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Biomedical subjects

H Uematsu

Publications and source records attributed to H Uematsu.

At least 55 records · Page 3Linked to original sources
PubMed1991

Effect of hypertonic saline infusion on renal vascular resistance in anesthetized dogs.

Changes in renal vascular resistance (RVR) and their mechanisms were investigated following infusion of 7.5% hypertonic saline (4 ml/kg) in anesthetized dogs. In all animals the left kidney was perfused at a constant perfusion flow (59 +/- 6 ml/min) with heparinized blood using a pulsatile roller pump. Renal perfusion pressure (RPP), systemic blood pressure (SBP), central venous pressure (CVP), and heart rate (HR) were measured simultaneously. Electrical stimulation of renal sympathetic nerves was also performed to evaluate the neurally mediated change in renal vasculature before and after infusion of hypertonic saline. In animals with intact vagi, intravenous administration of hypertonic saline resulted in significant increases in both mean blood pressure (MBP) and CVP, and caused significant decreases in HR and RVR. These effects were not affected by bilateral cervical vagotomy. In both intact and vagotomized animals, changes in RVR in response to renal nerve stimulation were attenuated after infusion of hypertonic saline. These results suggest that reduction in RVR after intravenous infusion of hypertonic saline is not a reflex effect mediated by vagal afferents. Instead, vascular response of the renal artery to hypertonic saline may result from a suppression of neurotransmission from renal sympathetic nerve endings to renal vascular smooth muscle.

Animals↗
PubMed1991

Characterization of antisense DNA derivatives having stereoisomeric linkages.

The isomer separation of oligonucleoside phosphoramidates (OPA) by RPLC was studied. All stereoisomers of OPA-tetramer (dATCG) modified with isopropylamine could be separated and they showed different CD spectra each other. OPA-decamer (dGGGCATCGTC) modified with 3-amino-1-propanol could be separated into five fractions. Each fraction was found to have different ability to form hybrids with its complementary oligonucleotide, indicating that it is possible to exclude stereoisomers which can hardly bind to target nucleic acids.

Amides↗
PubMed1991

[Evaluation of intraoperative transesophageal echocardiography].

With the development of medical ultrasonics, anesthesiologists have recognized the usefulness of transesophageal echocardiography as an intraoperative monitoring. Intraoperative transesophageal echocardiography is now used to monitor left ventricular function and to confirm the result of surgical correction immediately after cardiac operation. In this study, we evaluated the detectability of air embolism and the effect of hemodynamic changes on physiological mitral regurgitant flow by transesophageal Doppler echocardiography (TEDE). TEDE was more sensitive than precordial Doppler ultrasound in detecting intracardiac air. TEDE could detect air inflow to the right atrium earlier than alterations in pulmonary hemodynamics. The monitoring of intracardiac air by TEDE minimized the complication by air embolism. Regarding physiological mitral regurgitation, the degree of regurgitation increased with the elevation of BP in 70% of patients. An increase in afterload seemed to cause accidental volume loading on the left heart resulting in physiological mitral regurgitation. Intraoperative monitoring of regurgitant flow by TEDE was useful for the anesthesiologist as a guide of hemodynamic management. Transesophageal echocardiography is a useful intraoperative monitoring method regardless of its several disadvantages. With further improvement of mechanical device, transesophageal echocardiography will be more often and safely performed in operating room.

Echocardiography, Doppler↗
PubMed1990

Contribution of baroreceptor reflexes to blood pressure and sympathetic responses to cholecystokinin and vasoactive intestinal peptide in anesthetized dogs.

The effects of synthetic vasoactive intestinal peptide (VIP) and cholecystokinin (CCK) on systemic blood pressure and renal nerve activity were studied before and after cervical vagotomy, and sino-aortic denervation with vagotomy in anesthetized dogs. Intravenous injection of VIP (5 micrograms/kg) in animals with an intact neuraxis produced a significant decrease in systemic blood pressure and a significant increase in renal nerve activity. These responses to VIP did not change after vagotomy and after complete denervation, VIP did not cause any change in renal nerve activity, even during hypotension. The level of hypotension after complete denervation was greater than that under other conditions. These results indicate that the cardiovascular effects of VIP are reduced by activation of the systemic baroreceptors. Intravenous injection of CCK (10 micrograms/kg) in animals with an intact neuraxis produced significant decreases in blood pressure and renal nerve activity. These responses to CCK were abolished in animals with cervical vagotomy only. However, following complete denervation of the carotid sinus and total section of the vagal nerves, CCK caused a significant increase in blood pressure and renal sympathetic nerve activity. These results indicate that the sympathetic depressor effect of CCK may be mediated by activation of the vagal afferents, and that the sympathetic pressor effect may be due to a direct action of CCK on the central nervous system. Thus, each gastrointestinal peptide may regulate the cardiovascular system through a different mechanism.

Anesthesia↗
PubMed1990

Reflex effects on renal nerve activity and renal vascular tone during occlusion of superior mesenteric artery in anesthetized dogs.

This study was designed to evaluate the contribution of the systemic baroreceptor reflex on renal nerve activity (RNA) and renal vascular resistance (RVR) during occlusion of the superior mesenteric artery (SMAO) in anesthetized dogs. Animals were divided into two groups; RVR evaluated group and RNA measured group. For evaluation of changes in RVR, the left kidney was perfused at a constant flow with heparinized blood by using a pulsatile roller pump. Renal perfusion pressure, arterial blood pressure and heart rate were measured simultaneously. During SMAO, MAP and RVR increased significantly in animals with intact systemic baroreceptors. After combined denervation of the carotid sinus and vagal nerves, a significant enhancement of this RVR response during SMAO occurred and the level of changes in RVR were significantly greater than those in animals with an intact neuraxis. In the RNA measured group, renal sympathetic nerve activity, arterial blood pressure and heart rate were measured simultaneously before and during SMAO. During SMAO, MAP and RNA increased significantly in animals with intact systemic baroreceptors. These MAP and RNA responses to SMAO were significantly enhanced in animals with combined denervation of the carotid sinus and vagal nerves. These results indicate that SMAO evokes an increase in arterial blood pressure, renal sympathetic nerve activity and renal vascular resistance. The reflex increase in renal nerve activity and renal vascular tone during SMAO is modified and minimized by an activation of systemic baroreceptors.

Adrenergic Fibers↗
PubMed1990

Inhibitory effect of renal nerve activity during canine anaphylactic hypotension.

We have examined baroreceptor regulation of renal nerve activity (RNA) during anaphylactic hypotension that affects renal nerve activity. In anesthetized dogs, mean blood pressure (MBP), heart rate (HR), and RNA were simultaneously measured. To test for a normally functioning baroreceptor reflex in each animal, a transient hypotension was induced by an intravenous injection of sodium nitroprusside (4 micrograms/kg). Nitroprusside produced a reflex increase in RNA (+63 +/- 12% at -20 mmHg and +139 +/- 8% at -40 mmHg) and HR (+13 +/- 1 beats/min at -20 mmHg and +21 +/- 2 beats/min at -40 mmHg). However, intravenous administration of Ascaris suum antigen in animals with an intact neuraxis caused a decrease in RNA (-15 +/- 14% at -20 mmHg and -42 +/- 11% at -40 mmHg blood pressure during the antigen-induced hypotension) in parallel with a fall in systemic blood pressure. HR responses were -5 +/- 2 beats/min at -20 mmHg and -10 +/- 1 beats/min at -40 mmHg during the hypotension induced by the antigen. In animals with combined denervation of the carotid sinus and vagal nerves, HR did not change significantly during anaphylactic hypotension. However, a decrease in RNA remained (-60 +/- 4% at -20 mmHg and -72 +/- 4% at -40 mmHg of hypotension). The decrease in RNA after antigen administration was significantly greater after denervation than in animals with an intact neuraxis. These results indicate that systemic baroreceptor reflex control of RNA is reduced during anaphylactic hypotension. Impaired reflex control of sympathetic nerve activity may result from an impairment of sympathetic outflow through the central nervous system.

Anaphylaxis↗
PubMed1990

Reflex responses on blood pressure and renal nerve activity to local intra-arterial injection of capsaicin in anesthetized dogs.

The present study was performed to examine effects of intra-arterial and intravenous injection of capsaicin on efferent renal sympathetic nerve activity (RNA) in pentobarbital anesthetized dogs. In animals with intact baroreceptors, intra-arterial injection of capsaicin (4 +/- 1 microgram) produced significant increases in mean blood pressure (MBP) and heart rate (HR) by +43 +/- 8 mmHg and +33 +/- 15 beats/min at 20 s after the injection, respectively. There followed a recovery toward the control so that 60 s after the intra-arterial injection changes in MBP and HR were +8 +/- 5 mmHg and +18 +/- 8 beats/min, respectively. RNA showed a biphasic response, comprising of an initial increase (+52 +/- 28% of the control at 20 s) followed by a decrease by -30 +/- 8% of the control 60 s after the injection. Following bilateral cervical vagotomy the initial increase in RNA did not differ significantly from the value of RNA in animals with intact baroreceptors. However, the later decrease in RNA reversed above the control so that 60 s after the injection change in RNA was +5 +/- 10% of the control. Complete baroreceptor denervation showed a similar response on RNA in the vagotomized animals (+49 +/- 9 and +14 +/- 10% of the control at 20 and 60 s after the injection, respectively). In contrast, intravenous injection of capsaicin (6 +/- 1 microgram/kg) resulted in significant decreases in MBP (-19 +/- 11 mmHg) and HR (-9 +/- 4 beats/min). RNA at 20 s after the injection showed a unidirectional decrease by -16 +/- 7% of the control in animals with intact baroreceptors. These responses reversed above the control after cervical vagotomy. Thus, these data indicate that activation of C-fiber afferents in skeletal muscles by intra-arterial injection of capsaicin results in renal sympathoexcitation, and that the later sympathoinhibition is mediated by combined activation of systemic baroreceptors.

Animals↗
PubMed1990

Structural analysis of nucleic acids by labeled oligonucleotides.

In this report, the characterization of labeled oligonucleotides was discussed from the view points of base sequence analysis and structural analysis of nucleic acids in solution. Oligonucleotides site specifically spin labeled with TEMPO and fluorescent labeled with fluorescein were prepared and used for those analyses. The changes of ESR lines and rotational correlation time (tau) of the spin labeled oligonucleotide (S-probe) were dependent on the base sequence of S-probe, diastereoisomers, and the manner of hybridization. These results suggest that the conformation of the hybrid largely affected the local mobility of TEMPO and that tau value of S-probe reflected the local structure of the hybrid. When S-probe which was complementary to a single strand region of 5S RNA, was mixed with 5S RNA, tau value largely changed, indicating that the S-probe could form hybrid with 5S RNA in solution. Similar results were also obtained in the fluorescence depolarization analysis using fluorescent labeled oligonucleotide (F-probe). These results suggest that S-probe and F-probe are capable for the recognition of the secondary structure of 5S RNA in solution and useful for the analysis of the secondary structure of other nucleic acids in solution.

Base Sequence↗
PubMed1990

[Evaluation of physiological mitral regurgitant flow using transesophageal Doppler echocardiography].

Transesophageal Doppler echocardiography (TEDE) was performed to determine the incidence of physiological mitral regurgitation (MR) and the characteristics of regurgitant blood flow in presumably normal subjects. TEDE included color flow mapping, pulsed Doppler echocardiography and M-mode color flow mapping. Sixty-six surgical patients who had no histories or physical evidence of cardiac abnormalities were studied using TEDE under general anesthesia. MR flow was detected in 94% (62/66) of the patients by transesophageal color flow mapping. Transesophageal color flow mapping clearly differentiated physiological MR flow and signals generated from mitral valve closure. In 40% (25/62) of the patients whose MR flow was detected, transesophageal pulsed Doppler echocardiography (TEPD) revealed regurgitant signals lasting less than half of systole. Only 31% (19/62) had peak MR flow velocities greater than 1 m/sec. TEPD could not detect high velocities reflecting the pressure gradients across the mitral valve. Since the regurgitant volume was very small, TEPD may have been incapable of detecting high velocity components of the MR flow. In conclusion, our data suggested that nearly all normal subjects may have mild mitral regurgitation.

Adolescent↗
PubMed1989

Purification and characterization of a galactose-binding lectin from the skin mucus of the conger eel Conger myriaster.

1. A galactose-binding lectin was purified from the skin mucus of the conger eel Conger myriaster by affinity chromatography and HPLC. 2. The lectin was a simple protein having the same two subunits with a mol. wt of 12,500 and a N-terminal amino acid of phenylalanine. 3. Electrofocusing suggested that the purified lectin was composed of several isolectins. 4. From the ultraviolet difference spectra attributable to tryptophanyl residues in the binding site, the binding constant of the lectin for D-galactose was estimated to be 5.3 x 10(3)/M.

Animals↗
PubMed1989

The effects of 24% paraquat (1,1'-dimethyl-4,4'-bipyridylium dichloride) on hemodynamics, blood gases, plasma lactate and plasma catecholamines in dogs.

The cause of death after ingestion of a large dose of paraquat is unclear. We investigated the cardiovascular effects of paraquat injection in 7 dogs that were anesthetized with urethane and alpha-chloralose and maintained on controlled ventilation. After control measurements, paraquat (20 mg/kg) was injected iv. Average concentrations of plasma paraquat were 128 micrograms/ml at 15 min (point 1) and 44 micrograms/ml at 4 hr. The average time of survival was 5.5 +/- 2.2 hr. Comparison was made of control values, 15 min (point 1), and 2.5 +/- 1.0 hr before death (point 2). Pulmonary capillary wedge pressure (+33%) and pulmonary vascular resistance (PVR) (+28%) increased, but no change occurred in mean arterial pressure (MAP) or cardiac output (CO) at 15 min. Mean arterial pressure (-50%) and cardiac output (-61%) decreased, while total vascular resistance (+56%) and PVR (+256%) were increased at point 2. Arterial pH decreased from 7.394 and 7.307 (point 1) to 7.143 (point 2). The concentration of plasma catecholamines and lactic acid increased significantly at both points 1 and 2. Renal, adrenal and myocardial tissues were studied by light and electron microscopy. The outstanding feature was early swelling of mitochondria and disruption of the contents in the presence of intact mitochondrial membrane.

Animals↗
PubMed1989

[Kappa-type opioid receptor in human placental membrane].

Since many opioid receptor preparations are heterogeneous systems containing multiple types of receptor, characterization of each type of the receptor is influenced by contamination with other types of receptor. Demonstrating kappa receptor proved more difficult owing to the ability of kappa ligands to interact with a number of receptor classes and to the lack of the homogeneous preparation. It has been reported that kappa ligands selectively bind to human placental membrane. To establish homogeneous kappa receptor preparation, the kappa binding to human placenta was characterized. The portion which was predominantly villus tissue was removed from freshly collected placenta, and the P3-membrane fraction was prepared. Kappa opioid agonist, such as 3H-Dynorphin A, 3H-ethylketocyclazocine and 3H-U-69593, bound to the human placental membrane fraction in a manner of single class of binding site (Bmax: approximately 40 fmol.mg-1 protein). In contrast, 3H-dihydromorphine, 3H-DAGO (mu agonist), 3H-DADLE (delta agonist) or 3H-SKF-10047 (sigma agonist) showed no binding activity. The specific binding of 3H-diprenorphine was displaced only by kappa-selective ligand (U-50488H, dynorphin, butorphanol). These results suggest that opioid binding in human placental membrane is specific for kappa opioid.

Humans↗
PubMed1989

[A case report of reflex sympathetic dystrophy treated with nifedipine].

Reflex sympathetic dystrophy (RSD) refers to a symptom complex observed after nerve injury and consists primarily of severe burning pain associated with sensory, vasomotor and trophic phenomena. A 54-year-old male had undergone nephrectomy. At surgery left XIth intercostal nerve had been injured by cautery. After a few weeks following surgery, the patient developed progressive deep burning pain, stabbing sensation and dysesthesia in the left abdominal region. Analgesics and narcotics were ineffective. We diagnosed his case as RSD. He received nifedipine 10mg sublingually. Pain relief was obtained within 10min and lasted for 6hs. Consequently, nifedipine therapy was started at a daily dose of 30 to 60mg. His symptoms were markedly improved within 4 weeks. After 3 months his pain resolved. At the present, some pain often returns, but nifedipine is effective. Nifedipine may be useful as a drug for the management of reflex sympathetic dystrophy.

Humans↗
PubMed1988

Sites of origin of ventricular premature beats in patients with and without cardiovascular disease evaluated by body surface mapping.

The site of origin of ventricular premature beats (VPBs) was estimated by QRS maps and its distribution in two patient groups was studied. VPB origin was determined by comparing the body surface map of VPBs with that during electrical stimuli applied at various sites of the ventricle. Subjects were 100 patients without obvious underlying cardiovascular disease (Group N) and 289 patients with various heart diseases (Group D). Nine sites of origin of VPB were identified. In group N, VPBs of right ventricular origin were noted in 69%, those of left ventricular origin in 6%. There was a relatively high incidence of VPBs with foci estimated to be the divisions of the left bundle branch, and the age of patients with these VPBs was young. In Group D, VPBs of left ventricular origin showed a higher incidence (34.6%) and those of right ventricular origin a lower incidence (41.2%) than those in group N. The data suggest that VPBs originating from the apex and base of the ventricle strongly indicate the presence of basic heart disease and that VPBs originating in or near the divisions of the left bundle branch in younger subjects do not necessarily indicate cardiac disease.

Adolescent↗