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Biomedical subjects

K Nitta

Publications and source records attributed to K Nitta.

At least 109 records · Page 6Linked to original sources
PubMed1998

Eicosapentaenoic acid inhibits mitogen-induced endothelin-1 production and DNA synthesis in cultured bovine mesangial cells.

The present study was designed to examine whether eicosapentaenoic acid (EPA) inhibits the production of basal or stimulated endothelin (ET)-1 by platelet-derived growth factor (PDGF)-BB or epidermal growth factor (EGF), and DNA synthesis in cultured bovine mesangial cells. PDGF-BB and EGF stimulated ET-1 secretion in a dose-dependent fashion in these cells. EPA (10-100 microM) exhibited dose-related inhibition of PDGF-BB- and EGF-stimulated ET-1 secretion. EPA had no inhibitory effects on basal ET-1 secretion in these cells. Moreover, 50 microM EPA significantly attenuated PDGF-BB- and EGF-stimulated [3H]thymidine incorporation into mesangial cells. Receptor-binding experiments showed that EPA competitively inhibited 125I-PDGF-BB or 125I-EGF binding to mesangial cell surface receptors. Scatchard analysis for PDGF-BB receptor or EGF receptor revealed a linear regression fit and one binding site. Pretreatment with 50 microM EPA suppressed the number of maximum binding sites, but did not affect the Kd values. These results indicate that EPA potentially inhibits mesangial cell ET-1 production, when stimulated by PDGF-BB or EGF. This inhibitory effect of EPA could be related to the attenuation of mesangial cell proliferation via inhibition of the binding of PDGF-BB or EGF to their receptors due to alteration of the physicochemical characteristics of the cell membrane.

Animals↗
PubMed1998

Plasma concentration of brain natriuretic peptide as an indicator of cardiac ventricular function in patients on hemodialysis.

The plasma concentration of human brain natriuretic peptide (BNP) was measured by immunoradiometric assay in patients on maintenance hemodialysis (HD) to assess the possible relationship between the plasma levels of this peptide and cardiac ventricular function, as judged by M-mode echocardiography. The plasma BNP levels in the pre-HD state were significantly higher (688.5 +/- 154.5 pg/ml) than those of healthy subjects (<40 pg/ml). In addition, the plasma BNP levels were slightly decreased during HD (post-HD, 617.3 +/- 157.1 pg/ml). There was no correlation between the plasma levels of BNP and body weight changes during HD. The mean plasma BNP level was significantly higher in the group of patients with a low left ventricular ejection fraction (EF < 60%) than in the group with a normal EF. In the patients as a whole, there was an inverse correlation between plasma BNP levels and EF. Moreover, a positive correlation was found between plasma BNP levels and left ventricular mass index (r = 0.57, p < 0.05). These results suggest that plasma BNP levels increase in response to chronic stimulation in accordance with increased cardiac load, and that they may be a possible indicator of reduced ventricular function in HD patients.

Atrial Natriuretic Factor↗
PubMed1998

Apoptotic cell death induced by physarumin (hemagglutinin from myxomycete, Physarum polycephalum).

Physarumin, a carbohydrate-binding protein (hemagglutinin or lectin), was isolated from the plasmodium of Physarum polycephalum. Physarumin agglutinated not only several species of erythrocytes but also tumor cells such as AH109A ascites hepatoma cells, sarcoma 180 ascites cells and mouse leukemia P388 cell lines. Physarumin had tumor cell growth-inhibitory activity, and induced the apoptosis of P388 cell lines. Physarumin-induced apoptosis required binding to a 68 kDa counter-receptor on the P388 cell surface. Since the agglutinating and antiproliferative activities of physarumin were inhibited by asialofetuin and thyroglobulin, respectively, it is suggested that physarumin reacts with the galactose moiety of carbohydrate chains of physarumin receptor.

Animals↗
PubMed1998

Mineral recovery system for a Closed Ecology Experiment Facility (CEEF).

A unique recovery system, which consists of electrodialysis (ED) and crystallization processes, is proposed for NaCl (salt) from waste water after oxidation of urine. NaCl recovery characteristics from the oxidized urine, which contains KCl and NO3- impurities, were experimentally evaluated. Concentrated NaCl/KCl mixed solution was obtained using the ED process from simulated oxidized urine and sweat. Large amounts of NO3- were contained in the concentrated solution. After the crystallization process, NaCl salt of 90% purity, containing less than 5% NO3-, could be recovered by crystallization from the solution at 90 degrees C because NaNO3 or KNO3 salt has high solubility in water at that temperature. The results show that the proposed mineral recovery system can recover NaCl from waste water in the CEEF.

Chemical Precipitation↗
PubMed1998

[Comparison of transarterial technique and paresthesia technique of axillary brachial plexus block].

Axillary brachial plexus blocks were established in 40 patients using transarterial technique (n = 20) or paresthesia technique (n = 20). Sensory and motor blockades of nerves supplying the upper extremity were compared at 10, 20 and 30 minutes after the injection of local anesthetics (1.5% plain mepivacaine 40 ml). Sensory blockades of the radial nerve and axillary nerve were significantly higher with transarterial technique than paresthesia technique. The incidence of analgesia of the radial nerve at 30 min was 100% with transarterial technique and 70% with paresthesia technique. Sensory blockades of the other nerves and motor blockades of all nerves did not show any significant differences between the two techniques. Proximal and distal spreads of the local anesthetic-contrast medium mixture within the axillary neurovascular sheath were studied in 20 patients. No statistically significant difference was observed in the spread of contrast agent between the two techniques. Transarterial technique is a recommendable method for hand surgery and especially indicated for the surgery of the area supplied by the radial nerve.

Adult↗
PubMed1998

[Relationship between glomerular epithelial cell injury and proteinuria in IgA nephropathy].

The present study was designed to elucidate whether glomerular epithelial cell (GEC) injury is associated with the mechanism of proteinuria in biopsy-proven IgA nephropathy (IgAN). Twenty-four IgAN patients were divided into 4 groups based on their grade of proteinuria. Light microscopic examination revealed that GEC injury appeared prior to glomerular lesions such as sclerosis, crescent and adhesion. Reduced glomerular expression of C3b receptor (CR1), an indicator of GEC injury, was detected initially at the portion of damaged GEC and around the lesions of sclerosis, crescent and adhesion. CR1 expression eventually disappeared in the group IV patients who had nephrotic range proteinuria. Moreover, the grade of proteinuria in IgAN patients was associated with GEC injury and reduced glomerular expression of CR1. Taken together, GEC injury might be an important pathological finding which appears initially in the glomeruli, suggesting that GEC injury is a predictor of proteinuria in IgAN patients.

Adolescent↗
PubMed1998

[A clinicopathological study of recurrent IgA nephropathy following renal transplantation].

The present study was conducted to examine the clinicopathological features of recurrent IgA nephropathy (IgAN) following renal transplantation. Serial renal biopsies were performed regularly at 0-hour, 1-hour and 2-hours, and 39 episode biopsies were carried out when patients had increased serum creatinine levels and proteinuria. In 49 renal allograft recipients with IgAN, 12 patients were proved to be recurrent IgAN (24.5%). There was a significantly increased five- and ten-year risk of graft loss in the renal allograft recipients with biopsy-proved recurrent IgAN. Graft survival in 49 renal allograft recipients with IgAN was worse (68.8% at 5 years and 40.4% at 10 years) than that in 997 whole transplants (80.7% at 5 years, and 67.7% at 10 years). We found significant differences in the prevalence of HLA-DR4 (66.7%) and BW35 (25%) in the renal allograft recipients with recurrent IgAN when compared with normal healthy subjects. The renal allograft recipients with recurrent IgAN had a high incidence of proteinuria (8/12), hypertension (9/12) and renal dysfunction of less than 50 ml/min (7/12). Mean hemodialysis duration before renal transplantation in recurrent IgAN transplants was 12.5 months, which was shorter than in those without recurrent IgAN. Histopathological studies revealed that renal lesions due to IgAN frequently appeared in the renal allograft recipients with recurrent IgAN. Taken together, these findings suggest that donor-recipient matching may be carefully reconsidered, and recurrent IgAN after renal transplantation must be treated with effective immunosuppressive therapy.

Adult↗
PubMed1998

[Anesthetic management of total en bloc spondylectomy].

We analyzed the anesthetic management of 20 patients with total en bloc spondylectomy (TES) for solitary spinal metastases. Anesthesia was maintained with isoflurane, nitrous oxide in oxygen, and fentanyl in all patients. The duration of anesthesia was 733 minutes, and the amount of bleeding was 5371 ml on the average. During operation, hypovolemic shock occurred in 5 cases and huge hemothorax in 4 cases. Postoperative, huge hemothorax occurred in 6 cases and severe pneumonia in 3 cases. Maintenance of hemodynamic and respiratory function is important in perioperative management of TES.

Adult↗
PubMed1997

Fourier-transform infrared spectroscopic studies on the coordination of the side-chain COO- groups to Ca2+ in equine lysozyme.

Interactions between Ca2+ and the Asp side chains in the Ca2+-binding site of equine lysozyme were investigated by Fourier-transform infrared (FT-IR) spectroscopy. In the spectrum of equine lysozyme, the intensities of the bands at about 1595 cm-1 and 1578 cm-1 in the region of the COO antisymmetric stretches increased upon Ca2+ binding. In the region of the COO- symmetric stretches, the loss of intensity at about 1388 cm-1 and gains of intensities at about 1423 cm-1 and 1403 cm-1 were observed due to Ca2+ binding to equine lysozyme. The spectral changes for equine lysozyme indicate that the COO- groups of Asp85, Asp90 and Asp91 in the Ca2+-binding site coordinate to Ca2+ in the pseudo-bridging mode, where divalent metal cation is bound to one of the two oxygens in the COO- group and a water molecule is hydrogen bonded to the other oxygen. The results presented here provide further evidence for a high degree of similarity between Ca2+-binding lysozyme and alpha-lactalbumin. The effects of Ca2+ binding on the main-chain conformation of equine lysozyme were compared with those of bovine alpha-lactalbumin and hen egg-white lysozyme.

Animals↗
PubMed1997

FT-IR study of the Ca2+-binding to bovine alpha-lactalbumin. Relationships between the type of coordination and characteristics of the bands due to the Asp COO- groups in the Ca2+-binding site.

Fourier-transform infrared spectroscopy (FT-IR) was applied to examine relationships between the type of coordination and the COO- antisymmetric and symmetric stretches of the COO- groups in the Ca2+-binding site of bovine alpha-lactalbumin. The peaks at 1593, 1578, 1425, and 1403 cm(-1) were assigned to the COO- groups of Asp-82, 87, and 88 coordinating to Ca2+ in the pseudo bridging mode, according to the results of X-ray crystallography. The bands due to the COO- groups were quite similar to each other between alpha-lactalbumin and EDTA which is the model compound for the pseudo bridging state.

Animals↗
PubMed1997

The structure of Silurus asotus (catfish) roe lectin (SAL): identification of a noncovalent trimer by mass spectrometry and analytical ultracentrifugation.

We identified a noncovalent trimer of Sirurus asotus roe lectin (SAL) at Mr 95,362 along with its monomer at M(r) 31,750 by electrospray ionization mass spectrometry when SAL was dissolved in 0.5% acetic acid, sprayed into the ion source with methanol as a sheath liquid, and desolvated at 75 degrees C in a heated capillary column. The molecular weight of SAL, determined by the sedimentation equilibrium method, was 95,200 and the sedimentation coefficient (S20,w) of SAL in water was 5.58. SAL existed as a noncovalent trimer in solution and showed the ability to agglutinate rabbit erythrocytes. SAL showed three peaks (sal 1, sal 2, and sal 3) by C8 reverse-phase HPLC, and these appeared to be a monomer, a dimer, and a trimer, respectively, by matrix-assisted laser desorption ionization-time of flight mass spectrometry, sal 1 and sal 2 were shown to have a structure interchangeable with that of sal 3 in water.

Amino Acids↗
PubMed1997

Ascorbic acid and amino acid values in the aqueous humor of a patient with Lowe's syndrome.

BACKGROUND: Aminoaciduria is found in Lowe's syndrome. No studies of concentrations of ascorbic acid and amino acids in the aqueous humor of the syndrome have been performed. We examined these concentrations in a patient with Lowe's syndrome. METHODS: Ascorbic acid and amino acid levels in the aqueous humor and plasma of a male infant were measured by means of high-performance liquid chromatography. The patient, who had congenital cataract, miotic pupils, opaque corneas, glaucoma, aminoaciduria, normal levels of ascorbic acid and amino acid in the plasma, and renal tubular acidosis, underwent trabeculotomy, lensectomy, and anterior vitrectomy in both eyes. RESULTS: Intraocular pressure in both eyes decreased to within the normal range, but both corneas remained opaque. The amino acid levels in the aqueous humor were similar to those in the plasma, but intracameral ascorbic acid levels were decreased. After topical instillation of ascorbic acid, the corneas became transparent. The proband's mother had good visual acuity but paracentral lens opacities in both eyes. His maternal grandmother had scattered cortical opacities in both lenses. CONCLUSION: In this infant with Lowe's syndrome, we found intracameral levels of amino acids similar to those in the plasma. Levels of ascorbic acid in the aqueous humor were decreased.

Adolescent↗
PubMed1997

Clinical assessment of the significance of platelet-derived growth factor in patients with immunoglobulin A nephropathy.

To examine the role of platelet-derived growth factor (PDGF) in the pathogenesis of IgA nephropathy (IgAN), we investigated the expression of PDGF and the PDGF receptor in glomeruli with immunohistochemistry, the plasma levels of PDGF with ELISA, and the expression of PDGF in peripheral blood monocytes (PBMCs) with reverse transcription polymerase chain reaction (RT-PCR). We also assessed the effect of corticosteroid therapy on the plasma levels of the PDGF B-chain. At the time of kidney biopsy, the expression of the PDGF B-chain and the PDGF beta receptor in the glomeruli was upregulated in patients with IgAN. In addition, the plasma concentration of the PDGF B-chain was significantly higher in patients with IgAN than in normal subjects. Moreover, mRNA expression of PDGF beta-chain in PBMCs was up-regulated in patients with IgAN when compared with other patients with glomerulonephritis. We divided the patients into two groups according to the grade of urinary protein excretion (U[p]) after corticosteroid therapy. In patients in group 1 in whom U(p) was decreased by more than 50% or 1 gm/day after corticosteroid therapy, the expression of the PDGF B-chain and the PDGF beta receptor in the glomeruli was up-regulated. Finally, corticosteroid therapy decreased the plasma levels of PDGF B-chain in patients in group 1. Up-regulation of the PDGF B-chain and beta receptor in the glomeruli, elevated plasma levels of PDGF B-chain, and increased expression of PDGF mRNA in PBMCs could be associated with the pathogenesis of IgAN. The plasma concentration of PDGF B-chain may be a useful marker for patients with IgAN who would be responsive to corticosteroid therapy.

Adolescent↗
PubMed1997

Anti-mitogenic effects of sarpogrelate in cultured rat mesangial cells.

We investigated the effects of the new 5-HT2A receptor antagonist, sarpogrelate, on DNA synthesis in renal mesangial cells stimulated with 5-HT in the presence and absence of platelet-derived growth factor (PDGF)-BB. Both 5-HT and PDGF-BB demonstrated a mitogenic effect on these cells. When mesangial cells were incubated in the absence of PDGF-BB, sarpogrelate inhibited DNA synthesis in these cells in a dose-dependent manner. In the presence of PDGF-BB, sarpogrelate had a weaker anti-mitogenic effect in mesangial cells stimulated with 5-HT. Sarpogrelate was cytotoxic at concentrations over 10(-5) M according to the results of LDH release assays, and it reduced the S1 phase in mesangial cells stimulated with 5-HT by a flow cytometry. These findings suggest that sarpogrelate may be effective in the treatment of some glomerulonephritis associated with mesangial cell proliferation.

Animals↗