High resolution transmission electron microscopy of age-hardenable Au-Cu-Zn alloys for dental applications

Microstructures of age-hardenable AuCu-Zn pseudobinary alloys for dental applications were studied by means of high resolution transmission electron microscopic (HRTEM) observation and X-ray diffraction study. HRTEM study revealed that the appearance frequency of antiphase boundaries (APBs) per unit volume of the AuCu II superstructure effectively increased by Zn addition to AuCu, which may be the reason for that high hardness was maintained for a long time in AuCu-Zn alloys. The disordered APBs zone in the AuCu II superstructure had wavy characteristics and fluctuated within regular range. With increasing Zn content in AuCu-Zn alloys, the fluctuation range of APBs' width became narrower, thus random APBs' spacing and irregular APBs' shape of AuCu II superstructure changed to comparatively regular APBs' spacing and shape. Due to the APBs' wavy characteristics, spacing between successive APBs, M, was not constant but scattered, and the magnitude of the scattering of M value decreased with increasing Zn content. By Zn addition to AuCu, phase transformation from a disordered alpha phase to AuCu II phase was greatly accelerated, which made it possible for the AuCu-Zn alloy to have excellent age-hardenability at relatively low temperature like intraoral temperature.     

Age hardening by dendrite growth in a low-gold dental casting alloy

Commercial low-gold dental casting alloy composed of Ag-Pd-In-Au-Zn was studied to clarify the age-hardening mechanism and related microstructural changes. The hardness of solution-treated specimen began to increase and reached the maximum value with ageing time, and then the maximum hardness value decreased by further ageing. The changes of X-ray diffraction (XRD) pattern during isothermal ageing revealed that the age hardening was not caused by phase transformation. By comparing the age-hardening curve with the changes in full-width at half-maximum of the XRD peaks at each ageing time, it was revealed that the coherency strains were formed in the Ag-rich matrix, which contributed to the hardness increase during ageing. From scanning electron microscopic observation and electron probe microanalysis, it was clarified that fine particle-like structures composed of InPd containing small amount of Zn gathered by diffusion in the Ag-rich matrix, and the coherency strains which formed during that time caused the hardness increase in the early stage of age-hardening process. The coherency strains were released by the progress of coarsening of Zn-containing InPd dendrite during further ageing, which caused the overaging in the later stage of age-hardening process.     

Age-hardening reactions in a type III dental gold alloy

The age-hardening reactions in a commercial type III dental gold alloy were studied by means of hardness test, X-ray diffraction study and scanning and transmission electron microscopic observations. The hardening was attributed to the formation of the metastable AuCu 1' type ordered phase in the grain interior by the isothermal ageing at 225 and 450 degrees C at which two hardness peaks were observed by the isochronal ageing. By ageing at 450 degrees C, the hardening did not begin immediately because the incubation period was required. The age hardening at 225 degrees C was characterized by a slow growth rate of the metastable AuCu 1' type ordered phase. The overageing with softening which occurred following prolonged ageing at 450 degrees C was due to the formation of the lamellar structure composed of the Ag-rich alpha1 and AuCu 1 type ordered phases at grain boundaries.     

Solubility of compositions in the system CaTixZr4 − x(PO4)6 with X = 0–4

In vitro solubility tests of granulated materials and coatings were carried out on some compositions in the system CaTi_xZr_{4 − x}(PO₄)₆ with x = 0–4, in order to find a biocompatible material which is less soluble than hydroxyapatite (HA) and can also be used as bone substitution material. The granulated materials were leached out by using circulating equipment in which the solvent flows in circulation. The coatings were tested under conditions where the sample containers undergo a circular movement. The results show better chemical stability of nearly all tested compounds compared with HA for both granulated materials and coatings.     

Selective dissolution of AuCu and AuAg alloys in vitro and in vivo

AuCu and AuAg alloys (30 at.% Au) have been immersed in aqueous solutions of chloride and sulphide with additions of protein (mucin). The surfaces of the alloys were subsequently analysed by means of ESCA and compared with previous and similar tests without addition of mucin. No noticeable effect of the mucin addition was observed on the surface composition of the alloys after exposure to the various solutions. Cu in contrast to Ag was found to be selectively dissolved from the 2 or 3 uppermost atomic layers in chloride as well as sulphide solutions (pS > 4), both with and without additions of mucin, leaving behind a surface enriched from 10 to 25 at.% in Au. Testing of the same alloys in vivo for 8 d revealed the same tendencies to selective dissolution of Cu. The AuAg alloy was tarnished in the sulphide solutions and in vivo.     

牙科金属材料的组成对细胞毒性影响的研究

选择９种中日常胜的牙科金属和合金材料，其基本组成是Ｎ－Ｃｒ，Ｃｏ－Ｃｒ－Ｍｏ，Ａｇ－Ｐｄ－Ａｕ－Ｃｕ，Ａｇ－Ｚｎ，Ｎｉ－Ｔｉ，Ｎｉ－Ｃｒ－Ｃｏ和Ｃｕ基，用Ｌ－９２９小鼠成纤维细胞，经细胞－金属表面直接接触４８ｈ，对去除刺激因素的细胞，用紫外分光光度仪和扫描电镜进行检测，并在原子吸收光谱仪下定量分析材料渍液中溶出金属元素的成分，物化学组成，溶解元素对细胞毒性的影响。结果表明Ｃｕ基合金因合中存在分别形     

Calcium level-responsive in-vitro zinc release from zinc containing tricalcium phosphate (ZnTCP)

The in vitro Zn release from tricalcium phosphate containing Zn (ZnTCP; 0.63, 6.17, and 12.05 Zn w/w%) was investigated. The rates of release from ZnTCP powders were measured in 25 mL of simulated body fluid (SBF) containing 10 mg/100mL Ca (SBF/H), 5 mg/100mL Ca (SBF/L), or no Ca (SBF/-) at pH 7.25, 37.0+/-0.1 degrees C. The release from 6 and 12% ZnTCP was initially very fast. The rate of release from ZnTCP decreased as the concentration of Ca in the dissolution media increased, but increased as concentration of Zn in TCP increased. The dissolution kinetics of ZnTCP followed the Hixon-Crowell equation at the initial stage of dissolution, and the initial dissolution rate constant (IDR) was calculated by the least-squares method. The effect of Ca concentration on percent IDR of ZnTCP suggested that Zn release from 0.6% ZnTCP was significantly high compared to that from 6 or 12% ZnTCP. The relationship between the amount of Ca precipitated and Zn release of various ZnTCP samples suggested that the release from 0.6% ZnTCP was significantly different compared to that from 6 and 12% ZnTCP, consistent with the data for percent Zn IDR. X-ray diffraction data suggested that 0.6% ZnTCP contained 5% hydroxyapatite, a low solubility material, which acted as seed crystal during the dissolution test.     

Comparative corrosion study of Ti–Ta alloys for dental applications

Besides other important material features, the corrosion parameters and corrosion products are responsible for limiting the biocompatibility of metallic materials, and can produce undesirable reactions in implant-adjacent and/or more distant tissues. Titanium and some of its alloys are known as being the most biocompatible metallic materials due to their high strength, low modulus, high corrosion resistance in biological media, etc. More recently, Ti–Ta alloys have been developed, and these are expected to become more promising candidates for biomedical and dental applications than commercially pure Ti, Ti–6Al–4V or Ti–6Al–7Nb alloy. The corrosion behavior of the studied Ti–Ta alloys with Ta contents of 30, 40, 50 and 60 wt.% together with the currently used Ti–6Al–7Nb alloy were investigated for dental applications. All alloys were tested by open-circuit potential measurement, linear polarization, potentiodynamic polarization, coulometric zone analysis and electrochemical impedance spectroscopy performed in artificial saliva with different pH, acid lactic and fluoride contents. The passive behavior for all the titanium alloys is observed for artificial saliva, acidified saliva (9.8 g l⁻¹ lactic acid, pH 2.5) and for fluoridated saliva (1.0 g l⁻¹ F⁻, pH 8). A decrease in corrosion resistance and less protective passive oxide films are observed for all titanium alloys in fluoridated acidified saliva (9.8 g l⁻¹ lactic acid, 1.0 g l⁻¹ F⁻, pH 2.5) in regard to other electrochemical media used within this work. It is worthy of note that the most important decrease was found for Ti–6Al–7Nb alloy. These conclusions are confirmed by all the electrochemical tests undertaken. However, the results confirm that the corrosion resistance of the studied Ti–Ta alloys in all saliva is better or similar to that of Ti–6Al–7Nb alloy, suggesting that the Ti–Ta alloys have potential for dental applications.     

Properties of titanium-silver alloys for dental application

The purpose of this study was to develop titanium-silver alloys with biocompatibility, high corrosion resistance, and low ion-release rate, and to evaluate the electrochemical properties of titanium-silver alloys in artificial saliva. Titanium-silver alloys with silver contents ranging from 0 to 4.5 at % in steps of 0.5 at % were designed. The alloys were arc melted, homogenized at 950 degrees C for 72 h, hot rolled to 2 mm in thickness, and finally solution heat treated at 950 degrees C for 1 h and quenched in water. Chemical compositions, phases, hardnesses, electrochemical properties, and the cytotoxicity of the alloys were investigated. The purity of titanium-silver alloys was maintained above 99.9%, because few impurities were introduced through their manufacture. In the case of alloys containing silver in the range 2.0-4.0 at %, the formation of an acicular alpha phase was observed inside the beta phase. The acicular phase got thinner with increasing amounts of silver. This means that silver is a beta-phase stabilizing element in titanium-silver alloys. The hardness value tended to rise with increasing silver content and increased largely over 3.5 at %, and the increase of the hardness value versus pure titanium was about 33%. It is believed that the substantial increases in hardness was due to the effects of solid solution strengthening and of alpha-beta phase transition. Moreover, titanium-silver alloys had higher corrosion resistances than pure titanium. These results mean that silver additions to titanium can improve alloy corrosion resistance. Passive current densities in the potentiodynamic polarization curves were dependent on the chemical compositions of the titanium-silver alloys. However, they did not show a linear relationship with respect to silver contents. Titanium-silver alloys did not show pitting corrosion in artificial saliva. It is believed that silver addition to titanium strengthened the passive film due to titanium dissolution induced by the different electromotive forces of titanium and silver. In the agar overlay test, the cytotoxicity of the titanium-silver alloys and of titanium were none or mild. In summary, titanium-silver alloys had higher mechanical properties and corrosion resistance than titanium, and toxicities that were similar to titanium. Therefore, it is recommended that titanium-silver alloys be adopted cautiously by the biomedical and dental fields.     

Magnesium alloys: predicting in vivo corrosion with in vitro immersion testing

Magnesium (Mg) and its alloys have been proposed as degradable replacements to commonly used orthopedic biomaterials such as titanium alloys and stainless steel. However, the corrosion of Mg in a physiological environment remains a difficult characteristic to accurately assess with in vitro methods. The aim of this study was to identify a simple in vitro immersion test that could provide corrosion rates similar to those observed in vivo. Pure Mg and five alloys (AZ31, Mg-0.8Ca, Mg-1Zn, Mg-1Mn, Mg-1.34Ca-3Zn) were immersed in either Earle's balanced salt solution (EBSS), minimum essential medium (MEM), or MEM-containing 40 g/L bovine serum albumin (MEMp) for 7, 14, or 21 days before removal and assessment of corrosion by weight loss. This in vitro data was compared to in vivo corrosion rates of the same materials implanted in a subcutaneous environment in Lewis rats for equivalent time points. The results suggested that, for the alloys investigated, the EBSS buffered with sodium bicarbonate provides a rate of degradation comparable to those observed in vivo. In contrast, the addition of components such as (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) (HEPES), vitamins, amino acids, and albumin significantly increased corrosion rates. Based on these findings, it is proposed that with this in vitro protocol, immersion of Mg alloys in EBSS can be used as a predictor of in vivo corrosion.     

Research on an Mg–Zn alloy as a degradable biomaterial

In this study a binary Mg–Zn magnesium alloy was researched as a degradable biomedical material. An Mg–Zn alloy fabricated with high-purity raw materials and using a clean melting process had very low levels of impurities. After solid solution treatment and hot working the grain size of the Mg–Zn alloy was finer and a uniform single phase was gained. The mechanical properties of this Mg–Zn alloy were suitable for implant applications, i.e. the tensile strength and elongation achieved were ～279.5 MPa and 18.8%, respectively.The results of in vitro degradation experiments including electrochemical measurements and immersion tests revealed that the zinc could elevate the corrosion potential of Mg in simulated body fluid (SBF) and reduce the degradation rate. The corrosion products on the surface of Mg–Zn were hydroxyapatite (HA) and other Mg/Ca phosphates in SBF. In addition, the influence caused by in vitro degradation on mechanical properties was studied, and the results showed that the bending strength of Mg–Zn alloy dropped sharply in the earlier stage of degradation, while smoothly during the later period.The in vitro cytotoxicity of Mg–Zn was examined. The result 0–1 grade revealed that the Mg–Zn alloy was harmless to L-929 cells. For in vivo experiments, Mg–Zn rods were implanted into the femoral shaft of rabbits. The radiographs illustrated that the magnesium alloy could be gradually absorbed in vivo at about 2.32 mm/yr degradation rate obtained by weight loss method. Hematoxylin and eosin (HE) stained section around Mg–Zn rods suggested that there were newly formed bone surrounding the implant.HE stained tissue (containing heart, liver, kidney and spleen tissues) and the biochemical measurements, including serum magnesium, serum creatinine (CREA), blood urea nitrogen (BUN), glutamic-pyruvic transaminase (GPT) and creatine kinase (CK) proved that the in vivo degradation of Mg–Zn did not harm the important organs. Moreover, no adverse effects of hydrogen generated by degradation had been observed and also no negative effects caused by the release of zinc were detected. These results suggested that the novel Mg–Zn binary alloy had good biocompatibility in vivo.     

Heterogeneity in the B1 (CD20) cell surface molecule expressed by human B-lymphocytes

The B1 molecule (CD20) is a phosphoprotein expressed only by B-lymphocytes. In this study. analysis of B1 immunoprecipitated from surface iodinated B-cell lines and B-lymphocytes has shown that there are several expressed forms of Bl. A predominant species of M_r 33,000 represents 75–80% of the iodinated cell surface B1 and a M_r 35,000 species represents 20–25%. Limited proteinase digestion of these two species generated similar peptide maps demonstrating that the different forms of B1 shared common peptides. Biosynthetic labeling with [³⁵S]methionine revealed that the M_r 35,000 B1 species may actually represent two bands of M_r 34,500 and 36,000. Endoglycosidase digestion studies and metabolic labeling in the presence of tunicamycin indicated that neither the M_r 33,000 or 34,500–36,000 forms of B1 were glycosylated. The M_r 33,000 and 34,500–36,000 forms of B1 were constitutively phosphorylated in B-cell lines. However, exposure of B-cells to PMA resulted in a significant increase in the phosphorylation of the M_r 34,500–36,000 form. Exposure to PMA also resulted in an increase in the amount of M_r 34,500–36,000 protein immunoprecipitated from ³⁵S labeled cells. These results suggest that there are multiple forms of the B1 molecule expressed by B-lymphocytes and that this heterogeneity may result from phosphorylation of the B1 protein.     

Effect of nickel addition on microstructure and properties of Ti-Co-Ni alloys

The focus of this study was placed on the effect of nickel addition (5 wt%) on the microstructure, castability, biocorrosion resistance and some other properties of a series of cast high-cobalt (up to 25 wt%) Ti-Co-Ni alloys. Results indicated that melting temperatures of the present alloys were much lower than the melting temperature of pure titanium. Addition of 5 wt% Ni to replace an equivalent amount of Co slightly lowered the eutectoid and melting temperatures. Castability of the alloys was enhanced by the high alloy content and higher mould temperature. Substitution of 5 wt% Ni for Co increased the castability values. The phase transformation of β-Ti to -Ti was enhanced by nickel addition and higher mould temperature. Microhardness of the alloys increased with cobalt content and decreased with mould temperature. The addition of nickel lowered the hardness of the alloys. Breakdown potentials of the alloys were all higher than 900 mV and the critical anodic current densities were all lower than 8 μA cm⁻².     

Strengthening mechanisms in Ti-Nb-Zr-Ta and Ti-Mo-Zr-Fe orthopaedic alloys

The microstructural evolution and attendant strengthening mechanisms in two novel orthopaedic alloy systems, Ti-Nb-Zr-Ta and Ti-Mo-Zr-Fe, have been compared and contrasted in this paper. Specifically, the alloy compositions considered are Ti-34Nb-9Zr-8Ta and Ti-13Mo-7Zr-3Fe. In the homogenized condition, both alloys exhibited a microstructure consisting primarily of a beta matrix with grain boundary alpha precipitates and a low-volume fraction of intra-granular alpha precipitates. On ageing the homogenized alloys at 600 degrees C for 4 hr, both alloys exhibited the precipitation of refined scale secondary alpha precipitates homogeneously in the beta matrix. However, while the hardness of the Ti-Mo-Zr-Fe alloy marginally increased, that of the Ti-Nb-Zr-Ta alloy decreased substantially as a result of the ageing treatment. In order to understand this difference in the mechanical properties after ageing, TEM studies have been carried out on both alloys prior to and post the ageing treatment. The results indicate the existence of a metastable B2 ordering in the Ti-Nb-Zr-Ta alloy in the homogenized condition which is destroyed by the ageing treatment, consequently leading to a decrease in the hardness.     

Correlation of electrocorticographic to clinical seizure onset and interhemispheric propagation times in temporal lobe epilepsy

This study was performed to test the hypothesis that, in human temporal lobe epilepsy, electrocorticographic time factors involved in the ictal EEG to clinical ictal transition (electrocorticographic to clinical seizure onset time, ECOT) and the interhemispheric propagation of epileptic activity (interhemispheric propagation time, IHPT), which are independently correlated with temporal lobe epileptogenicity and predictive of seizure-free outcome following temporal lobectomy, are correlated with one another in a quantitative fashion. A series of 37 patients with medically intractable temporal lobe seizures was studied with long-term subdural videoelectroencephalographic monitoring. Temporal lobe seizure interhemispheric propagation time (IHPT) was found to be a negative, exponential function of electrocorticographic to clinical seizure onset time (ECOT) (f(x) = 8.201 × 10^−0.016x, r = 0.347, d.f. = 35, t = 2.19, p < 0.05, where f(x) = IHPT and x = ECOT). A small increase in ECOT was associated with a substantial decrease in IHPT and vice versa. The results suggest the electrophysiological time factor, ECOT, involved in the transition from ictal EEG seizure onset to clinical seizure onset, may determine the speed of interhemispheric propagation of established epileptic activity. The results suggest the interesting hypothesis that, in human temporal lobe epilepsy and, perhaps, under non-pathological circumstances, the human temporal lobe might possess a “time-labeling” function amenable to quantitative analysis.     

Microstructure,mechanical and corrosion properties of Mg–Dy–Gd–Zr alloys for medical applications

In previous investigations, a Mg–10Dy (wt.%) alloy with a good combination of corrosion resistance and cytocompatibility showed great potential for use as a biodegradable implant material. However, the mechanical properties of Mg–10Dy alloy are not satisfactory. In order to allow the tailoring of mechanical properties required for various medical applications, four Mg–10(Dy + Gd)–0.2Zr (wt.%) alloys were investigated with respect to microstructure, mechanical and corrosion properties. With the increase in Gd content, the number of second-phase particles increased in the as-cast alloys, and the age-hardening response increased at 200 °C. The yield strength increased, while the ductility reduced, especially for peak-aged alloys with the addition of Gd. Additionally, with increasing Gd content, the corrosion rate increased in the as-cast condition owing to the galvanic effect, but all the alloys had a similar corrosion rate (～0.5 mm year^?1) in solution-treated and aged condition.     

Evidence for a Local Action of Growth Hormone in Embryonic Tooth Development in the Rat

Abstract

Studies in non-dental embryonic tissues have suggested that an interaction between growth hormone and its receptor may play a role in growth and development before the foetal pituitary gland is competent. This study reports the distribution of growth hormone, its rezceptor and binding protein in developing rat tooth germs from embryonic day 17 to 21 and postnatal day 0 using antibodies specific for each of these proteins. Four foetal rats were processed at each time point (E17, EM, E20/21 and postnatal day 0). Following routine fixation and paraffin embedding, sections were treated with antisera to rat growth hormone, rat growth hormone binding protein and growth hormone receptor. Localization of antibody/antigen complexes was subsequently visualized by addition of biotinylated IgG and reaction with streptavidin peroxidase and diaminobenzidine. Assessment of the level of staining was qualitative and based on a subjective rankings ranging from equivocal to very strong staining. Overall, growth hormone and its binding protein were located both in the cellular elements and throughout the extracellular matrix, whereas the growth hormone receptor showed an exclusively intra-cellular location. All three proteins were detectable in cells of the dental epithelium and mesenchyme at the primordial bud stage (E17) which occurs prior to expression of pituitary growth hormone. At the cap stage of odontogenesis (E18-19), numerous cells in both the dental epithelium and mesenchyme were intensely immunoreactive for growth hormone, its binding protein and receptor. In the succeeding early bell stage (E20-21), most of the mesenchymal cells in the dental pulp were mildly positive for these proteins, while the dental epithelium and adjacent mesenchyme were more immunoreactive. At the late bell stage (postnatal day 0), all three proteins were localized in dental epithelium, differentiating mesenchymal cells the cuspal surface facing the epithelial-mesenchymal interface, preodontoblasts, and odontoblasts forming dentine. From these observations, immunoreactive growth hormone, its receptor and binding protein appear to be expressed in odontogenic cells undergoing histodiierentiation, morphodifferentiation and dentinogenesis in a cell-type and stage-specific pattern throughout embryonic tooth development. This suggests the possibility that growth hormone, or a growth hormone-like protein, plays a paracrindautocrine role in tooth development in utero.     

反复熔铸影响新旧钴铬烤瓷合金的机械性能

背景：目前关于反复铸造后钴铬烤瓷合金机械性能改变的研究已有较多研究报道,而对于将回收旧料再利用于新料中后再铸造钴铬烤瓷合金机械性能的研究则少有报道。 目的：研究反复熔铸对不同比例新旧钴铬烤瓷合金拉伸强度、屈服强度、延伸率及显微硬度等机械性能的影响。 方法：由新钴铬烤瓷合金熔铸成Ⅰ代铸件,40%Ⅰ代废旧料添加60%新钴铬烤瓷合金熔铸成Ⅱ代铸件,40%Ⅱ代废旧料添加60%新钴铬烤瓷合金熔铸成Ⅲ代铸件,40%Ⅲ代废旧料添加60%新钴铬烤瓷合金熔铸成第Ⅳ代铸件。采用拉伸实验测试各代试件的拉伸强度、0.2%屈服强度、延伸率;采用弯曲实验测试各代试件的弯曲强度;采用硬度实验测试各代试件的维氏硬度值;并进行显微金相观察。 结果与结论：Ⅱ,Ⅲ,Ⅳ代铸件拉伸强度、0.2%屈服强度、延伸率、弯曲强度及维氏硬度值与Ⅰ代铸件比较,差异均无显著性意义。Ⅰ代试样晶粒的大小均匀一致,直径较小,沿晶界分布的碳化物大小也较均匀细小,主要呈球形和不规则的蠕虫状两种形态;Ⅱ代和Ⅲ代试样组织形态尚均匀,只是晶粒有些粗化;Ⅳ代试样显微组织中的碳化物开始粗化,不规则蠕虫状的碳化物含量增多,可发现晶粒内存在少量非金属夹杂物。表明新旧比例为3∶2的钴铬烤瓷合金至少可以反复熔铸3次而不引起机械性能下降。     

Magnetic susceptibility and hardness of Au–xPt–yNb alloys for biomedical applications

Metal devices in the human body induce serious metal artifacts in magnetic resonance imaging (MRI). Metals artifacts are mainly caused by a volume magnetic susceptibility (χ_v) mismatch between a metal device and human tissue. In this research, Au–xPt–yNb alloys were developed for fabricating MRI artifact-free biomedical metal devices. The magnetic properties, hardness and phase constitutions of these alloys were investigated. The Au–xPt–8Nb alloys showed satisfactory χ_v values. Heat treatments did not clearly change the χ_v values for Au–xPt–8Nb alloys. The Vickers hardness (HV) of these two alloys was much higher than that of high-Pt alloys; moreover, aging at 700 °C increased the HV values of these two alloys. A dual phase structure consisting of face-centered cubic α1 and α2 phases was observed and aging at 700 °C promoted phase separation. The Au–5Pt–8Nb and Au–10Pt–8Nb alloys showed satisfactory χ_v values and high hardness and are thus suggested as candidates for MRI artifact-free alloys for biomedical applications.     

Quantitation of C-reactive protein in cerebrospinal fluid and serum by zone immunoelectrophoresis assay (ZIA)

The zone immunoelectrophoresis assay (ZIA) for C-reactive protein (CRP) determinations is easy to perform and requires only small amount of antiserum, e.g., 25–100 and 0.5–1.0 μ1 anti-CRP antibody/20 serum and CSF samples, respectively. For quantitating CSF-CRP the immunoprecipitates formed were stained using lakaline phosphatase-conjugated secondary antibodies and the lowest standard concentration used was 30 μg/1. The immunoprecipitates formed when measuring CRP in serum were stained by Coomasie brilliant blue R250 with a detection limit of about 300 μg/l.

CRP was determined in cerebrospinal fluid in 27 patients with bacterial meningitis (range <0.03–0.23 mg/l) and in 25 patients with viral meningitis (range <0.03–0.23 mg/l).

CRP was quantitated in 52 sera by both the CRP ZIA method (y) and by electroimmunoassay (x). The correlation coefficient was r = 0.992 with the regression line y = 1.024 x + 0.855.