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Biomedical subjects

H Ohyama

Publications and source records attributed to H Ohyama.

At least 91 records · Page 5Linked to original sources
PubMed1994

Radiosensitivity of CD45RO+ memory and CD45RO- naive T cells in culture.

Radiosensitivities of various human T-cell subsets were investigated by a proliferation assay and by a single-cell gel electrophoresis assay. Each T-cell subset was purified using a cell sorter and was induced to proliferate by ionomycin and interleukin 2. Unsorted T cells showed biphasic dose-survival curves, indicating the heterogeneity of T cells in terms of radiosensitivity. Purified CD4+ helper and CD8+ killer T cells showed similar biphasic dose-survival curves. Hence both T-cell subsets were composed of cells of different radiosensitivity. The T-cell subsets belonging to different activation stages such as CD45RO+ memory and CD45RO- naive T cells had different dose-survival curves. The former was more radiosensitive than the latter. The high radiosensitivity of CD45RO+ cells was also demonstrated by single-cell gel electrophoresis after irradiation. This is the first demonstration that a particular cell surface marker on T cells is correlated with greater radiosensitivity.

Antigens, CD↗
PubMed1993

Effects of dietary vitamin E on clinical course and plasma glutamic oxaloacetic transaminase and glutamic pyruvic transaminase activities in hereditary hepatitis of LEC rats.

Long-Evans Cinnamon (LEC) rats are autosomal recessive mutants that develop hepatitis and hepatocellular carcinoma. Because copper accumulates in the livers of these rats, and some of their clinical and pathological features are similar to those of patients with Wilson's disease, LEC rats are proposed as an animal model of Wilson's disease. It has been thought that unbound copper generates free radicals, which act as hemolytic and hepatocytotoxic agents. To examine the effects of vitamin E as an antioxidant on hereditary hepatitis in LEC rats, we fed 3-week-old rats for 25 weeks either vitamin E-deficient, control, or vitamin E-supplemented diets which contained < 0.01 mg of total tocopherols, 2 mg of d,l-alpha-tocopheryl acetate (2 I.U.), and 58.5 mg of d,l-alpha-tocopheryl nicotinate (50 I.U.), respectively, per 100 mg of feed. In males, body weight loss was first observed in the vitamin E-deficient group, and mean ages at which jaundice occurred were in the order: deficient younger than control younger than supplemented groups. The ages when plasma glutamic oxaloacetic transaminase and glutamic pyruvic transaminase activities began to increase sharply and peaked followed the same order. Thus, it is likely that free radicals are involved in jaundice and hepatitis in LEC male rats, and they are a model for studying the relationship of copper, free radicals, and hepatitis. Conversely, in females, no apparent differences in clinical and biochemical changes were observed among the three groups. Causes for the discrepancy between the sexes remain to be clarified.

Alanine Transaminase↗
PubMed1992

Effects of brain natriuretic peptide and C-type natriuretic peptide infusion on urine flow and jejunal absorption in anesthetized dogs.

Effects of brain natriuretic peptide (BNP) or C-type natriuretic peptide (CNP) on urinary excretion and jejunal absorption of fluid and electrolytes were examined in anesthetized dogs. Intravenous infusion of BNP increased urinary fluid and electrolyte excretion and decreased jejunal fluid and electrolyte absorption. CNP had a similar effect on jejunal absorption as BNP. However, CNP had no significant effect on renal fluid or electrolyte excretion. These results indicate that: 1) BNP is a powerful natriuretic peptide comparable to ANP and; 2) CNP may also contribute to the regulation of body fluid homeostasis by way of inhibiting net jejunal fluid and electrolyte absorption.

Animals↗
PubMed1990

Effects of portal infusion of hypertonic solution on jejunal electrolyte transport in anesthetized dogs.

Jejunal electrolyte absorption was measured in the jejunal loops of anesthetized dogs during infusions of hypertonic solutions via the portal vein. The net Na absorption was not influenced by the 9% NaCl infusion into the inferior vena cava, although it was significantly attenuated by the portal 9% NaCl infusion. This effect may not be due to the osmotic stimulus, since the portal 50% glucose or 6.5% LiCl infusion had no significant influence on the net Na absorption. To determine the mechanism of the decrease in the net Na absorption during the portal hypertonic NaCl infusion, the net Na absorption was measured after the section of anterior and posterior hepatic nerves (SAPH) or intravenous atropine injection. Both SAPH and the intravenous atropine injection completely blocked the effect of the portal 9% NaCl infusion on the net Na absorption. These results indicate that 1) net Na absorption in dog jejunum is depressed by the hypertonic NaCl infusion via the portal vein; 2) the effect is NaCl specific and may not be due to the osmotic stimulus; and 3) the afferent limbs of this effect are the anterior and posterior hepatic nerves, and the efferent limb of this effect is the vagus nerve. Thus the hepatojejunal reflex may play an important role in the regulation of body fluid homeostasis.

Absorption↗
PubMed1990

Resection after intraarterial chemotherapy of a hepatoblastoma originating in the caudate lobe.

A rare case of hepatoblastoma originating in the caudate lobe was treated successfully with intraarterial chemotherapy followed by extensive lobectomy of the left side of the liver. Imaging modalities demonstrated a solitary huge tumor, initially inoperable, occupying almost the entire liver in a 4-month-old female infant. Transcatheter intrahepatic arterial chemotherapy with 10 mg doxorubicin, 20 mg cisplatin, and 3 ml Lipiodol, repeated twice at a 1-month interval, led to a remarkable reduction in tumor size and thereby made it resectable. The volume ratio between the intact hepatic parenchyma and the tumor changed from 1:1.70 to 1:0.13, as assessed by serial computed tomography scans, and the patient's initial alpha-fetoprotein level of 223,210 ng/ml declined to 53 ng/ml. The present case is the first in the literature, to our knowledge, of a resected hepatoblastoma in the caudate lobe. Clinical details of the tumor and surgical issues are discussed.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1988

Radiation-induced interphase death of rat thymocytes is internally programmed (apoptosis).

Thymocytes are highly radiosensitive and show 'interphase death' within a few hours after low doses of irradiation. However, the mechanisms responsible for this type of death remain ill-defined. Separation of the dead thymocyte fraction from irradiated thymocyte suspensions by centrifugation on Percoll gradients provided homogeneous populations of dead cells suitable for detailed study. Using this method, radiation-induced interphase death of thymocytes was found to involve a sharp but transient increase in buoyant density, concomitant with the appearance of distinctive morphologic changes which included disappearance of microvilli and blistering of the cell surface. The chromatin in the dead cells had a molecular weight sufficiently low to resist sedimentation, and consisted of short oligonucleosome chains. We were unable to detect populations of cells intermediate between the dead and normal in the above characteristics. Interphase death thus involves a discrete, abrupt transition from the normal state and is not merely the consequence of progressive and degenerative changes. Furthermore, immediate cessation of development of interphase death by cycloheximide suggested a possible involvement of protein synthesis on this transition step.

Animals↗
PubMed1987

A direct determination of taurine in perchloric acid-deproteinized biological samples.

A high-performance liquid chromatographic method was developed to estimate the amount of taurine in tissue extracts and body fluids. Shodex Ionpak C-811, an adsorption-distribution type column, was chosen and combined with 3 mM perchloric acid as the mobile phase. The eluted taurine was derivatized with o-phthaladehyde-2-mercaptoethanol reagent and measured at an absorbance of 350 nm instead of fluorescent intensity. Using this method, it was possible to isolate and estimate the amount of taurine from other coexisting substances or structural analogs such as hypotaurine, cysteamine, or cysteinesulfinic acid. For rapid routine assays of taurine in many biological samples, it is advisable that the tissue extracts be pretreated with cation-exchange resin to exclude other interfering substances including O-phosphoserine. The linear relationship between the concentration of taurine and absorbance achieved over the concentration range 0.1-10.0 nmol and the recoveries obtained were 98-101% by the internal standard method. The specificity, reproducibility, and sensitivity of this method for taurine were good enough to be used for biological applications. Examples of the tissue levels of taurine in various organs of the rat, as determined by this new method, are also presented.

Animals↗
PubMed1987

[Effect of septal lesions on the hippocampal EEG and behavior during DRL learning in the rabbit].

We had reported that hippocampal high frequent activity at 8-10 Hz (alpha-burst) appeared during approach and lever press with the progress of DRL learning. In this study, effect of bilateral septal lesions on hippocampal EEG (especially on alpha-burst) and behavior during 10 second DRL learning was investigated in thirteen rabbits. Using the atlas of Sawyer et al., bipolar electrodes were implanted chronically in bilateral septum at coordinates of A 1-2, L 1 and D 10-11 and dorsal hippocampus at P 3-5, L 4-6 and D 7-8. Septal lesion was made by using 8-mA DC currents for 15-50-sec period enough to abolish hippocampal theta activity. DRL learning was performed after septal lesions in five rabbits. In this group, acquisition of learning was disturbed and rhythmic slow activity of the hippocampus was markedly reduced. However, movement itself was not disturbed. Although hippocampal activity recovered gradually with the progress of session, alpha-burst was not observed by the 70th session. In eight rabbits, septal lesions were made after completion of DRL learning which required 40-50 sessions. In this group, the preservation of DRL learning was disturbed and relearning was not completed by the 30th session after septal lesions. Hippocampal rhythmic activity was remarkably reduced and alpha-burst was disappeared. But, voluntary movement itself was not altered. There are several theories concerning with hippocampal rhythmic slow activity. Some author emphasized that hippocampal rhythmic activity appeared at the time of voluntary movement and it had close relation to voluntary movement.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Radiation-induced formation of apoptotic bodies in rat thymus.

The process of interphase death of thymocytes in whole-body X-irradiated rats were studied. Cell size distribution analysis indicates that cell fragments (= apoptotic bodies) appeared in the thymus and increased in number depending on dose (200-1000 R) and time (2-6 hr) after irradiation with corresponding decrease in normal-size thymocytes. Occurrence of nuclear fragmentation in association with the cellular fragmentation was proved with cytofluorometric determination of DNA content in individual cells. Scanning electron microscopic observations also revealed extensive fragmentation of cells in the irradiated rat thymus. The results show clearly that cells as well as nuclei fragment rapidly into smaller pieces of various sizes in the irradiated rat thymus as commonly observed with apoptosis.

Animals↗
PubMed1985

[CT-guided stereotaxic evacuation of cerebellar hematoma--lateral approach].

Stereotaxic lateral approach for cerebellar hematoma is presented using Leksell's CT-stereotaxic system. All of the procedures are performed in the CT room. Patient's head is turned to contralateral side of the hematoma 30 to 40 degrees with slight flexion of the neck. Stereotaxic apparatus is secured to the head under local anesthesia. Hematoma is confirmed by computerized tomograms. Three dimensional coordinates of the target point (center of the hematoma) are measured from the vertical and diagonal rods of Leksell's system. Linear skin incision 4 cm in length is made on retromastoid area. Burr-hole is put on just lateral position of the target point, usually 5 to 6 cm posterior and 1 cm above from the external auditory meatus. Transverse or sigmoid sinus does not appeared through the burr-hole by this approach. Specially made Dandy's cannula (3.0 mm in diameter, 220 mm in length) is inserted into the target point, and manual evacuation of the hematoma is performed carefully using a syringe. Then Dandy's cannula is replaced by silastic drainage tube (3.5 mm in diameter), and 6,000 Units of Urokinase solved in 2 ml of saline is administered to the hematoma cavity. Dissolved hematoma is aspirated every 24 hours until the most of the hematoma is evacuated. We operated three cases of cerebellar hematoma by this method with favorable results. Advantages of this method are as follows: Operative invasion is minimal; The surgeon can check the residual hematoma and position of the tip of cannula even at operation, if necessary.

Aged↗
PubMed1985

[EEG findings in moyamoya disease in children--with special reference to the genesis of re-build up].

EEG findings in Moyamoya diseases in children are characterized by build up during hyperventilation and re-build up after hyperventilation. We examined EEG, tcPO2, tcPCO2 and respiratory curves during and after hyperventilation in 10 cases of typical Moyamoya disease in children. In all of the cases, tcPCO2 decreased gradually by hyperventilation, and its level was about 50% of the pre-hyperventilation level at the end of hyperventilation. It took about five minutes for the tcPCO2 level to return to the pre-hyperventilation level. On the other hand, tcPO2 was increased by hyperventilation. However, it decreased down to 50% of the pre-hyperventilation level within a few minutes after hyperventilation because of the following decrease in the respiratory rate, and it took 5 to 10 minutes to return to the pre-hyperventilation level. Sequential changes in tcPCO2 and tcPO2 showed good correlation with the biphasic change in EEG by hyperventilation in children with Moyamoya disease. The decrease in tcPO2 after hyperventilation seemed in particular to play an important role in the appearance of re-build up. We also examined tcPO2 and tcPO2 during and after hyperventilation in 9 cases of normal children. Sequential changes in tcPCO2, tcPO2 and the respiratory rate were the same as those in children with Moyamoya disease, but re-build up was not observed. In 4 cases of Moyamoya disease we examined the sequential changes in EEG, tcPCO2, tcPO2 and the respiratory rate under the inhalation of 100% O2 and 8% CO2 air.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗