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Biomedical subjects

K Tamura

Publications and source records attributed to K Tamura.

At least 973 records · Page 54Linked to original sources
PubMed1990

Effect of early diastolic loading on myocardial relaxation in the intact canine left ventricle.

Early transmitral flow (MiF) patterns depend strongly on the rate of fall of measured left ventricular pressure (Pm) determined by both the active decay of pressure (Pa) due to myocardial relaxation and the increase in pressure due to stretch of passive elements during filling (Pp). This study was designed to uncouple passive forces from deactivation in order to reveal the instantaneous rate and duration of myocardial relaxation. We assumed a parallel combination of passive and active elements: Pm(t,V) = Pa(t) + Pp(V), with no constraints on the form of Pa(t), where t is time and V is ventricular volume. Pp(V) was determined by a retrospective analysis of data obtained in 11 anesthetized dogs instrumented for volume clamping with a remote-controlled mitral valve, with left atrial and left ventricular micromanometers, and with an electromagnetic probe to measure MiF. The passive pressure-volume relation (both positive and negative portions) was determined by clamping at end-systolic volume or after various filling volumes, and fit to logarithmic functions. Pp(t) was then calculated from Pp(V) and V(t) (integral of MiF). Time to end relaxation (Ter) was defined as time when Pa = 0. During isovolumic relaxation, when dPp/dt = 0, dPm/dt is equal to the relaxation rate, dPa/dt. In completely isovolumic relaxations, asymptote P infinity = -7 +/- 6 mm Hg (thus, Pa is 7 mm Hg greater than Pm) and Ter = 40 +/- 15 msec, compared with 175 +/- 53 msec during normal filling. In high versus low inotropic state, Pa at the beginning of filling was greater (18.1 +/- 6.1 vs. 12.2 +/- 3.9 mm Hg), and Ter was shorter (170 +/- 42 vs. 228 +/- 43 msec). Active pressure Pa(t) during filling is not an exponential function, and at any time, it was always greater after filling than in nonfilling beats, which indicates an increase in the relaxation duration. We conclude that myocardial relaxation is modulated by filling, which slows its rate and increases its duration, and is therefore a function of both ventricular volume and time. Such a mechanism may have an important role in regulating the diastolic pressure-volume relation.

Animals↗
PubMed1990

Diastolic viscous properties of the intact canine left ventricle.

The viscoelastic model of the ventricle predicts that the rate of change of volume (strain rate) is a determinant of the instantaneous pressure in the ventricle during diastole. Because relaxation is not complete before the onset of filling, one cannot distinguish the individual effects of relaxation and viscosity unless the passive and active components that determine the ventricular pressure are separated. To overcome this problem, we used the method of ventricular volume clamping to compare the pressures in the fully relaxed ventricle at a given volume at zero strain rate (static pressure) and high strain rate (dynamic pressure). Six open-chest, fentanyl-anesthetized dogs were instrumented with micromanometers and an electronically controlled mitral valve occluder in series with the electromagnetic flow probe. We reasoned as follows: If there were significant viscosity, then the dynamic pressure would be higher than the static pressure. The static pressure was measured when the ventricle was completely relaxed following a mitral valve occlusion after an arbitrary filling volume had been achieved. The dynamic pressure was determined by delaying the onset of filling until relaxation was complete and then measuring the pressure at the same volume that was achieved when the static pressure was measured. In 19 different hemodynamic situations, the dynamic and static pressures were identical (mean difference, 0.1 +/- 0.8 mm Hg), indicating that in the passive ventricle viscoelastic effects are insignificant and do not contribute to the left ventricular diastolic pressure under normal filling rates.

Animals↗
PubMed1990

Coagulation-fibrinolysis abnormalities in acute and chronic phases of cerebral thrombosis and embolism.

We assayed plasma concentrations of fibrinogen, fibrinopeptide A, plasmin-alpha 2 plasmin inhibitor complex, D dimer, and antithrombin III activity in 40 patients with cerebral thrombosis and nine patients with cerebral embolism during the acute (less than 7 days), subacute (7-27 days), and chronic (greater than or equal to 28 days) periods and compared these with 69 controls. In cerebral thrombosis, fibrinogen and fibrinopeptide A levels were elevated significantly in all stages (p less than 0.001), whereas plasmin-alpha 2 plasmin inhibitor complex and D dimer levels were elevated significantly in the subacute and chronic periods. The antithrombin III activity was significantly decreased in the acute stage. The elevation of fibrinogen and plasmin-alpha 2 plasmin inhibitor complex levels in the acute stage was significantly greater in patients with an infarct size greater than 10 mm2 compared to patients with an infarct size less than 10 mm2. We observed similar changes in patients with cerebral embolism. These results suggest that enhanced coagulation exists at all stages and endogenous fibrinolysis is activated in the subacute and chronic periods in a large proportion of patients with cerebral thrombosis and embolism.

Acute Disease↗
PubMed1990

Irreducible dorsal dislocation of the interphalangeal joint of the great toe: report of two cases.

In this paper, we report two cases of dislocation of the hallux interphalangeal joint with interposition of the plantar plate including the sesamoid bone. These dislocations were treated with open reduction: one through lateral approach and the other through plantar approach. Plantar approach afforded repair of the plantar plate with preservation of the sesamoid bone and satisfactory result.

Adult↗
PubMed1990

The influence of immunosuppressive acidic protein on the activity of peripheral K-lymphocytes in subacute thyroiditis.

We previously reported that immunosuppressive acidic protein (IAP), an alpha 1-acid glycoprotein, is increased during the acute phase of subacute thyroiditis (SAT). In this study we measured the percentage and absolute number of peripheral K-cells using a plaque-forming cell technique to investigate immunological abnormalities associated with SAT. Additionally, we investigated the relationship between IAP and peripheral K-cell activity. In normal controls, a sex-related difference in the percentage of K-cells among total lymphocytes was present; the percentage was significantly lower in women (mean +/- SD, 5.0 +/- 2.0%; n = 12; P less than 0.01) than in men (8.4 +/- 2.9%; n = 13). However, there was no difference (0.153 +/- 0.073 x 10(9)/L in five females; 0.173 +/- 0.054 x 10(9)/L in seven males) in the absolute number of peripheral K-cells. During the acute phase of SAT, the percentage (2.4 +/- 1.9% in 16 females; 2.7 +/- 1.0% in 3 males) and absolute number (0.058 +/- 0.048 x 10(9)/L in 11 females) of K-cells were significantly lower than those in normal controls. These values returned to normal during the recovery phase, although their mean values were still lower than those in normal controls. In female patients with Graves' disease, the percentage (2.2 +/- 1.8% in 11 females) and absolute number (0.038 +/- 0.033 x 10(9)/L in 11 females) of K-cells were significantly lower than those in normal controls; in male patients, the percentage (4.2 +/- 2.7% in 5 males) was lower than that in normal controls, but the absolute number (0.136 +/- 0.114 x 10(9)/L) of K-cells was not significantly different. Serum IAP values during the acute phase of SAT showed a significant negative correlation with the percentage of K-cells (r = -0.66; P less than 0.01). The number of K-cells from a normal subject decreased significantly when these lymphocytes were incubated with sera from patients with SAT, and the mean inhibition rate of K-cells by serum samples from 13 SAT patients during the acute phase was higher than that during the recovery phase (68.0 +/- 21.0 vs. 38.0 +/- 23.0%; P less than 0.01). Purified IAP inhibited the activity of K-cells from normal subjects dose dependently. These results suggest that 1) there may be inhibitory factors for the antibody-dependent cell-mediated cytotoxicity of peripheral K-cells in the serum of patients with SAT, and 2) IAP may be one of these inhibitory factors.

Acute-Phase Reaction↗
PubMed1990

Response of A431 experimental human solid xenograft to mitomycin C in combination with human epidermal growth factor in mice.

We previously demonstrated that the antitumor efficacy of various antitumor agents such as 5-fluorouracil and cisplatin against experimental solid tumors was enhanced by pre- or simultaneous administration of human epidermal growth factor (hEGF). In the present study, the combined therapy by hEGF and mitomycin C (MMC) as an antitumor agent was studied in A431 solid tumor-bearing mice to determine the dosage schedule of hEGF. When MMC alone was injected intraperitoneally (2 mg/kg) every 7th day to the tumor-bearing mice, tumor weights increased to 2138 +/- 285 mg from 282 +/- 41 mg during 22 d. Tumor weight in every day treatment of hEGF alone for 21 d increased to the same extent in the treatment by MMC alone. On the other hand, the increase of the solid tumor weight in the every day treatment and in the every 7th day treatment of hEGF, in combination with the every 7th day administration of MMC, were as follows; from 282 +/- 41 mg to 1522 +/- 357 mg (71.2 +/- 16.7% of MMC alone) and from 280 +/- 44 mg to 1245 +/- 150 mg (58.2 +/- 7.0% of MMC alone), respectively, demonstrating a greater antitumor potency of MMC in the combination with the every 7th day treatment of hEGF. Both combined therapies did not affect the toxicity of MMC as evaluated by decrease in nontumorous body weight. Single subcutaneous administration of hEGF to A431 tumor-bearing mice caused the decrease of the binding capacity of hEGF to A431 tumor cells by 80% 24 h after the administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

14 alpha-hydroxyandrost-4-ene-3,6,17-trione as a mechanical-based irreversible inhibitor of estrogen biosynthesis.

Various derivatives of androst-4-ene-3,17-dione derived from microbial transformation were evaluated as inhibitors of human placental aromatase. 14 alpha-Hydroxyandrost-4-ene-3,6,17-trione was the most potent inhibitor showing a time-dependent, pseudo-first-order inactivation of aromatase in the presence of reduced nicotinamide adenine dinucleotide phosphate with apparent Ki of 1.3 microM and Kinact of 0.23 min-1. This compound also inhibited aromatase in rat ovary and suppressed serum estradiol levels in in vivo experiments.

Androstenols↗
PubMed1990

Intrinsic pressor activity of midaglizole, an alpha-2 adrenoceptor antagonist, in pithed rats.

Midaglizole (3 and 30 mg/kg, i.v.) increased blood pressure in pithed rats. The pressor response was not inhibited by intravenous prazosin (0.3 mg/kg), yohimbine (1 mg/kg), ketanserin (1 mg/kg) or diphenhydramine (5 mg/kg). Diltiazem (1 mg/kg) antagonized the hypertension. Idazoxan (10 mg/kg) also increased blood pressure, and the pressor response was inhibited by prazosin, but not by yohimbine. These results suggest that the vascular effect of midaglizole is due to a mechanism different from that of idazoxan.

Adrenergic alpha-Antagonists↗
PubMed1990

Comparison of cardiovascular effects of pirmenol with those of disopyramide in isolated canine heart preparations cross-circulated with a donor dog.

To assess the cardiovascular profiles of pirmenol, a new antiarrhythmic drug, and to compare them with those of disopyramide, isolated canine sinoatrial node, papillary muscle and atrioventricular node preparations cross-circulated with a donor dog were used. Pirmenol injected intraarterially into the isolated preparations showed negative chronotropic and inotropic effects, which were comparable to those of disopyramide; and it also showed coronary vasodilator and negative dromotropic effects on atrio-His as well as His-ventricular conduction, which were significantly more potent than those of disopyramide. Similarly, pirmenol administered intravenously into the donor dog showed more potent negative dromotropic effects on the PQ interval and QRS width than disopyramide, while in the isolated preparations cross-circulated by the donor dog, pirmenol and disopyramide showed equipotent cardiodepressant effects. In the same preparation, pirmenol decreased coronary blood flow following a transient increase, while disopyramide only decreased coronary blood flow. Since the antiarrhythmic action of class I drugs is considered to result from inhibition of the fast inward current, which generates and propagates action potentials and also induces ventricular automaticity, our results suggest that pirmenol possesses an electrophysiologic effect typical to an efficacious class I agent such as disopyramide.

Action Potentials↗
PubMed1990

[The suspended particulate matter (SPM) and polycyclic aromatic hydrocarbons (PAHs) in indoor and outdoor air along a main road].

The change in concentration of suspended particulate matter (SPM) in indoor and outdoor air in the Tokyo metropolitan area was studied using a new portable sampler (SPMP-sampler). The relationship between the airborne particle concentration in indoor and outdoor air varied with the aerodynamic diameters of the particles. The concentration of the SPM in indoor air increased in proportion to that in outdoor air. The polycyclic aromatic hydrocarbon (PAH) concentration in SPM also varied with the aerodynamic diameters of the particles. Fine particles with diameters of less than 2 microns contained high concentrations of PAH. The PAH concentration in indoor air increased in proportion to that in outdoor air. There were significant correlations between the concentrations of B(k)F, B(a)P, and B(ghi)P in indoor air. The mutagenic activities in the airborne particles also varied with the aerodynamic diameters of the particles. Fine particles with diameters of less than 2 microns had high mutagenic activities.

Air Pollutants↗
PubMed1990

Enzyme-linked immunosorbent assay for human insulin-like growth factor-I using monoclonal and polyclonal antibodies with defined epitope recognition.

Monoclonal antibodies (McAb) and polyclonal antibodies (PcAb) against human insulin-like growth factor-I (somatomedin C; hIGF-I) were produced. Using these two antibodies, an enzyme-linked immunosorbent assay (ELISA) system for hIGF-I was established. The ELISA system was able to detect hIGF-I at a range of 1-25 micrograms/l, compared with the range of 1-50 micrograms/l detected by radioimmunoassay (RIA). Human IGF-II and human insulin could not be recognized in this system. The plasma concentrations of IGF-I found using the ELISA agreed well with those found using RIA after conventional Sep-Pak C18 cartridge pretreatment. Epitopes of hIGF-I to McAb and PcAb were investigated by enzymatic digestion of hIGF-I followed by comparing the affinity of the antibodies to the peptides obtained proteolytically. The epitope to McAb was found to be a peptide containing Leu10-Val11-Asp12 (epitope 2). Five epitopes to PcAb containing the following key fragments were identified: a conformational structure formed by the disulphide bonds between Cys6 and Cys48, and between Cys47 and Cys52 (epitope 1), Leu10-Val11-Asp12 (epitope 2), Val17-Cys18-Gly19-Asp20 (epitope 3), Arg21-Gly22-Phe23-Tyr24 (epitope 4) and Lys68-Ser69-Ala70 (epitope 5). Of these, the peptide containing epitope 5 showed the highest affinity to PcAb. The results indicated that our ELISA system combined recognition by epitope 2 of McAb and recognition by epitope 5 of PcAb to obtain its good specificity.

Animals↗
PubMed1990

[Expression of major histocompatibility complex on human medulloblastoma cells].

Medulloblastoma is one of the most common malignant brain tumors in childhood. These cells are immature bipotential cells that could differentiate into both neuronal and glial cells. The authors established two human medulloblastoma cell lines. One was derived from a 2-year-old girl with cerebellar tumor (designated as ONS-76) and another was from a 9-year-old girl with metastatic tumor in the right frontal lobe (ONS-81). Immunohistochemical studies showed that both cell lines possessed 145 and 200 kDa neurofilament proteins and neuron-specific enolase, without glial fibrillary acidic protein and S-100 protein. It was shown that interferon gamma could enhance or induce the expression of the major histocompatibility complex (MHC) antigens which play a major role in immune response. Also shown for the first time was the expression of MHC class II antigens on human medulloblastoma (ONS-76 and 81) with neuronal differentiation.

Cerebellar Neoplasms↗
PubMed1990

Different effect of Helicobacter pylori on the human gastric antral and body mucosal intracellular mucin.

To elucidate the role of Helicobacter pylori infection in the pathogenesis of gastric ulcer, we investigated the intracellular mucin content by measuring the periodic acid-Schiff-Alcian blue (PAS-AB)-stained substances, by means of computer, in the biopsy sample of gastric mucosa from patients with and without H. pylori infection. In the antral mucosa the intracellular PAS-AB-stained mucin content was significantly smaller in patients with infection than in patients without infection, whereas in the oxyntic gland mucosa the intracellular mucin content showed no significant change between patients with and without infection. In an animal study we investigated the effect of ammonia, which might be produced by H. pylori in the presence of urea. The ammonia, administered orally, caused a greater decrease of intracellular PAS-AB-stained mucin content in the gastric antral mucosa than in the body mucosa, in a dose-dependent manner. The results suggested that H. pylori infection had a different effect on the gastric mucosal intracellular PAS-AB-stained mucin and lowered specifically the antral intracellular PAS-AB-stained mucin content, possibly due to generation of ammonia by H. pylori.

Alcian Blue↗
PubMed1990

Reproducibility of pitch-matching test for tinnitus. Using a heptatonic scale.

We evaluated the reproducibility of measured values obtained using a heptachord pitch-matching test (PMT). Investigation of the measured values by considering the minimum unit width limits of the testing scale revealed that the coincidence ratios of the measured values of intra-daily variations, intra-weekly variations and eight values measured consecutively in one test were as high as 100%, 94.8% and 83.3%, respectively. We therefore concluded that the reproducibility of this method is satisfactory. The measured values obtained by both ordinary one-octave-interval and heptachord PMT are compared in this article.

Adolescent↗
PubMed1990

[Role of free radicals in the development of acute mild and severe pancreatitis in mice].

In order to clarify the role of free radicals in the pathogenesis of acute pancreatitis, we observed the effect of a new synthetic free radical scavenger (CV-3611) on the pathological state in the models of both caerulein and CDE-diet induced acute pancreatitis in mice. In both models of acute pancreatitis, the levels of serum amylase activity were reduced significantly by the treatment of CV-3611. Pancreatic edema formation was also reduced significantly at 3.5 and 9 h after the first caerulein i.p. injection. The 4 days survival rate in CDE-diet induced pancreatitis was significantly elevated from 41.2% to 81.3% by the treatment of CV-3611. These results indicate that this synthetic scavenger, which has a long circulation half life, high affinity to biomembrane and good cell penetration ability, is effective on the development of both severe and mild pancreatitis. The main pathogenesis of both models is suggested to be radical reactions on the biomembrane which is caused by the interreaction between endothelium and neurophile in caerulein induced pancreatitis, and by the lipid peroxidation on the biomembrane of the organella in the cell in CDE-diet induced pancreatitis.

Acute Disease↗
PubMed1990

[Kinetics of circulating hematopoietic stem cells following chemotherapy in patients with hematopoietic malignancies].

The number of circulating hematopoietic progenitor cells was determined during 47 courses of chemotherapy in 23 patients with hematopoietic malignancies. rhG-CSF was given subcutaneously to 14 patients to rescue chemotherapy-induced neutropenia following 22 courses of chemotherapy. The mean numbers of CFU-GM in patients with malignant lymphoma (ML), acute leukemia (AL) and myeloma (MM) were 56.0 +/- 58.8 (mean +/- SD), 46.7 +/- 66.0 and 11.0 +/- 11.1 CFU-GM/ml, respectively. The number of CFU-GM in MM was significantly less than in normal subjects (51.2 +/- 30.6 CFU-GM/ml). The number of CFU-GM in PB in all patients began to rise between 2 days before and 8 days after nadir of WBC count, and then reached the peak at the subsequent 5 days. The peak values of CFU-GM in ML, AL and MM were 711.3 +/- 974.7, 660.0 +/- 374.7 and 403.6 +/- 232.5 CFU-GM/ml, respectively, but there was no statistical difference among them. When ML patients were treated with rhG-CSF, the CFU-GM peak values increased as much as 5.5-folds compared with those following chemotherapy only. However, neither the period from nadir to start of increase in the CFU-GM count nor the time of the CFU-GM peak showed any significant change. These results indicate that the administration of rhG-CSF makes it possible to increase the number of circulating progenitor cells. It appears possible in most of the patients with hematopoietic malignancies to harvest the sufficient number of progenitor cells which are necessary for autologous blood stem cell transplantation.

Acute Disease↗