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Biomedical subjects

H Maezawa

Publications and source records attributed to H Maezawa.

At least 55 records · Page 3Linked to original sources
PubMed1991

Thallium-201 stress scintigraphy in Takayasu arteritis.

Thirty-eight women with Takayasu arteritis were studied using thallium-201 stress myocardial scintigraphy to assess the prevalence and pathophysiology of the perfusion abnormality. Twenty (53%) had abnormal scintigraphic findings (group A). Abnormal scans were divided into 3 groups: permanent defects in 6, reversible defects in 7 and slow washout in 7. The remaining 18 patients had normal scintigrams (group N). Group A had a tendency to be older and to have a high prevalence of complicated significant aortic regurgitation. Interventricular thickness plus left ventricular posterior wall thickness (26 +/- 7 vs 17 +/- 2 mm, p less than 0.01) and left ventricular mass (267 +/- 121 vs 133 +/- 39 g, p less than 0.01) were all greater in group A on echocardiography. The mean value of the central aortic pressure in systole was 170 +/- 15 mm Hg in the 7 catheterized patients in group A. Coronary ostial stenoses were present in 2 group A patients who showed reversible defects on scintigrams. These data indicate that the abnormal perfusion detected by imaging in patients with Takayasu arteritis was responsible for a decrease in coronary reserve or myocardial damage, or both, due to long-standing systemic hypertension or aortic regurgitation. Coronary artery disease should be considered if a reversible defect is present.

Adult↗
PubMed1991

Organic anion transport study in mutant rats with autosomal recessive conjugated hyperbilirubinemia.

The EHBR is a mutant rat strain with congenital conjugated hyperbilirubinemia bred from a Sprague-Dawley rat. Transport of conjugated bilirubin, indocyanine green, and tetrabromosulfophtalein from liver to bile is severely impaired in these rats. Serum bilirubin amounts to 6.0 +/- 0.05 mg/dl (n = 4) in adult rats, with 97% conjugates. The bile flow is reduced to about 65% of the control group, whereas total bile acid in 10-min bile samples is similar. Liver histology of 10 week-old rats revealed neither intracellular pigmentation nor architectural abnormalities.

Animals↗
PubMed1991

Serum ketone response to glucagon as a marker of insulin dependency in diabetics.

The serum ketone response to glucagon was measured in 10 patients with IDDM and 37 with NIDDM. In both groups, serum 3-hydroxybutyrate increased significantly after intravenous injection of 1 mg glucagon. The difference between the serum level of 3-hydroxybutyrate at 30 min and basal level [delta 3-OHBA(30')] was 133 +/- 25 mumol/l in the patients with IDDM, 13 +/- 8 mumol/l in those with NIDDM treated by diet alone or with oral hypoglycemic agents and 23 +/- 13 mumol/l in those with NIDDM treated with insulin. The delta 3-OHBA(30') was significantly greater in IDDM patients than in both groups of NIDDM patients (P less than 0.001). The delta 3-OHBA(30') was greater than 87 mumol/l in eighty percent of IDDM patients, but smaller than 87 mumol/l in both groups of NIDDM patients. The delta 3-OHBA(30') was correlated with the difference between the plasma level of C-peptide at 6 min and basal level [delta CPR(6')] (r = -0.540, P less than 0.001). The delta 3-OHBA(30') was not correlated with fasting plasma levels of glucose, fructosamine or hemoglobin A1c. These observations show that measurement of the serum ketone response to glucagon is a useful marker of insulin dependency. In order to determine insulin dependency, the simultaneous measurement of concentrations of ketones and C-peptide is indicated during the glucagon stimulation test.

3-Hydroxybutyric Acid↗
PubMed1991

Effects of K-shell X-ray absorption of intracellular phosphorus on yeast cells.

The effects of K-shell absorption of phosphorus atoms on yeast cells were investigated using synchrotron X-rays that were tuned to the resonance absorption peak (2153 eV). Three types of cellular effect (cell inactivation, induction of gene conversion at the trp-5 locus, and cell membrane impairment (changes in the permeability] were measured. It was demonstrated that the enhancement factor was 1.4 at the resonance peak regarding both lethality and the induction of gene conversion in reference of off-peak irradiation (2146 and 2160 eV). No difference was found between the two off-peak irradiation energies. No cell membrane impairment was detected, irrespective of the X-ray photon energies employed within the fluence range tested. These results strongly suggest that K-shell X-ray absorption in the resonance mode by cellular phosphorus atoms causes significantly more cellular effects than the off-resonance mode of absorption, probably via some specific changes induced in the phosphates of the DNA strand. Calculations using the number of phosphorus atoms in a defined size of the trp locus (2127 base pairs) on the DNA and the absorption cross-section of the resonance mode of phosphorus showed that gene conversion is inducible at a rate of 0.13 per X-ray photon absorption per locus. These results are discussed regarding the modes of K-shell photoabsorption.

Absorption↗
PubMed1991

Biological effects of Auger processes of bromine on yeast cells induced by monochromatic synchrotron X-rays.

The biological effects of inner-shell ionization in bromine atoms incorporated into DNA in the form of bromodeoxyuridine monophosphate (BrdUMP), induced by monochromatized synchrotron X-rays, were studied using a deoxythymidine monophosphate (dTMP)-permeable mutant of yeast, Saccharomyces cerevisiae. The BrdUMP-incorporated yeast cells were irradiated with monochromatic X-rays of 13.51 or 13.45 keV, between which the bromine K-absorption edge (13.47 keV) is located. The cells were 1.07 times more sensitive to irradiation by 13.51 keV X-rays than at 13.45 keV, while dTMP-incorporated cells did not show any difference in sensitivity. In the presence of a radioprotector during irradiation, BrdUMP-incorporated cells showed a larger enhancement (1.20). These enhancements observed in the bromine-incorporated cells cannot be explained only by an increase of the absorbed dose due to a substitution of CH3 group of thymine by bromine. It may be concluded that a major part of the enhancement was caused by inner-shell photoionization, followed by an Auger cascade of the bromine in the DNA. The quantum yield of lethality caused by the photoabsorption of bromine K-shell is not affected by the presence of cysteamine, suggesting the biological enhancement by the Auger processes may not be influenced by chemical protection.

Bromodeoxyuridine↗
PubMed1991

Enhanced killing effect on 5-bromodeoxyuridine labelled bacteriophage T1 by monoenergetic synchrotron X-ray at the energy of bromine K-shell absorption edge.

5-Bromo-2'-deoxyuridine labelled bacteriophage T1 was irradiated with monoenergetic X-rays obtained from synchroton radiation with the energies at 13.51 keV and 12.40 keV, just above and below the K-shell absorption edge (13.41 keV) of bromine, respectively. Phage samples were irradiated under three conditions, wet N2 gas, dry N2 gas and in vacuum, with water contents (g H2O/g sample) of 60, 2.6 and 0%. At 12.40 keV the D0 in kGy were 1.1 ("wet"), 1.9 ("dry") and 2.5 ("vacuum") for the Br-labelled phages and 1.6 ("wet"), 2.4 ("dry") and 6.2 ("vacuum") for unlabelled phages. The results clearly demonstrated that the X-ray sensitivities decreased with decrease in water contents. Br-enhancement ratios, ER = D0 (unlabelled)/D0 (Br-labelled), varied from 1.4 ("wet", 12.40 keV) to 2.5 ("vacuum", 13.51 keV). Auger enhancements which were defined by energy-dependent enhancement factor, Fen = [ER(13.51 keV)-ER(12.40 keV)]/ER(12.40 keV), were 0.09 +/- 0.09, 0.29 +/- 0.07 and 0.02 +/- 0.03 under "wet", "dry" and "vacuum" conditions, respectively. The change in Auger enhancement under "dry" condition in comparison with "wet" condition could be explained due to less of water. However the Auger enhancement decreased sharply under "vacuum" condition as the water content was zero. The reason for the sharp decrease in Auger enhancement under "vacuum" condition is difficult to understand. A possible explanation is discussed in the text.

Bromodeoxyuridine↗
PubMed1991

Increased thrombomodulin values in plasma of diabetic men with microangiopathy.

To study the significance of plasma thrombomodulin (TM) values in diabetes mellitus, we determined plasma TM in 34 patients with non-insulin-dependent diabetes mellitus (NIDDM) men, mean age 54 (SE 2) years. Plasma TM was determined by an enzyme immunoassay with anti-TM monoclonal antibodies. The plasma TM values were significantly greater in NIDDM patients with nephropathy than in patients without nephropathy (P less than 0.001). Also, a significant positive correlation was noted between the concentration of plasma TM and serum creatinine (r = 0.55, P less than 0.001). The plasma TM values of the patients with retinopathy were significantly greater than the values of those without it (P less than 0.002). Furthermore, we noted a significant positive correlation (r = 0.78, P less than 0.001) between plasma TM and the severity of diabetic retinopathy as graded by Scott's classification. These results suggest a close relationship between TM and diabetic microangiopathy.

Adult↗
PubMed1991

Study on cholesteryl ester transfer activity in coronary heart disease.

The net cholesterol transfer activity from high density lipoprotein (HDL) to low density lipoprotein (LDL) was determined in the patients with coronary heart disease (CHD) to examine its effect on the pathogenesis of arteriosclerosis. Furthermore, in the CHD patients with high HDL cholesterolemia (more than 60 mg/dl), the HDL particle size was measured by high performance liquid chromatography. A significant cholesteryl ester transfer activity (P less than 0.02) was noted in the CHD patients with low HDL cholesterolemia (less than 60 mg/dl). The rate of cholesteryl ester transfer activity (cholesteryl ester transfer activity/hour) inversely correlated with the serum HDL cholesterol value (r = -0.483, P = 0.096) in the patients with CHD. These results suggest that an increase of CETA caused a low HDL cholesterol value in the CHD patients with low HDL cholesterolemia and it may have the risk of causing CHD. However, an increase of the CETA was not found in the CHD patients with high HDL cholesterolemia compared to the normal subjects, the HDL particle size being significantly greater than that in the normal subjects. In the CHD patients with high HDL cholesterolemia, the large size of HDL may have the risk of causing CHD.

Apolipoproteins↗
PubMed1990

Degradation and metabolism of indocyanine green: high-pressure liquid chromatographic analysis.

Degradation of indocyanine green solution by exposure to light was studied by high-pressure liquid chromatography. Indocyanine green in an aqueous medium exposed to light changed rapidly into an unknown product. The plasma clearance rate and the biliary excretion rate of the unknown product were much slower than those of indocyanine green. Spectrophotometric scan revealed that the unknown product had almost the same absorption spectrum as indocyanine green. Therefore, if degraded indocyanine green solution were to be used in a liver function test, the clearance of indocyanine green assayed by spectrophotometry would apparently be much lower than that of undegraded indocyanine green. According to fast atom bombardment mass spectrometry, the molecular weight of the unknown product was 723, whereas that of indocyanine green was 775. The analysis of rat bile after injection of indocyanine green by high-pressure liquid chromatography revealed that about 1% of the administered indocyanine green was metabolized in the rat liver.

Animals↗
PubMed1989

[Influence of local hyperthermia combined with radiation on tumor growth and lung metastases of transplantable Lewis lung carcinoma growing in hind legs].

The influence of combination of local hyperthermia and radiation on tumor growth and metastases was studied using Lewis lung carcinoma. Tumors growing intramuscularly in the right hind legs of C57BL/6 mice were irradiated at 10 Gy of radiation dose and immersed in a water bath. Time and number of development of metastases were determined according to size and number of lung colonies at 19 days after tumor implantation. Local hyperthermia at 42.8, 43.3 or 43.5 degrees C for 30 min immediately after or before irradiation enhanced the growth delay of tumor with irradiation or with hyperthermia alone. Development of metastases several days after heating was also inhibited by the combination of heating and irradiation. These effects were diminished with hyperthermia applied 3 hr or more after irradiation. Promotion of metastases around the time of heating by severe hyperthermia with above 43.3 degrees C alone was not inhibited by combination with radiation, regardless of their sequence. Radiation had no effect on the number of metastases developed by the heating. However, irradiation 48 hr or more before severe heating reduced the number of metastases developed by the heating.

Animals↗
PubMed1989

Electrophysiological properties of isolated rat liver cells.

The electrophysiological properties of isolated rat liver cells were studied using the patch clamp method in whole-cell configuration. The membrane potential in isolated hepatocytes was -42 +/- 7 mV (n = 20). The input resistance (Rin) and the time constant (tau m) were 51 +/- 17 M (the range of 34 to 180 M omega) (n = 20) and 4.2 +/- 1.0 msec (the range of 3 to 16.5 ms) (n = 20). Assuming that the specific membrane capacitance is 1 microF/cm2, the membrane resistance and membrane capacitance were 42. +/- 9.0 K omega cm2 and 87 +/- 27 pF. These values indicate that isolated rat hepatocytes are not abnormally permeable or leaky. The current-voltage relationship was linear with no rectification. The depolarizing pulse from the resting potential did not induce fast or slow inward currents even when norepinephrine or high Ca2 (3.6 mM) were applied. This indicates that there is no voltage-sensitive Ca2+ channel in the isolated hepatocytes.

Animals↗
PubMed1989

Induction of chromosome aberrations in human lymphocytes by monochromatic X-rays of quantum energy between 4.8 and 14.6 keV.

The induction of chromosome aberrations was studied in human peripheral blood lymphocytes irradiated in vitro with synchrotron-produced monochromatic soft X-rays of quantum energy in a range between 4.8 and 14.6 keV. These X-rays were more effective in producing chromosome aberrations (dicentrics and rings) than 60Co gamma-rays. The efficiency increased with increasing LET of the photoelectrons and their associated Auger electrons, reaching a maximum at a track average LET (L delta = 100, T) of around 4 keV/microns, and tended to decrease or become rather refractory with further increase of LET. This unique LET dependency was consistent with the dual nature of chromosome aberration formation, and interpreted as a reflection of a limited range of photoelectrons as compared with the size and intranuclear geometry of the elemental chromatin fibres as vehicles of damage interaction.

Chromosome Aberrations↗