表观遗传调控与青光眼发病机制研究进展

表观遗传学主要机制包括DNA甲基化、组蛋白修饰和miRNAs等。这些机制将环境与基因相联系，在基因的特异性表达过程中发挥重要作用，影响疾病的表型。青光眼是全球第一大不可逆致盲眼病，其发病机制复杂，受遗传和环境的共同影响。本文分别对DNA甲基化、组蛋白修饰和miRNAs参与青光眼发病的机制进行综述，以期为临床诊治提供参考。     

DNA damage by the glycation products of glyceraldehyde 3-phosphate and lysine

Summary In order to evaluate whether base modifications, apurinic/apyrimidinic site formation, strand breaks, or a combination of these lesions results from the interaction of glycation products with DNA, plasmid DNA was first reacted with these products, and then subjected to digestion with endonuclease III and endonuclease IV of Escherichia coli. Analysis of the differential effects of digestions with these enzymes by electrophoresis on agarose gels demonstrated that reactive glycation products produce both base modification and apurinic/apyrimidinic sites in DNA, in addition to the strand breaks observed after incubation with glycation products alone. These types of DNA damage may occur in specific diabetic cells where elevated levels of glycating sugars are associated with pathologic dysfunction. [Diabetologia (1994) 37: 145–149] Received: 28 May 1993 and in revised form: 30 August 1993     

Some Guidelines for the Use of Stimulus Modifications in Teaching Response Topography to People with Developmental Disabilities

The use of stimulus modifications in teaching involves altering the materials of a task in order to simplify its execution. Though their use in teaching stimulus discriminations to people with developmental disabilities has been extensively investigated, less attention has been given to their utilization in teaching response topography. This paper offers some general guidelines about their use for this purpose. In relation to their design, it is suggested that the aim should be to reduce the demands made by task components, to eliminate components, and/or to increase the attentional value of the discriminating features of the response topography. In relation to their application, guidelines are suggested about when they should be employed in conjunction with response prompts; when they should be used, either alone or in conjunction with response prompts, in preference to response prompts alone; whether one or a series of modifications is required; and at what point during teaching should probe trials on the unmodified task be introduced.     

Partial Blocking of Mouse DSPP Processing by Substitution of Gly451–Asp452 Bond Suggests the Presence of Secondary Cleavage Site(s)

Dentin sialophosphoprotein (DSPP) in the extracellular matrix of dentin is cleaved into dentin sialoprotein and dentin phosphoprotein, which originate from the NH₂-terminal and COOH-terminal regions of DSPP, respectively. In the proteolytic processing of mouse DSPP, the peptide bond at Gly⁴⁵¹–Asp⁴⁵² has been shown to be cleaved by bone morphogenetic protein 1 (BMP1)/Tolloid-like metalloproteinases. In this study, we generated transgenic mice expressing a mutant DSPP in which Asp⁴⁵² was substituted by Ala⁴⁵². Protein chemistry analyses of extracts from the long bone of these transgenic mice showed that the D452A substitution partially blocked DSPP processing in vivo. When the full-length form of mutant DSPP (designated “D452A-DSPP”) isolated from the transgenic mice was treated with BMP1 in vitro, a portion of the D452A-DSPP was cleaved, suggesting the presence of secondary peptide bond(s) that can be broken by BMP1. To identify the potential secondary DSPP cleavage site(s), site-directed mutagenesis was performed to generate nine DNA constructs expressing DSPP-bearing substitutions at potential scission sites. These different types of mutant DSPP made in eukaryotic cell lines were treated with BMP1 and the digestion products were assessed by Western immunoblotting. All of the mutant DSPP molecular species were partially cleaved by BMP1, giving rise to a protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis similar to that of normal dentin sialoprotein. Taken together, we concluded that in addition to the peptide bond Gly⁴⁵¹–Asp⁴⁵², there must be a cryptic cleavage site or sites close to Asp⁴⁵² in the mouse DSPP that can be cleaved by BMP1.     

Enhanced SUMOylation and SENP-1 protein levels following oxygen and glucose deprivation in neurones

Here, we show that oxygen and glucose deprivation (OGD) causes increased small ubiquitin-like modifier (SUMO)-1 and SUMO-2/3 conjugation to substrate proteins in cultured hippocampal neurones. Surprisingly, the SUMO protease SENP-1, which removes SUMO from conjugated proteins, was also increased by OGD, suggesting that the neuronal response to OGD involves a complex interplay between SUMOylation and deSUMOylation. Importantly, decreasing global SUMOylation in cultured hippocampal neurones by overexpression of the catalytic domain of SENP-1 increased neuronal vulnerability to OGD-induced cell death. Taken together, these results suggest a neuroprotective role for neuronal SUMOylation after OGD.     

A review of the effects of the cell environment physicochemical nanoarchitecture on stem cell commitment

Physicochemical features of a cell nanoenvironment exert important influence on stem cell behavior and include the influence of matrix elasticity and topography on differentiation processes. The presence of growth factors such as TGF-β and BMPs on these matrices provides chemical cues and thus plays vital role in directing eventual stem cell fate. Engineering of functional biomimetic scaffolds that present programmed spatio-temporal physical and chemical signals to stem cells holds great promise in stem cell therapy. Progress in this field requires tacit understanding of the mechanistic aspects of cell-environment nanointeractions, so that they can be manipulated and exploited for the design of sophisticated next generation biomaterials. In this review, we report and discuss the evolution of these processes and pathways in the context of matrix adhesion as they might relate to stemness and stem cell differentiation. Super-resolution microscopy and single-molecule methods for in vitro nano-manipulation are helping to identify and characterize the molecules and mechanics of structural transitions within stem cells and matrices. All these advances facilitate research toward understanding of stem cell niche and consequently to developing new class of biomaterials helping the “used biomaterials” for applications in tissue engineering and regenerative medicine.     

Phenethyl Isothiocyanate Protects against High Fat/Cholesterol Diet-Induced Obesity and Atherosclerosis in C57BL/6 Mice

This study concerns obesity-related atherosclerosis, hyperlipidemia, and chronic inflammation. We studied the anti-obesity and anti-atherosclerosis effects of phenethyl isothiocyanate (PEITC) and explored their underlying mechanisms. We established an animal model of high fat/cholesterol-induced obesity in C57BL/6 mice fed for 13 weeks. We divided the mice into five groups: control (CON), high fat/cholesterol (HFCD), HFCD with 3 mg/kg/day gallic acid (HFCD + G), and HFCD with PEITC (30 and 75 mg/kg/day; HFCD + P30 and P75). The body weight, total cholesterol, and triglyceride were significantly lower in the HFCD + P75 group than in the HFCD group. Hepatic lipid accumulation and atherosclerotic plaque formation in the aorta were significantly lower in both HFCD + PEITC groups than in the HFCD group, as revealed by hematoxylin and eosin (H&E) staining. To elucidate the mechanism, we identified the expression of genes related to inflammation, reverse cholesterol transport, and lipid accumulation pathway in the liver. The expression levels of peroxisome proliferator activated receptor gamma (PPARγ), liver-X-receptor α (LXR-α), and ATP binding cassette subfamily A member 1 (ABCA1) were increased, while those of scavenger receptor A (SR-A1), cluster of differentiation 36 (CD36), and nuclear factor-kappa B (NF-κB) were decreased in the HFCD + P75 group compared with those in the HFCD group. Moreover, PEITC modulated H3K9 and H3K27 acetylation, H3K4 dimethylation, and H3K27 di-/trimethylation in the HFCD + P75 group. We, therefore, suggest that supplementation with PEITC may be a potential candidate for the treatment and prevention of atherosclerosis and obesity.     

Management of Type 2 Diabetes: Current Strategies,Unfocussed Aspects,Challenges, and Alternatives

Type 2 diabetes mellitus (T2DM) accounts for >90% of the cases of diabetes in adults. Resistance to insulin action is the major cause that leads to chronic hyperglycemia in diabetic patients. T2DM is the consequence of activation of multiple pathways and factors involved in insulin resistance and β-cell dysfunction. Also, the etiology of T2DM involves the complex interplay between genetics and environmental factors. This interplay can be governed efficiently by lifestyle modifications to achieve better management of diabetes. The present review aims at discussing the major factors involved in the development of T2DM that remain unfocussed during the anti-diabetic therapy. The review also focuses on lifestyle modifications that are warranted for the successful management of T2DM. In addition, it attempts to explain flaws in current strategies to combat diabetes. The employability of phytoconstituents as multitargeting molecules and their potential use as effective therapeutic adjuvants to first line hypoglycemic agents to prevent side effects caused by the synthetic drugs are also discussed.     

Modification of Surgery Equipment for Ovine Surgery

Surgery equipment was modified for ovine surgery. Pre- and postoperative holding pens were designed to meet the specific requirements of sheep. A hydraulic trolley lift was constructed and operating tables fitted with spilltrays. A gag was made to protect Magill tubing and the indifferent electrode was altered for electrosurgery. For fluoroscopy a flexible table was constructed to accommodate sheep.