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Biomedical subjects

Y Imai

Publications and source records attributed to Y Imai.

At least 1,027 records · Page 57Linked to original sources
PubMed1988

Difference in the nocturnal behaviour of blood pressure between monitorings with the arm-cuff method and with the finger-volume oscillometric method.

The nocturnal behaviour of blood pressure obtained by a new portable device for monitoring ambulatory blood pressure (ABPM 630) was compared with that obtained by a finger-volume oscillometric device (BP-100); the former uses a conventional arm-cuff inflated by CO2 gas to eliminate the noise of the motorized pump, and is based on a cuff-oscillometric as well as the Korotkoff sound technique (microphone method). With the microphone method in ABPM 630, the mean differences from the conventional auscultatory method were -0.28 +/- 6.15 mmHg (mean +/- s.d.) for systolic and 0.96 +/- 6.28 mmHg for diastolic blood pressure, and there was a highly significant correlation between blood pressure values measured by the ABPM 630 and by the auscultatory method. In 40 patients with mild to moderate hypertension 24-h blood pressure was monitored simultaneously with the ABPM 630 and BP-100. The daytime average of systolic blood pressure measured with the ABPM 630 was similar to that measured with the BP-100, whereas the night-time average assessed by the former was significantly higher than that assessed by the latter. Arm-cuff inflation by ABPM 630 caused some degree of sleep disturbance in 35 of 40 subjects, whereas finger-cuff inflation scarcely disturbed the sleep. The performance of the ABPM 630 was excellent.

Arm↗
PubMed1988

Reversed circadian rhythm of blood pressure in adult spontaneously hypertensive rats.

The diurnal rhythms of blood pressure and heart rate were examined in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) when they were 5-6 weeks old (young), 17-20 weeks old (adult) and 30-32 weeks old (old). Blood pressure was recorded continuously for 24 h in conscious, unrestrained rats. Hourly averages of blood pressure and heart rate were calculated by an on-line computer. The circadian variation of blood pressure and heart rate remained unchanged regardless of age in WKY, but the difference in blood pressure between the daytime average and the night-time average decreased as they grew older. A well-defined circadian variation of blood pressure and heart rate was observed in young rats of both strains, i.e. a nocturnal rise in blood pressure and heart rate. An inverted circadian variation of blood pressure, a nocturnal fall in blood pressure, was observed in adult and old SHR, whereas the ordinary circadian variation of the heart rate remained unchanged. A significant positive correlation was observed between the hourly averages of blood pressure and heart rate in WKY in all the age groups (r = 0.9, P less than 0.001 in each age group) and a weak positive correlation was observed in young SHR (r = 0.6, P less than 0.05, 5-6 weeks old). This positive correlation disappeared in adult and old SHR and, instead, a negative correlation was observed (r = -0.5, P less than 0.02 for 17-20-week-old rats: r = -0.8, P less than 0.001 for 30-32-week-old rats).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1988

Homologous human macrophage hybridomas that produce a novel cytotoxic factor in their culture supernatants.

Homologous human macrophage hybridoma cell lines were obtained by somatic cell fusion between peripheral blood monocyte-derived macrophages and a subclone of the myelomonocytic cell line, U937-F9. The hybridoma cell lines grown in vitro for more than a year were confirmed by manifestations of phagocytosis, adherence, nonspecific esterase, acid phosphatase, chromosome numbers and other cell surface antigens. Cell surface antigens on hybridomas were detected by flow cytometry analysis with monoclonal antibodies. With interclonal differences, a typical phenotype of hybridoma cells was CDw14+, OKM5+, Mac-1+ (equivalent to OKM1 and Mol), OKT9+, HLA-DR- and CD20+. After stimulation with lipopolysaccharide and calcium ionophore A23187, culture supernatants of clones c18A and c29A showed cytotoxic activity against human melanoma A375 Met-Mix and other cell lines which were resistant to the tumor necrosis factor, lymphotoxin and interleukin 1. This cytotoxic factor was found to be distinct from the tumor necrosis factor, lymphotoxin and interleukin 1 using the anti-tumor necrosis factor, anti-lymphotoxin and anti-interleukin 1 antisera.

Antibodies, Monoclonal↗
PubMed1988

Dendritic cell activating factor produced by mouse macrophage hybridoma.

A mouse macrophage (M phi) hybridoma which produces a soluble factor responsible for the cooperation between M phi and spleen dendritic cells (DC) was constructed. The antigen-presenting activity and the stimulator cell activity in the allogeneic or syngeneic mixed leukocyte reaction of DC were significantly augmented when DC were incubated with the culture supernatant of the hybridoma treated with various stimulants including latex beads. The monokine present in the culture supernatant of the hybridoma, called dendritic cell-activating factor (DCAF), augmented the production of lymphocyte-activating factor by DC while Ia expression of DCAF-treated DC was not altered. DCAF had no effect on the antigen-presenting activity of peritoneal resident M phi or B cell blasts while the antigen-presenting activity of spleen M phi was enhanced, but the degree of the enhancement was much less than that of spleen DC. DCAF was found to have the following properties: its pI value is between pH 4 and 5; it is stable at pH 2 to 10; and it loses its activity on incubation at 75 C for 30 min. When the culture supernatant of the hybridoma stimulated with latex beads was subjected to gel filtration, the DCAF activity was detected in the 20 Kd to 25 Kd, 30 Kd to 40 Kd, and 50 Kd to 60 Kd molecular weight regions. The 30 Kd to 40 Kd fraction, which is the major peak fraction, was further purified by ion-exchange chromatography followed by gel-filtration chromatography. When each fraction was subjected to SDS-PAGE, a 30 Kd band corresponding to the DCAF activity was observed and DCAF was purified to about 90% purity.

Animals↗
PubMed1988

A new monoclonal antibody, UFT-4, reacting with rat Kupffer cells. Immunohistochemical and immunoelectron microscopical analysis with reestimation of the reticuloendothelial system.

A new monoclonal antibody, designated UFT-4, reacting with rat Kupffer cells, was produced using sinusoidal liver-cell fraction as an immunogen. Immunohistochemically, UFT-4 reacted with Kupffer cells, interdigitating cells (IDCs), sinus endothelial cells of the spleen, a proportion of reticulum cells, smooth muscle fibers, choroid plexus epithelia and some macrophages. Immunoelectron microscopy disclosed two types of intracytoplasmic positivity: a striated type and a diffuse type. Both appeared to depend on variations in the quantity and distribution of the same antigen. On the other hand, UFT-4 gave a negative result for blood monocytes and most macrophages in lymphatic sinuses, lymphoid follicles, splenic red pulp and loose connective tissue. Cells positive for UFT-4 were mostly considered to belong to a narrow spectrum of the classical reticuloendothelial system, explaining the close relationship existing between some endothelia and some macrophages or reticulum cells. SDS-PAGE analysis of immunoprecipitates showed that the antigen reacting with UFT-4 was of molecule of 36-42 kDa under reducing conditions in the presence of 2-mercaptoethanol. The present results suggest that UFT-4 will be very useful for the study of Kupffer cells and for reconsidering their origin and destination.

Animals↗
PubMed1988

Criteria for two-staged arterial switch operation for simple transposition of great arteries.

We analyzed hemodynamic variables in patients with transposition of the great arteries with intact ventricular septum (simple transposition) after pulmonary artery banding and Blalock-Taussig anastomosis to establish the criteria for two-staged arterial switch operation. The study included 35 patients who underwent the switch operation after banding and anastomosis; two died shortly after surgery, and one died of tachycardia 31 days after the operation. The left-to-right ventricular pressure ratio was above 0.83 in all surviving patients, 0.68 and 0.63 in the two operative deaths, and 0.84 in the other death. In the 32 surviving patients, angiographically determined left ventricular (LV) end-diastolic volume and ejection fraction averaged 147 +/- 46(SD)% of normal and 0.64 +/- 0.12, respectively. We also measured LV mass using angiographic LV semiaxes and end-diastolic LV posterior wall thickness obtained from an echocardiogram. These variables of the patients who died were not different from those of the surviving patients. The wall thickness was greater than 4 mm in the surviving patients, while it was 3.5 mm in the two patients who died early and 5 mm in the patient who died later. From the semiaxes, the wall thickness, and aortic diastolic pressure, all of which were obtained before the anatomic repair, we calculated the predictive LV wall stress. This wall stress would indicate the LV wall stress at the time of aortic valve opening immediately after the arterial switch operation. Predictive wall stress was less than 120 x 10(3) dynes/cm2 in all but one of the surviving patients, whereas it was 151, 153, and 186 x 10(3) dynes/cm2 in the three patients who died.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1988

Altered circadian blood pressure rhythm in patients with Cushing's syndrome.

The circadian blood pressure rhythm was compared in patients with Cushing's syndrome, essential hypertension, and primary aldosteronism. In patients with essential hypertension or primary aldosteronism, a clear nocturnal fall in systolic and diastolic blood pressure and heart rate was observed. This fall was seen in untreated subjects as well as in patients receiving combined treatment with a calcium antagonist, diuretic, converting enzyme inhibitor, alpha-blocker and beta-blocker, or sympatholytic drug. In these groups, there was a positive correlation between heart rate and systolic or diastolic blood pressure. On the other hand, in patients with Cushing's syndrome, there was no nocturnal fall in blood pressure but in some patients a rise was observed. In all patients there was a nocturnal fall in heart rate. Thus, there was no significant correlation between heart rate and blood pressure in these patients. Exogenous glucocorticoid eliminated the normal nocturnal fall of blood pressure in patients with chronic glomerulonephritis or systemic lupus erythematosus. These results suggest that the changed circadian blood pressure pattern in patients with Cushing's syndrome is not due to antihypertensive treatment or to the mineralocorticoid excess accompanying this disease, but it is attributable to excess glucocorticoid or the associated disturbance in the adrenocorticotropic hormone-glucocorticoid system (or both). This conclusion also implies that the normal circadian rhythm of blood pressure may be regulated at least in part by the adrenocorticotropic hormone-glucocorticoid system.

Adolescent↗
PubMed1988

Effects of retinoic acid on alkaline phosphatase messenger ribonucleic acid, catecholamine receptors, and G proteins in ROS 17/2.8 cells.

Retinoic acid (RA) inhibits the increases in alkaline phosphatase (AP) and hormone-stimulated adenylate cyclase that accompany the growth of ROS 17/2.8 osteosarcoma cells in culture. The RA effects were first detected 2 days after initiation of treatment and were dose dependent, with an EC50 of 100 nM. The reduction in the hormone-responsive adenylate cyclase activity was associated with lower levels of beta-catecholamine receptors, without a change in apparent receptor affinity and with lower levels of the GTP-binding proteins Gs and Gi, visualized by NAD-dependent [32P]ADP ribosylation. The reduction in AP was correlated with a decrease in the steady state level of AP mRNA. RA had no effect on cell proliferation or saturation density. Retinoids thus inhibit the same features that are promoted by glucocorticoids in ROS 17/2.8 cells. These features seem to be subject to coordinate regulation, probably at the pretranslational level.

Adenylyl Cyclases↗
PubMed1988

Antipituitary antibodies in patients with the primary empty sella syndrome.

The frequency of detection of serum antibodies against pituitary cells was determined in 32 patients with the primary empty sella syndrome. Antibodies reacting with corticotropin-secreting mouse AtT20 and PRL-secreting rat GH3 cells were found in 24 (75%) and 15 (47%), respectively, of the 32 patients; 14 patients (44%) had antibodies reacting with both cell lines. In patients with pituitary adenomas, the prevalence of antipituitary antibodies was significantly lower than in those with the empty sella syndrome; 1 of 9 acromegalic patients had antibodies reacting with GH3 cells, and 2 of 9 prolactinoma patients and 1 of 7 patients with nonfunctioning adenomas had antibodies reacting with both AtT20 and GH3 cells. Among 6 patients with idiopathic diabetes insipidus, 1 patient had antibodies reacting with AtT20 and GH3 cells, and 2 patients had antibodies reacting with either AtT20 or GH3 cells. None of 5 patients with established autoimmune diseases (3 with systemic lupus erythematosus and 2 with autoimmune adrenal failure) had antipituitary antibodies in their serum. These results suggest that pituitary antibodies may be related to the development of pituitary atrophy and the primary empty sella syndrome, and that the test may be clinically useful as a screening test for the empty sella syndrome.

Adolescent↗
PubMed1988

Renal vein plasma renin activity in patients with unilateral renovascular hypertension.

Plasma renin activity in the renal veins (V) or infrarenal inferior vena cavae (IVC) of 20 patients with unilateral renovascular hypertension (RVH) was measured to determine how renal vein renin ratio (RVRR) compares with renin index (V-IVC/IVC) as a predictor of curability of RVH. Although there was no significant difference between them in predicting curability, 3 out of 4 patients with hypersecretion of renin (V-IVC/IVC greater than or equal to 0.48) in the stenosed side with contralateral suppression (V-IVC/IVC less than or equal to 0) on the normal side were cured. In addition, 7 out of 11 patients with contralateral suppression irrespective of values of renin index in the stenosed side were also cured. On the other hand, only one out of 6 patients who had neither hypersecretion nor contralateral suppression was cured. These results reconfirm that significant renin secretion with or without contralateral suppression, or only contralateral suppression of renin is highly suggestive of curable RVH.

Adult↗
PubMed1988

Changes in left ventricular dimensions after pulmonary artery banding and Jatene operation in children with complete transposition of the great arteries. Echocardiographic study.

Echocardiographic left ventricular (LV) dimensions in patients with complete transposition of the great arteries (TGA's) were measured before and after the Jatene procedure and/or pulmonary artery banding (PAB). The LV posterior wall thickness at end-diastole (LVPWTD) increased from 3.5 +/- 0.4 to 4.9 +/- 0.9 mm (mean +/- 1SD) (p less than 0.01) after PAB, but it did not show a significant change following the Jatene procedure (from 4.5 +/- 1.0 to 5.3 +/- 0.8 mm). The LV end-diastolic internal dimension (LVIDD) increased from 17.7 +/- 4.0 to 22.6 +/- 6.5 mm after PAB (p less than 0.01), but remained unchanged after the Jatene procedure (from 24.5 +/- 5.0 to 25.0 +/- 3.0 mm). The LV shortening fraction (LVSF) decreased from 0.62 +/- 0.10 to 0.47 +/- 0.14 after PAB (p less than 0.01), but remained unchanged after the Jatene procedure (0.40 +/- 0.10 to 0.37 +/- 0.10). the a/b ratio at end-systole: (a/b)s, which indicates the flatness of the LV configuration, increased from 0.27 +/- 0.14 to 0.60 +/- 0.21 after PAB (p less than 0.01) and from 0.61 +/- 0.13 to 0.74 +/- 0.17 after the Jatene procedure (p less than 0.01). The data obtained became stable 1 month after operation. One patient died of low cardiac output with no evidence of myocardial infarction after the Jatene procedure. In this patient, LVPWTD was 5.7 mm, LVIDD was 26 mm, LVSF was 0.71 and the (a/b)s ratio was 0.55.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1988

The hypotensive mechanism of percutaneous transluminal dilatation (PTD) in renovascular hypertension due to bilateral renal artery stenosis.

The hypotensive mechanism of percutaneous transluminal dilatation (PTD) in renovascular hypertension due to bilateral renal artery was investigated in two patients. Blood pressure was monitored continuously before, during and after PTD by use of a new automated blood pressure monitoring device based on finger volume-oscillometry. Plasma renin activity was measured repeatedly before, during and after PTD. A hypotensive effect appeared immediately after PTD and blood pressure remained low in the following observation period without any hypotensive medication. In these cases, the hypotension was accompanied by a transient decrease in heart rate immediately after PTD. The hypotensive response to PTD was not parallel to the basal plasma renin activity, suggesting that the renin-angiotensin system is not necessarily involved in the maintenance of the hypertension before PTD. The autonomic nervous system seemed to play a certain role. Since the hypotension was accompanied by a transient decrease in heart rate immediately after PTD, the hypotension may be induced either by a decrease in sympathetic tone or by an increase in vagal tone at least just after PTD. It is hypothesized that these changes in autonomic nervous activity are mediated centrally through the renal afferent mechanism in response to rapid changes in renal hemodynamics induced by PTD.

Adult↗
PubMed1988

Protein engineering in studies on metabolism of toxic substances.

Expression of cytochrome P-450s, drug metabolizing enzymes, from their coding sequences in heterologous cells were developed and the enzymatically active P-450s were synthesized. cDNAs of various chimera or mutant P-450s were constructed and expressed. Thus, regions or residues important for the function of cytochrome P-450 were analyzed.

Animals↗
PubMed1988

Continuous measurements of tissue impedance during secretion in dog submandibular gland.

The electrical impedance of the dog submandibular gland, as an indicator of changes in extracellular fluid (ECF) volume, was measured at 5 kHz, 500 kHz, and 5 MHz at intervals of 10 s during secretory stimulation, because the conductivity calculated from impedance at low frequencies reflected the ECF volume. The decrease in conductivity occurred in the first minute of stimulation. Its decrease was more marked during stimulation after circulatory arrest. Salivary secretion under intact circulation consists of two phases: an initial secretion occurring in the first minute of stimulation with a high secretory rate and a steady secretion continuing during stimulation at a constant rate. A decrease in conductivity occurred in the initial secretion. Within a few minutes following the cessation of stimulation, the conductivity increased to a level higher than the resting one with an intact circulation, while the blood flow remained several times higher than in the resting state. The conductivity of the gland slowly recovered to the prestimulation level over a 30-min period. The histological examination revealed that the main compartment of the ECF change was the interlobular space. Impedance and histological studies showed that the ECF volume of salivary glands changes dynamically during secretion. On the other hand, the cellular volume also increased in the initial secretion of an isolated gland. Its increase suggested that the fluid was transported to the lumen via a cellular pathway as well as a paracellular pathway in the initial secretion.

Animals↗
PubMed1988

The number and size of normal mediastinal lymph nodes: a postmortem study.

For the CT diagnosis of pathologically enlarged nodes, information concerning the size of normal nodes is required. We studied 40 adult cadavers and determined the number and size of normal lymph nodes for each region of the mediastinum, counting all nodes and directly measuring the short and long diameters of each in the transverse plane of the node. The location of each node was classified according to the American Thoracic Society system, and the range and standard maximum sizes of normal lymph nodes in each location were determined. Nodes were found in 90-100% of cadavers in regions 4, 7, and 10; and in 68-85% of cadavers in regions 2 and 6. The average number of lymph nodes found was 3.5-4.8 in regions 4, 6, and 10R; 2.1-2.9 in regions 2, 7, and 10L; and 0.1-1.2 in all other regions. The mean short transverse diameters ranged from 2.4 to 5.6 mm, and the mean long transverse diameters ranged from 3.9 to 10.0 mm. The largest mean short and long transverse diameters were found in region 7, the next largest were in region 10R, followed by regions 4, 5, and 10L. We noted a different maximum normal size of lymph nodes in each region of the mediastinum. The short transverse diameter, which showed a smaller variation, appeared to be a more useful parameter than the long transverse diameter. We propose a standard for maximum normal short transverse diameters for nodes in each region of the mediastinum as follows: 12 mm for nodes in region 7; 10 mm for nodes in regions 4 and 10R; and 8 mm for nodes in other regions. The maximum long transverse diameters showed a wider variation, ranging from 25 to 10 mm.

Female↗
PubMed1988

The differential cardiovascular response to centrally administered carbachol seen in Brattleboro and normal Long-Evans rats.

The cardiovascular effects of centrally administered carbachol were examined in conscious Long-Evans (LE) and Brattleboro (DI) rats. Carbachol induced a long-lasting increase in blood pressure and a decrease in heart rate in LE rats, whereas in DI rats no bradycardia was observed and the pressor response was significantly less than that in Long-Evans rats. Intravenous vasopressin antagonist, d(CH2)5 Tyr(Me)AVP, significantly attenuated the pressor response and eliminated the bradycardic response to carbachol in LE rats. However, the pressor response to carbachol in DI rats was still significantly less than that in LE rats treated with vasopressin antagonist. Intravenous phentolamine partially inhibited the pressor response to carbachol in LE rats and completely eliminated it in DI rats. These results suggest that hypertensive response to i.c.v. carbachol in normal rats is mediated both by an increase in central sympathetic outflow and in circulating vasopressin. The bradycardia seems to be mediated mainly by an increase in circulating vasopressin.

Animals↗