Search PubMed⌕ Search

Biomedical subjects

R Nakayama

Publications and source records attributed to R Nakayama.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Atrial late potential (ALP) by P wave-triggered signal-averaged electrocardiogram].

Late potentials, possibly representing fractionated electrograms recorded directly from slowly conducting cardiac tissue, can be detected by signal averaged ECG (SAECG) from the body surface noninvasively. Ventricular late potential, recorded with SAECG, is a good predictor of ventricular tachyarrhythmias. Analogously, SAECG triggered by P wave has recently been proposed determining atrial late potential (ALP), possibly related paroxysmal atrial fibrillation. ALP is analyzed by the time domain or frequency domain method. In the former, the prolongation of filtered P duration is an index of ALP. The results obtained by FFT analysis in the latter are controversial, and thus additional study will be required to confirm their meaning and significance.

Atrial Fibrillation↗
PubMed1995

[Atrial late potential by P wave-triggered signal-averaged electrocardiogram and paroxysmal atrial fibrillation].

Atrial fibrillation (AF), which is rather a common disease has a high risk of developing systemic embolism and stroke. Accordingly it can be significant for us to predict a patient at risk for AF during sinus rhythm Recently signal averaged ECG triggered by P wave has been expected to detect atrial late potential (ALP), which is thought to coincide with fractionated ECG significantly recorded directly from atrial muscle of a patient with paroxysmal AF. Although many time-domain ALP indices have been proposed, those excepting filtered P duration remain controversial with their diagnostic criteria having not yet been established, many studies agree as to the prolongation of filtered P duration, as observed for patients with AF. Although, also recently, frequency domain method has been applied to ALP for FFT analysis with the view of detecting ALP possibly undetectable by time domain method, no results better than the above method have been obtained, and further examination is hoped for.

Atrial Fibrillation↗
PubMed1994

Evidence for production of platelet-activating factor by yeast Saccharomyces cerevisiae cells.

Various yeast strains were screened for platelet-activating factor (PAF) production. High PAF production was found mainly in the strains of Saccharomyces genus. Yeast PAF showed a typical platelet aggregation pattern, which was inhibited by specific PAF antagonists, such as CV-3988, CV-6209 and L-652731. The main molecular species of yeast PAF were identified as 1-palmitoleoyl-, -palmitoyl-, -oleoyl- and -stearoyl-2-acetyl-sn-glycero-3-phosphocholines (16:1, 16:0, 18:1 and 18:0 acylPAFs) and 1-hexadecenyl- and hexadecyl-2-acetyl-sn-glycero-3-phosphocholines (16:1 and 16:0 PAFs), by mass spectrometry. PAF formation in yeast cells increased at the middle stationary phase of growth.

Chromatography, Thin Layer↗
PubMed1994

The routine use of Rh-negative reagent red cells for the identification of anti-D and the detection of non-D red cell antibodies.

BACKGROUND: Before 1987, fewer than 50 patients per year at the authors' laboratory had a positive antibody detection test due to antepartum Rhesus immunoprophylaxis. However, after 1987, a marked increase was observed in the number of patients who had received Rh immune globulin (RhIG) during pregnancy as part of routine antepartum Rh immunoprophylaxis. In anticipation that an increased use of RhIG during pregnancy would increase the number of patients in whom anti-D was detected by this laboratory, a protocol was developed to abbreviate the process required to identify anti-D. Although this protocol was adopted primarily to address an anticipated increase in antenatal RhIG usage in women, it was also applied to alloimmunized Rh-negative males. STUDY DESIGN AND METHODS: When an Rh-negative patient (male or female) had a reactive screening test for unexpected antibodies and met certain other criteria, the patient's serum was tested with a three-vial set of Rh-negative reagent red cells (Rh-negative screening RBCs), instead of with panels of typed RBCs (panel RBCs), for the identification of anti-D or the detection of non-D antibodies. If the serum under test did not agglutinate or hemolyze Rh-negative screening RBCs, anti-D was identified and no further testing was performed. If the serum agglutinated or hemolyzed Rh-negative screening RBCs, conventional testing with panel RBCs was done to determine the antibody specificity. RESULTS: Rh-negative patients (n = 1174) who had reactive screening tests for unexpected antibodies were tested with Rh-negative screening RBCs; 1079 were found to have anti-D as a single antibody. Seven of these patients subsequently developed a non-D alloantibody, after transfusion or pregnancy, and one patient had anti-C that escaped detection at the time of initial testing with Rh-negative RBCs (a false-negative result). Ninety-two patients had anti-D in combination with a non-D antibody, and three patients had a non-D antibody but not anti-D. Use of the anti-D identification protocol actually reduced the laboratory workload by 176 College of American Pathologists workload units per month, in spite of a marked increase in the number of patients in whom anti-D was detected. No hemolytic transfusion reaction was attributed to the abbreviation of anti-D identification. CONCLUSION: The identification of anti-D may be abbreviated without jeopardizing patient safety. Such a protocol can reduce laboratory workload and might be particularly appealing to health care facilities that perform antibody detection testing on large numbers of Rh-negative pregnant women, especially if antepartum RhIG is administered routinely.

Erythrocytes↗
PubMed1994

Critical PQ interval for the appearance of diastolic mitral regurgitation and optimal PQ interval in patients implanted with DDD pacemakers.

Diastolic mitral regurgitation (MR) may be induced by prolonging atrioventricular (AV) delay, and a significant negative correlation has been described between the critical PQ interval for the appearance of diastolic MR and pulmonary capillary wedge pressure (PCWP) in patients with DDD pacemakers. We report the relationship between the critical PQ interval for the appearance of diastolic MR and the optimal PQ interval in 11 patients (69.1 +/- 12.6 years). Cardiac output (CO) and PCWP were measured by Swan-Ganz catheter and transmitral blood flow was recorded by pulsed-Doppler echocardiography. AV delay was prolonged stepwise by 0.025 seconds starting from 0.065 seconds. The pacing rate was fixed at 70 beats/min. CO was highest when the PQ interval was 0.18 +/- 0.04 seconds. There was a significant positive correlation between the critical PQ interval for the appearance of diastolic MR and the PQ interval at which CO was the highest (r = 0.91, P < 0.01). The PQ interval at which CO was the highest was 0.02 +/- 0.02 seconds shorter than the critical PQ interval for the appearance of diastolic MR (P < 0.05). When the PQ interval was increased by 0.025 seconds from the critical PQ interval for the appearance of diastolic MR, CO decreased from 4.3 +/- 0.6 L/min to 4.1 +/- 0.6 L/min and PCWP increased from 7.5 +/- 6.4 mmHg to 8.5 +/- 7.3 mmHg (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

[Protective effects of prostaglandin E1 on postoperative liver function after cardiac surgery].

Effects of prostaglandin E1 (PGE1) on liver function were studied in 72 patients who underwent mitral valve replacement (MVR) and coronary artery bypass grafting (CABG). The patients were divided into three groups: (A) patients with preoperative hepatic dysfunction who underwent MVR; (B) patients without previous hepatic dysfunction who underwent MVR; (C) patients without hepatic dysfunction who underwent CABG. About half of the patients in each group received PGE1 during the operation and postoperative period in the ICU. Change of serum GOT, GPT, albumin, total bilirubin, and cholinesterase (ChE) showed no difference between the patients with and without PGE1 administration in groups B and C. But, in group A, PGE1 administration significantly ameliorated the decrease of ChE, a condition which is usually observed in the first and second postoperative weeks after MVR. None of the patients showed severe hepatic dysfunction in the PGE1 group. One patient in the control group A revealed severe hepatic failure with high bilirubinemia and decreased ChE. These results suggest that the administration of PGE1 to patients with hepatic dysfunction, scheduled for MVR, might protect the liver from deterioration.

Aged↗
PubMed1993

Molecular cloning, sequence analysis, and characterization of a new cell wall hydrolase, CwlL, of Bacillus licheniformis.

We have cloned a DNA fragment containing the gene for a cell wall hydrolase from Bacillus licheniformis FD0120 into Escherichia coli. Sequencing of the fragment showed the presence of an open reading frame (ORF; designated as cwlL), which is different from the B. licheniformis cell wall hydrolase gene cwlM, and encodes a polypeptide of 360 amino acids with a molecular mass of 38,994. The enzyme purified from the E. coli clone is an N-acetylmuramoyl-L-alanine amidase, which has a M(r) value of 41 kDa as determined by SDS-polyacrylamide gel electrophoresis, and is able to digest B. licheniformis, B. subtilis and Micrococcus luteus cell walls. The nucleotide and deduced amino acid sequences of cwlL are very similar to those of ORF3 in the putative operon xpaL1-xpaL2-ORF3 in B. licheniformis MC14. Moreover, the amino acid sequence homology of CwlL with the B. subtilis amidase CwlA indicates two evolutionarily distinguishable regions in CwlL. The sequence homology of CwlL with other cell wall hydrolases and the regulation of cwlL are discussed.

Amino Acid Sequence↗
PubMed1993

Sustained effects of plasma norepinephrine levels on femoral-radial pressure gradient after cardiopulmonary bypass.

In order to determine the influence of the sympathetic nervous system upon the femoral-radial artery pressure gradient after cardiopulmonary bypass (CPB), we examined plasma norepinephrine levels in 34 adult male patients undergoing coronary artery bypass grafting. Cardiovascular parameters, including systolic arterial pressure, mean arterial pressure, cardiac index (CI), systemic vascular resistance index (SVRI), pulmonary artery pressure (PAP), hemoglobin (Hb) and peak dP/dt of radial and femoral artery pressures were measured after sternotomy, and immediately after the discontinuation of CPB and 90 min after CPB. Plasma norepinephrine levels were measured after sternotomy, after aortic declamping and 90 min after CPB. The patients were divided into two groups. Group A consisted of 17 patients whose femoral minus radial systolic pressure difference was 15 mmHg or more at 90 min after CPB, while Group B consisted of 17 patients with the difference less than 15 mmHg. Group A patients had significantly longer time values in the duration of both CPB (Group A 175 +/- 10 min; Group B 115 +/- 12 min, P < 0.001) and aortic cross clamping (Group A 116 +/- 7 min, Group B 71 +/- 9 min, P < 0.001). Although there was no significant difference in Hb or PAP of 90 min after CPB in Groups A and B, the following values, listed in the order of A to B, were obtained; CI, 2.79 +/- 0.10 versus 3.46 +/- 0.16 l.min(-1).m(-2) (P < 0.01); mean radial artery pressure (MRP), 58.7 +/- 2.4 versus 65.1 +/- 1.8 mmHg (P < 0.05); peak dP/dt of radial artery pressure, 568 +/- 64 versus 1026 +/- 61 mmHg.sec(-1) (P < 0.001); and plasma norepinephrine concentration, 1.81 +/- 0.25 versus 0.98 +/- 0.10 ng.ml(-1) (P < 0.01), which were statistically significant. The higher femoral-radial artery pressure gradient after CPB was observed in patients with both a longer CPB time and a higher plasma norepinephrine concentration. These results suggest that a marked constriction of peripheral arteries might have produced a damped transmission of the pressure pulse to the radial artery.

Journal Article↗
PubMed1993

Regulation of liver glucose-6-P dehydrogenase levels in female rats.

1. Gender differences in the dietary regulation of rat liver glucose-6-P dehydrogenase activity, synthesis and mRNA levels were examined. 2. As expected, in normal rats fed a standard chow diet, females have higher G6PD activity than males because they have more G6PD mRNA and therefore a higher rate of G6PD synthesis. 3. In contrast, the decreased dietary induction in female rats is due to a more rapid rate of G6PD degradation rather than a decrease in G6PD mRNA or synthesis.

Animals↗
PubMed1993

The routine use of soluble Lewis antigens in the identification of Lewis system antibodies.

Approximately 3 percent of the blood samples tested at the authors' laboratory have contained unexpected red cell (RBC) antibodies, of which about one-third have been anti-Le(a) or anti-Le(b). Although these antibodies are usually clinically insignificant, considerable workload was expended in their identification. In hopes of reducing this workload, an alternative approach for identifying these antibodies was implemented. If a patient had no history of unexpected antibodies, with the exception of Lewis system antibodies, and if the results of serum antibody detection testing were typical for the presence of anti-Le(a) and/or anti-Le(b), the serum was treated with commercially standardized soluble human Le(a) and Le(b) blood group substances, and the Lewis phenotype of the patient's red cells was determined. If the treated serum demonstrated specific antibody neutralization and the red cell phenotype was Le(a-b-), the results were interpreted as positive for anti-Le(a) or anti-Le(b), and no further antibody identification workup was performed. If the patient was Le(a+b-) or Le(a-b+), or if the treated serum failed to demonstrate specific antibody neutralization, the serum was tested against panels of reagent RBCs that were licensed for the identification of unexpected antibodies. During the study period (8-1-89 to 6-16-90), 498 of 46,965 patients' samples met the criteria for testing for specific antibody neutralization. Of these 498 blood samples, 452 showed specific neutralization of antibody activity by Lewis substance and were Le(a-b-). Only 1 of these samples was discovered to contain an additional non-Lewis antibody (anti-Bg).(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗
PubMed1991

Effect of 17 beta-estradiol on PAF and prostaglandin levels in oophorectomized rat uterus.

The effects of 17 beta-estradiol on the levels of platelet-activating factor (PAF) and prostaglandins and their precursor phospholipid in the uterus of oophorectomized rats were studied. Oophorectomy results in the decrease in the uterine PAF level to one-third of that in natural estrus. This level was recovered by subcutaneous administration of 17 beta-estradiol. The level of uterine phospholipids, which are rich in arachidonic acid, was significantly decreased by estradiol treatment. More arachidonate-PC was depleted than arachidonate-PE. The molecular structure was confirmed by gas chromatography-mass spectrometry. The amount of PGF2 alpha in the oophorectomized uterine tissue was 10-times that of PAF, but like the latter, increased 3-4 times on estradiol treatment. The chemical structures of PAF and PGF2 alpha formed on estradiol treatment were confirmed by mass spectrometry. The present data strongly suggest a correlation between the formations of PAF and PGF2 alpha, and indicate that estradiol may regulate the physiological formations of PAF and PGs in non-pregnant rat uterus.

Animals↗
PubMed1991

Regulation of glucose-6-phosphate dehydrogenase synthesis and mRNA abundance in cultured rat hepatocytes.

Conditions were identified which, for the first time, demonstrate that primary hepatocytes can express the same range of glucose-6-phosphate dehydrogenase (G6PD) synthesis and mRNA as in live rats. Primary hepatocytes were cultured without prior exposure to serum, hormones or carbohydrates. Five modulators implicated in G6PD induction in vivo were examined: insulin, dexamethasone, tri-iodothyronine (T3), glucose and fructose, T3 did not affect G6PD activity, and did not interact with carbohydrate to affect the activity of G6PD. Neither glucose nor fructose alone affected G6PD activity, and they did not interact with insulin to increase G6PD activity. Hepatocytes isolated from fasted rats and cultured in serum-free media with amino acids ad the only energy source how a 12-fold increase in G6PD synthesis and mRNA (measured by a solution-hybridization assay). This induction does not require added hormones or carbohydrate. The addition of insulin alone caused another increase in G6PD synthesis and mRNA. There are at least three distinct phases to G6PD induction under these conditions. The largest increase in G6PD synthesis (12-fold) occurs in the absence of any hormones and with amino acids as the only energy source. This phase is due to increased G6PD mRNA. Insulin causes an additional 2-3-fold increase in G6PD synthesis and mRNA. However, dexamethasone and insulin are both required before G6PD synthesis is equal to that in rats which are fasted and refed on a high-carbohydrate diet.

Animals↗
PubMed1991

Chronic venous insufficiency in primary varicose veins evaluated by plethysmographic technique.

Venous hemodynamics were evaluated by plethysmography in normal subjects and patients with venous disorders of the lower extremity, to clarify the pathophysiology of chronic venous insufficiency (CVI) due to primary varicose veins. Expelled volume during five active dorsiflexions of the feet and venous recovery time were calculated to evaluate muscle pump efficiency and valvular competence. Limbs with CVI due to primary varicose veins showed a higher expelled volume and a more shortened refilling time than limbs with simple varicosities. With application of tourniquets, the refilling time normalized in limbs with CVI, as well as in limbs with simple varicosities. These results indicate that a high degree of venous congestion in the distal part of the calf and valvular incompetence of the superficial vein system might cause CVI due to primary varicose veins.

Humans↗
PubMed1991

The sensitivity of antibody detection testing using pooled versus unpooled reagent red cells.

Because the sensitivity of antibody detection testing may be reduced when pooled reagent red blood cells (RBCs) are used, the American Association of Blood Banks (AABB) prohibits the use of pooled reagent RBCs when performing pretransfusion antibody detection testing. This restriction imposed upon the use of pooled reagent RBCs is based, at least in part, on the belief that pooled reagent RBCs are less likely to detect clinically significant antibodies than are sets of unpooled reagent RBCs. Little data, however, have been published to support this contention. In the present study, the data show a decreased sensitivity for antibody detection when pooled reagent RBCs are used. This reduced sensitivity could result in failure to detect some clinically significant RBC alloantibodies, which might result in the occurrence of overt hemolytic transfusion reactions, especially if an indirect antiglobulin test is not performed at the time blood is crossmatched.

Journal Article↗