A unilateral increase in the occlusal vertical dimension of growing rats results in mandibular deviation.

OBJECTIVE: The effects of unilateral increased occlusal vertical dimension (iOVD) on bilateral craniofacial, mandibular and alveolar development in growing rats were investigated via cone-beam computed tomography (CBCT). The role of Wnt/ß-catenin signalling in this process was examined. MATERIALS AND METHODS: Forty-eight female Sprague-Dawley rats were randomly allocated into unilateral iOVD and sham groups. At 2, 4 and 8 weeks, the rats were scanned via CBCT to analyse cranial, maxillary, mandibular and dental morphology. Changes in temporomandibular joint (TMJ) cartilage histology and Wnt/ß-catenin signalling were assessed by histochemical and immunohistochemical staining and qRT-PCR. RESULTS: Dorsal cephalograms revealed that the mandible in the iOVD group tilted approximately 4° to the right. Unilateral iOVD had little effect on cranial and maxillary growth but inhibited mandibular growth (mandibular length and ramal height), especially on the deviated side (DS). Moreover, unilateral iOVD increased the length of the lower incisors and decreased the height of the molars on the DS. Unilateral iOVD induced bilateral osteoarthritis-like changes in the bilateral TMJ condylar cartilage and activated Wnt/ß-catenin signalling in the condylar cartilage, especially on the contralateral side (CLS). CONCLUSION: Occlusion with unilateral iOVD induced mandibular deviation, significantly inhibited mandibular growth and produced compensatory changes in the alveolar bone. In the iOVD group, the mandibular body length and ramal height were greater on the CLS than on the DS. Moreover, the greater ß-catenin protein expression in the TMJ condylar cartilage on the CLS than on the DS may account for the difference in asymmetrical mandibular development.

Research progress on the cellular toxicity caused by microplastics and nanoplastics.

Microplastics (MPs) are plastic particles of a diameter of less than 5 mm and a major carrier of pollution. In accordance with its diameter range, MPs can be divided into microplastics (100-5 mm) and nanoplastics (<100 nm). In recent years, in addition to the impact of MPs on the environment, the ways in which MPs affect the body has also attracted continuous attention. However, relevant studies on the cytotoxicity of MPs are not comprehensive. Based on the current research, this paper summarizes four main cytotoxic mechanisms of MPs, inducing oxidative stress, damaging cell membrane organelles, inducing immune response, and genotoxicity. Generally, MPs cause cytotoxicity such as oxidative stress, damage to cell membranes and organelles, activation of immune responses, and genotoxicity through mechanical damage or induction of cells to produce reactive oxygen species. Understanding these toxic mechanisms is helpful for the evaluation and prevention of human toxicity of MPs. This paper also analyzes the limitations of current research and prospects for future research into cellular MPs, with the aim of providing a scientific basis and reference for further research into the toxic mechanism of MPs.

Responses of Nonprotein Thiols to Stress of Vanadium and Mercury in Maize (Zea mays L.) Seedlings.

The heavy metal pollution in ecosystems is of increasing global concern. This study investigated firstly the responses of phytochelatins (PCs), glutathione (GSH) and other nonprotein thiols (NPT) in maize seedlings under vanadium (V), mercury (Hg) or their combined stress. With V or V-Hg combined stress, the contents of PCs, GSH and NPT in shoots and roots both increased with increasing the V stress level, and reached the maximum when the V stress level was 5 mg/L. Accumulation of V in all organs of maize seedlings was in sequence as follows: roots ≫ shoots, while Hg inhibited the accumulation of V. Results show that the root of plant has stronger tolerance to V, and the low V stress level can promote the synthesis of thiol groups to reduce the toxicity of Hg for plants.

Palladium-catalysed fragmentary esterification-induced allylic alkylation of allyl carbonates and cyclic vinylogous anhydrides.

An unprecedented palladium-catalysed fragmentary esterification-induced allylic alkylation (FEAA) of cyclic vinylogous anhydrides (CVAs) and allyl carbonates has been disclosed. The protocol features broad sp3-rich scaffold tolerance, rendering highly functionalized 1,6 and 1,7-dicarbonyls in up to high yields and diastereoselectivities. Three-component FEAA is also well tolerant to generate 1,6-dicarbonyls through the addition of extra O/N-nucleophiles. Furthermore, cyclic allyl carbonate-involved FEAA provides an efficient approach for the synthesis of structurally complex medium-sized rings.

Absorption, transport, content, and subcellular distribution of vanadium in the polysaccharide fraction of cell wall in corn seedlings.

This study investigated the tolerance of plants to vanadium (Ⅴ). The hydroponic method was employed to evaluate the absorption, transport, content, and subcellular distribution of vanadium in the polysaccharide fraction of corn seedlings cell wall under different concentrations of vanadium stress. Results showed that: (a) vanadium was mainly concentrated in the roots of the corn seedlings, and only trace amounts were transported to the leaves; (b) in terms of its subcellular distribution, vanadium was mainly enriched in cell wall regions followed by soluble fraction; (c) the content of vanadium in polysaccharide fraction was highest in alkali-soluble pectin, followed by chelated pectin (P < 0.05).