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1.  Risk stratification of pT1-3N0 patients after radical cystectomy for adjuvant chemotherapy counselling 
British Journal of Cancer  2012;107(11):1826-1832.
In pT1-T3N0 urothelial carcinoma of the bladder (UCB) patients, multi-modal therapy is inconsistently recommended. The aim of the study was to develop a prognostic tool to help decision-making regarding adjuvant therapy.
We included 2145 patients with pT1-3N0 UCB after radical cystectomy (RC), naive of neoadjuvant or adjuvant therapy. The cohort was randomly split into development cohort based on the US patients (n=1067) and validation cohort based on the Europe patients (n=1078). Predictive accuracy was quantified using the concordance index.
With a median follow-up of 45 months, 5-year recurrence-free and cancer-specific survival estimates were 68% and 73%, respectively. pT-stage, ge, lymphovascular invasion, and positive margin were significantly associated with both disease recurrence and cancer-specific mortality (P-values⩽0.005). The accuracies of the multivariable models at 2, 5, and 7 years for predicting disease recurrence were 67.4%, 65%, and 64.4%, respectively. Accuracies at 2, 5, and 7 years for predicting cancer-specific mortality were 69.3%, 66.4%, and 65.5%, respectively. We developed competing-risk, conditional probability nomograms. External validation revealed minor overestimation.
Despite RC, a significant number of patients with pT1-3N0 UCB experience disease recurrence and ultimately die of UCB. We developed and externally validated competing-risk, conditional probability post-RC nomograms for prediction of disease recurrence and cancer-specific mortality.
PMCID: PMC3504939  PMID: 23169335
bladder cancer; radical cystectomy; T1-3 N0; prediction; nomogram; chemotherapy
2.  Genetically defining the mechanism of Puma- and Bim-induced apoptosis 
Cell Death and Differentiation  2011;19(4):642-649.
Using genetically modified mouse models, we report here that p53 upregulated modulator of apoptosis (Puma) and Bcl-2 interacting mediator of cell death (Bim), two pro-apoptotic members of the B-cell lymphoma protein-2 (Bcl-2) family of proteins, cooperate in causing bone marrow and gastrointestinal tract toxicity in response to chemo and radiation therapy. Deletion of both Puma and Bim provides long-term survival without evidence of increased tumor susceptibility following a lethal challenge of carboplatin and ionizing radiation. Consistent with these in vivo findings, studies of primary mast cells demonstrated that the loss of Puma and Bim confers complete protection from cytokine starvation and DNA damage, similar to that observed for Bax/Bak double knockout cells. Biochemical analyses demonstrated an essential role for either Puma or Bim to activate Bax, thereby leading to mitochondrial outer membrane permeability, cytochrome c release and apoptosis. Treatment of cytokine-deprived cells with ABT-737, a BH3 mimetic, demonstrated that Puma is sufficient to activate Bax even in the absence of all other known direct activators, including Bim, Bid and p53. Collectively, our results identify Puma and Bim as key mediators of DNA damage-induced bone marrow failure and provide mechanistic insight into how BH3-only proteins trigger cell death.
PMCID: PMC3307979  PMID: 22015606
Puma; Bim; apoptosis; myelosuppression; ABT-737
3.  Molecular definitions of cell death subroutines: recommendations of the Nomenclature Committee on Cell Death 2012 
Cell Death and Differentiation  2011;19(1):107-120.
In 2009, the Nomenclature Committee on Cell Death (NCCD) proposed a set of recommendations for the definition of distinct cell death morphologies and for the appropriate use of cell death-related terminology, including ‘apoptosis', ‘necrosis' and ‘mitotic catastrophe'. In view of the substantial progress in the biochemical and genetic exploration of cell death, time has come to switch from morphological to molecular definitions of cell death modalities. Here we propose a functional classification of cell death subroutines that applies to both in vitro and in vivo settings and includes extrinsic apoptosis, caspase-dependent or -independent intrinsic apoptosis, regulated necrosis, autophagic cell death and mitotic catastrophe. Moreover, we discuss the utility of expressions indicating additional cell death modalities. On the basis of the new, revised NCCD classification, cell death subroutines are defined by a series of precise, measurable biochemical features.
PMCID: PMC3252826  PMID: 21760595
autophagy; mitochondrial membrane permeabilization; necroptosis; parthanatos; TNFR1; TP53
4.  Caspase-2: the orphan caspase 
Cell Death and Differentiation  2011;19(1):51-57.
Despite an abundance of literature on the role of caspase-2 in apoptosis, there exists much controversy about this protease making it difficult to place caspase-2 correctly in the apoptotic cascade, and hence its role in apoptosis remains unclear. The identification of the PIDDosome as a signaling platform for caspase-2 activation prompted intense investigation into the true role of this orphan caspase. What has emerged is the idea that caspase-2 may not be mandatory for apoptosis and that activation of this caspase in response to some forms of stress has other effects on the cell such as regulation of cell cycle progression. This idea is particularly relevent to the discovery that caspase-2 may act as a tumor suppressor. Here, we discuss the proposed mechanisms through which caspase-2 signals, in particular those involving PIDD, and their impact on cellular fate.
PMCID: PMC3252831  PMID: 22075987
caspase-2; apoptosis; PIDD; PIDDosome; cell cycle
5.  Use of sophisticated intra-operative monitoring in resuscitation of unexpected cardiovascular collapse during general anaesthesia 
The diagnosis of intraoperative anaphylaxis is important but can be difficult as the symptoms can be varying and dependent on patient factors.
We describe an acute, unexpected and life threatening cardiovascular (CV) collapse, presumed to be due to an acute anaphylactic reaction secondary to gelatin administration, following induction of general anaesthesia (GA), in an ASA 3 patient scheduled for axillo-bifemoral bypass.
The management of the profound cardiovascular (CV) collapse was greatly assisted by sophisticated haemodynamic, depth of anaesthesia and cerebral oximetry monitoring.1 As far as we are aware this is the first such case where the full haemodynamic, depth of anaesthesia and cerebral oxygenation changes during CV collapse, presumed due to an acute anaphylactic reaction under GA have been fully documented.
The use of advanced monitoring intraoperatively proved extremely useful in guiding the resuscitation of a life threatening allergic reaction under general anaesthesia.
PMCID: PMC3604686  PMID: 23336989
General anaesthesia; Analphylaxis; Haemodynamic monitoring; Cerebral oximetry; Depth of anaesthesia monitoring
7.  Structural correlates for lexical efficiency and number of languages in non-native speakers of English 
Neuropsychologia  2012;50(7):1347-1352.
► We dissociate structural correlates for two different non-native language skills. ► Number of languages spoken was associated with the posterior supramarginal gyrus. ► The efficiency of word use was associated with the left pars opercularis.
We used structural magnetic resonance imaging (MRI) and voxel based morphometry (VBM) to investigate whether the efficiency of word processing in the non-native language (lexical efficiency) and the number of non-native languages spoken (2+ versus 1) were related to local differences in the brain structure of bilingual and multilingual speakers. We dissociate two different correlates for non-native language processing. Firstly, multilinguals who spoke 2 or more non-native languages had higher grey matter density in the right posterior supramarginal gyrus compared to bilinguals who only spoke one non-native language. This is interpreted in relation to previous studies that have shown that grey matter density in this region is related to the number of words learnt in bilinguals relative to monolinguals and in monolingual adolescents with high versus low vocabulary. Our second result was that, in bilinguals, grey matter density in the left pars opercularis was positively related to lexical efficiency in second language use, as measured by the speed and accuracy of lexical decisions and the number of words produced in a timed verbal fluency task. Grey matter in the same region was also negatively related to the age at which the second language was acquired. This is interpreted in terms of previous findings that associated the left pars opercularis with phonetic expertise in the native language.
PMCID: PMC3382713  PMID: 22401989
Language; Efficiency; Lexical; MRI; Bilingual
8.  Preferential control of induced regulatory T cell homeostasis via a Bim/Bcl-2 axis 
Cell Death & Disease  2012;3(2):e270-.
Apoptosis has an essential role in controlling T cell homeostasis, especially during the contraction phase of an immune response. However, its contribution to the balance between effector and regulatory populations remains unclear. We found that Rag1−/− hosts repopulated with Bim−/− conventional CD4+ T cells (Tconv) resulted in a larger induced regulatory T cell (iTreg) population than mice given wild-type (WT) Tconv. This appears to be due to an increased survival advantage of iTregs compared with activated Tconv in the absence of Bim. Downregulation of Bcl-2 expression and upregulation of Bim expression were more dramatic in WT iTregs than activated Tconv in the absence of IL-2 in vitro. The iTregs generated following Tconv reconstitution of Rag1−/− hosts exhibited lower Bcl-2 expression and higher Bim/Bcl-2 ratio than Tconv, which indicates that iTregs were in an apoptosis-prone state in vivo. A significant proportion of the peripheral iTreg pool exhibits low Bcl-2 expression indicating increased sensitivity to apoptosis, which may be a general characteristic of certain Treg subpopulations. In summary, our data suggest that iTregs and Tconv differ in their sensitivity to apoptotic stimuli due to their altered ratio of Bim/Bcl-2 expression. Modulating the apoptosis pathway may provide novel therapeutic approaches to alter the balance between effector T cells and Tregs.
PMCID: PMC3288351  PMID: 22318539
iTreg; apoptosis; Bim; Bcl-2
9.  Welcome to Oncogenesis 
Oncogenesis  2012;1(2):e2-.
PMCID: PMC3412633  PMID: 23552519
10.  Infection in conflict wounded 
Although mechanisms of modern military wounding may be distinct from those of ancient conflicts, the infectious sequelae of ballistic trauma and the evolving microbial flora of war wounds remain a considerable burden on both the injured combatant and their deployed medical systems. Battlefield surgeons of ancient times favoured suppuration in war wounding and as such Galenic encouragement of pus formation would hinder progress in wound care for centuries. Napoleonic surgeons eventually abandoned this mantra, embracing radical surgical intervention, primarily by amputation, to prevent infection. Later, microscopy enabled identification of microorganisms and characterization of wound flora. Concurrent advances in sanitation and evacuation enabled improved outcomes and establishment of modern military medical systems. Advances in medical doctrine and technology afford those injured in current conflicts with increasing survivability through rapid evacuation, sophisticated resuscitation and timely surgical intervention. Infectious complications in those that do survive, however, are a major concern. Addressing antibiotic use, nosocomial transmission and infectious sequelae are a current clinical management and research priority and will remain so in an era characterized by a massive burden of combat extremity injury. This paper provides a review of infection in combat wounding from a historical setting through to the modern evidence base.
PMCID: PMC3013428  PMID: 21149356
war; wound; infection; trauma; antibiotic; nosocomial
11.  Deep Brain Stimulation of the Periaqueductal Grey (PAG) Induces Vasodilation in Humans 
Hypertension  2011;57(5):e24-e25.
PMCID: PMC3092071  PMID: 21403090
12.  Host immunity to repeated rabies virus infection in big brown bats 
The Journal of General Virology  2010;91(Pt 9):2360-2366.
Bats are natural reservoirs for the majority of lyssaviruses globally, and are unique among mammals in having exceptional sociality and longevity. Given these facets, and the recognized status of bats as reservoirs for rabies viruses (RABVs) in the Americas, individual bats may experience repeated exposure to RABV during their lifetime. Nevertheless, little information exists with regard to within-host infection dynamics and the role of immunological memory that may result from abortive RABV infection in bats. In this study, a cohort of big brown bats (Eptesicus fuscus) was infected intramuscularly in the left and right masseter muscles with varying doses [10−0.1–104.9 median mouse intracerebral lethal doses (MICLD50)] of an E. fuscus RABV variant isolated from a naturally infected big brown bat. Surviving bats were infected a second time at 175 days post-(primary) infection with a dose (103.9–104.9 MICLD50) of the same RABV variant. Surviving bats were infected a third time at either 175 or 305 days post-(secondary) infection with a dose (104.9 MICLD50) of the same RABV variant. When correcting for dose, similar mortality was observed following primary and secondary infection, but reduced mortality was observed following the third and last RABV challenge, despite infection with a high viral dose. Inducible RABV-neutralizing antibody titres post-infection were ephemeral among infected individuals, and dropped below levels of detection in several bats between subsequent infections. These results suggest that long-term repeated infection of bats may confer significant immunological memory and reduced susceptibility to RABV infection.
PMCID: PMC3052523  PMID: 20519458
15.  Alcohol exposure and outcomes in trauma patients 
To determine the injury patterns, complications, and mortality after alcohol consumption in trauma patients.
The Trauma Registry at an American College of Surgeons (ACS) level I center was queried for all patients with a toxicology screen admitted between 1st January 2002 and 31st December 2005. Alcohol-positive (AP) patients were matched to control patients who had a completely negative screen (AN) using age, gender, mechanism, Injury Severity Score (ISS), head Abbreviated Injury Scale (AIS), chest AIS, abdominal AIS, and extremity AIS. Injuries and outcomes were compared between the groups.
As many as 5,317 patients had toxicology data, of which 471 (8.9%) had a positive alcohol screen (AP). A total of 386 AP patients were then matched to 386 control (AN) patients. The AP group had a significantly higher mortality than the AN group overall (23 vs. 13%; p < 0.001), and by ISS stratification: ISS < 16 (6 vs. 0.4%; p < 0.001), ISS 16–25 (53 vs. 28%; p = 0.01), and ISS > 25 (90 vs. 67%; p = 0.01). AP patients had a higher incidence of admission systolic blood pressure < 90 (18 vs. 10%; p < 0.001) and Glasgow Coma Scale (GCS) score ≤ 8 (25 vs. 17%; p = 0.002). AN patients had a significantly higher incidence of hemopneumothorax (11 vs. 7%; p = 0.03), while AP patients had a higher incidence of cardiac arrest (8 vs. 3%; p = 0.004). There was no difference in intensive care unit (ICU) and hospital length of stay.
In a mixed population of trauma patients, an AP screen is associated with an increased incidence of admission hypotension and depressed GCS score. In this case-matched study, alcohol exposure appeared to increase mortality after injury.
PMCID: PMC3150794  PMID: 21837258
Alcohol; Injury; Trauma; Complications; Mortality
16.  Longitudinal assessment of fibrinogen in relation to subclinical cardiovascular disease: the CARDIA study 
To examine the strength of the associations of fibrinogen with subclinical atherosclerosis in healthy persons.
A population-based, prospective, observational study of black and white men and women (Coronary Artery Risk Development in Young Adults [CARDIA]). Fibrinogen levels were measured at year 7 (ages 25–37, n = 2969), and again at year 20 (ages 38–50, n = 2832). Measures of subclinical atherosclerosis (coronary artery calcification [CAC] and carotid intimal-medial thickness [CIMT]) were recorded at year 20.
Over the 13-year study interval (1992–1993 to 2005–2006), fibrinogen rose from a mean of 3.32 to 4.05 g L−1. After adjusting for age, gender and race, fibrinogen was positively associated with greater incidence of CAC and increased CIMT cross-sectionally as well as after 13 years of follow-up (all P-trend < 0.001). After further adjustment for field center, BMI, smoking, education, systolic blood pressure, diabetes, antihypertensive medication use, total and HDL cholesterol, and CRP, significant positive relationships between fibrinogen and incidence of CAC remained for the total cohort longitudinally (P-trend = 0.037), but not cross-sectionally (P-trend = 0.147).
This 13-year study demonstrates that higher levels of fibrinogen during young adulthood are positively associated with incidence of CAC and increased CIMT in middle-age, but the strength of the association declines with increasing age.
PMCID: PMC2856753  PMID: 20025644
atherosclerosis; carotid thickening; coronary calcification; fibrinogen
17.  Depersonalisation/derealisation symptoms in vestibular disease 
Depersonalisation is a subjective experience of unreality and detachment from the self often accompanied by derealisation; the experience of the external world appearing to be strange or unreal. Feelings of unreality can be evoked by disorienting vestibular stimulation.
To identify the prevalence of depersonalisation/derealisation symptoms in patients with peripheral vestibular disease and experimentally to induce these symptoms by vestibular stimulation.
121 healthy subjects and 50 patients with peripheral vestibular disease participated in the study. For comparison with the patients a subgroup of 50 age matched healthy subjects was delineated. All completed (1) an in‐house health screening questionnaire; (2) the General Health Questionnaire (GHQ‐12); (3) the 28‐item depersonalisation/derealisation inventory of Cox and Swinson (2002). Experimental verification of “vestibular induced” depersonalisation/derealisation was assessed in 20 patients and 20 controls during caloric irrigation of the labyrinths.
The frequency and severity of symptoms in vestibular patients was significantly higher than in controls. In controls the most common experiences were of “déjà vu” and “difficulty in concentrating/attending”. In contrast, apart from dizziness, patients most frequently reported derealisation symptoms of “feel as if walking on shifting ground”, “body feels strange/not being in control of self”, and “feel ‘spacey' or ‘spaced out'”. Items permitted discrimination between healthy subjects and vestibular patients in 92% of the cases. Apart from dizziness, caloric stimulation induced depersonalisation/derealisation symptoms which healthy subjects denied ever experiencing before, while patients reported that the symptoms were similar to those encountered during their disease.
Depersonalisation/derealisation symptoms are both different in quality and more frequent under conditions of non‐physiological vestibular stimulation. In vestibular disease, frequent experiences of derealisation may occur because distorted vestibular signals mismatch with the other sensory input to create an incoherent frame of spatial reference which makes the patient feel he or she is detached or separated from the world.
PMCID: PMC2077438  PMID: 16464901
depersonalisation; derealisation; dissociation; vestibular; dizziness
18.  Neonatal hypothermia detection by ThermoSpot in Indian urban slum dwellings 
To look at the performance of ThermoSpot liquid crystal thermometry in detecting neonatal hypothermia.
A comparison was made between skin temperatures taken by ThermoSpot and axillary temperatures taken by digital electric thermometry. Non‐medically trained local volunteers performed daily paired recordings on infants on days 1, 2, 3, 4, 5, 6, and 7 of life.
This is a non‐hospital based study set in the homes of neonates in an underprivileged urban slum community in the developing world.
Inclusion criteria: babies born at home. Exclusion criteria: hospital admission; parental refusal.
The ThermoSpot was stuck to the neonate's abdomen over the liver area on day 1 and removed on day 7.
Main outcome measures
Fixed test properties of ThermoSpot.
Over 180 paired observations, the fixed test properties of ThermoSpot in the detection of hypothermia were: sensitivity 88%; specificity 97%; positive likelihood ratio 29; negative likelihood ratio 0.13.
ThermoSpot performed well when used by non‐medically trained volunteers for the detection of neonatal hypothermia in the homes of an urban slum community.
PMCID: PMC2672686  PMID: 16159955
hypothermia; liquid crystal thermometry; ThermoSpot; temperature
20.  Exploring cross-linguistic vocabulary effects on brain structures using voxel-based morphometry 
Bilingualism (Cambridge, England)  2007;10(2):189-199.
Given that there are neural markers for the acquisition of a non-verbal skill, we review evidence of neural markers for the acquisition of vocabulary. Acquiring vocabulary is critical to learning one’s native language and to learning other languages. Acquisition requires the ability to link an object concept (meaning) to sound. Is there a region sensitive to vocabulary knowledge? For monolingual English speakers, increased vocabulary knowledge correlates with increased grey matter density in a region of the parietal cortex that is well-located to mediate an association between meaning and sound (the posterior supramarginal gyrus). Further this region also shows sensitivity to acquiring a second language. Relative to monolingual English speakers, Italian-English bilinguals show increased grey matter density in the same region.
Differences as well as commonalities might exist in the neural markers for vocabulary where lexical distinctions are also signalled by tone. Relative to monolingual English, Chinese multilingual speakers, like European multilinguals, show increased grey matter density in the parietal region observed previously. However, irrespective of ethnicity, Chinese speakers (both Asian and European) also show highly significant increased grey matter density in two right hemisphere regions (the superior temporal gyrus and the inferior frontal gyrus). They also show increased grey matter density in two left hemisphere regions (middle temporal and superior temporal gyrus). Such increases may reflect additional resources required to process tonal distinctions for lexical purposes or to store tonal differences in order to distinguish lexical items. We conclude with a discussion of future lines of enquiry.
PMCID: PMC2312335  PMID: 18418473
21.  Modelling the initial spread of foot-and-mouth disease through animal movements 
Livestock movements in Great Britain (GB) are well recorded and are a unique record of the network of connections among livestock-holding locations. These connections can be critical for disease spread, as in the 2001 epidemic of foot-and-mouth disease (FMD) in the UK. Here, the movement data are used to construct an individual-farm-based model of the initial spread of FMD in GB and determine the susceptibility of the GB livestock industry to future outbreaks under the current legislative requirements. Transmission through movements is modelled, with additional local spread unrelated to the known movements. Simulations show that movements can result in a large nationwide epidemic, but only if cattle are heavily involved, or the epidemic occurs in late summer or early autumn. Inclusion of random local spread can considerably increase epidemic size, but has only a small impact on the spatial extent of the disease. There is a geographical bias in the epidemic size reached, with larger epidemics originating in Scotland and the north of England than elsewhere.
PMCID: PMC1635508  PMID: 17015320
modelling; epidemiology; foot-and-mouth disease
22.  Demographic structure and pathogen dynamics on the network of livestock movements in Great Britain 
Using a novel interpretation of dynamic networks, we analyse the network of livestock movements in Great Britain in order to determine the risk of a large epidemic of foot-and-mouth disease (FMD). This network is exceptionally well characterized, as there are legal requirements that the date, source, destination and number of animals be recorded and held on central databases. We identify a percolation threshold in the structure of the livestock network, indicating that, while there is little possibility of a national epidemic of FMD in winter when the catastrophic 2001 epidemic began, there remains a risk in late summer or early autumn. These predictions are corroborated by a non-parametric simulation in which the movements of livestock in 2003 and 2004 are replayed as they occurred. Despite the risk, we show that the network displays small-world properties which can be exploited to target surveillance and control and drastically reduce this risk.
PMCID: PMC1635475  PMID: 16846906
foot-and-mouth disease; percolation; ergodicity; disease; control
23.  Validation of a Green Fluorescent Protein-Labeled Strain of Vibrio vulnificus for Use in the Evaluation of Postharvest Strategies for Handling of Raw Oysters▿†  
Applied and Environmental Microbiology  2006;72(11):7205-7211.
In this paper we describe a biological indicator which can be used to study the behavior of Vibrio vulnificus, an important molluscan shellfish-associated human pathogen. A V. vulnificus ATCC 27562 derivative that expresses green fluorescent protein (GFP) and kanamycin resistance was constructed using conjugation. Strain validation was performed by comparing the GFP-expressing strain (Vv-GFP) and the wild-type strain (Vv-WT) with respect to growth characteristics, heat tolerance (45°C), freeze-thaw tolerance (−20o and −80°C), acid tolerance (pH 5.0, 4.0, and 3.5), cold storage tolerance (5°C), cold adaptation (15°C), and response to starvation. Levels of recovery were evaluated using nonselective medium (tryptic soy agar containing 2% NaCl) with and without sodium pyruvate. The indicator strain was subsequently used to evaluate the survival of V. vulnificus in oysters exposed to organic acids (citric and acetic acids) and various cooling regimens. In most cases, Vv-GFP was comparable to Vv-WT with respect to growth and survival upon exposure to various biological stressors; when differences between the GFP-expressing and parent strains occurred, they usually disappeared when sodium pyruvate was added to media. When V. vulnificus was inoculated into shellstock oysters, the counts dropped 2 log10 after 11 to 12 days of refrigerated storage, regardless of the way in which the oysters were initially cooled. Steeper population declines after 12 days of refrigerated storage were observed for both iced and refrigerated products than for slowly cooled product and product held under conservative harvest conditions. By the end of the refrigeration storage study (22 days), the counts of Vv-GFP in iced and refrigerated oysters had reached the limit of detection (102 CFU/oyster), but slowly cooled oysters and oysters stored under conservative harvest conditions still contained approximately 103 and >104 CFU V. vulnificus/oyster by day 22, respectively. The Vv-GFP levels in the oyster meat remained stable for up to 24 h when the meat was exposed to acidic conditions at various pH values. Ease of detection and comparability to the wild-type parent make Vv-GFP a good candidate for use in studying the behavior of V. vulnificus upon exposure to sublethal stressors that might be encountered during postharvest handling of molluscan shellfish.
PMCID: PMC1636163  PMID: 16980431
24.  Pten (phosphatase and tensin homologue gene) haploinsufficiency promotes insulin hypersensitivity 
Diabetologia  2006;50(2):395-403.
Insulin controls glucose metabolism via multiple signalling pathways, including the phosphatidylinositol 3-kinase (PI3K) pathway in muscle and adipose tissue. The protein/lipid phosphatase Pten (phosphatase and tensin homologue deleted on chromosome 10) attenuates PI3K signalling by dephosphorylating the phosphatidylinositol 3,4,5-trisphosphate generated by PI3K. The current study was aimed at investigating the effect of haploinsufficiency for Pten on insulin-stimulated glucose uptake.
Materials and methods
Insulin sensitivity in Pten heterozygous (Pten+/−) mice was investigated in i.p. insulin challenge and glucose tolerance tests. Glucose uptake was monitored in vitro in primary cultures of myocytes from Pten+/− mice, and in vivo by positron emission tomography. The phosphorylation status of protein kinase B (PKB/Akt), a downstream signalling protein in the PI3K pathway, and glycogen synthase kinase 3β (GSK3β), a substrate of PKB/Akt, was determined by western immunoblotting.
Following i.p. insulin challenge, blood glucose levels in Pten+/− mice remained depressed for up to 120 min, whereas glucose levels in wild-type mice began to recover after approximately 30 min. After glucose challenge, blood glucose returned to normal about twice as rapidly in Pten+/− mice. Enhanced glucose uptake was observed both in Pten+/− myocytes and in skeletal muscle of Pten+/− mice by PET. PKB and GSK3β phosphorylation was enhanced and prolonged in Pten+/− myocytes.
Pten is a key negative regulator of insulin-stimulated glucose uptake in vitro and in vivo. The partial reduction of Pten due to Pten haploinsufficiency is enough to elicit enhanced insulin sensitivity and glucose tolerance in Pten+/− mice.
PMCID: PMC1781097  PMID: 17195063
Glucose uptake; Insulin hypersensitivity; Insulin sensitivity; Pten haploinsufficiency

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