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Biomedical subjects

J Takeda

Publications and source records attributed to J Takeda.

At least 379 records · Page 21Linked to original sources
PubMed1988

Evidence in volume-dependent hypertension for an augmenting factor for norepinephrine overflow from sympathetic nerve endings.

It has been reported that salt loading induces a blood pressure rise in rats whose renal mass has been reduced. We examined the involvement of the peripheral sympathetic nervous system in the pathogenesis of hypertension in subtotally nephrectomized and salt-loaded rats. Male Wistar rats (200-240 g) underwent subtotal nephrectomy (removal of 70-80% of the renal mass). After surgery, 1% saline was given ad libitum as drinking water in the experimental group (E), while tap water was given to the controls (C). On the 10th day after nephrectomy, blood pressure was determined, and plasma samples were collected. Deproteinized plasma samples were diluted with Ringer-Locke solution (1/40 v/v), and were perfused into isolated mesenteric artery-intestinal loop preparations of normotensive male Wistar rats. Pressor responses and norepinephrine overflow induced by electrical nerve stimulation, and the pressor responses to exogenous norepinephrine were assessed before and after the addition of deproteinized plasma to the perfusate. Systolic blood pressure was significantly elevated in the experimental group (E: 150 +/- 5 mmHg, C: 109 +/- 4 mmHg, p less than 0.01). When deproteinized plasma from the experimental group was perfused, pressor responses to electrical nerve stimulation were significantly increased (E: 167.2 +/- 13.7%, C: 91.1 +/- 6.4%; p less than 0.01), as was norepinephrine overflow (E: 117.3 +/- 6.4%, C: 90.7 +/- 5.9%; p less than 0.05), while responses to exogenous norepinephrine were only slightly augmented compared with the control group (E: 120.0 +/- 2.7%, C: 105.5 +/- 9.0%; n.s.).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Membrane fluidity of erythrocytes and its relevance to renin profile in essential hypertension.

This study was performed to investigate the membrane fluidity of hypertension by means of an electron spin resonance (E.S.R.) and a spin-labeling technique. Erythrocytes from patients with untreated essential hypertension (WHO I, II) and secondary hypertension were compared with those from normotensive subjects, and E.S.R. spectra for a fatty acid spin label agent (5-nitroxy stearate) incorporated into the erythrocyte membranes were obtained. The values of outer hyperfine splitting (2T'parallel) and order parameter (S) were significantly higher in erythrocytes from patients with essential hypertension than in those from normotensive subjects. However, these values were not significantly changed in patients with secondary hypertension compared with those in the normotensive subjects. This finding may indicate the reduced erythrocyte membrane fluidity in essential hypertension. Calcium-loading to erythrocytes with calcium-ionophore caused a greater decrease in the membrane fluidity of erythrocytes in patients with essential hypertension than in those from the normotensive subjects. This Ca-induced change in membrane fluidity was inversely correlated with plasma renin activity in essential hypertension. In addition, changes in membrane fluidity by Ca-loading in essential hypertension were inhibited by Ca-antagonists (diltiazem, verapamil). These results demonstrate that the membrane fluidity of erythrocytes might be decreased in essential hypertension, and that this abnormality could be accelerated by calcium, especially in low renin essential hypertension. Furthermore, it is suggested that Ca-antagonists might correct this Ca-abnormality at cellular levels of hypertension.

Adult↗
PubMed1988

Regulation of glucose-transporter gene expression by insulin in cultured human fibroblasts.

To clarify the effect of insulin on glucose-transporter (GT) biosynthesis, we determined GT mRNA levels in human cultured skin fibroblasts, using HepG2 GT cDNA as a probe. Insulin specifically increased the GT mRNA level in a time- and dose-dependent manner. Time-course study demonstrated that the mRNA level peaked within 3 h of insulin (1 x 10(-7) M) addition. After remaining elevated for several hours, mRNA decreased and returned to the basal level after 24 h. In the cell strains from seven normal subjects, the mean (+/- SE) GT mRNA level determined after 3 h of treatment with 1 x 10(-7) M insulin was 164.3 +/- 8.5% of the level found in untreated control cells. The insulin dose-response curve of GT mRNA levels showed that the maximum stimulation was elicited at 1 x 10(-7) M, and the half-maximum stimulation occurred at approximately 5 x 10(-10) M. Degradation rates of GT mRNA determined in the presence of actinomycin D were not different between insulin-treated and untreated cells. These results suggest that insulin increases GT gene expression in cultured human fibroblasts.

Cells, Cultured↗
PubMed1987

Sequence of an intestinal cDNA encoding human motilin precursor.

A cDNA clone encoding the human motilin precursor was isolated from an intestinal library using synthetic oligonucleotide probes. The predicted amino acid sequence indicates that the motilin precursor consists of 115 amino acids and includes a 25-residue N-terminal signal peptide followed by the 22-amino-acid motilin sequence and a long, 68-residue C-terminal peptide. The amino acid sequence of human motilin predicted from the cDNA sequence is identical to its porcine counterpart, which has been determined by protein sequencing. Proteolytic processing of promotilin to motilin occurs at the sequence, Lys-Lys, this being the first reported instance of processing occurring at a pair of Lys residues. In other precursors it occurs at Lys-Arg, Arg-Arg, Arg, or very rarely Lys.

Amino Acid Sequence↗
PubMed1987

Rapid and simple measurement of human C5a-des-Arg level in plasma or serum using monoclonal antibodies.

A new sandwich immunoassay method for measuring human C5a-des-Arg was developed using monoclonal antibody specifically reactive with C5a-des-Arg. Monoclonal antibodies were obtained from a panel of hybridomas produced by fusion of mouse myeloma cells, P3 X 63-AG8,653, with spleen cells from a CBF1(C57BL/6 X BALB/c) mouse immunized with purified C5a. The reactivities of these monoclonal antibodies against C5a, C5a-des-Arg and C5 were tested by solid-phase radioimmunoassay. One of the antibodies reacted with C5a-des-Arg, but not with C5a and C5. By use of this antibody for capturing antibody in sandwich immunoassay, a rapid and simple method was developed for measuring C5a-des-Arg without previous removal of C5. The sensitivity of this assay system was approximately 1 ng/ml for C5a-des-Arg.

Animals↗
PubMed1987

Covalent association of C3b with C4b within C5 convertase of the classical complement pathway.

The C5 convertase of the classical complement pathway is a complex enzyme consisting of three complement fragments, C4b, C2a, and C3b. Previous studies have elucidated functional roles of each subunit (4, 6, 7), but little is known about how the subunits associate with each other. In this investigation, we studied the nature of the classical C5 convertase that was assembled on sheep erythrocytes. We found that one of the nascent C3b molecules that had been generated by the C3 convertase directly bound covalently to C4b. C3b bound to the alpha' chain of C4b through an ester bond, which could be cleaved by treatment with hydroxylamine. The ester bond was rather unstable, with a half-life of 7.9 h at pH 7.4 and 37 degrees C. Formation of the C4b-C3b dimer is quite efficient; e.g., 54% of the cell-bound C3b was associated with C4b when 25,000 molecules of C4b and 12,000 molecules of C3b were present per cell. Kinetic analysis also showed the efficient formation of the C4b-C3b dimer; the rate of dimer formation was similar to or even faster than that of cell-bound monomeric C3b molecules. These results indicate that C4b is a highly reactive acceptor molecule for nascent C3b. High-affinity C5-binding sites with an association constant of 2.1 X 10(8) L/M were demonstrated on C4b-C3b dimer-bearing sheep erythrocytes, EAC43 cells. The number of high-affinity C5-binding sites coincided with the number of C4b-C3b dimers, but not with the total number of cell-bound C3b molecules. Anti-C4 antibodies caused 80% inhibition of the binding of C5 to EAC43 cells. These results suggest that only C4b-associated C3b serves as a high-affinity C5 binding site. EAC14 cells had a small amount of high-affinity C5 binding sites with an association constant of 8.1 X 10(7) L/M, 100 molecules of bound C4b being necessary for 1 binding site. In accordance with the hypothesis that C4b-associated C4b might also serve as a high-affinity C5-binding site, a small amount of C4b-C4b dimer was detected on EAC14 cells by SDS-PAGE analysis. Taken together, these observations indicate that the high-affinity binding of C5 is probably divalent, in that C5 recognizes both protomers in the dimers. The high-affinity binding may allow selective binding of C5 to the convertase in spite of surrounding monomeric C3b molecules.

Animals↗
PubMed1987

Effect of the alpha 2-blocker DG-5128 on insulin and somatostatin release from the isolated perfused rat pancreas.

2[2-(4.5-Dihydro-1H-imidazol-2-yl)-1-phenylethyl] pyridine dihydrochloride sesquihydrate (DG-5128) is an alpha 2-specific-adrenergic antagonist. We have studied the effect of DG-5128 on insulin and somatostatin release from the isolated perfused rat pancrease. DG-5128 stimulated somatostatin and insulin release not only at a low glucose concentration but also at a high glucose concentration. These findings suggest that an alpha 2-adrenergic receptor plays an important role in the regulation of insulin and somatostatin secretion.

Animals↗
PubMed1987

Safe jugular and subclavian venipuncture under ultrasonographic guidance.

Although jugular and subclavian venipuncture is a valuable technique and frequently utilized, blind venipuncture is at times associated with complications such as arterial puncture, pneumothorax, and malpositioning of catheters. We performed venipuncture under the guidance of high-resolution real-time ultrasonography, and these catheter-related complications were prevented. Jugular, subclavian and innominate veins and arteries, the pleura, and the lung are all delineated by supraclavicular and subclavicular scanning, and the needle and catheter can also be visualized. Ultrasonographically-assisted jugular and subclavian venipuncture is a simple and helpful procedure to carry out safe venipuncture. This method is particularly recommended for less experienced physicians and for more accurate puncture in patients with distorted cervical or subclavicular anatomic characteristics.

Humans↗
PubMed1987

Sequence of an intestinal cDNA encoding human gastric inhibitory polypeptide precursor.

Gastric inhibitory polypeptide (GIP) is a 42-amino acid hormone that stimulates insulin secretion in the presence of glucose. Complementary DNA clones encoding human GIP were isolated from a library prepared with RNA from duodenum. The predicted amino acid sequence indicates that GIP is derived by proteolytic processing of a 153-residue precursor, preproGIP. The GIP moiety is flanked by polypeptide segments of 51 and 60 amino acids at its NH2 and COOH termini, respectively. The former includes a signal peptide of about 21 residues and an NH2-terminal propeptide of 30 amino acids. GIP is released from the precursor by processing at single arginine residues. There is a region of nine amino acids in the COOH-terminal propeptide of the GIP precursor that has partial homology with a portion of chromogranin A as well as pancreastatin.

Amino Acid Sequence↗
PubMed1987

Collateral ventilation of obstructed lung during high-frequency oscillation in dogs and pigs.

To determine if collateral ventilation (CV) occurs in pigs and dogs during intermittent positive-pressure ventilation (IPPV) and high-frequency oscillation (HFO), seven pigs and seven dogs were studied by measuring Xenon 133 washout (XeW) from an occluded subsegmental bronchus. The rate constant/min (K) for Xe blood uptake (KXeb) was derived, and when subtracted from K for XeW (KXeW) gave K for removal of Xe by CV (KXecv). Pig XeW were single exponentials with mean KXew = 0.25/min during IPPV and 0.12/min with HFO. In pigs, mean K of XeW was no different from KXeb so that all XeW occurred by blood uptake and none by CV. XeW in dogs had two exponentials. Dogs had over 11 times greater mean KXeW than pigs during IPPV and over 24 times greater during HFO. In dogs, on average, 79% (IPPV) and 87% (HFO) of XeW occurred by CV. CV is a means of gas exchange during HFO and IPPV in dogs but not in pigs.

Animals↗