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Biomedical subjects

T Iwata

Publications and source records attributed to T Iwata.

At least 235 records · Page 13Linked to original sources
PubMed1992

Renal and extra-renal renin gene expression in spontaneously hypertensive rats.

To study the effect of antihypertensive therapy on the regulation of renin gene expression, the levels of tissue renin messenger RNA (mRNA) were measured after treatment with a calcium channel blocker (manidipine hydrochloride 3 mg/kg/day) or an angiotensin-converting enzyme inhibitor (delapril hydrochloride 30 mg/kg/day), administered orally for 1 week, in spontaneously hypertensive rats (SHR). Male SHR, aged 15 weeks old, were used in this study (n = 5 per group). Control rats were administered the vehicle alone. Tissue total RNA was isolated from kidney, adrenal gland, heart, and brain tissue, and tissue RNA was reverse-transcribed to complementary DNA (cDNA), which was specifically amplified by polymerase chain reaction with labeled-primers for the rat renin gene. The radioactivity of the cDNA products was measured directly. Although delapril increased plasma renin activity (PRA) about 5-fold compared with the control group, manidipine did not change PRA. The kidney renin mRNA content was increased about 6-fold by treatment with delapril. Manidipine and delapril significantly decreased the renin mRNA content in the heart (p < 0.01 and p < 0.05, respectively). The level of renin mRNA in the adrenal gland and brain tissues was not significantly changed by treatment with either drug. These results suggest that tissue renin gene expression in SHR is regulated by a tissue-specific process independent of the circulating renin-angiotensin system.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

Renin gene restriction fragment length polymorphisms in a Japanese family with a high incidence of essential hypertension.

1. Human renin gene restriction fragment length polymorphisms (RFLP) were compared in a Japanese family which has a high incidence of essential hypertension. 2. RFLP of human renin gene were observed in three restriction enzymes, Mbo I, Bgl I and Hind III; 1.4 kb and 1.0 kb [Mbo I], 5.0 kb and 9.0 kb [Bgl I] and 9.0 and 6.2 kb [Hind III]. 3. Plasma renin activity was not associated with blood pressure. 4. Renin gene RFLP were not cosegregated with essential hypertension in this Japanese family.

Adult↗
PubMed1992

[Proposal of a new classification of adult bronchial asthma--child onset asthma, adult onset asthma and adult relapse asthma. Project Team for Research into Adult Bronchial Asthma in Japan].

The first nationwide research into adult bronchial asthma in Japan proposed a new classification of adult asthma. Adult asthma was categorized into child onset asthma, adult onset asthma and adult relapse asthma. The frequency of child onset asthma, adult onset asthma and adult relapse asthma in adult asthma was 11.2%, 77.3% and 3.7%, respectively. The frequency of child onset asthma decreased markedly in the older age group. On the other hand, the frequency of adult onset asthma increased, and reached more than 90%, in the older age group. The frequency of the following factors: atopic asthma, complications with other atopic diseases, mild asthma, male patients, experience of mechanical ventilation, visits to night clinics and oxygen therapy on acute attack, was significantly higher in the child onset asthma group than in the adult onset asthma group. The frequency of infectious type, aspirin intolerance, steroid dependent asthma, severe asthma and regular medication was significantly higher in the adult onset asthma group. Adult relapse asthma seemed to fall between these two groups. Based on the above observations, we proposed a new classification of adult asthma which includes child onset asthma, adult onset asthma and adult relapse asthma.

Asthma↗
PubMed1992

X-linked retinitis pigmentosa: functional phenotype of an RP2 genotype.

Rod- and cone-mediated function was studied with psychophysics and electroretinography in members of an X-linked retinitis pigmentosa pedigree with the RP2 genotype. An asymptomatic hemizygote with an early stage of the disease had cone dysfunction in the mid-periphery and an abnormal cone electroretinogram (ERG); rod function was normal. Hemizygotes with more advanced disease had cone and rod dysfunction in the mid-peripheral retina and cone dysfunction in the far periphery; cone and rod ERGs were abnormal. At very advanced stages, there was an absolute mid-peripheral scotoma and marked cone and rod dysfunction in the far peripheral and central retina. Cone and rod ERGs were severely abnormal or not detectable. Heterozygotes showed tapetal-like reflexes, patches of pigmentary retinopathy, and a range of functional findings from no detectable abnormalities to moderate levels of retinal dysfunction. There were regions of normal function adjacent to dysfunctional patches that had greater cone than rod sensitivity losses or comparable cone and rod losses. The results suggest that the phenotype of this RP2 genotype of X-linked retinitis pigmentosa, unlike other forms of retinitis pigmentosa, is first expressed as a cone photoreceptor system dysfunction, and as the disease progresses, both rod and cone systems are involved.

Adult↗
PubMed1992

Impairment of baroreceptor reflex in patients with phaeochromocytoma.

We examined the baroreceptor reflex sensitivity (BRS) in two patients with adrenal phaeochromocytoma because of their wide BP fluctuations. These patients showed greatly reduced values for BRS, which returned to normal with marked improvements of BP fluctuations soon after the removal of phaeochromocytoma. In these patients, circulating blood volume was normal and episodic rises in BP occurred without detectable increases in plasma catecholamines. From these observations, a marked impairment of baroreceptor function is considered to be one of the determinants for the wide BP fluctuation in patients with phaeochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1992

Histologic features of the carotid artery trifurcation in thoroughbreds.

The common, external, and internal carotid and occipital arteries were examined histologically at the trifurcation of the common carotid arteries in 13 Thoroughbred foals (0 to 30 days old) and 64 Thoroughbred adults (2 to 4 years old). Calcification in the media of the common carotid and external carotid arteries was observed in 3 of the 13 foals and in 30 of the 64 adult horses. Calcification resembled that seen in Mönckeberg's arteriosclerosis in human beings, the cause of which is unknown.

Animals↗
PubMed1991

Quantitative measurement of extra-renal renin mRNA by polymerase chain reaction.

We established a simplified method of the quantitative measurement of extra-renal renin messenger RNA using polymerase chain reaction system. We could detect the renin messenger RNA in the kidney, heart, aorta and adrenal gland from a single RNA sample obtained from a Wistar-Kyoto rat. In the kidney, heart, aorta and adrenal gland, the contents of renin messenger RNA were found to be 55.8 +/- 17.8, 0.15 +/- 0.05, 0.11 +/- 0.03 and 0.16 +/- 0.07 pg/micrograms of total RNA (n = 5, mean +/- s.d.), respectively. The present method is very useful to study the extra-renal renin-angiotensin system.

Adrenal Glands↗
PubMed1991

Structure of the bovine atrial natriuretic peptide receptor (type C) gene.

The bovine gene encoding the type C atrial natriuretic peptide (ANP) receptor was isolated and characterized. The gene appears to exist as a single copy in the haploid genome and is comprised of eight exons distributed over more than 85 kilobases. The transcription start site was identified by primer extension and ribonuclease protection assay. A "TATA" box-like sequence was found just upstream of the start site (at position -32); however, no CAAT box was apparent. Exon boundaries of the ANP receptor gene correlated well with the functional domain boundaries of the receptor protein; for example, exon 1 contains coding information for a large proportion of the ANP-binding domain and the transmembrane and cytoplasmic domains are encoded by separate exons, namely by exon 7 and exon 8, respectively. These structural features suggest that the organization of the ANP receptor gene reflects the domain structure of the receptor.

Amino Acid Sequence↗
PubMed1991

Significance of freshly cultured fibroblasts from different tissues in promoting cancer cell growth.

The interactions between human cancer cells and primary cultured human fibroblasts without cell-to-cell contact were investigated using double soft-agar culture. Human fibroblasts obtained from different organs were cultured in monolayers and used after the 3rd or 4th passage. In double soft-agar culture, colony formations of cancer cells in the overlayer were stimulated or inhibited by the presence of various kinds of fibroblast in the underlayer. The growth of all cancer cells tested was always stimulated by the presence of fibroblasts obtained from an organ in which cancer cells had already developed, and inhibited by those from skin. However, fibroblast-conditioned media failed to affect cancer cell growth, either in MTT assay or in soft-agar culture. These results suggest that mutual growth reliance exists between human cancer cells and primary cultured fibroblasts by diffusible factors secreted by both cells (paracrine growth) and that mutual growth enhancement occurs between cancer cells and fibroblasts derived from tissues in which cancer cells had originated.

Adenocarcinoma↗
PubMed1991

Peripheral vascular permeability following a thermal injury to the airway.

Effects of thermal injury to the airway on the vascular permeability in the region of head and neck, were studied in the canine models. The thermal airway injury was produced by an inhalation of a gas burner's flame through the metallic tracheostomy cannula. The changes in vascular permeability were evaluated by calculating the reflection coefficient, which was obtained by the protein washdown technique into lymph. The reflection coefficient after the flame inhalation did not show any increases, while it increased significantly after a histamine infusion into the carotic artery. We concluded, that the vascular permeability in the unburned area does not increase at least in the first 3 hr after a thermal injury to the airway.

Journal Article↗
PubMed1991

Kidney renin gene expression after renin inhibition in the marmoset.

1. The effects of renin inhibitor ES-8891 on renin synthesis and its secretion by the kidney were investigated in normotensive sodium-depleted marmosets. We measured plasma renin activity, plasma immunoreactive renin concentration, plasma angiotensin II concentration and kidney renin mRNA content after oral administration of ES-8891 (60 mg day-1 kg-1) for 1 week. 2. The mean blood pressure was significantly decreased (P less than 0.01) on day 7 after oral administration of ES-8891. There was no significant change in heart rate during the administration. 3. Oral administration of ES-8891 for 1 week markedly decreased the plasma renin activity, the plasma immunoreactive renin concentration and the plasma angiotensin II concentration (to 18%, 41% and 24% of the corresponding control values; P less than 0.05 for each, n = 5). 4. The kidney renin mRNA content in ES-8891-treated marmosets was significantly lower than that in normal controls (4.2 +/- 3.5 versus 12.8 +/- 5.5 pg/micrograms of total RNA, means +/- SD, P less than 0.05, n = 5). 5. Oral administration of the renin inhibitor ES-8891 for 1 week not only inhibited plasma renin activity but also decreased renin synthesis and its secretion by the kidney.

Angiotensin II↗
PubMed1991

Bifunctional atrial natriuretic peptide receptor (type A) exists as a disulfide-linked tetramer in plasma membranes of bovine adrenal cortex.

Type A atrial natriuretic peptide (ANP) receptor was demonstrated to be present as a tetramer in the bovine adrenal cortex. Type A ANP receptor is composed of two functional domains, namely extracellular ANP-binding and cytoplasmic guanylate cyclase domains, and generally considered to be present as a single polypeptide chain of about 140 kDa based on its primary structure deduced from the cDNA sequence and its SDS/PAGE profile under reducing conditions. Characterization of the type A receptor or receptor/cyclase under non-reducing conditions led to the discovery stated in the title. The type A ANP receptor was partially purified from bovine adrenal cortex membranes by Blue-Sepharose and GTP-agarose chromatography. SDS-PAGE analysis of the receptor preparation revealed that although under reducing conditions it migrated as a 140-kDa band, the mobility of the receptor was greatly retarded in the absence of reducing agents, suggesting that the type A ANP receptor is present as a disulfide-linked oligomer in its native state. Further analysis using SDS-polyacrylamide-agarose gels suitable for determining the sizes of high-molecular-weight proteins revealed that the oligomer has an Mr of 500,000-550,000. This result clearly indicates that the native form of the type A receptor is a tetramer composed of four 140-kDa disulfide-linked receptor/cyclase molecules.

Adrenal Cortex↗
PubMed1991

A novel in vitro chemosensitivity test using materials collected by endoscopic biopsy.

The usefulness of chemosensitivity testing of cells collected by endoscopic biopsy using the adenosine triphosphate assay (ATP assay) was investigated for esophageal tumors. Correlation between this chemosensitivity test and other chemosensitivity tests was more than 80% in most combinations. The predictive rate of clinical sensitivity was 77.8% and of clinical resistance was 68.8%. The predictive accuracy was 72.0%. These results will extend the indication and usefulness of chemosensitivity testing in inoperable and preoperable cases.

Adenosine Triphosphate↗
PubMed1991

Amyloid enhancing factor (AEF). Isolation and biochemical and pathological characteristics.

Neutrophils and spleens were prepared from mice after treatment to induce amyloid deposition. The deposition of amyloid was accelerated in normal recipients by intravenous injection of more than 2 x 10(4) neutrophils, and intraperitoneal injection of supernatants obtained by homogenization and centrifugation of the neutrophils and spleens. The supernatants were subjected individually to DEAE ion-exchange chromatography. Amyloid enhancing factor (AEF) activity was present in peaks eluted at an NaCl concentration of 0.17 M. The fractions containing AEF were subjected to high-performance liquid chromatography (HPLC), and AEF was eluted at a position corresponding to about 15 KDa. Purified AEF was analyzed by amino acid sequencing and gas chromatography. The N-terminal amino acid was blocked, and AEF contained some saccharides including glucose, mannose, galactosamine and sialic acid, and an undefined substance (probably derived from certain proteins). Immunoelectron microscopy by the pre-embedding method using an anti-AEF antiserum demonstrated that the cytosol, but not primary and specific granules in neutrophils from the spleen of amyloid-laden mice, reacted with the antiserum. These findings suggest that AEF is a glycoprotein associated with neutrophils.

Amino Acid Sequence↗
PubMed1991

[Simple and efficient method for clinical isolation of Bordetella pertussis].

Commercially available Amies transport medium with charcoal and three isolation media were tested to assess their efficiency in the clinical isolation of B. pertussis. First, the isolation rates of B. pertussis were compared between direct inoculation of nasopharyngeal specimens and inoculation after stored in Amies transport medium for 8 hours or less. The comparative isolation rates were 81% both (35 of 43 specimens from 29 patients) for direct inoculation and transport medium. Second, nasopharyngeal specimens were incubated for 5 days at 35 degrees C on the three media; Bordet-Gengou Medium (BG) with 5 micrograms of CEX per ml, Cyclodextrin Solid Medium (CSM) with 5 micrograms of CEX per ml, and Charcoal Agar with 40 micrograms of CEX per ml. The organism was detected from 44 nasopharyngeal specimens from 20 patients on at least one of the three tested media. The comparative isolation rates were 91% (40 of 44) on BG with 5 micrograms of CEX per ml, 93% (41 of 44) on CSM with 5 micrograms of CEX per ml, and 91% (40 of 44) on CA with 40 micrograms of CEX per ml. Although no differences in the isolation rates were observed among the three media, the appearance of the colonies was earlier by one day on BG than the rest of the two media. The detection of B. pertussis was occasionally easier on CA than the rest of the two because of its higher suppression for nasopharyngeal flora. CSM has its advantage in that it does not need any blood and can be prepared at anytime. Also, the shelf life of these three media proved to be at least one month when stored at 10 degrees C. We conclude that the clinical isolation of B. pertussis was highly successful with the following simple procedure: nasopharyngeal specimens stored in Amies transport medium and inoculated on one of the three media, BG, CSM, or CA, and then incubated for 5 days at 35 degrees C.

Bacteriological Techniques↗
PubMed1991

[A senile patient with Rendu-Osler-Weber disease who underwent resection of 4 multiple bilateral pulmonary arteriovenous fistulas].

A 70-year-old female patient with multiple bilateral pulmonary arteriovenous fistulas was referred to our hospital for its treatment. She had experienced frequent epistaxis and had nasopharyngeal telangiectasia. Her mother, sister and all four children also suffered from epistaxis. We diagnosed this patient as Rendu-Osler-Weber disease combined with multiple bilateral pulmonary arteriovenous fistulas. Her chest roentgenogram revealed 4 arteriovenous fistulas in the left lung and 2 arteriovenous fistulas in the right. On admission arterial blood gas analysis while breathing room air showed a PaO2 of 39.8 torr and an SaO2 of 75.4%. The percent of R-L shunt was calculated to be 56.5%. Because of severe hypoxemia, she underwent resection of four large fistulas in segments 3, 4, 5, and 8 of the left lung. Twenty-eight days after the operation, the PaO2 was 76.4 torr and SaO2 was 95.7%. There was no sign of enlargement in size of the remaining arteriovenous fistulas.

Aged↗
PubMed1991

Effect of dietary safflower phospholipid on plasma and liver lipids in rats fed a hypercholesterolemic diet.

The effect of safflower phospholipid (SP) on plasma and liver lipids in rats fed a hypercholesterolemic diet was examined. Triglyceride mixture (SPO) of safflower oil and palm oil (8:2) containing almost comparable amounts of linoleic acid to safflower phospholipid was used as a control diet. Similarly, the effect of paste safflower phospholipid (PSP) which contains approximately 45% of neutral lipid was also compared to safflower oil (SO). Concentrations of total cholesterol in plasma and liver of rats fed the SP diet were markedly decreased in comparison with those of the other diets, but a slight reduction of total cholesterol in plasma and liver was observed in rats fed PSP diet. SP and PSP induced a reduction in the plasma level of low density lipoprotein (LDL) cholesterol as well as an increase in the level of high density lipoprotein (HDL) cholesterol. The activity of plasma lecithin-cholesterol acyltransferase (LCAT) was greatly increased in rats fed SP diet. These results suggest that the safflower phospholipids suppress the elevation of plasma and liver cholesterol and that this effect may depend on the phospholipid content in dietary lipid.

Acyltransferases↗