 by promoting repressive chromatin modifications via HDAC2. Supporting this, HDAC inhibitors reversed PELP1 driven repressive effects. Further, ectopic expression of miR200a and miR141 mimetic decreased PELP1 mediated invasion/metastatic functions. Prognostic significance of PELP1-miRNA axis was determined using Tissue micro-array (TMA) and in situ hybridization (ISH assays) of Locked Nucleic Acid (LNA™)-based microarray approach in 102 human breast tumors. To test therapeutic potential in vivo, we have generated ZR-PELP1- and MCF7-PELP1-shMIMIC of miR200a and miR141 stable cells. In vitro gene expression and Boyden chamber assays using these model cells revealed that shMIMIC of miR200a and miR141 reversed PELP1 mediated alterations in gene expression and reduced PELP1 driven migration/invasion. Proof of principle studies using IVIS imaging of nude mice based assays of GFP-Luc labeled cells demonstrated therapeutic efficacy of miRIDIAN shMIMIC of miR200a and miR141 on PELP1 driven in vivo metastasis. Collectively, these novel findings demonstrate for the first time a previously unknown role for PELP1 in epigenetically controlling the functions of tumor metastasis suppressor miR-200a and miR141. These results suggest that PELP1-miR axis may be crucial stimulus for promoting EMT and breast cancer metastasis. This study is funded by NIH T32CA148724 Postdoc Fellowship Grant.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-04-04.

[Cost-effectiveness of exenatide versus insulin glargine in Spanish patients with obesity and type 2 diabetes mellitus]

BACKGROUND AND OBJECTIVES

Exenatide, a GLP-1 receptor agonist for adjuvant treatment of type 2 diabetes mellitus (T2DM), has been shown to be as effective as insulin glargine (IG) for reducing glycated hemoglobin levels combined with metformin or/and sulphonylureas. Exenatide is associated to weight reduction and a higher incidence of gastrointestinal adverse events. The objective of this study was to assess the cost-effectiveness of exenatide as compared to IG in obese patients with T2DM not achieving an adequate blood glucose control from the perspective of the Spanish healthcare system.

METHODS

Pharmacoeconomic model inputs were obtained from an obese subpopulation (BMI ≥ 30 k/m(2)) of an international, randomized, controlled clinical trial comparing exenatide with IG in poorly controlled T2DM patients, and were supplemented with country-specific data.

RESULTS

Exenatide was associated to improvements in life-years gained and quality-adjusted life years (QALYs) by 0.11 and 0.62 respectively versus IG. Direct costs were € 9,306 higher as compared to IG (€ 47,010 versus € 37,704, with increased pharmacy costs as the main driver). Exenatideís incremental cost-effectiveness ratio was € 15,068 per QALY gained versus IG.

CONCLUSIONS

Exenatide was associated to greater clinical benefits and higher costs in obese T2DM patients as compared to IG. Considering a willingness-to-pay threshold of € 30,000 per QALY gained in the Spanish setting, exenatide represents an efficient option in comparison with IG.

Cost-effectiveness of highly purified omega-3 polyunsaturated fatty acid ethyl esters in the treatment of chronic heart failure: results of Markov modelling in a UK setting

AIMS

A recent randomized placebo-controlled clinical trial has reported reductions in mortality and hospitalizations in patients with chronic heart failure (CHF) who were prescribed highly purified omega-3 polyunsaturated fatty acid ethyl esters (n-3 PUFA). This study aimed at evaluating the cost and benefits associated with their use in the treatment of CHF in a UK setting.

METHODS AND RESULTS

Results from a recent clinical trial were used to develop a Markov model to project clinical outcomes while capturing relevant costs and patient quality of life. The model captured outcomes over a lifetime horizon from a UK National Health Service perspective, with direct costs accounted in 2009 GBP (£) and discounted at 3.5% together with clinical benefits. Results are presented in terms of life expectancy, quality-adjusted life expectancy, direct costs, and incremental cost-effectiveness ratios. In addition to standard therapy, n-3 PUFA vs. placebo increased lifetime direct costs by £993 (≈€1150), with additional quality-adjusted life expectancy of 0.079 quality-adjusted life years (QALYs), and mean lifetime costs of £12,636 (≈€14,600) per QALY gained. Probabilistic sensitivity analyses suggested a 60% likelihood of n-3 PUFA being regarded as cost-effective versus placebo at a willingness-to-pay threshold of £30,000 (≈€34,600) per QALY gained.

CONCLUSIONS

By currently accepted standards of value for money in the UK; the addition of n-3 PUFA to optimal medical therapy for patients with heart failure is likely to be cost-effective.

Some preliminary observations on the possible relationship between ammonia production from soiled bedding in calf rearing sheds and calf illness

A limited field study of covered facilities used for raising dairy calves suggested that respiratory disorders and death rates were highest when calves were continuously housed on bedding composed of wood shavings, where ventilation was poor and where automatic feeders were installed. High concentrations of ammonia were found in the urine-soaked bedding following overnight incubation. A prolific growth of mixed micro-organisms isolated from the shavings rapidly colonised plates of selective urea medium. Death rates of 10% and 13.5% were observed on two properties. Respiratory distress was common and lung disease was intractable to treatment on these farms. A histopathological diagnosis of subacute purulent pneumonia with distal necrotising bronchiolitis was made, similar to lung lesions produced experimentally in cats, guinea pigs and rabbits exposed to ammonia gas.

Evaluating the cost-effectiveness of self-monitoring of blood glucose in type 2 diabetes patients on oral anti-diabetic agents

OBJECTIVES

To evaluate the cost-effectiveness of self-monitoring of blood glucose (SMBG) in patients with type 2 diabetes treated with oral anti-diabetic agents (OADs) in Switzerland.

METHODS

A validated computer model of diabetes was used to project outcomes reported from a published longitudinal study of SMBG in type 2 diabetes patients, treated with OADs and with no history of SMBG, over a 30-year time horizon and cost-effectiveness was assessed from the perspective of a third party healthcare payer. Costs and clinical outcomes were discounted at 3% annually in line with recommended practice. Sensitivity analyses were performed.

RESULTS

Once, twice or three times daily SMBG was associated with improvements in HbA1c which led to increased life expectancy and quality-adjusted life expectancy, and reduced incidence of diabetes complications compared with no SMBG in type 2 diabetes patients on OADs. Direct medical costs increased by CHF 528, CHF 1'650 and CHF 2'899 in patients performing SMBG once, twice or three times daily compared to those not using SMBG, respectively. Incremental cost-effectiveness ratios were well below commonly quoted willingness-to-pay thresholds at CHF 9'177, CHF 12'928 and CHF 17'342 per quality-adjusted life year (QALY) gained respectively.

CONCLUSIONS

Based on data from a large observational study, SMBG is likely to be cost-effective by generally accepted standards in SMBG-naïve patients on oral anti-diabetic agents in the Swiss setting.

A study of misbehavior: token reinforcement in the rat

The purpose of this research was to investigate the phenomenon of misbehavior described by Breland and Breland (1961). Rats were trained to obtain ball-bearings and drop them in a hole for food or water reinforcers. In confirmation of the Brelands' observation, many subjects were slow to deliver the balls, and frequently attempted to chew them before they were dropped. A series of four experiments, in which the same rats were used throughout, showed that delivery times tended to be longer with food than with water, and that these times increased when nylon balls were substituted. The effect of motivational level was investigated by varying both deprivation and amount of prefeeding; no effect on delivery time was detected, although other measures of performance were affected by motivational factors. Similar results were obtained in a final experiment that employed a new set of naive subjects. The studies demonstrated that misbehavior can be studied in an experimental situation, and the results supported an analysis in terms of competition between stimulus-reinforcer and response-reinforcer contingencies. The question of why such effects have not been reported in previous token reinforcer studies was unanswered.

Anti-CD3 monoclonal antibody treatment in newly diagnosed Type 1 diabetes patients: a hypothetical modelling analysis

AIMS

Although limited clinical data exist for anti-CD3 monoclonal antibody therapies, it is believed that they may influence glycaemic control, endogenous insulin secretion and hypoglycaemic event rates in individuals newly diagnosed with Type 1 diabetes. In the absence of suitable empirical evidence, the objective of this study was to estimate the potential long-term clinical outcomes associated with treatment via a hypothetical modelling analysis.

METHODS

Analyses were performed using a published and validated computer simulation model of diabetes in a hypothetical US cohort based on published literature and expert opinion. The efficacy of anti-CD3 monoclonal antibody treatment was estimated from clinical data and expert opinion and simulations were performed over a 60-year time horizon. The impact on quality of life associated with treatment was also captured via published utility values.

RESULTS

Assuming that a treatment course of an anti-CD3 monoclonal antibody produced an initial reduction in glycated haemoglobin of -0.8%, and that the effects persisted for up to 5 years, treatment was projected to lead to an increase in undiscounted life expectancy of 0.43 years and an increase in quality-adjusted life expectancy of 0.36 quality-adjusted life years compared with conventional exogenous insulin.

CONCLUSIONS

A course of a hypothetical anti-CD3 monoclonal antibody treatment associated with improved glycaemic control and, potentially, the preservation of pancreatic beta-cell function was estimated to lead to improved life expectancy and quality-adjusted life expectancy compared with conventional treatment in patients with newly diagnosed Type 1 diabetes.

Evaluation of exenatide vs. insulin glargine in type 2 diabetes: cost-effectiveness analysis in the German setting

OBJECTIVES

The objective of this analysis was to determine the cost-effectiveness of exenatide vs. insulin glargine in patients with type 2 diabetes failing to achieve glycaemic control with oral antidiabetic agents, in the German setting, from a third-party payer perspective.

METHODS

Data from a published randomized controlled trial were used in combination with a published, validated computer simulation model of type 2 diabetes to project clinical and cost outcomes over a time horizon of 10 years. Cost data were obtained from published literature and expert opinion. Clinical and cost outcomes were discounted at 5% per annum. Sensitivity analyses were performed to establish key drivers and parameters.

RESULTS

Treatment with exenatide compared with insulin glargine was projected to be associated with improvements in life expectancy of 0.016 years and quality-adjusted life expectancy of 0.280 quality-adjusted life years (QALYs), increased lifetime direct medical costs of euro 3854 (euro 22 095 vs. euro 18 242) and an incremental cost-effectiveness ratio (ICER) of euro 13 746 per QALY. If quality of life was not taken into account, exenatide was associated with an ICER of euro 238 201 per life year gained vs. insulin glargine. Sensitivity analyses revealed that outcomes were most sensitive to changes in assumptions for (dis)utility values relating to weight change and the rate of self-monitored blood glucose testing.

CONCLUSIONS

Exenatide was projected to be associated with similar clinical outcomes and increased costs compared with insulin glargine. Analysis of cost-effectiveness from a third-party perspective suggests that exenatide is likely to represent good value for money in the German setting.

The consequences of delaying insulin initiation in UK type 2 diabetes patients failing oral hyperglycaemic agents: a modelling study

BACKGROUND

Recent data have shown that type 2 diabetes patients in the UK delay initiating insulin on average for over 11 years after first being prescribed an oral medication. Using a published computer simulation model of diabetes we used UK-specific data to estimate the clinical consequences of immediately initiating insulin versus delaying initiation for periods in line with published estimates.

METHODS

In the base case scenario simulated patients, with characteristics based on published UK data, were modelled as either initiating insulin immediately or delaying for 8 years. Clinical outcomes in terms of both life expectancy and quality-adjusted life expectancy and also diabetes-related complications (cumulative incidence and time to onset) were projected over a 35 year time horizon. Treatment effects associated with insulin use were taken from published studies and sensitivity analyses were performed around time to initiation of insulin, insulin efficacies and hypoglycaemia utilities.

RESULTS

For patients immediately initiating insulin there were increases in (undiscounted) life expectancy of 0.61 years and quality-adjusted life expectancy of 0.34 quality-adjusted life years versus delaying initiation for 8 years. There were also substantial reductions in cumulative incidence and time to onset of all diabetes-related complications with immediate versus delayed insulin initiation. Sensitivity analyses showed that a reduced delay in insulin initiation or change in insulin efficacy still demonstrated clinical benefits for immediate versus delayed initiation.

CONCLUSION

UK type 2 diabetes patients are at increased risk of a large number of diabetes-related complications due to an unnecessary delay in insulin initiation. Despite clear guidelines recommending tight glycaemic control this failure to begin insulin therapy promptly is likely to result in needlessly reduced life expectancy and compromised quality of life.

Cost-effectiveness of pioglitazone in type 2 diabetes patients with a history of macrovascular disease: a German perspective

BACKGROUND

The aim of this study was to project health-economic outcomes relevant to the German setting for the addition of pioglitazone to existing treatment regimens in patients with type 2 diabetes, evidence of macrovascular disease and at high risk of cardiovascular events.

METHODS

Event rates corresponding to macrovascular outcomes from the Prospective Pioglitazone Clinical Trial in Macrovascular Events (PROactive) study of pioglitazone were used with a modified version of the CORE Diabetes Model to simulate outcomes over a 35-year time horizon. Direct medical costs were accounted from a healthcare payer perspective in year 2005 values. Germany specific costs were applied for patient treatment, hospitalization and management. Both costs and clinical benefits were discounted at 5.0% per annum.

RESULTS

Over patient lifetimes pioglitazone treatment improved undiscounted life expectancy by 0.406 years and improved quality-adjusted life expectancy by 0.120 quality-adjusted life years (QALYs) compared to placebo. Direct medical costs (treatment plus complication costs) were marginally higher for pioglitazone treatment and calculation of the incremental cost-effectiveness ratio (ICER) produced a value of euro13,294 per QALY gained with the pioglitazone regimen versus placebo. Acceptability curve analysis showed that there was a 78.2% likelihood that pioglitazone would be considered cost-effective in Germany, using a "good value for money" threshold of euro50,000 per QALY gained. Sensitivity analyses showed that the results were most sensitive to changes in the simulation time horizon. After adjustment for the potential stabilization of pancreatic beta-cell function with pioglitazone treatment, the ICER was euro6,667 per QALY gained for pioglitazone versus placebo.

CONCLUSION

The findings of this modelling analysis indicated that, for patients with a history of macrovascular disease, addition of pioglitazone to existing therapy reduces the long-term cumulative incidence of diabetes-complications at a cost that would be considered to represent good value for money in the German setting.

Cost-effectiveness of pioglitazone in patients with type 2 diabetes and a history of macrovascular disease in a Swiss setting

OBJECTIVES

To evaluate the cost-effectiveness of pioglitazone versus placebo, given in addition to existing treatment regimens, in patients with type 2 diabetes and evidence of macrovascular disease in Switzerland.

METHODS

Event rates corresponding to macrovascular outcomes from the PROactive (Prospective Pioglitazone Clinical Trial in Macrovascular Events) trial of pioglitazone were used to project long-term clinical outcomes as part of a modified version of the previously validated CORE Diabetes Model. Direct medical costs associated with treatment regimens, complications and patient management were accounted in 2005 values based on Swiss-specific unit costs. Time horizon was set to lifetime (35 years). Future costs and clinical benefits were discounted at 2.5% annually in line with Swiss recommendations. One-way sensitivity analyses were performed.

RESULTS

Addition of pioglitazone was associated with a reduced incidence of most diabetes-related complications, improved life expectancy (0.258 years) and improved quality-adjusted life expectancy (0.180 QALYs) compared with placebo. Pioglitazone treatment increased direct costs by CHF 10,914 per patient over a lifetime horizon. The incremental cost-effectiveness ratio (ICER) of pioglitazone versus placebo was CHF 42,274 per life-year gained and CHF 60,596 per QALY gained. ICERs were sensitive to variation in time horizon and duration of pioglitazone treatment effects. With a willingness to pay of CHF 80,000 per QALY in the Swiss setting, there was a 62.5% chance that pioglitazone would be cost-effective.

CONCLUSIONS

Addition of pioglitazone to existing therapy was projected to reduce the long-term cumulative incidence of most diabetes complications and improve quality-adjusted life expectancy. Evaluation of incremental direct medical costs associated with these clinical benefits indicated that pioglitazone is likely to be a cost-effective treatment option in the Swiss setting over patient lifetimes.

Evaluating the cost-effectiveness of therapy conversion to insulin detemir in patients with type 2 diabetes in Germany: a modelling study of long-term clinical and cost outcomes

OBJECTIVES

To evaluate the long-term cost-effectiveness of transferring type 2 diabetes patients to an insulin detemir regimen after failure to achieve adequate control with oral antidiabetic agents (OADs) alone, or in combination with neutral protamine hagedorn (NPH) insulin, or with insulin glargine in Germany.

METHODS

A computer simulation model of diabetes was used to make long-term projections of future clinical outcomes and direct medical costs based on findings from a German subanalysis of the PREDICTIVE trial. The study analysed the impact of converting patients failing their current treatments to an insulin detemir regimen. Therapy conversion to insulin detemir +/- OADs was associated with a significant reduction in glycosylated haemoglobin (HbA(1)c) compared with OADs alone, NPH insulin +/- OADs, and insulin glargine +/- OADs. Across all three groups, hypoglycaemia rates decreased by 80% and patients lost an average of 0.9 kg of body weight during treatment with insulin detemir +/- OADs.

RESULTS

Therapy conversion to insulin detemir +/- OADs was projected to improve life expectancy by 0.28 years compared with OADs alone, and by 0.13 years compared with the NPH and glargine regimens. Transfer to insulin detemir was associated with improvements in quality-adjusted life expectancy of 0.21 quality-adjusted life years (QALYs) over OADs alone, 0.28 QALYs over NPH +/- OADs, and 0.29 QALYs over glargine +/- OADs. Insulin detemir was associated with savings over patient lifetimes due to reduced diabetes-related complications in all three comparisons.

CONCLUSIONS

Therapy conversion to insulin detemir +/- OADs in type 2 diabetes patients failing OADs alone, NPH or insulin glargine regimens was associated with improvements in life expectancy, quality-adjusted life expectancy and cost savings in all three scenarios evaluated.

Biphasic insulin aspart 70/30 vs. insulin glargine in insulin naïve type 2 diabetes patients: modelling the long-term health economic implications in a Swedish setting

OBJECTIVES

To evaluate the long-term clinical and economic outcomes of biphasic insulin aspart 70/30 (BIAsp 70/30) treatment vs. insulin glargine in insulin naïve, type 2 diabetes patients failing oral antidiabetic drugs in a Swedish setting.

METHODS

A published and validated computer simulation model (the CORE Diabetes Model) was used to project life expectancy, quality-adjusted life expectancy (QALE) and costs over patient lifetimes. Cohort characteristics [54.5% male, mean age 52.4 years, 9 years mean diabetes duration, mean glycosylated haemoglobin (HbA1c) 9.77%] and treatment effects were based on results from the Initiate Insulin by Aggressive Titration and Education (INITIATE) clinical trial. Direct medical costs were accounted in 2006 Swedish Kronor (SEK) and economic and clinical benefits were discounted at 3% per annum.

RESULTS

Biphasic insulin aspart 70/30 treatment when compared with insulin glargine treatment was associated with improvements in discounted life expectancy of 0.21 years (13.10 vs. 12.89 years) and QALE of 0.21 quality-adjusted life years (QALYs) (9.16 vs. 8.96 QALYs). Reductions in the incidence of diabetes-related complications in the BIAsp 70/30 treatment arm led to reduced total costs of SEK 10,367 when compared with insulin glargine (SEK 396,475 vs. SEK 406,842) over patient lifetimes. BIAsp 70/30 treatment was projected to be dominant (cost and lifesaving) when compared with insulin glargine in the base case analysis.

CONCLUSIONS

Biphasic insulin aspart 70/30 treatment was associated with improved clinical outcomes and reduced costs compared with insulin glargine treatment over patient lifetimes. These results were driven by improved HbA1c levels associated with BIAsp 70/30 compared with insulin glargine and the accompanying reduction in diabetes-related complications despite increases in body mass index.

Cost-effectiveness of insulin aspart versus human soluble insulin in type 2 diabetes in four European countries: subgroup analyses from the PREDICTIVE study

OBJECTIVES

To evaluate the long-term health economic outcomes associated with insulin aspart (IAsp) compared to human soluble insulin (HI) in type 2 diabetes patients on basal-bolus therapy in Sweden, Spain, Italy and Poland.

METHODS

A published computer simulation model of diabetes was used to predict life expectancy, quality-adjusted life expectancy and incidence of diabetes-related complications. Baseline cohort characteristics (age 61.6 years, duration of diabetes 13.2 years, 45.1% male, HbA(1c) 8.2%, BMI 29.8 kg/m(2)) and treatment effects were derived from the PREDICTIVE observational study. Country-specific complication costs were derived from published sources. The analyses were run over 35-year time horizons from third-party payer perspectives in Spain, Italy and Poland and from a societal perspective in Sweden. Future costs and clinical benefits were discounted at country-specific discount rates. Sensitivity analyses were performed.

RESULTS

IAsp was associated with improvements in discounted life expectancy and quality-adjusted life expectancy, and a reduced incidence of most diabetes-related complications versus HI in all four settings. IAsp was associated with societal cost-savings in Sweden (SEK 2470), direct medical cost-savings in Sweden and Spain (SEK 8248 and euro 1382, respectively), but increased direct costs in Italy (euro 2235) and Poland (euro 743). IAsp was associated with improved quality-adjusted life expectancy in Sweden (0.077 QALYs), Spain (0.080 QALYs), Italy (0.120 QALYs) and Poland (0.003 QALYs).

CONCLUSIONS

IAsp was dominant versus HI in both Sweden and Spain, would be considered cost-effective in Italy with an incremental cost-effectiveness ratio of euro 18,597 per QALY gained, but would not be considered cost-effective in Poland.

Cysteine biosynthesis in Trichomonas vaginalis involves cysteine synthase utilizing O-phosphoserine

Trichomonas vaginalis is an early divergent eukaryote with many unusual biochemical features. It is an anaerobic protozoan parasite of humans that is thought to rely heavily on cysteine as a major redox buffer, because it lacks glutathione. We report here that for synthesis of cysteine from sulfide, T. vaginalis relies upon cysteine synthase. The enzyme (TvCS1) can use either O-acetylserine or O-phosphoserine as substrates. The K(m) values of the enzyme for sulfide are very low (0.02 mm), suggesting that the enzyme may be a means of ensuring that sulfide in the parasite is maintained at a low level. T. vaginalis appears to lack serine acetyltransferase, the source of O-acetylserine in many cells, but has a functional 3-phosphoglycerate dehydrogenase and an O-phosphoserine aminotransferase that together result in the production of O-phosphoserine, suggesting that this is the physiological substrate. TvCS1 can also use thiosulfate as substrate. Overall, TvCS1 has substrate specificities similar to those reported for cysteine synthases of Aeropyrum pernix and Escherichia coli, and this is reflected by sequence similarities around the active site. We suggest that these enzymes are classified together as type B cysteine synthases, and we hypothesize that the use of O-phosphoserine is a common characteristic of these cysteine synthases. The level of cysteine synthase in T. vaginalis is regulated according to need, such that parasites growing in an environment rich in cysteine have low activity, whereas exposure to propargylglycine results in elevated cysteine synthase activity. Humans lack cysteine synthase; therefore, this parasite enzyme could be an exploitable drug target.

Dopamine manipulations limited to preexposure are sufficient to modulate latent inhibition

Four experiments are reported that demonstrated that dopamine (DA) transmission is involved in the acquisition of latent inhibition (LI) of a conditioned taste aversion. LI refers to weaker conditioning as a consequence of nonreinforced preexposure (PE) of the future conditioned stimulus. Although it is known to depend on DA transmission during the conditioning phase, it is usually thought that the cognitive processes involved in the establishment of LI (during the PE phase) are DA independent. Either amphetamine (AMPH; 0.5 or 1.0 mg/kg) or haloperidol (HAL; 0.1 mg/kg) were injected before 1 or all of the 3 PE sessions. AMPH blocked the acquisition of LI if it was injected before each or before only the last PE session and HAL potentiated LI.

Ice-active proteins from the Antarctic nematode Panagrolaimus davidi

The Antarctic nematode Panagrolaimus davidi has an ice-active protein that shows recrystallization inhibition but no thermal hysteresis. It belongs to a class of ice-active proteins found in a variety of freezing-tolerant organisms that display insignificant levels of thermal hysteresis in the context of the environmental temperatures to which they are exposed. The recrystallization inhibition activity of the P. davidi ice-active protein is present at low concentrations, is relatively heat stable, is affected more by acid than by alkaline pH, is not calcium dependant and is not affected by reagents that target carbohydrate residues or sulphydryl linkages. A hexagonal ice crystal growth form also indicates the presence of an ice-active protein. This protein could have important functions in the survival of intracellular freezing by this organism by controlling the stability of ice after its formation.

Freezing and cryoprotective dehydration in an Antarctic nematode (Panagrolaimus davidi) visualised using a freeze substitution technique

The pattern of ice formation during the freezing of Panagrolaimus davidi, an Antarctic nematode that can survive intracellular ice formation, was visualised using a freeze substitution technique and transmission electron microscopy. Nematodes plunged directly into liquid nitrogen had small ice crystals throughout their tissues, including nuclei and organelles, but did not survive. Those frozen at high subzero temperatures showed three patterns of ice formation: no ice, extracellular ice, and intracellular ice. Nematodes subjected to a slow-freezing regime (at -1 degrees C) had mainly extracellular ice (70.4%), with the bulk of the ice in the pseudocoel. Some (24.8%) had no ice within their bodies, due to cryoprotective dehydration. Nematodes subjected to a fast-freezing regime (at -4 degrees C) had intracellular (54%) and extracellular (42%) ice. Intracellular ice was confined to the cytoplasm of cells, with organelles in the spaces in between ice crystals. The survival of nematodes subjected to the fast-freezing regime (53%) was less than those subjected to the slow-freezing regime (92%).

Light and scanning electron microscopy of the cardiac gland region of the stomach of the Babirusa (Babyrousa babyrussa – Suidae, Mammalia)

Previous studies have indicated that the gross anatomical structure of the stomach of the babirusa (Babyrousa babyrussa) differs markedly from that of all other pigs. This light and scanning electron microscopic study revealed a previously unknown, microscopic structure characterised by a 'honeycomb' pattern at the luminal surface of the tunica mucosa. The walls of the 'honeycomb' were about 0.20-0.25 mm high and appeared almost entirely composed of various types of bacteria. Underneath the bacteria the walls were formed by thin tubes composed of non-glandular squamous epithelial-like cells, extending from the tops of the ridges between each glandular pit. There is as yet no evidence of a comparable structure in the stomach of any other pig, or to our knowledge any other forestomach-fermenting mammal.

Freezing survival and cryoprotective dehydration as cold tolerance mechanisms in the Antarctic nematode Panagrolaimus davidi

The relative importance of freezing tolerance and cryoprotective dehydration in the Antarctic nematode Panagrolaimus davidi has been investigated. If nucleation of the medium is initiated at a high subzero temperature (-1 degree C), the nematodes do not freeze but dehydrate. This effect occurs in deionised water, indicating that the loss of water is driven by the difference in vapour pressure of ice and supercooled water at the same temperature. If the nematodes are held above their nucleation temperature for a sufficient time, or are cooled slowly, enough water is lost to prevent freezing (cryoprotective dehydration). However, if the medium is nucleated at lower temperatures or if the sample is cooled at a faster cooling rate, the nematodes freeze and can survive intracellular ice formation. P. davidi thus has a variety of mechanisms that ensure its survival in its harsh terrestrial Antarctic habitat.

Social and individual recognition in rodents: Methodological aspects and neurobiological bases

What animals know about each other, and how they construct and use knowledge of their social world involves at least an ability to recognise different social categories. Although much evidence has accumulated that animals are able to identify and classify other individuals into different categories, few studies have definitively demonstrated true individual recognition, i.e. discrimination between individuals on the basis of their idiosyncratic characteristics. Furthermore, the neural structures and pathways involved in social and, a fortiori, individual recognition have as yet been poorly investigated. This paper discusses various methods and measures currently used to assess different forms of social categorisations in animals, with special reference to rodents. Recent progress concerning the neurobiological bases involved in social recognition is also discussed. Finally, integrative perspectives for studying individual recognition in the context of social cognition is underlined in relation to different approaches investigating rodents' ability to use learned olfactory information.

Freezing rate affects the survival of a short-term freezing stress in Panagrolaimus davidi, an Antarctic nematode that survives intracellular freezing

The ability of the Antarctic nematode Panagrolaimus davidi to survive a short-term freezing stress depended upon the rate of freezing of its surroundings, measured as the duration of the sample exotherm. The freezing rate increased as the sample volume and freezing temperature decreased and resulted in fewer nematodes surviving. This appears to be due to the greater risk of physical damage by ice crystal growth at high freezing rates. Once frozen the nematodes will then survive exposure to lower temperatures. The environment of the nematode is likely to produce the slow rate of freezing of its surroundings that is necessary for its survival.

Acute interferon-alpha administration modulates sucrose consumption in the rat

One of the two core symptoms of depression as defined by the Diagnostic and statistical manual of mental disorders (DSM-IV) (American Psychiatric Association) is anhedonia, or a loss of interest or pleasure. Sucrose consumption has been described as a valid measure of sensitivity to reward. In the present set of studies, changes in sucrose consumption (three-bottle test using 1, 8 and 32% sucrose) were taken as a measure of the anhedonic effect of interferon-alpha (IFN-alpha). Sucrose tests were carried out following the i.p. administration (20 min pre-treatment time) of Recombinant Human Interferon-alphaA (rHIFN-alpha), 10(1), 10(2), 10(4) units(U) and Rat Interferon alpha (rRIFN-alpha), 1,10 and 100 IRU. Both types of IFN-alpha produced a decrease in sucrose consumption and drinking rate (DR) at the highest doses, with the greatest inhibition being at the lowest sucrose concentration (1%). Longer pre-treatment times with rHIFN-alpha (40 and 80 min prior to commencement of 1 h drinking test) resulted in insignificant effects. Significant hypothermia relative to vehicle-injected rats was observed following interferon administration in the 20 min pre-treatment condition, but showed no significant difference when compared to vehicle at 40 or 80 min. Overall these results confirm a depression-like behavioural syndrome (anhedonia) following administration of IFN-alpha.

Attentional and mnemonic deficits associated with infectious disease in humans

BACKGROUND

Infectious diseases are accompanied by behavioural and psychological changes that suggest the implication of the central nervous system. Among them, cognitive alterations have been reported, but their specificity and implication in everyday life are still largely unclear. The purpose of the present study was to evaluate and specify the everyday memory disturbances in sick human subjects and to determinate the role of fever in the appearance of these alterations.

METHODS

The study was carried out in a military training centre for naval recruits. Ninety-one volunteer subjects, healthy (N = 30) or suffering from flu-like syndrome, with (N = 29) or without fever (N = 32), participated in this experiment and were administered a cognitive test (the ERBMT) according to a cross-sectional design for assessing various aspects of everyday memory.

RESULTS

Sick subjects were specifically impaired in daily memory tasks that require the temporary management of a large amount of information. This impairment was similar for the feverish and apyretic sick subjects who both differed from the controls.

CONCLUSION

These findings suggest that infectious disease disturbs the complex cognitive processes that might be associated with attentional functions. Moreover, these results show that fever is not a necessary condition for the appearance of these cognitive disturbances.

[Evaluation of cognitive functions after anesthesia with propofol]

OBJECTIVES

To assess the disturbances and delay of recovery of cognitive functions following propofol anaesthesia, and to evaluate a series of simple cognitive recovery tests.

STUDY DESIGN

Prospective comparative non randomized clinical study.

PATIENTS

Two groups of non premedicated patients, of ASA physical class 1 and 2 were studied. The control group (n = 11) included patients undergoing gastric fibroscopy under local anaesthesia. The propofol group (n = 22) consisted of patients scheduled for coloscopy under propofol anaesthesia.

METHODS

The gastric fibroscopy was performed under local anaesthesia with lidocaine and the coloscopy under general anaesthesia with propofol as the sole anaesthetic. Five cognitive tests, designed to assess short-term memory, delayed memory, the ability to plan complex tasks, attention, and language comprehension were conducted the day before, and 1 hour, 3 hours and 6 hours after the endoscopy.

RESULTS

The cognitive functions remained significantly depressed for at least 3 hours after anaesthesia, and recovered fully about 6 hours after the cessation of propofol administration. The capacity for planning was the most heavily affected.

CONCLUSIONS

Complete recovery can be evaluated by simple cognitive tests, which showed that cognitive functions are impaired over a longer period than psychomotor functions. Oral instructions may therefore not be fully understood by the patient within 3 hours after anaesthesia, emphasizing the importance of written instructions and the essential role played by a well-informed accompanying person.

Differential effects of lipopolysaccharide on pup retrieving and nest building in lactating mice

Behavioral symptoms of sickness that develop in response to lipopolysaccharide (LPS) and proinflammatory cytokines include depressed locomotion, anorexia, and reduced social activities. The way maternal behavior is affected in response to cytokines has, however, not yet been investigated. We checked that lactating mice are sensitive to LPS by showing that LPS- (400 microg/kg, ip) injected mice ate and drank less than saline-injected mothers and displayed a decreased rectal temperature. At an ambient temperature of 22 degrees C, nest building was significantly decreased in LPS-treated mothers compared to saline-treated animals, whereas pup retrieving, while slower, was still present and globally as efficient as for saline-treated mice. In a second experiment, dams were either injected with physiological saline or LPS but were also exposed to a cold ambient temperature (6 degrees C) or kept in standard external condition (22 degrees C). LPS-treated mice exposed to cold expressed not only pup-retrieving but also nest-building activity. These differential results indicate that the behavioral expression of LPS-induced sickness depends on the priority of the behavior under consideration.

Creating RNA bulges: cleavage of RNA in RNA/DNA duplexes by metal ion catalysis

The manipulation of a single-stranded RNA target by forming different RNA/antisense hybrids demonstrates the possibility of cleaving the RNA strand within duplexes. This was achieved using the sequence composition of the antisense oligonucleotide, an approach that results in various bulges [unpaired base(s)] in the RNA target, which is then cleavable at these specific bulge sites under free metal ion or metal complex catalysis. RNA cleavages promoted by metal ions were performed under mild conditions and characterized by separating the RNA fragments carrying end label. The observed products result from intramolecular transesterification causing RNA strand scission. No detectable cleavage of the RNA was observed with either a fully complementary RNA/antisense hybrid or a bulged base in the antisense strand. A molecular modeling study of the RNA backbone suggests that the local conformation of the RNA backbone at a bulge in such hybrid duplexes greatly facilitates the metal-assisted catalytic cleavage. Endonucleolytic RNA cleavage within an RNA/antisense hybrid by metal complexes attached to the antisense oligonucleotide might lead to a new approach in antisense technology with artificial ribonucleases which operate with catalytic turnover.

Human interleukin-3 (IL-3) induces disulfide-linked IL-3 receptor alpha- and beta-chain heterodimerization, which is required for receptor activation but not high-affinity binding

The human interleukin-3 receptor (IL-3R) is a heterodimer that comprises an IL-3 specific alpha chain (IL-3R alpha) and a common beta chain (beta C) that is shared with the receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-5. These receptors belong to the cytokine receptor superfamily, but they are structurally and functionally more related to each other and thus make up a distinct subfamily. Although activation of the normal receptor occurs only in the presence of ligand, the underlying mechanisms are not known. We show here that human IL-3 induces heterodimerization of IL-3R alpha and beta c and that disulfide linkage of these chains is involved in receptor activation but not high-affinity binding. Monoclonal antibodies (MAb) to IL-3R alpha and beta c were developed which immunoprecipitated, in the absence of IL-3, the respective chains from cells labelled with 125I on the cell surface. However, in the presence of IL-3, each MAb immunoprecipitated both IL-3R alpha and beta c. IL-3-induced receptor dimers were disulfide and nondisulfide linked and were dependent on IL-3 interacting with both IL-3R alpha and beta c. In the presence of IL-3 and under nonreducing conditions, MAb to either IL-3R alpha or beta c immunoprecipitated complexes with apparent molecular weights of 215,000 and 245,000 and IL-3R alpha and beta c monomers. Preincubation with iodoacetamide prevented the formation of the two high-molecular-weight complexes without affecting noncovalent dimer formation or high-affinity IL-3 binding. Two-dimensional gel electrophoresis and Western blotting (immunoblotting) demonstrated the presence of both IL-3R alpha and beta c in the disulfide-linked complexes. IL-3 could also be coimmunoprecipitated with anti-IL-3R alpha or anti-beta c MAB, but it was not covalently attached to the receptor. Following IL-3 stimulation, only the disulfide-linked heterodimers exhibited reactivity with antiphosphotyrosine antibodies, with beta c but not IL-3R alpha being the phosphorylated species. A model of IL-3R activation is proposed which may be also applicable to the related GM-CSF and IL-5 receptors.

Cognitive sequelae of propofol anaesthesia

As with any substance that interferes with nervous system functioning, anaesthetics are likely to have neural effects the duration of which extend beyond the acute loss of consciousness. Studies of recovery after anaesthesia have shown that physiological effects and psychomotor functions return to pre-anaesthesia levels within at most 90 min of the cessation of propofol administration. To date no report has been published concerning the possible longer term effects of propofol anaesthesia on higher cognitive functions such as learning, language, reasoning and planning. We evaluated a range of cognitive tasks (short and long-term memory, attention, language comprehension and planning) up to 6 h after cessation of Propofol administration, and found that this set of cognitive functions was still depressed after 3 h, but had recovered by 6 h. The results suggest that, for their security, patients should be remain in a supervised environment for at least 3 h after propofol anaesthesia, and that oral information to patients within those 3 h should be avoided.

Corticosterone regulates behavioral effects of lipopolysaccharide and interleukin-1 beta in mice

The modulatory role of endogenous corticoids in the behavioral effects of lipopolysaccharide (LPS) and recombinant human interleukin-1 beta (IL-1 beta) was studied in mice. Adrenalectomy enhanced the depression of social exploration induced by subcutaneous injection of 200 ng of IL-1 beta or 2 micrograms of LPS. This effect was mimicked by an acute injection of the progesterone antagonist RU-38486 (0.25-1 mg). Chronic replacement with a 15-mg corticosterone pellet abrogated the enhanced susceptibility of adrenalectomized animals to 200 ng of IL-1 beta but had only partial protective effects on their response to 400 ng of IL-1 beta and LPS. These results suggest that the pituitary-adrenal response to cytokines exerts an inhibitory feedback on the cell targets that mediate the behavioral effects of LPS and IL-1 beta.

Pyrogens specifically disrupt the acquisition of a task involving cognitive processing in the rat

In addition to changes in body temperature and other metabolic and physiological responses corresponding to immune activation, pyrogens can induce profound behavioral changes referred to collectively as sickness behavior. One feature of sickness behavior, sometimes reported in clinical settings, but rarely exposed to experimental analysis, is depressed cognitive functioning. The present series of five experiments sought to demonstrate the existence of specific cognitive deficits in rats, independently of any confounding performance effects of pyrogen injections. The behavioral task used, called autoshaping, consisted of presenting hungry Wistar rats with a stimulus (introduction of a retractable lever) that predicted food delivery. Control rats quickly learned to press the lever, although this response does not influence the probability of food delivery. When pyrogens (250 micrograms/kg lipopolysaccharide, 4 micrograms/rat interleukin-1 beta, or 300 mg/rat yeast) were injected to rats during acquisition of this task, they severely disrupted acquisition while the pyrogen was active. The same treatments were, however, without effect on performance when injected later, when performance had stabilized. It is argued that these results demonstrate specific, performance-independent effects of pyrogens on the cognitive processes needed for the acquisition of this task. The results are discussed in terms of the relationship between these effects and the cytokines induced in the brain by pyrogens, and in terms of the exact nature of the cognitive process likely to be affected.

Compared effects of cold ambient temperature and cytokines on macronutrient intake in rats

To compare the effects of cold and cytokines on spontaneous dietary self-selection, rats (n = 14) were given free access to carbohydrate, protein and fat diets for 4 hours a day. After a 10-day period of habituation to this regimen, they were injected with physiological saline, IL-1 beta (4 micrograms/rat ip) or LPS (83 micrograms/rat ip) or exposed to cold (5 degrees C), the order of treatments being randomized. LPS- and IL-1 beta-treated rats ate less, but ingested relatively more carbohydrate and less protein whereas relative fat intake remained unchanged. In contrast, cold exposed rats slightly increased their food intake but in a non significant manner. They also increased their relative intake of fat but did not change their relative intake of carbohydrate and protein. These results are discussed with respect to the pyrogenic and metabolic effects of cytokines.

Behaviour problems in childhood and stressors in early adult life. I. A 20 year follow-up of London school children

The research presented in this paper examined the relationship between the presence of childhood behaviour problems and the rate of life events and difficulties in early adult life. Data are presented from a 20 year follow-up study of a sample of inner London school children first studied when they were aged 10. The key finding was that emotional or behavioural disturbance in childhood was associated with a marked increase in the rate of severely negative events and difficulties some two decades later. This increase was only obtained for stressors with severe negative impact of the type shown in previous investigation to be associated with the onset of psychiatric disorder. Additional results demonstrated that this main finding could not be accounted for by stressors that were a result of adult psychiatric disorder, by the respondent's own behaviour, or by continuing association with the family of origin. The need for a lifespan developmental approach to the well-established stressor-illness is discussed.

Ethological study of the effects of tetrahydroaminoacridine (THA) on social recognition in rats

Two major difficulties confront ethopharmacological investigations on cognitive abilities such as social recognition in drug-treated animals involved in free social interactions. The first concerns the choice of the most relevant behaviours, those reflecting the cognitive abilities attributed to the animals and assessing the specificity of the drug activity, and those reflecting non-specific drug effects. The second refers to the experimenter's awareness that in contrast to physical objects, social stimuli respond to drug-treated subjects and that their own level of responsiveness may influence the changes of drug-treated subjects' social interest. In addition, their contribution may vary according to the different treatments the drug-treated subjects receive. In examining the effects of tetrahydroaminoacridine (THA) at doses of 0.3, 1 and 3 mg/kg on the ability of adult male rats to recognize previously encountered conspecifics, we attempted to take into consideration such difficulties. A detailed behavioural profile of drug-treated rats was reported to separate specific from non-specific effects of THA. In addition, rats were assigned an index of responsibility for contact which takes into account the interactive dimension of each dyad and allows relevant comparisons between different treatments. The doses of THA which were found to decrease the duration of exploration of a familiar juvenile were also found to decrease the number of contacts initiated by the drug-treated subjects. THA induced a relative increase in body care by comparison to saline treatment. However, it had no effect of locomotor activity and rearing of the subjects. These findings enable dissociation of the effects of THA on cognitive versus non-cognitive processes.

Abnormal patterns of maze patrolling in the mutant mouse staggerer

Two experiments describe the abnormal patterns of maze patrolling of adult mutant staggerer mice. The clinical symptoms of this mutant involve exclusively postural and gait abnormalities, apparently due to a disruption of cerebellar architecture leading to a vast reduction in cell numbers and size of this structure. This clinical feature can easily account for the first clear difference reported in these experiments, involving a reduction in the total ambulatory activity in a maze by this mutant. The more interesting result involves different qualitative aspects of the maze patrolling by staggers, compared to normal litter-mate controls. The experiments measured the distribution of subjects' visits to different maze locations, and varied the configuration and the amount of familiarization with the maze. Neither of these factors significantly influenced the basic results. These were the staggerers confined their ambulatory activity to a smaller number of different locations, which were more intensively visited compared to normals, and the staggerers showed a pronounced tendency to return to the place that was most recently visited, compared to a tendency by the normals to avoid that location. It is suggested that these results could be due either to abnormal novelty reactions or to a reduced tendency to pursue an initiated trajectory.

Permanency of gait improvement induced by vestibular stimulation in the mutant mouse staggerer

Among the several methods that have been used to investigate the impact of environmental enrichment, on the behavior of an animal, the use of behaviorally deficient mutant mice has been especially useful. The use of this model allows one to investigate functional recovery compared to a known baseline (the normal animal) without the trauma and imprecision associated with surgical intervention. The present study extends a previous investigation that demonstrated a significant improvement in certain measures of the gait of the cerebellar mutant mouse staggerer, as a result of daily vestibular, muscular and visual stimulation. The results of the present study concerned the durability of that observed improvement. No clear-cut conclusion as to the permanency of the stimulation's effects could be drawn, because results differed according to the measures used. When tested two months after the end of the stimulation period the mutants ran more slowly, with as many "errors" as unstimulated mutants, leading one to infer a deleterious effect of the stimulation. On the other hand, if one considers only the number of "errors" during the test, one may conclude that early stimulation has a permanent advantageous effect of increasing the staggerer's receptivity to further stimulation. Other measures lead to more ambiguous conclusions. Finally, it is argued that even though true improvement in the staggerer's gait can be inferred from these results, and that at least some aspects of that improvement seem to be long-lasting, the generality of the findings cannot validly be extended beyond the precise experimental conditions.