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Biomedical subjects

K Kohno

Publications and source records attributed to K Kohno.

At least 217 records · Page 12Linked to original sources
PubMed1996

[The evaluation of the bio-compatibility and the clinical usefulness of heparin-coated cardiopulmonary bypass circuits].

We studied the biocompatibility and the clinical usefulness of heparin-coated cardiopulmonary bypass circuits (Duraflow-II) compared with non-coated circuits. First study was done to clarify the biocompatibility of heparin coated circuit. 33 cases of elective coronary artery bypass grafting were randomized into two grops. Both group had full dose heparin in this study and laboratory tests were done such as blood cell count, free hemoglobin, AT-III, fibrinogen, FDP, and complement system. The use of heparin-coated circuits resulted in a reduction of C3a generation, and a reduction of fibrinogen consumption. The decline of AT-III may be due to bonding of coated heparin to AT-III, leading to effective anticoagulation. Next study was carried out in 26 cases. In heparin coated group, the amount of heparin was reduced to 200 IU/kg compared to 350 IU/kg in control group. ACT was maintained above 300 sec. and 400 sec. respectively. The amount of post operative bleeding was identical in both groups. There was no case which required autologous blood transfusion, re-operation for bleeding in both groups. Myocardial infarction and hospital mortality were not seen in this study. Concerning the fear of graft occlusion in low dose heparin surgery, there was no statistical difference of graft patency in both groups. In conclusion, heparin coated CPB circuits (Duraflo-II) are favorable in the meaning of biocompatibility and sefely used with low dose heparin.

Biocompatible Materials↗
PubMed1996

[Surgical treatment of pericostal tuberculosis].

The following two points must be considered on treating pericostal tuberculosis: the first is the appropriate time to treat pericostal tuberculosis surgically when the medical therapy fails to induce a remission, and the second is how to prevent postoperative relapse. In the present study, we investigated these two points by examining seven patients who underwent surgery at the department of thoracic surgery (Osaka Red Cross Hospital), during a 10 years period from January 1985 to December 1994. Antituberculotics were administered to these patients for an average of 3.9 months before surgery, but in vain. Therefore, they were surgically treated. In all cases, the incision was closed at once, and there were no severe complications. The signs and symptoms disappeared soon after surgery. It has been reported that the medical treatment leads to recovery or tendency to recovery within three months of drug administration. The conditions of pericostal tuberculosis patients during this period can be used as indicators to decide whether or not to carry out surgical treatment. Also, by active excision of the rib and tumor as one mass, and by administering antituberculotic for 13.1 months after surgery, no relapse took place during the follow-up period (average 37.4 months). And the postoperative respiratory functions did not decrease compared to those before surgery.

Adult↗
PubMed1996

[Incidence of synchronous or metachronous multiple primary cancers and aggregation of cancers in families of patients with endometrial cancer].

We evaluated the incidence of synchronous or metachronous multiple primary cancer, hereditary or familial cancer, and the familial aggregation of cancer in 142 patients who were treated for endometrial cancer at Tsukuba University Hospital in the period 1977 to 1995. Synchronous multiple primary cancers were identified in 6 of the 142 patients (4.2%). Eleven patients (7.7%) had a history of extraendometrial cancer. Patients with endometrial cancer had a significantly high incidence of a history of breast cancer. Endometrial cancer was diagnosed in two patients who were screened before menopause. Four patients with endometrial cancer (2.8%) subsequently developed extraendometrial forms of cancer. One patient (0.7%) was considered to have a hereditary form of cancer, and 5 patients (3.5%) had familial forms of cancer. A total of 86 cases of cancer were found among 53 kindred (37.3%). More detailed studies are needed to elucidate the aggregation of cancers in the families of patients with endometrial cancer in Japan. Patients with a history of breast cancer should be screened for the presence of endometrial cancer.

Adenocarcinoma↗
PubMed1996

Decreased DNA topoisomerase II alpha expression and cold-sensitive growth in a mouse mammary cancer cell line resistant to etoposide and doxorubicin.

A mouse mammary carcinoma FM3A cell line resistant to the DNA topoisomerase (topo) II-targeting agent, etoposide (VP-16), FM3A/VP-2B, had a markedly reduced growth rate at a low temperature (33 degrees C). The cells had the following properties: (a) FM3A/VP-2B, which had 24-fold higher resistance to VP-16 than its parental line, FM3A, was cross-resistant to doxorubicin, but not to a camptothecin derivative, CPT-11. (b) Cold-resistant revertants from FM3A/VP-2B, R-6 and R-11, remained 8- to 9-fold more resistant to VP-16 and 2- to 3-fold more resistant to doxorubicin. (c) FM3A/VP-2B had one-fourth the level of topo II activity and one-third of the topo II alpha content and mRNA of FM3A. R-6 and R-11, however, had levels similar to FM3A. (d) FM3A/VP-2B and FM3A had a 3-base deletion at position 4170 on one allele on the topo II alpha cDNA, but expression of the wild-type and the deletion allele was not appreciably changed in both cell lines. Decreased topo II alpha expression might have led to the acquisition of drug resistance to etoposide in FM3A/VP-2B, and appeared to be linked with the cold-sensitive growth. We also present a corrected mouse topo II alpha cDNA sequence.

Amino Acid Sequence↗
PubMed1995

The exogenous control of transfected c-fos gene expression and angiogenesis in cells implanted into the rat brain.

Previously, we established a stable transfectant, Nf-1, from normal rat kidney (NRK) fibroblasts transfected with a human metallothionein II A (hMT-IIA) promoter/human genomic c-fos fusion gene to produce c-Fos protein. Since the hMT-IIA promoter can be activated by heavy metals, the level of human c-fos gene expression can be increased by addition of heavy metals to the culture medium of Nf-1 cells and the anchorage-independent growth of Nf-1 in soft agar is markedly enhanced in the presence of transforming growth factor-beta (TGF-beta) and epidermal growth factor (EGF). In this study, we found that the hMT-IIA promoter can be activated by zinc, resulting in the elevation of fused c-fos gene expression in Nf-1 cells. We transplanted NRK and Nf-1 cells into the striatum of the rat brain and investigated whether expression of the human c-fos gene could be modified in the brain by exogenous zinc. After 8 weeks, we found that the Nf-1 cells could survive in the rat brain without any immunosuppression and grafts of Nf-1 induced angiogenesis when zinc was administered. Such implants enhanced the expression of c-fos mRNA by zinc. These results indicated that the transplanted cells continued expressing the c-fos transgene when the rats were given drinking water containing zinc, resulting in the promotion of cell growth and of neovascularization. This study will present a useful animal model of gene therapy by control of transgene expression in the brain.

Animals↗
PubMed1995

Intraventricular administration of nitric oxide synthase inhibitors prevents delayed neuronal death in gerbil hippocampal CA1 neurons.

We performed experiments to investigate the participation of nitric oxide (NO) in the delayed neuronal death (DND) of gerbil hippocampal CA1 neurons, following 5-min forebrain ischemia with pretreatment of stereotaxic intraventricular administration of several types of NO synthase inhibitors and biologically inactive control drugs. The number of surviving neurons in the control drug groups administered NG-monomethyl-D-arginine or NG-nitro-D-arginine methyl ester was comparable to that in the group administered artificial cerebro-spinal fluid, while the groups administered NOS inhibitors, such as NG-monomethyl-L-arginine or NG-nitro-L-arginine methyl ester, showed significant preservation of the neuronal densities compared with the control drug groups, to over 60% of the sham operation group value. Furthermore, intraventricular administration of N omega-nitro-L-arginine at various concentrations disclosed a dose-dependent protection against the DND. These results suggest that the generation of NO may act to promote the establishment of DND.

Animals↗
PubMed1995

Cellular levels of thioredoxin associated with drug sensitivity to cisplatin, mitomycin C, doxorubicin, and etoposide.

Thioredoxin, a cellular thiol, functions as a self-defense mechanism in response to environmental stimuli, including oxidative stress. We first determined cellular levels of thioredoxin in several human bladder and prostatic cancer cell lines resistant to cis-diamminedichloroplatinum(II) (cisplatin). All cisplatin-resistant cell lines had much higher levels of thioredoxin than those in their drug-sensitive parental counterpart. We then, by introducing thioredoxin antisense expression plasmids into human bladder cancer T24 cells, established two bladder cancer cell lines that had decreased levels of thioredoxin. These thioredoxin antisense transfectants showed increased sensitivity to cisplatin and also to other superoxide-generating agents, i.e., doxorubicin, mitomycin C, etoposide, and hydrogen peroxide, as well as to UV irradiation, but not to the tubulin-targeting agents, vincristine, and colchicine. Cellular levels of thioredoxin thus appear to limit sensitivity to various superoxide-generating anticancer drugs in cancer cells.

Antineoplastic Agents↗
PubMed1995

Expression and functional analyses of the Dxpa gene, the Drosophila homolog of the human excision repair gene XPA.

Xeroderma pigmentosum (XP) is a human hereditary disease characterized by a defect in DNA repair after exposure to ultraviolet light. Among the seven groups of XP, group A (XP-A) patients show the most severe deficiency in excision repair and a wide variety of cutaneous and neurological disorders. We have cloned homologs of the human XPA gene from chicken, Xenopus, and Drosophila, and sequence analysis revealed that these genes are highly conserved throughout evolution. Here, we report characterization of the Drosophila homolog of the human XPA gene (Dxpa). The Dxpa gene product shows DNA repair activities in an in vitro repair system, and Dxpa cDNA has been shown to complement a mutant allele of human XP-A cells by transfection. Polytene chromosome in situ hybridization mapped Dxpa to 3F6-8 on the X chromosome, where no mutant defective in excision repair was reported. Northern blot analysis showed that the gene is continuously expressed in all stages of fly development. Interestingly, the Dxpa protein is strongly expressed in the central nervous system and muscles as revealed by immunohistochemical analysis using anti-Dxpa antibodies, consistent with the results obtained in transgenic flies expressing a Dxpa-beta-galactosidase fusion gene driven by the Dxpa promoter.

Amino Acid Sequence↗
PubMed1995

Role of HU proteins in forming and constraining supercoils of chromosomal DNA in Escherichia coli.

Induction of supercoiling in plasmid DNA by HU heterotypic and homotypic dimers, a mutant HU-2 (HupAN12), HBs and HB1 proteins with different DNA-binding affinities was investigated in vitro. The abilities of these proteins to induce supercoiling in DNA correlated with their affinities for DNA. Stoichiometrical analysis of HU heterodimers bound to DNA in the complex restraining the negative torsional tension of DNA showed that 12-13 dimers account for a single superhelical turn. The number of supercoils in the plasmid in vivo decreased on inhibition of DNA gyrase with coumermycin, reaching a steady-state level that indicated the existence of a compartment of restrained supercoils. The size of the restrained compartment was reduced in the absence of HU, indicating the participation of HU in constituting this fraction, and was larger on overproduction of HU-2 in the cells. An increased level of DNA gyrase, expressed from a plasmid carrying both gyr genes, in the cells did not compensate for the deficit of the restrained supercoils caused by HU deficiency, indicating seeming distinct and unrelated action of HU and DNA gyrase in introducing and constraining supercoiling of intracellular DNA.

Bacterial Proteins↗
PubMed1995

DNA topoisomerase II alpha gene expression under transcriptional control in etoposide/teniposide-resistant human cancer cells.

We previously isolated etoposide/teniposide-resistant cell lines from human cancer KB cells, designated KB/VP-2 and KB/VM-4, respectively, and we found that decreased expression of topoisomerase II alpha was associated with the acquisition of etoposide/teniposide resistance in both resistant cell lines. In this study, we studied how the expression of the DNA topoisomerase II alpha gene is regulated in drug-resistant cell lines at the transcriptional level. We first examined whether the decreased topoisomerase II alpha mRNA level was due to a shorter lifetime of mRNA molecules in drug-resistant cell lines. A comparison of the degradation kinetics of topoisomerase II alpha mRNA demonstrated that there was no difference in mRNA stability between both resistant cell lines and their parental counterpart. A run-on experiment with isolated nuclei showed that the transcriptional activity of topoisomerase II alpha gene of both resistant cell lines constituted less than 20% of the parental KB cells. The activity of DNA topoisomerase II alpha promoter in resistant cells was also less than 20% of that in KB cells when transient transfection assays were performed with the promoter-driven bacterial chloramphenicol acetyltransferase gene. Among the several transcription factors that might be involved in DNA topoisomerase II alpha gene expression, expression of Sp3, an inhibitory member of the Sp1 family, was elevated to about 3-fold higher in both resistant cell lines than their parental counterpart. These results indicated that the expression of DNA topoisomerase II alpha gene decreased at the transcriptional level through the enhanced expression of Sp3 in our two etoposide/teniposide-resistant cell lines.

Antigens, Neoplasm↗
PubMed1995

Markedly decreased expression of glutathione S-transferase pi gene in human cancer cell lines resistant to buthionine sulfoximine, an inhibitor of cellular glutathione synthesis.

Buthionine sulfoximine (BSO) is a synthetic amino acid that irreversibly inhibits an enzyme, gamma-glutamylcysteine synthetase (gamma-GCS), which is a critical step in glutathione biosynthesis. We isolated three BSO-resistant sublines, KB/BSO1, KB/BSO2, and KB/BSO3, from human epidermoid cancer KB cells. These cell lines showed 10-to 13-fold higher resistance to BSO, respectively, and had collateral sensitivity to cisplatin, ethacrynic acid, and alkylating agents such as melphalan and nitrosourea. Cellular levels of glutathione S-transferase pi (GST-pi) and its mRNA in BSO-resistant cell lines were less than 10% of the parental cells. Nuclear run-on assay showed that the transcriptional activity of GST-pi was decreased in BSO-resistant cells, and transient transfection of GST-pi promoter-chloramphenicol acetyltransferase constructs revealed that the sequences between -130 and -80 base pairs of the 5'-flanking region wer at least partially responsible for the decreased expression of the GST-pi gene. By contrast, gamma-GCS mRNA levels were 3-to 5-fold higher in resistant cell lines than in KB cells, and the gamma-GCS gene was found to be amplified in the BSO-resistant cells lines. GST-pi mRNA levels appeared to be inversely correlated with gamma-GCS mRNA levels in BSO-resistant cells. We further established the transfectants, KB/BSO3-pi1 and KB/ BSO2-pi2, that overexpressed GST-pi, from KB/BSO3, after introducing a GST-pi expression plasmid. These two transfectants had similar levels in gamma-GCS mRNA, drug sensitivity to alkylating agents, and glutathione content at those of KB cells. These findings suggest that the cellular levels of GST-pi and gamma-GCS might be co-regulated in these novel BSO-resistant cells.

Blotting, Southern↗
PubMed1995

Modulation by bovine angiogenin of tubular morphogenesis and expression of plasminogen activator in bovine endothelial cells.

Angiogenin is a potent angiogenic molecule in the chick chorioallantoic membrane assay and rabbit corneal assay. However, no angiogenic activity has been reported in in vitro system. In this study, we isolated and purified angiogenin from bovine milk, and the biological effect of the bovine angiogenin on bovine endothelial cells was examined in in vitro angiogenesis models. Bovine angiogenin significantly stimulated both cell migration and formation of tube-like structures in the collagen gel by bovine aortic endothelial cells. Angiogenin at 10-100 ng/ml stimulated about 2-fold higher the tube formation when basic fibroblast growth factor (bFGF) at 10 ng/ml stimulated about 3-fold over the control. Tubular morphogenesis stimulated by bFGF or angiogenin was almost completely blocked in the presence of aprotinin, an inhibitor of serine proteases. Angiogenin up-regulated both mRNA level and activity of urokinase type plasminogen activator, a key mediator of angiogenesis. Moreover, both bFGF and bovine angiogenin induced a marked increase of c-fos mRNA level at 30 min after stimulation. These novel effects of bovine angiogenin are to be discussed in relation to its structure specificity.

Allantois↗
PubMed1995

Quantitative measurement of regional blood flow with gadolinium diethylenetriaminepentaacetate bolus track NMR imaging in cerebral infarcts in rats: validation with the iodo[14C]antipyrine technique.

NMR bolus track measurements were correlated with autoradiographically determined regional cerebral blood flow (rCBF). The NMR method is based on bolus infusion of the contrast agent gadolinium diethylenetriaminepentaacetate and high-speed T*2-sensitive NMR imaging. The first pass of the contrast agent through the image plane causes a transient decrease of the signal intensity. This time course of the signal intensity is transformed into relative concentrations of the contrast agent in each pixel. The mean transit time and relative blood flow and volume are calculated from such indicator dilution curves. We investigated whether this NMR technique correctly expresses the relative rCBF. The relative blood flow data, calculated from NMR bolus track experiments, and the absolute values of iodo[14C]antipyrine autoradiography were compared. A linear relationship was observed, indicating the proportionality of the transient NMR signal change with CBF. Excellent interindividual reproducibility of calibration constants is observed (r = 0.963). For a given NMR protocol, bolus track measurements calibrated with autoradiography after the experiment allow determination of absolute values for rCBF and regional blood volume.

Animals↗
PubMed1995

Expression of vascular endothelial growth factor and its possible relation with neovascularization in human brain tumors.

To examine which growth factors correlate with neovascularization in human brain tumors, the mRNA levels of transforming growth factor alpha, transforming growth factor beta, basic fibroblast growth factor, and vascular endothelial growth factor (VEGF) genes were determined by a Northern blot analysis in surgically obtained human gliomas and meningiomas. The vascular development was determined by counting the number of microvessels which were immunostained with von Willebrand factor. We normalized the growth factor mRNA levels versus the glyceraldehyde phosphate dehydrogenase mRNA level. In the 17 gliomas and 16 meningiomas examined, the mRNA of transforming growth factors alpha and beta, basic fibroblast growth factor, and VEGF were expressed at various levels. Among those 4 growth factors, the mRNA levels of VEGF, but not those of transforming growth factors alpha and beta and basic fibroblast growth factor, correlated significantly with vascularity in both gliomas (correlation coefficient r = 0.499; P < 0.05) and meningiomas (correlation coefficient r = 0.779; P < 0.001). These findings thus suggest that VEGF may be a positive factor in tumor angiogenesis in both human gliomas and meningiomas.

Brain Neoplasms↗
PubMed1995

Heterogeneity of circulating and exudated polymorphonuclear leukocytes in superoxide-generating response to cyclic AMP and cyclic AMP-elevating agents. Investigation of the underlying mechanism.

It has been found that cyclic AMP and cyclic AMP-elevating agents inhibit formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated superoxide production from polymorphonuclear leukocytes (PMNs). The quantitative differences of this inhibitory effect on human and rabbit blood versus human salivary and rabbit peritoneal (tissue) PMNs were investigated. PMNs from all sources showed the same pattern of fMLP-stimulated superoxide generation, although it was slightly higher in tissue PMNs. However, treatment with salbutamol differentially blunted fMLP-stimulated superoxide production from blood PMNs compared with tissue PMNs in both human and rabbit. While it could inhibit production from blood PMNs by 30-60%, it had only a negligible effect on generation from tissue PMNs. Similarly, forskolin, phosphodiesterase IV inhibitor Ro-201724, and dibutryl cyclic AMP showed significantly higher inhibitory effects on superoxide generation from blood PMNs than tissue PMNs in both species. beta-Adrenergic receptors, cyclic AMP accumulation, and protein kinase A activity were investigated in blood versus tissue PMNs to clarify the mechanism underlying the above-mentioned differences. At the beta-adrenergic receptor level, no significant changes were detected in the number or the binding affinity of the receptors in tissue versus blood PMNs of human and rabbit. On the other hand, cyclic AMP accumulation was significantly higher in response to salbutamol and Ro-201724 in fMLP-stimulated blood versus tissue PMNs in human and rabbit. At the same time, blood PMNs showed significantly higher cyclic AMP-dependent protein kinase A activity than tissue PMNs in human and rabbit. We concluded that tissue PMNs are less responsive to the effect of cyclic AMP-elevating agents in terms of fMLP-stimulated superoxide inhibition. This is due to differences, at least, at two levels. The first is lower accumulation of cyclic AMP and the second is lower protein kinase A activity in tissue versus blood PMNs.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗
PubMed1995

Changes of relaxation times (T1, T2) and apparent diffusion coefficient after permanent middle cerebral artery occlusion in the rat: temporal evolution, regional extent, and comparison with histology.

The quantitative NMR parameters T1, T2, rho, and apparent diffusion coefficient (ADC) were determined during the 7 h after middle cerebral artery occlusion in rats. In the normal caudate-putamen (CP), 869 +/- 145 ms and 72 +/- 2 ms for T1 and for T2, respectively, were found; the corresponding values for cortex were 928 +/- 117 ms and 73 +/- 2 ms. The ADC showed significant dependence on gradient direction: diffusion along x resulted in 534 +/- 53 microns 2/s (CP) and 554 +/- 62 microns 2/s (cortex), and along y in 697 +/- 58 microns 2/s (CP) and 675 +/- 53 microns 2/s (cortex). In the ischemic territory, a continuous increase over time of both relaxation times was observed in the CP, leading to an increase of 29 +/- 20% (T1) and 51 +/- 41% (T2) above control level. ADC dropped to 63 +/- 15% of control in the CP and to 74 +/- 4% of control in the temporal cortex. No significant change was noted in proton density during the observation period. Strongest ADC reduction was in the center of the ischemic territory (< or = 60% of control) surrounded by a region of lesser reduction (< or = 80% of control). During the early part of the study, the area of reduced ADC was larger than that of elevated relaxation times. Toward the end of the experiment, the area of increased relaxation times approached that of decreased ADC at < or = 80% of control. Good agreement of histological presentation of infarct with the total area of decreased ADC (< or = 80%) was demonstrated.

Animals↗
PubMed1995

Evolution of acute focal cerebral ischaemia in rats observed by localized 1H MRS, diffusion-weighted MRI, and electrophysiological monitoring.

Focal cerebral ischaemia was produced in 11 rats by permanent occlusion of the right middle cerebral artery (MCA) using a suture model modified to enable manipulation with the animals in situ in an NMR spectrometer. The development of the ischaemic insults and the resultant infarcts were observed for up to 6 h by localized 1H MRS and diffusion-weighted MRI while performing continuous monitoring of electroencephalogram and extracellular DC potential. The ischaemic areas were depicted as regions of hyperintensity in the diffusion-weighted images. Signals due to lactate became visible in the 1H spectra after MCA occlusion indicating the onset of anaerobic glycolysis. A depletion of N-acetylaspartate was seen in all animals post-occlusion. Transient or stepwise increases of lactate were observed to occur coincidentally with the events of spontaneous transient peri-infarct depolarization detected by the electrophysiological measurements. Expansion of the ischaemic area delineated in the diffusion-weighted images also accompanied peri-infarct depolarizations. These observations are consistent with transient peri-infarct depolarization playing a role in the growth of infarcts.

Acute Disease↗