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Biomedical subjects

R Song

Publications and source records attributed to R Song.

At least 91 records · Page 5Linked to original sources
PubMed1994

Phagocytic processing of exogenous particulate antigens by macrophages for presentation by class I MHC molecules.

Exogenous Ags that are processed in vacuolar endocytic compartments are generally presented by class II MHC molecules and not class I MHC (MHC-I) molecules, which conventionally present cytoplasmic or endogenous Ags. Accordingly, i.v. immunization of C57BL/6 mice with soluble OVA did not elicit a CD8 T cell response. However, i.v. immunization with OVA coupled to Latex particles (Latex-OVA) elicited an OVA-specific CD8 T cell response in vivo (particles from 59 to 2000 nm diameter were effective). In vitro, Latex-OVA was processed by H-2b macrophages and presented by Kb at least 100- to 1000-fold more efficiently than was soluble OVA. Inhibition of phagocytosis by cytochalasin D blocked the processing of Latex-OVA, whereas processing was not blocked by Brefeldin A. Latex-OVA was presented directly by H-2b macrophages or after "regurgitation" of processed OVA peptide from viable MHC-disparate macrophages for binding to surface Kb molecules on fixed H-2b macrophages. Peptide regurgitation was observed during processing of both Latex-OVA and Salmonella typhimurium 14028s that express an OVA fusion protein (Crl-OVA). However, the regurgitation pathway was less efficient than direct processing by viable H-2b macrophages. Thus, macrophages express an alternate pathway that allows MHC-I presentation of vacuolar exogenous particulate Ags, including inert synthetic particles without lipid membranes and intravacuolar bacteria. Peptides from these Ags are released from intracellular compartments to bind to surface MHC-I molecules, but peptide-MHC-I complexes also may be generated within intracellular compartments.

Animals↗
PubMed1994

Cellular binding site and membrane binding proteins for triglyceride-rich lipoproteins in human monocyte-macrophages and THP-1 monocytic cells.

Triglyceride- and cholesterol-rich foam cells derived from monocyte-macrophages are commonly associated with some forms of hypertriglyceridemia. In this report, direct binding studies at 4 degrees C demonstrate that human monocyte-macrophages (HMM) 1-6 days after isolation from blood and human THP-1 monocytic cells, before and up to 7 days after differentiation with phorbol ester, exhibit a high affinity (Kd 3-6 nM), saturable, specific, and apolipoprotein (apo) E-independent binding site for the uptake and degradation of certain triglyceride-rich lipoproteins (TGRLP). Ligand blotting analysis identified two membrane binding proteins (MBP) of apparent molecular weights of 200 and 235 kDa (MBP 200 and MBP 235) in both cell types that share the same ligand specificity as the cellular site and bind hypertriglyceridemic (HTG) VLDL, trypsinized VLDL devoid of apoE (tryp-VLDL), and dietary plasma chylomicrons from normal subjects but not LDL, acetyl LDL, or normal VLDL with high affinity. Neither lipoprotein lipase nor apoE are required for TGRLP binding to the cells or the isolated MBPs. The cellular binding site and the MBPs are expressed at similar levels at all stages of differentiation, unlike the LDL or the acetyl LDL receptor. TGRLP that bind to the MBPs induce rapid, saturable, cellular triglyceride accumulation in monocytes as well as macrophages; normal VLDL does not. In addition, the cellular high affinity binding site and MBP 200 and 235 are not affected by the media sterol content, unlike the LDL receptor. Taken together, these data indicate that human monocyte-macrophages exhibit a high affinity, saturable, specific, apoE- and lipoprotein lipase-independent binding site and membrane binding proteins for TGRLP that differ in expression, specificity, and molecular size from receptors of the LDL receptor gene family or the acetyl LDL receptor. The shared characteristics of the cellular binding site with MBP 200 and MBP 235 suggest that they are candidates for the receptor-mediated, apoE-independent uptake of HTG-VLDL and chylomicrons by monocytes and macrophages and therefore may be involved in foam cell formation.

Animals↗
PubMed1992

Breast volume measurement in 125 young Chinese women.

The authors carried out research on breast volume and body surface anatomy of 125 unmarried young women. As a result, an average breast volume for young Chinese women was obtained (325.36 +/- 12.66 ml), and a table together with several linear equations for calculating breast volume were derived. These will provide plastic surgeons with useful tools for designing mammaplasty procedures.

Adolescent↗
PubMed1990

Relationship between dihydropyrimidine dehydrogenase activity and plasma 5-fluorouracil levels with evidence for circadian variation of enzyme activity and plasma drug levels in cancer patients receiving 5-fluorouracil by protracted continuous infusion.

The activity of dihydropyrimidine dehydrogenase (DPD) in peripheral blood mononuclear cells and plasma concentration of 5-fluorouracil (FUra) were simultaneously determined in cancer patients receiving FUra by protracted continuous infusion (300 mg/m2/day). Blood samples were drawn every 3 h over 24-h period and the resulting DPD and FUra values analyzed for circadian periodicity. In the seven patients studied, a circadian rhythm of DPD activity was observed (P less than 0.00001, Cosinor analysis) with the peak of activity at 1 a.m. (0.197 +/- 0.007 nmol/min/mg) and the trough at a 1 p.m. (0.113 +/- 0.007 nmol/min/mg). In addition, a circadian rhythm was observed for the plasma concentrations of FUra obtained over a 24-h period (P less than 0.00001, Cosinor analysis) with peak values (27.4 +/- 1.3 ng/ml) occurring at 11 a.m. and trough values (5.6 +/- 1.3 ng/ml) occurring at 11 p.m. The ratio of the maximum concentration of FUra to the minimum concentration observed was almost 5-fold. This study demonstrates a circadian variation of DPD activity in human peripheral blood mononuclear cells and a circadian variation of FUra plasma levels in patients receiving FUra by protracted continuous infusion. An inverse relationship between the circadian patterns of DPD activity and FUra plasma levels was also noted, suggesting that an association may exist between DPD activity and FUra plasma concentration. Further evidence of an association between DPD activity in peripheral blood mononuclear cells and plasma FUra concentration was demonstrated by a linear relationship between the two parameters in all patients (r = -0.627) and within individual patients (-0.978 less than r less than -0.742). With the recent advent of programmable pumps, information on the circadian pattern of FUra and/or DPD may be useful in planning continuous infusion schedules in order that optimal plasma drug concentration may be maintained over a 24-h cycle, thereby enhancing the therapeutic efficacy of FUra administered by continuous infusion.

Aged↗