Biomedical subjects

M Ohtsuki

Publications and source records attributed to M Ohtsuki.

At least 73 records · Page 4Linked to original sources

PubMed1995

[A case of interstitial pneumonia in polymyositis difficult to distinguish from gold pneumonitis].

Rheumatoid arthritis was diagnosed in a 48-year-old woman. She received a gold compound, and 4 weeks after the start of that therapy, interstitial pneumonia appeared. Findings from a muscle biopsy, and high serum CPK and LDH levels indicated that she suffered from polymyositis rather than rheumatoid arthritis. The result of a drug lymphocyte stimulation test (DLST) for the gold compound was more than 200%. Because the usefulness of the DLST for the gold compound in the diagnosis of gold pneumonitis is not thoroughly established, the DLST was also done in patients with rheumatoid arthritis who were receiving the gold compound without side effects, and in normal subjects. Many of the rheumatoid arthritis patients and some of the normal subjects had a positive response to the gold compound. Therefore a positive response on the DLST for the gold compound does not always support the diagnosis of gold pneumonitis.

Antirheumatic Agents↗

PubMed1995

[The effect of dopamine and prostaglandin E1 on urine oxygen tension (PuO2)].

We reported that PuO2 reflects renal medullary perfusion and decreases during N2O-O2 isoflurane (GOI) or sevoflurane (GOS) anesthesia. In the present study, we examined the effect of dopamine (DOA) or prostaglandin E1 (PGE1) on PuO2 during GOI anesthesia. Twenty four patients from elective surgery with GOI anesthesia were randomly divided into three groups, i.e. control group (n = 8), DOA group (n = 8) and PGE1 group (n = 8). PuO2 decreased significantly in the control group, while in the DOA and PGE1 groups, PuO2 was unchanged. These results suggest that DOA and PGE1 maintain renal medullary perfusion under GOI anesthesia.

Adolescent↗

PubMed1994

Disease-activated transcription factor: allergic reactions in human skin cause nuclear translocation of STAT-91 and induce synthesis of keratin K17.

Epidermal keratinocytes have important immunologic functions, which is apparent during wound healing, in psoriasis, and in allergic and inflammatory reactions. In these processes, keratinocytes not only produce cytokines and growth factors that attract and affect lymphocytes but also respond to the polypeptide factors produced by the lymphocytes. Gamma interferon (IFN-gamma) is one such signaling polypeptide. Its primary molecular effect is activation of specific transcription factors that regulate gene expression in target cells. In this work, we present a molecular mechanism of lymphocyte-keratinocyte signaling in the epidermis. We have induced cutaneous delayed-type hypersensitivity reactions that are associated with an accumulation of lymphocytes. These resulted in activation and nuclear translocation of STAT-91, the IFN-gamma-activated transcription factor, in keratinocytes in vivo and subsequent induction of transcription of keratin K17. Within the promoter of the K17 keratin gene, we have identified and characterized a site that confers the responsiveness to IFN-gamma and that binds the transcription factor STAT-91. Other keratin gene promoters tested were not induced by IFN-gamma. These results characterize at the molecular level a signaling pathway produced by the infiltration of lymphocytes in skin and resulting in the specific alteration of gene expression in keratinocytes.

Base Sequence↗

PubMed1994

Molecular effects of T lymphocytes on the regulation of keratin gene expression.

The interactions between lymphocytes and the epidermis are very important in autoimmune skin diseases. Mutual interaction between keratinocytes and T cells is effected both by soluble peptides and by direct cell-to-cell contact. We investigated the possibility that direct cell-to-cell contact with T cells may also play a role in the regulation of keratin gene expression. We have transfected human epidermal keratinocytes with the constructs containing promoters of keratin genes and then cocultured them with the HUT78 strain of human T cells. We found that T cells induce transcription of K5, K6, K14 and K16 genes, as well as the RSV viral promoter, but not K17, K10 or the SV40 viral promoter controls.

Cell Communication↗

PubMed1994

[Changes in urine oxygen tension (PuO2) during anesthesia with isoflurane and sevoflurane].

Leonhardt and coworkers have suggested that PuO2 may indicate degree of renal medullary perfusion and function. The changes in PuO2 during N2O-O2-isoflurane anesthesia (GOI) and N2O-O2-sevoflurane anesthesia (GOS) were studied in 20 patients (GOI group: 10 cases, GOS group: 10 cases) who underwent elective surgeries. In the GOI group, PuO2 decreased significantly 30 and 60 minutes after the beginning of surgical incision, and it returned to the previous value immediately after the cessation of isoflurane. In the GOS group PuO2 decreased starting 30 minutes after the beginning of surgical incision until 10 minutes after the cessation of sevoflurane. These results suggest that isoflurane and sevoflurane administration caused a reduction in renal medullary perfusion, and that the low perfusion during sevoflurane anesthesia lasted longer than during isoflurane anesthesia. Measurement of PuO2 has a number of problems, but we believe that PuO2 is useful as an indicator of renal medullary blood flow.

Adult↗

PubMed1993

Epidermal growth factor and transforming growth factor alpha specifically induce the activation- and hyperproliferation-associated keratins 6 and 16.

Epidermal injury results in activation of keratinocytes which produce and respond to growth factors and cytokines and become migratory. Activated keratinocytes express a specific pair of keratin proteins, K6 and K16, distinct from the keratins in the healthy epidermis. Keratinocytes can be activated, for example, by binding of the appropriate ligands to the epidermal growth factor receptor (EGFR). We have analyzed the effects of EGFR activation on keratin gene transcription by transfecting DNAs containing keratin promoters linked to a reporter gene into primary cultures of human epidermal keratinocytes in the presence or absence of EGF or transforming growth factor alpha (TGF alpha), two growth factors that activate EGFR. The activation of EGFR had no effect on the promoters of simple epithelial, basal-layer-specific, or differentiation-specific keratins. In contrast, the expression of K6 and K16 was strongly and specifically induced. A 20-bp DNA segment of the K16 gene promoter conveyed the EGF regulation, functioned in a heterologous construct, and therefore constituted an EGF-responsive element. A nuclear protein specifically bound to this element and to the analogous sequence of the K6 promoter. Thus, EGF specifically induces K6 and K16, markers of activated keratinocytes, via nuclear proteins that bind to EGF-responsive elements in the promoters of these keratin genes.

Base Sequence↗

PubMed1993

Negative regulation of G1 in mammalian cells: inhibition of cyclin E-dependent kinase by TGF-beta.

Transforming growth factor-beta (TGF-beta) is a naturally occurring growth inhibitory polypeptide that arrests the cell cycle in middle to late G1 phase. Cells treated with TGF-beta contained normal amounts of cyclin E and cyclin-dependent protein kinase 2 (Cdk2) but failed to stably assemble cyclin E-Cdk2 complexes or accumulate cyclin E-associated kinase activity. Moreover, G1 phase extracts from TGF-beta-treated cells did not support activation of endogenous cyclin-dependent protein kinases by exogenous cyclins. These effects of TGF-beta, which correlated with the inhibition of retinoblastoma protein phosphorylation, suggest that mammalian G1 cyclin-dependent kinases, like their counterparts in yeast, are targets for negative regulators of the cell cycle.

Animals↗

PubMed1993

Transcriptional regulators of expression of K#16, the disease-associated keratin.

In most malignant and benign skin diseases, the normal pattern of keratin expression is altered. Among other phenotypic changes, the expression of hyperproliferation- and activation-associated keratins K#16 and K#6 is induced. Because the molecular mechanisms and the nuclear regulators involved in this induction are unknown, we have characterized the transcriptional regulators of expression of the keratin K#16 promoter. Our previous studies have shown that the transcription of K#16 is strongly and specifically induced in epidermal keratinocytes by epidermal growth factor (EGF), through the EGF-responsive element (RE). In the present work, using an electrophoretic mobility-shift assay, we have found several nuclear protein binding sites that have been identified as an Sp1 site, an AP2 site, the EGF-RE, and an enhancer element. The function of each site was assessed in transfection assays using specific deletions. Both the Sp1 and EGF-RE sites are essential for K#16 promoter activity. The site that functions as an independent enhancer, E, was found adjacent to and interacting with a sequence recognized by the AP2 transcription factor. This knowledge of the nuclear regulators of expression of the disease-associated K#16 keratin provides insight into the molecular parameters that might be important in skin diseases.

Base Sequence↗

PubMed1993

A cluster of five nuclear proteins regulates keratin gene transcription.

A common feature of all epithelial cells is the presence of keratin proteins that assemble into an intermediate filament cytoskeletal network. Whereas other cell types often use a specific master transcription factor to coordinate cell type-specific transcription, analysis of transcriptional regulation of keratin genes suggests that specific groupings of widely expressed transcription factors, acting on clusters of recognition elements in the promoter regions, confer epithelia-specific transcription. We define such a cluster of three sites that binds five transcription factors in the human K5 keratin gene. Within this cluster, an unusual Sp1 site binds the Sp1 transcription factor and two additional proteins. Flanking the Sp1 site are an AP2 site and another sequence, Site A; each binds a transcription factor. Similar clusters of recognition sites for the same five transcription factors have been also identified in other keratin genes. Such clusters may play a role in epithelia-specific expression of keratins.

Base Sequence↗

PubMed1993

On the role of AP2 in epithelial-specific gene expression.

Transcription factor AP2 plays an important role in transcription of keratin genes, and it has been suggested that AP2 confers epithelial specificity. Promoters of keratin genes contain AP2 sites, usually within tight clusters of binding sites for other nuclear transcription factors. The role of AP2 was examined by in vitro gel shift analysis, AP2 binding site mutagenesis, and stable and transient transfection experiments. Nonepithelial cells, such as GM10 fibroblasts and melanocytes, neither express keratin nor become phenotypically epithelial when transfected with an AP2-expressing vector. However, in 3T3 and HeLa cells, co-transfection of an AP2-expressing vector increases the level of transcription from keratin gene promoters. This increase requires an intact AP2 binding site. Thus, the role of AP2 in keratin gene expression is quantitative rather than qualitative. AP2 interacts with other transcription factors and may convey extracellular regulatory signals to the transcription complex in the promoters of keratin genes.

3T3 Cells↗

PubMed1992

TGF-beta receptors.

The nature and role of cell surface proteins that bind members of the TGF-beta family has been investigated. TGF-beta, activins, and BMPs each bind to receptors of 55 kDa (type I) and 70 kDa (type II). In the TGF-beta system, these receptors are implicated in the mediation of multiple responses. A member of the type II receptor family has been cloned that encodes four alternatively spliced versions of a transmembrane serine/threonin kinase receptor related to the recently cloned mouse activin receptor and C-elegans daf-1 gene. Inhibitors of serine/threonine kinase activity block transcriptional and growth inhibitory responses to TGF-beta. In addition to the signaling receptors, many cell types express the TGF-beta binding proteoglycan betaglycan. Betaglycan has been purified, molecularly cloned, and shown to bind TGF-beta via its core protein and basic fibroblast growth factor via its heparan sulfate chains. In addition to receptors I and II and betaglycan, some cells express a newly identified set of membrane proteins that specifically bind either TGF-beta 1 or TGF-beta 2. Three of the four isoform-restricted binding proteins are bound to the membrane via phospholipid anchors. Like betaglycan, these proteins might function to regulate the interaction between TGF-beta and their target cells.

Amino Acid Sequence↗

PubMed1992

Losartan, a specific angiotensin II receptor antagonist, increases angiotensin I and angiotensin II release from isolated rat hind legs: evidence for locally regulated renin-angiotensin system in vascular tissue.

The effect of Losartan (10(-9) to 10(-6) M) on angiotensins I and II release was examined in isolated hind legs perfused with Krebs-Ringer solution from normal and bilaterally nephrectomized rats. Losartan increased dramatically both angiotensins I (Ang I) and II (Ang II) release in a dose-dependent fashion; the maximal percent increment in Ang I and Ang II release evoked by Losartan (10(-6) M) was about +380% and +160%, respectively, in normal rat hind legs. In nephrectomized animals, Losartan elicited a marked increase in both peptides dose-dependently. There was a highly positive correlation between the released amounts of Ang I and that of Ang II altered by Losartan in either normal (r = 0.954) or nephrectomized rats (r = 0.923). These results not only confirm the existence of a functional renin-angiotensin system in vascular tissues, but also suggest that the system is regulated by locally generated Ang II.

Angiotensin I↗

PubMed1992

Effects of losartan, a nonpeptide angiotensin II receptor antagonist, on cardiac hypertrophy and the tissue angiotensin II content in spontaneously hypertensive rats.

Losartan, a recently developed nonpeptide angiotensin II (Ang II) receptor antagonist, was administered orally to 10-week-old spontaneously hypertensive rats (SHR) for 2 weeks. Cardiac weight and tissue Ang II, as well as plasma renin activity (PRA) and Ang II, were determined. Treatment with Losartan (10 mg/kg per day) lowered blood pressure markedly. Losartan reduced significantly the left ventricular weight by 11% compared with control rats. The left ventricular Ang II content was lowered by Losartan (18.6 +/- 0.9 pg/tissue; 21.9 +/- 0.9 pg/tissue, control, p less than 0.05), whereas PRA and plasma Ang II concentration were increased by the treatment. With the control and Losartan-treated animals, there was a significant positive correlation between the left ventricular weight and the tissue Ang II content (r = 0.563, p less than 0.05). These results provide evidence that cardiac tissue Ang II, rather than circulating Ang II, plays an important role in the pathophysiology of left ventricular hypertrophy of this animal model of human hypertension.

Analysis of Variance↗

PubMed1992

Nuclear proteins involved in transcription of the human K5 keratin gene.

Keratin K5 is expressed in the basal layer of stratified epithelia in mammals and its synthesis is regulated by hormones and vitamins such as retinoic acid. The molecular mechanisms that regulate K5 expression are not known. To initiate analysis of the protein factors that interact with the human K5 keratin gene upstream region, we have used gel-retardation and DNA-mediated cell-transfection assays. We found five DNA sites that specifically bind nuclear proteins. DNA-protein interactions at two of the sites apparently increase transcription levels, at one decrease it. The importance of the remaining two sites is, at present, unclear. In addition, the location of the retinoic acid and thyroid hormone nuclear receptor action site has been determined, and we suggest that it involves a cluster of five sites similar to the consensus recognition elements. The complex constellation of protein binding sites upstream from the K5 gene probably reflects the complex regulatory circuits that govern the expression of the K5 keratin in mammalian tissues.

Base Sequence↗

PubMed1992

Regulation of epidermal keratin expression by retinoic acid and thyroid hormone.

In the epidermis, retinoic acid (RA) is known to regulate the gene expression of keratins, the intermediate filament proteins of epithelial cells. We have cloned the upstream regulatory regions of three human epidermal keratin genes, K5, K10, and K14, and engineered DNA constructs in which these regions drive expression of the CAT reporter gene. By co-transfecting the constructs into various epithelial cell types along with the vectors expressing the nuclear receptors for RA and thyroid hormone (T3), we have shown that RA and T3 directly regulate expression of these three keratin genes through the action of their nuclear receptors. In this paper, we review our previous results to stress that RA has a dual effect on keratin expression in epidermis: both direct and indirect. We also analyze the DNA sequences upstream from those three RA-regulated keratin genes and identify the clusters of degenerate consensus half-site motifs, which may comprise the putative retinoic acid recognition elements (RAREs). Furthermore, our recent results concerning the regulation of K5 and K14 expression by the RA receptor are also shown; these confirm our predictions regarding the location of the RAREs in epidermal keratin genes.

Base Sequence↗

PubMed1992

Evidence for the involvement of protein kinase activity in transforming growth factor-beta signal transduction.

Transforming growth factor-beta 1 (TGF-beta 1) rapidly increases the expression of junB transcription factor and plasminogen activator inhibitor-1 (PAI-1) and prevents the cell cycle-dependent phosphorylation of the RB retinoblastoma susceptibility gene product during late G1 phase in Mv1Lu lung epithelial cells. These responses are shown in this report to be blocked by the potent serine/threonine protein kinase inhibitor, H7, added with TGF-beta 1. Added alone, H7 does not alter the basal junB or PAI-1 mRNA levels, the deposition of PAI-1 into the extracellular matrix, or the phosphorylation of RB in late G1 phase, suggesting that this inhibitor does not have a general nonspecific effect on the cell. The analogs H8 and H9, which are preferential inhibitors of cyclic nucleotide-dependent protein kinases, are fivefold less potent than H7 as inhibitors of the TGF-beta response. The PAI-1 response to TGF-beta 1 is not affected by the simultaneous addition of staurosporine, which is a protein kinase C inhibitor, or by the prolonged preincubation of cells with phorbol 12-myristate 13-acetate, which down-regulates protein kinase C. The results suggest the possibility that H7 and its analogs block various early TGF-beta responses by inhibiting a protein serine/threonine kinase(s).

Animals↗

PubMed1991

Responsiveness to interleukin 4 and interleukin 2 of peripheral blood mononuclear cells in atopic dermatitis.

Although the pathogenesis of atopic dermatitis (AD) is unknown, many immunologic abnormalities such as high levels of serum IgE and increase of IgE Fc receptor-positive lymphocytes have been demonstrated. Recently, interleukin 4 (IL-4) has been shown to induce enormously the production of IgE and to enhance the expression of IgE Fc receptor by B cells, suggesting the possible involvement of IL-4 in the pathogenesis of AD. We examined IL-4 responsiveness or interleukin 2 (IL-2) responsiveness of peripheral blood mononuclear cells of 31 patients with AD, 19 healthy individuals, and seven patients with other skin diseases. We found that IL-4 responsiveness of AD was higher than that of non-AD control, although IL-2 responsiveness of AD showed no significant change. However, the value of the IL-4 responsiveness did not significantly correlate with the clinical severity, personal history of respiratory allergy, serum IgE level, or clinical course of patients with AD. The hyperresponsiveness to IL-4 detected in AD was not likely to be due to the effects of steroids or anti-mast cell drugs because the value of IL-4 responsiveness was significantly low, compared to AD, in patients with other skin diseases who were treated similarly. Because the T-cell-enriched population, but not the B-cell-enriched population, showed significant proliferation in response to exogenous IL-4 or IL-2, T cells were the main population that reacted in our proliferation assay. These results indicate that IL-4-driven proliferative response may be efficiently operative in T cells in patients with AD.

B-Lymphocytes↗

PubMed1990

Membrane fusion events during endocytosis in mouse kidney tubule cells detected by rapid freezing followed by freeze-substitution.

Membrane fusion events during endocytosis were examined in renal proximal tubule cells processed by rapid freezing followed by freeze-substitution. An extensive fusion site of the membranes between two apical vacuoles or a vacuole and a lysosome, which appeared as a pentalaminar structure, was not observed in this study, though such a pentalaminar structure has been found in chemically fixed specimens. In vitro experiments using subcellular fractions revealed that the pentalaminar structure did not always represent the initial stage of membrane fusion. Membrane fusion appeared to occur in a specific membrane site, wHere a minute pore connecting the two lumens was formed immediately after the two membranes came into contact with each other. Some pore necks showed an asymmetrical feature which consisted of a sharp corner and a gently curved corner. Enlargement of the pore appears to be mediated by a fibrous structure observed near the sharp corner of the pore neck.

Animals↗