Occupational coke oven emissions exposure and risk of abnormal liver function: modifications of body mass index and hepatitis virus infection

OBJECTIVES

Occupational coke oven emissions (COEs) have been considered an important health issue. However, there are no conclusive data on human hepatic injury due to COE exposure. The association of COE exposure with liver function was explored and the effects of modification of potential non-occupational factors were assessed.

METHODS

705 coke oven workers and 247 referents were investigated. Individual cumulative COE exposure was quantitatively estimated. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase, alkaline phosphatase, hepatitis B surface antigen and anti-hepatitis C antibody were measured.

RESULTS

Among those with high COE exposure, the adjusted ORs of abnormal ALT and AST were 5.23 (95% CI 2.66 to 10.27) and 1.95 (95% CI 1.18 to 3.52), respectively. Overweight individuals (body mass index (BMI) > or =25 kg/m(2)) with high COE exposure had elevated risks of abnormal ALT (adjusted OR 23.93, 95% CI 8.73 to 65.62) and AST (adjusted OR 5.18, 95% CI 2.32 to 11.58). Risk of liver damage in hepatitis B virus- or hepatitis C virus-positive individuals with COE exposure was also elevated.

CONCLUSIONS

Long-term exposure to COE increases the risk of liver dysfunction, which is more prominent among those with higher BMI and hepatitis virus infection. The risk assessment of liver damage associated with COE exposure should take BMI and hepatitis virus infection into consideration.

The association of metabolic syndrome with triple-negative breast cancer

1038

Background: Metabolic syndrome, a conglomerate of obesity, insulin resistance, hypertriglyceridemia, low HDL (high density lipoprotein), and hypertension is associated with an increased risk of breast cancer. However, no clear association has been shown between the highly aggressive triple-negative breast cancer and metabolic syndrome. Methods: In a retrospective review we compared triple-negative and non-triple-negative breast cancer cases for the presence of metabolic syndrome by NCEP (National Cholesterol Education Program) or AACE (American Association of Clinical Endocrinologists) definitions. Data on metabolic syndrome criteria, tumor size, grade, lymph node status, and ductal carcinoma in situ (DCIS) were reviewed. Chi-square test or Student's t-test was used for data analysis. Results: The entire cohort of 176 patients (12.5% African-American) with median age 56.5 years (range 26–91 years) comprised of 86 triple-negative cases and 90 non-triple-negative cases. A statistically significant association of triple-negative breast cancer with metabolic syndrome was observed. According to the NCEP criteria 58.1% of triple negative patients had metabolic syndrome as compared to only 36.7% of non-triple negative patients (p = 0.004). Consistently, by the AACE criteria 52.3% of triple negative patients had metabolic syndrome as compared to 34.4% of non-triple negative patients (p = 0.017). Contrary to blood glucose, triglyceride, or HDL levels, which independently showed significant association with triple-negative breast cancer, hypertension, or BMI showed no independent association. Additionally, triple-negative tumors displayed a significantly higher histologic grade and relative paucity of ductal carcinoma in situ (DCIS) when compared to the non-triple negative tumors (p < 0.001). Conclusions: The data suggests that the metabolic syndrome is significantly more prevalent in triple-negative breast cancer patients when compared to the non-triple-negative patients. Additionally, triple-negative breast cancer showed a significantly higher histologic grade and a relative absence of DCIS. Whether the presence of metabolic syndrome preferentially increases the risk of developing triple-negative-breast cancer needs to be elucidated by future prospective studies.

No significant financial relationships to disclose.

Impact of short-term therapies with biologics on prothrombotic biomarkers in rheumatoid arthritis

BACKGROUND

Imbalance of haemostasis in patients with rheumatoid arthritis (RA) contributes to future risk of cardiovascular diseases (CVD). Prothrombotic molecules, e.g. fibrinogen, D-dimer, and tPA are elevated in plasma of RA patients, being associated to CVD. There is no imformation about the influence of biological drugs, e.g. anti-CD20 and tumor necrosis factor (TNF) antibodies on these prothrombotic molecules.

OBJECTIVE

To assess whether anti-TNF and anti-CD20 therapies modify the profiles of cardiovascular risk factors in patients with RA.

METHODS

The expression of prothrombotic molecules in plasma was investigated in 10 RA patients before and after treatment with TNF-alpha antibodies and in another 12 RA patients before and after anti-CD20 treatment.

RESULTS

Both anti-TNF and anti-CD20 infusions gave rise to clear clinical improvement. However, only anti-CD20 infusion significantly (p=0.05) reduced concentration of fibrinogen (p=0.05), D-dimer (p<0.001), as well as tPA levels (p<0.01). In contrast, in TNF antibody treated patients only tPA levels were significantly decreased following the treatment (p<0.05).

CONCLUSIONS

Infusion of CD20 antibodies to the patients with active RA led to a clearly reduced plasma levels of predictors of CVD indicating that this treatment, apart from its anti-inflammatory properties, may reduce the risk for future CVD in RA.

Occurrence of ammonia-oxidizing Archaea in activated sludges of a laboratory scale reactor and two wastewater treatment plants

AIMS

Characterization of the ammonia-oxidizing archaea (AOA) community in activated sludge from a nitrogen removal bioreactor and wastewater treatment plants (WWTPs).

METHODS AND RESULTS

Three primer sets specific for ammonia mono-oxygenase alpha-subunit (amoA) were used to construct clone libraries for activated sludge sample from a nitrogen removal bioreactor. One primer set resulted in strong nonspecific PCR products. The other two clone libraries retrieved both shared and unique AOA amoA sequences. One primer set was chosen to study the AOA communities of activated sludge samples from Shatin and Stanley WWTPs. In total, 18 AOA amoA sequences were recovered and compared to the previous reported sequences. A phylogenetic analysis indicated that sequences found in this study fell into three clusters.

CONCLUSIONS

Different primers resulted in varied AOA communities from the same sample. The AOA found from Hong Kong WWTPs were closely similar to those from sediment and soil, but distinct from those from activated sludge in other places. A comparison of clone libraries between Shatin WWTP and bioreactor indicated the AOA community significantly shifted only after 30-day enrichment.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study confirmed the occurrence of AOA in a laboratory scale nitrogen removal bioreactor and Hong Kong WWTPs treating saline or freshwater wastewater. AOA communities found in this study were significantly different from those found in other places. To retrieve diverse AOA communities from environmental samples, a combination of different primers for the amoA gene is needed.

The WNT signalling pathway and diabetes mellitus

The WNT signalling pathway is involved in many physiological and pathophysiological activities. WNT ligands bind to Frizzled receptors and co-receptors (LDL receptor-related protein 5/6), triggering a cascade of signalling events. The major effector of the canonical WNT signalling pathway is the bipartite transcription factor beta-catenin/T cell transcription factor (beta-cat/TCF), formed by free beta-cat and one of the four TCFs. The WNT pathway is involved in lipid metabolism and glucose homeostasis, and mutations in LRP5 may lead to the development of diabetes and obesity. beta-Cat/TCF is also involved in the production of the incretin hormone glucagon-like peptide-1 in the intestinal endocrine L cells. More recently, genome-wide association studies have identified TCF7L2 as a diabetes susceptibility gene, and individuals carrying certain TCF7L2 single nucleotide polymorphisms could be more susceptible to the development of type 2 diabetes. Furthermore, beta-cat is able to interact with forkhead box transcription factor subgroup O (FOXO) proteins. Since FOXO and TCF proteins compete for a limited pool of beta-cat, enhanced FOXO activity during ageing and oxidative stress may attenuate WNT-mediated activities. These observations shed new light on the pathogenesis of type 2 diabetes as an age-dependent disease.

Cancer gene therapy with iCaspase-9 transcriptionally targeted to tumor endothelial cells

Antiangiogenic therapies have shown varying results partly because each tumor type secretes a distinct panel of angiogenic factors to sustain its own microvascular network. In addition, recent evidence demonstrated that tumors develop resistance to antiangiogenic therapy by turning on alternate angiogenic pathways when one pathway is therapeutically inhibited. Here, we test the hypothesis that expression of a caspase-based artificial death switch in tumor-associated endothelial cells will disrupt tumor blood vessels and slow down tumor progression irrespective of tumor type. Adenoviral vectors expressing inducible Caspase-9 (iCaspase-9) under transcriptional regulation with the endothelial cell-specific vascular endothelial growth factor receptor-2 (VEGFR2) promoter (Ad-hVEGFR2-iCaspase-9) induced apoptosis of proliferating human dermal microvascular endothelial cells (HDMECs), but not human tumor cells (UM-SCC-17B, head and neck squamous cell carcinoma; HepG2, hepatocellular carcinoma; PC-3, prostate adenocarcinoma; SLK, Kaposi's sarcoma; MCF-7, breast adenocarcinoma). Notably, apoptosis was dependent upon activation of iCaspase-9 with the dimerizer drug AP20187. Local delivery of Ad-hVEGFR2-iCaspase-9 followed by intraperitoneal injection of AP20187 ablated tumor microvessels and inhibited xenografted tumor growth in all tumor models evaluated here. We conclude that a cancer gene therapy strategy based on a transcriptionally targeted viral vector expressing an inducible caspase allows for selective and controlled ablation of microvessels of histopathologically diverse tumor types.

Double-negative regulatory T cells induce allotolerance when expanded after allogeneic haematopoietic stem cell transplantation

Double-negative (DN) regulatory T cells (Tregs) are specialized T lymphocytes involved in the down-modulation of immune responses, resulting in allotolerance after allogeneic haematopoietic stem cell transplantation (HSCT). Most of the properties of DN Tregs were identified in murine models, including the unique ability to suppress alloreactive syngeneic effector T cells in an antigen-specific manner via Fas/Fas-ligand interactions. We investigated the behaviour of DN Tregs following human allogeneic HSCT with regard to occurrence of graft-versus-host disease (GvHD) and restoration of T-cell receptor repertoire in a cohort of 40 patients. The frequency of DN Tregs and CD4/CD8 TCR repertoire was measured serially and at the time of diagnosis of GvHD by flow cytometry. Analysis demonstrated a positive correlation between degree of alloreactivity, as measured by grade of GvHD, and the number of variable beta chain (Vbeta) family expansions in both T-cell populations. We also found that a deficiency of DN Tregs was associated with an increased number of Vbeta family expansions, and most importantly, with the occurrence of GvHD. All individuals who demonstrated more than 1% DN Tregs did not develop GvHD, providing evidence that DN Tregs participate in peripheral tolerance to prevent GvHD when expanded after allogeneic HSCT.

Intense beam production of highly charged heavy ions by the superconducting electron cyclotron resonance ion source SECRAL

There has been increasing demand to provide higher beam intensity and high enough beam energy for heavy ion accelerator and some other applications, which has driven electron cyclotron resonance (ECR) ion source to produce higher charge state ions with higher beam intensity. One of development trends for highly charged ECR ion source is to build new generation ECR sources by utilization of superconducting magnet technology. SECRAL (superconducting ECR ion source with advanced design in Lanzhou) was successfully built to produce intense beams of highly charged ion for Heavy Ion Research Facility in Lanzhou (HIRFL). The ion source has been optimized to be operated at 28 GHz for its maximum performance. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. An innovative design of SECRAL is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. For 28 GHz operation, the magnet assembly can produce peak mirror fields on axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. During the commissioning phase at 18 GHz with a stainless steel chamber, tests with various gases and some metals have been conducted with microwave power less than 3.5 kW by two 18 GHz rf generators. It demonstrates the performance is very promising. Some record ion beam intensities have been produced, for instance, 810 e microA of O(7+), 505 e microA of Xe(20+), 306 e microA of Xe(27+), and so on. The effect of the magnetic field configuration on the ion source performance has been studied experimentally. SECRAL has been put into operation to provide highly charged ion beams for HIRFL facility since May 2007.

WBC changes as a pharmacodynamic marker of outcome in metastatic renal cell carcinoma (mRCC) patients (Pts) receiving sunitinib

5043

Background: Sunitinib is a VEGF, PDGF, c-Kit and FLT-3 inhibitor with significant anti-tumor activity in mRCC. Myelosuppression is a common side effect observed in mRCC pts treated with sunitinib. Thus, the association of myelosuppression with clinical outcome was investigated. Methods: All mRCC pts receiving sunitinib at The Cleveland Clinic Taussig Cancer Center with available data were investigated. White blood cell (WBC) and differential counts at baseline and day 28 of cycle 1 were collected. Peripheral blood mononuclear cell (PBMC) T helper 1 (Th1), T helper 2 (Th2) and T regulatory cell (Treg) numbers at baseline and day 28 of C1 were determined using flow cytometry. Hematologic parameters were analyzed as continuous variables and also dichotomized using a recursive partitioning algorithm. Fisher’s exact test was used to analyze categorical data, the log rank test was used to assess time to progression (TTP) and Spearman’s rank correlation was used to summarize associations between hematologic and immune parameters. Results: Sixty-seven pts were studied (75% male, median age 59 yrs). Objective responses (OR) included 2 complete and 35 partial responses (overall response rate 55%), with a median (m) TTP of 12.4 months. There was a significant reduction (end of C1 vs. baseline) in the absolute neutrophil count (ANC) (m decrease of 46.4%; p <0.001) and absolute monocyte count (m decrease of 41.3%; p<0.001), but not absolute lymphocyte count (m 6.6% decrease; p=0.5). A decrease in the ANC of =2.5K/uL compared to <2.5 K/uL was associated with improved OR (64% vs. 36%; p= .07) and TTP (m 20.6 months vs. 8 months; p=.003). Patients demonstrating a maximum lymphocyte count =1.2 K/uL at anytime during treatment compared to patients with a maximum lymphocyte count <1.2 K/uL also had a greater OR (64% vs. 25%, p=.02) and TTP (m 17.6 months vs. 4.2 months, p=.03). Changes in Treg number and Th1 and Th2 response bias of PBMC did not correlate with ANC/ lymphocyte changes or clinical outcome. Conclusions: Treatment with sunitinib produces significant neutropenia with minimal effects on total lymphocyte numbers. Changes in ANC and maximum lymphocyte count could represent a pharmacodynamic marker of clinical outcome for mRCC patients treated with sunitinib.

No significant financial relationships to disclose.

Is rituximab (R) the optimal therapeutic intervention (TI) for post-transplant lymphoproliferative disorder (PTLD) following solid organ transplant (SOT)?

8074

Background: PTLD is a rare, often fatal, complication of SOT. Most are derived from CD20+ B-cells. Historically, patients (pts) received a variety of TIs ranging from decreased immunosuppression to chemotherapy (CT). Based on promising initial study results, most pts now receive rituximab (R) without CT as part of 1st TI. Methods: We searched the Cleveland Clinic pathology archives for SOT pts, who were diagnosed with PTLD between 1987 and 2006; reviewed the medical records; extracted clinical information and outcomes; and analyzed the data by Cox proportional univariate and multivariate analyses. Results: We identified 55 SOT pts (heart, 18; lung, 16; kidney 14; liver, 6; pancreas, 1), who were diagnosed with PTLD at median age 47 years (range 7–66). The median time from SOT to PTLD was 1.7 years (range .2–20.9). 1st TI (usually >1) included “complete” resection (4), decreased immunosuppresion (53), acyclovir or ganciclovir (28), interferon (4), radiation therapy (6), CT (12), and/or R (17). Response to 1st TI was CR (30) or PR (10). The median follow-up among surviving pts is 5.0 years (range .1–11.4). 29 (including 5 CT and 5 R) pts have died; only 2 CT but all 5 R pts died from PTLD. On univariate analysis, younger age+, <2 prior rejection episodes+*, PS <2+*, normal LDH+*, <2 extranodal sites+, lower IPI+*, >1 1st TI+, and 1st TI with CT* were associated with an improved overall survival (OS)+ and/or PTLD-specific survival (PSS)*. On multivariate analysis, only PS <2 (HR 0.04 [CI 0.01–0.14], p<0.001) and >1 1st TI (HR 0.43 [CI 0.19–0.97], p=0.041) were associated with improved OS while PS <2 (HR 0.04 [0.01- 0.16], p<0.001) and 1st TI with CT (HR 0.19 [CI 0.04–0.84], p<0.028) were associated with improved PSS. Conclusions: A significant minority of SOT pts that receive R without CT as part of 1st TI still die from PTLD. PS is the most important predictor of outcome. In conjunction with the improved survival observed in de novo B-cell NHL pts treated with R+CT (compared to CT alone), this retrospective analysis suggests that some SOT PTLD pts should receive R+CT as part of 1st TI.

No significant financial relationships to disclose.

Irinotecan and bevacizumab in progressive primary brain tumors: The Cleveland Clinic experience

2077

Background: High-grade gliomas are generally resistant to modern chemotherapy. In the case of glioblastoma multiforme, median overall survival has been less than 12 months and progression free survival of less than 4 months. For patients with recurrent GBMs, the 6 month progression free survival is 15–20%. The combination of irinotecan and bevacizumab is an active regimen in the treatment of this disease. Herein we report the experiences with this regimen at our institution with the objective of identifying a therapy with a better outcome than historical results. Methods: Single institutional, retrospective review of 27 patients with recurrent or progressive high grade gliomas treated at the Cleveland Clinic Brain Tumor Institute from 7/2005 through 10/2006. Patients had progressed on at least one prior chemotherapy. Patients with prior irinotecan or bevacizumab were excluded. Patients were analyzed on an intention-to-treat basis, and outcomes estimated by the Kaplan-Meier method. Results: The median age of the group was 46 years (range 5–69). The median number of prior therapies was 2 (range 1–10). Twenty of 27 patients have progressed (74%), and 11 of 27 patients have died (41%). Kaplan-Meier estimates for outcomes are summarized in the table . Progression-free survival at 6 months is 46 %, with median of 5.1 months. Overall survival at 6 months is 84%, with median of 12.6 months. In 7 patients, treatment was terminated early prior to progression. Significant toxicities include: one patient who developed hematuria, one patient with deep venous thrombosis and one patient who experienced intracranial hemorrhage. Conclusions: Our experience suggests that the combination of irinotecan and bevacizumab improves the 6-month progression-free survival when compared to historical figures. The rate of severe toxicities is consistent with prior reports and mandates careful selection of patients. Further randomized, phase 3 studies should be done to validate these results.

[Table: see text]

No significant financial relationships to disclose.

Proteomic identification of potential protein markers in cerebrospinal fluid of GBS patients

Increased protein level in the cerebrospinal fluid (CSF) is a characteristic of patients with Guillain-Barré syndrome (GBS), an acute inflammatory autoimmune disorder in the peripheral nervous system (PNS). However, the molecular mechanisms underlying the disease remain poorly understood and so far no reliable disease-related markers are available. By comparing the CSF proteome of GBS patients with control subjects suffering from other neurological disorders, it may be possible to identify proteins that involve in the disease process and thus to study the pathogenesis of GBS. We used two-dimensional difference gel electrophoresis (2D DIGE) technique, in combination with matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS), to determine the abnormal CSF proteins in GBS patients. Our data showed that the levels of six proteins and their isoforms in CSF were significantly altered in GBS patients compared with controls. Haptoglobin, apolipoprotein A-IV and PRO2044 (unnamed protein) were considerably increased in the CSF of GBS patients, whereas transthyretin, apolipoprotein E and fibrinogen were considerably decreased. We concluded that these six proteins may be involved in the pathogenesis of GBS and call for further studying the role of these proteins in the pathogenesis of the disease.

Increased risk of chronic obstructive pulmonary diseases in coke oven workers: interaction between occupational exposure and smoking

BACKGROUND

Coke oven workers are regularly exposed to coke oven emissions (COE) and may be at risk of developing lung diseases. There is limited evidence for the link between exposure to COE and chronic obstructive pulmonary diseases (COPD). The aim of this study was to explore the dose-response relationship between COE exposure and COPD and to assess the interaction with cigarette smoking.

METHODS

Seven hundred and twelve coke oven workers and 211 controls were investigated in southern China. Benzene soluble fraction (BSF) concentrations as a surrogate of COE were measured in representative personal samples and the individual cumulative COE exposure level was quantitatively estimated. Detailed information on smoking habits and respiratory symptoms was collected and spirometric tests were performed.

RESULTS

The mean BSF levels at the top of two coking plants were 743.8 and 190.5 microg/m3, respectively, which exceed the OSHA standard (150 microg/m3). After adjusting for cigarette smoking and other risk factors, there was a significant dose-dependent reduction in lung function and increased risks of chronic cough/phlegm and COPD in coke oven workers. The odds ratio for COPD was 5.80 (95% confidence interval 3.13 to 10.76) for high level cumulative COE exposure (> or =1714.0 microg/m3-years) compared with controls. The interaction between COE exposure and smoking in COPD was significant. The risk of COPD in those with the highest cumulative exposure to COE and cigarette smoking was 58-fold compared with non-smokers not exposed to COE.

CONCLUSION

Long term exposure to COE increases the risk of an interaction between COPD and cigarette smoking.

Antifouling properties of 10beta-formamidokalihinol-A and kalihinol A isolated from the marine sponge Acanthella cavernosa

Many soft-bodied sessile marine invertebrates such as sponges and soft corals defend themselves against fouling directly through the production of antifouling compounds, or indirectly through regulating the epibiotic microbes that affect larval settlement. In this study, 10beta-formamidokalihinol-A and kalihinol A were isolated and purified from the marine sponge Acanthella cavernosa (Dendy). The results indicated that both compounds inhibited the growth of bacteria isolated from the natural environment whereas kalihinol A suppressed larval settlement of a major fouling polychaete, Hydroides elegans with an EC50 of 0.5 microg ml(-1). Kalihinol A was incorporated in Phytagel that was exposed to the bacterial consortia in natural seawater for biofilm formation. Biofilms that developed on the Phytagel surfaces were analysed for bacterial abundance and bacterial species composition using a DNA fingerprinting technique, terminal restriction fragment length polymorphism (T-RFLP). The results showed that kalihinol A only slightly reduced bacterial abundance (t-test, p = 0.0497), but modified the bacterial species composition of the biofilms. Inhibition of H. elegans larval settlement was observed when biofilms developed under the influence of kalihinol A were exposed to larvae, suggesting that compounds like kalihinol A from the sponge A. cavernosa may change bacterial community composition on the sponge surface, which in turn, modulates larval settlement of fouling organisms.

Biomarkers of cadmium and arsenic interactions

Advances in proteomics have led to the identification of sensitive urinary biomarkers of renal dysfunction that are increasingly used in toxicology and epidemiology. Recent animal data show that combined exposure to inorganic arsenic (As) and cadmium (Cd) gives rise to more pronounced renal toxicity than exposure to each of the agents alone. In order to examine if similar interaction occurs in humans, renal dysfunction was studied in population groups (619 persons in total) residing in two metal contaminated areas in China: mainly a Cd contaminated area in Zhejiang province (Z-area) and mainly a As contaminated area in Guizhou province (G-area). Nearby control areas without excessive metal exposure were also included. Measurements of urinary beta(2)-microglobulin (UB2MG), N-acetyl-beta-glucosaminidase (UNAG), retinol binding protein (URBP) and albumin (UALB) were used as markers of renal dysfunction. Urinary Cd (UCd) and total As (UTAs) were analyzed by graphite-furnace atomic absorption spectrometry. Urinary inorganic As and its mono- and di-methylated metabolites (UIAs) were determined by Hydride generation. Results. As expected, the highest UCd values occurred in Z-area (Geometric mean, GM 11.6 microg/g crea) while the highest UTAs values occurred in G-area (GM = 288 microg/g crea). Statistically significant increases compared to the respective control area were present both for UTAs, UCd and for UB2MG, UNAG and UALB in Z-area as well as in G-area. UIAs was determined only in Z area. In G-area, there was a clear dose-response pattern both in relation to UTAs and UCd for each of the biomarkers of renal dysfunction. An interaction effect between As and Cd was demonstrated at higher levels of a combined exposure to As and Cd enhancing the effect on the kidney. In Z-area an increased prevalence of B2MG-uria, NAG-uria and ALB-uria was found in relation to UCd, but no relationship to UTAs was found. A statistically significant relationship between UIAs and UB2MG was found among women in this area and an interaction between As and Cd was indicated for B2MG. Conclusion. The present studies, which employed sensitive biomarkers of renal dysfunction, give support to the idea that human co-exposure to Cd and inorganic arsenic gives rise to more pronounced renal damage than exposure to each of the elements alone, but further studies are needed to establish and clarify this interaction.

Anchoring and structural transitions as a function of molecular length in confined liquid crystals

Using deuteron nuclear magnetic resonance to study liquid crystals confined to cylindrical pores, an anchoring transition has been found. The transition exhibits an unexpected sharp dependence of the anchoring strength on cyanobiphenyl liquid crystal molecular length. A structural transition from a parallel axial to a planar radial configuration occurs due to an anchoring transition from planar to weakly homeotropic orientation at the walls. The anchoring strength is at a minimum near the decylcyanobiphenyl (10CB) liquid crystal length. Long chain liquid crystal configurations depend on thermal cycling and on the equilibrium atmosphere leading to a bistable SmA structure. Orientational order wetting in the isotropic phase also depends on molecular length.