Computer-assisted sleep classification according to the standard of the American Academy of Sleep Medicine: validation study of the AASM version of the Somnolyzer 24 × 7

BACKGROUND

In 2007, the AASM Manual for the Scoring of Sleep and Associated Events was published by the American Academy of Sleep Medicine (AASM). Concerning the visual classification of sleep stages, these new rules are intended to replace the rules by Rechtschaffen and Kales (R&K).

METHODS

We adapted the automatic R&K sleep scoring system Somnolyzer 24 × 7 to comply with the AASM rules and subsequently performed a validation study based on 72 polysomnographies from the Siesta database (56 healthy subjects, 16 patients, 38 females, 34 males, aged 21-86 years). Scorings according to the AASM rules were performed manually by experienced sleep scorers and semi-automatically by the AASM version of the Somnolyzer. Manual scorings and Somnolyzer reviews were performed independently by at least 2 out of 8 experts from 4 sleep centers.

RESULTS

In the quality control process, sleep experts corrected 4.8 and 3.7% of the automatically assigned epochs, resulting in a reliability between 2 Somnolyzer-assisted scorings of 99% (Cohen's kappa: 0.99). In contrast, the reliability between the 2 manual scorings was 82% (kappa: 0.76). The agreement between the 2 Somnolyzer-assisted and the 2 visual scorings was between 81% (kappa: 0.75) and 82% (kappa: 0.76).

CONCLUSION

The AASM version of the Somnolyzer revealed an agreement between semi-automated and human expert scoring comparable to that published for the R&K version with a validity comparable to that of human experts, but with a reliability close to 1, thereby reducing interrater variability as well as scoring time to a minimum.

Magnetic Order and Structure of Ultrathin Films and Multilayers

Ultrathin epitaxial films grown in UHV – Fe(110) on Au(111) and Ag(111), Co(0001) on Au(111) – , sputtered Fe films between Ag and sputtered Fe/Au multilayers were studied by SQUID magnetometry and Mössbauer spectroscopy (CEMS). It could be shown that the magnetic anisotropy relative to the film normal, the, ground state magnetic moment per Fe atom and thermal spin excitations are affected by the structure of the films. In particular, a more 3-dimensional growth mode in the early state of film formation which is observed except in a certain temperature range around 300 K reduces the apparent magnetic interface anisotropy and the ferromagnetic ground state moment, and it enhances the thermal spin fluctuations and the tendency for superparamagnetic relaxation in the thinnest films.

Matrix-assisted autologous chondrocyte implantation into a 14cm(2) cartilage defect, caused by steroid-induced osteonecrosis

Modern chemotherapy protocols have improved the prognosis for acute lymphoblastic leukaemia (ALL), one of the most common paediatric malignancies, but their high-dose corticosteroids lead to osteonecrosis in up to 9% of ALL patients. A 13.5-year-old female patient developed massive osteonecrosis of the right knee after successful ALL treatment. She presented at the age of 17.5 years as a candidate for knee arthroplasty after conservative treatment had failed. Magnetic Resonance Imaging (MRI) revealed severe osteonecrosis, with the cartilage layer of the medial femoral condyle completely detached from the bone. We preferred to attempt a two-step biological reconstruction in this young patient, with arthroscopy of the right knee joint and removal of the dissected cartilage layer of the medial condyle. Matrix-assisted autologous chondrocyte implantation (MACI) was performed with harvested chondrocytes after imaging had indicated vital bone remodelling. Rehabilitation was according to MACI guidelines and after 5.5 years, the patient shows continuous clinical improvement and is satisfied with the result. The Lysholm score improved from 45 to 99 and Tegner's activity score from 1 to 4. MRI follow-up showed a solid cartilage layer covering the medial condyle as a result of bone and chondral regeneration. Even if this approach had failed, bone remodelling would have still provided better conditions for knee arthroplasty.

[Clinical and radiological outcome after trapezium resection with suspension and interposition arthroplasty]

INTRODUCTION

Trapezium resection with suspension and interposition arthroplasty of the thumb-carpometacarpal joint is a common method for treatment of severe osteoarthritis of the 1st carpometacarpal joint.

METHODS

We performed a single center retrospective data analysis after trapezium resection with suspension and interposition arthroplasty of the thumb-carpometacarpal joint with emphasis on quality of life and radiological parameters 3.4 years (1.2-8.7 years) after operation in 60 patients. Pre- and postoperative pain was analysed with VAS, function was measured using the DASH score, pinch grip power with a pinchmeter.

RESULTS

Subjective outcome was rated excellent in 42 cases (64.6%), good in 17 (26.2%), fair in 3 (4.6%) and 3 times (4.6%) poor. 56 patients (93.3%) would like to be operated again; 4 patients (6.7%) would deny an operation retrospectively. In the VAS pain was reduced by about 75% compared to the preoperative value. The pinch grip was increased by 46.6% compared to the preoperative value. The rate of major complications was 1.5% and of minor complications 9.2 %.

CONCLUSION

Trapezium resection with suspension and interposition arthroplasty can increase the quality of life and reduce pain in patients with severe osteoarthritis of the 1st carpometacarpal joint. The rate of complications is low. Outcome assessment is possible by subjective parameters. Objective values like the range of movement or the decrease of the distance between metacarpal I and scaphoid do not correlate with outcome.

Functional analyses of Src-like adaptor (SLA), a glucocorticoid-regulated gene in acute lymphoblastic leukemia

Glucocorticoids (GCs) cause apoptosis and cell cycle arrest in lymphoid cells and are used in the therapy of lymphoid malignancies. SLA (Src-like-adaptor), an inhibitor of T- and B-cell receptor signaling, is a promising candidate derived from expression profiling analyses in children with acute lymphoblastic leukemia (ALL). Over-expression and knock-down experiments in ALL in vitro model revealed that transgenic SLA alone had no effect on survival or cell cycle progression, nor did it affect sensitivity to, or kinetics of, GC-induced apoptosis. Although SLA is a prominent GC response gene, it does not seem to contribute to the anti-leukemic effects of GC.

Sleep classification according to AASM and Rechtschaffen & Kales: effects on sleep scoring parameters

STUDY OBJECTIVE

To investigate differences between visual sleep scoring according to the classification developed by Rechtschaffen and Kales (R&K, 1968) and scoring based on the new guidelines of the American Academy of Sleep Medicine (AASM, 2007).

DESIGN

All-night polysomnographic recordings were scored visually according to the R&K and AASM rules by experienced sleep scorers. Descriptive data analysis was used to compare the resulting sleep parameters.

PARTICIPANTS

Healthy subjects and patients (38 females and 34 males) aged between 21 and 86 years.

INTERVENTIONS

N/A.

MEASUREMENT AND RESULTS

While sleep latency and REM latency, total sleep time, and sleep efficiency were not affected by the classification standard, the time (in minutes and in percent of total sleep time) spent in sleep stage 1 (S1/N1), stage 2 (S2/N2) and slow wave sleep (S3+S4/N3) differed significantly between the R&K and the AASM classification. While light and deep sleep increased (S1 vs. N1 [+10.6 min, (+2.8%)]: P<0.01; S3+S4 vs. N3 [+9.1 min (+2.4%)]: P<0.01), stage 2 sleep decreased significantly according to AASM rules (S2 vs. N2 [-20.5 min, (-4.9%)]: P<0.01). Moreover, wake after sleep onset was significantly prolonged by approximately 4 minutes (P<0.01) according to the AASM standard. Interestingly, the effects on stage REM were age-dependent (intercept at 20 years: -7.5 min; slope: 1.6 min for 10-year age increase). No effects of sex and diagnosis were observed.

CONCLUSION

The study shows significant and age-dependent differences between sleep parameters derived from conventional visual sleep scorings on the basis of R&K rules and those based on the new AASM rules. Thus, new normative data have to be established for the AASM standard.

The HSG procedure for modelling integrated urban wastewater systems

Whilst the importance of integrated modelling of urban wastewater systems is ever increasing, there is still no concise procedure regarding how to carry out such modelling studies. After briefly discussing some earlier approaches, the guideline for integrated modelling developed by the Central European Simulation Research Group (HSG - Hochschulgruppe) is presented. This contribution suggests a six-step standardised procedure to integrated modelling. This commences with an analysis of the system and definition of objectives and criteria, covers selection of modelling approaches, analysis of data availability, calibration and validation and also includes the steps of scenario analysis and reporting. Recent research findings as well as experience gained from several application projects from Central Europe have been integrated in this guideline.

Pollution load modelling in sewer systems: an approach of combining long term online sensor data with multi-objective auto-calibration schemes

Pollutant load modelling for sewer systems is state-of-the-art, especially for the estimation of discharged pollutant loads and development of sewer management strategies. However, conventionally obtained calibration data sets are often not exhaustive and have significant drawbacks. In the Graz West catchment area (Graz, Austria), continuous high-resolution long-term online measurements for discharge and pollutant concentration have been carried out since 2002.In this paper, the application of single- and multi-objective auto-calibration schemes based on evolution strategies for a deterministic hydrological pollutant load model will be discussed. Three approaches for pollutant load modelling are examined and compared: using a constant storm weather concentration and two surface accumulation-wash-off approaches with basic respectively extended wash-off equations. It is shown that the applied auto-calibration method leads to very satisfying results for both the calibration and the validation data set, and also for the dry and the storm weather runoff. Results from multi-objective calibration show better robustness in validation events than single-objective calibration. The build-up wash-off approach using the basic wash-off equation gives the best correlations between measured data and simulation results.

Instrumental conditioning of human sensorimotor rhythm (12-15 Hz) and its impact on sleep as well as declarative learning

STUDY OBJECTIVES

To test whether instrumental conditioning of sensorimotor rhythm (SMR; 12-15 Hz) has an impact on sleep parameters as well as declarative memory performance in humans.

DESIGN

Randomized, parallel group design

SETTING

10 instrumental conditioning sessions, pre- and posttreatment investigation including sleep evaluations

PARTICIPANTS

27 healthy subjects (13 male)

INTERVENTIONS

SMR-conditioning (experimental group) or randomized-frequency conditioning (control group); declarative memory task before and after a 90-min nap

MEASUREMENT AND RESULTS

The experimental group was trained to enhance the amplitude of their SMR-frequency range, whereas the control group participated in a randomized-frequency conditioning program (i.e., every session a different 3-Hz frequency bin between 7 and 20 Hz). During pre- and posttreatment the subjects had to attend the sleep laboratory to take a 90-min nap (2:00-3:30 pm) and to perform a declarative memory task before and after sleep. The experimental design was successful in conditioning an increase in relative 12-15 Hz amplitude within 10 sessions (d = 0.7). Increased SMR activity was also expressed during subsequent sleep by eliciting positive changes in different sleep parameters (sleep spindle number [d = 0.6], sleep onset latency [d = 0.7]); additionally, this increased 12-15 Hz amplitude was associated with enhancement in retrieval score computed at immediate cued recall (d = 0.9).

CONCLUSION

Relative SMR amplitude increased over 10 instrumental conditioning sessions (in the experimental group only) and this "shaping of one's own brain activity" improved subsequent declarative learning and facilitated the expression of 12-15 Hz spindle oscillations during sleep. Most interestingly, these electrophysiological changes were accompanied by a shortened sleep onset latency.

Is there a link between sleep changes and memory in Alzheimer's disease?

Aging and Alzheimer's disease (AD) are both characterized by memory impairments and sleep changes. We investigated the potential link between these disturbances, focusing on sleep spindles, involved in memory consolidation. Two episodic memory tasks were given to young and old healthy participants, as well as to AD patients. Postlearning sleep was recorded. Sleep spindles were globally reduced in aging and AD. AD patients also exhibited a further decrease in fast spindles. Besides, mean intensity of fast spindles was positively correlated, in AD patients, with immediate recall performance. Our results are the first report of a specific decrease in fast spindles in AD, associated with learning abilities. They also give further hints for a functional differentiation between slow and fast spindles.

Top-fenestrating technique in stentgrafting of aortic diseases with mid-term follow-up

AIM

As a consequence of the rapid growth of thoracic and abdominal endovascular aneurysm repair management of aortic branches has come into focus. The top-fenestrating technique can be used where one or two of the renal arteries, the left carotid artery or the left subclavian artery, have deliberately been covered by a stent-graft and immediately reopened by a preplaced stent. The aim of this study is to evaluate whether this technique is feasible and durable.

METHODS

Registry study on 24 patients endovascular repaired with the top-fenestrating technique between September 2004 and January 2008. Elective operations were performed in 15 patients and acute procedures in nine. The median neck length for the patients having a carotid stent was 0 mm, range -18-15, related to the left subclavian artery and median 11 mm, range 0-31 mm, for those having a renal stent. Altogether 25 stents were used.

RESULTS

There were two postoperative deaths. One patient died from a cardiac infarction and the other, a ruptured thoracic aortic aneurysm, had a major stroke. Median follow-up time was 17 months (range 1-40 months). Two patients died during follow-up from no-aneurysm related reasons. One type I endoleak was solved with a secondary intervention. Two patients had type II endoleak, which was not treated. After 12 months, 71% of the aneurysms had significantly decreased in size. None of the aneurysms had increased. There were no stent-graft migrations in the entire group. None of the stented branches was lost during follow-up.

CONCLUSION

The top-fenestrating technique is feasible in short aortic necks and results are durable in a mid-term follow-up perspective.

Extracapsular tumor spread and the risk of local, axillary and supraclavicular recurrence in node-positive, premenopausal patients with breast cancer

BACKGROUND

Extracapsular tumor spread (ECS) has been identified as a possible risk factor for breast cancer recurrence, but controversy exists regarding its role in decision making for regional radiotherapy. This study evaluates ECS as a predictor of local, axillary, and supraclavicular recurrence.

PATIENTS AND METHODS

International Breast Cancer Study Group Trial VI accrued 1475 eligible pre- and perimenopausal women with node-positive breast cancer who were randomly assigned to receive three to nine courses of classical combination chemotherapy with cyclophosphamide, methotrexate, and fluorouracil. ECS status was determined retrospectively in 933 patients based on review of pathology reports. Cumulative incidence and hazard ratios (HRs) were estimated using methods for competing risks analysis. Adjustment factors included treatment group and baseline patient and tumor characteristics. The median follow-up was 14 years.

RESULTS

In univariable analysis, ECS was significantly associated with supraclavicular recurrence (HR = 1.96; 95% confidence interval 1.23-3.13; P = 0.005). HRs for local and axillary recurrence were 1.38 (P = 0.06) and 1.81 (P = 0.11), respectively. Following adjustment for number of lymph node metastases and other baseline prognostic factors, ECS was not significantly associated with any of the three recurrence types studied.

CONCLUSIONS

Our results indicate that the decision for additional regional radiotherapy should not be based solely on the presence of ECS.

Automatic sleep classification according to Rechtschaffen and Kales

Conventionally, polysomnographic recordings are classified according to the rules published in 1968 by Rechtschaffen and Kales (R&K). The present paper describes an automatic classification system embedded in an e-health solution that has been developed and validated in a large database of healthy controls and sleep disturbed patients. The Somnolyzer 24x7 adheres to the decision rules for visual scoring as closely as possible and includes a structured quality control procedure by a human expert. The final system consists of a raw data quality check, a feature extraction algorithm (density and intensity of sleep/wake-related patterns such as sleep spindles, delta waves, slow and rapid eye movements), a feature matrix plausibility check, a classifier designed as an expert system and a rule-based smoothing procedure for the start and the end of stages REM and 2. The validation based on 286 recordings in both normal healthy subjects aged 20 to 95 years and patients suffering from organic or nonorganic sleep disorders demonstrated an overall epoch-by-epoch agreement of 80% (Cohen's Kappa: 0.72) between the Somnolyzer 24x7 and the human expert scoring, as compared with an inter-rater reliability of 77% (Cohen's Kappa: 0.68) between two human experts. Two Somnolyzer 24x7 analyses (including a structured quality control by two human experts) revealed an inter-rater reliability close to 1 (Cohen's Kappa: 0.991). Moreover, correlation analysis in R&K derived target variables revealed similar -- in 36 out of 38 variables even higher -- relationships between Somnolyzer 24x7 and expert evaluations as compared to the concordance between two human experts. Thus, the validation study proved the high reliability and validity of the Somnolyzer 24x7 both, on the epoch-by-epoch and on the target variable level. These results demonstrate the applicability of the Somnolyzer 24x7 evaluation in clinical routine and sleep studies.