Investigation of Bimetallic Nickel Catalysts in Catalyst‐Transfer Polymerization of π‐Conjugated Polymers

A comparative study involving bimetallic nickel catalysts designed from disubstituted N,N,N′,N′‐tetra(diphenylphosphanylmethyl)benzene diamine bridging ligands is reported. Catalyst behavior is explored in the Kumada catalyst‐transfer polymerization (KCTP) using poly(3‐hexylthiophene) (P3HT) as the model system. The success of a controlled polymerization is monitored by analyzing monomer conversion, degree of polymerization, end‐group identity, and molecular weight distribution. The characterization of P3HT obtained from KCTP initiated with the bimetallic catalysts shows chain‐growth behavior; however, the presence of Br/Br end‐groups and broader molecular weight distribution reveals a reduced controlled polymerization compared to the commonly employed Ni(dppp)Cl₂. The observed increase in intermolecular chain transfer and termination processes in KCTP initiation with the bimetallic catalysts can be attributed to a weaker Ni(0)‐π‐aryl complex interaction, which is caused by increased steric crowding of the coordination sphere.     

A study of some variables in a tetrazolium dye (MTT) based assay for cell growth and chemosensitivity

We have studied various factors involved in the optimal use of a tetrazolium (MTT) based colorimetric assay for cell growth and chemosensitivity. The assay is dependent on the ability of viable cells to metabolise a water-soluble tetrazolium salt into a water-insoluble formazan product. We have found that DMSO is the best solvent for dissolving the formazan product, especially where a significant amount of residual medium is left in the wells of the microtitre tray used for the assay. A reaction occurs between medium and a solution of MTT formazan in DMSO which changes the shape of the absorbance spectrum of the solution. The resulting optical density is not however greatly dependent upon the volume of added medium in the range 1-10 microliters. Between 10 and 40 microliters of added medium results in a gradually lower optical density than that produced by the smaller volumes. Above 40 microliters, the optical density increases again due to turbidity as protein precipitation occurs. When cells are incubated with MTT, the resulting optical density of the formazan product is dependent upon both the concentration of MTT and the incubation time. The optical density is stable for several hours after solution of the formazan in DMSO. A linear relationship is seen between optical density and cell number for incubation times of 2, 4, 6 or 24 h with 20 microliters of MTT (5 mg ml-1) added to 200 microliters medium. We have adopted 4 h as the standard incubation time for the assay. Only a small amount of MTT formazan product can be detected in the growth medium of wells in which cells have been exposed to MTT. Comparative chemosensitivity data for EMT6 mouse tumour cells show good agreement between results obtained using the MTT assay and results based on total cell count after a fixed period of growth.     

Revision of well-fixed infected Birmingham hip resurfacing using the Explant system and cement mould: an useful technique

Deep infections do occur during hip resurfacing despite all precautions. We present the method and use of the acetabular bone stock preserving Explant system in the removal of infected well-fixed cementless acetabular components and the technique of using an antibiotic impregnated cement spacer to provide a functional joint, enabling the patient to mobilise with minimal discomfort between two staged revision procedures.     

Tacrine hydrochloride treatment IND: methods for rapid physician and patient enrollment and data retrieval

A Treatment IND (TIND) is a mechanism available to the Food and Drug Administration (FDA) in the United States by which promising new drugs can be provided to patients with life-threatening illnesses. In many instances, the illness is life-threatening but of relatively low incidence, making the demand for the new treatment limited. However, if the disease is more prevalent and incidence is increasing, the demand for access to an experimental therapy may be substantially greater. Novel approaches and technologies would help manage recruitment of physicians, enrollment of patients and retrieval and timely analysis of data. Such was the case in the TIND for tacrine hydrochloride (Cognex), a cholinesterase inhibitor which was under development for the treatment of patients with Alzheimer's Disease (AD). There were an estimated 4 million prevalent cases of AD in the US for which no approved therapeutic option was available at the time this TIND was initiated. We anticipated that there could be a large demand by both physicians and patients to enroll in the TIND. Therefore, to meet this demand, various mechanisms were employed to allow rapid enrollment and drug shipments to the patient. In addition, physicians who participated in the TIND were able to use a telephone touch-tone data entry system for reporting data and ordering new supplies of tacrine for their patients. Serious adverse events were reported directly to trained operators and summarized on a weekly basis for reporting to the FDA. At the time the programme was terminated, nearly 2000 physicians had enrolled to participate in the TIND and nearly 10,000 patients had received tacrine under the programme. The methods employed in this study to collect clinic visit and safety data met both regulatory and good clinical practice guidelines. In summary, a large volume of data was handled rapidly and efficiently in this programme.     

Allelic loss on chromosomes 8p, 22q and 18q (DCC) in human prostate cancer

Previous studies have suggested the involvement of tumour-suppressor genes on chromosomes 8p, 22q and 18q (DCC) in prostate cancer. The aim of this study was to further characterize these regions. We investigated 20 polymorphic regions on the 3 chromosome arms in 43 cancers and 10 cases of benign prostatic hyperplasia (BPH). Allelic loss was observed in 72% of cancers on 8p, 16% on 22q and 24% at DCC. For BPH, loss was observed in 20% on 8p and in 12% at DCC. The low incidence of LOH on 22q implies that this locus has no significant role in prostate carcinogenesis. At DCC, although the overall incidence was low, tumours with LOH were mostly of high grade or had metastases, suggesting a role for this gene in prostate cancer progression. On chromosome 8p, 29% of cancers had deletions at the LPL locus on 8p22 and 60% had deletions within a region flanked by the markers D8S339 and ANKI on 8p11.1-p21.1. Within this region, 2 distinct areas of allelic loss were observed, at one or both ANKI and D8S255, and in the region defined by the markers D8S259-D8S505. For the regions 8p22 and ANKI-D8S255, tumours with metastases had a greater frequency of LOH compared to non-metastasizing tumours, suggesting the presence of putative metastasis-suppressor genes in these regions. © 1996 Wiley-Liss, Inc.     

Bilateral intraocular lens implantation

A study of 1796 consecutive cataract patients in a posterior chamber intraocular lens implant (IOL) series revealed 373 patients (20.8%) who had bilateral IOLs. Visual acuity was 20/40 or better in 87% of first eyes operated and 90% in second eyes. The major cause of vision less than 20/40 was senile macular choroidal degeneration in both first and second eyes. The surgical reintervention rate was 11.8% in first eyes and 3.7% in second eyes. Ninety-two percent of patients had an interval of six months or more between surgery on the first and second eyes.     

Can we track the impact of Australian mental health research?

OBJECTIVE: Arguments are being made to increase research and development funding for mental health research in Australia. Consequently, the methods used to measure the results of increased investment require review. This study aimed to describe the status of Australian mental health research and to propose potential methods for tracking changes in research output. Specifically, we describe the research output of nations, Australian states, Australian and New Zealand institutions and Australian and New Zealand researchers using citation rates. METHOD: Information on research output was sourced from two international databases (Institute for scientific information [ISI] Essential Science Indicators and ISI Web of Science) and the ISI list of Highly Cited Researchers. RESULTS: In an international setting, Australia does not perform as well as other comparable countries such as New Zealand or Canada in terms of research output. Within Australia, the scientific performance of institutions apparently relates to the strength of some individual researchers or consolidated research groups. Highly cited papers are evident in the fields of syndrome definition, epidemiology and epidemiological methods, cognitive science and prognostic or longitudinal studies. CONCLUSIONS: Australian researchers need to consider the success of New Zealand and Canadian researchers, particularly given the relatively low investment in health and medical research in New Zealand. Although citation analyses are fraught with difficulties, they can be effectively complemented by other measures of responsiveness to clinical or population needs and community expectations and should be conducted regularly and independently to monitor the status of Australian mental health research.