Nacre surface transformation to hydroxyapatite in a phosphate buffer solution

Nacre, also known as mother-of-pearl, constitutes the inner layer of mollusc shells. Nacre is a natural composite material consisting mostly of calcium carbonate in the aragonite crystal form and some organic matter. Previous studies have shown that geological aragonite, coral and nacre can convert hydrothermally to hydroxyapatite (HAP) in phosphate solution by a solid-state topotactic ion-exchange reaction. This conversion typically occurs within the range of 140-260 degrees C, although higher temperatures are possible. In this work, we have found that nacre can transform to HAP in a phosphate buffer solution at room temperature via a surface reaction. The morphology of the nacre-transformed HAP surface was investigated by scanning electron microscopy (SEM). The HAP surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). A layer covered with packed particles was found in contrast to the tablet structure typical of nacre surfaces. XPS and SIMS indicated that the mineral phase of the nacre surface had converted from an aragonite phase to an HAP phase. Fourier transform infrared spectroscopy (FTIR) showed that phosphate (PO(4)) bands appeared after nacre was soaked in a phosphate buffer and the intensity of the PO(4) bands increased with exposure time. The FTIR was consistent with XPS and SIMS results. We suggest that this surface reaction occurs by a dissolution-precipitation mechanism. Calcium ions are released from the nacre surface, react with phosphate ions in the buffer solution, and then precipitate as HAP on the nacre surface.     

Relationship between a novel human cytotoxin (factor 2) produced by a B cell line (Karpas 160) and phorbol-myristate-acetate-associated cytotoxicity.

We found that 160b cells, a subclone of Karpas 160 human B cell line, spontaneously secreted a novel cytotoxin, factor 2 (F2). F2 was also extracted from the cells by 60% ammonium sulphate, 0.5% CHAPS and 0.28% Triton X-114. We were able to show that phorbol myristate acetate (PMA) greatly enhanced the production of F2, and PMA may also account for part of the putative F2 cytotoxic activity to K562 cells in crude preparations. We compared the cytotoxic effect of F2 with PMA-associated F2-like cytotoxicity to K562 cells as well as the adequacy of our schemes to purified F2 with regard to its separation from PMA. We found that it was possible to separate PMA from F2 preparations by gel filtration and Rotofor preparative isoelectric focusing. The fate of PMA was also monitored with 3H-PMA and chromatographic profiles of 3H-PMA were studied using DE52 and gel filtration chromatography. We were able to establish that less than 2.9% of the cytotoxicity to K562 was due to PMA. We also found that the radioactive peaks and cytotoxicity peaks to K562 were not well correlated, indicating that the cytotoxicity was not mainly due to remaining PMA. Activated charcoal removed virtually all F2 and PMA but not tumour necrosis factor activity. Our results also showed that cytotoxicity to K562 resulting from F2 or PMA-associated proteins had different physicochemical properties, indicating that they are different molecular entities. These findings are consistent with the earlier observation that 160 cells produce F2 spontaneously and that PMA can amplify its production significantly.     

Relationship between HLA-DRB1 and DQ alleles and the genetic susceptibility to type 1 diabetes

Objective　To study the relationship between human leukocyte antigen (HLA)-DRB1 and DQ alleles and the genetic susceptibility of type 1 diabetes in North Chinese children. Methods　Polymerase chain reaction (PCR) techniques were used to amplify the second exon of DRB1 and DQ alleles, after which sequence specific olignucleotide probe (SSOP) dot blot hybridization techniques were used to analyze the amplified products. Results　DRB1*0301, DQA1*0301, DQB1*0201 alleles and DRB1*0301-DQA1*0501-DQB1*0201 haplotype were significantly increased in patients, while DQA1*0103 and DQB1*0601 alleles were significantly increased in controls. The distribution of DR4 and DR9 haplotypes in patients and controls were not significantly different, but DR3/DR4 and DR4/DR9 heterozygotes were significantly increased in patients. Conclusions　DRB1*0301, DQA1*0301 and DQB1*0201 confer susceptibility while DQA1*0103 and DQB1*0601 confer protection to type 1 diabetes. DRB1*0301-DQA1*0501-DQB1*0201 haplotype offers a predisposition to type 1 diabetes in North Chinese. Although the distribution of DR4 and DR9 in patients and controls had no significant difference, DR3/DR4 and DR3/DR9 heterozygotes were significantly increased in patients, showing that the susceptive effects of DR3 and DR4 or DR4 and DR9 haplotypes could be added up.     

L-精氨酸对兔血管平滑肌细胞体外增殖的影响

目的：探讨Ｌ－精氨酸抗动脉粥样硬化（ＡＳ）的作用机制。方法：观察Ｌ－ａｒｇ对兔血管平滑肌细胞（ＶＳＭＣ）体外增殖的影响。结果：Ｌ－ａｒｇ显著增加一氧化氮（ＮＯ）含量,明显抑制ＶＳＭＣ,并呈剂量依赖性。加入单甲基－Ｌ－精氨酸（Ｌ－ＮＭＭＡ）,上述作用被逆转 。结论：Ｌ－ａｒｇ可显著抑制兔ＶＳＭＣ体外增殖,且此作用由Ｌ－ａｒｇ转则ａｒｇ抗ＡＳ的作用可能与此有关。     

nm23-H1基因在人贲门癌中的表达

目的 :检测转移抑制基因 nm2 3- H1在贲门癌中的表达 ,探讨其与贲门癌生物学特性和其他病理学指标的关系。方法 :应用免疫组化染色技术对 2 8例贲门癌组织中的 nm2 3- H1进行检测并与正常组织对照。结果 :贲门癌及其相应的正常组织中 nm2 3- H1蛋白表达率分别为 67.9%和71 .4% ,两者间无显著性差异 ( P<0 .0 5)。 nm2 3- H1蛋白在贲门癌中的表达 ,随肿瘤浸润程度的增加而表达下降 ( P>0 .0 5) ;在淋巴结转移阳性组贲门癌中 ,表达阳性率为 46.2 % ,而淋巴结转移阴性组为 92 .8% ,两者差异显著 ( P<0 .0 5)。结论 :nm2 3- H1蛋白表达在肿瘤分化程度高组与低组之间 ,无显著性差异。     

Graves 与ABO血型的关联分析

目的：探讨Graves病(GD)与ABO血型的相关性。方法：采用玻片凝集法鉴定我院汉族GD患者215例ABO血型分布并进行疾病与血型的关联分析。结果：GD患者血型分布特征为O＞B＞A＞AB。发病相对危险率(RR),O型RR＞2,其他血型均RR＜1;A/O、B/O、AB/O均RR＜1(P＜0.01～0.0001)。结论：GD的发生可能与ABO血型有关。     

大鼠应激时垂体c-fos和催乳素基因表达关系的研究

目的：探讨应激刺激下,垂体是否有ｃ－ｆｏｓ表达及其与催乳素（ＰＲＬ）基因表达的关系。方法：雌性Ｗｉｓｔａｔａｒ大鼠给予禁锢应激６０ｍｉｎ,用原位杂效方法检测应激开始后１５,３０,６０,１２０,１８０ｍｉｎ时ＲＰＬ ｍＲＮＡ水平。结果：基础状态下垂体前叶ｃ－ｆｏｓ有弱表达,在禁应激开始后１５￣３０ｍｉｎ迅速增加达高峰,尔后下降,在１２０￣１８０ｍｉｎ出现第２次表达高峰,ＰＲＬ ｍＲＮＡ水平的改变与ｃ     

流行性出血热患者早期免疫应答的研究

应用反向被动血凝集抑制试验和血凝集抑制试验检测流行性出血热患者早期血清（７病日内）中病毒核蛋白、膜蛋白抗体。１０３例患者血清,仅核蛋白抗体出现者３３例,病情转径及无变化者３１例（９３．９４％）．而转重者仅２例（６．０６％）,且其血清抗体主要为ＩｇＧ型。仅膜蛋白抗体出现的患者９例,病情转重者８例（８８．８９％）,其抗体主要为ＩｇＭ．核蛋白、膜蛋白抗体均阳性的６１例患者,病情转归介于上述二者之间．提示：核蛋白抗体先出现的患者,病情多转轻,而膜蛋白抗体先出现的患者,病情普遍转重,似与病毒的＂一次性打击＂有关。在仅核蛋白抗体出现的患者中,有２例病情转重,但其抗体球蛋白类型为ＩｇＧ,故尚不能排除本病有＂二次感染＂的可能,这一现象在推行本病预防接种时值得重视,另对进一步探讨本病的发病机理及预测患者的病情转归亦具参考价值。     

儿科临床研究协调员职业培训现状的调查与需求分析

目的 了解儿科临床研究协调员（clinical research coordinator,CRC）职业培训现状,探讨儿科CRC基地化培训建设,以促进儿科CRC的能力提升。方法 采用匿名问卷调研法,于2023年7月25日至10月16日期间,通过问卷星向调查对象发放自行设计的问卷,以进行儿科CRC职业培训及基地化培训需求相关情况的调查分析。采用Excel对数据进行整理。计数资料以例数或者率表示。结果 回收有效问卷328份。调查结果显示,认为当前CRC培训充分且可以满足实际工作需求的仅为7.62%（25人）,另有4.88%（16人）的人认为没有CRC培训,46.34%（152人）的人认为培训不足以支撑实际工作的要求。87.50%（287人）的人认为CRC需要持续的培训。46.95%（154人）的人选择了有经验的CRC是较为合适的带教人员之一,但是需要3年及以上CRC工作经验。46.95%（154人）选择了CRC合适的培训时长为3个月。培训方式的选择从高到低为：有经验的CRC带教实习（90.85%,298人）、实操技能手把手带教（88.41%,290人）、案例分析讨论（87.20%,286人）、流程模拟（83.23%,273人）、授课（76.52%,251人）。培训后考核方式的选择从高到低为：案例分析（76.52%,251人）、操作模拟（74.09%,243人）、流程模拟（73.17%,240人）、笔试（66.16%,217人）、面试（63.72%,209人）。结论 目前,儿科CRC的培训还不足以满足实际工作需求,急需制定一个符合工作需要的CRC培训体系并进行推广实践,从基础上促进中国儿科临床研究健康生态的构建。     

阻塞性睡眠呼吸暂停综合征的听觉脑干电反应

１９９１年１月至１９９８年１月共有８０例阻塞性睡眠呼吸暂停综合征患者在我科接受悬雍垂腭咽成形术治疗,其中４１例行听觉及脑干电反应测试。ＡＢＲ各波潜伏期,峰间期及Ｉ,Ｖ波波幅与下沉对照人群的测试结果相近,差异无统计学意义,表明阻塞性睡眠呼吸暂停综合征并非必须合并ＡＢＲ的异常。