Biomedical subjects

Y Imai

Publications and source records attributed to Y Imai.

At least 775 records · Page 43Linked to original sources

PubMed1992

The influence of antihypertensive agents on circadian rhythms of blood pressure and heart rate in patients with essential hypertension.

The effects of once-daily administration of calcium (Ca) channel blockers, beta-blockers and and angiotensin-converting enzyme (ACE) inhibitors on circadian rhythms of blood pressure (BP) and heart rate (HR) were studied using the cosinor method. Sixty-two recruited patients with essential hypertension (WHO stage I or II) were divided into three groups based on the class of administered drugs. In the Ca channel blocker group (n = 37, age 54 +/- 9.0 years), 18 patients were given YM 730 at a mean dose of 11 +/- 4.0 mg/day (mean +/- S.D.), 8 were given nitrendipine (11 +/- 6.7 mg/day), and 11 were given nisoldipine (8 +/- 6.4 mg/day). In the beta-blocker group (n = 15, age 42 +/- 13.5 years), 13 patients were given atenolol (44 +/- 11.0 mg/day), 1 was given nadolol (30 mg/day), and 1 was given sustained-release propranolol (60 mg/day). In the ACE inhibitor group (n = 10, age 56 +/- 8.7 years), 7 patients were given enalapril (6 +/- 2.8 mg/day), and 3 were given lisinopril (20 mg/day). Ambulatory BP monitoring (ABPM) was performed before and during treatment. Mean arterial pressure (MAP) and HR were monitored under ambulatory conditions every five minutes for 24 hr with a finger volume oscillometric device. In all three groups, the mesor of MAP decreased significantly, while the amplitude and acrophase did not change during treatment. beta-Blockers reduced the amplitude as well as the mesor of HR. Ca channel blockers increased the amplitude of HR without influencing the mesor. ACE inhibitors had no effect on the circadian rhythm parameters of HR. These results suggest that Ca channel blockers, beta-blockers and ACE inhibitors lowered BP throughout the day without changing the circadian BP rhythm. However, the three drug classes may have different influences on the autonomic nervous system that regulates circadian cardiac rhythm.

Adrenergic beta-Antagonists↗

PubMed1992

The effects of intrarenal infusion of recombinant human erythropoietin on mean arterial pressure and renal hemodynamics in anesthetized rabbits.

The effects of recombinant human erythropoietin (rHuEPO) on mean arterial pressure (MAP) and renal hemodynamics were studied in anesthetized rabbits without renal failure. Intrarenal infusion of rHuEPO at a rate of 100 U/min for 30 min resulted in no change in MAP, renal blood flow, or renal vascular resistance. rHuEPO also produced no significant change in glomerular filtration rate filtration fraction, or arterial hematocrit. These results demonstrate that rHuEPO has no direct effects on MAP or renal hemodynamics in anesthetized rabbits without renal failure.

Anesthesia↗

PubMed1992

Dependence of endocochlear potential on basolateral Na+ and Cl- concentration: a study using vascular and perilymph perfusion.

Inside-positive endocochlear potential (EP) and high potassium concentration in the endocochlear duct are generated by transepithelial K+ transport in marginal cells of the stria vascularis. In order to estimate the degree of involvement of Na+ and Cl- in K+ transport in marginal cells, EP in guinea pigs was measured under artificial vascular and perilymphatic perfusion in situ. Na+ depletion due to both vascular and perilymphatic perfusion decreased EP by -10.0 +/- 4.1 mV (delta EP = -86 +/- 5.2 mV, n = 5) from the control value of 78 +/- 4.3 mV (p < 0.01). Cl- depletion due to vascular and perilymphatic perfusion also decreased EP by -10.0 +/- 4.9 mV (delta EP = 8.5 +/- 4.8 mV, n = 6) from the control value of 77 +/- 5.1 mV (p < 0.01). However, under either vascular or perilymphatic perfusion, even lowering of Na+ or Cl- concentration in the perfusate decreased EP only slightly compared to the results under both vascular and perilymphatic perfusion. Furosemide, a blocker of Na+/K+/2Cl- symport, decreased EP under vascular perfusion. This dependency of EP on basolateral Na+ and Cl- concentration strongly suggests that K+ transport by the marginal cell is dependent on the basolateral Na+ and Cl- concentration, and that Na+/K+/2Cl- symport is raised as a possible mechanism for Na+ and Cl- dependency of EP.

Animals↗

PubMed1992

Osmotically inactive space during hyperosmotic stress in the perfused submandibular gland of the rat.

Cell volume changes were measured by an impedance method during hyperosmotic stress in the perfused rat submandibular gland. When the perfusate osmolarity was raised to 484 mosmol, the cell volume decreased and remained at a plateau level (79%). The decrease was smaller than expected from the extracellular fluid osmolarity change. Furthermore, the potassium content of the gland increased by 7% during the hyperosmotic stress. These results suggest that the cell volume changes observed during hyperosmotic stress are affected by the existence of an osmotically inactive space and by an increase in the intracellular solute content.

Animals↗

PubMed1992

Circadian blood pressure variation in patients with renovascular hypertension or primary aldosteronism.

Circadian blood pressure (BP) variation were studied in patients with renovascular hypertension (RVH) and primary aldosteronism (PA). Ambulatory BP (ABP) was monitored every 5 min for 24 hrs in a ward setting in 23 patients with PA and 17 patients with RVH (13 patients with unilateral renal arterial stenosis and 4 with bilateral stenosis). In patients with RVH, ABP was monitored before and after treatment with a converting enzyme inhibitor or percutaneous transluminal angioplasty. Plasma renin activity (PRA) was high before percutaneous transluminal angioplasty in almost all patients with RVH and low in those with PA. Ordinary circadian BP variation, i.e. nocturnal fall and diurnal rise in BP, was confirmed in the patients with unilateral or bilateral renal artery stenosis. Percutaneous transluminal angioplasty successfully normalized both BP and PRA in those with RVH. Normal circadian BP variation was observed in those with RVH before the treatment with a converting enzyme inhibitor or percutaneous transluminal angioplasty as well as during treatment with the former and after treatment with the latter. Circadian BP variation in the patients with RVH was affected by the pathogenesis of renal artery stenosis alone, i.e, fibromuscular hyperplasia and atherosclerosis; with fibromuscular hyperplasia normal circadian BP variation was observed, while with atherosclerosis, nocturnal BP fall was restricted or eliminated. Circadian BP variation in those with PA before and after excision of adrenal adenoma was essentially similar to that in normal subjects and essential hypertensive patients. From these it seems that in patients with RVH or PA, circadian BP variation is not affected by hypertension per se or by pathogenesis of hypertension.

Adenoma↗

PubMed1992

A Japanese pedigree of autosomal dominant congenital stationary night blindness with variable expressivity.

Three cases in three successive generations of one family with autosomal dominant congenital stationary night blindness are presented. Case 1, the proband, and Case 3, his grandfather had the same electroretinographic responses: nonrecordable scotopic electroretinogram (ERG), normal but slightly diminished flicker ERG, and negative-shaped single bright-flash ERG. Their dark adaptation curves were monophasic with no rod segment. However, Case 2, the proband's father, showed different ERG findings; a moderately diminished scotopic ERG, a normal flicker ERG, and a biphasic dark adaptation curve with an elevated final rod threshold. The authors believe that these differences reflect variations in the expressivity of a single gene mutation with the lowest expressivity being seen in Case 2.

Adult↗

PubMed1992

Effect of alpha-tocopherol on oxidative hemolysis, as evaluated by impedance measurement.

Using a hypoxanthine-xanthine oxidase (HX-XOD) reaction system, the effect of vitamin E (VE) on oxidative membrane injury was studied by the impedance method. Both VE-sufficient and VE-deficient erythrocytes showed an elevation of low frequency permittivity in the early phase of reaction. In the later phase of reaction, VE-sufficient erythrocytes showed a sustained elevation in permittivity, while VE-deficient erythrocytes showed a decrease in permittivity with time. These changes consisted with the process of hemolysis in the HX-XOD system. The similarity of early phase change between VE-sufficient and VE-deficient erythrocytes indicates that the HX-XOD system exerted a similar effect on both erythrocytes in the early phase. The difference in changes of later phase between the two types of erythrocytes suggests that VE suppressed the reduction in permittivity. When the results were analyzed by the Pauly-Schwan's theory based on the assumption that erythrocytes are spherical, the product of VE-deficient or VE-sufficient erythrocyte size (R) and membrane capacity (Cm) showed a change similar to that in permittivity.

Algorithms↗

PubMed1992

Effect of slow release nifedipine tablets in patients with essential hypertension.

The antihypertensive effect of slow release nifedipine (CAS 21829-25-4) tablets (20 mg, Adalat) administered once or twice daily was studied in patients with essential hypertension of WHO stage I or II. Ambulatory blood pressure was monitored by a finger volume oscillometric device every 5 min for 24 h before and during the treatment with nifedipine. Whether administered once or twice daily, nifedipine tablets dit not change the pattern of circadian blood pressure variation; i.e. diurnal rise and nocturnal fall. Twice daily administration induced a significant downward shift in the blood pressure pattern. In other words, further hypotensive effect was observed during the night when the blood pressure was already low. On the other hand, administration once daily in the morning lowered daytime blood pressure without affecting blood pressure during the night. The duration of action of nifedipine tablets administered once daily was 12 h or more. In the acute experiment using 20 mg tablets of nifedipine, plasma concentration of nifedipine was well correlated with the percentage change in mean blood pressure. The minimal effective plasma concentration of nifedipine was estimated to be 13.4 ng/ml. However, in chronic treatment, nifedipine lowered blood pressure at the plasma concentration of 10 ng/ml. The results indicate that nifedipine tablets administered once daily provide an effective antihypertensive regimen for controlling daytime hypertension with minimal antihypertensive effect during the night.

Adult↗

PubMed1992

[A case report of postoperative recurrent hepatocellular carcinoma effectively treated with HCFU administration combined with TAE].

A 62-year-old man was found to have recurrent hepatocellular carcinoma (HCC) 2 cm in diameter in the left lobe in June 1990. After right lobectomy of the liver which contained the tumors of S6 2 cm and S8 3 cm in diameter 7 months before, the patient was treated with hepatic arterial embolization (TAE) combined with infusion of anti-cancer drug (ADM, CDDP) four times since June 1990. HCFU 300 mg per day was administered orally since June 1990. Since the 3rd TAE in December, 1990, the tumor stain in the left lobe disappeared for 10 months till October, 1991. No remarkable side effect of HCFU was noticed during this period. HCFU administration combined with TAE effectively prevented post-surgical recurrence of HCC in this case.

Antineoplastic Agents↗

PubMed1992

Complement activation in the follicular light zone of human lymphoid tissues.

A comparative immunohistochemical study of the distribution pattern of complement components and regulatory proteins within secondary lymphoid follicles was performed by the immunoperoxidase technique. Fifteen lymphoid tissues including appendices. Peyer's patches and tonsils were analysed. Sixty secondary lymphoid follicles with evident polarity, that is, the distinct coexistence of a light zone, dark zone and mantle zone in the same lymphoid follicle, were tested with single antibodies. The light zones were consistently immunostained in a dendritic meshwork pattern with all antibodies. The immunostaining patterns were classified into two major groups based on the immunoreactivity of the dark zone. One immunostaining pattern was characterized by no immunostaining of the dark zone to the majority of the antigens. The second group was characterized by a diffusely weak to moderate dendritic meshwork pattern of the dark zone to some of the immunostainings of C9 (monoclonal), S-protein, and DF-DRC1, and all immunostainings of CR1 (CD35), Ber-Mac-DRC (CD35), CR2 (CD21), and R4/23. All four complement regulatory proteins were localized by immunoelectron microscopy attached to the cell surface of the cells, including follicular dendritic cells, in the light zone. Our data indicate that there is an evident functional difference between the light zone and the dark zone, and that complete activation of the complement system occurs only in the light zone.

Antigens, Differentiation, B-Lymphocyte↗

PubMed1992

Follicular dendritic cell and ICCOSOMES in germinal center reactions.

The development and destination of immune complex coated bodies (ICCOSOMES) was investigated at the ultrastructural level in the germinal centers (GC) of murine lymph nodes after secondary-immunization with horseradish peroxidase. Immediately after a booster injection, large amounts of immune complex (IC) were trapped on the surface of the cytoplasmic extensions of follicular dendritic cells (FDC). Cytoplasmic extensions, consisting mainly of FDC processes with associated IC, formed complex lamellar labyrinth-like structures (LBS). We describe here morphological changes of LBS. Lamellar or stationary LBS before the injection sequentially changed into distorted, filiform, glomerated and transitional LBS. Around day 1, IC-coated cytoplasmic extensions developed into glomerated LBS (G-LBS) which were invaginated into their own cytoplasmic ends, which swelled up to several microns in diameter. Around day 2, tufts of the glomerated LBS were unlaced and dispersed as (ICCOSOMES) in the interstitium. Some ICCOSOMES were endocytosed by germinal center cells (GCCs) and transported to the Golgi apparatus and perinuclear space. These ICCOSOME-bearing GCCs were B220-positive and some produced specific antibody (spAb) in the perinuclear space indicating they are in the B cell lineage. ICCOSOME-ingesting GCCs are thought to be able to process the antigen and present it to T cells. This may be important in the development of plasma cells and memory cells which developed from the GC B cells.

Animals↗

PubMed1992

[Surgical correction of atrioventricular discordance--results and follow-up].

Between January 1977 and October 1991, 47 consecutive patients with atrioventricular discordance, ventriculoarterial discordance, and two ventricles underwent intracardiac repair at the Heart Institute of Japan. Their ages at operation ranged from 2 months to 21 years (average 9.2 years) and period of follow-up ranged from 1 month to 168 months (average 65.1 months). There were five basic anatomic types according to the associated anomalies, grouped into (1) situs solitus, ventriculoarterial (V-A) discordance or double-outlet right ventricle (DORV), ventricular septal defect (VSD) and pulmonary outflow tract obstruction (POTO) (31 patients); (2) situs solitus, V-A discordance and VSD (6 patients); (3) situs solitus, V-A discordance and tricuspid regurgitation (TR) (2 patients); (4) situs inversus, V-A discordance or DORV, VSA and POTO (7 patients); (5) situs inversus, V-A discordance and VSD (1 patient). TR was evident preoperatively in 13 patients (28% of 47 patients), one of whom had Ebstein's anomaly. The conventional operation, which consisted of closure of VSD (34 patients), posterolateral pulmonary outflow enlargement (2 patients), tricuspid valvuloplasty (2 patients), and tricuspid replacement (1 patient) using the anatomical right ventricle as the systemic ventricle, was performed in 35 patients (RV group). The anatomic correction (so-called "double switch operation"), the new alternative operation using the anatomical left ventricle as the systemic ventricle, was achieved in 12 patients (LV group). Anatomic correction consisted of Senning and RV-PA ECR in 3, Mustard and RV-PA ECR in 4, Senning and arterial switch in 2, and Mustard and arterial switch in 1 patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

[Assessment of long-term systemic ventricular function after the surgical repair in patients with atrioventricular discordance].

Long-term systemic ventricular function at rest and during supine bicycle exercise was studied in 12 patients with atrioventricular discordance (AVD group) using multigated radionuclide blood pool imaging. For comparison, similar measurements were made in eight children (control group). The mean age at the exercise test was 12.3 years in AVD group and was 14.8 years in the control group. In AVD group, ages at the operation ranged from three to 21 years (mean 12.3 years), and the exercise test was performed from one to 9.8 years after the operation (mean 5.3 years). The operative procedures in AVD group consisted of closure of the ventricular septal defect in 11 patients, extracardiac conduit between the left ventricle and the pulmonary artery in nine patients, postero-lateral left ventricular outflow reconstruction in two patients, tricuspid annuloplasty in one patient, and tricuspid valve replacement in one patient. Exercise tolerance of AVD group was less than that of the control group. Heart rate and blood pressure were significantly increased during exercise in both groups. In the control group, end-diastolic count index (EDCI) (= end-diastolic volume) remained unchanged and end-systolic count index (ESCI) (= end-systolic volume) decreased during exercise. In contrast, both EDCI and ESCI were decreased in AVD group. As a consequence, systemic right ventricular ejection fraction (RVEF) increased during exercise in the control group, but remained unchanged in AVD group. Although stroke count index (SCI) (= stroke volume index) did not increased during exercise in AVD group, output count index (OCI) (= cardiac index) increased with the increase of heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

[Two-stage Jatene procedure after Mustard or Senning operation].

We have successfully performed a two-stage Jatene procedure in four patients who showed severe anatomical right ventricular dysfunction after atrial switch (Mustard or Senning) operation for transposition of the great arteries. All four patients developed an adequate left ventricular pressure for the arterial switch operation by one or two-stage pulmonary artery banding. Left ventricular posterior wall thickness increased sufficiently enough after the banding although left ventricular ejection fraction showed significant decrease. After Jatene procedure left ventricular ejection fraction recovered, and RV end-diastolic volume which had been prominently enlarged preoperatively was dramatically normalized. Cardiac index increased from 3.6 +/- 1.6 l/min/m2 preoperatively to 5.3 +/- 6.1 l/min/m2 postoperatively with the decrease in left atrial pressure. Postoperative electrophysiological study revealed the recovery of sinus node function and atrial conduction by means of the take-down of atrial switch operation previously performed. We conclude that the Jatene procedure should be an ideal alternative in patients with right ventricular dysfunction after atrial switch operation. The left ventricle could be prepared by an effective pulmonary artery banding in most instances.

Cardiac Surgical Procedures↗

PubMed1992

[A case report--combined Jatene procedure and extended aortic arch reconstruction for the original Taussig-Bing malformation associated with hypoplastic aortic arch, subaortic stenosis and coarctation of the aorta].

A successful repair with combined Jatene procedure (Lecompte modification) and extended aortic arch reconstruction in a two-month-old boy with the original Taussig-Bing malformation, associated with hypoplastic aortic arch, subaortic stenosis and coarctation of the aorta was described. The ascending aorta was measuring 8 mm and the distal aortic arch was 4 mm in outer diameter. The interventricular rerouting was not feasible, because the infundibular septum was almost aligned to the interventricular septum. So that arterial switch operation was preferred. The primary interventricular foramen was enlarged by wedge resection and the secondary interventricular foramen was closed with a patch of preserved equire pericardium. An extensive patch angioplasty of entire aortic arch down to descending aorta was performed with a composite patch of Xenomedica (preserved equire pericardium) and Dacron velour. Hypertrophied muscle bundles were resected for relief of subaortic stenosis. Jatene procedure was then performed. During neo-pulmonary reconstruction, distal pulmonary orifice was shifted towards right to avoid kinking and compression on the coronary arteries. One stage correction consisting of Jatene procedure and extended aortic arch reconstruction was considered to be a procedure of choice in this type of complex anomalies.

Aorta, Thoracic↗

PubMed1992

[Inhibition of acute rejection of heart graft in rats without immunosuppressants after intrathymic myocardial cell inoculation in the neonatal period].

There have been no successful cases reported of organ transplantation in application of neonatal immunological tolerance. Isolated myocardial cells from Lewis (LEW/Crj) rat hearts were inoculated into the thymus of incompatible King (WKAH/Hkm) rats. Ten weeks later the heart from LEW donor was transplanted heterotopically to the WKAH rat that had inoculated intrathymic myocardial cells without immunosuppression (n = 4, Group 1). Group 2 was made up of 4 isografts of heart transplantation (nontreated isograft). Group 3 was made up 4 allografts of heart transplantation (nontreated allograft). The animals were killed 7 days after transplantation, and early rejection was evaluated by accumulation of iodine-125 (125I)-labeled antimyosin antibody (AMA) uptake and confirmed by histological examination. In Group 1 & 2, the value of I-125 AMA uptake ratio was small (Group 1; RV: 1.28 +/- 0.28, IVS: 1.29 +/- 0.28, LV: 1.43 +/- 0.25, Group 2: RV: 1.14 +/- 0.07, IVS: 0.95 +/- 0.06, LV: 1.16 +/- 0.21). This level of the value indicates that the rejection does not occur. On the other hand, in Group 3, the value was high (RV: 4.63 +/- 1.92, IVS: 4.42 +/- 1.75, LV: 4.45 +/- 1.73) compared with Group 1 & 2. This level indicate that the rejection is severe. In the histological studies, Group 3 showed necrosis of myocardial cells, while Group 1 with neonatal immunological tolerance showed only very mild lymphocytic infiltration. The histology of thymic tissue in Group 1, the LEW myocardial cells are surviving in the WKAH rat thymus.

Animals↗

PubMed1992

The Kaike triathletes' hematocrit values. With relation to their competition results.

The subjects were 20 male triathletes in the 4th Kaike Triathlon, held in Tottori during 1984. The competitors' hemogram values were estimated at rest, during, and after the competition. The results were related to their competition order by methods of rank correlations and cluster analysis, using the average distance method. The first cluster, including an competition order is composed of hematocrit at rest, after swimming, after bicycling, and after the finish. The rank correlation coefficients between competition order and hematocrit values were significant (p less than 0.05) at each of the four periods, especially after swimming, though the probability is the same. We found that lower hematocrit values correlate with excellent competition results, as the competitors' hematocrit values could be elevated during exercise if their hematocrit values are in the low normal density whilst at rest.

Adult↗

PubMed1992

Role of the septal leaflet in tricuspid valve closure. Consideration for treatment of complete atrioventricular canal.

A septal leaflet of the tricuspid valve is thought to work differently from other anterior and posterior leaflets. We studied its role in valve closure in dogs by means of a dynamic area meter. During the control state, the tricuspid valve orifice area increased twice in diastole coincidentally with either atrial systole or rapid ventricular filling. We observed several findings after the septal leaflet resection: (1) two peak area patterns of the tricuspid valve orifice in diastole, (2) no elevation of right atrial pressure on ventricular systole (there was no V wave), (3) no tricuspid valve regurgitation on right ventriculography. These findings suggest that a complete valve closure occurred without the septal leaflet in regular sinus rhythm. An elevation of the right ventricular pressure produced by pulmonary artery stenosis without septal leaflet, however, easily caused tricuspid valve regurgitation in contrast to the same pressure of the right ventricle with the normal tricuspid valve. The right ventricular pacing caused severe valve regurgitation without the septal leaflet. Results indicate that in the repair of the complete atrioventricular canal defect and other tricuspid valve lesions, the septal leaflet of the tricuspid valve rarely requires attention. An atrioventricular block should be avoided, however, because electrical cardiac pacing on the right ventricle causes severe valve regurgitation without the septal leaflet.

Animals↗