Leptin reduces in vitro cementoblast mineralization and survival as well as induces PGE2 release by ERK1/2 commitment

Objectives

Juvenile obesity is a complex clinical condition that is present more and more frequently in the daily orthodontic practice. Over-weighted patients have an impaired bone metabolism, due in part to their increased levels of circulating adipokines. Particularly, leptin has been reported to play a key role in bone physiology. Leptin is ubiquitously present in the body, including blood, saliva, and crevicular fluid. If, and to what extent, it could influence the reaction of cementoblasts during orthodontic-induced forces is yet unknown.

Material and methods

OCCM-30 cementoblasts were cultivated under compressive forces using different concentrations of leptin. The expression of ObR, Runx-2, Osteocalcin, Rank-L, Sost, Caspase 3, 8, and 9 were analyzed by RT-PCR. Western blots were employed for protein analysis. The ERK1/2 antagonist FR180204 (Calbiochem) was used and cPLA2 activation, PGE2, and cytochrome C release were further evaluated.

Results

In vitro, when compressive forces are applied, leptin promotes ERK1/2 phosphorylation, as well as upregulates PGE2 and caspase 3 and caspase 9 on OCCM cells. Blockade of ERK1/2 impairs leptin-induced PGE2 secretion and reduced caspase 3 and caspase 9 expression.

Conclusions

Leptin influences the physiological effect of compressive forces on cementoblasts, exerting in vitro a pro-inflammatory and pro-apoptotic effect.

Clinical relevance

Our findings indicate that leptin exacerbates the physiological effect of compressive forces on cementoblasts promoting the release of PGE2 and increases the rate of cell apoptosis, and thus, increased levels of leptin may influence the inflammatory response during orthodontically induced tooth movement.

[Trends of in-hospital mortality and constituent ratio of patients with acute myocardial infarction]

Objective: To analyze the trends on constituent ratio of non-ST-segment-elevation (NSTEMI) and ST-segment-elevation myocardial infarction (STEMI) and related in-hospital mortality in acute myocardial infarction (AMI) patients hospitalized in Beijing Anzhen Hospital from 2004 to 2014. Methods: This is a single-center, retrospective study. We reviewed all patients hospitalized for AMI in Beijing Anzhen Hospital from January 1 2004 to December 31 2014, and collected all related information including hospitalization stay, the type of AMI, revascularization and in-hospital mortality. We analyzed the trends of constituent ratio of NSTEMI and STEMI, and their in-hospital mortalities during the 11 years. Results: Data from a total of 23 864 patients with AMI, including 5 539 STEMI and 18 325 NSTEMI, were analyzed. Compared with STEMI patients, NSTEMI patients were older, less likely to be male (P<0.001), had higher prevalence of hypertension, hyperlipidemia, diabetes (P<0.001), and lower prevalence of smoking (P<0.001). Additionally, patients with NSTEMI were more likely to have prior history of MI (12.6% (695/5 539) vs. 7.4% (1 354/18 325), P<0.001) and coronary artery bypass graft surgery (2.7% (152/5 539) vs. 0.7% (124/18 325), P<0.001). The constituent ratio of NSTEMI was significantly increased during the observation period, rising from 15.8% (107/802) in 2004 to 35.7% (1 273/3 583) in 2014 (P value for trend <0.001). The in-hospital mortality of NSTEMI patients was significantly lower compared with those with STEMI (1.84% (102 cases) vs. 2.74% (502 cases), P<0.001). The mortality of both STEMI and NSTEMI were significantly decreased during the 11 years (both P value for χ(2) trend test <0.001). After adjusting for other risk factors, NSTEMI was independently associated with lower in-hospital mortality (OR=0.50, 95%CI 0.40-0.63, P<0.001). Conclusions: In patients with AMI, the constituent ratio of NSTEMI versus STEMI is increased during the 11 years. The in-hospital mortality is decreased for both STEMI and NSTEMI patients in the past 11 years, and the in-hospital mortality rate of NSTEMI patients is lower than STEMI patients in this patient cohort during the observation period.

Control of axillary bud initiation and shoot architecture in Arabidopsis through the SUPERSHOOT gene

The aerial architecture of flowering plants is determined to a large extent by shoot growth and shoot branching arising from the initiation and growth of axillary meristems. We have identified an Arabidopsis mutant, supershoot (sps), which is characterized by a massive overproliferation of shoots, such that a single plant can generate 500 or more inflorescences. Analysis of the mutant plants shows that the primary defect is because of an increase in the number of meristems formed in leaf axils, together with release of bud arrest, resulting in reiterative branch formation from rosette and cauline leaves. The SPS gene is shown here to encode a cytochrome P450, and together with a 3- to 9-fold increase in levels of Z-type cytokinins in sps mutant plants, indicate a role for SPS in modulating hormone levels. The expression pattern of SPS, with strong expression at the leaf axils, correlates well with the phenotypic defects. Our results indicate that control of shoot branching in Arabidopsis may be accomplished in part by suppression of axillary meristem initiation and growth through the localized attenuation of cytokinin levels at sites of bud initiation.

Effects of elevated [CO(2)] and nitrogen nutrition on cytokinins in the xylem sap and leaves of cotton

We measured the level of xylem-derived cytokinins (CKs) entering a cotton leaf, and the CK levels in the same leaf, thus enabling xylem sap and foliar CKs to be compared concurrently. Although zeatin was the dominant CK in xylem sap, zeatin, dihydrozeatin, and N(6)-(2-isopentenyl) adenine were present in approximately equimolar levels in leaves. Elevated [CO(2)] (EC) has an effect on the levels of cytokinins in sap and leaf tissues. This effect was modulated by the two levels of root nitrogen nutrition (2 and 12 mM nitrate). Growth enhancement (70%) in EC over plants in ambient [CO(2)] (AC) was observed for both nitrogen nutrition treatments. Low-nitrogen leaves growing in EC exhibited photosynthetic acclimation, whereas there was no sign of photosynthetic acclimation in high-nitrogen grown leaves. Under these prevailing conditions, xylem sap and leaf tissues were obtained for CK analysis. Higher nitrogen nutrition increased the delivery per unit leaf area of CKs to the leaf at AC. EC caused a greater increase in CK delivery to the leaf at low nitrogen conditions (106%) than at high nitrogen conditions (17%). EC induced a significant increase in CK content in low-nitrogen leaves, whereas CK content in leaf tissues was similar for high-nitrogen leaves growing in AC and EC.

A technique for the culture of Barrett's oesophageal cells

Establishment of cells in tissue culture from Barrett's columnar epithelium has been difficult. The aim of this study was to develop a successful tissue culture method employing a serum-free medium for cultivation of Barrett's epithelial cells. Fragments of Barrett's mucosal tissue were explanted in a 3:1 mixture of Dulbecco's modification of Eagle's medium and Ham's F12, to initiate the outgrowth of epithelial cells. Subsequently, a commercial serum-free medium (formulated for the growth of keratinocytes) was used for the propagation of Barrett's oesophagus cells without fibroblast growth. Cells established in culture retained their epithelial morphology, stained positive for cytokeratin, and contained Alcian blue (pH 2.5) and periodic acid-Schiff reagent-positive/diastase-resistant vacuoles, confirming their origin from Barrett's epithelium. Electron microscopy showed tonofilaments, microvilli and desmosomes. Coating the surface of culture vessels was not required and four cell strains could be passaged up to 20 times with no fibroblast growth, in the keratinocyte serum-free medium.