Biomedical subjects

Y Abiko

Publications and source records attributed to Y Abiko.

At least 109 records · Page 6Linked to original sources

PubMed1997

Cardioprotective effect of K-7259, a novel dilazep derivative, against ischemia-reperfusion damage in isolated, working rat hearts.

Global ischemia (15 min) followed by reperfusion (10, 20 or 30 min) was performed in isolated, working rat hearts. Ischemia depressed mechanical function, which was not restored by reperfusion of 20 min. Preischemic administration of K-7259 (N,N'-bis[4-(3,4,5-trimethoxyphenyl)butyl]homopiperazine dihydrochloride) (1, 5 or 10 microM) decreased the function before ischemia, but it attenuated the ischemia-induced dysfunction during reperfusion (20 min). Postischemic administration of K-7259 (10 microM) or dilazep (20 microM) also attenuated the ischemia-induced dysfunction during reperfusion (30 min). Ischemia-reperfusion (10 min) increased the tissue malondialdehyde level, and postischemic administration of K-7259 (10 microM) or dilazep (20 microM) attenuated the malondialdehyde accumulation. K-7259 has a cardioprotective effect when given either before or after ischemia.

Animals↗

PubMed1997

Beneficial effects of dilazep on the palmitoyl-L-carnitine-induced derangements in isolated, perfused rat heart: comparison with tetrodotoxin.

The present study was carried out to determine the effect of dilazep, having an inhibitory effect on the Na+ channel, on the mechanical dysfunction and metabolic derangements induced by palmitoyl-L-carnitine in isolated rat heart and to compare the effect of dilazep with that of tetrodotoxin, a specific inhibitor of the Na+ channel. Rat hearts were perfused aerobically at a constant flow according to Langendorff's technique and paced electrically. Palmitoyl-L-carnitine (5 microM) decreased the left ventricular developed pressure and increased the left ventricular end diastolic pressure (i.e., it produced mechanical dysfunction), decreased the tissue level of adenosine triphosphate and increased the tissue level of adenosine monophosphate (i.e., it produced metabolic derangements). These mechanical and metabolic alterations induced by palmitoyl-L-carnitine were attenuated by either dilazep (1 microM) or tetrodotoxin (3 microM). On the other hand, neither dilazep nor tetrodotoxin modified the mechanical function and energy metabolism of the normal (palmitoyl-L-carnitine-untreated) heart. These results suggest that inhibition of the Na+ channel with dilazep or tetrodotoxin is responsible, at least in part, for attenuating the palmitoyl-L-carnitine-induced mechanical dysfunction and metabolic derangements in the heart.

Adenosine Diphosphate↗

PubMed1997

A new approach to the development of anti-ischemic drugs. Substances that counteract the deleterious effect of lysophosphatidylcholine on the heart.

Lysophosphatidylcholine (LPC) is an amphiphilic metabolite that can be produced from membrane-phospholipids by activation of phospholipase A2 (PLA2), and it accumulates in the heart during ischemia and reperfusion. It is known that LPC is an arrhythmogenic substance. Recent studies have revealed that LPC produces mechanical and metabolic derangements in perfused working rat hearts, and Ca(2+)-overload in isolated cardiac myocytes. Thus, LPC possesses an ischemia-like effect on the heart. LPC accumulated in the myocardium activates phospholipase A2, establishing a vicious circle; i.e. LPC itself has an ability to produce another LPC. Therefore, a drug that has an anti-LPC effect would protect or improve ischemia/reperfusion damage. This article will review the effect of LPC in relation to ischemia, and consider a possibility of developing new anti-ischemic drugs on the basis of the anti-LPC action.

Adrenergic beta-Antagonists↗

PubMed1997

Immunolocalization of proliferating cell nuclear antigen in the peri-implant epithelium.

The aim of the present study was to investigate the proliferating activity of peri-implant epithelium immunohistochemically using proliferating cell nuclear antigen (PCNA). Eight ITI (Internationale Team für Implantologie) implants were placed into simulated sockets in the mandibles of two beagle dogs two months following tooth extraction. As a control, junctional epithelium of the molar teeth in the same animals were used. The nature of staining and the distribution of PCNA immunoreactivity were determined by scoring a minimum of 100 cells on two sections from each of the implants. In the junctional epithelium, the immunoreactivity to PCNA was detected mainly in the basal cells, in some of the prickle cells, and in a few cells attached to the enamel. In peri-implant epithelium, only some of the basal cells were positive for PCNA. The PCNA score of the peri-implant epithelium was significantly lower than that of junctional epithelium. These results suggest that the peri-implant epithelium maintains a lower capacity to act as a proliferative defence mechanism than does the junctional epithelium.

Animals↗

PubMed1997

Molecular cloning and characterization of the gene encoding 53 kD outer membrane protein of Porphyromonas gingivalis.

The pga53 gene which encoded the antigenic 53 kD outer membrane protein (Ag53) was isolated from a genomic DNA library of Porphyromonas gingivalis FDC381 by using an Ag53-immunized rabbit serum. Determination of its complete nucleotide sequence revealed that the precursor of Ag53 had a 50 amino-acid putative signal sequence and the mature protein of 448 amino acids. The deduced amino acid sequence after a 50 amino-acid putative signal sequence was in complete agreement with the first 20 N-terminal amino acids of purified Ag53. Analysis of the deduced amino acid sequence revealed the presence of a highly hydrophilic proline-rich region at the C-terminal of Ag53. The deduced amino acid sequence showed 29.9% homology with that of a 72 kD cell-surface protein in P. gingivalis. Southern hybridization revealed that pga53 was specific to several P. gingivalis strains and that P. gingivalis strains which did not possess Ag53 had genes homologous to pga53.

Amino Acid Sequence↗

PubMed1996

Effects of in vitro cellular aging on alkaline phosphatase, cathepsin activities and collagen secretion of human periodontal ligament derived cells.

It is believed that the degree of periodontal tissue breakdown and tooth loss increase with age. In periodontal tissues which are gingiva, periodontal ligament (PL), alveolar bone and tooth cementum, the PL which is soft connective tissue, lies between the tooth cementum and alveolar bone, having the primary function of tooth support, and maintaining the homeostasis of supporting tissues, as well as providing the healing process. We therefore investigated the effects of in vitro cellular aging on alkaline phosphatase (ALP), cathepsin activities and collagen secretion from human PL cells obtained from 18-23 year-old patients' teeth. ALP, cathepsin activities and collagen secretion may play important roles in the remodeling and maintaining of periodontal tissues. To investigate the life span of PL cells, the cells were sequentially subcultivated. The maximum population doubling level of the PL cells in the present experiment was 22-25 passages. Investigating some important biological activities of the PL cells at different passage levels (6-7, 30% of life span to 17-20, 75% of life span), ALP activity and collagen secretion were found to have significantly decreased while cathepsin B and L activities significantly increased with cellular aging. Since these biological activities in human PL cells tend to be more catabolic with increase in cellular aging, the increase in periodontal breakdown with age may be partly related to the catabolic changes of the PL cells themselves.

Adolescent↗

PubMed1996

In vitro senescence enhances IL-6 production in human gingival fibroblasts induced by lipopolysaccharide from Campylobacter rectus.

The production of interleukin-6 (IL-6) in human gingival fibroblasts (Gin cells) is increased by lipopolysaccharide (LPS) from Campylobacter rectus (C. rectus), which is associated with adult periodontitis; however, the age-related changes in the susceptibility of Gin cells to C. rectus LPS remain unclear. We examined the influence of in vitro senescence on C. rectus LPS-stimulated IL-6 production in Gin cells. LPS was prepared from C. rectus ATCC 33238 using hot phenol-water. The Gin cells were established from healthy gingival tissue removed from three patients, aged 10-12 years. The cells were cultured until confluence then stimulated with LPS (0.01, 0.1, 1.0 and 10.0 micrograms/ml). Levels of IL-6 released in the medium were measured after incubation for 3, 6, 9, 12, and 24 h. In both young (5-6 population doublings) and senescent (17-20 population doublings) cells, LPS stimulated IL-6 production in a dose- and time-dependent manner. In response to 0.01-10.0 micrograms/ml of LPS, IL-6 production in the senescent cells was higher than that in the young cells. Using cells from each of the three donors, we found that this phenomenon of higher LPS-stimulated IL-6 production in senescent cells was reproducible. The greater capacity of the senescent cells to synthesize IL-6 in response to LPS was a higher production of mRNA for IL-6. This increase of IL-6 production induced by C. rectus LPS in senescent Gin cells could help to explain the increased susceptibility to periodontal diseases shown by aged individuals.

Adult↗

PubMed1996

Polymerase chain reaction and an outer membrane protein gene probe for the detection of Porphyromonas gingivalis.

A sensitivity assay for Porphyromonas gingivalis based upon the polymerase chain reaction (PCR) was developed. A 426-bp sequence, including a DraI-HincII DNA fragment (278 bp) encoding the 40-kDa outer membrane protein of the P. gingivalis gene was amplified. PCR products were obtained from chromosomal DNAs of the P. gingivalis strains tested but not from those of other oral microorganisms. The lower limit of template DNA detection was 10 pg with 30 cycles and 100 fg with 40 cycles of PCR by agarose gel electrophoresis. The PCR products were hybridized with DraI-HincII DNA fragment internal to the PCR primers regions used. The lower limit of hybridization detection was 10 pg and 10 fg of template DNA with 30 and 40 cycles of PCR, respectively. These results demonstrated the simplicity, rapidity and specificity of the procedure, as well as the use of the DraI-HincII DNA fragment in the identification of P. gingivalis.

Bacterial Outer Membrane Proteins↗

PubMed1996

Stimulation of interleukin-1beta-converting enzyme activity during growth inhibition by CPT-11 in the human myeloid leukemia cell line K562.

Camptothecin (CPT) was first extracted from Camptotheca acuminata and has a strong antitumor effect. Its water-soluble derivative, CPT-11, has higher therapeutic efficacy and less toxicity than CPT. Recently, CPT-treated cells have been shown to undergo apoptosis. However, the mechanism of induction of apoptosis by CPT has not been characterized in detail in any type of cells. On the other hand, interleukin-1beta-converting enzyme (ICE) is a mammalian homologue of CED3, a protein required for apoptosis in the nematode Caenorhabditis elegans. To determine how CPT-11 brings about cell death by apoptosis, we investigated the effects of CPT-11 on the expression of ICE activity in K562 cells, which represent human myeloid leukemia cells. The proliferation of K562 cells was shown to be inhibited by the presence of CPT-11 in the culture medium. We also found that the levels of mRNA for ICE in the cells were increased in the presence of CPT-11. Furthermore, we demonstrated that when CPT-11 was added to the culture medium, apoptosis of K562 cells was clearly detected in situ. These features suggested that CPT-11 enhances the apoptotic cell death in K562 cells and that a part of induction of apoptosis by CPT-11 may be correlated with the stimulation of the ICE activity.

Apoptosis↗

PubMed1996

Detection of Actinomyces species using nonradioactive riboprobes coupled with polymerase chain reaction.

We have been focusing our attention on the detection and identification of oral bacteria which are frequently associated with periodontal disease. In previous studies, Actinomyces species-specific riboprobes were generated and used to identify this microorganism. However, problems lie in the low sensitivity of this method. We have developed a novel system for the detection of Actinomyces species using nonradioactive riboprobes coupled with polymerase chain reaction (PCR) in this study. This system employs two procedures; initially, DNA fragments specific for the target microorganism are amplified by PCR, and these specific fragments are further hybridized with nonradioactive riboprobes. PCR analysis using chromosomal DNA isolated from Actinomyces species including laboratory strains, clinical isolates, and Actinomyces naeslundii (ATCC 12104) indicated the presence of the predicted common 756-bp fragment, a portion of the sialidase gene. These amplified DNA fragments were effectively visualized by hybridization with the digoxigenin-labeled riboprobes corresponding to the internal region of the amplified sialidase gene. With this system, approximately three orders of magnitude less chromosomal DNA was sufficient for the detection of specific microorganisms compared to the conventional riboprobe systems.

Actinomyces↗

PubMed1996

Complement-mediated killing of porphyromonas gingivalis 381 by the immunoglobulin G induced by recombinant 40-kDa outer membrane protein.

Porphyromonas gingivalis has been implicated as an important pathogen in severe adult periodontitis. We have previously cloned a 40-kDa outer membrane protein from P. gingivalis 381 and succeeded in producing sufficient quantities of the recombinant protein (r40-kDa OMP). r40-kDa OMP has been the subject of considerable interest to us as a possible vaccine candidate. To understand the role of anti-r40-kDa OMP antibody in the host defense mechanisms against P. gingivalis, we examined the involvement of a rabbit antibody against r40-kDa OMP (r40-kDa OMP Ab) to an in vitro complement-mediated bactericidal assay for P. gingivalis 381. By measuring the absorbance values in order to assay the surviving bacteria, we found significant anti-P. gingivalis activity of r40-kDa OMP Ab when guinea pig complement was present. Using affinity-purified immunoglobulin G of r40-kDa OMP Ab (IgG-r40-kDa OMP), we demonstrated that the IgG contributed to anti-P. gingivalis activity in the antibody-complement system. This was effected by measuring the incorporation of tritiated thymidine into newly synthesized nucleic acids. Finally, we confirmed the cell lysis of P. gingivalis 381 exposed to IgG-r40-kDa OMP in the presence of complement sources in a radioactive bactericidal assay using bacteria labeled with [14C]sodium acetate. Assembling the data from experiments using component-deficient complements, we concluded that IgG-r40-kDa OMP was related to the killing of P. gingivalis 381 by mediation in the complement activated through both the classical and the alternative pathways.

Animals↗

PubMed1996

Stimulation of interleukin-1beta-independent interleukin-6 production in human dental pulp cells by lipopolysaccharide.

Dental pulpal infection is most commonly caused by extensive dental caries. A principal driving force behind pulpal disease response appears to lie in the immune system's response to bacteria. However, the production of interleukin (IL)-1beta and IL-6 in human dental pulp (HDP) cells in response to lipopolysaccharide (LPS) has not been well characterized. We examined IL-1beta and IL-6 production in HDP cells by challenging with LPS from Porphyromonas endodontalis, which is a Gram-negative bacteria found in root canals. Our results presented here showed that when HDP cells were stimulated by LPS, the production of IL-6 always preceded that of IL-1beta. Since the IL-6 production was observed even in the presence of the IL-1beta receptor antagonist, we concluded IL-6 production was independent of the IL-1beta molecule in LPS-stimulated HDP cells. This idea was further supported by the results obtained from RT-PCR experiments, in which IL-6 mRNA, but not IL-1beta mRNA, was present in the RNA preparation isolated from the early stage of cells.

Cells, Cultured↗

PubMed1996

Role of the sympathetic nervous system in the ischemic and reperfused heart.

Norepinephrine, that has been released from sympathetic nerve endings in response to myocardial ischemia, may have either a beneficial or a harmful effect on the ischemic heart. If the duration of ischemia is short, the release of norepinephrine may be favorable for the production of energy and for protection of the heart against ischemic damage. If the duration of ischemia is prolonged, there is a marked increase in number of both alpha 1 and beta-adrenoceptors located in the sarcolemmal membrane, as well as an excessive increase in release of norepinephrine. These events during the prolonged period of ischemia can produce an imbalance between oxygen supply and demand, which is harmful to the heart. The anti-ischemic effect of alpha 1- and beta-adrenoceptor antagonists is not attributed merely to improvement of oxygen balance, but reduction of phospholipase activity or stabilization of membrane may also be important as an underlying mechanism.

Adrenergic alpha-Antagonists↗

PubMed1996

Exogenous lysophosphatidylcholine increases non-selective cation current in guinea-pig ventricular myocytes.

Whole cell, patch-clamp studies were performed to examine the effect of lysophosphatidylcholine (LPC) on the membrane current in guinea-pig ventricular myocytes. The addition of 10 microM LPC to the external solution induced a membrane current which had a reversal potential of 0 mV. When Na+, the main cation in the external solution, was replaced by either K+, N-methyl-D-glucamine (NMG) or 90 mM Ca2+, LPC induced a current with the reversal potential near 0 mV, indicating that the current passed through a Ca2+-permeable non-selective cation channel. The order of the cationic permeability calculated from the reversal potential of the current was Cs+ > K+ > NMG > Na+ > Ca2+. Cl- did not pass through the LPC-induced channel. The LPC-induced current was not blocked by Gd3+ in the external solution, nor by the absence of Ca2+ in the pipette solution. In conclusion, LPC induces a Ca2+-permeable non-selective cation channel in guinea-pig ventricular myocytes.

Animals↗

PubMed1996

Involvement of nitric oxide in spinally mediated capsaicin- and glutamate-induced behavioural responses in the mouse.

The intrathecal (i.t.) injection of capsaicin (0.1 nmol/mouse) through a lumbar puncture elicited scratching, biting and licking responses. Pretreatment with the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) (320 nmol), by i.t. injection, resulted in a significant inhibition of the behavioural response produced by i.t. capsaicin (0.1 nmol/mouse). Similar behavioural responses were induced by i.t. injections of NMDA (0.4 nmol), kainate (0.05 nmol) or AMPA (0.05 nmol), which were all inhibited by co-administration of L-NAME (20-80 nmol). L-Arginine (600 mg/kg, i.p.) but not D-arginine (600 mg/kg, i.p.) reversed the inhibitory effect of L-NAME on capsaicin-, NMDA-, kainate- and AMPA-induced behavioural response. Scratching, biting and licking responses induced by tachykinin receptor agonists, substance P, [Sar9,Met(O2)11]substance P, neurokinin A and neurokinin B were not affected by co-administration of L-NAME (40 and 80 nmol). These results suggest that spinal nitric oxide may play a significant role in mechanisms of the behavioural response to capsaicin, probably through the release of glutamate, but not tachykinins.

Animals↗

PubMed1996

Impaired specific cellular immunity to the varicella-zoster virus in patients with herpes zoster oticus.

The possible involvement of depression on cellular immunity in reactivation of varicella-zoster virus (VZV) in herpes zoster oticus was investigated. The subjects comprised 59 cases of herpes zoster oticus, 33 cases of herpes zoster sine herpete (ZSH) with facial paralysis, and 205 cases of Bell's palsy. The transformation rate of lymphocytes to phytohaemagglutinin in herpes zoster oticus tended to be lower than that in Bell's palsy. In skin tests with purified protein derivatives of tuberculin, the positivity rate in herpes zoster oticus was significantly lower than that in Bell's palsy (p < 0.015). In skin tests using VZV antigen the positivity rate in herpes zoster oticus and ZSH were significantly lower than that of Bell's palsy (p < 0.001 and p < 0.015, respectively). Thus, it was noted that cellular immunity, especially specific cellular immunity against VZV, was significantly depressed in herpes zoster oticus and ZSH. We consider that depression of specific cellular immunity plays an important role in triggering reactivation of VZV and onset of these diseases.

Adolescent↗

PubMed1996

Effects of beta-adrenoceptor antagonists on Ca(2+)-overload induced by lysophosphatidylcholine in rat isolated cardiomyocytes.

1. The effects of beta-adrenoceptor antagonists including (-)- and (+)-propranolol, (-)- and (+)-penbutolol, timolol, pindolol, atenolol, acebutolol and practolol on the Ca(2+)-overload induced by lysophosphatidylcholine (LPC) were examined in isolated cardiomyocytes of the rat. 2. Fura-2 was used for measurement of the intracellular calcium concentration ([Ca2+]i). LPC (15 microM) produced a rapid increase in [Ca2+]i from 72 +/- 5 to 3042 +/- 431 nM which coincided with a decrease in the percentage of rod-shaped cells from 69 +/- 2 to 5 +/- 2%. 3. Preincubation with (-)-propranolol (20 microM), (+)-propranolol (50 microM), or (-)- or (+)-penbutolol (20 microM), the lipophilicity of which is higher than other beta-adrenoceptor antagonists, significantly inhibited both the increase in [Ca2+]i and the cell-shape change induced by 15 microM LPC. The inhibitory effects of the four drugs on the LPC-induced increase in [Ca2+]i and cell-shape change were concentration-dependent. The IC50S of (-)-propranolol, (+)-propranolol, (-)- and (+)-penbutolol for the increase in [Ca2+]i were 1.28, 10.50, 0.67 and 0.76 microM, respectively. 4. Pretreatment with pindolol, timolol, acebutolol, practolol, atenolol or lignocaine did not inhibit the increase in [Ca2+]i and the morphological change induced by LPC. 5. LPC markedly increased the release of creatine phosphokinase from 9 +/- 1 to 45 +/- 2% which could be significantly reduced by (-)- or (+)-propranolol but not by acebutolol or timolol. 6. The protective effects of (-)- and (+)-propranolol, (-)- and (+)-penbutolol against the Ca(2+)-overload induced by LPC were not associated with the beta-adrenoceptor antagonistic action, but probably with an unknown action which is related to the preservation of membrane integrity. Further studies are necessary to clarify the exact mechanisms of the protective action of these beta-adrenoceptor antagonists against the Ca(2+)-overload induced by LPC.

Adrenergic beta-Antagonists↗

PubMed1996

Effect of in vitro aging on Campylobacter rectus lipopolysaccharide-stimulated PGE2 release from human gingival fibroblasts.

OBJECTIVE: We examined the influence of in vitro aging on Campylobacter rectus (C. rectus) lipopolysaccharide (LPS)-stimulated prostaglandin (PG), E2 release frOm human gingival fibroblasts (HGFs). MATERIALS AND METHODS: LPS was prepared from C. rectus ATCC33238. HGFs were established from healing gingival tissue removed from three patients (donors A, B and C), aged 10-12 years. Aging of the cells in culture was determined with increasing population doubling. The cells were cultured until confluence, then stimulated with LPS (1.0 micrograms ml-1), and the levels of PGE2 in the medium were measured after 24 h by radioimmunoassay. RESULTS: The LPS-stimulated PGE2 production in each old cell (passage 17-20) was significantly increased to about 1.6-2.6 times than that in the corresponding young cells (passage 5-6). The gene expression of cyclooxygenase-2 mRNA in the old cells was higher than that in the young cells in response to LPS. In the absence of LPS, PGE2 production levels in both the young and old cells were very low, and also at the same level. However, there was a higher level of LPS-stimulated PGE2 production in the young cells from donor C compared to that in the old cells from donor B. The LPS-stimulated PGE2 production in each young cell from donors A and C was almost equal to that in each old cell from donors B and A, respectively. CONCLUSIONS: The results suggested that aging in HGFs may be one of the factors that take part in the stimulation of C. rectus LPS-stimulated PGE2 production in old cells.

Analysis of Variance↗