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Biomedical subjects

K Kikuchi

Publications and source records attributed to K Kikuchi.

At least 811 records · Page 45Linked to original sources
PubMed1992

[Study on uric acid metabolism in patients with primary aldosteronism].

This study was conducted to elucidate renal uric acid metabolism in patients with primary aldosteronism (PA;16 cases) as compared with normotensive subjects (NT;25 cases) and essential hypertensives (EHT;51 cases). All subjects were hospitalized and received a regular diet(Na;120 mEq,K;75 mEq,daily) for more than two weeks, after which renal clearance tests were performed, and serum uric acid(SUA), fractional excretions of uric acid(FEUA), sodium(FENa), and inorganic phosphorus(FEP) were evaluated. Plasma aldosterone concentration(PAC) was measured in 16 patients with PA before treatment and in 8 patients after adrenalectomy. SUA was lower in PA than in either NT or EHT, and this lowering was more obvious in male subjects. In NT, PA and EHT, FEUA, an index of renal excretion of uric acid, correlated negatively with SUA and positively with FENa and FEP, which reflected sodium reabsorption at the renal total tubules and proximal tubules, respectively. Although FENa was nearly the same in all the three groups, FEUA and FEP were significantly higher in PA than in EHT or NT. However, no significant correlation was found between PAC and SUA or FEUA in PA. In PA a significant increase of SUA, and decreases of FEUA and FEP were observed after the removal of adenoma compared to before the surgery. These results suggest that uric acid transport might be closely related to sodium transport in the renal tubules, particularly at the proximal site, and also lead to the conclusion that the lower SUA in PA resulted from the suppression of reabsorption and/or an enhancement of secretion of uric acid in the proximal tubules, being related to the so-called escape phenomenon.

Adenoma↗
PubMed1992

Production of macrophage colony-stimulating factor by adult murine parenchymal liver cells (hepatocytes).

The activity of macrophage colony-stimulating factor (M-CSF) was found in the culture supernatant of mouse parenchymal liver cell fractions in a bone marrow colony-forming assay. The activity of an M-CSF-like substance purified by a four-step procedure was neutralized by goat anti-mouse M-CSF antiserum. M-CSF mRNA was detected in cellular RNA prepared from cultured parenchymal liver cell fractions by Northern blot analysis and also in cultured parenchymal liver cells by in situ hybridization. These results indicate that parenchymal liver cells have the capacity to produce M-CSF. We discuss the role of M-CSF in hematopoiesis, the immune response, and other biological phenomena.

Acrylic Resins↗
PubMed1992

Effects of running training on in vitro brown adipose tissue thermogenesis in rats.

Brown adipose tissue (BAT) is a major site of nonshivering thermogenesis (NST) during cold acclimation for most mammals. Repetitive nonthermal stress such as immobilization has been shown to enhance the capacity of NST as cold acclimation. In the present study, the effects of running training, another type of nonthermal stress, were investigated on in vitro thermogenesis and the cellularity of interscapular BAT in rats. The rats were subjected to treadmill running for 30 min daily at 30m/min under 8 degrees inclination for 4-5 weeks. In vitro thermogenesis was then measured in minced tissue blocks incubated in a Krebs-Ringer phosphate buffer containing glucose and albumin at 37 degrees C, using a Clark type oxygen electrode. The trained rats showed less body weight gain during the experiment. The weights of BAT and epididymal white adipose tissue were smaller in the trained rats. Noradrenaline- and glucagon-stimulated oxygen consumption were also significantly smaller in the trained rats. The tissue DNA level was greater in the trained rats, but the DNA content per tissue pad did not significantly differ. The results indicate that running training reduces BAT thermogenesis, possibly as an adaptation to conserve energy substrates for physical work.

Adipose Tissue, Brown↗
PubMed1992

The reaction of Aspergillus niger catalase with methyl hydroperoxide.

The formation of Compound I from Aspergillus niger catalase and methyl hydroperoxide (CH3OOH) has been investigated kinetically by means of rapid-scanning stopped-flow techniques. The spectral changes during the reaction showed distinct isobestic points. The second-order rate constant and the activation energy for the formation of Compound I were 6.4 x 10(3) M-1s-1 and 10.4 kcal.mol-1, respectively. After formation of Compound I, the absorbance at the Soret peak returned slowly to the level of ferric enzyme with a first-order rate constant of 1.7 x 10(-3) s-1. Spectrophotometric titration of the enzyme with CH3OOH indicates that 4 mol of peroxide react with 1 mol of enzyme to form 1 mol of Compound I. The amount of Compound I formed was proportional to the specific activity of the catalase. The irreversible inhibition of catalase by 3-amino-1,2,4-triazole (AT) was observed in the presence of CH3OOH or H2O2. The second-order rate constant of the catalase-AT formation in CH3OOH was 3.0 M-1 min-1 at 37 degrees C and pH 6.8 and the pKa value was estimated to be 6.10 from the pH profile of the rate constant of the AT-inhibition. These results indicate that A. niger catalase forms Compound I with the same properties as other catalases and peroxidases, but the velocity of the Compound I formation is lower than that of the others.

Animals↗
PubMed1992

Can the chest tube draining the pleural cavity with persistent air leakage be removed?

The pleural drain with persistent air leak in six selected patients after pulmonary surgery was clamped or removed without causing pulmonary collapse. In all the patients, air leak through the chest tube was present when speaking or coughing but not seen when breathing normally at rest or taking deep breaths. The fact that the chest tube could be removed in selected patients is explained by supposing the air leakage through an alveolopleural fistula is dependent on pressure difference between the alveoli and the pleural cavity, and this was confirmed in a rethoracotomy case for persistent air leak. Removal of the chest tube following the above-mentioned rationale would reduce the number of rethoracotomy cases for air leak and facilitate early removal of the chest tube in some patients.

Aged↗
PubMed1992

Functional analysis of mononuclear cells infiltrating into tumors. VI. The effect of lymphocyte chemotactic factors on lymphocyte adhesion to endothelial cells.

We have analyzed mechanisms controlling infiltration of T lymphocytes into tumor tissues. A lymphocyte chemotactic factor-b (LMF-b) produced by tumor infiltrating CD4+ T lymphocytes was purified. LMB-b was specifically chemotactic for CD8+ T lymphocyte. Furthermore, LMF-b augmented lymphocyte adhesion to high endothelial venule (HEV) cells. The binding of CD8+ T cells to HEV cells was specifically augmented by LMF-b. The LMF-b primarily acted on T lymphocytes, whereas tumor necrosis factor as well as IFN-gamma acted on HEV cells or fibroblast cells. The binding of lymphocytes to fibroblast cell line was not augmented by LMF-b. The augmentation of lymphocyte adhesion to endothelial cells by LMF-b was mediated by the lymphocyte function associated antigen-1/intercellular adhesion molecule (LFA-1/ICAM) pathway, the CD2/LFA-3 pathway, and the very late antigen-4/culture supernatant-1 (VLA-4/CS-1) pathway.

Animals↗
PubMed1992

Increase in potential activities of protein phosphatases PP1 and PP2A in lymphoid tissues of autoimmune MRL/MpJ-lpr/lpr mice.

The differential assay conditions for protein phosphatases PP1, PP2A, and PP2C were extensively studied by using crude extracts from mouse lymphoid tissues as enzyme sources. Under these conditions, the protein phosphatase activities were measured in MRL/MpJ-lpr/lpr mice (MRL/lpr mice), autoimmune-prone mice, and MRL/MpJ(-)+/+ mice (MRL/+/+ mice) and C3H/HeJ mice as the controls. In MRL/lpr mice, significant alterations in protein phosphatase activities from those in the control mice were demonstrated. In spleen and liver from MRL/lpr mice, potential activities of PP1 and PP2A were distinctly elevated over those of the control mice. These elevations appeared to be due to accumulation of the abnormal lymphocytes that emerged in MRL/lpr mice. Although the PP1 activity in MRL/lpr lymph nodes was lower than those of normal spleen and thymus, it was greatly increased by Co(2+)-trypsin treatment so that the PP1 activity of MRL/lpr lymph nodes was the highest among those of all the tissues examined. In contrast, PP2C activity showed no remarkable alteration in the autoimmune disease model mice as compared with that in the control mice. These results demonstrated a specific elevation in potency of protein dephosphorylation in the tissues of MRL/lpr mice, suggesting a new explanation for the defect in signal transduction in this disease.

Animals↗
PubMed1992

Differential modulation of bFGF receptors by TGF-beta in adult skin, scleroderma skin, and newborn foreskin fibroblasts.

Effects of transforming growth factor beta (TGF-beta) on proliferative responses to basic fibroblast growth factor (bFGF) were studied in human diploid fibroblasts cell strains derived from three different sources: adult skin, scleroderma, and newborn foreskin. All three types of cell strains were similarly responsive to TGF-beta, whereas adult skin fibroblasts were significantly more responsive to bFGF. Incubation of cells with TGF-beta prior to bFGF addition substantially increased responsiveness of adult skin fibroblasts to this latter cytokine, slightly increased that of scleroderma fibroblasts, and decreased that of foreskin fibroblasts. Modulation of bFGF receptors by TGF-beta correlated positively with these mitogenic effects. Adult skin fibroblasts showed increases of both high- and low-affinity receptors and scleroderma fibroblasts showed small increases of high-affinity receptors only, whereas foreskin fibroblasts showed no changes. Heparitinase treatment of adult skin fibroblasts during TGF-beta pre-incubation resulted in reduced bFGF binding to low-affinity receptors and reduced mitogenic response to bFGF, suggesting that the TGF-beta-stimulated increase of low-affinity receptors in these cells contributes to the observed enhanced mitogenic effects of bFGF. Abnormal responses of scleroderma fibroblasts to TGF-beta/bFGF stimulation, particularly failure to synthesize low-affinity receptors in response to TGF-beta, adds a new characteristic to the fibrotic phenotype of scleroderma fibroblasts.

Adult↗
PubMed1992

mRNA levels of catalytic subunits of protein phosphatases 1, 2A, and 2C in hepatocarcinogenesis.

The mRNA levels of three phosphoseryl/phosphothreonyl protein phosphatases, PP1, PP2A and PP2C, in rat liver have been determined by Northern blot analysis in various stages of rat chemical hepatocarcinogenesis using a Solt-Farber model. Five weeks after administration of diethylnitrosamine, the mRNA levels of PP1 alpha, PP2A and PP2C were elevated 8, 29 and 11 times, respectively, as compared to those of the control livers. However, in primary hepatoma induced according to the Solt-Farber model, the mRNA levels of all three protein phosphatases were dramatically decreased to normal levels or even to much lower levels, whereas the mRNA level of glutathione S-transferase placental form, a tumor marker protein, was greatly elevated as compared with that of the control livers. In a poorly differentiated hepatoma AH13, a line of rat ascites hepatoma, the mRNA level of PP1 alpha was 5.6 times higher than that of the control livers, whereas the mRNA lever of PP2C was almost the same as that of the control livers and the level of PP2A mRNA was distinctly lower than that of the control livers. These data appear to suggest some involvement of protein phosphatases in hepatocarcinogenesis.

Animals↗
PubMed1992

VLA-4 molecules on tumor cells initiate an adhesive interaction with VCAM-1 molecules on endothelial cell surface.

To elucidate the role of VLA-4 (alpha 4 beta 1 integrin) in tumor metastasis, we have transfected cDNA coding alpha 4 subunit into human fibrosarcoma (HT1080) cells. VLA-4-overexpressing HT-VC1 cells exhibited increased ability to interact with known ligands for VLA-4, such as CS1 peptide and VCAM-1 (vascular cell adhesion molecule-1). In addition, the in vitro invasive ability of HT-VC1 cells was augmented and the mRNA for type IV collagenase was increased in HT-VC1 cells. The induction of VCAM-1 molecules on lung endothelial cells of nude mice by tumor necrosis factor-alpha treatment resulted in augmentation of in vivo HT-VC1 cell adhesion to the lung endothelial cells. Thus, the VLA-4 molecules on tumor cells initiate an adhesive interaction with VCAM-1 molecules on endothelial cells, that is important for hematogenous metastasis.

Animals↗
PubMed1992

Gene expression of growth-related proteins and ECM constituents in response to unilateral nephrectomy.

To identify the specific regulatory mechanism associated with the events following unilateral nephrectomy, we measured the levels of mRNA encoding for extracellular matrix (ECM) constituents, for protooncogenes, and for proliferating cell nuclear antigen (PCNA) in renal cortex and glomeruli. One hour after left nephrectomy, c-jun and c-fos mRNA levels in renal cortex increased rapidly and then decreased rapidly to the control level, whereas c-myc and PCNA mRNA levels showed a slower and more sustained increase, with a peak at 6 h after nephrectomy, and then decreased to the control level after 7 days. mRNA levels for basement membrane components including alpha 1-chain of type IV collagen, laminin B1 and B2 chains, and heparan sulfate proteoglycan core protein were significantly increased in renal cortex at 12 h after nephrectomy, whereas those for interstitial collagens including alpha 1-chains of type I and type III collagen were unchanged following nephrectomy. On the other hand, the glomerular expression of all genes examined in this study showed little change during the experimental period. These results suggest that the time course of mRNA expression of ECM constituents is different from that of growth-related proteins in renal cortex and that glomerular mRNA levels for these components may not be associated with renal hypertrophy in the early stages following unilateral nephrectomy.

Animals↗
PubMed1992

Growth hormone rapidly activates insulin-like growth factor I gene transcription in vivo.

Many of the growth-promoting properties of GH are mediated by insulin-like growth factor I (IGF-I), a highly conserved circulating 70-amino acid peptide. Recent studies have shown that multiple mechanisms influence IGF-I gene expression, including transcription from two promoters, alternative RNA splicing, and variable polyadenylation. In order to determine how GH regulates IGF-I gene expression we have analyzed the response of hypophysectomized rats to a single ip injection of recombinant GH. A rise in hepatic IGF-I mRNA was detected within 2 h of GH treatment, with peak values of more than 15-fold above untreated animals by 4 h, and a decline by 16 h. A coordinate increase was seen in all IGF-I mRNA splicing and polyadenylation variants, indicating that neither alternative RNA processing nor differential poly A addition were altered by GH. Transcription run-on experiments using isolated hepatic nuclei and direct analysis of nuclear RNA demonstrated a rise in nascent IGF-I mRNA within 30 min of GH treatment, with peak levels reaching more than 10-fold above background by 2 h and declining by 6 h. As determined by RNase protection assays, transcripts directed by each promoter were coordinately and equivalently activated after GH. A single GH-responsive DNase I hypersensitive site was mapped in chromatin to the second IGF-I intron. This site exhibited rapid kinetics of induction which mirrored the pattern of transcriptional stimulation after GH treatment. These experiments show that GH enhances IGF-I expression in vivo by predominantly transcriptional mechanisms. The rapid kinetics of IGF-I gene activation and the temporally associated chromatin changes demonstrate a direct link between a GH-dependent signal transduction pathway and nuclear events.

Animals↗
PubMed1992

New method of detecting nitric oxide production.

Nitric oxide (NO) reacts with H2O2 to produce a rise in potent luminol-dependent chemiluminescence under neutral pH conditions. We applied this reaction to the continuous detection of NO released from the rat isolated perfused kidney with simultaneous pressure changes. Acetylcholine increased NO release dose-dependently with the pressure reduction. An NO synthesis inhibitor, NG-monomethyl-L-arginine, abolished the release. This inhibition was reversed by the addition of L-arginine.

Animals↗