Biomedical subjects

H Ohyama

Publications and source records attributed to H Ohyama.

At least 55 records · Page 3Linked to original sources

PubMed1999

In vitro induction of activation-induced cell death in lymphocytes from chronic periodontal lesions by exogenous Fas ligand.

Periodontitis is a chronic inflammatory disease which gradually destroys the supporting tissues of the teeth, leading to tooth loss in adults. The lesions are characterized by a persistence of inflammatory cells in gingival and periodontal connective tissues. To understand what mechanisms are involved in the establishment of chronic lesions, we hypothesized that infiltrating lymphocytes might be resistant to apoptosis. However, both Bcl-2 and Bcl-xL were weakly detected in lymphocytes from the lesions, compared with those from peripheral blood, suggesting that these cells are susceptible to apoptosis. Nevertheless, very few apoptotic cells were observed in tissue sections from the lesions. Lymphocytes from the lesions expressed mRNA encoding Fas, whereas Fas-ligand mRNA was very weakly expressed in lymphocytes from the lesions and in periodontal tissues. Since the results indicated that lymphocytes in the lesions might be susceptible to Fas-mediated apoptosis but lack the death signal, we next investigated if these lymphocytes actually undergo apoptosis by the addition of anti-Fas antibodies in vitro. Fas-positive lymphocytes from the lesions underwent apoptosis by these antibodies, but Fas-negative lymphocytes and Fas-positive peripheral lymphocytes did not undergo apoptosis by these antibodies. These results indicate that lymphocytes in the lesions are susceptible to activation-induced cell death and are induced to die by apoptosis after the addition of exogenous Fas ligand.

Adult↗

PubMed1999

Adaptive response in embryogenesis: II. Retardation of postnatal development of prenatally irradiated mice.

We previously reported that a priming dose of 0.3 Gy on gestation day 11 significantly increased the rate of living fetuses and reduced the incidence of congenital malformations caused by exposure to 5 Gy X rays on gestation day 12 in ICR mice. In the present study, postnatal development of the live offspring was investigated using a set of developmental and behavioral parameters. The offspring of the mice irradiated with 0.3 Gy generally showed a delay in the appearance of most of the physiological markers, impaired acquisition of neonatal reflexes, and alteration of adult behavior. However, an increase in body weight in the females was observed 4 weeks postnatally. In the offspring primed with 0.3 Gy followed by a challenging dose of 5 Gy prenatally, a high postnatal mortality was found, and all the survivors had various radiation-induced detrimental effects. The results indicated that the priming dose was advantageous to survival itself, but was disadvantageous to the health of survivor. The results also suggested that studying the whole animal can show the extent of the effects of radiation, i.e. quality of life, in a way that cellular or molecular studies cannot.

Abnormalities, Radiation-Induced↗

PubMed1999

Radiation-induced apoptosis and limb teratogenesis in embryonic mice.

In utero irradiation of the fetus during the period of organogenesis induces a dramatic increase in malformation. However, the mechanisms underlying the teratogenesis remain to be elucidated. In the present study, the correlation between radiation-induced apoptosis and limb malformation was examined in mice. The mice were exposed to X rays in utero on day 11 of gestation during the period of organogenesis of limb buds. A marked increase in the number of apoptotic cells in the predigital regions in the forelimb buds was detected 4 h after irradiation. The preinterdigital regions of the forelimb buds did not show such an increase at the same time. Aphlangy and ectrodactyly were the main types of anomalies observed on day 19 in the limbs of the fetuses irradiated with 5 Gy. The increases in prenatal death and teratogenesis in limb digits in living fetuses were dependent on dose. The possible mechanisms involved are discussed.

Abnormalities, Radiation-Induced↗

PubMed1998

Neutralization of aspartate residues in the murine inwardly rectifying K+ channel IRK1 affects the substate behaviour in Mg2+ block.

1. To investigate the molecular basis of the sublevels induced in the outward current during block by intracellular Mg2+, single-channel currents through inwardly rectifying K+ (IRK1) channels were studied. 2. cDNA encoding a functional murine IRK1 channel was transfected into COS-1 cells (a Green Monkey kidney cell line) using the liposome method, and voltage clamp experiments were done after 48-72 h. 3. Intracellular Mg2+ at micromolar concentrations induced sublevels in the outward current at one-third and two-thirds of the unitary amplitude seen in wild-type channels. Replacing Asp 172 with Asn (D172N) and Gln (D172Q) abolished these sublevels, i.e. the channel showed only the fully open and fully blocked states. 4. Both mutations reduced the Mg2+ sensitivity of the channel at 2 microM Mg2+. However, the Mg2+ sensitivity did not differ significantly at higher concentrations (10 microM) and voltages (+70 mV). 5. Channels expressed from D172E showed the sublevels, indicating that a negative charge is indispensable to the substate behaviour. 6. Channels from tandem tetramers of IRK1 with one and two D172N mutant subunits mainly showed sublevels with two-thirds amplitude, while those from tetramers with three D172N mutant subunits showed no sublevels. 7. These findings suggest that differences in Mg2+ binding patterns lead to different conductive states in a single-barrelled channel.

Animals↗

PubMed1998

Radio-sensitive murine thymoma cell line 3SB: characterization of its apoptosis-resistant variants induced by repeated X-irradiation.

3SB, a mouse thymoma cell line, is one of the most radio-sensitive cells (D0 = 0.3 Gy), and its rapid apoptosis (4 h after 5 Gy irradiation, 90% apoptosis) seems to play a decisive role in enhancing the radiosensitivity. To understand the molecular mechanisms underlying extremely high radiosensitivity and rapid apoptosis, we attempted to isolate X-ray-resistant (XR) variants from 3SBH5, a stable subclone of 3SB, by repeating exposure of the cells to 2-5 Gy X-rays. Four independent stable XR variants, R111, R223, R316 and R429, were isolated by the repeated irradiation protocols. All XR cells possessed about 3 times higher D10 values than that of their parental 3SBH5. They were also resistant to apoptosis; only 10% cells underwent apoptosis 4 h after 5 Gy irradiation. The p53 protein was induced in all the cell lines after 5 Gy X-irradiation. These variants showed a cross resistance to a chemical reagent daunorubicin (DNR) that is known to be involved in the ceramide-mediated apoptosis. DNR, as well as C2-ceramide (5 muM) induced apoptosis in parental 3SBH5 cell, but not in two XR variants, R233 and R316 cells. Present result suggests that the induction of X-ray resistance by repeated X-irradiation might be achieved, at least partly, by the enhanced resistance to the ceramide-mediated apoptosis.

Animals↗

PubMed1998

IL-4-dependent regulation of TGF-alpha and TGF-beta1 expression in human eosinophils.

TGFs play important roles in wound healing and carcinogenesis. We have previously demonstrated that eosinophils infiltrating into different pathologic processes elaborate TGF-alpha and TGF-beta1. Eosinophils infiltrating hamster cutaneous wounds were found to express TGFs sequentially. In this study, we examined the biologic mediators that may regulate the expression of TGF-alpha and -beta1 by eosinophils. Eosinophils were isolated from the peripheral blood of healthy donors and cultured in the absence or presence of IL-3, IL-4, and IL-5. Cells were analyzed by in situ hybridization and immunohistochemistry. Supernatants from these cultures were assayed for secreted TGF-alpha and TGF-beta1 using TGF-specific ELISAs. IL-3, IL-4, and IL-5 independently up-regulated TGF-beta1 mRNA and product expression by eosinophils in all donors. Interestingly, TGF-alpha production by eosinophils was up-regulated by IL-3 and IL-5 but was down-regulated by IL-4. Consistent with the ability of IL-4 to regulate eosinophil responses, IL-4 signaling molecules are present in human eosinophils. The observation that IL-4 can differentially regulate the expression of TGF-alpha and TGF-beta1 suggests that IL-4 may serve as a physiologic molecular switch of TGF expression by the infiltrating eosinophils in wound healing and carcinogenesis.

Adult↗

PubMed1998

Optimized conditions for gene transfection into the human eosinophilic cell line EoL-1 by electroporation.

Eosinophils are emerging as an increasingly important cell in the immunoregulatory network of normal and pathological processes. No studies has yet described optimized experimental strategies to transfect DNA into human eosinophils. Using a frequently employed in vitro model of human eosinophil, the EoL-1 cells, we now described the optimal transfection of DNA into these cells by electroporation. Our results indicate that electroporation can efficiently and reproducibly transfect DNA into EoL-1 cells. Optimal electroporation conditions consist of the use of 1 X RPMI medium 1640 with 10% FBS, voltage setting at 275 V, 1150 microF capacitance, 40 mg of DNA and 4.0 X 10(7) cells/ml per electroporation in a total volume of 0.5 ml in 0.4 cm gap cuvettes. These conditions may be a useful protocol for transfecting eosinophil cell lines.

DNA↗

PubMed1998

Cloning, mapping, expression, function, and mutation analyses of the human ortholog of the hamster putative tumor suppressor gene Doc-1.

doc-1 is a putative tumor suppressor gene isolated and identified from the hamster oral cancer model. Here, we report the molecular cloning and the functional characterization of the human ortholog of the hamster doc-1 gene. Human doc-1 cDNA is 1.6 kilobase pairs in length and encodes for a 115-amino acid polypeptide (12.4 kDa, pI 9. 53). Sequence analysis showed 98% identity between human and hamster doc-1 protein sequences. DOC-1 is expressed in all normal human tissues examined. In oral keratinocytes, expression of DOC-1 is restricted to normal oral keratinocytes. By immunostaining of normal human mucosa, DOC-1 is detected in both the cytoplasm and nuclei of basal oral keratinocytes; while in suprabasilar cells, it is primarily found in the nuclei. Human oral cancers in vivo did not exhibit immunostaining for DOC-1. Like murine DOC-1, human DOC-1 associates with DNA polymerase alpha/primase and mediates the phosphorylation of the large p180 catalytic subunit, suggesting it may be a potential regulator of DNA replication in the S phase of the cell cycle. Using a human doc-1 cosmid as a probe, human doc-1 is mapped to chromosome 12q24. We identified four exons in the entire human doc-1 gene and determined the intron-exon boundaries. By polymerase chain reaction and direct sequencing, we examined premalignant oral lesion and oral cancer cell lines and found no intragenic mutations.

Amino Acid Sequence↗

PubMed1998

Cell death induced by high-linear-energy transfer carbon beams in human glioblastoma cell lines.

The cytotoxic effect of high-linear-energy transfer (LET) carbon beams on two human glioblastoma cell lines (A172 and TK1) was analyzed, especially concerning cell death, including apoptosis. Gamma-ray radiation was used for comparison. The results of standard colony formation assay showed that the survival fraction of each cell line decreased in an LET-dependent manner. The results of other direct cytotoxic assays, dye exclusion test, and lactate dehydrogenase (LDH) release assay, also displayed a similar relationship between the cytotoxic effect of carbon beams and LET. The maximum values of the cell death index (CDI) were 50.2% in A172 and 37.5% in TK1, both obtained on day 7 after exposure to carbon beams of 80 keV/microm. Apoptosis was observed only on days 4 and 7 after carbon beam irradiation, with maximum values of 7% in A172 and 4.5% in TK1, and the induction of apoptosis after high-LET radiation could be p53-independent. This indicated that a combination of multiple assays to detect cell death was important in evaluating the radiosensitivity of tumor cells, because this approach could more precisely reflect the clinical effectiveness of radiotherapy.

Apoptosis↗

PubMed1998

Treatment of acute superior sagittal sinus thrombosis by t-PA infusion via venography--direct thrombolytic therapy in the acute phase.

BACKGROUND: Dural sinus thrombosis is a relatively rare syndrome, often with a very poor prognosis. Systemic anticoagulant therapy has produced poor results; therefore rapid recanalization of the affected vessels is essential. The recent advancements in angiographic technique and catheter technology enable us to perform direct selective venography. CASE REPORT: We observed a case of acute superior sagittal sinus thrombosis in a pregnant woman. The patient's consciousness level and motor function gradually deteriorated. Direct thrombolysis was performed via venography. RESULTS: The patient was treated successfully by thrombolysis with infusion of t-PA via selective venography within 2 days of rapid clinical deterioration and sustained a dramatic improvement of her neurological deficits. CONCLUSIONS: Direct thrombolysis via selective venography is considered a safe and useful treatment for dural sinus thrombosis in the acute phase.

Acute Disease↗

PubMed1998

T cell responses to 53-kDa outer membrane protein of Porphyromonas gingivalis in humans with early-onset periodontitis.

Patients with early-onset periodontitis (EOP) are susceptible to infection with periodontopathic bacteria, such as Porphyromonas gingivalis. Ag53, 53-kDa outer membrane protein of P. gingivalis, evokes strong humoral immune responses in EOP patients. In a first step to clarify how host immune cells recognize Ag53, we established Ag53-specific short-term T cell lines from 22 subjects including 6 EOP patients and 16 healthy donors, using overlapping peptides based on Ag53 amino acid sequences. All T cell lines from active EOP patients recognized a common region (p141-181, especially p141-161) on Ag53, while those from healthy donors showed heterogeneous specificity. p141-181 was not recognized by T cell lines established from EOP patients following therapy. A monoclonal antibody to HLA-DRB 1 inhibited Ag53-induced proliferation of most of the T cell lines. Our observations suggest that, although antigen-presenting molecules are common in EOP patients and in healthy individuals, p141-161 includes a major T cell epitope(s) on Ag53 for active EOP patients but not for healthy individuals or inactive EOP patients.

Adult↗

PubMed1998

IL-1 beta and IL-6 in mouse parotid acinar cells: characterization of synthesis, storage, and release.

Synthesis, storage, and secretion of the proinflammatory cytokine interleukin-1 beta (IL-1 beta) and the anti-inflammatory cytokine IL-6 have not been established in normal exocrine gland secretory cells. Parotid glands and isolated acinar cells prepared from BALB/c mice were homogenized for RNA isolation and reverse transcription-polymerase chain reaction (RT-PCR). IL-1 beta and IL-6 enzyme-linked immunosorbent assays (ELISAs) were done on supernatants prepared from mouse parotid acinar cell (MPAC) preparations unstimulated or stimulated between 0 and 10 min with 10(-5) M norepinephrine at 37 degrees C. MPACs were fixed in paraformaldehyde, frozen sectioned for light and electron microscopy, and labeled with antibodies to IL-1 beta and IL-6. Mouse specific riboprobes to IL-1 and IL-6 were used for in situ hybridization. RT-PCR yielded the expected IL-1 (336-bp) and IL-6 (614-bp) mRNA products. By ELISA, stimulated MPACs showed a significant increase in IL-1 beta (P < 0.03) and IL-6 (P < 0.01) release into supernatants by 10 min that paralleled the time course of amylase release. In situ hybridization showed the presence of transcripts for IL-1 and IL-6 in glandular epithelial cells. Gold-labeled IL-1 beta and IL-6 were significantly higher (P < 0.01) in granules than in the nucleus and cytoplasm. This study shows that MPACs synthesize IL-1 beta and IL-6 and release these cytokines from their granules after alpha- and beta-adrenergic stimulation.

Amylases↗

PubMed1998

Isolation and characterization of apoptosis-resistant mutants from a radiosensitive mouse lymphoma cell line.

To analyze specific genes related to radiation-induced apoptosis, 12 apoptosis-resistant clones were isolated from cells of the radiosensitive mouse thymic lymphoma 3SB line after treatment with ethyl methanesulfonate. Five of 12 clonal cell lines were recloned and were examined for their susceptibility to X-ray-induced apoptosis. A cell survival assay showed that all five secondary cell lines were two to three times more resistant to X rays than 3SB cells. When 3SB cells were exposed to 5 Gy of X rays, the fraction of cells stained with erythrosin B increased quickly within 8 h of incubation after irradiation. However, no apoptosis occurred in these secondary mutant cells. In particular, the percentage of cells undergoing apoptosis in one clone, 1B1C4, was low even after incubation for 48 h. In contrast to X rays, after exposure to 20 J/m2 UV radiation, the proportion of apoptotic cells in these mutant cells increased and reached about 60 to 100% at 24 h, indicating a difference in the ability of X rays and UV radiation to induce apoptosis. A similar radioresistance was observed using agarose gel electrophoresis of DNA from cells of all X-irradiated secondary lines. Western blot analysis and a sequence-specific DNA-binding assay demonstrated that 1B1C4 cells had a functional defect in p53 protein, but the other four cell lines displayed wild-type p53 after X irradiation. Our results suggest the existence of separate radiation-specific p53-dependent and independent apoptosis in thymic lymphoma cells. Thus these apoptosis-resistant cell lines provide a useful tool to identify the genes involved in the signaling pathways leading to X-ray-specific apoptosis.

Animals↗

PubMed1998

Adaptive response in embryogenesis: I. Dose and timing of radiation for reduction of prenatal death and congenital malformation during the late period of organogenesis.

An adaptive response was demonstrated during embryogenesis in mice. Whole-body irradiation at a dose of 0-50 cGy was given to condition pregnant ICR mice on day 9 to day 11 of gestation. Then their whole bodies were exposed to a challenging dose of 5 Gy on the next day. The numbers of living fetuses, prenatal deaths and living fetuses with external gross malformations were determined on day 19. A conditioning dose of 30 cGy on day 11 significantly increased the rate of living fetuses and reduced the incidence of congenital malformations induced by a 5-Gy dose on day 12. This indicates the existence of a critical dose and timing for administering a conditioning dose for radioadaptation during the late period of organogenesis in mice. The possible mechanisms involved are discussed.

Abnormalities, Radiation-Induced↗

PubMed1997

Purification and properties of DNase gamma from apoptotic rat thymocytes.

We previously identified three distinct DNA endonucleases, DNases alpha, beta and gamma, present in rat thymocyte nuclei. On the basis of their enzymic and biochemical properties, gamma-type DNase was regarded as a candidate for the apoptotic endonuclease. Here we purified DNase gamma to apparent homogeneity from apoptotic rat thymocyte nuclei induced by X-irradiation and characterized its properties in detail. The purified DNase gamma exhibited one predominant protein band on SDS/PAGE and an endonuclease activity in a zymography with an estimated molecular mass of 33 kDa. The molecular mass of the native form determined by G2000SW gel-filtration HPLC was 30 kDa. Amino acid analysis showed that the amino acid composition of DNase gamma was similar to that of rat DNase I (molecular mass 32 kDa) but different with regard to alanine and lysine residues. The N-terminal amino acid sequence of DNase gamma was revealed to be not identical with that of rat DNase I. In accordance with previous studies, homogeneously purified DNase gamma requires both Ca2+ and Mg2+ for activity. This requirement could be partially supplied by Mn2+. Of the bivalent metal ions tested, Co2+, Ni2+, Cu2+ and Zn2+ inhibited DNase gamma activity. These bivalent cations also suppressed apoptotic DNA fragmentation in rat thymocytes irradiated by X-rays. The same order of inhibitory ability was observed for these bivalent metal ions in vivo (in intact cells) and in vitro, suggesting that the suppression of apoptotic DNA fragmentation at the cellular level is due to the inhibition of DNase gamma. DNase gamma activity was found to exist at high levels in spleen, lymph node, thymus, liver and kidney, but little was present in brain, heart or pancreas. On the basis of these findings, together with previous data, we conclude that DNase gamma is a novel DNase I-like endonuclease responsible for internucleosomal cleavage of chromatin during thymic apoptosis.

Animals↗

PubMed1997

Retinoblastoma protein expressed in human non-Hodgkin's lymphoma cells generates resistance against radiation-induced apoptosis.

Inactivation of the retinoblastoma susceptibility (Rb) gene has been observed in various cancers. Nevertheless, in several cancer cases, including non-Hodgkin's lymphoma, previous investigations showed that the Rb gene product (pRb) was abundantly expressed with varying degree. Here we report the THS-SP1.1 cell line isolated from non-Hodgkin's lymphoma. The THS-SP1.1 cells abundantly expressed pRb and showed resistance against radiation-induced apoptosis. Culture with the antisense phosphorothioate oligonucleotide complementary to the Rb gene augmented the apoptosis of THS-SP1.1 cells after radiation, whereas the control oligonucleotides did not. These data showed that pRb abundantly expressed in the lymphoma cells inhibited radiation-induced apoptosis.

Apoptosis↗

PubMed1997

Prophylactic efficacy of traditional herbal medicines against recurrent herpes simplex virus type 1 infection from latently infected ganglia in mice.

Traditional herbal medicines with anti-herpes simplex virus type 1 (HSV-1) activity in vivo were examined for their prophylactic effects on recurrent HSV-1 infection in mice. Mice were intradermally infected with HSV-1 in the pinna and recurrent HSV-1 disease was induced by ultraviolet irradiation. Herbal extracts arrested the progression of recurrent HSV-1 disease, reduced the incidence of severe erythema and/or vesicles in the pinna, and/or shortened the period of severe recurrent lesions compared with water-administered mice (P < 0.01 or 0.05). Similarly, the prophylactic treatment of herbal extracts limited the development of recurrent skin lesions induced by stripping with cellophane tape physically. The prophylactic efficacy on recurrence was confirmed by the absence of HSV DNA in the skin lesions. HSV-1 genome was revealed to exist in the trigeminal ganglia but not in the pinna of latently infected mice before stimuli by a nested-polymerase chain reaction assay. After stimuli, HSV-1 genome was detected in both pinna and trigeminal ganglia of latently infected mice administered with water. However, prophylactic treatment decreased the rate of detection of HSV-1 genome in the stimulated pinna. Thus, the herbal extracts exhibited prophylactic efficacy against recurrent HSV-1 disease in mice and modulated the recurrent HSV-1 infection.

Animals↗

PubMed1997

The restrictive proteolysis of alpha-fodrin to a 120 kDa fragment is not catalyzed by calpains during thymic apoptosis.

The alpha-subunit (240 kDa) of fodrin was found to be digested selectively to a 120 kDa fragment during apoptosis of rat thymocytes in vivo and in vitro. This fragment was detected by an antibody (Ab) against full length alpha-fodrin, but not by the anti-N-terminal sequence (GMMPR) of the mu-calpain-generated 150 kDa fragment Ab or the anti-PEST sequence of alpha-fodrin Ab. On the other hand, basal levels of the 150 kDa fragment were constantly recognized by these three antibodies during apoptosis. The production of the 120 kDa fragment during apoptosis was not affected by the addition of calpain inhibitors such as Ac-LLLnal and E-64d, despite inhibition of the generation of the 150 kDa fragment. When x-irradiated thymocytes were incubated in the presence of N-tosyl-L-phenylalanyl chloromethyl ketone (TPCK), both production of the 120 kDa fragment and apoptosis were suppressed. Purified mu- and m-calpain did not catalyze the formation of the 120 kDa fragment from purified alpha-fodrin in vitro. These results suggest that a protease different from calpains is involved in the major process of alpha-fodrin proteolysis to a 120 kDa fragment during thymic apoptosis.

Journal Article↗