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Biomedical subjects

C L Clarke

Publications and source records attributed to C L Clarke.

At least 19 recordsLinked to original sources
PubMed2002

Loss of co-ordinate expression of progesterone receptors A and B is an early event in breast carcinogenesis.

Progesterone receptor (PR) mediates the effects of progesterone in mammary tissues and plays a crucial role in normal breast development and in breast cancer. PR proteins are expressed as two isoforms, PRA and PRB, that have different capacities to activate target genes, yet it is unknown whether progesterone action in normal and malignant breast is mediated by PRA and/or PRB. This study determines the relative expression of PRA and PRB in normal breast and in benign, premalignant and malignant archival breast lesions by dual immunofluorescent histochemistry. In normal breast and in proliferative disease without atypia (PDWA) PRA and PRB were co-expressed within the same cells in comparable amounts, implicating both isoforms in progesterone action. In atypical lesions, however, there was a significant increase in predominant expression of PRA or PRB, with lesion progression from the normal state to malignancy. PR isoform predominance, especially PRA predominance, was evident in a high proportion of ductal carcinomas in situ (DCIS) and invasive breast lesions. In the normal breast and in PDWA, the relative expression of PRA and PRB in adjacent cells was homogenous. There was a significant increase in cell-to-cell heterogeneity of PR isoform expression in ADH and DCIS lesions and in the majority of breast cancers. Heterogeneous cell-to-cell expression of PR isoforms occurred prior to overall predominant expression of one isoform in premalignant breast lesions, demonstrating that loss of control of relative PRA:PRB expression is an early event in the development of breast cancer. PRA:PRB ratios within a breast lesion are likely to be important as both markers and effectors of tumor growth and development, and progressively aberrant PR isoform expression may play a role in the etiology of breast cancer.

Adult↗
PubMed2001

Relative expression of progesterone receptors A and B in endometrioid cancers of the endometrium.

The nuclear receptor for the female hormone progesterone (PR) is widely expressed in uterine cancer. PR is expressed as two proteins (PRA and PRB) with different functions, and in vitro evidence reveals PRA to inhibit PRB function, so the cellular ratio of PRA:PRB is likely to be an important determinant of progesterone action. The relative expression of PRA and B and their involvement in the pathogenesis of endometrial cancer is not known. The aims of this study were to determine PRA and B expression by dual immunofluorescent histochemistry in endometrial adenocarcinomas compared with expression in normal and hyperplastic glands, and to correlate expression in tumors with clinical features including grade. Significantly lower PR levels were found in tumors compared with normal glands and areas of complex atypical hyperplasia within the same specimen. The normal glands expressed both of the isoforms at similar levels, whereas there was increased predominance of one isoform in hyperplastic areas and in tumors, which suggested that the loss of coordinated expression of PR isoforms was an early event in tumor progression. The majority of tumors [27 (58%) of 46] expressed only one PR isoform, and the proportion expressing either PRA or B was the same [14 (30%) of 46, and 13 (28%) of 46, respectively]. One-half of all tumors ([23 (50%) of 46] expressed either PRA only or a predominance of PRA, and a few tumors [10 (22%) of 46] expressed comparable levels of PRA and B. Similar levels of PRA and B were noted only in FIGO grade 1 tumors, whereas higher grades (2 and 3) were associated with a predominance of one isoform. In summary, expression of only one PR isoform was common in endometrial cancers, which indicates that the decreased PR levels observed in these cancers arise from the loss of one PR isoform. Expression of a single PR isoform was associated with higher clinical grade, which suggests a relationship between the loss of PR isoform expression and features of poorer prognosis. Disruption of relative PR isoform expression was observed in complex atypical hyperplasia, which suggests that early alterations in the ratio of PRA:PRB may precede and/or be implicated in the development of endometrial adenocarcinoma. Alterations in the ratio of PR isoform expression are likely to cause disordered regulation of target genes, resulting in altered progestin action in the uterus, and this may be involved in the pathogenesis of endometrial cancer.

Adult↗
PubMed2001

Professional and organizational learning: analysing the relationship with the development of practice.

BACKGROUND: Organizational and professional learning are interrelated processes that underpin the contemporary drive for a quality evidence-based delivery of health care in the United Kingdom (UK). DESIGN: A soft systems methodology was used to explore the pervasiveness of practice developments. Three case study sites were identified using matrix sampling and data collected through 29 individual interviews and two focus group interviews, with the interviews augmented with a tool designed to maximize analysis of the processes of developing practice. FINDINGS: The resultant model of developing health care practice includes three processes: using and creating knowledge, understanding and practice of patient care, and effecting development. The whole model was underpinned by professional and organizational learning in which 'expert thinkers' engaged in double loop learning to reconceptualize care rather than just perpetuate existing patterns of care delivery.

Attitude of Health Personnel↗
PubMed2001

Detection of progesterone receptor forms A and B by immunohistochemical analysis.

AIM: The measurement of progesterone receptors (PR) is recommended as part of the clinical management of breast and endometrial cancers, and immunohistochemistry on formalin fixed tissue is now the method of choice. PR is expressed as two isoforms, PRA and PRB, and although both these proteins are expressed in hormone dependent cancers, there is evidence that a large proportion of tumours express a predominance of one isoform. Therefore, it is essential to document the individual detection of PRA and PRB by the presently available anti-PR antibodies. The aim of this study is to investigate the detection of PR isoforms A and B in formalin fixed, paraffin wax embedded cell lines and tissue sections by immunohistochemistry, using a panel of commercial and in house antibodies to human PR. METHODS: PR negative cell lines stably transfected to express only PRA (MCF-7Mll/PRA) or PRB (MDA-MB-231/PRB), and tissue sections of human breast carcinoma and normal endometrium were stained using an immunoperoxidase method. A panel of primary PR specific antibodies was evaluated for ability to detect both PRA and PRB proteins, and for intensity and distribution of positive staining under optimal conditions. RESULTS: Of the 11 antibodies assessed, only four recognised PRA and PRB similarly. Six recognised PRA proteins but were unable to detect PRB expression in the cell lines expressing only PRA or PRB. In tissues expressing high amounts of PRA and PRB, all antibodies tested demonstrated positive PR staining. However, in tissues expressing a predominance of PRB, differential staining patterns were observed, with variations in staining intensity and in the proportion of cells positive for PR. CONCLUSIONS: Most PR specific antibodies tested failed to detect PRB in formalin fixed tissue by immunohistochemical techniques, despite their ability to do so by immunoblot analysis. These observations suggest that there are conformational differences between PRA and PRB that mask epitopes on the PRB protein recognised by most anti-PR antibodies. The selection of antibodies that recognise both PRB and PRA in formalin fixed tissue is essential for the accurate evaluation of PR positivity in clinical specimens.

Animals↗
PubMed2000

The hD52 (TPD52) gene is a candidate target gene for events resulting in increased 8q21 copy number in human breast carcinoma.

Chromosome band 8q21 is frequently overrepresented in human cancer, but to date no 8q21 target gene has been proposed. The hD52 (TPD52) gene is of potential significance in breast and other cancers due to its location and expression pattern. Fine mapping of hD52 placed this locus within the peak of the 8q21 amplicon delineated in the SK-BR-3 breast carcinoma cell line, and a positive association between hD52 gene dosage and transcript levels was subsequently demonstrated in four breast carcinoma cell lines, including SK-BR-3. Increased copy number (ICN) was measured using Southern blot analyses in 3/32 human breast carcinomas at hD52, and the related hD54 gene in 20q13.2-q13.3. Subsequent immunohistochemical analysis of hD52 expression in 19 breast carcinomas with varying hD52 gene dosages demonstrated a significant positive association between hD52 dosage and hD52 expression using a Spearman rank correlation coefficient (r(s) = 0.573, alpha = 0.01) and a Wilcoxon rank-sum test (alpha = 0.05). On the basis of its map location and expression pattern in breast carcinoma, we therefore propose hD52 as a candidate target gene at chromosome band 8q21.

Aneuploidy↗
PubMed2000

Heterogeneity of progesterone receptors A and B expression in human endometrial glands and stroma.

The human progesterone receptor (PR) is expressed as two isoforms, PRA and PRB, which function as ligand-activated transcription factors. In-vitro studies suggest that the isoforms differ functionally and that their relative expression in a target cell may determine the nature and magnitude of response to progesterone. We have shown recently that PRA and PRB are co-expressed in target cells of the human endometrium. The purpose of this study was to investigate the homogeneity of expression of PRA and PRB in target cells of the human uterus throughout the menstrual cycle. In the functionalis, PRA and PRB were expressed in comparable levels in glandular epithelium during the proliferative phase of the cycle, whereas there was persistence of PRB but not PRA in the glands during mid-secretory phase. In the stroma, there was predominance of the PRA isoform throughout the cycle. There was remarkable homogeneity in the relative expression of PRA and PRB in adjacent cells within the same tissue compartment, suggesting that the mechanisms regulating relative PR isoform expression are similarly active in these cells. By contrast, heterogeneity between glands was observed under some circumstances in the functionalis of the endometrium, suggesting PR isoform down-regulation by progesterone to be asynchronous. Heterogeneity was also seen between the glands of the basalis and functionalis of the endometrium implying region-specific responses to hormonal stimuli. This study demonstrates adjacent cell homogeneity in the relative expression of PRA and PRB in normal human endometrial tissue and a differential response to ovarian steroid hormones between cell types and between different regions within the same tissue.

Endometrium↗
PubMed2000

Hearing the voices of children with chronic illness.

This qualitative study has aimed to explore children's, parents' and health professionals' experience of childhood chronic illness. Seven families and their professional carers participated in semistrucured interviews. The children's interviews were augmented with a 'drawing' technique. A grounded theory approach facilitated data collection and analysis. This paper debates the perceived passivity of the voice of children in health care and research and illustrates data collection methods that seek to give children and other disadvantaged groups a voice. The children who participated in this study are described as competent interpreters of their world.

Adaptation, Psychological↗
PubMed2000

Histone deacetylase inhibitors decrease proliferation and modulate cell cycle gene expression in normal mammary epithelial cells.

Full-term pregnancy early in reproductive life is protective against breast cancer in women. The protective effects of parity have variously been attributed to the differentiation that accompanies pregnancy and lactation, alterations in ovarian hormone receptor levels, and altered sensitivity to ovarian hormones. Butyrate, a short-chain fatty acid, induces differentiation in breast cancer cell lines and decreases hormone receptor expression. Butyrate also inhibits proliferation in breast cancer cell lines and modulates expression of key cell cycle-regulatory proteins including cyclin D1. Given these properties, butyrate could be considered a promising agent for breast cancer prevention. Therefore, this study aimed to determine the effects of butyrate on normal human breast epithelial cells and to compare the effects of two stable butyrate derivatives with more favorable pharmacological properties: phenylacetate and its p.o. active precursor phenylbutyrate. Treatment with each agent resulted in concentration-dependent growth inhibition in a normal breast epithelial cell line and two breast cancer cell lines (MCF-7 and MDA-MB-231). Phenylbutyrate and butyrate inhibited proliferation to a similar extent, but phenylacetate was less effective in all of the cell lines. All three of the agents induced differentiation (accumulation of lipid droplets) in normal as well as in breast cancer cells and caused a decrease in estrogen receptor (ER) mRNA in MCF-7 cells. The butyrates decreased expression of cyclin D1, increased expression of p21(Waf1/Cip1), and hypophosphorylated pRB in the normal mammary epithelial cells. The effects on cyclin D1 expression correlated with the effects on cell proliferation, which suggests that modulation of cyclin D1 expression may underpin the antiproliferative effects of butyrates. We have shown that butyrate and butyrate-like agents are able to decrease proliferation and induce differentiation in normal breast cells as well as in malignant breast cells (ER-positive and ER-negative) and, as such, may be considered as candidate chemopreventative agents for women at high risk of developing breast cancer.

Anticarcinogenic Agents↗
PubMed1999

Localization of the delta-opioid receptor and dopamine transporter in the nucleus accumbens shell: implications for opiate and psychostimulant cross-sensitization.

Opiate- and psychostimulant-induced modulation of dopamine transmission in the nucleus accumbens shell (AcbSh) is thought to play a key role in their potent reinforcing and locomotor effects. To investigate the cellular basis for potential functional interactions involving opiates active at the delta-opioid receptor (DOR) and psychostimulants that bind selectively to the dopamine transporter (DAT), we examined the electron microscopic localization of their respective antisera in rat AcbSh. DOR immunoperoxidase labeling was seen primarily, and DAT immunogold particles exclusively, in axon terminals. In these terminals, DOR immunoreactivity was prominently associated with discrete segments of the plasma membrane and the membranes of nearby small synaptic and large dense core vesicles. DAT immunogold particles were almost exclusively distributed along nonsynaptic axonal plasma membranes. Thirty-nine percent DOR-labeled profiles (221/566) either apposed DAT-immunoreactive terminals or also contained DAT. Of these 221 DOR-labeled profiles, 13% were axon terminals containing DAT and 15% were dendritic spines apposed to DAT-immunoreactive terminals. In contrast, 70% were morphologically heterogeneous axon terminals and small axons apposed to DAT-immunoreactive terminals. Our results indicate that DOR agonists in the AcbSh can directly modulate the release of dopamine, as well as postsynaptic responses in spiny neurons that receive dopaminergic input, but act principally to control the presynaptic secretion of other neurotransmitters whose release may influence or be influenced by extracellular dopamine. Thus, while opiates and psychostimulants mainly have differential sites of action, cross-sensitization of their addictive properties may occur through common neuronal targets.

Animals↗
PubMed1999

N-methyl-D-aspartate receptor 1 in the caudate-putamen nucleus: ultrastructural localization and co-expression with sorcin, a 22,000 mol. wt calcium binding protein.

Entry of calcium through N-methyl-D-aspartate-type glutamate receptors in the caudate-putamen nucleus is essential for normal motor activity, but can produce cytotoxicity with continued stimulation and subsequent release of intracellular calcium. To determine potential functional sites for N-methyl-D-aspartate receptor activation in this region, we examined the ultrastructural localization of the R1 subunit of the N-methyl-D-aspartate receptor (NMDAR1) in rat brain. In addition, we comparatively examined the localization of NMDAR1 and sorcin, a 22,000 mol. wt calcium binding protein present in certain striatal neurons and involved in calcium-induced calcium release. NMDAR1-like immunoreactivity was seen at synaptic and non-synaptic sites on neuronal plasma membranes. Of 1514 NMDAR1-labeled profiles, 62% were dendrites and dendritic spines and the remainder were mainly unmyelinated axons and axon terminals. Sorcin-like immunoreactivity was present in 39% of the profiles that contained NMDAR1 labeling, most (533/595) of which were dendrites and dendritic spines. Of 1807 sorcin-labeled profiles, 42% were identified, however, as small processes including spine necks and unmyelinated axons or axon terminals. These profiles also occasionally contained NMDAR1 or showed synaptic or appositional contacts with other NMDAR1-immunoreactive neurons. The results of this study suggest that in the caudate-putamen nucleus, activation of NMDA receptors permits calcium influx at plasmalemmal sites mainly on dendrites where sorcin may play a role in calcium-induced calcium release. The presence of sorcin in some, but not all NMDA-containing neurons in the caudate-putamen nucleus has potential implications for the known differential vulnerability of certain striatal neurons to excitotoxins.

Animals↗
PubMed1999

Absence of progesterone receptor associated with secondary breast cancer in postmenopausal women.

The relationship between expression of receptors for oestrogen and progesterone (ER and PR) and disease progression in breast cancer was investigated by comparing immunocytochemical determinations of ER and PR in fine needle aspirates from primary and secondary breast tumours. Rates of receptor expression were significantly higher in primary than in secondary lesions: for ER 63.3% (n = 689) compared with 45.3% (n = 223), and for PR 53.7% (n = 443) compared with 33.1% (n = 121). The effect of menopausal status was examined by subdividing the patient cohort into those over or under the age of 50 years. In both instances, ER expression in secondary tumours was relatively low; however, only postmenopausal patients had significantly lower rates of PR expression in secondary tumours. Consistent with this, an increase in the ER+PR- profile in secondary tumours compared with primary cases from postmenopausal patients was seen, and in a multivariate analysis, a specific absence of PR expression in secondary tumours was revealed. Comparison of ER and PR expression in simultaneously sampled primary tumours and lymph node metastases from the same patient showed that receptor expression was stable with progression to a metastatic site as results were concordant for ER in 92% (n = 88) and PR in 93.8% of cases (n = 65). These results suggest that absence of PR expression in primary breast cancer is associated with disease progression and may be a marker of an aggressive tumour phenotype.

Adult↗
PubMed1999

Family care-giving for people with dementia: some implications for policy and professional practice.

The objective of this paper is to describe one study undertaken in the north of England which sought an understanding of family care-giving for people with dementia. Data were collected by interview and diary with 14 family carers, by questionnaire with 60 professional carers, and by interview and diary from nine case studies. Family carers were found to value their continuing relationship with the person with dementia. This emphasis on their relationship together influenced the contact which they had with professional carers. The implications of this research for policy and professional practice are explored through illumination of the tensions in professional responses to family carers.

Adaptation, Psychological↗
PubMed1999

Nursing older people: constructing need and care.

As the population of the world 'ages', older people are increasingly viewed as a 'problem' whose needs challenge the resources of care services. However, this view is predicated on the negative and nihilistic attitudes that are held throughout society about older people and the effectiveness of therapeutic intervention. It is these pessimistic views which colour professional understandings of the needs of older people and the most appropriate ways of delivering care to meet those needs. However, any knowledge of need and care is a constructed story, and is limited by the knowledge base on which it rests. For example, western healthcare is dominated by an orientation to identified problems, the minimizing of physical risk or harm, and a reductionalist approach to problem solving. A social critical challenge to prevailing understandings of need and care produces a very different story about older age; one which emphasizes an individual's strengths and their family and community relationships. In exploring these issues in policy and practice two key areas are highlighted. One is the role of critical gerontology in challenging the stories of negativity about old age, and replacing these with positive stories that allow older people to retain their social purpose. The second key area is the need to address issues of older age at both a practice and policy level, and to understand the interrelationship between them.

Aged↗
PubMed1999

Expression and hormonal regulation of the Sox4 gene in mouse female reproductive tissues.

The SOX genes define a family of transcriptional regulators whose diverse patterns and tightly controlled temporal profiles of expression suggest that they play key roles in determination of cell fate during development. One of the family members, Sox4, is expressed in the gonads of adult mice, but expression in the reproductive tissues has not been studied. As previous studies in this laboratory had shown that the SOX4 gene was regulated by ovarian hormones in breast cancer cells, murine Sox4 expression was analyzed in the reproductive tissues of mice by Northern blot analysis and ribonuclease protection assays. Sox4 mRNA expression was detected in the uterus and, at a lower level, in the mammary glands of pubertal and adult mice. Expression was modulated in the uterus of intact mice at various stages of the estrous cycle and was reduced by estradiol treatment of ovariectomized mice. Progesterone treatment partially reversed the estradiol effect. Although no modulation of Sox4 expression in the mammary glands was detected by Northern blot analysis, further evaluation of Sox4 protein expression at a cellular level is required. No modulation of Sox4 levels was observed in the thymus. The results presented here suggest that expression of the Sox4 gene is under ovarian hormone control in the uterus and implicate Sox4 in the complex effects controlled by ovarian hormones in the female reproductive system.

Animals↗
PubMed1999

Coexpression of alternatively spliced estrogen and progesterone receptor transcripts in human breast cancer.

Primary transcripts of the human estrogen receptor (ER) and progesterone receptor (PR) are subject to a number of alternative splicing events resulting in a range of variant messenger ribonucleic acid species in receptor-positive tissues. Despite in vitro demonstrations of a possible role for some of these variants in hormonal sensitivity, the clinical significance of this process is uncertain. In this study the coexpression of variant ER and PR transcripts has been documented by RT-PCR and Southern blot analysis in a series of receptor-positive breast tumors. In 35 ER-positive tumors, a common profile of variant ER transcripts was present, with all tumors containing the delta2ER and delta7ER, 94% containing the delta4ER, and 83% containing the delta5ER. In 25 of these cases, which were also PR positive, the most highly expressed PR variants, the delta4PR, delta6PR, and delta(4/2)PR, a transcript from which a 126-bp portion of PR exon 4 was deleted, were detected in over 90% of the cases. The alternatively spliced ER variants were expressed at higher relative levels than the PR species, which had mean levels of expression less than 10% that of wild-type PR. The most abundant species was the delta7ER, which was present at levels ranging from 29-83% of the wild type. There was no relationship between the level of delta7ER in individual tumors and the pattern of expression of the estrogen-responsive proteins PR and pS2. The common profile of alternatively spliced ER and PR transcripts in breast tumors means that this feature cannot be used as a discriminator of hormone responsiveness or other clinical end points. Further, the low level of expression of the majority of variant species calls into question their potential for impacting significantly on receptor function.

Adult↗
PubMed1999

Colocalization of progesterone receptors A and B by dual immunofluorescent histochemistry in human endometrium during the menstrual cycle.

The human progesterone receptor (PR) is expressed as two isoforms, PRA and PRB, that function as ligand-activated transcription factors. In vitro studies suggest that the isoforms differ functionally and that the relative levels in a target cell may determine the nature and magnitude of response to progesterone. However, it is not known whether the two isoforms are normally coexpressed in vivo. To understand the functional significance of relative PR isoform expression in normal physiology, it is essential to determine whether PRA and PRB are coexpressed in the same cell. This study reports the development of a dual immunofluorescent staining technique to demonstrate PRA and PRB proteins by single cell analysis in the same tissue section of human endometrium during the menstrual cycle. PRA and PRB are coexpressed in target cells of the human uterus. In the glands, PRA and PRB were expressed before subnuclear vacuole formation and glycogenolysis, implicating both isoforms in this process, whereas persistence of PRB during the midsecretory phase suggested its significance in glandular secretion. In the stroma, the predominance of PRA throughout the cycle implicates this isoform in post-ovulatory progesterone-mediated events. These results support the view that PRA and PRB mediate distinct pathways of progesterone action in the glandular epithelium and stroma of the human uterus throughout the menstrual cycle.

Cell Nucleus↗