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Biomedical subjects

S L Cheng

Publications and source records attributed to S L Cheng.

90 records · Page 5Linked to original sources
PubMed1985

Nipple aspirates of breast fluid and the epidemiology of breast disease.

Epidemiologic data were obtained, and nipple aspiration attempted, from 289 healthy women, 548 women currently having or with a history of benign breast disease, 153 untreated women with breast cancer, and 106 women previously treated by mastectomy. Breast duct fluid was produced in detectable amounts by 59% of the controls and patients with benign or untreated malignant breast disease; in 35% the volume was in excess of 10 microliters. There were more secretors aged 30 to 50 years (72%), than either those who were younger (52%), or older (44%). Overall, 57% of premenopausal women were secretors, compared with 38% of postmenopausal women. Healthy women who had their menarche before age 13 years were more likely to be secretors. Neither parity, age at first completed pregnancy, nor body weight affected secretor status. There was a trend for the 141 benign breast disease patients aged 40 to 49 years to include more women yielding greater than 10 microliter of fluid (57%) compared with 46 controls (39%). Although breast cancer per se did not appear to influence secretor status, postmastectomy patients were more likely to secrete large fluid volumes, an effect that was particularly pronounced after menopause. Hormonal factors related to age and fibrocystic disease risk and endocrine activity after mastectomy may be the principal determinants influencing the secretion of breast duct fluid.

Adult↗
PubMed1985

Murine macrophage tumors are a source of a 260,000-dalton acetyl-low density lipoprotein receptor.

Subcutaneous injection of murine macrophage cell line P388D1 into syngeneic DBA/2 produced tumors, which upon solubilization with 40 mM octyl glucoside contained acetylated low density lipoprotein binding activity. The tumor-derived receptor specifically bound acetylated low density lipoprotein with an affinity of approximately 3 X 10(-8) M but did not bind low density lipoprotein or high density lipoprotein. It was identical in binding specificity, affinity, and Pronase sensitivity to the receptor in intact cells or that obtained from solubilized cultured cell membranes. Partial purification of the receptor was achieved by solubilizing tumors with 1% Triton X-100 followed by chromatography on polyethyleneimine cellulose. After elution with a NaCl gradient in the presence of octyl glucoside and association with liposomes, a 287-fold purification of the receptor was achieved. The receptor was identified by specific ligand blotting as a 260,000-dalton protein having a pI of approximately 6.0. Binding to the receptor by acetylated low density lipoprotein, malondialdehyde-modified low density lipoprotein, and maleic anhydride-modified serum albumin was demonstrated by ligand blotting. A single receptor protein can, therefore, account for the binding of multiple types of charge-modified lipoprotein and nonlipoprotein ligands to the macrophage cell surface.

Animals↗
PubMed1984

Comparison of rabbit androgen binding protein with testosterone estradiol binding globulin--I. Physical and chemical properties.

Rabbit epididymal androgen binding protein (rbABP) and serum testosterone estradiol binding globulin (rbTeBG) were purified and their physicochemical properties compared. Both proteins bound dihydrotestosterone (DHT) with high affinity. Both contained two components, Heavy (H) and Light (L), and their molecular weights and pI values were comparable. rbABP and rbTeBG were different with regard to their ConA-Sepharose binding property. rbABP was not bound by ConA-Sepharose while rbTeBG was found and retained by this lectin; thus, rbABP and rbTeBG differed in their carbohydrate structure. Peptide mapping on SDS-PAGE indicated that the H components of rbABP and rbTeBG were distinct even though they showed a high degree of homology. By contrast, the L components of these two proteins appeared to be identical. The structure of the steroid binding sites of these two proteins was analyzed by peptide mapping of [1,2(3)H]17 beta hydroxy-androsta-4,6-dien-3-one photoaffinity labeled protein. The size distribution of radioactive peptide fragments generated appeared to be identical for these two proteins. However, the distribution of labeled peptides was slightly different when examined by high pressure liquid chromatography (HPLC). The observations suggest that the differences between rbABP and rbTeBG might reside not only in carbohydrate moieties but also in their amino acid sequences.

Affinity Labels↗
PubMed1983

Radioimmunoassay of testosterone-estradiol-binding globulin in humans: a reassessment of normal values.

Antiserum against human testosterone-estradiol-binding globulin (hTeBG) was prepared in rabbits, and its specificity was demonstrated by crossed immunoelectrophoresis. A RIA for the measurement of hTeBG in serum was developed. With this assay, hTeBG was readily measured in 1-2 microliters serum. Interassay coefficients of variation for pools of serum from men, women, and women in late pregnancy were 7.7%, 5.5%, and 6.1%, respectively. Interassay coefficients of variation for the same pools were 10%, 12%, and 12%, respectively. The TeBG levels in a number of nonselected subjected determined by the present method show good correlations with those obtained by steady state polyacrylamide gel electrophoresis and dextran-coated charcoal assay. The concentrations of TeBG determined by the RIA in sera from men, women, and women in late pregnancy were 18 +/- 9 (n = 12), 54 +/- 13 (n = 8), and 374 +/- 55 (n = 6) pmol/ml (mean +/- SD), respectively.

Amniotic Fluid↗
PubMed1982

Purification and characterization of androgen binding protein from rabbit epididymis.

A method for the purification of androgen binding protein (ABP) from the rabbit epididymis is presented. Epididymal extracts were submitted to sequential ammonium sulfate precipitation, androgen affinity chromatography, concanavalin A (Con A) affinity chromatography, and preparative polyacrylamide gel electrophoresis. Since the blood protein testosterone-estradiol binding globulin (TeBG) was a possible component of the epididymal extract, ABP was differentiated and separated from TeBG by affinity chromatography on Con A-Sepharose since the latter protein was shown to be completely absorbed by the lectin while the former was not. The final product was shown to be pure by polyacrylamide gel electrophoresis. Electrophoresis in the presence of sodium dodecyl sulfate revealed that ABP is comprised of subunits.

Androgen-Binding Protein↗
PubMed1971

Lymphoid Cells in Delayed Hypersensitivity II. In Vitro Phagocytosis and Cellular Immunity.

Guinea pigs which develop delayed hypersensitivity, as measured by skin test, after intraperitoneal infection with Candida albicans have mononuclear cells (macrophages and lymphocytes) which show migration inhibition in vitro in the presence of soluble antigen. Macrophages from such animals phagocytose in vitro fewer numbers of C. albicans per cell than those of normal animals, and lower numbers of macrophages are phagocytic in vitro. Nevertheless, such sensitized animals have lower numbers of pathogens in their tissues than the controls, after both groups have been challenged. Thus, the result of macrophages from sensitized guinea pigs being less mobile, less phagocytic, and more destructive than those from normal animals may be a more limited spread of the infectious agent throughout the tissues; the animal would seem more resistant.

Journal Article↗
PubMedDate not supplied

Treatment of locked posterior fracture-dislocations of the shoulder by total shoulder arthroplasty.

Total shoulder arthroplasty is indicated in the treatment of locked posterior fracture-dislocations of the shoulder where there is extensive damage to the articular surfaces of the humerus and glenoid. This report reviews the surgical technique, postoperative rehabilitation program, and functional results of seven shoulders in five patients who had locked posterior dislocations of the shoulder. Activities involving overhead positioning of the arm and heavy lifting continued to be challenging for this group of patients. The American Shoulder and Elbow Surgeons' Shoulder Score improved from 20.1 before surgery to 55.6 after surgery (p = 0.018). The extrication of the posteriorly dislocated humeral head may be difficult from an anterior deltopectoral approach. The authors describe the use of a secondary posterior incision facilitating the extrication of the humeral head. In this series total shoulder arthroplasty reliably decreased the patients' level of pain, improved their range of motion, and significantly improved their level of function.

Adult↗