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Results for “Base Composition”

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At least 577 records · Page 32Linked to original sources
PubMed2002

Biocompatibility studies on biodegradable polyester-based composites of human osteoblasts: a preliminary screening.

A series of biodegradable composites with natural hydroxyapatite, designed for possible use in orthopedics applications, were preliminarily screened for biocompatibility by employing primary cultures of human osteoblasts in a direct contact method. The cells were seeded at low density onto the materials under investigation and allowed to grow for 2 weeks. They then were analyzed for morphology, proliferation, viability, alkaline phosphatase activity (AP), osteocalcin (OC) production, and extracellular matrix mineralization. The results showed that all materials have good biocompatibility. Cell viability tests demonstrated that in all cases the values were comparable to the control, and the addition of hydroxyapatite always resulted in an enhancement of performance with respect to the plain polymer. AP and OC analysis confirmed that all composites allowed the expression of phenotypic markers. Scanning electron microscopy provided direct evidence of intense cell adhesion and proliferation on the tested materials.

Biocompatible Materials↗
PubMed1984

Fatty acid and long-chain base composition of gangliosides isolated from adult human brain.

A series of major and minor ganglioside species were isolated from a single human adult brain and analyzed for their lipophilic composition. Hematosides, GM3 and GD3, each showing double bands on thin-layer chromatograms, were separated into the upper band and lower band fractions to be analyzed for the heterogeneity of their ceramide moieties. The upper band fractions of GM3 and GD3 were found to contain relatively high amounts of longer-chain fatty acids (C20-C26), whereas the lower band fractions contained high amounts of shorter-chain fatty acids (C16-C18). Compared to other gangliosides which contain hexosamine, the two hematosides contained a smaller proportion of stearic acid. The proportion of 4-eicosasphingenine was found to increase with increasing sialic acid content in gangliosides. These findings suggest that, in the biosynthesis of various gangliosides, N-acetylhexosamine is preferentially transferred to hematosides rich in stearic acid, and sialic acid residues are preferentially transferred to 4-eicosasphingenine-containing species.

Brain Chemistry↗
PubMed2001

Secondary ion mass spectrometric investigation of Au-based composites.

The electrodeposition of thick gold layers plays an important role both in traditional and high-tech productions, such as jewelry and microelectronics, respectively. In this work a secondary ion mass spectrometric study will be presented on Au co-deposits with (sub-)micrometric ceramic powders, in order to harden gold. Mass spectra are used to identify the components deposited, providing evidence of the additives and/or eventual contaminants introduced during electrolysis. Furthermore, analysis of ion depth profiles and the intensity distribution of ionic species along the film were studied.

Journal Article↗
PubMed1996

A tissue composition-based algorithm for predicting tissue:air partition coefficients of organic chemicals.

The objectives of the present study were (i) to develop an algorithm for predicting the tissue:air partition coefficients (PCs) of volatile organic chemicals (VOCs) and (ii) to apply this algorithm to predict the rat tissue:air PCs of 45 VOCs. The approach consisted of estimating the tissue:air PCs by dividing the tissue solubility of chemicals by their saturable vapor concentrations. The tissue solubility of chemicals was calculated as the sum total of their solubility in neutral lipid, phospholipid, and water fractions of tissues. The rat liver:air, muscle:air, and adipose tissue:air PCs predicted using this algorithm compared well with literature data available for several ketones, alcohols, acetate esters, alkanes, haloalkanes, aromatic hydrocarbons, and diethyl ether. The average ratios between the predicted and experimental values of the tissue:air PC values were 0.94 (liver), 0.93 (muscle), and 1.10 (adipose tissue). The mechanistic algorithm developed in the present study should be useful for predicting tissue:air PCs of VOCs and for verifying the current default assumption of considering tissue:air PCs to be species-invariant.

Adipose Tissue↗
PubMed1979

Deoxyribonucleic acid base composition and taxonomy in the genus Geotrichum Link.

The molar percentage of guanine + cytosine (% GC) in the DNA from 25 yeast-like fungi related to the genus Geotrichum has been measured. This criterion together with the biochemical characteristics allow the division of the species into 3 groups: one group resembling G. candidum (% GC: 31.5--42) and containing 8 imperfect and 6 perfect forms. In this group only G. capitatum has a lower % GC (31.5). A second group of 6 species resembling the genus Trichosporon (57--60%) and a third intermediate category of 4 species (42--53.5%) were observed. The GC-values correlate well with biochemical characters, e.g. the presence of urease, the number of organic substrates assimilated, and also with the presence of characters typical of the Ascomycetes or the Basidiomycetes.

Cytosine↗