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Biomedical subjects

J Kato

Publications and source records attributed to J Kato.

At least 343 records · Page 19Linked to original sources
PubMed1994

Trial of vaginal birth following cesarean section for arrest disorders of labor: analysis of patients with well-documented medical records.

We elucidated several controversial problems surrounding the vaginal trial in patients with prior abdominal delivery under the diagnosis of failure to progress or cephalopelvic disproportion, by conducting a prospective 6-year survey on the basis of patients who underwent prior operation for arrest disorders of labor (ADL). Of 45 full-term women who were defined as patients of prior ADL following a review of their past medical records, 28 patients underwent trial of labor and 75% (21/28) were successfully delivered of their infants vaginally. The seemingly critical determinants as to whether or not a vaginal birth is successful are the difference in neonatal weights between prior and current pregnancies as well as the difference between maternal obstetric conjugate and fetal biparietal diameter. These data suggest that patients who underwent prior cesarean section for indications of ADL have a high chance of safely succeeding if given a trial of labor under certain exclusionary criteria.

Adult↗
PubMed1994

Comparison of inhibition of Escherichia coli topoisomerase IV by quinolones with DNA gyrase inhibition.

In order to examine the inhibitory activities of quinolones against topoisomerase IV, both subunits of this enzyme, ParC and ParE, were purified from Escherichia coli. The specific activity of topoisomerase IV decatenation was found to be more than five times greater than that of topoisomerase IV relaxation. Thus, the decatenation activity of topoisomerase IV seems the most relevant activity for use in studies of drug inhibition of this enzyme. Although topoisomerase IV was less sensitive to quinolones than DNA gyrase, the 50% inhibitory concentrations for decatenation were significantly lower than those for type I topoisomerases. Moreover, there was a positive correlation between the inhibitory activity against topoisomerase IV decatenation and that for DNA gyrase supercoiling. These results imply that topoisomerase IV could be a target for the quinolones in intact bacteria and that quinolones could inhibit not only supercoiling of DNA gyrase but also decatenation of topoisomerase IV when high concentrations of drug exist in bacterial cells.

4-Quinolones↗
PubMed1994

Production and release of polyphosphate by a genetically engineered strain of Escherichia coli.

A recombinant strain of Escherichia coli MV1184, which contains plasmid-borne genes encoding the phosphate-specific transport (Pst) system and polyphosphate (polyP) kinase, accumulated high levels of Pi and released polyP into the medium. PolyP could be separated from the culture supernatant by DEAE-Toyopearl 650M chromatography and identified by high-resolution 31P nuclear magnetic resonance spectroscopy. Once E. coli recombinants accumulated high levels of polyP, they released polyP concomitantly with Pi uptake. PolyP release did not accompany the decrease in the cell density, indicating that it is not simply a result of cell lysis. PolyP release ceased when Pi became depleted in the medium and resumed upon addition of Pi to the medium. When Pi uptake was inhibited by 0.1 mM carbonyl cyanide m-chlorophenylhydrazone (CCCP), no polyP release was observed. Furthermore, neither Pi uptake nor polyP release occurred when cells were incubated at 4 degrees C. These findings suggest that the occurrence of polyP release is a possible mechanism that limits a further increase in the cellular polyP concentration in E. coli recombinants. High-resolution 31P nuclear magnetic resonance spectroscopy also detected a surface pool of polyP in intact cells of the E. coli recombinant. The polyP resonance increased when cells were treated with EDTA and broadened upon the addition of a shift reagent, praseodymium. Although the mechanism of surface polyP accumulation is unclear, surface polyP seems to serve as the source for polyP release.

Biological Transport, Active↗
PubMed1994

Cloning and characterization of a Pseudomonas aeruginosa gene involved in the negative regulation of phosphate taxis.

Pseudomonas aeruginosa PAO1 exhibited a positive chemotactic response to P(i). The chemotactic response was induced by P(i) limitation. An alkaline phosphatase (AP) constitutive mutant showed a chemotactic response to P(i), regardless of whether the cells were starved for P(i). Sequence analysis and complementation studies showed that the P. aeruginosa phoU gene was involved both in the regulation of AP expression and in the induction of P(i) taxis. However, unlike AP expression, P(i) taxis was not regulated by the phoB gene product.

Alkaline Phosphatase↗
PubMed1994

Improved recovery of myelosuppression following chemotherapy in mice by combined administration of PSK and various cytokines.

Granulocyte-colony-stimulating factor (G-CSF), granulocyte/macrophage-colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) were used in combination with PSK, a protein-bound polysaccharide extracted from mycelium of Coriolus versicolor (strain CM101), in myelosuppressed mice. The myelosuppression model consisted of BDF1 mice who received 150 mg/kg 5-fluorouracil (5-FU) intravenously. The peripheral blood leukocyte count during the recovery stage was significantly increased when these cytokines were administered with PSK compared to when the cytokines were used individually. In vitro colony assay revealed that the combination of PSK and any of GM-CSF, IL-3 or stem cell factor (SCF) showed a greater increase in colony numbers than when these materials were administered individually, although G-CSF did not show a synergistic effect with PSK. When bone marrow cells were obtained from mice which had been given PSK or IL-3, the colony assays were made in the presence of PSK or IL-3 in vitro. The greatest increase in the numbers was observed in colonies of the cultured group in the presence of IL-3 after the PSK priming. However, the colony formation potential of PSK was not inhibited by addition of anti-SCF antibody. The above results indicate that the combined administration of PSK with G-CSF, GM-CSF or IL-3 increased the hematological recovery of myelosuppressed mice. Moreover, the phase at which PSK has effects on hematopoietic cells seems to be at a more immature level than with IL-3. The combined administration of PSK and the above cytokines may improve myelosuppression after chemotherapy in patients with malignancy.

Animals↗
PubMed1994

Chronic idiopathic neutropenia associated with abnormal expression of granulocyte colony-stimulating factor mRNA of bone marrow stromal cells.

Chronic idiopathic neutropenia is an uncommon condition characterized by a low level of neutrophils without any causative disease. We report the details of 4 patients whose stromal cytokine mRNA expressions were examined by reverse transcription polymerase chain reaction. Three patients showed a lower expression of granulocyte colony-stimulating factor (G-CSF) mRNA both in constructive and lipopolysaccharide (LPS)-induced conditions and normal colony forming unit-granulocyte-macrophage (CFU-GM) from the bone marrow cells. One patient showed an increase of G-CSF mRNA and a decrease of CFU-GM. No abnormal expression of other cytokines including interleukin (IL)-1 beta, IL-6 and IL-8 were observed. These findings indicate that cytokine mRNA analysis of stromal cells is useful for elucidation of the etiology.

Adult↗
PubMed1994

[Intrabronchial neurilemmoma: a case report].

A 62-year-old woman who was pointed out abnormal shadow at left middle lung field in chest X-ray was followed up as a hamartoma from 1989. In this period, the tumor was growing up in chest X-ray and occupying the left segmental bronchus (B3) in bronchofiberscopic study. It was suspected neurilemmoma by the final biopsy examination. Left upper lobectomy was performed and pathohistological diagnosis was typical neurilemmoma that consist of Antoni type A and Antoni type B. Intrapulmonary or intrabronchial neurilemmoma is rare and only 20 cases have been reported in the Japanese literature.

Bronchial Neoplasms↗
PubMed1994

[Effects of ketamine on somatosympathetic reflex discharges in cats].

Effects of ketamine on somatosympathetic reflex discharges induced from sympathetic trunk with electrical stimulation of superficial peroneal nerve were investigated in 51 cats under anesthesia with urethane and alpha chloralose. These reflex discharges through spinal cord and medulla oblongata consist of two components, A and C reflexes, which are derived from somatic myelinated and unmyelinated afferent fiber respectively. Amplitudes of both A and C reflex potentials were depressed significantly after intravenous injection of ketamine 10 mg.kg-1. The maximum depression was observed 5 min after administration. In decerebrated cats with surgical transection at the midbrain, both A and C reflexes were also depressed after administration of the same dosages, and the maximum level of the depression was more profound than that in brain intact cats. After intrathecal injection of ketamine 1 mg.kg-1 to the lumbar spinal region, a slight depression of C reflex was found, but, dosages of 10 mg.kg-1 significantly depressed both A and C reflexes to the similar levels as those in iv injection to brain intact cats. The maximum depression was observed 30 min after administration. The depressive effects on both reflexes of intravenous ketamine 10 mg.kg-1 were not antagonized by naloxone 0.06 mg.kg-1 in brain intact cats. These results suggest that the suppressive effects of ketamine on somatosympathetic reflexes are caused by direct inhibition of medulla oblongata and spinal cord, whereas supra-midbrain regions may be activated by ketamine, and the effect of ketamine is predominant on medulla oblongata in this situation rather than on the spinal cord.

Action Potentials↗
PubMed1994

[Basic and clinical studies on sex hormone receptors].

Sex hormone, an essential hormone in reproduction, acts upon the tissues through binding to its receptors. Thus, the study on the receptors is essential for understanding the reproductive processes, physiologically or pathologically. With the advent of molecular biology, receptorology in our field has rapidly developed. In this lecture, we presented our recent findings on the receptor and its gene expression, together with some brief overview on the development of the receptor study, basically or clinically. I. Basic study. 1) Methology: A specific and highly sensitive quantitative RT-PCR assay for measurement of the steroid hormone receptor (SHR) mRNA was developed. 2) Rat progesterone receptor (PR) cDNA, especially PR-BcDNA, was partially cloned. Using primers designed upon the cloned cDNA, two distinct different promoters was found to exist in PR-A and B gene expression in the rat. 3) Tissue specificity of gene expression of the SHRs in the central and peripheral tissues: The synthesis of the receptor protein was regulated mostly on the level of transcription. In some tissues, however, the receptor synthesis was regulated posttranscriptionally. Gene expression of the SHRs was widely distributed even in non-target tissue, indicating the existence of 'basic action' of SH on the tissues. 4) Primate monkey studies: SHR, especially PR, was localized mostly in the preoptic hypothalamic region and hypophysis in contrast with its wide distribution in the rat brain, suggesting the more limited feedback site of progesterone in women. 5) Brain sex differentiation and acquisition of steroid sensitivity: Region-specific and dynamic appearance of SHRs during peri- and postnatal development seemed to a major determinant of sex differentiation and hormone sensitivity' acquisition in female rats. Based upon analysis of PR-A and B mRNAs, gene expression of PR-B was first 'turn on', followed by PR-B gene expression. Progesterone seemed to be associated with 'termination' of the critical period of sex differentiation in the brain. 6) Thyroid hormone may be a regulator of synthesis and gene expression of the PR in rat cerebral cortex. Arachidonic acid, released from cell membrane, regulated SHRs in a non-competitive way, indicating some 'second messenger' role. Cross-talk might exist between the membrane factor and SHR. 7) Antisense mRNA against GnRHmRNA, SH2RNA, was identified in rat brain. Most interestingly, there was a reciprocal relationship between GnRHmRNA and SH2RNA, suggesting some GnRHmRNA regulatory mechanism other than previously thought. 8) Depression of the GnRH receptor (GnRHR)mRNA level by GnRH agonist indicated another mechanism on down-regulation of GnRHR.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1994

[Liver cirrhosis in primary hemochromatosis and Wilson's disease].

Iron is an essential element in all living cells because it serves machineries for biological oxidation including hemoglobin, cytochrome c oxidase, etc. Copper is also essential for mammalian life since copper is the prosthetic element of several life-essential enzymes. Although intracellular excessive iron and copper were usually sequestrated in ferritin and metallothionein molecules, accumulation of excess iron and copper may also cause severe tissue injury by including oxyradicals and lipid peroxidation and eventually bring about tissue fibrosis such as liver cirrhosis. Hemochromatosis and Wilson's disease are known as iron and copper accumulation disorders, respectively. In this chapter, we review the cirrhosis in hemochromatosis and Wilson's disease.

Hemochromatosis↗
PubMed1994

The immunostimulant OK-432 enhances liver regeneration after 90% hepatectomy in rats.

The effect of reticuloendothelial system activation on liver regeneration after 90% hepatectomy was investigated. OK-432, a killed streptococcal preparation that increases reticuloendothelial system activity, was administered to rats before 90% partial hepatectomy. Pretreated rats showed marked improvement in long-term survival: 87% (18 of 23) survived beyond 42 hr, compared with only 44.2% (24 of 52) of controls (p < 0.05). Survival was determined by means of life-table analysis and regeneration response by means of bromodeoxyuridine labeling index of hepatic DNA. OK-432 pretreatment had significantly increased bromodeoxyuridine labeling index 18, 24, and 42 hr after partial hepatectomy (p < 0.05). The results indicate that reticuloendothelial system activation by OK-432 before 90% partial hepatectomy enhances liver regeneration and improves survival, but these factors may not be related. The improved survival may be because of less infection in macrophage-stimulated animals or more rapid clearance of hypotension-causing vasoactive compounds.

Adjuvants, Immunologic↗
PubMed1994

Interleukin-6 enhances hepatic transferrin uptake and ferritin expression in rats.

To explore a mechanism of interleukin (IL)-6-induced hypoferremia in rats, iron metabolism was investigated both in vivo and in vitro. Recombinant IL-6 was intraperitoneally administered to male Wistar rats and the serial change of parameters related to iron metabolism was examined. After administration of IL-6, plasma IL-6 concentration increased rapidly, reached its maximum in 1 hr and thereafter decreased quickly. Plasma IL-6 3 hr after IL-6 injection (50 micrograms/kg) was 3 units/ml, which is a concentration capable of inducing hepatic 125I-labeled transferrin uptake in vitro using isolated hepatocytes. Plasma iron concentration and transferrin saturation had decreased to approximately one third of the initial level within 3 hr and then recovered. Total iron binding capacity remained unchanged for 6 hr, then began to decrease. Red blood cell count and hemoglobin concentration showed no remarkable changes during this period. By ferrokinetic study with plasma that contained iron 59-labeled transferrin, the plasma iron disappearance half time, calculated from the disappearance curve, was significantly shortened from 55 min to 22 min by IL-6 treatment (p < 0.01). The ferritin concentration in the liver was increased significantly after the administration of IL-6 (p < 0.001), but transiently decreased in the spleen. The plasma ferritin showed a gradual increase during the 6-hr period after IL-6 injection. The uptake of 125I-labeled diferric transferrin by isolated hepatocytes was increased by IL-6 treatment and this increment was inhibited by addition of 100-fold excess unlabeled transferrin. On the other hand, no significant increment of 125I-labeled diferric transferrin uptake was observed in Kupffer cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Point mutation of aldehyde dehydrogenase-2 gene in mutant strains of Long-Evans rats.

Long-Evans Cinnamon (LEC) and Long-Evans Agouti (LEA) rats are mutant strains established from Long-Evans rats. LEC rats display hereditary hepatitis and spontaneous hepatocellular carcinoma, but LEA rats do not develop liver diseases. We previously demonstrated that LEC rats had an impairment of liver aldehyde dehydrogenase (ALDH) activities, and all LEC rats which were fed with a liquid diet containing 5% ethanol died within 2 weeks. In the present study, we also found that LEA rats could not metabolize ethanol and died after being fed the same diet. Remarkably, in the liver of LEA rats, low Km ALDH activities were suppressed as much as in LEC rats. These results suggested that both LEC and LEA rats have hereditary deficiencies in ALDH. Nucleotide sequence analysis of ALDH2 genes in both LEC and LEA rats demonstrated that the point mutation of the codon for residue 67 encoding Gln to Asp was observed; this was not so in either Long-Evans rats or Wistar rats. This mutation in ALDH2 genes may cause inactivation of ALDR activity in LEC and LEA rats.

Aldehyde Dehydrogenase↗
PubMed1993

Cloning, sequence and characterization of the polyphosphate kinase-encoding gene (ppk) of Klebsiella aerogenes.

Polyphosphate kinase (PPK) catalyzes the formation of polyphosphate (polyP). The PPK-encoding gene (ppk) has been cloned from Klebsiella aerogenes ATCC9621. The gene possessed an open reading frame of 2055 bp capable of encoding a putative polypeptide with a deduced M(r) of 80,157. This polypeptide showed 93% similarity to the Escherichia coli PPK. The nucleotide sequence of the promoter region of K. aerogenes ppk differed from that of the previously sequenced E. coli ppk. A putative pho box sequence was found in the promoter region of K. aerogenes ppk. The expression of lacZ from the ppk promoter was increased in E. coli MV1184 under conditions of phosphate (Pi) limitation, but not in E. coli ANCS3 (phoB-), indicating that the ppk promoter is regulated by the phoB product. Increased levels of specific PPK activity were shown by expressing the cloned ppk at high levels, resulting in increased accumulation of polyP in E. coli.

Amino Acid Sequence↗
PubMed1993

Two new monoclonal antibodies against the alpha subunit of the human insulin-like growth factor-I receptor.

Recently, we have reported three monoclonal antibodies (mAbs) against purified human placental insulin-like growth factor (IGF)-I receptors. These antibodies, in contrast to the well-studied mAb alpha IR-3, stimulate binding of IGF-I and IGF-II to the receptor and DNA synthesis as well [Xiong, et al., Proc. Natl. Acad. Sci. U.S.A. 1992(89), 5356]. Here we describe two additional mAbs, 1H7 and 2C8, against the IGF-I receptor that have characteristics different from either alpha IR-3 or our previously reported mAbs. Both 1H7 and 2C8 bind to the alpha subunit of the IGF-I receptor as determined by immunoblotting. MAb 1H7 inhibited the binding of IGF-I and IGF-II to the IGF-I receptor while 2C8 had no effect on the binding of either ligand to the receptor. When their effects on DNA synthesis were examined using NIH 3T3 cells expressing human IGF-I receptors, 1H7 inhibited basal and IGF-I- or IGF-II-stimulated DNA synthesis whereas 2C8 stimulated basal DNA synthesis but provided no synergism in the presence of IGF-I or IGF-II.

3T3 Cells↗
PubMed1993

Chemotaxis away from thiocyanic and isothiocyanic esters in Pseudomonas aeruginosa.

Negative chemotaxis, the movement of organisms away from chemicals, was investigated in Pseudomonas aeruginosa using a rapid videotape method. Digital image processing was used to detect changes in bacterial numbers near the mouth of a capillary containing a test chemical. P. aeruginosa was found to be repelled by thiocyanic and isothiocyanic esters including allyl isothiocyanate, ethyl thiocyanate, methyl isothiocyanate and methyl thiocyanate. Particularly, the movement of bacteria away from methyl thiocyanate was so drastic that bacterial numbers near the mouth of the capillary decreased by approximately 80% within 30 s after the start of observation. Mutant strains, fully motile but lacking positive chemotaxis, did not escape away from the esters, suggesting a common mechanism between positive and negative chemotaxes in this organism.

Chemotaxis↗