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Biomedical subjects

J Kato

Publications and source records attributed to J Kato.

At least 451 records · Page 25Linked to original sources
PubMed1990

[Clinical experiences of 35 cases with upper urinary tract stones by extracorporeal shock wave lithotripter (MEDSTONE 1000)].

We made clinical trials of the extracorporeal shock wave lithotripter (MEDSTONE-1000) in patients with upper urinary tract stones. Thirty-five cases (total 40 trials) treated during the period of October 1987 through March 1988 were enrolled in this study. The ages of the cases ranged from 22 to 65 (average 43.9) years old, comprising 23 men and 12 women. The site of presence of urinary tract stones was the renal pelvis and calyx in 28 cases and the upper ureter in 7 cases. The size of the stone was smaller than 1 cm in 15 cases, 1 to 2 cm in 12 cases, 2 to 3 cm in 7 cases and larger than 3 cm in 1 case. 13 patients with renal stones were treated with double-J stent catheter and all patients with ureteral stones were treated with the ureteral balloon catheter or flexible-tip ureteral catheter as preoperative manipulation. In 26 cases epidural anesthesia was used and the others were treated under general anesthesia. Stone targetting was determined by two oblique radiographs from separate axes. The intensity of shock waves was mainly 24 KV and the maximum shock wave counts to break up stones were 6800 shots. The size of the broken stone fragments was less than 2 mm in 24 cases (68.5%) and 2 to 5 mm in 10 cases (28.6%), which indicated that the procedure was very effective. However, one case in whom the stone could not be broken was with cystinuria. After three months the fragments completely passed in 22 cases (64.7%) and the residual fragments larger than 5 mm were left in 2 cases (5.9%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Association between mechanical stress and bone remodeling.

Stress patterns and levels were analyzed by use of the three-dimensional finite element method. Three-dimensional models were constructed for the human upper central incisor (1205 nodes and 920 elements) and the sheep metacarpus (240 nodes and 128 elements). Orthodontic and orthopedic forces were applied to the tooth and the bone, simulating orthodontic tooth movement and experimental loading test for the bone. Three principal stresses were determined in the alveolar bone and the sheep long bone. The following results were obtained. 1. Stress distributions in the lateral alveolar bone were similar to those with bone deformation from cantilever bending mode. On the medial surface of the alveolar bone, a bending stress was observed, however, remaining stresses exhibited changes corresponding to those in the PDL produced by tipping displacement of the tooth. 2. In the sheep long bone, tensile and compressive stresses were induced on the dorsal and volar sides, respectively. The magnitude of stresses was greatest at the mid-diaphyseal region. Compressive and tensile stresses were related with bone resorption and apposition. The magnitude of principal stresses was almost proportional to dimensional changes of the bone at the mid-diaphyseal region. Bone remodeling in the long bone is related with mechanical stress, principal stress in particular, indicating that remodeling of the alveolar bone may be induced by application of orthodontic force in addition to conventional change of the bone adjacent to the PDL. Thus, it is shown that mechanical stress in living structures may be a trigger to induce biological remodeling of bones.

Alveolar Process↗
PubMed1990

[A case of primary coronary artery dissection].

Primary coronary artery dissection occurring as a spontaneous event and not associated with trauma due to catheter manipulation is rare. We recently experienced (a case of) a 52-year-old man with primary artery dissection. He was admitted to our hospital with severe chest pain as his chief complaint on September 6, 1988. Electrocardiography and laboratory data showed acute inferior myocardial infarction. He was treated with medication and underwent coronary angiograms on October 3, 1988. Right coronary angiogram revealed an intimal flap and false lumen. But right coronary angiograms 6 months after the onset of myocardial infarction revealed progression of stenosis but no intimal flap, and coronary spasm was not evoked after acetylcholine administration. Primary coronary artery dissection has been reported since Pretty's first description of it in 1931. The majority of earlier cases were diagnosed at autopsy, but recently reports of survivors have been increasing due to the progress in and popularization of coronary angiographic technics. This case is the 46th case of primary coronary dissection found by coronary angiography. So it is not extremely rare. In our case the involved artery was the right coronary artery. In survivors, right coronary artery dissection is more frequent than left, because the area supplied by the right coronary artery is smaller than the area supplied by the left one. Although in our case coronary artery stenosis progressed, after a long term resolution of dissection may occur. There are a few cases in which resolution of dissection occurred naturally.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Dissection↗
PubMed1990

[Effects of narcotic analgesics on somatosympathetic reflex discharges in anesthetized cats: buprenorphine and naloxone].

Effects of buprenorphine and naloxone on the sympathetic reflex evoked in the inferior cardiac nerve following electrical stimulation to the ipsilateral superficial peroneal nerve were investigated in 29 cats under satisfactory anesthesia with urethane and alpha chloralose. Two components of the somato-sympathetic reflexes with two different latencies were recorded. The early component was due to an activation of myelinated A afferent (referred to as A reflex), while the late component was due to an activation of unmyelinated fibers (referred to as C reflex). Intravenous injection of buprenorphine (0.006 mg.kg-1) depressed neither A or C reflex. A somewhat larger dose of buprenorphine (0.06 mg.kg-1) markedly depressed C reflex. A larger dose of buprenorphine (0.3 mg.kg-1) antagonized the depressive effects of buprenorphine (0.06 mg.kg-1) on C reflex. Naloxone (0.2 mg.kg-1 i. v.) antagonized the depressive effects of buprenorphine (0.06 mg.kg-1) on C reflex in 7 cats in which C reflex had been depressed less than 50% of control with buprenorphine 0.06 mg.kg-1. In other 5 cats naloxone (0.2 mg.kg-1) did not antagonize the depressive effects of buprenorphine (0.06 mg.kg-1) on C reflex which had been depressed more than 50% of control with buprenorphine 0.06 mg.kg-1. The present results suggest that buprenorphine has an effect which is called "non competitive autoinhibition", and the somato-sympathetic C reflex can be a useful indicator of analgesics in satisfactorily anesthetized cats.

Anesthesia↗
PubMed1989

Nucleotide sequence of a regulatory region controlling alginate synthesis in Pseudomonas aeruginosa: characterization of the algR2 gene.

Alginate (Alg), an exopolysaccharide with strong gelling properties, is produced by Pseudomonas aeruginosa primarily during its infection of the cystic fibrosis (CF) lung. The alg genes are normally not expressed in other environments. The promoter for a critical Alg biosynthetic gene, algD, encoding GDP-mannose dehydrogenase, is activated only under conditions reminiscent of the CF lung (i.e., under high osmolarity), and at least two regulatory genes, algR1 and algR2, have been implicated in this activation process. The physical mapping of a 4.4-kb region harboring algR2 has been accomplished and the complete nucleotide sequence of this fragment, including that of algR2, is presented. The cloning and complementation experiments also demonstrate the presence, on this fragment, of regulatory gene(s) different from algR1 and algR2. The expression of the algR2 gene allows a high level of activation of the algD promoter in Escherichia coli, in the presence of algR1 in a high osmotic environment, suggesting that the AlgR2 and AlgR1 proteins act cooperatively to activate the algD promoter. Hyperexpression of the algR2 gene from the tac promoter also allows the conversion of nonmucoid cells of strain 8822, a spontaneous revertant of the mucoid CF isolate strain 8821, back to mucoidy, but not that of the clinical isolate, strain PAO1.

Alcohol Oxidoreductases↗
PubMed1989

Immunoreactive endothelin in rat kidney inner medulla: marked decrease in spontaneously hypertensive rats.

Using a specific and sensitive radioimmunoassay for endothelin, the regional distribution and molecular form of endothelin was investigated in rat tissue. The highest concentration was observed in the inner medulla of the kidney (8.7 +/- 2.2 pg/mg wet weight). On two kinds of reverse phase high performance liquid chromatography, immunoreactive endothelin in the inner medulla of the kidney was separated into two peaks at positions where authentic porcine/human and putative rat/human endothelin eluted. Furthermore, the concentration of immunoreactive endothelin in the inner medulla of the kidney was remarkably decreased in spontaneously hypertensive rats (SHR) compared with normotensive control Wistar Kyoto rats (WKY) but no difference was observed in lung immunoreactive endothelin.

Amino Acid Sequence↗
PubMed1989

Regional distribution of immunoreactive endothelin in porcine tissue: abundance in inner medulla of kidney.

A specific and sensitive radioimmunoassay for endothelin has been developed. Half maximal inhibition of binding of radioiodinated endothelin was observed at 37 pg/tube and endothelin was detectable as low as 1 pg/tube. With this assay, the regional distribution of endothelin was determined in porcine tissue. The highest concentration of immunoreactive endothelin was observed in inner medulla of kidney (6.2 +/- 1.1 pg/mg wet weight), while the concentration in kidney cortex was very low. Immunoreactive endothelin was also found in lung in relatively high concentration. The immunoreactive endothelin in porcine lung and inner medulla of kidney was further characterized by reverse phase high performance liquid chromatography combined with radioimmunoassay.

Animals↗
PubMed1989

Escherichia coli parA is an allele of the gyrB gene.

A thermosensitive (ts) parA mutant, MFT110, of Escherichia coli carried at least two ts mutations. The major ts defect, resulting from a mutation mapped originally at 95 min and complemented by pLC8-47, was most probably due to psd. A plasmid carrying the 1.6 kb BamHI-PvuII fragment recloned from pLC8-47 complemented the major ts mutation in MFT110 and psd(ts) in two mutants, but did not correct the Par phenotype of MFT110. The second ts mutation was salt-repairable and mapped at 83 min close to recF and tnaA. This mutation was linked with the Par phenotype as shown unambiguously by 4',6-diamidino-2-phenylindole stained nucleoids in parA mutant cells with the W3110 genetic background. Both salt-repairable ts and Par traits were corrected concomitantly by a plasmid carrying the chromosomal region solely for the gyrB gene. This strongly suggests that parA is an allele of gyrB.

Alleles↗
PubMed1989

Arachidonic acid as a possible modulator of estrogen, progestin, androgen, and glucocorticoid receptors in the central and peripheral tissues.

In an attempt to learn whether modulation of steroid hormone receptor by arachidonate is generalized or not, the arachidonate effect was examined in cytosol estrogen (ER), progestin (PR), androgen (AR) and glucocorticoid receptors (GCR) from the central and peripheral tissues of rats by sucrose density gradient centrifugation, and gel filtration on LH20 columns or dextran-coated charcoal absorption. Arachidonate and other long-chain fatty acids appear to inhibit the specific binding of estrogen ([3H]R2858), progestin ([3H]R5020), androgen ([3H]R1881) and glucocorticoid ([3H]dexamethasone) to the respective receptors in brain (neonatal cerebral cortex and hypothalamus-preoptic area, HPOA), uterus and prostate, with the exception of the potentiating effect on the brain estrogen receptors. The potency of the unsaturated fatty acids paralleled to some degree the number of cis double bonds and carbon, in that oleate (C18:1) arachidonate (C20:4) docosahexaenoate (C22:6). The arachidonate inhibition was dose-dependent in the tissue steroid hormone receptors, except for dose-dependent potentiation of the brain cortical estrogen receptors. Inhibitory potency as expressed by the concentration for 50% maximum inhibition (Ki) was in the range of 11-18 microM for the receptors other than the uterine estrogen receptors with the value of 44 microM, suggesting lower sensitivity for the estrogen receptor to the arachidonate effect in the uterus. Analysis on kinetics and Scatchard plot revealed the non-competitive type of the inhibition. In addition, arachidonate lowered dose-dependently the peak of labelled progestin or estrogen binding to the 8S receptor proteins, which were collected from fractions in the 8S region of the cytosols from intact or diethylstibestrol-primed rat uteri. These results suggest the generalized modulatory effect of arachidonate on the steroid hormone receptors in the central and peripheral tissues. Arachidonate could affect, negatively or positively, the estrogen receptors, and negatively the progestin, androgen and glucocorticoid receptors, through a possibly direct but weak binding at sites different from steroid binding sites on the receptor molecules. A potential messenger role of arachidonate itself has been implicated in the regulation or modulation of the steroid hormone receptors.

Animals↗
PubMed1989

Natriuretic and hypotensive effects of brain natriuretic peptide (BNP) in spontaneously hypertensive rats.

Effects of four doses (0.1, 0.2, 1.0 and 2.0 nmol/kg) of brain natriuretic peptide (BNP) on natriuresis and blood pressure were investigated in anesthetized spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). An intravenous injection of 1.0 and 2.0 nmol/kg of BNP caused a significant increase of natriuresis and reduction of blood pressure in SHR and WKY. These effects were essentially identical to the effects of atrial natriuretic peptide (ANP). Remarkable bioactivity elicited by BNP rasises the possibility that BNP has a role in the regulation of blood pressure and water-electrolyte balance. On the other hand, when the effects of BNP on both strains of rats were compared with those of alpha-human ANP reported previously, the hypotensive effect of BNP was less than those of alpha-human ANP only in SHR. It is suggested that BNP might have different bioactivity than that of ANP in SHR.

Animals↗
PubMed1989

Studies on angiotensin converting enzyme inhibitors. 4. Synthesis and angiotensin converting enzyme inhibitory activities of 3-acyl-1-alkyl-2-oxoimidazolidine-4-carboxylic acid derivatives.

(4S)-1-Alkyl-3-[[N-(carboxyalkyl)amino]acyl]-2-oxoimidazolidine-4- carboxylic acid derivatives (3) were prepared by two methods. Their angiotensin converting enzyme (ACE) inhibitory activities and antihypertensive effects were evaluated, and the structure-activity relationships were discussed. The dicarboxylic acids 3a-n possessing S,S,S configuration showed potent in vitro ACE inhibitory activities with IC50 values of 1.1 X 10(-8)-1.5 X 10(-9) M. The most potent compound in this series, monoester 3p, had an ID50 value of 0.24 mg/kg, po for inhibition of angiotensin I induced pressor response in normotensive rats and produced a dose-dependent decrease in systolic blood pressure of spontaneously hypertensive rats (SHRs) at doses of 1-10 mg/kg, po.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1989

Natriuretic and hypotensive effects of brain natriuretic peptide in anaesthetized DOCA-salt hypertensive rats.

1. Both natriuretic and hypotensive effects of brain natriuretic peptide (BNP), a novel peptide identified in porcine brain, were investigated in anaesthetized DOCA-salt rats and control rats. 2. An intravenous injection of two different doses (0.5 and 5.0 nmol/kg) of BNP produced a rapid and marked natriuresis and hypotension in DOCA-salt rats. 3. In particular, significant differences of responsiveness were observed between DOCA-salt and control rats when administered the lower dose of BNP. 4. It was suggested that DOCA-salt rats might be relatively more susceptible to BNP.

Anesthesia↗
PubMed1989

Cefotiam disposition in markedly obese athlete patients, Japanese sumo wrestlers.

Markedly obese athletes like Japanese sumo wrestlers may frequently suffer various traumas which result in the prophylaxis or treatment of posttraumatic infection with antibiotics. However, appropriate dosage regimens in this group of patients have not been fully known for many antibiotics. Therefore, we studied the kinetic disposition of cefotiam, a parenteral, broad-spectrum cephalosporin with activity against gram-positive and -negative bacteria, after an intravenous dose (2 g) infused over 30 min into 15 sumo wrestler patients with an excess body weight (130 to 220% of ideal body weight) and 10 control patients with a normal weight (90 to 102% of ideal body weight). Mean (+/- standard deviation) clearance and steady-state volume of distribution were significantly greater in the sumo wrestler than in the control group (38.3 +/- 9.4 versus 23.5 +/- 6.0 liters/h, P less than 0.001, and 30.2 +/- 8.0 versus 17.9 +/- 6.1 liters, P less than 0.001). Mean elimination half-life was slightly but significantly longer in the sumo wrestler than in the control group (0.91 +/- 0.14 versus 0.74 +/- 0.20 h, P less than 0.05). However, mean residence time did not differ between the two groups (0.79 +/- 0.10 versus 0.75 +/- 0.14 h). The statistical differences in clearance and volume of distribution between the two groups disappeared when these kinetic parameters were corrected for body surface area, but not for total body weight or ideal body weight. The results suggest that the dosage calculation of cefotiam, a hydrophilic antibiotic, should be made on the basis of body surface area in morbidly obese athlete or sumo wrestler patients. However, whether this recommendation should extend to other nonathlete obese subjects remains to be determined.

Adult↗
PubMed1989

Cloning of regions required for contact hemolysis and entry into LLC-MK2 cells from Shigella sonnei form I plasmid: virF is a positive regulator gene for these phenotypes.

Two distinct regions required for both contact hemolysis and entry into LLC-MK2 cells were cloned into Escherichia coli from the Shigella sonnei form I plasmid, pSS120. The first region was cloned into an E. coli HB101 strain containing noninvasive Tn1 insertion mutants of the form I plasmid, and expression of ipa (invasion plasmid antigen) gene products was restored. The plasmid carrying the first region was then transformed into E. coli lacking the form I plasmid, and additional DNA fragments from the form I plasmid were cloned into the same recipient on compatible vectors. Five of these double transformants were found to be positive for contact hemolysis activity. Restriction analysis of these five clones indicated that the previously reported ipa locus and the invA locus were present on the second plasmid region. Only the strains carrying both of these regions were active in contact hemolysis and cell invasion assays. Several proteins, including the a, b, c, and d proteins encoded by the ipa genes, were detected in the double transformants by Western blot (immunoblot) analysis with serum of a monkey convalescing from shigellosis. A positive regulator was suggested to exist in the first region, since the amounts of most of these proteins were simultaneously increased in the presence of this region. Subcloning and nucleotide sequencing indicated that this positive regulator gene was virF. Product analysis of the virF gene with minicells showed that two peptides (30 and 21 kilodaltons) were synthesized and that at least the 30-kilodalton protein was essential for regulation of the ipa genes.

Amino Acid Sequence↗