Faculty Profiles - TSUKAHARA Hirokazu

MISC - TSUKAHARA Hirokazu

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Spontaneous Resolution of Lumbar Bone Mineral Depletion in Prematurely Born Children

TSUKAHARA Hirokazu, HORI Chikahide, FUJII Yasushi, TSUCHIDA Shinya, YAMAMOTO Kazutaka, ISII Yasushi, SUDO Masakatsu

5 ( 2 ) 171 - 177 1995.12

Dual Energy X-ray Absorptiometry in Growing Rats: Comparison with Biochemical Markers

TSUKAHARA Hirokazu, MIURA Masakazu, HATA Keishi, HORI Chikahide, TSUCHIDA Shinya, YAMAMOTO Kazutaka, ISHII Yasushi, SUDO Masakatsu

5 ( 2 ) 129 - 134 1995.12

FAVORABLE PROGNOSIS IN STEROID-RESPONSIVE NEPHROTIC CHILDREN IDENTIFIED BY CHANCE PROTEINURIA

M HIRAOKA, N TAKEDA, K KIMURA, K TAKAGI, S HAYASHI, E KATO, K OHTA, C HORI, S TSUCHIDA, H TSUKAHARA, M SUDO

JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY 5 ( 3 ) 352 - 352 1994.9

MOLECULAR AND FUNCTIONAL-CHARACTERIZATION OF THE NON-ISOPEPTIDE-SELECTIVE ET(B) RECEPTOR IN ENDOTHELIAL-CELLS

H TSUKAHARA, H ENDE, HI MAGAZINE, WF BAHOU, MS GOLIGORSKY

JOURNAL OF BIOLOGICAL CHEMISTRY 269 ( 34 ) 21778 - 21785 1994.8

Language：English Publisher：AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

There is accumulating evidence that endothelial cells express a non-isopeptide-selective endothelin (ET) receptor, ET(B), which may be responsible for ET-1-induced transient vasorelaxation. The purpose of the present study was to seek direct evidence for ET(B) receptor expression in human umbilical vein endothelial cells (HUVEC) and to characterize its functional role in HUVEC and in Chinese hamster ovary cells stably transfected with ET(B) receptor cDNA (CHO-ET(B)). Reverse polymerase chain reaction using HUVEC total RNA and ET(B) receptor-specific oligonucleotide primers firmly demonstrated the presence of an endogenous transcript of the appropriate molecular size. Next, a biotinylated ligand specifically recognizing the ET(B) receptor, IRL-1620, was synthesized, and immunocytochemical mapping of binding sites was performed in CHO-ET(B) cells. Specific binding of biotinylated IRL-1620 was evident in CHO-ET(B) cells, confirming appropriate cell surface receptor expression. continuous nitric oxide (NO) monitoring with NO-selective electrode revealed a dose-dependent ET-1 stimulation of NO production by HUVEC. Stable transfection of CHO-ET(B) cells with endothelial nitric oxide synthase (NOS), but not mock-transfection, imparted responsiveness to ET-1 similar to that for HUVEC and was characterized by the immediate release of NO. Protein tyrosine kinase-dependent and calcium-calmodulin-dependent pathways were involved in ET-1-induced activation fo the constitutive NOS in CHO-ET(B)/NOS cells, but coupling of the receptor to the enzyme in HUVEC appeared to be predominantly protein tyrosine kinase-dependent. Although sufficient calcium/calmodulin system was not an obligatory prerequisite for the ET-1-induced activation of NOS in HUVEC. In conclusion, using two cell systems, we demonstrated that the ET(B) receptor is functionally coupled to NOS and coordinates the generation of NO via a tyrosine kinase-dependent and a calcium/calmodulin-dependent pathway.

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TETRODOTOXIN-BLOCKABLE DEPOLARIZATION-ACTIVATED NA+ CURRENTS IN A CULTURED ENDOTHELIAL-CELL LINE DERIVED FROM RAT INTERLOBAR ARTERY AND HUMAN UMBILICAL VEIN

DV GORDIENKO, H TSUKAHARA

PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY 428 ( 1 ) 91 - 93 1994.8

Language：English Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：SPRINGER VERLAG

Voltage-dependent Na+ current (I-Na) was identified in cultured endothelial cells derived from rat interlobar artery (RIAE cells) and human umbilical vein (HUVE cells). Tetrodotoxin (TTX) reduced I-Na in a dose-dependent manner with the apparent dissociation constant (K-d) of 1.4 mu M. Low sensitivity of I-Na to TTX as well as its kinetics and voltage-dependent properties indicates that voltage-gated Na channels expressed in vascular endothelial cells belong to the so-called TTX-resistant type [2].

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DECREASE IN AMBIENT [CL-] STIMULATES NITRIC-OXIDE RELEASE FROM CULTURED RAT MESANGIAL CELLS

H TSUKAHARA, Y KRIVENKO, LC MOORE, MS GOLIGORSKY

AMERICAN JOURNAL OF PHYSIOLOGY 267 ( 1 ) F190 - F195 1994.7

Language：English Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：AMER PHYSIOLOGICAL SOC

It has been hypothesized that fluctuations of the ionic composition in the interstitium of juxtaglomerular apparatus (JGA) modulate the function of extraglomerular mesangial cells (MC), thereby participating in tubuloglomerular feedback (TGF) signal transmission. We examined the effects of isosmotic reductions in ambient sodium concentration ([Na+]) and [Cl-] on cytosolic calcium concentration ([Ca2+](i)) in cultured rat MC. Rapid reduction of [Na+] or [Cl-] in the bath induced a concentration-dependent rise in [Ca2+](i). MC are much more sensitive to decreases in ambient [Cl-] than to [Na+]; a decrease in [Cl-] as small as 14 mM was sufficient to elicit a detectable [Ca2+](i) response. These observations suggest that MC can be readily stimulated by modest perturbations of extracellular [Cl-]. Next, we examined whether activation of MC by lowered ambient [Cl-] influences cellular nitric oxide (NO) production. Using an amperometric NO sensor, we found that a 13 mM decrease in ambient [Cl-] caused a rapid, Ca2+/calmodulin-dependent rise in NO release from MC. This response was not inhibitable by dexamethasone, indicating the involvement of the constitutive rather than the inducible type of NO synthase in MC. In addition, the NO release was blunted by indomethacin pretreatment, suggesting that a metabolite(s) of cyclooxygenase regulates the activation of NO synthase in MC. Our findings that small perturbations in external [Cl-] stimulate MC to release NO, a highly diffusible and rapidly acting vasodilator, provide a possible mechanism to explain the transmission of the signal for the TGF response within the JGA.

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SCAPHOID MEGALOURETHRA WITH MULTIPLE UROGENITAL ANOMALIES

A HATA, H TSUKAHARA, Y SHIGEMATSU, S NISHIBUCHI, K OKADA, M SUDO

PEDIATRIC NEPHROLOGY 8 ( 2 ) 218 - 220 1994.4

Language：English Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：SPRINGER VERLAG

A male infant with scaphoid megalourethra, which is a rare congenital anomaly, is presented. At birth he exhibited a grossly swollen, malformed penis and cryptorchidism. The corpus spongiosum was not palpable. The infant had congenital renal failure. Retrograde urethrography revealed a crescent-shaped dilatation of the anterior urethra, and the diagnosis of scaphoid megalourethra was made. Subsequent uroradiological examinations showed that there were also severe urogenital anomalies, i. e. renal hypoplasia-dysplasia, hydronephrosis, hydroureter and vesicoureteral reflux. This disorder is frequently associated with other urogenital anomalies. Therefore, once the diagnosis is reached, a careful investigation for other associated abnormalities should be undertaken.

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Ultrasound findings of ureteral reflux in early infancy

Masahiro Hiraoka, Chikahide Hori, Shinya Tsuchida, Hirokazu Tsukahara, Masakatsu Sudo

Pediatric Nephrology 8 ( 2 ) 264 - 265 1994.4

DIRECT DEMONSTRATION OF INSULIN-LIKE GROWTH FACTOR-I-INDUCED NITRIC-OXIDE PRODUCTION BY ENDOTHELIAL-CELLS

H TSUKAHARA, DV GORDIENKO, B TONSHOFF, MC GELATO, MS GOLIGORSKY

KIDNEY INTERNATIONAL 45 ( 2 ) 598 - 604 1994.2

Language：English Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：BLACKWELL SCIENCE INC

Several lines of evidence indicate that insulin-like growth factor-I (IGF-I) is a potent mediator of vasodilation. To elucidate the mechanism and site of action of IGF-I, we performed continuous monitoring of nitric oxide (NO) release from endothelial cells using a highly-sensitive amperometric NO-sensor. Two types of cultured cells were used: human umbilical vein endothelial cells and immortalized rat renal interlobar artery endothelial cells. In separate experiments, [Ca2+]i changes in response to IGF-I were measured spectrofluorometrically in fura-2-loaded cells. Stimulation with IGF-I resulted in a rapid, dose-dependent increase in [NO] as detected by the NO-probe positioned 1 mm above the monolayers, followed by a sustained elevation lasting for at least five minutes. The effect of IGF-I was significantly suppressed by pretreatment with anti-IGF-I antibody, suggesting that it was specific for IGF-I. N(G)-nitro-L-arginine methyl ester, an inhibitor of NO synthesis, significantly blunted responses to IGF-I, but dexamethasone preincubation did not reduce the IGF-I-induced release of NO. These results indicate that the observed IGF-I-induced release of NO is a result of activation of the constitutive, rather than the inducible type of NO synthase in endothelial cells. Genistein, a tyrosine kinase inhibitor, resulted in a profound suppression of the IGF-I-induced release of NO. IGF-I did not affect [Ca2+]i in either type of cells. Therefore, IGF-I-induced NO production by both types of endothelial cells is mediated via a tyrosine kinase-dependent mechanism. IGF-I may be an important regulator of vascular tone in vivo through NO release from the vascular endothelium, and may contribute to the regulation of renal blood flow under physiological and pathophysiological conditions.

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CONTINUOUS MONITORING OF NITRIC-OXIDE RELEASE FROM HUMAN UMBILICAL VEIN ENDOTHELIAL-CELLS

H TSUKAHARA, DV GORDIENKO, MS GOLIGORSKY

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 193 ( 2 ) 722 - 729 1993.6

CALCIUM-CHANNEL CURRENT IN CULTURED RAT MESANGIAL CELLS

M NISHIO, H TSUKAHARA, M HIRAOKA, M SUDO, S KIGOSHI, MURAMATSU, I

MOLECULAR PHARMACOLOGY 43 ( 1 ) 96 - 99 1993.1

Language：English Publisher：WILLIAMS & WILKINS

The presence of voltage-dependent calcium channels has been suggested in mesangial cells by using calcium-sensitive fluorescent probes. However, direct electrophysiological evidence for voltage-dependent calcium channels has not yet been presented. In this study voltage-dependent calcium channels were studied in cultured rat mesangial cells. Whole-cell patch-clamp experiments were done with 50 mM Ba2+ as a charge carrier. Step depolarizing pulses from a holding potential of -50 mV produced an inward barium current at potentials more positive than -10 mV, and a peak current (10-45 pA) was obtained at a membrane potential of approximately +30 mV. The inward current was augmented by 1 00 nm Bay K 8644, attenuated by 1 muM nifedipine, and abolished by 50 muM Cd2+. These results indicate that the inward current is a barium current flowing through L-type calcium channels. This may be the first study that demonstrates the presence of L-type calcium channels in mesangial cells.

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Dual Energy X-Ray Absorptiometry in Growth Hormone Deficiency

Akio Nakai, Yosuke Shigematsu, Hirokazu Tsukahara, Masakatsu Sudo

clinical pediatric endocrinology 2 ( 1 ) 111 - 113 1993

Language：English

Bone mineral density (BMD) of the lumbar spine was measured by dual energy X-ray absorptiometry (DXA) in nine Japanese children with growth hormone (GH) deficiency. Before hGH therapy, BMDs of the GH-deficient patients were lower than those of controls. When their bone ages were substituted for their chronological ages, however, almost all BMDs of the patients were distributed within the normal range. After 12 months of hGH therapy, the BMDs increased in 8 of 9 GH-deficient patients
they were still lower as compared to controls. the relation between BMDs and bone ages suggested delayed skeletal maturation in GH-deficient patients. dual energy X-ray absorptiometry (DXA), growth hormone deficiency, bone mineral density (BMD), lumbar vertebrae, Japanese children. © 1993, The Japanese Society for Pediatric Endocrinology. All rights reserved.

DOI： 10.1297/cpe.2.Supple2_111

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Autosomal dominant polycystic kidney disease in a child diagnosed by ultrasonography

Masahiro Hiraoka, Keiko Kimura, Shiny A Tsuchida, Hirokazu Tsukahara, Masakazu Saito, Masakatsu Sudo

Japanese Journal of Nephrology 35 ( 4 ) 383 - 386 1993

Language：English

A 10-year-old boy with a chief complaint of nocturnal enuresis was identified as having three cysts in each kidney on ultrasonographic examination. These findings together with a positive family history for renal failure prompted us to examine his father ultrasonographically on the same day, resulting in the identification of multiple large cysts in both kidneys. These observations supported a diagnosis of autosomal dominant polycystic kidney disease. Enhanced X-ray CT demonstrated more sensitively the presence of renal cysts in the boy. He had a normal urinary concentrating ability and no other abnormalities except for mild hypertension, which was successfully treated only by salt restriction. Ultrasonography thus appears to be a valuable tool for diagnosing polycystic kidney diseases. © 1993, Japanese Society of Nephrology. All rights reserved.

DOI： 10.14842/jpnjnephrol1959.35.383

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URINARY ERYTHROCYTE VOLUME ANALYSIS - A SIMPLE METHOD FOR LOCALIZING THE SITE OF HEMATURIA IN PEDIATRIC-PATIENTS

H TSUKAHARA, M YOSHIMOTO, K MORIKAWA, T OKADA, M KURODA, M SUDO

JOURNAL OF PEDIATRICS 115 ( 3 ) 433 - 436 1989.9

INSULIN RESISTANCE IN A BOY WITH CONGENITAL GENERALIZED LIPODYSTROPHY

H TSUKAHARA, K KIKUCHI, H KUZUYA, E ITO, Y ODA, A KOSAKI, T KAKEHI, H NISHIMURA, K YAMADA, Y YOSHIMASA, H IMURA, H MIKAWA

PEDIATRIC RESEARCH 24 ( 6 ) 668 - 672 1988.12

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