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21.
Objective: To prepare hydroxyapatite cement (or calcium phosphate cement,CPC) and analyze its capability. Methods: Tetracalcium phospluge (TTCP ) was prepared by the method of high heat. TTCP reacted with in simulated body situation and produced CPC. Its capability was analyzed by scanning electron microscopy ( SEM), X-ray diffraction( XRD). Its density, absorbing water coefficient, macroporosity and compressive strength were measured also. Results: The main element of CPC is hydroxyapatile (HA), its microstructure comprised of petal crys-tals. The diameter of micropore was 4-10μm, density was 1. 922 g/cm^3, macroporosity was 29. 777%, absorbing coefficient was 15. 503%, compressive strength was 42.70 Mpa. Conclusion: This CPC has three-dimensional spatial structure, its strength meets the need of cancellous bone grafting. 相似文献
22.
Placenta can be considered as a pump of calcium necessary for the normal development of the fetus. We believe that the location of this pump is in the placental basement membrane. The calcification of this membrane has been described only in cases of in utero fetal death. In this study we describe for the first time a case of placental calcification in a living fetus. The fetus of a normal 21-year-old pregnant woman showed heart abnormalities but the genetic analysis showed a normal male karyotype. The histology of the placenta demonstrated multiple intravillous linear and granular calcific incrustations The hemtoxylin/eosin stain of the sections revealed basement membrane calcific incrustations and intravillous calcium deposits. We postulate that the fetal circulation in the villi was impaired and the calcium that reached the villi from the mother was deposited at this level. 相似文献
23.
Fumonisins as a possible contributory risk factor for primary liver cancer: A 3-year study of corn harvested in Haimen, China, by HPLC and ELISA 总被引:13,自引:0,他引:13
Y. Ueno K. Iijima S.-D. Wang Y. Sugiura M. Sekijima T. Tanaka C. Chen S.-Z. Yu 《Food and chemical toxicology》1997,35(12):1143-1150
Employing HPLC fluorometry, gas-liquid chromatography (GLC) and a novel enzymelinked immunosorbent assay (ELISA) based on a monoclonal antibody, 40 corn samples, each collected in 1993 from agricultural stocks for human consumption in Haimen (Jiangsu County) and Penlai (Shandong Province), high- and low-risk areas for primary liver cancer (PLC) in China, respectively, were analysed for fumonisins (FBs), aflatoxins (AFs) and trichothecenes. Levels and positive rates of FBs and deoxynivalenol (DON) were significantly higher in Haimen than in Penlai. ELISA of the 40 corn samples harvested in the two areas in 1994 revealed that FB contamination levels and rates in these areas were comparable to those observed in 1993 in Haimen. ELISA analysis of 1993 and 1994 products revealed a wide occurrence of AFB1 but the positive rates as well as levels were not significantly different between these areas. ELISA of the same sample number of corn harvested in 1995 revealed that FB contamination in Haimen was significantly higher than in Penlai. These 3-yearly surveys of corn samples (240 in total) demonstrated that corn harvested in Haimen was highly contaminated with FBs and that the contamination level, as well as positive rate in 1993 and 1995, were 10–50-fold higher than those in Penlai, suggesting FBs as a risk factor for promotion of PLC in endemic areas, along with the trichothecene DON. Co-contamination with AFs, potent hepatocarcinogens, was assumed to play an important role in the initiation of hepatocarcinogenesis. 相似文献
24.
目的:制备水泥型羟基磷灰石人工骨,并进行性能分析。方法:高温法制备出磷酸四钙,然后在模拟体内环境下将其与无水磷酸氢钙发生水化固化反应,合成水泥型羟基磷灰石人工骨,采用X线衍射、扫描电镜观察、体积密度、吸水率、孔隙率及耐压强度测量进行性能分析。结果:该人工骨主要成分为低结晶度的羟基磷灰石;微观结构呈针状或花瓣状晶体构成,微孔直径约4-10 μm,孔隙相互交通;平均体积密度为1.922 g·cm~(-3);平均吸水率为15.503%;孔隙率为29.777%;耐压强度为42.70 MPa。结论:本研究所制人工骨具有三维空间结构,力学性能符合人体非负重骨植骨要求。 相似文献
25.
Zheng Qi-xin Zhu Tong-bai Du Jing-yuan Hong Guang-xiang Li Shi-pu Yan Yun-hua Zhang En-dang 《华中科技大学学报(医学英德文版)》1992,12(3):173-178
Summary The authors have prepared the artificial bone of porous tricalcium phosphate ceramics according to an appropriate formula
and manufacturing technology. Physical and chemical testing shows that it possesses several distinguishing features: the communicating
pores and macro/micropores; mean pore size, 380 μm (from 240 μm to 510 μm); porosity, 46.4 %; and compressive strength, 97.4
kg/cm2. It consists of CaO (49.09 %) and P2O5 (48.84 %). The testing of its biocompatibility shows that it is devoid of systemic or local toxicity, and free of irritation
or foreign body response in tissues, and it does not result in hemolysis or mutation. The new bone readily grows into its
pores with direct contact to the implanted material. 11 cases of bone defects were treated with this artificial bone with
satisfactory results. 相似文献
26.
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28.
目的:探讨雌激素,胎盘生乳素,钙在妊高征发病中的作用及其相互关系,方法:采用放射免疫法及离心分析钙试剂,测定了42例妊高征患者血清雌二醇,胎盘生乳素,钙,磷及尿钙,磷的含量,34例同期门诊正常孕妇作为对照组,结果:轻度妊高征患者血清雌二醇明显增加(P〈0.05)。重度妊高征患者血清胎盘生乳素显著减少(P〈0.05),轻,中,重度妊高征患者血钙,尿钙含量显著降低(P〈0.05,P〈0.01,P〈0. 相似文献
29.
Abstract Nitric oxide (NO) plays an important physiological role in regulating gastrointestinal motility. Involvement of endogenous NO was evaluated in the response to non-adrenergic, non-cholinergic (NANC) nerve stimulation of the dog sphincter muscle of Oddi. Transmural electrical stimulation (TES), nicotine (10?5M) and K+ (10 mM) produced only a relaxation in the sphincter muscle strips contracted with substance P, which was not potentiated by atropine. The TES-induced relaxation was abolished by tetrodotoxin (3 times 10?7 M) and oxyhaemoglobin (1.6 times 10?5 M), but not affected by atropine (10?7 M), propranolol (10?7 M), phentolamine (10?7 M), indomethacin (10?6 M), chole-cystokinin (CCK, 10?8 M) and vasoactive intestinal polypeptide (VIP, 10?8 M). The relaxation was also abolished by treatment with NG-nitro-L-arginine (L-NA, 10?5 M), an NO synthase inhibitor. Nicotine produced a transient relaxation, which was abolished by tetrodotoxin, hexamethonium (10?5 M) and L-NA, but not affected by atropine and NG-nitro-D-arginine (D-NA, 10?5 M). The addition of K+ elicited a transient relaxation, which was abolished by tetrodotoxin and L-NA. The inhibitory effects of L-NA were antagonized by L-arginine (10?3 M). The presence of neurons containing nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase was histochemically demonstrated in the sphincter of Oddi. These findings may indicate that TES, nicotine and K+ liberate NO from NANC inhibitory nerve which is involved in the relaxation of the dog sphincter of Oddi. The muscular tone does not seem to be regulated by cholinergic nerves under the experimental conditions used. 相似文献
30.
目的:为了深讨心肌细胞内钙离子浓度的变化与心力衰竭发生的关系。方法:原子吸收分光技术测定红细胞内外Ca2+含量。我们对住院的56例心力衰竭患儿进行了红细胞内及血浆钙离子浓度的测定,并与30例正常小儿对照。结果:心衰患儿红细胞内Ca2+浓度明显升高,血浆Ca2+浓度降低,与对照组相比有非常显著性差异(P<0.001)。其升高程度与心衰呈正相关(r=0.63,P<0.01),即心衰越重,心功能越差,红细胞内Ca2+浓度升高亦越明显。而当心衰纠正,心功能恢复后,红细胞内Ca2+浓度则明显下降,血浆Ca2+浓度也恢复正常。而不同病因所致的心衰,其间红细胞内Ca2+浓度升高程度无明显差异。结论:提示钙离子参与了心力衰竭的发生与发展。 相似文献