Sleep quality, the neglected outcome variable in clinical studies focusing on locomotor system; a construct validation study

In addition to general health and pain, sleep is highly relevant to judging the well-being of an individual. Of these three important outcome variables, however, sleep is neglected in most outcome studies.Sleep is a very important resource for recovery from daily stresses and strains, and any alteration of sleep will likely affect mental and physical health, especially during disease. Sleep assessment therefore should be standard in all population-based or clinical studies focusing on the locomotor system. Yet current sleep assessment tools are either too long or too specific for general use.

Periosteal Distraction Osteogenesis and Barrier Membrane Application: An Experimental Study in the Rat Calvaria

Background: Distraction of the periosteum results in the formation of new bone in the gap between the periosteum and the original bone. We postulate that the use of a barrier membrane would be beneficial for new bone formation in periosteal distraction. Methods: To selectively influence the contribution of the periosteum, a distraction plate with perforations was used alone or covered by a collagen barrier membrane. All animals were subjected to a 7-day latency period and a 10-day distraction period with a rate of 0.1 mm/day. Four animals per group with or without a barrier membrane were sacrificed at 2, 4, and 6 weeks after the end of the distraction. The height of new bone generated relative to the areas bound by the parent bone and the periosteum was determined by histomorphometric methods. Results: New bone was found in all groups. At the periphery of the distraction plate, significant differences in bone height were found between the hinge and the distraction screw for the group without barrier membrane at 2 weeks (0.39 ± 0.19 mm) compared to 4 weeks (0.84 ± 0.44 mm; P = 0.002) and 6 weeks (1.06 ± 0.39 mm; P = 0.004). Differences in maximum bone height with and without a barrier membrane were observed laterally to the distraction plate at 2 weeks (1.22 ± 0.64 versus 0.55 ± 0.14 mm; P = 0.019) and 6 weeks (1.61 ± 0.56 versus 0.73 ± 0.33 mm; P = 0.003) of the consolidation period. Conclusion: Within the limitations of the present study, the application of a barrier membrane may be considered beneficial for new bone formation induced by periosteal distraction.

Recruitment dynamics of the grove-dominant tree Microberlinia bisulcata in African rain forest: extending the light response versus adult longevity trade-off concept

In groves of ectomycorrhizal caesalpiniaceous species in the Atlantic coastal forest of Central Africa the dominant tree Microberlinia bisulcata, which is shade-intolerant as a seedling but highly light-responding as a sapling, shows very limited regeneration. M. bisulcata saplings were mapped in an 82.5-ha plot at Korup and found to be located significantly far (>40 m) away from adults, a result confirmed by direct testing in a second 56-ha plot. Sapling growth over 6 years, the distribution of newly emerging seedlings around adults, recruitment of saplings in a large opening and the outward extent of seedlings at the grove edge were also investigated. Two processes appear to have been operating: (1) a very strong and consistent restriction of the very numerous seedlings establishing after masting close to adults, and (2) a strong but highly spatially variable promotion of distant survivors by increased light from the deaths of large trees of species other than M. bisulcata (which itself has very low mortality rate). This leads to an apparent escape-from-adults effect. To maintain saplings in the shade between multiple short periods of release ectomycorrhizal connections to other co-occurring caesalp species may enable a rachet-type mechanism. The recorded sapling dynamics currently contribute an essential part of the long-term cycling of the groves. M. bisulcata is an interesting example of an important group of tropical trees, particularly in Africa, which are both highly light-demanding when young yet capable also of forming very large forest emergents. To more comprehensively explain tropical tree responses, the case is made for adding a new dimension to the trade-off concept of early tree light-response versus adult longevity.

DESIGN OF A LIQUID FUEL INJECTOR FOR ALTERNATIVE FUEL STUDIES IN AN ATMOSPHERIC MODEL GAS TURBINE COMBUSTOR

A new liquid-fuel injector was designed for use in the atmospheric-pressure, model gas turbine combustor in Bucknell University’s Combustion Research Laboratory during alternative fuel testing. The current liquid-fuel injector requires a higher-than-desired pressure drop and volumetric flow rate to provide proper atomization of liquid fuels. An air-blast atomizer type of fuel injector was chosen and an experiment utilizing water as the working fluid was performed on a variable-geometry prototype. Visualization of the spray pattern was achieved through photography and the pressure drop was measured as a function of the required operating parameters. Experimental correlations were used to estimate droplet sizes over flow conditions similar to that which would be experienced in the actual combustor. The results of this experiment were used to select the desired geometric parameters for the proposed final injector design and a CAD model was generated. Eventually, the new injector will be fabricated and tested to provide final validation of the design prior to use in the combustion test apparatus.

Technical Feasibility and Application of Mechanical Thrombectomy with the Solitaire FR Revascularization Device in Acute Basilar Artery Occlusion

Acute BAO is a devastating neurological condition associated with a poor clinical outcome and a high mortality rate. Recanalization has been identified as a major prognostic factor for good outcome in BAO. Mechanical thrombectomy using retrievable stents is an emerging treatment option for acute stroke. First clinical trials using stent retrievers have shown promising high recanalization rates. However, these studies mainly included large artery occlusions in the anterior circulation with only a few or single cases of BAO. Therefore, the purpose of this study was to evaluate technical feasibility, safety, and efficacy of mechanical thrombectomy using retrievable stent in the treatment of acute BAO.

Systematic review of the survival rate and the incidence of biological, technical, and aesthetic complications of single crowns on implants reported in longitudinal studies with a mean follow-up of 5 years

To assess the 5-year survival of implant-supported single crowns (SCs) and to describe the incidence of biological, technical, and aesthetic complications. The focused question was: What is the survival rate of implants supporting single crowns and implant-supported crowns with a mean follow-up of 5 years and to which extent do biological, technical, and aesthetic complications occur?

Impact of admission glucose and diabetes on recanalization and outcome after intra-arterial thrombolysis for ischaemic stroke

BACKGROUND: Stroke patients with diabetes and admission hyperglycaemia have worse outcomes than non-diabetics, with or without intravenous thrombolysis. Poor vessel recanalization was reported in diabetics treated with intravenous thrombolysis. AIMS: This study aimed to determine the impact of admission glucose and diabetes on recanalization and outcome after intra-arterial thrombolysis. METHODS: We analysed 389 patients (213 men, 176 women) treated with intra-arterial thrombolysis. The association of diabetes and admission glucose value with recanalization, outcome, mortality, and symptomatic intracranial haemorrhage was determined. Recanalization was classified according to thrombolysis in myocardial infarction grades. Outcome was measured using the modified Rankin Scale at three-months and categorized as favourable (modified Rankin Scale 0-2) or poor (modified Rankin Scale 3-6). RESULTS: The rate of partial or complete recanalization (thrombolysis in myocardial infarction 2-3) did not differ between patients with and without diabetes (67% vs. 66%; P = 1·000). Mean admission glucose values were similar in patients with poor recanalization (thrombolysis in myocardial infarction 0-1) and patients with partial or complete recanalization (thrombolysis in myocardial infarction 2-3; 7·3 vs. 7·3 mmol/l; P = 0·746). Follow-up at three-months was obtained in 388 of 389 patients. Clinical outcome was favourable (modified Rankin Scale 0-2) in 189 patients (49%) and poor (modified Rankin Scale 3-6) in 199 patients (51%). Mortality at three-months was 20%. Diabetics were more likely to have poor outcome (72% vs. 48%; P = 0·001) and to be dead (30% vs. 19%; P = 0·044) at three-months. After multivariable analysis, there remained an independent relationship between diabetes and outcome (P = 0·003; odds ratio 3·033, 95% confidence interval 1·452-6·336), but not with mortality (P = 0·310; odds ratio 1·436; 95% confidence interval 0·714-2·888). Moreover, higher age (P = 0·001; odds ratio 1·039; 95% confidence interval 1·017-1·061), higher baseline National Institutes of Health Stroke Scale score (P < 0·0001; odds ratio 1·130; 95% confidence interval 1·079-1·182), location of vessel occlusion as categorical variable (P < 0·0001), poor collaterals (P = 0·02; odds ratio 1·587; 95% confidence interval 1·076-2·341), poor vessel recanalization (P < 0·0001; odds ratio 4·713; 95% confidence interval 2·627-8·454), and higher leucocyte count (P = 0·032; odds ratio 1·094; 95% confidence interval 1·008-1·188) were independent baseline predictors of poor outcome. Higher admission glucose was associated with poor outcome (P = 0·006) and mortality (P < 0·0001). After multivariate analyses, glucose remained independently associated with poor outcome (P = 0·019; odds ratio 1·150; 95% confidence interval 1·023-1-292) and mortality (P = 0·005; odds ratio 1·183; 95% confidence interval 1052-1·331). The rate of symptomatic intracranial haemorrhage was similar in diabetics and non-diabetics (6·7% vs. 4·6%; P = 0·512). Mean admission glucose was higher in patients with symptomatic intracranial haemorrhage than without (8·58 vs. 7·26 mmol/l; P = 0·010). Multivariable analysis confirmed an independent association between admission glucose and symptomatic intracranial haemorrhage (P = 0·027; odds ratio 1·187; 95% confidence interval 1·020-1·381). CONCLUSIONS: Diabetes and glucose value on admission did not influence recanalization after intra-arterial thrombolysis; nevertheless, they were independent predictors of poor outcome after intra-arterial thrombolysis and a higher admission glucose value was an independent predictor of symptomatic intracranial haemorrhage. This indicates that factors on the capillary, cellular, or metabolic level may account for the worse outcome in patients with elevated glucose value and diabetes.

High acceptance rate of hybrid allogeneic-autologous umbilical cord blood banking among actual and potential Swiss donors

Two competitive concepts of umbilical cord blood (UCB) banking are currently available: either allogeneic UCB is donated to a public bank or autologous cells are stored in a private bank. Allogeneic-autologous hybrid banking is a new concept that combines these two approaches. However, acceptance of hybrid UCB banking among potential donors is unknown to date.

Tests for Comparing Mark-Specific Hazards and Cumulative Incidence Functions

It is of interest in some applications to determine whether there is a relationship between a hazard rate function (or a cumulative incidence function) and a mark variable which is only observed at uncensored failure times. We develop nonparametric tests for this problem when the mark variable is continuous. Tests are developed for the null hypothesis that the mark-specific hazard rate is independent of the mark versus ordered and two-sided alternatives expressed in terms of mark-specific hazard functions and mark-specific cumulative incidence functions. The test statistics are based on functionals of a bivariate test process equal to a weighted average of differences between a Nelson--Aalen-type estimator of the mark-specific cumulative hazard function and a nonparametric estimator of this function under the null hypothesis. The weight function in the test process can be chosen so that the test statistics are asymptotically distribution-free.Asymptotically correct critical values are obtained through a simple simulation procedure. The testing procedures are shown to perform well in numerical studies, and are illustrated with an AIDS clinical trial example. Specifically, the tests are used to assess if the instantaneous or absolute risk of treatment failure depends on the amount of accumulation of drug resistance mutations in a subject's HIV virus. This assessment helps guide development of anti-HIV therapies that surmount the problem of drug resistance.

Analysis of stapling versus endoloops in appendiceal stump closure

BACKGROUND: The effectiveness of various appendiceal stump closure methods has not been evaluated systematically. The aim of this study was to compare the morbidity of stump closure by stapling or use of endoloops. METHODS: A non-concurrent cohort study of prospectively acquired data was performed. The primary outcome variable was the rate of intra-abdominal surgical-site infection. Secondary outcome measures were complications, duration of intervention, hospital stay, rate of readmission to hospital and the difference in direct costs of the operation. RESULTS: Staples were used in 60.5 per cent and endoloops in 39.5 per cent of 6486 patients operated on for suspected appendicitis between January 1995 and December 2003. Among 4489 patients with acute appendicitis the rate of intra-abdominal surgical-site infection was 0.7 per cent in the stapler group and 1.7 per cent in the endoloop group (P = 0.004). The rate of readmission to hospital was 0.9 and 2.1 per cent respectively (P = 0.001). CONCLUSION: Application of a stapler for transection and closure of the appendiceal stump in patients with acute appendicitis lowered the risk of postoperative intra-abdominal surgical-site infection and the need for readmission to hospital.

Survival Analysis with Large Dimensional Covariates: An Application in Microarray Studies

Use of microarray technology often leads to high-dimensional and low- sample size data settings. Over the past several years, a variety of novel approaches have been proposed for variable selection in this context. However, only a small number of these have been adapted for time-to-event data where censoring is present. Among standard variable selection methods shown both to have good predictive accuracy and to be computationally efficient is the elastic net penalization approach. In this paper, adaptation of the elastic net approach is presented for variable selection both under the Cox proportional hazards model and under an accelerated failure time (AFT) model. Assessment of the two methods is conducted through simulation studies and through analysis of microarray data obtained from a set of patients with diffuse large B-cell lymphoma where time to survival is of interest. The approaches are shown to match or exceed the predictive performance of a Cox-based and an AFT-based variable selection method. The methods are moreover shown to be much more computationally efficient than their respective Cox- and AFT- based counterparts.