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Biomedical subjects

S Cook

Publications and source records attributed to S Cook.

At least 19 recordsLinked to original sources
PubMed2007

Selective inhibition of MEK1/2 reveals a differential requirement for ERK1/2 signalling in the regulation of HIF-1 in response to hypoxia and IGF-1.

The transcription factor hypoxia-inducible factor 1 (HIF-1) plays a pivotal role in tumour growth and progression, and HIF-1 is regulated through a number of signalling pathways. Here, we investigated the involvement of the mitogen-activated protein kinase (MAPK) signalling pathway in HIF-1 regulation. We found that overexpression of wild-type (WT) extracellular signal regulated protein kinase 1 (ERK1) greatly potentiated HIF-1 activation in hypoxia and HIF-1alpha induced in response to insulin growth-like factor 1 (IGF-1). Conversely, treatment of tumour cells with the MEK1/2 inhibitors PD98059 or U0216, or expression of a dominant-negative form of ERK1 blocked HIF-1 activation in hypoxia without affecting HIF-1alpha induction, localization or binding of HIF-1beta. Interestingly however, the highly selective MEK1/2 inhibitor PD184352 did not inhibit HIF-1 activity or vascular endothelial growth factor (VEGF) induced in response to hypoxia but blocked HIF-1alpha protein and HIF-1 activity induced by IGF-1 stimulation without affecting HIF-1alpha mRNA levels. Finally, we found that ERK5 phosphorylation status was not significantly affected by hypoxia in the presence or absence of PD184352. Taken together, our data suggest that although ERK1/2 signalling is important for HIF-1alpha induction and HIF-1 activity in response to IGF-1, it is dispensable for the induction of HIF-1alpha and activation of HIF-1 in response to hypoxia.

Benzamides↗
PubMed2007

The relationship between dosing of alosetron and discontinuation patterns reported by patients participating in a follow-up programme.

BACKGROUND: Alosetron was reintroduced for treatment of irritable bowel syndrome with a risk management programme in November 2002. Recommended starting dosage was 1 mg/day for 4 weeks. If symptoms remained uncontrolled, dosage could be changed to 2 mg/day. AIM: To describe alosetron dosages and associated patient characteristics from the Lotronex follow-up survey programme. METHODS: Patients reported dosages of alosetron at start and regular follow-up intervals. Analyses were limited to patients with the potential to have at least 1 year of follow-up (enrolled between 9 December 2002 and 31 December 2003). RESULTS: At baseline, 75% of 2817 respondents reported starting on 1 mg/day, 17% on 2 mg/day and 8% on other doses. Adherence to recommended starting dosage did not vary by status at end of follow-up, previous alosetron experience or age. At last reported dose, 50% of respondents were using 1 mg/day; 29% were using 2 mg/day. Discontinuation was not related to baseline doses. Longer times to discontinuation were associated with previous use, symptoms for more than 6 months and dose change throughout follow-up. CONCLUSIONS: High adherence to recommended dosing at baseline and follow-up suggests that the risk management programme is encouraging safe use of alosetron, including adherence to dosing recommendations.

Adult↗
PubMed2006

A patient follow-up survey programme for alosetron: assessing compliance to and effectiveness of the risk management programme.

BACKGROUND: In November 2002, alosetron HCl (Lotronex, GlaxoSmithKline Research Triangle Park, NC, USA) was re-introduced to the US marketplace for women with severe diarrhoea-predominant irritable bowel syndrome. In support of the re-introduction, a risk management programme was implemented, which included a patient follow-up study in which all users of alosetron could participate. AIM: We report on the methods used and the effectiveness of key elements of the risk management programme. METHODS: Patients voluntarily enroled in the study and completed questionnaires at baseline, after 5 and 10 weeks, and quarterly thereafter. Questions focussed on patient eligibility, knowledge of risks and benefits, and adherence to the recommended programme elements for education, prescribing and dispensing. RESULTS: Between December 2002 and 2004, 4,803 patients enrolled in the study, and <3% were lost to follow-up. The average follow-up time was approximately 6 months, and the response rate for each assessment was >95%. A total of 90% of patients at baseline met the full clinical criteria recommended for the treatment. Patient adherence to the risk management programme was >87%. CONCLUSIONS: Using the Lotronex risk management programme, patients met clinical criteria, were knowledgeable about treatment risks and benefits, and were adherent to the process elements of the programme. These patients seemed to engage in active dialogue with their physicians about symptoms and use of alosetron.

Adolescent↗
PubMed2006

Subjective memory beliefs and cognitive performance in normal and mildly impaired older adults.

Previous research suggests that subjective perceptions of memory may be related to objective memory performance. In the present study, healthy community-dwelling elders (N = 73, mean age = 75.25 years, education = 16.2 years) completed a neuropsychological assessment, including two questionnaires of subjective memory beliefs. Each participant was identified, via consensus conference, as belonging to either an amnestic mild cognitive impairment (MCI, n = 16) or no mild cognitive impairment (noMCI, n = 57) group. Results indicated that subjective memory capacity beliefs were significantly related to verbal memory performance in the MCI group, but not in the noMCI group. This differential relationship persisted even after controlling for depressive symptoms, and was not reflective of unequal variances in the two groups. Thus, results indicate that subjective memory beliefs may be better indicators of performance in those with possible incipient cognitive impairment than normal older adults, perhaps because persons with MCI have heightened insight into their memory functioning, and that this relationship is not due to group differences in depressive symptoms.

Aged↗
PubMed2006

Postnatal changes in testicular gonadotropin receptors, serum gonadotropin, and testosterone concentrations and functional development of the testes in bulls.

The primary objectives of this study were to follow the temporal patterns of testicular LH and FSH receptor (LH-R and FSH-R) concentrations and affinity (Ka) during sexual maturation in bulls and to see if such patterns could help explain the control of rapid testicular growth that occurs after 25 weeks of age, when serum gonadotropin concentrations are low. Separate groups of Hereford x Charolais calves (n = 6) were castrated every 4 weeks from 5 to 33 weeks of age and at 56 weeks of age. A week prior to castrations, from 5 to 33 weeks of age, blood was collected every 15 min for 10 h. The transition from indifferent supporting cells to Sertoli cells in seminiferous tubules was rapid between 13 and 25 weeks and rapid testis growth occurred after 25 weeks of age. Serum LH and FSH concentrations were transiently elevated at 12 weeks of age (P < 0.05). LH-R concentrations decreased from 13 to 25 weeks of age and increased to 56 weeks of age (P < 0.05). LH-RKa decreased from 9 to 17 weeks of age, increased to 29 weeks of age and declined to 33 weeks of age (P < 0.05). FSH-R concentrations declined from 17 to 25 weeks of age then increased to 56 weeks of age (P < 0.05). FSH-RKa increased from 17 to 25 weeks of age (P < 0.05). High concentrations of gonadotropins and their receptors may be critical to initiate testis growth postnatally and support it after 25 weeks of age in the face of low serum gonadotropin concentrations.

Animals↗
PubMed2005

A multigene analysis of the phylogenetic relationships among the flaviviruses (Family: Flaviviridae) and the evolution of vector transmission.

The genus Flavivirus (family Flaviviridae) presently comprises around 70 single-strand positive-sense RNA viruses. These replicate in a range of vertebrate and invertebrate cells and may be mosquito-borne, tick-borne or have no-known-vector. Since transmission mode correlates strongly with phylogeny, the flaviviruses constitute a valuable model for the evolution of vector-borne disease. Attempts to resolve the higher-level taxonomic relationships of the flaviviruses through molecular phylogenetics have thus far proved inconclusive because of conflicting positions for the three main transmission groups. We conducted the most comprehensive phylogenetic study to date, involving maximum likelihood analyses of the NS3 and NS5 genes and the entire genome sequences available at present. For the first time, we use and test a variety of more robust methods of sequence alignment and appropriate models of amino acid replacement to study these highly divergent sequences, and explicitly test specific hypotheses of tree topology. We show that (i) the NS5 gene contains insufficient phylogenetic signal to choose between competing topological hypotheses, (ii) the NS3 gene and whole genome data indicate that the mosquito-borne flaviviruses represent an outgroup to the remaining flaviviruses, and (iii) that tick-borne transmission is probably a derived trait within the genus.

Animals↗
PubMed2005

Homocysteine and B vitamins.

Homocysteine (tHcy) is an intermediate sulfur-containing amino acid which acts as a methyl group donor for methionine metabolism. Increased serum concentrations (=hyperhomocysteinemia, >10 micromol/l) have been associated with an increased cardiovascular risk. Homocystinuria, an infrequent genetic disease usually due to lack of cystathione beta-synthase, has been found with severely elevated serum homocysteine values (>150 micromol/l). Functional gene polymorphisms of key enzymes (e.g., N5,N10-methylene-tetrahydrofolate reductase) and dietary B-vitamin deficiencies in the elderly are, however, frequent in the 'Western' population. Hyperhomocysteinemia has been associated with other vascular effects such as atherothrombosis and endothelial dysfunction due to its auto-oxidative potential, thereby increasing the production of reactive oxygen species. Other effects may involve neurodegenerative diseases such as Alzheimer or dementia praecox of the elderly. Therapeutic interventions lowering tHcy may therefore offer novel tools for the prevention and treatment of atherosclerosis. B-vitamin supplementation (folic acid=vitamin B9, vitamin B6 and vitamin B12) is an efficient and safe tHcy-lowering therapy, decreases tHcy by 30%-50% and has been shown to lower cardiovascular morbidity and mortality. Furthermore, folic acid supplementation has been shown to reduce or even almost eliminate neurotubular birth defects (spina bifida) and to markedly decrease the rate of megaloblastic anemia. Thus, fortification of flour with folic acid in the USA was advocated several years ago in order to prevent these entities.

Animals↗
PubMed2004

Developmental regulation of Notch signaling genes in the embryonic pituitary: Prop1 deficiency affects Notch2 expression.

Normal development of the pituitary gland requires coordination between the maintenance of a progenitor cell pool and the selection of progenitor cells for differentiation. As Notch signaling controls progenitor cell differentiation in many embryonic tissues, we investigated the involvement of this important developmental pathway in the embryonic pituitary. We report that expression of Notch signaling genes is spatially and temporally regulated in pituitary embryogenesis and implicate Notch2 in the differentiation of several cell lineages. Notch2, Notch3, and Dll1 are initially expressed by most cells within the pituitary primordium and become restricted to a subset of the progenitor cell pool as differentiated pituitary cells begin to appear. Mutations in the transcription factor Prop1 interfere with pituitary growth and cell specification, although the mechanism is unknown. Notch2 expression is nearly absent in the developing pituitaries of Prop1 mutant mice, but unaltered in some other panhypopituitary mutants, revealing that Prop1 is directly or indirectly required for normal Notch2 expression. Transgenic overexpression of Prop1 is not sufficient for enhancement of endogenous Notch2 expression, indicating that there are multiple inputs into this pathway. Dll3 is expressed only in the presumptive corticotrope and melanotrope cells. Analysis of Dll3 null mutants indicates that Dll3 is not required for specification of these two cell types, although there may be functional overlap with Dll1. The spatial and temporal expression patterns of Notch signaling genes in the pituitary suggest overlapping roles in pituitary growth and cell specification.

Animals↗
PubMed2004

Nuclear accumulation of histone deacetylase 4 (HDAC4) coincides with the loss of androgen sensitivity in hormone refractory cancer of the prostate.

OBJECTIVES: To examine the effect of androgen treatment upon histone deacetylase 4 (HDAC4) localisation and, thus, enzymatic function in androgen sensitive prostate cancer (CaP) models. To study HDAC4 expression in benign prostatic hyperplasia, primary and hormone refractory (HR) CaP and to investigate the involvement of histone deacetylase activity in the development of the androgen insensitive phenotype. METHODS: Immunohistochemical staining of prostate sections of both benign tissue and primary and hormone relapsed prostate cancer, as well as of the CWR22 mouse xenograft model, and indirect quantitative immunofluorescence staining of endogenous HDAC4 in LNCaP cells. RESULTS: HDAC4 is recruited to the nuclei of HR cancer cells, where it may exert an inhibitory effect on differentiation and contribute to the development of the aggressive phenotype of late stage CaP. The above may result from the loss of androgen responsiveness characterising HR CaP, since HDAC4 nuclear localisation is regulated by androgens in androgen responsive systems (i.e. LNCaP, CWR22) reflecting earlier phase disease. CONCLUSIONS: HDAC4 may contribute to the development of HR CaP and, therefore, constitute a potential therapeutic target, particularly in the most lethal phase of androgen independence.

Androgens↗
PubMed2003

Drowning your sorrows? Attitudes towards alcohol in UK Jews and Protestants: a thematic analysis.

BACKGROUND: Jewish culturally supported beliefs may discourage drinking and drunkenness as ways of socialising and coping with stress. Thus Jewish men under stress may be relatively more likely to become depressed, and less likely to use and abuse alcohol. This study is the first qualitative comparison of Jews and Protestants, men and women. It examines whether alcohol-related beliefs are consistent with the alcohol-depression hypothesis, i.e. that positive beliefs about alcohol use and effects are associated with high alcohol use and low depression. MATERIAL AND DISCUSSION: A thematic (interpretive phenomenological) analysis on open-ended question responses, from 70 Jews and 91 Protestants, and on semi-structured interviews with five Jews and four Protestants, identified three salient themes: the importance of retaining self-control; the pleasures of losing inhibitions; and the relations of alcohol-related behaviour to identity. Compared to Protestants, Jews described alcohol-related behaviour as threatening to self-control, loss of inhibition as unenjoyable and dangerous and distinguished between the kinds of drinking behaviours appropriate for Jews and others. Sub-themes for Protestant men were denial that drinking threatens self-control, and appropriateness of going to the pub. CONCLUSIONS: The themes identified are not measurable using published research instruments. Alcohol-related behaviour may be a feature of Jewish identity. The beliefs identified are consistent with the alcohol-depression hypothesis.

Adult↗
PubMed2003

Increased eNO and pulmonary iNOS expression in eNOS null mice.

Nitric oxide (NO) is a major regulatory molecule of the cardiovascular system; however, measurement of vascular NO synthesis in vivo represents a major challenge. NO stemming from the lower respiratory tract has been used as a marker of vascular endothelial function. Experimental evidence for this concept is lacking. Therefore, the aim of the present study was to investigate this relationship. Lower respiratory tract exhaled NO concentration, together with systemic and pulmonary artery pressure, was measured in endothelial nitric oxide synthase (NOS) (eNOS) null mice (eNOS-/-). Similar studies were performed in inducible NOS (iNOS) null mice (iNOS-/-). Defective endothelial NO synthesis in eNOS-/- mice (evidenced by systemic and pulmonary hypertension) was associated with augmented exhaled NO levels (12.5 +/- 1.9 versus 9.8 +/- 1.2 parts per billion (ppb), eNOS-/- versus wild type), whereas normal endothelial NO synthesis in iNOS-/- mice was associated with decreased exhaled NO levels (4.3 +/- 1.5 ppb). Augmented exhaled NO levels in eNOS-/- mice were associated with upregulation of iNOS expression in the lung. These results indicate that inducible nitric oxide synthase is a major determinant of gaseous nitric oxide production in the lung, and lower respiratory tract exhaled nitric oxide does not always represent a marker of vascular endothelial nitric oxide synthesis.

Animals↗
PubMed2002

Analysis of the variations in clinical signs shown by 254 cases of equine headshaking.

A national survey of headshaking in 254 horses was undertaken to describe the clinical signs of the condition as observed by horse owners. Principal component analysis was used to determine the underlying structure of 11 signs and the criteria by which the affected horses could be most effectively differentiated; the analysis suggested five components with a variance greater than one which together explained over 60 per cent of the total variance. Other analyses of the data indicated that headshaking could develop at any age and that twice as many males were affected as females; 64 per cent of the horses shook their heads seasonally and geldings were more likely than mares to be seasonally affected. Seasonal headshaking tended to be significantly worse on sunny days but improved on rainy days, windy days, at night and indoors.

Animals↗
PubMed2002

Tolerance for depression: are there cultural and gender differences?

This study examined tolerance for depression among Jewish and Protestant men and women in the United Kingdom. A measure of tolerance for depression was developed, which examined willingness to admit to and seek help for depression. More specifically, the items in the measure (developed from extended interviews) covered empathy towards sufferers, potential virtues of the illness, hopes for treatment, seeing the illness as 'normal', and telling other people about it. Existing evidence suggested that tolerance for depression might be greater amongst Jews compared with Protestants, and women compared with men. Also, Jewish men were expected to be more tolerant than Protestant men, whereas Protestant and Jewish women were not expected to differ from each other. It was found that tolerance for depression was greater amongst Jews than Protestants, and this is consistent with the elevated levels of depression amongst Jewish men as compared with Protestant men. However, findings relating to gender were mixed and were not always consistent with our expectations. The findings suggest that there may be some cultural variations in willingness to admit to and seek help for depression, and this may be worth examining in other cultural-religious groups. Individual variations in tolerance for depression may be clinically significant.

Adolescent↗
PubMed2001

Tip60 is a co-activator specific for class I nuclear hormone receptors.

The nuclear hormone receptor superfamily is composed of a group of hormone-dependent transcription factors that play prominent roles in homeostatic events in vertebrates. A prerequisite for steroid hormone receptor activity is the binding of co-activator molecules to the activation function-2 domain of the receptor. The LXXLL motif/nuclear receptor box, contained within a number of co-activator molecules, mediates the interaction with nuclear hormone receptors. Tip60 (Tat-interactive protein 60 kDa), previously shown to bind to and enhance androgen receptor (AR)-mediated transactivation, contains a single nuclear receptor box at its extreme C terminus. We demonstrate that unlike members of the p160 co-activator family that interact predominantly with the N terminus of the AR in an LXXLL motif-independent manner, the LXXLL motif of Tip60 is required and is sufficient for AR interaction. Furthermore, by using the mammalian two-hybrid system and transient transfection experiments, we show that Tip60 preferentially interacts with and up-regulates class I nuclear receptors, suggesting that Tip60 is a steroid hormone receptor-specific co-activator. We conclude that Tip60 may specifically regulate a subset of nuclear hormone receptors, giving an indication to how regulated nuclear receptor activation can be achieved.

Acetyltransferases↗