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Biomedical subjects

T Katayama

Publications and source records attributed to T Katayama.

At least 361 records · Page 20Linked to original sources
PubMed1989

Linear alpha-human atrial natriuretic peptide analogs display receptor binding activity and inhibit alpha-hANP-induced cGMP accumulation.

We have synthesized a series of [Cys(R)7,23]alpha-hANP analogs, in which the two Cys residues were modified with various alkyl groups(R); i.e., R=Acm, Pe, Qe, Cam, Me, Ae, Bzl, Cm, Ocam and sulfo. The Acm-, Cam-, and Me-analogs exhibited binding activity as potent as alpha-hANP in rat vascular smooth muscle cells (VSMC). Binding activity of the analogs decreased progressively as the bulkiness of the R group increased. None of the analogs caused accumulation of cGMP in VSMC and vasorelaxant activity in rat aorta. Acm-, Cam- and Me-analogs substantially antagonized alpha-hANP-induced cGMP accumulation, but did not antagonize vasorelaxation induced by alpha-hANP in vitro.

Animals↗
PubMed1989

Changes in blood ketone body ratio with reference to graft viability after liver transplantation in rats.

Arterial blood ketone body ratio (acetoacetate/3-hydroxybutyrate; KBR), which reflects hepatic mitochondrial redox potential, was measured during a 2-week period after orthotopic liver transplantation in three groups of rats: group 1, the isogenic combination of LEW (RT1l) graft to LEW recipient as control; group 2, the allogenic combination of ACI (RT1a) graft to LEW recipient without immunosuppressive treatment: and group 3, the allogenic combination of ACI to LEW with immunosuppressive treatment using cyclosoporin (CyA). Isogenic recipients survived indefinitely. Allogenic recipients in group 2 had severe rejection with a mean survival of 10.3 +/- 0.54 days, while 77.8% of the allogenic recipients in group 3 survived more than 30 days. KBR of rats surviving more than 2 weeks in groups 1 and 3 gradually increased post-transplantation and was maintained at a high level. By contrast, though KBR in group 2 was restored at 3 days, it gradually fell and remained at a significantly low level (P less than 0.001). It is suggested that KBR provides an accurate indicator for evaluating metabolic viability of the critically deteriorating liver graft accompanied by sever rejection.

Animals↗
PubMed1989

Effect of hyperbaric oxygen therapy on essential haematuria.

Forty-three patients with essential haematuria were studied for 35 days to determine the efficacy of hyperbaric oxygen (OHP) exposure on haemostatic ability. Out of 15 untreated patients, haematuria persisted for the study period in all but one patient (6.7%). Out of 11 patients who received 90 mg/day of carbazochrome sodium sulfate and 750 mg/day of tranexanic acid excellent haemostatic results had been obtained in 2 (18.2%). Results of exposure of 17 patients to 2 atm. pressure of OHP for 90 min daily were excellent in 10 (58.8%) and good in one (5.9%). No serious adverse effects had been noted following OHP treatment. These results indicate that OHP can be applied for the treatment of essential haematuria if routine haemostatic drugs fail to improve the condition.

Adrenochrome↗
PubMed1989

Impaired urine concentrating ability in Itai-itai (ouch-ouch) disease.

A case of Itai-itai (ouch-ouch) disease with reduced urinary kallikrein excretion and slightly enhanced renin-angiotensin-aldosterone system is described. Although it is well known that cadmium toxicity frequently affects the renal tubular lesions, this report is the first to demonstrate the impaired urine concentrating ability in this disease.

Aged↗
PubMed1989

Vascular dilatory action of Artemisia capillaris bud extracts and their active constituent.

In perfusion experiments, the acetone extract of Artemisia capillaris buds significantly inhibited the response to norepinephrine of helical strips of rabbit thoracic aorta. The acetone extract was fractionated by column chromatography to identify the active constituent. Kinetic experiments using rabbit thoracic aorta showed that 6,7-dimethoxycoumarin (scoparone) has a marked inhibitory effect on the contractions induced by norepinephrine, 5-hydroxytryptamine, histamine and angiotensin II. Like nitroglycerin, scoparone appeared to be a competitive antagonist of norepinephrine.

Animals↗
PubMed1989

The effect of adrenal surgery on plasma atrial natriuretic factor and sodium escape phenomenon in patients with primary aldosteronism.

Plasma concentrations of atrial natriuretic factor and some vasoactive substances were determined in 8 patients with aldosterone-producing adenoma, 10 with idiopathic adrenal hyperplasia, 10 normotensive subjects and 12 patients with essential hypertension. Plasma atrial natriuretic factor concentration in patients with aldosterone-producing adenoma was the highest among the examined groups. Adrenal surgery reduced plasma concentrations of atrial natriuretic factor and aldosterone concomitant with the elevation in urinary sodium excretion, plasma renin activity and urinary sodium-to-potassium ratio. Withdrawal of trilostane (3 beta-hydroxysteroid dehydrogenase inhibitor) in patients with idiopathic adrenal hyperplasia increased plasma concentrations of atrial natriuretic factor and aldosterone, and decreased the urinary sodium-to-potassium ratio, plasma renin activity and urinary sodium excretion. However, reduced urinary sodium excretion following trilostane treatment returned to the control level successively despite the high levels of plasma atrial natriuretic factor and aldosterone. Acute infusion of saline remarkably increased plasma atrial natriuretic factor concentration in patients with idiopathic adrenal hyperplasia and aldosterone-producing adenoma. These results suggest that a high level of atrial natriuretic factor is a characteristic feature in patients with aldosterone-producing adenoma caused chiefly by the expansion of extracellular fluid volume, and circulating atrial natriuretic factor may contribute to regulation of the sodium escape phenomenon in patients with aldosterone-producing adenoma or idiopathic adrenal hyperplasia.

Adenoma↗
PubMed1989

Age-related differences in norepinephrine and non-collagenous protein in human vas deferens.

The existence of norepinephrine or non-collagenous protein in some tissues is believed to reflect the sympathetic discharge of the structures and plays an important role in contractile ability. Specimens of vas deferens were obtained from 44 subjects in various decades of life from age 20 to 84, and levels of norepinephrine, non-collagenous protein, collagen and elastin were determined. The level of norepinephrine and non-collagenous protein declined with increasing age. Both parameters inversely correlated with age. Collagen and elastin increased with advancing age. The regression line and coefficient of correlation between both variables showed significantly positive correlations. It is suggested that the contractile ability of human vas deferens, as defined by norepinephrine and non-collagenous protein contents, decreases with age, and the age-related increase in collagen and elastin may be of importance in reducing the contractile capability of this structure.

Adult↗
PubMed1989

Protection of glutathione S-transferase from bilirubin inhibition.

Inhibition of the enzyme activity of glutathione S-transferase (GST) by a physiological concentration of bilirubin was studied using various substrates. When rat liver cytosol was used as an unfractionated GST, its GSH-conjugation activity toward 1-chloro-2,4-dinitrobenzene was decreased to one-half by bilirubin, while the activity toward 1,2-dichloro-4-nitrobenzene, p-nitrobenzyl chloride, or 1,2-epoxy-(p-nitrophenoxy)propane and also the non-selenium dependent GSH-peroxidase activity toward cumene hydroperoxide (CHPx activity) were hardly affected under the same conditions. In contrast, bilirubin inhibited each of the purified GST isozymes and no remarkable difference in bilirubin inhibition was observed with any of the substrates tested. From the chromatographic analysis of the cytosol incubated with [3H]bilirubin, it was found that a major part of the added bilirubin binds to subunit 1 (Ya) of GST isozyme, leaving not only the conjugation activity derived from 3-4 type GST but also the CHPx activity of subunit 2 (Yc) quantitatively intact. The bilirubin inhibition of both the conjugation activity of GST 3-4 and the CHPx activity of GST 2-2 was prevented almost completely by addition of a 3-fold molar excess of GST 1-1. From these results, it was assumed that the enzyme activities of both 3-4 type GSTs and subunit 2 (Yc) were protected from the inhibitory action of bilirubin by the scavenger effect of subunit 1 (Ya).

Animals↗
PubMed1989

Genetic suppression of a dnaG mutation in Escherichia coli.

Escherichia coli strains with a temperature-sensitive mutation, dnaG2903, in the primase-encoding gene spontaneously reverted to the temperature-insensitive phenotype at a high frequency. Many of the reversions were caused by extragenic sdg suppressors. About 100 independently isolated sdg suppressors were analyzed. They fall into two classes. The sdgA mutations were genetically mapped very close to and upstream of the dnaG gene and were found to be cis dominant. DNA sequencing of two of them revealed that G----A and C----A base substitutions had occurred 43 and 62 bases, respectively, upstream of the dnaG start codon. This region represents a transcriptional terminator thought to contribute to control of dnaG gene expression. The other class of suppressor, sdgB, seemed to comprise mutant alleles in the rpoB gene coding for the beta subunit of RNA polymerase core enzyme. Some of them were initially isolated as rifampin-resistant mutants. Both the sdgA and sdgB suppressors were found to increase the transcriptional activity of dnaG. This finding and other observations led to the proposition that sdgA and sdgB suppress the phenotype caused by dnaG2903 by overproducing the mutated primase; the quantitative oversupply may compensate for the qualitative defect of the dnaG2903 primase. An alternative mechanism of suppression by sdgB is discussed.

Base Sequence↗
PubMed1989

Orthotopic partial liver transplantation in dogs can be performed without cold perfusion of the donor liver. Evaluation of its feasibility in terms of energy metabolism.

To investigate the feasibility of obtaining grafts from living, genetically related adult donors without any complicated harvesting techniques, orthotopic partial liver transplantation (PLT) without cold perfusion of the donor graft was evaluated in beagles by assessing the graft viability using ketone body ratio (KBR). Ten PLT were performed under venovenous bypass. The left half of the donor liver was transected in situ followed by systemic heparinization, and immediately implanted with care taken to leave the recipient's inferior vena cava intact, and to maintain the normothermic state without cold perfusion. Four of ten dogs survived for 5 days or longer (longest survival was 9 days) and died of other causes than graft dysfunction. Four others died of thromboembolitic episode, accidental bleeding or technical failure. Two dogs died of graft dysfunction. The changes in KBR in 5 dogs without fatal complications after transplantation were maintained within normal range thereafter. These results suggest that the PLT without cold perfusion of donor graft is possible from the viewpoint of energy metabolism.

Animals↗
PubMed1989

Immunological treatment with low dosage ciclosporin in rat liver allotransplantation.

Ciclosporin (CsA) was administered subcutaneously at a dose of 3 mg/kg body weight/day from the day of operation to 14 days of liver allotransplantation in ACI rat (RT1a) to LEW rat (RT1(l) strain combination. All LEW recipients of ACI liver transplants without immunosuppressive treatment had severe rejection and expired within 12 days. In contrast, 7 out of 9 recipients in the same strain combination with temporary CsA treatment survived indefinitely. Histologically, widespread cellular infiltration and massive hepatocyte necrosis were evident upon autopsy of the recipients without CsA treatment. In contrast, in the surviving rats of the CsA-treated group, mononuclear cell infiltration was restricted to the periportal field and hepatocytes appeared to be normal at 14 days posttransplant. CsA concentrations in whole blood were determined by high-performance liquid chromatography. The trough levels were 788 +/- 48, 621 +/- 76 and 546 +/- 52 ng/ml, at 5, 10 and 14 days posttransplant, respectively. We concluded that this relatively low-dose subcutaneous administration of CsA offered adequate immunosuppression in rat liver allotransplantation in this strain combination.

Animals↗
PubMed1989

Structural studies on milk of calcium in calyceal diverticulum.

Structural studies were performed on a renal specimen removed from a patient with milk of calcium in a calyceal diverticulum. Infrared spectroscopy revealed that stones consisted of crystals of calcium oxalate. On scanning electron microscopy and X-ray microanalysis, the intact surface of the stones was composed of weddellite and the fractured face of the stones showed calcium phosphate. Subsequently, stagnation is considered to be an important factor in the formation of milk of calcium.

Adult↗
PubMed1989

The effect of scoparone, a coumarin derivative isolated from the Chinese crude drug Artemisiae capillaris flos, on the heart.

In the present study, scoparone isolated from Artemisia Capillaris Flos has been investigated to determine its pharmacological properties on the heart. Scoparone was found to cause the increase in coronary flow and heart rate, but did not affect cardiac output, left ventricular pressure or left ventricular work in the isolated perfused heart. Scoparone at 25 mg/kg and 50 mg/kg, p.o. had a marked inhibitory effect on the ST wave depression. Consequently it is suggested that scoparone has antianginal action.

Animals↗
PubMed1989

[Dynamic study of titanium-hydroxyapatite implant by finite element method].

In order to evaluate the strength of titanium-hydroxyapatite implant, adhesive tests and loading tests were performed. The results of the loading tests were compared with the computed results by finite element method. Axisymmetric 8-node quadrilateral element for arbitrary loading was used for the analysis. Implants of 3.2 mm diameter were loaded at 45 degrees of the implant axis by using an Instron testing machine at crosshead speed of 0.5 mm/min. The results were obtained as follows: 1. The mean value of the adhesive test of titanium-resin (Panavia)-hydroxyapatite was 2.3 kgf/mm2. The fracture was caused at Panavia layer. 2. The mean value of the fracture loads of implants was 10.9 kgf. The fracture was caused at Panavia layer, similarly to the result described in 1. 3. The principal stress caused at Panavia layer of the implant was approximately 2.3 kgf/mm2, which was calculated under the load of 10.9 kgf by the finite element method. This result corresponds to that of the loading test described in 1 and 2. It was ascertained by these findings that finite element method is effective for the evaluation of the strength of this implant.

Dental Implants↗
PubMed1989

Testosterone replacement therapy and prostate/seminal vesicle volume in Klinefelter's syndrome.

Volume of prostate and seminal vesicles was measured in patients with Klinefelter's syndrome by means of transrectal ultrasonography before and after testosterone replacement therapy. Continuous suppression of plasma gonadotropin levels was not observed, and plasma levels of testosterone did not maintain the normal range. However, volume of prostate (p less than 0.001) and seminal vesicles (p less than 0.05) increased significantly after testosterone replacement therapy. Volume determination of prostate and seminal vesicles by means of transrectal ultrasonography is an available parameter for evaluating the adequacy of testosterone replacement therapy in Klinefelter's syndrome.

Adult↗
PubMed1989

Isolation and characterization of new antibiotics resorcinomycins A and B.

New antibiotics, resorcinomycins A and B, were isolated from the culture broth of a streptomycete strain identified as Streptoverticillium roseoverticillatum. The antibiotics are water-soluble amphoteric substances, positive to SAKAGUCHI'S reagent. The molecular formulas C14H20N4O5 and C13H18N4O5 for A and B were indicated by elemental analysis and secondary ion MS. The structures of these antibiotics were determined by 1H and 13C NMR spectrometry and some chemical evidences to be N-[(S)-alpha-guanidino-3,5-dihydroxy-4-isopropylphenylacetyl]glyci ne and N-[(S)-alpha-guanidino-3,5-dihydroxy-4-ethylphenylacetyl]-glycine, respectively.

Actinomycetales↗
PubMed1989

Mureidomycins A-D, novel peptidylnucleoside antibiotics with spheroplast forming activity. III. Biological properties.

Mureidomycins (MRD's) A-D were specifically active against Pseudomonas aeruginosa. Among them, MRD C was most active, with MICs of 0.1 to 3.13 micrograms/ml against many strains of the target organism. Its activity was comparable to that of cefoperazone, ceftazidime and cefsulodin. MRD C-resistant mutants of P. aeruginosa appeared spontaneously at a high frequency when cultured in the presence of the antibiotic. No cross-resistance was observed with beta-lactam antibiotics. A rapid decrease of turbidity along with spheroplast formation and cell lysis was observed when cells of P. aeruginosa were grown in the presence of MRD C. The compounds exhibited low toxicity and protected mice from experimental infection with P. aeruginosa. The urinary and fecal recoveries of MRD C given subcutaneously were 5 and 18%, respectively.

Animals↗