From randomized trial to practice: single institution experience using the GOG 172 i.p. chemotherapy regimen for ovarian cancer

BACKGROUND

The objective of the study was to evaluate completion rates and toxic effects of an i.p. chemotherapy regimen in a cross-section of nonselected patients with ovarian cancer (OC).

PATIENTS AND METHODS

All patients with stage IIIC OC consecutively operated at our institution from January 2006 to December 2007 were prospectively collected and analyzed.

RESULTS

Eighty-nine patients with stage IIIC OC optimally debulked were evaluated for this study. An i.p. port was primarily placed in 53 of 89 (60%), and i.p. chemotherapy was recommended in 55 patients. Reasons for not recommending i.p. chemotherapy in patients optimally debulked included postoperative complications (n = 7: 8%), poor nutritional/functional status (n = 5: 6%), and extensive surgery including bowel resection (n = 9: 10%). Thirty-three patients (33/55: 60%) recommended to receive i.p. chemotherapy-initiated i.p. treatment. Fifty-two percent of those beginning i.p. therapy (17/33) received three or more cycles with 36% (12/33) successfully completing six cycles. Reasons for discontinuation included grade 3-4 nephrotoxicity in 3 of 21 (14%), febrile neutropenia/sepsis in 3 of 21 (14%), port infection or malfunction in 8 of 21 (38%).

CONCLUSIONS

The i.p. chemotherapy regimen used in a consecutive cohort of patients carries could be completed in only a small percentage of patients. Less toxic regimens with higher acceptability should be considered.

Breaking Bad News: Relationship between the Experience Receiving Breast Cancer Diagnosis and Early Psychological Adjustment

Experiences at time of breast cancer (BC) diagnosis are associated with patient psychological health several months to years later; however, little investigation of this relationship during initial period following diagnosis has been undertaken.METHODS:This prospective study was designed to characterize the experience of receiving cancer diagnosis in women initiating treatment for BC (Stage 0 to III) and to identify associations between this experience and early psychological adjustment, hopefulness, and satisfaction with medical care. 121 women who recently received BC diagnosis prompting referral to specialty center responded to questionnaires assessing their experiences and coping styles:1. Experience Receiving Breast Cancer Diagnosis (ERBCD), categorizing patient demographic, medical, and psychosocial factors; context factors (location, privacy); clinician factors and behaviors.2. Cancer Diagnostic Interview Scale (CDIS) for perceived psychotherapeutic techniques used by clinican conveying cancer diagnosis.3. Mental Adjustment to Cancer Scale (MAC) for coping styles of fighting spirit, hopelessness/helplessness, anxious preoccupation, fatalism, and avoidance.Subjects completed the Profile of Mood States (POMS), Spielberger State-Trait Anxiety Inventory (STAI) and ratings of hopefulness and satisfaction. Multivariate regression analysis was employed with scores from POMS, STAI, hopefulness and satisfaction as dependent variables and values from ERBCD, CDIS and MAC as independent variables.RESULTS:Patients received diagnosis from general physicians, surgeons, radiologists, nurses, NP/PAs, gynecologists, breast specialists, family members, and secretaries. BC diagnosis was disclosed by telephone (59%), face-to-face (40%), letter (1%) and spouse (1%). Mean CDIS-Caring score was 3.4 ± 1.1 and CDIS-Competence was 4.0 ± 0.9 of 5.0. Results of multivariate regression analysis are shown:POMS-Total Mood DisturbanceIndependent VariableParameterSEP ValueAge-0.6600.2760.0183MAC-Fighting Spirit-1.1550.4360.0093MAC-Anxious Preoccupation5.2720.780< 0.001 STAI-State AnxietyIndependent VariableParameterSEP ValueRecent Stress Level0.9420.3710.0127MAC-Fighting Spirit-0.3670.1480.0147MAC-Anxious Preoccupation1.9740.271<0.0001MAC-Avoidant4.4671.4950.0036 Satisfaction was predicted by CDIS-Caring, individual conveying diagnosis, type of information helpful, feeling concerns were understood.CONCLUSIONS:Experiences receiving BC diagnosis are variable and associated with hopefulness and satisfaction. Age, recent stress level and predominant coping style appear more predictive of psychological adjustment (POMS, STAI) than experience receiving BC diagnosis. Understanding these relationships provides direction for future research and clinical interventions to identify patients at risk for early mood disturbance and anxiety following BC diagnosis and to modify aspects of conveying BC diagnosis that influence hopefulness and satisfaction with medical care.HopefulnessIndependent VariableParameterSEP ValueCDIS-Caring0.4270.088<0.0001Diagnosis by Telephone0.3810.1770.0338Opportunity to Ask Questions0.4440.2270.0535Recent Stress Level-0.0820.0290.0057MAC-Fighting Spirit0.0430.0120.0005MAC-Anxious Preoccupation-0.0610.0230.0098 

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1069.

Ki67: A Time-Varying Biomarker of Risk of Breast Cancer in Atypical Hyperplasia

Background: Uncontrolled proliferation is a defining feature of the malignant phenotype. Ki67 is a marker for proliferating cells and is overexpressed in many breast cancers. Atypical hyperplasia is a premalignant lesion of the breast (relative risk ∼ 4.0). Here we asked if Ki67 expression could stratify risk in women with atypia.Methods: Ki67 expression was assessed immunohistochemically by digital image analysis in archival sections from 192 women with atypia diagnosed at the Mayo Clinic 1/1/67-12/31/91. Risk factor and follow-up data were obtained via study questionnaire and medical records. Observed breast cancer events were compared to population expected rates (Iowa SEER) using standarized incidence ratios (SIRs). We examined both short-term (within 10 years) and long-term (after 10 years) risk of breast cancer (BC) following atypia biopsy.Results: The median value for percent positive cells for Ki67 was 1.0%; the 75th percentile value was 2.3%. Based on the empirical distribution of staining values in our cohort, we selected a cutoff of 2% cells positive to separate high from low staining. There were no differences in Ki67 levels by age at biopsy, type of atypia (ADH, ALH, or both), number of foci of atypia, or family history. 32 women developed BC over a median of 14.6 years. Among them, those with ≥2% Ki67 expression had a shorter time to breast cancer (median 5.5 years, IQR=3.2-7.2) than those with <2% cells positive (median=13.8 years, IQR=11.6-20.3). There was a positive association between Ki67 overexpression (≥2% of cells positive) and risk of BC in the first 10 years of follow-up (SIR=4.42 [95% CI 2.21-8.84]). This excess risk resulted in a 10-year cumulative incidence of 14.1%. In contrast, in the women with low Ki67 expression, we found no increased risk of BC in the first 10 years, with SIR 1.01 (95% CI 0.38-2.70), which was significantly lower than the women with high expression (p=0.01). The 10-year cumulative incidence of BC was 3% for the low Ki67group, in line with population averages. After 10 years, risk increased significantly in the low Ki67 group [SIR 5.69 (3.63-8.92)] vs. no increased risk in the high Ki67 group [SIR 0.78 (0.11-5.55)]. We formally examined this apparent time-dependent difference in incidence patterns by Ki67 staining levels via Poisson regression analysis, and found a statistically significant interaction between pre- vs. post-10 years incidence and high vs. low staining levels (p<0.001).Conclusions: Ki67 appears to be a time-varying biomarker of risk of breast cancer in women with atypical hyperplasia. Women whose atypias show higher proliferation rates have an increased risk for an earlier BC (within 10 years). Those with lower proliferation rates tend to develop BCs later, after 10 years. Ki67 levels may help to define the time period of greatest risk for women with atypia.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 909.

Lobular Involution and Mammographic Density: Independent Contributors to Breast Cancer Risk

Background: Women with benign breast disease are at elevated breast cancer risk. In order to accurately predict a woman's individual risk of breast cancer, a breast cancer risk-prediction model is needed that incorporates significant breast cancer risk factors. This report describes two factors: tissue based assessment of lobular involution, and radiological marker- mammographic density (MD). Lobular involution, or physiologic atrophy of the breast glandular epithelium, is inversely associated with breast cancer risk. MD is a strong positive risk factor for breast cancer. With increasing age, the extent of lobular involution increases while MD decreases. However, it is unclear whether involution and MD represent independent breast cancer risk factors. We examined breast cancer risk associated with lobular involution and MD in women with benign breast disease (BBD) to determine whether these features are independently associated with breast cancer risk.Methods: Using the Mayo Clinic Surgical and Pathology Indices, 9376 women ages 18 to 85 with benign excisional breast biopsy between January 1, 1967 and December 31, 1991 were identified and formed the Mayo BBD cohort. We studied a sub-cohort of women diagnosed with BBD between 1985 and 1991 (when MD was clinically assessed and recorded) who had a mammogram within 6 months of the BBD diagnosis. Breast cancer outcomes were determined through the Mayo medical records and a study-specific questionnaire. Lobular involution extent was assessed in background tissue as 'none' (0% lobules involuted), 'partial' (1-74% lobules involuted) or 'complete' (≥75% lobules involuted). MD was classified as Wolfe's parenchymal pattern (PP) as N1/ fatty; P1; P2; and DY/ homogenously dense. Hazard ratios and confidence intervals were calculated using Cox regression analyses, adjusting for confounders: age, parity, BMI, BBD histology, menopausal status, family history, PP and involution extent.Results: A total of 2666 women in the Mayo BBD cohort, with biopsies between 1985 and 1991, had a mammogram within 6 months of the breast biopsy. The mean age at biopsy was 54.6 years. After a mean follow-up of 13.3 years, 172 (6.5%) women developed breast cancer. After adjustment for PP and other confounders, women with no or partial involution had elevated risk compared to women with complete involution (HR 2.62 [95% CI 1.39, 4.94] for no involution and 1.61 [95% CI 1.03, 2.53] for partial involution; complete involution as reference group; p for trend 0.003). Moreover, women with dense breasts were at greater risk compared to women with nondense breasts (HR 1.67 [95% CI 1.0, 2.73] for DY pattern, 1.96 [95% CI 1.2 – 3.21] for P2, 1.23 [95% CI 0.67, 2.26] for P1; N1 category as reference group; p for trend 0.02). Multivariate analyses also showed that women with the combination of no involution and dense breasts had greater risk compared to those with complete involution and nondense breasts (HR 4.08 [95% CI 1.72, 9.68]).Conclusion: Lobular involution and MD are both risk factors for breast cancer; this report is the first to demonstrate that each provides unique information about breast cancer risk. These findings emphasize the potential for inclusion of both these factors in future breast cancer risk-prediction models.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6064.

Evaluation of the Tyrer-Cuzick Model in Women with Atypical Hyperplasia

Background: Risk prediction models are important clinical tools for counseling and decision making for women with an elevated risk of breast cancer, such as women with atypical lobular or ductal hyperplasia (atypia). The Gail model has been shown to underestimate the risk of breast cancer in women with atypia. We sought to evaluate the performance of the Tyrer-Cuzick model in a well-defined cohort of women with atypia.Methods: The Mayo Benign Breast Disease (BBD) Cohort includes 9,376 women aged 18 to 85 who had an open breast biopsy with benign pathological findings between 1967 and 1991. The subset of women with atypia was identified by our study pathologists. Risk factor data required by the Tyrer-Cuzick model were collated for each woman, and the model was used to predict each woman's risk of developing invasive breast cancer within ten years. The predicted numbers of breast cancers were compared to the observed numbers to assess overall model calibration, and the concordance between breast cancer outcomes and predicted probabilities was used to measure the accuracy of the model on the individual level. Subset analysis of women with strong family history was performed. Strong family history was defined as: at least one first-degree relative with breast cancer before the age of 50 years or two or more relatives with breast cancer, at least one being a first degree relative.Results: Three hundred and thirty one women with atypia were identified. Over a mean follow up of 13.7 years, 62 (19%) women have developed invasive breast cancer. Thirty one women developed invasive cancer in the first ten years after biopsy. The Tyrer-Cuzick model predicted that 64.6 invasive breast cancers would occur in the first ten years after biopsy. Thus, the predicted to observed ratio was 2.08 [95% CI: 1.47 – 2.96], p < 0.001).The concordance statistic was 0.51, revealing that the Tyrer-Cuzick model did not accurately distinguish, on an individual level, between women who were diagnosed with invasive breast cancer within ten years of biopsy and those who were not.Performance was somewhat better in the subset of 68 women with a strong family history of breast cancer. The model predicted 12.3 invasive breast cancers, and 7 were observed, for a predicted to observed ratio of 1.76 [95% CI: 0.84 – 3.70]. The concordance statistic was 0.57.Conclusion: The Tyrer-Cuzick model significantly overestimated the risk of breast cancer in the first ten years after biopsy for this group of women with atypia. Individual risk estimates showed poor concordance. Performance was slightly improved in women with a strong family history of breast cancer. Physicians should be cautious when using the Tyrer-Cuzick model to predict ten-year risk in patients with atypia.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6063.

p16 Expression and Breast Cancer Risk in Women with Atypical Hyperplasia

Background: p16 is a nuclear protein encoded by the p16INK4a gene that regulates the G1-S cell cycle checkpoint. Its overexpression could reflect normal proliferative arrest, but also the evolution of carcinogenic processes that have overcome the p16 block, with progression from hyperplasic lesions to invasive breast cancer. Our aim with this study was to correlate p16 expression, both individually and in combination with expression of COX-2 and Ki67, with subsequent risk of breast cancer among women with atypical hyperplasia. Methods: p16 expression was assessed by immunohistochemical assays in archival paraffin-embedded, formalin-fixed sections from 233 women with atypia whose biopsy specimens were obtained via surgical excision at the Mayo Clinic from January 1, 1967, through December 31, 1991. p16 expression was scored as percent of cells positive and intensity of staining. Risk factor information and follow-up for breast cancer events were obtained via study questionnaire and the medical records. Standardized incidence ratios (SIRs) were used to compare observed numbers of breast cancer events to population-based expected counts, both at 10 years and over the entire course of follow-up. Results: Forty-seven patients (20%) developed breast cancer with a mean follow-up of 14.3 (SD=6.96) years. The overall risk of developing breast cancer was not modified by increasing p16 overexpression (low percent of staining with RR=3.89, 95% CI=2.72 to 5.56; high percent of staining with RR=3.91, 95% CI=2.43 to 6.28; similar results for intensity of staining). However, overexpression of both p16 and COX2 conveyed a stronger risk of breast cancer (SIR=4.01, 95% CI 2.28 to 7.07) as compared to dual low expression (SIR 1.78, 95% CI 0.67-4.74). Moreover, overexpression of both Ki67 and p16 was related to a higher 10-year breast cancer risk (SIR 6.25, 95% CI 2.35-16.6) as compared to low expression of both markers (SIR 0.87, 95% CI 0.22-3.49). Conclusions: although single expression of p16 does not stratify breast cancer risk, its overexpression in concert with biomarkers that reflect other carcinogenic processes (e.g. Ki67 and COX2) could help to define risk of tumor development.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 910.

Evaluation of aromatase expression in mammographically dense and non-dense regions of the breast in healthy women

Abstract #4033

Background: Aromatase activity within the breast is a source of estrogen that may cause breast cancer. Mammographic density (MD) is a risk factor for breast cancer whose biologic basis is unknown. Our study compared aromatase expression in tissue from dense and non-dense areas of the breasts of healthy volunteers.
 Methods: Participants were 40+ yrs, had a screening mammogram with visible MD, no history of cancer and were not on endocrine therapy. Ultrasound-guided core biopsies were done within 6 months of mammography to obtain three paired cores from mammographically dense and non-dense regions of the breast. Immunostaining for aromatase expression employed the streptavidin-biotin amplification method using the recently developed 677 mouse monoclonal antibody. Immunoreactivity (IR) was scored in terms of proportion of cells staining positive for aromatase (PPC) (0=<1%, 1=1-25%, 2=26-50%, 3=51+% (and 4=75%+ for adipocytes)) and relative immunointensity (0=none, 1=weak, 2=moderate, 3=intense) for each cell type (stroma, normal ductal epithelium, adipocytes). A composite score weighting the PPC by their relative intensity (range 0-9; 0-12 for adipocytes) was also calculated. The sum of the composite score across the three cell types provided a global assessment of aromatase IR. Repeated measures analyses evaluated differences in aromatase IR for dense compared to non-dense tissue within and across cell types. Parameter estimates (β) indicated the average difference between dense and non-dense IR.
 Results: 18 (37%) of the 49 participants were premenopausal (median age 46 yrs). Summing across cell types, the global composite score showed increased aromatase IR on sections sampled from dense vs. non-dense regions (β=5.3,p<0.001). This global difference reflected increased aromatase IR in the stroma and normal ductal epithelium from dense sections (vs. non-dense). For 42 women with >1% stromal cells on each section, there was evidence for increased IR on dense sections as indicated by the greater PPCs (β=0.9), relative intensity (β=0.7) and composite score (β=2.7)(p's<0.001). Similarly, for 20 women with >1% normal ductal epithelium in both dense and non-dense sections, there was a greater composite score (β=1.4,p=0.004) for cells on dense sections although differences for PPC (β=0.3,p=0.11) and relative intensity (β=0.3,p=0.09) did not reach statistical significance. No differences were seen in IR for adipocytes from the two density regions (46 women). Findings were unchanged with adjustment for covariates, including proportions of each cell type per section.
 Conclusions: There is strong evidence for increased aromatase expression in the stromal and normal ductal epithelium of dense vs. non-dense tissue. These results support ongoing research into mammographic density as a biomarker of effect of aromatase inhibitors.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4033.

Risk assessment and risk reduction strategies: overview

Abstract #MS1-1

In this mini-symposium, we will address the major risk factors for breast cancer, current risk prediction tools, and measures to reduce risk in those women deemed at high risk. Those factors that convey a significantly increased risk of breast cancer (e.g. relative risk greater than 4.0) include: strong family history of breast cancer (i.e. early onset of disease, multiple relatives with disease, including BRCA1/2 carriers); atypical hyperplasia on benign biopsy; older age; and dense breast tissue. Multiple other features are recognized as contributing to breast cancer risk but to a lesser degree. These include having a family history of breast cancer but not with a hereditary pattern (RR approximately 2.0), benign breast disease (RR 1.5), multiple reproductive factors including early menarche, late menopause, current or recent estrogen plus progesterone use, current OC use (all with relative risks in the 1.2-1.3 range); and alcohol use (e.g. 3 drinks per day) (RR∼1.3). Numerous other features such as induced abortion and sedentary lifestyle have been reported to increase risk of breast cancer but to a very minor degree and results are not consistent.
 Several risk prediction models for breast cancer focus on an individual's likelihood of carrying a hereditary predisposition to the disease (e.g. Frank, Couch, Shattuck-Eidens, Parmigiani, BRCAPRO, BOADICEA, Claus). Outside of the hereditary setting, the most widely used tool is the Gail model. Features incorporated in the Gail model include age, family history, number of breast biopsies, age at menarche, age at first live birth, and the presence of atypia on a benign biopsy. While the Gail model has been shown to be calibrated in predicting number of breast cancers likely to develop in groups of women, its discriminatory accuracy in predicting risk for individual women is limited. This limitation is not well appreciated by many clinicians.
 Regarding options for surgical risk reduction in high risk individuals, several studies examined the efficacy of both bilateral and contralateral mastectomy in women at increased risk for breast cancer, including BRCA1/2 carriers. Results consistently show a greater than 90% reduction in risk of subsequent breast cancer. A study by the Cancer Research Network (6 HMOs) examined the impact of contralateral PM on mortality from breast cancer and showed reduced death from breast cancer with CPM (HR 0.57 [0.45-0.72]).
 Studies of risk-reducing salpingo-oophorectomy (RRSO) in BRCA carriers have shown dramatic reductions in risk of subsequent ovarian/peritoneal cancer, providing approximately 90% protection. The reduction in breast cancer risk after RRSO is seen only when the oophorectomy is performed in premenopausal women. Recent data on 368 BRCA1 and 229 BRCA2 carriers from a multicenter study show a differential effect on breast cancer risk following RRSO by mutation type. The hazard ratio for risk of breast cancer in BRCA2 carriers was 0.28 (0.08-0.92) (p 0.04) but for BRCA1 carriers was 0.61 (0.30-1.22) (p 0.16). This appeared to be due to the preponderance of ER-negative breast cancers in BRCA1 carriers, where no risk reduction with RRSO was seen. (N Kauff et al, JCO, 3/10/08)

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr MS1-1.

[Massive hemorrhage following photodynamic therapy in exudative ARMD]

Photodynamic therapy (PDT) can prevent visual loss and the risk of hemorrhage in exudative ARMD. Nevertheless, it can sometimes complicate with massive hemorrhage. We report the case of a massive macular hemorrhage 4 days after a first treatment with dynamic phototherapy (PDT) with Visudyne for rapidly progressive (6 months) exudative AMD with occult neovessels in an 86-year-old female. The rationale for PDT was a rapidly progressive lesion with preserved visual acuity (20/40). Four days after injection, a massive submacular hemorrhage of 6 disc diameter developed, with a dramatic decrease in visual acuity. This hemorrhage recovered within 6 months, producing large, fibroglial, submacular scarring with changes on the retinal pigment epithelium. This case highlights the possible side effects of this treatment.

[Measurement of the central corneal power after myopic LASIK]

PURPOSE

Comparison of the central corneal refractive power before and after myopic LASIK using the Keratograph and the Pentacam. The Scheimpflug technique (Pentacam) enables the measurement of the corneal refractive power by examining the anterior and posterior corneal curvature.

METHOD

The corneal refractive power of 59 eyes was examined before, 3 months and 6 months after myopic LASIK. The refractive power was measured at the corneal apex and at a distance of 2 and 4 mm. Statistical analysis was performed using the Wilcoxon signed rank test; a p value of 0.05 or less was considered statistically significant.

RESULTS

At the corneal apex and at a distance of 2 mm the findings with the Keratograph showed a higher refractive power of up to 1.05 D. The differences were statistically significant at all times. At a distance of 4 mm from the corneal apex postoperatively there was no statistically significant difference.

CONCLUSION

The results using the Pentacam system showed a lower corneal refractive power following myopic LASIK at all times. Its measuring principle compared to that of the Keratograph should be preferred when detecting changes of the refractive power of the central cornea after corneal refractive procedures.

Spin gases: quantum entanglement driven by classical kinematics

A spin gas is a natural extension of a classical gas. It consists of a large number of particles whose (random) motion is described classically, but, in addition, have internal (quantum mechanical) degrees of freedom that interact during collisions. For specific types of quantum interactions we determine the entanglement that occurs naturally in such systems. We analyze how the evolution of the quantum state is determined by the underlying classical kinematics of the gas. For the Boltzmann gas, we calculate the rate at which entanglement is produced and characterize the entanglement properties of the equilibrium state.

Entanglement in spin chains and lattices with long-range Ising-type interactions

We consider N initially disentangled spins, embedded in a ring or d-dimensional lattice of arbitrary geometry, which interact via some long-range Ising-type interaction. We investigate relations between entanglement properties of the resulting states and the distance dependence of the interaction in the limit N-->infinity. We provide a sufficient condition when bipartite entanglement between blocks of L neighboring spins and the remaining system saturates and determine S(L) analytically for special configurations. We find an unbounded increase of S(L) as well as diverging correlation and entanglement length under certain circumstances. For arbitrarily large N, we can efficiently calculate all quantities associated with reduced density operators of up to ten particles.

Amphiphilic conetworks as regenerative controlled releasing antimicrobial coatings

Bitelechelic polydimethylsiloxanes (PDMS) and 2-hydroxyethylacrylate (HEA)/acrylic acid(AA) were photopolymerized to give nanophase separated amphiphilic 20-mum-thin coatings covalently attached to glass. The coatings quickly take up the antimicrobial surfactant cetyltrimethylammonium chloride (CTAC). After a 30 min loading period the release of CTAC in water was followed by simultaneously measuring both the antimicrobial activity of the coating's surface against Staphylococcus aureus and the release of the structurally related dye Rhodamine B. Depending on the composition the antimicrobial activity remained up to 3 weeks. The influence of different pH, varying sodium chloride concentrations, and the surfactant Pluronic was investigated. However, even in the cases of 160 mM NaCl and 1 wt.% Pluronic as release medium, the antimicrobial activity remained more than 6 days in case of a coating consisting of 45 wt.% PDMS, 31 wt.% PHEA, and 25 wt.% PAA. Mechanistic investigations revealed that the CTAC-loaded coatings act like contact-active surfaces, i.e., they do not kill microbes in the surrounding solution but only on their surface. This supports our hypothesis that the antimicrobial action is due to a concentration gradient of CTAC on the surface, allowing it to be antimicrobial on contact and to release only very low concentration of the biocide into the surrounding.

Molecular dynamics in thin grafted and spin-coated polymer layers

Broadband Dielectric Spectroscopy is employed to study the molecular dynamics in thin layers of grafted and spin-coated polydimethylsiloxane (PDMS) and of the type-A polymer cis-1,4-polyisoprene (PI). Strong resemblance with low-molecular-weight systems is found but additionally the conformation of the chain and its extension becomes important. For PI a confinement-induced relaxation is found. It is observable if the layer thickness is comparable to the end-to-end vector of the chain and it depends strongly on the separation between interfaces. In contrast, the dynamic (and hence the calorimetric) glass transition is not affected by the geometrical confinement.