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Biomedical subjects

T Hamasaki

Publications and source records attributed to T Hamasaki.

At least 19 recordsLinked to original sources
PubMed1999

Overexpression of striatal enriched phosphatase (STEP) promotes the neurite outgrowth induced by a cAMP analogue in PC12 cells.

A cytoplasmic protein tyrosine phosphatase (PTPase) designated as striatal enriched phosphatase with a molecular weight of 46 kDa (STEP46) is highly expressed in striatal neurons with dopamine D1-receptors. To examine the hypothesis that STEP46 is involved in the neuronal functions modulated by the cyclic adenosine 3', 5'-monophosphate (cAMP)-signaling system, we introduced the complementary DNA of STEP46 into the pheochromocytoma cell line PC12, which exhibits neuronal differentiation characterized by neurite outgrowth in response to cAMP and nerve growth factor stimulation, and we established subclonal cell lines that constitutively overexpress STEP46 protein with PTPase activity. The subclones expressing STEP46 showed increased neurite outgrowth during differentiation induced by a cAMP analogue (dibutyryl cAMP). The positive regulatory role of STEP46 in the cAMP-induced neuronal differentiation of PC12 cells indicates that STEP46 may play a role in neuronal processes modulated by the cAMP-signaling cascade as a PTPase.

Animals↗
PubMed1998

Tumor progression and expression of matrix metalloproteinase-2 (MMP-2) mRNA by human urinary bladder cancer cells.

Tumor cells at the stage of tumor progression build up a high tolerance to intrinsic and extrinsic defence systems and/or therapeutic procedures, and the cells deeply infiltrate the adjacent tissue, which is followed by tumor metastasis to remote organs and tissues. This study was designed to investigate the relationship between expression of matrix metalloproteinase-2 (MMP-2) and invasiveness of human bladder cancer cells, using cell lines derived from a parental human urinary bladder tumor cell line, T24. Two subpopulations of the human bladder cancer cell line T24, Hi-T24 and Lo-T24, were selected using an invasion assay and then expression of MMP-2 mRNA and protein was analyzed by reverse-transcription polymerase chain reaction (RT-PCR) and enzyme immunoassay (EIA). The gross morphology, cell growth rate, and adhesion activity to a basement membrane extract (matrigel) of the high-invasive Hi-T24 cells were similar to those of the low-invasive Lo-T24 cells, but the Hi-T24 cells were 3.8-fold more haptotactic through matrigel than the Lo-T24 cells. The haptotactic activity of the Hi-T24 cells was suppressed by the addition of an anti-MMP-2 antibody, and the amounts of MMP-2 protein secreted into the spent medium by the Hi-T24 and Lo-T24 cells were 7.8+/-0.2 and 3.8+/-0.3 ng/ml (P<0.05), respectively. The quantities of tissue inhibitor of metalloproteinase-2 (TIMP-2) protein secreted by Hi-T24 and Lo-T24 cells were 133.2+/-4.3 and 168.7+/-5.6 ng/ml, respectively (P<0.05). The levels of transcription of the genes encoding MMP-2 and the transmembrane MMP, MT-MMP, evaluated by RT-PCR, were higher in the Hi-T24 cells than in the Lo-T24 cells. Expression of the TIMP-2 gene was slightly lower in the Hi-T24 cells than in the Lo-T24 cells. These results indicate that expression of the metalloproteinases are imbalanced at the gene level in human urinary bladder cancer cells at the stage of tumor progression.

Carcinoma, Transitional Cell↗
PubMed1998

Neurotoxicity evoked by N-methyl-D-aspartate in the organotypic static slice cultures of rat cerebral cortices: effect of GABA(A) receptor activation.

We investigated the neurotoxicity evoked by N-methyl-D-aspartate (NMDA) receptor stimulation in the organotypic static slice cultures of rat cerebral cortices. We also examined whether the gamma-aminobutyric acid (GABA)A receptor agonist muscimol has a protective effect on the NMDA-mediated neurotoxicity in this culture system. NMDA-mediated cytotoxicity was evaluated histologically and quantified by the measurement of lactate dehydrogenase (LDH) release into the culture medium. There was an NMDA-induced, dose-dependent leakage of LDH release and neuronal cell death, which were not attenuated by muscimol treatment. The results suggested that NMDA neurotoxicity is reproduced in the organotypic culture, and that GABA(A) receptor activation exerted no protective action against the NMDA cytotoxicity.

Animals↗
PubMed1998

Soluble complement receptor type I limits damage during revascularization of ischemic myocardium.

BACKGROUND: This study was undertaken to determine whether suppression of complement activation with soluble human complement receptor type I reduces myocardial damage during the revascularization of ischemic myocardium. METHODS: In 20 pigs, the second and third diagonal coronary arteries were occluded for 90 minutes, followed by 45 minutes of cardioplegic arrest and 180 minutes of reperfusion. In 10 pigs, soluble human complement receptor type I (10 mg/kg) was infused over 30 minutes before the period of coronary occlusion; 10 other pigs received no soluble human complement receptor type I. Complement activation was measured by total hemolytic complement activity (expressed as a percentage of preischemic values). Ischemic damage was assessed by changes in myocardial tissue pH, wall motion scores (range, 4=normal to -1=dyskinesia), and infarct size (area of necrosis versus area at risk). RESULTS: After 180 minutes of reperfusion, hearts treated with soluble human complement receptor type I had significantly less complement activation than nontreated hearts (1.1%+/-0.09% versus 7.8%+/-0.04%, respectively; p < 0.002), less myocardial acidosis (-0.41+/-0.03 versus -0.72+/-0.03, respectively; p < 0.0001), higher wall motion scores (3.1+/-0.09 versus 1.67+/-0.16, respectively; p < 0.0001), and smaller infarct size (24.6%+/-2.0% versus 41%+/-1.3%, respectively; p < 0.0001). CONCLUSIONS: Complement inhibition with soluble human complement receptor type I significantly limits ischemic damage during the revascularization of acutely ischemic myocardium.

Acidosis↗
PubMed1998

Ultrastructure of blood vessel regression in involution of foreign-body granuloma.

The diversity of endothelial cell deletion in regressing blood vessels during involution of granulation tissue was investigated in foreign-body granulomas induced by a collagen sponge implanted into the dorsum of the rat. Small blood vessel density counts were performed to determine the degree of blood vessel regression in the involution of granulation tissue in foreign-body granuloma. The density of these small blood vessels significantly decreased between 100 and 130 days after sponge implantation. The detachment of endothelial cells from their underlying basement membrane and the consequent protrusion into and/or out of the lumen in the vascular network of granulation tissue was observed by electron microscopy. Based on the pattern of manifestation in the endothelium and the characteristic deformation of nuclei, the detached endothelial cells were classified into two groups: 1) the endothelial cell apoptosis group and 2) the endothelial cell degeneration group. The essential difference between the two groups was easily distinguishable as the nucleus of the former group displayed chromatin condensation and margination as the hallmark of early apoptotic changes, while the nucleus of the latter group displayed a pinch structure and intranuclear pocket formation. However, the process by which the detached endothelial cells were shed into the vascular lumen and eventually eliminated from circulation was the same in both groups. The occurrence of both groups increased on the 90th day after sponge implantation and reached a maximum on the 110th day, indicating that the appearance of the groups was synchronized. These results suggest that the two major processes of apoptosis and degeneration of endothelial cells occur during endothelial cell deletion as a mechanism contributing to blood vessel regression.

Animals↗
PubMed1997

Mizoribine in steroid-dependent nephrotic syndrome of childhood.

We evaluated a 1-year course of a newly developed immunosuppressant, mizoribine (at a dosage of 3 mg/kg body weight per day), in nine children with steroid-dependent nephrotic syndrome. Steroid treatment could be discontinued in two patients and the maintenance dosage of steroid could be reduced to less than half of that given before mizoribine therapy in a third. There were no beneficial effects in the remaining six patients. No adverse effects of mizoribine were observed during the course of therapy.

Adolescent↗
PubMed1997

Heparin-bonded circuits decrease myocardial ischemic damage: an experimental study.

BACKGROUND: Heparin-bonded cardiopulmonary bypass circuits reduce complement activation, but their effect on myocardial function is unknown. This study was undertaken to determine whether heparin-bonded circuits reduce myocardial damage during acute surgical revascularization. METHODS: In 16 pigs, the second and third diagonal vessels were occluded with snares for 90 minutes followed by 45 minutes of cardioplegic arrest and 180 minutes of reperfusion with the snares released. During the period of coronary occlusion, all animals were placed on percutaneous bypass followed by standard cardiopulmonary bypass during the periods of cardioplegic arrest and reperfusion. In 8 pigs, heparin-bonded circuits were used, whereas 8 other pigs received nonbonded circuits. RESULTS: Animals treated with heparin-bonded circuits had the best preservation of wall motion scores (3.5 +/- 0.3 versus 2.3 +/- 0.2; 4 = normal to -1 = dyskinesis; p < 0.05), least tissue acidosis (change in pH = -0.31 +/- 0.02 versus -0.64 +/- 0.08; p < 0.05), smallest increase in lung H2O (1.7% +/- 0.7% versus 6.1% +/- .5%; p < 0.05), and the lowest area of necrosis/area of risk (20.3% +/- 2.2% versus 40.4% +/- 1.6%; p < 0.05). CONCLUSIONS: We conclude that heparin-bonded circuits significantly decrease myocardial ischemic damage during acute surgical revascularization.

Acid-Base Equilibrium↗
PubMed1997

An immunogenicity and efficacy study of purified chick embryo cell culture rabies vaccine manufactured in Japan.

Purified chick embryo cell rabies vaccine manufactured by the Chemo-Sero-Therapeutic Institute(Kaketsuken) at Kumamoto, Japan (Kaketsuken) was submitted to an immunogenicity and efficacy study. 52 severely rabies exposed patients were treated with the conventional five doses intramuscular WHO approved ('Essen') postexposure schedule. This included the administration of 40 IU kg-1 of equine rabies immune globulin on Day 0. A control group of equally severely exposed subjects were treated with human diploid cell rabies vaccine manufactured by the Swiss Serum and Vaccine Institute as well as human rabies immune globulin. There were no deaths in either group in the more than 2 years follow-up period. Subjects treated with the chick embryo vaccine showed greater suppression of the neutralizing antibody response by the equine rabies immune globulin than those given the human diploid cell vaccine and human rabies immune globulin. A group of 20 less severely rabies exposed patients who received only the chick embryo vaccine without immune globulin all had antibody titers greater than the WHO minimal acceptable level on Day 14, 30, 90 and 180. Fourteen subjects among the severely exposed vaccine and immune globulin study group were given vaccine boosters on Day 180 because of low antibody titers. It is concluded that chick embryo rabies vaccine manufactured by Kaketsuken is an immunogenic and effective rabies vaccine, but that the potency of future batches must be increased to provide a greater safety margin.

Animals↗
PubMed1996

[Clinical study of occupational uroepithelial cancer].

We studied 438 persons who were engaged in the production and use of aromatic amines (benzidine sulfate, beta-naphthylamine, alpha-naphthylamine and dianisidine). Among these 438 persons, 88 new cases of occupational uroepithelial cancer had occurred from 1949 to 1995. The incident rate of occupational uroepithelial cancer was 20.1%. The average exposure period of these 88 cases to the aromatic amines was 7.40 years (range, 0.75-26.75), and the incidence rate of tumors increased with the length of exposure to aromatic amines. The average latent period was 26.79 years (range, 1.33-48.50), and the average age of first onset was 52.59 (range, 24-79). Recently it has been determined that the longer the latent period, the older the age of first onset. Of these 88 cases, the tumor sites were bladder in 67 cases (76.1%) and upper urinary tract (renal pelvis and/or ureter) in 5 cases (5.7%). The other 16 cases (18.2%) were the bladder and upper urinary tract. The screening examination for chemical workers using urinary cytology was begun in 1962. In our cases, urine cytology was a useful method for diagnosing occupational uroepithelial cancer. As for initial treatment of the 88 cases, transurethral surgery was most frequently performed, that is on 58 cases (65.9%). However, eight cases (9.1%) had to undergo a total nephroureterectomy, and six cases (6.8%) had a total cystectomy. Recurrence was observed in 61 cases (69.3%) out of the 88 patients with an average of 1.81 times. The other organic cancers developed in 39 cases (8.9%) out of 438 workers who were exposed to aromatic amines and in 8 cases out of 88 patients (9.1%). Prognosis of the 88 patients is that, the number of alive and dead is 51 (58.0%) and 37 (42.0%) respectively on December 31, 1995. Twenty-eight patients (31.8%) died of uroepithelial cancer, and five patients (5.7%) died of other organic cancers. The survival rates of 5, 10, 15 and 20 years was 87.9%, 74.0%, 65.9% and 56.3%, respectively. From these results, patients with occupational uroepithelial cancer and workers who are exposed to aromatic amines should undergo long term observation.

2-Naphthylamine↗
PubMed1996

Ultrastructure of multinucleated giant cell apoptosis in foreign-body granuloma.

To elucidate the role of apoptosis in the disappearance of multinucleated giant cells from the granulation tissue in cases of foreign-body granuloma, we induced a foreign-body reaction by implanting a collagen sponge into the dorsum of the rat and observed apoptotic changes within the multinucleated giant cells using electron microscopy. Two types of multinucleated giant cells were identified presenting apoptotic characteristics morphologically. One was characterized by apoptosis of only one nucleus, followed by cytoplasmic changes, rupture of the plasma membrane and necrosis evoking an inflammatory reaction. The other showed typical apoptotic changes in the majority or in all of the nuclei, followed by phagocytosis of the apoptotic syncytia. The results of the present study suggest that apoptosis occurring within only one nucleus might be triggered by overexpression of the p53 protein, because DNA abnormalities are confined to this single nucleus. In contrast apoptosis occurring simultaneously in the majority or all of the nuclei is most probably due to cell death caused by senescence.

Animals↗
PubMed1996

Effects of calcium in continuous cardioplegia on myocardial protection.

The effects of calcium (Ca) on a hyperkalemic cardioplegic solution for continuous cardioplegia were examined in an isolated perfused working rat heart model. The coronary arteries were perfused with a modified Krebs-Henseleit bicarbonate buffer (K-H) solution, containing various concentrations of Ca (0.1, 0.6, 1.2, and 2.5 mmol/l) and a high concentration of potassium (20 mmol/l), for 180 min, after which cardiac arrest was induced at 37 degrees C for 180 min. Cardiac function and creatine kinase (CK) were measured. In the control group, K-H solution was infused in place of the cardioplegic solution, and cardiac arrest was not induced. No significant differences were observed between the groups infused with the K-H solution containing Ca concentrations of 0.6, 1.2, and 2.5 mmol/l in the percent recovery of aortic flow (82.1 +/- 2.9%, 80.6 +/- 2.0%, and 71.5 +/- 3.7% (mean +/- SEM) respectively) or in the recovery of other indices of cardiac function, or in CK leakage. There were also no significant differences in the recovery of cardiac function and CK leakage between these groups and the control group. In the Ca 0.1 mmol/l group, however, the characteristic Ca paradox was observed. These findings suggest that if the Ca concentration in a cardioplegic solution is higher than 0.6 mmol/l during continuous cardioplegia, excellent cardioprotective effects will be achieved.

Animals↗
PubMed1996

Hyperinsulinemia increases the risk of gestational hypertension.

OBJECTIVE: To determine whether hyperinsulinemia is related to gestational hypertension. METHODS: We measured the arterial blood pressure and the level of immunoreactive insulin (IRI) during a 75 g oral glucose tolerance test in a total of 84 pregnant women. Hyperinsulinemia was defined as a fasting IRI level > or = 9 IU/l, while gestational hypertension was defined as arterial blood pressure > or = 140/90 mmHg. RESULTS: The incidence of gestational hypertension was higher in the hyperinsulinemic group (n = 29) than in the control group (n = 55) (24.1% vs. 7.3%, respectively P < 0.05). After controlling for maternal age, parity, pre-pregnancy body mass index and the gestational age at the time of oral glucose tolerance test (OGTT), using a multiple regression model, the relative risk of developing gestational hypertension for a fasting insulin level was 1.19 (95% C.I., 1.03-1.38). CONCLUSION: Pregnant women with hyperinsulinemia are at increased risk of developing gestational hypertension.

Adult↗
PubMed1996

Pancreatic juice output after pancreatoduodenectomy in relation to pancreatic consistency, duct size, and leakage.

BACKGROUND: A soft pancreas with a main pancreatic duct (MPD) with normal diameter has been considered a high risk for pancreatic anastomotic leakage because of a relatively high output of pancreatic juice, but data are lacking. METHODS: An attempt was made to assess the relationship between the consistency of the pancreas, MPD diameter, pancreatic juice output, and pancreatic leakage after partial pancreatoduodenectomy. The pancreatic parenchyma was classified as of soft, intermediate, and hard consistency in 70 consecutive patients undergoing operation (groups 1, 2, and 3, respectively) by one surgeon. The MPD diameter was determined by means of endoscopic pancreatography or abdominal ultrasonography. Pancreatic juice output was measured for 21 days after operation by using a catheter inserted into the MPD. Anastomotic leakage was identified radiologically by using contrast medium. RESULTS: The mean (SD) pancreatic juice output during a period of 10 days (postoperative days 5 to 14) was 1554 (1073) ml in group 1 (n = 29), 1513 (1060) ml in group 2 (n = 13), and 187 (220)ml in group 3 (n = 28) (groups 1 and 2 versus group 3, p < 0.0001). The MPD diameter was 3.0 (1.6) mm in group 1, 5.9 (2.5) mm in group 2, and 6.6 (2.6) mm in group 3 (group 1 versus groups 2 and 3, p = 0.0001). Anastomotic leaks occurred in four (14%) patients in group 1, three (23%) in group 2, and none in group 3 (p < 0.05). CONCLUSIONS: Patients with a pancreatic parenchyma with an intermediate or normal consistency produced more pancreatic juice and had a higher leak rate.

Adult↗
PubMed1996

Simple detection of xylosidase activity in single colonies, using 1-naphthyl-beta-D-xylopyranoside.

Since the xylosidase of Bacillus pumilus hydrolyzed 1-naphthyl-beta-D-xylopyranoside (naphthyl-X) to produce xylose and 1-naphthol and a chromogenic azo compound is produced by coupling 1-naphthol and Fast Blue Salt B, a simple method for detection of xylosidase activity in single colonies was studied. Escherichia coli JM109 carrying the xylosidase gene of B. pumilus was cultivated at 37 degrees C for 18 h on a LB plate containing 0.5 mg/ml naphthyl-X, and then the plate was overlaid with 3 ml of a top layer containing 24 mg of agar and 6 mg of Fast Blue Salt B. After incubation of the plate at 37 degrees C for 1 h, each colony became reddish-brown. Even a small colony with xylosidase on the plate was easily distinguished from colonies without the enzyme.

Bacillus↗
PubMed1996

A simple assay for xylanase using o-nitrophenyl-beta-D-xylobioside.

We measured xylanase activities upon eight chromogenic substrates, o- or p-nitrophenyl-beta-D-xylopyranoside (oNP-X or pNP-X) and o- or p-nitrophenyl-beta-D-xylooligosaccharides (oNP-Xn or pNP-Xn, n = 2-4), and studied for their uses as substrates in a kinetic study. The Kcat and K(m) of Bacillus pumilus xylanase (EC 3.2.1.8) activities for pNP-X2 were 0.24s-1 and 0.5 mM, respectively. The relative xylanase activities with the other substrates to that with pNP-X2, pNP-X3, pNP-X4, oNP-X, oNP-X2, oNP-X3, and oNP-X4 were < 0.001, 9.4, 9.7, < 0.001, 19, 190, and 200, respectively. HPLC analysis of the digestion products of oNP-X2 or pNP-X2 showed that the xylanase hydrolyzed each of the substrates only at the ether bond between nitrophenol and xylobiose. All ether bonds of pNP-X3, oNP-X3, pNP-X4, or oNP-X4 were hydrolyzed by the xylanase and further hydrolyses proceeded in the digestion products, e.g., oNP-X2 and oNP-X3 from oNP-X4. Therefore, oNP-X2 was screened as a useful substrate in a kinetic study of the xylanase. The K(m) and Kcat of the xylanase for oNP-X2 were 0.38 mM 2.29s-1, respectively. Thermodynamic studies showed that the higher reaction rate obtained with oNP-X2 than that with pNP-X2 was due to a significant decrease in the activation energy change, despite a decrease in the activation entropy change.

Bacillus↗