The effects of insulin resistance on individual tissues: an application of a mathematical model of metabolism in humans

Whilst the human body expends energy constantly, the human diet consists of a mix of carbohydrates and fats delivered in a discontinuous manner. To deal with this sporadic supply of energy, there are transport, storage and utilisation mechanisms, for both carbohydrates and fats, around all tissues of the body. Insulin-resistant states such as type 2 diabetes and obesity are characterised by reduced efficiency of these mechanisms. Exactly how these insulin-resistant states develop, for example whether there is an order in which tissues become insulin resistant, is an active area of research with the hope of gaining a better overall understanding of insulin resistance. In this paper we use a previously derived system of 12 first-or der coupled differential equations that describe the transport between, and storage in, different tissues of the human body. We briefly revisit the derivation of the model before parametrising the model to account for insulin resistance. We then solve the model numerically, separately simulating each individual tissue as insulin resistant, and discuss and compare these results, drawing three main conclusions. The implications of these results are in accordance with biological intuition. First, insulin resistance in a tissue creates a knock-on effect on the other tissues in the body, whereby they attempt to compensate for the reduced efficiency of the insulin resistant tissue. Secondly, insulin resistance causes a fatty liver; and the insulin resistance of tissues other than the liver can cause fat to accumulate in the liver. Finally, although insulin resistance in individual tissues can cause slightly reduced skeletal-muscle metabolic flexibility, it is when the whole body is insulin resistant that the biggest effect on skeletal muscle flexibility is see

A participatory physical and psychosocial intervention for balancing the demands and resources among industrial workers (PIPPI): study protocol of a cluster-randomized controlled trial

Background: Need for recovery and work ability are strongly associated with high employee turnover, well-being and sickness absence. However, scientific knowledge on effective interventions to improve work ability and decrease need for recovery is scarce. Thus, the present study aims to describe the background, design and protocol of a cluster randomized controlled trial evaluating the effectiveness of an intervention to reduce need for recovery and improve work ability among industrial workers. Methods/Design: A two-year cluster randomized controlled design will be utilized, in which controls will also receive the intervention in year two. More than 400 workers from three companies in Denmark will be aimed to be cluster randomized into intervention and control groups with at least 200 workers (at least 9 work teams) in each group. An organizational resources audit and subsequent action planning workshop will be carried out to map the existing resources and act upon initiatives not functioning as intended. Workshops will be conducted to train leaders and health and safety representatives in supporting and facilitating the intervention activities. Group and individual level participatory visual mapping sessions will be carried out allowing team members to discuss current physical and psychosocial work demands and resources, and develop action plans to minimize strain and if possible, optimize the resources. At all levels, the intervention will be integrated into the existing organization of work schedules. An extensive process and effect evaluation on need for recovery and work ability will be carried out via questionnaires, observations, interviews and organizational data assessed at several time points throughout the intervention period. Discussion: This study primarily aims to develop, implement and evaluate an intervention based on the abovementioned features which may improve the work environment, available resources and health of industrial workers, and hence their need for recovery and work ability

Adjuvant dendritic cell vaccination induces tumor-specific immune responses in the majority of stage III melanoma patients.

Purpose To determine the effectiveness of adjuvant dendritic cell (DC) vaccination to induce tumor-specific immunological responses in stage III melanoma patients.Experimental design Retrospective analysis of stage III melanoma patients, vaccinated with autologous monocyte-derived DC loaded with tumor-associated antigens (TAA) gp100 and tyrosinase after radical lymph node dissection. Skin-test infiltrating lymphocytes (SKILs) obtained from delayed-type hypersensitivity skin-test biopsies were analyzed for the presence of TAA-specific CD8(+) T cells by tetrameric MHC-peptide complexes and by functional TAA-specific T cell assays, defined by peptide-recognition (T2 cells) and/or tumor-recognition (BLM and/or MEL624) with specific production of Th1 cytokines and no Th2 cytokines.Results Ninety-seven patients were analyzed: 21 with stage IIIA, 34 with stage IIIB, and 42 had stage IIIC disease. Tetramer-positive CD8(+) T cells were present in 68 patients (70%), and 24 of them showed a response against all 3 epitopes tested (gp100:154-162, gp100:280-288, and tyrosinase:369-377) at any point during vaccinations. A functional T cell response was found in 62 patients (64%). Rates of peptide-recognition of gp100:154-162, gp100:280-288, and tyrosinase:369-377 were 40%, 29%, and 45%, respectively. Median recurrence-free survival and distant metastasis-free survival of the whole study population were 23.0 mo and 36.8 mo, respectively.Conclusions DC vaccination induces a functional TAA-specific T cell response in the majority of stage III melanoma patients, indicating it is more effective in stage III than in stage IV melanoma patients. Furthermore, performing multiple cycles of vaccinations enhances the chance of a broader immune response

Ischemic patterns assessed by positron emission tomography predict adverse outcome in patients with idiopathic dilated cardiomyopathy

Although patients with idiopathic dilated cardiomyopathy (DCM) have no coronary artery disease, regional impairment of myocardial perfusion combined with preserved metabolism has been found using positron emission tomography (PET). Our aim was to assess the prognostic relevance of PET-mismatch between stress myocardial perfusion and glucose uptake on clinical outcome in DCM. In 24 patients with DCM who underwent both myocardial perfusion and metabolism PET scanning, "mismatch" was assessed and the association with clinical outcome (hospitalization, mortality, and heart transplantation) was investigated. Mismatch was found in 16 patients (66.7%). Univariate analysis showed that the presence of mismatch was associated with adverse outcome (P = 0.03). After adjustment for sex and age, the association remained significant with an adjusted relative risk of 10.4 (95% CI 1.1-103; P = 0.04) for death, heart transplant, or hospitalization. Univariate analysis also showed that a higher extent of mismatch was significantly associated with adverse outcome (P = 0.02). After adjusting for sex and age, the association remained significant with an adjusted relative risk of 6.5 [95% CI 1.2-36; P = 0.03] for death, heart transplantation, or hospitalization. PET stress perfusion-metabolism mismatch, indicative for ischemia, is frequently found in DCM patients and related to a poorer outcome

Prerequisites for a dry powder inhaler for children with cystic fibrosis

Correct inhalation technique is essential for effective use of dry powder inhalers (DPIs), as their effectiveness largely depends on the patient's inhalation manoeuvre. Children are an especially challenging target population for DPI development due to the large variability in understanding and inspiratory capacities. We previously performed a study in which we determined the prerequisites for a paediatric DPI in a mostly healthy paediatric population, for which we used an empty test inhaler with variable internal airflow resistance and mouthpiece. In the current study we investigated what specifications are required for a DPI for children with cystic fibrosis (CF), for which we expanded on our previous findings. We recorded flow profiles of 35 children with CF (aged 4.7-14.7 years) at three airflow resistances (0.031-0.045 kPa0.5.min.L-1) from which various inspiratory parameters were computed. Obstructions in the mouth during inhalation were recorded with a sinuscope. All children were able to perform a correct inhalation manoeuvre, although video analysis showed that children did not place the inhaler correctly in the mouth in 17% of the cases. No effect was found of medium to high airflow resistance on total inhaled volume, which implies that the whole resistance range tested is suitable for children with CF aged 4-14 years. No effect could be established of either mouthpiece design or airflow resistance on the occurrence of obstructions in the mouth cavity. This study confirms our previous conclusion that the development of DPIs specifically for children is highly desired. Such a paediatric DPI should function well at 0.5 L inhaled volume and a peak inspiratory flow rate of 20 to 30 L/min, depending on the internal airflow resistance. This resistance can be increased up to 0.045 kPa0.5.min.L-1 (medium-high) to reduce oropharyngeal deposition. A higher resistance may be less favourable due to its compromising effect on PIF and thereby on the energy available for powder dispersion

A mathematical model of the human metabolic system and metabolic flexibility

In healthy subjects some tissues in the human body display metabolic flexibility, by this we mean the ability for the tissue to switch its fuel source between predominantly carbohydrates in the post prandial state and predominantly fats in the fasted state. Many of the pathways involved with human metabolism are controlled by insulin, and insulin- resistant states such as obesity and type-2 diabetes are characterised by a loss or impairment of metabolic flexibility. In this paper we derive a system of 12 first-order coupled differential equations that describe the transport between and storage in different tissues of the human body. We find steady state solutions to these equations and use these results to nondimensionalise the model. We then solve the model numerically to simulate a healthy balanced meal and a high fat meal and we discuss and compare these results. Our numerical results show good agreement with experimental data where we have data available to us and the results show behaviour that agrees with intuition where we currently have no data with which to compare

Expression of transforming growth factor-β (TGF-β) in chronic idiopathic cough

In patients with chronic idiopathic cough, there is a chronic inflammatory response together with evidence of airway wall remodelling and an increase in airway epithelial nerves expressing TRPV-1. We hypothesised that these changes could result from an increase in growth factors such as TGFβ and neurotrophins

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Compressed representation of a partially defined integer function over multiple arguments

In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one

Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO