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S A Murray

Publications and source records attributed to S A Murray.

At least 19 recordsLinked to original sources
PubMed2005

Alms1-disrupted mice recapitulate human Alström syndrome.

Mutations in the human ALMS1 gene cause Alström syndrome (AS), a progressive disease characterized by neurosensory deficits and by metabolic defects including childhood obesity, hyperinsulinemia and Type 2 diabetes. Other features that are more variable in expressivity include dilated cardiomyopathy, hypertriglyceridemia, hypercholesterolemia, scoliosis, developmental delay and pulmonary and urological dysfunctions. ALMS1 encodes a ubiquitously expressed protein of unknown function. To obtain an animal model in which the etiology of the observed pathologies could be further studied, we generated a mouse model using an Alms1 gene-trapped ES cell line. Alms1-/- mice develop features similar to patients with AS, including obesity, hypogonadism, hyperinsulinemia, retinal dysfunction and late-onset hearing loss. Insulin resistance and increased body weight are apparent between 8 and 12 weeks of age, with hyperglycemia manifesting at approximately 16 weeks of age. In addition, Alms1-/- mice have normal hearing until 8 months of age, after which they display abnormal auditory brainstem responses. Diminished cone ERG b-wave response is observed early, followed by the degeneration of photoreceptor cells. Electron microscopy revealed accumulation of intracellular vesicles in the inner segments of photoreceptors, whereas immunohistochemical analysis showed mislocalization of rhodopsin to the outer nuclear layer. These findings suggest that ALMS1 has a role in intracellular trafficking.

Animals↗
PubMed2005

Flavocytochrome P450 BM3: an update on structure and mechanism of a biotechnologically important enzyme.

Since its discovery in the 1980s, the fatty acid hydroxylase flavocytochrome P450 (cytochrome P450) BM3 (CYP102A1) from Bacillus megaterium has been adopted as a paradigm for the understanding of structure and mechanism in the P450 superfamily of enzymes. P450 BM3 was the first P450 discovered as a fusion to its redox partner--a eukaryotic-like diflavin reductase. This fact fuelled the interest in soluble P450 BM3 as a model for the mammalian hepatic P450 enzymes, which operate a similar electron transport chain using separate, membrane-embedded P450 and reductase enzymes. Structures of each of the component domains of P450 BM3 have now been resolved and detailed protein engineering and molecular enzymology studies have established roles for several amino acids in, e.g. substrate binding, coenzyme selectivity and catalysis. The potential of P450 BM3 for biotechnological applications has also been recognized, with variants capable of industrially important transformations generated using rational mutagenesis and forced evolution techniques. This paper focuses on recent developments in our understanding of structure and mechanism of this important enzyme and highlights important problems still to be resolved.

Animals↗
PubMed2005

How evidence based is the management of two common sports injuries in a sports injury clinic?

OBJECTIVES: To examine the diagnosis and management of adults attending a sports injury clinic, to establish to what extent the management of the two most common injuries treated at this clinic is evidence based, and to explore factors that affect management. METHODS: A retrospective examination of 100 random case notes extracted age, sex, sport, type and site of injury, treatment, and outcome. Systematic literature reviews examined the extent and quality of scientific evidence for the management of the two most commonly presenting injuries. A clinical attachment period and practitioner interviews allowed recognition of factors impinging on management decisions. RESULTS: Patellofemoral pain syndrome (PFPS; 10% of all injuries) and Achilles tendinopathy (6% of all injuries) were the most commonly presenting injuries. The mean (SD) number of treatments used for PFPS was 2.8 (0.9). The mean number of treatments used for Achilles tendinopathy was 3.7 (1.0). Clinicians reported that personal experience formed the basis of management plans in 44% of PFPS cases and 59% of Achilles tendinopathy cases, and that primary research evidence only accounted for 24% of management plans in PFPS and 14% in Achilles tendinopathy. Practitioners were unaware of literature supporting over 50% of the treatment modalities they used. However, clinicians were often using evidence based treatments, unaware of the supporting research data. CONCLUSIONS: This study highlights a lack of evidence base, a lack of knowledge of the research evidence, and a lack of management based on the current evidence that is available for these conditions. Practitioners practised evidence based medicine in under 50% of cases.

Achilles Tendon↗
PubMed2002

Redistribution of connexin 43 by cAMP: a mechanism for growth control in adrenal cells.

In order to investigate the regulation of connexin distribution in rapidly growing cells, we evaluated the effects of dibutyryl cyclic adenosine monophosphate (DbcAMP) treatment on the cellular location of endogenous connexin 43 (Cx43) in an adrenal tumor cell population. Polyclonal antibodies to Cx43 and a Cx43 green fluorescent fusion protein (Cx43-GFP) were used to localize Cx43 gap junction protein in plaques at sites of cell-cell contact and in spherical packets within the cytoplasm. Treatment with DbcAMP significantly decreased the number and size of packets within the cytoplasm, and significantly increased surface gap junction plaque size. These data support the theory that cAMP can influence the availability of gap junction protein at the points of cell contact where it is required for cell-cell communication, and thus has the potential to be an important regulator of adrenal tumor cell proliferation.

Adrenal Cortex↗
PubMed2002

Gap junction proteins and cell-cell communication in the three functional zones of the adrenal gland.

Mouse and monkey adrenal glands were used to study the relationships between gap junction protein expression, intercellular communication and adrenal zonation. Dye communication patterns were determined by incubating freshly excised and hemisected adrenal glands in Lucifer yellow, a gap junction permeable fluorescent dye. Immunohistochemical techniques were used to localize adrenal gap junction proteins. The combination of these two techniques permitted the correlation of gap junction proteins with dye transfer and hormone responses in specialized regions of the adrenal cortex. Lucifer yellow dye communication was most pronounced in the inner glucocorticoid/androgen-producing regions (zona fasciculata/zona reticularis), but was virtually absent in the outer mainly mineralocorticoid-producing region (zona glomerulosa). This pattern of dye communication was coincident with immunohistochemical localization of the gap junction protein, alpha(1)Cx43. The variations in communication and alpha(1)Cx43 expression within the adrenal cortex are thought to be relevant to normal physiological regulation of the adrenal gland.

Adrenal Cortex↗
PubMed2001

Vanadate disrupts mammary gland development in whole organ culture.

Protein tyrosine kinases and phosphatases are signaling molecules involved in all aspects of development, including proliferation, differentiation, and apoptosis. How disruption of protein tyrosine phosphatase affects mammary gland development is not entirely clear. We examined the effects of sodium vanadate, which is known to primarily inhibit tyrosine phosphatases, in mouse mammary gland development in whole organ culture. Mammary epithelial differentiation was effectively inhibited by vanadate in a dose-dependent manner as indicated by lack of epithelial alveoli compared to the contralateral non-treated gland controls. Mammary glands in the differentiation medium after four days in the presence of vanadate did not differentiate into alveoli. Instead, they exhibited prominent terminal end buds and lost the distinctive epithelial structures. The inhibitory effect of vanadate on mammary epithelial cell differentiation was irreversible after one day of treatment. Immunohistochemical staining for PCNA (Proliferating Cell Nuclear Antigen) showed that vanadate-treated glands exhibited elevated proliferation signals in the differentiation medium. Expression of beta-casein protein in the vanadate-treated glands decreased dramatically and progressively. Short-term exposure (up to 72 hours) of mammary glands to vanadate resulted in an increase in mammary epithelial cell density and loss of organization of the mammary structures. TUNEL assay of mammary glands with prolonged exposure to vanadate revealed widespread apoptosis. Furthermore, some cells were still proliferating or expressing beta-casein after prolonged exposure to vanadate. Taken together, these data indicate that vanadate treatment blocks mammary epithelial cell differentiation and promotes abnormal proliferation and apoptosis, likely through the inhibition of protein tyrosine phosphatase-mediated signaling.

Animals↗
PubMed2001

Bimodal inhibition of connexin 43 gap junctions decreases ACTH-induced steroidogenesis and increases bovine adrenal cell population growth.

In order to elucidate the role of gap junctions in adrenal cell responses, we measured the effect of inhibiting gap junctions with 18-alpha glycerrhetinic acid (GA; a potent inhibitor of cell-cell communication) and connexin antisense transfection on cell proliferation and adrenocorticotropin (ACTH)-stimulated steroidogenesis. In these experiments we utilized a bovine adrenocortical cell (SBAC) population, which responds to ACTH treatment with a dose-dependent increase in steroid production, an increase in connexin 43 (alpha(1)-Cx43) gap junction protein concentrations, and a decrease in cell population growth. SBAC cell populations treated with GA had increased growth rates, decreased ACTH-stimulated steroidogenesis, but no reduction in alpha(1)-Cx43 gap junction protein contents. In contrast, when SBAC cells were transfected with alpha(1)-Cx43 antisense cDNA, gap junction protein concentration was dramatically reduced as expected, unlike the GA-treated cell populations. Cell populations transfected with alpha(1)-Cx43-antisense also exhibited increased growth rates and a decreased steroidogenic response to ACTH treatment as compared with control or vector-only transfected cell populations. The decreased responsiveness and increased number of cells in the population after gap junction function was decreased by either GA treatment or antisense transfection, suggests that gap junctions may be necessary factors in ACTH-stimulated responsiveness and growth control in the adrenal gland.

Adrenal Glands↗
PubMed2000

Giant ancient schwannoma of the pelvis.

A 43-year-old man with a large ancient schwannoma of the pelvis, presenting with varicose veins, is reported. Ancient schwannoma (neurilemmoma) is a benign tumour of nerve sheath origin characterised histologically by features of severe degeneration and which rarely can grow to a large size. Malignant transformation, though reported, is extremely rare.

Adult↗
PubMed2000

The interplay between social and cultural context and perceptions of cardiovascular disease.

This paper seeks to explore the impact of social and cultural factors upon perceptions of the patients' cardiovascular risk and intended lifestyle changes. Qualitative and quantitative research approaches were used. The sample was purposeful; matched groups of 10 first time post myocardial infarction (MI) patients, 10 informal (spouse, blood relative or partner) and 10 formal carers (nursing staff) were selected on a convenience basis. Personal interviews were conducted with participants, during which a semistructured questionnaire was completed. A combination of descriptive statistics and qualitative analysis of these data revealed that social and cultural factors formed the basis of patients' and informal carers' perceptions of cardiovascular risks and social information networks provided the main source of information about cardiovascular risk. For the staff, known risk factors based on epidemiological evidence (lack of exercise and diet) formed the basis of their perceptions of the patients' cardiovascular risk factors. However, for all the participant groups (i.e. patients, informal carers and staff) the risk factors - diet and exercise were indicated as being the patients' intended lifestyle changes., The results illustrate potential interplay between 'social' and 'cultural' context and perceptions of cardiovascular risk and incongruency between perceptions of risk and perceptions of the patients' intended lifestyle change. These results may assist nurses in giving effective advice to patients and relatives about lifestyle change following myocardial infarction and inform future policy for cardiac rehabilitation.

Adult↗
PubMed2000

Alpha1 connexin 43 gap junctions are decreased in human adrenocortical tumors.

Gap junctional communication disorders have been implicated in the etiology of benign and malignant tumors. Understanding the type, distribution, and frequency of gap junctions in adrenal disorders should provide insight into the role of gap junctions in adrenal carcinogenesis as well as information that may be useful in developing improved diagnosis and treatment of adrenal diseases. Using immunocytochemical techniques, we have characterized and compared alpha1 connexins 43 gap junction protein levels in normal adrenal glands to those in benign and malignant adrenocortical human tumors. In addition, gap junction protein levels were studied in a human adrenal cancer cell line (H295). In both normal and neoplastic adrenal tissues, only alpha1 connexin 43 could be detected, whereas beta1 connexin 32 and beta2 connexin 26 were not found. In the normal adrenal gland, the zona fasciculata was demonstrated to have the highest number of gap junctions per cell (mean +/- SEM, 13.78 +/- 1.93). In contrast, in benign adrenocortical adenomas, the number of gap junctions per cell compared to that detected in normal adrenal glands was significantly reduced (mean +/- SEM, 4.6 +/- 1.17; P < or = 0.05), and the lowest number was found in malignant adrenocortical tumors (1.42 +/- 0.58; P < or = 0.05). Similarly, there were few or no alpha1 connexin 43 gap junctions in the H295 population. There was a progressive decrease in gap junction plaques in adrenocortical cancer cell populations compared to those in normal cell populations. Therefore, analysis of gap junction protein may be helpful for the differential diagnosis of benign and malignant adrenal tumors. The induction of gap junctions in malignant cells may provide a novel therapeutic strategy for adrenal cancer.

Adenoma↗
PubMed2000

Hypophysectomy results in a loss of connexin gap junction protein from the adrenal cortex.

To test the hypothesis that gap junctions are dependent on the tropic state of the adrenal gland, the effect of hypophysectomy on connexin 43 (alpha1-Cx43) gap junction protein occurrence and distribution was examined in mice. Gap junction protein occurrence was assessed with immunohistochemical techniques. In the adrenal gland from intact animals, alpha1-Cx43 gap junction protein was detected in the zonae fasciculata(ZF) and reticularis (ZR) while only a few alpha1-Cx43 gap junction plaques were found connecting zona glomerulosa(ZG) cells. Hypophysectomy led to a profound atrophy of the cortex which was more marked in the inner zones (zonae fasciculata and reticularis) than in the zona glomerulosa. There was a time dependent loss of alpha1-Cx43 gap junction protein in the adrenal cortex after hypophysectomy. At 33 day following hypophysectomy there was a two fold decrease in gap junctions in the zona fasciculata while the average gap junction plaque size was not different than the size seen in control animal adrenal glands.. ACTH (1U/gm body weight) treatment in hypophysectomized animals increased the number of gap junction plaques in the zona fasciculata. Hypophysectomy led to diminished alpha1-Cx43 gap junction expression in the zona fasciculata which could be restored by ACTH treatment. Because altering the tropic state of the adrenal glands via hypophysectomy leads to a reduction in gap junction number, it can be suggested that control of gap junction expression in the adrenal gland is hormone dependent and linked to adrenal gland function.

Adrenal Cortex↗
PubMed1997

Relationship of cytoskeletal filaments to annular gap junction expression in human adrenal cortical tumor cells in culture.

In addition to the well-characterized surface gap junctions expressed at contact sites between cells, annular gap junction profiles have been localized within the cytoplasm of some cell populations. To study and characterize these annular profiles, gap junction protein type was demonstrated with Western blot and immunocytochemistry. The distribution of annular gap junctions and the relationships to cytoskeletal elements were demonstrated with immunocytochemical, transmission electron microscopic, or image analysis with confocal microscopy techniques. SW-13 adrenal cortical tumor cells expressed alpha1 gap junctions at areas of cell to cell contact. In addition, alpha1 gap junction annular profiles were seen within the cytoplasm. Actin and myosin II were found closely associated with these annular gap junctions, while no physical association between tubulin- or vimentin-containing fibers and gap junction protein could be established. Disruption of microfilaments with cytochalasin B treatment (10 microg/ml, 1 h) resulted in a decrease in the average number and an increase in the average size of annular gap junctions compared to control populations. The results are consistent with a role for cytoskeletal elements containing actin and myosin II in annular gap junction turnover.

Actin Cytoskeleton↗
PubMed1997

Transcriptional and post-transcriptional control of lysyl oxidase expression in vascular smooth muscle cells: effects of TGF-beta 1 and serum deprivation.

Transforming growth factor-beta 1 (TGF-beta 1) markedly reduced cell proliferation and elevated steady state lysyl oxidase (LO) mRNA 3-fold in neonatal rat aorta smooth muscle cells cultured in medium containing 10% fetal bovine serum. The increase in LO mRNA was prevented by the presence of cycloheximide, indicative of controlling events at the level of protein synthesis. The basal level of mRNA in cells proliferating in 10% fetal bovine serum in the absence of TGF-beta 1 was enhanced 7-fold upon decreasing growth by shifting to medium containing 0.5% serum. Changes in LO activity paralleled those in LO mRNA. Nuclear run-on assays revealed that the stimulation of expression in 0.5% serum involved increased gene transcription whereas that caused by TGF-beta 1 was mostly post-transcriptional in origin. LO mRNA was quite labile (t1/2 approximately 3 h) in 10% serum but was markedly stabilized (t1/2 > 12 h) by the presence of TGF-beta 1 in the 10% serum medium. LO mRNA was also considerably more stable under retarded growth conditions (0.5% serum) in the absence of TGF-beta 1. LO promoter activity in luciferase reporter constructs transfected into these cells was low and not significantly affected by the addition of TGF-beta 1 to the 10% serum medium but was markedly elevated by shifting from 10 to 0.5% serum in the absence of TGF-beta 1. Thus, LO expression is inversely correlated with cell proliferation, and is subject to control at transcriptional and post-transcriptional levels. TGF-beta 1 enhances LO expression in these cells by dramatically stabilizing LO mRNA.

Animals↗
PubMed1997

Comparison of gap junction expression in the adrenal gland.

The presence of alpha 1 (Cx43) gap junction protein was demonstrated in rat, mouse, guinea pig, and bovine adrenal glands with immunocytochemical techniques. The presence of six other connexin species was not detected in the adrenal glands studied. The gap junction stain within the adrenal cortex was punctate and located at sites of cell-cell contact. While little gap junction, alpha 1, staining was detected at sites of cell contact in the zona glomerulosa (ZG), the zona fasciculata (ZF) and zona reticularis (ZR) had intense staining at cell contacts in all rodent species studies. In the bovine adrenal, ZG cells were connected by large gap junctions as were the cells of the ZF and ZR. The variations in alpha 1 distribution within the adrenal cortex may correspond with the different division rates and hormone functions within the adrenal gland as well as species differences between rodent and bovine adrenal gland.

Adrenal Glands↗