Search PubMed⌕ Search

Biomedical subjects

C L Clarke

Publications and source records attributed to C L Clarke.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1999

Effect of overexpression of progesterone receptor A on endogenous progestin-sensitive endpoints in breast cancer cells.

The human progesterone receptor (PR) is expressed as two isoforms, PRA and PRB, which differ in the N-terminal region and exhibit different activities in vitro, with PRA demonstrating dominant negative inhibitory effects on the activity of PRB and other nuclear receptors. PRA and PRB are expressed in target tissues at comparable levels although cells expressing a predominance of one isoform can be identified. In breast cancers, PRA is expressed at high levels in some tumors, and this may be associated with features of poorer prognosis. To investigate the role of PRA overexpression in PR-positive target cells, the effect of PRA induction on cell proliferation and expression of endogenous progestin-sensitive genes, SOX4 and fatty acid synthetase (FAS), was examined using PR-positive T-47D cell lines, which express a predominance of PRB, in which PRA could be increased 2- to 20-fold over basal levels. No effect of PRA induction was noted on cell proliferation, but marked changes in morphology, consistent with loss of adherent properties, were observed. Increases up to 4-fold in the relative PRA levels augmented progestin induction of SOX4 mRNA expression, and RU486 treatment revealed a progestin agonist effect. There was no consistent effect of PRA induction on progestin-mediated increases in FAS mRNA levels under these conditions. Clones with PRA:PRB ratios greater than 15 were associated with diminished progestin responses on both SOX4 and FAS mRNA expression. These data show that PRA overexpression is associated with alteration in adhesive properties in breast cancer cells and effects on endogenous progestin targets that were dependent on the cellular ratio of PRA:PRB. The results of this study are consistent with the view that PRA expression can fluctuate within a broad range in target cells without influencing the nature of progestin action on downstream targets, but that overexpression of PRA, such as is seen in a proportion of breast cancers, may be associated with inhibition of progestin action and features of poor prognosis.

Breast Neoplasms↗
PubMed1999

Expression of the oestrogen responsive protein pS2 in human breast cancer.

The trefoil peptide pS2 was discovered in a breast cancer cell line as a result of its oestrogen responsive character. The expression of pS2 in breast tumours in vivo is also likely to be an oestrogenic effect and as such, the presence of pS2 in oestrogen receptor positive breast cancer is evidence of an intact oestrogen response pathway and an indicator of putative hormone responsiveness. Consistent with this, clinical studies of breast cancer have revealed a correlation between pS2 expression and favourable tumour characteristics as well as response to endocrine therapy.

Breast Neoplasms↗
PubMed1999

Regulation of the expression and activity by progestins of a member of the SOX gene family of transcriptional modulators.

The mammalian testis-determining gene Sry and the related Sox genes define a family of transcriptional regulators widely expressed during embryogenesis. Tightly controlled temporal profiles of expression are a feature of the Sox gene family and may be required for initiation of a cascade of gene expression, yet the molecular mechanisms that control Sox gene expression are unknown. We now show that human SOX4 is expressed in the normal breast and in breast cancer cells. In these cells SOX4 is a progesterone-regulated gene, the expression of which is increased by progestins, leading to a marked increase in SOX-mediated transcriptional activity. Treatment of T-47D breast cancer cells with the synthetic progestin ORG 2058 directly increased SOX4 transcription, resulting in a 4-fold increase in SOX4 mRNA levels within 4 h of treatment. No effect of ORG 2058 was noted on other SOX genes measured, nor were other hormone-regulated HMG box proteins detected in this system, suggesting that the observed ability of progestin to increase SOX mRNA expression was confined to SOX4. The increase in SOX4 transcription was reflected in increased SOX4 protein expression, as progestin treatment of T-47D cells transfected with a SOX-responsive reporter resulted in a marked increase in reporter gene expression. Progesterone is essential for normal development and differentiation of the female reproductive system, plays an essential role in regulating growth and differentiation of the mammary gland and is required for opposing the proliferative effects of estrogen in specific cell types. The detection of SOX4 expression in the normal and malignant breast and the demonstration that SOX4 expression is under progesterone control suggests that changes in SOX4 gene expression may play a role in commitment to the differentiated phenotype in the normal and malignant mammary gland.

Base Sequence↗
PubMed1998

Cellular sites for activation of delta-opioid receptors in the rat nucleus accumbens shell: relationship with Met5-enkephalin.

The shell compartment of the nucleus accumbens (AcbSh) is prominently involved in the rewarding aspects of delta-opioid receptor (DOR) agonists, including one of its putative endogenous ligands, Met5-enkephalin (Enk). We examined the ultrastructural immunocytochemical localization of an antipeptide DOR antiserum and an antibody against Enk to determine the major cellular sites for DOR activation and the spatial relationship between DOR and Enk in this region. Sixty percent of DOR-immunoreactive profiles were axon terminals and small unmyelinated axons, whereas the remainder were mainly dendrites and dendritic spines. In axons and terminals, DOR labeling was distributed along plasma and vesicular membranes. DOR-containing terminals were mainly large and primarily formed symmetric synapses or occasionally asymmetric synapses. DOR immunoreactivity also was associated with terminals that were small and formed punctate symmetric or nonrecognizable synapses. Dual immunoperoxidase and immunogold labeling showed that 35% of DOR-labeled axons apposed other terminals that contained Enk. In addition, 25% of the DOR-labeled terminals contained Enk. Thirty-five percent of DOR labeling was observed within dendrites and dendritic spines. DOR-labeled spines showed intense immunoreactivity within asymmetric postsynaptic junctions, which were formed by terminals that lacked Enk immunoreactivity. DOR-labeled spines, however, were apposed to Enk-containing terminals in 13% of all associations between dually labeled profiles. These results provide ultrastructural evidence that activation of DOR in the AcbSh is primarily involved in modulating the presynaptic release of mainly inhibitory, but also excitatory, neurotransmitters. These data also suggest that DOR plays a role in determining the postsynaptic response to excitatory afferents.

Animals↗
PubMed1998

Loss of nuclear BRCA1 expression in breast cancers is associated with a highly proliferative tumor phenotype.

Recent studies have suggested that BRCA1-associated hereditary breast cancer may be a more aggressive form of disease than sporadic breast cancer. BRCA1-associated breast cancer has been reported to be significantly associated with grade 3 disease. Because grade 3 disease indicates a poor prognosis, this implies that women with a germ-line mutation in BRCA1 who develop breast cancer may have a poorer prognosis than those with sporadic disease. However, little is known about the association of BRCA1 expression with biological markers of prognosis. The present study examined the expression of BRCA1 in a total of 40 archival breast tumor specimens from three patient cohorts (sporadic, familial, and early onset breast cancer) to determine localization of the protein. Furthermore, BRCA1 staining was compared with expression of markers of tumor biology. We found that BRCA1 is generally located in the nucleus and the cytoplasm of normal and malignant breast tissue. Nuclear staining for BRCA1 was observed in most sporadic tumors, but nuclear BRCA1 was reduced or absent in the majority of familial and early onset breast tumors. Although no correlation was found between nuclear BRCA1 expression and estrogen and progesterone status, a significant inverse correlation was found between nuclear BRCA1 and expression of the proliferation marker Ki-67 (P = 0.01). Our findings suggest that tumors associated with a germ-line mutation in one of the breast cancer genes may be highly proliferative and support the view that loss of BRCA1 expression in breast tumors may lead to a more aggressive tumor phenotype.

Adult↗
PubMed1998

Characterization of a truncated progesterone receptor protein in breast tumors.

The progesterone receptor (PR) mediates the actions of progesterone in the normal and malignant breast. PR is expressed as two proteins, PR B and PR A, which are expressed in normal progesterone target tissues and in breast cancers. A significant proportion of breast cancers contain, in addition, a smaller PR protein of molecular mass 78 kDa (PR78 kDa). The significance of PR78 kDa expression is unknown, and in particular, there are no data on whether PR78 kDa is able to bind ligand and therefore potentially exhibit transcriptional activity. If this smaller PR species exhibits similar differences in function as have been evidenced in vitro for PR A relative to PR B, it is possible that this PR species may be an important component in determination of progesterone response in breast cancer. The purpose of this study was to determine whether the PR78 kDa protein in breast tumors is able to bind ligand and to determine whether posttranscriptional mechanisms contribute to its formation in breast cancers. There was no evidence that PR78 kDa was derived from proteolytic activity of either PR B or PR A. Similarly, although exon-deleted PR transcripts were detected (which could, if translated, give rise to a PR protein similar in size to PR78 kDa), neither the abundance of such transcripts nor their relationship to levels of expressed PR78 kDa protein supported a role for exon deletion in formation of this truncated PR protein. PR78 kDa was not recognized by an antibody specific for PR B, indicating that, like PR A, it lacks the N-terminal portion of PR. PR78 kDa was able to bind the progestin ligand, indicating that it may have transcriptional activity. In summary, this study has shown that a truncated PR protein, found in breast cancers, is ligand-binding and seems to be derived from PR A, indicating that it may have a role in progesterone signaling, although a deeper understanding of its role, if any, in breast cancer remains to be established.

Breast Neoplasms↗
PubMed1998

Immunohistochemical detection of progesterone receptors in archival breast cancer.

The progesterone receptor (PR) is an important marker of response to endocrine agents in breast cancer. Immunohistochemical demonstration of PR in formalin fixed tissue has previously proved difficult, and heat pretreatment is considered necessary to retrieve the antigen. There are few data on the effectiveness of autoclaving in unmasking PR, however, and it is not known whether all PR epitopes are equally unmasked. The objectives of this study were to compare the efficacy of autoclaving and microwaving to retrieve PR antigen in archival breast tumors, to determine whether there is an epitope-dependent variability in the pretreatment required, and to examine different slide types and adhesives to reduce the problem of section loss frequently associated with these procedures. Paraffin embedded sections were cut at 2 or 4 microm, mounted onto various slide types with or without the addition of adhesive, and heat pretreated prior to immunoperoxidase staining. Whereas PR immunoreactivity was clearly demonstrated in tissue after both autoclaving and microwaving, autoclaving produced a significantly stronger staining intensity under the conditions used in this study. The duration of autoclaving required to reveal PR fully differed for different epitopes examined. In the absence of heat pretreatment, PR was not detected. Section retention was improved by the use of adhesives and by cutting tissue at 2 microm. Maximum retention was obtained using positively charged slides coated with Mayer albumen adhesive. We conclude that for maximal tissue preservation autoclave pretreatment is the preferred method of PR antigen retrieval from archival breast tumors, that there is epitope-dependent variability in pretreatment required, and that section loss during this procedure can be minimized by choice of slide type, the use of adhesive, and by cutting sections at 2 microm.

Adhesives↗
PubMed1997

Ultrastructural localization of sorcin, a 22 kDa calcium binding protein, in the rat caudate-putamen nucleus: association with ryanodine receptors and intracellular calcium release.

Sorcin is a 22 kDa calcium binding protein that is widely distributed in mammalian tissues, including brain, and is associated with the ryanodine receptor (RyR) family of intracellular calcium-release channels in the heart. To determine the cellular sites for potential central functions of sorcin, we examined the electron microscopic immunocytochemical localization of antipeptide antisera against sorcin and against cardiac and brain RyR in the rat caudate-putamen nucleus (CPN), one of the few regions expressing high levels of brain RyR. Sorcin-like immunoreactivity (S-LI) was detected in both neurons and glia by using immunoperoxidase and immunogold methods. Of 1,735 profiles containing immunogold-silver labeling for sorcin, almost 50% were dendrites and many of these dendrites were spiny. The remainder were mainly small axons, axon terminals, and, more rarely, glia. Furthermore, analysis of dually labeled tissue sections showed the presence of sorcin in many of the dendrites and some of the axonal and glial processes containing RyR. In dendrites, gold-silver deposits showing S-LI were prominently localized to saccules of smooth endoplasmic reticulum and mitochondria, both of which are known to store calcium. These labeled structures were located near the plasma membrane at sites postsynaptic to excitatory-type asymmetric junctions, as well as non-synaptic portions of the plasma membrane. In axons, S-LI was also often seen at extrasynaptic sites on, or near, the plasma membrane. We conclude that in the rat CPN, sorcin may act independently or, in conjunction with RyR, to modulate cytoplasmic release of calcium, mainly from smooth endoplasmic reticulum and/or mitochondria in neurons.

Animals↗
PubMed1997

Association of hereditary angioedema and hereditary breast cancer.

A family is presented in whom hereditary angioedema (HAE) and hereditary breast cancer were coexistent, an association not previously reported. A potential for genetic and treatment-related interactions between the two conditions exists. The use of the hormonal agent danazol to suppress HAE is unlikely to adversely affect the development or outcome of breast cancer. Surgery, chemotherapy, and radiotherapy were received by affected family members, without triggering edema. Whether hormonal breast cancer treatment affects the suppression of HAE by danazol remains unknown.

Aged↗
PubMed1997

Expression of osteonectin mRNA in human breast tumours is inversely correlated with oestrogen receptor content.

Osteonectin is a secreted glycoprotein which is detected in a number of normal and neoplastic human tissues in vivo. It is an extracellular matrix (ECM)-associated protein which is postulated to regulate cell migration, adhesion, proliferation and matrix mineralisation and previous reports suggest that it may be modulated by steroid hormones in target tissues. The aim of this study was to measure osteonectin mRNA and protein expression in breast tumour biopsies and compare these with oestrogen (ER) and progesterone receptor (PR) levels in the same tumours. An inverse correlation was seen between osteonectin mRNA expression and ER level. Samples with low ER protein expression had a mean osteonectin mRNA level which was almost 4-fold greater than the mean level of expression observed in tumours containing high concentrations of ER protein. This inverse correlation was statistically significant. Despite the strong inverse relationship between osteonectin mRNA levels and tumour ER content, no correlation was seen when osteonectin protein concentration was measured in tumour cytosols on immunoblots and compared to ER and PR levels in the same tumours. However, since it is a secreted protein, osteonectin protein expression may not reflect cellular osteonectin levels in breast tumours. In summary, these data suggest that ER-mediated suppression of osteonectin gene expression may contribute to the less aggressive characteristics associated with receptor-positive tumours and that loss of ER expression may lead to over-expression of osteonectin and contribute to a poorer differentiated, more invasive phenotype.

Blotting, Northern↗
PubMed1996

Progesterone receptor A and B protein expression in human breast cancer.

The human progesterone receptor (PR) is a ligand-activated nuclear transcription factor which mediates progesterone action in target tissues. Two PR proteins, PR A (81-83 kDa) and PR B (116-120 kDa), have been described and different physiological activities ascribed to each on the basis of in vitro studies, suggesting that their ratio of expression may control progesterone responsiveness in target cells. Presence of PR in breast tumors is an important indicator of likely responsiveness to endocrine agents. However, the relative expression of PR A and B in breast cancer has not been described and its clinical significance has not been addressed. We have examined the expression of PR A and B in PR-positive breast tumors and found that while in most tumors PR A and B were expressed in similar amounts there was a broad overall distribution of PR A:B ratio which deviated significantly from a normal log distribution with tumors containing a PR A:B ration greater than 4 being over-represented in the group. Linear regression analysis revealed that high PR A:B ratios, in general, derived from a low concentration of PR B rather than high expression of PR A. PR A:B protein ratios were not correlated with the age of the patient or with total PR concentration. A third PR protein band (PR 78 kDa) was detected which comprised greater than 20% of total PR protein in a quarter of the tumor samples examined. The characteristics of tumors containing PR 78 kDa were not different from the overall group. In summary, in PR-positive breast tumors the ratio of expression of PR A and B proteins is close to unity as is seen in a number of other progestin target tissues. However, a significant proportion of tumors expressed very low levels of PR B and a consequently high PR A:B ration. Although the clinical consequence of this observation is not known, the in vitro findings that PR A may act as a repressor for PR B suggests that tumors containing primarily PR A may identify a subset of patients with low or aberrant response to endocrine agents.

Adolescent↗
PubMed1995

Preferential stimulation of human progesterone receptor B expression by estrogen in T-47D human breast cancer cells.

Human progesterone receptor (PR) expression is controlled by two promoter regions giving rise to transcripts encoding PR A and B proteins. It is unknown whether estrogen and progesterone, the major physiological modulators of PR expression, exert their effects equally on the PR promoters. The aim of this study was to analyze estrogen and progestin effects on PR promoters, PR-encoding transcripts, and PR A and B proteins in T-47D human breast cancer cells. The progestin ORG 2058 caused a prolonged decrease in transcription of the PR gene and also abrogated estrogen stimulation of PR transcription. Estradiol (E2) treatment increased the activity of the B but not the A promoter transfected into T-47D cells. ORG 2058 had no effect on the basal or E2-stimulated activity of either promoter. E2 caused a preferential increase in transcripts derived from promoter B, whereas progestins decreased the levels of all PR transcripts. E2 preferentially increased the concentration of the PR B protein and caused a decrease in the PR A/B ratio. This demonstration that estrogen and progestin independently control the synthesis of transcripts arising from the PR promoters and that estrogen alters the cellular PR A/B ratio provides possible mechanisms underlying the cell and tissue specificity of PR regulation.

Breast Neoplasms↗