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Biomedical subjects

T Kamada

Publications and source records attributed to T Kamada.

At least 433 records · Page 24Linked to original sources
PubMed1992

Detection of hepatitis C virus RNA in chronic non-A, non-B liver disease.

Serum samples were tested for detection of hepatitis C virus (HCV) RNA from 156 patients with chronic non-A, non-B liver disease. HCV RNA was detected in 121 (93.8%) of 129 patients positive for anti-C100-3 but was also found in 15 (55.6%) of 27 patients negative for anti-C100-3. The rate of positivity for HCV RNA was not significantly different among various stages of liver diseases. These results showed that HCV continues to replicate even in advanced liver disease and that it seems to be related to half of the cases of chronic non-A, non-B liver disease negative for anti-C100-3.

Adult↗
PubMed1992

Mechanism of gastric mucosal damage induced by ammonia.

The mechanism for Helicobacter pylori-induced gastric mucosal injury remains obscure. H. pylori has high urease activity to produce ammonia from urea in the stomach. In this study, the effects of ammonia on (a) gastric mucosal integrity, (b) gastric mucosal hemodynamics, (c) mucosal cellular viability, (d) mitochondrial respiration, and (e) energy metabolism of gastric mucosal were investigated. Ammonia (pH 10.3) at concentrations of greater than 125 mmol/L caused acute macroscopic gastric mucosal lesions in a dose-dependent manner, whereas glycine-NaOH buffer (pH 10.3) or ammonium chloride (pH 4.5) did not. The decrease in energy charge preceded the occurrence of gastric mucosal lesions, but ammonia caused no change in mucosal hemodynamics. Oxygen consumption of isolated cells and mitochondria of gastric mucosa was inhibited by ammonia dose-dependently. The present results indicate that ammonia impairs mitochondrial and cellular respiration and energy metabolism and that ammonia decreases mucosal cell viability, leading subsequently to mucosal damage.

Ammonia↗
PubMed1992

Successful treatment of a hepatic cyst by one-shot instillation of minocycline chloride.

Hepatic cysts are not rare but usually are asymptomatic; however, large ones sometimes show clinical manifestations. Treatment of a solitary hepatic cyst by one-shot instillation of minocycline chloride is reported here; 500 mg of minocycline chloride was instilled into the hepatic cyst, 11 cm in diameter, through a percutaneous transhepatic cholangiography needle under ultrasound guidance. After 5 weeks, the cyst had decreased in size to 5 cm. Five months later, the cyst could not be detected by diagnostic imaging. Fifteen months after the treatment, no reaccumulated fluid was observed. Ultrasound-guided percutaneous one-shot instillation of minocycline chloride seems to be a safe, easy, and useful procedure for treating a hepatic cyst.

Cysts↗
PubMed1992

Power spectral analysis of heart rate variability in Type As during solo and competitive mental arithmetic task.

It has been reported that there are differences in autonomic balance between Type As and Type Bs. This study evaluated the sympathovagal interaction in Type A (N = 10) and Type B (N = 10) male students during mental arithmetic task in a solo and a competitive condition by the spectral component analysis of heart rate variability (HRV). The low-frequency (LF) component to high-frequency (HF) component ratio was significantly greater in Type As than in Type Bs, though no significant differences were found in task performance, heart rate change, and blood pressure between the two subject groups in both conditions. The present findings indicate that there was a significant difference in sympathovagal balance between Type As and Type Bs, and that Type As showed dominant sympathetic activity. The results suggest that the power spectral analysis of HRV, which is convenient and non-invasive, has enough sensitivity to discriminate differences in autonomic balance between Type A subjects and Type B subjects, not only during the solo and competitive task period but also during the resting period.

Heart Rate↗
PubMed1992

Recombinant human superoxide dismutase can attenuate ischemic neuronal damage in gerbils.

The effects of recombinant human superoxide dismutase (r-hSOD) on ischemic neuronal injury were examined. Cerebral ischemia was produced in Mongolian gerbils by occluding bilateral common carotid arteries for 5 min. Preischemic treatment with r-hSOD clearly reduced hippocampal neuronal damages while postischemic treatment did not. This result suggests that oxygen free radicals play an important role in selective vulnerability to ischemia and r-hSOD has a potential clinical usefulness against cerebral ischemia.

Analysis of Variance↗
PubMed1992

Adverse effects of epinephrine in patients with advanced left ventricular dysfunction: analysis of ventriculo-arterial coupling.

We examined the response of ventriculo-arterial coupling to epinephrine in 19 patients with normal left ventricular function and with left ventricular dysfunction of various degrees using a conductance catheter. They were divided into three groups: group I, seven patients without left ventricular wall motion abnormality; group II, six patients with ejection fraction of 45-60%; group III, six patients with ejection fraction of 28-40%. Changes in the slope of the end-systolic pressure-volume relationship (end-systolic elastance), the effective arterial elastance, the ratio of effective arterial elastance to end-systolic elastance and the ventricular work efficiency during administration of two different doses of epinephrine (0.05 and 0.1 micrograms/kg/min) were compared among the three groups. At baseline there were no significant differences among the three groups in the ratio of effective arterial elastance to end-systolic elastance, or ventricular work efficiency. At the lower dose of epinephrine, the mean ratio of effective arterial elastance to end-systolic elastance decreased and the mean ventricular work efficiency increased in any groups. At the higher dose of epinephrine the mean ratio of effective arterial elastance to end-systolic elastance further decreased and the mean ventricular work efficiency further increased in groups I and II. However, the mean ratio of effective arterial elastance to end-systolic elastance did not decrease but the mean ventricular work efficiency even decreased in group III. Thus, in patients with advanced left ventricular dysfunction, even a high dose of epinephrine does not modulate the ventriculo-arterial coupling to increase ventricular work efficiency.

Aged↗
PubMed1992

Normoglycemia per se but not normoinsulinemia is responsible for suppressing endogenous insulin secretion after oral glucose load in NIDDM.

It is well known that intensive insulin treatment of non-insulin-dependent diabetics (NIDDM) suppresses endogenous insulin secretion and thereafter improves it. To determine whether 'peripheral normo-insulinemia' or 'normoglycemia' established by the treatment is responsible for this suppression, the following five experiments were conducted on 15 well-controlled non-obese NIDDM patients. Experiment 1: a 100 g oral glucose load (OGL) was performed and blood glucose was monitored by an artificial endocrine pancreas (AP). Experiment 2: a 100 g OGL was done and blood glucose was normalized by AP-controlled insulin infusion. Experiments 3 and 4: a 100 g OGL was conducted while 'hyperglycemia' seen in experiment 1 was mimicked by AP-controlled glucose infusion with pre-programmed insulin infusion at the same rates as those in experiment 2 ('normoinsulinemia') or at rates 1.5 times higher than those in experiment 2 ('relative hyperinsulinemia'), respectively. Experiment 5: a 40 g OGL was conducted while AP-controlled insulin and glucose infusions were administered to make the plasma insulin level lower than in experiment 2 ('hypoinsulinemia') and to mimic the normoglycemic profile observed in experiment 2, respectively. In experiments 3 and 4, neither 'normoinsulinemia' nor 'relative hyperinsulinemia' suppressed the increase in plasma C-peptide after a 100 g OGL. In experiment 5, where the plasma insulin level showed a significantly (P less than 0.05) lower level than in experiment 2 and glycemia was normalized, C-peptide did not show a significant rise after OGL. These results indicate that 'normoglycemia' rather than 'normoinsulinemia' attained during exogenous insulin therapy, is responsible for suppressing endogenous insulin secretion against orally administered glucose.

Blood Glucose↗
PubMed1992

Changes in polyphosphoinositides and phosphatidic acid of erythrocyte membranes in diabetes.

We studied metabolic pool size of polyphosphoinositides and phosphatidate of erythrocyte membranes from normal and diabetic subjects using 32P for 20-h incubation, a sufficiently long period to reach isotopic equilibrium between monoesterphosphate bond and gamma-phosphate of ATP. Phosphatidylinositol 4-monophosphate (PtdIns4P), phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) and phosphatidate were the phospholipids labelled. Metabolic pools of individual phospholipids were estimated, based on their proportionate and absolute radioactivity. A significant decline in radioactivity of phosphatidate and PtdIns(4,5)P2 was seen in erythrocytes from the diabetic subjects, indicating suppression of the metabolically labile pool of these two phospholipids. There was no significant change in PtdIns4P radioactivity between the groups. The direct effect of insulin on phosphorylation of polyphosphoinositides and phosphatidate was also evaluated by a short incubation period of erythrocyte membranes with [gamma-32P]-ATP. Added insulin increased the incorporation of 32P into phosphatidate in a dose-dependent manner that reached a steady state at 2 nM. We conclude that the metabolically labile pool size of phosphatidate is decreased and that of polyphosphoinositides is altered in erythrocyte membranes from diabetic patients.

Adenosine Triphosphate↗
PubMed1992

Lowered membrane fluidity of younger erythrocytes in diabetes.

In vivo age-related changes in membrane fluidity of erythrocytes were investigated by a spin label method after fractionation of the cells by discontinuous density gradient centrifugation. Membrane fluidity was lower in older than in younger erythrocytes in both the normal and diabetic subjects. Cells from diabetic subjects showed a significantly lower level of membrane fluidity for all three age groups (younger, middle and older) than the corresponding cells from normal subjects. The magnitude of progression in the decrease in membrane fluidity in erythrocytes did not differ significantly between both groups of subjects. Both erythrocyte ATP and acetylcholinesterase activity declined, while glycosylated hemoglobin (HbA1c) increased with cell age in both groups of subjects. The HbA1c level in each corresponding fraction was higher in diabetic subjects than normal subjects, but was not correlated with membrane fluidity in either group. Neither the ATP level nor acetylcholinesterase activity in each corresponding fraction differed between groups. Membrane fluidity was significantly correlated with acetylcholinesterase activity in both normal and diabetic subjects. Our results indicate that decreased erythrocyte membrane fluidity in diabetic patients does not form gradually during their life span but develops soon after the cells enter the circulation or during their maturation in the bone marrow.

Acetylcholinesterase↗
PubMed1992

Enhanced expression of HLA class I by inhibited replication of hepatitis B virus.

HLA class I display on hepatitis B virus (HBV)-infected hepatocytes is important for limiting HBV infection. However, the effect of HBV replication on HLA class I expression on host cells has not been determined. Since acyclovir is known to inhibit HBV replication of the novel cell line HB611, which was transfected with HBV genome using human hepatoblastoma cells as the recipient and continuously replicates HBV DNA, we analyzed HLA class I expression on acyclovir-treated HB611 by quantitative flow cytometry. The results demonstrated that acyclovir treatment clearly increases the level of HLA class I on HB611, and suggested that HBV replication inhibits expression of HLA class I on infected hepatocytes. This effect of HBV replication on the host cell may be a means by which HBV evades immune surveillance to maintain chronic infection.

Acyclovir↗
PubMed1992

Effects of various fat sources on growth and hepatic mitochondrial function in mice.

1. Five parameters with biophysical meaning for Parks' feeding and growth equations showed that mice fed diets containing hydrogenated beef tallow or beef tallow had lower mature body weight than soybean oil, linseed oil or fish oil-fed groups, and that mice fed hydrogenated beef tallow or fish oil diets had a lower feed efficiency factor than beef tallow, soybean oil or linseed oil-fed groups. 2. Mice fed the diet containing soybean oil or linseed oil had higher carcass fat as a per cent of body weight, significantly different from mice fed hydrogenated beef tallow, which exhibited the lowest carcass fat. 3. The respiratory rate of state 3 and the rate of ATP synthesis of liver mitochondria isolated were highest in the group fed the diet containing soybean oil.

Animals↗
PubMed1992

Dependence of ultrasonic attenuation of liver on pathologic fat and fibrosis: examination with experimental fatty liver and liver fibrosis models.

To clarify the effect of the pathological state of the liver on ultrasonic attenuation, we produced two experimental rabbit models. The influence of fat on ultrasonic attenuation was examined using a fatty liver model without liver fibrosis, and that of fibrosis on attenuation using a liver fibrosis model without fatty infiltration. Ultrasonic data were obtained in vivo directly from the liver, and an acoustic attenuation coefficient slope was obtained by the spectral difference method. Tissue components of the liver, namely the total lipid, hydroxyproline and water contents, were measured precisely by quantitative methods. We revealed that ultrasonic attenuation depends mainly on fatty infiltration of the liver and to a lesser extent on fibrosis, but not on the water content.

Adipose Tissue↗
PubMed1992

Computer-assisted two-dimensional analysis of gastric mucosal hemoglobin distribution using electronic endoscopy.

An electronic endoscope was modified to assess the imaging of two-dimensional distribution of gastrointestinal mucosal hemoglobin with the aid of a computer and image analyzing system. The band-pass filters ranging from 530-470 nm (G'), and 770-830 nm (IR) replaced ordinary filters in a conventional electronic endoscope (Olympus V-10 or EVIS-200). As the hemoglobin is the most abundant biological pigment in the gastrointestinal mucosa absorbing the green light with little absorption in the infrared region, we used the algorithm of 32 [log2(Vir/Vg)] as a reflection of hemoglobin content in the surface mucosa. The algorithm had a good correlation with the spectrophotometrically measured hemoglobin concentration. The mucosal distribution of hemoglobin was displayed in patients with gastric ulcer. In conclusion, the computer and image analyzing system were successfully applied in an attempt to determine gastric mucosal hemoglobin content and its distribution. The possible applications of computers in endoscopic image analysis are discussed.

Adult↗
PubMed1992

Portal vein aneurysm demonstrated by blood pool SPECT.

Portal vein aneurysms are rare and are occasionally suggested by ultrasound and usually confirmed by invasive angiography. Such a case was diagnosed by scintigraphic studies, most importantly blood pool SPECT, which clearly separates it from hepatic cysts.

Adult↗
PubMed1992

Ethanol stimulates immunoreactive endothelin-1 and -2 release from cultured human umbilical vein endothelial cells.

The present study employed enzyme-immunoassay to examine the effect of ethanol on endothelin-1 and/or -2(ET1 + 2) release from human umbilical vein endothelial cells. Thirty minutes of exposure to ethanol increased the release of immunoreactive ET1 + 2 from cultured endothelial cells in a dose-dependent manner. However, ethanol at concentrations of less than 400 mM did not induce any LDH release from the endothelial cells. Trypan blue exclusion test revealed that 400 mM solution of ethanol decreased the cell viability to 7.7%. Thus, ethanol was found to directly stimulate ET1 + 2 release from cultured human umbilical vein endothelial cells. This reaction of vascular endothelial cells against ethanol may be related to ethanol-induced cardiovascular diseases such as hypertension, myocardial infarction and stroke, as well as fatal alcohol syndrome.

Cells, Cultured↗
PubMed1992

Role of atrial contraction and synchrony of ventricular contraction in the optimisation of ventriculoarterial coupling in humans.

OBJECTIVE: To examine the effects of pacing modes on the interaction between the left ventricle and arterial system in humans. DESIGN: The slope of the end systolic pressure-volume relation (end systolic elastance), effective arterial elastance, the ratio of effective arterial elastance to end systolic elastance, and mechanical energy efficiency were compared under different pacing modes (atrial, atrioventricular, and ventricular). PATIENTS: Nine male patients with sick sinus syndrome who had cardiac catheterisation for diagnosis and to see whether they needed a pacemaker. INTERVENTIONS: A conductance catheter with tip-manometer was inserted into the left ventricle to obtain pressure-volume loops, and two pacing catheters were inserted into the right atrium and into the right ventricle respectively. RESULTS: End systolic elastance was lower in atrioventricular pacing than in atrial pacing, but effective arterial elastance was not significantly different. End systolic elastance was lower in ventricular pacing than in atrioventricular pacing, and effective arterial elastance was higher in ventricular pacing than in atrioventricular pacing. Consequently the ratio of effective arterial elastance to end systolic elastance was lowest in atrial pacing and highest in ventricular pacing, and mechanical energy efficiency was highest in atrial pacing and lowest in ventricular pacing. CONCLUSIONS: Atrial contraction and synchronous ventricular contraction independently optimise ventriculoarterial coupling in terms of a transfer of energy. Thus atrial pacing gives the best ventriculo-arterial coupling among these pacing modes.

Adult↗
PubMed1992

Oncotic pressure regulates gene transcriptions of albumin and apolipoprotein B in cultured rat hepatoma cells.

The mechanism of the accelerated syntheses of albumin and apolipoprotein B (apo B) in response to decreased oncotic pressure was investigated in cultured rat hepatoma H4-II-E cells. Addition of dextran (mol wt 6-9 x 10(4)) to the culture medium decreased the levels of albumin and apo B mRNAs in an oncotic pressure-dependent manner. The reductions of both mRNAs were attenuated with increase in the molecular weight of dextran, which resulted in a decrease in oncotic pressure. Addition of macromolecule increased the viscosity in medium; however, alteration of viscosity appeared not to correlate with albumin and apo B mRNA levels. Transcriptional run-on assays with isolated nuclei from dextran-treated vs. untreated hepatoma cells indicated that the changes in steady-state mRNA levels were mainly controlled at the transcriptional step. Treatment with cycloheximide increased albumin mRNA to the basal level, which was effectively suppressed by dextran, and resulted in superinduction of apo B mRNA. These changes occurred primarily at the transcriptional step. These results suggest that regulations of the expressions of the albumin and apo B genes for adaptive increases in the mRNAs may require the continued synthesis of a labile protein(s) or a limiting transcription factor(s). We conclude that oncotic pressure plays an important role in regulation of expression of the albumin and apo B genes at the transcriptional step.

Animals↗