How Modifiable Are Modifiable Dementia Risk Factors? A Framework for Considering the Modifiability of Dementia Risk Factors

Many risk factors for dementia, identified from observational studies, are potentially modifiable. This raises the possibility that targeting key modifiable dementia risk factors may reduce the prevalence of dementia, which has led to the development of dementia risk reduction and prevention strategies, such as intervention trials or dementia prevention guidelines. However, what has rarely been considered in the studies that inform these strategies is the extent to which modifiable dementia risk factors can (1) be identified by individuals, and (2) be readily modified by individuals. Characteristics of modifiable dementia risk factors such as readiness of identification and targeting, as well as when they should be targeted, can influence the design, or success of strategies for reducing dementia risk. This review aims to develop a framework for classifying the degree of modifiability of dementia risk factors for research studies. The extent to which these modifiable dementia risk factors could be modified by an individual seeking to reduce their dementia risk is determined, as well as the resources that might be needed for both risk factor identification and modification, and whether modification may be optimal in early-life (aged <45 years), midlife (aged 45-65 years) or late-life (aged >65 years). Finally, barriers that could influence the ability of an individual to engage in risk factor modification and, ultimately, dementia risk reduction are discussed.

Protocol of a Phase II Randomized, Multi-Center, Double-Blind, Placebo-Controlled Trial of S-Adenosyl Methionine in Participants with Mild Cognitive Impairment or Dementia Due to Alzheimer's Disease

BACKGROUND

S-adenosyl methionine (SAMe) is a pivotal metabolite in multiple pathways required for neuronal homeostasis, several of which are compromised in Alzheimer's disease (AD). Correction of the SAMe deficiency that is characteristic of the AD brain may attenuate or prevent pathological processes driving AD-associated neurodegeneration including aberrant tau hyperphosphorylation and DNA hypomethylation.

OBJECTIVES

The primary aim is to test the hypothesis that daily treatment with 400 mg oral SAMe for 180 days will lead to a greater reduction from baseline in plasma levels of p-tau181 compared to placebo in patients with mild cognitive impairment or dementia due to AD.

DESIGN, SETTING, PARTICIPANTS

This is a phase II, randomized, multi-center, double-blind, placebo-controlled trial among 60 participants with mild cognitive impairment or dementia due to AD. Participants will be randomized in a 1:1 ratio to receive either SAMe or matching placebo, to be taken as an adjunct to their AD standard of care.

MEASUREMENTS AND RESULTS

The primary outcome is change in plasma p-tau181 concentration between baseline and following 180 days of treatment, which will be compared between the active and placebo group. Secondary outcomes are the safety of SAMe administration (incidence of serious adverse events), change from baseline in cognitive performance (as measured by the Repeatable Battery for the Assessment of Neuropsychological Status), and epigenetic changes in DNA methylation.

CONCLUSION

Demonstration of effective and safe lowering of plasma p-tau181 with SAMe in this phase II trial would pave the way for an exciting field of translational research and a larger phase III trial.

Longitudinal Cognitive Decline in Patients With Mild Cognitive Impairment or Dementia Due to Alzheimer's Disease

Sensitive cognitive assessments accurately detect and track cognitive decline in Alzheimer's disease. The Cogstate battery was used to measure cognitive change in cognitively normal participants and in individuals with mild cognitive impairment and mild Alzheimer's disease enrolled in the Australian Imaging, Biomarker and Lifestyle Rate of Change Substudy. Over 18 months, verbal episodic memory performance declined for mild cognitive impairment and mild Alzeheimer's disease groups when compared to cognitively normal participants. Frequent assessments of episodic memory may facilitate early detection of cognitive decline due to Alzheimer's disease.

Bactericidal and cytotoxic activity of a diarylheptanoid (etlingerin) isolated from a ginger (Etlingera pubescens) endemic to Borneo

AIMS

The aim of this study was to investigate the antimicrobial activities of Etlingera pubescens, and to isolate and identify the antimicrobial compound.

METHODS AND RESULTS

The crude extracts of E. pubescens were obtained through methanol extraction, and evaluated for antimicrobial activities. From this extract, 1,7-bis(3,4-dihydroxyphenyl)heptan-3-yl acetate (etlingerin) was isolated. When compared to curcumin (a compound with a similar chemical structure), etlingerin showed twofold lower minimum inhibitory concentration values while also being bactericidal. Through time kill assay, etlingerin showed rapid killing effects (as fast as 60 min) against the Gram-positive bacteria (Staphylococcus aureus ATCC 43300 and Bacillus subtilis ATCC 8188). Further assessment revealed that etlingerin caused leakage of intracellular materials, therefore suggesting alteration in membrane permeability as its antimicrobial mechanism. Cytotoxicity study demonstrated that etlingerin exhibited approximately 5- to 12-fold higher IC50 values against several cell lines, as compared to curcumin.

CONCLUSIONS

Etlingerin isolated from E. pubescens showed better antibacterial and cytotoxic activities when compared to curcumin. Etlingerin could be safe for human use, though further cytotoxicity study using animal models is needed.

SIGNIFICANCE AND IMPACT OF THE STUDY

Etlingerin has a potential to be used in treating bacterial infections due to its good antimicrobial activity, while having potentially low cytotoxicity.

Characterisation of the action mechanism of a Lactococcus-specific bacteriocin, lactococcin Z

Lactococcin Z is a novel Lactococcus-specific bacteriocin produced by Lactococcus lactis QU 7 that shares 55.6% identity with lactococcin A. To identify the receptor targeted by lactococcin Z, several lactococcin Z-resistant mutants were generated from the sensitive strain, L. lactis IL1403. The resistant mutants showed difficulties in utilising mannose and glucose as sole carbon sources, contrary to their pattern of growth in the presence of galactose as a sole carbon source. Mutations were found in the ptnC and ptnD genes of lactococcin Z-resistant mutants, which encode the mannose phosphotransferase system (Man-PTS) components, IIC and IID, respectively; therefore, IIC and IID are proposed as potential receptors employed by lactococcin Z and are the same receptors targeted by lactococcin A. Both lactococcins A and Z share a high percentage identity in their N-termini regions in contrast to their C-termini that show less similarity; this may explain the difference in their action mechanisms as well as the lack of cross-immunity between them. Although lactococcin Z showed bactericidal activity, it neither dissipated membrane potential nor formed pores on the membranes of sensitive cells, in sharp contrast to the pore-forming lactococcin A.

Investigation on the antimicrobial activities of gingers (Etlingera coccinea (Blume) S.Sakai & Nagam and Etlingera sessilanthera R.M.Sm.) endemic to Borneo

AIMS

To investigate the antimicrobial properties of Etlingera coccinea and Etlingera sessilanthera and to isolate and identify the antimicrobial compounds.

METHODS AND RESULTS

Extracts were obtained via sequential solvent extraction method using hexane, dichloromethane, ethyl acetate, methanol and water. Antimicrobial activity testing was done using broth microdilution assay against 17 strains of bacteria. The leaf hexane extract of E. coccinea and rhizome hexane extract of E. sessilanthera showed best antimicrobial activities, with minimum inhibitory concentration (MIC) values ranging from 0·016 to 1 mg ml-1 against Gram-positive bacteria. From these active extracts, two antimicrobials were isolated and identified as trans-2-dodecenal and 8(17),12-labdadiene-15,16-dial with MIC values ranging from 4 to 8 μg ml-1 against Bacillus cereus, Bacillus subtilis and Staphylococcus aureus.

CONCLUSION

Etlingera coccinea and E. sessilanthera demonstrated good antimicrobial activities against clinically relevant bacteria strains. The antimicrobial compounds isolated showed low MIC values, hence suggesting their potential use as antimicrobial agents.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study is the first to identify the potent antimicrobials from these gingers. The antimicrobials isolated could potentially be developed further for use in treatment of bacterial infections. Also, this study warrants further research into other Etlingera species in search for more antimicrobial compounds.

Abstract P4-02-12: Tomosynthesis as an alternative to magnetic resonance imaging (MRI) in assessing invasive lobular carcinoma (ILC) multifocality

Introduction

Invasive lobular carcinoma is associated with a higher rate of multifocality than other types of breast cancer. Breast MRI is commonly performed in patients diagnosed with ILC to assess for additional disease prior to formulating a management plan. MRI may be both time consuming and costly and can delay treatment.

Recently tomosynthesis has become an adjunct in the assessment and diagnosis of breast cancer. It is readily available at the time of mammography therefore providing information at the one stop clinic. We proposed that it may be possible to use tomosynthesis to assess for multifocality in ILC in place of MRI.

Method

A retrospective review of all cases of ILC diagnosed at a single regional screening unit over a 3-year period was performed. Patients having surgery as primary treatment were included. Ninety-eight patients were identified, 29 having both MRI and tomosynthesis in addition to mammography and ultrasound scan as part of their assessment. Histological data was used to compare the two imaging modalities. Bland and Altman limits of agreement analysis was performed to assess the difference between MRI and tomosynthsis in these patients. An acceptable difference (the difference in values that is unlikely to influence management) was set at 5mm.

Results

The Bland and Altman limits of agreement analysis produced three graphs to demonstrate the difference between MRI and Tomosynthesis, MRI and histology size and Tomosynthesis and histology size. It shows that the average difference between MRI and Tomosynthesis = 3.8mm (95% limits of agreement: –19.2 to 26.8mm). The percentage of 'acceptable' differences (defined as ≤ 5mm) was 72% for MRI and tomosynthesis suggesting that there is good concordance between the two. Tumours measuring &gt;30mm on MRI are perceived as smaller under Tomosynthesis.

The analysis demonstrated the average difference between MRI and histology values is -1.3 mm (95% limits of agreement = – 33.2 to 30.6)compared with an average difference between Tomosynthesis and histology of -5.1 mm (95% limits of agreement = – 27.7 to 17.5). The percentage of 'acceptable' differences (defined as ≤ 5 mm) was 48% for both MRI vs histology and Tomosynthesis vs histology, suggesting that neither is superior when compared to final histology results.

In three patients there were multifocal cancers identified on histology that had not been detected by any imaging modality. In one patient there were MRI images that suggested a second tumour which was not present on histological examination. The same is true for a patient diagnosed with a second cancer identified by tomosynthesis but not found in the specimen. A third patient was diagnosed with a second tumour by both image modalities but again not present on histology. In one case tomosysnthesis detected a true second cancer that was not identified on MRI.

Conclusion

We believe this preliminary study suggests that tomosynthesis is equivocal to MRI for assessing multifocality in ILC. If confirmed the implications would be a shorter investigative pathway with reduced delays and costs. A larger mutli-centre trial to assess the use of tomosynthesis to replace MRI in patients with ILC is warranted.

Citation Format: Holt RE, Topps A, Lim YY, Gandhi A. Tomosynthesis as an alternative to magnetic resonance imaging (MRI) in assessing invasive lobular carcinoma (ILC) multifocality [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-02-12.

A randomised pilot study comparing 13 G vacuum-assisted biopsy and conventional 14 G core needle biopsy of axillary lymph nodes in women with breast cancer

AIM

To compare the acceptability, safety, and feasibility of vacuum-assisted biopsy (VAB) and core needle biopsy (CNB) of axillary lymph nodes in women with breast cancer.

MATERIALS AND METHODS

This parallel, non-blinded, randomised study was approved by the National Research Ethics Service. Following written informed consent, women with abnormal appearing axillary lymph nodes and radiologically malignant breast masses were randomised 1:1 to lymph node sampling under local anaesthetic with either 14 G CNB or 13 G VAB in a single UK centre. Primary outcomes were study uptake rate and patient willingness to undergo a repeat procedure if necessary. Procedure duration, immediate and post-procedure pain scores, diagnostic yield, complications, and surgical histopathology were recorded.

RESULTS

Ninety-five women were approached; 81 (85.3%) consented and were randomised. Forty underwent CNB; 40 underwent VAB; one was excluded. Median age was 57 years. The median procedure time was 2 minutes for both techniques. The median number of samples obtained was three for CNB and four for VAB. Median pain scores for the procedure and first 3 days were 1/10 and 1/10 for CNB and 1/10 and 2/10 for VAB (p=0.11 and 0.04). More women were prepared to undergo repeat CNB compared to VAB, but the difference was not significant (38/39 versus 33/39; p=0.11). Two patients developed a haematoma after VAB. One CNB and six VABs failed to yield adequate tissue (p=0.11), but the sensitivity was similar at 79% and 78%.

CONCLUSION

Study uptake was high. Acceptability of the two procedures was similar, but VAB was associated with more post-procedure pain. The sensitivity appears to be similar.

APOE and BDNF polymorphisms moderate amyloid β-related cognitive decline in preclinical Alzheimer's disease

Accumulation of β-amyloid (Aβ) in the brain is associated with memory decline in healthy individuals as a prelude to Alzheimer's disease (AD). Genetic factors may moderate this decline. We examined the role of apolipoprotein E (ɛ4 carrier[ɛ4(+)], ɛ4 non-carrier[ɛ4(-)]) and brain-derived neurotrophic factor (BDNF(Val/Val), BDNF(Met)) in the extent to which they moderate Aβ-related memory decline. Healthy adults (n=333, Mage=70 years) enrolled in the Australian Imaging, Biomarkers and Lifestyle study underwent Aβ neuroimaging. Neuropsychological assessments were conducted at baseline, 18-, 36- and 54-month follow-ups. Aβ positron emission tomography neuroimaging was used to classify participants as Aβ(-) or Aβ(+). Relative to Aβ(-)ɛ4(-), Aβ(+)ɛ4(+) individuals showed significantly faster rates of cognitive decline over 54 months across all domains (d=0.40-1.22), while Aβ(+)ɛ4(-) individuals showed significantly faster decline only on verbal episodic memory (EM). There were no differences in rates of cognitive change between Aβ(-)ɛ4(-) and Aβ(-)ɛ4(+) groups. Among Aβ(+) individuals, ɛ4(+)/BDNF(Met) participants showed a significantly faster rate of decline on verbal and visual EM, and language over 54 months compared with ɛ4(-)/BDNF(Val/Val) participants (d=0.90-1.02). At least two genetic loci affect the rate of Aβ-related cognitive decline. Aβ(+)ɛ4(+)/BDNF(Met) individuals can expect to show clinically significant memory impairment after 3 years, whereas Aβ(+)ɛ4(+)/BDNF(Val/Val) individuals can expect a similar degree of impairment after 10 years. Little decline over 54 months was observed in the Aβ(-) and Aβ(+) ɛ4(-) groups, irrespective of BDNF status. These data raise important prognostic issues in managing preclinical AD, and should be considered in designing secondary preventative clinical trials.

Inhibitory effect of tianeptine on catagen induction in alopecia areata-like lesions induced by ultrasonic wave stress in mice

BACKGROUND

Alopecia areata (AA) is characterized by rapid and complete hair loss in one or multiple areas of the scalp. Stress is an important triggering factor in AA.

AIM

To identify the inhibitory effect of tianeptine on catagen induction in C57BL/6 mice with AA-like lesions induced by ultrasonic wave stress (UWS).

METHODS

The mice were divided into four groups. Group 1 received oral tianeptine before and after UWS; group 2 received oral tianeptine only after UWS; group 3 was given UWS treatment only; and group 4 (negative control group) was not given any treatment. Phototrichigraphy and dermatoscopy were used for assessment. Histological analysis was performed using haematoxylin and eosin, toluidine blue, Masson trichrome and Verhoeff-van Gieson stains. Immunohistochemical analysis was also performed. The level of apoptosis and expression of neuropeptides in the skin were assessed by terminal deoxynucleotidyl transferase dUTP nick end labelling and immunofluorescence assays.

RESULTS

Mice in group 1 had an increased rate of hair growth and greater hair-shaft thickness compared with mice in groups 2 and 3. In addition, mice in group 1 had a higher number of anagen hair follicles, increased synthesis of collagen and elastic fibres, decreased mast-cell degranulation, reduction in cell apoptosis in hair follicles, and recovery of vitamin D receptor expression. Expression of neuropeptides (substance P, calcitonin gene-related peptide) was not altered.

CONCLUSIONS

Tianeptine might play a role in suppressing catagen induction in a stress-induced AA mouse model.

Abstract P6-06-06: The therapeutic potential and hazard of exposure to Cerbera odollam leaf extracts

Background: Despite its significance in leading to the reduction of breast cancer mortality rates, therapeutic regiments for breast cancer still face two major problems: (1) the heterogeneity of the tumours and (2) the prevalence of drug resistance towards anti-estrogen therapy. The leaf extracts from Cerbera odollam were screened for active compounds with the potential to overcome these problems.

Methods: Hormone responsive (MCF7) and hormone-independent cell lines (MDA-MB-231) were treated with the fractionated methanolic extracts of C. odollam followed by analyses on cell cycle perturbations and gene expression changes resulting from the treatment. The stated analyses were performed by flow cytometry, semi-quantitative RT-PCR, western blotting and immunofluorescence. The active fraction was identified, upon which HPLC separation was performed to identify the putative active compound.

Results: Initial experiments revealed that a fractionated extract contains a potent cytostatic agent which is active towards hormone-responsive but not hormone-independent breast cell lines [the Estrogen Receptor-alpha (ERα) positive MCF7 cells remained static in growth for 10 days]. Comparison of the effects of the active and inactive fractions on MCF7 cells revealed key differences in cell growth and expression of ERα and its downstream regulated genes. The active compound was identified to be neriifolin (a cardiac glycoside) which also exhibited prolonged cytostatic effects (for 10 days upon treatment of 18.7 nM) similar to the active fraction. Gene expression analyses suggested that the ERα/Estrogen (E2) regulatory pathway and p53-dependent p21WAF1 transactivaton could be the cellular targets.

Conclusion: Although neriifolin could be a potential drug for breast cancer treatment, its severity in down regulation of the ERα/E2 regulatory pathway which is critical during female development indicates the potential health hazard from our exposure to C. odollam. We are now focusing on establishing assay to evaluate whether neriifolin could cause drug resistance (similar to tamoxifen) by silencing ERα expression through hypermethylation of the ERα promoter.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-06-06.

Providing diabetes patients with personalized written clinical information in the diabetes outpatient clinic: a pilot study

AIM

To explore the impact of sharing personalized written clinical information with diabetes outpatients on patient involvement in the clinical consultation.

METHODS

One hundred and six patients attending diabetes outpatient clinics for a review visit were allocated to receive either a patient information sheet containing personalized clinical information (prior to their consultation) or no information sheet. Both groups were compared by observing the number of patients raising any of the 17 topics included on the patient information sheet, the number of topics raised by each individual and the proportion of the total consultation time in which the patient was involved in conversation. A mean patient score was calculated by summing the number of topics raised by each patient.

RESULTS

Patients in the intervention group were more likely to initiate a conversation on all 17 topics during the consultation than those in the control group. These differences were significant for all topics except glycated haemoglobin (HbA(1c)) and diabetes complications. The mean patient score was significantly higher in the intervention group (5 vs. 1, P < 0.005), with the highest patient score in the intervention group being 14 compared with 4 in the control group. The mean patient conversation time for the intervention group was significantly longer than for the control group (6.34 vs. 3.34 min, P < 0.01). The overall consultation time did not significantly differ between groups.

CONCLUSIONS

Providing patients with personalized clinical information in a routine clinical setting can increase patients' involvement in the consultation without significantly increasing the length of the consultation.

Factors associated with poor academic achievement among urban primary school children in Malaysia

INTRODUCTION

The aim of this study was to identify factors associated with poor academic achievement during the early school years.

METHODS

This was a cross-sectional study of urban Primary Two children. Sociodemographic and medical data were obtained from questionnaires and interviews. Achievement was based on marks obtained in the core subjects of the Primary One examination. All students underwent the Raven's Standard Progressive Matrices test as a general measure of cognitive ability, audiometry and visual tests, and standardised measurements of weight and height.

RESULTS

Out of 1,470 eligible children, 206 (14 percent) had poor academic achievement. Of the 919 children who participated in the study, 111 (12.1 percent) had poor achievement compared with 95 (17.2 percent) of the 551 non-participants. Using logistic regression analysis, the factors that were found to be independently associated with poor academic achievement were lower mean Raven scores (p-value is less than 0.001), lower mean socioeconomic status scores (p-value is less than 0.001), larger sibship size (p-value is 0.031), male gender (odds ratio [OR] 1.7; 95 percent confidence interval [CI] 1.1-2.65) and a history of prematurity (OR 14; 95 percent CI 2-97.8).

CONCLUSION

Cognitive ability, gender, prematurity and social factors contribute to poor academic achievement during the early school years. The higher proportion of poor achievers among non-participants warrants further attention.

Diagnostic and interventional radiology workload in acute pancreatitis in an ITU/HDU setting

AIM

To determine the impact on diagnostic and interventional radiology services when imaging patients with severe pancreatitis on intensive therapy (ITU) and high-dependency units (HDU) in a tertiary referral centre.

MATERIAL AND METHODS

One hundred and sixty-nine patients admitted to ITU/HDU over a 9-year period (1996-2004) with severe acute pancreatitis were reviewed. There were 109 admissions to the ITU with length of stay of 0.2-81.6 days (mean 19.7 days) and 92 admissions to the HDU with length of stay of 0.4-12.8 days (mean 4.9 days).

RESULTS

One hundred and seventy-nine computed tomography (CT) and 199 ultrasound (US) examinations were performed on the ITU patients in whom interventional procedures were required in 24% of patients undergoing CT examinations and in 32% of patients undergoing US. Sixty-two CT and 60 US examinations were performed in the HDU patients. The percentage of interventional procedures performed in HDU patients was similar to that in ITU patients, i.e., 18% CT-guided and 35% US-guided. The proportion of patients that underwent investigations and interventions has gradually increased over the period of the study. Inpatient mortalities were 29% and 5.4%, respectively, in ITU and HDU patients.

CONCLUSIONS

This study demonstrates the huge input and increasing workload undertaken by radiologists when managing patients with severe acute pancreatitis in an ITU/HDU setting. We believe this is partly due to the implementation of the British Society of Gastroenterology (BSG) guidelines on management of acute pancreatitis and partly due to the more intensive non-surgical management offered to patients being referred into a specialist tertiary referral unit.

Effects of aminoacids on the autooxidation of 3,5-di-tert-butylcatechol in the presence of surface-active copper(II) complexes

The rate of autooxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) in the presence of micelles formed from mixing equal concentrations of [Cu(C(12)-tmed)Br(2)] (where C(12)-tmed is N,N,N'-trimethyl-N'-dodecylethylenediamine) and several amino acids has been investigated. It was found that the rate in air-saturated solution is very much dependent on pH, which affects the availability of copper(II) coordination site for the catechol and the degree of micellization. At a given pH, the rates in [Cu(C(12)-tmed)Br(2)] micellar media are greatly enhanced in the presence sodium halide.

Expression of glucose oxidase by using recombinant yeast

The glucose oxidase gene (GO) of Aspergillus niger was cloned into the yeast shuttle vector YEp352 with combinations of various promoters and terminators, and then used to transform Saccharomyces cerevisiae. Expressed GO was successfully secreted into culture medium due to the presence of the intrinsic signal peptide of GO. Four different promoters fused to GO were tested: bidirectional galactose dehydrogenase 1 and 10 (GAL1, GAL10) promoters, glyceraldehyde-3-phosphate dehydrogenase (GPD) promoter and an yeast hybrid ADH2-GPD promoter consisting of alcohol dehydrogenase II (ADH2) and GPD promoter. The intrinsic terminator of GO as well as the GAL7 terminator were also compared for better production of GO. Deletion of most of the terminating region from GO yielded only a slight amount of GO while the presence of either terminator greatly increased GO production. The GAL10 promoter produced the least amount of GO, GAL1 and GPD promoters were moderate, and the ADH2-GPD hybrid promoter was the best among all tested. However, the hybrid promoter was tightly regulated by the presence of an excess amount of either glucose or ethanol, and it appeared that 2% glucose and 1. 5% ethanol supplement was the best concentration for GO production. It was possible to produce 260 IU ml(-1) of GO, an equivalent of 5 g l(-1), under the presence of 2% glucose and 1.5% ethanol. UV mutagenesis of a recombinant S. cerevisiae was also applied and it further increased the yield of GO to 460 IU ml(-1) under the presence of 2% glucose and 1.5% ethanol without any changes in cell growth. Corn steep liquor which is commonly used in bioindustry is a good alternative substrate for high priced glucose for the hybrid promoter and suggests a cost effective means for commercial mass production of GO using recombinant yeast.

Effects of Aminocarboxylate Ligands of Surface Active Copper(II) Complexes on the Hydrolysis of p-Nitrophenyldiphenylphosphate

The rate of hydrolysis of p-nitrophenyldiphenylphosphate in the presence of micellized [Cu(C(12)tmed)(L)](+) where C(12)tmed is N,N,N'-trimethyl-N'-dodecylethylenediamine and L is the anion part of the amino acid has been investigated. It was found that the observed maximum rate obtained under the excess surfactant over the substrate condition depends very much on the ability of the amino acid ligand to form a mixed-chelate complex with the [Cu(C(12)tmed)](2+) moiety. In general, a chelating ligand with better coordination ability gives a slower rate because of the reduction in the supply of Cu-OH nucleophile in the micelle. Copyright 1999 Academic Press.

Interaction of Aqueous Solutions of a Surface Active Copper(II) Complex with Several Common Surfactants

Micellar properties of binary mixed surfactants of a surface active mixed copper(II) chelate, [Cu(C12-tmed)(acac)Cl] (where C12-tmed is N,N,N'-trimethyl-N'-dodecylethylenediamine) with three common surfactants, viz. sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and octaethylene glycol monododecyl ether (C12E8), were investigated by surface tensiometry, ESR, and UV-visible absorption techniques. The surface tension data were treated with Rubingh's method for mixed micelle formation and Rosen's method for mixed monolayer formation at the aqueous solution/air interface. It was found that in the mixed micelle there is strong attractive interaction between cationic copper surfactant and anonic dodecyl sulfate while there is almost ideal mixing between copper surfactant and CTAB and C12E8. From the ESR and UV-visible studies, a mixed block-type arrangement of head groups is proposed. Copyright 1997 Academic Press. Copyright 1997Academic Press

Spectrophotometric and Electron Spin Resonance Studies on Acetylacetonato(N,N,N',N'-Tetra-Methylethylenediamine)Copper(II) Tetraphenylborate in Various Solvents

1 : 1 equilibrium constants for the Lewis acid-base interaction between acetylacetonato- (N, N, N', N'- tetramethylethylenediamine )copper(II) tetraphenylborate and tetrahydrofuran, pyridine, ethylacetate and N, N- dimethylformamide were obtained at 298 K in 1,2-dichloroethane by u.v .-visible spectrophotometry . The optical absorption maxima, D, of the mixed-chelate copper(II) complex in various donor solvents which decrease as the axial interaction increases were also measured and it was found that no linear correlation exists between C (cm-l) and the solvent donor number. Isotropic hyperfine coupling constants of 63,65Cu, Aiso, and isotropic g values, giso were obtained in various solvents. In general, Aiso decreases but giso increases as the axial interaction increases. The coefficient, α, of the dx2-y2 orbital in the ground state molecular orbital (B1g) was found to decrease with increasing axial interaction. The frozen solution e.s.r. spectra als ; gave α values similar to those obtained from the solution spectra. The relationship g?> g? was found in all solvents, indicating the presence of elongated tetragonal symmetry.