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Biomedical subjects

M Ishikawa

Publications and source records attributed to M Ishikawa.

At least 73 records · Page 4Linked to original sources
PubMed2001

Identification of a potent and nonpeptidyl ccr3 antagonist.

CCR3 is expressed in a variety of leukocyte subsets, especially eosinophils, and may be involved in allergic disorders such as atopic asthma. To clarify the pathophysiological roles of CCR3 in allergic disorders, we developed a nonpeptidyl CCR3 antagonist. This antagonist, which is referred to as "Compound X," that inhibited the binding of [(125)I]Eotaxin to CHO cells transfected with human CCR3 with an IC(50) value of 2.3 nM. In human eosinophils, Compound X also inhibited Eotaxin-induced increases in intracellular Ca(2+) concentrations and chemotaxis. Thus, Compound X appears to be a highly potent CCR3 antagonist. These findings suggest that Compound X may be a useful tool for elucidating the pathophysiological roles of CCR3 in a variety of allergic disorders.

Animals↗
PubMed2001

Atomic force microscopy of RecA--DNA complexes using a carbon nanotube tip.

We report high resolution images of RecA-double stranded (ds) DNA complexes obtained by atomic force microscopy (AFM). When a carbon nanotube (CNT) tip was used, AFM images visualized the 10-nm pitch of RecA-dsDNA complexes and RecA filaments as three-dimensional surface topography without reconstruction analysis. The depth of the notch between two pitches was less than 1 nm. When adsorbed on a soft surface covered with proteins, naked DNA, RecA monomers, RecA hexamers, and short RecA filaments were all clearly resolved in one image. The high resolution images with a CNT tip provided valuable information on the initiation process of RecA-dsDNA complex formation.

DNA↗
PubMed2001

The NPK1 mitogen-activated protein kinase kinase kinase is a regulator of cell-plate formation in plant cytokinesis.

Mitogen-activated protein kinase (MAPK) cascades play important roles not only in the transduction of extracellular signals but in the progression of the cell cycle. However, evidence for their role in cytokinesis is limited. Here, we show that a tobacco MAPK kinase kinase (MAPKKK), designated NPK1, is required for cytokinesis. The activity of NPK1 increases in the late M phase of the tobacco cell cycle. During expansion of a new cross-wall (cell plate) toward the cell cortex, NPK1 is consistently localized to the equatorial zone of the phragmoplast, the cytokinetic apparatus where the cell plate is formed. Expression of a kinase-negative mutant of NPK1 results in the generation of multinucleate cells with incomplete cell plates. Phragmoplasts can be formed, but its expansion toward the cell cortex is also blocked. Thus, our results indicate that the NPK1 MAPKKK is essential for the formation of the cell plate, especially for its lateral growth.

Animals↗
PubMed2001

Acetyl-CoA synthetase 2, a mitochondrial matrix enzyme involved in the oxidation of acetate.

Using peptide sequences derived from bovine cardiac acetyl-CoA synthetase (AceCS), we isolated and characterized cDNAs for a bovine and murine cardiac enzyme designated AceCS2. We also isolated a murine cDNA encoding a hepatic type enzyme, designated AceCS1, identical to one reported recently (Luong, A., Hannah, V. C., Brown, M. S., and Goldstein, J. L. (2000) J. Biol. Chem. 275, 26458-26466). Murine AceCS1 and AceCS2 were purified to homogeneity and characterized. Among C2-C5 short and medium chain fatty acids, both enzymes preferentially utilize acetate with similar affinity. The AceCS2 transcripts are expressed in a wide range of tissues, with the highest levels in heart, and are apparently absent from the liver. The levels of AceCS2 mRNA in skeletal muscle were increased markedly under ketogenic conditions. Subcellular fractionation revealed that AceCS2 is a mitochondrial matrix enzyme. [(14)C]Acetate incorporation indicated that acetyl-CoAs produced by AceCS2 are utilized mainly for oxidation.

Acetate-CoA Ligase↗
PubMed2001

Requirement of nitric oxide for murine oocyte maturation, embryo development, and trophoblast outgrowth in vitro.

We investigated the extent to which NO participates in the developmental competence (oocyte maturation, fertilization and embryo development to blastocyst) using an in vitro culture system adding sodium nitroprusside (SNP), NO donor, and NOS inhibitor (N-omega-nitro-L-arginine methyl ester, L-NAME). We also assessed the effects of NO/NOS system on blastocyst implantation using an in vitro trophoblast outgrowth assay. The treatment of low concentrations of SNP (10(-7) M) significantly stimulated meiotic maturation to metaphase II stages in cumulus enclosed oocytes. In contrast, 10(-3) and 10(-5) M L-NAME demonstrated a significant suppression in resumption of meiosis. This inhibition was reversed by the addition of SNP. No development beyond the four-cell stage was observed by the addition of high concentration of SNP (10(-3) M). Inhibition of embryo development, especially the conversion of morulae to blastocysts, was also observed in the treatment of lower doses of SNP (10(-5) and 10(-7) M). Similarly, inhibition of NO by NOS inhibitor resulted in the dose-dependent inhibition of embryo development and hatching rates, but the concomitant addition of SNP with L-NAME reversed the inhibitory effect by each SNP or L-NAME treatment. Furthermore, low concentration of SNP (10(-7) M) but not high concentration of SNP (10(-3) M) significantly stimulated trophoblast outgrowth, whereas the addition of L-NAME suppressed the spreading of blastocysts in a dose-dependent manner. These results suggest that NO may have crucial roles in oocyte maturation and embryogenesis including the process of implantation. The observed differences in required amount of NO and the sensitivity to cytotoxicity of NO in each developmental stage embryos may also suggest that NO/NOS system is tightly regulated in developmental stage specific manner.

Animals↗
PubMed2001

Controlled immobilization of DNA molecules using chemical modification of mica surfaces for atomic force microscopy: characterization in air.

Immobilization of biomolecules on surfaces while keeping the maximum conformational flexibility of the molecules is one of the most important techniques for atomic force microscopy imaging. We have developed two methods of controlling adsorption of DNA molecules on mica surfaces. The first method is the use of a mica surface modified with diluted 3-aminopropyltriethoxysilane (APS). Here we named this a "diluted APS-treated mica (AP-mica)" technique. The second method is the use of a mica surface modified with mixed self-assembled monolayers of organosilanes. In both of the techniques, the number of DNA molecules immobilized on a mica surface was controlled. Further, a conformational change of circular DNA, from a supercoiled to a relaxed form was observed for the molecules immobilized on a diluted AP-mica surface, when 254-nm UV light was irradiated. This observation demonstrated that flexibility of circular DNA molecules was kept on a diluted AP-mica surface.

Air↗
PubMed2001

Role of (111)In-DTPA-pentetreotide scintigraphy in accurate diagnosis of neuroendocrine gastroenteropancreatic tumors.

Most gastroenteropancreatic neuroendocrine tumors contain high-affinity binding sites for somatostatin, and somatostatin-receptor scintigraphy has been introduced for the in-vivo evaluation of such tumors. We report two patients with gastroenteropancreatic neuroendocrine tumors, in whom it was quite difficult to localize the tumors by conventional techniques, and in whom we found that (111)In-DTPA-pentetreotide scintigraphy was useful for accurate information on tumor localization. In the first patient, who had gastrinoma, multiple tumors were shown in the gastrinoma triangle, but we could not clarify whether there were any tumors in the pancreatic body. The selective arterial secretin injection (SASI) test diagnosed that the gastroduodenal artery was the feeder of the gastrinomas, and (111)In-DTPA-pentetreotide scintigraphy with single-photon emission computed tomography indicated the absence of tumors in the pancreatic body. In the second patient, who had insulinoma, multiple liver tumors and a large mass in the hilum of the spleen were shown. (111)In-DTPA-pentetreotide scintigraphy was useful in determining that there was no secretion of insulin from the tumor in the hilum of the spleen. In conclusion, X-ray computed tomography is superior for detection of neuroendocrine tumors, because not all neuroendocrine tumors have somatostatin receptors; however, somatostatin receptor scanning, as well as the SASI test, may be useful for the surveillance of patients with known primary tumors, for monitoring patients with disseminated disease, and for following the treatment of these patients.

Adult↗
PubMed2001

Evaluation of the acetaminophen absorption test for early detection of orthotopic small bowel transplant rejection.

We evaluated the efficiency of the acetaminophen (AC) absorption test as a marker of graft rejection in orthotopic small bowel transplantation (SBTX) in rats. Brown Norway (BN) rats were used as donors and Lewis (LEW) rats as recipients. Orthotopic allogenic SBTX was accomplished using a cuff technique for vessel anastomosis. Animals were divided into: group A (n = 9), untreated; group B (n = 15), extended small bowel resection; group C (n = 12), syngeneic SBTX without immunosuppressants; group D (n = 15), allogenic SBTX with tacrolimus (0.1 mg/kg per day); group E (n = 15), allogenic SBTX with tacrolimus (0.5mg/kg per day). Serum AC was measured 15 min following the instillation of 0.15 g/kg AC into the stomach on postoperative days (POD) 1, 3, and 7. Grafts were examined histologically. The group D grafts showed progressive acute rejection histologically, from normal on POD 1, to moderate on POD 3, and severe on POD 7. Serum AC in group D decreased significantly from 53.1 +/- 3.9 microg/ml on POD 1, to 35.0 +/- 12.0 microg/ml on POD 3, and 10.9 +/- 5.6 microg/ml on POD 7. No remarkable change was observed in the other groups. Serum AC correlated well with histological changes in rats subjected to SBTX, resulting in acute rejection. The AC absorption test could be useful for detection of progressive graft rejection in clinical SBTX.

Absorption↗
PubMed2001

A new idea for a protective balloon system during carotid stenting.

Percutaneous transluminal angioplasty with stenting for high-grade carotid stenosis has been recently come into use. However, distal embolic events remain a problem with this procedure compared to results with established carotid endarterectomy. To counteract such problems, various blocking balloon system such as a simple distal blocking balloon system or a thrombi catching system have been used in some instances. This time, a double-balloon system was used as a proximal blocking system during predilation, and an existing distal blocking system was used during practical carotid stenting. These systems were applied to six cases. In addition, we used a modified conventional blood transfusion system for filtration and retrieval of the aspirated blood. Compared with the simple distal blocking balloon system, occurrence of distal emboli could be reduced with our new combined method although the number of cases is too small to reach any definite conclusions.

Aged↗
PubMed2001

Pure V1 trigeminal neuralgia caused by a cryptic trigeminal neurinoma.

Most idiopathic trigeminal neuralgias are caused by vascular compression at the root entry zone of the trigeminal nerve. (Dandy [1] and Jannetta [2]) We report a case of pure V1 trigeminal neuralgia caused by a small trigeminal neurinoma which had not been detected on preoperative neuroradiological examination.

Diagnosis, Differential↗
PubMed2001

Effect of intrahepatic omental implantation on angiogenesis in rat liver with hepatic artery ligation.

Despite early surgical intervention, the results of treating hepatic artery thrombosis remain poor. The use of omental flaps is well documented for its angiogenic potential in promoting neovascularization in ischemic tissues. This experimental study evaluated the formation of new blood-vessels after omental implantation (OI) in rats after ligation of the hepatic artery. Wistar rats were used and divided into the following groups: I OI with HAL, II OI without HAL, III hepatic artery ligation (HAL). For angiography, measurements were made of liver tissue blood flow by the laser Doppler method and of hepatic artery flow by the colored microsphere method (CMS), and immunohistochemical study was done for vascular endothelial growth factor (VEGF). The rats were killed at 1, 3, 7 or 30 days after laparotomy. Relative arterial hepatic blood flow in the implanted lobe of group I, as determined by CMS, reached 50% of control values 7 days after surgery. Angiography and microscopic studies of the excised liver revealed distinct angiogenesis surrounding the omental implant in the liver for 7 days postoperatively. The formation of new blood-vessels after OI was not observed in livers without HAL. Omental implantation appears to be useful in preventing organ anoxia after hepatic artery thrombosis.

Animals↗
PubMed2001

A longitudinal study of disturbances of the hypothalamic-pituitary-adrenal axis in women with progestin-negative functional hypothalamic amenorrhea.

OBJECTIVE: To longitudinally evaluate disturbances of the hypothalamic-pituitary-adrenal (HPA) axis in women with secondary progestin-negative hypothalamic amenorrhea. DESIGN: Retrospective cohort study. SETTING: Yokohama City University, Yokohama, Japan. PATIENT(S): Twenty-four women with progestin-negative hypothalamic amenorrhea. INTERVENTION(S): Administration of human corticotropin-releasing hormone (hCRH) and treatment with a combination of estrogen and progesterone. MAIN OUTCOME MEASURE(S): Plasma cortisol and ACTH concentrations and period required for recovery from amenorrhea. RESULT(S): Plasma ACTH concentrations 30 and 60 minutes after injection of hCRH and the percent maximum increment (%Cmax) of ACTH were significantly lower in the amenorrheic patients compared with the control group patients. The basal cortisol was significantly higher, and the %Cmax of cortisol was significantly lower. In the 16 patients who recovered from amenorrhea, there was a significant positive correlation (Y = 1.93X-10.8, r = 0.629) between the basal cortisol concentrations (X) and the period for recovery (Y). The serum E2 gradually increased before recovery, and this E2 increase was preceded by changes in the plasma cortisol concentration and the %Cmax values of cortisol and ACTH. CONCLUSION(S): The CRH test might be useful for evaluating the roles of stress and for estimating the period required for recovery in hypothalamic amenorrhea.

Adrenocorticotropic Hormone↗
PubMed2001

Synthesis, structural characterization and antimicrobial activities of 4- and 6-coordinate nickel(II) complexes with three thiosemicarbazones and semicarbazone ligands.

To investigate the relationship between antimicrobial activities and the molecular structures of nickel(II) complexes with thiosemicarbazone and semicarbazone ligands, nickel(II) complexes with ligands Hmtsc, Hatsc, Hasc and H2dmtsc, were prepared and characterized by elemental analysis, FT-IR, 1H and 13C NMR spectroscopies, magnetic susceptibility measurements, UV-Vis absorption spectra, TG/DTA and single-crystal X-ray analysis. Their antimicrobial activities were evaluated by the MIC against four bacteria (B. subtilis, S. aureus, E. coli and P. aeruginosa), two yeasts (C. albicans and S. cerevisiae) and two molds (A. niger and P. citrinum). The 4-coordinate, diamagnetic nickel(II) complexes showed antimicrobial activities which were different from those of free ligands or the starting nickel(II) compounds; [Ni(mtsc)(OAc)] 1 showed selective and effective antimicrobial activities against two Gram-positive bacteria (B. subtilis and S. aureus) and modest activities against a yeast (S. cerevisiae), [Ni(mtsc)Cl] 3 exhibited moderate activities against a Gram-positive bacterium (S. aureus), and [Ni(atsc)(OAc)] 5 showed modest activities against two Gram-positive bacteria (B. subtilis and S. aureus). On the other hand, the 6-coordinate, paramagnetic nickel(II) complexes with two protonated or deprotonated ligands ([Ni(mtsc)2] 2, [Ni(atsc)(mtsc)] 4, [Ni(atsc)2] 6, [Ni(Hatsc)2](NO3)(2)7, [Ni(Hatsc)2]Cl(2)8 and [Ni(Hasc)2](OAc)(2)9) and the sterically crowded 4-coordinate, diamagnetic nickel(II) complex ([Ni(dmtsc)] 10) did not inhibit the growth of the test organisms. The structure-activity correlation in this series of nickel(II) complexes was discussed based on their ligand-replacement abilities.

Anti-Bacterial Agents↗
PubMed2001

The magnitude of variation in temperature within a year has an effect on the seasonal variations of chickenpox incidence in Japan.

We investigated the epidemic pattern of chickenpox incidence among 47 prefectures in Japan. There were two peaks in chickenpox incidence in all prefectures. The first peaks appear at almost the same time in a year, while the second peaks occur at different times with relatively different types of size and shape. The feature of the second peak might characterize the epidemic pattern of chickenpox. We first introduced the second peak index, that is, the ratio of the difference between the incidence at the point of the second peak and the minimum incidence between the first and second peaks to the difference between the incidence at the point of the second peak and the minimum incidence in the year. There was a close correlation between the second peak index and the magnitude of variation in temperature within a year corresponding to the difference between the maximum and the minimum of the monthly mean of the highest daily temperature. This is the first article focusing on the close relationship between the second peak of epidemic pattern of chickenpox incidence and the variation of temperature within a year.

Chickenpox↗
PubMed2001

Flexible video cystoscope with built-in high-frequency cauterizing element for transurethral resection of bladder tumor.

The major advantage of the flexible video cystoscope is that a digital signal can be obtained while high frequency cauterization is carried out. Cauterization while observing a digital signal picture was not possible before this new model was developed. We decided to use this new cystoscope to resect a bladder tumor and coagulate the bleeding because the patient could tolerate only local anesthesia due to severe heart disease complications. We successfully treated the patient with this technique and no complications were noted. This new flexible video cystoscope was found to be safe for resecting bladder tumor under local anesthesia.

Aged↗
PubMed2001

Predictability of internal carotid artery (ICA) dissectability in cases showing ICA involvement in parasellar meningioma.

The present study identified predictors for surgical internal carotid artery (ICA) dissection in cases showing ICA involvement in parasellar meningiomas. Twelve cases encountered over the past 4 years were reviewed. Based on MRI findings, patients were divided into two groups; six patients demonstrated complete ICA involvement (encasement) and the other six showed partial ICA involvement (engulfment). The ICA was dissected in all cases in the engulfment group and in four of six cases in the encasement group. The ICA can be dissected even if it is involved at the centre of the tumour if the tumour is soft and can be aspirated. Preservation of the perforating arteries is more important and more difficult. Angiographic finding showing encasement of a long segment of the ICA is unfavourable because of the high possibility that the perforating arteries are involved. Local stenosis of ICA is another unfavourable finding for surgical dissection because tumour invasion of the arterial wall would be suspected. Thus, ICA encasement by the tumour is the less favourable finding for surgery but it is not a decisive predictor. More important findings for ICA dissection in cases showing ICA encasement are involvement of a long segment of the ICA and local ICA stenosis on angiogram.

Aged↗
PubMed2001

Method for orienting DNA molecules on mica surfaces in one direction for atomic force microscopy imaging.

An efficient method was developed to stretch DNA molecules on an atomically flat surface for AFM imaging. This method involves anchoring DNA molecules from their 5' ends to amino silanized mica surfaces. N-Succinimidyl6-[3'-(2-pyridyldithio) propionamido]hexanoate (LC-SPDP), a heterobifunctional cross-linker with a flexible spacer arm was used for this purpose. Immobilization was carried out by introducing a thiol group to the 5' end of DNA by PCR. Thiolated molecules were then reacted with the cross linker to conjugate with its 2-pyridyl disulphide group via sulfhydryl exchange. The resulting complex was deposited on amino silanized mica where NHS-ester moiety of the cross linker reacted with the primary amino group on the surface. Samples were washed by a current of water and dried by an air jet in one direction parallel to the surface. DNA molecules were fully stretched in one direction on imaging them by AFM.

Aluminum Silicates↗