Functional Hydrogels With Tunable Structures and Properties for Tissue Engineering Applications

Tissue engineering (TE) has been used as an attractive and efficient process to restore the original tissue structures and functions through the combination of biodegradable scaffolds, seeded cells, and biological factors. As a unique type of scaffolds, hydrogels have been frequently used for TE because of their similar 3D structures to the native extracellular matrix (ECM), as well as their tunable biochemical and biophysical properties to control cell functions such as cell adhesion, migration, proliferation, and differentiation. Various types of hydrogels have been prepared from naturally derived biomaterials, synthetic polymers, or their combination, showing their promise in TE. This review summarizes the very recent progress of hydrogels used for TE applications. The strategies for tuning biophysical and biochemical properties, and structures of hydrogels are first introduced. Their influences on cell functions and promotive effects on tissue regeneration are then highlighted.

Some Properties of Fresh and Ripened Traditional Akcakatik Cheese

Akcakatik cheese (yogurt cheese) is produced by drying strained yogurt with or without adding cloves or black cumin. The main objective of this study was to detect the properties of both fresh and ripened Akcakatik cheeses and to compare them. For this purpose the biogenic amine content, volatile flavor compounds, protein degradation level, chemical properties and some microbiological properties of 15 Akcakatik cheese samples were investigated. Titratable acidity, total dry matter, NaCl, total nitrogen, water soluble nitrogen, ripened index, histamine, diacetyl and acetaldehyde levels were found to be higher in ripened cheese samples than in fresh cheese samples. On the other hand, the clove and black cumin ratios were found to be higher in the fresh cheese samples. Sodium dodecyl sulphate polyacrylamide gel electropherograms of cheese samples showed that protein degradation was higher in ripened cheese samples than in fresh samples, as expected. The dominant Lactic acid bacteria (LAB) flora of Akcakatik cheese samples were found to be Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus.

Influence of steeping duration, drying temperature, and duration on the chemical composition of sorghum starch

The quest for high-quality starch that would meet the needs of manufacturers is ever increasing. This study investigated the effect of steeping duration, drying temperature, and duration on the chemical properties of sorghum starch, to possibly alter the characteristics of sorghum starch for food applications. Steeping duration, drying temperature, and drying time of starch isolation were optimized using a central composite design and nine parameters including pH, amylose content, moisture, protein, ash, crude fiber, fat, carbohydrate, and total energy determined. Results obtained showed that most of the parameters were majorly influenced by steeping and drying duration. Steeping duration significantly (p < .05) increased the moisture, protein, and ash content of the sorghum with a corresponding decrease in pH values. The obtained experimental and predicted values of the investigated parameters were similar, with statistical indices indicating the relative validity of the generated models [absolute average deviation (AAD between 0 and 0.20), bias factor (B_f , 1-1.02), and accuracy factor (A_f , 1-1.21)]. The varying values of the parameters obtained indicates the potential use of the sorghum starches as thickeners, starch substitutes, and for other desired roles in food processing.

Reducing the Amount of Catalyst in TEMPO-Oxidized Cellulose Nanofibers: Effect on Properties and Cost

Cellulose nanofibers (CNF) are interesting biopolymers that find numerous applications in different scientific and technological fields. However, manufacturing costs are still one of the main drawbacks for the industrial production of highly fibrillated, transparent CNF suspensions. In the present study, cellulose nanofibers were produced from bleached eucalyptus pulp via TEMPO-mediated oxidation with varying amounts of NaClO and passed through a high-pressure homogenizer. The CNFs were chemically and physically characterized; cellulose nanopapers were also produced to study tensile properties. Production costs were also calculated. Results indicated that CNF properties are strongly dependent on the carboxyl content. Manufacturing costs showed that chemicals, in particular TEMPO catalyst, represent a large part of the final cost of CNFs. In order to solve this problem, a set of samples were prepared where the amount of TEMPO was gradually reduced. Characterization of samples prepared in this way showed that not only were the costs reduced, but also that the final properties of the CNFs were not significantly affected when the amount of TEMPO was reduced to half.

Molecular Connectivity Predefines Polypharmacology: Aliphatic Rings, Chirality, and sp3 Centers Enhance Target Selectivity

Dark chemical matter compounds are small molecules that have been recently identified as highly potent and selective hits. For this reason, they constitute a promising class of possible candidates in the process of drug discovery and raise the interest of the scientific community. To this purpose, Wassermann et al. (2015) have described the application of 2D descriptors to characterize dark chemical matter. However, their definition was based on the number of reported positive assays rather than the number of known targets. As there might be multiple assays for one single target, the number of assays does not fully describe target selectivity. Here, we propose an alternative classification of active molecules that is based on the number of known targets. We cluster molecules in four classes: black, gray, and white compounds are active on one, two to four, and more than four targets respectively, whilst inactive compounds are found to be inactive in the considered assays. In this study, black and inactive compounds are found to have not only higher solubility, but also a higher number of chiral centers, sp3 carbon atoms and aliphatic rings. On the contrary, white compounds contain a higher number of double bonds and fused aromatic rings. Therefore, the design of a screening compound library should consider these molecular properties in order to achieve target selectivity or polypharmacology. Furthermore, analysis of four main target classes (GPCRs, kinases, proteases, and ion channels) shows that GPCR ligands are more selective than the other classes, as the number of black compounds is higher in this target superfamily. On the other side, ligands that hit kinases, proteases, and ion channels bind to GPCRs more likely than to other target classes. Consequently, depending on the target protein family, appropriate screening libraries can be designed in order to minimize the likelihood of unwanted side effects early in the drug discovery process. Additionally, synergistic effects may be obtained by library design toward polypharmacology.

Emulsifying Properties of Oxidatively Stressed Myofibrillar Protein Emulsion Gels Prepared with (-)-Epigallocatechin-3-gallate and NaCl

The dose-dependent effects of (-)-epigallocatechin-3-gallate (EGCG; 0, 100, or 1000 ppm) on the textural properties and stability of a myofibrillar protein (MP) emulsion gel were investigated. Addition of EGCG significantly inhibited formation of carbonyl but promoted the loss of both thiol and free amine groups. Addition of EGCG, particularly at 1000 ppm, initiated irreversible protein modifications, as evidenced by surface hydrophobicity changes, patterns in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and differential scanning calorimetry. These results indicated that MP was modified by additive reactions between the quinone of EGCG and thiols and free amines of proteins. These adducts increased cooking loss and destabilized the texture, especially with a large EGCG dose. Confocal laser scanning microscopy and scanning electron microscopy images clearly indicated the damage to the emulsifying properties and the collapse of the internal structure when the MP emulsion gel was treated with a large EGCG dose. A high concentration of NaCl (0.6 M) improved modification of MP and increased the rate of deterioration of the internal structure, especially with the large EGCG dose (1000 ppm), resulting in an MP emulsion gel with extremely unstable emulsifying properties.

Protein Characteristics that Affect the Quality of Vital Wheat Gluten to be Used in Baking: A Review

The use of vital wheat gluten in the baking industry and wheat flour mills aims to improve the rheological characteristics of flour considered unsuitable to obtain products such as sliced bread, French bread, high-fiber breads, and other products that require strong flours. To improve characteristics such as flour strength, dough mixing tolerance, and bread volume, vital wheat gluten is added to flour at levels that can vary from 2% to 10% (flour basis), with 5% being a commonly used dosage. However, the vital wheat gluten commercialized in the market has few quality specifications, especially related to the characteristics of the proteins that constitute it and are responsible for the formation of the viscoelastic gluten network. Information on protein quality is important, because variations are observed in the technological quality of vital wheat gluten obtained from different sources, which could be associated to damage caused to proteins during the obtainment process. Several tests, either physical-chemical analyses, or rheological tests, are carried out to establish gluten quality; however, they are sometimes time-consuming and costly. Although these tests give good answers to specify gluten quality, flour mills, and the baking industries require fast and simple tests to evaluate the uses and/or dosage of vital gluten addition to wheat flour. This review covers the concepts, uses, obtainment processes, and quality analysis of vital wheat gluten, as well as simple tests to help identify details about protein quality of commercial vital wheat gluten.

Physicochemical Property Variation in Spider Silk: Ecology, Evolution, and Synthetic Production

The unique combination of great stiffness, strength, and extensibility makes spider major ampullate (MA) silk desirable for various biomimetic and synthetic applications. Intensive research on the genetics, biochemistry, and biomechanics of this material has facilitated a thorough understanding of its properties at various levels. Nevertheless, methods such as cloning, recombination, and electrospinning have not successfully produced materials with properties as impressive as those of spider silk. It is nevertheless becoming clear that silk properties are a consequence of whole-organism interactions with the environment in addition to genetic expression, gland biochemistry, and spinning processes. Here we assimilate the research done and assess the techniques used to determine distinct forms of spider silk chemical and physical property variability. We suggest that more research should focus on testing hypotheses that explain spider silk property variations in ecological and evolutionary contexts.

Seed germination and biochemical profile of Silybum marianum exposed to monometallic and bimetallic alloy nanoparticles

In recent years nanotechnology has become increasingly important in almost every field. The new and improved physical, chemical and biological properties of material at nanoscale have far reaching implications in the fields of science and technology. Nanoparticles' effect on various plant species must be investigated to develop a comprehensive toxicity profile for nanoparticles. The current study strives to evaluate the effects of nine types of metal nanoparticles including monometallic and bimetallic alloy nanoparticles [Ag, Au, Cu, AgCu (1:3), AgCu (3:1), AuCu (1:3), AuCu (3:1), AgAu (1:3), AgAu (3:1)] on seed germination, root and shoot growth and biochemical profile of Silybum marianum plant. Seed germination was greatly affected and increased significantly upon treatment with nanoparticles' suspensions and was recorded highest for Ag nanoparticle suspension. Metal nanoparticles also had a significant effect on the biochemical profile of S. marianum. For the first week, the effect on DPPH, total phenolics content, total flavonoids content, total protein content, peroxidase activity and superoxide dismutase activity was enhanced, but declined as the time progressed. Among the nanoparticles being used, the effect of Ag nanoparticle was mostly enhancing. The results obtained are significant in mapping the effects of different monometallic and bimetallic nanoparticles on medicinal plant species.

Loss of stability and hydrophobicity of presenilin 1 mutations causing Alzheimer's disease

Nearly 200 mutations in the gene coding for presenilin 1 (PSEN1) cause early-onset Alzheimer's disease, yet the molecular mechanism remains obscure. As a meta-analysis, we compiled available clinical and biochemical data for PSEN1 variants and correlated these to chemical properties of the mutants. We found statistically significant relationships between relative Aβ42 levels and clinical age of onset. We then computed chemical properties of the mutants from a variety of computational chemistry tools. Relative Aβ42 levels correlated significantly (95% confidence or more from p-values of linear regression) with loss of hydrophobicity for four different regression analyses (squared correlation coefficient of linear regression R(2) of 0.41-0.53) and with increased polarity (R(2) = 0.47, 0.59) and loss of protein stability (R(2) = 0.39, 0.63) for two independent data sets. Age of onset of patients carrying PSEN1 variants correlated with increased polarity (R(2) = 0.49, 0.40) and loss of stability (R(2) = 0.75, 0.44) of the protein for both data sets. These relations suggest that mutants impair the membrane-associated structural integrity of presenilin by reducing hydrophobic membrane association and overall protein stability. This explains why the many mutations that spread out across the protein and far from the catalytic aspartates can cause disease. The identified molecular determinants of clinical age of symptom onset may be relevant to future presenilin-modulating therapies specifically directed towards increasing the structural integrity and packing of the protein. Close to 200 mutations in presenilin 1 (PSEN1) cause Alzheimer's disease, but the biochemical relating these to disease remains debated. The chemical properties of PSEN1 variants were computed and correlated against clinical age of symptom onset. Loss of stability and hydrophobicity and gain of polarity relate to disease onset, suggesting that mutants impair the membrane structure of PSEN1 and that therapies should increase PSEN1 structural integrity.

Caseinate-gelatin and caseinate-hydrolyzed gelatin composites formed via transglutaminase: chemical and functional properties

BACKGROUND

Treatment of food proteins by enzymatic crosslinking and other reactions can confer modified properties on the treated proteins. Bovine gelatin and hydrolyzed bovine gelatin were used to generate two caseinate-based composites via transglutaminase, and potential useful properties to food processing were investigated for both composites.

RESULTS

Caseinate-gelatin and caseinate-hydrolyzed gelatin composites contained 33.4 and 10.3 g kg(-1) protein of 4-hydroxyproline, respectively. Caseinate conjugation with gelatin and hydrolyzed gelatin resulted in two composites with stronger absorption at five wavenumbers during Fourier transform-infrared analysis, demonstrating that they were rich in hydroxyl and carboxyl groups. Both composites exhibited higher viscosity values in aqueous dispersions, lower thermal stability (i.e. higher mass loss) during thermogravimetric analysis and worse emulsifying properties than original caseinate, owing to conjugation and crosslinking via transglutaminase. However, confocal laser scanning microscopy (CLSM) analysis revealed that both composites actually had better emulsion stability after 2 weeks of storage.

CONCLUSION

The composites generated were different in chemical characteristics and better in viscosity and emulsion stability than original caseinate. They might have potential as protein thickeners and emulsifiers. CLSM is a better technique to assess emulsion stability of food proteins than the classic turbidity method.

Ammonia gas sensing behavior of tanninsulfonic acid doped polyaniline-TiO₂ composite

A highly active tannin doped polyaniline-TiO₂ composite ammonia gas sensor was developed and the mechanism behind the gas sensing activity was reported for the first time. A tanninsulfonic acid doped polyaniline (TANIPANI)-titanium dioxide nanocomposite was synthesized by an in situ polymerization of aniline in the presence of tanninsulfonic acid and titanium dioxide nanoparticles. X-ray diffraction and thermogravimetric analysis were utilized to determine the incorporation of TiO₂ in TANIPANI matrix. UV-Visible and infrared spectroscopy studies provided information about the electronic interactions among tannin, polyaniline, and TiO₂. Scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM) surface analysis techniques were used to investigate the metal oxide dispersions inside polyaniline matrix. Gas sensors were prepared by spin coating solutions of TANIPANI-TiO₂ and TANIPANI composites onto glass slides. Sensors were tested at three different concentrations (20 ppm, 40 ppm, and 60 ppm) of ammonia gas at ambient temperature conditions by measuring the changes in surface resistivity of the films with respect to time. Ammonia gas sensing plots are presented showing the response values, response times and recovery times. The TANIPANI-TiO₂ composite exhibited better response and shorter recovery times when compared to TANIPANI control and other polyaniline composites that have been reported in the literature. For the first time a proposed mechanism of gas sensing basing on the polaron band localization and its effects on the gas sensing behavior of polyaniline are reported.

Assessment of soil nitrogen and related enzymes as influenced by the incorporation time of field pea cultivated as a catch crop in Alfisol

The effect of the time of catch crop (field pea) incorporation [catch crop incorporated in the autumn (A) or in the spring (B) versus plots without a catch crop (C)] on the soil enzymes related to N transformation (urease - UR, protease - PRO, nitrate reductase - NR, arginine ammonification rate - AAR), the total N and mineral N as well as microbial biomass N (MBN) contents were investigated in a 3-year experiment. The catch crop was sown at the beginning of August and plowed in the autumn in 2008, 2009 and 2010 or left as mulch during the winter. Soil samples for microbial activity were taken from spring barley plots that were grown in 2009, 2010 and 2011 before sowing (March), during the tillering phase (May), shooting (June) and after the harvesting of spring barley (August). The use of catch crop significantly increased the soil mineral and MBN contents as well as the activities of PRO and NR as compared to the control soil. The spring incorporation of the field pea significantly increased the MBN content in contrast to the autumn application, while the activity of N-cycle enzymes were clearly unaffected (UR and AAR) regardless of the time of the incorporation of field pea or else the results were inconsistent (PRO and NR). When the catch crop was incorporated in the spring, a significantly higher content of mineral N as compared to autumn incorporation was noted on only two of the four sampling dates. The enzymatic activity (PRO and AAR) was about 1.3-2.8 times higher in May and June as compared with March and August. Both spring or autumn incorporation of catch crop can be a useful management practice to increase the soil mineral N content and enhance the soil biological activity.

Effect of bismuth oxide on white mineral trioxide aggregate: chemical characterization and physical properties

AIM

To assess the effect of bismuth oxide (Bi2 O3 ) on the chemical characterization and physical properties of White mineral trioxide aggregate (MTA) Angelus.

METHODOLOGY

Commercially available White MTA Angelus and White MTA Angelus without Bi2 O3 provided by the manufacturer especially for this study were subjected to the following tests: Rietveld X-ray diffraction analysis (XRD), energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), compressive strength, Vickers microhardness test and setting time. Chemical analysis data were reported descriptively, and physical properties were expressed as means and standard deviations. Data were analysed using Student's t-test and Mann-Whitney U test (P = 0.05).

RESULTS

Calcium silicate peaks were reduced in the diffractograms of both hydrated materials. Bismuth particles were found on the surface of White MTA Angelus, and a greater amount of particles characterized as calcium hydroxide was observed by visual examination on White MTA without Bi2 O3 . The material without Bi2 O3 had the shortest final setting time (38.33 min, P = 0.002), the highest Vickers microhardness mean value (72.35 MPa, P = 0.000) and similar compressive strength results (P = 0.329) when compared with the commercially available White MTA Angelus containing Bi2 O3 .

CONCLUSION

The lack of Bi2 O3 was associated with an increase in Vickers microhardness, a reduction in final setting time, absence of Bi2 O3 peaks in diffractograms, as well as a large amount of calcium and a morphology characteristic of calcium hydroxide in EDX/SEM analysis.

Chemical properties of a polysaccharide purified from solid-state fermentation of Auricularia auricular and its biological activity as a hypolipidemic agent

A water-soluble crude polysaccharide was extracted by hot water from Auricularia auricular mycelium grown under solid-state fermentation (SSF). The crude polysaccharide was purified by DEAE Sephadex A-50 and Sephadex G-200 chromatography. Fourier transform infrared spectroscopy and nuclear magnetic resonance ((1) H NMR) spectroscopy were used to investigate the structure of the purified A. auricular polysaccharide (AAP-I) and revealed that it is α-glycosidically linked. After 14 and 28 days of AAP-I orally administered, the AAP-I significantly decreased the levels of total cholesterol, triglyceride, and low-density lipoprotein cholesterol in mice in which hyperlipidemia had been induced by a high fat diet (P < 0.05). The results revealed that AAP-I from SSF of A. auricular mycelium possesses potent hypolipidemic properties. The polysaccharide may be useful as a functional food additive and a hypolipidemic agent.

Catalytic Activity of Biomorphic α-MoO(3) in the Degradation of Methyl Violet Dye

A network of fibers comprising orthorhombic molybdenum trioxide (α-MoO(3)) crystals were synthesized using paper as template via a biomorphic approach. The template was completely removed by annealing the sample at 600°C for 5 min. Monoclinic MoO(3) was formed and consequently converted into orthorhombic α-MoO(3) after prolonged annealing. Three milligrams of the biomorphic α-MoO(3) could degrade up to 90% of a methyl violet aqueous solution with a concentration of 20 mg/L under normal visible light. The size of the α-MoO(3) grains and the porosity of the biomorphic sample affected catalytic performance.

A comparison of fruit chemical characteristics of two wild grown Rubus species from different locations of Croatia

The main focus of our study was to investigate differences in nutritional (dry matter, soluble solids content, total acidity and pH value) and bioactive values (ascorbic acid, total anthocyanins, total phenols, and non-flavonoids content) of wild grown raspberry (Rubus idaeus) and blackberry (Rubus discolor) genotypes harvested from native populations in Croatia. The average total acidity ranged from 0.93 to 1.72% in R. discolor and 1.57 to 1.91% in R. idaeus. Ascorbic acid was found between 22.34 mg and 45.00 mg 100 g⁻¹ in R. idaeus, while it was between 30.64 mg and 33.09 mg 100 g⁻¹ in R. discolor genotypes. A great variability in total anthocyanins was detected in roatian wild blackberry and raspberry genotypes, ranging from 2,226 to 2,367 mg kg⁻¹ for blackberries and 279 to 582 mg kg⁻¹ for raspberries, indicating wild blackberries are particularly rich in anthocyanins. On the basis of these results, it can be concluded that investigated wild growing fruit species have a great potential in nutritive research, as well as in biodiversity research. It is necessary to carry out further investigation and evaluation of wild growing fruit species to utilize them in the most appropriate way, as well as conservation of interesting accessions in the gene banks.

Chemical properties of air pollutants and cause-specific hospital admissions among the elderly in Atlanta, Georgia

BACKGROUND

Health risks differ by fine particle (aerodynamic diameter ≤ 2.5 μm) component, although with substantial variability. Traditional methods to assess component-specific risks are limited, suggesting the need for alternative methods.

OBJECTIVES

We examined whether the odds of daily hospital admissions differ by pollutant chemical properties.

METHODS

We categorized pollutants by chemical properties and examined their impacts on the odds of daily hospital admissions among Medicare recipients > 64 years of age in counties in Atlanta, Georgia, for 1998-2006. We analyzed data in two stages. In the first stage we applied a case-crossover analysis to simultaneously estimate effects of 65 pollutants measured in the Aerosol Research and Inhalation Epidemiology Study on cause-specific hospital admissions, controlling for temperature and ozone. In the second stage, we regressed pollutant-specific slopes from the first stage on pollutant properties. We calculated uncertainty estimates using a bootstrap procedure. We repeated the two-stage analyses using coefficients from first-stage models that included single pollutants plus ozone and meteorological variables only. We based our primary analyses on exposures on day of admission.

RESULTS

We found that 24-hr transition metals and alkanes were associated with increased odds [0.26%; 95% confidence interval (CI), 0.02-0.48; and 0.37%; 95% CI, 0.04-0.72, respectively] of hospital admissions for cardiovascular disease (CVD). Transition metals were significantly associated with increased hospital admissions for ischemic heart disease, congestive heart failure, and atrial fibrillation. Increased respiratory-related hospital admissions were significantly associated with alkanes. Aromatics and microcrystalline oxides were significantly associated with decreased CVD- and respiratory-related hospital admissions.

CONCLUSIONS

The two-stage approach showed transition metals to be consistently associated with increased odds of CVD-related hospital admissions.

Glass formation, chemical properties and surface analysis of Cu-based bulk metallic glasses

This paper reviews the influence of alloying elements Mo, Nb, Ta and Ni on glass formation and corrosion resistance of Cu-based bulk metallic glasses (BMGs). In order to obtain basic knowledge for application to the industry, corrosion resistance of the Cu–Hf–Ti–(Mo, Nb, Ta, Ni) and Cu–Zr–Ag–Al–(Nb) bulk glassy alloy systems in various solutions are reported in this work. Moreover, X-ray photoelectron spectroscopy (XPS) analysis is performed to clarify the surface-related chemical characteristics of the alloy before and after immersion in the solutions; this has lead to a better understanding of the correlation between the surface composition and the corrosion resistance.

Quantitative changes in the biochemical composition of lignocellulosic residues during the vegetative growth of Lentinula edodes

The chemical changes in barley-straw (BS), wheat-straw (WS) and vineyard-pruning (VP) substrates were determined during colonization of Lentinula edodes mycelia (during primordium development) in solid state fermentation. Primordia appeared 39-50 days after inoculation. VP appeared to promote early sporophore initiation. The concentration of hemicellulose in BS and VP decreased gradually from 25.5% to 15.6% and from 15.8% to 12.3%, respectively. However in WS, hemicellulose decreased from 27.2% to 9.5%. Lignin broke down continuously in BS and WS, with 31.8% and 34.4% degradation, respectively; higher than that of cellulose. During the pinning stage, the C:N ratio decreased in VP and BS, but not in WS. On all substrates the phenols decreased notably throughout the first week of mycelial growth. The time elapsed (days) to pinning was positively correlated with cellulose content (r=0.89), total sugar (r=0.85) and inversely correlated to lignin (r=-1.00) and phenol content (r=-0.55).

Detailed characterization of a high-molecular-weight glycoprotein secreted by lung cancer cells

A cancer-associated, high-molecular-weight glycoprotein antigen (6B3.Ag) recognized by monoclonal antibody 6B3 was purified from culture medium of human large cell lung carcinoma cell line (HLC-2) and characterized biochemically and immunochemically. The 6B3.Ag was purified more than 1,200-fold with a yield of 30% by salting out, precipitation by acidification at pH 4.5, and chromatographies on Sepharose 4B and concanavalin A-Sepharose. The molecular weight of 6B3.Ag is approximately 1,000,000 and the molecule is a homodecamer of 94,000 subunits. The 6B3.Ag is a glycoprotein containing 22.9% sugars, consisting of both N- and O-glycoside chains. The N-terminal 19 amino acids were determined and only 4 out of 19 amino acid residues were different from those of an antigen, L3, secreted by lung carcinoma cell line Calu-1. The serum level of 6B3.Ag was determined in normal adults as well as patients with various diseases by enzyme-linked immunosorbent assay. The mean serum level of 6B3.Ag was 3.1 micrograms/ml, ranging from 1.6 to 6.2 micrograms/ml in 131 healthy adults. When the cut-off value was set at 6.2 micrograms/ml, the incidence of positive values in the sera was elevated not only in malignant diseases such as hepatoma (73%) and leukemia (62%), but also in benign diseases such as chronic hepatitis (42%) and liver cirrhosis (63%). While the incidence of positive values was elevated in advanced liver diseases, namely, chronic hepatitis, liver cirrhosis and hepatoma, the cancer specificity of 6B3.Ag did not appear to be high.