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Biomedical subjects

T Tagawa

Publications and source records attributed to T Tagawa.

At least 127 records · Page 7Linked to original sources
PubMed1993

Inhibition of nitric oxide formation in the nucleus tractus solitarius increases renal sympathetic nerve activity in rabbits.

It has been shown that nitric oxide (NO) is synthesized in the central nervous system as well as in vascular endothelial cells. However, the physiological role of NO in cardiovascular regulation by the central nervous system remains unclear. This objective of this study was to examine the possibility that NO plays a role in neural transmission in the nucleus tractus solitarius (NTS) and thus contributes to control of sympathetic nerve activity in rabbits. We examined the effects of NG-monomethyl-L-arginine (L-NMMA), an inhibitor of the formation of NO from L-arginine, microinjected into the NTS on arterial pressure (AP), heart rate (HR), and renal sympathetic nerve activity (RSNA). L-NMMA increased AP and RSNA in rabbits with intact as well as denervated sinoaortic baroreceptors and vagi. L-NMMA increased HR only in rabbits with sinoaortic denervation and vagotomy. Pretreatment with L-arginine microinjected into the NTS, which did not alter baseline AP, HR, and RSNA, prevented the increases in AP and RSNA evoked with subsequent L-NMMA. Pretreatment with D-arginine did not alter the effects of subsequent L-NMMA injections into the NTS. The gain of arterial baroreflex control of RSNA assessed by the slope of the regression line relating changes in AP and those in RSNA caused by intravenous phenylephrine or nitroglycerin did not differ before and after microinjections of L-NMMA. L-NMMA microinjected into the area postrema did not alter AP, HR, or RSNA. These results suggest that in rabbits NO is involved in the mechanism in the NTS that mediates tonic inhibition of RSNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Vasodilatory effect of arginine vasopressin is mediated by nitric oxide in human forearm vessels.

Arginine vasopressin (AVP) causes biphasic changes in vascular resistance in human forearms; vasoconstriction at lower doses and vasodilation at higher doses. Vasoconstriction is mediated by the V1 receptor. However, the mechanism of AVP-induced vasodilation is not known. We investigated whether AVP-induced vasodilation is mediated by nitric oxide (NO) in human forearms by examining the effects of L-arginine (a precursor of NO) and NG-monomethyl-L-arginine (L-NMMA, a blocker of NO synthase) on AVP-induced vasodilation. AVP was infused intraarterially at doses of 0.05, 0.1, 0.2, 0.5, and 1.0 ng/kg per min (n = 8). The lower doses of AVP (< or = 0.1 ng/kg per min) increased, whereas the higher doses of AVP (> or = 0.5 ng/kg per min) decreased forearm vascular resistance (FVR) (P < 0.01). Intraarterially infused L-arginine at 10 mg/min did not alter arterial pressure, baseline FVR, or heart rate. L-arginine did not alter the magnitude of AVP-induced vasoconstriction at the lower doses, but L-arginine augmented the magnitude of AVP-induced vasodilation at doses of 0.2 (P < 0.05), 0.5 (P < 0.01), and 1.0 (P < 0.05) ng/kg per min. In another group (n = 6), intraarterially infused L-NMMA (4 mumol/min for 5 min) increased baseline FVR without systemic effects, and inhibited acetylcholine-induced vasodilation (P < 0.01). L-NMMA at this dose inhibited AVP-induced vasodilation (P < 0.01) but did not affect vasoconstriction. L-arginine reversed the inhibitory effect of L-NMMA. Our results suggest that the vasodilatory effect of AVP may be mediated by NO in human forearms.

Adult↗
PubMed1993

[Comparison of typical and atypical bronchoplasty for bronchogenic carcinoma].

One-hundred and twenty-eight patients who underwent bronchoplasty for bronchogenic carcinoma from 1969 to 1990 were retrospectively analyzed. Ninety-six patients had upper sleeve lobectomy or upper lobectomy with wedge bronchoplasty (typical procedure) and 32 underwent bronchoplasty with lobectomy other than upper lobes (atypical bronchoplasty). The two groups were statistically similar in preoperative characteristics including sex, age, cell types and stages. In typical group, right upper sleeve lobectomy was performed in 48 patients, left upper sleeve lobectomy in 27, right upper lobectomy with wedge bronchoplasty in 11, left upper lobectomy with wedge bronchoplasty in 7 and sleeve bronchoplasty alone in 2. In atypical group, right middle and lower lobectomy with sleeve bronchoplasty in 10 patients, left lower sleeve lobectomy in 5, right lower lobectomy with wedge bronchoplasty in 4 and others in 13. Postoperative mortality was 5.2% in the typical group and 9.4% in the atypical group. Postoperative respiratory complications occurred in 16 patients (50%) in the patients with the atypical group and in 33 (34.7%) in those with typical group. Three years and 5 years survival rates in the typical group were 46 and 40% and those in the atypical group, 27 and 18%. However, there was no statistical difference in survival between the two groups. In conclusion, atypical bronchoplasty is useful for preserving the lung parenchyma, but, careful perioperative management and surgical technique of bronchoplasty are mandatory.

Adult↗
PubMed1992

Comparison of bone matrix-derived bone morphogenetic proteins from various animals.

Bone matrix-derived bone morphogenetic protein (BMP) was extracted from bovine, porcine, rabbit, Sprague-Dawley rat, and Wistar rat bone and purified. The purified fractions all had similar molecular weights and induced new bone in 3 weeks when implanted into muscle pouches of Wistar rats. Bone matrix-derived BMP is believed to consist of subunits and that of different animal origin to contain the same fraction with BMP activity.

Alkaline Phosphatase↗
PubMed1992

Primitive reflex profiles in infants: differences based on categories of neurological abnormality.

In order to clarify reflex profiles in the first year of life in connection with categories of neurological abnormality, six primitive reflexes, i.e., the crossed extensor reflex, suprapubic extensor reflex, heel reflex, Galant response, asymmetric tonic neck reflex and plantar grasp response, were examined in 458 normal infants, 78 infants with cerebral palsy (CP) and 81 infants with mental retardation (MR), whose diagnoses were confirmed at a later follow-up examination. The change in the mean score for each of these reflexes with age was characteristic for each category or type of neurological abnormality. This implies that a presumptive diagnosis can be made in neurologically high-risk infants by examination of the primitive reflexes. Such reflexes are therefore of specific significance, among other neurological criteria, in infants within the first year of life.

Ataxia↗
PubMed1992

Methylglyoxal bis(butylamidinohydrazone) exhibits antitumor effect on human malignant melanoma cells but reduces the antitumor action of cisplatin.

The antitumor effect of a polyamine biosynthetic pathway inhibitor methylglyloxal bis(butylamidinohydrazone) (MGBB) on human malignant melanoma (HMG) cells and its combination effect with cisplatin were investigated. The growth of cultured HMG cells was inhibited in a dose dependent manner by either MGBB or cisplatin; complete inhibition of cell proliferation was attained with 5 micrograms/ml of MGBB or 50 micrograms/ml of cisplatin. Pretreatment of HMG cells with MGBB diminished the antitumor action of cisplatin. The cultured HMG cells were inoculated in nude mice and aliquots of the resulting solid tumors (HMG tumor) were transplanted. The growth of transplanted HMG tumors in mice was inhibited markedly by cisplatin (3.8 mg/kg) and moderately by MGBB (10 or 20 mg/kg). The in vivo antitumor effect of cisplatin was also reduced by combined treatment with MGBB.

Animals↗
PubMed1992

Endothelium-dependent forearm vasodilation to acetylcholine but not to substance P is impaired in patients with heart failure.

It has been shown that endothelium-dependent vasorelaxation in response to muscarinic stimulation is attenuated in patients as well as animals with heart failure. This study aimed to determine if endothelium-dependent forearm vasodilation evoked with substance P (SP) as well as acetylcholine (ACh) was impaired in patients with heart failure. Forearm blood flow was measured using a strain-gauge plethysmograph and forearm vascular responses to intra-arterial infusions of ACh, SP, or sodium nitroprusside (SNP) at graded doses were examined. The drugs caused the dose-dependent increases in forearm blood flow (FBF) and the decreases in forearm vascular resistance (FVR) in patients with heart failure as well as normal subjects. However, the percent decreases in FVR by ACh were less in patients with heart failure than in normal subjects (p < 0.01). In contrast, the percent decreases in FVR by SP or SNP did not differ between the two groups. These results suggest that endothelium-dependent vasodilation of forearm resistance vessels via muscarinic receptors is specifically impaired, whereas via SP receptors, is preserved in patients with heart failure.

Acetylcholine↗
PubMed1992

Effects of L-arginine on forearm vessels and responses to acetylcholine.

This study was designed to investigate the effects of L-arginine (the substrate of endothelium-derived nitric oxide) in human forearm vessels. We examined whether intra-arterial infusion of L-arginine dilated forearm vessels and augmented vasodilatory responses to acetylcholine in young, healthy humans. The left brachial artery was cannulated for drug infusions and direct measurement of arterial pressure. Forearm blood flow was measured by a strain gauge plethysmograph. Intra-arterial infusions of L-arginine at 10, 20, 40, and 60 mg/min increased forearm blood flow from 4.7 +/- 0.6 to 4.9 +/- 0.5, 5.7 +/- 0.5, 7.2 +/- 0.8, and 8.2 +/- 0.9 ml.min-1.100 ml-1, respectively (n = 8, p less than 0.01), whereas D-arginine at the same doses did not alter forearm blood flow (n = 7). Intra-arterial infusions of acetylcholine (n = 7) (4, 8, 16, and 24 micrograms/min) and sodium nitroprusside (n = 5) (0.2, 0.4, 0.8, and 1.2 micrograms/min) increased forearm blood flow dose dependently (p less than 0.01 for both). Arterial pressure was not altered with infusions of these drugs. Responses to acetylcholine were augmented with simultaneous intra-arterial infusion of L-arginine at 10 mg/ml (p less than 0.01) but not with D-arginine. Responses to sodium nitroprusside were not altered by L-arginine. These results in human forearm resistance vessels support the notion that vasodilation induced by acetylcholine is a result of the conversion from L-arginine to endothelium-derived nitric oxide.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1992

[Perinatal neurosurgical care for one fetal hydrocephalus on twin gestation].

Twin gestations are responsible for a disproportionate amount of perinatal mortality and morbidity. Such gestations may impose greater demands on maternal and child physiologic systems than singleton pregnancies. The most common antenatal complications were preterm labor. The clinical record of myelomeningocele infant presenting with overt hydrocephalus in utero at 27 weeks of twin gestation and operated miniature Ommaya's reservoir placement early after birth and intentional delayed back closure for myelomeningocele was reported. Although perinatal neurosurgical care for one fetal hydrocephalus on twin gestation is clearly advantageous, it alone is relatively ineffective in reducing the incidence of the complication, preterm labor.

Diseases in Twins↗
PubMed1991

Induced microseizures in West syndrome.

Induced microseizures (IMS) were observed in a 5-month-old girl with symptomatic West syndrome. The seizures occurred following the suppression of infantile spasms with adrenocorticotropic hormone therapy and disappeared following the cessation of clonazepam administration. The ictal manifestations consisted of periods of irregular respiration, and respiratory arrest lasting for several seconds which often involved opening of the eyes and mild extension of the neck corresponding with the diffuse fast wave bursts in EEG activity observed during sleep. These seizures were thought to be equivalent to the IMS in Lennox-Gastaut syndrome, which have never been reported before in patients with West syndrome.

Adrenocorticotropic Hormone↗
PubMed1991

Human dentin-matrix-derived bone morphogenetic protein.

Bone morphogenetic protein (BMP) was extracted from human dentin matrix with 4 mol/L guanidine-HCl and was purified by liquid chromatography. SDS-PAGE and IEF showed that the purified BMP was homogeneous and induced new bone formation in situ after three weeks when implanted into muscle pouches in Wistar rats. The molecular weight of BMP was estimated to be about 20.0 kDa by SDS-PAGE, and the pI value was 8.8 by IEF. Amino acid analysis suggested that BMP is a protein containing 191 amino acids. A partial amino acid sequence was obtained from the final purified BMP. Dentin-matrix-derived BMP is probably not identical to, but is similar to, bone-matrix-derived BMP, though both types of BMP have the same action in vivo.

Alkaline Phosphatase↗
PubMed1991

The vascular architecture and innervation of the cerebral arteries in Leiothrix lutea.

The vascular architecture and innervation of the cerebral arteries in the robin-billed leiothrix, Leiothrix lutea, were studied using catecholamine fluorescence, acetylcholinesterase active staining, and immunohistochemical techniques. The cerebral arteries in Leiothrix lutea consisted of the cerebral carotid and the basilar systems. The cerebral carotid artery can be divided into the anterior and posterior rami. Due to poor development of the posterior ramus, the posterior cerebral artery originated from the anterior ramus, and an anterior communicating artery between the cerebroethmoidal arteries formed the circle of Willis. The cerebral carotid system was supplied with aminergic nerve fibers (Amn), cholinergic nerve fibers (Chn) and peptides [substance P (SP), neurokinin A (NKA), calcitonin gene related peptide (CGRP) and vasoactive intestinal polypeptide (VIP)]-like immunoreactive (LI) nerve fibers in all regions. These nerve fibers were abundant in the cerebral carotid system, but were few and scattered in the basilar system. Only neuropeptide Y (NPY)-LI nerve fibers were recognized in moderate numbers in the cerebral carotid system, but were not found in the basilar system. Innervation of the small blood vessels of the cerebral parenchyma differed from that of the cerebral superficial arteries, SP-, NKA-, CGRP- and VIP-LI nerve fibers showed a dense distribution, but Amn and NPY-LI nerve fibers showed a sparse distribution, and almost no Chn was observed. Double staining in the cerebral arteries for SP-, NKA- and CGRP-LI nerve fibers demonstrated exactly the same distribution. This suggests that SP, NKA and CGRP co-exist in the same fiber.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic Fibers↗
PubMed1991

[Catecholamine fluorescent, acetylcholinesterase positive and peptide immunoreactive nerve fibers in the rat hepatic portal system].

Innervation of rat hepatic portal system consisting of stem (portal vein) and peripheral portions (superior mesenteric vein, inferior mesenteric vein, splenogastric vein) was investigated by catecholamine fluorescence, acetylcholinesterase and immunohistochemical methods. Catecholamine fluorescent and Neuropeptide Y (NPY) immunoreactive (ir) nerve fibers were distributed throughout the hepatic portal system. Greater density was demonstrated in the peripheral portions. Catecholamine fluorescent and NPY ir nerve fibers formed ground plexus around the hepatic portal system. Acetylcholinesterase positive and vasoactive intestinal polypeptide-ir nerve fibers were sparsely distributed and no significant difference in density was noticed in the stem and the peripheral portions. Density of substance P ir, neurokinin A ir and calcitonin gene-related peptide ir nerve fibers was greater in the peripheral than the stem portion. All these fibers reticular showed pattern.

Acetylcholinesterase↗
PubMed1991

Analysis of bone morphogenetic protein (BMP) derived from human and bovine bone matrix.

Recently, Bone Morphogenetic Protein (BMP) has attracted the attention of a number of investigators, but its elucidation remains incomplete. At present, the determination of its amino acid sequence, which is necessary for its synthesis, and screening for a carrier that allows BMP to be effective in small amounts are unsolved problems. Bone morphogenetic protein is studied here to clarify its clinical applications. BMP was extracted from human and bovine bone matrix with 4 M guanidine-HCl and purified by liquid chromatography. Acrylamide electrophoresis (SDS-PAGE) and isoelectric focusing (IEF) showed that the purified BMP was homogeneous. We used type I collagen as the carrier in the bioassay. This BMP induced new bone in situ three weeks after implantation in muscle pouches in Wistar rats. The molecular weights of human and bovine bone matrix-derived BMP are 17.0 and 18.0 kDa by SDS-PAGE, and pI values for both are 4.9 by IEF. Human and bovine bone matrix-derived BMP are peptides containing 165 and 163 amino acids, respectively, according to amino acid analysis. The NH2-terminal sequence of bovine bone matrix-derived BMP was obtained from the bovine band, electroblotted onto polyvinylidene difluoride membrane, that corresponded to the final purified fraction. The sequence differs from previously designated BMPs25 and other proteins reported to have similar activity, but the physicochemical characteristics are comparable to the native preparations.

Amino Acid Sequence↗