Network topology of stable isotope interactions in a sub-arctic raptor guild

Predation is an ecologically important process, and intra-guild interactions may substantially influence the ecological effects of predator species. Despite a rapid expansion in the use of mathematical graph theory to describe trophic relations, network approaches have rarely been used to study interactions within predator assemblages. Assemblages of diurnal raptors are subject to substantial intra- and interspecific competition. Here we used the novel approach of applying analyzes based on network topology to species-specific data on the stable isotopes (13)C and (15)N in feathers to evaluate patterns of relative resource utilization within a guild of diurnal raptors in northern Sweden. Our guild consisted of the golden eagle (Aquila chrysaetos), the gyrfalcon (Falco rusticolus), the peregrine falcon (Falco peregrinus) and the rough-legged buzzard (Buteo lagopus). We found a modular trophic interaction structure within the guild, but the interactions were less nested than expected by chance. These results suggest low redundancy and hence a strong ecological importance of individual species. Our data also suggested that species were less connected through intra-guild interactions than expected by chance. We interpret our results as a convergence on specific isotope niches, and that body size and different hunting behaviour may mediate competition within these niches. We finally highlight that generalist predators could be ecologically important by linking specialist predator species with disparate dietary niches.

Increased serum levels of lipopolysaccharide and antiflagellin antibodies in patients with diarrhea-predominant irritable bowel syndrome

BACKGROUND

Innate immune responses to conserved microbial products such as lipopolysaccharide (LPS) and flagellin are likely important in microbial-host interactions and intestinal homeostasis. We hypothesized that bacterial translocation and activation of mucosal immunity against common microbial antigens might be involved in the development of irritable bowel syndrome (IBS). We therefore compared serum levels of LPS, soluble CD14 (sCD14), and flagellin antibodies between patients with different subtypes of IBS and healthy controls.

METHODS

We analyzed serum obtained from 88 patients (74 females) aged 19(43)-73 years and 106 healthy volunteers (77 females) aged 19(38)-62 years. Diarrhea-predominant IBS (D-IBS) was present in 32 patients (36%), 23 patients (26%) had constipation-predominant IBS (C-IBS), and 33 patients (38%) had A-IBS. We used ELISA for sCD14 and antiflagellin immunoglobulin G and limulus amebocyte assay for LPS. Abdominal symptoms and psychiatric comorbidities were assessed using validated questionnaires.

KEY RESULTS

We found a significantly higher serum level of LPS in patients with D-IBS compared to controls (p = 0.0155). The level of antibodies to flagellin was higher in patients with IBS than in controls (mainly driven by higher levels in D-IBS, p = 0.0018). The levels of sCD14 were lower in D-IBS patients compared to controls (p = 0.0498). We found a weak, but significant correlation between the levels of antiflagellin antibodies and anxiety among IBS patients (ρ = 0.38; p = 0.0045).

CONCLUSIONS & INFERENCES

Our results support the concept that immune reactivity to luminal antigens may have a role in the development of D-IBS. The serum level of antiflagellin antibodies was found to correlate with patients' self-reported anxiety score.

Bestrophin-3 is differently expressed in normal and injured mouse glomerular podocytes

AIM

Bestrophins are putative calcium-activated chloride channels. Recently, cell-protective functions for Bestrophin-3 (Best3) were proposed. Best3 exists in different splice variants. We have here examined expression, alternative splicing and localization of Best3 in mouse podocytes under normal conditions and during endoplasmic reticulum (ER) stress.

METHODS

Best3 expression was determined on the mRNA level using quantitative PCR and on the protein level by immunohistochemistry and Western blotting.

RESULTS

Staining for Best3 was pronounced in glomeruli and was detected in cultured mouse podocytes. Best3 did not co-localize with markers for endothelial cells (CD31), podocyte foot processes (synaptopodin) or microtubules (actin). However, immunogold-based electron microscopy and co-localization with nestin showed Best3 presence in podocyte primary processes and cell bodies. Only two splice variants of Best3 mRNA (both lacking exons 2 and 3, and one also lacking exon 6), but no full-length variant, were detected. ER stress induced by lipopolysaccharides in vivo transiently elevated mRNA levels of total Best3 and its two splice variants with different time courses. In cultured podocytes under ER stress induced by thapsigargin, the expression of total Best3, its splice variants and nestin transiently increased with similar time courses. The ER stress marker C/EBP homologous protein (CHOP) and nestin mRNA increased during ER stress in vivo and in vitro.

CONCLUSIONS

Best3 is localized intracellularly in cell bodies and primary processes of mouse podocytes and is co-localized with nestin. Two splice variants of Best3 are expressed in glomeruli and in cultured podocytes, and their expression is differentially regulated in ER stress.

Electrolyte ion adsorption and charge blocking effect at the hematite/aqueous solution interface: an electrochemical impedance study using multivariate data analysis

A model-free multivariate analysis using singular value decomposition is employed to refine an equivalent electrical circuit model in order to probe the electrochemical properties of the hematite/water interface in dilute NaCl and NH4Cl solutions using electrochemical impedance spectroscopy. The result shows that the surface protonation is directly related to the mobility and trapping of charge carriers at the mineral surface. Moreover, the point of zero charge can be found at pH where the charge transfer resistance is the highest, in addition to the minimum double layer capacitance. The inner-sphere interaction of the NH4(+) ion with the surface is indicated by an increase of capacitance for charge carrier trapping from the protonated surface as well as lower double layer capacitance and open circuit potential. It is clear that the intrinsic electrochemical activity of hematite depends on the degree of surface (de)protonation and other inner-sphere adsorption, as these processes affect the charge carrier density in the surface state. This work also highlights an important synergistic effect of the two spectral analyses that enables EIS to be utilized in an in-depth investigation of mineral/water interfaces.

Evolution of fibrosis during HCV recurrence after liver transplantation--influence of IL-28B SNP and response to peg-IFN and ribavirin treatment

The IL-28 gene is associated with sustained viral response (SVR) after treatment with peg-IFN and ribavirin in liver transplant recipients with chronic hepatitis C genotype 1 infection. We analysed the importance of recipient and donor IL-28B genotype for response to treatment and fibrosis progression in 54 liver transplant recipients. Fibrosis stage (F) was defined as mild when F≤2 and severe when F≥3 in a liver biopsy or according to liver elasticity analysis. We found a significantly lower prevalence of IL-28B SNP CC in the recipients (22%) than in the donors (67%), P<0.0001. SVR was seen in 61% of the recipients with mild and 27% with severe fibrosis pretreatment, P=0.01. Recipients with IL-28 CC and non-CC had mild fibrosis in 64% and 38% prior to treatment, P=0.13. At follow-up, after treatment, significantly more recipients with CC had mild fibrosis than non-CC recipients (75% versus 32%, P=0.0072), and all with CC and SVR had mild fibrosis. The strongest baseline factor predicting SVR was genotype. Hence, 13/19 (68%) genotype non-1 patients reached SVR versus only 9/35 (26%) genotype 1 patients, P=0.0022. In summary, we found that liver transplant recipients with IL-28B CC tended to have less advanced fibrosis prior to and significantly less after SOC treatment and that all recipients with IL-28B CC who achieved SVR had mild fibrosis at follow-up. A significantly higher SVR rate was achieved in recipients with mild than severe fibrosis pretreatment and with genotype non-1 than 1 infection. Our findings indicate that treatment for post-transplant HCV recurrence should be offered before advanced fibrosis is seen in the recipient.

Indoleamine 2,3-dioxygenase expression and functional activity in dendritic cells exposed to cholera toxin

Indoleamine 2,3-dioxygenase (IDO), a tryptophan-metabolizing enzyme expressed by dendritic cells (DC), has the potential to inhibit T cell responses and to promote tolerance. In contrast, cholera toxin (CT), the enterotoxin produced by Vibrio cholerae, promotes T cell responses, partly through its ability to induce DC maturation and promote antigen presentation. We hypothesized that the adjuvant activity of CT is associated with a lack of induction of IDO in DC. To test this hypothesis, monocyte-derived DC were pulsed with CT, and the IDO mRNA expression, IDO functional activity and cytokine production were measured as well as the ability of DC to induce T cell responses in vitro. Cholera toxin exposure induced enhanced levels of IDO mRNA in DC but no functional IDO protein activity. Cholera toxin pulsing however primed DC for CD40L-induced IDO protein activity. CD40L stimulation of CT-pulsed DC induced a modest IL-12p40 production, but not IL-12p70 or IL-23 secretion. Furthermore, CT-pulsed DC induced strong allogeneic and autologous T cell responses in vitro, which were not affected by the IDO-specific inhibitor 1-methyl tryptophan. Our results show that CT per se does not induce the expression of functional IDO protein, although it primes DC for CD40L-mediated IDO production and IL-12p40 secretion. Furthermore, CT-treated DC were equally powerful in their T cell stimulatory capacity as cytokine-matured DC.

Orally administered CpG oligodeoxynucleotide induces production of CXC and CC chemokines in the gastric mucosa and suppresses bacterial colonization in a mouse model of Helicobacter pylori infection

Bacterial DNA and unmethylated CpG oligodeoxynucleotides (CpG ODN) are known to be potent stimulators of the innate immune system in vitro and in vivo. We therefore investigated if oral administration of CpG ODN could enhance innate immunity in the gastric mucosa and control the extent of Helicobacter pylori infection in mice. Intragastric administration of a single dose of CpG ODN significantly increased local production of the CC chemokines macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, and RANTES and the CXC chemokine gamma interferon-inducible protein 10 in the stomach and/or the small intestine. Importantly, intragastric administration of CpG ODN to mice with an already established H. pylori infection, in the absence of any coadministered antigen, was found to reduce the bacterial load in the stomach compared to the load in H. pylori-infected control mice, while similar administration of non-CpG ODN had no effect on the bacterial load. The reduction in the bacterial numbers in the stomachs of mice treated with CpG ODN was associated with enhanced infiltration of immune cells and increased RANTES production in the gastric mucosa compared to the infiltration of immune cells and RANTES production in H. pylori-infected control animals. These findings suggest that intragastric administration of CpG ODN without antigen codelivery may represent a valuable strategy for induction of innate immunity against H. pylori infection.

Combined near-infrared spectroscopy and multifrequency bio-impedance investigation of skin alterations in diabetes patients based on multivariate analyses

A group of 34 diabetic men, with different degrees of diabetes complications, including skin changes, were studied by near-infrared (NIR) spectroscopy and total body multi-frequency bio-impedance analyses (MFBIA-body). Skin reflectance spectra were measured with a fibre-optic probe in four locations (sites): hand, arm, leg and foot. As control subjects, a group of 23 healthy males were also measured. A combined multivariate analysis of the two types of spectrum was performed. It was concluded that the NIR method has the potential to detect diabetes-related skin conditions and also that the combination of the two techniques provides a higher potential for classification and discrimination of the skin conditions, with correct classification increasing from 63% to 85%.

The direct thrombin inhibitor melagatran and its oral prodrug H 376/95: intestinal absorption properties, biochemical and pharmacodynamic effects

Suboptimal gastrointestinal absorption is a problem for many direct thrombin inhibitors. The studies presented herein describe the new oral direct thrombin inhibitor H 376/95, a prodrug with two protecting residues added to the direct thrombin inhibitor melagatran. Absorption properties in vitro: H 376/95 is uncharged at intestinal pH while melagatran is charged. H 376/95 is 170 times more lipophilic (octanol water partition coefficient) than melagatran. As a result, the permeability coefficient across cultured epithelial Caco-2 cells is 80 times higher for H 376/95 than for melagtran. Pharmacokinetic studies in healthy volunteers: H 376/95 is converted to melagatran in man. Oral bioavailability, measured as melagatran in plasma, is about 20% after oral administration of H 376/95, which is 2.7-5.5 times higher than after oral administration of melagatran. The variability in the area under the drug plasma concentration vs. time curve (AUC) is much smaller with oral H 376/95 (coefficient of variation 20%) than with oral melagatran (coefficient of variation 38%). Pharmacodynamic properties: H 376/95 is inactive towards human alpha-thrombin compared with melagatran [inhibition constant (K(i)) ratio, 185 times], a potential advantage for patients with silent gastrointestinal bleeding. In an experimental thrombosis model in the rat, oral H 376/95 was more effective than the subcutaneous low molecular weight heparin dalteparin in preventing thrombosis.

CONCLUSION

By the use of the prodrug principle, H 376/95 endows the direct thrombin inhibitor melagatran with pharmacokinetic properties required for oral administration without compromising the promising pharmacodynamic properties of melagatran.

[Disaster management lessons can be learned from the Gothenburg fire]

On the night of October 29, 1998, a fire broke out in an old warehouse in Gothenburg, where nearly 400 teenagers had gathered for a disco party. More than 200 patients were brought to four different hospitals in the region. Sixty-one people died at the scene due to inhalation of toxic fumes caused by the fire. Another two died later in the hospital due to severe burns. Disaster management in Sweden is based on mobile medical teams consisting of hospital staff supporting ambulance crews in the event of major incidents. Only one team together with a GP was able to be mobilized during this incident. Thus, medical care at the scene was limited. The principle of OEload and go pi was used, placing the major burden of triage on the hospitals. The limited numbers of medical personnel and available supplies caused major stress for the physicians involved at the scene.

Comparison of different tests of fencing performance

Three different procedures to analyse fencing performances were tested. The test subjects were ten world class epée fencers from the Swedish national team. The procedures involved measurements of reaction time and response time to different stimuli. Test 1 measured the lunging performance as a response to a light. Tests 2 and 3 measured more complex fencing movements as response to a more fencing-like starting procedure. The results showed that test 3 but not tests 1 and 2 could differentiate between world class fencers and beginners (p less than 0.006). The reaction time in test 3 correlated significantly (p less than 0.01) with competition success within the group of world class fencers.

Physiological and morphological characteristics of world class fencers

Physiological and morphological characteristics of world class épée fencers were analysed. The results showed that épée fencers have a high maximal aerobic power and high maximal isometric and dynamic strength. The movement pattern of épée fencing results in an asymmetry of the body. Thus, weapon hand isometric elbow flexion and forward leg isometric and dynamic muscle strength were higher than the contralateral extremity. Finally, forward leg muscle mass--evaluated from computed tomography--was higher while the muscle fiber composition was not different from the contralateral leg.

Characteristics of alveolar cells and soluble components in bronchoalveolar lavage fluid from non-smoking aluminium potroom workers

Aluminium potroom workers have been reported to develop severe pneumoconiosis and bronchial hyperreactivity. The influence of inhalation of aluminium oxide and fluorides on the alveolar milieu was studied by bronchoalveolar lavage (BAL) in 14 male non-smoking potroom workers; 28 non-smoking healthy volunteers served as controls. The total numbers, concentrations, and proportions of various alveolar cells did not differ between the groups. The concentrations of albumin and fibronectin in BAL fluid were significantly higher (p less than 0.01 for both) in the exposed workers, reflecting an increased alveolar capillary permeability and an activation of alveolar macrophages (AMs). The concentration of angiotensin converting enzyme, another AM marker, was, however, decreased (p less than 0.01) in the workers. The concentration of hyaluronan, a fibroblast marker, did not differ between the groups. AMs from workers had a decreased capacity (p less than 0.05) to interact with yeast C3b particles but not to ingest them. The expression of HLA-DR and OKM1 on the cell surfaces of AMs were equal in the two groups. The BAL findings were not accompanied by restrictive lung disease in the workers. The fact that only a discrete alveolitis was found in the potroom workers may be due to a low grade of exposure to alumina and fluorides and to frequent use of respiratory protection equipment.

Lung function and bronchial reactivity in aluminum potroom workers

Lung function and bronchial reactivity were measured in 38 aluminum potroom workers with no airway symptoms and in 20 healthy referents (office workers). All of the participants were non-smokers. The magnitude of exposure to airborne dust (alumina) and fluorides was determined. The aluminum potroom workers had obstructive lung function impairment with a significant decrease in expiratory flow and an increase in residual volume. Diffusing capacity was found to be lower than in the referents. No bronchial hyperreactivity was found in the aluminum potroom workers. The exposure to inhaled alumina and particulate and gaseous fluorides in the plant was low, 15-20% of the Swedish exposure limits. The finding of only modest lung function alterations with no bronchial hyperreactivity in the aluminum potroom workers is not consistent with the results of other authors. This discrepancy can probably be explained by the fact that the exposure to inhaled contaminants in the investigated aluminum plant was low.

Effect of long-term anemia and retransfusion on central circulation during exercise

The purpose of this study was to evaluate the effect of long-term anemia and subsequent retransfusion of erythrocytes on various circulatory parameters. Anemia was induced in nine healthy male subjects by repeated venesections. The stored blood was retransfused after 9 wk (range 8-11 wk). Exercise tests were performed before venesection in the control state (C), in the anemic state (A), and 48 h after retransfusion (R). Hemoglobin concentration levels were 146 +/- 10 g/l in C, 110 +/- 7 g/l in A, and 145 +/- 9 g/l in R. Maximal O2 uptake was 4.55 +/- 0.6, 3.74 +/- 0.7, and 4.45 +/- 0.6 l/min in C, A, and R, respectively. A decrease in heart rate of 7 beats/min (P less than 0.01) and in cardiac output of 2 l/min (P less than 0.05) at maximal exercise occurred in the anemic state compared with control values. These decreases were not reversed but, rather, were further accentuated after retransfusion. The adaptive response to submaximal exercise (cycling at 150-175 W) in anemia was mediated to the amount of 50% by an increase in cardiac output (mainly an increase in heart rate) and 50% was due to increased O2 extraction in the peripheral tissue. In conclusion, long-term anemia was found to decrease the heart rate and cardiac output at maximal exercise. Furthermore the close correlation between hemoglobin concentration and maximal O2 uptake in humans is confirmed.

Evaluation of a modified acetylene rebreathing method for the determination of cardiac output

In order to evaluate a computerized modified acetylene rebreathing method for the determination of cardiac output, 15 healthy subjects were studied at different levels of their maximal oxygen uptake (VO2max). Submaximal exercise was performed on a cycle ergometer and maximal exercise on a treadmill. Oxygen uptake, heart rate, and cardiac output (acetylene method) were determined in all test situations. In seven subjects simultaneous determinations of cardiac output were made by a modified acetylene rebreathing method (QA) and a dye dilution method (QD). Furthermore, a new resting rebreathing technique was used. The methodological error for QA (means of double samples) was 0.37 litre min-1 (2.8%) in the same individual at 150 W. The corresponding values between individuals were 0.71 (rest), 0.41 (50 W), 0.69 (150 W), and 0.40 litre min-1 (VO2max). Thus the methodological error of the modified acetylene method was very low. There was a significant difference (P less than 0.01), however, between the acetylene method and the dye dilution method, which showed a lower value for QA at all levels. This was probably due to the long response time of the mass spectrometer combined with anatomical and physiological arteriovenous shunt effects in the lungs during exercise. When these factors were considered the correcting formula was: QAc = QA + 0.005 X Q2A. There was no significant difference between the corrected cardiac output values (QAc), and the corresponding QD values. In conclusion, this modified acetylene rebreathing method is a very useful non-invasive method for measuring cardiac output at rest as well as during heavy exercise.