Treatment of Mantle and Inverted Y Fields in Modern Era: A VMAT Approach

PURPOSE/OBJECTIVE(S)

Hodgkin's lymphoma has been treated with combined modality therapy (chemotherapy and radiation) with a very high degree of success. Total Nodal Irradiation (TNI) performed with large AP/PA mantle fields for treatment of axillary, cervical, and mediastinal lymphatics, provide adequate coverage to the mediastinum and bilateral axillae and hila, while blocking lungs. The para-aortic and pelvic lymph nodes are treated with the so called inverted-Y AP/PA fields, which often includes the spleen in cases of TNI. Multileaf Collimators (MLC) have been tried, but due to the irregular shape of the fields and necessity of island blocking in 3D treatment, they have not been successful in full elimination of Cerrobend blocks. We hypothesize that using two or three matched Volumetric Modulated Arc Therapy (VMAT) fields will not only eliminate a need for Cerrobend blocks or island blocks, but will also provide better target coverage and better organs at risk (OAR) sparing.

MATERIALS/METHODS

Under IRB study, 10 patients were retrospectively planned using two or three matched VMAT technique for mantle and inverted-Y treatments of TNI that had been previously treated using MLC and Cerrobend block combination. Pinnacle treatment planning system version 16.2.1 was used to generate plans using mantle/inverted-Y technique and corresponding VMAT plans using 2-3 arcs per isocenter (2 isocenters per plan). Optimization was performed to cover targets with the prescribed dose of 1500 cGy in 10 fractions per institutional protocol. The VMAT plans were compared with traditional 3D plans.

RESULTS

VMAT consistently provided better or similar results to traditional field arrangements. Target coverage: V15Gy - 95.45% vs 77.99% (p = 0.00017), OAR coverage: total lung V5Gy 63.7% vs 68.8% (p = 0.016), bone marrow mean dose 539.1 cGy vs 727.8 cGy (p = 0.00047), Integral Dose 464.1 mJ vs 573.9 mJ (p = 0.0026). Low isodose lines- mean volume of 5 Gy isodose line was not significantly different - 24036 cc vs 25091 cc (p = 0.271). Cord maximum dose was 40% lower for VMAT plans (p = 0.00006). Mean bladder dose was similar in VMAT plans compared to 3D plan - 821.7 cGy vs 804.9 cGy (p = 0.454). One counter-intuitive result is that the mean integral dose for 10 patients was 24% lower for VMAT plans.

CONCLUSION

VMAT based mantle fields for TNI eliminates Cerrobend blocks and improve dosimetry significantly for target volumes and all OARs; including bone marrow, which plays important role in patient's recovery after chemotherapy, radiation and often stem cell transplantation in recurrent disease. Lower integral dose for VMAT plans is explained by the large irradiated in-fields and small out-of-field volumes. The VMAT process requires minimal effort for optimization and is economical compared to the traditional planning, while improving the target coverage and decreasing dose to OARs.

Polygenic Scores of Alzheimer’s Disease Risk Genes Add Only Modestly to APOE in Explaining Variation in Amyloid PET Burden

Background: Brain accumulation of amyloid-β is a hallmark event in Alzheimer’s disease (AD) whose underlying mechanisms are incompletely understood. Case-control genome-wide association studies have implicated numerous genetic variants in risk of clinically diagnosed AD dementia. Objective: To test for associations between case-control AD risk variants and amyloid PET burden in older adults, and to assess whether a polygenic measure encompassing these factors would account for a large proportion of the unexplained variance in amyloid PET levels in the wider population. Methods: We analyzed data from the Mayo Clinic Study of Aging (MCSA) and the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Global cortical amyloid PET burden was the primary outcome. The 38 gene variants from Wightman et al. (2021) were analyzed as predictors, with PRSice-2 used to assess the collective phenotypic variance explained. Results: Known AD risk variants in APOE, PICALM, CR1, and CLU were associated with amyloid PET levels. In aggregate, the AD risk variants were strongly associated with amyloid PET levels in the MCSA (p = 1.51×10–50) and ADNI (p = 3.21×10–64). However, in both cohorts the non-APOE variants uniquely contributed only modestly (MCSA = 2.1%, ADNI = 4.4%) to explaining variation in amyloid PET levels. Conclusion: Additional case-control AD risk variants added only modestly to APOE in accounting for individual variation in amyloid PET burden, results which were consistent across independent cohorts with distinct recruitment strategies and subject characteristics. Our findings suggest that advancing precision medicine for dementia may require integration of strategies complementing case-control approaches, including biomarker-specific genetic associations, gene-by-environment interactions, and markers of disease progression and heterogeneity.

OP0134 ACTIVE RHEUMATOID ARTHRITIS AND ASSOCIATED COMORBIDITIES INCREASE RISK OF DEMENTIA: A POPULATION-BASED COHORT STUDY

Background

Growing evidence from observational studies indicates that patients with rheumatoid arthritis (RA) have a higher risk of developing dementia. However, the incidence of dementia among RA patients has declined in recent years 1. It is unknown if this reflects broader trends of dementia incidence over time, changes in the prevalence or treatment of associated comorbidities, advances yielding better control of inflammation in RA, or other factors (e.g., environmental risk factors). Longitudinal population-based studies assessing risk factors for dementia among RA patients are scarce 2.

Objectives

We aimed to identify risk factors for incident dementia in a large inception cohort of patients with RA.

Methods

This retrospective population-based cohort study included residents of Olmsted County, MN, who were ≥50 years when they met 1987 ACR criteria for incident RA in 1980-2014. All individuals were followed until death/migration or 12/31/2019. Patients with dementia before RA incidence were excluded (n=12). Incident dementia was defined as two relevant ICD-9/10 codes at least 30 days apart. Risk factors including socio-demographics, RA disease characteristics and medications, cardiovascular/cerebrovascular disease (CVD) risk factors and other comorbidities were abstracted from medical records. Any CVD was defined as coronary heart disease (i.e., angina pectoris, coronary artery disease, myocardial infarction, coronary revascularization procedures, cerebral stroke or heart failure (HF). Association of individual risk factors with incident dementia was examined using Cox proportional hazard models. Three models were utilized: Model 1, adjusting for age, sex, and calendar year of RA incidence; Model 2, adding smoking, obesity, hypertension, diabetes mellitus, and hyperlipidemia to the first; and Model 3, adding ‘any CVD’ to the second. Time-dependent covariates were used to represent factors that developed during follow-up.

Results

The study included 886 patients with RA (mean age 65 years, 65% females). During the follow-up period (median=8.5 years), 103 patients developed dementia. Mean age at the diagnosis of dementia was 82.3 (7.2) years. The cumulative incidence of dementia increased by 2-3% every 5 years after the diagnosis of RA. Older age at RA incidence (Hazard Ratio (HR) 1.14 per 1 year increase, confidence interval (CI): 1.12-1.17) was consistently associated with risk of dementia. Presence of rheumatoid nodules (HR 1.76, CI: 1.05-2.95), large joint swelling (HR 2.11, CI: 1.33-3.34), hypertension (HR 1.84, CI: 1.19-2.85), HF (HR 2.72, CI: 1.29-5.74), and depression (HR 2.23, CI: 1.36-3.67) at baseline or during the first year after RA incidence were significantly associated with risk of dementia. Large joint swelling (HR 2.03, CI: 1.14-3.60), any CVD (HR 2.25, CI: 1.38-3.66), anxiety (HR 1.86, CI: 1.16-2.97), and depression (HR 2.63, CI: 1.76-3.93) at any time during the disease increased the risk of dementia. Among CVD conditions, stroke (HR 3.16, CI: 1.84-5.43) and HF (HR 1.82, CI: 1.10-3.00) significantly increased risk of dementia. After adjusting for CVD risk factors (Model 2), or CVD risk factors plus any CVD (Model 3), all the covariates listed above were still significantly associated with the risk of dementia.

Conclusion

Apart from age, CVD (particularly hypertension), depression and anxiety, which are universally recognized risk factors for dementia, we observed that clinically active RA was associated with an elevated risk of dementia incidence among RA patients. Studies are ongoing to further evaluate the role of systemic inflammation and its interactions with other risk factors in dementia overall and by dementia subtype in patients with RA.

References

[1]Kronzer V L et al. Trends in incidence of dementia among patients with rheumatoid arthritis: A population based cohort study. Semin. Arthritis Rheum.51, 853–857 (2021)

[2]Wallin K et al. Midlife rheumatoid arthritis increases the risk of cognitive impairment two decades later: A population based study J. Alzheimer’s Dis.31, 669–676 (2012)

Acknowledgements

This work was supported by grants from the National Institutes of Health, NIAMS (R01 AR46849) and NIA (R01 AG068192, R01 AG034676).

Disclosure of Interests

Chanakya Kodishala: None declared, Cassondra A Hulshizer: None declared, Vanessa Kronzer: None declared, John M Davis III Grant/research support from: Pfizer, Vijay K Ramanan: None declared, Maria Vassilaki Shareholder of: Abbott Laboratories, Johnson and Johnson, Medtronic, and Amgen, Consultant of: F. Hoffmann-La Roche Ltd, Grant/research support from: F. Hoffmann-La Roche Ltd and Biogen, Michelle Mielke Consultant of: Biogen, Brain Protection Company, and LabCorp, Cynthia S. Crowson: None declared, Elena Myasoedova: None declared

POS0311 NEUROIMAGING BIOMARKERS IN INDIVIDUALS WITH AND WITHOUT RHEUMATOID ARTHRITIS: RESULTS FROM THE MAYO CLINIC STUDY OF AGING

Background:

Age-related increase in the burden of systemic inflammation is an established key player and potential treatment target in Alzheimer’s disease (AD) and other age-related dementias. (Dregan, Chowienczyk et al. 2015) Although rheumatoid arthritis (RA) is an autoimmune hyper-inflammatory disease, studies on RA and dementia or vascular neuroimaging biomarkers are lacking.

Objectives:

To examine the associations between RA and dementia/vascular neuroimaging biomarkers in the Mayo Clinic Study of Aging (MCSA).

Methods:

The study consisted of 35 RA cases in MCSA and 104 MCSA participants without RA matched 1:3 for age, sex, education, cognitive status (≥50 years old) at baseline and the availability of at least one magnetic resonance imaging (MRI). The primary outcome measures were well established dementia-related neuroimaging biomarkers, including global beta-amyloid (Aβ) using PiB-positron-emission tomography (PET; n=47); neurodegeneration (hypometabolism via FDG-PET (n=45), hippocampal volume (n=139), and cortical thickness via structural MRI [n=138], and cerebrovascular pathology via FLAIR-MRI (white matter hyperintensity [WMH; n=49] burden, subcortical, and cortical infarctions (n=55)). Elevated 11C-PiB-PET was defined as standardized uptake value ratio ≥1.48 in an Alzheimer’s disease (AD)-related region of interest and reduced AD signature cortical thickness as ≤2.68mm (neurodegeneration; N+). Kruskal-Wallis rank sum and Pearson’s chi-squared tests were used to compare the neuroimaging measures between participants with and without RA.

Results:

Participants with vs. without-RA did not differ in age, sex, years of education, major comorbidities, Aβ burden, hippocampal volume, and neurodegeneration measures (Table 1). Although the sample size was small, we observed that RA participants (vs. without-RA) had greater mean WMH volume (relative to the total intracranial volume (TIV) (mean (SD) %: 1.12 (0.57) % vs 0.76 (0.69) % of TIV, p=0.011), were more likely to have cortical infarctions (4 vs.1; p=0.013) and had a higher mean number of cortical infarctions (mean (SD): 0.24 (0.44) vs. 0.05 (0.32), p=0.017).

Table 1.

Participants’ baseline characteristics.

With RAWithout RATotalp value*Age, mean (SD)76.3 (7.9)75.9 (7.9)1390.82Male13 (37%)37 (36%)1390.87Education (years), mean (SD)14.5 (2.5)14.3 (2.4)1390.75Apolipoprotein E ε4 carrier6 (17%)28 (27%)1390.24Cognitively unimpaired27 (77%)83 (80%)1100.94Mild cognitive impairment7 (20%)18 (17%)25Dementia1 (3%)3 (3%)4Reduced AD signature cortical thickness20 (57%)60 (58%)1380.91Elevated β-amyloid4 (33%)11 (31%)470.90FDG PET SUVR1.52 (0.16)1.59 (0.18)450.46White matter hyperintensity volume % of TIV1.12 (0.57)0.76 (0.69)490.011With cortical infarctions4 (24%)1 (3%)550.013

N (%) unless otherwise stated; * Kruskal-Wallis rank sum or Pearson’s Chi-squared test.

SD=standard deviation; AD= Alzheimer’s disease; SUVR=standardized uptake value ratio; TIV= Total intracranial volume.

Conclusion:

Our preliminary data suggest significant differences in cerebrovascular biomarker measures by RA status. Further studies would add valuable information to our understanding and insight into the development of interventions for the prevention of cerebrovascular pathology in RA patients.

References:

[1]Dregan, A., P. Chowienczyk and M. C. Gulliford (2015). “Are Inflammation and Related Therapy Associated with All-Cause Dementia in a Primary Care Population?” J Alzheimers Dis 46(4): 1039-1047.

Acknowledgements:

The study was supported by the NIH AG068192. The Mayo Clinic Study of Aging was supported by the NIH (U01 AG006786, P50 AG016574, R01AG057708, R01 AG011378, R01 AG021927, R01 AG041851, R01 NS097495), the Alexander Family Alzheimer’s Disease Research Professorship of the Mayo Clinic, Mayo Foundation for Medical Education and Research, the Liston Award, the Schuler Foundation and was made possible by the Rochester Epidemiology Project (R01 AG034676).

Disclosure of Interests:

Maria Vassilaki Shareholder of: M. Vassilaki has equity ownership in Abbott Laboratories, Johnson and Johnson, Medronic and Amgen., Grant/research support from: M. Vassilaki has received research funding from Roche and Biogen in the past., Cynthia S. Crowson: None declared, John M Davis III Grant/research support from: JM. Davis III receives research funding from Pfizer., Stephanie Duong: None declared, David Jones: None declared, Michelle Mielke Consultant of: M. Mielke has consulted for Biogen and Brain Protection Company, Prashanthi Vemuri: None declared, Elena Myasoedova: None declared

OP0216 TRENDS IN OCCURRENCE OF DEMENTIA IN PATIENTS WITH RHEUMATOID ARTHRITIS: A POPULATION-BASED COHORT STUDY, 1980-2009

Background:

Some cross-sectional studies show increased odds of cognitive impairment and dementia in patients with rheumatoid arthritis (RA) compared to the general population, while others show the reverse. Furthermore, existing studies have not evaluated trends in incidence of dementia on a longitudinal basis.

Objectives:

We aimed to assess the incidence of dementia over time in patients with incident RA and to compare it to those of population-based comparators.

Methods:

This population-based, retrospective cohort study included Olmsted County residents with incident RA and non-RA individuals matched on age, sex, and calendar year. All RA cases met 1987 ACR criteria for RA between 1980 and 2009. Index date was the date of RA criteria fulfillment or a corresponding date for referents. All individuals were followed until death, migration, or 12/31/2019. For sensitivity analyses, follow-up of each decade was truncated at eleven years to make the length of follow-up comparable (e.g., the 1980–89 cohort was truncated at 12/31/1999). Incident dementia was defined as an ICD-9/10 code for dementia. Patients with dementia prior to RA incidence/index date were excluded. Cox proportional hazards models calculated hazard ratios (HR) with 95% confidence intervals (CI) for incident dementia by decade, adjusting for age and sex. The cumulative incidence of dementia was assessed, adjusting for the competing risk of death.

Results:

The study included 895 persons with RA (mean age 55.3 years; 69% female) followed up for a median of 15.2 years. The 10-year cumulative incidence of dementia in these individuals during the 1980s was 12.7% (95%CI 7.9-15.7%), 1990s was 7.2% (95%CI 3.7-9.4%), and 2000s was 6.2% (95%CI 3.6-7.8%) Patients with incident RA in 2000-09 had markedly lower cumulative incidence of dementia than patients diagnosed in the 1980s (HR 0.57; 95%CI 0.33-0.98). Patients with incident RA were then compared to population-based comparators without RA (N=880, mean age 55.2 years; 68% female) followed up for a median of 16.4 years. The 10-year cumulative incidence of dementia in these individuals in the 1980s was 9.3% (95%CI 4.6-11.9%), in the 1990s was 5.0% (95%CI 2.2-6.3%) and in the 2000s was 7.1% (95%CI 4.3-8.9%). Overall, the risk of dementia in RA patients was significantly higher than in the non-RA persons (HR 1.38; 95%CI 1.04-1.83). When subdivided by decade, the risk of dementia in patients diagnosed with RA was higher than non-RA comparators in the 1980s and 1990s but not 2000s (Figure 1). Sensitivity analysis with truncated follow-up yielded similar results.

Figure 1.

Cumulative incidence of dementia (based on ICD 9/10 codes) versus age-and sex-matched non-RA comparators by decade of RA incidence/index.

Conclusion:

Our findings show substantial decline in risk of dementia in patients with RA onset in the 2000s as compared to 1980s, including when compared to the general population comparators. This decline coincides with the advent of novel biologic treatments for RA. Further studies should investigate this association using manual verification rather than billing codes for dementia, and should also elucidate the role of inflammation, autoimmunity, and anti-rheumatic treatments in risk of dementia.

Acknowledgements:

This work was funded by grants from the National Institutes of Health, NIAMS (R01 AR46849) and NIA (R01 AG068192, R01 AG034676).

Disclosure of Interests:

Vanessa Kronzer: None declared, Cynthia S. Crowson: None declared, John M Davis III Grant/research support from: Pfizer, Maria Vassilaki Shareholder of: Abbott Laboratories, Johnson and Johnson, Medronic and Amgen, Grant/research support from: Roche, Biogen, Michelle Mielke Consultant of: Biogen and Brain Protection Company, Elena Myasoedova: None declared

POS0309 SEROPOSITIVITY INCREASES RISK OF INCIDENT DEMENTIA IN INDIVIDUALS WITH RHEUMATOID ARTHRITIS: A POPULATION-BASED COHORT STUDY

Background:

Several studies show increased risk of dementia among individuals with rheumatoid arthritis (RA), while others show no association. One reason for this discrepancy might be differential association by serostatus. No prior studies have investigated the association between RA and dementia by serostatus.

Objectives:

We aimed to evaluate the risk of incident dementia among individuals with RA, stratified by serostatus.

Methods:

This population-based cohort study included all cases of incident RA within Olmsted County, Minnesota with index date of RA onset between 1 January 1999 and 31 December 2013. We matched RA cases to non-RA comparators 1:1 on age and sex. All RA cases met 1987 ACR criteria for RA. We defined seropositivity as positive rheumatoid factor or anti-cyclic citrullinated peptide antibodies. We defined incident dementia as having two ICD-9/10 codes for dementia at least 30 days apart, with the date of the second code representing the time of dementia onset. We excluded individuals with dementia prior to index date. We estimated the cumulative incidence of dementia adjusting for the competing risk of death. For the main analysis, cox proportional hazard models estimated adjusted hazard ratios (aHR) with 95% confidence intervals (CI) for incident dementia, adjusting for age, sex, index year, body mass index, and smoking status (never, former, current). These models compared the incidence of dementia for RA versus non-RA, seropositive and seronegative RA versus their matches, and seropositive versus seronegative RA. To validate these results, we also performed sensitivity analyses using groups matched via inverse probability weighting on age, sex, index year, obesity, smoking status, and race.

Results:

We identified 597 RA cases (mean age 56, 70% female), and 594 non-RA comparators. Of the RA cases, 388 (65%) were seropositive, and 209 (35%) were seronegative. The ten-year cumulative incidence of dementia in patients with RA was 3.3 (95%CI 2.0,5.5) per 100,000 compared to 2.4 (95%CI 1.3,4.2) in non-RA comparators, for aHR of 1.26 (95%CI 0.7,2.3). When stratifying by serostatus, the ten-year incidence of dementia for seropositive RA cases was 3.6 (95%CI 2.0,6.5), corresponding to aHR of 1.45 (95%CI 0.73,2.9) compared to matched non-RA cases. In contrast, the incidence of dementia in seronegative RA cases was 2.6 (95%CI 1.0,7.0), for an aHR of 1.0 (95%CI 0.29,3.5). Overall, the incidence of dementia in seropositive RA cases was significantly higher than seronegative cases (aHR 3.2, 95%CI 1.2,8.5). Indeed, sensitivity analysis using inverse probability weighting confirmed that among participants aged 50 and older, dementia incidence was higher for seropositive than seronegative RA (aHR 2.9, 95%CI1.1,7.8) (Figure 1).

Conclusion:

Individuals with seropositive RA have an increased risk for incident dementia than those with seronegative RA. Future studies should replicate these findings and investigate the mechanism for this association.

Figure 1.

Cumulative incidence of dementia for individuals with seropositive versus seronegative RA aged 50 and older, balanced by inverse probability weighting

Acknowledgements:

This work was funded by grants from the National Institutes of Health, NIAMS (R01 AR46849) and NIA (R01 AG068192, R01 AG034676).

Disclosure of Interests:

Vanessa Kronzer: None declared, Tina Gunderson: None declared, Cynthia S. Crowson: None declared, John M Davis III Grant/research support from: Pfizer, Maria Vassilaki Shareholder of: equity ownership in Abbott Laboratories, Johnson and Johnson, Medronic and Amgen;, Grant/research support from: Roche and Biogen, Michelle Mielke Consultant of: Biogen and Brain Protection Company, Elena Myasoedova: None declared

Normative Data that Does Not Exclude Participants with Mild Cognitive Impairment Results in Lower Than Expected Memory Impairment Rates, Particularly in Females

Objective

Mayo’s Older Adult Normative Studies (MOANS) have served as an important resource for clinicians for three decades. Data collection was completed prior to the development and widespread use of Mild Cognitive Impairment (MCI) as a construct. Therefore, a portion of individuals included in the MOANS normative studies likely had undetected cognitive impairment.

Method

The Mayo Clinic Study of Aging (MCSA) is a population-based study of cognitive aging among Olmsted County, Minnesota, residents that began in October 2004. We applied age-adjusted MOANS norms (Ivnik et al., 1992) for the Auditory Verbal Learning Test (AVLT) long delay recall to cognitively unimpaired participants age 56 or older in the MCSA (N = 3,603). We used 1-sample tests of proportions comparing observed impairment rates to impairment rates expected based on a normal distribution of performance.

Results

Results showed that a significantly lower than expected number of participants demonstrated impaired delayed recall based on MOANS norms (all p’s < .001). Using a lenient cut-off (< -1 SD), only 7.3% of participants demonstrated impaired performance (vs. 15.9% expected), and this was more pronounced for females (3.5% impaired) relative to males (11.1% impaired). Further, only 0.6% of participants demonstrated impaired performance at a cut-off of < -2 SD, and no participants aged 80-91 reached this cut-off (2.3% expected).

Conclusions

Results suggest that the sensitivity of the original MOANS norms is lowered by likely inclusion of individuals with MCI, particularly in females. Updated normative data for the AVLT that exclude individuals with MCI and adjust for sex are needed.

Systematic literature analysis and review of targeted preventive measures to limit healthcare-associated infections by meticillin-resistant Staphylococcus aureus

Meticillin-resistant Staphylococcus aureus (MRSA) is a major cause of healthcare-associated infections in Europe. Many examples have demonstrated that the spread of MRSA within healthcare settings can be reduced by targeted infection control measures. The aim of this systematic literature analysis and review was to summarise the evidence for the use of bacterial cultures for active surveillance the benefit of rapid screening tests, as well as the use of decolonisation therapies and different types of isolation measures. We included 83 studies published between 2000 and 2012. Although the studies reported good evidence supporting the role of active surveillance followed by decolonisation therapy, the effectiveness of single-room isolation was mostly shown in non-controlled studies, which should inspire further research regarding this issue. Overall, this review highlighted that when planning the implementation of preventive interventions, there is a need to consider the prevalence of MRSA, the incidence of infections, the competing effect of standard control measures (e.g. hand hygiene) and the likelihood of transmission in the respective settings of implementation.

[The 2011 HUS epidemic in Germany. Challenges for disease control: what should be improved?]

From May to July 2011 [corrected] the world's largest outbreak of hemolytic uremic syndrome (HUS) occurred in northern Germany with dramatic consequences for the population, the health care system and the food industry. In the following we examine the detection of the outbreak, epidemic management and related public communication aspects based on scientific publications, media reports as well as own and new data analyses. The subsequent 17 recommendations concern issues such as participation in and implementation of existing and new surveillance systems particularly with respect to physicians, broad application of finely tuned microbiological typing, improved personnel capacity and crisis management structures within the public health service and evidence-based communication by administrations and scientific associations. Outbreaks of similar dimensions can inevitably occur again and result in costs which will far exceed investments needed for early detection and control. This societal balance should be taken into account in spite of limited resources in the public health sector.

[Role of pathogen surveillance and subtyping in outbreak recognition of food-borne bacterial infections. Microbiological perspective - Aims, methods and prospects of pathogen subtyping]

The recognition of infection clusters via determination of clonal relationships between pathogen isolates represents the major aim of pathogen subtyping during outbreaks. In addition, a continuing and comprehensive subtyping of pathogen isolates is a prerequisite for early recognition of changes within pathogen populations, especially of new pathogen types and variants. Here, in an exemplary manner, we outline the current practice in Germany for three important agents of food-borne infections, Salmonella enterica, Listeria monocytogenes and enterohemorrhagic Escherichia coli (EHEC). Pathogen subtyping is mostly performed in specialized laboratories. Collection of representative pathogen isolates is therefore critical for comprehensive pathogen surveillance. Salmonella and L. monocytogenes are usually isolated by sample culturing in primary diagnostic laboratories and a considerable number are sent to the respective reference laboratories for further subtyping. However, the current situation in terms of EHEC is problematic. As the detection of shiga toxin (or gene) is sufficient for diagnosis and case reporting, primary diagnostic laboratories actually rarely isolate EHEC; therefore, a concept for appropriate retrieval of isolates is needed to ensure effective EHEC surveillance in Germany.

[Methicillin-resistant Staphylococcus aureus (MRSA) in medical rehabilitation. Draft of a model hygiene plan]

Rehabilitation facilities often apply the same standards for management of methicillin-resistant Staphylococcus aureus (MRSA) carriers as acute care hospitals. This makes it difficult to ensure access to the facilities and adequate rehabilitation for carriers. A working group of the Bavarian state committee for multiresistant pathogens addressed these problems by a systematic review of literature, expert group meetings and evaluation of existing hygiene plans. Thereby a model hygiene plan for rehabilitation facilities concerning management of MRSA carriers was derived. The management is based on physician risk assessment blending standards applied in acute and long-term care facilities. For rehabilitation typical risk scenario examples of risk analyses are given. The preventive measures are based on the respective objectives of protection. The risk analysis which gives the basis for the model hygiene plan described in this paper gives equal weight to two main objectives of protection: infection control and medical rehabilitation.

[Tuberculosis infection control - recommendations of the DZK]

The epidemiological situation of tuberculosis (TB) in Germany has improved considerably during the past few years. However, those in unprotected contact with infectious tuberculosis patients frequently and/or over longer periods of time and/or intensively continue to have a higher risk for TB infection. Rapid diagnosis, prompt initiation of effective treatment, and adequate infection control measures are of particular importance to prevent infection. The present recommendations depict the essentials of infection control as well as specific measures in the hospital (isolation, criteria for its duration and technical requirements, types of respiratory protection, disinfection measures, waste disposal). The specific requirements for outpatients (medical practice), at home, for ambulance services, and in congregate settings, including prisons, are also addressed. Compared with the previous recommendations the pattern of respiratory protection measures has been simplified. As a rule, hospital staff and those visiting infectious tuberculosis patients are advised to wear respiratory protection that satisfies the criteria of FFP2-masks (DIN EN 149), while patients should wear mouth-nose protectors (surgical masks) in the presence of others and outside the isolation room. A detailed depiction of criteria for isolation and its duration in smear positive and only culturally confirmed pulmonary tuberculosis has been added.

[Tuberculosis infection control--recommendations of the DZK]

The epidemiological situation of tuberculosis (TB) in Germany has improved considerably during the past few years. However, those in unprotected contact with infectious tuberculosis patients frequently and/or over longer periods of time and/or intensively continue to have a higher risk for TB infection. Rapid diagnosis, prompt initiation of effective treatment, and adequate infection control measures are of particular importance to prevent infection. The present recommendations depict the essentials of infection control as well as specific measures in the hospital (isolation, criteria for its duration and technical requirements, types of respiratory protection, disinfection measures, waste disposal). The specific requirements for outpatients (medical practice), at home, for ambulance services, and in congregate settings, including prisons, are also addressed. Compared with the previous recommendations the pattern of respiratory protection measures has been simplified. As a rule, hospital staff and those visiting infectious tuberculosis patients are advised to wear respiratory protection that satisfies the criteria of FFP2-masks (DIN EN 149), while patients should wear mouth-nose protectors (surgical masks) in the presence of others and outside the isolation room. A detailed depiction of criteria for isolation and its duration in smear positive and only culturally confirmed pulmonary tuberculosis has been added.

Clusters of infectious diseases in German nursing homes: observations from a prospective infection surveillance study, October 2008 to August 2009

A prospective infection surveillance study was carried out among residents of seven nursing homes in and around Berlin, Germany, from October 2008 to August 2009. A considerable number of infections were found to occur in clusters. Active surveillance was carried out using pre-established case definitions of infections in nursing homes (McGeer criteria). Case finding was based on routine nursing files. Infection rates were calculated per 1,000 resident days. Clusters were identified using a pre-established definition. In total 511 residents were observed during 74,626 resident days (rd), and 393 infections occurred in 243 participants, giving an overall incidence of infection of 5.3 per 1,000 rd. The most common infections were gastrointestinal infections (n=122; 1.6/1,000 rd), acute respiratory disease (n=86; 1.2/1,000 rd) and urinary tract infections (n=71; 1.0/1,000 rd). Seven clusters involving 74 infections in 57 residents were observed: three of acute respiratory disease, three of acute gastrointestinal disease and one of conjunctivitis. Attack rates varied between 11% and 61%. Clusters occurred frequently in the observed nursing homes and could be detected by infection surveillance based on routine documentation.

Methicillin-resistant Staphylococcus aureus (MRSA): burden of disease and control challenges in Europe

Methicillin-resistant Staphylococcus aureus (MRSA) isa major cause of healthcare- and community-associated infections worldwide. Within the healthcare setting alone, MRSA infections are estimated to affect more than 150,000 patients annually in the European Union (EU), resulting in attributable extra in-hospital costs of EUR 380 million for EU healthcare systems. Pan-European surveillance data on bloodstream infections show marked variability among EU Member States in the proportion of S. aureus that are methicillin-resistant, ranging from less than 1% to more than 50%. In the past five years, the MRSA bacteraemia rates have decreased significantly in 10 EU countries with higher endemic rates of MRSA infections. In addition to healthcare-associated infections, new MRSA strains have recently emerged as community and livestock-associated human pathogens in most EU Member States. The prevention and control of MRSA have therefore been identified as public health priorities in the EU. In this review, we describe the current burden of MRSA infections in healthcare and community settings across Europe and outline the main threats caused by recent changes in the epidemiology of MRSA. Thereby, we aim at identifying unmet needs of surveillance, prevention and control of MRSA in Europe.

The effect of epoch length on the electromyographic mean power frequency and amplitude versus time relationships

The electromyographic (EMG) mean power frequency (MPF) and amplitude versus time relationships are commonly used to characterize localized muscle fatigue.

PURPOSE

The purpose of this study was to compare the effect of epoch length on the individual and mean slope coefficients and y-intercepts resulting from the EMG MPF and amplitude versus time relationships of the vastus medialis (VM) muscle during fatiguing isometric muscle actions at 30 and 75% of maximum voluntary isometric contraction (MVC).

METHODS

Eight adults performed two continuous, isometric muscle actions of the leg extensors at 30 and 75% MVC to exhaustion. Six, 5.0 s epochs of the surface EMG signals were recorded from the VM during each minute. Epoch lengths of 0.5, 1.0, and 2.0 s were selected from the middle of each 5.0 s epoch. Linear regression was used to estimate the slope coefficient and y-intercept values for the EMG MPF and amplitude versus time relationships for each epoch length (0.5, 1.0, 2.0, and 5.0 s) and subject.

RESULTS

There were no significant differences between epoch lengths for the individual or mean slope coefficients or y-intercepts (EMG MPF and amplitude versus time relationships).

CONCLUSION

This study indicated that epochs of 0.5 - 5.0 s resulted in the same characterization of EMG (MPF and amplitude) versus time relationships during isometric muscle actions.

A mechanomyographic fatigue threshold test for cycling

The purposes of this study were twofold: 1) to derive the mechanomyographic mean power frequency fatigue threshold (MMG MPFFT) for submaximal cycle ergometry; and 2) to compare the power outputs associated to the MMG MPFFT to other neuromuscular and gas exchange fatigue thresholds. 9 adults (5 men and 4 women; mean+/-SD age=23.7+/-3.7 years; body weight=66.3+/-8.2 kg) performed an incremental cycle ergometry test to exhaustion while expired gas samples, electromyographic (EMG), and MMG signals were measured from the vastus lateralis muscle. The non-significant correlations (r=0.17 to 0.66; p>0.05) among the physical working capacity at the fatigue threshold (PWCFT), MMG MPFFT, and gas exchange threshold (GET) suggested that different physiological mechanisms may underlie these 3 fatigue thresholds. A significant correlation (r=0.83) for the MPFFT vs. respiratory compensation point (RCP) suggested that these fatigue thresholds may be mediated by a common physiological mechanism. In addition, the significantly lower mean values found for the PWCFT (mean+/-SD=163+/-43 W), MMG MPFFT (132+/-33 W), and GET (144+/-28 W) than MPFFT (196+/-53 W) and RCP (202+/-41 W) suggested that these gas exchange and neuromuscular fatigue thresholds may demarcate different exercise intensity domains.

The effects of parallel versus perpendicular electrode orientations on EMG amplitude and mean power frequency from the biceps brachii

The purposes of this study were threefold: (1) to compare the isometric torque-related patterns of absolute and normalized electromyographic (EMG) amplitude and mean power frequency (MPF) responses for electrode orientations that were parallel and perpendicular to the muscle fibers; (2) to examine the influence of electrode orientation on mean absolute EMG amplitude and MPF values; and (3) to determine the effects of normalization on mean EMG amplitude and MPF values from parallel and perpendicular electrode orientations. Ten adults (5 men and 5 women mean +/- SD age = 23.8 +/- 2.3 years) volunteered to participate in the investigation. Two sets of bipolar surface EMG electrodes (20 mm center to center) were placed parallel and perpendicular to the muscle fibers over the biceps brachii. The subjects performed a maximal voluntary isometric contraction (MVIC) test followed by randomly ordered submaximal muscle actions in 10% increments from 10 to 90% MVIC. Paired t-tests indicated that absolute EMG amplitude values for the parallel electrode orientation were greater (p < 0.05) than those for the perpendicular orientation at all isometric torque levels except 10% MVIC For normalized EMG amplitude values, however, there were no significant mean differences between electrode orientations. There were also no differences between electrode orientations for absolute or normalized EMG MPF values. In 30% of the cases, different torque-related patterns of responses were observed between the parallel and perpendicular electrode orientations for the absolute and normalized EMG amplitude and MPF values. Therefore, the results of the present study support the need for standardizing electrode orientation to compare the pattern of responses for EMG amplitude and MPF values and normalizing EMG amplitude data to compare the mean values.

Observation of an "ABC" Effect in proton-proton collisions

The cross section for inclusive multipion production in the pp-->ppX reaction was measured at COSY-ANKE at four beam energies, 0.8, 1.1, 1.4, and 2.0 GeV, for low excitation energy in the final pp system, such that the diproton quasiparticle is in the 1S0 state. At the three higher energies, the missing-mass M_{X} spectra show a strong enhancement at low M_{X}, corresponding to an Abashian-Booth-Crowe effect that moves steadily to larger values as the energy is increased. Despite the missing-mass structure looking very different at 0.8 GeV, the variation with M_{X} and beam energy are consistent with two-pion production being mediated through the excitation of two Delta(1232) isobars, coupled to S and D states of the initial pp system. There is no sign of any resonancelike structure in the energy dependence of the type recently observed for the pn-->dpi;{0}pi;{0} total cross section.

The effect of pedaling cadence and power output on mechanomyographic amplitude and mean power frequency during submaximal cycle ergometry

The purpose of this study was to examine the effects of power output and pedaling cadence on the amplitude and mean power frequency (MPF) of the mechanomyographic (MMG) signal during submaximal cycle ergometry. Nine adults (mean age +/- SD = 22.7 +/- 2.1 yrs) performed an incremental (25 W increase every min) test to exhaustion on an electronically braked cycle ergometer to determine VO2Peak and Wpeak. The subjects also performed three, 8 min continuous, constant power output rides (randomly ordered) at 35%, 50%, and 65% Wpeak. The continuous 8 min workbouts were divided into 4 min epochs. The subjects pedaled at either 50 or 70 rev x min(-1) (randomized) during the first 4 min epoch, then changed to the alternate cadence during the second 4 min epoch. The MMG signal was recorded from the vastus lateralis during the final 10 s of each minute. Two separate two-way [cadence (50 and 70 rev x min(-1)) x %Wpeak (35, 50, and 65)] repeated measures ANOVAs indicated that MMG amplitude followed power output, but not pedaling cadence, whereas MMG MPF was not consistently affected by power output or pedaling cadence. Furthermore, these findings suggested that power output was modulated by motor unit recruitment and not rate coding.

[Five years of the Robert Koch Institute guidelines for reprocessing of flexible endoscopes. A look back and a look forward]

In a short review the national and international reception of the German guidelines for reprocessing flexible endoscopes is presented. The recommendations of the guidelines are discussed in view of recent knowledge on old problems such as prion inactivation and new infectious diseases and new microorganisms such as SARS, avian influenza and C. difficile. New disinfectants and new methods for endoscope disinfection are mentioned, the importance of careful cleaning is underlined. The German guidelines of the Robert Koch Institute and the US Multi-Society guidelines, published in 2003, are compared. The discrepancies concerning recommendations for water quality for final rinsing and need of microbiological controls of endoscope reprocessing are stressed. Aspects not mentioned in the German guidelines, e.g. duration of storage after reprocessing and risk of infection transmission by the endo-washer, are discussed.

Precision study of the eta3He system using the dp--> 3Heeta reaction

The differential and total cross sections for the dp--> 3Heeta reaction have been measured in a high precision high statistics COSY-ANKE experiment near threshold using a continuous beam energy ramp up to an excess energy Q of 11.3 MeV with essentially 100% acceptance. The kinematics allowed the mean value of Q to be determined to about 9 keV. Evidence is found for the effects of higher partial waves for Q >or= 4 MeV. The very rapid rise of the total cross section to its maximum value within 0.5 MeV of threshold implies a very large eta3He scattering length and hence the presence of a quasibound state extremely close to threshold.

Community MRSA

Additional to epidemic methicillin resistant Staphylococcus aureus (haMRSA) which had been disseminated in and between hospitals, MRSA emerged in the community independent upon the nosocomial setting (caMRSA). caMRSA possess the capacity to form Panton-Valentine-Leukocidin (PVL) as a special virulence factor. In general PVL-positive S. aureus isolates are associated with necrotizing skin and soft tissue infections as well as with necrotizing pneumonia. caMRSA are less "broad" resistant against different groups of antibiotics as haMRSA and require special attention when performing antimicrobial susceptibility testing. Prevention of further dissemination of caMRSA requires appropriate diagnosis, therapy and sanitation of the carrier state. Hygienic measures have not only to be taken in ambulant treatment but also in households of affected patients.

Effects of 28 days of beta-alanine and creatine monohydrate supplementation on aerobic power, ventilatory and lactate thresholds, and time to exhaustion

The effect of beta-alanine (beta-Ala) alone or in combination with creatine monohydrate (Cr) on aerobic exercise performance is unknown. The purpose of this study was to examine the effects of 4 weeks of beta-Ala and Cr supplementation on indices of endurance performance. Fifty-five men (24.5 +/- 5.3 yrs) participated in a double-blind, placebo-controlled study and randomly assigned to one of 4 groups; placebo (PL, n = 13), creatine (Cr, n = 12), beta-alanine (beta-Ala, n = 14), or beta-alanine plus creatine (CrBA, n = 16). Prior to and following supplementation, participants performed a graded exercise test on a cycle ergometer to determine VO(2peak), time to exhaustion (TTE), and power output, VO(2), and percent VO(2peak) associated with VT and LT. No significant group effects were found. However, within groups, a significant time effect was observed for CrBa on 5 of the 8 parameters measured. These data suggest that CrBA may potentially enhance endurance performance.

Activity of an alkaline 'cleaner' in the inactivation of the scrapie agent

The capacity of a routinely available alkaline cleaner for medical devices to inactivate the causative agent of a transmissible spongiform encephalopathy (TSE) was tested. The co-incubation of brain homogenates, prepared from terminally ill scrapie-infected hamsters, with the cleaner led to the denaturation of misfolded protein as the proteinase K-resistant prion protein was no longer detectable after such treatment. In addition, intra-cerebral inoculation of hamsters with the alkaline cleaner-treated and subsequently neutralized samples reduced the level of infectivity of the material below the limit of detection. This report shows the possibility that a routinely available alkaline cleaner could reduce the infectivity of TSE agents and so minimize the risk of iatrogenic transmission of TSEs by asymptomatic carriers. This study is intended to encourage further investigations in this field.

[1974-2004: the Commission for Hospital Hygiene has been working for 30 years. From the "old" to the "new" guideline]

After 2 years of preparation, the Commission for Hospital Hygiene, founded in 1974 by the former German Public Health Service, published the "Guideline for Assessment,Prevention, and Controlling of Nosocomial Infections," which represented an exemplarily complete standard for hospital hygiene. In 1997 within the framework of planning the amendment to the Federal Epidemic Law, a new Commission for Hygiene and Infectious Disease Prevention started work and adapted the guideline to meet today's standards of systematic risk analysis and risk management. The amended Infection Protection Act (Infektionsschutzgesetz, IfSG), which came into force in January 2001, installed the Commission for Hospital Hygiene and Infectious Disease Prevention legally and required it to formulate a guideline to decrease the rate of nosocomial infections, the number of outbreaks, and the dissemination of antibiotic-resistant pathogens in healthcare facilities by establishing standards of modern prevention. This article describes the political importance of nosocomial infections for public health as well as the working basis, the methods, and the latest guidelines of the Commission.