Search tips
Search criteria

Results 1-25 (49)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
more »
1.  Probing the GnRH receptor agonist binding site identifies methylated triptorelin as a new anti-proliferative agent 
D-amino acid substitutions at glycine postion 6 in GnRH-I decapeptide can possess super-agonist activity and enhanced in vivo pharmacokinetics. Agonists elicit growth-inhibition in tumorigenic cells expressing the GnRH receptor above threshold levels. However, new agonists with modified properties are required to improve the anti-proliferative range. Effects of residue substitutions and methylations on tumourigenic HEK293[SCL60] and WPE-1-NB26-3 prostate cells expressing the rat GnRH receptor were compared. Peptides were ranked according to receptor binding affinity, induction of inositol phosphate production and cell growth-inhibition. Analogues possessing D-Trp6 (including triptorelin), D-Leu6 (including leuprolide), D-Ala6, D-Lys6, or D-Arg6 exhibited agonist and anti-proliferative activity. Residues His5 or His5,Trp7,Tyr8, corresponding to residues found in GnRH-II, were tolerated, with retention of sub-nanomolar/low nanomolar binding affinities and EC50s for receptor activation and IC50s for cell growth-inhibition. His5D-Arg6-GnRH-I exhibited reduced binding affinity and potency, effective in the mid-nanomolar range. However, all GnRH-II-like analogues were less potent than triptorelin. By comparison, three methylated-Trp6 triptorelin variants showed differential binding, receptor activation and anti-proliferation potency. Significantly, 5-Methyl-DL-Trp6-Triptorelin was equipotent to triptorelin. Subsequent studies should determine whether pharmacologically enhanced derivatives of triptorelin can be developed by further alkylations, without substitutions or cleavable cytotoxic adducts, to improve the extent of growth-inhibition of tumour cells expressing the GnRH receptor.
PMCID: PMC3906704  PMID: 24490142
2.  Integrating online communities and social networks with computerised treatment for insomnia: a qualitative study 
The British Journal of General Practice  2012;62(605):e840-e850.
Insomnia is a common psychological complaint. Cognitive behavioural therapy for insomnia (CBT-I), although effective, is little used because of lack of trained providers. Computerised CBT-I (CCBT-I) may be a solution to this shortfall in access.
To explore patient and health professional perspectives and the role of social networking, to develop a novel CCBT-I programme to increase access to this form of intervention.
Design and setting
Qualitative methods underpinned by the theory of planned behaviour in primary care in Lincolnshire and Nottinghamshire.
Semi-structured interviews and focus groups with a purposive sample of health professionals and adults with insomnia.
A total of 23 health professionals and 28 patients were interviewed. Features designed to engender trust and improve functionality were perceived to improve uptake and adherence to CCBT-I. Trust lay in programme accreditation; for professionals, trust derived from evidence of effectiveness; for patients, trust depended on the doctor–patient relationship, professional support, the quality of online peer support, and perceptions of risk. Patients wanted mobile applications; access in short periods; self-assessment; interactive, personalised information on sleep; and moderated contact with other users. Patients and practitioners differed over whether useful information could be distinguished from less useful or potentially incorrect information.
Improving uptake and adherence to online programmes for insomnia requires design features focusing on trust and functionality. Enabling greater patient control and interaction with other users and professionals may stimulate positive experiences of online therapy. CCBT-I would enable greater access to treatment but is limited by lack of online access or poor computer literacy.
PMCID: PMC3505418  PMID: 23211265
cognitive behaviour therapy for insomnia, computerised; general practice; insomnia; primary health care; social networking
3.  Assessment of posttraumatic symptoms in patients with first-episode psychosis 
The Journal of nervous and mental disease  2011;199(11):10.1097/NMD.0b013e318234a037.
Posttraumatic Stress Disorder (PTSD) is common among patients with psychotic disorders. The present study examined the internal reliability and comparability of the Impact of Event Scale (IES) in a sample of 38 patients with first-episode psychosis and 47 controls exposed to severe physical and/or sexual abuse. The IES total score and both subscales showed high internal consistency in both groups (Cronbach alpha coefficients of approximately .9 or above). Given their equivalent trauma reporting, the lack of differences in IES scores between patients and controls seems to indicate that patients are likely to report accurately and neither exaggerate nor minimize their posttraumatic symptoms. Overall, the findings suggest that the IES can be used to assess symptoms of posttraumatic stress in patients with psychotic disorders as in other populations.
PMCID: PMC3825662  PMID: 22048144
trauma; post-traumatic stress; first-episode psychosis; reliability
4.  Gender Differences in Neuropsychological Performance across Psychotic Disorders – a Multi-Centre Population Based Case-Control Study 
PLoS ONE  2013;8(10):e77318.
Patients with schizophrenia and other psychoses exhibit a wide range of neuropsychological deficits. An unresolved question concerns whether there are gender differences in cognitive performance.
Data were derived from a multi-centre population based case-control study of patients with first-episode psychosis. A neuropsychological test battery was administered to patients with a diagnosis of schizophrenia or schizoaffective disorder (N=70, 36% females), bipolar/mania (N=34, 60% females), depressive psychosis (N=36, 58% females) and healthy controls (N=148, 55% females). Generalized and specific cognitive deficits were compared.
There was strong evidence for disorder-specific gender differences in neuropsychological performance. Males and females with schizophrenia showed similar pervasive neuropsychological impairments. In psychotic depressive disorder females performed worse than males across neuropsychological measures. Differences in neuropsychological performance between males and females with bipolar/manic disorder were restricted to language functions. Symptom severity did not contribute to the observed gender differences.
Early in the course of psychotic illness, gender related factors appear to moderate the severity of cognitive deficits in depressive psychosis and bipolar/mania patients.
PMCID: PMC3810462  PMID: 24204806
5.  TREM2 Variants in Alzheimer's Disease 
The New England journal of medicine  2012;368(2):117-127.
Homozygous loss-of-function mutations in TREM2, encoding the triggering receptor expressed on myeloid cells 2 protein, have previously been associated with an autosomal recessive form of early-onset dementia.
We used genome, exome, and Sanger sequencing to analyze the genetic variability in TREM2 in a series of 1092 patients with Alzheimer's disease and 1107 controls (the discovery set). We then performed a meta-analysis on imputed data for the TREM2 variant rs75932628 (predicted to cause a R47H substitution) from three genomewide association studies of Alzheimer's disease and tested for the association of the variant with disease. We genotyped the R47H variant in an additional 1887 cases and 4061 controls. We then assayed the expression of TREM2 across different regions of the human brain and identified genes that are differentially expressed in a mouse model of Alzheimer's disease and in control mice.
We found significantly more variants in exon 2 of TREM2 in patients with Alzheimer's disease than in controls in the discovery set (P = 0.02). There were 22 variant alleles in 1092 patients with Alzheimer's disease and 5 variant alleles in 1107 controls (P<0.001). The most commonly associated variant, rs75932628 (encoding R47H), showed highly significant association with Alzheimer's disease (P<0.001). Meta-analysis of rs75932628 genotypes imputed from genomewide association studies confirmed this association (P = 0.002), as did direct genotyping of an additional series of 1887 patients with Alzheimer's disease and 4061 controls (P<0.001). Trem2 expression differed between control mice and a mouse model of Alzheimer's disease.
Heterozygous rare variants in TREM2 are associated with a significant increase in the risk of Alzheimer's disease. (Funded by Alzheimer's Research UK and others.)
PMCID: PMC3631573  PMID: 23150934
6.  Linking Protective GAB2 Variants, Increased Cortical GAB2 Expression and Decreased Alzheimer’s Disease Pathology 
PLoS ONE  2013;8(5):e64802.
GRB-associated binding protein 2 (GAB2) represents a compelling genome-wide association signal for late-onset Alzheimer’s disease (LOAD) with reported odds ratios (ORs) ranging from 0.75–0.85. We tested eight GAB2 variants in four North American Caucasian case-control series (2,316 LOAD, 2,538 controls) for association with LOAD. Meta-analyses revealed ORs ranging from (0.61–1.20) with no significant association (all p>0.32). Four variants were hetergeneous across the populations (all p<0.02) due to a potentially inflated effect size (OR = 0.61–0.66) only observed in the smallest series (702 LOAD, 209 controls). Despite the lack of association in our series, the previously reported protective association for GAB2 remained after meta-analyses of our data with all available previously published series (11,952-22,253 samples; OR = 0.82–0.88; all p<0.04). Using a freely available database of lymphoblastoid cell lines we found that protective GAB2 variants were associated with increased GAB2 expression (p = 9.5×10−7−9.3×10−6). We next measured GAB2 mRNA levels in 249 brains and found that decreased neurofibrillary tangle (r = −0.34, p = 0.0006) and senile plaque counts (r = −0.32, p = 0.001) were both good predictors of increased GAB2 mRNA levels albeit that sex (r = −0.28, p = 0.005) may have been a contributing factor. In summary, we hypothesise that GAB2 variants that are protective against LOAD in some populations may act functionally to increase GAB2 mRNA levels (in lymphoblastoid cells) and that increased GAB2 mRNA levels are associated with significantly decreased LOAD pathology. These findings support the hypothesis that Gab2 may protect neurons against LOAD but due to significant population heterogeneity, it is still unclear whether this protection is detectable at the genetic level.
PMCID: PMC3665686  PMID: 23724096
7.  A multi-centre study of ACE and the risk of late-onset Alzheimer’s disease 
A key pathological feature of late-onset Alzheimer’s disease (LOAD) is the abnormal extracellular accumulation of the amyloid beta (Aβ) peptide. Thus altered Aβ degradation could be a major contributor to the development of LOAD. Variants in the gene encoding the Aβ-degrading enzyme, angiotensin-1 converting enzyme (ACE) therefore represent plausible candidates for association with LOAD pathology and risk. Following Alzgene meta-analyses of all published case-control studies, the ACE variants rs4291 and rs1800764 showed significant association with LOAD risk. Furthermore ACE haplotypes are associated with both plasma ACE levels and LOAD risk. We tested three ACE variants (rs4291, rs4343 and rs1800764) for association with LOAD in ten Caucasian case-control populations (n=8,212). No association was found using multiple logistic models (all p>0.09). We found no population heterogeneity (all p>0.38) or evidence for association with LOAD risk following meta-analysis of the ten populations for rs4343 (OR=1.00), rs4291 (OR=0.97) or rs1800764 (OR=0.99). Although we found no haplotypic association in our complete dataset (p=0.51), a significant global haplotypic p-value was observed in one population (p=0.007) due to an association of the H3 haplotype (OR=0.72, p=0.02) and a trend towards an association of H4 (OR=1.38, p=0.09) and H7 (OR=2.07, p=0.08) although these did not survive Bonferroni correction. Previously reported associations of ACE variants with LOAD will be diminished following this study. At best, ACE variants have modest effect sizes, which are likely part of a complex interaction between genetic, phenotypic and pharmacological effects that would be undetected in traditional case-control studies.
PMCID: PMC3655234  PMID: 21297258
Alzheimer Disease; Late Onset; Angiotensin-1 Converting Enzyme; Haplotype; Heterogeneity; Meta-Analysis
8.  Transcript and protein profiling identifies signaling, growth arrest, apoptosis, and NF-κB survival signatures following GNRH receptor activation 
Endocrine-Related Cancer  2013;20(1):123-136.
GNRH significantly inhibits proliferation of a proportion of cancer cell lines by activating GNRH receptor (GNRHR)-G protein signaling. Therefore, manipulation of GNRHR signaling may have an under-utilized role in treating certain breast and ovarian cancers. However, the precise signaling pathways necessary for the effect and the features of cellular responses remain poorly defined. We used transcriptomic and proteomic profiling approaches to characterize the effects of GNRHR activation in sensitive cells (HEK293-GNRHR, SCL60) in vitro and in vivo, compared to unresponsive HEK293. Analyses of gene expression demonstrated a dynamic response to the GNRH superagonist Triptorelin. Early and mid-phase changes (0.5–1.0 h) comprised mainly transcription factors. Later changes (8–24 h) included a GNRH target gene, CGA, and up- or downregulation of transcripts encoding signaling and cell division machinery. Pathway analysis identified altered MAPK and cell cycle pathways, consistent with occurrence of G2/M arrest and apoptosis. Nuclear factor kappa B (NF-κB) pathway gene transcripts were differentially expressed between control and Triptorelin-treated SCL60 cultures. Reverse-phase protein and phospho-proteomic array analyses profiled responses in cultured cells and SCL60 xenografts in vivo during Triptorelin anti-proliferation. Increased phosphorylated NF-κB (p65) occurred in SCL60 in vitro, and p-NF-κB and IκBϵ were higher in treated xenografts than controls after 4 days Triptorelin. NF-κB inhibition enhanced the anti-proliferative effect of Triptorelin in SCL60 cultures. This study reveals details of pathways interacting with intense GNRHR signaling, identifies potential anti-proliferative target genes, and implicates the NF-κB survival pathway as a node for enhancing GNRH agonist-induced anti-proliferation.
PMCID: PMC3573841  PMID: 23202794
GnRh; NFκB; triptorelin; xenograft; SCL60
9.  Next generation sequencing of CLU, PICALM and CR1: pitfalls and potential solutions 
CLU, PICALM and CR1 were identified as genetic risk factors for late onset Alzheimer’s disease (AD) in two large genome wide association studies (GWAS) published in 2009, but the variants that convey this alteration in disease risk, and how the genes relate to AD pathology is yet to be discovered. A next generation sequencing (NGS) project was conducted targeting CLU, CR1 and PICALM, in 96 AD samples (8 pools of 12), in an attempt to discover rare variants within these AD associated genes. Inclusion of repetitive regions in the design of the SureSelect capture lead to significant issues in alignment of the data, leading to poor specificity and a lower than expected depth of coverage. A strong positive correlation (0.964, p<0.001) was seen between NGS and 1000 genome project frequency estimates. Of the ~170 “novel” variants detected in the genes, seven SNPs, all of which were present in multiple sample pools, were selected for validation by Sanger sequencing. Two SNPs were successfully validated by this method, and shown to be genuine variants, while five failed validation. These spurious SNP calls occurred as a result of the presence of small indels and mononucleotide repeats, indicating such features should be regarded with caution, and validation via an independent method is important for NGS variant calls.
PMCID: PMC3508540  PMID: 23205178
Next generation sequencing; Alzheimer’s disease; genes; CLU; PICALM; CR1
10.  Replication of BIN1 association with Alzheimer’s disease and evaluation of genetic interactions 
The most recent late-onset Alzheimer’s disease (LOAD) genome-wide association study revealed genome-wide significant association of two new loci: rs744373 near BIN1 (p=1.6×10−11) and rs597668 near EXOC3L2/BLOC1S3/MARK4 (p=6.5×10−9). We have genotyped these variants in a large (3,287 LOAD, 4,396 controls), independent dataset comprising eleven case-control series from the USA and Europe. We performed meta-analyses of the association of these variants with LOAD and also tested for association using logistic regression adjusted by age-at-diagnosis, sex and APOE ε4 status. Meta-analysis results showed no evidence of series heterogeneity and logistic regression analysis successfully replicated the association of BIN1 (rs744373) with LOAD with an odds ratio (OR=1.17, p=1.1×10−4) comparable to that previously reported (OR=1.15). The variant near EXOC3L2 (rs597668) showed only suggestive association with LOAD (p=0.09) after correcting for the presence of the APOE ε4 allele. Addition of our follow-up data to the results previously reported increased the strength of evidence for association with BIN1 (11,825 LOAD, 32,570 controls, rs744373 Fisher combined p=3.8×10−20). We also tested for epistatic interaction between these variants and APOEε4 as well as with the previously replicated LOAD GWAS genes (CLU: rs11136000, CR1; rs3818361, and PICALM: rs3851179). No significant interactions between these genes were detected. In summary, we provide additional evidence for the variant near BIN1 (rs744373) as a LOAD risk modifier, but our results indicate that the effect of EXOC3L2 independent of APOE ε4 should be studied further.
PMCID: PMC3489170  PMID: 21321396
Alzheimer Disease; Late Onset; Heterogeneity; Meta-Analysis; Case-Control Studies
11.  No consistent evidence for association between mtDNA variants and Alzheimer disease 
Hudson, G. | Sims, R. | Harold, D. | Chapman, J. | Hollingworth, P. | Gerrish, A. | Russo, G. | Hamshere, M. | Moskvina, V. | Jones, N. | Thomas, C. | Stretton, A. | Holmans, P.A. | O'Donovan, M.C. | Owen, M.J. | Williams, J. | Chinnery, P.F. | Harold, Denise | Abraham, Richard | Hollingworth, Paul | Sims, Rebecca | Gerrish, Amy | Chapman, Jade | Russo, Giancarlo | Hamshere, Marian | Pahwa, Jaspreet Singh | Moskvina, Valentina | Dowzell, Kimberley | Williams, Amy | Jones, Nicola | Thomas, Charlene | Stretton, Alexandra | Morgan, Angharad | Lovestone, Simon | Powell, John | Proitsi, Petroula | Lupton, Michelle K | Brayne, Carol | Rubinsztein, David C. | Gill, Michael | Lawlor, Brian | Lynch, Aoibhinn | Morgan, Kevin | Brown, Kristelle | Passmore, Peter | Craig, David | McGuinness, Bernadette | Todd, Stephen | Johnston, Janet | Holmes, Clive | Mann, David | Smith, A. David | Love, Seth | Kehoe, Patrick G. | Hardy, John | Mead, Simon | Fox, Nick | Rossor, Martin | Collinge, John | Maier, Wolfgang | Jessen, Frank | Heun, Reiner | Kölsch, Heike | Schürmann, Britta | van den Bussche, Hendrik | Heuser, Isabella | Kornhuber, Johannes | Wiltfang, Jens | Dichgans, Martin | Frölich, Lutz | Hampel, Harald | Hüll, Michael | Rujescu, Dan | Goate, Alison | Kauwe, John S.K. | Cruchaga, Carlos | Nowotny, Petra | Morris, John C. | Mayo, Kevin | Livingston, Gill | Bass, Nicholas J. | Gurling, Hugh | McQuillin, Andrew | Gwilliam, Rhian | Deloukas, Panagiotis | Holmans, Peter | O'Donovan, Michael | Owen, Michael J. | Williams, Julie
Neurology  2012;78(14):1038-1042.
Although several studies have described an association between Alzheimer disease (AD) and genetic variation of mitochondrial DNA (mtDNA), each has implicated different mtDNA variants, so the role of mtDNA in the etiology of AD remains uncertain.
We tested 138 mtDNA variants for association with AD in a powerful sample of 4,133 AD case patients and 1,602 matched controls from 3 Caucasian populations. Of the total population, 3,250 case patients and 1,221 elderly controls met the quality control criteria and were included in the analysis.
In the largest study to date, we failed to replicate the published findings. Meta-analysis of the available data showed no evidence of an association with AD.
The current evidence linking common mtDNA variations with AD is not compelling.
PMCID: PMC3317529  PMID: 22442439
12.  Reliability and Comparability of Psychosis Patients’ Retrospective Reports of Childhood Abuse 
Schizophrenia Bulletin  2009;37(3):546-553.
An increasing number of studies are demonstrating an association between childhood abuse and psychosis. However, the majority of these rely on retrospective self-reports in adulthood that may be unduly influenced by current psychopathology. We therefore set out to explore the reliability and comparability of first-presentation psychosis patients’ reports of childhood abuse. Psychosis case subjects were drawn from the Aetiology and Ethnicity of Schizophrenia and Other Psychoses (ÆSOP) epidemiological study and completed the Childhood Experience of Care and Abuse Questionnaire to elicit abusive experiences that occurred prior to 16 years of age. High levels of concurrent validity were demonstrated with the Parental Bonding Instrument (antipathy: rs = 0.350–0.737, P < .001; neglect: rs = 0.688–0.715, P < .001), and good convergent validity was shown with clinical case notes (sexual abuse: κ = 0.526, P < .001; physical abuse: κ = 0.394, P < .001). Psychosis patients’ reports were also reasonably stable over a 7-year period (sexual abuse: κ = 0.590, P < .01; physical abuse: κ = 0.634, P < .001; antipathy: κ = 0.492, P < .01; neglect: κ = 0.432, P < .05). Additionally, their reports of childhood abuse were not associated with current severity of psychotic symptoms (sexual abuse: U = 1768.5, P = .998; physical abuse: U = 2167.5, P = .815; antipathy: U = 2216.5, P = .988; neglect: U = 1906.0, P = .835) or depressed mood (sexual abuse: χ2 = 0.634, P = .277; physical abuse: χ2 = 0.159, P = .419; antipathy: χ2 = 0.868, P = .229; neglect: χ2 = 0.639, P = .274). These findings provide justification for the use in future studies of retrospective reports of childhood abuse obtained from individuals with psychotic disorders.
PMCID: PMC3080697  PMID: 19776204
psychotic disorders; child abuse; trauma; schizophrenia; psychometrics
13.  Interactions between PPAR-α and inflammation-related cytokine genes on the development of Alzheimer’s disease, observed by the Epistasis Project 
Neuroinflammation contributes to the pathogenesis of sporadic Alzheimer’s disease (AD). Variations in genes relevant to inflammation may be candidate genes for AD risk. Whole-genome association studies have identified relevant new and known genes. Their combined effects do not explain 100% of the risk, genetic interactions may contribute. We investigated whether genes involved in inflammation, i.e. PPAR-α, interleukins (IL) IL- 1α, IL-1β, IL-6, and IL-10 may interact to increase AD risk.
The Epistasis Project identifies interactions that affect the risk of AD. Genotyping of single nucleotide polymorphisms (SNPs) in PPARA, IL1A, IL1B, IL6 and IL10 was performed. Possible associations were analyzed by fitting logistic regression models with AD as outcome, controlling for centre, age, sex and presence of apolipoprotein ε4 allele (APOEε4). Adjusted synergy factors were derived from interaction terms (p<0.05 two-sided).
We observed four significant interactions between different SNPs in PPARA and in interleukins IL1A, IL1B, IL10 that may affect AD risk. There were no significant interactions between PPARA and IL6.
In addition to an association of the PPARA L162V polymorphism with the AD risk, we observed four significant interactions between SNPs in PPARA and SNPs in IL1A, IL1B and IL10 affecting AD risk. We prove that gene-gene interactions explain part of the heritability of AD and are to be considered when assessing the genetic risk. Necessary replications will require between 1450 and 2950 of both cases and controls, depending on the prevalence of the SNP, to have 80% power to detect the observed synergy factors.
PMCID: PMC3316448  PMID: 22493750
AD; genetics; epistasis; inflammation; interleukin; steroid receptors; PPAR-alpha; sporadic; genetic interaction
14.  The varying impact of type, timing and frequency of exposure to childhood adversity on its association with adult psychotic disorder 
Psychological medicine  2010;40(12):1967-1978.
Childhood adversity has been associated with onset of psychosis in adulthood but these studies have used only general definitions of this environmental risk indicator. Therefore, we sought to explore the prevalence of more specific adverse childhood experiences amongst those with and without psychotic disorders using detailed assessments in a large epidemiological case-control sample (ÆSOP).
Data were collected on 182 first-presentation psychosis cases and 246 geographically-matched controls in two UK centres. Information relating to the timing and frequency of exposure to different types of childhood adversity (neglect, antipathy, physical and sexual abuse, local authority care, disrupted living arrangements and lack of supportive figure) was obtained using the Childhood Experience of Care and Abuse Questionnaire.
Psychosis cases were three times more likely to report severe physical abuse from mother that commenced prior to 12 years of age, even after adjustment for other significant forms of adversity and demographic confounders. A non-significant trend was also evident for greater prevalence of reported severe maternal antipathy amongst those with psychosis. Associations with maternal neglect and childhood sexual abuse disappeared after adjusting for maternal physical abuse and antipathy. Paternal maltreatment and other forms of adversity were not associated with psychosis nor was there evidence of a dose-response effect.
These findings suggest that only specific adverse childhood experiences are associated with psychotic disorders and only in a minority of cases. If replicated, this greater precision will ensure that research into the mechanisms underlying the pathway from childhood adversity to psychosis is more fruitful.
PMCID: PMC3272393  PMID: 20178679
child abuse; psychotic disorders; childhood trauma; aetiology; psychosis
15.  A Whole-Body Model for Glycogen Regulation Reveals a Critical Role for Substrate Cycling in Maintaining Blood Glucose Homeostasis 
PLoS Computational Biology  2011;7(12):e1002272.
Timely, and sometimes rapid, metabolic adaptation to changes in food supply is critical for survival as an organism moves from the fasted to the fed state, and vice versa. These transitions necessitate major metabolic changes to maintain energy homeostasis as the source of blood glucose moves away from ingested carbohydrates, through hepatic glycogen stores, towards gluconeogenesis. The integration of hepatic glycogen regulation with extra-hepatic energetics is a key aspect of these adaptive mechanisms. Here we use computational modeling to explore hepatic glycogen regulation under fed and fasting conditions in the context of a whole-body model. The model was validated against previous experimental results concerning glycogen phosphorylase a (active) and glycogen synthase a dynamics. The model qualitatively reproduced physiological changes that occur during transition from the fed to the fasted state. Analysis of the model reveals a critical role for the inhibition of glycogen synthase phosphatase by glycogen phosphorylase a. This negative regulation leads to high levels of glycogen synthase activity during fasting conditions, which in turn increases substrate (futile) cycling, priming the system for a rapid response once an external source of glucose is restored. This work demonstrates that a mechanistic understanding of the design principles used by metabolic control circuits to maintain homeostasis can benefit from the incorporation of mathematical descriptions of these networks into “whole-body” contextual models that mimic in vivo conditions.
Author Summary
Homeostasis of blood glucose concentrations during circadian shifts in survival-related activities, sleep and food availability is crucial for the survival of mammals. This process depends upon glucose intake, short-term storage as glycogen, and gluconeogenesis. The integration of hepatic glycogen anabolic and catabolic dynamics with whole body energetics is critical for survival. In this paper we use computational modeling to investigate the potential survival advantage of substrate (futile) cycling of glycogen and glycogen precursors. Our simulations, combined with published experimental results of other researchers, indicate that as the body enters a state of fasting, the activity of enzymes involved in the synthesis of glycogen increases leading to increased substrate cycling. This increase in substrate cycling allows the system to respond more rapidly once new external sources of glucose become available. The whole-body computational model developed for this work allows the metabolic control circuitry to be studied under simulated in vivo conditions, providing functional insights that are not evident when individual modules of glycogen regulatory circuitry are examined in isolation.
PMCID: PMC3233304  PMID: 22163177
16.  GnRH receptor activation competes at a low level with growth signaling in stably transfected human breast cell lines 
BMC Cancer  2011;11:476.
Gonadotrophin releasing hormone (GnRH) analogs lower estrogen levels in pre-menopausal breast cancer patients. GnRH receptor (GnRH-R) activation also directly inhibits the growth of certain cells. The applicability of GnRH anti-proliferation to breast cancer was therefore analyzed.
GnRH-R expression in 298 primary breast cancer samples was measured by quantitative immunofluorescence. Levels of functional GnRH-R in breast-derived cell lines were assessed using 125I-ligand binding and stimulation of 3H-inositol phosphate production. Elevated levels of GnRH-R were stably expressed in cells by transfection. Effects of receptor activation on in vitro cell growth were investigated in comparison with IGF-I and EGF receptor inhibition, and correlated with intracellular signaling using western blotting.
GnRH-R immunoscoring was highest in hormone receptor (triple) negative and grade 3 breast tumors. However prior to transfection, functional endogenous GnRH-R were undetectable in four commonly studied breast cancer cell lines (MCF-7, ZR-75-1, T47D and MDA-MB-231). After transfection with GnRH-R, high levels of cell surface GnRH-R were detected in SVCT and MDA-MB-231 clones while low-moderate levels of GnRH-R occurred in MCF-7 clones and ZR-75-1 clones. MCF-7 sub-clones with high levels of GnRH-R were isolated following hygromycin phosphotransferase transfection. High level cell surface GnRH-R enabled induction of high levels of 3H-inositol phosphate and modest growth-inhibition in SVCT cells. In contrast, growth of MCF-7, ZR-75-1 or MDA-MB-231 clones was unaffected by GnRH-R activation. Cell growth was inhibited by IGF-I or EGF receptor inhibitors. IGF-I receptor inhibitor lowered levels of p-ERK1/2 in MCF-7 clones. Washout of IGF-I receptor inhibitor resulted in transient hyper-elevation of p-ERK1/2, but co-addition of GnRH-R agonist did not alter the dynamics of ERK1/2 re-phosphorylation.
Breast cancers exhibit a range of GnRH-R immunostaining, with higher levels of expression found in triple-negative and grade 3 cancers. However, functional cell surface receptors are rare in cultured cells. Intense GnRH-R signaling in transfected breast cancer cells did not markedly inhibit growth, in contrast to transfected HEK 293 cells indicating the importance of intracellular context. GnRH-R signaling could not counteract IGF-I receptor-tyrosine kinase addiction in MCF-7 cells. These results suggest that combinatorial strategies with growth factor inhibitors will be needed to enhance GnRH anti-proliferative effects in breast cancer
PMCID: PMC3227622  PMID: 22051164
17.  Replication of CLU, CR1 and PICALM associations with Alzheimer’s disease 
Archives of neurology  2010;67(8):961-964.
Harold et al. and Lambert et al. recently published two large genome-wide association studies of late onset Alzheimer’s disease (LOAD) in which CLU, CR1, and PICALM were identified as novel LOAD genes.
To test for replication of the association between variants in the CLU, CR1 and PICALM genes with Alzheimer’s disease.
Case-control association study
Community-based ascertainment of patients seen at the Mayo Clinic Jacksonville, FL and Rochester, MN, and autopsy-confirmed cases and controls whose pathology was evaluated at the Mayo Clinic Jacksonville. Additional samples were obtained from the National Cell Repository for Alzheimer’s Disease (NCRAD).
LOAD case-control series of European descent consisting of 1,829 LOAD cases and 2,576 controls
Main Outcome Measure
Clinical or pathology-confirmed diagnosis of LOAD
In our follow-up study of 1,829 LOAD cases and 2,576 controls, the most significant SNPs in CLU (rs11136000), CR1 (rs3818361), and PICALM (rs3851179) were tested for allelic association and gave ORs of 0.82, 1.15, and 0.80 respectively that were comparable in direction and magnitude to those originally reported with p values of 8.6×10−5, 0.014, and 1.3×10−5 that were significant even after Bonferroni correction for 3 SNPs tested.
These results showing near perfect replication provide the first additional evidence that CLU, CR1, and PICALM are LOAD genes.
PMCID: PMC2919638  PMID: 20554627
18.  Replication of EPHA1 and CD33 associations with late-onset Alzheimer's disease: a multi-centre case-control study 
A recently published genome-wide association study (GWAS) of late-onset Alzheimer's disease (LOAD) revealed genome-wide significant association of variants in or near MS4A4A, CD2AP, EPHA1 and CD33. Meta-analyses of this and a previously published GWAS revealed significant association at ABCA7 and MS4A, independent evidence for association of CD2AP, CD33 and EPHA1 and an opposing yet significant association of a variant near ARID5B. In this study, we genotyped five variants (in or near CD2AP, EPHA1, ARID5B, and CD33) in a large (2,634 LOAD, 4,201 controls), independent dataset comprising six case-control series from the USA and Europe. We performed meta-analyses of the association of these variants with LOAD and tested for association using logistic regression adjusted by age-at-diagnosis, gender, and APOE ε4 dosage.
We found no significant evidence of series heterogeneity. Associations with LOAD were successfully replicated for EPHA1 (rs11767557; OR = 0.87, p = 5 × 10-4) and CD33 (rs3865444; OR = 0.92, p = 0.049), with odds ratios comparable to those previously reported. Although the two ARID5B variants (rs2588969 and rs494288) showed significant association with LOAD in meta-analysis of our dataset (p = 0.046 and 0.008, respectively), the associations did not survive adjustment for covariates (p = 0.30 and 0.11, respectively). We had insufficient evidence in our data to support the association of the CD2AP variant (rs9349407, p = 0.56).
Our data overwhelmingly support the association of EPHA1 and CD33 variants with LOAD risk: addition of our data to the results previously reported (total n > 42,000) increased the strength of evidence for these variants, providing impressive p-values of 2.1 × 10-15 (EPHA1) and 1.8 × 10-13 (CD33).
PMCID: PMC3157442  PMID: 21798052
19.  Multiple Insulin Degrading Enzyme Variants Alter In Vitro Reporter Gene Expression 
PLoS ONE  2011;6(6):e21429.
The insulin degrading enzyme (IDE) variant, v311 (rs6583817), is associated with increased post-mortem cerebellar IDE mRNA, decreased plasma β-amyloid (Aβ), decreased risk for Alzheimer's disease (AD) and increased reporter gene expression, suggesting that it is a functional variant driving increased IDE expression. To identify other functional IDE variants, we have tested v685, rs11187061 (associated with decreased cerebellar IDE mRNA) and variants on H6, the haplotype tagged by v311 (v10; rs4646958, v315; rs7895832, v687; rs17107734 and v154; rs4646957), for altered in vitro reporter gene expression. The reporter gene expression levels associated with the second most common haplotype (H2) successfully replicated the post-mortem findings in hepatocytoma (0.89 fold-change, p = 0.04) but not neuroblastoma cells. Successful in vitro replication was achieved for H6 in neuroblastoma cells when the sequence was cloned 5′ to the promoter (1.18 fold-change, p = 0.006) and 3′ to the reporter gene (1.29 fold change, p = 0.003), an effect contributed to by four variants (v10, v315, v154 and v311). Since IDE mediates Aβ degradation, variants that regulate IDE expression could represent good therapeutic targets for AD.
PMCID: PMC3120874  PMID: 21731745
20.  Murine J774 Macrophages Recognize LPS/IFN-g, Non-CpG DNA or Two-CpG DNA-containing Sequences as Immunologically Distinct 
Specific bacterial lipopolysaccharides (LPS), IFN-γ, and unmethylated cytosine or guanosine-phosphorothioate containing DNAs (CpG) activate host immunity, influencing infectious responses. Macrophages detect, inactivate and destroy infectious particles, and synthetic CpG sequences invoke similar responses of the innate immune system. Previously, murine macrophage J774 cells treated with CpG induced the expression of nitric oxide synthase 2 (NOS2) and cyclo-oxygenase 2 (COX2) mRNA and protein. In this study murine J774 macrophages were exposed to vehicle, interferon γ + lipopolysaccharide (IFN-g/LPS), non-CpG (SAK1), or two-CpG sequence-containing DNA (SAK2) for 0–18 hr and gene expression changes measured. A large number of immunostimulatory and inflammatory changes were observed. SAK2 was a stronger activator of TNFα- and chemokine expression-related changes than LPS/IFN-g. Up regulation included tumor necrosis factor receptor superfamily genes (TNFRSF’s), IL-1 receptor signaling via stress-activated protein kinase (SAPK), NF-κB activation, hemopoietic maturation factors and sonic hedgehog/wingless integration site (SHH/Wnt) pathway genes. Genes of the TGF-β pathway were down regulated. In contrast, LPS/IFN-g -treated cells showed increased levels for TGF-β signaling genes, which may be linked to the observed up regulation of numerous collagens and down regulation of Wnt pathway genes. SAK1 produced distinct changes from LPS/IFN-g or SAK2. Therefore, J774 macrophages recognize LPS/IFN-g, non-CpG DNA or two-CpG DNA-containing sequences as immunologically distinct.
PMCID: PMC2833108  PMID: 20097302
bacterial; chemokines; cytokines; endotoxin shock; gene regulation; hematopoiesis; J774; monocytes/macrophages; murine
21.  The role of IREB2 and transforming growth factor beta-1 genetic variants in COPD: a replication case-control study 
BMC Medical Genetics  2011;12:24.
Genetic factors are known to contribute to COPD susceptibility and these factors are not fully understood. Conflicting results have been reported for many genetic studies of candidate genes based on their role in the disease. Genome-wide association studies in combination with expression profiling have identified a number of new candidates including IREB2. A meta-analysis has implicated transforming growth factor beta-1 (TGFbeta1) as a contributor to disease susceptibility.
We have examined previously reported associations in both genes in a collection of 1017 white COPD patients and 912 non-diseased smoking controls. Genotype information was obtained for seven SNPs in the IREB2 gene, and for four SNPs in the TGFbeta1 gene. Allele and genotype frequencies were compared between COPD cases and controls, and odds ratios were calculated. The analysis was adjusted for age, sex, smoking and centre, including interactions of age, sex and smoking with centre.
Our data replicate the association of IREB2 SNPs in association with COPD for SNP rs2568494, rs2656069 and rs12593229 with respective adjusted p-values of 0.0018, 0.0039 and 0.0053. No significant associations were identified for TGFbeta1.
These studies have therefore confirmed that the IREB2 locus is a contributor to COPD susceptibility and suggests a new pathway in COPD pathogenesis invoking iron homeostasis.
PMCID: PMC3047296  PMID: 21320324
22.  Correction: Genetic Evidence Implicates the Immune System and Cholesterol Metabolism in the Aetiology of Alzheimer's Disease 
Jones, Lesley | Holmans, Peter A. | Hamshere, Marian L. | Harold, Denise | Moskvina, Valentina | Ivanov, Dobril | Pocklington, Andrew | Abraham, Richard | Hollingworth, Paul | Sims, Rebecca | Gerrish, Amy | Pahwa, Jaspreet Singh | Jones, Nicola | Stretton, Alexandra | Morgan, Angharad R. | Lovestone, Simon | Powell, John | Proitsi, Petroula | Lupton, Michelle K. | Brayne, Carol | Rubinsztein, David C. | Gill, Michael | Lawlor, Brian | Lynch, Aoibhinn | Morgan, Kevin | Brown, Kristelle S. | Passmore, Peter A. | Craig, David | McGuinness, Bernadette | Todd, Stephen | Holmes, Clive | Mann, David | Smith, A. David | Love, Seth | Kehoe, Patrick G. | Mead, Simon | Fox, Nick | Rossor, Martin | Collinge, John | Maier, Wolfgang | Jessen, Frank | Schürmann, Britta | van den Bussche, Hendrik | Heuser, Isabella | Peters, Oliver | Kornhuber, Johannes | Wiltfang, Jens | Dichgans, Martin | Frölich, Lutz | Hampel, Harald | Hüll, Michael | Rujescu, Dan | Goate, Alison M. | Kauwe, John S. K. | Cruchaga, Carlos | Nowotny, Petra | Morris, John C. | Mayo, Kevin | Livingston, Gill | Bass, Nicholas J. | Gurling, Hugh | McQuillin, Andrew | Gwilliam, Rhian | Deloukas, Panos | Al-Chalabi, Ammar | Shaw, Christopher E. | Singleton, Andrew B. | Guerreiro, Rita | Mühleisen, Thomas W. | Nöthen, Markus M. | Moebus, Susanne | Jöckel, Karl-Heinz | Klopp, Norman | Wichmann, H.-Erich | Rüther, Eckhard | Carrasquillo, Minerva M. | Pankratz, V. Shane | Younkin, Steven G. | Hardy, John | O'Donovan, Michael C. | Owen, Michael J. | Williams, Julie
PLoS ONE  2011;6(2):10.1371/annotation/a0bb886d-d345-4a20-a82e-adce9b047798.
PMCID: PMC3039022
23.  Discovery of potent kisspeptin antagonists delineate physiological mechanisms of gonadotropin regulation 
Neurons that produce gonadotropin-releasing hormone (GnRH) are the final common pathway by which the brain regulates reproduction. GnRH neurons are regulated by an afferent network of kisspeptin-producing neurons. Kisspeptin binds to its cognate receptor on GnRH neurons and stimulates their activity, which in turn provides an obligatory signal for GnRH secretion—thus gating down-stream events supporting reproduction. We have developed kisspeptin antagonists to facilitate the direct determination of the role of kisspeptin neurons in the neuroendocrine regulation of reproduction. In vitro and in vivo studies of analogues of kisspeptin-10 with amino substitutions have identified several potent and specific antagonists. A selected antagonist was shown to inhibit the firing of GnRH neurons in the brain of the mouse and to reduce pulsatile GnRH secretion in female pubertal monkeys; the later supporting a key role of kisspeptin in puberty onset. This analogue also inhibited the kisspeptin-induced release of luteinizing hormone (LH) in rats and mice and blocked the post-castration rise in LH in sheep, rats and mice, suggesting that kisspeptin neurons mediate the negative feedback effect of sex steroids on gonadotropin secretion in mammals. The development of kisspeptin antagonists provides a valuable tool for investigating the physiological and pathophysiological roles of kisspeptin in the regulation of reproduction and could offer a unique therapeutic agent for treating hormone-dependent disorders of reproduction, including precocious puberty, endometriosis, and metastatic prostate cancer.
PMCID: PMC3035813  PMID: 19321788
Kisspeptin; gpr-54; antagonists; steroid feedback; GnRH; LH
24.  Investigation of 15 of the top candidate genes for late-onset Alzheimer’s disease 
Human Genetics  2010;129(3):273-282.
The 12 genome-wide association studies (GWAS) published to-date for late-onset Alzheimer’s disease (LOAD) have identified over 40 candidate LOAD risk modifiers, in addition to apolipoprotein (APOE) ε4. A few of these novel LOAD candidate genes, namely BIN1, CLU, CR1, EXOC3L2 and PICALM, have shown consistent replication, and are thus credible LOAD susceptibility genes. To evaluate other promising LOAD candidate genes, we have added data from our large, case–control series (n = 5,043) to meta-analyses of all published follow-up case–control association studies for six LOAD candidate genes that have shown significant association across multiple studies (TNK1, GAB2, LOC651924, GWA_14q32.13, PGBD1 and GALP) and for an additional nine previously suggested candidate genes. Meta-analyses remained significant at three loci after addition of our data: GAB2 (OR = 0.78, p = 0.007), LOC651924 (OR = 0.91, p = 0.01) and TNK1 (OR = 0.92, p = 0.02). Breslow–Day tests revealed significant heterogeneity between studies for GAB2 (p < 0.0001) and GWA_14q32.13 (p = 0.006). We have also provided suggestive evidence that PGBD1 (p = 0.04) and EBF3 (p = 0.03) are associated with age-at-onset of LOAD. Finally, we tested for interactions between these 15 genes, APOE ε4 and the five novel LOAD genes BIN1, CLU, CR1, EXOC3L2 and PICALM but none were significant after correction for multiple testing. Overall, this large, independent follow-up study for 15 of the top LOAD candidate genes provides support for GAB2 and LOC651924 (6q24.1) as risk modifiers of LOAD and novel associations between PGBD1 and EBF3 with age-at-onset.
Electronic supplementary material
The online version of this article (doi:10.1007/s00439-010-0924-2) contains supplementary material, which is available to authorized users.
PMCID: PMC3036835  PMID: 21132329
25.  Using Fisher's method with PLINK ‘LD clumped’ output to compare SNP effects across Genome-wide Association Study (GWAS) datasets 
As the number of publically available GWAS datasets continues to grow, bioinformatic tools which enable routine manipulation of data are becoming increasingly useful. Meta-analysis using multiple GWAS datasets has become essential to elucidate novel SNP associations which may not be readily discovered in each GWAS individually due to insufficient power. Replication of GWAS findings is critical and is the ‘arbiter’ of genuine SNP associations. We have developed an ‘LD aware’ bioinformatics application which allows efficient comparison of SNP effects across multiple GWAS datasets using Fisher’s combined probability test from PLINK (v1.06) ‘LD clumped’ output. Availability: the application is freely available from the authors.
PMCID: PMC3077236  PMID: 21537399
Genome-wide Association Studies (GWAS); Fisher’s method; bioinformatic tools

Results 1-25 (49)