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Biomedical subjects

Karen James

Publications and source records attributed to Karen James.

At least 19 recordsLinked to original sources
PubMed2016

DNA barcoding in diverse educational settings: five case studies.

Despite 250 years of modern taxonomy, there remains a large biodiversity knowledge gap. Most species remain unknown to science. DNA barcoding can help address this gap and has been used in a variety of educational contexts to incorporate original research into school curricula and informal education programmes. A growing body of evidence suggests that actively conducting research increases student engagement and retention in science. We describe case studies in five different educational settings in Canada and the USA: a programme for primary and secondary school students (ages 5-18), a year-long professional development programme for secondary school teachers, projects embedding this research into courses in a post-secondary 2-year institution and a degree-granting university, and a citizen science project. We argue that these projects are successful because the scientific content is authentic and compelling, DNA barcoding is conceptually and technically straightforward, the workflow is adaptable to a variety of situations, and online tools exist that allow participants to contribute high-quality data to the international research effort. Evidence of success includes the broad adoption of these programmes and assessment results demonstrating that participants are gaining both knowledge and confidence. There are exciting opportunities for coordination among educational projects in the future.This article is part of the themed issue 'From DNA barcodes to biomes'.

Biodiversity↗
PubMed2006

Preclinical pharmacokinetics and metabolism of a novel diaryl pyrazole resorcinol series of heat shock protein 90 inhibitors.

CCT018159 was recently identified as a novel inhibitor of heat shock protein (Hsp) 90, a promising target for cancer therapy. Pharmacokinetic and metabolic properties are likely to be important for efficacy and need to be optimized during drug development. Here, we define the preclinical metabolism and pharmacokinetics of CCT018159 and some early derivatives. In addition, we assess in vitro metabolic stability screening and in vivo cassette dosing (simultaneous administration of several compounds to a single animal) as approaches to investigate these compounds. The plasma clearance following individual i.v. administration to mice was rapid (0.128-0.816 L/h), exceeding hepatic blood flow. For CCT066950 and CCT066952, this could be attributed in part to extensive (>80%) blood cell binding. Oral bioavailability ranged from 1.8% to 29.6%. Tissue distribution of CCT066952 was rapid and moderate, and renal excretion of the compounds was minimal (<1% of dose excreted). Compounds underwent rapid glucuronidation both in vivo and following incubation with mouse liver microsomes. However, whereas CCT066965 was metabolized to the greatest extent in vitro, this compound displayed the slowest plasma clearance. The rank order of the compounds from the highest to lowest area under the curve was the same following discrete and cassette dosing. Furthermore, pharmacokinetic variables were similar whether the compounds were dosed alone or in combination. We conclude that the pharmacokinetics of CCT018159 are complex. Cassette dosing is currently the best option available to assess the pharmacokinetics of this promising series of compounds in relatively high throughput and is now being applied to identify compounds with optimal pharmacokinetic properties during structural analogue synthesis.

Animals↗
PubMed2006

Cost effectiveness of biventricular pacemakers in heart failure patients.

BACKGROUND: Biventricular pacemakers have been shown to reduce mortality and hospitalizations in heart failure (HF) patients and are indicated for those with a New York Heart Association functional class of III or IV and a QRS interval of >130 ms. However, these devices currently cost in the region of dollar US 33,500 and require replacement upon battery depletion. Therefore, determination of the cost effectiveness of resynchronization therapy is important, although little data have been published to date on this topic. METHODS AND RESULTS: A cost-utility analysis from the healthcare perspective was performed using HF patients who received a biventricular pacing device in the Cleveland Clinic Foundation. The comparator was a similarly profiled group of patients who did not receive the device but were treated medically. A Markov model was used to investigate the cost effectiveness at 1 and 5 years. Second-order Monte-Carlo simulation was used to determine the variability in results, using probabilistic sensitivity analysis. Medical treatment was dominated by biventricular pacemaker treatment at both 1 and 5 years of follow-up. CONCLUSION: Biventricular device insertion is an economically attractive treatment option for clinically indicated HF patients.

Cardiac Pacing, Artificial↗
PubMed2005

The identification, synthesis, protein crystal structure and in vitro biochemical evaluation of a new 3,4-diarylpyrazole class of Hsp90 inhibitors.

High-throughput screening identified the 3,4-diarylpyrazole CCT018159 as a novel and potent (7.1 microM) inhibitor of Hsp90 ATPase activity. Here, we describe the synthesis of CCT018159 and a number of close analogues together with data on their biochemical properties. Some initial structure-activity relationships are discussed, as well as the crystal structure of CCT018159 bound to Hsp90.

Adenosine Triphosphatases↗
PubMed2005

Holographic glucose sensors.

A novel holographic sensor system capable of detecting dynamic changes in glucose concentration has been developed. The hologram is recorded within a bio-compatible hydrogel matrix containing phenylboronic acid derivatives. On binding glucose, the colour of the hologram red-shifts to longer wavelengths as the hydrogel expands and this colour change is used to quantify glucose concentration. However, phenylboronic acids are non-selective and bind a wide variety of cis-diols. In blood, glucose is the only sugar found free at high concentration, whilst other sugars are typically found as part of glycoproteins and macromolecular structures. Although glycoproteins have been shown to have no effect on the sensor, phenylboronic acids can bind lactate much more readily than glucose. We have designed two polymer hydrogel systems to increase the selectivity of the sensor for glucose over lactate. The first involved the use of high concentrations of 3-acrylamidophenylboronic acid (3-APB) whilst the second system utilised 2-acrylamido-5-fluorophenylboronic acid (5-F-2-MAPB). Both systems displayed an increased selectivity to glucose over lactate at physiological pH and ionic strength and could be deployed as selective holographic sensors for glucose detection in physiological fluids.

Biosensing Techniques↗
PubMed2004

Molecular analysis of WFDC1/ps20 gene in prostate cancer.

BACKGROUND: WFDC1/ps20 protein has been previously established as a growth suppressor of the prostate cancer cell line PC3. It maps to chromosome 16q23.1, a region of frequent loss of heterozygosity, familial association, and genomic loss in prostate cancer. We, therefore, chose to examine WFDC1/ps20 for mutations and expression changes in prostate cancer. METHODS: DNA from 21 prostate cancer patients and 5 prostate cancer cell lines was screened for mutations in the WFDC1/ps20 gene by sequencing PCR products of each exon. An SphI polymorphism in the 5' UTR was screened in 23 tumors, 22 normal adjacent prostate tissue samples, and 35 control DNAs. Expression of WFDC1/ps20 in different tissue types was examined by Northern blot and by PCR across a multi-tissue cDNA panel. Expression patterns of WFDC1/ps20 in primary tumors were examined by full-length RT-PCR and products were cloned and sequenced to identify novel splice forms. Quantitative RT-PCR analysis of WFDC1/ps20 was performed in a separate cohort of matched tumor/benign tissues. RESULTS: No tumor-associated mutations were identified in the coding region of WFDC1/ps20. A novel polymorphism was found in exon 6 in DNA from cell lines, tumors, and normal adjacent benign tissue. A novel splice form completely deleted for exon 3 was found in tumor and normal prostate RNA. Quantitative RT-PCR demonstrated significant down regulation of WFDC1/ps20 in prostate tumors. Subdivision of normal tissue into stromal and epithelial compartments showed that WFDC1/ps20 expression correlates exponentially with the amount of stroma present. CONCLUSIONS: WFDC1/ps20 is down regulated but not frequently mutated in prostate cancer. It is expressed predominantly in the normal stroma of the prostate. We, therefore, propose that WFDC1/ps20 may not be a classical tumor suppressor gene, but might play a role in the maintenance of the normal extra cellular matrix milieu in the prostate.

Cell Line↗
PubMed2004

Integration of high-resolution array comparative genomic hybridization analysis of chromosome 16q with expression array data refines common regions of loss at 16q23-qter and identifies underlying candidate tumor suppressor genes in prostate cancer.

We have constructed a high-resolution genomic microarray of human chromosome 16q, and used it for comparative genomic hybridization analysis of 16 prostate tumors. We demarcated 10 regions of genomic loss between 16q23.1 and 16qter that occurred in five or more samples. Mining expression array data from four independent studies allowed us to identify 11 genes that were frequently underexpressed in prostate cancer and that co-localized with a region of genomic loss. Quantitative expression analyses of these genes in matched tumor and benign tissue from 13 patients showed that six of these 11 (WWOX, WFDC1, MAF, FOXF1, MVD and the predicted novel transcript Q9H0B8 (NM_031476)) had significant and consistent downregulation in the tumors relative to normal prostate tissue expression making them candidate tumor suppressor genes.

Chromosomes, Human, Pair 16↗
PubMed2003

Synthesis and biochemical evaluation of some novel benzoic acid based esters as potential inhibitors of oestrone sulphatase.

Oestrone sulphatase is an important target in the fight against hormone-dependent breast cancer. In an effort to investigate the reported definitive pharmacophore for oestrone sulphatase and continue our search for potent inhibitors of this enzyme, we have undertaken extensive synthesis, biochemical evaluation and physicochemical property determination of a range of benzoic acid based esters. Here, we report the initial results of our study into a series of straight chain alkyl esters of 4-sulphonylbenzoic acid. Using these compounds, we have investigated the involvement of two physicochemical properties, namely logP and pK(a). The results of this study show that there was a strong correlation between the inhibitory activity and the logP of the parent compound. Within the series of compounds studied, hydrophobicity appears to be a more important factor than pK(a) in determining the overall inhibitory activity. In a previous report, we showed that pK(a) plays an important role in stabilizing the phenoxide ion resulting from the hydrolysis of the sulphamate group. Here, we propose that although pK(a) is an important factor in determining the overall inhibitory activity when a wide range of compounds are considered, both hydrophobicity and pK(a) need to be considered in the design of potential inhibitors of oestrone sulphatase.

Benzoates↗
PubMed2003

Structure-activity relationship determination within a group of substituted phenyl sulfamate based compounds against the enzyme oestrone sulfatase.

The enzyme oestrone sulfatase (ES) is responsible for the conversion of the stored (sulfated) form of oestrogens to the active form, namely oestrone. In our continuing quest to synthesize potent inhibitors of oestrone sulfatase and to determine the structural requirements for such inhibition, we have synthesized and evaluated several derivatives of phenyl sulfamate. We report the results of the synthesis and biochemical evaluation of a series of 3- and 4-aminosulfonated derivatives of phenol in an effort to investigate the role of the acid dissociation constant (pK(a)), and therefore the stability of the phenoxide ion, on the inhibitory activity of compounds against this enzyme. The results showed that there was a strong correlation between the observed pK(a) and inhibitory activity within the aminosulfonated compounds considered. This suggested that in the inhibition of oestrone sulfatase by these compounds, pK(a) was an important physicochemical property, and as such, the stability of the O(-) ion was a crucial factor in the inhibition, and therefore the drug design process.

Enzyme Inhibitors↗
PubMed2003

Implementing a shared-care approach to improve the management of patients with pulmonary arterial hypertension.

Patients with pulmonary arterial hypertension (PAH) may present to internists, rheumatologists, cardiologists, or pulmonologists. This breadth of clinicians who encounter PAH patients, together with the complicated nature of PAH as a disease entity, argues for a shared-care approach to the management of these patients. This review describes the contributions of several key specialties to PAH management and outlines the collaborative PAH management model in place at our institution.

Attitude of Health Personnel↗
PubMed2002

Inhibition of estrone sulfatase (ES) by derivatives of 4-[(aminosulfonyl)oxy] benzoic acid.

In our search for potent inhibitors of the enzyme estrone sulfatase (ES), we have undertaken the synthesis and biochemical evaluation of a range of straight chain alkyl esters of 4-[(aminosulfonyl)oxy] benzoic acid. The results of the study show that the synthesised compounds possess greater inhibitory activity when compared to COUMATE, although they were all found to possess lower inhibitory activity with respect to EMATE. Furthermore, the data suggest a strong correlation between logP and IC(50) and therefore adds further support to our previous report where we suggested a link between inhibitory activity and hydrophobicity.

Antineoplastic Agents↗
PubMed2002

The design, synthesis, and biochemical evaluation of derivatives of biphenyl sulfamate-based compounds as novel inhibitors of estrone sulfatase.

We report the initial results of our study into the use of a potential transition state (TS) of the reaction catalyzed by the enzyme estrone sulfatase (ES) in the design of a series of simple 4'-O-sulfamoyl-4-biphenyl-based compounds as novel inhibitors of ES. The results of the study show that these compounds are: potent inhibitors, possessing greater inhibitory activity than 4-methylcoumarin-7-O-sulfamate (COUMATE); weaker inhibitors than the tricyclic derivative of COUMATE, namely 667-COUMATE and the steroidal inhibitor estrone-3-O-sulfamate (EMATE), and irreversible inhibitors of ES.

Catalysis↗
PubMed2002

Design, synthesis and biochemical evaluation of AC ring mimics as novel inhibitors of the enzyme estrone sulfatase (ES).

We report the initial results of our study into a series of simple 4'-O-sulfamoyl-4-biphenyl based compounds as novel inhibitors of the enzyme estrone sulfatase (ES). The results of the study show that these compounds are potent inhibitors, possessing greater inhibitory activity than COUMATE, but weaker inhibitory activity than EMATE or the tricyclic derivative of COUMATE, namely 667-COUMATE. Furthermore, the compounds are observed to be irreversible inhibitors.

Coumarins↗
PubMed2002

The mechanism of the irreversible inhibition of estrone sulfatase (ES) through the consideration of a range of methane- and amino-sulfonate-based compounds.

We report the results of our study into a series of simple phenyl and alkyl sulfamates and alkyl methanesulfonates as potential inhibitors of the enzyme estrone sulfatase (ES). The results of the study show that the substituted phenyl sulfamates are good irreversible inhibitors; the alkyl sulfamate compounds were found to lack inhibitory activity; whilst the large alkyl chain containing methanesulfonate-based compounds were found to possess weak reversible inhibitory activity. Using the results of the inhibition study, we postulate the probable mechanism for ES and suggest that an attack by the gem-diol is a major requirement prior to the hydrolysis of the sulfamate group, following which, attack on the active site C=O occurs and which therefore leads to the production of an imine type functionality, resulting in irreversible inhibition.

Enzyme Inhibitors↗
PubMed2002

Evidence for the mechanism of the irreversible inhibition of oestrone sulphatase (ES) by aminosulphonate based compounds.

In our search for the mechanism of the enzyme oestrone sulphatase (ES) we have synthesised and evaluated a number of compounds that were predicted to possess some inhibitory activity. Some of these compounds were indeed found to be inhibitors of ES, whilst other compounds were not. From a consideration of the structure-activity relationship (SAR) of the inhibitors and non-inhibitors of this enzyme, we discovered a factor which we now believe is the main inhibitory moiety within the aminosulphonated inhibitors. We therefore report the results of our study into a series of phenyl and alkyl sulphamated compounds as inhibitors of ES. The results of the study show that the substituted phenyl sulphamates are potent inhibitors, whereas the alkyl compounds are, in general, non-inhibitors. Using the results of our SAR study, we postulate the probable mechanism for the irreversible and reversible inhibition of ES, and rationalise the role of the different physicochemical factors in the inhibition of this crucial enzyme.

Anions↗
PubMed2002

Synthesis and biochemical evaluation of novel and potent inhibitors of the enzyme oestrone sulphatase (ES).

In an effort to investigate the structural requirements for the inhibition of the enzyme oestrone sulphatase (ES), we have previously undertaken extensive structure-activity relationship studies. Using the data from molecular modelling and structure-activity relationship determination studies, we have designed a number of compounds based upon 4-sulphamated phenyl ketones. Here, we report the results of our study into a series of these compounds as potential inhibitors of ES. The results of the study show that these compounds are potent inhibitors the possessing greater inhibitory activity than 4-methylcoumarin-7-O-sulphamate derivative (COUMATE) (a potent non-steroidal inhibitor), but are weaker than oestrone-3-sulphamate (EMATE) and the recently reported 667- and 669-COUMATE, however, they provide good lead compounds in the search for potent inhibitors of ES. Furthermore, the compounds are observed to be irreversible inhibitors. From the consideration of the structure-activity relationship of these novel compounds, we have attempted to rationalise the significance of the log P factor in the inhibition of ES and suggest that a log P requirement of approximately 3.5 aids the inhibition through the rapid expulsion of the carbon backbone from the active site. We also propose that the same factor is responsible for the hydrolysis of oestrone sulphate reaction, appearing to be an irreversible process.

Coumarins↗
PubMed2002

Design, synthesis and biochemical evaluation of AC ring mimics as novel inhibitors of the enzyme estrone sulfatase (ES).

We report the results of our study into a series of 4'-O-sulfamoyl-4-biphenyl based compounds as novel inhibitors of the enzyme estrone sulfatase (ES). From the results of the molecular modeling design process, it was suggested that these compounds would be able to mimic both the A and C rings of the steroid backbone, and thus possess inhibitory activity against ES. The results of the biochemical evaluation study show that these compounds are indeed good inhibitors, possessing greater inhibitory activity than COUMATE, but weaker inhibitory activity than EMATE or the tricyclic derivative of COUMATE, namely 667-COUMATE. Furthermore, the compounds are observed to be irreversible inhibitors.

Coumarins↗