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Biomedical subjects

R Clarke

Publications and source records attributed to R Clarke.

At least 91 records · Page 5Linked to original sources
PubMed1998

Two-dimensional gel electrophoresis analyses identify nucleophosmin as an estrogen regulated protein associated with acquired estrogen-independence in human breast cancer cells.

We have used two-dimensional gel electrophoresis to identify proteins associated with estrogen-induced proliferation in MCF-7 breast cancer cells and their progression to estrogen-independent proliferation. We compared the total cellular proteins from MCF-7 cells and an estrogen independent derivative of the MCF-7 cells MCF-7/LCC1 (Brünner et al. Cancer Research 1993, 53, 283-290), each grown with and without estradiol. These comparisons reveal seven estrogen-regulated proteins. Three of these proteins (HI-1: 36 kDa/pI 4.5, HI-10: 40 kDa/pI 5.5 and HI-19: 62 kDa/pI 5.0) exhibit a 'progression-like' pattern, being induced by estradiol in MCF-7 cells and constitutively present/upregulated in the MCF-7/LCC1 growing without estradiol. HI-11 (65 kDa/pI 5.5) is strongly induced by estradiol in MCF-7 cells but constitutively downregulated and unresponsive to estradiol in the MCF-7/LCC1 cells. Two proteins exhibit a suppressor pattern and are downregulated by estradiol in the estrogen-dependent MCF-7 cells (HI-3: 44 kDa/pI 4.4 and HI-4: 56 kDa/ pI 5.2) and present in MCF-7/LCC1 cells growing without estradiol at levels comparable to that seen in estrogen-treated MCF-7 cells. One protein (HI-9: 68 kDa/pI 5.5) exhibits a marked estrogen regulated pI shift, rather than changes in abundance. We purified and sequenced the HI-10 protein, which we identified as the nucleolar protein, nucleophosmin (NPM). One- and two-dimensional Western blot analyses of MCF-7/LCC1 cell lysates confirmed that HI-10 is immunoreactive with an antinucleophosmin antibody. Western blotting also confirmed the estrogenic regulation of NPM seen in the initial two-dimensional gel electrophoresis studies. Thus, NPM is induced by estradiol in the MCF-7 cells and upregulated in the MCF-7/LCC1 cells growing without estrogen, clearly associating its expression with an acquired estrogen-independent phenotype. NPM has several potentially important roles in regulating cell function and signaling. It is a substrate for phosphorylation by p34cdc2 kinase, protein kinase C and nuclear kinase II, and a repressor of the transcriptional regulating activities of both the IRF-1 tumor suppressor protein and the YY1 transcription factor. Studies are currently underway to determine which of these NPM functions may be involved in the hormonal progression of breast cancer.

Amino Acid Sequence↗
PubMed1998

Diogenes' syndrome in patients with intellectual disability: 'a rose by any other name'?

Diogenes' syndrome is characterized by marked self-neglect, domestic squalor, social withdrawal and hoarding of rubbish (syllogomania). The syndrome has been reported to occur in association with a wide variety of conditions, but the present authors were unable to find any previous reports of Diogenes' syndrome in patients with intellectual disability.

Activities of Daily Living↗
PubMed1998

Familial slipped capital femoral epiphysis: a report and considerations in management.

BACKGROUND: Familial inheritance of slipped capital femoral epiphysis (SCFE) is known. It has not been described in non-identical twins. A family where the mother and three of five siblings developed SCFE were investigated and managed. METHODS: Anthropometric measurement consisted of height-weight ratios. Serum sex hormone levels and bone Gla Protein was measured. Bone mineral densities were evaluated. RESULTS: The affected siblings had higher bodyweight percentiles. Other investigations were within normal limits. CONCLUSION: The unfavourable height-to-weight ratio was one of the mainstays in developing a management protocol for all siblings. The management protocol developed for the family is discussed.

Algorithms↗
PubMed1998

Design, objectives, and lessons from a pilot 25 year follow up re-survey of survivors in the Whitehall study of London Civil Servants.

DESIGN: To assess the feasibility of conducting a re-survey of men who are resident in the United Kingdom 25 years after enrollment in the Whitehall study of London Civil Servants. METHODS: A random sample of 401 study survivors resident in three health authority areas was selected for this pilot study. They were mailed a request to complete a self administered questionnaire, and then asked to attend their general practice to have their blood pressure, weight, and height measured and a blood sample collected into a supplied vacutainer, and mailed to a central laboratory. Using a 2 x 2 factorial design, the impact of including additional questions on income and of an informant questionnaire on cognitive function was assessed. RESULTS: Accurate addresses were obtained from the health authorities for 96% of the sample. Questionnaires were received from 73% and blood samples from 61% of the sample. Questions on income had no adverse effect on the response rate, but inclusion of the informant questionnaire did. Between 1970 and 1995 there were substantial changes within men in the mean blood pressure and blood total cholesterol recorded, as reflected by correlation coefficients between 1970 and 1995 values of 0.26, and 0.30 for systolic and diastolic blood pressure and 0.38 for total cholesterol. CONCLUSION: This pilot study demonstrated the feasibility of conducting a re-survey using postal questionnaires and mailed whole blood samples. The magnitude of change in blood pressure and blood total cholesterol concentrations within individuals was greater than anticipated, suggesting that such remeasurements may be required at different intervals in prospective studies to help interpret risks associations properly. These issues will be considered in a re-survey of the remaining survivors of the Whitehall study.

Aged↗
PubMed1998

Variability and determinants of total homocysteine concentrations in plasma in an elderly population.

The variability of plasma total homocysteine (tHcy) was examined in 96 individuals over a 1-yr period. Blood tHcy concentrations varied from 7.1 micromol/L in the bottom quintile to 14.5 micromol/L in the top quintile. The mean tHcy was 10.4 micromol/L, the between-person SD was 2.5 micromol/L, and the within-person SD was 0.93 micromol/L. There was little seasonal variation, and the reliability coefficient was 0.88. Mean tHcy concentrations were inversely related to mean plasma folate (r = -0.36) and vitamin B12 (r = -0.35) concentrations. Median tHcy concentrations were approximately 1 micromol/L higher in men than in women and in older (70 to 74 years) than in younger (65 to 69 years) individuals and higher in those with the TT and CT genotypes for the methylenetetrahydrofolate reductase polymorphism than in those with the CC genotype (10.7 and 10.6 vs 9.6 micromol/L). Epidemiological studies based on single tHcy measurements may underestimate the magnitude of any risk associations with disease by 10-15%.

Aged↗
PubMed1998

Timing of dietary fat exposure and mammary tumorigenesis: role of estrogen receptor and protein kinase C activity.

The possible association between a high fat diet and increased breast cancer risk has remained controversial. This largely reflects the conflicting data obtained from migrant, case control and animal studies, which generally support this association, and cohort studies which often fail to show a link between fat and breast cancer. The mammary gland is particularly sensitive to estrogens during fetal development, leading us to hypothesize that dietary fat levels during this period may significantly influence breast cancer risk. Using chemically-induced mammary tumors in rats as our experimental model, we have demonstrated the ability of a maternal diet, high in the polyunsaturated fatty acid (PUFA) linoleic acid, to alter mammary gland differentiation, accelerate the onset of sexual maturation, and increase breast cancer risk. The mammary glands of female rats exposed to a high-fat diet in utero have more of the undifferentiated structures (terminal end buds) and fewer of the differentiated structures (alveolar buds) than the glands of rats exposed to a low-fat diet in utero. Furthermore, these mammary glands contain lower levels of total estrogen receptors and have reduced total protein kinase C activity. These effects appear to be mediated by an increase in the serum estradiol levels of pregnancy, which are elevated at least 30% in pregnant dams fed a high-fat diet. Furthermore, the administration of estradiol to pregnant dams produces effects on mammary gland development, onset of puberty and sensitivity to chemical carcinogenesis comparable to those seen in the offspring of rats fed a high fat diet during pregnancy. Our results, thus, support the hypothesis based on epidemiological data that high maternal estrogen levels increase daughters' breast cancer risk. The results also suggest that a high-fat diet may be an important factor in increasing pregnancy estrogenic activity.

Animals↗
PubMed1998

Autoantibodies to the nuclear phosphoprotein nucleophosmin in breast cancer patients.

Nucleophosmin (NPM) is an estrogen-regulated nucleolar phosphoprotein; a substrate for phosphorylation by p34cdc2 kinase, protein kinase C, and casein kinase II; and a repressor of the transcriptional regulating activities of the YY1 and IFN regulatory factor-1 transcription factors. We have completed a pilot study to determine whether autoantibodies to NPM are present in breast cancer patients and explored the ability of these autoantibodies to predict recurrence in breast cancer patients. One hundred breast cancer patients were studied: 50 who recurred, and 50 matched for age and length of follow-up but who did not recur. Patients' sera were collected at the times of diagnosis (T1), six months before recurrence (T2), and at recurrence (T3). Recurrent and nonrecurrent patients did not differ in autoantibody levels at the times of diagnosis or recurrence. However, antiNPM autoantibody levels increase significantly between diagnosis and six months before recurrence in recurrent patients, whereas no change occurs over the comparable time period in nonrecurrent patients (repeated measures ANOVA; P = 0.041). At recurrence, the levels return to those seen at diagnosis. The greater the change in levels between T1 and T2, the greater the risk of recurrence within the next 6 months (conditional logistic regression: increase in risk for highest versus lowest tertile of change from T1 to T2; odds ratio, 3.25; 95% confidence interval, 1.04-10.18; P = 0.043). Consistent with the estrogenic/antiestrogenic regulation of the antigen in breast cancer cells, the levels of antiNPM autoantibodies are decreased 6 months before recurrence in patients treated with the antiestrogen tamoxifen (P = 0.012). The association between antiNPM levels and recurrence remained after adjustment for confounding factors. Further study of antiNPM autoantibody levels as a new and simple, intermediate serum biomarker for predicting both the timing of recurrence and monitoring response to endocrine manipulations in breast cancer patients is warranted.

Adult↗
PubMed1997

A maternal diet high in n - 6 polyunsaturated fats alters mammary gland development, puberty onset, and breast cancer risk among female rat offspring.

We hypothesized that feeding pregnant rats with a high-fat diet would increase both circulating 17beta-estradiol (E2) levels in the dams and the risk of developing carcinogen-induced mammary tumors among their female offspring. Pregnant rats were fed isocaloric diets containing 12% or 16% (low fat) or 43% or 46% (high fat) of calories from corn oil, which primarily contains the n - 6 polyunsaturated fatty acid (PUFA) linoleic acid, throughout pregnancy. The plasma concentrations of E2 were significantly higher in pregnant females fed a high n - 6 PUFA diet. The female offspring of these rats were fed with a laboratory chow from birth onward, and when exposed to 7,12-dimethylbenz(a)anthracene had a significantly higher mammary tumor incidence (60% vs. 30%) and shorter latency for tumor appearance (11.4 +/- 0.5 weeks vs. 14.2 +/- 0.6 weeks) than the offspring of the low-fat mothers. The high-fat offspring also had puberty onset at a younger age, and their mammary glands contained significantly higher numbers of the epithelial structures that are the targets for malignant transformation. Comparable changes in puberty onset, mammary gland morphology, and tumor incidence were observed in the offspring of rats treated daily with 20 ng of E2 during pregnancy. These data, if extrapolated to humans, may explain the link among diet, early puberty onset, mammary parenchymal patterns, and breast cancer risk, and indicate that an in utero exposure to a diet high in n - 6 PUFA and/or estrogenic stimuli may be critical for affecting breast cancer risk.

Animals↗
PubMed1997

MCF7/LCC9: an antiestrogen-resistant MCF-7 variant in which acquired resistance to the steroidal antiestrogen ICI 182,780 confers an early cross-resistance to the nonsteroidal antiestrogen tamoxifen.

Acquired resistance to antiestrogens is a major problem in the clinical management of initially endocrine responsive metastatic breast cancer. We have shown previously that estrogen-independent and -responsive MCF7/LCC1 human breast cancer cells selected for resistance to the triphenylethylene tamoxifen produce a variant (MCF7/LCC2) that retains sensitivity to the steroidal antiestrogen ICI 182,780 (N. Brunner et al., Cancer Res., 53: 3229-3232, 1993). We have now applied stepwise selections in vitro from 10 pM to 1 microM ICI 182,780 against MCF7/LCC1 and obtained a stable ICI 182,780-resistant variant designated MCF7/LCC9. In contrast to 4-hydroxytamoxifen-selected MCF7/LCC2 cells, MCF7/LCC9 cells exhibit full cross-resistance to tamoxifen, despite never having been exposed to this drug. Significantly, tamoxifen cross-resistance arose early in the selection, appearing following selection against only 0.1 nM ICI 182,780. Although limited resistance to ICI 182,780 also was observed, full ICI 182,780 resistance was not detected until the selective pressure increased to 100 nM ICI 182,780. Cross-resistance to tamoxifen persisted throughout these additional selections. Despite their antiestrogen cross-resistance, MCF7/LCC9 cells retain a level of estrogen receptor expression comparable to that of their parental MCF7/LCC1 cells. Whereas MCF7/LCC1 cells retain an estrogen-inducible expression of progesterone receptors, MCF7/LCC9 cells exhibit an up-regulated expression of both progesterone receptor mRNA and protein that is no longer estrogen responsive. Estrogen-independent and -responsive components of the MCF7/LCC9 phenotype are apparent in vivo. These cells form slowly growing tumors in ovariectomized athymic nude mice but respond mitogenically upon estrogenic supplementation. The in vivo growth of MCF7/LCC9 tumors is not affected by treatment with ICI 182,780. Although there is some evidence of tamoxifen stimulation of tumor growth, this did not reach statistical significance. If this pattern of cross-resistance occurs in some breast cancer patients, administering triphenylethylene antiestrogens as a first-line therapy with a cross-over to steroidal compounds upon recurrence may be advantageous.

Animals↗
PubMed1997

Induction of apoptosis by tamoxifen and ICI 182780 in primary breast cancer.

Hormonal breast cancer therapies have traditionally been considered cytostatic, but recent pre-clinical data suggest that anti-oestrogens can induce apoptosis. The aim of this study was to assess whether tamoxifen (TAM) and ICI 182780 (ICI) could induce apoptosis in human breast cancer, and whether this was related to oestrogen receptor status. We measured apoptosis in primary breast cancer patients before and after pre-surgical treatment with 20 mg/day TAM (study 1) or 6 or 18 mg/day ICI (study 2). In each study there was a randomised non-treatment (NT) control group. TAM significantly increased apoptotic index (AI) in ER+ but not in ER- tumours. There was a significant increase in AI following treatment with ICI. Insufficient pairs of samples were available to determine whether this change was confined to ER+ tumours, but in a cross-sectional analysis AI was significantly higher in excision biopsies for ICI-treated than NT patients for ER+ but not ER- tumours. Our results provide clinical evidence that apoptosis may be induced in ER+ primary breast cancer by both non-steroidal and steroidal anti-oestrogens.

Adult↗
PubMed1997

Multidrug resistance in breast cancer: a meta-analysis of MDR1/gp170 expression and its possible functional significance.

BACKGROUND: P-glycoprotein (gp170; encoded by the MDR1 gene [also known as PGY1]) is a membrane protein capable of exporting a variety of anticancer drugs from cells. MDR1/gp170 expression has been studied in breast cancer, but the prevalence of this expression and its role in breast tumor drug resistance are unclear. PURPOSE: We conducted a critical review and meta-analysis of studies examining MDR1/gp170 expression in breast cancer to estimate the likely prevalence and clinical relevance of this expression. We also explored reasons for differences in the findings from individual studies. METHODS: Published papers on MDR1/gp170 expression in breast cancer were identified by searching several literature databases and reviewing the bibliographies of identified papers. Variability across the studies in the proportion of tumors expressing MDR1/gp170 was assessed by use of chi-squared tests of homogeneity, weighted means, and weighted linear regression. Pooled relative risks (RRs) for the association between the induction of MDR1/gp170 expression and prior chemotherapy and associations between MDR1/gp170 expression and several clinical outcomes were estimated by use of Mantel-Haenszel methods. Heterogeneity among the pooled RRs was explored by use of chi-squared tests. Reported P values are two-sided. RESULTS: Thirty-one studies were identified and evaluated. The proportion of breast tumors expressing MDR1/gp170 in all of the studies was 41.2%, but there was substantial heterogeneity in the values across individual studies (P<.0001). Regression analyses demonstrated that a considerable portion of the observed heterogeneity was a consequence of the change, over time, from RNA hybridization-based assays to immunohistochemistry-based assays of MDR1/gp170 expression. Measuring MDR1/gp170 expression before versus after chemotherapy and use of cytotoxic drugs that are not substrates for gp170 also contributed to the heterogeneity. Treatment with chemotherapeutic drugs or hormonal agents was associated with an increase in the proportion of tumors expressing MDR1/gp170 (RR = 1.77; 95% confidence interval [CI] = 1.46-2.15). Patients with tumors expressing MDR1/gp170 were three times more likely to fail to respond to chemotherapy than patients whose tumors were MDR1/gp170 negative (RR = 3.21; 95% CI = 2.28-4.51); this RR increased to 4.19 (95% CI = 2.71-6.47) when considering only patients whose tumor expression of MDR1/gp170 was measured after chemotherapy. MDR1/gp170 expression was not associated with lymph node metastases, estrogen receptor status, tumor size, tumor grade, or tumor histology. CONCLUSIONS AND IMPLICATIONS: MDR1/gp170 expression in breast tumors is associated with treatment and with a poor response to chemotherapy. The data are consistent with a contributory role for MDR1/gp170 in the multidrug resistance in some breast tumors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Dietary lipids and blood cholesterol: quantitative meta-analysis of metabolic ward studies.

OBJECTIVE: To determine the quantitative importance of dietary fatty acids and dietary cholesterol to blood concentrations of total, low density lipoprotein, and high density lipoprotein cholesterol. DESIGN: Meta-analysis of metabolic ward studies of solid food diets in healthy volunteers. SUBJECTS: 395 dietary experiments (median duration 1 month) among 129 groups of individuals. RESULTS: Isocaloric replacement of saturated fats by complex carbohydrates for 10% of dietary calories resulted in blood total cholesterol falling by 0.52 (SE 0.03) mmol/l and low density lipoprotein cholesterol falling by 0.36 (0.05) mmol/l. Isocaloric replacement of complex carbohydrates by polyunsaturated fats for 5% of dietary calories resulted in total cholesterol falling by a further 0.13 (0.02) mmol/l and low density lipoprotein cholesterol falling by 0.11 (0.02) mmol/l. Similar replacement of carbohydrates by monounsaturated fats produced no significant effect on total or low density lipoprotein cholesterol. Avoiding 200 mg/day dietary cholesterol further decreased blood total cholesterol by 0.13 (0.02) mmol/l and low density lipoprotein cholesterol by 0.10 (0.02) mmol/l. CONCLUSIONS: In typical British diets replacing 60% of saturated fats by other fats and avoiding 60% of dietary cholesterol would reduce blood total cholesterol by about 0.8 mmol/l (that is, by 10-15%), with four fifths of this reduction being in low density lipoprotein cholesterol.

Cholesterol, Dietary↗
PubMed1997

Development of a sedation scoring protocol.

The creation of a research and development post within the Intensive Therapy Unit (ITU) environment at St Helier has provided the opportunity to review all aspects of practice to ensure that the care delivered is evidence-based and not merely rooted in routines and rituals. The first aspect of care to be examined was our sedation practice. It was felt that sedation procedures varied at times and that a research-based protocol was necessary to ensure that patients receive optimal levels of sedation consistently. A 'sedation scoring group' was set up in order to achieve this. Questionnaires were sent to all members of staff and the resulting data used to formulate a sedation scoring system and algorithm as well as a protocol which included information on sedative drugs and the effects of over- and under-sedating patients.

Algorithms↗