Long-Term Dynamics in a Metapopulation of the American Pika

A 20-yr study of a metapopulation of the American pika revealed a regional decline in occupancy in one part of a large network of habitat patches. We analyze the possible causes of this decline using a spatially realistic metapopulation model, the incidence function model. The pika metapopulation is the best-known mammalian example of a classical metapopulation with significant population turnover, and it satisfies closely the assumptions of the incidence function model, which was parameterized with data on patch occupancy. The model-predicted incidences of patch occupancy are consistent with observed incidences, and the model predicts well the observed turnover rate between four metapopulation censuses. According to model predictions, the part of the metapopulation where the decline has been observed is relatively unstable and prone to large oscillations in patch occupancy, whereas the other part of the metapopulation is predicted to be persistent. These results demonstrate how extinction-colonization dynamics may produce spatially correlated patterns of patch occupancy without any spatially correlated processes in local dynamics or extinction rate. The unstable part of the metapopulation gives an empirical example of multiple quasi equilibria in metapopulation dynamics. Phenomena similar to those observed here may cause fluctuations in species' range limits

Minimum viable metapopulation size.

We define the minimum viable metapopulation (MVM) size as the minimum number of interacting local populations necessary for long-term persistence of a metapopulation in a balance between local extinctions and recolonizations. The minimum amount of suitable habitat (MASH) is defined as the minimum density (or number) of suitable habitat patches necessary for metapopulation persistence. Levins's metapopulation model suggests that MASH can be estimated by the fraction of empty patches in a network in which the metapopulation occurs at a stochastic steady state. We discuss three reasons why this rule of thumb is likely to give an underestimate, and possibly a severe underestimate, of MASH: the rescue effect, colonization-extinction stochasticity, and nonequilibrium (transient) metapopulation dynamics. The assumption that metapopulations occur at a steady state, common to many models, may be frequently violated because of the high rate of habitat loss and fragmentation in many landscapes. Scores of rare and endangered species may already be ''living dead,'' committed to extinction because extinction is the equilibrium toward which their metapopulations are moving in the present fragmented landscapes. To conserve these species we should reverse the process of habitat loss and fragmentation

The genetic variant rs4073 A→T of the Interleukin-8 promoter region is associated with the earlier onset of exudative age-related macular degeneration

Peer reviewe

TRPA1 Mediates Contact Hypersensitivity Induced by 2,4-Dinitrochlorobenzene

publishedVersionNon peer reviewe

Urine sodium excretion is related to extracellular water volume but not to blood pressure in 510 normotensive and never-treated hypertensive subjects

PURPOSE: High sodium intake is an accepted risk factor for hypertension, while low Na+ intake has also been associated with increased risk of cardiovascular events. In this cross-sectional study, we examined the association of 24-h urinary Na+ excretion with haemodynamics and volume status. MATERIALS AND METHODS: Haemodynamics were recorded in 510 normotensive and never-treated hypertensive subjects using whole-body impedance cardiography and tonometric radial artery pulse wave analysis. The results were examined in sex-specific tertiles of 24-h Na+ excretion, and comparisons between normotensive and hypertensive participants were also performed. Regression analysis was used to investigate factors associated with volume status. The findings were additionally compared to 28 patients with primary aldosteronism. RESULTS: The mean values of 24-h urinary Na+ excretion in tertiles of the 510 participants were 94, 148 and 218 mmol, respectively. Average tertile age (43.4-44.7 years), office blood pressure and pulse wave velocity were corresponding in the tertiles. Plasma electrolytes, lipids, vitamin D metabolites, parathyroid hormone, renin activity, aldosterone, creatinine and insulin sensitivity did not differ in the tertiles. In supine laboratory recordings, there were no differences in aortic systolic and diastolic blood pressure, heart rate, cardiac output and systemic vascular resistance. Extracellular water volume was higher in the highest versus lowest tertile of Na+ excretion. In regression analysis, body surface area and 24-h Na+ excretion were independent explanatory variables for extracellular water volume. No differences in urine Na+ excretion and extracellular water volume were found between normotensive and hypertensive participants. When compared with the 510 participants, patients with primary aldosteronism had 6.0% excess in extracellular water (p = .003), and 24-h Na+ excretion was not related with extracellular water volume. CONCLUSION: In the absence of mineralocorticoid excess, Na+ intake, as evaluated from 24-h Na+ excretion, predominantly influences extracellular water volume without a clear effect on blood pressure.publishedVersionPeer reviewe

NHLRC2 variants identified in patients with fibrosis, neurodegeneration, and cerebral angiomatosis (FINCA) : characterisation of a novel cerebropulmonary disease

A novel multi-organ disease that is fatal in early childhood was identified in three patients from two non-consanguineous families. These children were born asymptomatic but at the age of 2 months they manifested progressive multi-organ symptoms resembling no previously known disease. The main clinical features included progressive cerebropulmonary symptoms, malabsorption, progressive growth failure, recurrent infections, chronic haemolytic anaemia and transient liver dysfunction. In the affected children, neuropathology revealed increased angiomatosis-like leptomeningeal, cortical and superficial white matter vascularisation and congestion, vacuolar degeneration and myelin loss in white matter, as well as neuronal degeneration. Interstitial fibrosis and previously undescribed granuloma-like lesions were observed in the lungs. Hepatomegaly, steatosis and collagen accumulation were detected in the liver. A whole-exome sequencing of the two unrelated families with the affected children revealed the transmission of two heterozygous variants in the NHL repeat-containing protein 2 (NHLRC2); an amino acid substitution p.Asp148Tyr and a frameshift 2-bp deletion p.Arg201GlyfsTer6. NHLRC2 is highly conserved and expressed in multiple organs and its function is unknown. It contains a thioredoxin-like domain; however, an insulin turbidity assay on human recombinant NHLRC2 showed no thioredoxin activity. In patient-derived fibroblasts, NHLRC2 levels were low, and only p.Asp148Tyr was expressed. Therefore, the allele with the frameshift deletion is likely non-functional. Development of the Nhlrc2 null mouse strain stalled before the morula stage. Morpholino knockdown of nhlrc2 in zebrafish embryos affected the integrity of cells in the midbrain region. This is the first description of a fatal, early-onset disease; we have named it FINCA disease based on the combination of pathological features that include fibrosis, neurodegeneration, and cerebral angiomatosis.Peer reviewe

The characteristics of elevated blood pressure in abdominal obesity correspond to primary hypertension : a cross-sectional study

Background: Obesity-related hypertension and the associated metabolic abnormalities are considered as a distinct hypertensive phenotype. Here we examined how abdominal fat content, as judged by waist:height ratio, influenced blood pressure and hemodynamic profile in normotensive subjects and never-treated hypertensive patients. Methods: The 541 participants (20–72 years) underwent physical examination and laboratory analyses and were divided into age and sex-adjusted quartiles of waist:height ratio. Supine hemodynamics were recorded using whole-body impedance cardiography, combined with analyses of radial tonometric pulse wave form and heart rate variability. Results: Mean waist:height ratios in the quartiles were 0.46, 0.51, 0.55 and 0.62. Radial and aortic blood pressure, systemic vascular resistance, pulse wave velocity, markers of glucose and lipid metabolism, leptin levels and C-reactive protein were higher in quartile 4 when compared with quartiles 1 and 2 (p < 0.05 for all). Cardiac index was lower in quartile 4 versus quartile 1, while no differences were seen in heart rate variability, augmentation index, plasma renin activity, and aldosterone concentration between the quartiles. Linear regression analyses showed independent associations of abdominal obesity with higher aortic systolic and diastolic blood pressure, systemic vascular resistance, and pulse wave velocity (p < 0.05 for waist:height ratio in all regression models). Conclusion: Higher waist:height ratio was associated with elevated blood pressure, systemic vascular resistance, and arterial stiffness, but not with alterations in cardiac sympathovagal modulation or activation of the circulating renin-angiotensin-aldosterone system. Although obesity-related elevation of blood pressure has distinct phenotypic features, these results suggest that its main characteristics correspond those of primary hypertension. Trial registration: ClinicalTrails.gov NCT01742702 (date of registration 5th December 2012).publishedVersionPeer reviewe

Ustekinumab for Crohn's disease: a nationwide real-life cohort study from Finland (FINUSTE)

Background: Ustekinumab (UST), a human anti-IL12/23p40 monoclonal antibody, has been approved for treatment of Crohn's Disease (CD) since the end of 2016. This nationwide noninterventional, retrospective chart review explored real-life data in patients receiving UST to provide guidance in UST treatment in the era of increasing prevalence of CD. Methods: The study assessed UST treatment patterns such as dosing frequency, concomitant medication and persistence in 48 CD patients commencing UST therapy in 12 Finnish hospitals during 2017. Clinical remission and response rates were explored using a modified Harvey-Bradshaw index (mHBI) and endoscopic response via the simple endoscopic score for Crohn's disease (SES-CD) as proportions of patients at week 16 and at the end of follow-up. Results: Forty patients (83%) continued UST-treatment at the end of follow-up. At week 16, clinical response and endoscopic healing was observed, where data were available; mHBI decreased from 9 to 3 (p = .0001) and SES-CD from 12 to 3 (p = .009). Clinical benefit was achieved by 83% (19/23) at week 16 and by 76% (16/21) at the end of follow-up. The proportion of patients using corticosteroids decreased from 48% to 25% at week 16 and to 13% at the end of the follow-up. Conclusion: UST showed to be effective and persistent, inducing short-term clinical benefit and endoscopic response in this real-life nationwide study of CD patients. Significant corticosteroid tapering in patients with highly treatment refractory and long-standing CD was observed

Ustekinumab for Crohn’s disease: a nationwide real-life cohort study from Finland (FINUSTE)

Background: Ustekinumab (UST), a human anti-IL12/23p40 monoclonal antibody, has been approved for treatment of Crohn?s Disease (CD) since the end of 2016. This nationwide noninterventional, retrospective chart review explored real-life data in patients receiving UST to provide guidance in UST treatment in the era of increasing prevalence of CD.Methods: The study assessed UST treatment patterns such as dosing frequency, concomitant medication and persistence in 48?CD patients commencing UST therapy in 12 Finnish hospitals during 2017. Clinical remission and response rates were explored using a modified Harvey?Bradshaw index (mHBI) and endoscopic response via the simple endoscopic score for Crohn?s disease (SES-CD) as proportions of patients at week 16 and at the end of follow-up.Results: Forty patients (83%) continued UST-treatment at the end of follow-up. At week 16, clinical response and endoscopic healing was observed, where data were available; mHBI decreased from 9 to 3 (p?=?.0001) and SES-CD from 12 to 3 (p?=?.009). Clinical benefit was achieved by 83% (19/23) at week 16 and by 76% (16/21) at the end of follow-up. The proportion of patients using corticosteroids decreased from 48% to 25% at week 16 and to 13% at the end of the follow-up.Conclusion: UST showed to be effective and persistent, inducing short-term clinical benefit and endoscopic response in this real-life nationwide study of CD patients. Significant corticosteroid tapering in patients with highly treatment refractory and long-standing CD was observed.Peer reviewe