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Biomedical subjects

Steven D Heys

Publications and source records attributed to Steven D Heys.

At least 19 recordsLinked to original sources
PubMed2004

The relationship between vascular and metabolic characteristics of primary breast tumours.

The objective of this study was to investigate the relationship between vascular and metabolic characteristics of breast tumours in vivo, using contrast-enhanced dynamic MRI and 2-[(18)F] fluoro-2-deoxy- d-glucose (FDG) PET imaging. Twenty patients with large or locally advanced primary breast cancers were imaged prior to therapy. MRI data were acquired using a dynamic gradient echo sequence and analysed using two pharmacokinetic models. Static PET data were acquired in 2D mode. A significant association ( P<0.05) was observed between the calculated exchange rate constants of both pharmacokinetic models and calculated PET FDG dose uptake ratios (DUR). Statistical analysis showed that the exchange rate constants can explain between 27 and 44% of the variance observed in the PET FDG uptake ratios. A relationship was demonstrated between the vascular and metabolic characteristics of primary breast tumours showing that any assessment of tumour metabolic activity using PET may be controlled at least in part by delivery of uptake agent due to the vascular characteristics of the tumour. MRI and PET provide methods of assessing breast tumour vascularity and metabolism in vivo using the exchange rate constants of dynamic MRI, and DUR of PET, respectively, these measures being related but not equivalent.

Adult↗
PubMed2004

Reduced expression of p27 is a novel mechanism of docetaxel resistance in breast cancer cells.

INTRODUCTION: Docetaxel is one of the most effective chemotherapeutic agents in the treatment of breast cancer. Breast cancers can have an inherent or acquired resistance to docetaxel but the causes of this resistance remain unclear. However, apoptosis and cell cycle regulation are key mechanisms by which most chemotherapeutic agents exert their cytotoxic effects. METHODS: We created two docetaxel-resistant human breast cancer cell lines (MCF-7 and MDA-MB-231) and performed cDNA microarray analysis to identify candidate genes associated with docetaxel resistance. Gene expression changes were validated at the RNA and protein levels by reverse transcription PCR and western analysis, respectively. RESULTS: Gene expression cDNA microarray analysis demonstrated reduced p27 expression in docetaxel-resistant breast cancer cells. Although p27 mRNA expression was found to be reduced only in MCF-7 docetaxel-resistant sublines (2.47-fold), reduced expression of p27 protein was noted in both MCF-7 and MDA-MB-231 docetaxel-resistant breast cancer cells (2.83-fold and 3.80-fold, respectively). CONCLUSIONS: This study demonstrates that reduced expression of p27 is associated with acquired resistance to docetaxel in breast cancer cells. An understanding of the genes that are involved in resistance to chemotherapy may allow further development in modulating drug resistance, and may permit selection of those patients who are most likely to benefit from such therapies.

Antineoplastic Agents, Phytogenic↗
PubMed2004

Conjugated linoleic acids (CLAs) decrease prostate cancer cell proliferation: different molecular mechanisms for cis-9, trans-11 and trans-10, cis-12 isomers.

The aims of this study were to examine the anti-proliferative effects of different concentrations of a commercial preparation of conjugated linoleic acids (CLA) mixture of isomers [cis-9, trans-11 CLA (c9,t11 CLA): trans-10, cis-12 CLA (50:50)] and their constituent isomers on PC-3, a human prostatic carcinoma cell line, and to study their effects on gene expression (mRNA and protein levels) of different enzymes and oncoproteins involved in oncogenesis and progression of prostate cancer. This includes pathways for arachidonic acid metabolism [cyclooxygenase 1 (COX-1), 2 (COX-2) and 5-lipoxygenase (5-LOX)], apoptosis (bcl-2) and cell cycle control (p21(WAF/Cip1)). Our results indicate a significant decrease in PC-3 proliferation elicited by CLA, although with high variability between isomers. The trans-10, cis-12 CLA was the most effective isomer (55% inhibition). This isomer was also able to decrease bcl-2 gene expression and to increase p21(WAF1/Cip1) mRNA levels (60% increase at highest concentration). In contrast, cis-9, trans-11 had no effect on these proteins but had a clear effect on 5-LOX expression and to a lesser degree on COX-2 protein level isomers. In conclusion, the anti-proliferative effects on PC-3 of CLA mixture and their constituent isomers are not equivalent, due to the different pathways involved for individual isomers. Trans-10, cis-12 seems to work preferentially through modulation of apoptosis and cell cycle control, while c9,t11 CLA isomer affects arachidonic acid metabolism.

Arachidonate 5-Lipoxygenase↗
PubMed2004

Conjugated linoleic acids: are they beneficial or detrimental to health?

Conjugated linoleic acids (CLAs) comprise a family of positional and geometric isomers of linoleic acid (18:2n-6; LA) that are formed by biohydrogenation and oxidation processes in nature. The major dietary sources of these unusual fatty acids are foods derived from ruminant animals, in particular dairy products. The main form of CLA, cis-9, trans-11-18:2, can be produced directly by bacterial hydrogenation in the rumen or by delta-9 desaturation of the co-product vaccenic acid (trans-11-18:1) in most mammalian tissues including man. The second most abundant isomer of CLA is the trans-10, cis-12-18:2 form. Initially identified in grilled beef as a potential anti-carcinogen a surprising number of health benefits have subsequently been attributed to CLA mixtures and more recently to the main individual isoforms. It is also clear from recent studies that the two main isoforms can have different effects on metabolism and cell functions and can act through different cell signalling pathways. The majority of studies on body compositional effects (i.e. fat loss, lean gain), on cancer and cardiovascular disease attenuation, on insulin sensitivity and diabetes and on immune function have been conducted with a variety of animal models. Observations clearly emphasise that differences exist between mammalian species in their response to CLAs with mice being the most sensitive. Recent studies indicate that some but not all of the effects observed in animals also pertain to human volunteers. Reports of detrimental effects of CLA intake appear to be largely in mice and due mainly to the trans-10, cis-12 isomer. Suggestions of possible deleterious effects in man due to an increase in oxidative lipid products (isoprostanes) with trans-10, cis-12 CLA ingestion require substantiation. Unresponsiveness to antioxidants of these non-enzymatic oxidation products casts some doubt on their physiological relevance. Recent reports, albeit in the minority, that CLAs, particularly the trans-10, cis-12 isomer, can elicit pro-carcinogenic effects in animal models of colon and prostate cancer and can increase prostaglandin production in cells also warrant further investigation and critical evaluation in relation to the many published anti-cancer and anti-prostaglandin effects of CLAs.

Animals↗
PubMed2004

Can patients' likelihood of benefiting from primary chemotherapy for breast cancer be predicted before commencement of treatment?

PURPOSE: Primary chemotherapy is commonly used in patients with breast cancer to downstage the primary tumour prior to surgery. There is a need to establish, prior to commencement of chemotherapy, predictors of clinical and pathological response, which may then be surrogate markers for patient survival and thus allow identification of patients who are most likely to benefit from such treatment. PATIENTS AND METHODS: A total of 104 patients with large and locally advanced breast cancers received an anthracycline/docetaxel-based regimen prior to surgery. Immunohistochemistry was carried out on pre-treatment core biopsies of the tumour to detect hormone receptors (oestrogen-ER; progesterone-PR), a proliferation marker (MIB-1), the oncoprotein Bcl-2, an extracellular matrix degradation enzyme (cathepsin D), p53, and an oestrogen associated protein (pS2). Both clinical and pathological response were assessed following completion of chemotherapy. RESULTS: Patients whose tumours did not express oestrogen receptor (p = 0.02) or did not express Bcl-2 (p < 0.01) had a better pathological response in a univariate analysis. However, in a multivariate model, it was only the absence of detectable Bcl-2 protein that predicted a better pathological response (p = 0.001). CONCLUSIONS: This study has identified that patients whose breast cancers are most likely to experience the greatest degree of tumour destruction by primary chemotherapy do not express either oestrogen receptors or Bcl-2. This may have important implications in the selection of patients with breast cancer for primary chemotherapy who are most likely to gain a survival benefit.

Adult↗
PubMed2004

Factor analysis can be a useful standard setting tool in a high stakes OSCE assessment.

BACKGROUND: No method of standard setting for objective structured clinical examinations (OSCEs) is perfect. Using scores aggregated across stations risks allowing students who are incompetent in some core skills to pass an examination, which may not be acceptable for high stakes assessments. AIM: To assess the feasibility of using a factor analysis of station scores in a high stakes OSCE to derive measures of underlying competencies. METHODS: A 12-station OSCE was administered to all 192 students in the penultimate undergraduate year at the University of Aberdeen Medical School. Analysis of the correlation table of station scores was used to exclude stations performing unreliably. Factor analysis of the remaining station scores was carried out to characterise the underlying competencies being assessed. Factor scores were used to derive pass/fail cut-off scores for the examination. RESULTS: Four stations were identified as having unpredicted variations in station scores. Analysis of the content of these stations allowed the underlying problems with the station designs to be isolated. Factor analysis of the remaining 8 stations revealed 3 main underlying factors, accounting for 53% of the total variance in scores. These were labelled "examination skills", "communication skills" and "history taking skills". CONCLUSION: Factor analysis is a useful tool for characterising and quantifying the skills that are assessed in an OSCE. Standard setting procedures can be used to calculate cut-off scores for each underlying factor.

Clinical Competence↗
PubMed2004

Conjugated linoleic acid inhibits proliferation and modulates protein kinase C isoforms in human prostate cancer cells.

Prostate cancer is the second most common cancer in men. The disease etiology is poorly understood, but diet and lifestyle are contributory factors. Conjugated linoleic acids (CLAs), naturally occurring fatty acids in ruminant food products, have antitumor properties in animal models of cancer and antiproliferative effects on cancer cells in vitro. The cellular mechanisms by which CLAs elicit these effects are unclear, particularly for prostate cancer cells. We have previously identified protein kinase C (PKC) isoforms, alpha, delta, iota, mu, and zeta in LNCaP prostate cancer cells. The objective of this study was to determine the effects of CLAs (individual cis-9, trans-11 and trans-10, cis-12 isoforms and a 50:50 mixture) on PKC isoform abundance in LNCaP cells. Confluent cells were treated with 6, 25, and 50 microM CLA for 0.5, 6, and 24 h. Cytosol and membrane protein fractions were assayed for PKC isoforms (mainly alpha and delta but also iota, mu, and zeta) by Western blot analysis using specific antibodies. CLAs clearly modulated the abundance of these PKC isoforms, both positively and negatively, depending on the isoform, concentration of CLAs, and period of treatment. Increased PKC-delta and decreased PKC-iota membrane abundance was consistent with CLAs eliciting increased apoptosis and, in part, with their antitumor effects.

Cell Division↗
PubMed2004

Docetaxel as adjuvant and neoadjuvant treatment for patients with breast cancer.

Developments in the role of adjuvant and neoadjuvant chemotherapy for the treatment of patients with breast cancer have focused on the taxes, in particular, docetaxel. This paper discusses the rationale for the introduction of docetaxel into the management of patients following surgery and also its role in those patients with locally-advanced disease, focussing on key clinical trials. The addition of docetaxel to standard adjuvant chemotherapeutic regimens does seem to result in an increased survival in some patients with early-stage disease. In the neoadjuvant setting, the addition of docetaxel to standard regimens does increase pathological response rates, which is a surrogate marker of eventual outcome.

Antineoplastic Agents, Phytogenic↗
PubMed2003

Local recurrence in patients with large and locally advanced breast cancer treated with primary chemotherapy.

BACKGROUND: Primary chemotherapy is being given in the treatment of large and locally advanced breast cancers, but a major concern is local relapse after therapy. This paper has examined patients treated with primary chemotherapy and surgery (either breast-conserving surgery or mastectomy) and has examined the role of factors which may indicate those patients who are subsequently more likely to experience local recurrence of disease. METHODS: A consecutive series of 173 women, with data available for 166 of these, presenting with large and locally advanced breast cancer (T2>/=4 cm, T3, T4, or N2) were treated with primary chemotherapy comprising cyclophosphamide, vincristine, doxorubicin, and prednisolone and then surgery (either conservation or mastectomy with axillary surgery) followed by radiotherapy were examined. RESULTS: The clinical response rate of these patients was 75% (21% complete and 54% partial), with a complete pathological response rate of 15%. A total of 10 patients (6%) experienced local disease relapse, and the median time to relapse was 14 months (ranging from 3 to 40). The median survival in this group was 27 months (ranging from 13 to 78). In patients having breast conservation surgery, local recurrence occurred in 2%, and in those undergoing mastectomy 7% experience local relapse of disease. Factors predicting patients most likely to experience local recurrence were poor clinical response and residual axillary nodal disease after chemotherapy. CONCLUSIONS: Excellent local control of disease can be achieved in patients with large and locally advanced breast cancers using a combination of primary chemotherapy, surgery and radiotherapy. However, the presence of residual tumor in the axillary lymph nodes after chemotherapy is a predictor of local recurrence and patients with a better clinical response were also less likely to experience local disease recurrence. The size and degree of pathological response did not predict patients most likely to experience recurrence of disease.

Adult↗
PubMed2003

A new histological grading system to assess response of breast cancers to primary chemotherapy: prognostic significance and survival.

The clinical and complete pathological response of a primary breast cancer to chemotherapy has been shown to be an important prognostic for survival. However, the majority of patients do not experience a complete pathological response to primary chemotherapy and the significance of lesser degrees of histological response is uncertain and the prognostic significance is unknown. The purpose of this study was to evaluate a new histological grading system to assess response of breast cancers to primary chemotherapy and to determine if such a system has prognostic value.A consecutive series of 176 patients with large (> or =4cm) and locally advanced breast cancers were treated with multimodality therapy comprising primary chemotherapy, surgery, radiotherapy and tamoxifen. All underwent assessment of the primary breast tumour before and after completion of chemotherapy. Residual tumour was excised after completion of chemotherapy (mastectomy or wide local excision with axillary surgery). The removed tissue was assessed and response to chemotherapy graded using a five-point histological grading system based with the fundamental feature being a reduction in tumour cellularity; comparison being made with a pre-treatment core biopsy. All patients were followed up for 5 years or more. Pathological responses were compared to 5 year overall survival and disease-free survival using log rank tests. The overall 5-year survival for all patients was 71%, and 5 year disease free interval was 60%. There was a significant correlation between pathological response using this new grading system and both overall survival (P=0.02) and disease-free interval (P=0.04). In a multivariate analysis of known prognostic factors, the Miller/Payne grading system was an independent predictor of overall patient survival. This grading system, which assesses the histological response to primary chemotherapy, can predict overall survival and disease-free interval in patients with large and locally advanced breast cancers treated with such therapy. The relationship of degree of histological response to overall and disease-free survival has been shown in univariate and multivariate analyses and could potentially have an important role in the clinical management of patients with locally advanced breast cancer undergoing primary chemotherapy.

Adult↗
PubMed2003

Neoadjuvant docetaxel in locally advanced breast cancer.

Neoadjuvant chemotherapy produces substantial increases in clinical response rates and rates of breast conserving therapy. Pathologic response rate, though generally low, is an important outcome as it is presumably associated with eradication of micrometastatic disease and may likely result in improved outcomes. Anthracyclines have long been considered the most efficacious chemotherapy agents for neoadjuvant therapy of early breast cancer. Unfortunately, not all patients respond to neoadjuvant anthracycline-based chemotherapy. In an effort to improve primary tumor response, docetaxel, an active agent in breast cancer, has been evaluated in the neoadjuvant setting. Several randomized trials, including the NSABP B-27, GEPAR-duo, and the Aberdeen trial, evaluating docetaxel in sequence with a doxorubicin-based neoadjuvant regimen have been reported, with encouraging findings. We designed the Aberdeen trial with two primary aims: (1) to evaluate primary docetaxel in patients that initially fail a neoadjuvant anthracycline-based polychemotherapy regimen, and (2) to compare a docetaxel-based neoadjuvant regimen with a standard anthracycline-based regimen in patients who do respond to the first four cycles of the anthracycline-based regimen. Eligible patients (n = 162) had previously untreated large (> or = 3 cm) or locally advanced (T3, T4, T x N2) breast cancer. All received four cycles of CVAP, after which clinical response was assessed. Responding patients were then randomized to four additional cycles of CVAP or to docetaxel 100 mg/m2 every 3 weeks for four cycles. Patients failing to respond to CVAP received the docetaxel regimen. After the first four cycles of CVAP, the overall response rate (ORR) was 67%. Ultimately, responses were higher in the group randomized to docetaxel compared with those continuing CVAP (cCR: 94% vs. 66%; p = 0.001; pCR 34% vs. 16%; p = 0.04). The addition of docetaxel improved overall survival and disease-free survival for patients responding to four cycles of CVAP as compared with those receiving eight cycles of CVAP. Relative dose intensity was higher and the incidence of severe leukopenia was lower in the group randomized to docetaxel. These data and data from the NSABP B-27 and GEPAR-duo trials strongly support a combined anthracycline/docetaxel regimen in the neoadjuvant setting.

Antineoplastic Agents, Phytogenic↗
PubMed2003

Polyunsaturated fatty acids and gene expression in mammalian systems.

Over the last 30 years it has become apparent that specific dietary fatty acids are capable of regulating, either directly or indirectly through various signal pathways, the expression of numerous genes, either positively or negatively. Such nutrient-gene interactions have important effects on cell metabolism, differentiation and growth, and ultimately on disease processes. The present review describes some of the more important fatty acid-gene interactions in relation to health and disease in mammalian species, and focuses on the underlying cell signal mechanisms, including various transcription factors, affected by fatty acids and some of their oxygenated derivatives, e.g. the eicosanoids. The review also attempts to clarify some of the complexities of the effects of fatty acids by suggesting a possible overriding regulation by the redox status of the cell. The latter will at least stimulate controversy in this exciting area of lipid research.

Eicosanoids↗
PubMed2003

Women who wish breast reconstruction: characteristics, fears, and hopes.

The aims of the present study were to identify the characteristics of a consecutive series of women with newly diagnosed breast cancer and to evaluate the perceived benefits and disadvantages of breast reconstruction. A consecutive series of 125 women completed the Breast Reconstruction Questionnaire, the Hospital Anxiety and Depression Scale, and the Eysenck Personality Questionnaire. The median age was 48 years (range, 28 to 75 years). A total of 49.6 percent (n = 62) indicated that, if it were possible, they would like breast reconstruction. Logistic regression (simultaneous entry) revealed that younger women (p = 0.0001) and more depressed women (p = 0.026) were more likely to wish reconstruction. Marital status, tumor size, extroversion, neuroticism, and tough-mindedness did not independently predict the desire for reconstruction. If given a choice of reconstruction at 3 months or 6 months after mastectomy, of the women who wished reconstruction, 74 percent would prefer it at 3 months. Of the women who wished reconstruction and expressed a preference, 63 percent were afraid reconstruction might mask recurrence, 39 percent were afraid that reconstruction might cause the cancer to return, and 89 percent thought they would be concerned with their appearance after the operation. Positively, 94 percent considered that reconstruction would be beneficial in terms of their self-esteem, 86 percent indicated that reconstruction would give greater freedom to wear any clothing, and 86 percent thought that the cosmetic appearance of breast reconstruction was better than that of a prosthesis. Concerns about recurrence were common. A better understanding of the concerns of women with regard to reconstruction would allow more informed preoperative discussion.

Adult↗
PubMed2002

Conjugated linoleic acids (CLAs) regulate the expression of key apoptotic genes in human breast cancer cells.

Conjugated linoleic acid (CLA) reduces mammary tumorigenesis in rodent models, induces apoptosis in rodent mammary tumor cell lines, and decreases expression of antiapoptotic bcl-2 in rat mammary tissue. This investigation focused on the cell mechanisms underlying the antitumor effects of CLA. Changes (mRNA, protein) in expression of major proapoptotic p53, p21WAF1/CIP1, bax, bcl-Xs genes, and the antiapoptotic bcl-2 gene were observed in malignant MCF-7 and MDA-MB-231 cells and in benign MCF-10a human mammary tumor cells in culture. CLA, but not linoleic acid (LA), inhibited proliferation in all cells; CLA mix was most effective. CLA increased DNA damage (apoptosis). CLA increased mRNA expression of p53 and p21WAF1/CIP1 (three- to fivefold and twofold, respectively) but either decreased bcl-2 by 20-30% or had no effect in MCF-7 and MCF-10a cells, respectively; protein expression reflected mRNA values. In MDA-MBA-231 (mutant p53) cells, mRNA for p53 was not changed, but p21WAF1/CIP1 and bcl-2 mRNA was increased. Protein expression largely reflected mRNA changes but, surprisingly, CLA completely suppressed mutant p53 protein in MDA-MB-231 cells. Apparent antiapoptotic effects of increased bcl-2 expression in MDA-MBA-231 cells were countered by increased proapoptotic p21WAF1/CIP1, Bax, and Bcl-Xs proteins. Findings indicate that CLA elicits mainly proapoptotic effects in human breast tumor cells through both p53-dependent and p53-independent pathways, according to cell type.

Apoptosis↗