Endoscopic biopsies in Ussing chambers evaluated for studies of macromolecular permeability in the human colon

OBJECTIVE: Studies of mucosal permeability to protein antigens in humans are limited to in vitro techniques. The use of surgical specimens for such studies has major shortcomings. Endoscopic biopsies in Ussing chambers have been introduced as a means of studying secretion and transepithelial permeability, but have not been evaluated for studies of protein antigen uptake in human intestine. MATERIAL AND METHODS: Standard forceps biopsies from the sigmoid colon of 24 healthy volunteers were mounted in Ussing chambers with an exposed tissue area of 1.76 mm2. 51Cr-EDTA (paracellular probe) and horseradish peroxidase (HRP; 45 kDa protein antigen) were used as permeability markers. Mucosal permeability, electrophysiology, histology and energy contents of the biopsies were studied over time. To evaluate the ability of the technique to detect permeability changes, the mucosa was modulated with capric acid, a medium-chain fatty acid, known to affect tight junctions. RESULTS: In the Ussing chamber the mucosal biopsies were viable for 160 min with stable levels of ATP and lactate, and only minor changes in morphology. Steady-state permeability with low variability was seen for both markers during the 30-90 min period. Exposure to capric acid induced a rapid decrease in short-circuit current (Isc) and a slower reversible decrease in transepithelial resistance (TER), as well as an increased permeability to 51Cr-EDTA and HRP. CONCLUSIONS: Endoscopic biopsies of human colon are viable in Ussing chambers and are reliable tools for studies of mucosal permeability to protein antigens. The technique offers a broad potential for studies of mucosal function in the pathophysiology of human gastrointestinal diseases.     

Overweight,obesity and the risk of LADA: results from a Swedish case–control study and the Norwegian HUNT Study

Aims/hypothesis

Excessive weight is a risk factor for type 2 diabetes, but its role in the promotion of autoimmune diabetes is not clear. We investigated the risk of latent autoimmune diabetes in adults (LADA) in relation to overweight/obesity in two large population-based studies.

Methods

Analyses were based on incident cases of LADA (n?=?425) and type 2 diabetes (n?=?1420), and 1704 randomly selected control participants from a Swedish case–control study and prospective data from the Norwegian HUNT Study including 147 people with LADA and 1,012,957 person-years of follow-up (1984–2008). We present adjusted ORs and HRs with 95% CI.

Results

In the Swedish data, obesity was associated with an increased risk of LADA (OR 2.93, 95% CI 2.17, 3.97), which was even stronger for type 2 diabetes (OR 18.88, 95% CI 14.29, 24.94). The association was stronger in LADA with low GAD antibody (GADA; <median) (OR 4.25; 95% CI 2.76, 6.52) but present also in LADA with high GADA (OR 2.14; 95% CI 1.42, 3.24). In the Swedish data, obese vs normal weight LADA patients had lower GADA levels, better beta cell function, and were more likely to have low-risk HLA-genotypes. The combination of overweight and family history of diabetes (FHD) conferred an OR of 4.57 (95% CI 3.27, 6.39) for LADA and 24.51 (95% CI 17.82, 33.71) for type 2 diabetes. Prospective data from HUNT indicated even stronger associations; HR for LADA was 6.07 (95% CI 3.76, 9.78) for obesity and 7.45 (95% CI 4.02, 13.82) for overweight and FHD.

Conclusions/interpretation

Overweight/obesity is associated with increased risk of LADA, particularly when in combination with FHD. These findings support the hypothesis that, even in the presence of autoimmunity, factors linked to insulin resistance, such as excessive weight, could promote onset of diabetes.

     

Spectral karyotyping and interphase FISH reveal abnormalities not detected by conventional G-banding. Implications for treatment stratification of childhood acute lymphoblastic leukaemia: detailed analysis of 70 cases

Seventy uniformly treated children with acute lymphoblastic leukemia were analysed for chromosomal abnormalities with conventional G-banding, spectral karyotyping (SKY) and interphase fluorescent in situ hybridisation (FISH) using probes to detect MLL, BCR/ABL, TEL/AML1 rearrangements and INK4 locus deletions. Numerical and/or structural changes could be identified in 80% of the patients by the use of molecular cytogenetic techniques, whereas abnormalities could be detected in 60% of the patients using G-banding alone. Altogether, 106 structural aberrations were defined by FISH compared to 34 using G-banding. Seventy-four percent of the patients had numerical aberrations, 54% structural aberrations and 20% had no identified aberrations. Twelve cases had prognostically unfavourable chromosomal aberrations that had not been detected in the G-banded analysis. We identified three novel TEL partner breakpoints on 1q41, 8q24 and 21p12, and a recurrent translocation t(1;12)(p32;p13) was found. In addition, two cases displayed amplification (7-15 copies) of AML1. Our results demonstrate the usefulness of SKY and interphase FISH for the identification of novel chromosome aberrations and cytogenetic abnormalities that provide prognostically important information in childhood ALL.     

Heparan sulfate on endothelial cells mediates the binding of Plasmodium falciparum-infected erythrocytes via the DBL1alpha domain of PfEMP1

Plasmodium falciparum may cause severe forms of malaria when excessive sequestration of infected and uninfected erythrocytes occurs in vital organs. The capacity of wild-type isolates of P falciparum-infected erythrocytes (parasitized red blood cells [pRBCs]) to bind glycosaminoglycans (GAGs) such as heparin has been identified as a marker for severe disease. Here we report that pRBCs of the parasite FCR3S1.2 and wild-type clinical isolates from Uganda adhere to heparan sulfate (HS) on endothelial cells. Binding to human umbilical vein endothelial cells (HUVECs) and to human lung endothelial cells (HLECs) was found to be inhibited by HS/heparin or enzymes that remove HS from cell surfaces. (35)S-labeled HS extracted from HUVECs bound directly to the pRBCs' membrane. Using recombinant proteins corresponding to the different domains of P falciparum erythrocyte membrane protein 1 (PfEMP1), we identified Duffy-binding-like domain-1alpha (DBL1alpha) as the ligand for HS. DBL1alpha bound in an HS-dependent way to endothelial cells and blocked the adherence of pRBCs in a dose-dependent manner. (35)S-labeled HS bound to DBL1alpha-columns and eluted as a distinct peak at 0.4 mM NaCl. (35)S-labeled chondroitin sulfate (CS) of HUVECs did not bind to PfEMP1 or to the pRBCs' membrane. Adhesion of pRBCs of FCR3S1.2 to platelet endothelial cell adhesion molecule-1 (PECAM-1)/CD31, mediated by the cysteine-rich interdomain region 1alpha (CIDR1alpha), was found be operative with, but independent of, the binding to HS. HS and the previously identified HS-like GAG on uninfected erythrocytes may act as coreceptors in endothelial and erythrocyte binding of rosetting parasites, causing excessive sequestration of both pRBCs and RBCs.     

Estimation of drug receptor occupancy when non-displaceable binding differs between brain regions – extending the simplified reference tissue model

AimThe simplified reference tissue model (SRTM) is used for estimation of receptor occupancy assuming that the non-displaceable binding in the reference region is identical to the brain regions of interest. The aim of this work was to extend the SRTM to also account for inter-regional differences in non-displaceable concentrations, and to investigate if this model allowed estimation of receptor occupancy using white matter as reference. It was also investigated if an apparent higher affinity in caudate compared with other brain regions, could be better explained by a difference in the extent of non-displaceable binding.MethodsThe analysis was based on a PET study in six healthy volunteers using the 5-HT_1B receptor radioligand [¹¹C]-AZ10419369. The radioligand was given intravenously as a tracer dose alone and following different oral doses of the 5-HT_1B receptor antagonist AZD3783. Non-linear mixed effects models were developed where differences between regions in non-specific concentrations were accounted for. The properties of the models were also evaluated by means of simulation studies.ResultsThe estimate (95% CI) of Ki_PL was 10.2 ng ml⁻¹ (5.4, 15) and 10.4 ng ml⁻¹ (8.1, 13.6) based on the extended SRTM with white matter as reference and based on the SRTM using cerebellum as reference, respectively. The estimate (95% CI) of Ki_PL for caudate relative to other brain regions was 55% (48, 62%).ConclusionsThe extended SRTM allows consideration of white matter as reference region when no suitable grey matter region exists. AZD3783 affinity appears to be higher in the caudate compared with other brain regions.     

Enduring inequality: educational disparities in health among the oldest old in Sweden 1992–2011

Objectives

Although the past two decades have involved changes in the living conditions of the oldest old in Sweden, little is known about how health inequalities have developed in this group during the period. This study explores the educational disparities in a wide range of health outcomes among the oldest old in Sweden between 1992 and 2011.

Methods

The study uses the repeated cross-sectional design of the SWEOLD survey, a nationally representative survey of the oldest old in Sweden with comparable data from 1992, 2002, and 2011. The development of educational disparities in health was tracked across the three waves.

Results

The results show that although the prevalence of most health problems increased during the period, the prevalence of disability in activities of daily living decreased. Despite these changes, educational disparities in health remained largely unaffected.

Conclusions

The results of the study suggest that the association between education and health is remarkably robust. It prevailed into the oldest age groups, was consistently found for a wide range of health problems, and tended to be stable over extended periods of time.