PubMed Health⌕ Search

Biomedical subjects

J F Guo

Publications and source records attributed to J F Guo.

9 recordsLinked to original sources
PubMed1991

The binding specificity of high and low molecular weight phosphomannosyl receptors from bovine testes. Inhibition studies with chemically synthesized 6-O-phosphorylated oligomannosides.

A series of chemically synthesized oligomannosides that contain mannose 6-phosphate residues were utilized as inhibitors of the binding of beta-galactosidase to high (CI-MPR, 215 kDa) and low (CD-MPR, 41-46 kDa) molecular mass mannose 6-phosphate receptor from bovine testes in order to probe the specificity of each receptor. Mannobioside phosphorylated in the terminal position and linked alpha(1,2) was a 6-fold better inhibitor than the corresponding alpha(1,3)- and alpha (1,6)-linked isomers. Inhibition observed with a monophosphorylated alpha(1,2)-linked mannotrioside was approximately 6-fold greater than that with the corresponding mannobioside. Penultimate glycosidic linkages of the oligomannosides played little or no role in the inhibition of binding of ligand to the receptors. Monophosphorylated oligomannosides containing phosphomonoester groups on penultimate mannose residues were not inhibitors. Binding inhibition observed for biantennary oligomannosides with phosphate on terminal mannose residues of either alpha(1,3) or alpha(1,6) chains closely approximated the values obtained with analogous trimannosides. A biantennary oligomannoside on which each antennary chain contained a terminal phosphate exhibited approximately an 8-fold greater inhibition than monophosphorylated compounds. Although the receptors exhibited similar relative specificities for phosphomonoesters, phosphodiesters did not inhibit binding of ligand to CD-MPR and only weakly inhibited binding to CI-MPR.

Animals↗
PubMed1990

Levels of cytochrome P-450-mediated aryl hydrocarbon hydroxylase (AHH) are higher in differentiated than in germinative cutaneous keratinocytes.

Induction of microsomal aryl hydrocarbon hydroxylase and cytochrome P-450 was observed in epidermal cells obtained from the skin of newborn rats exposed to benz(a)anthracene by topical exposure and in submerged cultures exposed to the procarcinogen in vitro. The level of aryl hydrocarbon hydroxylase activity was increased 2.5-fold in vivo and six- to sevenfold in vitro when the measurements were made on the entire epidermis or the entire culture, respectively. However, separate measurement on germinative (basal) and on differentiated cells revealed that AHH was sevenfold higher in differentiated cells as compared with basal cells in the skin of both unexposed animals and animals exposed in vivo. Similar results were obtained in cultured cells exposed in vitro. Immunocytochemical staining of sections of skin from animals exposed to benz(a)anthracene in vivo with a monoclonal antibody generated against cytochrome P-450c showed a higher binding of the antibody in lower spinous cells than in basal cells in the epidermis. Although more stained cells were observed in exposed cultures than in untreated cultures, the antibody, which inhibits at least 85% of the hydroxylase activity in the skin, inhibited only 6%-16% of the activity in culture. These observations support the interpretations that a) differentiated keratinocytes have a higher capacity in the metabolic activation of PAH than do germinative cells, although both types of cell are susceptible to induction of cytochrome P-450 by exposure to BA, and b) the cytochrome P-450 induced by exposure of epidermis to benz(a)anthracene in vivo exhibits some differences from the one induced upon exposure of keratinocytes to this procarcinogen in vitro.

Animals↗
PubMed1989

Bovine testicular beta-galactosidase: purification of enzyme fractions that exhibit high affinity for phosphomannosyl receptors.

An improved method is described for the preparation of bovine testicular beta-galactosidase that allows the isolation of enzyme fractions that bind avidly to phosphomannosyl receptors. The procedure permits removal of a contaminating beta-hexosaminidase and yields nearly homogeneous beta-galactosidase. Enzyme eluted from DEAE-Sephacel was arbitrarily divided into pools that exhibited differing ability to bind phosphomannosyl receptors. A high binding fraction was rapidly assimilated by cultured cells and bound to both low and high molecular weight phosphomannosyl receptors. Carbohydrate analysis of the high binding fraction indicates an average content of one complex and one high mannose oligosaccharide chain per molecule and an average mannose 6-phosphate content of two residues per molecule. However, electrofocusing studies indicated that all the fractions were heterogeneous with respect to sialic acid and phosphate content. The purification procedure also provides highly purified beta-galactosidase suitable for removing beta-galactosidase residues from a variety of complex carbohydrates.

Animals↗
PubMed1989

Culture and growth characteristics of chondrocytes encapsulated in alginate beads.

Methodology is described for the culture of avian and mammalian chondrocytes in ionotrophically gelled "semi-solid" and "hollow" alginate beads. Chondrocytes grown in "semi-solid" gels exhibited a spherical shape as opposed to a fibroblastic morphology observed in monolayer culture. In the "semi-solid" beads, the cells grew as small clumps and as large aggregates. The aggregates were round or elliptical in appearance and surrounded by a dense Alcian Blue positive halo. Preliminary studies with collagen and chitosan matrixes encapsulated in "hollow" beads suggest that cell growth and morphology are profoundly influenced by the composition of the cellular environment. Chondrocyte structure and function in the "semi-solid" and "hollow" beads were partially characterized by light microscopy, histochemical and biochemical means. The encapsulation methodology is readily applicable for the culture of chondrocytes in single beads, in multiwell dishes, or mass culture.

Alginates↗
PubMedDate not supplied

Morphology-based interpolation for 3D medical image reconstruction.

Interpolation is an important processing step in 3D reconstruction. A new method, based on mathematical morphology, is presented here to implement the interpolation by means of a combined operation of weighted dilation and erosion. Compared with previously proposed methods, the new approach successfully resolves the interpolation problem when there is no overlapping area between the two objects. In the mean time, it has a wide adaptability and is easy to implement.

Algorithms↗