Time extrapolation in regulatory risk assessment: The impact of study differences on the extrapolation factors.

In human risk assessment, time extrapolation factors (EFs) account for differences in exposure duration of experimental studies. We calculated EFs based on N(L)OEL (no (lowest) observed effect level) ratios, dividing shorter-term by longer-term values. The 'oral' datasets comprised 302 EFs (subacute-subchronic) and 1059 EFs (subchronic-chronic). The 'inhalation' datasets contained 67 EFs (subacute-subchronic) and 226 EFs (subchronic-chronic). The experimental EF distribution oral:subchronic-chronic showed that study parameters like deviation in dose selection and spacing influence mainly the data variance. Exclusion of these influences led to a dataset representing more realistically the difference of N(L)OELs with prolonged treatment. This dataset showed a GM of 1.5, indicating that the impact of a longer treatment period on the study N(L)OEL is on average not high. A factor of 1.5 seemed to be also sufficiently conservative for subacute-subchronic and subchronic-chronic extrapolation (inhalation or oral exposure). EFs for groups of similar compounds did not differ, but for compounds with low and high NOEL values. Relatively toxic compounds (GM 1) might thus not require time extrapolation. Within and between chemical variance was analysed in the dataset oral:subchronic-chronic (GSD 4.8). The variance between chemicals should be considered within extrapolation by selecting an appropriate percentile for which a chemical variance factor is suggested. In risk assessment, often a combination of EFs is required. Our analysis indicates that such a combination will result in an accumulation of non-toxicological variance and therefore unrealistically high EFs. Further evaluations are needed to identify appropriate chemical variance factors for these situations.

[Status quo and potential of health services research: the perspective of Bavarian actors]. / Stand und Potenziale der Versorgungsforschung: Die Perspektive der Akteure in Bayern.

In 2011, the Bavarian Parliament decided to advance health services research (HSR) in Bavaria by bundling scientific competencies in a State Working Group and integrating other actors in it. The establishment of such a State Working Group "Health Services Research" -(LAGeV) together with members from science, health care and politics followed in 2012. The objective of this study is to identify the status quo of HSR in Bavaria including its determinants and potential for development based on the actors' perspective.After the inaugural meeting a semi-structured questionnaire was sent to all 36 members from 28 organisations. Items comprise information on the respondent's background as well as status quo, future topics and potential for development of HSR in Bavaria.27 members took part in the survey, resulting in a response rate of 75.0%. Satisfaction of actors with the status quo of HSR is rather low, especially regarding the effectiveness of policy advice. Researchers and health care providers are also not much satisfied with the HSR environment. For the future of HSR, respondents prioritise the topics interface and networking research, followed by innovative care concepts, care for patients with multiple or chronic conditions as well as evaluation of innovations, processes and technologies. Potential for development and thus improvement of care is primarily seen in the abolishment of existing constraints by an overall HSR concept (including selective research promotion), networking and cooperation, research funding as well as improving the interface between politics and science. Respondents assess the benefit of an increased networking within the LAGeV as high.Status quo of HSR in Bavaria is not very satisfactory. The survey reveals important constraints as well as promoting factors based on the viewpoints of different groups of actors. It also prioritises future HSR topics and identifies potential for development, which are important for the LAGeV. The findings can be used for advancing HSR in Bavaria and beyond.

[Memorandum 'Development of health services research in Bavaria from the perspective of the Bavarian State Working Group 'Health Services Research (LAGeV)': status quo - potential - strategies']. / Memorandum "Weiterentwicklung der Gesundheitsversorgungsforschung in Bayern aus Sicht der Landesarbeitsgemeinschaft Gesundheitsversorgungsforschung: Status quo - Entwicklungspotenziale - Strategien".

The aim of the memorandum on the development of health services research (HSR) in Bavaria is to operationalise the global objectives of the State Working Group "Health Services Research" (LAGeV) and to collectively define future topics, specific implementation steps, methods as well as ways of working for the future course of the LAGeV. The LAGeV is an expert committee that integrates and links the competencies of different actors from science, politics and health care regarding HSR and facilitates their cooperation. The memorandum is based on an explorative survey among the LAGeV members, which identified the status quo of health services research in Bavaria, potential for development, important constraints, promoting factors, specific recommendations as well as future topics for the further development of HSR in Bavaria. From the perspective of the LAGeV members, the 12 most important future topics are: 1) Interface and networking research, 2) Innovative health care concepts, 3) Health care for multimorbid patients, 4)Health care for chronically ill patients, 5) Evaluation of innovations, processes and technologies, 6) Patient orientation and user focus, 7) Social and regional inequalities in health care, 8) Health care for mentally ill patients, 9) Indicators of health care quality, 10) Regional needs planning, 11) Practical effectiveness of HSR and 12) Scientific use of routine data. Potential for development of HSR in Bavaria lies a) in the promotion of networking and sustainable structures, b) the establishment of an HSR information platform that bundles information and results in regard to current topics and aims to facilitate cooperation as well as c) in the initiation of measures and projects. The latter ought to pinpoint health care challenges and make recommendations regarding the improvement of health care and its quality. The cooperation and networking structures that were established with the LAGeV should be continuously expanded and be used to work on priority topics in order to achieve the global objectives of the LAGeV.

Efficacy of two different CHX-containing desensitizers: a controlled double-blind study.

The aim of this study was to compare the effectiveness and duration of action of the tooth desensitization agent Cervitec (C) vs that of the new Cervitec Plus (C+). In this monocentric, single-center, three-armed, controlled, double-blind study, 120 subjects were randomly assigned to one of three groups:group I received Cervitec Plus (C+), group II received Cervitec (C), and group III received placebo (P). Varnishes were applied after base-line determination of cervical dentin hyper-sensitivity using a pain score of one or higher.Re-evaluation was performed 1, 7, 30, and 90 days after application. Statistical evaluation was carried out using nonparametric statistics for relative effects and analysis of variance(ANOVA). Thirty days after application of Cand C+, all hypersensitivity decreased significantly in relation to baseline measurements(p<0.001), with no changes taking place in the placebo group. Significant differences were observed between C and C+ vs placebo(p<0.001), whereas no significant difference between C and C+ was seen after 30 days(p=0.840). After 90 days, the reduction in hypersensitivity with C+ was still significant compared with baseline measurements(p=0.001). However, C was not significantly different compared with baseline measurements (p=0.05). Analysis of all hypersensitive posterior teeth examined showed no significant difference between C and C+ after 90 days(p=0.362). For anterior teeth, the difference between C and C+ was significant (p=0.012).Both C and C+ reduce cervical tooth hypersensitivity, whereas C+ reduces hypersensitivity for a longer period of time.

Abdominal incision defect following AAA-surgery (AIDA): 2-year results of prophylactic onlay-mesh augmentation in a multicentre, double-blind, randomised controlled trial.

The reported incidence of incisional hernia following repair of abdominal aortic aneurysm (AAA) via midline laparotomy is up to 69%. This prospective, multicenter, double-blind, randomised controlled trial was conducted at eleven hospitals in Germany. Patients aged 18 years or older undergoing elective AAA-repair via midline incision were randomly assigned using a computer-generated randomisation sequence to one of three groups for fascial closure: with long-term absorbable suture (MonoPlus®, group I), long-term absorbable suture and onlay mesh reinforcement (group II) or extra long-term absorbable suture (MonoMax®, group III). The primary endpoint was the incidence of incisional hernia within 24 months of follow-up, analysed by intention to treat. Physicians conducting the postoperative visits and the patients were blinded. Between February 2011 and July 2013, 104 patients (69.8 ± 7.7 years) were randomised, 99 of them received a study intervention. The rate of incisional hernia within 24 months was not significantly reduced with onlay mesh augmentation compared to primary suture (p = 0.290). Furthermore, the rate of incisional hernia did not differ significantly between fascial closure with slow and extra long-term absorbable suture (p = 0.111). Serious adverse events related to study intervention occurred in five patients (5.1%) from treatment groups II and III. Wound healing disorders were more frequently seen after onlay mesh implantation on the day of discharge (p = 0.010) and three (p = 0.009) and six (p = 0.023) months postoperatively. The existing evidence on prophylactic mesh augmentation in patients undergoing AAA-repair via midline laparotomy probably needs critical review. As the implementation of new RCTs is considered difficult due to the increasing number of endovascular AAA treated, registry studies could help to collect and evaluate data in cases of open AAA-repair. Comparisons between prophylactic mesh implantation and the small bite technique are also required. Trial registration: ClinicalTrials.gov Identifier: NCT01353443. Funding Sources: Aesculap AG, Tuttlingen, Germany.

Smartphone and wearable detected atrial arrhythmias in Older Adults: Results of a fully digital European Case finding study.

Aims: Simplified detection of atrial arrhythmias via consumer-electronics would enable earlier therapy in at-risk populations. Whether this is feasible and effective in older populations is not known. Methods and results: The fully remote, investigator-initiated Smartphone and wearable detected atrial arrhythmia in Older Adults Case finding study (Smart in OAC-AFNET 9) digitally enrolled participants ≥65 years without known atrial fibrillation, not receiving oral anticoagulation in Germany, Poland, and Spain for 8 weeks. Participants were invited by media communications and direct contacts. Study procedures adhered to European data protection. Consenting participants received a wristband with a photoplethysmography sensor to be coupled to their smartphone. The primary outcome was the detection of atrial arrhythmias lasting 6 min or longer in the first 4 weeks of monitoring. Eight hundred and eighty-two older persons (age 71 ± 5 years, range 65-90, 500 (57%) women, 414 (47%) hypertension, and 97 (11%) diabetes) recorded signals. Most participants (72%) responded to adverts or word of mouth, leaflets (11%) or general practitioners (9%). Participation was completely remote in 469/882 persons (53%). During the first 4 weeks, participants transmitted PPG signals for 533/696 h (77% of the maximum possible time). Atrial arrhythmias were detected in 44 participants (5%) within 28 days, and in 53 (6%) within 8 weeks. Detection was highest in the first monitoring week [incidence rates: 1st week: 3.4% (95% confidence interval 2.4-4.9); 2nd-4th week: 0.55% (0.33-0.93)]. Conclusion: Remote, digitally supported consumer-electronics-based screening is feasible in older European adults and identifies atrial arrhythmias in 5% of participants within 4 weeks of monitoring (NCT04579159).

Oral health in adult patients with congenital coagulation disorders--a case control study.

Inflammatory disorders of the periodontium, gingivitis and periodontitis are among the most prevalent diseases worldwide. A few studies have found poorer oral health in patients with congenital coagulation disorders (CCD) like haemophilia and von Willebrand's disease compared with non-affected controls. The aim of this study was to investigate the effect of congenital coagulation disorders on oral health and periodontal (alveolar) bone loss. This is a case control study comparing oral health and periodontal bone loss of patient with congenital coagulation disorders with matched healthy subjects. The examination included dental status (DMF-T), assessment of oral hygiene (modified Quigley-Hein-Index: QHI) and a dental panoramic X-ray for assessment of alveolar bone loss caused by periodontal disease. A total of 15 patients with CCD (Haemophilia A: n = 8, von Willebrand's disease: n =7) were matched with 31 non-affected controls. We observed no clinical relevant difference of oral health (DMF-T, QHI) between patients with CCD and controls despite better oral hygiene (QHI) of patients with CCD. Moreover, there was a statistically significant difference in periodontal bone loss, but the observed difference is not clinically meaningful. Unlike previous studies carried out mainly in children we found no evidence that oral health or periodontal status in adult patients with CCD is worse than that in healthy subjects. However, larger studies and longitudinal studies in adults are needed to confirm our results.

Serial NT-proBNP measurements for risk stratification of patients with decompensated heart failure.

PURPOSE: NT-proBNP is an important prognostic predictor in patients with heart failure. However, it is unknown whether a change of NT-proBNP plasma levels in the early phase of decompensation might be of additional prognostic value in patients with acute decompensation of heart failure. METHODS AND RESULTS: NT-proBNP plasma levels of 116 patients with decompensated heart failure from ischemic/non-ischemic origin were measured at baseline and at 12, 24 and 48 h after hospital admission. Baseline levels and changes of plasma levels within the first 48 h were correlated with 30-day mortality. In all patients, NT-proBNP 12 h after admission was highest and superior with respect to the prediction of 30-day mortality compared to plasma levels on admission. In total, 38 patients died within the first 30 days. In these patients absolute NT-proBNP plasma levels were significantly higher and the increase within 12 h after admission was more pronounced compared to survivors (p<0.001). NT-proBNP at 12 h after admission also had the highest predictive value for the 30-day mortality rate in patients with acute myocardial infarction. The increase of NT-proBNP plasma levels within 12 h after admission had the highest predictive value in patients suffering from decompensated heart failure. CONCLUSIONS: NT-proBNP is a powerful marker of 30-day mortality in patients with decompensated heart failure of ischemic and non-ischemic origin. Compared with single baseline measurements, serial measurements of NT-proBNP plasma levels within 12 h after hospital admission may be used to increase the predictive value of NT-proBNP with regard to the early identification of patients who are at high risk of mortality.

Efficacy of different irrigants in the removal of calcium hydroxide from root canals.

AIM: To compare the efficacy of different solutions (1% sodium hypochlorite, 10% citric acid and 20% EDTA) in the removal of calcium hydroxide from root canals. METHODOLOGY: One hundred single-rooted maxillary incisors were prepared to size 50 and split longitudinally. Two standardized grooves were cut into the apical and coronal part of the root canal dentine and filled with calcium hydroxide. The reassembled teeth were irrigated with a syringe and a size 30 needle using the following irrigants: (i) 20% EDTA, (ii) 10% citric acid, (iii) 1% NaOCl, (iv) 10% citric acid + 1% NaOCl, (v) 20% EDTA + 1% NaOCl and (vi) water (control). Volume of irrigant was 20 mL in each group, and irrigation time was 5 min. Evaluation of cleanliness of the blinded specimens was performed by two calibrated observers under a microscope with 30x magnification using a four-grade scoring system as described by van der Sluis et al. (2007). Statistical evaluation was performed using a SAS-macro for non-parametric multifactorial analysis (P < 0.05). RESULTS: The best results were found for irrigation with EDTA and citric acid, whereas NaOCl and water showed the least effect. The combinations of irrigants did not result in improvement in terms of cleanliness. CONCLUSIONS: None of the irrigants nor their respective combinations were able to completely remove the calcium hydroxide. Chelating agents such as citric acid and EDTA showed the best results. The combination of chelators and NaOCl did not result in significant improvement of calcium hydroxide removal.

[Tobacco prevention at the regional level, Bavaria as an example]. / Tabakprävention auf Landesebene. Das Beispiel Bayern.

Tobacco consumption is one of the most relevant behavior-based health risks. It has been estimated that there are 14,000-18,000 tobacco-related deaths each year in Bavaria, Germany. Thus, efficient tobacco prevention, which involves measures of behavior-oriented as well as of condition-oriented prevention at the Federal State level, is a priority objective of prevention politics in Bavaria. Measures of behavior-oriented prevention account for the fact that tobacco prevention affects private lifestyles, where statutory provisions may not be effectual. However, smoking bans have achieved the creation of smoke-free living spaces especially for children and adolescents. In the long term, it is essential to enhance evaluation of tobacco prevention, to pay more attention to sustainability of approved projects, and to ensure a smoke-free environment for children and adolescents. The Bavarian health program "Gesund.Leben.Bayern." is an important platform for this.

[Protection from BSE : Efforts, measures, success, and costs]. / Schutz vor BSE : Anstrengungen, Massnahmen, Erfolge und Kosten.

By the mid 1980s, bovine spongiform encephalopathy (BSE) emerged in the United Kingdom (UK) and reached its peak in the early 1990s with up to 37,000 cases. In the year 2000, BSE was diagnosed for the first time for a cow born in Germany. Since then, 413 cases of BSE have been detected. About 10 years after the first BSE cases were detected, variant Creutzfeldt-Jakob disease (vCJD), a new variant of Creutzfeldt-Jakob disease (CJD), was described in the UK. Legal measures for protection from BSE are described. The number of cases of vCJD and the development of the BSE situation in Germany and Bavaria until 2009 are presented.

Dopaminergic treatment is associated with decreased body weight in patients with Parkinson's disease and dyskinesias.

BACKGROUND AND PURPOSE: Several studies suggested that patients with advanced Parkinson's disease (PD) showed a too low body weight when compared with age-matched, healthy subjects. We aimed to investigate whether PD patients with dyskinesias display body weight alterations and to observe any correlations between medication and other putative determinants. METHODS: Charts of 166 PD patients with fluctuations and dyskinesias, admitted within 6 months to a German movement disorders clinic, were investigated for body mass index (BMI), age at onset, disease duration, Unified Parkinson's Disease Rating Scale motor score, eating coordination and medication. RESULTS: Analysis showed that 4.2% of PD patients were underweight (BMI < 18.5 kg/m(2)), 46.4% were normal (BMI > 18.5-25 kg/m(2)), 33.7% were overweight (BMI > 25-30 kg/m(2)), 15.7% were obese (BMI > 30 kg/m(2)). Daily levodopa dosage per kg and total dopaminergic dosage per kg body weight were negatively correlated with BMI. Overall, patients' BMI had not significantly changed within 2 years of follow-up. CONCLUSIONS: In sum, advanced PD patients showed a reduced BMI when compared with a control population obtained from an age-matched group taken from a survey of the German Federal Office for Statistics. Our findings indicate that patients with a lower BMI received a higher cumulative levodopa dosage and that levodopa may be responsible for weight loss in PD.

[Air quality in schools - classroom levels of carbon dioxide (CO2), volatile organic compounds (VOC), aldehydes, endotoxins and cat allergen]. / Raumluftqualität in Schulen - Belastung von Klassenräumen mit Kohlendioxid (CO2), flüchtigen organischen Verbindungen (VOC), Aldehyden, Endotoxinen und Katzenallergenen.

Children are assumed to be more vulnerable to health hazards and spend a large part of their time in schools. To assess the exposure situation in this microenvironment, we evaluated the indoor air quality in winter 2004/5 in 92 classrooms, and in 75 classrooms in summer 2005 in south Bavaria, Germany. Indoor air climate parameters (temperature, relative humidity), carbon dioxide (CO2) and various volatile organic compounds, aldehydes and ketones were measured. Additionally, cat allergen (Fel d1) and endotoxin (LAL-test) were analysed in the settled dust of school rooms. Data on room and building characteristics were collected by use of a standardised form. Only data collected during teaching hours were considered in analysis. The median indoor CO2 concentration in the classrooms ranged in the winter and summer period from 598 to 4 172 ppm and 480 to 1 875 ppm, respectively. While during the winter period in 92% of the classrooms the CO2 daily medians went above 1 000 ppm, the percentage of classrooms with increased CO2 concentration fell to 28% in summer. In winter, in 60% of classes the daily median CO2 concentration exceeded 1 500 ppm, while in summer this threshold was reached by only 9%. A high concentration of CO2 was associated with a high number of pupils, a low room surface area and a low room volume. The levels of total volatile organic compounds (TVOC) in classrooms ranged between 110 and 1 000 microg/m3 (median in winter 345 microg/m3, in summer 260 microg/m3). Acetone, formaldehyde and acetaldehyde were measured in concentrations from 14.0 to 911 microg/m3, from 3.1 to 46.1 microg/m3, and from 2.9 to 78 microg/m3, respectively. The other aldehydes were detected in minor amounts only. The median Fel d1 level in winter was 485 ng/g dust (20 to 45 160 ng/g) and in summer it was 417 ng/g (40-7 470 ng/g). We observed no marked differences between the two sampling periods and between smooth floors and rooms with carpeted floors. No differences were found according to room surface area and room volume. The median endotoxin contents in winter and summer were 19.7 EU/mg dust (6.6 to 154 EU/mg) and 32.2 EU/mg (9.6 to 219 EU/mg), respectively. The levels varied significantly between the sampling periods, but were independent of room surface area, room volume and surface floorings. Overall the results of VOC, aldehydes, ketones and endotoxin indicate, in general, a low exposure level in classrooms. The observed concentrations of cat allergens should be considered as a meaningful exposure route and thus could be tackled within preventive programs.

The volume of postoperative drainage fluid as a potential early predictor of lymphedema after lymph node excision for metastatic melanoma.

Lymphedema (LE) following lymph node dissection is a major problem for cancer patients, and radiation therapy, extended surgery, groin dissection, obesity, and older age are well-established risk factors of LE. We studied whether these risk factors are further associated with high volumes of postoperative drainage fluid after complete lymph node dissection (CLND) for melanoma metastases. Moreover, we examined whether a high amount of drainage fluid after sentinel lymph node biopsy (SLNB) can predict a high amount of drainage fluid after subsequent CLND. Using descriptive statistics and regression analyses, we analyzed the cumulative volumes of postoperative drainage fluid for 836 melanoma patients with lymph node excision in the axilla or groin. In multiple regression analyses, the well-established risk factors of LE, i.e., increased body mass index, older age, and ilioinguinal versus inguinal versus axillary dissection predicted a high drainage volume after CLND. Of note, a high drainage fluid volume after SLNB also predicted a high drainage volume after subsequent CLND. In patients with groin dissections, who are particularly susceptible to swelling, extended iliac dissection, age above 60, and a cumulative drainage volume of more than 100 ml in the preceding SLNB were predictors of the cumulative drainage volume. We find that common risk factors predict the volume of postoperative drainage fluid after CLND and postoperative LE. Further, high postoperative drainage volume may therefore function as a potential early predictor of LE following CLND.

[Differences in small area prevalence of respiratory diseases in children: challenges of an investigation initiated by parents]. / Kleinräumige Prävalenzunterschiede von Atemwegserkrankungen bei Kindern: Grenzen der Erkenntnismöglichkeiten einer von Eltern angeregten Studie.

OBJECTIVE: The aim of our study was to assess the prevalence of respiratory diseases in children living in a rural area in Bavaria in a systematic and standardised way to clarify whether a disease cluster exists. Reports from a parents' initiative claiming an increase of diseased children and assuming an association with air pollution due to nearby industrial sources and heavy traffic were the reason for the study. METHODS: Parents of all children living in small towns specified by the parents' initiative as affected region (central area) and parents of those children aged 6-7 or 13-14 years living in adjacent areas (control area) were asked to complete a written questionnaire. In bivariate analysis, differences in prevalences between the central area and the control area were assessed by the chi (2) test. In multivariate analysis, confounder-adjusted odds ratios with 95 % confidence intervals were calculated by logistic regression. In addition, generalized linear mixed models were used to control for potential clusters in families. RESULTS: The response rate was rather low (total 46 %, central area 53 %, control area 34 %). The study population comprised 121 girls and 141 boys. There was a pattern of increased prevalences of cough, wheeze and respiratory diseases caused by infections in children living in the central area compared to the control area. However, statistical significance was rarely observed. No systematic differences were observed for the prevalence of allergic rhinitis and atopic dermatitis. Selection bias due to varying response rates in the central versus the control area and information bias introduced by the preceding intensive public discussion could not be excluded. The comparison of prevalences detected in the small area with published data from other epidemiological studies in Germany did not indicate a systematically increased prevalence of respiratory symptoms or physician-diagnosed respiratory diseases in children from the whole area as well as in children from the central area only. CONCLUSION: This study exemplifies the challenges of small area investigations initiated by the residential community to clarify an assumed disease cluster caused by environmental pollution. The prior comparison of small area prevalence data with results of other epidemiological studies aids the decision making as to whether a detailed study with comprehensive assessment of individual exposure is justifiable.

Establishing an optimal trajectory for calcaneotibial K-wire fixation in emergent treatment of unstable ankle fractures.

OBJECTIVE: In unstable ankle fractures the associated soft tissue damage can be a therapeutic challenge. The aim of this study was to optimize planning of minimally invasive stabilization of ankle fractures by calcaneotibial transfixation, which is a demanding technique due to the complex hind foot anatomy. METHODS: In a retrospective radiographic analysis the angles and dimensions of a safe drill tunnel for calcaneotibial K-wire insertion were defined on standard radiographs of the ankle joint. 165 lateral weight-bearing radiographs (77 right; 88 left) and 147 (80 right; 67 left) mortise views of 186 (90 right; 96 left) uninjured feet from 123 patients (74 women (114 feet); 49 men (72 feet)) were included in this study. The average patient age was 49 (range, 13-85) years. Inter- and intra-observer reliability was evaluated on 20 randomized radiographs that were analyzed in a default set, three times, by two different examiners on three different days. RESULTS: In the lateral view the drilling tunnel was orientated at 59.4° to the plantar plane with a maximum proximal variance of 7.1 image-mm. Distal variance cannot be tolerated since an ankle joint injury would ensue. In the mortise view the drill tunnel was directed with a mean angle of 18.4° to the distal tibial articular surface. At most a mean of 11° fibular- and 13.4° tibial- expansion can be tolerated. Intra- and inter-observer reliability was higher for the angles than for the drill corridors. CONCLUSION: The three-dimensional (3D) orientation for safe K-wire placement for calcaneotibial transfixation should adhere to the drill tunnels established in this study.

Comparison of the intracellular itineraries of insulin-like growth factor-I and insulin and their receptors in Rat-1 fibroblasts.

In this study we have compared the intracellular itineraries of insulin and insulin-like growth factor-I (IGF-I) and their receptors subsequent to ligand internalization in rat fibroblasts. We found that the endocytic rate constant is approximately 3 times as high for insulin as for IGF-I. The dissociation of internalized ligand from its receptor was monitored by the ability of ligand-receptor complexes to precipitate in the presence of polyethylene glycol (PEG). Insulin loses its ability to precipitate with PEG more rapidly than IGF-I. After 60 min, less than 10% of the intracellular insulin remains PEG precipitable, whereas 44% of intracellular IGF-I stays PEG precipitable. Ligand degradation was determined by precipitation with trichloroacetic acid (TCA). Insulin degradation after internalization is more rapid compared with IGF-I degradation; after 2 h, 80% of intracellular IGF-I, in contrast to only 30% of intracellular insulin, remains intact. We measured retroendocytosis of insulin and IGF-I by assessing the amount of internalized ligand that was subsequently released from the cells. When analyzing released ligand by TCA precipitation, we found that 25% of insulin and 53% of IGF-I were TCA precipitable. After 120 min, only 16% of insulin and 43% of IGF-I remained intracellular. To provide insight into a possible mechanism that prevents IGF-I from being subjected to the same degree of degradation as insulin, we studied the effect of pH on IGF-I and insulin binding. We found IGF-I binding to be less sensitive to decreases in pH compared with insulin binding. Therefore, it is likely that after internalization, IGF-I does not dissociate from its intracellular receptor as easily as insulin in the acidifying endosome and, therefore, can return to the cell surface via a recycling receptor. In summary, we have observed distinct differences in the intracellular itineraries of IGF-I and insulin and their receptors. IGF-I internalization and degradation proceed less efficiently than insulin internalization, and IGF-I is preferentially targeted into a retroendocytotic pathway in contrast to insulin, which primarily undergoes lysosomal degradation. The differential effect of pH on ligand binding to these structurally related hormone receptors may account for the quantitatively distinct ligand trafficking events.

NPXY motif in the insulin-like growth factor-I receptor is required for efficient ligand-mediated receptor internalization and biological signaling.

The NPXY motif that was identified in the low density lipoprotein receptor serves as an internalization signal, and subsequent studies have indicated that the NPXY sequence is also an important recognition element for internalization of both insulin and transferrin receptors. The insulin-like growth factor (IGF-I) receptor contains an NPXY sequence (residues 947-950) in the immediate submembranous domain, and we sought to determine whether these residues play a role in facilitating ligand-mediated internalization of the IGF-I receptor. To study this, we have constructed stable cell lines expressing NPXY deletion mutant receptors (CHONPXY) or wild-type receptors (CHOWT). Ligand internalization studies showed that CHONPXY cells internalized [125I]IGF-I with a 40% defect (P < 0.005) compared to the CHOWT cells. Ligand-mediated receptor internalization and down-regulation were decreased by 90% in CHONPXY compared to CHOWT cells. The kinase activity of the mutant receptors was also defective as a result of removal of the NPXY motif. This is in contrast to the insulin receptor, in which deletion of the NPXY motif or deletions of even larger portions of amino acids in proximity to the NPXY motif do not affect the kinase activity of the receptor. Finally, the ability of the mutant receptors to mediate biological signaling is also defective, as measured by the thymidine incorporation assay.

Palladium/phosphite catalyst systems for efficient cross coupling of aryl bromides and chlorides with phenylboronic acid

The Suzuki reaction of aryl bromides is efficiently catalyzed by palladium/ phosphite complexes generated in situ. The influence of ligand, base, and different additives is examined. The process tolerates various functional groups and catalyst turnover numbers up to 820,000 are obtained even with deactivated aryl bromides. For the first time it is shown that palladium/phosphite complexes also catalyze efficiently the Suzuki reaction of aryl chlorides.

Induction of DNA single-strand breaks by 131I and 99mTc in human mononuclear blood cells in vitro and extrapolation to the in vivo situation.

The radionuclides (131)I and (99m)Tc are frequently used for therapy of benign and malignant thyroid disease ((131)I) and for diagnosis of thyroid and other diseases ((99m)Tc). However, the levels of DNA single-strand breaks (SSBs) induced in cells of patients after administration of (131)I and (99m)Tc are not known. In this study, we measured the number of SSBs per cell induced by (131)I and (99m)Tc in vitro, extrapolated the results to the clinical situation, and assessed their biological relevance by comparing levels of SSBs induced after therapeutic administration of (131)I and (99m)Tc to those induced by endogenous processes or by occupational exposure to genotoxic substances. A linear dose-response relationship between the radioactivity concentrations of (131)I and (99m)Tc and SSBs in human mononuclear blood cells (determined by alkaline elution) was obtained after incubation at 4 and 37 degrees C. At 4 degrees C, where almost no repair of SSBs takes place, (131)I and (99m)Tc induced 81 and 7 SSBs per cell per hour/(MBq/ml), respectively. At 37 degrees C, only 20 and 1.6 SSBs per cell per hour/(MBq/ml) were observed after incubation with (131)I and (99m)Tc. To estimate the induction of SSBs in vivo in cells of patients after administration of 3700 MBq (131)I (oral) or 60 MBq (99m)Tc (i.v.), the rates of induction of SSBs obtained in vitro were extrapolated to the concentrations of (131)I and (99m)Tc measured in blood of patients. The total number of SSBs (mean +/- standard deviation) accumulated after oral administration of 3700 MBq (131)I up to 70 h after administration was calculated as 200 +/- 59 SSBs/cell. After administration of 60 MBq (99m)Tc (i.v.), 0.032 +/- 0.009 SSBs per cell (total SSBs up to 2 h after administration) were cumulated. The induction of SSBs by endogenous processes (estimated 2,000 SSBs per cell per hour) and by occupational exposure to genotoxic substances (125-430 SSBs per cell) has been estimated in earlier studies. In conclusion, the frequency of SSBs induced by thyroid diagnosis with 60 MBq (99m)Tc is approximately 5 orders of magnitude smaller than the frequency of spontaneous SSBs and thus is most probably without biological relevance. Since the frequency of induction of SSBs by therapy with (131)I (3700 MBq) is about 6000-fold higher compared to thyroid diagnosis by (99m)Tc, its biological relevance is more difficult to assess. Nevertheless, the number of SSBs induced by therapy with (131)I is substantially lower than that induced by endogenous processes.