Priority effects transcend scales and disciplines in biology

Although primarily studied through the lens of community ecology, phenomena consistent with priority effects appear to be widespread across many different scenarios spanning a broad range of spatial, temporal, and biological scales. However, communication between these research fields is inconsistent and has resulted in a fragmented co-citation landscape, likely due to the diversity of terms used to refer to priority effects across these fields. We review these related terms, and the biological contexts in which they are used, to facilitate greater cross-disciplinary cohesion in research on priority effects. In breaking down these semantic barriers, we aim to provide a framework to better understand the conditions and mechanisms of priority effects, and their consequences across spatial and temporal scales.

Vitamin C as a Potential Prophylactic Measure Against Frozen Shoulder in an In Vivo Shoulder Contracture Animal Model

BACKGROUND

Frozen shoulder is a common, painful, and movement-restricting condition. Although primary frozen shoulder is idiopathic, secondary frozen shoulder can occur after trauma or surgery. Prophylactic and therapeutic options are often unsatisfactory. Vitamin C (ascorbic acid) is a potent physiological antioxidant and likely inhibits the activation of nuclear factor κB, which plays a decisive role in inflammatory reactions.

HYPOTHESIS

Because of its anti-inflammatory effects, vitamin C may be valuable in the prevention of secondary frozen shoulder.

STUDY DESIGN

Controlled laboratory study.

METHODS

An in vivo shoulder contracture model was conducted by fixation of the right proximal limb of Sprague-Dawley rats. A treatment group (n = 8) receiving vitamin C orally was compared with a control group (n = 9) without vitamin C. The primary outcome was capsular thickness at the shoulder joint measured on magnetic resonance imaging (MRI) examination. Further histological examination was performed but was not statistically analyzed because of variability of the cutting plane through the glenoid.

RESULTS

Vitamin C treatment resulted in less thickening of the axillary fold of the operated shoulder at 2 of the 3 locations measured on MRI compared with untreated controls (insertion to the glenoid, P = .074; insertion to the humerus, P = .006; middle of the axillary recess, P = .008). The observed structural changes in histological examination corroborated the significant changes obtained from the MRI measurements.

CONCLUSION

Prophylactic vitamin C seemed to reduce the thickening of the axillary recess in secondary frozen shoulder in this preclinical study.

CLINICAL RELEVANCE

Vitamin C may be helpful as a noninvasive therapeutic measure to prevent secondary frozen shoulder (eg, within the context of surgery in the shoulder region or immobilization) or to treat primary frozen shoulder at an early stage. Further studies are required to evaluate the effect of this treatment in humans and the necessary dosage in humans.

Obesity measured by outer abdominal fat may cause facet joint arthritis at the lumbar spine

BACKGROUND AND OBJECTIVES

There is a lack of studies on obesity measured by outer abdominal fat (OAF), which describes abdominal subcutaneous adipose tissue thickness with regard to spino-pelvic parameters. We investigated OAF and its physiologic values on computed tomography (CT) scans with regard to age, gender, facet joint (FJ) arthritis, FJ orientation, lumbar lordosis (LL) and pelvic incidence (PI).

MATERIAL AND METHOD

OAF, lumbar FJs, LL and PI were evaluated on CT scans.

RESULTS

CT scans of 620 individuals with a mean age of 42.5 years were reviewed. OAF showed a mean value of 19.7 millimeters (mm). It significantly increased with age until 70 years and decreased thereafter (p 0.0001). There was no significant gender difference. OAF was significantly increased with FJ arthritis (p = 0.01), but not with FJ orientation, LL or PI.

CONCLUSION

OAF on CT scans seems to have a mean value of 19.7 mm. It is higher in the older age groups until 70 years and declines again afterward. As a novelty finding, OAF significantly increases with higher degrees of FJ arthritis, but is not related to gender or other spino-pelvic parameters such as FJ orientation, LL or PI. Differences in fat distribution may be found at other anatomic sites, such as visceral fat. Obese patients may benefit from weight loss by decreasing their FJ arthritis, which may potentially decrease associated back pain, which may be worth further investigations.

The dual PPARα/γ agonist aleglitazar increases the number and function of endothelial progenitor cells: implications for vascular function and atherogenesis

BACKGROUND AND PURPOSE

Aleglitazar is a dual PPARα/γ agonist but little is known about its effects on vascular function and atherogenesis. Hence, we characterized its effects on circulating angiogenic cells (CAC), neoangiogenesis, endothelial function, arteriogenesis and atherosclerosis in mice.

EXPERIMENTAL APPROACH

C57Bl/6 wild-type (WT, normal chow), endothelial NOS (eNOS)(-/-) (normal chow) and ApoE(-/-) (Western-type diet) mice were treated with aleglitazar (10 mg·kg(-1) ·day(-1) , i.p.) or vehicle.

KEY RESULTS

Aleglitazar enhanced expression of PPARα and PPARγ target genes, normalized glucose tolerance and potently reduced hepatic fat in ApoE(-/-) mice. In WT mice, but not in eNOS(-/-) , aleglitazar up-regulated Sca-1/VEGFR2-positive CAC in the blood and bone marrow and up-regulated diLDL/lectin-positive CAC. Aleglitazar augmented CAC migration and enhanced neoangiogenesis. In ApoE(-/-) mice, aleglitazar up-regulated CAC number and function, reduced markers of vascular inflammation and potently improved perfusion restoration after hindlimb ischaemia and aortic endothelium-dependent vasodilatation. This was associated with markedly reduced formation of atherosclerotic plaques. In human cultured CAC from healthy donors and patients with coronary artery disease with or without diabetes mellitus, aleglitazar increased migration and colony-forming units in a concentration-dependent manner. Furthermore, oxidative stress-induced CAC apoptosis and expression of p53 were reduced, while telomerase activity and expression of phospho-eNOS and phospho-Akt were elevated. Comparative agonist and inhibitor experiments revealed that aleglitazar's effects on CAC migration and colony-forming units were mediated by both PPARα and PPARγ signalling and required Akt.

CONCLUSIONS AND IMPLICATIONS

Aleglitazar augments the number, function and survival of CAC, which correlates with improved vascular function, enhanced arteriogenesis and prevention of atherosclerosis in mice.