Superior beta cell proliferation, function and gene expression in a subpopulation of rat islets identified by high blood perfusion

AIMS/HYPOTHESIS

The blood perfusion of individual pancreatic islets is highly variable, with a subgroup of islets having high perfusion and blood vessels responsive to further blood flow increase induced by glucose. This study tested the hypothesis that there is heterogeneity between islets with regard to beta cell proliferation, function and gene expression based on differences in their blood perfusion.

METHODS

Fluorescent microspheres were injected into the ascending aorta, and then microsphere-containing and non-microsphere-containing pancreatic islets were isolated for investigation. By this procedure, the 5% of islets with the greatest blood perfusion were identified for study. Islet endothelial cells were isolated separately to investigate the role of improved vascular support in the observed differences.

RESULTS

The vascular network was found to be more dense and tortuous in microsphere-containing than other islets. The most highly blood-perfused islets also had a higher rate of beta cell proliferation, superior beta cell function and a markedly different gene expression from other islets. Cultured islets exposed to islet endothelial cell products had a similarly increased beta cell proliferation rate, yet significantly fewer changes in gene expression than observed in the most highly blood-perfused islets.

CONCLUSIONS/INTERPRETATION

A novel heterogeneity between islets was observed, with superior beta cell proliferation, function and gene expression in a subpopulation of islets identified by high blood perfusion. In contrast with a previously described population of low-oxygenated, sleeping islets, which are recruited into functionality when needed, the presently described heterogeneity is shown to remain in vitro after islet isolation.

Importance of epoch length and registration time on accelerometer measurements in younger children

AIM

The aim of this study was to investigate the effect of epoch length on accumulation of minutes of physical activity per day over a spectrum of intensities, and the effect that selection of number of hours of acceptable registration required per day had on number of days that were considered acceptable.

METHODS

Participants were 696 children (369 boys and 327 girls) aged 6.7±0.4 yrs, from a population-based cohort. Physical activity was assessed by the Actigraph accelerometer for four days.

RESULTS

Main findings were that epoch length had a profound impact on accumulation of minutes of physical activity per day for higher intensities, whereas it had no effect on mean counts per minute. The chosen number of hours for an acceptable registration per day heavily influenced the number of days that were considered acceptable.

CONCLUSION

The findings in the present investigation should be taken into consideration when planning objective measurements of daily physical activity in younger children, and highlight the need for setting international recommendations for physical activity measurements with accelerometers, if different studies are to be comparable.

Drug and treatment costs in Parkinson's disease patients in Sweden

BACKGROUND

Parkinson's disease (PD) is a chronic neurodegenerative disease expected to cause great costs. The aim of this study was to calculate drug and treatment costs in patients with PD in Sweden.

METHOD

All healthcare contacts of patients with PD in Stockholm County, Sweden, were extracted from registers together with information on reimbursements from the authorities to the caregivers. PD-related costs were calculated together with non-PD-related costs. Cost per patient was calculated and extrapolated to the whole Swedish population, taking population demographics into consideration. In addition, nationwide PD drug sales statistics were included.

RESULTS

The PD prevalence of Stockholm County was estimated to 196 per 100,000 inhabitants, resulting in an estimated total of about 22,000 patients with PD in Sweden. The cost per patient was estimated to SEK 76,000 of which drug costs accounted for SEK 15,880. The annual direct costs in patients with PD in Sweden were SEK 1.7 billion in 2009.

CONCLUSION

Our study estimates high direct costs in patients with PD in Sweden, SEK 1.7 billion, 52% for inpatient care, 27% for outpatient care and 21% for drugs. With an ageing population and the medical progress, the financial burden on society will most probably increase in the future. This study might initiate and provide information for discussions about future cost allocations and healthcare priorities.

Longitudinal assessment of femoral knee cartilage quality using contrast enhanced MRI (dGEMRIC) in patients with anterior cruciate ligament injury--comparison with asymptomatic volunteers

OBJECTIVE

In this observational longitudinal study we estimate knee joint cartilage glycosaminoglycan (GAG) content, in patients with an acute anterior cruciate ligament (ACL) injury, with or without a concomitant meniscus injury.

METHODS

29 knees (19 men/10 women) were prospectively examined by repeat delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), approximately 3 weeks and 2.3±1.3 (range 4.5) years after the injury. We estimated the GAG content (T1Gd) in the central weight-bearing parts of the medial and lateral femoral cartilage and compared results with a reference cohort (n=24) with normal knees and no history of injury examined by dGEMRIC at one occasion previously.

RESULTS

The healthy reference group had longer T1Gd values compared with the ACL-injured patients at follow-up both medially: 428±38 vs 363±61ms (P<0.0001) and laterally: 445±41 vs 396±48ms (P=0.0002). At follow-up T1Gd was lower in meniscectomized patients compared to those without a meniscectomy, both medially (-84ms, P=0.002) and laterally (-38ms, P=0.05). In the injured group, the medial femoral cartilage showed similar T1Gd at the two dGEMRIC investigations: 357±50 vs 363±61ms (P=0.57), whereas the lateral femoral cartilage T1Gd increased: 374±48 vs 396±48ms (P=0.04).

CONCLUSIONS

The general decrease in cartilage T1Gd in ACL-injured patients compared with references provide evidence for structural matrix GAG changes that seem more pronounced if a concomitant meniscal injury is present. The fact that post-traumatic OA commonly develops in ACL-injured patients, in particularly those with meniscectomy, suggests that shorter T1Gd may be an early biomarker for OA.

Maternal autoimmune thyroid disease and the fetal immune system

OBJECTIVE

Several studies indicate that in utero exposure to maternal autoimmune diseases and transplacental passage of autoantibodies affect the risk of autoimmunity in the offspring, e. g., maternally derived GAD65 autoantibody correlates with decreased risk of type 1 diabetes, whereas thyroid peroxidase autoantibody (TPOAb) positivity at birth is associated with increased incidence of autoimmune thyroid disease later in life. The aim of this study was to identify immunological changes in children born to mothers with thyroid autoimmunity that may be related to in utero exposure to autoantibodies.

DESIGN AND METHOD

Open label prospective analysis of cord blood lymphocytes and serum cytokines by Flow Cytometry in children born to mothers with autoimmune thyroiditis (AIT) (n=31) and to healthy mothers (n=76) and titers of thyroid autoantibodies were determined in cord blood and in maternal peripheral blood at delivery.

RESULTS

We found an increase (almost 30%) in the frequency of cord blood natural killer (NK) cells (p=0.0016) and a minor increase in the subset of T cells expressing NK markers (p=0.028), in children born to AIT mothers. There were no detectable differences in the phenotype or frequency of cord blood memory/activated T cells, including CD4 (+)CD25 (+) T cells, between the 2 groups. The levels of pro-inflammatory cytokines TNF-α, IL-10, IL-12p70, IFN-γ and IL-1β were significantly decreased in offspring of AIT mothers as compared to healthy controls.

CONCLUSIONS

Maternal thyroid autoimmunity and transplacental passage of autoantibodies against thyroid antigens may affect the generation or expansion of cells with NK activity and the secretion of inflammatory cytokines.

The use of bayesian inversion to resolve plasma equilibrium

Recently, bayesian probability theory has been used at a number of experiments to fold uncertainties and interdependencies in the diagnostic data and forward models, together with prior knowledge of the state of the plasma, to increase accuracy of inferred physics variables. A new probabilistic framework, MINERVA, based on bayesian graphical models, has been used at JET and W7-AS to yield predictions of internal magnetic structure. A feature of the framework is the bayesian inversion for poloidal magnetic flux without the need for an explicit equilibrium assumption. Building on this, we discuss results from a new project to develop bayesian inversion tools that aim to (1) distinguish between competing equilibrium theories, which capture different physics, using the MAST spherical tokamak, and (2) test the predictions of MHD theory, particularly mode structure, using the H-1 Heliac. Specifically, we report on correction of the motional Stark effect, pickup coils, flux-loop constrained bayesian inferred equilibrium for varying toroidal flux.

Diagnostics design for steady-state operation of the Wendelstein 7-X stellarator

The status of the diagnostic developments for the quasistationary operable stellarator Wendelstein 7-X (maximum pulse length of 30 min at 10 MW ECRH heating at 140 GHz) will be reported on. Significant emphasis is being given to the issue of ECRH stray radiation shielding of in-vessel diagnostic components, which will be critical at high density operation requiring O2 and OXB heating.

Birthweight and the risk of childhood-onset type 1 diabetes: a meta-analysis of observational studies using individual patient data

AIMS/HYPOTHESIS

We investigated whether children who are heavier at birth have an increased risk of type 1 diabetes.

METHODS

Relevant studies published before February 2009 were identified from literature searches using MEDLINE, Web of Science and EMBASE. Authors of all studies containing relevant data were contacted and asked to provide individual patient data or conduct pre-specified analyses. Risk estimates of type 1 diabetes by category of birthweight were calculated for each study, before and after adjustment for potential confounders.Meta-analysis techniques were then used to derive combined ORs and investigate heterogeneity between studies.

RESULTS

Data were available for 29 predominantly European studies (five cohort, 24 case-control studies), including 12,807 cases of type 1 diabetes. Overall, studies consistently demonstrated that children with birthweight from 3.5 to 4 kg had an increased risk of diabetes of 6% (OR 1.06 [95% CI 1.01-1.11]; p=0.02) and children with birthweight over 4 kg had an increased risk of 10% (OR 1.10 [95% CI 1.04-1.19]; p=0.003), compared with children weighing 3.0 to 3.5 kg at birth. This corresponded to a linear increase in diabetes risk of 3% per 500 g increase in birthweight (OR 1.03 [95% CI 1.00-1.06]; p=0.03). Adjustments for potential confounders such as gestational age, maternal age, birth order, Caesarean section, breastfeeding and maternal diabetes had little effect on these findings.

CONCLUSIONS/INTERPRETATION

Children who are heavier at birth have a significant and consistent, but relatively small increase in risk of type 1 diabetes.

Clinical characteristics of 18-year-old men with elevated blood pressure

Twenty "hypertensive" 18-year-old men (systolic BP greater than or equal to 146 and/or diastolic BP greater than or equal to 90 mmHg) from the screening examinations of a military draught bureau were compared with 17 normotensive (systolic BP 124-131) and 12 hypotensive (systolic BP 100-106) subjects. The hypertensive subjects were on average taller, showed more often ECG evidence of sympathoadrenomedullary overactivity, tended to excrete more adrenaline in the urine during a standardized psychological stress test, had higher serum levels of sodium and potassium and reported more frequently family prevalence of hypertension than the normotensives and hypotensives. Non-participating subjects without verified hypertension had higher mean relative weight than any of the study groups. Only one hypertensive subject showed dilated pulmonary vessels on chest X-ray and borderline evidence of mild left ventricular hypertrophy. None of the hypertensive subjects showed evidence of decreased glomerular filtration rate or endocrine disorder. The subjects in both comparison groups showed frequently ECG evidence of parasympathetic activity. The hypotensive group had a lower average relative body weight than the other groups.

Perfusion Weighted MR Imaging may Differentiate Primary CNS Lymphoma from other Homogeneously Enhancing Brain Tumors

Primary central nervous system lymphoma (PCNSL), glioblastoma multiforme (GBM) and metastases may be difficult to differentiate based on conventional imaging alone. The aim of this study was to investigate the value of perfusion weighted imaging (PWI) in differentiating homogeneously enhancing PCNSL from homogeneously enhancing GBM and metastases. Seven consecutive patients presenting with homogeneously enhancing intraaxial tumors on MRI were retrospectively analyzed. All seven patients (three immunocompetent patients with PCNSL, three with GBM, and one with cerebral metastases) were examined with identical MR-sequences including PWI. The relative regional Cerebral Blood Volume (rrCBV) and the rrCBV ratio (rrCBVratio) were calculated. In lymphomas rrCBVratio was 0.93 ± 0.42 (mean ± SD) compared with 7.93 ± 1.44 in GBM and metastases. All lymphomas had rrCBVratio < 1.43 while all GBM and metastases had rrCBVratio > 1.43 (Fischer exact test; p < 0.001). PWI may be a valuable method in differentiating homogenously enhancing PCNSL from GBM and metastases.

Forward modeling of JET polarimetry diagnostic

An analytical Bayesian inversion of the JET interferometry line integrated densities into density profiles and associated uncertainty information, is demonstrated. These are used, with a detailed model of plasma polarimetry, to predict the rotation and ellipticity for the JET polarimeter. This includes the lateral channels, for over 45,000 time points over 1313 JET pulses. Good agreement with measured values is shown for a number of channels. For the remaining channels, the requirement of a more detailed model of the diagnostic is demonstrated. A commonly used approximation for the Cotton-Mouton effect on the lateral channels is also evaluated.

A carbon nanotube gated carbon nanotube transistor with 5 ps gate delay

Semiconducting carbon nanotubes (CNTs) are attractive as channel material for field-effect transistors due to their high carrier mobility. In this paper we show that a local CNT gate can provide a significant improvement in the subthreshold slope of a CNT transistor compared to back gate switching and provide gate delays as low as 5 ps. The CNT gated CNT transistor devices are fabricated using a two-step chemical vapour deposition technique. The measured transfer characteristics are in very good agreement with theoretical modelling results that provide confirmation of the operating principle of the transistors. Gate delays below 2 ps should be readily achievable by reducing the thickness of the gate dielectric.

Caesarean section is associated with an increased risk of childhood-onset type 1 diabetes mellitus: a meta-analysis of observational studies

AIMS/HYPOTHESIS

The aim of this study was to investigate the evidence of an increased risk of childhood-onset type 1 diabetes in children born by Caesarean section by systematically reviewing the published literature and performing a meta-analysis with adjustment for recognised confounders.

METHODS

After MEDLINE, Web of Science and EMBASE searches, crude ORs and 95% CIs for type 1 diabetes in children born by Caesarean section were calculated from the data reported in each study. Authors were contacted to facilitate adjustments for potential confounders, either by supplying raw data or calculating adjusted estimates. Meta-analysis techniques were then used to derive combined ORs and to investigate heterogeneity between studies.

RESULTS

Twenty studies were identified. Overall, there was a significant increase in the risk of type 1 diabetes in children born by Caesarean section (OR 1.23, 95% CI 1.15-1.32, p < 0.001). There was little evidence of heterogeneity between studies (p = 0.54). Seventeen authors provided raw data or adjusted estimates to facilitate adjustments for potential confounders. In these studies, there was evidence of an increase in diabetes risk with greater birthweight, shorter gestation and greater maternal age. The increased risk of type 1 diabetes after Caesarean section was little altered after adjustment for gestational age, birth weight, maternal age, birth order, breast-feeding and maternal diabetes (adjusted OR 1.19, 95% CI 1.04-1.36, p = 0.01).

CONCLUSIONS/INTERPRETATION

This analysis demonstrates a 20% increase in the risk of childhood-onset type 1 diabetes after Caesarean section delivery that cannot be explained by known confounders.

Investigation of spatial resolution, partial volume effects and smoothing in functional MRI using artificial 3D time series

This work addresses the balance between temporal signal-to-noise ratio (tSNR) and partial volume effects (PVE) in functional magnetic resonance imaging (fMRI) and investigates the impact of the choice of spatial resolution and smoothing. In fMRI, since physiological time courses are monitored, tSNR is of greater importance than image SNR. Improving SNR by an increase in voxel volume may be of negligible benefit when physiological fluctuations dominate the noise. Furthermore, at large voxel volumes, PVE are more pronounced, leading to an overall loss in performance. Artificial fMRI time series, based on high-resolution anatomical data, were used to simulate BOLD activation in a controlled manner. The performance was subsequently quantified as a measure of how well the resulted activation matched the simulated activation. The performance was highly dependent on the spatial resolution. At high contrast-to-noise ratio (CNR), the optimal voxel volume was small, i.e. in the region of 2(3) mm(3). It was also shown that using a substantially larger voxel volume in this case could potentially negate the CNR benefits. The optimal smoothing kernel width was dependent on the CNR, being larger at poor CNR. At CNR >1, little or no smoothing proved advantageous. The use of artificial time series gave an opportunity to quantitatively investigate the effects of partial volume and smoothing in single subject fMRI. It was shown that a proper choice of spatial resolution and smoothing kernel width is important for fMRI performance.