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Biomedical subjects

Y Saeki

Publications and source records attributed to Y Saeki.

At least 127 records · Page 7Linked to original sources
PubMed1994

[Changes in anal canal pressure during caudal and lumbar epidural anesthesia].

To compare anesthetic effect of caudal and lumbar epidural anesthesia, anal canal pressure during these anesthesia was measured. Anal canal pressure under resting condition decreased soon after injection of local anesthetics into epidural space in both groups. In early post injection stage the pressure decreased more in caudal group than in lumbar epidural group. The pressure when anus was contracted at will fall significantly further in caudal group than in lumbar group. These results suggest that caudal anesthesia should be utilized for obtaining full muscle relaxation of anal area in a short time compared with lumbar epidural anesthesia.

Adult↗
PubMed1994

Effect of seaweed extracts on Streptococcus sobrinus adsorption to saliva-coated hydroxyapatite.

The inhibitory effect of the extracts of seaweeds on the adsorption of Streptococcus sobrinus B13 to the tooth surface was investigated in vitro. Using saliva-coated hydroxyapatite beads (S-HA) as experimental salivary pellicle, extracts from Gloiopeltis furcata and Gigartina teedii (Rhodopheceae) strongly inhibited the adsorption of S. sobrinus B13 to S-HA. The G. furcata extract, which strongly inhibited the adsorption of S. sobrinus B13 to S-HA, was a high molecular weight sulfated polysaccharide. The result of I.R. analysis indicated that the active component in this extract of G. furcata was funoran.

Bacterial Adhesion↗
PubMed1993

Molecular cloning of a novel putative G protein-coupled receptor (GPCR21) which is expressed predominantly in mouse central nervous system.

A novel cDNA clone encoding a putative G protein-coupled receptor (named GPCR21) was isolated from a mouse brain cDNA library along with its homologue, GPCR01 (the mouse counterpart of previously reported rat receptor R334 [(1991) FEBS Lett. 292, 243-248]) by the polymerase chain reaction using degenerate oligonucleotide primers. Northern blotting and reverse transcription-polymerase chain reaction analyses showed predominant expression of these two receptors in the central nervous system. In situ hybridization analysis revealed their prominent expression in the limbic system and further demonstrated the differential distribution of their mRNAs in mouse brain. Although the ligands for these receptors are yet to be identified, the significant sequence homology between these receptors suggests that they constitute a new receptor subfamily and they possibly represent different receptor subtypes for an unknown neurotransmitter.

Amino Acid Sequence↗
PubMed1993

Renal vascular and sympathetic nerve responses to hypotension induced by platelet-activating factor in anesthetized dogs.

This experiment was designed to determine renal sympathetic and renal vascular responses to platelet-activating factor (PAF)-induced hypotension in anesthetized dogs with and without systemic baroreceptor denervation. The left kidney was perfused at a constant flow, and renal perfusion pressure and efferent left renal sympathetic nerve activity were measured simultaneously. Intrarenal injection of PAF (1.25-5.0 x 10(-2) micrograms/kg, n = 6) produced a dose-dependent increase in renal perfusion pressure without any change in systemic blood pressure. An intravenous injection of PAF (10 micrograms/kg) to intact animals (n = 7) caused an initial increase in renal nerve activity (157 +/- 14%) followed by a gradual reduction below baseline (72 +/- 7%) with concomitant systemic hypotension (from 116 +/- 7 to 46 +/- 6 mmHg). Renal perfusion pressure increased significantly from 84 +/- 2 to 161 +/- 33 mmHg concomitant with an increase in renal nerve activity at 1 min and was maintained at this elevated level throughout the experiment. Similar responses of renal nerve activity and renal perfusion pressure were found in animals with complete systemic baroreceptor denervation (n = 7). These results suggest that renal vascular response during PAF-induced hypotension may presumably be mediated by a direct vasoconstrictor effect of PAF on the renal vasculature and that baroreceptor reflex is not involved in either renal sympathetic or renal vascular changes.

Animals↗
PubMed1993

Expression of the D3 dopamine receptor gene and a novel variant transcript generated by alternative splicing in human peripheral blood lymphocytes.

The sequential reverse transcription and polymerase chain reaction amplified the mRNA coding for the D3 dopamine receptor (D3R) in human peripheral blood lymphocytes. Pharmacological analysis confirmed the binding of the D3R specific ligand to the lymphocytes. In addition, there was a novel shorter variant transcript of the D3R gene generated by alternative splicing in lymphocytes and brain. This variant, termed D3(TM4-del), has a 143 bp deletion and encodes a 138 amino acid protein containing the first three transmembrane domains of the native D3R.

Adult↗
PubMed1993

Effects of verapamil on the cardiac alpha 1-adrenoceptor signalling system in diabetic rats.

We evaluated the effects of chronic verapamil treatment on the cardiac alpha 1-adrenoceptor signalling system in streptozocin-induced diabetic rats. The decrease in maximum cell surface [3H]bunazosin binding (Bmax) in isolated cardiac myocytes from the diabetic group (-46%, P < 0.01) was completely reversed by a 4-week course of verapamil, while Bmax in the verapamil-treated control group was unchanged. Similarly, the reduction in ventricular inositol 1,4,5-trisphosphate (IP3) production after stimulation with 10 microM noradrenaline (NA) seen in diabetes (-30%, P < 0.01) was completely normalized by verapamil, while the response in the verapamil-treated control group was unaffected. These results indicate that verapamil can induce complete recovery of the impaired cardiac alpha 1-adrenoceptor signalling system in the diabetic heart without affecting glucose metabolism.

Animals↗
PubMed1993

Simple, rapid, and accurate determination of deletion mutations by automated DNA sequencing of heteroduplex fragments of the adenomatous polyposis coli (APC) gene generated by PCR amplification.

Germline mutations in patients with familial adenomatous polyposis were analyzed by polymerase chain reaction (PCR) amplification of the adenomatous polyposis coli gene. PCR products from heterozygous patients for deletions of this gene formed four distinct bands on polyacrylamide gel electrophoresis. The four fragments were subsequently purified and both strands of each fragment were directly sequenced, using an automated DNA sequencer and the same primers as those for PCR amplification. It was found that the two slower migrating fragments were "bulge" heteroduplexes, while the other two were homoduplexes made up of two wild-type strands and two deletion-mutant strands, respectively. The sites of deletions in the adenomatous polyposis coli gene could be exactly determined in four of the five patients. In an attempt to identify deletion-carriers of familial adenomatous polyposis at the presymptomatic stage, a family study was also carried out, and two children were found to have the same mutations as those of their affected parents. The direct sequencing of heteroduplex fragments generated during PCR amplification is a potentially useful method for detecting mutations of not only the adenomatous polyposis coli gene but also many other genes of genetic diseases.

Adenomatous Polyposis Coli↗
PubMed1993

Pharmacokinetics of (Me)Arg-Lys-Pro-Trp-tert-Leu-Leu-OEt and (Me)Arg-Lys-Pro-Trp-tert-Leu-Leu administered intravenously to beagle dogs.

The pharmacokinetics of two analogues (NT-1 and NT-2) of the smallest active fragment of neurotensin were investigated in beagle dogs after intravenous (iv) administration at the doses of 0.1 and 0.5 mg/kg for NT-1 and of 0.25 and 0.5 mg/kg for NT-2. After iv administration of these two drugs, the plasma levels decreased with time with a biexponential pattern, and linear kinetic behavior was observed. The pharmacokinetic parameters (mean +/- standard error of mean) after iv administration of NT-1 at 0.1 mg/kg were as follows: the half-life of the distribution phase (t1/2 alpha) was 0.29 +/- 0.11 h, the half-life of the terminal phase (t1/2 beta) was 1.99 +/- 0.41 h, total plasma clearance (CL) was 33.2 +/- 6.3 mL/h/kg, steady-state volume of distribution (Vdss) was 57.1 +/- 2.8 mL/kg, and mean residence time (MRT) was 2.20 +/- 0.55 h. The t1/2 alpha, t1/2 beta, CL, Vdss, and MRT values after iv administration of NT-2 at 0.25 mg/kg were 0.11 +/- 0.02 h, 0.58 +/- 0.04 h, 257.3 +/- 17.2 mL/h/kg, 180.3 +/- 4.6 mL/kg, and 0.71 +/- 0.04 h, respectively. After iv administration of NT-1, NT-2 was detected in the plasma. It was confirmed from this result that NT-1 was metabolically hydrolyzed to NT-2 in the body of beagle dog.

Amino Acid Sequence↗
PubMed1993

Polyunsaturated fatty acid metabolism and acetylated low density lipoprotein uptake in J774A.1 cells.

The mechanism of the antiatherogenic activity of n-3 polyunsaturated fatty acids is not well understood. In these studies, we studied the metabolism of unsaturated fatty acids in murine macrophage-like J774A.1 cells. The major metabolic pathway of 18- and 20-carbon chain unsaturated fatty acids in these cells is the sequence of 2-carbon chain elongation, successive two steps of delta 8- and delta 5-desaturation, and additional elongation. Polyunsaturated fatty acids, arachidonic acid [20:4 (n-6)] and eicosapentaenoic acid [20:5 (n-3)], are elongated into 22:4 (n-6) and 22:5 (n-3) fatty acids, respectively. Accumulation of 22:4 (n-6) and 22:5 (n-3) fatty acids shows that J774A.1 cells have an active chain elongation activity, but lack delta 4-desaturase activity. Furthermore, J774A.1 cells demonstrated almost negligible delta 6-desaturase activity. Enrichment of the membrane lipids of J774A.1 cells with polyunsaturated fatty acids, arachidonic acid [(20:4 (n-6)] and eicosapentaenoic acid [(20:5 (n-3)], increased membrane fluidity and decreased the uptake of acetylated low density lipoprotein.

Animals↗
PubMed1993

Tension and intracellular calcium transients of activated ferret ventricular muscle in response to step length changes.

To elucidate the effects of mechanical constraints on the (Ca2+) affinity of cardiac troponin C, we studied the relationships among the myoplasmic Ca2+ concentration ([Ca2+]i), tension and length in steadily activated intact cardiac muscle. The Ca2+ sensitive photoprotein, aequorin, was micro-injected into cells of ferret right ventricular papillary muscles to monitor the [Ca2+]i. The muscle was then steadily activated with ouabain (10(-4) M)(ouabain contracture) or high frequency stimuli in the presence of ryanodine (5 microM)(tetanic contraction); the tension and aequorin light (AL) transients in response to a step length change were then analyzed. The tension transient response to either the stretch or release in length was oscillatory: tension decreased rapidly during the release and then increased, after which it lapsed into a new steady level in a series of damped oscillations. The opposite was true for the stretch. The oscillatory responses were conspicuous and less damped in the ouabain contracture. The transient AL response was also oscillatory, the time course of which corresponded exactly to that of the tension transient response, though no detectable changes in AL were observed at the initial phase of the stretch response. The increase in AL corresponded exactly to the decrease in tension, likewise the decrease in AL to the increase in tension. The steady level of AL after release was decreased in ouabain contracture, but was increased in tetanic contraction. These results suggest that the Ca2+ affinity of cardiac troponin C is increased with an increase in tension (i.e., the cross-bridge attachment) and decreased with a decrease in tension (i.e., the cross-bridge detachment), and that the myoplasmic calcium concentration is lowered by release, at least in a Ca(2+)-overloaded condition, mainly through the sarcoplasmic reticulum.

Aequorin↗
PubMed1993

Increase in vertical dimension alters mechanical properties and isometric ATPase activity in guinea pig masseter.

To study the changes in mechanical and metabolic properties associated with an increase in the vertical dimension of the face, isometric tension, isometric ATPase activity, unloaded shortening velocity (Vmax), and the tension transients in response to step stretches in length were measured at constant levels of various Ca2+ activations in glycerinated masseter muscles (75 to 150 microns in diameter and about 3 mm long) from normal and bite opened (6 mm increase in the vertical dimension, period of 1 week) guinea pigs. The isometric tension increased sigmoidally with an increase in Ca2+ concentration in both preparations. However, the bite opening shifted the pCa-relative tension relationship in the direction of increasing Ca2+ required for activation, and the pCa at Km (Ca2+ concentration required to develop half maximum tension) was 6.40 +/- 0.08 in control and 6.27 +/- 0.05 in the bite opened preparations. The maximum isometric tension at the saturating Ca2+ concentration was greater in the bite opened preparation. The ATPase activity changed almost in parallel with the tension (i.e., Ca2+ concentration) in both preparations. However, the tension cost (ATPase activity/tension) was significantly (p < 0.05) lower in the bite opened preparation, compared with the control. The Vmax at the saturating Ca2+ concentration was lower in the bite opened preparations. The tension transients in response to step stretch in length were characterized by four distinct phases; the first phase of an immediate tension increase coincident with the stretch, the second phase of a rapid quasi-exponential tension reduction, the third phase of a minute tension increase and the fourth phase of a slow tension reduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1993

Alterations in intracellular calcium and tension of activated ferret papillary muscle in response to step length changes.

1. To study the effects of mechanical constraints on the calcium (Ca2+) affinity of cardiac troponin C, we analysed the tension and aequorin light (AL, intracellular Ca2+) transients in response to a step length change in aequorin-injected ferret right ventricular papillary muscles. The muscle preparations were continuously activated with ouabain (10(-4) M) (ouabain contracture) or with high frequency stimuli in the presence of ryanodine (5 microM) (tetanic contraction). 2. The tension transient in response to either the release or stretch was oscillatory: tension decreased rapidly during the release and then increased, after which it lapsed into a new steady level in a series of damped oscillations. The opposite was true for the stretch. The oscillatory responses were conspicuous and less damped in ouabain-activated preparations (oscillation frequency of 2.2-2.3 Hz at 22 degrees and 4.5-4.6 Hz at 30 degrees C) and much more damped in ryanodine-treated preparations. 3. The transient AL response was also oscillatory, the time course of which corresponded to that of the transient tension response. Regardless of the difference in the time course of the transients in two different preparations and at two different temperatures, the increase in AL corresponded to the decrease in tension, likewise the decrease in AL to the increase in tension. 4. The mean level of AL after release was lower than the control level present just prior to the release in ouabain-activated preparations, but the AL after release finally returned to the nearly control level in ryanodine-treated preparations. 5. When the ryanodine-treated muscle was further treated with 2,3-butanedione monoxime (BDM) (20 mM), the tetanic tension decreased remarkably without affecting the AL signal. The tension transient of this preparation was quite similar to that of the resting muscle, which changed in a nearly stepwise fashion; AL was hardly affected by step length changes, as in the resting muscle, in spite of the higher AL level. 6. These results suggest that the Ca2+ affinity of cardiac troponin C is increased with an increase in tension (i.e. the cross-bridge attachment) and decreased with a decrease in tension i.e. the cross-bridge detachment), and that the mean [Ca2+]i is lowered by release, at least in a Ca(2+)-overloaded condition, mainly through the sarcoplasmic reticulum.

Aequorin↗
PubMed1993

PAF increases capillary pressure but not vascular permeability in isolated blood-perfused canine lungs.

We determined the effects of platelet-activating factor (PAF) on pulmonary vascular resistance, lung weight, and microvascular permeability in isolated canine lungs perfused at constant pressure with autologous blood. PAF caused a dose-dependent increase in total pulmonary vascular resistance (Rt) and pulmonary capillary pressure assessed as double-occlusion pressure. PAF (33 micrograms; n = 7) caused a 10-fold increase in Rt and a decrease in precapillary-to-postcapillary vascular resistance ratio from 0.97 +/- 0.10 to 0.38 +/- 0.03, suggesting predominant pulmonary venoconstriction. Shortly after PAF, lung weight decreased transiently and then increased, reaching a plateau above baseline (112.5 +/- 1.6%) at 30 min. In lungs perfused in the antidromic direction from the pulmonary vein to the artery (n = 5), PAF (33 micrograms) produced marked precapillary vasoconstriction, consistent with pulmonary venoconstriction, and a remarkable and sustained decrease in lung weight below baseline by 30 min. Vascular permeability, measured 30 min after PAF using the capillary filtration coefficient and isogravimetric capillary pressure, did not change significantly from baseline. Thus we conclude that PAF produces lung weight gain by means of an increase in capillary pressure predominantly due to pulmonary venoconstriction without significant changes in vascular permeability in isolated blood-perfused canine lungs.

Animals↗
PubMed1993

Crossbridge scheme and the kinetic constants of elementary steps deduced from chemically skinned papillary and trabecular muscles of the ferret.

Elementary steps of the crossbridge cycle in chemically skinned ferret myocardium were investigated with sinusoidal analysis. The muscle preparations were activated at pCa 4.82 and an ionic strength of 200 mM, and the effects of the change in the MgATP (S) and phosphate (Pi) concentrations on three exponential processes were studied at 20 degrees C. Results are consistent with the following crossbridge scheme: [formula: see text] where A is actin, M is myosin, D is MgADP, and Det includes all detached states (MS and MDP) and weakly attached states (AMS and AMDP). From our studies, we obtained K1a = 0.99 mM-1 (MgATP association), k1b = 270 s-1 (ATP isomerization), k-1b = 280 s-1 (reverse isomerization), K1b = k1b/k-1b = 0.95, k2 = 48 s-1 (crossbridge detachment), k-2 = 14 s-1 (reverse detachment), K2 = 3.5, k4 = 11 s-1 (crossbridge attachment), k-4 = 107 s-1 (reverse attachment), K4 = 0.11, and K5 = 0.06 mM-1 (Pi association). K6 is the rate-limiting step, and it is the slowest forward reaction in the cycle, which results in the rigor-like AM state. K1a (MgATP binding) is four times that of rabbit psoas, and K5 (Pi binding) is 0.3 times that of psoas, demonstrating that crossbridges in myocardium bind MgATP more and Pi less than psoas. The rate constants of ATP isomerization (k1b, k-1b), crossbridge detachment (k2, k-2), and crossbridge attachment (k4) steps are generally an order of magnitude slower than rabbit psoas. The reverse attachment step (k-4) is similar to that in psoas, indicating that this step may occur irrespective of the myosin type and possibly spontaneously. The above scheme with the deduced kinetic constants predicts the following crossbridge distributions at 5 mM MgATP2- and 8 mM Pi:AM (3%), AM S (15%), AM*S (14%), Det (50%), AM*DP (6%), and AM*D (12%). The actual number of attached crossbridges was measured to be 51 +/- 4% by the stiffness ratio during activation and after rigor induction, and a strong correlation was seen with the prediction. Our results are consistent with the hypothesis that force generation occurs at the Det-->AM*DPi transition, and the same force is maintained after the release of Pi.

Actins↗
PubMed1993

[Evaluation of the renal function during hypotensive anesthesia induced by nitroglycerin, prostaglandin E1 or nitroglycerin+prostaglandin E1].

We investigated the renal function perioperatively in 32 female patients who underwent mastectomy with hypotensive general anesthesia induced by nitroglycerin (NG), prostaglandin E1 (PGE1) and NG+PGE1. Urine output in PGE1 group (11 patients) was significantly larger than that in NG group (9 patients). It could be attributed to the increase of glomerular filtration rate. On the other hand, the value of beta 2-microglobulin in urine in NG group and the value of N-acetyl-beta-D-glucosaminidase in urine in NG+PGE1 group (12 patient) were abnormal in some patients. These changes were not significant, but the disturbance of renal tubule could be possible. In summary, PGE1 was effective in the maintenance of the renal function.

Adult↗
PubMed1993

Role of sympathetic nervous system in hypotension induced by platelet-activating factor in anesthetized dogs.

This experiment was designed to investigate whether platelet-activating factor (PAF)-induced hypotension in anesthetized dogs produces changes in sympathetic activity in the heart, kidney, liver, and adrenal gland in intact animals (n = 5) and in animals with complete systemic baroreceptor denervation (n = 5). Following intravenous injection of PAF (10 micrograms/kg) in animals with intact baroreceptors, systemic blood pressure fell significantly. However, sympathetic nerve activity in the kidney, liver, and adrenal gland revealed a biphasic pattern: an initial increase (within 30 sec) followed by a progressive reduction below the preinjection level. In contrast to these nerve responses to PAF, only cardiac nerve activity showed an initial and significant increase, and it remained elevated above the preinjection level until the end of the experiment (10 min). In animals with complete systemic baroreceptor denervation, these sympathetic responses to PAF did not differ significantly from the responses in the intact animals. These results indicate that intravenous injection of PAF produces differential control of sympathetic nerve activity in different organs. The contribution of systemic baroreceptors to reflex compensations is minor in PAF-induced hypotension.

Adrenal Glands↗
PubMed1993

Relative contribution of renal nerve and adrenal gland to renal vascular tone during prolonged canine hemorrhagic hypotension.

This study was designed to determine roles of renal sympathetic nerve activity (RNA) and adrenal catecholamines in the changes of renal vascular resistance during prolonged hemorrhagic shock in anesthetized dogs. In animals with intact baroreceptors, hemorrhagic hypotension (40 mm Hg) caused RNA to increase significantly within 1 min after bleeding, followed by a return to baseline within 10 min. Thereafter, a secondary increase in RNA occurred that was followed by a gradual decline towards the baseline level. The renal perfusion pressure (RPP) showed a progressive and significant increase until the end of the experiment. The initial increase in RNA was abolished by complete denervation of the systemic baroreceptors. The initial increase in RPP, which was observed within 10 min after bleeding in animals with intact baroreceptors, was attenuated by the denervation. In animals with bilateral adrenalectomy, RPP still showed an initial increase, but the progressive increase throughout the entire experimental period did not occur. In animals with baroreceptor denervation and bilateral adrenalectomy, RPP did not show any significant changes during the experiment. These results indicate that the initial renal vasoconstrictive response to hemorrhage is regulated by a reflex sympathetic mechanism. In contrast, a late renal vasoconstriction during hemorrhagic hypotension is predominantly evoked by humoral substances such as adrenal catecholamines.

Adrenal Glands↗