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Biomedical subjects

Y Imai

Publications and source records attributed to Y Imai.

At least 829 records · Page 46Linked to original sources
PubMed1991

A quantitative analysis of hemodynamic effects of the right ventricle included in the circulation of the Fontan procedure.

BACKGROUND: Right heart hemodynamics were analyzed with a catheter-mounted velocity meter in seven patients after direct atrioventricular anastomosis for Fontan procedure (RV group) and were compared with those obtained in eight patients after direct atriopulmonary anastomosis (RA group). METHODS AND RESULTS: In the RV group, cardiac output was 2.7 +/- 0.6 l/min/m2; mean right atrial and pulmonary artery pressures were both 13 +/- 3 mm Hg; mean pulmonary artery wedge pressure was 7 +/- 5 mm Hg; left ventricular end-diastolic volume, determined angiographically, was 129 +/- 40% of normal; and its ejection fraction was 0.50 +/- 0.09. In the RA group, data were similar to those of the RV group except that right heart pressure were lower in the RV group, which was related to the preoperative condition of the pulmonary circulation. In the RV group, the fraction of ventricular forward flow of the total forward flow in the main pulmonary artery ranged from 0.21 to 0.46 and was not correlated with cardiac output or with any other parameter. The backward flow into the inferior vena cava at ventricular systole was greater than the atrial flow in two patients in whom cardiac output was less than 2.2 l/min/m2, whereas caval backward flow at atrial contraction was greater than ventricular flow in the other five patients, of whom four had a cardiac output greater than 3.1 l/min/m2. CONCLUSIONS: We conclude that the inclusion of right ventricle in the circulation of the Fontan procedure does not necessarily improve overall hemodynamics in most patients.

Adult↗
PubMed1991

Importance of polymerization initiator systems and interfacial initiation of polymerization in adhesive bonding of resin to dentin.

Although various adhesive resins for dentin have been developed and used clinically, most attention has been directed to adhesion-promoting monomers and pre-treatment agents. The role of polymerization initiator systems in bonding has been overlooked. The purpose of this work was to study the role of initiators from the viewpoint of interfacial initiation of polymerization in dentin bonding. The bond strength between dentin and methyl methacrylate resin was significantly improved by a possible interfacial initiation with (1) the combination of ferric chloride, adsorbed onto dentin, and oxidized tri-n-butylborane (TBBO) and (2) the addition of tertiary butyl peroxymaleic acid (containing a carboxylic acid group, which has an affinity with dentin) to chemically- or light-activated initiator systems.

Acid Etching, Dental↗
PubMed1991

Effect of a high dose of cimetidine on biliary, intestinal and fecal bile acids in rats.

Effect of an intraperitoneal injection of cimetidine at a daily dose of 160 mg/kg for two weeks on biliary lipid secretion, fecal excretion of bile acids and intestinal bile acids was studied in rats. Bile flow, biliary lipid secretion and fecal excretion of bile acids remained unchanged, while the pool size of bile acids decreased by cimetidine treatment. Chenodeoxycholic acid increased with a concomitant decrease of beta-muricholic acid in the biliary bile acid composition of cimetidine-treated rats.

Animals↗
PubMed1991

Influence of heat stimulation on the amount of calcitonin gene-related peptide and neurokinin A in the subcutaneous space of the rat hind instep.

The release of tachykinins and calcitonin gene-related peptide (CGRP) into subcutaneous perfusates was investigated. Immersion of the hind paw of rats in water at 47 degrees C for 30 min led to a marked increase of immunoreactive CGRP (iCGRP) release as well as immunoreactive substance P release, but no detectable increase of immunoreactive neurokinin A release. Neonatal pretreatment with capsaicin or section of the sciatic and the saphenous nerves significantly inhibited the heat stimulation-induced release of iCGRP.

Animals↗
PubMed1991

Key role of complement activation and platelet-activating factor in exudate formation in zymosan-induced rat pleurisy.

Involvement of complement and platelet-activating factor (PAF) in zymosan-induced rat pleurisy was examined. Only a very low level of complement remained in the exudate at 1-5 hr after zymosan injection, indicating that complement activation had occurred during this period in the pleural cavity. When rats were injected with cobra venom factor (CVF) 24 hr prior to the zymosan injection to deplete complement, the exudate volumes at 0.5 and 5 hr after zymosan injection were significantly reduced. Furthermore, combined treatment with CVF and CV-6209, an antagonist of PAF, also significantly suppressed the exudation but to no further extent than the suppression by CVF alone, suggesting that the level of complement depletion achieved was sufficient to halt PAF synthesis/release. To see if complement activation is involved in PAF production, we examined the PAF production by resident leukocytes in response to zymosan in vitro. When pleural leukocytes were stimulated with zymosan in the presence of rat serum, PAF-like activity both in the medium and in the cellular fraction increased. If the serum was heat inactivated, no PAF-like activity was detected. These results suggest that initial activation of the complement system may occur in the pleural cavity by zymosan and that the activated complement may then stimulate the production of PAF, which in turn elicits the exudate.

Animals↗
PubMed1991

Paradoxical prolactin response to growth hormone-releasing hormone in a patient with hyperprolactinemia and empty sella.

In a 30-year-old woman with amenorrhea due to hyperprolactinemia, serum PRL increased to twice the basal amount in response to growth hormone-releasing hormone (GHRH). Roentgenological studies revealed no pituitary adenoma but empty sella. Bromocriptine therapy normalized serum PRL and made the paradoxical response to GHRH disappear. The paradoxical response did not occur in any of eight other patients with hyperprolactinemia due to prolactinoma. Although this case is rare, GHRH stimulates PRL as well as GH release remarkably in some cases with hyperprolactinemia without a GH-producing tumor.

Adult↗
PubMed1991

Population study of ambulatory blood pressure in a rural community in northern Japan.

A cross sectional survey was performed on ambulatory blood pressure (ABP) in a rural community in northern Japan. ABP was measured in 468 participants (148 men and 320 women, or 27.3% of the less than or equal to 20 year-old population in the study region) with a Colin ABPM 630, an ABP monitoring system. ABP was determined every 30 min for 24 hr. All-day average of 24 hr ambulatory systolic, (SBP) and diastolic BP (DBP) in these subjects were 121.5 +/- 11.8 and 71.7 +/- 8.0 mmHg (mean +/- S.D.), respectively. Ambulatory SBP and DBP levels increased gradually with an increase in age in both sexes. The age dependent increase in SBP was, however, extremely small in men compared with that in the casual SBP of the ordinary Japanese reported. The minimal age-dependent increase in ambulatory SBP in men reflects a high ambulatory SBP in those below 50 years-old as well as a minimal increase in ambulatory SBP in those over 50. Ambulatory SBPs in women were lower than those in men until they reach the age of 50 years. Ambulatory SBP levels in men and women were similar after their 60's. Ambulatory DBP tended to fall or remain at the same level after 60 years-old. Thus, a greater pulse pressure was observed in elderly subjects. Casual SBP and DBP in the ordinary Japanese were significantly higher than the daytime average ambulatory SBP and DBP in all age groups of both sexes in the population except those in their 20's. The results suggests that ABP has different clinical characteristics and may have a different clinical significance from casual BP.

Adult↗
PubMed1991

Dose effects of acetylcholine on the cell volume of rat mandibular salivary acini.

The effects of acetylcholine (ACh) on the cell volume of the isolated rat mandibular acini were studied stereologically using video-enhanced contrast optical microscopy. The lengths of major and minor axes of the acini were measured in the successive video images, from which the relative volume change was estimated. ACh induced a rapid shrinkage of the acinar cell to reach minimum volume within 1 min. Simultaneously, the acinus and acinar clump shrunk in the same proportion as the acinar cell. The initial volume decrease induced by ACh was dose dependent: 0.92 at 10(-8) M, 0.91 at 10(-6) M, 0.77 at 10(-5) M, 0.78 at 10(-4) M, and 0.75 at 10(-3) M (the relative volume compared with the resting control). During sustained stimulation by ACh for 3 min, the volume of acinar cell remained at the plateau level at concentrations lower than 10(-5) M ACh, whereas the volume increased by 0.1-0.15 at concentrations higher than 10(-4) M ACh. The dose-dependent manner of the cell volume coincided with the fluid secretion measured in the isolated perfused gland. The findings on the dose effects of ACh are discussed in connection with the intercellular communication and the movement of electrolytes.

Acetylcholine↗
PubMed1991

[Urethral indwelling catheter, intermittent self-catheterization and urinary infection].

Once a catheter has been passed into the bladder without contamination, there are several possible routes of subsequent infection during drainage period, such as: 1. Entry of bacteria alongside the catheter in the urethra. 2. Introduced bacteria adhered easily to the indwelling catheter and drainage system and colonized. 3. The catheter tip is covered rapidly by various nutrient materials which becomes a good culture medium of stuck bacteria, which is a supply source of bacteria into the bladder urine. 4. Although the motile bacilli ascend very slowly through the stagnant tube and no bacteria ascend against a slowly moving column, rapid transport of organisms occurs in the swirling fluid caused by the passage of rising air bubbles. 5. Continuous urethral catheter drainage permits an average residual urine volume of 7.3 ml. 6. The catheter destroys the antibacterial defense mechanisms of the urinary bladder. The reasons why in many cases of intermittent self-catheterization (CID) urine becomes sterile despite non-sterile procedure, are as follows. In addition to that CIC has none of the disadvantages of the indwelling catheter, it improves the vesical defense mechanisms deteriorated by high pressure voiding. The number of bacteria reintroduced during catheterization is relatively small and they can be eradicated by usual scheduled catheterization within 4-5 hours without residual urine. CIC must be started before trabeculation or diverticuli are formed, in which bacteria remain. Actual determination of residual urine volume after catheterization will help to prescribe a rational program of CIC.

Bacteria↗
PubMed1991

Flow cytometric measurement of NK cell cytotoxicity.

A simple and fast method to measure the natural killer (NK) cell cytotoxicity has been established. In our novel assay, following the incubation of K562 target and effector cells, the cells were stained with FITC-conjugated anti-transferrin receptor (CD71) mAb. The K562 targets alone were labeled with anti-CD71 mAb, since CD71 is highly expressed on K562 cells but not on mononuclear cells. The fluorescence intensity of CD71 on K562 cells were analyzed using flow cytometry, and the cytotoxicity was evaluated. In our assay, designated as a "CD71 assay", no spontaneous release of anti-CD71 mAb was observed from labeled K562 cells and living K562 cells were able to be divided from dead K562 cells. The data obtained by this assay was well correlated with that by the standard 51Cr-release assay as well as the C-FDA assay. In addition, the CD71 assay is a safe and simple analytic procedure since no isotope is required.

Antigens, CD↗
PubMed1991

Effect of protein kinase inhibitors on the proliferation of leukemic cells stimulated by granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor or interleukin-3.

The effects of the inhibitor for protein kinase A or C, or tyrosine kinase (H-8, staurosporine, or genistein, respectively) on the proliferation of leukemic and normal bone marrow cells stimulated by granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), or interleukin-3 (IL-3) were studied using the MTT assay. These inhibitors suppressed the proliferation of leukemic and normal bone marrow cells in a dose-dependent manner. Although the suppressive effect of each inhibitor on cell proliferation was varied in each instance, the effects were almost similar whichever CSF was added. A significant difference was not recognized between leukemic and normal bone marrow cells in terms of sensitivity to these inhibitors. The data indicate that protein kinase inhibitors have an inhibitory effect on leukemic and normal hematopoietic cell proliferation and that further studies are required to determine if this effect is due to the inhibition of protein kinases acting as the second messenger of CSFs.

Cell Division↗
PubMed1991

[Effects of morphine on cutaneous blood flow and substance P release evoked by electric stimulation of rat sciatic nerve].

Electric stimulation of the rat sciatic nerve containing sensory afferent fibers produced an increase in cutaneous blood flow. Morphine (10, 30 mumol.kg-1 ia infusion) inhibited the electric stimulation-induced increase of the cutaneous blood flow velocity, and its effect was antagonized by naloxone (2 mg.kg-1 ip). In order to investigate the cause of this effect, we determined immunoreactive substance P (iSP) levels in the sc perfusate of hind paw. We found that electric stimulation of the sciatic nerve led to a significant increase of iSP release into the sc perfusate. Morphine (30 mumol.kg-1 ia infusion) inhibited the electrical stimulation-induced release of iSP, and this effect was completely antagonized by naloxone (2 mg.kg-1 ip). These result suggest that morphine-induced inhibition of the electrical stimulation-evoked increase in cutaneous blood flow could result from inhibition of the release of SP from peripheral sensory nerve endings.

Animals↗
PubMed1991

[Fontan type procedure in patient with borderline hemodynamics: using a temporary R-L shunt in early postoperative period].

Fontan type procedure was successfully performed to a 14-year-old patient with borderline hemodynamics using a temporary R-L shunt in early post operative period. Preoperative diagnosis was DORV (ILD), small RV, PS, ASD, juxtaposition of atrial appendages and post bilateral B-T shunts. Preoperative catheterization studies showed low PARI but insufficient pulmonary arterial size (PA-index 220). In the Fontan procedure, RA was partitioned obliquely with a composite patch of xenograft and Dacron velour. A 5.5 mm hole was created only in xenograft to allow a temporary R-L shunt. During rewarming period, systemic pressure hovering around 60 mmHg with 10 micrograms/kg/min of dopamine and dobutamine. Then a R-L shunt was created by a side to side anastomosis between the appendages with the orifice diameter of 10 mm, followed by a rise in the systemic pressure up to about 80 mmHg. One post operative day, a readjustable occluder was applied at the site of appendage anastomosis to control R-L shunt flow. According as CVP decreased, the occluder was tightened up step by step. Finally, the occluder was fully tightened up in 10 post operative days. This experience suggests that a temporary R-L shunt in early post operative period may be applicable in patient with borderline hemodynamics for Fontan type procedure.

Adolescent↗
PubMed1991

[The treatment of hypertensive patients with renal insufficiency--a comparison of the blood pressure management in patients with diabetic nephropathy and patients with hypertensive nephropathy].

It is well known that hypertension (HT) is frequently accompanied with diabetic nephropathy (DN) and that HT contributes to progression of DN. Thus, proper anti-hypertensive therapy is required in hypertensive patients with DN. However, there is so far no consensus of optimal blood pressure (BP) level to maintain the renal function in these patients. In order to evaluate the optimal BP level in the patients with renal insufficiency, we investigated the relation between BP and renal function in 15 DN patients with HT (aged 56.9 +/- 11.7 years at the first medical examination; 6 male and 9 female, total 117 patient-years) and 20 patients with hypertensive nephropathy (aged 44.3 +/- 13.0 years at the first medical examination; 17 male and 3 female, total 207.5 patient-years) as the control, who receive antihypertensive therapy for more than 4 years as outpatients at the second department of internal medicine of Tohoku University Hospital between 1974 and 1990. During this period 7 patients with DN came to receive hemodialysis therapy 2 to 6 (average 3.8 +/- 1.3) years after the first medical examination. As a result, in patients with hypertensive nephropathy, there was a tendency to show that the lower the mean BP was, the better the renal function. On the contrary, in DN patients there was an optimal mean BP (MBP) range; i.e, when MBP was controlled in this range, the deterioration rate of renal function was delayed, while deviation of MBP from this range made the renal function worse (p less than 0.01). However, this range varied with the serum creatinine (SCr) concentration level.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Cepstral analysis of ultrasound in chronic liver disease--a preliminary study in the non-invasive evaluation of structural change.

To evaluate the morphological changes in chronic liver disease non-invasively we used the frequency-domain analysis of ultrasound. We assumed that liver tissue is a collection of semi-regularly arrayed small scatterers of ultrasound. We applied cepstral analysis to ultrasonic waveforms and evaluated the periodicity of scalloping of the power spectrum, caused by an interference effect among liver scatterers of a given spacing. In a phantom experiment, we could correctly measure the space among scatterers of a phantom consisting of a regularly spaced distribution of nylon filaments. In an experiment involving a freshly excised porcine liver, the distribution of the space among scatterers (SAS) determined on cepstral analysis reflected the size distribution of the hepatic lobules. In a human study, two statistical parameters, mode and kurtosis, were determined from the distribution of the SAS for each patient. In a previous study, we collected ultrasonic data during peritoneoscopy with a 10 MHz transducer directly contacting the liver and showed that we could evaluate morphological changes in chronic liver disease using cepstral analysis. In the present study, we obtained data in two ways: with a 3.5 MHz transducer through the abdominal wall and with a 10 MHz transducer directly contacting the liver during peritoneoscopy. The mode and kurtosis of the SAS obtained with the 3.5 MHz transducer were both well correlated with the mode and kurtosis of the SAS obtained with the 10 MHz transducer. These results suggest that we can evaluate morphological changes in chronic liver disease non-invasively.

Animals↗
PubMed1991

Fracture behavior of dental composite resins.

Fracture toughness (KIC), critical stress intensity factor, and bending strength of 3 types of commercially available dental composite resins (macrofilled, hybrid and microfilled type) were determined using three point bend specimens. Acoustic Emission (AE), which is the generation of elastic wave due to the release of energy from the localized sources in material, was also detected during the fracture toughness test. Fracture surfaces were examined by scanning electron microscope. The fracture toughness values, AE patterns, and the nature of fracture surface were analyzed to understand fracture behavior of dental composite resins and fracture mechanism for each dental composite resin are proposed.

Acoustics↗