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Biomedical subjects

R Yu

Publications and source records attributed to R Yu.

At least 163 records · Page 9Linked to original sources
PubMed1992

CD68 antigen expression by human retinal pigment epithelial cells.

Although a primary role of the retinal pigment epithelium (RPE) is the phagocytosis of aged outer segment membranes, the RPE may also phagocytize particulates via several specific receptors that are characteristically present on mononuclear phagocytes of bone marrow origin. In recent immunophenotypic studies, CD68 monoclonal antibodies (mAb) have been shown to react selectively with a specific 110 kDa cytoplasmic glycoprotein present in mononuclear phagocytes from various sources. Designated as anti-macrophage antibodies that react with this macrophage-associated antigen, CD68 antibodies are now widely used for immunohistochemical identification of mononuclear phagocytes. Using a panel of CD68 mAb (KP1, EMB11, Ki-M6, Y1/82A, and Y2/131) we performed immunohistochemistry on three cytospin preparations of freshly isolated human RPE cells, three primary human RPE cultures, and 12 human RPE cell lines maintained in culture for up to 40 passages. Cytospin preparations of freshly isolated RPE cells demonstrated heavy reactivity in 5% of cells. Five- to 7-day-old primary RPE cultures exhibited uniform, heavy staining of all cells. Strong immunohistochemical reactivity persisted in all 12 cell lines at various passages up to and including passage 40. Stimulation of cultured RPE cells with interferon-gamma (100 U ml-1) for 24 and 48 hr did not produce observable differences in CD68 staining. RPE cells failed to stain when control mAb or mouse serum were substituted for the primary antibody. The constitutive expression of CD68 by neuroectodermally-derived RPE cells extends their immunophenotypic similarities with mesenchymally-derived mononuclear phagocytes and provides an additional antigenic marker to identify RPE cells in vitro.

Antigens, CD↗
PubMed1992

T lymphocytes bearing the gamma delta T-cell receptor: a study in normal human skin and pathological skin conditions.

The aims of this study were to investigate the presence of gamma delta T cells in normal human skin, and the possible role of these cells in cutaneous reactions. Twenty-eight samples of normal skin from various sites, and 52 biopsies from inflammatory and neoplastic skin conditions were investigated by immunohistochemical techniques. In normal human skin gamma delta T cells were infrequently seen in the epidermis and dermis. In the inflammatory and neoplastic dermatoses, gamma delta T cells were occasionally present, accounting for 0-5% of CD3+ cells in most of the biopsies examined. In one case of pityriasis lichenoides chronica and one case of lichen planus gamma delta T cells were found to be increased, accounting for 15% of the CD3+ cells in each case. Dermal gamma delta T cells were markedly increased in three of six cases of Langerhans cell histiocytosis, with up to 30% of dermal CD3+ cells showing positive staining to an anti-T-cell receptor gamma delta monoclonal antibody. In two of these cases gamma delta T cells were seen in both the dermis and the epidermis. In two further cases dermal gamma delta T cells were not a prominent feature, but small clusters of epidermal gamma delta T cells were observed. T cells bearing the gamma delta T-cell receptor are thus not a major feature of normal human epidermis, unlike the murine system, where the great majority of epidermal lymphocytes express the gamma delta T-cell receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidermis↗
PubMed1992

Haemodialysis-related porphyria cutanea tarda and treatment by recombinant human erythropoietin.

Haemodialysis-related porphyria cutanea tarda is a rare, but serious and mutilating skin condition, resulting from extremely high plasma porphyrin levels because of their inadequate clearance by haemodialysis. The treatment is very difficult as chloroquine is ineffective and venesection, the conventional treatment of this disease, is not always an option because of anaemia of end-stage renal disease. We report a case of haemodialysis-related porphyria cutanea tarda and her successful management by recombinant human erythropoietin treatment.

Erythropoietin↗
PubMed1992

The effect of warm heart surgery on postoperative bleeding.

The effects of normothermic systemic perfusion (35 degrees to 37 degrees C; n = 73) were compared with those of moderately hypothermic systemic perfusion (25 degrees to 29 degrees C; n = 73) with respect to blood loss, transfusion requirements, and platelet levels in 146 patients undergoing isolated, primary coronary artery bypass grafting. In addition, most patients were given an antifibrinolytic medication during operation as follows: tranexamic acid (10 gm intravenously; n = 63), epsilon-aminocaproic acid (15 gm intravenously; n = 63), or no drug as a control. (n = 20). Normothermic patients tended to bleed less at 24 hours (warm, 864 +/- 42 ml and cold, 918 +/- 68 ml), but these differences were not statistically significant. Patients receiving either tranexamic acid or epsilon-aminocaproic acid, regardless of perfusion temperature, bled less after 6, 12, and 24 hours than did cold control patients (p less than 0.05). Warm control patients also bled less than did cold control patients after 6 or 12 hours (p less than 0.05), and neither drug further reduced blood loss in these patients. Circulating platelet levels were better preserved in patients receiving either tranexamic acid or epsilon-aminocaproic acid and in patients with warm perfusion and no drug than in cold control patients. Normothermic systemic perfusion, tranexamic acid, and epsilon-aminocaproic acid each reduced postoperative blood loss and preserved platelets.

Aminocaproic Acid↗
PubMed1991

Comparative mutagenicity testing of bropirimine, 3. Bropirimine does not induce cytogenetic damage in vivo in the rat but does produce micronuclei in the mouse.

Bropirimine is a biological response modifier (BRM) with potential antineoplastic and antiviral indications. Recent results have documented the negative findings in the Ames Salmonella assay, the in vitro UDS assay and the mouse lymphoma TK+/- assay as well as positive findings in the in vitro cytogenetic assay in CHO cells. Extensive mechanistic studies failed to establish the reason for positive findings in the in vitro cytogenetic assays. The data reported here cast doubt on the relevance of the in vitro cytogenetic results and suggest limited in vivo genotoxic potential. At doses as high as 150 mg/kg (i.p.) and 6.73 g/kg (p.o.), no evidence of chromosome aberration induction was observed in rat bone marrow cytogenetic assays. Consistent with these data, plasma and bone marrow tissue levels in similarly treated animals were well below those required for activity in the in vitro chromosome aberration assays. Positive results were obtained in the mouse micronucleus assay. However, the significance of these findings may be explained by markedly different pathways of metabolism in that species as compared to the rat. Hence, the findings in the mouse are of questionable relevance to human risk assessment. Exposure of humans to bropirimine, under therapeutically acceptable regimens is unlikely to constitute a genotoxic health hazard.

Animals↗
PubMed1991

[Toxic principles of Oxytropis glabra DC].

Eight alkaloids were isolated from Oxytropis glabra and identified as anagirine, thermopsine, N-methylcytisine, sparteine, baptifoline, adenine, dictamnine and ethyl allophanate respectively by spectral analysis and physicochemical methods. All these alkaloids were isolated from this genus for the first time and ethyl allophanate was found in nature for the first time.

Alkaloids↗
PubMed1988

Seizures following myelography with iopamidol.

Iopamidol, a water-soluble contrast medium, has been rarely associated with seizures. We describe 3 patients (from a series of 785) who had generalized tonic-clonic seizures after iopamidol myelography. Two of the patients underwent lumbar and one cervical myelography. There was a history of seizures in 2 patients, and the dose of iopamidol used in the patients who convulsed was high, ranging from 3,000 to 4,500 mg iodine. Despite the reported low incidence of complications with iopamidol, seizures may occur, especially in patients with previous seizures and also in those receiving higher doses of iopamidol.

Female↗
PubMed1987

Stability of ceramic pigments for maxillofacial applications.

In this study samples made from pigmented porcelain and Silastic 44210 were evaluated for colour stability after accelerated ageing in order to determine the potential of coloured ceramic powders as maxillofacial pigments. These pigments demonstrated good clear colour stability compared with the same pigments which were not incorporated into a porcelain matrix.

Dental Porcelain↗