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J Kato

Publications and source records attributed to J Kato.

At least 361 records · Page 20Linked to original sources
PubMed1993

Cell size-specific appearance of neuropeptide Y in the trigeminal ganglion following peripheral axotomy of different branches of the mandibular nerve of the rat.

The effect of peripheral axotomy of the mental nerve (MN) and the cutaneous branch of the mylohyoid nerve (MhN) on the appearance of neuropeptide Y-like immunoreactivity (NPY-IR) in cells in the trigeminal ganglion of the rat was examined with combined retrograde-tracing and immunohistochemistry. Retrograde-tracing with True Blue (TB) revealed that the cell-size spectrum of the trigeminal cells sending peripheral processes to the MN (TB MN cells) ranged from 75.9 to 1560.5 microns2 (or from 9.8 to 44.6 microns in diameter); approximately 53% of TB MN cells were 300-600 microns2. TB MhN cells ranged from 47.7 to 1261.5 microns2 (or from 7.8 to 40.1 microns in diameter); 56% of TB MhN cells were < 300 microns2. In the normal trigeminal ganglion, there were no NPY-IR cells. 14 days after MN transection, approximately 35% of TB MN cells displayed NPY-IR. The distribution of the cross-sectional areas of NPY-IR cells after MN transection was very similar to that of TB MN cells. Transection of MhN also induced the appearance of NPY-IR in the trigeminal ganglion but to a lesser extent (approximately 17% of TB MhN cells). The distribution of the cross-sectional areas of NPY-IR cells after MhN transection was similar to that of NPY-IR cells after MN transection. These results indicate that injury-evoked NPY-IR is specific for the medium- and large-sized ganglion cells.

Animals↗
PubMed1993

Functional interactions of the retinoblastoma protein with mammalian D-type cyclins.

The retinoblastoma gene product (Rb) can interact efficiently with two of three D-type G1 cyclins (D2 and D3) in vitro. Binding depended upon the minimal regions of Rb necessary for its growth-suppressive activity, as well as upon the D-type cyclin sequence motif shared with Rb-binding DNA tumor virus oncoproteins. Coexpression of the three D-type cyclins with the cyclin-dependent kinase (cdk4) in insect cells generated Rb kinase activity. By contrast, cyclins D2 and D3, but not D1, activated another such kinase, cdk2. Introduction of cyclin D2 and Rb into the Rb-deficient cell line SAOS-2 led to overt Rb hyperphosphorylation, whereas Rb, expressed alone or together with cyclin D1, remained unphosphorylated. Cyclin D2-dependent phosphorylation inhibited its binding to the transcription factor E2F and reversed the Rb G1 exit block in the cell cycle. Thus, all D-type cyclins do not function equivalently, and one of them plays a major role in reversing the cycle-blocking function of a known tumor suppressor.

Amino Acid Sequence↗
PubMed1993

Induction of nitric oxide synthase regulates atrial natriuretic peptide receptors in vascular smooth muscle cells.

In a previous study, we reported that cyclic GMP (cGMP) selectively down-regulates the atrial natriuretic peptide clearance receptor (ANPC receptor) in the vascular endothelial cells. The aim of the present study is to determine whether nitric oxide (NO) regulates ANP receptor by accumulating intracellular cGMP in cultured rabbit aortic smooth muscle cells. Treatment with interleukin-1 beta (IL-1), a cytokine known to induce NO synthase, dose-dependently increased the basal level of intracellular cGMP with a concomitant increase of nitrite in the conditioned media. These effects of IL-1 were attenuated in the presence of N omega-nitro-L-arginine. IL-1 (40 pM) significantly (P < 0.01) decreased [125I]atriopeptin III binding to the cells, an effect that was inhibited by N omega-nitro-L-arginine. Treatment with sodium nitroprusside (SNP) which releases NO also decreased [125I]atriopeptin III binding to the cells. In addition, further decrease in [125I]atriopeptin III binding following IL-1 or SNP treatment was observed in the presence of 0.1 mM zaprinast, a cGMP-specific phosphodiesterase inhibitor. Scatchard analysis of the binding data in the treated cells showed a decrease in Bmax without a significant change in Kd. Affinity cross-linking of [125I]atriopeptin III to the treated cells demonstrated a decrease in 70-kDa band corresponding to the ANPC receptor. MEanwhile, intracellular cGMP response to atriopeptin III was significantly (P < 0.01) enhanced in the cells pretreated with IL-1 or SNP despite the decrease in receptor density. These findings suggest that NO down-regulates the ANPC receptor by the accumulation of intracellular cGMP in cultured rabbit aortic smooth muscle cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗
PubMed1993

Regulation of iron metabolism in HepG2 cells: a possible role for cytokines in the hepatic deposition of iron.

In chronic inflammation it is reported that serum iron is depleted and hepatic iron is increased because of reticuloendothelial system iron blockade. However, recent studies indicate that hepatic parenchymal cells increase the uptake of transferrin-bound iron after in vivo stimulation with bacterial lipopolysaccharide, suggesting that endotoxemia itself or lipopolysaccharide-induced production of inflammation-related cytokines may also be responsible for this phenomenon. In this study the actions of inflammation-related cytokines on the synthesis of iron-binding proteins (transferrin and ferritin) and transferrin receptor and the uptake of transferrin-bound iron were investigated in a human hepatoblastoma cell line, HepG2, which is the most commonly used cell line for examining the regulation of hepatic protein synthesis by cytokines. The cells were exposed to interleukin-1 beta, interleukin-6 or tumor necrosis factor-alpha separately for 24 hr. In each cytokine treatment group, the level of transferrin, which is secreted into the conditioned medium, was found to be decreased compared with that of untreated cells. On the other hand, the biosynthesis of ferritin was markedly elevated after the same treatment. This increase in ferritin by cytokine treatment was diminished when deferoxamine was used concomitantly to deplete intracellular chelatable iron. After stimulation with interleukin-1 beta, interleukin-6 or tumor necrosis factor-alpha, 59Fe-labeled transferrin uptake into the cells was increased by 36%, 48%, or 18%, respectively, and this uptake was inhibited by the addition of excess unlabeled transferrin. A binding study with 125I-labeled diferric transferrin revealed that the three cytokines increased the number of transferrin receptors on the cell surface by 1.15-fold to 1.35-fold.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Hepatocellular↗
PubMed1993

DNA fingerprint analysis of a free-range koala population.

Thirty-six koalas in a free-range Queensland population were fingerprinted using an M13 probe in combination with MspI digestion. The technique was found to be highly repeatable, with estimates of 0.1-1.6% within-gel error and 0.1-2.5% between-gel error. Of the 43 different-size fingerprint bands produced in the population, only 2 bands were common to all 36 koalas. Ten bands were quite rare, occurring at a frequency of 0.2 or less. All 36 koalas had unique DNA fingerprints (probability of 1.88 x 10(-7)), which enabled them each to be uniquely identified. Despite this, there was still a high level of band sharing in the population (mean number of shared bands = 0.749). This level is much higher than that reported for humans, birds, cats, dogs, and cattle but not as high as that reported previously for Victorian koalas. This lack of genetic variation may influence the ability of the population to respond to stress situations, such as lack of food, habitat destruction, and disease.

Animals↗
PubMed1993

Appearance of neuropeptide Y-like immunoreactive cells in the rat trigeminal ganglion following dental injuries.

The effects of these injuries on the presence and distribution of neuropeptide Y (NPY)-immunoreactive (-IR) neurones were examined immunohistochemically. In the normal trigeminal ganglion: some perivascular nerves displayed NPY-IR but there were no NPY-IR ganglionic cells. Fourteen days after extraction or pulp exposure of the upper first molar, NPY-IR cells appeared in the maxillary region of the trigeminal ganglion. About 90% of the injury-evoked NPY-IR cells had medium to large diameters (more than 300 microns2 in cross-sectional area). Shallow cavity preparation, however, did not induce the appearance of NPY-IR cells in the trigeminal ganglion. These results indicate the dental injuries alter the primary sensory neurones in the trigeminal ganglion.

Animals↗
PubMed1993

Overproduction of riboflavin by an Arthrobacter sp. mutant resistant to 5-fluorouracil.

Antagonistic action between 5-fluorouracil (5-FU) and riboflavin (RF) was investigated. The growth of Arthrobacter sp. was inhibited by 5-FU at 5 x 10(-5) M, and the inhibition was reversed by RF at 5 x 10(-5) M. 5-FU-resistant mutants of Arthrobacter sp. were isolated and excreted RF in relatively high yields, but the wild-type strain excreted no RF. One of the mutants, strain No. 28-35, produced 223.2 micrograms ml-1 of RF in culture medium at 4 days.

Arthrobacter↗
PubMed1993

The ontogeny of gene expression of progestin receptors in the female rat brain.

The postnatal development of the progestin receptor (PR) system in the rat brain is a region-specific and stage-related process. In an attempt to analyze the molecular mechanism by which the dramatic change of gene expression of the PR occurs we have examined the level of PR mRNAs in the hypothalamus-preoptic area (HPOA) and cerebral cortex in development from fetal to postnatal stages of female rats. We used polymerase chain reaction to clone, from uterine cDNA, the cDNA corresponding to the steroid-binding domain of the PR forms 'A' and 'B' mRNA as well as the region around the translation-initiation site (ATG1) of the putative PR form 'B' mRNA. A quantitative reverse transcription-polymerase chain reaction assay was used to measure the level of mRNAs for PR forms 'A' and 'B' (total PR mRNAs) and PR form 'B'. There was a regional difference in the intracerebral distribution between the total and form 'B' mRNAs, indicating possible distinct mechanisms responsible for regulating the expression of the PR mRNAs. The PR mRNAs in the brain, already detectable 2 days before birth, increased at early neonatal stages. The total PR mRNAs in the cortex developed in a manner essentially similar to the PR protein at the early stages, but, surprisingly, unlike the receptor, the messages remained high at the later stages from day 18 to 8 weeks of life. On the other hand, the ontogeny of the cortical mRNA for form 'B', which predominantly existed in the region, resembled that of the cortical PR protein. In the HPOA the postnatal development of the form 'B' mRNAs was also roughly similar to the PR. These results suggest region-specific and stage-related gene expression of the PR isoform system in the developing brain: gene expression of form 'B' seems to be predominantly, first, "turned on" around birth, followed by form 'A' mRNA expression around days 8-12. Moreover, lowered levels of the cortical PR mRNAs in the propylthiouracil-induced hypothyroid rat, together with suppressed PR level, indicate a possible regulatory role of thyroid hormone on gene expression of the cortical receptor.

Amino Acid Sequence↗
PubMed1993

Production and characterization of specific asialoglycoprotein receptor antibodies.

Monoclonal antibodies (MoAbs) were produced by immunizing BALB/c mice with asialoglycoprotein receptor (AGPR) purified from human liver. The purity of AGPR was confirmed by SDS-polyacrylamide gel electrophoresis and by amino acid sequence. An enzyme-linked immunoassay revealed 24 monoclonal antibodies which reacted with human AGPR. By Western blot analysis, all antibodies recognized the 46 kDa human AGPR under the non-reduced conditions and four MoAbs recognized reduced protein. Two MoAbs reacted with AGPR derived from rat, rabbit and mouse liver under both non-reduced and reduced conditions, suggesting that we could obtain antibodies which reacted with AGPR epitopes shared by different species. In immunohistochemical studies, 30201-MoAb reacted with human liver tissue but not with other tissues. This antibody immunoprecipitated two major bands of 46 kDa and 39 kDa from [35S]-methionine metabolically labeled human hepatoma HepG2 cells. The determinant recognized by 30201-MoAb is a common epitope of AGPR which is present in different species and in both the precursor and maturation forms of the receptor.

Amino Acid Sequence↗
PubMed1993

Abnormal ethanol metabolism in Long-Evans Cinnamon rats, a mutant strain developing spontaneous hepatoma.

The Long-Evans Cinnamon (LEC) rat is a mutant strain established from Long-Evans rats. LEC rats display hereditary hepatitis and spontaneous hepatocellular carcinoma (HCC). We first tried to examine effects of ethanol consumption on the development of HCC, and fed a Lieber's liquid diet containing 5% ethanol to LEC rats. However the rats died within 2 weeks because of acute alcohol intoxication. In LEC rats, the concentration of ethanol and acetaldehyde in blood was significantly higher, and liver alcohol dehydrogenase activity was slightly lower and acetaldehyde dehydrogenase activities were remarkably suppressed compared to those of Wistar rats. These results suggest that LEC rats have hereditary deficiencies of ethanol and acetaldehyde metabolizing enzymes.

Acetaldehyde↗
PubMed1993

Direct binding of cyclin D to the retinoblastoma gene product (pRb) and pRb phosphorylation by the cyclin D-dependent kinase CDK4.

The product (pRb) of the retinoblastoma gene (RB-1) prevents S-phase entry during the cell cycle, and inactivation of this growth-suppressive function is presumed to result from pRb hyperphosphorylation during late G1 phase. Complexes of the cyclin-dependent kinase, cdk4, and each of three different D-type cyclins, assembled in insect Sf9 cells, phosphorylated a pRb fusion protein in vitro at sites identical to those phosphorylated in human T cells. Only D-type cyclins activated cdk4 enzyme activity, whereas cyclins A, B1, and E did not. When Sf9 cells were coinfected with baculovirus vectors encoding human pRb and murine D-type cyclins, cyclins D2 and D3, but not D1, bound pRb with high stoichiometry in intact cells. Introduction of a vector encoding cdk4, together with those expressing pRb and D-type cyclins, induced pRb hyperphosphorylation and dissociation of cyclins D2 and D3, whereas expression of a kinase-defective cdk4 mutant in lieu of the wild-type catalytic subunit yielded ternary complexes. The transcription factor E2F-1 also bound to pRb in insect cells, and coexpression of cyclin D-cdk4 complexes, but neither subunit alone, triggered pRb phosphorylation and prevented its interaction with E2F-1. The D-type cyclins may play dual roles as cdk4 regulatory subunits and as adaptor proteins that physically target active enzyme complexes to particular substrates.

Adenosine Triphosphate↗
PubMed1993

Intracellular metabolism and cytotoxicity of transferrin-neocarzinostatin conjugates of differing molar ratios.

Transferrin-neocarzinostatin (NCS) conjugates with differing molar ratios of drug to protein were synthesized and their intracellular metabolism was investigated. The conjugate mixtures of transferrin-NCS were separated by DEAE-Sephacel column chromatography. The separated molecular species were examined with respect to binding affinity to transferrin receptor, cytotoxicity and intracellular metabolism using the human leukemia cell line, K562. Transferrin-NCS conjugate is capable of binding to transferrin receptors specifically and its reactivity became weaker as the ratio of bound NCS to transferrin was increased. Transferrin-6NCS did not bind measurably to the receptor. On the other hand, the cytotoxicity was augmented when the number of NCS molecules bound per molecule of transferrin was increased to 4NCS/transferrin, while transferrin-5NCS and transferrin-6NCS species exhibited low activity. Examination of the kinetics of metabolism by pulse chase study using 125I-labeled ligand indicated that unconjugated transferrin and transferrin-NCS conjugates were internalized in similar ways, although the degradation of internalized conjugate was more marked in the case of transferrin-4NCS than transferrin-1NCS. Thus, the molar ratio of transferrin-drug conjugate could be optimized with respect to both the binding activity to receptor and the intracellular metabolic pathway.

Animals↗
PubMed1993

Abnormal hepatic iron accumulation in LEC rats.

The LEC (Long-Evans cinnamon) rat is a mutant strain displaying hereditary hepatitis and spontaneous hepatocellular carcinoma, and shows abnormal hepatic copper accumulation similar to that occurring in Wilson's disease. We evaluated the iron metabolism of LEC rats compared to LEA (Long-Evans agouti) rats. Hepatic iron and ferritin concentrations were remarkably increased depending on age in LEC rats but not in LEA rats. Increased hepatic iron is normally associated with decreased serum transferrin and total iron binding capacity in hepatic iron overload. In LEC rats, however, both serum transferrin and total iron binding capacity increased with increasing hepatic iron. This increase of serum transferrin and hepatic iron may be an additional important factor contributing to liver injury in LEC rats.

Age Factors↗
PubMed1993

Genetic improvement of Escherichia coli for enhanced biological removal of phosphate from wastewater.

The ability of Escherichia coli MV1184 to accumulate inorganic phosphate (Pi) was enhanced by manipulating the genes involved in the transport and metabolism of Pi. The high-level Pi accumulation was achieved by modifying the genetic regulation and increasing the dosage of the E. coli genes encoding polyphosphate kinase (ppk), acetate kinase (ackA), and the phosphate-inducible transport system (pstS, pstC, pstA, and pstB). Acetate kinase was employed as an ATP regeneration system for polyphosphate synthesis. Recombinant strains, which contained either pBC29 (carrying ppk) or pEP02.2 (pst operon), removed approximately two- and threefold, respectively, more Pi from minimal medium than did the control strain. The highest rates of Pii removal were obtained by strain MV1184 containing pEP03 (ppk and ackA). However, unlike the control strain, MV1184 (pEP03) released Pi to the medium after growth had stopped. Drastic changes in growth and Pi uptake were observed when pBC29 (ppk) and pEP02.2 (pst operon) were introduced simultaneously into MV1184. Even though growth of this recombinant was severely limited in minimal medium, the recombinant could remove approximately threefold more Pi than the control strain. Consequently, the phosphorus content of this recombinant reached a maximum of approximately 16% on a dry weight basis (49% as phosphate).

Biological Transport, Active↗
PubMed1993

Detection and levels of androgen receptor messenger ribonucleic acid in the rat brain by means of reverse transcription-polymerase chain reaction.

In order to examine the existence and level of androgen receptor messenger ribonucleic acid (ARmRNA) in the rat brain, reverse transcription-polymerase chain reaction (RT-PCR)-Southern blot analysis was carried out. Total RNA extracted from each tissue was reverse transcribed, followed by PCR with two oligonucleotide primers specific for a part (458 bp) of the androgen binding domain of the rat ARcDNA. It was confirmed by direct nucleotide sequencing that the amplified fragment corresponded to part of the rat ARcDNA. To detect and quantify the amplified fragments, a Southern blot analysis was carried out. The levels of amplified fragments were calculated from the standard curve obtained from graded diluted adrenal total RNAs. In the present study, it was revealed that the RT-PCR-Southern blot analysis possessed a high-degree of sensitivity and allowed the quantitative estimation of mRNA. With this method, amplified fragments were obtained from all five brain regions examined. The results indicate that ARmRNA is widely distributed in the whole brain. Moreover, since the ARmRNA level roughly paralleled the AR protein level, it seems that the AR protein level in the brain may be primarily regulated by the ARmRNA level.

Amino Acid Sequence↗
PubMed1993

Increased serum level of interleukin-5 in a patient with episodic angioedema and eosinophilia syndrome.

A case of episodic angioedema and eosinophilia syndrome is reported. An 18-year-old male suffered from monthly episodes of angioedema, pruritic papules, weight gain, and fever for twelve years. During the episodes, peripheral eosinophils and serum levels of interleukin (IL)-5, an eosinophil proliferating cytokine were elevated. Extensive evaluations disclosed neither visceral involvement nor evidence of parasitic infections, collagen diseases, or neoplastic disorders. Corticosteroid treatment brought about a dramatic clinical improvement concomitant with decrement of eosinophils and serum IL-5 was observed. These observations suggest that IL-5 may be a causative factor for this pathological state.

Adolescent↗