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Biomedical subjects

T Kasai

Publications and source records attributed to T Kasai.

At least 91 records · Page 5Linked to original sources
PubMed1999

High-performance liquid chromatography-fluorescence determination of dinitropyrenes in soil after column chromatographic clean-up and on-line reduction.

In order to quantify 1,3-dinitropyrene (DNP), 1,6-DNP and 1,8-DNP in soil, we developed an efficient clean-up procedure and a sensitive determination method using fluorescence detection. DNP isomers were efficiently cleaned by three stages of fractionation, i.e., a silica gel open column chromatography using stepwise elution and two further purification steps by high-performance liquid chromatography (PPLC) using a monomeric-type octadecylsilyl (ODS) column and a polymeric-type ODS column. The recoveries of DNPs during the whole clean-up process were 94% or more. The fraction corresponding to DNPs was injected into an analytical polymeric-type ODS column for HPLC to separate DNP isomers. The effluent from the analytical ODS column was directly introduced to a catalyst column, which was packed with 5 microns alumina coated with platinum and rhodium (Pt-Rh), in order to reduce DNPs to diamino compounds, and then the fluorescence of diaminopyrenes was detected. The immediate detection of diaminopyrene isomers after on-line reduction afforded a sensitive detection of DNP isomers. The detection limits for DNPs were in the range of 0.7 to 4 pg. These developed methods were applied to four soil samples collected at parks in residential areas.

Chromatography, High Pressure Liquid↗
PubMed1999

[Neurotoxicity of 1-bromopropane in rats].

Neurotoxicity of 1-bromopropane (1-BP) used as an alternative solvent of fluorocarbons was experimentally studied. Eight rats in the experimental group were exposed to 1-BP at 1500 ppm for six hours a day, five days a week for four weeks in an exposure chamber. Another eight rats in the control group were exposed to room air in a similar exposure chamber as those in the experimental group. During the latter half of the fourth week of exposure, all the rats in the experimental group showed a loss of body weight and ataxic gait compared with control rats. At the end of the fourth week, the rats in both groups were perfused through the ascending aorta and fixed. The cerebellum, medulla oblongata, spinal cord and peripheral nerve were processed for histopathological studies. No statistically significant difference in the frequency of axonal degeneration in both peroneal and sural nerves was found between the experimental and control groups. In the cerebellum, the frequency of degeneration of Purkinje cells in both the vermis and hemisphere was higher in the experimental group than in the control group (P < 0.05). There was no significant difference in the frequency of myelin ovoids in the fifth thoracic and in the third cervical posterior columns of the spinal cord between control and experimental groups. There was also no significant difference in the frequency of axonal swelling in the nucleus gracilis of the medulla oblongata between control and experimental groups. Ataxic gait was considered to be induced by degeneration of Purkinje cells in the cerebellum due to 1-BP exposure. However, degenerative findings of nerve fibers in the peripheral nerve, spinal posterior column and nucleus gracilis of the medulla oblongata due to 1-BP exposure were not evident. At the end of the fourth week of exposure, rats in the experimental group showed loss of body weight and markedly decreased motor activities, and it was considered that they would die if we continued the exposure into the fifth week. Therefore, we feel that our experimental schedule should be reconsidered before undertaking any further studies on the peripheral nerve toxicity of 1-BP.

Animals↗
PubMed1999

Motor evoked potentials of the first dorsal interosseous muscle in step and ramp index finger abduction.

The present experiment was undertaken to study the change in motor cortex excitability as a function of muscle contraction speed during ramp and step abduction by the index finger. Motor evoked potentials (MEPs) of the first dorsal interosseous muscle elicited by transcranial magnetic stimulation (TMS) were modulated by different muscle contraction speeds. When TMS was delivered at 10% maximum voluntary contraction (MVC), MEP amplitudes were always significantly larger in step than in ramp contractions. These differences were dependent on the amount of background electromyographic activity (EMG), which was significantly larger in step than in ramp contractions. However, using maximum output of TMS (100%) with a trigger level at 10% MVC, these differences disappeared. With a trigger level at 30% MVC, these differences also disappeared in spite of differences in the amount of background EMG between them. These results are attributed to different central motor commands. Motor evoked potential amplitudes are dependent not only on the level of background EMG activity but also on the nature of descending motor commands.

Adult↗
PubMed1999

A rat model of human T lymphocyte virus type I (HTLV-I) infection: in situ detection of HTLV-I provirus DNA in microglia/macrophages in affected spinal cords of rats with HTLV-I-induced chronic progressive myeloneuropathy.

To investigate the pathogenetic role of human T lymphocyte virus type I (HTLV-I) in central nervous system disease, a rat model for HTLV-I-associated myelopathy/tropical spastic paraparesis, designated as HAM rat disease, has been established. Wistar-King-Aptekman-Hokudai strain rats with induced HTLV-I infection develop a chronic progressive myeloneuropathy with paraparesis of hind limbs after an incubation period of 15 months. In the affected spinal cord in these rats, white matter degeneration, demyelination and vacuolar change with microglia/macrophage infiltration are present as are the provirus DNA and the virus mRNA. To identify infected cells in the affected lesions, we carried out in situ hybridization of amplified fragments of the provirus DNA by polymerase chain reaction on thin sections, plus immunohistochemistry on the same sections. The provirus DNA was localized in some microglia/macrophages in the spinal cord lesion. In addition, the HTLV-I provirus was clearly evident not only in ED-1-negative lymphoid cells but also in ED-1-positive macrophages from lymph nodes. These observations suggest that cells of microglia/macrophage lineage may be one of dominant viral reservoirs in the spinal cords and lymph nodes in HAM rat disease. These infected microglia/macrophages may relate to cause the myeloneuropathy through neurotoxic cytokine synthesis.

Animals↗
PubMed1999

Effect of sperm immobilisation and demembranation on the oocyte activation rate in the mouse.

To analyse the effect of the state of the sperm plasma membrane on oocyte activation rate following intracytoplasmic sperm injection (ICSI), three types of human and mouse spermatozoa (intact, immobilised and Triton X-100 treated) were individually injected into mouse oocytes. At 30, 60 and 120 min after injection, maternal chromosomes and sperm nuclei within oocytes were examined. Following human sperm injection, the fastest and the most efficient oocyte activation and sperm head decondensation occurred when the spermatozoa were treated with Triton X-100. Intact spermatozoa were the least effective in activating oocytes. Thus, the rate of mouse oocyte activation following human sperm injection is greatly influenced by the state of the sperm plasma membrane during injection. When mouse spermatozoa were injected into mouse oocytes, the rates of oocyte activation and sperm head decondensation within activated oocytes were the same irrespective of the type of sperm treatment prior to injection. We witnessed that live human spermatozoa injected into moue oocytes often kept moving very actively within the ooplasm for more than 60 min, whereas motile mouse spermatozoa usually became immotile within 20 min after injection into the ooplasm. In 0.002% Triton X-100 solution, mouse spermatozoa are immobilised faster than human spermatozoa. These facts seem to suggest that human sperm plasma membranes are physically and biochemically more stable than those of mouse spermatozoa. Perhaps the physical and chemical properties of the sperm plasma membrane vary from species to species. For those species whose spermatozoa have 'stable' plasma membranes, prior removal or 'damage' of sperm plasma membranes would increase the success rate of ICSI.

Animals↗
PubMed1999

Local drug delivery system using ceramics: vacuum method for impregnating a chemotherapeutic agent into a porous hydroxyapatite block.

We performed an experimental study on a new drug delivery system that employs a porous hydroxyapatite block (HAb) (composition: Ca10(PO4)6(OH)2)) to conduct sustained release of a chemotherapeutic agent. To confirm penetration of the agent into the HAb (2 cm3), an aqueous solution containing eosin dye was used at various vacuum pressures. To estimate the storage capacity of the HAb, blocks were weighed before and after being impregnated with the aqueous dye solutions, and the capacity of the block was calculated from the increase in weight after vacuum. In this slow-release study using vacuum, the anti-cancer drug methotrexate (MTX) was used in vitro. Four HAb (1 cm3) containing different concentrations of MTX, ranging from 1.22 to 2.38 mg per block, were studied. All were found to release the drug, maintaining a mean concentration of 0.22 to 0.32 microg/ml even after twelve days. This concentration is high enough to be effective against tumor cells. The results suggest that HAb impregnated with a chemotherapeutic agent using a simple vacuum system may serve as a valuable new method of administering local chemotherapy, primarily when used as a strut graft for bone defects. This new drug delivery system can also be used as an adjuvant material in extended curettage, which can also discourage recurrence of benign tumors without any risk of systemic toxicity.

Journal Article↗
PubMed1999

Ingestion of sugar beet fiber enhances irradiation-induced aberrant crypt foci in the rat colon under an apoptosis-suppressed condition.

The induction of aberrant crypt foci (ACF) by irradiation of gamma-rays (60Co), and the effect of dietary sugar beet fiber (SBF) on irradiation-induced ACF were examined. We found that abdominal irradiation of gamma-rays could induce ACF in the rat colon. The irradiation was performed once a week at a dose rate of 2 or 3 Gy per irradiation. Irradiation-induced ACF were observed in the colon at 10 weeks after the first irradiation at dose of 2 Gy for six times or 3 Gy for four times. Dietary SBF had no effect on the number of ACF, aberrant crypts (AC) or AC/focus induced by abdominal gamma-irradiation. However, an ingestion of SBF resulted in an increase in the number of these parameters in apoptosis-suppressed rats by cycloheximide (CHX). An injection of CHX suppressed irradiation-induced apoptosis of the colonic epithelial cells for at least 6 h after the irradiation. In CHX-injected rats, an ingestion of SBF significantly increased the number of ACF, AC and AC/focus compared with fiber-free fed rats at 9 weeks after the first irradiation. On the other hand, in saline-injected rats, no significant difference was found between SBF and fiber-free diets in the number of ACF, AC and AC/focus through the experimental period. These results suggest that dietary SBF may be involved in the elimination of abnormal cells from an irradiated colon through the apoptosis of colonic epithelial cells. In this study, we have shown a new method for inducing ACF by using gamma-rays which were not influenced by luminal contents such as bacterial enzyme, at least in the initiation stage.

Animals↗
PubMed1999

Ingestion of guar gum hydrolysate, a soluble fiber, increases calcium absorption in totally gastrectomized rats.

Gastrectomy induces osteopenia. We examined the effects of feeding a diet containing soluble dietary fiber, guar gum hydrolysate (GGH, 50 g/kg diet), on intestinal calcium absorption and bone mineralization in totally gastrectomized (Roux-en-Y esophagojejunostomy) rats by comparing them with those in two control groups (laparotomized and bypassed rats). In the bypassed rats, chyme bypassed the duodenum and upper jejunum without gastrectomy. In a second separate experiment, we compared calcium absorption and bone mineralization in the gastrectomized rats fed diets containing soluble and insoluble calcium salts and in bypassed rats fed insoluble calcium. In Experiment 1, apparent absorption of calcium supplied as a water-insoluble salt was more than 50% lower in gastrectomized rats than in the intact (laparotomized) or bypassed rats 3 wk after the start of feeding the test diets (P < 0.05). Calcium absorption was higher (P < 0.05) in gastrectomized rats fed the GGH diet than in those rats fed the GGH-free diet. In Experiment 2, absorption of soluble calcium in the gastrectomized rats did not differ from the absorption of calcium from calcium carbonate by bypassed rats. The soluble calcium pool in the cecal contents was significantly lower in gastrectomized rats (Experiment 1) than in intact or bypassed control rats, and was higher (P < 0.05) in the GGH-fed gastrectomized rats than in those fed the GGH-free diet. However, calcium absorption correlated most closely (r = 0.787, P < 0.01) with cecal propionic acid concentration. The femur calcium content was significantly lower in gastrectomized rats fed insoluble calcium than in bypassed rats fed the same diet, but was partially restored in the rats fed soluble calcium (Experiment 2). Bone calcium was not increased by feeding GGH in gastrectomized rats (Experiment 1). We conclude that the severely diminished calcium absorption following total gastrectomy is totally due to a decrease in calcium solubilization, and feeding GGH partially restores calcium absorption. The decrease in bone calcium that occurs as a result of gastrectomy is mainly due to diminished intestinal calcium absorption.

Administration, Oral↗
PubMed1999

Guanidino group is involved in the stimulation of exocrine pancreatic secretion by protamine in normal and chronic bile-pancreatic juice-diverted rats.

We previously demonstrated that the feeding of guanidinated casein, whose lysine residues are converted to homoarginine, stimulates pancreatic secretion much higher than that of intact casein in chronic bile-pancreatic juice (BPJ)-diverted rats, which suggests that the guanidino group is involved in BPJ-independent enhancement of pancreatic secretion. However, the role of the guanidino group in the protein for the enhancement of pancreatic secretion has not been clarified. In this study, we examined the stimulation of pancreatic secretion by a arginine rich dietary protein, protamine (25, 50 mg/ml), and then determined whether the guanidino group in protamine was responsible for the secretory responses in normal and BPJ-diverted rat by comparison with pancreatic secretion between intact and deguanidinated protamine. The deguanidinated protamine was prepared by converting arginine residues of salmon protamine to ornithine using heated hydrazine (conversion rate of arginine residue was 87%). In normal rats, pancreatic protein and chymotrypsin secretion were stimulated in dose-response fashion after a duodenal instillation of native protamine solution (25, 50 mg in 1 ml). In chronic BPJ-diverted rats, native protamine (25 mg) maximally stimulated pancreatic protein and protease secretion. In contrast, deguanidinated protamine (50 mg in 1 ml) did not stimulate pancreatic secretion in both normal and BPJ-diverted rats. In addition, the duodenal administration of arginine, which is equal to the amount contained in 50 mg of native protamine, had no effect on pancreatic secretion in both rats. These results suggest that a naturally occurring protein, protamine, stimulates pancreatic secretion by a luminal BPJ-independent mechanism and that the guanidino group in this protein is responsible for stimulating pancreatic secretion in BPJ-diverted rats.

Amino Acids↗
PubMed1999

[Evaluation of procalcitonin levels in patients with systemic inflammatory response syndrome as the diagnosis of infection and the severity of illness].

To understand the presence or absence of bacterial infection in patients with systemic inflammatory response syndrome (SIRS), the level of procalcitonin (PCT), a precursor of calcitonin, was determined. Subjects consisted of 14 SIRS patients without complication by bacterial infection, 14 SIRS patients complicated by sepsis, and 14 SIRS patients complicated by severe sepsis and septic shock. PCT levels in SIRS patients with sepsis (2.9 +/- 2.3 ng/ml) were significantly higher than those in SIRS patients without complication by infection (0.7 +/- 1.1 ng/ml). However, there were no significant differences in the levels of C-reactive protein (CRP), interleukin 6 (I-6) or tumor necrosis factor-alpha (TNF-alpha) between the two groups. PCT levels in SIRS patients with severe sepsis and septic shock (172.2 +/- 276.3 ng/ml) were significantly higher than those in SIRS patients with sepsis. Levels of CRP, IL-6 and TNF-alpha were also significantly higher in the patients with sepsis compared to those in patients with local infection. Significant correlations were observed between the levels of PCT and those of CRP, IL-6 and TNF-alpha in SIRS patients. It was suggested that to measure the levels of procalcitonin in patients with SIRS is useful to diagnose the infection and severity of illness.

Adult↗
PubMed1999

Development of resistance to chloroform toxicity in male BDF1 mice exposed to a stepwise increase in chloroform concentration.

To investigate the development of resistance to chloroform toxicity, a 4-week inhalation study was conducted in which BDF1 male mice were exposed to a low level of chloroform for an initial two-week period, and thereafter the exposure concentration was increased for a second two-week period. The animals were exposed to inhalation of chloroform vapor 6 hr per day, 5 days per week, with clinical observation and measurement of body weight conducted. These results demonstrate that pre-exposure to chloroform at a low dose level induced resistance to a higher dose of chloroform in male mice. This resistance was dependent on the pre-exposure concentration.

Animals↗
PubMed1999

Dependence of deltoid muscle activity upon initial angles of shoulder abduction prior to flexion.

The present study was undertaken to investigate the hypothesis that the direction and selectivity of an appropriately modified version of shoulder flexion is dependent upon initial angles of shoulder abduction. Analysis indicated that initial small angles of shoulder abduction were associated with longer electromyographic (EMG) durations of the agonist (anterior deltoid) muscle. Moreover, as initial angles became smaller, EMG onsets of the antagonist (posterior deltoid muscle) occurred nearer to those of the agonist. Modulations of duration of the agonist EMG activity can be explained by changes in amplitude of movement. Two possible interpretations of the changes of EMG onset of the antagonist in accordance with different initial angles of shoulder abduction are considered. One concerns the effect of the change on the load of the upper limb, dependent on different angles of shoulder abduction. The second concerns the changing role of the antagonist to a synergist, dependent upon decreased initial angles of shoulder abduction prior to the shoulder flexion. Based on the present findings, it is suggested that angles of shoulder abduction are an important determinant of agonist-antagonist muscle activity of the deltoid during flexion of the shoulder.

Adult↗
PubMed1999

[Pathogenecity of fosfomycin-resistant strains isolated from Escherichia coli].

Two fosfomycin-resistant strains, FRC14 (parent strain, Escherichia coli [E.coli] c73-18) and FRK104 (parent strain, E. coli O124), were isolated from spleens before the bacterial disappearance, after inoculating the parent strains intraperitoneally into mice and treating them with a single oral dose of fosfomycin. The resistant strains were successfully isolated by a replica method from a mass of sensitive cells of respective parent. To elucidate the pathogenesis of the resistant strains, their characteristics were investigated. The MIC of fosfomycin for FRC14 was 25 micrograms/ml (4 times the MIC for the parent) and that for FRK104 was 100 micrograms/ml (8 times the MIC for the parent). The strain FRC14 showed a defective utilization of sn-glycerol 3-phosphate (G3P), but utilization of other carbohydrates was similar to that of the parent strain. Thus, the strain FRC14 seemed to be a glpT mutant. The strain FRK104 did not use variety of carbohydrates including G3P, but used glucose 6-phosphate. The utilization of G3P was recovered in the presence of cAMP. Thus, the strain FRK104 seemed to be a ptsI mutant. These resistant strains were diminished their killing activity for mice in comparison to that of the each parent strain when they were inoculated intraperitoneally. The cell number of FRC14 decreased or disappeared in blood and spleen in mice, while that of the parent increased. The strain FRK104 diminished its ability of producing keratoconjuctivitis in guinea pigs in comparison to that of the parent strain.

Animals↗
PubMed1999

[Detection of culprit lesion in patients with unstable angina pectoris by using ATP thallium-201 myocardial SPECT].

The purpose of this study is to determine the diagnostic accuracy for detection of culprit lesions in patients with unstable angina. Both ATP 201Tl SPECT and coronary angiography were performed in 51 patients with unstable angina pectoris within a week since the last attack. SPECT images were divided into 17 segments and the regional uptakes were scored semiquantitatively (0 = normal to 3 = no activity) and compared with the coronary angiographic findings. ATP 201Tl SPECT revealed decreased uptakes in 54 of 56 culprit lesions. The sensitivity, specificity and accuracy for detection of culprit lesions were 96.4%, 89.5% and 92.4%, respectively. Although adverse effects during ATP administration were complicated in 28 (54.9%) patients, all the complications were mild and resolved within two minutes. ATP 201Tl SPECT is sensitive and reliable method for detecting culprit lesions and can be performed safely even at acute phase in patients with unstable angina pectoris.

Adenosine Triphosphate↗
PubMed1999

Ingestion of guar-gum hydrolysate partially restores calcium absorption in the large intestine lowered by suppression of gastric acid secretion in rats.

We examined the effects of feeding guar-gum hydrolysate (GGH), a highly fermentable form of dietary fibre with low viscosity, on Ca absorption in the small and large intestines in rats under conditions in which gastric acid secretion was suppressed by a proton pump inhibitor, omeprazole. We also examined the role of the caecum in influencing these effects. The study was designed in a 2 x 2 x 2 factorial arrangement with two diet (GGH-containing (50 g/kg diet) and GGH-free diets) groups, two injection (omeprazole and vehicle) groups and two operation (sham and caecectomy) groups. Apparent Ca absorption was lower in rats administered omeprazole (30 mg/kg body weight per d) for 8 d than in rats administered the vehicle. Ingestion of GGH led to partial restoration of Ca absorption decreased by omeprazole treatment. However, this increment in Ca absorption was not sufficient to meet requirements because the dietary Ca level (3.0 g/kg diet) was the minimum requirement for the intact rats. The small increment in Ca absorption caused by the GGH diet was completely abolished by caecectomy. Soluble Ca pools in the caecal and colonic contents were increased by feeding GGH, and the soluble Ca concentrations were much higher than the Kt values of the Ca active transport system in the large intestine or the serum Ca concentration. These findings suggest that Ca solubilization is not a limiting factor for Ca absorption in the large intestine. Apparent Mg absorption was clearly lower in caecectomized rats than in sham-operated rats, and higher in the GGH-fed groups than in the groups fed on the GGH-free diet, even in the case of caecectomized rats. We conclude that Ca absorption lowered by inhibition of gastric acid secretion is partially restored in rats fed with GGH, but the increment is not sufficient to meet requirements.

Animals↗
PubMed1998

Increased activity of oleate-dependent type phospholipase D during actinomycin D-induced apoptosis in Jurkat T cells.

Apoptosis is an active form of cell death that can be induced by a wide variety of agents and conditions. In response to actinomycin D, hydrogen peroxide (H2O2), or TNF-alpha, Jurkat T cells underwent typical apoptosis. Phospholipase D (PLD) activity in intact cells determined by phosphatidylbutanol generation was up-regulated by these agents. The PLD activation was in a time-dependent manner during apoptosis. It was also shown that the PLD activity measured by using exogenous substrate in the lysate from apoptotic cells was higher than that in the lysate from control untreated cells. The PLD activity in lysate from control untreated cells was stimulated by unsaturated fatty acids (UFA), but not by guanosine 5'-O-(3-thiotriphosphate). However, the PLD activity in the apoptotic cell lysate was no longer enhanced by the addition of oleate, suggesting that the increased PLD activity during apoptosis was attributed to the PLD of UFA-dependent type, but not the small G protein-dependent one. In fact, the release of free UFA was increased during apoptosis. The caspase inhibitors, z-DEVD and z-VAD, effectively suppressed PLD activation and apoptosis, but UFA release was unaffected. These results suggest the possibility that UFA-dependent type PLD may be implicated in apoptotic process in Jurkat T cells. This is the first demonstration that the PLD of UFA-dependent type would be involved in cellular responses.

Apoptosis↗
PubMed1998

Early development of Epstein-Barr virus-associated T-cell lymphoma after a living-related renal transplantation.

We herein report a case of Epstein-Barr virus (EBV)-associated T-cell lymphoma that developed within a month after a kidney transplantation. The recipient was a 37-year-old man who had evidence of a previous EBV infection. Cyclosporine, methylprednisolone, and azathioprine were used for immunosuppression, and acute rejection was treated with high-dose methylprednisolone. The lactate dehydrogenase level started to increase on day 24 and thereafter peaked on day 37 while also demonstrating progressive jaundice and a bleeding tendency. A transplant nephrectomy was done on day 37; however, the patient could not recover and eventually died of respiratory failure as a result of diffuse pulmonary edema. A pathological examination of the resected kidney revealed a diffuse proliferation of large atypical lymphoid cells in the parenchyma. Immunohistochemically, the tumor cells were positive for CD45 and T-cell marker, CD45RO, but negative for B-cell markers. EBV-encoded RNA was demonstrated within the neoplastic cells by in situ hybridization.

Adult↗