Biomedical subjects

Y Imai

Publications and source records attributed to Y Imai.

At least 559 records · Page 31Linked to original sources

PubMed1995

The role of nitric oxide in the baroreceptor-cardiac reflex in conscious Wistar rats.

The role of nitric oxide (NO) in baroreceptor-cardiac reflex function was examined using a NO synthase inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME), in conscious Wistar rats. Mean arterial pressure (MAP) and heart period (HP) relationships were obtained by intravenous injection of graded doses of phenylephrine and sodium nitroprusside (SNP). The baroreflex function was compared before and after L-NAME (10 mg/kg iv), L-NAME (10 mg/kg iv) followed by exogenous NO supplied as SNP (10-20 micrograms.kg-1.min-1 iv), or SNP alone (20 micrograms.kg-1.min-1 iv). To find the effect of changing basal MAP on baroreflex function, the baroreflex function was also examined before and after phenylephrine (8 micrograms.kg-1.min-1 iv) or L-NAME followed by concomitant infusion of SNP and phenylephrine. L-NAME increased basal MAP as well as HP from 104 +/- 1 to 141 +/- 2 mmHg and from 168 +/- 3 to 237 +/- 7 ms, respectively. L-NAME shifted the sigmoid curve in the direction of higher MAP with a significant increase in the gain (gain: control 2.14 +/- 0.15 ms/mmHg, L-NAME 3.70 +/- 0.26 ms/mmHg, P < 0.001). L-NAME together with SNP infusion did not significantly affect the gain, basal MAP, or HP. Infusion of SNP alone shifted the sigmoid curve in the direction of lower MAP but had no significant effect on the gain. An infusion of phenylephrine or L-NAME with concomitant infusion of SNP and phenylephrine increased basal MAP similarly as L-NAME alone did but had no significant effect on the gain.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Enhanced gustatory neural responses to sugars in the diabetic db/db mouse.

Sweet taste sensitivity in a genetic model of diabetes, the db/db mouse, in which a single major gene defect leads to the expression of diabetes and obesity, was studied by examining chorda tympani nerve responses to various taste stimuli, including sugars. The chorda tympani responses to four sugars, sucrose, fructose, glucose, and maltose, in adult db/db mice showed greater relative magnitudes and lower thresholds than those in adult lean mice, but responses to other basic taste stimuli, such as NaCl, HCl, and quinine HCl, were not different in the two groups. Behavioral experiments using a two-bottle preference test demonstrated that taste preference scores for the four sugars at suprathreshold concentrations, except 1.0 M, were higher in db/db than in control mice. Infant mice of 7-9 days of age possessing the genotype db/db also exhibited greater neural responses and lower thresholds for sugars than infant control mice, whereas streptozotocin-induced adult diabetic mice possessing the genotype +/+ did not exhibit larger sugar responses. These findings suggest that the enhanced sugar sensitivities observed in db/db mice are probably determined by a single major gene, db. The db gene may act on a common factor(s) involved in the stimulus-secretion coupling in the pancreatic B cell and the taste cell of db/db mice.

Aging↗

PubMed1995

Hermansky-Pudlak syndrome; a case report with analysis of auto-fluorescent ceroid-like pigments.

The Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disease characterized by a triad of oculocutaneous albinism, accumulation of auto-fluorescent ceroid-like pigments within macrophages, and bleeding tendency due to a storage pool disease of the platelets. We report an autopsy case (39y, male), who died of pulmonary fibrosis and hemorrhage, with analysis of auto-fluorescent ceroid-like pigments (CLP). Pigmented macrophages were seen in almost all organs, especially marked in bone marrow, spleen, liver, colon, lymph nodes and kidneys. Ultrastructurally, CLP was intracytoplasmic electron-dense and -lucent congeries. Histochemical characteristics and auto-fluorescence of CLP showed similarities to ceroid. Substance which revealed brilliant lemon yellow autofluorescent was extracted from homogenized tissue of spleen with chloroform/methanol (2:1), then separated by thin-layer chromatography. The fluorescent substance had an excitation maximum at 360nm and a fluorescence maximum at 440nm, which is the same characteristic as described fluorescent lipid peroxidation products in vitro.

Adult↗

PubMed1995

Long-term results after surgical repair of total anomalous pulmonary venous connection--hemodynamic evaluation of pulmonary venous obstruction with isoproterenol infusion.

To evaluate late pulmonary venous obstruction following surgical repair in patients with total anomalous pulmonary venous connection, which may be disclosed at high cardiac output but not at rest, a hemodynamic study was performed using isoproterenol infusion. The study included 7 patients in NYHA class I, aged from 5 to 12 years (mean 6 years), who had undergone surgical correction in their early infancy (mean 79 days). After a routine catheterization protocol, isoproterenol was infused at a rate of 0.01 microgram/kg per min. On average, cardiac index increased from 4.8 to 8.1 L/min per m2. The pulmonary arterial and wedge pressures following isoproterenol infusion remained normal in all patients, including 1 case with mild pulmonary hypertension. These results suggest that most, if not all, patients with total anomalous pulmonary venous connection repaired in early infancy do not have any hemodynamic impairment if they show no pulmonary venous obstruction within the first 12 months following surgical correction.

Child↗

PubMed1995

Recombinant human erythropoietin stimulates tubular reabsorption of sodium in anesthetized rabbits.

To determine whether recombinant human erythropoietin (rHuEPO) exerts a direct vasoconstrictive effect on renal arteries or affects renal function, we measured renal hemodynamics and renal function during a 30-min intrarenal infusion of rHuEPO in anesthetized rabbits without renal failure. Intrarenal infusion of rHuEPO at a rate of 100 U/min did not alter mean arterial pressure, renal blood flow, or renal vascular resistance, as compared with controls treated with vehicle. There were no significant rHuEPO-associated changes in glomerular filtration rate, filtration fraction, or arterial hematocrit. However, urine volume, urinary excretion of sodium and potassium, and fractional sodium excretion were significantly reduced by intrarenal infusion of rHuEPO. These observations indicate that rHuEPO has no direct effects on mean arterial pressure or renal hemodynamics, but that it stimulates net tubular sodium reabsorption, and reduces urine volume and urinary excretion of sodium and potassium in anesthetized rabbits without renal failure.

Animals↗

PubMed1995

Clinical significance and cost-effectiveness of 24-hour ambulatory blood pressure monitoring.

Ambulatory blood pressure (BP) monitoring as an adjunct to casual/clinic BP measurements is currently used widely for the diagnosis and treatment of hypertension. It has been established that ambulatory BP monitoring is essential to confirm "white coat" hypertension, drug-resistant hypertension, duration of drug action, short-term BP variation, and nocturnal and on-the-job BP levels. It is estimated that approximately 10,000 ambulatory BP monitoring devices are currently used in Japan. That number would increase if 1) a standard algorithm with a theoretical basis to determine BP levels is introduced for ambulatory BP monitoring devices based on cuff-oscillometric method, 2) the reproducibility of ambulatory BP levels is confirmed, 3) reference values for evaluating ambulatory BP monitoring levels are established, and 4) the clinical significance and prognostic value of ambulatory BP monitoring is established. If such problems is settled, the use of ambulatory BP monitoring in the diagnosis and treatment of hypertension would be national health insurance and would improve the prognostic accuracy of evaluating hypertension as well as the cost-effectiveness of screening, diagnosis and treatment of hypertension.

Blood Pressure Monitoring, Ambulatory↗

PubMed1995

Evolution of severe aplastic anemia to myelodysplasia with monosomy 7 following granulocyte colony-stimulating factor, erythropoietin and high-dose methylprednisolone combination therapy.

A 19-year-old man was diagnosed as having severe aplastic anemia and received high-dose methylprednisolone treatment without hematological response. A second course of high-dose mPSL treatment together with granulocyte colony-stimulating factor (G-CSF) plus erythropoietin (EPO) was then started and resulted in trilineage blood cell response. Ten months after the combination therapy thrombocytopenia developed and cytogenetic analysis showed 45,XX,-7, indicating an evolution to myelodysplastic syndrome (MDS) associated with monosomy 7.G-CSF and EPO treatment together with immunosuppression may be an effective therapy in SAA patients, but such a therapy may increase the risk of evolution to MDS.

Adult↗

PubMed1995

Two types of exocytosis evoked by ACh in salivary acinar cells: a morphological observation in perfused submandibular gland of rats.

Exocytosis in the perfused rat submandibular gland was studied using electron microscopy. Stimulation with 1 microM acetylcholine (ACh) evoked exocytosis; i.e., the secretory granules fused with the luminal membrane and their contents were extruded into the luminal space, and watery vacuoles were observed in some acinar cells. Stimulation with 1 mM ACh also induced exocytosis, and led to a marked increase in the number of watery vacuoles. Some watery vacuoles were connected to the lumen and were thus suggested to be formed by the fusion of the granules. On the other hand, no watery vacuoles were observed in the acinar cells during 1 microM isoproterenol stimulation, while isoproterenol induced exocytosis and led to a marked decrease in the number of intracellular granules. Thus, the watery vacuolation is a characteristic response to the cholinergic stimulation, is dependent on the ACh dose in the submandibular acinar cells, and is regarded as a kind of exocytosis.

Acetylcholine↗

PubMed1995

The mechanism responsible for hypertension in a patient with Guillain-Barré syndrome.

We report a case of hypertension associated with Guillain-Barré syndrome. In this case, the circadian variation of blood pressure was interrupted. Examination of neurohumoral factors revealed a hyperactive sympathetic nervous system and an increase in plasma renin activity. Clonidine, which acts centrally to inhibit sympathetic outflow, did not suppress serum norepinephrine or epinephrine. These observations suggest that autonomous hyperactivity of the efferent pathway of the sympathetic nervous system may cause the sustained hypertension throughout the day in this case.

Adult↗

PubMed1995

Pressor effect of recombinant human erythropoietin: results of ambulatory blood pressure monitoring and home blood pressure measurements.

We investigated whether treatment of anemic hemodialysis patients with a low dose of recombinant human erythropoietin (erythropoietin) for a short period would increase their blood pressure. Ambulatory blood pressure monitoring and home blood pressure measurements were used to detect minute increase in blood pressure. Thirty-two patients with a hematocrit of 25% or less received erythropoietin at the dose of 4500 IU/week, by the intravenous route for 8 weeks. Erythropoietin increased the hematocrit from 20.9 +/- 2.1 to 26.2 +/- 2.1%. Erythropoietin elevated mean ambulatory blood pressure by 5 mmHg or more in two-thirds of patients (n = 20; pressor group), while it elevated home mean blood pressure by 5 mmHg or more in one-third of patients (n = 11). An increase in clinic mean blood pressure by more than 5 mmHg was observed only in one-fourth of patients (n = 7). Circadian variation of blood pressure (nocturnal fall and diurnal rise) had been attenuated in the patients of the pressor group before erythropoietin treatment and erythropoietin decreased the nocturnal fall of blood pressure further more. Erythropoietin elevated nocturnal blood pressure more than diurnal blood pressure. Therefore, the increase in blood pressure induced by erythropoietin was detected more reliably by ambulatory blood pressure monitoring. There was no relation between the change in hemoglobin concentration and the increase in ambulatory blood pressure induced by erythropoietin. Erythropoietin tended to decrease cardiac output and plasma volume while it increased total peripheral resistance. It also decreased plasma norepinephrine and vasopressin levels but did not affect other humoral factors. Although the pressor effect of erythropoietin treatment for 8 weeks at the dose of 4500 IU/week was not evident on clinic blood pressure measurements, any increase in blood pressure determined by ambulatory blood pressure should be treated carefully to reduce the risk of a cardiovascular complication in patients receiving hemodialysis.

Aldosterone↗

PubMed1995

Phosphoric acid tooth conditioner containing copper salt for bonding MMA-TBB resin.

The purpose of this study was to examine the feasibility of a conditioner for treating enamel and dentin simultaneously for MMA-TBB resin bonding. Various phosphoric acid solutions containing copper salts were prepared and used as conditioners before bonding MMA-TBB resin to bovine teeth. Their effects on the surface morphology and bonding were studied by scanning electron microscopy and tensile bond strength testing. The concentrations of phosphoric acid as well as copper salts therein affected the bond strength to dentin. Ten percent phosphoric acid containing 3% copper (II) chloride appeared optimal for treating dentin and was significantly effective in improving the bond strength compared with phosphoric acid alone. This conditioner was applicable also to enamel without any adverse effect on the bond strength. Therefore, enamel and dentin may effectively be treated simultaneously with this conditioner before bonding of MMA/TBB-based resin.

Acid Etching, Dental↗

PubMed1995

Effects of a barbituric acid/CuCl2 initiator system on resin adhesion to dentin.

The effectiveness of a barbituric acid/copper (II) chloride initiator system in dentin was examined in terms of the effects of barbituric acid structures and dentin conditioners on bond strength. Curing times and tensile bond strengths to bovine dentin were measured for PMMA/MMA resins in conjunction with initiators consisting of a combination of CuCl2 and four barbituric acids having different substituents. The dentin surfaces were treated with six conditioners consisting of 10% citric acid or phosphoric acid with or without 3% FeCl3 and CuCl2. Among the four barbituric acid systems studied, curing times varied significantly (p < 0.002), but the bond strengths to dentin, conditioned with 10% citric acid containing 3% CuCl2, did not (p > 0.60). The dentin conditioners influenced bond strength significantly (p < 0.02). The phosphoric acid based conditioners produced higher bond strengths than those based on citric acid. The bond strengths obtained under optimal conditions were comparable to those reported for MMA-TBB resin. Thus, the resin applied using the barbituric acid/CuCl2 system worked as well as one of the most effective bonding resins available.

Acid Etching, Dental↗

PubMed1995

Usefulness of color Doppler flow imaging in differential diagnosis of multilocular cystic lesions of the kidney.

Color Doppler flow imaging was carried out in 10 multilocular cystic lesions of the kidney. These consisted of three renal cell carcinomas, three hemorrhagic renal cysts, one benign multilocular cystic nephroma, two infected renal cysts, and one benign multilocular renal cyst secondary to von Hippel-Lindau disease. In the patients with renal cell carcinoma, color signals were obtained at the septum and in the solid component within the lesions. A pulsatile wave with a large maximum flow velocity and a high PI value was obtained in two of them. In one of the patients with hemorrhagic renal cysts, color signals were obtained at the region of the septum. In the other benign lesions, however, color signals were obtained only at the peripheral margin, and the flow waveform in these cases was identical to the waveforms found in the interlobar arteries. This study suggested that color display in the lesion well reflects its vascularity in patients with multilocular cystic renal diseases and that measurement of the systolic maximum flow velocity by fast Fourier transform analysis is useful for the differential diagnosis of malignant versus benign lesions.

Adolescent↗

PubMed1995

Magnetic resonance imaging following microwave thermotherapy, laser ablation and transurethral resection in patients with BPH.

Morphologic changes in hyperplastic prostate tissue following three different treatments were analysed by MRI using an endorectal surface coil. In cases treated by TUMT, the MRI findings of the prostate showed hemorrhagic necrosis, which was absorbed in 12 weeks, and a widened prostatic urethra. In cases treated by laser ablation, the thermal effect went deep, causing necrotic changes, and it took more than 8 weeks for the tissue to be shed and re-epithelization completed. In TURP, degenerative changes were seen only near the surface following mass reduction of the hyperplastic tissue, and the capsule shrinkage resulted in normalization of the prostatic urethra. It is suggested that improvement of the other parameters, such as IPSS and peak flow, in patients with obstructive BPH basically depends on these morphologic changes shown by MRI.

Aged↗

PubMed1995

The equine pericardial valved conduit and current strategies for pulmonary reconstruction.

In the period from 1976 to February 1995, 268 cases underwent extracardiac conduit repair (ECR), or direct reconstruction of the pulmonary artery. Of these 268 patients, 64 had a valved Dacron conduit, 143 received handmade valved equine pericardial conduits (Xenomedica), 24 had autologous fresh pericardial conduits, and 37 cases had pulmonary artery reconstruction by direct anastomosis without the use of tubular conduits. Hospital mortality in each group showed gradual improvement chronologically; 20.3% in the Dacron group, 9.8% in the equine conduit group, 4.2% in the autologous pericardial conduit group, and 5.4% in the direct anastomosis group, and the mortality rate was significantly higher in the Dacron group (P = .0261). Late death was seen in 7 of 51 (13.7%) in the Dacron group, 12 of 129 (9.3%) in the equine group, 1 of 23 (4.3%) in the autologous pericardial conduit, and none in the direct anastomosis group (P = .1263). Actuarial survival rates of the patients in the Dacron and equine conduit groups showed better survival in the latter without statistical significance: 75.0%, 83.2% at 5 years, and 69.7%, 80% at 10 years, respectively. However, actuarial survival rates among short-term survivors in the Dacron and equine conduit groups remained the same: 87.5%, and 88.7% at 10 years. Our current strategy in this entity is autologous tissue reconstruction of the pulmonary artery either by direct anastomosis or autologous pericardial conduit. Of 30 cases with transposed great arteries or truncus arteriosus, direct anastomosis could be performed in 19 (63.3%) since January 1992.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗

PubMed1995

[A case of visceral ischemia associated with acute type IIIb aortic dissection].

The case was a 61-year-old man who was transported to our hospital with complaining of severe chest and back pain of sudden onset and diagnosed as acute type IIIb aortic dissection. Inspite of intensive medical treatments, severe abdominal pain with abdominal distension and progressive metabolic acidosis appeared at around 11 hours after admission. Aortogram revealed obstruction of both superior and inferior mesenteric arteries suggesting visceral ischemia associated with acute type IIIb aortic dissection. Emergent operation consisting of bypass grafting for the superior and the inferior mesenteric arteries with saphenous vein, partial resection of small intestine, left hemicolectomy and construction of artificial anus was immediately carried out. The patient had no particular trouble after the operation and returned to the previous job.

Acute Disease↗

PubMed1995

Immunohistochemical analysis of dendritic/Langerhans cells in thyroid carcinomas.

Recent immunohistochemical investigations of thyroid carcinomas have revealed that dense infiltration by dendritic cells (DCs) is correlated with a favorable prognosis. The present study was done to clarify the frequency and characteristics of DC infiltration in thyroid carcinomas, and also cytokines associated with DC maturation and migration. Compared with follicular carcinomas, papillary carcinomas contained significantly higher numbers of DCs, interleukin (IL)-1 alpha- and tumor necrosis factor (TNF)-alpha-positive cells, and cells positive for two TNF-alpha receptors (p60 and p80). The centers of cancer nodules had large numbers of CD1a- and CD1c-positive DCs suggesting that they were Langerhans cells, whereas the periphery of cancer nodules and inflamed surrounding thyroid tissues had numerous CD1b-, L-M2- and X-12-positive DCs suggesting that they were interdigitating cells, as well as many CD1a- and CD1c-positive DCs. Neoplastic cells of papillary carcinomas were more frequently reactive with antibodies against IL-1 alpha and TNF-alpha than those of follicular carcinomas, and a good correlation between their immunoreactivity and the frequency of DCs was found. These data suggest that cytokines such as IL-1 alpha and TNF-alpha released from carcinoma cells and cells in the cancer stroma may regulate the infiltration and maturation of dendritic/Langerhans cells, and that this process may be better preserved in papillary than in follicular carcinomas.

Adenocarcinoma, Follicular↗

PubMed1995

[A successful circulatory assist in acute left heart failure after a rapid two-stage arterial switch operation].

A 6-month-old female with transposition of the great arteries with intact ventricular septum successfully survived with the aid of a circulatory assist device for acute left heart failure after rapid two stage-arterial switch operation (ASO). The interval between pulmonary artery banding and ASO was 9 days. Left heart failure appeared immediately after ASO, so we started the circulatory assist with a centrifugal pump. The left ventricular function gradually recovered. After 43 hours assisted circulation, she was successfully weaned from the pump. Subsequent recovery was uneventful and the patient was discharged from the hospital on the 40th postoperative day. In case of acute left heart failure after ASO due to sudden changes in the left ventricular afterload, adaptation of the left ventricle can be expected by a relatively short period of circulatory assist with centrifugal pump.

Acute Disease↗