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K Takeda

Publications and source records attributed to K Takeda.

At least 1,099 records · Page 61Linked to original sources
PubMed1987

Amino acid analysis by reversed-phase high-performance liquid chromatography. Automatic pre-column derivatization with activated carbamate reagent.

Succinimido alpha-naphthylcarbamate, an activated carbamate reagent, facilitated the simple and rapid pre-column derivatization of amino acids for fluorimetric detection. The method is based on the formation of naphthylcarbamyl derivatives of amino acids. The carbamylation of amino acids is completed within 1 min at room temperature, and the reaction mixture can be injected directly into a liquid chromatograph equipped with an octadecylsilyl reversed-phase column. The effluent stream is monitored fluorimetrically at 370 nm excited at 290 nm at the sub-picomole level. Naphthylcarbamyl derivatives of common protein amino acids were separated within 30 min by gradient elution with aqueous sodium acetate and acetonitrile. Excess of the reagent does not interfere with the analysis of amino acids, because it is hydrolysed in 2-3 min to give naphthylamine, which is more strongly retained than any amino acid derivatives.

Amino Acids↗
PubMed1987

Optical resolution of enantiomeric amino acid derivatives on a naphthylethylurea multiple-bonded chiral stationary phase prepared via an activated carbamate intermediate.

A new chiral stationary phase (CSP) was developed for the direct optical resolution of enantiomeric amino acid derivatives. The CSP was readily prepared by a three-step reaction carried out in a pre-packed aminopropylsilyl silica gel column. In the first step, a solution of disuccinimido carbonate (DSC) was delivered through the pre-packed column to give a succinimido carbamyl aminopropylsilyl-bonded, activated-carbamate type silica gel (ACsil) column. Through the column was then delivered a solution of pentaethylenehexamine to afford a polyamine-bonded column. Finally, a solution of optically active succinimido (S)- or (R)-naphthylethyl carbamate was delivered through the polyamine column, to give a naphthylethylurea multiple-bonded CSP. p-Bromophenylcarbamyl derivatives of enantiomeric protein amino acids were resolved on these CSPs by elution with an aqueous mobile phase. Simultaneous analysis of these amino acid enantiomers by means of gradient elution was also accomplished.

Amino Acids↗
PubMed1987

Synergism of tumor necrosis factor and interferon-gamma in induction of differentiation of human myeloblastic leukemic ML-1 cells.

Natural or recombinant human tumor necrosis factor (TNF) induced NBT-reducing activity of ML-1 cells in a dose-dependent manner. Interferon-gamma (IFN-gamma) induced NBT-reducing activity only marginally. However, when IFN-gamma was combined with TNF, induction of NBT-reducing activity was remarkably increased. IFN-alpha or -beta had almost no effect on the induction of NBT-reducing activity of ML-1 cells, either alone or in combination with TNF. Treatment with both TNF and IFN-gamma synergistically enhanced morphological changes, growth inhibition and activity of Fc receptors, and NBT reduction in ML-1 cells, but not phagocytic activity. The TNF treated cells were classified as macrophage-like by morphology, and by lineage-specific alpha-naphthyl acetate esterase stain. The results indicate that combinations of TNF and IFN-gamma act synergistically in the induction of differentiation of human myeloblastic ML-1 cells.

Cell Differentiation↗
PubMed1987

[The source and significance of increased urinary dopamine excretion during sodium loading in rats].

To investigate the source and physiological significance of urinary free dopamine (f-DA) in high sodium diet (8% NaCl) loading, the effects of renal denervation and administration of carbidopa, an inhibitor of peripheral dopa decarboxylase, on urinary f-DA excretion were studied in male Wistar rats. Carbidopa was orally administered in a dose of 20mg/kg every 12h. To ascertain the extent of denervation, kidney norepinephrine was measured. Catecholamines were assayed by HPLC with electrochemical detection. Urinary f-DA and sodium excretion were significantly increased in response to the added NaCl. There were few effects of renal denervation on urinary excretion of f-DA and sodium in high sodium diet loading, whereas carbidopa caused a significant fall not only in urinary f-DA excretion but also in urinary sodium excretion. A highly significant correlation was also found between sodium excretion and f-DA excretion on the 5th day of carbidopa treatment. The data indicates that urinary f-DA in a high sodium diet is mainly derived from the renal tubular cells but not from renal nerves and that f-DA may be an important natriuretic hormone.

Administration, Oral↗
PubMed1987

Effects of angiotensin I converting enzyme (ACE) related substances upon the vascular prostacyclin generation.

We investigated the interaction of angiotensin I (AI) converting enzyme (ACE) related substances to prostacyclin (PGI2) generation and ACE activity using cultured human vascular endothelial cells (EC) and rat aortic rings (AR). In case of cultured EC, AI and bradykinin (BK) increased PGI2 generation and at the same time ACE released from EC, however angiotensin II (AII) did not show any effect on both of them. When the EC were pretreated by captopril both of basal PGI2 production and ACE activity were reduced but the enhancing effects on PGI2 generation by AI or BK were preserved. On the other hand in the experimental system with AR, not only AI or BK but also AII increased PGI2 generation and the higher concentration of captopril inhibited PGI2 generation. When the EC were removed, the enhancing effect by AII was diminished and the mechanical stimulation to AR remarkably increased PGI2. From these experimental studies, we obtained the results that (1) the reported hypothesis that the vasodilative effect of captopril would be developed by the enhanced PGI2 generation was not confirmed in our systems of EC and AR. (2) AII did not affect on PGI2 generation of EC. Therefore the enhanced PGI2 generation by AII in AR was considered to be mainly derived from the mechanical stimulation to EC by the AII induced smooth muscle cells contraction. (3) It was speculated that the enhanced PGI2 generation by AI or BK might be modulated through their activating effect on ACE as an autoregulatory mechanism.

Angiotensin I↗
PubMed1987

Voltage-activated potassium, but not calcium currents in cultured bovine aortic endothelial cells.

The electrophysiological properties of cultured bovine aortic endothelial cells were characterized using the patch clamp technique. Resting potentials were measured on passing to the whole cell recording configuration and were close to--65 mV in healthy cells. In cell-attached recordings with a high potassium pipette solution, inward single channel currents were observed with zero applied pipette potential. A linear slope conductance of 25 pS was found for a wide range of hyperpolarizing patch potentials and also for depolarizing patch potentials of up to 50-60 mV. A pronounced inward rectification was apparent as no reversal of these currents was seen for larger depolarizations. Whole cell recording in physiological solutions revealed the presence of a hyperpolarization-activated inward current with strong inward rectification and no voltage-dependent ionic current was observed upon depolarization in this subset of cells. Substitution of potassium for external sodium resulted in a shift in the zero current potential consistent with potassium being the main permeant ion. Together with the characteristic voltage-dependent blocking actions of external sodium ions and low concentrations of barium and caesium ions, our results indicate that this current is very similar to the classical inward rectifier as originally described in skeletal muscle and in tunicate eggs. In a second population of cells, a depolarization-activated outward current displaying characteristics of the fast transient A-type potassium current as first reported in molluscan neurones was also observed. No evidence for inward voltage dependent sodium or calcium currents was found.

Animals↗
PubMed1987

Assessment of myocardial blood flow by real-time infrared imaging.

In order to evaluate the applicability of infrared imaging for the assessment of myocardial perfusion, 10 open-chested dogs were studied by a real-time infrared imaging system. The left anterior descending coronary artery was occluded for 90 min followed by 210 min of reperfusion. During the experiment, myocardial surface temperature was mapped by an infrared imaging system with a thermal resolution power of 0.1 degree C and correlated with regional myocardial blood flow measured using radiolabeled microspheres. Following the experiment, acute myocardial injury was evaluated using triphenyltetrazolium chloride staining. After 90 min of ischemia, there was a significant correlation between myocardial blood flow and myocardial surface temperature (R = 0.694, P less than 0.001). After reperfusion, temperature did not correlate with blood flow, but there was a significant correlation between temperature and ischemic myocardial injury (R = 0.551, P less than 0.05). Temperature changes during acute regional ischemia and reperfusion may be regulated by the changes in myocardial blood flow and myocardial metabolism. Temperature analysis using real-time infrared imaging may be a useful means for the evaluation of myocardial blood flow and myocardial injury during ischemia and reperfusion.

Animals↗
PubMed1987

Effects of angiotensin I converting enzyme (ACE)-related substances on prostacyclin generation and ACE activity of human vascular endothelial cells and rat aortic rings.

The effects of angiotensin I (ANG I) converting enzyme (ACE)-related substances on prostacyclin (PGI2) generation were investigated using cultured human vascular endothelial cells (EC) and rat aortic rings. ANG I or bradykinin (BK) increased while captopril decreased PGI2 generation and ACE activity of EC, whereas ANG II was without effect. The enhancement of PGI2 generation induced by ANG I or BK was not affected by the pretreatment with captopril. In rat aortic rings, ANG I, ANG II, and BK enhanced whereas captopril (10(-3) M) attenuated PGI2 generation. Mechanical stimulation of aortic rings stimulated PGI2 generation. These results suggest that (a) the conversion of ANG I to ANG II did not enhance PGI2 generation in EC; (b) the ANG II stimulated PGI2 generation of aortic rings was partially derived by mechanical stimulation of EC, probably originating from the contraction of smooth muscle cells by ANG II; (c) captopril directly inhibited PGI2 generation; and (d) in EC, the stimulation of PGI2 generation by ANG I or BK is probably regulated by an activating effect on ACE as an autoregulatory mechanism.

Animals↗
PubMed1987

A Japanese patient with the Dubowitz syndrome.

A 2-year-old Japanese male whose clinical features included intrauterine and postnatal growth retardation, mild mental retardation, microcephaly and characteristic facial appearance including sloping forehead, blepharophimosis, ptosis of unilateral eyelid, broad nasal bridge, dysplastic auricles, and retrognathia, is presented. The clinical findings of this patient are strikingly similar to those of patients with the Dubowitz syndrome. However, all reported cases with the Dubowitz syndrome are Caucasians. This syndrome may be diagnosed even in sporadic cases of any ethnic groups based on the characteristic features.

Child↗
PubMed1987

Hypoxia enhances unilateral lung injury by increasing blood flow to the injured lung.

We hypothesized that in unilateral lung injury, bilateral hypoxic ventilation would induce vasoconstriction in the normal lung, redirect blood flow to the injured lung, and cause enhanced edema formation. Unilateral left lung injury was induced by intrabronchial instillation of 1.5 ml/kg of 0.1 N HCl. After HCl injury, blood flow to the injured left lung decreased progressively from 0.70 +/- 0.04 to 0.37 +/- 0.05 l/min and percent of flow to the injured left lung (QL/QT) decreased from 37.7 +/- 2.2 to 23.6 +/- 2.2% at 240 min. Exposure to hypoxia (12% O2) for three 10-min episodes did not affect QL/QT in normal animals, but after unilateral HCl injury, it caused blood flow to the injured left lung to increase significantly. A concomitant decrease in blood flow occurred to the noninjured right lung, resulting in a significant increase in QL/QT. The enhanced blood flow to the injured lung was associated with a significant increase in the wet-to-dry lung weight ratio in the dependent regions of the injured lung. These findings demonstrate that in unilateral HCl-induced lung injury, transient hypoxia can enhance blood flow to the areas of injury and increase lung edema formation.

Animals↗
PubMed1987

Nude mice bearing human CSF-producing tumor: analysis of hemopoietic factor(s) acting on primitive stem cells.

Previously, we serially transplanted tumors that produced colony-stimulating factor (CSF) into nude mice, who developed marked granulocytosis along with tumor growth; their leukocyte counts reaching approximately one million per cu mm. The numbers of CFU-GM, CFU-E, CFU-Meg, CFU-S and BFU-E were increased in nude mice bearing CSF-producing tumor. We here report that tumor-conditioned medium (TCM) derived from the CSF-producing tumors had colony-stimulating activity (CSA) and burst-promoting activity (BPA) when normal murine spleen cells as well as normal human bone marrow cells were the target cells. The activity of TCM supported multilineage colony formation in 5-fluorouracil (5-FU)-treated mouse spleen cells, in which only the primitive population of stem cells was reserved. No interleukin-3 (IL-3) activity was detected in TCM when assayed using the IL-3 dependent cell lines. We conclude that the factor in TCM acts on pluripotent stem cells and on the early progenitor stage of various cell lineages. It is distinct from IL-3.

Animals↗
PubMed1987

Myocardial oxygen metabolism of the right ventricle with volume loading and hypoperfusion.

A comparison of blood flow and myocardial O2 consumption (MVO2) in the right and the left ventricles was made in dogs whose chests had been opened. The effect of volume loading by arterio-venous and arterio-left atrial shunts, and the effect of ventricular hypoperfusion by rapid removal of blood were examined in the presence and absence of the pericardium. Blood flow per unit myocardium was greater in the left anterior descending coronary artery (LAD) than in the right coronary artery (RCA), 75 +/- 4.3 vs. 46 +/- 2.8 (mean +/- SE) ml/min per 100g, respectively. Similarly, the myocardial O2 extraction ratio (EO2) was 59 +/- 2% in the left ventricle and 43 +/- 3% in the right ventricle (p less than 0.001). The MVO2 was greater for the left than for the right ventricle, 8.0 +/- 0.6 vs. 3.5 +/- 0.3 ml O2/min per 100g. Volume loading to both ventricles by arterio-venous (AV) shunt increased MVO2 of the right ventricle by augmented EO2 in addition to a rise in the coronary arterial blood flow. Decrease in aortic pressure by rapid removal of blood increased EO2 in both ventricles. The increments of EO2 were greater in the right ventricle than in the left ventricle, 54 vs. 31% (p less than 0.01). When the pericardium was closed with suture, right and left end-diastolic pressure rose, but EO2 and coronary blood flow of both ventricles did not change. We conclude that reserve capacity of myocardial O2 extraction was greater in the right ventricle than in the left ventricle.

Animals↗
PubMed1987

Attenuation of hypothalamo-sympathetic hyperactivity by renal denervation in experimental hypertensive rats.

To clarify the effect of renal nerves on hypothalamic cardiovascular regulation in hypertension, posterior hypothalamus was electrically stimulated in renal denervated SHR (RD-SHR) and DOCA hypertensive (RD-DOCA) rats during recording blood pressure and sympathetic nerve activity. In urethane anesthetized SHR, mean blood pressure was not different between RD- and sham-operated SHR 48 hours after denervation, but two weeks later, blood pressure was lower in RD-SHR. Pressor and sympathetic nerve responses to hypothalamic stimulation were partly attenuated 48 hours after denervation, but two weeks later, attenuation was strong. The development of hypertension was abolished during two weeks observation in RD-SHR. In DOCA hypertensive rats, the development of hypertension was significantly inhibited by renal denervation. Pressor and sympathetic nerve responses to hypothalamic stimulation were significantly diminished in RD-DOCA rats. Water intake and urine volume was identical in both groups. These results suggest that renal denervation inhibited the development of hypertension accompanied with the inhibition of hypothalamo-sympathetic nerve system, furthermore, it is indicated that hypothalamic cardiovascular regulation controlled by afferent renal nerve could contribute to the development of hypertension in SHR and DOCA hypertensive rats.

Animals↗
PubMed1987

Central effect of captopril on baroreflex.

To clarify effect of converting enzyme inhibitors (CEI) on heart rate regulation, captopril (2 mg/kg) was injected intravenously (i.v.) with or without pretreatment of atropine and also responses to intracisternal (i.c.) injections were examined. Captopril induced bradycardia with lowering blood pressure, and this bradycardia was abolished by pretreatment of atropine. Reduction of heart rate by i.c. injection of captopril was significantly larger than those of i.v. injection. Furthermore, to determine whether CEI can modify baroreflexes centrally, the aortic depressor nerve (ADN) was stimulated electrically in captopril treated rats. Vasodepressor and sympatho-inhibitory responses induced by ADN stimulation were significantly attenuated by captopril, while the bradycardiac response was not changed. These findings suggest that captopril attenuated centrally vasodepressor and sympatho-inhibitory responses of the baroreflex and activated centrally cardiac vagal efferent activity.

Animals↗