Inhibition of platelet adhesion to fibronectin, fibrinogen, and von Willebrand factor substrates by a synthetic tetrapeptide derived from the cell-binding domain of fibronectin

The role in platelet function of the cell-binding region of fibronectin was explored by the use of synthetic peptides. The prototypical peptide gly-arg-gly-asp-ser was capable of inhibiting thrombin-induced platelet aggregation without altering the degree of platelet activation as judged by the secretion of 14C-serotonin. The peptide also effectively inhibited, in a concentration-dependent manner, the binding of radiolabeled fibronectin to platelets and the adhesion of platelets to fibronectin substrates. The smallest peptide from the cell-binding region of fibronectin which retained full activity was arg-gly-asp-ser. Transposition of amino acids or conservative substitutions of amino acids within this short sequence resulted in inactive peptides. Peptides containing the arg-gly-asp-ser sequence were also capable of inhibiting the adhesion of platelets to fibrinogen and von Willebrand factor substrates. Examination of the entire panel of synthetic peptides for ability to inhibit adhesion to fibrinogen or von Willebrand factor substrates revealed the same structure-function relationships that had been determined in the studies with fibronectin.     

Preliminary Clinical Study on Perforating Prosthokeratoplasty

Purpose:To observe the effects of perforating prosthokeratoplasty on patients with leucoma who failed in keratoplasty or were not suitable for keratoplasty, and improved their vision.Methods:Five cases with leucoma (4 with chemical burn and 1 with blast) received Yakimenko Style keratoprosthesis implantation. Preoperative examination showed the visual acuity in 4 of the 5 cases was light perception, and that of the other one was FC/20 cm. The light orientation in 3 patients was definite, and that in the other two was indefinite.Results:The vision improved in 4 of 5 patients in the follow-up period of 9 months to 3 years. Their visual acuity showed 0.09 to 0.8. And there was no change of vision in the other 1 case.Conclutions:Prosthokeratoplasty is the first choice for rehabilitation of the blind that have leucoma but are not suitable for or failed in penetrating keratoplasty. Eye Science 2003;19:146-149.     

The production of contact sensitivity by the injection into the footpads of recipients of the lymph node cells from mice 1 day after painting the skin with contact sensitizing agent: requirement for matching at the major histocompatibility complex between donor and recipient mice.

Donor mice were painted on the skin of the abdomen with the contact sensitizing agent, oxazolone. One day later 2-5 x 10(6) cells from the regional lymph nodes were injected into the footpads of recipient mice. Contact sensitivity was detected 6 days later by challenging the ears of the recipients and measuring the increase of thickness at 24 h. Good contact sensitivity was obtained when CBA cells were injected into CBA mice and BALB/c cells injected into BALB/c mice; the injection of BALB/c (H-2d) cells into CBA (H-2k) mice and vice versa failed to give rise to contact sensitivity. Hybrid F1 cells gave intermediate responses. The contact sensitivity caused by the injection of small numbers of lymph node cells into the footpad is interpreted as a mode of active immunization and the present results show that this only occurs when there is genetic matching at the major histocompatibility complex between the donor and the recipient mouse.     

穿透人工角膜植入术的初步临床观察

目的 应用穿透人工角膜植入术使角膜移植失败或难以进行角膜移植的角膜白斑患者脱盲。方法 应用Yakimenko型人工角膜对4例化学烧伤后角膜白斑和1例爆炸伤后的角膜白斑进行了穿透人工角膜植入术。术前3例光定位准确，2例光定位不准确。结果 术后1眼视力无变化。4眼视力有不同程度的提高(0．09～0．6)、其中最好的1例术后裸眼视力为0．6，矫正视力为0．8，观察时间9个月～3年。结论 应用耳软骨加固人工角膜植床是一个行之有效的方法，对不能行角膜移植和角膜移植失败但尚存光感的角膜白斑患者，穿透人工角膜植入术是目前首选的复明手术。     

Vitamin A status of children in Sri Lanka.

A representative country-wide rural nutrition status survey determined the extent and distribution of vitamin A deficiency in Sri Lanka in children 6 through 71 months of age. Trained paramedical personnel recorded the presence or absence of selected ophthalmological signs and symptoms associated with vitamin A deficiency in 13,450 children. The results of the country-wide clinical survey indicate that a vitamin A deficiency problem of public health importance may exist in two of 15 health areas. Serum vitamin A levels were determined on 346 survey children from two of 15 health areas and compared with clinical findings for these areas. The lowest mean serum vitamin A, 26.3 microgram/100 ml, occurred in children with clinical eye findings. A high prevalence of clinical eye findings, 34%, and the low mean serum vitamin A value, 28.2 microgram/100 ml, were found in the group of chronically undernourished children--children who are less than 90% of their expected height for age. The survey results enabled planned redirection of the distribution of vitamin A capsules to preschool children in Sri Lanka to areas shown to have the highest prevalences of ophthalmological signs and symptoms and/or the highest prevalence of chronic undernutrition.     

人胚胎干细胞源性表皮样干细胞分化潜能

[目的]探讨人胚胎干细胞源性表皮样干细胞的分化潜能,为研究其分化的调控机制及寻找新的人皮肤组织工程种子细胞奠定基础.[方法]将人胚胎干细胞与人羊膜共培养 4 d,定向诱导其分化为表皮样干细胞克隆,用胰酶消化后移植裸鼠皮下 20 d、 30 d及 50 d.对移植后细胞的分化情况进行了形态学和免疫组织化学观察分析.[结果]人胚胎干细胞源性表皮样干细胞在裸鼠皮下 20～ 30 d后,细胞分化为由单层或复层上皮样细胞构成的管状或泡状结构,它们可分别呈 CEA和 CK18阳性.种植 50 d后,除上述结构外,可见角化复层扁平上皮、毛囊样、汗腺样及皮脂腺样等结构.[结论]研究结果提示人胚胎干细胞源性表皮样干细胞具有分化为角化复层扁平上皮及毛囊样、汗腺样和皮脂腺样等结构的潜能.