Search PubMed⌕ Search

Biomedical subjects

K Okubo

Publications and source records attributed to K Okubo.

At least 253 records · Page 14Linked to original sources
PubMed1992

Relationship between increased cyclic AMP-phosphodiesterase activity and abnormal adenylyl cyclase regulation in leukocytes from patients with atopic dermatitis.

Atopic dermatitis (AD) is characterized by a variety of abnormal physiologic and pharmacologic responses in the skin. Leukocyte abnormalities of the cyclic nucleotide system include increased cAMP phosphodiesterase (PDE) and adenylyl cyclase activities. We have evaluated the possibility that a defect of the inhibitory GTP-binding protein (Gi) might cause inadequate modulation of adenylyl cyclase activity in AD leukocytes. We carried out a series of studies assessing adenylyl cyclase and Gi subunits in monocyte membranes. Using both pertussis toxin ribosylation and direct monoclonal antibody labeling of Gi proteins, we have shown evidence for a decrease or possible absence of one of the Gi proteins in atopic monocyte membranes. A genetic defect or toxin-mediated abnormality in leukocyte membrane Gi could account for these findings. Increased cAMP degradation by PDE may be a compensatory mechanism for increased cAMP synthesis that is regulated by GTP-binding proteins. But this increased PDE activity also rendered AD leukocytes hypo-responsive to immunofunction regulatory signals mediated by cAMP.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1992

Epidermal keratinocytes of bullous pemphigoid express intercellular adhesion molecule-1 (ICAM-1).

Intercellular adhesion molecule-1 (ICAM-1) is the ligand for lymphocyte function associated antigen-1 (LFA-1), mediating the adhesion of lymphocytes to vascular endothelium. Keratinocytes are known to express ICAM-1 in some inflammatory dermatoses. Using an indirect immunofluorescence method, we examined the patterns of ICAM-1 and LFA-1 staining in bullous pemphigoid (BP) lesions and compared them to pemphigus vulgaris (PV) cases. ICAM-1 was expressed on the cell surface and in the cytoplasm of epidermal keratinocytes at the sites of erythematous and bullous lesions of BP. LFA-1 molecules were expressed on T cells at the basement membrane zone. In addition, HLA-DR-positive keratinocytes were observed in the basal layer. ICAM-1 was not, however, expressed on epidermal keratinocytes in uninvolved skin from BP patients, PV or normal control skin. It is known that ICAM-1 is expressed on keratinocytes at the site of lymphoid infiltration in cutaneous dermatoses and that LFA-1-positive T cells can bind to interferon gamma-induced ICAM-1-positive keratinocytes. Our results suggest that cellular immunity involving ICAM-1 and LFA-1 may play a part in the pathogenesis of bullous pemphigoid.

Cell Adhesion↗
PubMed1992

Band 3-Memphis is associated with a lower transport rate of phosphoenolpyruvate.

Band 3-Memphis is the most common variant of erythrocyte band 3 protein, in which a single amino acid substitution (Lys56-->Glu) in a cytoplasmic domain of band 3 has been found. We showed here that the prevalence of the variant was particularly higher in the Japanese population than that in other populations. The calculated gene frequency of the variant in Japanese was 0.156, which was about 4 times higher than that in Caucasian. Although it has been generally accepted that the cytoplasmic domain of band 3 bears no relation to anion transport activity, we found that the transport rate of phosphoenolpyruvate in erythrocytes of homozygotes was decreased to about 80% of that in control cells, and that of heterozygotes was at an intermediate level. The evidence indicates that some structural changes in the cytoplasmic domain of band 3 may have influence on the conformation of anion transport system.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1992

Giant hypertrophic gastritis and acute hepatitis associated with cytomegalovirus infection.

A 38-year-old man developed prominent hypoproteinemia after acute elevation of serum transaminase levels. Giant hypertrophy of the gastric mucosa, a short serum albumin half-life, and the absence of massive hepatocyte necrosis established the diagnosis of protein-losing gastropathy. The hypoproteinemia, gastric fold hypertrophy and hepatitis remitted spontaneously within 4 months. A high antibody titer against cytomegalovirus suggested an association between the viral infection and the patient's disease.

Acute Disease↗
PubMed1992

Surface charge of fractionated guinea pig keratinocytes measured by free-flow cell electrophoresis.

Keratinocytes differentiate from basal cells to spinous, granular, and horny layer cells. It is known that alterations in the surface charge of cell membranes in most cases reflect the processes of differentiation. By using a continuous colloidal silica (Percoll) density gradient, keratinocytes may be separated into three fractions which correspond to their arrangement in vivo. Using a free-flow cell electrophoretic technique, we measured the electrophoretic mobility of guinea pig keratinocytes. Electrophoretic mobility histograms of basal and granular cells showed slow and fast monophasic patterns, respectively. In spinous cells, a biphasic pattern of slow and fast electrophoretic mobility was present. The electrophoretic mobility level of guinea pig keratinocytes was slightly reduced with neuraminidase digestion. Those of human red blood cells and lymphocytes, however, were markedly decreased. These results indicate that membrane charge density is lower in basal cells and higher in granular cells and that the membrane charge density of guinea pig keratinocytes involves not only neuraminic acid residues but also other substance(s). Our results illustrate the alterations of cell membrane charge properties during epidermal cell differentiation.

Animals↗
PubMed1992

[A case of Tolosa-Hunt syndrome accompanied by facial and vestibular nerve damage].

A 37-year old man, who had repeatedly suffered from transient ophthalmoplegia in his left eye at the age of 29 and 36, developed left painful ophthalmoplegia accompanied by ipsilateral facial nerve palsy in August, 1991. Neurological examination revealed involvement of the left oculomotor, trochlear, ophthalmic division of the trigeminal, abducens, facial and vestibular nerves. Gadolinium-enhanced MRI which was taken at the acute phase of the illness demonstrated markedly enhanced left cavernous sinus and adjacent thickened dura mater in the middle cranial fossa. At the remission phase after starting corticosteroid therapy, these enhanced lesions were no longer observed even in enhanced MRI studies. We diagnosed him as suffering from Tolosa-Hunt syndrome presently accompanied by facial and vestibular nerve damage because of his history of illness, confined lesion in the left cavernous sinus and steroid-induced remission. We concluded that Tolosa-Hunt syndrome may be accompanied by damage of other cranial nerves in its course and that repeated gadolinium-enhanced MRIs are necessary for diagnosis and observation of the patients.

Adult↗
PubMed1992

[Polarized light irradiation near the stellate ganglion in a patient with Raynaud's sign].

Polarized light irradiation near the stellate ganglion was performed in a 55-year-old female with Raynaud's sign. She was suffering from cold and numb pain in bilateral fingers for 1 year. Stellate ganglion block and low reactive-level laser therapy near the stellate ganglion were not sufficient to relieve this symptom. Polarized light irradiation near the stellate ganglion induced a sting stimulation and warm sensation in her hands. Thermograms revealed a remarkable increase in temperature of her hands. The results imply that polarized light irradiation near the stellate ganglion increases blood flow of forearms and relieves Raynaud's sign.

Female↗
PubMed1992

[A case of lung cancer in a patient with von Recklinghausen's disease].

A 57-year-old man was admitted to our hospital for further investigation of an abnormal shadow in his chest X-ray. He had cafe-au-lait spots and multiple subcutaneous neurofibromas and was diagnosed as having von Recklinghausen's disease. Bronchofiberscopy was performed, but an adequate specimen was not obtained. Therefore, percutaneous needle biopsy was performed, and the specimen showed poorly-differentiated adenocarcinoma. The left subclavian artery was deviated on aortography, therefore, neoadjuvant chemotherapy with CDDP & VDS was performed. He subsequently underwent left upper lobectomy. Pathologically, the tumor cell showed necrosis and scarring. Including this case, there have been 11 reports of von Recklinghausen's disease associated with lung cancer in the Japanese literature. Adenocarcinoma was observed in 72.9% of cases, and poorly-differentiated tumor was observed in 7 out of 8 patients with distinct tumor differentiation.

Adenocarcinoma↗
PubMed1991

Palmitoylation of cysteine 69 from the COOH-terminal of band 3 protein in the human erythrocyte membrane. Acylation occurs in the middle of the consensus sequence of F--I-IICLAVL found in band 3 protein and G2 protein of Rift Valley fever virus.

One of the major physiologic functions of erythrocytes is the mediation of chloride-bicarbonate exchange in the transport of carbon dioxide from the tissues to the lungs. The anion exchange is mediated by a typical polytopic transmembrane protein in the cell membrane, designated Band 3. A carboxyl-terminal peptide of Band 3 was affinity-labeled with pyridoxal phosphate, a substrate for the anion transport system, and then sequenced (Kawano, Y., Okubo, K., Tokunaga, F., Miyata, T., Iwanaga, S., and Hamasaki, N. (1988) J. Biol. Chem. 263, 8232-8238). The 10th amino acid residue of the peptide could not be determined, suggesting post-translational modification of the residue. In the present communication, we have investigated the molecular structure of human Band 3 and the COOH-terminal 8500-dalton peptide using gas-liquid chromatography-mass spectrometry. Band 3 was modified covalently by fatty acids and these acids were released from Band 3 by hydroxylamine treatment at either pH 7 or 11, indicating that the linkage between Band 3 and the fatty acid is a thio ester bond. 1 mol of Band 3 interacted with 1 mol of fatty acid at a cysteine residue located 69 residues from the COOH terminus of Band 3. The fatty acids used in the modification were myristate, palmitate, oleate, and stearate, with palmitate being the major component. The esterified site is close to the site affinity-labeled with pyridoxal phosphate (Kawano, Y., Okubo, K., Tokunaga, F., Miyata, T., Iwanaga, S., and Hamasaki, N. (1988) J. Biol. Chem. 263, 8232-8238). The amino acid sequence including the acylation site was Phe-Thr-Gly-Ile-Gln-Ile-Ile-Cys-Leu-Ala-Val-Leu, which is conserved in the G2 protein of Rift Valley fever virus as Phe-Ser-Ser-Ile-Ala-Ile-Ile-Cys-Leu-Ala-Val-Leu. The G2 protein, like Band 3, is a polytopic transmembrane protein. Although acylation of the cysteine residue of G2 protein has not been examined, the Phe-X-X-Ile-X-Ile-Ile-Cys-Leu-Ala-Val-Leu sequence could be a common motif for fatty acylation of certain membrane proteins.

Acylation↗
PubMed1991

Production and effect of infectious Dane particles in transgenic mice.

We have demonstrated by immunoelectron microscopy that 42-nm particles with double-shelled structures characteristic of Dane particles are present in the serum of transgenic mice, 1.2HB-BS 10, carrying partly duplicated hepatitis B virus (HBV) genome. Furthermore, these particles were shown to infect primary human fetal hepatocytes as demonstrated by the elevation of HBV surface antigen (HBsAg) in the culture medium. HBV DNA is known to be expressed in a liver- and kidney-specific manner in the adult mouse, so we examined the developmental expression of viral antigens. In the liver, viral antigens (HBsAg and HBV e antigen) began to be expressed before birth and the level of expression showed a sharp rise after birth. On the other hand, in the kidney, viral antigens began to be expressed after birth. Serum levels of viral antigens were roughly proportional to the levels of expression in the liver, suggesting that the liver is the main source for viral antigens in the serum. None of these transgenic mice produced anti-HBs or anti-HBV core response or showed biochemical or pathological change up to at least 24 months of age. All these results suggest that infectious viral particles can be produced in transgenic mice, and that expression and replication of HBV DNA are not toxic in vivo.

Aging↗
PubMed1991

Changes in nasal metachromatic cells during allergen immunotherapy.

We have investigated changes of nasal metachromatic cell number, nasal symptoms and nasal provocation at the third and sixth month during allergen immunotherapy. Twenty-five subjects with perennial allergic rhinitis (house dust (23), Alternaria (2) were divided into two groups: an immunotherapy-treated group (n = 14) and a control group (n = 11). At the first visit nasal symptom scores, nasal provocation reactions and the number of metachromatic cells in nasal mucosal epithelial scrapings were not significantly different between groups. At the third and sixth month after immunotherapy nasal symptom scores, nasal provocation and the metachromatic cells in epithelial scrapings were significantly reduced (P less than 0.05) compared with the pretreatment values in the immunotherapy group, but unchanged in the control group. These results suggest that the reduction in metachromatic cell number at the nasal mucosal surface may be one of the mechanisms which could explain the improvement of nasal allergic symptoms by immunotherapy.

Adolescent↗
PubMed1991

Bullous pemphigoid antigen expression in Pam 212 cells induced by the addition of platelet activating factor.

Platelet activating factor (Paf-acether) is a phospholipid which has various activities including platelet and neutrophil aggregation and eosinophil chemotaxis. We have previously reported that the blister fluids of bullous pemphigoid possess platelet aggregation activity and suggested that Paf-acether might be concerned with the accumulation and activation of neutrophils and eosinophils. In this study, we examined the influence of Paf-acether on BP antigen expression on Pam 212 cells. Paf-acether enhanced the expression of BP antigen on Pam 212 cells and this expression was blocked by Paf-acether antagonist. Our observations might suggest that Paf-acether contributes to the blister formation not only by the activation of inflammatory cells but the enhancement of BP antigen.

Animals↗
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

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↗
PubMed1991

A novel system for large-scale sequencing of cDNA by PCR amplification.

We have developed a method for constructing a library containing the 3' end fragment of cDNA for large-scale sequencing of cDNA clones. The average size of the insert was 270 bp. Cell lysates that carry plasmids having the cDNA insert were subjected to PCR amplification of the cDNA moiety and the products were subjected to sequencing analysis using an autosequencer. With this protocol, sample preparation became a non-limiting step, that allowed us to sequence as many samples as the autosequencer could handle.

Base Sequence↗
PubMed1991

Purification and some properties of soybean saponin hydrolase from Aspergillus oryzae KO-2.

We had investigated the enzymatic hydrolysis of soybean saponins and selected soybean saponin hydrolase from Aspergillus oryzae KO-2. We attempted purification of this enzyme for further characterization. This enzyme was purified 1500-fold using ammonium sulfate fractionation and Sephadex G-200 gel filtrations. The enzyme was electrophoretically homogeneous and a glycoprotein by PAS staining. By gel filtration, the molecular weight of enzyme was 158,000 and SDS-PAGE showed the enzyme to have a tetrameric structure composed of heterogeneous subunits of 35,000 and 45,000. The enzyme activity was stable at temperatures below 40 degrees C and stable from pH 5.0 to 8.0. The optimum pH was pH 4.5 to 5.0 and the optimum temperature was 50 degrees C. The Km and Vmax for soyasaponin I were 0.48 mM and 9.8 mumol/hr mg protein, respectively. After hydrolysis with the enzyme, soyasapogenol B and alpha-L-rhamnopyranosyl (1----2)-beta-D-galactopyranosyl (1----2)-D-glucuronopyranoside were released from soyasaponin I.

Aspergillus oryzae↗