Resonance-stabilized hydrocarbon-radical chain reactions may explain soot inception and growth.

Mystery surrounds the transition from gas-phase hydrocarbon precursors to terrestrial soot and interstellar dust, which are carbonaceous particles formed under similar conditions. Although polycyclic aromatic hydrocarbons (PAHs) are known precursors to high-temperature carbonaceous-particle formation, the molecular pathways that initiate particle formation are unknown. We present experimental and theoretical evidence for rapid molecular clustering-reaction pathways involving radicals with extended conjugation. These radicals react with other hydrocarbon species to form covalently bound complexes that promote further growth and clustering by regenerating resonance-stabilized radicals through low-barrier hydrogen-abstraction and hydrogen-ejection reactions. Such radical-chain reaction pathways may lead to covalently bound clusters of PAHs and other hydrocarbons that would otherwise be too small to condense at high temperatures, thus providing the key mechanistic steps for rapid particle formation and surface growth by hydrocarbon chemisorption.

A small porous-plug burner for studies of combustion chemistry and soot formation.

We have developed and built a small porous-plug burner based on the original McKenna burner design. The new burner generates a laminar premixed flat flame for use in studies of combustion chemistry and soot formation. The size is particularly relevant for space-constrained, synchrotron-based X-ray diagnostics. In this paper, we present details of the design, construction, operation, and supporting infrastructure for this burner, including engineering attributes that enable its small size. We also present data for charactering the flames produced by this burner. These data include temperature profiles for three premixed sooting ethylene/air flames (equivalence ratios of 1.5, 1.8, and 2.1); temperatures were recorded using direct one-dimensional coherent Raman imaging. We include calculated temperature profiles, and, for one of these ethylene/air flames, we show the carbon and hydrogen content of heavy hydrocarbon species measured using an aerosol mass spectrometer coupled with vacuum ultraviolet photoionization (VUV-AMS) and soot-volume-fraction measurements obtained using laser-induced incandescence. In addition, we provide calculated mole-fraction profiles of selected gas-phase species and characteristic profiles for seven mass peaks from AMS measurements. Using these experimental and calculated results, we discuss the differences between standard McKenna burners and the new miniature porous-plug burner introduced here.

Design and characterization of a linear Hencken-type burner.

We have designed and constructed a Hencken-type burner that produces a 38-mm-long linear laminar partially premixed co-flow diffusion flame. This burner was designed to produce a linear flame for studies of soot chemistry, combining the benefit of the conventional Hencken burner's laminar flames with the advantage of the slot burner's geometry for optical measurements requiring a long interaction distance. It is suitable for measurements using optical imaging diagnostics, line-of-sight optical techniques, or off-axis optical-scattering methods requiring either a long or short path length through the flame. This paper presents details of the design and operation of this new burner. We also provide characterization information for flames produced by this burner, including relative flow-field velocities obtained using hot-wire anemometry, temperatures along the centerline extracted using direct one-dimensional coherent Raman imaging, soot volume fractions along the centerline obtained using laser-induced incandescence and laser extinction, and transmission electron microscopy images of soot thermophoretically sampled from the flame.

A single gene defect causing claustrophobia.

Claustrophobia, the well-known fear of being trapped in narrow/closed spaces, is often considered a conditioned response to traumatic experience. Surprisingly, we found that mutations affecting a single gene, encoding a stress-regulated neuronal protein, can cause claustrophobia. Gpm6a-deficient mice develop normally and lack obvious behavioral abnormalities. However, when mildly stressed by single-housing, these mice develop a striking claustrophobia-like phenotype, which is not inducible in wild-type controls, even by severe stress. The human GPM6A gene is located on chromosome 4q32-q34, a region linked to panic disorder. Sequence analysis of 115 claustrophobic and non-claustrophobic subjects identified nine variants in the noncoding region of the gene that are more frequent in affected individuals (P=0.028). One variant in the 3'untranslated region was linked to claustrophobia in two small pedigrees. This mutant mRNA is functional but cannot be silenced by neuronal miR124 derived itself from a stress-regulated transcript. We suggest that loosing dynamic regulation of neuronal GPM6A expression poses a genetic risk for claustrophobia.

[Medial hip neck fracture: influence of pre-operative delay on the quality of outcome. Results of data from the external in-hospital quality assurance within the framework of secondary data analysis]. / Mediale Schenkelhalsfraktur: Einfluss des Versorgungszeitpunkts auf die Ergebnisqualität. Ergebnisse der Daten der externen stationären Qualitätssicherung im Rahmen sekundärer Datennutzung.

PROBLEM: According to international and national studies and clinical guidelines, patients with medial hip neck fracture should receive surgery as soon as medically reasonable after hospitalization, preferably within 48 h. Analysis of the German quality registry data of 2006 showed, however, that in 13 out of the 16 federal states less than 85% of patients were operated on within 48. Delayed surgery was found especially during the weekend. OBJECTIVE: The objective of the study was to examine whether German data confirm that a short preoperative waiting time after hip fracture improves the outcome. The study was commissioned by the Federal Joint Committee (G-BA) and was jointly performed by the German Society for Accident Surgery (DGU) and the National Institute for Quality in Healthcare (BQS). DATA AND METHODS: The analysis is based on the data of the nationwide quality registry of the years 2004-2006. Out of a total of 129,075 patients with a medial hip neck fracture 22,171 received operative treatment later than 48 h after hospital admission. Comparable study groups were constructed with the help of a propensity score (1-to-1 matching). Study and control groups only differed in terms of delay of surgery. The comparison concerning the outcomes was made with the Fisher exact test (bilateral). RESULTS: In the group of patients with a delay of surgery longer than 48 h significantly higher rates of surgical complications (OR 1.10), general complications (OR 1.09) and pressure ulcers (1.27) were observed (all p<0.001). The in-hospital mortality showed no significant difference (OR 0.96, p=0.302). CONCLUSIONS: Patients with medial hip neck fracture should receive operative treatment without delay, if no medical contra-indications for immediate surgery. In particular appropriate organizational measures should be taken to ensure an early surgical treatment even during weekends.

[Determining the indication for primary total hip and knee replacement. Results of external quality assurance of over 270,000 primary total hip and knee replacements]. / Indikationsstellung in der primären Hüft- und Kniegelenkendoprothetik. Ergebnisse der externen Qualitätssicherung von über 270.000 primären Hüft- und Kniegelenkendoprothesen.

BACKGROUND: The German mandatory quality assurance programme collects data from all primary total hip and knee replacements. The quality of the indication is measured by clinical and radiological criteria. The results were analysed in terms of differences in establishing the indication subject to patient and hospital characteristics. MATERIALS AND METHODS: Data on more than 270,000 primary total hip and knee replacements that were operated in 2006 in Germany were analysed concerning differences in the quality of the indication subject to age, gender, hospital volume and density of population and hospitals (metropolitan vs rural areas). The statistical analysis was done by exact Fisher's test. RESULTS: The quality of the indication was statistically significantly better in men, patients 60 and older, in rural areas and in high volume hospitals (50 and more joint replacements per year). DISCUSSION: Data of this mandatory German quality assurance programme are useful to describe differences in medical care. The results are valid and complete. An exact analysis of the reasons for these differences is difficult though. Data focus is on quality assurance and represent only in-hospital results. CONCLUSION: Further analyses are necessary to ascertain whether the differences in quality of care are deficits or only variances in medical care.

[Experience in orthopaedic surgery with minimum provider volumes]. / Erfahrungen mit Mindestmengen in der Orthopädie.

The implementation of minimum provider volumes in orthopaedic surgery appears to be logically evident. A general volume outcome relationship could be found for total knee and hip replacement on a high level of evidence, but no definite threshold value could be identified. For other orthopaedic procedures the evaluated data hint at a volume outcome relationship but do not prove one. Preliminary model calculations on the effects of a regulation based on volume outcome considerations concerning medical care in Germany show that, though for total hip and knee replacement quite a large number of hospitals would be excluded from medical care, the number of patients to be reallocated would be small. Since 1 January 2007 a minimum provider volume of 50 total knee replacements per year per hospital has been mandatory in Germany. The further application of a minimum requirement regulation based on volume outcome considerations in the German health care system must be performed very carefully, because significant effects are to be expected.

[Volume-outcome-relationship in total hip replacement--literature review and model calculation of the health care situation]. / Mindestmengen in der Hüftgelenksendoprothetik bei Coxarthrose und Schenkelhalsfraktur--Evidenzbericht und Modellrechnung zur Auswirkung auf die flächendeckende Versorgung.

AIM: The aim of this study was to assess the volume-outcome relationship of total hip replacement and the effects of its application on medical care in Germany. METHOD: Electronic bibliographic databases, the reference lists of relevant articles and various health services research-related resources were searched and selected studies were assessed. Additionally, the consequences of implementing a regulation based on volume-outcome relations were calculated by using administrative data in different settings. RESULTS: The results in the literature concerning defined outcome parameters are inconsistent, but a general correlation between high volume and low complication rate could be identified. Implementing a regulation based on volume-outcome relationship with cut-off points of 20/50 total hip replacements/year would lead to an exclusion of 216 (17%)/483 (38%) hospitals, respectively, from medical care. This would result in a reallocation of 2214 (1.4%)/11,476 (7.4%) patients/year, respectively (extrapolation). CONCLUSION: The application of a minimum requirement regulation based on volume-outcome considerations in the German health care system must be performed very sensitively, because significant effects are to be expected.

[Is it possible to calculate minimum provider volumes for total knee replacement using routine data? Results of a threshold value analysis of German quality assurance data for inpatient treatment]. / Können Mindestmengen für Knieprothesen anhand von Routinedaten errechnet werden? Ergebnisse einer Schwellenwertanalyse mit Daten der externen stationären Qualitätssicherung.

AIM OF THE STUDY: The aim of this study was to calculate, for the first time, minimum provider volumes in total knee replacement using routine German data. MATERIALS AND METHODS: In patients with primary total knee replacement (TKR), the relationship between hospital volume per year and risk of "insufficient mobility" (primary quality indicator) and "wound infection" (secondary quality indicator) was calculated by means of logistic regression models. RESULTS: For both indicators, a statistically significant relationship between hospital volume and outcome could be demonstrated. Other risk factors such as age and ASA status also had a significant influence, but did not appear as important confounders. The risk for the secondary quality indicator "infection" decreased constantly with increasing hospital volume, thus the curve was very flat. This supports the hypothesis that high volume hospitals have a higher quality level than low volume hospitals. A threshold value could be calculated. However, the explanation value for hospital volume was too low to derive a threshold level that clearly discriminates between good and bad quality of care. The relationship between the primary quality indicator "insufficient mobility" and hospital volume unexpectedly showed a U-shaped distribution. This questions the concept of a minimum provider volume regulation for primary total knee replacement for the quality indicator "insufficient mobility". Therefore, in this case no quantitative threshold values were calculated. CONCLUSION: This analysis supports the hypothesis of a volume-outcome relationship in primary total knee replacement. However, a minimum provider volume that clearly discriminates between good and bad quality of care could not be calculated on the basis of these German quality assurance data.

Aromatase expression in the human temporal cortex.

The expression of the human cyp19 gene, encoding P450 aromatase, the key enzyme for estrogen biosynthesis, involves alternative splicing of multiple forms of exon I regulated by different promoters. Aromatase expression has been detected in the human cerebral cortex, although the precise cellular distribution and promoter regulation are not fully characterized. We examined the variants of exon I of cyp19 by PCR analysis and the cellular distribution of the enzyme using immunohistochemistry in the human temporal cortex. We detected four different variants of exon I, suggesting a complex regulation of cyp19 in the cerebral cortex. In addition, the enzyme was localized mainly in a large subpopulation of pyramidal neurons and in a subpopulation of astrocytes. However, the majority of GABAergic interneurons identified by their expression of the calcium-binding proteins calbindin, calretinin and parvalbumin, did not display aromatase immunoreactivity. The broad range of potential modulators of the cyp19 gene in the cortex and the widespread expression of the protein in specific neuronal and glial subpopulations suggest that local estrogen formation may play an important role in human cortical function.

[Consequence of evidence-based medicine and individual case appraisal of the Robodoc method for the MDK, and the malpractice management of insurance funds and the principles of managing innovations]. / Konsequenzen des Evidenzberichts und der Einzelfallbewertung der Methode Robodoc für die Begutachtungspraxis des MDK, das Behandlungsfehlermanagement der Krankenkassen und den grundsätzlichen Umgang mit Innovationen.

PURPOSE: Robots in Total Hip Replacement were introduced to utilize the precision of an industrial robot for reaming the femur. This method has been discussed controversially from the beginning of its clinical application in Germany. Criticism increased recently especially in respect of alleged malpractice. Aim of this study was to describe the consequences of the results of a systematic review and the evaluation of malpractice accusations for statutory health insurance and medical advisory services. METHOD: Robot-assisted total hip replacement was evaluated by a Health Technology Assessment report, especially concerning proof of clinical benefit and specific complications of this method. 44 cases of alleged malpractice reported to health insurance were assessed as well and compared with the results of the systematic review. RESULTS: The HTA report showed no proof of clinical benefit but pointed to increased rates of complications. In the 44 evaluated cases the entire range of endoprosthesis- but no robot-specific complications could be identified. CONCLUSION: Patients must be informed about risks, complications, benefits and especially alternatives to a robot-assisted operation. The prospective procedure of management of assumed malpractice concerning Robodoc can not be standardised, but each case must be evaluated individually. Consequently, implementation of a structured malpractice management system for health insurance and medical advisory services should be useful. Additionally, health service should implement an "early warning system" for innovative procedures.

[Technique evaluation for orthopedic use of Robodoc]. / Methodenbewertung in der Orthopädie am Beispiel Robodoc.

AIM: The aim of this study was to assess the clinical benefit and rate of complications of robot-assisted primary total hip replacement. METHODS: Electronic bibliographic databases, the reference lists of relevant articles and various health services research-related resources were analysed and selected studies were assessed using defined quality criteria. RESULTS: 57 publications and three HTA-reports were assessed. Only two prospective randomised controlled studies could be identified. There was no proof of clinical benefit but rather an increased incidence of complications. CONCLUSION: Patients must be informed on the risks, complications, benefits and especially alternatives to a robot-assisted operation. The importance of HTA reports to evaluate new or established procedures will even increase in Germany especially in the recent medico-legal context.

[Minimum requirements in total knee replacement. Evidence report and model calculation of the healthcare situation]. / Mindestmengen in der Kniegelenkendoprothetik. Evidenzbericht und Modellrechnung zur Versorgungssituation.

This report assesses the volume-outcome relationship of total knee replacement and the effects of its application on medical care in Germany. Electronic bibliographic databases, the reference lists of relevant articles, and research-related resources of various health services were searched and selected studies were assessed. Additionally, the consequences of implementing a regulation based on volume-outcome relationship were calculated using different models. The results in the literature concerning defined outcome parameters are inconsistent, but in all but one publication a general correlation between high volume and low complication rate could be identified. Implementing a regulation based on volume-outcome relationship with cutoff points of 20/50/100 total knee replacements/year would lead to an exclusion of 242/502/709 hospitals, respectively, from medical care. This would result in a reallocation of 2358 (2.9%)/10752 (13.2%)/25482 (31.2%) patients/year, respectively (extrapolation). The application of a regulation based on volume-outcome considerations in the German healthcare system must be performed very carefully because significant effects are to be expected.

[Accusations of malpractice in chirotherapeutic treatment]. / Vorgeworfene Behandlungsfehler im Zusammenhang mit chirotherapeutischen Behandlungen.

BACKGROUND: Little is known about the incidence of adverse effects after chiropractic manipulation. Over representation of severe and under representation of less severe complications has to be assumed. MATERIAL AND METHODS: A total of 57 expert opinions from the malpractice advisory board of the North Rhine General Medical Council (Nordrheinische Arztekammer), as well as judgments from German courts since 1949, were analyzed. RESULTS AND CONCLUSIONS: A total of 16 of 57 cases of chiropractic manipulation (since 1975) were attested as malpractice by expert opinion, seven of which had significant negative consequences. In nine cases, the judgments of German courts refer to manual therapy. Of these, five deal with informed consent. Observance of the "Bingen Declaration" would have avoided all cases of malpractice found by the advisory board over 29 years.

[Evidence-based medicine in orthopedics - a sensible or unnecessary addition to clinical routine? Part 1: the diagnostics tool]. / Evidence-Based Medicine in der Orthopädie - Sinnvolle Ergänzung oder überflüssiger Ballast in der klinischen Arbeit? Teil 1: Das Modul "Diagnostik"

AIM: The methods of evidence based medicine (EBM) are recommended to solve problems in day-to-day routine. Aim of this article is to demonstrate the practicability of this procedure for the diagnostic module. METHODS: Within a teaching session in our department 20 participants guided by an extern al EBM teacher validated the results of an article according to the EBM criteria concerning the module "diagnosis". We demonstrate what EBM can contribute to solve day-to-day clinical problems and discuss the six formal steps for the implementation of EBM into day-to-day practice. 1) To transform the clinical problem into an answerable 4-part question. 2) To answer this question based on your internal evidence. 3) To search for external evidence to answer this question. 4) To critically appraise the evidence found with respect to its validity, importance and applicability. 5) To integrate the appraised external evidence into your existing internal evidence in order to come to a new decision if the additional new external evidence is convincing. 6) To assess the benefit which was gained for the patient. RESULTS: Statistical tests to evaluate the relevance and validity of the chosen article were performed. The following data were determined: sensitivity, specifity, pretest probability, posttest probability, likelihood ratio, positive predictive value, negative predictive value. CONCLUSION: In conclusion we show that EBM can help to solve day-to-day clinical problems, because the structured analysis of concrete questions can lead to a validation of the literature.

[Evidence-based medicine in orthopaedics - a sensible or unnecessary addition to clinical routine? Part 2: the therapy tool]. / Evidence-Based Medicine in der Orthopädie - Sinnvolle Ergänzung oder überflüssiger Ballast in der klinischen Arbeit ? Teil 2: Das Modul "Therapie"

AIM: In the second part of our project to implement evidence-based medicine into day-to-day clinical practice the module therapy is presented. METHODS: Within a teaching session in our department 20 participants guided by an extern al EBM teacher validated the results of an article according to the EBM criteria concerning the module therapy. To work with this module formal procedures are necessary, too. RESULTS: Statistical tests to evaluate the relevance and validity of the chosen article were performed. The following data were determined: relative risk reduction, absolute risk reduction, number needed to treat. CONCLUSION: In conclusion we can show, that EBM can help to solve day-to-day clinical problems, because the structured analysis concerning valid answers to concrete clinical problems is possible.

International variation in hip replacement rates.

OBJECTIVES: To summarise epidemiological data on the frequency of hip replacements in the countries of the developed world, especially in countries of the Organisation for Economic Cooperation and Development (OECD), and to investigate whether missing consensus criteria for the indication for total hip replacement (THR) result in different replacement rates. METHODS: Country-specific hip replacement rates were collected using the available literature, different data sources of national authorities, and estimates of leading hip replacement manufacturers. RESULTS: According to administrative and literature data sources the reported crude primary THR rate varied between 50 and 130 procedures/100000 inhabitants in OECD countries in the 1990s. The crude overall hip implantation rate, summarising THR, partial hip replacement, and hip revision procedures, was reported to range from 60 to 200 procedures/100000 inhabitants in the late 1990s. Moreover, large national differences were seen in the relationship between total and partial hip replacement procedures. CONCLUSION: The reported differences in hip replacement rates in OECD countries are substantial. They may be due to various causes, including different coding systems, country-specific differences in the healthcare system, in total expenditure on health per capita, in the population age structure, and in different indication criteria for THR.

[Preliminary results in the therapy of psoriatic arthritis with mycophenolate mofetil]. / Erste Ergebnisse der Therapie der Psoriasisarthritis mit Mycophenolatmofetil.

BACKGROUND: Psoriatic arthritis concerns both the skin and the joints. Therapeutic interventions should therefore ideally improve both symptoms. Current disease modifying drugs are effective; however, they are usually limited to either psoriasis or arthritis. AIM OF THE STUDY: The aim of this study was to analyze the therapeutic effects of a new immunosuppressive drug (Mycophenolate mofetil) in the treatment of psoriatic arthritis. METHODS: Six patients with psoriatic arthritis were treated with Mycophenolate mofetil for a period of 12 weeks and examined every 14 days (range of motion, joint swelling, joint deformity, PASI score (Psoriasis Area and Severity Index). In addition, a life quality assessment (SF-36 Health Survey) was performed. White and red blood count as well as inflammation parameter were controlled regularly. RESULTS: 6 patients could be included in a complete follow-up (5 men, 1 woman, average age 50.3 years, average duration of psoriasis 8.3 years, average duration of arthritis 5.7 years). Four of 6 patients showed relevant improvement in pain, mobility and degree of psoriatic skin effluorescences. Only 3 of 6 showed relevant improvement in life quality. CONCLUSION: For the first time results of treatment of psoriatic arthritis with a new immunosuppressive drug (Mycophenolate mofetil) were presented. A positive influence on both, the arthritis and the psoriasis could be shown. These first observations warrant controlled, randomized clinical trials.

Comparison of Gas Temperatures Measured by Coherent Anti-Stokes Raman Spectroscopy (CARS) of O(2) and N(2).

We investigate the accuracy of temperature measurements by coherent anti-Stokes Raman spectroscopy (CARS) of O(2) and use measurements taken with N(2) CARS and a thermocouple for comparison. Scanning vibrational CARS spectra of O(2) and N(2) were recorded over a broad range of temperatures: between 294 K and 1900 K in air that was heated in a tube furnace and at approximately 2450 K in a fuel-lean CH(4)-O(2)-N(2) flame. Temperatures were derived from least-squares fits of simulated and experimental spectra. Both the fundamental vibrational band and the first hot vibrational band were included in fitting. In the case of the tube furnace, the N(2) and the O(2) CARS temperature measurements agreed to within 3%, and results were similar with the thermocouple; in the flame the agreement was to within 1%. We conclude that, for cases in which O(2) is present in sufficient concentrations ( approximately 10% or greater), the accuracy of O(2) thermometry is comparable with that of N(2).

Histology of the ligamentum flavum in patients with degenerative lumbar spinal stenosis.

The degree of calcification as well as the structural changes of the elastic fibres in the ligamentum flavum in patients with degenerative lumbar spinal stenosis were evaluated and the results were compared to those of patients without spinal stenosis. In 21 patients (13 male, 8 female) with lumbar spinal stenosis the ligamentum flavum was removed, histologically processed and stained. The calcification, the elastic/collagenous fibre ratio as well as the configuration of the fibres were evaluated with an image analyzing computer. As a control group, 20 ligaments of 10 human corpses were processed in the same way. The results were statistically analysed using the Mann-Whitney-Wilcoxon test (alpha = 0.05) and the t-test (alpha = 0.05). Nearly all the ligaments of patients with lumbar spinal stenosis were calcified (average 0.17%, maximum 3.8%) and showed relevant fibrosis with decreased elastic/collagenous fibre ratio. There was a significant correlation between age and histological changes (P<0.05). In the control group we only found minimal calcification in 3 of 20 segments (average 0.015%). No relevant fibrosis was found and the configuration of elastic fibres showed no pathologic changes. The results of this study illustrate the important role of histological changes of the ligamentum flavum for the aetiology of lumbar spinal stenosis.