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H Ohkubo

Publications and source records attributed to H Ohkubo.

At least 73 records · Page 4Linked to original sources
PubMed1991

Cellular localization of rat Isk protein in the stria vascularis by immunohistochemical observation.

A novel rat membrane protein, termed Isk protein, that exhibits a voltage-dependent potassium channel activity was first reported through molecular cloning combined with an electrophysiological assay (Takumi et al., 1988). In the present study, we made an attempt to identify the cellular localization of the rat Isk protein in the stria vascularis using two types of antibodies that specifically react with the distinct parts of the rat Isk protein. Immunohistochemical analysis showed that the rat Isk protein was present only on the endolymphatic surface of the marginal cell. The possibility that the Isk protein is involved in potassium permeation in the luminal membrane of the marginal cell will be also discussed.

Amino Acid Sequence↗
PubMed1991

Extracorporeal spread and its prognostic impact in stages I and II (FIGO) endometrial carcinoma.

Prognostic risk factors were statistically analyzed from the histopathologic data obtained from 90 Japanese women with stages I and II endometrial carcinoma treated surgically, including systemic retroperitoneal lymph node dissection, between June 1979 and June 1989. In stage Ia endometrial carcinoma, pelvic and paraaortic nodes metastasis were seen in 13.8(4/29)% and 0.0(0/19)% of patients, respectively. In stage Ib, the incidence of pelvic and paraaortic node metastasis was 25.6(11/43)% and 9.7(3/31)%, respectively. In stage II, the incidence was 38.9(7/18)% and 13.3(2/15)%, respectively. Prognosis of patients even with deep myometrial invasion (greater than or equal to 2/3) or G3 tumor was fairly good (5-year survival rate: 87.5% and 85.7%, respectively) if the disease was histologically confined to the uterine corpus. Once the tumor spread outside the corpus uteri, the survival rate of patients was strongly affected by the grade of the tumor, moderate to marked lymph-vascular space invasion of tumor cells, or tumor invading middle or outer third of myometrium (P less than 0.05 for each factor). In summary, endometrial cancer frequently metastasize to pelvic and paraaortic lymph nodes even in the early stages, and lymph node metastasis and other extracorporeal spread of disease have a serious impact on patient survival. Prognosis of patients with extracorporeal spread of disease seems to be determined by the high grade of tumor and lymph-vascular space invasion. These results suggest that surgical exploration including paraaortic lymph node dissection to accurately evaluate the extent of the disease is essential to estimate the patient's prognostic risk and to individualize the treatment schedule.

Female↗
PubMed1991

Intra-individual variation of skin temperature recovery rate after cold water immersion among Japanese bush-cutter operators.

Recovery rates of skin temperature after cold water immersion tests and other measurements were recorded from 1978 to 1989 to assess the effects of vibration due to the use of bush-cutters on the health of 42 road-maintenance workers having an average age of 51.7 years. Their work and health conditions were controlled and checked systematically, and the incidence of white finger in 1989 was 2%. The recovery rate as well as the initial skin temperature was influenced greatly by ambient temperature and thus direct assessment of the changes in recovery rate had little value. The intra-individual variation in recovery rates among 6 examinations ranged widely from 6.7 to 55.7%. Subjects with large variation in the recovery rate showed better results in recovery rate, skin temperature, and vibratory sensation than those with little variation. Individuals with large variation tend to respond well to changes in ambient temperature and to suspension and resumption in the use of bush-cutters, indicating the elasticity of their peripheral circulatory system.

Adult↗
PubMed1990

Cloning of a full-length cDNA encoding bovine thymus poly(ADP-ribose) synthetase: evolutionarily conserved segments and their potential functions.

The primary structure of bovine thymus poly(ADP-ribose) synthetase, as deduced from the nucleotide sequence of a cloned cDNA, indicated that this enzyme is composed of 1016 amino acids (aa) with an Mr of 113,481. An abundance of Lys and Arg residues was in accord with the known basic nature of this protein. A comparison with reported sequences of human counterparts revealed: (1) three functional domains separated by partial proteolysis, i.e., DNA-binding (N-terminal), automodification (central), and NAD-binding (C-terminal) domains, have, in this order, increasing degrees of homology; (2) the DNA-binding domain is composed of two distinct regions: one, less conserved, containing zinc-binding fingers and the other, more conserved, containing helix-turn-helix motifs; (3) all Glu and Asp residues in the automodification domain are conserved; and (4) a 78-aa stretch encompassing the nucleotide-binding fold in the NAD-binding domain is completely conserved. These results are compatible with specific features of each domain, i.e., complex DNA-enzyme interactions, multiple automodification at acidic aa residues, and a stringent specificity for the substrate, NAD.

Amino Acid Sequence↗
PubMed1990

Immunohistochemical study of a rat membrane protein which induces a selective potassium permeation: its localization in the apical membrane portion of epithelial cells.

We previously reported a novel rat membrane protein that exhibits a voltage-dependent potassium channel activity on the basis of molecular cloning combined with an electrophysiological assay. This protein, termed IsK protein, is small and different from the conventional potassium channel proteins but induces selective permeation of potassium ions on its expression in Xenopus oocytes. In this investigation, we examined cellular localization of rat IsK protein by preparing three different types of antibody that specifically reacts with a distinct part of rat IsK protein. Immunohistochemical analysis using these antibody preparations demonstrated that rat IsK protein is confined to the apical membrane portion of epithelial cells in the proximal tubule of the kidney, the submandibular duct and the uterine endometrium. The observed tissue distribution of rat IsK protein was consistent with that of the IsK protein mRNA determined by blot hybridization analysis. In epithelial cells, the sodium, potassium-ATPase pump in the basolateral membrane generates a sodium gradient across the epithelial cell and allows sodium ions to enter the cell through the apical membrane. Thus, taking into account the cellular localization of the IsK protein, together with its electrophysiological properties, we discussed a possible function of the IsK protein, namely that this protein is involved in potassium permeation in the apical membrane of epithelial cells through the depolarizing effect of sodium entry.

Amino Acid Sequence↗
PubMed1990

Generation of transgenic mice with elevated blood pressure by introduction of the rat renin and angiotensinogen genes.

The role of the renin-angiotensin system in blood pressure control and in the development of hypertension was investigated by generating transgenic mice carrying the rat renin or angiotensinogen gene or both genes under the control of the mouse metallothionein I promoter. The systolic blood pressure was significantly elevated in transgenic mice carrying both transgenes but was maintained normally in those bearing either of the transgenes. The transgene was effectively and properly transcribed to form the mature mRNA in the transgenic mice. The production of rat renin and angiotensinogen in the transgenic mice carrying the corresponding transgene was also verified by immunoanalyses of these proteins. Furthermore, the specific angiotensin-converting enzyme inhibitor captopril was effective in reducing the elevated blood pressure of the hypertensive transgenic mice. These results indicate that the combined action of the exogenous rat renin and angiotensinogen is responsible and necessary for elevation of blood pressure in the hypertensive transgenic mice.

Angiotensinogen↗
PubMed1990

Characterization of gene organization and generation of heterogeneous mRNA species of rat ISK protein.

The ISK protein is a novel, probably epithelial potassium channel which differs from conventional potassium channels in its structure, electrophysiology, and tissue distribution. In this investigation, we isolated and analyzed genomic and cDNA clones coding for the rat ISK protein to characterize the structural organization and expression pattern of the ISK protein gene. This analysis, together with primer extension and RNase protection experiments, indicated that the ISK protein mRNA is initiated from two different upstream exons and then encoded by an uninterrupted downstream exon covering the protein-coding and the 3'-untranslated regions of the mRNA. RNA blot hybridization analysis showed additional generation of several large species of mRNAs which result from inclusion of a part of the intron sequence and the 3'-flanking region of the ISK protein gene. Thus, the single ISK protein gene is involved in the production of multiple species of mRNAs through a variety of cellular mechanisms including transcription initiation at different sites, alternative RNA splicing, and polyadenylation at different sites. The heterogeneity of the ISK protein mRNAs may be associated with the emergence of the functional and regulatory diversity observed for potassium ion permeation in epithelial cells.

Animals↗
PubMed1990

Elevated angiotensinogen mRNA levels in rat liver by nephrectomy.

The expression of the angiotensinogen gene was studied in nephrectomized rats with and without adrenal glands. Angiotensinogen mRNA was measured by a sensitive radiodensitometric hybridization assay. Angiotensinogen mRNA levels in the liver increased 5 times by nephrectomy alone and 2.6 times by nephrectomy with adrenalectomy in acute experiments. Brain mRNA levels remained the same in both groups. When nephrectomy was performed 7 days after adrenalectomy, mRNA level increased by 50%. Angiotensinogen mRNA increased 5 times in the liver and 2.3 times in the brain by the administration of dexamethasone. An additive effect on liver angiotensinogen mRNA level was observed in nephrectomy with dexamethasone treatment. These results suggest that in nephrectomy, a synergetic action of glucocorticoids and other unknown factors increase hepatic angiotensinogen mRNA levels.

Adrenalectomy↗
PubMed1990

[The incidence and clinical significance of paraaortic lymph node metastases in patients with uterine cervical cancer].

Paraaortic lymph node dissection was performed in the treatment of patients with carcinoma of the cervix who were subjected to radical hysterectomy between June, 1982 and March, 1988 at the Department of Obstetrics and Gynecology, Hokkaido University Hospital, Sapporo, Japan. Thirteen out of 246 (5.3%) patients had metastases in the paraaortic lymph node. Of the patients with stage I carcinoma of the cervix, 1.0 per cent had positive paraaortic lymph node. Of the patients with stage II carcinoma, 4.9 per cent had metastases in the paraaortic lymph nodes, and of the stage III patients, 16.7 per cent had positive paraaortic lymph nodes. The incidence of paraaortic node involvement increased along with the advance of the disease. Of the patients with squamous cell carcinoma of the cervix, 4.6 per cent had paraaortic lymph node metastases. Of the patients with adenocarcinoma of the cervix including mixed carcinoma, 6.8 per cent had positive paraaortic node. All the patients with positive paraaortic lymph nodes had metastatic diseases in the pelvic nodes. In addition, the number of groups of positive pelvic nodes in the patients with positive paraaortic lymph nodes was significantly larger than that in those with negative paraaortic nodes. At the time of reporting, seven out of 13 patients with positive paraaortic lymph node have died of the disease. The mean survival period of those seven patients was 14.9 +/- 12.2 (mean +/- SD) months. Of the remaining six surviving patients, three have been doing well for more than three years.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗
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

Molecular cloning and sequence analysis of human genomic DNA encoding a novel membrane protein which exhibits a slowly activating potassium channel activity.

The amino acid sequence for a novel human membrane protein that induces selective potassium permeation by membrane depolarization was deduced by molecular cloning and sequence analysis of its genomic DNA. This protein consists of 129 amino acid residues and shares several structural characteristics with the rat counterpart. These include a single putative transmembrane domain surrounded by many charged amino acid residues, two potential N-glycosylation sites at the amino-terminal portion and a single cysteine residue at the carboxyl-terminal portion. The transmembrane domain and its flanking carboxyl-terminal sequence are highly conserved between the human and rat sequences. Because the slowly activating potassium current elicited by the human protein on its expression in Xenopus oocytes is indistinguishable from that induced by the rat protein, the sequence conserved at the transmembrane domain and its following sequence should play an essential role in the induction of selective K+ permeation.

Amino Acid Sequence↗
PubMed1989

Captopril and hydralazine suppress atrial natriuretic peptide (ANP) gene expression in the ventricles of spontaneously hypertensive rat.

We investigated the influences of captopril (CAP) and hydralazine (HYD) on the ANP mRNA level in the hypertrophied left ventricle (LV) of spontaneously hypertensive rats (SHR). Male SHRs (16 weeks of age) were given CAP (35 mg/kg/day) or HYD (3.5 mg/kg/day) for two weeks. Both drugs reduced blood pressure by a similar magnitude. Treatment with CAP caused a reduction in the ANP mRNA level in LV by 62%, and a reduction in the weight of the LV. The ANP mRNA level in LV of the HYD-treated rats was also decreased, but only by 31%. HYD did not affect LV hypertrophy. ANP gene expression in LV of SHR might be effectively suppressed by a reduction of blood pressure and also by the concomitant attenuation of hypertrophy.

Animals↗