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Biomedical subjects

S Nakaya

Publications and source records attributed to S Nakaya.

At least 37 records · Page 2Linked to original sources
PubMed1997

Effects of ovariectomy and estrogen replacement on aorta angiotensin-converting enzyme activity in rats.

We investigated the possibility that physiological doses of estrogen protect against atherosclerotic change produced by changes in vascular angiotensin-converting enzyme (ACE) activity. Rats were ovariectomized, and after 14 days, treated with estradiol-17 beta (0.2 microgram/rat) for 14 weeks. Aorta ACE activity significantly increased in the ovariectomized rats, and decreased following estradiol-17 beta administration to a level not different from proestrous control rats. These results suggest that the lack of estrogenic action increases atherosclerotic change associated with changes in aorta ACE activity and that estrogen replacement therapy reduces the risk of atherosclerotic change associated with the decrease of aorta ACE activity.

Administration, Oral↗
PubMed1997

[Efficacy and safety of sulbactam/cefoperazone for hepato-biliary infections].

We studied efficacy and safety of sulbactam/cefoperazone (SBT/CPT) in the treatment of biliary tract infections in hospitalized patients at 26 hospitals from February 1993 to March 1995. Secondary to dropout, 273 out of 338 patients entered in the study were evaluated, 127 patients with cholecystitis, 132 patients with cholangitis, and 14 patients with liver abscesses. Of these, 93 patients (34.1% had malignancy as an underlying disease. SBT/CPZ had an efficacy of 79.9% (218 patients; excellent: 52, good: 166), with the efficacy in patients with cholecystitis, cholangitis and liver abscess at 89.0% (113 patients), 77.3% (102 patients and 21.4% (3 patients), respectively. A significant difference (p < 0.05) was observed in the efficacy rates of patients with (59 patients [63.4%]) and without malignancy (159 patients [88.3%]). A total of 84 strains were isolated from bile specimens of 53 patients, and the major isolates were Escherichia coli, Pseudomonas aeruginosa and Enterococcus spp. Two or more bacterial strains were isolated simultaneously in 20 patients. Mild or moderate side effect (allergic reaction including rash etc.) were noted in 4 patients (1.18%), and laboratory abnormalities (increased GOT, etc.) were in 16 patients (4.71%) out of the total 338 patients. This study clearly demonstrated that SBT/CPZ retains its excellent clinical efficacy and safety profile, throughout its use over the past decade.

Adolescent↗
PubMed1996

[Diagnosis and clinical manifestations of diarrheal virus infections in Maizuru area from 1991 to 1994--especially focused on small round structured viruses].

Rotavirus (44.7%), adenovirus (5.6%), small round structured viruses such as astrovirus (9.8%) and Norwalk like virus (6.9%) were detected by latex agglutination and reverse transcription polymerase chain reaction amplification from 378 stool samples in an outpatient clinic of Pediatrics in Maizuru area from 1991 to 1994. 70.0% were found from 6 months to 2 years old and 91.0% were detected from January to April. Serotype 1 astrovirus and group 2 Norwalk like virus were mainly found in all serotypes in each virus. Diarrhea, vomiting, nausea, fever, cough and rhinorrhea, and severity of diseases were examined in each case. Fever is significantly found in patients with rotavirus. Sporadic cases with small round structured viruses were recognized in the outpatient clinic of pediatrics.

Adenoviridae↗
PubMed1995

Detection of astroviruses from stool samples in Japan using reverse transcription and polymerase chain reaction amplification.

We developed a reverse transcription and polymerase chain reaction (RT-PCR) method for detecting astrovirus serotypes 1, 2, 3, 5, 6 and 7 (but not serotype 4). Furthermore, we developed the specific primers for detecting serotypes 1 and 2, the most predominant serotypes in the world. Sensitivity of the first PCR with serotype common primers was about 10 times higher than that of enzyme immunoassay with monoclonal antibody (EIA-MAb). Sensitivity of the second PCR with the serotype-specific primers was even higher. The RT-PCR method was useful for detecting astroviruses from clinical samples, especially serotypes 1 and 2.

Base Sequence↗
PubMed1992

Endothelin blocks ATP-sensitive K+ channels and depolarizes smooth muscle cells of porcine coronary artery.

ATP-sensitive K+ channels with a conductance of 30 pS in smooth muscle cells of porcine coronary artery were found to be highly active in the intact cell-attached patch configuration when the pipette contained a physiological concentration of Ca2+ (greater than 10(-4) M). In the inside-out configuration, these channels were activated by extracellular Ca2+ and blocked by cytosolic ATP and glibenclamide. Endothelin applied to the pipette specifically blocked these channels in a concentration-dependent manner in the cell-attached configuration (half-maximal inhibition, 1.3 x 10(-9) M). A K+ channel opener, nicorandil, activated these channels even in the presence of 10(-8) M endothelin. In the whole-cell current-clamp method, the cell membrane was depolarized by endothelin and then repolarized by nicorandil. The membrane depolarization is closely related to contraction of smooth muscle cells. These results suggest that the ATP-sensitive K+ channels are important in controlling the vascular tone of the coronary artery and that endothelin can increase vascular tone by blocking these channels.

Adenosine Triphosphate↗
PubMed1991

Hydration of fibrinogen, fibrin, and fibrin degradation product (FDP) as estimated by nuclear magnetic resonance (NMR) spectroscopy.

The relaxation times (T1 and T2) of water proton in nuclear magnetic resonance (NMR) were measured with solutions containing bovine fibrinogen (Fbg), fibrin degradation products (FDP) and with fibrin-gel (Gel), at varying protein concentrations (0.7-70 mg/ml). Both T1 and T2 declined exponentially with increasing protein concentration. At a protein concentration of 35 mg/ml, the T1 of Fbg, Gel and FDP were 2.32, 2.12 and 2.82 s and the T2 values were 0.35, 0.17 and 0.70, respectively. The relaxation times for the control samples (0.2 M borate buffer) were 3.41 (T1) and 2.28 (T2). When the relaxation rates (the inverse of T1 and T2), R1 and R2 were plotted against the protein concentration, there were positive linear correlations between them. Using the slopes of the plots, the hydration value of each protein was calculated. The hydration value (g of H2O/g of protein) was 0.24 for Fbg, 0.34 for Gel and 0.14 for FDP.

Animals↗
PubMed1991

Mechanisms of absorption of inorganic mercury from rat small intestine. IV: Effect of chelating agents and cysteine on absorption of mercuric chloride in situ and in vitro.

The effects of chelating agents (citric acid, tartaric acid, penicillamine and ethylenediaminetetraacetic acid) and cysteine on the absorption of HgCl2 were investigated in rats. Perfusion of the small intestine showed that the chelating agents and cysteine decreased the absorption of HgCl2 depending on their stability of constants with Hg2+, under the predominant conditions of water absorption and secretion. The difference in absorption of HgCl2 between both conditions was inversely correlated with their logarithmic stability constant values. These agents decreased the transport of HgCl2 through the everted intestinal wall and the uptake of HgCl2 by the intestinal brush border membrane in a similar manner. From these results, it is suggested that the chelating agents and cysteine decrease the absorption of HgCl2 through the pores of the brush border membrane due to the solvent drag effect.

Animals↗
PubMed1991

Effects of hypogastric nerve and sympathetic chain stimulation on the pelvic nerve induced penile erection in the dog.

The effects of electrical stimulation of hypogastric nerve and sympathetic chain on 'electroerection' (penile erection induced by electrical stimulation of the pelvic nerve) were studied in dogs to clarify the physiological roles that these neural inputs may play in producing and/or maintaining penile erection. As an objective parameter of hemodynamics of the penile circulation, the pressure in the corpus cavernosum of the penis was measured. Hypogastric nerve electrostimulation was performed in 24 dogs who had received pelvic nerve stimulation and, therefore, had 'electroerection'. Ten dogs responded to this procedure with an augmentation of 'electroerection', 10 with an attenuation of 'electroerection', and 4 with no appreciable changes. 4 out of the 10 animals who exhibited an attenuation response were then given an alpha 1-adrenergic blocker (prazosin hydrochloride) prior to the electrical stimulation to evaluate the specificity of the effects of the hypogastric nerve stimulation. In 3 of the 4 dogs the attenuation effect was abolished by this treatment and instead an augmentation effect became evident. Sympathetic chain electrostimulation was performed in 6 dogs with 'electroerection'. When applied to the L4-5 interganglionic segment, it produced a biphasic response which consisted of an initial increase followed by a decrease of the intracorporeal pressure. In contrast, stimulation of the L2-3 interganglionic segment produced a monophasic response consisting of only augmentation of the intracorporeal pressure. These data suggested that there might be two groups of fibers in the hypogastric nerve and sympathetic chain which are functioning antagonistically, and that the anti-erectile neural inputs are mediated primarily by the alpha 1-adrenergic system. To examine the sites of penile vasculature where the innervating hypogastric nerve exerts its effects, electrical pelvic/hypogastric nerve stimulations were performed in dogs in whom the inflow blood circulation to the corpora cavernosa was disrupted by arterial ligation and replaced by a constant saline infusion. It appears that the stimulatory input via the hypogastric nerve caused an increased blood flow into the cavernous space due to vasodilation of the inflow blood vessels, and the inhibitory effect occurred mainly due to relaxation of the draining blood vessels with a resultant increase of the blood outflow from the cavernous space.

Animals↗
PubMed1991

Effects of nitroglycerin on ATP-induced Ca(++)-mobilization, Ca(++)-activated K channels and contraction of cultured smooth muscle cells of porcine coronary artery.

Extracellular application of ATP transiently increases the cytosolic-free Ca++ concentration ([Ca++]i) in cultured smooth muscle cells of porcine coronary artery, and this activates large conductance Ca(++)-activated K (Kca) channels. In the present study effects of nitroglycerin (NG) and 4-aminopyridine (4-AP) on [Ca++]; and contraction were studied. 4-AP blocked Kca channels and enhanced the rise of [Ca++]i with oscillation, which led to contraction of the cells. NG activated the Kca channels of 300 picosiemens and inhibited 4-AP-induced contraction and oscillation of [Ca++]i. These results suggest that the vasorelaxant effect of NG involves hyperpolarization of the cell membrane by activating the Kca channels. NG also cause rapid decrease of [Ca++]i during the Ca(++)-mobilization by ATP in Ca-free solution. Similar effects were observed with cyclic GMP, suggesting that the effects of NG on the Kca channels and [Ca++]i were mediated by cyclic GMP.

4-Aminopyridine↗
PubMed1990

Mechanisms of absorption of inorganic mercury from rat small intestine. III. Comparative absorption studies of inorganic mercuric compounds in vitro.

The transport of various inorganic mercuric compounds (HgX2s) was compared in everted intestinal sacs and intestinal brush border membrane vesicles (BBMV) of the rat. The preparations were incubated in a medium containing 10(-4) M HgX2 at pH 5.5, 6.4 or 7.4, respectively. The order of transport through the intestinal wall at each pH (HgOAc)2 greater than HgCl2 greater than Hg(SCN)2 greater than HgBr2 greater than Hg(CN)2) was the reverse order of their stability constants, and an increase in pH tended to increase the transport of HgX2. In the experiment with BBMV, similar results were obtained except for the transport of Hg(CN)2. These results suggest that the extent of transport of a certain HgX2 depends on its stability constant, and that the increase in pH promotes the transport possibly as a result of the conversion of HgX2 to Hg(OH)X and Hg(OH)2.

Animals↗
PubMed1990

Difference in effect of sodium selenite on mercury distributions after duodenal administration of mercuric chloride and mercuric oxide.

To obtain evidence for difference in the absorptive forms of HgCl2 and HgO from duodenum, the Hg distributions after the duodenal administration of HgCl2 and HgO and the effect of Na2SeO3 on their Hg distributions were compared. The Hg concentrations in erythrocytes and liver 2 hr after the administration of HgCl2 were significantly lower and higher than those of HgO, respectively, but their Hg distributions at 3.5 or 5 hr became identical. The administration of Na2SeO3 (intravenously) 2 hr after the administration of HgCl2 and HgO resulted in significant differences in their Hg concentrations in plasma, erythrocytes and kidney at 3.5 or 5 hr. These results suggest that the absorptive form of HgCl2 from the duodenum differs from that of HgO and this difference is a cause for the marked difference in effect of Na2SeO3 on the Hg distributions of HgCl2 and HgO.

Animals↗
PubMed1990

[A case of obstructive jaundice caused by incarceration of pancreatic stones in the ampulla of papilla Vater].

A very rare case of obstructive jaundice caused by the incarceration of pancreatic stones in the ampulla of papilla Vater is reported. A forty-eight-year-old man, who had been taking alcohol daily for 10 years, was admitted to our hospital because of recurrent attacks of upper abdominal pain. Biochemical analysis demonstrated typical pattern of chronic pancreatitis. US, CT and ERCP showed a markedly dilated pancreatic duct and pancreatic calcifications. Cholecystolithiasis, or dilatation of the choledochus was not noted. Conservative treatment was performed under the diagnosis of chronic calcifying pancreatitis for one month. Then, obstructive jaundice, severe epigastralgia, and high fever occurred. Obstructive jaundice with sudden onset and existence of pancreatic stones suggested incarceration of pancreatic stones in the bile duct, and cephalic pancreaticoduodenectomy was performed. The largest pancreatic stone was incarcerated into the ampulla of papilla Vater. Histopathological analysis of the pancreas showed severe chronic pancreatitis. No report of the similar case can be found in the literature. Incarceration of pancreatic stones into biliary system might be very rare, however, should not be forgotten in differential diagnoses of obstructive jaundice in chronic pancreatitis patients.

Ampulla of Vater↗
PubMed1989

Extracellular Ca2+-activated K channel in coronary artery smooth muscle cells and its role in vasodilation.

An extracellular Ca2+-activated K channel (KR channel), having a conductance of 30 pS, was identified in isolated single smooth muscle cells from porcine coronary artery. The KR channel was active at greater than 10(-5) M Ca2+, and was blocked by 4-aminopyridine (4AP). At less than 10(-6) M Ca2+, the KR channel became inactive, but could be activated by 2-nicotinamidethyl nitrate (nicorandil), or by 4-acetamide-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) applied to the pipette solution. It was found that there is a close correlation between the KR channel activity and cell contraction: cells contracted under conditions in which the KR channel became inactive, but were relaxed when the KR channel was active. As the KR channel is highly active in cells in physiological saline, we suggest that it controls the tonus of the coronary artery, as an endogenous dilating factor.

Animals↗
PubMed1989

Quantitative analysis of outflow pathway of corpora cavernosa by pressure flow technique.

Using a pressure flow technique, quantitative analysis of the physiological characteristics of the outflow pathway of the corpus cavernosum was carried out in 19 male dogs weighing 7.5 to 23.0 kg. Pressure flow curves were made on dogs whose pelvic nerve was stimulated electrically and on dogs left unstimulated. When a cyclical change in saline perfusion rate was applied without nerve stimulation, the variable of the intracorporeal pressure showed a large hysteretic loop, indicating that the resistance of the outflow canals to flow was altered by the distension of the sinusoidal space. In dogs whose pelvic nerve was stimulated, the pressure flow curves shifted to the left side in comparison with the outward phase of the pressure flow curve of animals without pelvic nerve stimulation, and this curve piled on the returning phase. No hysteretic relation was observed between the outward and returning phase of the pressure flow curve with pelvic nerve stimulation, but in the detailed analysis, in which the % flow rate was used instead of actual flow rate of saline perfusion, a small hysteretic loop based on the difference of the elasticity of the outlet canals was found. The distension of the corpora cavernosa and the pelvic nerve electrostimulation probably act as the triggers of the same occlusive mechanism in the outflow pathway. The percentage decrease in the blood flow in the outflow canal of the corpus cavernosum induced by the distension of the sinusoidal space or by the pelvic nerve electrostimulation was 69.6 +/- 14.4% (mean +/- SD).

Animals↗
PubMed1989

Factors involved in absorption of organic mercuric compounds from rat small intestine: comparative study with mercuric chloride in situ.

A correlation between absorption of organic mercuric compounds and their molecular weight or lipophilicity was investigated by the perfusion of rat small intestine. The intestine was perfused for 1.0 hr at different osmolarity and different pH with buffers containing 10(-4) M organic mercuric compounds, methyl mercuric chloride (MMC), phenyl mercuric chloride (PMC), p-chloromercuribenzoic acid (PCMB) and p-chloromercuriphenylsulfonic acid (PCMBS). The order of absorption of these compounds at several osmolarities and pHs (MMC greater than PMC greater than PCMB greater than PCMBS) was inversely correlated to their molecular weight. The increase in pH decreased markedly the absorption and n-octanol/water partition coefficient of PCMB, and it decreased scarcely those of MMC, PMC and PCMBS. The order of the coefficients at each pH was as follows; PMC greater than MMC greater than PCMB greater than PCMBS, in disagreement with the order of absorption. These results suggest that the molecular weight is more important factor in the intestinal absorption of organic mercuric compounds than the lipophilicity.

Animals↗
PubMed1988

Tetraethylammonium-induced contraction of rabbit coronary artery.

The vasoactive effect of tetraethylammonium (TEA), a well-known K channel blocker, was tested on helical strips excised from the large epicardial coronary arteries of rabbit hearts. TEA (10 mM) induced transient tetanic contraction of greater amplitude as a result of summation of twitch responses. Occasionally, spontaneous periodic contractions occurred during prolonged exposure to 10 mM TEA. This TEA-induced contraction was abolished in Ca-free solution and suppressed by Ca-entry blockers: nitroglycerin, nicorandil, and isoproterenol, but not by phentolamine or atropine. In strips in which TEA did not induce remarkable contraction, subsequent addition of a subthreshold concentration of ergonovine, serotonin, acetylcholine, ouabain, K-rich solution, or alkalinization of the solution provoked remarkable contraction. These results are consistent with previous reports that TEA induced tetanic contraction as a result of summation of twitch responses due to spontaneous discharge of Ca-spikes in some arterial and tracheal smooth muscle. The results also support the idea that TEA-induced contraction of the rabbit coronary artery is mediated by the same mechanism, i.e., spontaneous Ca-spike discharge.

Animals↗
PubMed1988

Mechanisms of absorption of inorganic mercury from rat small intestine. I. Solvent drag effect on absorption of inorganic mercury.

A correlation of mercury absorption with water absorption was investigated by using the perfusion of rat small intestine with buffers containing 10(-4) M HgCl2. With a decrease in the osmolarity of the buffers or with increases in the sodium ion and urea concentrations in the buffers, absorption of water and mercury and accumulation of mercury in the intestinal tissue increased, and the increases in mercury absorption and accumulation were found to correlate with the increase in water absorption. Both the decrease in osmolarity and the increase in sodium ion concentration increased mercury accumulation in the epithelial cell after the perfusion. But these changes did not alter the mercury distribution in subcellular fractions. The results suggest that the increase in water absorption due to the hyptonicity or the increase in concentration of sodium ion or urea increases the mercury absorption and accumulation in the epithelial cell without change in the distributional pattern of mercury in the cell.

Adenosine Triphosphate↗