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Biomedical subjects

Y Doi

Publications and source records attributed to Y Doi.

At least 253 records · Page 14Linked to original sources
PubMed1996

Immunocytochemistry of perinatal rat livers with a special reference to the roles of mesenchymal cells in hepatic differentiation.

To investigate the roles of extracellular matrix produced by hepatic mesenchymal cells in the organization of hepatic cell cords, perinatal rat livers were examined with immunocytochemistry of fibronectin (FN) and laminin (LM). Some hepatocytes in a free state at prenatal day 15 actively produced FN and LM in the rough endoplasmic reticulum but lost this synthetic activity when such cells were incorporated into hepatic cell cords. On the other hand, hepatic mesenchymal cells, especially those associated with the perisinusoidal space, retained this synthetic activity throughout the stages examined. In the differentiating hepatic cell cords, positive immunoreactions for FN and LM were preferentially seen on the cell surface facing both sinusoidal space and differentiating bile canaliculus concomitant with the expression of the tight junction protein, ZO-1, from prenatal day 17. Since such hepatocytes have lost or reduced their synthetic activities of both glycoproteins in the rER, the immunoreactions appear to be mainly due to hepatic mesenchymal cells which seem to play a role in the formation of the hepatic cell cords and the bile canaliculi.

Animals↗
PubMed1996

[Trial of home infusion therapy for near-terminal stage patients with lung cancer].

To improve the quality of life in patients with malignant diseases at the near-terminal stage, we established a system for home infusion therapy (HIT) in Osaka Prefectural Habikino Hospital in 1994. Thirty-three patients were taken care of at home using the HIT system from January, 1995 to May, 1996. Their average age was 70 years old. The duration of HIT varied from 1 to 105 days (mean:25.5 days). Twenty-four cases received parenteral nutrition. The others received agents for brain edema (4 cases), morphine hydrochloride (2 cases), and anti-fungal agents (3 case). Additionally, 63% of these patients required home oxygen therapy (HOT) with HIT. Questionnaires to their families revealed that they were afraid of the progress of the disease in patients and their physical burden became heavier after the start of HIT. However, they were quite satisfied with the results of HIT.

Adolescent↗
PubMed1996

[Infective endocarditis associated with vertebral osteomyelitis: report of two cases].

A 42-year-old man and a 65-year-old woman with infective endocarditis suffered onset of severe back pain. Magnetic resonance imaging and technetium-99 m bone scanning demonstrated osteomyelitis in the lumbar spine which is an unusual complication of infective endocarditis. The man was treated by antibiotics and finally aortic valve replacement and laminectomy with bone grafting. The woman had small patent ductus arteriosus and developed aortic regurgitation, but was treated by antibiotics and corset application with good result. The possibility of osteomyelitis in the lumbar spine should be considered in a patient with endocarditis complaining of severe back pain. The appropriate antibiotic therapy over a prolonged period is recommended.

Adult↗
PubMed1995

A SP1 binding site in the GC-rich region is essential for a core promoter activity of the human endothelial nitric oxide synthase gene.

Endothelial nitric oxide synthase (eNOS) is an important oxygenase which catalyzes the conversion of L-arginine to L-citrulline to form nitric oxide (NO), a potent important factor for vasodilation and inhibition of platelet aggregation. We have analyzed characteristics of the promoter region of the human eNOS gene using the transient expression in human endothelial cells of CAT constructs with a series of 5'-deletion mutants. The 5'-flanking region between -116 and -98, which contains a putative consensus sequence for binding of transcription factor Sp1, is essential to direct a basal promoter activity. Gel mobility shift analysis involving anti-Sp1 antibody and competitor DNAs disrupted at the binding site for Sp1 reveals that Sp1 or its closely related protein(s) binds to the consensus sequence located between -104 and -96. These results indicate that the Sp1 site is essential for a core promoter activity of the human eNOS gene.

Base Composition↗
PubMed1995

Studies on neurovirulence in poliovirus-sensitive transgenic mice and cynomolgus monkeys for the different temperature-sensitive viruses derived from the Sabin type 3 virus.

We have studied methods for testing the neurovirulence of live poliovaccine viruses by intraspinal inoculation into mice carrying the human poliovirus receptor gene (Tg mice). A comparison of the neurovirulence of Sabin type 3 vaccine virus and related viruses using the 50% paralysis dose determined after intraspinal inoculation into the Tg mice as an index revealed a close correlation between the results of the paralysis dose in Tg mice, the neurovirulence expressed by the histopathological lesions core in monkeys, and the temperature sensitivity of the viruses. The results of experiments in the Tg mice also showed a good correlation with the number of mutations at position 472 from U to C in the 5' noncoding region in the genomes of the viruses tested. These results strongly suggest that the neurovirulence test for oral poliomyelitis vaccine using the Tg mice is an excellent method and may be used in place of the test using monkeys.

Animals↗
PubMed1995

Noninvasive assessment of left ventricular relaxation using continuous-wave Doppler aortic regurgitant velocity curve. Its comparative value to the mitral regurgitation method.

BACKGROUND: The most established parameters of left ventricular (LV) relaxation are peak negative value of the first derivative of LV pressure (-dP/dtmax) and the time constant of isovolumic LV pressure fall. The instantaneous pressure gradient between the aorta and the LV during diastole can be calculated from the continuous-wave Doppler aortic regurgitant velocity spectrum. Because the fluctuation of aortic pressure during LV isovolumic relaxation is negligibly minor and because LV minimal pressure is negligibly low, LV pressure during the isovolumic relaxation period may be derived from the continuous-wave Doppler aortic regurgitant velocity spectrum. This study was designed to clarify whether analysis of continuous-wave Doppler aortic regurgitation recording provides accurate measures of LV relaxation over a wide range of LV function and to determine comparative values of aortic and mitral regurgitation methods in the assessment of LV relaxation. METHODS AND RESULTS: In eight mongrel dogs with acute ischemic LV dysfunction, the continuous-wave Doppler aortic regurgitant velocity spectrum was recorded simultaneously with high-fidelity LV and aortic pressures, while the continuous-wave Doppler mitral regurgitant velocity spectrum was recorded simultaneously with high-fidelity left atrial and LV pressures. The aortic regurgitant velocity spectrum was provided for the determination of Doppler-derived mean rate of LV pressure fall in 20 ms after the onset of aortic regurgitation (delta P/delta t-AR) and the time interval from the onset of aortic regurgitation to the point at (1-1/e)1/2 of the maximal aortic regurgitant velocity as an estimate of the time constant. The mitral regurgitant velocity spectrum was provided for Doppler-derived mean rate of LV pressure fall in 20 ms after the point of -dP/dtmax (delta P/delta t-MR) and the time interval from the point of -dP/dtmax to the point with mitral regurgitant velocity of (1/e)1/2 of the mitral regurgitant velocity at the point of -dP/dtmax as an estimate of the time constant. delta P/delta t-AR and delta P/delta t-MR correlated well with catheter-derived -dP/dtmax (r = .92, r = .98, P < .01, respectively). The time constant derived from aortic and mitral regurgitant velocity spectra (tau-AR and tau-MR) also correlated well with catheter-derived time constant (r = .84, r = .76, P < .01, respectively). However, a mean difference of the catheter-derived time constant minus tau-MR was larger than tau-AR (29 +/- 30 versus 4 +/- 17 ms, P < .01, presented as mean +/- 2 SD). CONCLUSIONS: LV relaxation can be assessed from the continuous-wave Doppler aortic regurgitant velocity spectrum. The aortic regurgitation method provides an even more accurate estimate of the time constant compared with the mitral regurgitation method, particularly in the presence of LV dysfunction.

Animals↗
PubMed1995

Histamine release from Weibel-Palade bodies of toad aortas induced by endothelin-1 and sarafotoxin-S6b.

BACKGROUND: Endothelin-1 (ET-1) and sarafotoxin-S6b (STX) induce a remarkable degranulation of Weibel-Palade (WP) bodies prior to the vasocontraction of toad aortas. As WP bodies play the role of a reservoir site of the histamine in the endothelial cells, there is the possibility that ET-1 and STX evoke the release of histamine from WP bodies of this vessel. METHODS: Histamine concentrations were assayed by high-performance liquid chromatography (HPLC) from the perfusate after being perfused with a solution containing ET-1 and STX. Each vessel was fixed and embedded for conventional electron microscopy and immunoelectron microscopy using antihistamine sera. RESULTS: The appreciable concentrations of histamine were assayed by HPLC from the perfusate after the toad aortas were perfused with a solution containing ET-1 and STX. The immunoelectron microscopy revealed that histamine immunoreactive gold particles in the WP bodies remarkably decreased in number in the treated samples when compared to the control ones. Our immunoelectron micrographs indicated that the release of histamine from the endothelial cells occurred in association with the degranulation and the exocytosis of the WP bodies after treatment with ET-1 and STX. CONCLUSIONS: The present study clearly shows that ET-1 and STX induce the histamine release from WP bodies of the toad aortas by means of HPLC and immunoelectron microscopy. Histamine discharged from the WP bodies may be involved in the vasocontraction evoked by ET-1 and STX.

Animals↗
PubMed1995

Pyrolysis-gas chromatography of carbonate apatites used for sintering.

Gas chromatography was employed to quasi-continuously determine the amount of carbon dioxide that evolved from carbonate apatite specimens during sintering. Assuming that the carbonate in the specimens decomposed to carbon dioxide on a mole-for-mole basis, the determination of the carbon dioxide evolved allowed for the determination of the amount of carbonate that remained in the specimens during different stages of sintering. Previously, this measurement could be carried out only after sintering was completed. Comparison of data obtained from specimens compacted isostatically at 600 MPa for sintering with powder specimens indicated that the amount of carbonate remaining in the sintered apatite mass strongly depended on heating rates, heating temperatures, and holding-time intervals.

Apatites↗
PubMed1995

Erythrocyte sodium-potassium transport in hyperkalaemic and normokalaemic infants.

UNLABELLED: One of the causes of early onset hyperkalaemia in very low birth weight infants is presumed to be the dysfunction of K+ transport across the cell membrane. Sodium-potassium adenosine triphosphatase(Na(+)-K+ ATPase) is known to play a major role in K+ transport. We compared the concentrations of erythrocyte Na(+)-K+ ATPase (Vmax levels) for hyperkalaemic and normokalaemic infants of matched gestational age. In hyperkalaemic infants, the highest levels of Vmax were reached at 24-48 h after birth, but in normokalaemic infants, there were no significant changes in Vmax levels during the 1st week after birth. At 12-72 h after birth, erythrocyte K+ concentrations for hyperkalaemic infants were higher than those of normokalaemic infants. For both groups of infants, the highest levels of plasma K+ during the 1st week after birth showed a positive correlation with those of Vmax. CONCLUSION: Na(+)-K+ ATPase on the cell membrane is activated to compensate for hyperkalaemia; however, when this compensation is incomplete, hyperkalaemia occurs.

Erythrocyte Membrane↗
PubMed1995

Effect of adrenomedullin on aldosterone secretion by dispersed rat adrenal zona glomerulosa cells.

Adrenomedullin, a novel hypotensive peptide, was discovered in human pheochromocytoma. Although adrenomedullin exists also in normal adrenal medulla and several other organs, its effect on steroidogenesis in adrenal cortex has not been studied. We examined the effect of adrenomedullin on aldosterone secretion by the dispersed rat adrenal zona glomerulosa cells. Adrenomedullin (10(-12)-10(-7) M) did not affect basal aldosterone secretion. Adrenomedullin dose dependently inhibited aldosterone secretion stimulated by 10(-9) M angiotensin II and 10 mM potassium, whereas 10(-9) M ACTH-stimulated aldosterone was not significantly inhibited by adrenomedullin. N6,O2'-dibutyryladenosine 3':5'-cyclic monophosphate (db-cAMP, 10(-5)-10(-3) M) and Ca+ ionophore A23187 (10(-8)-10(-6) M) stimulated aldosterone secretion dose dependently, and A23187-stimulated secretion was significantly inhibited by adrenomedullin (10(-8) M), but db-cAMP-stimulated secretion was not inhibited by adrenomedullin. Our data suggest the possibility that adrenomedullin is a novel inhibitory peptide of aldosterone secretion induced by increasing concentration of intracellular free calcium.

Adrenocorticotropic Hormone↗
PubMed1995

Validation of transthoracic myocardial ultrasonic tissue characterization: comparison of transthoracic and open-chest measurements of integrated backscatter.

To investigate whether myocardial integrated backscatter (IB) can be measured through the chest wall, myocardial IB parameters were measured in five adult mongrel dogs with a newly developed IB imaging system capable of measurements of myocardial IB relative to backscatter from the blood. There was no significant difference in the calibrated myocardial IB between the closed chest and the open chest conditions either in the septum or in the posterior wall if a 2.5- or 3.5-MHz frequency transducer was used. There was no significant difference in the magnitude of cyclic variation in IB between the closed chest and the open chest conditions independent of the frequency of the transducer used. These data suggest that we can accurately measure not only the magnitude of cyclic variation in IB but also the calibrated myocardial IB through the chest wall with a 2.5- or 3.5-MHz frequency transducer. Such data may validate measurements of myocardial IB parameters through the chest wall even in humans.

Algorithms↗
PubMed1995

Antidiuretic hormone decreases the intracellular pH in distal nephron epithelium (A6) by inhibiting Na+/H+ exchange.

1. To clarify the effect of arginine vasotocin (AVT) on intracellular pH (pHi) of A6 cells (an amphibian renal cell line), we measured pHi with a single-cell fluorescent imaging system in an HCO3(-)-nominally-free medium. 2. AVT (40 mU/ml) significantly decreased pHi from 7.44 +/- 0.11 to 7.19 +/- 0.22 (mean +/- SE) by inhibiting the Na+/H+ exchanger. 3. A membrane-permeable analogue of cAMP, dibutyryl cAMP (1 mM), significantly decreased pHi from 7.40 +/- 0.02 to 7.17 +/- 0.02, a response similar to that of AVT. 4. These data indicate that, in A6 cells, AVT suppresses the Na+/H+ exchanger via a cAMP-dependent pathway and the Na+/H+ exchanger maintains pHi under HCO3(-)-nominally-free conditions.

Amiloride↗
PubMed1995

Bumetanide and bicarbonate increase short-circuit current in fetal lung epithelium.

1. We studied the effects of bumetanide (a Na+/K+/2Cl- cotransport inhibitor) and HCO3(-) on beta-adrenergic-agonist-stimulated short-circuit current (beta-Isc) in rat fetal distal lung epithelium (FDLE). 2. Bumetanide significantly increased beta-Isc in the absence of amiloride but decreased it in its presence. The amiloride- and bumetanide-insensitive beta-Isc was diminished by a removal of HCO3(-) in the bathing solution. 3. Our results suggest that bumetanide stimulates the amiloride-sensitive beta-Isc in FDLE and that the amiloride-insensitive beta-Isc is composed of two different pathways: bumetanide-sensitive and HCO3(-)-dependent Cl- secretion in FDLE.

Adrenergic beta-Agonists↗
PubMed1995

Characterization of vitelline membrane outer layer protein I, VMO-I: amino acid sequence and structural stability.

Vitelline membrane outer layer protein I (VMO-I) tightly bound to ovomucin fibrils of hen's egg yolk membrane was characterized in terms of its amino acid sequence and structural stability. The deduced sequence of VMO-I using the conventional sequencing method is: RTREYTSVITVPNGGHWGKWGIRQFCHSGYANGFALKVEPSQFGRDDTALNGIRLRCLD- GSVIESLVGKWGTWTSFLVCPTGYLVSFSLRSEKSQGGGDDTAANNIQFRCSDEAVLVGD- DLSWGRFGPWSKRCKICGLQTKVESPQGLRDDTALNNVRFFCCK. Thus, VMO-I is composed of 163 amino acid residues with a calculated molecular weight of 17,979. The sequence confirms the cDNA sequence of VMO-I we recently determined and does not show any significant similarity to proteins compiled in the NBRF database. Two of the four disulfide bonds found in VMO-I were estimated to lie between Cys26 and Cys57 and between Cys79 and Cys110. The sequence analyses show that VMO-I contains three 53-residue internal repeats that contain distinctive regions of turns flanked by beta-sheets consistent with the recent finding that the molecule contains a new beta-fold motif, the beta-prism. The molecular characteristics of VMO-I in solution were examined by CD spectroscopy in the far and near ultraviolet regions, NMR spectroscopy, and high sensitive differential scanning calorimetry (DSC). CD spectra in the far UV region at room temperature were similar to that assigned to a random coil, while in the near UV region, small positive peaks were observed. The ellipticity in both regions decreased on raising the temperature. Proton NMR experiments showed the native structure unfolds to unordered conformations at 70 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗