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Biomedical subjects

T Minami

Publications and source records attributed to T Minami.

At least 55 records · Page 3Linked to original sources
PubMed2000

Energy confinement time and heat transport in initial neutral beam heated plasmas on the large helical device

The confinement characteristics of large net-current-free plasmas heated by neutral-beam injection have been investigated in the Large Helical Device (LHD). A systematic enhancement in energy-confinement times from the scaling derived from the medium-sized heliotron/torsatron experiments have been observed, which is attributed to the edge pedestal. The core confinement is scaled with the Bohm term divided by the square root of the gyro radii. The comparative analysis using a dimensionally similar discharge in the Compact Helical System indicates gyro-Bohm dependence in the core and transport improvement in the edge region of LHD plasmas.

Journal Article↗
PubMed2000

Edge thermal transport barrier In LHD discharges

In LHD discharges a significant enhancement of the global energy confinement has been achieved for the first time in a helical device with an edge thermal barrier, which exhibits a sharp gradient at the edge of the temperature profile. Key features associated with the barrier are quite different from those seen in tokamaks: (i) almost no change in particle (including impurity) transport, (ii) a gradual formation of the barrier, (iii) a very high ratio of the edge temperature to the average temperature, and (iv) no edge relaxation phenomenon. These features are very attractive in applying the thermal barrier to future reactor grade devices.

Journal Article↗
PubMed2000

Tea catechins and related polyphenols as anti-cancer agents.

Epigallocatechin gallate (EGCg) and theaflavins, a major constituent of green tea infusion and the constituents of black tea, respectively, were found to inhibit matrix metalloproteinases (MMPs) which are intimately associated with tumor invasion and metastasis. EGCg and related polyphenols exhibited apoptosis-inducing activity for several cancer cell lines including human stomach and colon cancer cells. Comparison of the activity of these compounds revealed the importance of the number and the steric disposition of hydroxyl groups. A pyrogallol-type structure in a molecule is a minimum requirement for apoptosis induction of catechin compounds and that in the B ring has an important role in the activity. These data would provide useful information for designing anti-cancer agents on the basis of anti-inhibitory activity for MMPs and/or apoptosis-inducing activity.

Anticarcinogenic Agents↗
PubMed2000

Expression of hepatocyte growth factor and c-met in ulcerative colitis.

OBJECTIVE AND DESIGN: This study was designed to determine if the hepatocyte growth factor (HGF)-Met system is involved in the repair process of inflamed mucosa of ulcerative colitis (UC) and in the development of UC-associated colorectal cancer. MATERIALS AND METHODS: HGF and c-met gene expressions were quantified in colonic mucosal specimens from healthy control subjects, patients with UC and patients with UC-associated colorectal cancer, using the competitive reverse transcription-polymerase chain reaction. Expression of HGF protein was determined by immunoblot analysis. Expression of c-Met protein was analyzed immunohistochemically. RESULTS: HGF and c-met gene expressions were increased in inflamed mucosa of UC, compared with control subjects. Gene expression of HGF was also increased in the surrounding inflamed mucosa of UC-associated cancers. In cases in which the HGF gene expression was increased, an apparent increase in protein levels of HGF in inflamed mucosa of UC were observed by immunoblot analysis. The c-met gene was overexpressed in UC-associated cancers and a high level of immunoreactivity of the c-Met protein was immunohistochemically detected within the cancer cells. CONCLUSION: We showed that HGF and c-met expression is increased in the inflamed mucosa of UC and that c-met is overexpressed in UC-associated colorectal cancers. These observations suggest HGF-Met system is involved in the repair process of the inflamed mucosa of UC and provide further support for the view that the inappropriate expressions of both HGF and c-met genes predispose to the development of colorectal cancer in patients with UC.

Adult↗
PubMed2000

Characterization of nociceptin/orphanin FQ-induced pain responses in conscious mice: neonatal capsaicin treatment and N-methyl-D-aspartate receptor GluRepsilon subunit knockout mice.

Activation of primary afferent C fibers gives rise to spinal release of substance P and glutamate, and these mediators facilitate the cascade of nociceptive processing. We recently showed that intrathecal administration of nociceptin or orphanin FQ (hereafter called nociceptin) induced hyperalgesia to noxious thermal stimuli and allodynia to innocuous tactile stimuli applied to conscious mice. In the present study, we designed experiments to elucidate the pathways and mediators of nociceptin-evoked pain responses. Neonatal capsaicin treatment eliminated the induction of hyperalgesia and allodynia by nociceptin. Whereas this treatment markedly reduced the content of substance P in the spinal cord, it did not affect the nociceptin content or the expression of nociceptin receptors and GluRvarepsilon and GluRzeta subunits of N-methyl-D-aspartate receptors in it. The substance P antagonists CP96,345 and CP99,994 blocked the nociceptin-induced hyperalgesia, but not the allodynia. In contrast, the nociceptin-evoked allodynia, but not hyperalgesia, disappeared in N-methyl-D-aspartate receptor GluRvarepsilon1 subunit knockout mice. Both nociceptin-evoked hyperalgesia and allodynia were attenuated by morphine in a dose-dependent manner. Taken together, these results demonstrate that capsaicin-sensitive primary afferent fibers are involved not only in thermal hyperalgesia but also in tactile allodynia induced by nociceptin, but in different pathways; the former is mediated by substance P and the latter is mediated by glutamate through the N-methyl-D-aspartate receptor comprising the GluRvarepsilon1 subunit.

Analgesics, Opioid↗
PubMed2000

Endogenous endothelin in a rat model of acute colonic mucosal injury.

BACKGROUND: Endothelin (ET) is involved in various biologic activities in non-vascular and vascular tissues. While ET has some significant effects on gastrointestinal functions, the possible role of endogenous ET in the host response to mucosal injury has not been well clarified. METHODS: The present study describes an investigation of the effects of an endothelin A receptor antagonist, BQ-123, on lactate dehydrogenase (LDH), mucus and albumin flux into the perfusate in a rat model of acute colonic injury, induced by acetic acid perfusion. The present study also examined localization of ET in damaged rat colons by using immunohistochemistry. RESULTS: A 4% acetic acid treatment induced mild mucosal damage of perfused rat colon and increased LDH as well as albumin and protein-bound hexose release into the perfusate. Pretreatment with BQ-123 significantly reduced LDH activity and protein-bound hexose concentration in the perfusate and delayed the reduction of albumin leakage from damaged mucosa. Vascular endothelial, neural and surface epithelial cells of the colon showed strong ET-like immunoreactivity. Mucosal damage markedly influenced ET expression by epithelial cells. Mild mucosal damage decreased the ET expression by surface epithelial cells while moderate mucosal damage induced a mosaic location of ET-positive epithelial cells in the crypt. Severe mucosal damage abolished the ET expression by epithelial cells. CONCLUSIONS: Endothelin may play a role in the host response to acute mucosal damage. Mucosal ET production is significantly affected by mucosal injury.

Acetates↗
PubMed2000

Surgical management of intractable epilepsy associated with cerebral neurocytoma.

Neuronal neoplasms of the CNS constitute a rarely encountered group of tumors. This report concerns the surgical management of seizures encountered in four cases (ranging from 2 to 10 years-of-age at onset; consisting of two males and two females) of a recently recognized morphologically unique tumor, called 'cerebral neurocytoma'. All patients were associated solely with intractable complex partial seizures. The tumor involved the temporal lobe in two cases, and the frontal in two. Magnetoencephalography (MEG) clearly demonstrated an accumulation of equivalent current dipoles originating from the interictal spikes on the cortex around the tumor. On intra-operative electrocorticography (ECoG), the epileptogenic zone was topographically distinct from the region of the tumor. No definite ECoG activities were observed at the tumor site, although this tumor did consist of small mature neuronal cells. Either a complete or a subtotal resection of the tumor and the epileptogenic cortex was performed and, post-operatively, universal freedom from seizures was demonstrated in all patients. A histological examination of the epileptogenic cortex revealed the presence of minute cortical dysplasia or tumor involvement in the hippocampus. A resection of the epileptogenic cortex along with the tumor was thus found to improve the seizure outcome in patients with neurocytoma-associated epilepsy without inducing any identifiable neurological deficits attributable to the incremental resection.

Adult↗
PubMed2000

Low susceptibility of Long-Evans Cinnamon rats to N-butyl-N-(4-hydroxybutyl)-nitrosamine-induced urinary bladder carcinogenesis and inhibitory effect of urinary copper.

We studied the susceptibilities to N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced urinary bladder carcinogenesis of male Long-Evans Cinnamon (LEC), F344 and Long-Evans Agouti (LEA) rats. Male rats (n=21) were given 0.1% BBN in their drinking water from week 6, 8 and 10 for one week, and killed in week 56. The incidences of transitional cell tumors (papillomas plus carcinomas) in BBN-treated LEC and F344 rats were 12% and 76%, respectively (P<0.001, experiment 1), and those in LEC and LEA rats were 11% and 95%, respectively (P<0.001, experiment 2). When male LEC and F344 rats were given 0.1% BBN in their drinking water for 7 days, the intake of BBN and the urinary concentration of its active metabolite, N-butyl-N-(3-carboxypropyl)nitrosamine (BCPN), were higher in the LEC rats (P<0.01). The urinary pHs of untreated LEC and F344 rats were similar between week 6 and 30. The urinary copper concentration was lower in LEC rats before jaundice than in F344 rats, but its concentrations in 28- and 50-week-old LEC rats were 1.7 and 2.3 times those in F344 rats. In a two-stage carcinogenesis study using F344 rats, i.p. injections of cupric nitrilotriacetate increased urinary copper excretion, and inhibited BBN-induced bladder carcinogenesis. In a two-stage carcinogenesis study using LEC rats, oral administration of D-penicillamine decreased urinary copper excretion, and increased BBN-induced bladder cancer, although the difference was not significant. These data show that LEC rats are resistant to bladder carcinogenesis and suggest that urinary copper has a significant role in their resistance.

Age Factors↗
PubMed2000

Polycyclic aromatic hydrocarbon carcinogens increase ubiquitination of p21 protein after the stabilization of p53 and the expression of p21.

Polycyclic aromatic hydrocarbon carcinogens (PAHs) and their metabolites have been found to result in a rapid accumulation of p53 gene product in human and mouse cells. However, the induced p53 protein was reported to be transcriptionally inactive. In the present study, the induction of p53 target gene expression after the treatment with either benzo(a)pyrene (B[a]P) or 1-nitropyrene (1-NP) was investigated. A marked induction of messenger RNA (mRNA) expressions of Mdm2, Bax, and p21 was detected in wild-type p53-expressing cells after the treatment with either B[a]P or 1-NP, whereas no significant change in mRNA expression of these genes was observed in p53-negative and mutant cells. 1-NP activated the p21 promoter in a p53-dependent manner. Binding activity of p53 to a p53 consensus sequence increased after the treatment in wild-type p53-expressing cells. Nevertheless, the induced mRNA levels of the p21 did not result in a proportional p21 protein increase, indicating the possibility of post-transcriptional regulation of the protein. With the addition of MG-132, a proteasome inhibitor, to B[a]P or 1-NP treatments, both p21 and p53 protein levels were increased; however, the increase in p21 protein levels was significantly larger than the increase in p53 protein levels. PAHs treatment increased the level of ubiquitinated p21. These results suggest that the p21 product is degraded by the ubiquitin-proteasome system. We conclude that PAHs-induced p53 protein is transcriptionally active.

Benzo(a)pyrene↗
PubMed2000

[Studies of metals and metallothionein in tissue].

This paper is a review of three topics related to bio-trace metals. First, the transfer of metals into tissues of patients with chronic diseases treated with hemodialysis is examined. Such diseases include chronic hepatitis, diabetes, and chronic renal failure. In these diseases, metal contents from fingernails were flexible but non-specific. Toxicity may appear as the amount of heavy metals in tissues of patients with chronic renal failure treated with hemodialysis. For example, cadmium and lead were not excreted from the blood of patients during the hemodialysis treatment, and, therefore, their amounts gradually increased in the blood of patients. The level of zinc increased and was excreted in the urine of diabetic patients and experimental animals. Calcium accumulated in the kidney of streptozotocin (STZ)-induced diabetic rats that were fed low zinc diets; and, as a result, severe renal failure occurred. From these results, complication syndromes of either metal deficiency or excesses may occur in tissues of patients with chronic diseases. Second, the role of metallothionein (MT), an inducible protein, and the properties of MT isoforms have been studied on experimental animals. In the exocrine cells of the pancreas, MT was induced by various stresses such as zinc, STZ, alloxan and 4-aminopyrazolo-(3,4-d) pyrimidine, but the effects of those stresses were not clear in the endocrine cells. Therefore, MT may have a role in the exocrine cells of the pancreas. In addition, we were able to separate completely MT-1 and MT-2 isoforms in cytosol fractions of tissues using a capillary zone electrophoresis system at neutral pH without any detergents. Each role of the MT isoforms in the tissues soon started to become clear. Third, cisplatin, a platinum-containing anti-tumor drug, did not penetrate into the brain tissue under physiological conditions, as there is a blood-brain barrier to cerebral tissues; however, it did penetrate with either short-term hypoxia or in the case of lipopolysaccharide-treated experimental animals. Nitric oxide, prostaglandin, and free radicals are related to the penetration. Older rats had a higher sensitivity to cisplatin than younger rats.

Animals↗
PubMed2000

Age-dependent decreases of phosphorus and magnesium in human Achilles' tendons.

To elucidate changes of human tendons with aging, the authors studied age-related changes of elements in human Achilles' tendons by inductively coupled plasma-atomic emission spectrometry. The subjects consisted of seven men and seven women, ranging in age from 61 to 97 yr. It was found that the content of calcium increased progressively with aging in the Achilles' tendons, whereas the contents of phosphorus and magnesium decreased gradually with aging. The previous investigations demonstrated that the content of calcium and phosphorus increased progressively with aging in most, but not all, human tissues, except for the bones. In ligaments, such as the anterior cruciate ligament and the ligament of the head of the femur, which are histologically similar to the Achilles' tendon, it was previously found that both the contents of calcium and phosphorus increased with aging in the ligaments. It should be noted that the content of phosphorus in the Achilles' tendons decreased during the aging process. In addition, it was found that there was a very high direct correlation between phosphorus and magnesium contents in the tendons, but not between calcium and phosphorus contents.

Achilles Tendon↗
PubMed2000

Age-related changes of elements in human ureter.

To elucidate changes of the ureter with aging, the authors investigated age-related changes of element contents in human ureters. The subjects consisted of seven men and seven women, ranging in age from 61 to 97 yr. The contents of calcium, sulfur, and iron in the ureters increased progressively with aging, whereas the contents of phosphorus and magnesium did not increase with aging. Significant relationships were found both between calcium and sulfur contents and between calcium and iron contents in the ureters, but not between calcium and either phosphorus or magnesium contents. It was noteworthy that a significant relationship was also found between sulfur and iron contents in the ureters. It remains uncertain whether calcium forms a compound with sulfur or iron in aged human ureters or not.

Aged↗
PubMed2000

Toxicity of cisplatin to the central nervous system of male rabbits.

The cytotoxic effects of platinum (Pt) were studied by intraparenchymal injection of 1 mg of cisplatin (CDDP) in male rabbits. Time-serial plasma Pt levels were used as CDDP clearance indices in brain and kidney tissues. The tissue samples were also examined histologically. Changes in the blood-brain barrier (BBB) were evaluated by horseradish peroxidase (HRP) extravasation. In the brain infusion group, Pt was detected in the plasma 30 min after the start of infusion. In the kidney, Pt was detected after 10 min of CDDP injection. The maximum plasma concentration of Pt in the brain group showed diffuse edema, neuronal necrosis, karyolysis, and HRP extravasation around the injection site. In contrast, the histological damage to kidneys was minimal. The results presented here show that direct infusion of CDDP caused the most extensive cytotoxicity in the brain. The low clearance rate of CDDP from the brain and BBB disruption may explain this behavior.

Animals↗
PubMed2000

Accumulation of calcium and phosphorus in the mitral valve in comparison with the abdominal aorta and the scaphoid bone.

To clarify why calcification of the mitral valve occurred, the authors chose the abdominal aorta and the scaphoid bone among many arteries and bones, and they studied both relationships in element contents between the mitral valve and the abdominal aorta and between the mitral valve and the scaphoid bone. The subjects consisted of 11 men and 8 women, ranging in age from 52 to 96 yr. The accumulation of calcium and phosphorus occurred progressively with aging in the mitral valve, whereas it became the highest in the sixties in the abdominal aorta and did not increase thereafter. The accumulation of calcium and phosphorus occurred in the abdominal aorta earlier than the thoracic aorta, in which it became remarkable in the seventies. It should be noted that in regard to the accumulation of calcium and phosphorus, no significant correlations were found between the mitral valve and the abdominal aorta. It is suggested that calcification of the abdominal aorta is not essentially accompanied by calcification of the mitral valve. The scaphoid bone was chosen among many bones consisting mainly of spongy bone and the relationship was examined between the calcium content in the mitral valve and the bone mineral density of the scaphoid bone. It was found that there was a low relationship between them. Therefore, it is suggested that a part of the surplus calcium released from bones is deposited in the mitral valve.

Aged↗
PubMed2000

Differences in accumulation of elements in human cardiac valves.

To elucidate changes of human cardiac valves with aging, the authors determined age-related changes of element contents in the four human cardiac valves by inductively coupled plasma-atomic emission spectrometry and attempted to examine the relationships in the element contents among the four cardiac valves. The subjects consisted of 10 men and 15 women, ranging in age from 65 to 102 yr. The accumulation of calcium and phosphorus was the highest in the aortic valve, and decreased in the order mitral, pulmonary, and tricuspid valves. The contents of calcium and phosphorus in the aortic valves corresponded to about 12 and 19 times the amounts of those in the tricuspid valves, in which the contents were very low. The contents of calcium and phosphorus in the aortic valves were about 2.5-fold the amounts of those in the mitral valves. An examination was attempted to determine whether or not there were relationships in element contents among the four cardiac valves. As for the aortic and mitral valves, there were no relationships in the contents of calcium and phosphorus between them, but there were relationships in the contents of sulfur and magnesium between them. Three out of 24 cases contained high contents of calcium and phosphorus in both the mitral and aortic valves, whereas 16 out of 24 cases contained high contents of calcium and phosphorus in the aortic valves alone, without the high contents in the mitral valves. Likewise, there were no relationships in the element contents, such as calcium, phosphorus, sulfur, and magnesium, between the mitral and pulmonary valves or between the mitral and tricuspid valves. It is suggested that the accumulation of calcium and phosphorus in the cardiac valve occurs independent of the other cardiac valves.

Aged↗
PubMed2000

Age-related variations of elements as compared among optic, radial, and sciatic nerves.

To elucidate changes of peripheral nerves with aging, the authors studied age-related changes of element contents in the optic, radial, and sciatic nerves by inductively coupled plasma-atomic emission spectrometry. The subjects consisted of seven men and seven women, ranging in age from 61 to 97 yr. The contents of phosphorus and sulfur remained constant through ages 61 to 97 yr in three nerves, the optic, radial, and sciatic nerves. It was found that there were age-related differences in calcium content among the optic, radial, and sciatic nerves: The calcium content of the optic nerve increased progressively with aging; in the radial nerve, it was hardly changed with aging; in contrast, the calcium content of the sciatic nerve decreased gradually with aging. In addition, it was found that in the radial nerve there were moderate correlations between age and zinc or sodium content, whereas significant correlations between age and the content of silicon or iron were found in the sciatic nerve. Furthermore, there was a correlation between the silicon and iron contents in the sciatic nerves.

Aged↗