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Biomedical subjects

J Kato

Publications and source records attributed to J Kato.

At least 415 records · Page 23Linked to original sources
PubMed1991

Cyclic GMP down-regulates atrial natriuretic peptide receptors on cultured vascular endothelial cells.

Down-regulation of atrial natriuretic peptide (ANP) receptors was investigated using a cultured bovine pulmonary artery endothelial (CPAE) cell line. Endothelial cells have been shown to possess two subtypes of ANP receptors, a guanylate cyclase-coupled receptor (B-receptor) and a clearance receptor (C-receptor). The treatment with APIII, rat ANP (103-126), at concentrations of 10(-8) to 10(-6) M for 24 h, resulted in a significantly (p less than 0.01) greater decrease in maximum 125I-APIII binding to CPAE cells than the identical concentration of API, rat ANP (103-123). APIII at concentrations of 10(-8) to 10(-6) M stimulated cyclic GMP (cGMP) production 3.3-17.5-fold greater than similar concentrations of API. From these findings, we hypothesized that cGMP produced following ANP binding to the B-receptor participates in ANP receptor regulation. M&B 22948, a selective inhibitor of cGMP-specific phosphodiesterase, significantly (p less than 0.01) potentiated the effect of both API and APIII on 125I-APIII binding, while M&B 22948 itself had no significant effect on 125I-APIII binding. Treatment of the cells with 1 mM 8-bromo-cGMP also significantly (p less than 0.01) decreased 125I-APIII binding to the cells, and a potentiation of this effect was observed by M&B 22948. Scatchard analysis of binding data from 8-bromo-cGMP-treated cells showed a significant decrease in Bmax (1.79 +/- 0.15 to 1.20 +/- 0.07 fmol/mg protein, p less than 0.05) without a significant change in Kd. Affinity cross-linking of 125I-APIII to 8-bromo-cGMP-treated cells showed a decrease in the labeling of 60- and 70-kDa bands corresponding to the C-receptor. In addition, the APIII-stimulated cGMP response remained unchanged in the 8-bromo-cGMP-treated cells, indicating that the B-receptor was not down-regulated. We conclude that cGMP regulates ANP-binding sites on the endothelial cell and that the evidence indicates that the C-receptor may preferentially be down-regulated by cGMP in CPAE cells.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

Purification of the regulatory protein AlgR1 and its binding in the far upstream region of the algD promoter in Pseudomonas aeruginosa.

A regulatory protein AlgR1, previously suggested to be a member of a two-component sensory transduction system because of its homology to OmpR and NtrC and its ability to allow activation of the algD promoter under conditions of high osmolarity, has been hyperproduced in Escherichia coli after deletion of the upstream region including part of the Shine-Dalgarno sequence of the algR1 gene and its subsequent cloning under the tac promoter. The AlgR1 protein is purified as a monomer, and the sequence of the nine N-terminal amino acids of the monomer matches with that predicted from the DNA sequence of the algR1 gene. The purified AlgR1 protein binds to two separate DNA fragments of the algD upstream region. DNase protection experiments identify these two DNA segments as 14-mer sequences centered at -382 and -458 regions, which contain a common CCGT-TCGTC sequence in them. While the presence of at least one AlgR1 binding site is important for the activation of the algD promoter, the presence of both of the binding sites in the upstream region leads to a higher level of activation.

Amino Acid Sequence↗
PubMed1991

Enzymatic activity of cellulase adsorbed on cellulose and its change during hydrolysis.

Hydrolysis of pure cellulose Avicel has been carried out, using Meicelase from Trichoderma viride, where the enzymatic activity of cellulase adsorbed on cellulose and its changes during the hydrolysis were investigated. A rapid drop of the hydrolysis rate during the reaction, that is always observed in enzymatic hydrolysis of cellulose, could be explained by a decline of specific activity of adsorbed enzyme, and it was implied that the decline results from a loss of synergistic action between endoglucanase and exoglucanase. An empirical equation expresses the change of hydrolysis rate during the reaction and also shows that the change of the hydrolysis rate is caused by the decline of the specific enzymatic activity of adsorbed enzyme.

Adsorption↗
PubMed1991

Cardiac content of brain natriuretic peptide in DOCA salt-hypertensive rats.

The cardiac content of immunoreactive rat brain natriuretic peptide (ir-rBNP) in deoxycorticosterone acetate (DOCA)-salt hypertensive rats was measured by radioimmunoassay (RIA). The atrial content of ir-rBNP was significantly lower in the DOCA-salt group than in the control group (p less than 0.01). However, the ventricular content of ir-rBNP was markedly increased in the DOCA-salt group as compared to the other groups. Ir-rBNP level in the atria was negatively correlated with other groups. Ir-rBNP level in the atria was negatively correlated with blood pressure (r = -0.49, p less than 0.01), while that in the ventricle was positively correlated with blood pressure (r = 0.79, p less than 0.001). A significant correlation was observed between tissue levels of ir-rBNP and ir-rat atrial natriuretic peptide (rANP) both in atrium and ventricle (atrium, r = 0.63, p less than 0.001; ventricle, r = 0.95, p less than 0.001). These results raise the possibility that rBNP as well as rANP functions as a cardiac hormone, the production of which probably changes in response to increased of body fluid and blood pressure.

Animals↗
PubMed1991

Molecular cloning and characterization of form I antigen genes of Shigella sonnei.

Sau3AI-generated DNA fragments of the Shigella sonnei large plasmid encoding the form I antigen were cloned into Escherichia coli with cosmid vector pHSG262. One resulting plasmid, designated pJK1137, was studied further. Restriction endonuclease mapping and analysis of transposon Tn3 insertion mutants demonstrated that the form I antigen genes were located within a region of about 12.6 kb consisting of the two contiguous HindIII fragments of 1.26 kb and 12.4 kb. The results of complementation studies between Tn3 insertion mutants of pJK1137 and recombinant plasmids carrying different parts of the form I antigen genes indicated that the 12.6 kb DNA sequence contained at least four gene clusters, regions A, B, C and D. Analysis of radioactively labelled proteins in minicells demonstrated that the DNA sequence of about 12.6 kb coded for at least four specific proteins of 42, 23, 48 and 39 kDa. The former two were coded by region A, the latter two by region D.

Agglutination Tests↗
PubMed1991

Environmentally regulated algD promoter is responsive to the cAMP receptor protein in Escherichia coli.

The environmentally activated algD promoter of Pseudomonas aeruginosa has been shown to be influenced by DNA supercoiling. It is believed that protein-induced bending or looping is required for this activation. We studied the role of Escherichia coli cAMP-CRP on algD promoter activation in E. coli and show that a functional CRP is required for this activation. We also demonstrate that the algD promoter is sensitive to glucose repression both in E. coli and P. aeruginosa. Deletion of a putative consensus CRP binding sequence upstream of the algD promoter renders the promoter non-responsive to glucose repression. The involvement of cAMP-CRP complex in the activation of the algD promoter in E. coli has been demonstrated directly through binding of a 255 base pair DNA fragment containing the putative consensus CRP binding sequence. Other fragments, upstream or downstream but without any consensus CRP binding sequence, did not show any binding with CRP. A CRP-like analogue, similar to that in Xanthomonas campestris, but capable of activating genes without forming a complex with cAMP, is believed to allow glucose repression in P. aeruginosa.

Bacterial Proteins↗
PubMed1991

Tissue reactions after experimental luxation injuries in immature rat teeth.

Immature permanent teeth often develop complications after luxation injuries. The pathology and the degenerative processes of the complications, however, are not well understood. In this study, we histologically examined the long-term reactions of immature rat teeth after standardized luxation injuries delivered in our previously developed experimental model. The upper first molars of 3-week-old male Wistar rats weighing 50-60 g were pushed horizontally toward the palate to cause a constant amount of dislocation. The follow-up changes of the luxated molars were studied up to 56 days after the trauma. Soon after the trauma, the periodontium had irregular fibers, degenerated cells, hemorrhage and edema in various places. After 12 h, a cell free area appeared in the palatal periodontium. In the alveolar bone and on the surface of the root, resorption occurred one day and 5-7 days after injury respectively. Although the damage in the periodontium and alveolar bone was gradually repaired, the root resorption, especially in the palatal cervical region, continued throughout the experimental period. In the most cases, the dental pulp did not seem to be damaged immediately after the trauma. By the 3rd day after injury, however, displacement of odontoblasts into the dentinal tubules was observed in many teeth. Moreover, formation of irregular dentin was observed in some teeth after 7 days. These changes of the pulp tended to disappear in the later stages of the experiment.

Alveolar Process↗
PubMed1991

Alginate synthesis by Pseudomonas aeruginosa: a key pathogenic factor in chronic pulmonary infections of cystic fibrosis patients.

Pulmonary infection by mucoid, alginate-producing Pseudomonas aeruginosa is the leading cause of mortality among patients suffering from cystic fibrosis. Alginate-producing P. aeruginosa is uniquely associated with the environment of the cystic fibrosis-affected lung, where alginate is believed to increase resistance to both the host immune system and antibiotic therapy. Recent evidence indicates that P. aeruginosa is most resistant to antibiotics when the infecting cells are present as a biofilm, as they appear to be in the lungs of cystic fibrosis patients. Inhibition of the protective alginate barrier with nontoxic compounds targeted against alginate biosynthetic and regulatory proteins may prove useful in eradicating P. aeruginosa from this environment. Our research has dealt with elucidating the biosynthetic pathway and regulatory mechanism(s) responsible for alginate synthesis by P. aeruginosa. This review summarizes reports on the role of alginate in cystic fibrosis-associated pulmonary infections caused by P. aeruginosa and provides details about the biosynthesis and regulation of this exopolysaccharide.

Alginates↗
PubMed1991

Preferential increase in the free form of atrial natriuretic peptide in adriamycin-induced nephrotic rats.

In order to evaluate the pathophysiologic role of a free form of atrial natriuretic peptide (ANP) in the nephrotic syndrome, the plasma concentration of immunoreactive ANP was measured by radioimmunoassay using direct (unextracted) and extraction methods in adriamycin-induced nephrotic and normal control rats. The ir-ANP levels measured using unextracted or extracted plasma were representative of total and the free form of ANP, respectively. The plasma levels of total and the free form of ANP were significantly higher in nephrotic rats than in controls (p less than 0.01, p less than 0.001). However, plasma levels of the bound form of ANP, calculated by subtracting the free form of ANP from total ANP, were comparable between the two groups. The free form of ANP was inversely correlated with the daily urinary sodium excretion (r = -0.71, p less than 0.001) and plasma albumin (r = -0.83, p less than 0.001), and positively correlated with the daily urinary protein excretion (r = -0.85, p less than 0.001) in both control and nephrotic groups. Based on these results, the preferential increase in the free form of ANP in nephrotic rats is considered to be a compensatory phenomenon induced by the decreased renal ability to eliminate sodium and water. An increase in the free form of ANP may have some role in urinary protein excretion in the nephrotic syndrome.

Animals↗
PubMed1991

A new technique of ureteric catheterization.

Insertion of an indwelling stent catheter or ureteric catheterization using a new guide wire (the Radiofocus guide wire) was carried out in a total of 24 subjects. The subjects comprised 16 patients in whom insertion of a conventional guide wire and ureteric catheter was not possible due to previous use of an indwelling stent catheter for extracorporeal shock-wave lithotripsy (ESWL), 2 cases in whom a conventional guide wire could not be inserted due to post-ESWL formation of a stone street, 4 patients with ureteric stenosis and 2 patients with normal ureters in whom catheterization was impossible by the usual methods. Insertion of a Radifocus guide wire into the renal pelvis was successfully accomplished in all 24 cases and an indwelling catheter could be passed in 21 cases. These results suggest that the Radifocus guide wire should make a useful contribution to ESWL therapy. It can also be applied to retrograde pyelography, ureteric obstruction, and the dilation of ureteric stenosis.

Adult↗
PubMed1991

Binding specificities and transducing function of the different molecular weight forms of insulin-like growth factor-II (IGF-II) on IGF-I receptors.

In a study that was reported from this laboratory, the mitogenic potency of an apparent mol wt (appMr) of 15,000 precursor form of human insulin-like growth factor-II (hIGF-II) was shown to be greater than that of completely processed hIGF-II for human fetal-derived fibroblasts, and both were more potent than rIGF-I. Since it is generally acknowledged that the stimulation of cell replication by the IGFs is mediated by IGF-I receptors, we undertook to determine whether differences between the receptors' affinity for the two Mr forms of hIGF-II and recombinant IGF-I (rIGF-I) or between its efficiency to couple specific growth factor occupancy to the activation of protein kinase could explain the greater replicating potential of appMr 15,000 hIGF-II. Equilibrium dissociation, i.e. Kd, and inhibition, i.e. Ki, constants were determined by measuring the ability of rIGF-I, hIGF-II, appMr 15,000 hIGF-II, insulin, and the antireceptor monoclonal antibody alpha IR-3 to compete with 125I-labeled rIGF-I and hIGF-II for binding to purified preparations of IGF-I receptors prepared from an enriched source of fetal membrane, i.e. human term placenta. The results of these experiments established that 1) hIGF-II and appMr 15,000 hIGF-II bind to the IGF-I receptor with the same affinity as rIGF-I, e.g. with Kd and Ki values between 0.03-0.07 nM; 2) the total binding capacity, i.e. Ro, for IGF-I binding was not statistically different from the Ro calculated for IGF-II binding; and 3) the statistical analysis of 12 data sets from the competitive binding experiments for goodness of fit indicated that a 1-site model for IGF-I and -II binding was a better fit of the data than a 2-site model. Measurements of the stimulation of IGF-I receptor autophosphorylation at low ligand concentrations established that appMr 15,000 hIGF-II and hIGF-II were more effective than rIGF-I in coupling receptor occupancy to the activation of its protein kinase. At saturating ligand concentrations, the 3 had similar potencies. The original preparation of appMr 15,000 hIGF-II contains a mixture of forms with acidic isoelectric points (pIs) and was more potent than Mr 7,500 IGF-II in stimulating receptor autophosphorylation. These results are consistent with the relative potencies of this preparation, hIGF-II, and rIGF-I in stimulating the replication of 12-week-old fetal dermal fibroblasts.(ABSTRACT TRUNCATED AT 400 WORDS)

Antibodies, Monoclonal↗
PubMed1991

Pharmacological studies on TA-6366, a new ACE inhibitor: II. Effect of long-term administration from the pre-hypertensive stage on blood pressure, relative heart weight and ACE activity of various tissues in spontaneously hypertensive rats (SHRs).

The long-term oral administration of TA-6366 (5 mg/kg/day) from 4-weeks old impeded the genetic hypertension development with only a slight decrease in heart rate in spontaneously hypertensive rats (SHRs). However, the lower dose (1 mg/kg/day) of TA-6366 did not affect the development, but it lowered blood pressure after the development was almost accomplished. Concomitantly, relative heart weights in both the groups were markedly decreased to almost the same degree. The reduction of ACE activity in the aorta, brain and lung of both groups was found at 24 hr after the final administration, particularly at the 5 mg/kg/day dose; and that of the aorta was kept at almost the same low level even on the 9th day after withdrawal. After withdrawal of TA-6366 (5 mg/kg/day), the significant decrease in blood pressure was sustained at least for 10 weeks. The beneficial effect of TA-6366 on the hypertension development in SHRs seems to be related to its strong and long-lasting ACE inhibition, especially in the vasculature.

Administration, Oral↗
PubMed1991

Isolation of chicken-bek and a related gene; identification of structural variation in the ligand-binding domains of the FGF-receptor family.

cDNA clones carrying the chicken-bek gene and a related gene were isolated. Deducing the amino acid sequence of chicken-bek allowed us to predict that it encodes for a receptor tyrosine kinase related to the fibroblast growth factor (FGF) receptor, and that the chicken-bek gene and Cek3 are closely related. However, a significant structural difference was identified between chicken-bek and Cek3 within the putative extracellular region, in such a manner that the structure of the immunoglobulin-like domain was conserved. A probe specific to the altered structure detected mRNA in the tissues as did a probe common to bek and Cek3, indicating heterogeneity in the FGF-receptor family in a novel manner. Furthermore, another bek-like gene was isolated and the expressions of its mRNA and protein product were analysed in tissues and cultured cells.

Amino Acid Sequence↗
PubMed1991

[Two cases of spermatocytic seminoma].

Two cases of spermatocytic seminoma are reported. The first case was a 58-year-old man who visited our hospital with a complaint of painless swollen left scrotal content. Left orchiectomy was performed under the diagnosis of testicular tumor. Since the pathological diagnosis first made was anaplastic seminoma, he was treated with combined chemotherapy (PVB, 1 course). However, since the pathological diagnosis after re-examination of the specimen, was spermatocytic seminoma, he underwent prophylactic radiation therapy. The second case was a 64-year-old man who visited our hospital with a complaint of painless swelling of right scrotal content. Right orchiectomy was performed under the diagnosis of testicular tumor. The pathological diagnosis was spermatocytic seminoma. He underwent prophylactic radiation therapy. Postoperatively these two patients have been well with no evidence of recurrence. These are the 14th and 15th cases of spermatocytic seminoma reported in Japan.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Experimental study on the hemodynamic effects of veno-arterial extracorporeal membrane oxygenation with an automatically driven blood pump on puppies.

Hemodynamics, mainly the pressure of the heart, was studied while performing veno-arterial extra-corporeal membrane oxygenation (VA-ECMO) on 16 puppies between the right atrium and the right carotid artery with a unique ECMO circuit using an automatically driven blood pump. The resulting decrease in the mean pulmonary arterial pressure indicated a definite support of VA-ECMO on the volume work of the right heart. The right and left ventricular end-diastolic pressures decreased during the low flow bypass, but increased significantly with flow over 50 ml/min/kg. The results indicated biventricular pressure strain due to the increase in afterload. The left ventricular systolic pressure gradually increased despite the steady decrease in the systemic arterial systolic pressure when bypass flow exceeded 60 ml/min/kg. The findings were similar to those in peripheral circulatory insufficiency. The authors concluded that VA-ECMO flow should be kept as low as possible, in view of undesirable hemodynamic effects on both ventricles.

Animals↗
PubMed1991

[A case of aortitis syndrome with coronary steal syndrome due to collateral circulation from the right coronary artery to intracranial vessels].

A 44-year old female with aortitis syndrome complained of precordial pain on effort. Exercise electrocardiograms revealed significant ST segment depression in leads II, III, aVF and V. Coronary arteriograms demonstrated no stenosis. However, the right coronary arteriogram revealed collateral circulation arising from the sinus node artery to the bilateral vertebral arteries and the left internal carotid artery. Collateral vessels in aortitis.syndrome arising from the coronary artery to the lung have been reported sporadically. However, to our knowledge, the collateral circulation from the coronary artery to intracranial vessels as seen in the present case has never been reported. In the present case, the left ventricular hypertrophy was observed on electrocardiograms and echocardiograms. It can not be denied that it was a cause of the angina pectoris. However, exercise myocardial scintigraphy showed transient myocardial ischemia at stress on the inferoposterior wall corresponding to leads II, III, aVF and V on electrocardiograms. Therefore, coronary steal syndrome due to the collateral pathway from the coronary artery may be considered a likely cause of the angina pectoris. The collateral circulation was considered to be an important route of blood flow supply to the brain and, at the same time, a cause of coronary steal syndrome and consequently angina pectoris.

Adult↗