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Biomedical subjects

T Hamasaki

Publications and source records attributed to T Hamasaki.

At least 19 recordsLinked to original sources
PubMed2000

High concentrations of serum inhibin in pre-eclampsia.

OBJECTIVE: To evaluate maternal serum immunoreactive inhibin (ir-inhibin) concentrations in women with pre-eclampsia, and assess the correlation between serum ir-inhibin and HCG. METHODS: The subjects comprised 28 pregnant women with suspected intrauterine growth retardation (IUGR) during the third trimester. Serum concentrations of ir-inhibin and HCG were measured in 13 women with pre-eclampsia and 15 pregnant women as control subjects. Serum ir-inhibin was determined by a double antibody radioimmunoassay, and HCG by a solid-phase immunoradiometric assay. RESULTS: There were no significant differences in maternal characteristics between the pre-eclamptic group and control group. The pre-eclamptic group had significantly higher concentrations of serum ir-inhibin and HCG compared with the control group. The serum concentrations of ir-inhibin correlated positively with those of HCG. CONCLUSION: The pre-eclamptic patients displayed high serum levels of ir-inhibin and HCG, and this might reflect hyperplasia of trophoblastic cells.

Adult↗
PubMed2000

Evidence for a novel affinity mechanism of motor-assisted transport along microtubules.

In microtubule (MT) translocation assays, using colloidal gold particles coupled to monoclonal tubulin antibodies to mark positions along MTs, we found that relative motion is possible between the gold particle and an MT, gliding on dynein or kinesin. Such motion evidently occurred by an affinity release and rebinding mechanism that did not require motor activity on the particle. As the MTs moved, particles drifted to the trailing edge of the MT and then were released. Sometimes the particles transferred from one MT to another, moving orthogonally. Although motion of the particles was uniformly rearward, movement was toward the (-) or (+) end of the MT, depending on whether dynein or kinesin, respectively, was used in the assay. These results open possibilities for physiological mechanisms of organelle and other movement that, although dependent on motor-driven microtubule transport, do not require direct motor attachment between the organelle and the microtubule. Our observations on the direction of particle drift and time of release may also provide confirmation in a dynamic system for the conclusion that beta tubulin is exposed at the (+) end of the MT.

Animals↗
PubMed2000

Successful treatment of a neonate with vein of Galen aneurysmal malformation.

We present a follow-up study on a 5-year-old boy who was born with vein of Galen aneurysmal malformation (VGAM) accompanied by extreme cardiovascular distress. He was successfully treated by the staged endovascular technique during the neonatal stage. Postoperative angiographic study confirmed complete occlusion of the VGAM and the establishment of normal brain perfusion. At 5 years of age, the child is growing normally without neurological deficits or developmental retardation. We suggest that the restoration of normal brain perfusion in neonates with VGAM can cause normal brain development.

Cardiomegaly↗
PubMed2000

Endoscopic treatment of vesicoureteral reflux in children with glutaraldehyde cross-linked bovine dermal collagen. Short-term results.

BACKGROUND: Endoscopic treatment using glutaraldehyde cross-linked (GAX) collagen was conducted on 4 children with bilateral primary vesicoureteral reflux (VUR)..... a 1-year-old boy and three 5- to 8-year-old girls $B!D (Ball having a history of repeated hospitalization for fever due to acute pyelonephritis, visiting as pediatric outpatients regularly and receiving antibiotics continuously. By international VUR classification, 4 ureters were grade 3, 2 grade 4, and 2 grade 5. METHODS: After nonallergy to GAX collagen was confirmed intracutaneously, a needle was used through a 9.5 Fr cystoscope channel to puncture bladder mucosa 4 to 5 mm from the affected ureteral orifice at 6 o'clock under general anesthesia; 1.1 to 1.9 ml of GAX collagen was injected immediately below affected orifices. RESULTS: Three months after surgery, voiding cystourethrography showed reflux had disappeared in 6 ureters, for a short-term success rate of 75%. VUR in the Remaining 2 ureters improved from grade 3 to 1 and from grade 5 to 4. No postoperative urinary tract infection occurred and antibiotics were stopped. CONCLUSION: Since GAX collagen is less viscous than Teflon paste, it is easily injected into submucosa, does not form granuloma or migrate to other organs, and is noncarcinogenic. Endoscopic VUR treatment using GAX collagen is indicated when less invasion and shorter hospitalization are considered, although it requires general anesthesia, which itself involves some risk.

Child↗
PubMed2000

[Relationship between changes in estimated and measured blood concentrations of propofol and serum albumin concentration during propofol anesthesia: effects of intraoperative bleeding (a case report)].

We investigated the effect of intraoperative bleeding on the changes in estimated and measured blood concentrations of propofol, and the relationship between anesthetic effect of propofol and serum albumin concentration in a patient undergoing prostatectomy during propofol/epidural anesthesia. The rate of propofol infusion was titrated to keep the BIS value about 50. The estimated blood concentration of propofol calculated by ConGrase, a program for on-line simulation of blood propofol concentration, was monitored during anesthesia. Blood samples were obtained at nine points during surgery and the blood concentrations of propofol and albumin were measured postoperatively. When the amount of bleeding reached about 2000 mg, the difference between estimated and measured blood concentrations of propofol did not increase. As the serum albumin concentration decreased, the concentration of propofol to keep bispectral index about 50 decreased. This study suggests that the change in serum albumin concentration following intraoperative bleeding is an important factor in the anesthetic effect of propofol.

Aged↗
PubMed2000

Permanent cardiac pacing following surgery for acquired valvular disease.

Between January 1980 and January 1998, implantation of a permanent pacemaker (PP) was performed in 22 patients (6.7%) following 327 acquired valvular surgeries. The indications for implantation of a PP were bradycardia with atrial fibrillation in 12 cases, sick sinus syndrome in 7 cases and complete atrioventricular block in 3 cases. These patients received an implantation after surgery for mitral valvular disease in 14 cases, aortic valvular disease in 3 cases and combined valvular disease in 5 cases. These cases were also concomitant with a tricuspid valve annuloplasty in 6 cases for secondary regurgitation and with a maze procedure in 4 cases. For the purpose of this study, these patients were compared to patients who did not require implantation of a PP after surgery. Univariate analysis showed the significant factors to be female gender (p = 0. 041), preoperative atrial fibrillation (p = 0.013), redo cardiac surgery (p < 0.0001), and the use of blood cardioplegia (p = 0.003). There were no differences in valvular disease, age at the last valvular operation, addition of tricuspid valve annuloplasty, extracorporeal circulation times, or aortic cross-clamp times between those patients with and those without PP. Among these factors, logistic regression analysis showed female gender, redo surgery and the use of blood cardioplegia to be more significant predictors for the requirement of PP after acquired valvular disease operation. Maze procedure was not a significant predictor for the requirement of PP after surgery.

Adult↗
PubMed1999

Transient and compartmental expression of the reeler gene product reelin in the developing rat striatum.

Mammalian neostriatum is composed of two neurochemically and neuroanatomically defined compartments, called the patches and matrix. The present study concerns a search for neurochemical molecules involved in formation of the striatal compartments. Using the monoclonal antibody CR-50, we here disclose a transient expression of the reeler gene product Reelin, which is known to play a crucial role in neuronal positioning and axon guidance during corticogenesis, in the developing striatum of rats. Furthermore, Reelin protein is differentially concentrated in the two distinct compartments showing a mosaic-like fashion in the early postnatal period: the compartments of heightened CR-50-immunolabeling correspond to so-called "dopamine islands" (i.e., developing striosomes) visualized by tyrosine hydroxylase (TH)-immunostaining. On the basis of these findings, we hypothesize that Reelin protein may play a role in developmental organization of the striatal compartments.

Animals↗
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↗
PubMed1999

Cloning and characterization of the O-methyltransferase I gene (dmtA) from Aspergillus parasiticus associated with the conversions of demethylsterigmatocystin to sterigmatocystin and dihydrodemethylsterigmatocystin to dihydrosterigmatocystin in aflatoxin biosynthesis.

O-Methyltransferase I catalyzes both the conversion of demethylsterigmatocystin to sterigmatocystin and the conversion of dihydrodemethylsterigmatocystin to dihydrosterigmatocystin during aflatoxin biosynthesis. In this study, both genomic cloning and cDNA cloning of the gene encoding O-methyltransferase I were accomplished by using PCR strategies, such as conventional PCR based on the N-terminal amino acid sequence of the purified enzyme, 5' and 3' rapid amplification of cDNA ends PCR, and thermal asymmetric interlaced PCR (TAIL-PCR), and genes were sequenced by using Aspergillus parasiticus NIAH-26. A comparison of the genomic sequences with the cDNA of the dmtA region revealed that the coding region is interrupted by three short introns. The cDNA of the dmtA gene is 1,373 bp long and encodes a 386-amino-acid protein with a deduced molecular weight of 43,023, which is consistent with the molecular weight of the protein determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The C-terminal half of the deduced protein exhibits 76.3% identity with the coding region of the Aspergillus nidulans StcP protein, whereas the N-terminal half of dmtA exhibits 73.0% identity with the 5' flanking region of the stcP gene, suggesting that translation of the stcP gene may start at a site upstream from methionine that is different from the site that has been suggested previously. Also, an examination of the 5' and 3' flanking regions of the dmtA gene in which TAIL-PCR was used demonstrated that the dmtA gene is located in the aflatoxin biosynthesis cluster between (and in the same orientation as) the omtA and ord-2 genes. Northern blotting revealed that expression of the dmtA gene is influenced by both medium composition and culture temperature and that the pattern correlates with the patterns observed for other genes in the aflatoxin gene cluster. Furthermore, Southern blotting and PCR analyses of the dmtA gene showed that a dmtA homolog is present in Aspergillus oryzae SYS-2.

Aflatoxins↗
PubMed1999

Enzymatic formation of G-group aflatoxins and biosynthetic relationship between G- and B-group aflatoxins.

We detected biosynthetic activity for aflatoxins G(1) and G(2) in cell extracts of Aspergillus parasiticus NIAH-26. We found that in the presence of NADPH, aflatoxins G(1) and G(2) were produced from O-methylsterigmatocystin and dihydro-O-methylsterigmatocystin, respectively. No G-group aflatoxins were produced from aflatoxin B(1), aflatoxin B(2), 5-methoxysterigmatocystin, dimethoxysterigmatocystin, or sterigmatin, confirming that B-group aflatoxins are not the precursors of G-group aflatoxins and that G- and B-group aflatoxins are independently produced from the same substrates (O-methylsterigmatocystin and dihydro-O-methylsterigmatocystin). In competition experiments in which the cell-free system was used, formation of aflatoxin G(2) from dihydro-O-methylsterigmatocystin was suppressed when O-methylsterigmatocystin was added to the reaction mixture, whereas aflatoxin G(1) was newly formed. This result indicates that the same enzymes can catalyze the formation of aflatoxins G(1) and G(2). Inhibition of G-group aflatoxin formation by methyrapone, SKF-525A, or imidazole indicated that a cytochrome P-450 monooxygenase may be involved in the formation of G-group aflatoxins. Both the microsome fraction and a cytosol protein with a native mass of 220 kDa were necessary for the formation of G-group aflatoxins. Due to instability of the microsome fraction, G-group aflatoxin formation was less stable than B-group aflatoxin formation. The ordA gene product, which may catalyze the formation of B-group aflatoxins, also may be required for G-group aflatoxin biosynthesis. We concluded that at least three reactions, catalyzed by the ordA gene product, an unstable microsome enzyme, and a 220-kDa cytosol protein, are involved in the enzymatic formation of G-group aflatoxins from either O-methylsterigmatocystin or dihydro-O-methylsterigmatocystin.

Aflatoxin B1↗
PubMed1999

New method of bladder biopsy using combined aspiration and snare.

A method of multiple random biopsy combined with bladder wall aspiration and snare in bladder cancer is presented. Our method was used on 23 patients with clinically superficial bladder cancer and was found to have advantages in obtaining an adequate amount of tissue with minimal thermal degeneration.

Biopsy, Needle↗
PubMed1999

[A case of extragonadal germ cell tumor with inferior vena caval tumor thrombus].

We report a case of retroperitoneal extragonadal germ cell tumor with tumor thrombus in the inferior vena cava. The patient referred to our hospital with lumbago. Computed tomography (CT) showed a bulky mass in the retroperitoneum. The levels of alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (beta-HCG) in the serum were elevated. Histological examinations indicated embryonal cell carcinoma. Bilateral testicles did not contain any palpable mass upon careful palpation. No tumor mass was detected in the bilateral testicles on ultrasonography. Clinically, the diagnosis was a retroperitoneal extragonadal germ cell tumor associated with para-aortic lymph-node involvement. After the combination chemotherapy (BEP 1 course and EP 3 courses), the tumor mass was reduced in size and the tumor marker was normalized. Retroperitoneal lymph node dissection (RPLND) was performed and tumor thrombus in the inferior vena cava was resected. There was no involvement of the viable cells in the resected tumor. The patient has been in good condition with no evidence of disease.

Adult↗
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↗