Biomedical subjects

M Yoshida

Publications and source records attributed to M Yoshida.

At least 721 records · Page 40Linked to original sources

PubMed1998

phd1+, a histone deacetylase gene of Schizosaccharomyces pombe, is required for the meiotic cell cycle and resistance to trichostatin A.

A gene named phd1+ encoding a protein highly homologous to the yeast and human histone deacetylases, such as Saccharomyces cerevisiae Rpd3p and human HDAC1, was cloned from Schizosaccharomyces pombe. The immune complex isolated from S. pombe cells expressing Phd1 fused to the FLAG epitope showed histone deacetylase activity, which was inhibited by trichostatin A (TSA), a specific inhibitor of histone deacetylase. The null mutation of phd1+ resulted in a marked decrease in the total cellular histone deacetylase activity and an increase in the sensitivity to TSA. Although the phd1 disruptant showed no obvious defect in the mitotic cell cycle or mating, both homothallic haploid and heterothallic diploid cells failed to form spores in the absence of phd1+. These results indicate that phd1+ encodes a histone deacetylase, which is involved in the meiotic cell cycle in S. pombe.

Base Sequence↗

PubMed1998

The possible effect of nitric oxide on relaxation and noradrenaline release in the isolated rabbit urethra.

We evaluated the effects of N(omega)-nitro-L-arginine (L-NNA, a nitric oxide (NO) synthase inhibitor) and carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO, a NO scavenger) on NO-mediated relaxation and noradrenaline release from adrenergic nerve endings induced by electrical field stimulation in the rabbit urethra. Electrical field stimulation caused frequency-dependent relaxation of rabbit urethral smooth muscles precontracted with phenylephrine. The relaxation responses were significantly inhibited by treatment with L-NNA or carboxy-PTIO. The inhibitory effect of carboxy-PTIO was significantly weaker than that of L-NNA. Electrical field stimulation caused significant noradrenaline release from adrenergic nerve endings in the rabbit urethra. Treatment with carboxy PTIO enhanced electrical field stimulation-induced noradrenaline release, and simultaneous application of L-NNA and carboxy-PTIO did not further enhance noradrenaline release in the rabbit urethra. As carboxy-PTIO reacts only with the free radical NO, the present results suggest that free radical NO and NO-containing compounds are involved in the L-NNA-sensitive nitrergic nerve-mediated relaxation in the rabbit urethra. At the same time free radical NO has a prejunctional action by which it may inhibit noradrenaline release from adrenergic nerves.

Animals↗

PubMed1998

Purification and characterization of a novel physiological substrate for calcineurin in mammalian cells.

Although the calcium/calmodulin-regulated protein phosphatase calcineurin has been shown to play a role in a number of intracellular processes, relatively few of the downstream phosphoproteins that are dephosphorylated by this enzyme in cells have been described. Calcineurin was previously shown to play a role in amylase secretion by rat pancreatic acinar cells and to specifically dephosphorylate a 24-kDa cytosolic protein. The present study describes the purification and characterization of this novel phosphoprotein, termed CRHSP-24 (calcium-regulated heat-stable protein with a molecular mass of 24 kDa). Microgram quantities of CRHSP-24 were purified from a large-scale rat pancreas preparation in a procedure involving heat and acid precipitation, anion-exchange chromatography, preparative electrophoresis, electroelution, and two-dimensional electrophoresis. Internal amino acid sequence was obtained from two peptides following trypsin digestion and high pressure liquid chromatography. Both sequences matched with 100% identity nucleotide sequences of expressed sequence tags from human placenta and rat PC-12 cells. Two CRHSP-24 transcripts of 0.7 and 2. 9 kilobases were detected in multiple rat tissues by Northern analysis, whereas a single 24-kDa protein was observed by Western blotting. The CRHSP-24 protein is 147 amino acids in length, is composed of nearly 14% proline, and is phosphorylated entirely on serine residues. Western analysis and 32P metabolic labeling of acini revealed CRHSP-24 to be maximally phosphorylated in control cells and to undergo a rapid sustained dephosphorylation on at least 3 serine residues in response to calcium-mobilizing stimuli. Dephosphorylation of CRHSP-24 was completely inhibited by pretreatment of acini with cyclosporin A or FK506. Furthermore, the inhibitory effects of FK506 were blocked by excess rapamycin. The ubiquitous expression of CRHSP-24 in rat tissues suggests that this novel calcineurin substrate plays a common role in calcium-mediated signal transduction.

Amino Acid Sequence↗

PubMed1998

Interaction site for soluble cytochromes on the tetraheme cytochrome subunit bound to the bacterial photosynthetic reaction center mapped by site-directed mutagenesis.

The crystallographic structure of the Blastochloris (formerly called Rhodopseudomonas) viridis tetraheme cytochrome subunit bound to the photosynthetic reaction center (RC) suggests that all four hemes are located close enough to the surface of the protein to accept electrons from soluble cytochrome c2. To identify experimentally the site of this reaction we prepared site-directed mutants of Rubrivivax gelatinosus RCs with surface charge substitutions in the bound cytochrome subunit and studied the kinetics of their reduction by soluble cytochromes (mitochondrial horse cytochrome c, Blc. viridis cytochrome c2, and Rvi. gelatinosus cytochrome c8). In comparison with the wild-type, the mutants E79K (glutamate-79 substituted by lysine), E93K (glutamate-93 substituted by lysine), and E85K (glutamate-85 substituted by lysine) located near the solvent-exposed edge of low-potential heme 1, the fourth heme from the special pair of bacteriochlorophyll, exhibited decreased second-order rate constants for the reaction between the tetraheme subunit and the soluble cytochromes. Double charge substitutions in this region: E79K/E85K (glutamate-79 and -85 both replaced by lysine) and E93K/E85K (glutamate-93 and -85 both replaced by lysine) appeared to show an additive inhibitory effect. Mutations in other charged regions did not alter the kinetics of electron transfer between bound and soluble cytochromes. In light of the available structural information on Blc. viridis RC, these results indicate that the cluster of acidic residues immediately surrounding the distal heme 1 of the RC-bound tetraheme subunit forms an electrostatically favorable binding site for soluble cytochromes. Thus, all four hemes in the subunit seem to be directly involved in the electron transfer toward the photo-oxidized special pair of bacteriochlorophyll. On the basis of these findings, a model is proposed for the hypothetical cytochrome c2-RC transient complex for Blc. viridis.

Amino Acid Substitution↗

PubMed1998

Misincorporation of 2'-deoxyoxanosine 5'-triphosphate by DNA polymerases and its implication for mutagenesis.

2'-Deoxyoxanosine (dOxo) is a novel DNA lesion produced by the reaction of 2'-deoxyguanosine (dGuo) with nitrous acid and nitric oxide [Suzuki, T., Yamaoka, R., Nishi, M., Ide, H., and Makino, K. (1996) J. Am. Chem. Soc. 118, 2515-2516]. In this work, 2'-deoxyoxanosine 5'-triphosphate (dOTP) was prepared by nitrous acid treatment of 2'-deoxyguanosine 5'-triphosphate (dGTP), and its incorporation into DNA by DNA polymerases was investigated to elucidate the substrate and mutagenic properties of dOTP. Primed M13mp18 DNA was replicated by Escherichia coli DNA polymerase I Klenow fragment (Pol I Kf) in the presence of three normal dNTPs and dOTP or 2'-deoxyxanthosine 5'-triphosphate (dXTP), another major product of reaction of dGTP with nitrous acid and nitric oxide. dOTP substituted for dGTP and to a lesser extent for dATP, while dXTP substituted slightly for dGTP but not for dATP. Neither dOTP nor dXTP substituted for dCTP and dTTP. The similar results were obtained for the incorporation by T7 DNA polymerase deficient in 3'-5' exonuclease [T7(exo-)]. To quantify the substitution efficiency, kinetic parameters for incorporation of dOTP and dXTP opposite template C or T by Pol I Kf (exo-) were determined and compared with those for dGTP using oligodeoxynucleotide templates. Incorporation efficiencies (f = Vmax/Km) of dOTP (f = 0.28% min-1 microM-1) and dXTP (f = 0.10% min-1 microM-1) opposite template C were much lower than that of dGTP (f = 1506% min-1 microM-1). Frequencies of mutagenic incorporation of dOTP opposite template T were dependent on the nearest neighbor base pairs, and 1.6-3.9-fold higher than those for dGTP with the nearest neighbors containing G.C pairs. dXTP was not incorporated opposite template T with all four nearest neighbors. These data suggest that formation of dOTP, but not dXTP, from dGTP with nitrous acid or nitric oxide in the intracellular nucleotide pool would result in the elevation of the mutation frequency.

Anti-Bacterial Agents↗

PubMed1998

V-ATPase of Thermus thermophilus is inactivated during ATP hydrolysis but can synthesize ATP.

The ATP hydrolysis of the V1-ATPase of Thermus thermophilus have been investigated with an ATP-regenerating system at 25 degreesC. The ratio of ATPase activity to ATP concentration ranged from 40 to 4000 microM; from this, an apparent Km of 240 +/- 24 microM and a Vmax of 5.2 +/- 0.5 units/mg were deduced. An apparent negative cooperativity, which is frequently observed in case of F1-ATPases, was not observed for the V1-ATPase. Interestingly, the rate of hydrolysis decayed rapidly during ATP hydrolysis, and the ATP hydrolysis finally stopped. Furthermore, the inactivation of the V1-ATPase was attained by a prior incubation with ADP-Mg. The inactivated V1-ATPase contained 1.5 mol of ADP/mol of enzyme. Difference absorption spectra generated from addition of ATP-Mg to the isolated subunits revealed that the A subunit can bind ATP-Mg, whereas the B subunit cannot. The inability to bind ATP-Mg is consistent with the absence of Walker motifs in the B subunit. These results indicate that the inactivation of the V1-ATPase during ATP hydrolysis is caused by entrapping inhibitory ADP-Mg in a catalytic site. Light-driven ATP synthesis by bacteriorhodopsin-VoV1-ATPase proteoliposomes was observed, and the rate of ATP synthesis was approximately constant. ATP synthesis occurred in the presence of an ADP-Mg of which concentration was high enough to induce complete inactivation of ATP hydrolysis of VoV1-ATPase. This result indicates that the ADP-Mg-inhibited form is not produced in ATP synthesis reaction.

Adenosine Diphosphate↗

PubMed1998

Leptomycin B inhibition of signal-mediated nuclear export by direct binding to CRM1.

Leptomycin B (LMB) is a Streptomyces metabolite that inhibits nuclear export of the human immunodeficiency virus type 1 regulatory protein Rev at low nanomolar concentrations. Recently, LMB was shown to inhibit the function of CRM1, a receptor for the nuclear export signal (NES). Here we show evidence that LMB binds directly to CRM1 and that CRM1 is essential for NES-dependent nuclear export of proteins in both yeast and mammalian cells. Binding experiments with a biotinylated derivative of LMB and a HeLa cell extract led to identifying CRM1 as a major protein that bound to the LMB derivative. Microinjection of a purified anti-human CRM1 antibody into the mammalian nucleus specifically inhibited nuclear export of NES-containing proteins, as did LMB. Consistent with this, CRM1 was found to interact with NES, when assayed with immobilized NES and HeLa cell extracts. This association was disrupted by adding LMB or purified anti-human CRM1 antibody. The inhibition of CRM1 by LMB was also observed in fission yeast. The fission yeast crm1 mutant was defective in the nuclear export of NES-fused proteins, but not in the import of nuclear localization signal (NLS)-fused proteins. Interestingly, a protein containing both NES and NLS, which is expected to shuttle between nucleus and cytoplasm, was highly accumulated in the nucleus of the crm1 mutant cells or of cells treated with LMB. These results strongly suggest that CRM1 is the target of LMB and is an essential factor for nuclear export of proteins in eukaryotes.

Biological Transport, Active↗

PubMed1998

Direct observation of the rotation of epsilon subunit in F1-ATPase.

Rotation of the epsilon subunit in F1-ATPase from thermophilic Bacillus strain PS3 (TF1) was observed under a fluorescence microscope by the method used for observation of the gamma subunit rotation (Noji, H., Yasuda, R., Yoshida, M., and Kinosita, K., Jr. (1997) Nature 386, 299-302). The alpha3 beta3 gamma epsilon complex of TF1 was fixed to a solid surface, and fluorescently labeled actin filament was attached to the epsilon subunit through biotin-streptavidin. In the presence of ATP, the filament attached to epsilon subunit rotated in a unidirection. The direction of the rotation was the same as that observed for the gamma subunit. The rotational velocity was slightly slower than the filament attached to the gamma subunit, probably due to the experimental setup used. Thus, as suggested from biochemical studies (Aggeler, R., Ogilvie, I. , and Capaldi, R. A. (1997) J. Biol. Chem. 272, 19621-19624), the epsilon subunit rotates with the gamma subunit in F1-ATPase during catalysis.

Actin Cytoskeleton↗

PubMed1998

The role of BK(Ca) channels in the nitric oxide-mediated regulation of adrenal catecholamine secretion.

We examined whether high conductance Ca2+-activated K+ (BK(Ca)) channels are involved in the modulatory action of nitric oxide (NO) on the secretion of adrenal catecholamines in response to splanchnic nerve stimulation and acetylcholine in anesthetized dogs. The NO donor 3-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-propanamin e (NOC 7), the BK(Ca) channel blocker charybdotoxin and acetylcholine were administered intraarterially (i.a.) into the adrenal gland. NOC 7 infusion (2 microg min(-1)) inhibited increases in catecholamine output induced by splanchnic nerve stimulation (1-3 Hz) and acetylcholine (0.75-3 microg). Charybdotoxin infusion (100 ng min(-1)) did not affect increases in catecholamine output induced by splanchnic nerve stimulation and acetylcholine. Charybdotoxin blocked the NOC 7-induced inhibition of increases in catecholamine output induced by splanchnic nerve stimulation but not by acetylcholine. These results suggest that NO may inhibit the secretion of adrenal catecholamines induced by splanchnic nerve stimulation through activation of BK(Ca) channels.

Acetylcholine↗

PubMed1998

Mechanism of antitumor action of PKC activator, gnidimacrin.

Daphnane-type diterpene gnidimacrin isolated from the Chinese plant Stellera chamaejasme L. is an antitumor agent that activates protein kinase C (PKC). The mechanism of antitumor action of gnidimacrin and the possible involvement of PKC were examined using sensitive K562 and refractory HLE cells. Gnidimacrin did bind to K562 cells 3 times more than to HLE cells. Immunoblot analyses revealed pronounced PKC betaII expression in gnidimacrin sensitive cell lines including K562 cells, while refractory HLE cells strongly expressed PKC alpha, but not PKC betaII. In a 24-hr exposure of K562 cells to gnidimacrin, G1 phase arrest and inhibition of cdk2 kinase activity was found at growth-inhibitory concentration (0.0005 microg/ml). Complete inhibition of cdk2 activity and maximum G1 phase arrest were observed at 0.005 microg/ml, however, these biological effects were reduced at 0.05 microg/ml (260 times the 50% inhibitory concentration). Cellular PKC after a 24-hr exposure was examined by immunoblot analysis and specific binding of [3H]phorbol-12,13-dibutyrate as a ligand of PKC. Expression and the amount of functional PKC of K562 cells were not changed at 0.002 microg/ml, but down-regulated to less than 1/10th of the control at 0.05 microg/ml. The reduction of biological effects at 0.05 microg/ml is most likely due to PKC down-regulation. Our results suggest that PKC (particularly betaII) is one of the major determinants of the ability of cells to respond to gnidimacrin and that the antitumor action might be associated with cell-cycle regulation through suppression of cdk2 activity.

Antineoplastic Agents, Phytogenic↗

PubMed1998

Phosphorylation of the cytoplasmic domain of E-selectin is regulated during leukocyte-endothelial adhesion.

E-selectin, a selectin expressed on activated vascular endothelium, supports rolling and stable adhesion of leukocytes at sites of inflammation. Previously, we have reported that leukocyte adhesion to cultured endothelial cells induces association of the cytoplasmic domain of E-selectin with cytoskeletal elements, suggesting that outside-in signaling may occur during E-selectin-mediated adhesion. To investigate this potential signaling function of E-selectin, HUVEC activated with recombinant human IL-1beta (10 U/ml, 4 h) were labeled with [32P]orthophosphate, and E-selectin was immunoprecipitated using mAb H18/7. Autoradiography revealed constitutive phosphorylation of E-selectin in these cells and time-dependent dephosphorylation following adhesion of HL-60 cells. Cross-linking of cell surface E-selectin using H18/7 and a polyclonal secondary Ab induced E-selectin dephosphorylation, as did adhesion of beads coated with recombinant P-selectin glycoprotein ligand-1 (PSGL-1), an E-selectin ligand. Using adenoviral vector-mediated transfection in HUVEC of a tail-less E-selectin and phosphoamino acid analysis, we documented phosphorylation occurring exclusively within the cytoplasmic domain and involving serine residues. Additional experiments using a series of cytoplasmic domain mutants of E-selectin expressed in COS-7 cells localized the regions that were constitutively phosphorylated. Preincubation with okadaic acid and sodium vanadate abrogated adhesion-induced dephosphorylation of E-selectin. Thus, E-selectin, which is constitutively phosphorylated in cytokine-activated human endothelial cells, undergoes an enzymatically regulated dephosphorylation following leukocyte adhesion. This process appears to be triggered by multivalent ligand binding and/or cross-linking of cell surface E-selectin. Ligand-dependent regulation of the phosphorylation of E-selectin's cytoplasmic domain provides additional evidence for a transmembrane signaling function of this molecule during leukocyte-endothelial interactions.

Amino Acid Sequence↗

PubMed1998

F1-ATPase is a highly efficient molecular motor that rotates with discrete 120 degree steps.

A single molecule of F1-ATPase, a portion of ATP synthase, is by itself a rotary motor in which a central gamma subunit rotates against a surrounding cylinder made of alpha3beta3 subunits. Driven by three catalytic betas, each fueled with ATP, gamma makes discrete 120 degree steps, occasionally stepping backward. The work done in each step is constant over a broad range of imposed load and is close to the free energy of hydrolysis of one ATP molecule.

Actin Cytoskeleton↗

PubMed1998

Selective kana jargonagraphia following right hemispheric infarction.

A strongly right-handed Japanese man showed an unusual writing disorder associated with Broca-type aphasia after suffering a right hemispheric infarction. Writing with his right hand produced a fluent output in contrast to his nonfluent speech. The patient's agraphia disproportionately affected the writing of kana (Japanese syllabograms), leaving relatively intact the writing of kanji (Japanese ideograms). His kana agraphia, consisting of substitutions, intrusions, transpositions, and deletions, became apparent as the number of syllables in target words increased. Quantitative analysis of the substitutions in terms of their phonological similarity to the target revealed that most of the substitutions were phonologically dissimilar. Those errors were distributed almost identically for familiar and novel words. Moreover, the errors were observed asymmetrically across the target: more errors occurred near the end than at the beginning of a word. The kana agraphia in association with fluent writing output resulted in kana jargonagraphia. These observations suggest that our patient's selective kana jargonagraphia is best explained by selective damage to the hypothesized kana graphemic buffer and by disinhibition of the motor engrams of writing behavior, both of which resulted from right hemispheric damage.

Agraphia↗

PubMed1998

Immunochemical approaches to AGE-structures: characterization of anti-AGE antibodies.

Recent immunological approaches have greatly helped broaden our understanding of the biomedical significance of advanced glycation end products (AGEs) in aging and age-enhanced disease processes. Recently, Nepsilon-(carboxymethyl) lysine (CML), one of the glycoxidation products of AGEs, was demonstrated to be a major immunological epitope among AGEs. In the subsequent study, we characterized 13 different polyclonal anti-AGE antibodies and showed that these antibodies could be classified into three groups (Groups I, II and III). Group I was specific for CML and both Group II and Group III were specific for other epitopes (non-CML). Time-course study suggested that the epitope of Group II was formed earlier than that of Group III. In the present study, we prepared two monoclonal anti-AGE antibodies (2A2 and 3A3) whose epitope structures appeared to be closely related to Group III and Group II, respectively. The result indicates that AGE-proteins express at least two major non-CML epitopes.

Animals↗

PubMed1998

FR901228, a potent antitumor antibiotic, is a novel histone deacetylase inhibitor.

Screening for microbial metabolites that induce transcriptional activation of the SV40 promoter resulted in the identification of two known compounds, FR901228 and trichostatin A (TSA). FR901228 is a potent antitumor drug that is currently under clinical investigation. TSA is a specific inhibitor of histone deacetylase. Despite structural unrelatedness, both FR901228 and TSA greatly enhanced the transcriptional activity of the SV40 promoter in an enhancer-dependent manner. The effects of FR901228 on the cell cycle, chromatin structure, and histone acetylation were examined and compared with those of TSA. Both compounds caused arrest of the cell cycle at both G1 and G2/M phases and induction of internucleosomal breakdown of chromatin. FR901228, like TSA, inhibited intracellular histone deacetylase activity, as a result of which marked amounts of acetylated histone species accumulated. FR901228 is therefore a new type of histone deacetylase inhibitor, whose chemical structure is unrelated to known inhibitors such as trichostatins and trapoxins.

Acetylation↗

PubMed1998

Non-histone chromosomal proteins HMG1 and 2 enhance ligation reaction of DNA double-strand breaks.

DNA ligase IV in a complex with XRCC4 is responsible for DNA end-joining in repair of DNA double-strand breaks (DSB) and V(D)J recombination. We found that non-histone chromosomal high mobility group (HMG) proteins 1 and 2 enhanced the ligation of linearized pUC119 DNA with DNA ligase IV from rat liver nuclear extract. Intra-molecular and inter-molecular ligations of cohesive-ended and blunt-ended DNA were markedly stimulated by HMG1 and 2. Recombinant HMG2-domain A, B, and (A + B) polypeptides were similarly, but non-identically, effective for the stimulation of DSB ligation reaction. Ligation of single-strand breaks (nicks) was only slightly activated by the HMG proteins. The DNA end-binding Ku protein singly or in combination with the catalytic component of DNA-dependent protein kinase (DNA-PK) as the DNA-PK holoenzyme was ineffective for the ligation of linearized pUC119 DNA. Although the stimulatory effect of HMG1 and 2 on ligation of DSB in vitro was not specific to DNA ligase IV, these results suggest that HMG1 and 2 are involved in the final ligation step in DNA end-joining processes of DSB repair and V(D)J recombination.

Animals↗

PubMed1998

A new system for the measurement of electrogenicity produced by ion pumps using a thin polymer film: examination of wild type bacteriorhodopsin and the D96N mutant over a wide pH range.

We developed a new assay system for the measurement of capacitive electric currents generated by ion pumps using the thin polymer film 'Lumirror' (Toray Co., Japan). This system enables us to examine the electrogenicity of ion pumps over a wide range of experimental conditions with high reproducibility due to the mechanical and chemical stability, the high electric resistance and the high electric capacitance of the thin polymer film. Using this method, we examined the photoelectric response of wild type bacteriorhodopsin and its D96N mutant over a wide pH range (2.8-10.0). The results were explained in terms of the affinities of the proton binding sites for translocated protons. A possibility that the direction of the proton transfer from the Schiff base was influenced by the protonation/deprotonation state of the surrounding proton binding sites was suggested. We also found that this film can be used as a substrate for atomic force microscopy (AFM) samples and hence the active purple membrane was observed with AFM.

Bacteriorhodopsins↗

PubMed1998

Effects of steroid and lipopolysaccharide on spontaneous resorption of herniated intervertebral discs. An experimental study in the rabbit.

STUDY DESIGN: Histologic examination was performed on autografted intervertebral disc materials of rabbit models, which were partially incised through a retroperitoneal approach at L1-L2 and grafted within the posterior epidural space at L4. OBJECTIVE: To evaluate whether the resorption process of the herniated intervertebral disc is influenced and controlled by treatments with medications. SUMMARY OF BACKGROUND DATA: Regarding resorption of herniated intervertebral discs, recent studies of magnetic resonance images and histologic investigations of surgically resected specimens in lumber disc herniation patients have been reported. It has been shown that inflammatory factors may play an important role in the mechanism of resorption of the herniated intervertebral disc. However, little is known about the origin of newly formed vessels and inflammatory cells detected in herniated disc specimens from patients. In this study, The resorption process of disc material grafted into the epidural space was observed in a rabbit model. METHODS: Thirty-six adult rabbits were used. The L1-L2 intervertebral disc was partially incised through a retroperitoneal approach. The harvested disc material, which contains the nucleus pulposus and the anulus fibrosus were placed into the posterior epidural space at L4 of the same rabbit. The animals were divided into control, and steroid groups. The control group received no treatment after surgery. In the lipopolysaccharide group, rabbits were injected 1 mg/kg into the peritoneum immediately and at 7 days after surgery. In the steroid group, rabbits were injected with 1 mg/kg betamethasone into the epidural space daily from 1 to 7 days after surgery. Rabbits of each group were killed for histologic examination at 1, 2, 4, and 8 weeks after surgery. RESULTS: At 1 and 2 weeks after surgery, inflammatory cells and newly formed vessels were more frequently observed in the lipopolysaccharide group than in the control and steroid groups. At 4 weeks after surgery, derangement and loosening of collagen fibers were also observed in the lipopolysaccharide group. At 8 weeks after surgery, fragmentation and partial disappearance of matrix were observed in the control and lipopolysaccharide groups. Most of the intervertebral discs were replaced by fibrous tissues in the lipopolysaccharide group. However, the matrix of the intervertebral disc almost remained. CONCLUSIONS: Autologous intervertebral disc material grafted into the epidural space was penetrated by newly formed vessels produced from the epidural fat tissue and resolved as the result of inflammatory reaction. Lipopolysaccharide accelerated the replacement of grafted intervertebral disc by fibrous tissue, which suggests the resorption of the disc in the epidural space of the rabbit, whereas high-dose steroid suppressed the replacement.

Animals↗