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Biomedical subjects

Y Sasai

Publications and source records attributed to Y Sasai.

At least 109 records · Page 6Linked to original sources
PubMed1991

Monoclonal antibody KOLT-2 enhances DNA synthesis and expression of IL-2 receptors on activated T cells.

The functional properties of the KOLT-2 antigen, which was placed among the CD28 group in the 3rd International Workshop on Human Leukocyte Differentiation Antigens, are described. The method of production and a detailed characterization of the monoclonal antibody KOLT-2 including stain affinities and influence of T cell activation are presented. While KOLT-2 antigen was selectively expressed on human thymocytes, adult T-cell leukemia-lymphoma cells and activated T cells, the antigen was also spontaneously expressed by resting T cells after 24 hrs culture. Expression was transient, since it disappeared after 96 hrs. DNA synthesis and expression of Tac antigen on activated T cells was enhanced by stimulation with the KOLT-2. These observations suggest that the KOLT-2 antigen may have an important role in the early stages of T cell activation.

Antibodies, Monoclonal↗
PubMed1991

Correlation between DNA quantities in agarose gel and chromatographic areas of photographed DNA bands.

To quantitate DNA from photographs, correlations between chromato-scanned (in the fluorescence mode) and virtual areas from white DNA bands on photographs were examined. A linear correlation between the two measurements with coefficients higher than 0.89 was observed. The dynamic range of the fluorescence detection yielded good linearity for a wide range of amounts of DNA (microgram-ng) on the photograph.

Chromatography↗
PubMed1991

Low concentrations of interferon-gamma stimulate DNA synthesis in normal human keratinocytes during the initial stages of cultivation.

High concentrations of interferons can inhibit keratinocyte proliferation and induce the expression of HLA-DR antigen on keratinocytes. In the present study, the effects of low concentrations of recombinant human interferon alpha, beta and gamma were examined on DNA synthesis and the expression of HLA-DR and bullous pemphigoid (BP) antigens in normal human keratinocytes. Low concentrations of interferons induced DNA synthesis in normal human keratinocytes when epidermal cell growth factor and low Ca++ were used during the initial stages of culturing. This result indicates that physiological concentrations of interferons can induce keratinocyte activation.

Animals↗
PubMed1990

Alterations in membrane fluidity during keratinocyte differentiation measured by fluorescence polarization.

The epidermis shows a distinctive pattern of differentiation wherein keratinocytes proliferate in the basal cell layer and mature into spinous and granular cells. Using a discontinuous density-gradient centrifugation method, guinea-pig keratinocytes were separated into high (HDF), intermediate (IDF), and low (LDF) density fractions. Morphological and flow cytometrical observations demonstrated that HDF, IDF, and LDF were basal, spinous, and granular cell-rich fractions, respectively. Membrane fluidity of the fractionated keratinocytes was measured by diphenylhexatriene fluorescence polarization. Polarization (p)-value of keratinocytes was negatively correlated with temperature. At each temperature, HDF cells showed a lower p-value than IDF or HDF cells except at 40 degrees C. Since a low p-value indicates a high degree of Brownian motion, membrane fluidity is higher in basal cells and lower in spinous and granular cells. Our results indicate that membrane fluidity of guinea-pig keratinocytes decreases during their maturation.

Animals↗
PubMed1990

Human papillomavirus DNA from warts for typing by endonuclease restriction patterns: purification by alkaline plasmid methods.

The alkaline plasmid DNA extraction method of Birnboim and Doly was applied for the isolation of human papillomavirus (HPV) from warts. Tissue from common and plantar warts was digested with proteinase K, and the extrachromosomal circular covalently-closed form of HPV-DNA was rapidly extracted by alkaline sodium dodecyl sulphate and phenol-chloroform treatment. Recovery of HPV-DNA from the tissue was sufficient for determination of endonuclease restriction patterns by agarose gel electrophoresis.

Adolescent↗
PubMed1990

Multiple keratoacanthomas with peculiar manifestations and course.

The case of a 60-year-old Japanese man with unique multiple keratoacanthomas is reported. The lesions were located in the perioral area, grew peripherally, and healed centrally. Although individual lesions spontaneously regressed, prompt recurrence was observed after excision. Biopsy specimens taken from early proliferative, fully developed, and regressing stages revealed keratoacanthoma. Involucrin was demonstrated in the lesions during development and resolution. The early stage showed homogeneous staining of moderate intensity in the tumor cells at the suprabasal layers, and the staining became slightly irregular and intense when the lesions were fully developed. During resolution the intensity was markedly diminished. These results suggest that preterminal squamous differentiation accelerated during development of the tumors.

Diagnosis, Differential↗
PubMed1990

Cytofluorometric study of lectin binding to the keratinocytes of epidermolysis bullosa simplex.

Epidermolysis bullosa (EB) simplex is a congenital disease that has blister formation following minor mechanical trauma to the skin. The least amount of information concerning the pathogenesis is known in this disease. One possibility is that there are structural abnormalities in keratinocytes. In the present study, we report the binding of lectin (Ricinus communis agglutinin, Peanut agglutinin, and Soybean agglutinin) to keratinocytes using cytofluorometry. Biopsy skin specimens were taken from patients with simplex, junctional, and dystrophic forms of EB, and normal volunteers. Free keratinocytes were obtained by the treatment of EDTA and trypsin, and fractionated by centrifugation on a continuous colloidal silica (Percoll) density gradient. Fractionated basal cells were stained with biotinyl lectins and avidin-FITC, and measured by cytofluorometry. In all lectins examined, the intensity was low in the basal cells of EB simplex, as compared with normal controls. However, there were no differences among the other forms of EB and normal controls. This results suggest the presence of structural abnormalities in epidermis of EB simplex.

Avidin↗
PubMed1990

Proliferating trichilemmal cyst with spindle cell carcinoma.

We report a 58-year-old woman with proliferating trichilemmal cyst (PTC), from which a spindle cell carcinoma arose. The tumor on her scalp had been removed at another hospital. Histological examination had revealed almost typical features of PTC. However, the case showed a partial transformation to spindle cell carcinoma, and transition zones between squamous epithelium and spindle cells were present. Three months after histologic examination, the patient came to us for the treatment of recurrent tumor. Despite surgical resection, the patient died as a result of distant metastases. Histologically, the recurrent tumor was composed of only spindle-shaped tumor cells. We describe the first example of this uncommon condition.

Carcinoma↗
PubMed1990

Cutaneous phaeohyphomycosis caused by Exophiala jeanselmei after renal transplantation.

A 60-year-old man who had had a renal transplantation developed a nodule on the dorsum of his right middle finger, which was subsequently diagnosed as cutaneous phaeohyphomycosis caused by Exophiala jeanselmei. The patient was successfully treated with 5-fluorocytosine. To our knowledge, this case is the third reported case in the world caused by this species in a postrenal transplant patient that manifested as phaeohyphomycosis.

Dermatomycoses↗
PubMed1990

Expression of ras p21 in mammary and extramammary Paget's disease.

With the use of immunohistochemical techniques, we examined the expression of ras oncogene product p21 in 4 cases of mammary and 13 cases of extramammary Paget's disease. In every mammary case, positive immunostaining was observed in Paget's cells and the underlying tumor (in the 3 cases where a tumor was present). Among the extramammary cases, the cells in 6 cases were immunoreactive. In 4 of these positive extramammary cases, dermal invasion and metastases of regional lymph nodes were observed. Another 2 extramammary cases were weakly reactive. An enhanced expression of ras p21 therefore seems to depend on the region of the tumor or on the biologic behavior. This work suggested that an enhanced expression of ras p21 in Paget's cells may represent a new clinical marker for tumors in cases of mammary and extramammary Paget's disease.

Aged↗
PubMed1989

Molecular characterization of rat substance K receptor and its mRNAs.

The nucleotide sequence and the amino acid sequence for rat substance K receptor were deduced by molecular cloning and sequence analysis of its cDNAs. The rat substance K receptor consists of 390 amino acid residues and belongs to the family of G protein-coupled receptors. The comparison of the amino acid sequences of the rat and bovine substance K receptors indicated that they are highly homologous in the regions covering seven putative transmembrane domains, and this similarity is particularly remarkable in the transmembrane segments III and VII and their surrounding regions. RNA blot hybridization analysis showed that the rat substance K receptor is encoded by two species of mRNAs which differ in the lengths of the extreme 5' sequence of the 5'-untranslated regions. This analysis also indicated that the substance K receptor mRNAs are expressed in the gastrointestinal tract. Interestingly, no appreciable substance K receptor mRNAs were detected in poly(A)+ RNAs isolated from the brain and spinal cord, even though these tissues are known to not only contain substance K but also express the mRNA encoding the substance K precursor.

Amino Acid Sequence↗
PubMed1989

Molecular characterization of a functional cDNA for rat substance P receptor.

This paper describes the amino acid sequence of the rat substance P receptor and its comparison with that of the rat substance K receptor on the basis of molecular cloning and sequence analysis. From a rat brain cDNA library constructed with an RNA expression vector, we identified a cDNA mixture containing a functional substance P receptor cDNA by examining electrophysiologically a receptor expression following injection of the mRNAs synthesized in vitro into Xenopus oocytes. A receptor cDNA clone was then isolated by cross-hybridization with the bovine substance K receptor cDNA. The clone was confirmed by selective binding of substance P to the cloned receptor expressed in mammalian COS cells. The deduced amino acid sequence (407 amino acid residues) possesses seven putative membrane spanning domains and shows a sequence similarity to the members of G-protein-coupled receptors. The rat substance P and substance K receptors are very similar in both size and amino acid sequences, particularly in the putative transmembrane regions and the first and second cytoplasmic loops. This similarity is in marked contrast to the sequence divergence in the amino- and carboxyl-terminal regions and the third cytoplasmic loop. The observed sequence similarity and divergence would thus contribute to the expression of similar but pharmacologically distinguishable activities of the two tachykinin receptors.

Amino Acid Sequence↗
PubMed1989

Alteration in the density, morphology, and biological properties of eosinophils produced by bullous pemphigoid blister fluid.

Bullous pemphigoid blister fluid (BP-BF) was examined for its effects on the density, morphology, and biological properties of eosinophils. Normodense eosinophils (NEo) were prepared from guinea pig peritoneal exudates by Nycodenz density gradient centrifugation. After culturing with BP-BF, NEo were converted into hypodense eosinophils (HEo) in a time-dependent manner. HEo were morphologically different from NEo in that HEo had spheroidal granules each with a lytic crystalloid core and a significantly increased cell volume. These HEo showed an enhanced antibody- and/or complement-dependent helminthotoxic activity to Schistosoma mansoni larvae, amplified chemiluminescence response to opsonized zymosan, and augmented expression of both FcR+ and CR+. These results suggest that BP-BF contains an activity that may not only induce an eosinophil hypodensity as a consequence of increasing cell volume, but simultaneously enhance an eosinophil cytotoxic potential through augmenting cell-surface receptors and receptor-linked oxidative metabolism. In addition, observed tissue accumulation of this activity suggests that eosinophils may be regulated by their phenotypic change in the skin lesions of bullous pemphigoid and be involved in blister formation.

Animals↗
PubMed1989

Cytofluorometric study on lectin binding of isolated guinea pig keratinocytes.

Lectin binding was cytofluorometrically measured on fractionated keratinocytes of guinea pig. Free keratinocytes were obtained by treatment of EDTA and trypsin. After the treatment, they were separated into 3 fractions by centrifugation on a continuous colloidal silica (Percoll) density gradient. Cells in each fraction were stained by biotinyl lectins and avidin-FITC, and fluorescence intensity was measured by cytofluorometry. Results obtained indicate that little cell surface glycoconjugate is lost during the preparation of free keratinocytes.

Animals↗
PubMed1989

Immunohistochemical demonstration of epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), and keratin on mammary and extramammary Paget's disease.

We examined the presence and the distribution of epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), and keratin in 4 cases (6 specimens) of mammary Paget's disease and 9 cases (18 specimens) of extramammary Paget's disease utilizing immunoperoxidase technique. Paget's cells in 23 out of 24 specimens were demonstrable for EMA. Positive staining was observed for CEA in every specimen. Among the 24 specimens, 16 showed positivity for keratin. In addition, CEA was positive in Paget's cells and the staining for CEA was stronger than that of EMA and keratin. On the other hand, some Paget's cells were negative for EMA of keratin although other positive cells were observed in the same sections. This findings indicates that Paget's cells might express CEA and/or EMA and/or keratin depending on their differentiation. EMA is present in most organs showing glandular differentiation, and anti-keratin antibody used in this study recognizes not only keratinocytes but glandular cells. Thus, our study suggests Paget's cells are of glandular origin.

Antigens↗