Biomedical subjects

T Todo

Publications and source records attributed to T Todo.

At least 73 records · Page 4Linked to original sources

PubMed1996

Molecular cloning of the cDNAs encoding pituitary glycoprotein hormone alpha- and gonadotropin II beta-subunits of the Japanese eel, Anguilla japonica, and increase in their mRNAs during ovarian development induced by injection of chum salmon pituitary homogenate.

cDNAs encoding the glycoprotein hormone alpha- and gonadotropin (GTH) II beta-subunits of Japanese eel (Anguilla japonica) pituitary were cloned using the polymerase chain reaction. The nucleotide sequence of the glycoprotein hormone alpha-subunit cDNA was 364 base pairs (bp) long, encoding 117 amino acids, and that of the GTH II beta-subunit cDNA was 433 bp long, encoding 140 amino acids. The deduced amino acid sequence of each mature subunit showed high homology with those of other teleosts, indicating that the structure of GTH subunits has been conserved during the evolution of teleosts. Changes in the expression of these subunit genes during ovarian development induced artificially by the injection of chum salmon pituitary homogenate were examined using Northern blot analysis. Glycoprotein hormone alpha-subunit mRNA increased almost linearly during ovarian development, whereas GTH II beta-subunit mRNA was detected only at the late vitellogenic and migratory nucleus stages. These data indicate that eel GTH II is synthesized mainly at the late vitellogenic and migratory nucleus stages, and suggest that GTH II plays an important role in final oocyte maturation of Japanese eel. Changes in the expression of glycoprotein hormone alpha- and GTH II beta-subunits mRNA correlate with the serum estradiol-17 beta (E(2)) and testosterone profile during ovarian development. The increase in mRNA of both subunits is probably due to positive feedback of E(2) and testosterone produced by ovarian follicles in response to the GTH contained in chum salmon pituitary homogenate.

Amino Acid Sequence↗

PubMed1996

Autocrine growth stimulation of human meningioma cells by platelet-derived growth factor.

The authors have previously shown that meningioma-derived conditioned medium profoundly stimulates the in vitro proliferation of meningioma cells. In this paper, self mitogenic agents found in the conditioned medium-autocrine growth-stimulatory factors actually secreted by human meningioma cells-are characterized as proteins related to the B chain of platelet-derived growth factor (PDGF) and possibly to the A chain of PDGF as well. The addition to conditioned medium of a neutralizing antibody against PDGF-BB caused a significant inhibition of the conditioned medium-stimulated DNA synthesis in all three meningioma cultures studied. A similar neutralizing effect was observed with an anti-PDGF-AA antibody in one meningioma culture studied. Gel filtration chromatography of concentrated conditioned medium from two different meningiomas using a Sephadex G-100 column revealed similar profiles from both conditioned media with a major peak of mitogenic activity against meningioma cells at a molecular weight (M(r)) of approximately 32 to 36 kD, accompanied by a minor peak at approximately 22 kD. The major peak mitogenic activity was significantly reduced by addition of an anti-PDGF-BB antibody. Western blot analysis of protein extracts from five meningioma specimens was performed using a monoclonal antibody against the B chain of PGDF, and a major band of PDGF-B immunoreactivity was detected at an M(r) of approximately 19 kD in all five meningiomas under both reducing and nonreducing conditions. Exogenous human and porcine PDGFs both exhibited a significant dose-dependent stimulation of DNA synthesis in two of three and three of five meningioma cultures examined, respectively. Although not all meningiomas investigated proved to share the biological activity associated with PDGF and these results may be preliminary, it seems that the autocrine growth-stimulatory loop established by PDGF-B-related molecules plays an important functional role in meningioma cell proliferation.

Brain Neoplasms↗

PubMed1995

Novel DNA binding proteins highly specific to UV-damaged DNA sequences from embryos of Drosophila melanogaster.

Three new proteins which selectively bind to UV-damaged DNA were identified and purified to near homogeneity from UV-irradiated Drosophila melanogaster embryos through several column chromatographies. These proteins, tentatively designated as D-DDB P1, P2 and P3, can be identified as different complex bands in a gel shift assay by using UV-irradiated TC-31 probe DNA. Analysis of the purified D-DDB P1 fraction by native or SDS-polyacrylamide gel electrophoresis and FPLC-Superose 6 gel filtration demonstrated that it is a monomer protein which is a 30 kDa polypeptide. The D-DDB P2 protein is a monopolypeptide with a molecular mass of 14 kDa. Both D-DDB P1 and P2 highly prefer binding to UV-irradiated DNA, and have almost no affinity for non-irradiated DNA. Gel shift assays with either UV-irradiated DNA probes demonstrated that D-DDB P1 may show a preference for binding to (6-4) photoproducts, while D-DDB P2 may prefer binding to pyrimidine dimers. Both these proteins require magnesium ions for binding. D-DDB P1 is an ATP-preferent protein. These findings are discussed in relation to two recently described [Todo and Ryo (1991) Mutat. Res., 273, 85-93; Todo et al. (1993) Nature, 361, 371-374] DNA-binding factors from Drosophila cell extracts. A possible role for these DNA-binding proteins in lesion recognition and DNA-binding proteins in lesion recognition and DNA repair of UV-induced photo-products is discussed.

Adenosine Triphosphate↗

PubMed1995

Preferential inhibition of nucleosome assembly by ultraviolet-induced (6-4)photoproducts.

We reconstituted nucleosomes in vitro using two kinds of damaged pBR322 plasmid DNA carrying cyclobutane pyrimidine dimers (CPD) or (6-4)photoproducts. The results indicate that nucleosome assembly is inhibited preferentially by (6-4)photoproducts compared with CPD, suggesting that the regions carrying (6-4)photoproducts retain their nucleosome-free form, i.e. linker-like conformation until completion of the repair processes.

Animals↗

PubMed1995

Lumbar adhesive arachnoiditis following attempted epidural anesthesia--case report.

A 30-year-old female experienced a sudden sharp pain radiating down to the left leg from the lower back at epidural intubation for anesthesia at childbirth. She continued to complain of pain in the left leg afterwards. Magnetic resonance images demonstrated a conglomeration of adherent nerve roots due to lumbar adhesive arachnoiditis. Microsurgical dissection of adherent nerve roots was performed. Her symptoms disappeared after surgery, but soon recurred, being less severe and responsive to anti-inflammatory agents. Lumbar adhesive arachnoiditis should be considered for differential diagnosis in patients presenting with back and leg pain syndrome.

Adult↗

PubMed1994

Cloning of a marsupial DNA photolyase gene and the lack of related nucleotide sequences in placental mammals.

Photoreactivating enzyme, DNA photolyase, reduces lethal, mutagenic and carcinogenic effects of ultraviolet light (UV) by catalyzing near UV or visible light-dependent repair of cyclobutane pyrimidine dimers (CPDs) in DNA. The enzyme activity has been detected in a wide variety of organisms ranging from bacteria to nonplacental mammals. However, the evidence for photoreactivation in placental mammals, including humans, is controversial. As a first step to identify the presence and activity of the gene in mammalian species, we isolated a cDNA clone of this gene from a marsupial, the South American opossum Monodelphis domestica. Photolyase activity was expressed in Escherichia coli from the cDNA which is predicted to encode a polypeptide of 470 amino acid residues. The deduced amino acid sequence of this protein is strikingly similar to those of photolyases from two metazoans; the opossum photolyase shares 59% and 63% sequence identity with the Drosophila melanogaster and goldfish Carassius auratus enzymes, respectively. However, no closely related nucleotide sequence was detected in higher mammals and a homologous transcript was undetectable in a number of human tissues. These results strongly suggest that humans, as well as other placental mammals, lack the photolyase gene.

Amino Acid Sequence↗

PubMed1994

Involvement of protein kinase C in growth regulation of human meningioma cells.

In order to investigate the possible role of protein kinase C (PKC)-mediated signal pathways in growth regulation of meningiomas, we examined the effect of two PKC-activating phorbol esters, 12-O-tetradecanoyl-13-phorbol acetate (TPA) and phorbol 12, 13-dibutyrate (PDBu), and PKC inhibitor, staurosporine, on cell proliferation using low-passage human meningioma cells in culture. TPA (0.1 to 100 ng/ml) caused a dose-dependent stimulation of cell proliferation in six of eight meningioma cultures. At optimal concentrations of TPA, the cell growth ranged from 113% to 251% versus control. In contrast, PDBu (0.1 to 100 ng/ml) caused a significant inhibition of cell proliferation in three of five meningioma cultures. At optimal concentrations of PDBu, the cell growth ranged from 52% to 79% of control. Staurosporine exhibited a stimulation of cell proliferation (135% to 178%) in three of four meningioma cultures studied at a concentration of 10(-10) to 10(-9)M, although a tendency of growth inhibition was observed at a lower concentration. A time course of DNA synthesis in response to TPA, assessed by [3H] thymidine incorporation studies, revealed a time- and dose-dependent stimulation and/or inhibition which further depended on the serum concentration of the growth medium used. The overall results indicate that PKC-mediated signal pathways are closely involved in growth regulation of human meningioma cells. The results further suggest that the signalling processes consist of complex mechanisms which await to be elucidated.

Alkaloids↗

PubMed1994

High-level expression of the photorepair gene in Drosophila ovary and its evolutionary implications.

DNA photolyase catalyzes light-dependent repair of cis, syn-cyclobutane dipyrimidines (pyrimidine dimers); its apoenzyme is encoded by the photorepair (phr) gene. The phr cDNA was cloned from D. melanogaster; it has an open reading frame to encode a 61,483-Da protein. The phr cDNA hybridized to band 44C-D of Drosophila polytene chromosome, equivalent to the locus of the phr- gene. Drosophila photolyase is made of an apoenzyme with a molecular weight of 62 kDa. Drosophila photolyase is extraordinarily abundant in the embryo and adult ovary, whereas mRNA of the phr gene is abundant only in the ovary. The action spectrum of Drosophila photolyase for photoreactivation has a maximum at 440 nm. The phr gene of Drosophila has about 60% identical amino acid sites with that of goldfish but only 13-18% with those of microorganisms. Implications of the unique characteristics of the Drosophila phr gene are discussed overviewing the diversified characteristics of phr genes in various organisms that have presumably evolved from a common ancestral gene.

Amino Acid Sequence↗

PubMed1994

Vasospasm prevention with postoperative intrathecal thrombolytic therapy: a retrospective comparison of urokinase, tissue plasminogen activator, and cisternal drainage alone.

The authors report the results of a retrospective review, between January 1986 and December 1991, of the results of early surgery and intrathecal thrombolytic therapy in 111 patients with aneurysmal subarachnoid hemorrhage. Effects on clot lysis, angiographic and symptomatic vasospasm, cerebral infarction, and clinical outcome were compared in 60 patients treated with urokinase (UK) 60,000 IU/d for 7 days (UK group), 22 patients treated with 0.042 to 1 mg tissue plasminogen activator (tPA) every 6 to 8 hours for 5 days (tPA group), and 29 patients who did not receive treatment with either thrombolytic agent (no-treatment group). The no-treatment group consisted of all patients treated before July 1986 and of patients in whom thrombolytic therapy was attempted but failed to start or in whom the therapy was not used intentionally because of small subarachnoid clot. Treatment with UK was employed between July 1986 and March 1991, and tPA was employed during the remainder of the study for patients at a higher risk for vasospasm. The severity of angiographic vasospasm and the incidence of infarction in the UK and the tPA groups were less than those of the no-treatment group (P < 0.01), in spite of a larger amount of initial subarachnoid blood clot in both thrombolytic groups. This appears to be the result of the more rapid clearance of cisternal clot in the thrombolytic groups than the no-treatment group (P < 0.01). Only tPA therapy reduced the incidence of symptomatic vasospasm (P < 0.05). No serious complications were observed, although in the tPA group, asymptomatic intraventricular hemorrhage occurred in one patient, and transient confusion in another. Both received 4 mg tPA/d. Meningitis was suspected in 16 patients of the UK group. However, in this relatively small retrospective series, there were no differences among the three groups in overall outcome at 3 months. This study indicates that postoperative intrathecal thrombolytic therapies, especially with less than 4 mg/d of tPA, are effective in lysing subarachnoid clot and preventing vasospasm and infarction safely.

Adult↗

PubMed1994

Accumulation of inositol phosphates in low-passage human meningioma cells following treatment with epidermal growth factor.

In order to elucidate some of the signal transduction processes in human meningioma cells, the authors studied the effect of epidermal growth factor (EGF) and bromocriptine on inositol phospholipid hydrolysis, using low-passage human meningioma cells in culture. Epidermal growth factor is a well-studied mitogenic factor for meningioma cells, whereas bromocriptine is known to have an inhibitory effect on meningioma cell proliferation. The addition of EGF to meningioma cells caused stimulation of inositol phosphate accumulation in a dose-dependent manner at 60 minutes posttreatment, with the maximum effect (120% to 167% of control) achieved at a concentration of 10 ng/ml. Extraction of separate inositol phosphates accumulation in a dose-dependent manner at 60 minutes posttreatment, with the maximum effect (120% to 167% of control) achieved at a concentration of 10 ng/ml. Extraction of separate inositol phosphates revealed that inositol monophosphate (IP1) and inositol bisphosphate (IP2), but not inositol trisphosphate (IP3), accounted for the increase at 60 minutes. Kinetic analysis of EGF-stimulated inositol phospholipid hydrolysis showed that a sharp and transient increase in IP3 from 5 to 12 minutes post-EGF and a transient but more gradual increase in IP2 from 2 to 12 minutes post-EGF were followed by a gradual and steady increase in IP1, which was significantly greater than control after 5 minutes. On the other hand, long-term studies showed a down-regulation of inositol phosphate accumulation (a 64% decrease vs. control) after 7 days of treatment with EGF (10 ng/ml). Bromocriptine (5 microM) exhibited no significant effect on inositol phosphate accumulation at 60 minutes in four of five meningiomas studied. However, of two meningiomas studied with bromocriptine in combination with EGF, both showed a significant additive increase in inositol phosphate accumulation compared to those treated with EGF alone. The results suggest a close involvement of inositol phospholipid turnover in human meningioma cells in response to mitogenic stimulation by EGF.

Bromocriptine↗

PubMed1994

Secretion of interleukin-6 by human meningioma cells: possible autocrine inhibitory regulation of neoplastic cell growth.

Using cell culture techniques, the authors have previously shown that human meningioma cells secrete an autocrine growth stimulator related to platelet-derived growth factor. Here, they further demonstrate potential autocrine inhibitory regulation of meningioma cell growth by interleukin (IL)-6. Constitutive IL-6 production was detected in all meningiomas studied, in the form of protein as well as IL-6-specific messenger ribonucleic acid. The IL-6 immunoreactivity in conditioned medium from three different meningioma cultures eluted from a Sephadex G-100 column was evidenced by a single peak corresponding to a molecular weight of about 32 kD. Interleukin-6 secretion was remarkably stimulated by tumor necrosis factor-alpha, IL-1 beta, and IL-4, and was also influenced by a combination of epidermal growth factor and bromocriptine. Recombinant IL-6 exhibited a significant dose-dependent inhibitory effect on meningioma cell proliferation. The maximum effect was observed at concentrations of 10 to 100 pg/ml, with the decrease in thymidine incorporation ranging from 21% to 35% versus control. Addition of an anti-IL-6 antibody enhanced the growth-stimulating effect of meningioma-derived conditioned medium. The rate of IL-6 secretion tended to show an inverse correlation with meningioma growth rate. The results presented here and the previous results suggest that the regulation of meningioma cell proliferation is defined by a complex network of autocrine stimulation, autocrine inhibition, and influences from multiple exogenous factors.

Blotting, Northern↗

PubMed1993

A new photoreactivating enzyme that specifically repairs ultraviolet light-induced (6-4)photoproducts.

Cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts ((6-4)photoproducts) are the two major classes of cytotoxic, mutagenic and carcinogenic DNA photoproducts produced by ultraviolet light irradiation of cells. The phenomenon of photoreactivation, the reduction of the lethal and mutagenic effects of ultraviolet radiation by simultaneous or subsequent irradiation with near ultraviolet or visible light, has been identified in several organisms and in some cases the enzymes that catalyse this process have been characterized in sufficient detail. CPDs are the only known substrate for the photoreactivating enzymes so far analysed and enzymatic photoreactivation of (6-4)photoproducts has not yet been reported. We report here that an enzyme that catalyses the light-dependent repair of (6-4)photoproduct exists in Drosophila melanogaster. This is, to our knowledge, the first report of such photoreactivating activity specific for (6-4)photoproducts in any organism.

Animals↗

PubMed1993

Immunohistochemical expression of protein kinase C type III in human pituitary adenomas.

Immunohistochemical expression of the three major isozymes of protein kinase C--Types I, II, and III--was studied in 32 cases of human pituitary adenomas, and the results were compared in detail with their clinical data. Immunoreactivity for the Type I and Type II isozymes was negative in tumor cells of all pituitary adenomas. Moderate to strong cytoplasmic immunoreactivity for the Type III isozyme was constantly seen in acromegaly, Cushing's disease, and nonfunctioning adenomas, which indicated overexpression of the isozyme, since only slight cytoplasmic immunoreactivity was observed in the normal human anterior pituitary cells. Among 13 prolactinomas, 5 cases showed positive immunoreactivity for Type III in all tumor cells, whereas 8 cases showed negative immunoreactivity for the isozyme in all or more than 85% of tumor cells. The sizes of the tumors in this protein kinase C Type III negative group of prolactinomas tended to be smaller than those of the Type III positive prolactinomas. Also, the negative immunoreactivity for Type III was predominantly observed in those cases where prolactinomas were relatively well controlled by continuous oral dosage of dopamine agonists before operation. These results suggest that protein kinase C Type III is closely involved in human pituitary adenomas. The exceptional negativity for the isozyme in prolactinomas may be relevant to the suppression of tumor growth by dopamine agonists.

Acromegaly↗

PubMed1993

Dandy-Walker syndrome forming a giant occipital meningocele--case report.

A boy was born with Dandy-Walker syndrome associated with a giant occipital meningocele, cleft lip, and cleft palate. The meningocele was actually a component of the giant posterior fossa cyst which communicated with the fourth ventricle. A cyst-peritoneal shunt achieved a considerable decrease in the size of the meningocele, but decubital ulcers developed due to restricted head movement caused by the occipital lesion. Cranioplasty removed a wide area of the inferior occipital bone, and the boundary between the superior occipital and parietal bones was thinned to allow free bending of the bone flap. The meningocele was removed totally in the third operation, but infection of the wound and pneumonia developed, causing death. The coexistence of Dandy-Walker syndrome and occipital meningocele, together with midline facial anomalies, may suggest a later pathogenesis of Dandy-Walker syndrome than previously believed.

Cerebrospinal Fluid↗

PubMed1993

Inhibitory effect of trapidil on human meningioma cell proliferation via interruption of autocrine growth stimulation.

In a previous study, the authors demonstrated that meningioma cells secrete platelet-derived growth factor (PDGF)-like molecules that stimulate their own growth in an autocrine manner. Based on that finding, a study was undertaken to examine the effect of trapidil, a drug known to have an antagonistic action against PDGF, on cell proliferation of human meningiomas in culture. Trapidil showed a dose-dependent inhibition of meningioma cell proliferation in the absence of any exogenous mitogenic stimulation. The maximum effect was observed at a concentration of 100 micrograms/ml, with the decrease in cell growth ranging from 16% to 54% compared to control samples. Trapidil similarly inhibited the basal deoxyribonucleic acid (DNA) synthesis assessed by [3H]-thymidine incorporation in three of seven meningiomas. While the conditioned medium generated from meningioma cells remarkably stimulated the proliferation of meningioma cells (166% to 277% of control), this effect was strikingly inhibited by the addition of trapidil. Trapidil also inhibited conditioned medium-stimulated DNA synthesis, even when there was no effect on basal DNA synthesis. Furthermore, trapidil significantly inhibited the epidermal growth factor (EGF)-stimulated proliferation of meningioma cells. This inhibitory effect on EGF-stimulated cell proliferation was also observed in nontumorous fibroblasts, demonstrating that trapidil is not an antagonist specific to PDGF. The addition of trapidil (30 micrograms/ml) in combination with bromocriptine (1 microM) showed an additive inhibitory effect on the meningioma cell growth compared to trapidil or bromocriptine alone. The overall results suggest that trapidil exhibits an inhibitory effect on meningioma cell proliferation through blocking the mitogenic stimulation induced by autocrine or exogenous growth factors, and may be considered as a possible new approach to the medical treatment of meningiomas.

Cell Division↗

PubMed1992

Cerebral metastasis of malignant cardiac myxoma.

A rare case of bona fide cerebral metastasis of malignant cardiac myxoma is presented. The parenchymal brain tumor of a 32-year-old woman with a history of surgical operations on cardiac myxoma and jejunal leiomyosarcoma was surgically extirpated. The initial pathological diagnosis was metastatic sarcoma. Ten months later, an occlusion of bilateral carotid arteries occurred that was due to tumor emboli. The postmortem examination revealed an unusually rapid recurrence of the cardiac tumor containing sarcomatous components that were histologically identical to the tumors of the brain and the jejunum and the emboli of the cerebral vessels. Hence it was deduced that they all originated in the primary malignant cardiac myxoma.

Adult↗

PubMed1992

Identification of cellular factors that recognize UV-damaged DNA in Drosophila melanogaster.

Using a gel electrophoresis DNA band-shift assay, we have identified 2 DNA-binding protein complexes in wild-type Drosophila embryonic cells which have high affinity for UV-irradiated, double-stranded DNA. Screening of Drosophila mutants deficient in DNA repair led to the identification of 5 mutants which lacked either one of the 2 protein complexes. Four excision repair-deficient mutants (mus-201, phr, mus-308 and mus-205) lacked one protein complex (Factor 2). The other protein complex (Factor 1) was not detectable in the post-replication repair-deficient mutant mus-104. These findings might suggest the possible involvement of these gene products in lesion recognition and repair of UV-induced photoproducts in DNA.

Animals↗

PubMed1991

Autocrine control of human meningioma proliferation: secretion of platelet-derived growth-factor-like molecules.

We have used cell-culture techniques to investigate growth-factor production by human meningioma cells. Meningioma tissue was dispersed with collagenase and the cells grown to high density in tissue-culture flasks. The cultures were used to generate conditioned medium (MEN-CM), which was used to cultivate IMR32 cells (a human neuroblastoma line) and freshly dispersed primary meningioma cells. MEN-CM profoundly stimulated the in vitro growth of both IMR32 and meningioma cells. In addition, H3-thymidine uptake by cultured meningioma cells was increased in a dose-dependent manner by varying concentrations of MEN-CM. A neutralizing anti-body against platelet-derived growth factor (PDGF) completely abolished the stimulatory effects of MEN-CM, whereas an antibody against TGF-alpha was without effect. The mitogenic activity of MEN-CM, as assayed by promotion of H3-thymidine uptake by cultured meningioma cells, eluted from a Sephadex G-100 column in 3 peaks corresponding to molecular weights of greater than or equal to 150, 56 and 28 kDa. Our results show that proliferation of human meningiomas may be under autocrine control via secretion of PDGF-like molecules.

Cell Division↗