The RB-IL-6 axis controls self-renewal and endocrine therapy resistance by fine-tuning mitochondrial activity.

Retinoblastoma (RB) protein inactivation during tumor progression is often associated with acquisition of immature phenotypes and resistance to therapy. Determination of an RB inactivation signature in a context of gaining undifferentiated phenotype in a p53-null sarcoma system revealed a critical role for interleukin (IL)-6. Using a Gene Set Enrichment Analysis (GSEA), we discovered that poorly differentiated breast cancers are enriched for this RB inactivation signature. Accelerated IL-6 secretion following RB inactivation in an RB-intact luminal-type breast cancer cell line MCF-7 promoted a positive feed forward loop between IL-6 and STAT3 driving tumor growth and endocrine therapy resistance. In addition, some of RB-intact basal-like type breast cancer cell lines exhibited a similar phenotype following RB depletion. The mechanism whereby RB inactivation increases IL-6 production in MCF-7 cells appeared to involve fatty acid oxidation (FAO)-dependent mitochondrial metabolism and c-Jun NH(2)-terminal kinase (JNK). In addition, IL-6, via STAT3-mediated feedback to mitochondria, autonomously adjusts mitochondrial superoxide to levels suitable to maintain stem cell-like activity. The gene expression profile of luminal-type breast cancer patients with low RB expression revealed high enrichment of genes involved in mitochondrial respiration and downstream targets of IL-6. These findings unveiled an unexpected strategy whereby RB suppresses malignant features of cancer cells through metabolic reprogramming and cell-autonomous inflammation.

Effects of acivicin on growth, mycotoxin production and virulence of phytopathogenic fungi.

Acivicin is an inhibitor of γ-glutamyl transpeptidase and glutamine amidotransferase. When grown on a synthetic minimal agar medium, acivicin strongly inhibited the growth of Magnaporthe oryzae and Alternaria brassicicola, and to a lesser extent, Botrytis cinerea. However, only partial or marginal growth inhibition was observed with regard to Fusarium sporotrichioides and Fusarium graminearum. The growth retardation caused by acivicin was significantly alleviated by cultivating the fungus on a nutrient-rich medium. The inhibition of M. oryzae growth caused by 1 µmol l(-1) of acivicin on minimal agar medium was subdued by the addition of specific single amino acids, including His, a branched-chain amino acid (Leu, Ile or Val), an aromatic amino acid (Trp, Tyr or Phe), Met or Gln, at a concentration of 0·4 mmol l(-1). Trichothecene production by F. graminearum in trichothecene-inducing liquid medium was reduced significantly in the presence of acivicin despite its inability to inhibit growth in the trichothecene-inducing liquid medium. Foliar application of conidia in the presence of acivicin reduced the severity of rice blast disease caused by M. oryzae. These results suggest the usefulness of this modified amino acid natural product to mitigate agricultural problems caused by some phytopathogenic fungi. Significance and impact of the study: Fusarium head blight or scab disease and rice blast, caused by Fusarium graminearum and Magnaporthe oryzae, respectively, are major diseases of cereal crops that cause a significant loss of yield and deterioration in the quality of the grain. The present study investigated the effects of acivicin, a glutamine amino acid analog, on the physiology of various phytopathogenic fungi. Application of acivicin to a fungal culture and conidial suspension reduced mycotoxin production by the wheat scab fungus and the severity of rice blast, respectively. These results suggest the possibility that acivicin may serve as a lead compound to develop agricultural chemicals for the control of some plant diseases.

Effects of hypergravity stimulus on global gene expression during reproductive growth in Arabidopsis.

The life cycle of higher plants consists of successive vegetative and reproductive growth phases. Understanding effects of altered gravity conditions on the reproductive growth is essential, not only to elucidate how higher plants evolved under gravitational condition on Earth but also to approach toward realization of agriculture in space. In the present study, a comprehensive analysis of global gene expression of floral buds under hypergravity was carried out to understand effects of altered gravity on reproductive growth at molecular level. Arabidopsis plants grown for 20-26 days were exposed to hypergravity of 300 g for 24 h. Total RNA was extracted from flower buds and microarray (44 K) analysis performed. As a result, hypergravity up-regulated expression of a gene related to ß-1,3-glucanase involved in pectin modification, and down-regulated ß-galactosidase and amino acid transport, which supports a previous study reporting inhibition of pollen development and germination under hypergravity. With regard to genes related to seed storage accumulation, hypergravity up-regulated expression of genes of aspartate aminotransferase, and down-regulated those related to cell wall invertase and sugar transporter, supporting a previous study reporting promotion of protein body development and inhibition of starch accumulation under hypergravity, respectively. In addition, hypergravity up-regulated expression of G6PDH and GPGDH, which supports a previous study reporting promotion of lipid deposition under hypergravity. In addition, analysis of the metabolic pathway revealed that hypergravity substantially changed expression of genes involved in the biosynthesis of phytohormones such as abscisic acid and auxin.

A marine phytoplankton (Prymnesium parvum) up-regulates ABC transporters and several other proteins to acclimatize with Fe-limitation.

Iron (Fe) is one of the vital limiting factors for phytoplankton in vast regions of the contemporary oceans, notably the high nutrient low chlorophyll regions. Therefore, it is apparent to be acquainted with the Fe uptake strategy of marine phytoplankton under Fe-limited condition. In the present study, marine phytoplankton Prymnesium parvum was grown under Fe-deplete (0.0025 µM) and Fe-rich (0.05 µM) conditions, and proteomic responses of the organism to Fe conditions were compared. In sodium dodecyl sulfate (SDS) gel electrophoresis, 7 proteins (16, 18, 32, 34, 75, 82, and 116 kDa) were highly expressed under Fe-deplete condition, while one protein (23 kDa) was highly expressed under Fe-rich condition. These proteins were subjected to 2-dimensional gel electrophoresis (2-D DIGE) to differentiate individual proteins, and were identified by matrix-assisted laser desorption-ionization-time of flight-mass spectrometer (MALDI-TOF-MS) analysis. The results showed that under Fe-deplete condition P. parvum increases the biosynthesis of ATP binding cassette (ABC) transporters, flagellar associated protein (FAP), and Phosphoribosylaminoimidazole-succinocarboxamide synthase. These proteins are assumed to be involved in a number of cellular biochemical processes that facilitate Fe acquisition in phytoplankton. Under Fe-deplete condition, P. parvum increases the synthesis of ribulose biphosphate carboxylase (RuBisCo), malate dehydrogenase, and two Fe-independent oxidative stress response proteins, manganese superoxide dismutase (MnSOD) and Serine threonine kinase (STK). Thus, marine phytoplankton may change their Fe acquisition strategy by altering the biosynthesis of several proteins in order to cope with Fe-limitation.

Raloxifene inhibits menin-dependent estrogen receptor activation in breast cancer cells.

BACKGROUND: Menin is a tumor suppressor encoded by Men1 that is mutated in the human-inherited tumor syndrome--multiple endocrine neoplasia type 1. Menin binds to estrogen receptors (ER) to enhance estrogen activity in breast cancer cells. AIM: Our clinical study showed that the outcome in the case of menin-positive tumors was worse than in the case of menin-negative tumors. We examined the role of raloxifene on the cell growth in a menin-positive breast cancer cell line. MATERIAL AND METHODS: To examine the mechanism of raloxifene on menin-dependent activation of ER, we employed the mammalian two-hybrid system. We have established a breast cancer cell line that stably expresses menin. Using these cells, we have examined the effect of raloxifene and tamoxifen on cell growth of menin-transfected cells. RESULTS: The expression of activation function (AF)-2 enhanced menin-mediated luciferase expression in the mammalian two-hybrid assay. Raloxifene attenuated the effect of menin on estrogen response element-luciferase activation, indicating that raloxifene inhibited the binding of menin to AF-2. Raloxifene significantly inhibited the growth of menin-transfected cells in a dose-dependent manner. Tamoxifen also inhibited menin-transfected MCF-7 cells; however, this inhibition was much less than that of raloxifene. CONCLUSION: Raloxifene inhibits the binding of menin to the AF-2 domain of ERα, suggesting that raloxifene is one of the therapeutic options for menin-positive breast cancer.

Quantitative laser atom probe analyses of hydrogenation-disproportionated Nd-Fe-B powders.

We report a successful atom probe tomography of hydrides in hydrogenation-disproportionated Nd-Fe-B powder using a green femtosecond laser. The atom probe specimens were prepared from one particle of powder using the focused ion beam lift-out method. The atom probe tomography taken from an α-Fe/NdH(2) structure suggested that B and Ga (trace added element) were partitioned in the NdH(2) phase. The hydrogen concentration of 64 at% determined from the atom probe analysis was in excellent agreement with the stoichiometry of the NdH(2) phase.

Hyperglycemia suppresses ABCA1 expression in vascular smooth muscle cells.

Hyperglycemia is a major risk factor for atherosclerotic disease. The ATP-binding cassette transporter A1 (ABCA1) functions as a pivotal regulator of lipid efflux from cells to apolipoproteins and is thus involved in lowering the risk of atherosclerosis. In this study, we have examined the glucose-mediated regulation of the ABCA1 gene expression in vascular smooth muscle cells. ABCA1 expression was examined by real-time polymerase chain reaction (PCR), Western blot analysis, and reporter gene assay. The results showed that the expression of the ABCA1 mRNA and protein decreased after the cells were treated with 22.4 mM glucose for 48 h. The transcriptional activity of the ABCA1 promoter paralleled the endogenous expression of the ABCA1 gene. Next, we used inhibitors of certain signal transduction pathways to demonstrate that the glucose-induced ABCA1 suppression is sensitive to the p38-mitogen-activated protein kinase (MAPK) inhibitors. The expression of a constitutively active form of p38-MAPK in the cells inhibited the ABCA1 promoter activity, irrespective of the presence of glucose. A dominant-negative mutant of p38-MAPK abrogated the inhibitory effect of glucose on the ABCA1 promoter activity. These results indicate that the glucose-induced suppression of ABCA1 expression is partially mediated by the activation of the p38-MAPK pathway.

Interferon alpha decreases expression of human scavenger receptor class BI, a possible HCV receptor in hepatocytes.

BACKGROUND: Infection with the hepatitis C virus (HCV) causes acute hepatitis. This disease has a high probability of becoming chronic and leading to cirrhosis, but a more deadly consequence is hepatocellular carcinoma. Interferon alpha (IFN alpha)-based treatment combined with ribavirin is the major therapeutic choice available for the treatment of chronic HCV infection. AIMS: The scavenger receptor class B type I (SR-BI) or its human homologue CD36 and LIMPII Analogous-1 (hSR-BI/CLA-1) has recently been shown to interact with HCV envelope glycoprotein E2, thus suggesting that it might participate in entry of the virus into host cells. This rationale underlies current interest in the potential role of IFN alpha in hSR-BI/CLA-1 expression in HepG2 cells. RESULTS: It was shown that endogenous hepatocyte expression of hSR-BI/CLA-1 was suppressed by exposure to IFN alpha. Decreased hSR-BI/CLA-1 expression in IFN alpha-treated cells was due to lower transcriptional activity of the promoter. A potential pathway for the effect of IFN alpha on hSR-BI/CLA-1 promoter activity was identified when the inhibitory action of IFN was abrogated in signal transducer and activator of transcription 1 (STAT1)/STAT2 knocked-down cells. Exposure of HepG2 cells to IFN alpha elicited a rapid phosphorylation of STAT1/STAT2, a known target of IFN alpha signalling. In addition, the mutagenesis of a STAT1/STAT2 response element in the hSR-BI/CLA-1 promoter abolished the ability of IFN alpha to suppress promoter activity. CONCLUSIONS: Together, these results indicate that the STAT1/STAT2 pathway participates in IFN alpha inhibition of hSR-BI/CLA-1 expression, and raise the possibility that lowering the expression of this gene may be of therapeutic value for treating HCV infections.

Possible involvement of protein phosphorylation in the wound-responsive expression of Arabidopsis plastid omega-3 fatty acid desaturase gene.

The plastid omega-3 fatty acid desaturase (FAD7) catalyzes the conversion of linoleic acid to linolenic acid. Wounding enhances the expression of the FAD7 gene in leaves and induces its expression in stems and roots. The wound-induced expression of the FAD7 promoter was investigated in transgenic tobacco plants carrying the -825 Arabidopsis FAD7 promoter::beta-glucuronidase (GUS) fusion gene. The protein kinase inhibitor, staurosporine, and the protein phosphatase inhibitor, calyculin A, suppressed the wound induction of the FAD7 gene in stems. A tobacco mitogen-activated protein kinase (WIPK) was rapidly activated upon wounding not only in leaves but also in stems and roots, indicating that WIPK probably mediates the wound signals in most vegetative organs. The FAD7 promoter::GUS fusion gene was introduced into the transgenic tobacco plants in which the wipk gene was expressed constitutively at a high level or into the transgenic plants in which the wipk gene was suppressed possibly due to the transgene-induced gene silencing. The wound-induced expression of the FAD7 gene in stems was enhanced in the former transgenic tobacco plants and suppressed in the latter plants. These results suggest that the wound activation of the FAD7 promoter depends on both protein phosphorylation and dephosphorylation events especially in stems, and also that WIPK is involved in such signaling cascades.

Wound-induced expression of the FAD7 gene is mediated by different regulatory domains of its promoter in leaves/stems and roots.

The FAD7 gene is expressed preferentially in the chlorophyllous tissues of unwounded plants. Wounding activates the expression of the FAD7 gene not only in chlorophyllous tissues, but also in nonchlorophyllous tissues of stems and roots. Our previous study suggested that wound-responsive transcriptional activation by the FAD7 promoter in leaves/stems and roots is brought about by a jasmonic acid (JA)-independent and JA-dependent signaling pathway, respectively. In this paper, we show that a specific region (from -259 to -198) in the FAD7 promoter is required for wound-activated expression of this gene in leaves and stems, while another region (from -521 to -363) is necessary not only for wound-activated but also for JA-responsive expression of this gene in roots. Thus, different regulatory regions of the FAD7 promoter mediate distinct wound-induced expression of this gene in leaves/stems and roots. Gel mobility shift assays revealed the wound-inducible DNA-binding activity to the -242/-223 region in both stem and leaf nuclear extracts. In fact, deletion of this region abolished wound response of the FAD7 promoter, suggesting the in vivo role of this site. Furthermore, we detected root nuclear factors interacting with the region from -433 to -363 of this promoter. Wounding and methyl jasmonate treatments induced differently these DNA-binding activities. These results suggest that different regulatory mechanisms mediate the wound-induced expression of the FAD7 gene in aerial and subterranean organs.

Wounding changes the spatial expression pattern of the arabidopsis plastid omega-3 fatty acid desaturase gene (FAD7) through different signal transduction pathways.

The Arabidopsis FAD7 gene encodes a plastid omega-3 fatty acid desaturase that catalyzes the desaturation of dienoic fatty acids in membrane lipids. The mRNA levels of the Arabidopsis FAD7 gene in rosette leaves rose rapidly after local wounding treatments. Wounding also induced the expression of the FAD7 gene in roots. To study wound-responsive expression of the FAD7 gene in further detail, we analyzed transgenic tobacco plants carrying the -825 Arabidopsis FAD7 promoter-beta-glucuronidase fusion gene. In unwounded transformants, FAD7 promoter activity was restricted to the tissues whose cells contained chloroplasts. Activation of the FAD7 promoter by local wounding treatments was more substantial in stems (29-fold) and roots (10-fold) of transgenic plants than it was in leaves (approximately two-fold). Significant induction by wounding was observed in the overall tissues of stems and included trichomes, the epidermis, cortex, vascular system, and the pith of the parenchyma. Strong promoter activity was found preferentially in the vascular tissues of wounded roots. These results indicate that wounding changes the spatial expression pattern of the FAD7 gene. Inhibitors of the octadecanoid pathway, salicylic acid and n-propyl gallate, strongly suppressed the wound activation of the FAD7 promoter in roots but not in leaves or stems. In unwounded plants, exogenously applied methyl jasmonate activated the FAD7 promoter in roots, whereas it repressed FAD7 promoter activity in leaves. Taken together, wound-responsive expression of the FAD7 gene in roots is thought to be mediated via the octadecanoid pathway, whereas in leaves, jasmonate-independent wound signals may induce the activation of the FAD7 gene. These observations indicate that wound-responsive expression of the FAD7 gene in aerial and subterranean parts of plants is brought about by way of different signal transduction pathways.

Different secretion profiles of atrial and brain natriuretic peptides after acute volume loading in patients with ischemic heart disease.

In order to clarify the different secretion profiles of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in response to acute hemodynamic change by volume expansion, we measured plasma ANP and BNP levels after intravenous isotonic saline infusion for 3 min at a rate of 3 ml/kg body weight/min in 15 patients with ischemic heart disease. Plasma ANP and BNP levels before the volume loading were 30.7 +/- 16.7 and 19.4 +/- 24.6 pg/ml, respectively. Five and 10 minutes after infusion, plasma ANP levels rose significantly to 43.5 +/- 20.7 and to 46.0 +/- 22.5 pg/ml, respectively (p < 0.01), and plasma BNP levels rose significantly to 27.3 +/- 30.8 and 24.8 +/- 23.2 pg/ ml, respectively (p < 0.01). The BNP/ANP ratio was not affected by volume loading. The maximum increments of plasma ANP level correlated significantly with those of the mean pulmonary capillary wedge pressure (mPCWP, r = 0.78, p < 0.01) or left ventricular end-diastolic pressure (LVEDP, r = 0.86, p < 0.01). However, there were no significant correlations between the maximum increments of plasma BNP levels and those of mPCWP or LVEDP. Plasma ANP level can be a useful parameter for atrial pressure even if the hemodynamic state change rapidly. However, in an early phase of ventricular overload BNP secretion is not increased sufficiently despite the raised LVEDP, and plasma BNP level may not always reflect ventricular hemodynamics.

cDNA cloning of a wounding-inducible gene encoding a plastid omega-3 fatty acid desaturase from tobacco.

A cDNA encoding the plastid omega-3 fatty acid desaturase was isolated from a tobacco (Nicotiana tabacum cv. SR1) leaf cDNA library. The amino terminal extension of the deduced amino acid sequence of this clone had a characteristic feature of the transit peptides of plastid-destined proteins. Northern analysis indicated that the mRNA corresponding to this cDNA was present in leaves, but was not detected in roots. Responses to wounding of the plastid and microsome omega-3 desaturase genes were investigated in tobacco leaves. The mRNA level of the plastid omega-3 desaturase gene increased to about 2-fold that of unwounded controls at 12 h after a wounding treatment. On the other hand, the mRNA level of the microsome omega-3 desaturase gene remained constant in the wounded leaves. Linolenic acid contents of major leaf polar lipids increased by wounding. These results indicate that wounding enhances the accumulation of the plastid omega-3 desaturase mRNA, and increases the conversion of linoleic acid to linolenic acid in leaf polar lipids.

Tissue-specific and light-responsive regulation of the promoter region of the Arabidopsis thaliana chloroplast omega-3 fatty acid desaturase gene (FAD7).

The Arabidopsis FAD7 gene encodes a chloroplast omega-3 fatty acid desaturase that catalyzes the desaturation of lipid-linked dienoic fatty acids (18:2 and 16:2). An 825 bp FAD7 promoter fragment upstream from the transcriptional start point contained several short sequences which were homologous to the cis-elements (box II, G-box, etc.) conserved in many light-responsive genes. We introduced the FAD7 promoter fused to the beta-glucuronidase (GUS) or the luciferase (LUC) reporter gene into tobacco plants. The -825 promoter sequence conferred tissue-specific and light-responsive expression to both these reporter genes in transgenic tobacco, indicating that these expressions of the FAD7 gene were regulated mainly at the transcriptional level. Histochemical GUS staining showed that the activity of the FAD7 promoter is restricted to the tissues with chloroplast-containing cells although the staining was noticeably absent in the chloroplast-containing cells associated with vascular systems. The 5' deletion experiments of the promoter revealed that the -362/-166 region, containing two putative box II sequences, was responsible for the tissue-specific and light-responsive expression of the FAD7 gene.

Inhibition of neutrophil superoxide generation by hypericin, an antiretroviral agent.

We previously reported that phorbol 12-myristate 13-acetate (PMA)-induced superoxide (O2.-) generation of neutrophils was inhibited by hypericin, a photosensitizing pigment found in St. Johnswort (herb Hypericin triquetrifolium Turra), via a mechanism involving protein kinase C (PKC). To obtain further insights into the mechanism of inhibition, the effects of hypericin on stimulation-dependent O2.- generation and related enzymes of neutrophils were investigated. Hypericin inhibited O2.- generation of neutrophils induced by PKC-dependent and -independent stimuli in a light- and concentration-dependent manner. Oxygen was required for the light-dependent inhibition by hypericin. NADPH oxidase activity in a cell-free system and TNF-alpha-induced tyrosyl phosphorylation of neutrophil proteins were also inhibited by hypericin in a concentration- and light-dependent manner. However, tyrosine kinase of p60src, an enzyme not bound to a membrane, was not inhibited either in the light or in the dark. Oxygen uptake of neutrophils by photosensitization with hypericin resulted in the formation of singlet oxygen (1O2), O2.-, and hydroxyl radical (.OH) and enhanced lipid peroxidation. The formation of 1O2 was inhibited by azide, a quencher of 1O2, but not by desferrioxamine (DSF), a ferric ion chelator. By contrast, both generation of .OH and lipid peroxidation were inhibited by DSF but not by azide. Furthermore, PMA-induced O2.- generation inhibited by hypericin partially recovered in the presence of azide but not DSF. These results suggested that the light-dependent inhibition of O2.- generation by hypericin might be due to inhibition of tyrosine kinase, PKC, and NADPH oxidase via an oxygen-dependent mechanism, possibly through both Type I and II photosensitization mechanisms.

Fatty Acid Desaturation during Chilling Acclimation Is One of the Factors Involved in Conferring Low-Temperature Tolerance to Young Tobacco Leaves.

The FAD7 gene, a gene for a chloroplast [omega]-3 fatty acid desaturase, is responsible for the trienoic fatty acid (TA) formation in leaf tissues. The TA content of the leaf tissue of the 25[deg]C-grown transgenic tobacco (Nicotiana tabacum cv SR1) plants, in which the FAD7 gene from Arabidopsis thaliana was overexpressed, increased uniformly by about 10%. Fatty acid unsaturation in all major leaf polar lipid species increased in the 25[deg]C-grown FAD7 transformants but was approximately the same between the control plants and the FAD7 transformants when grown at 15[deg]C. Therefore, the overexpression of the exogenous FAD7 gene leads to the same consequence in the tobacco plants as the low-temperature-induced TA production that may be catalyzed by an endogenous, temperature-regulated chloroplast [omega]-3 fatty acid desaturase. In the 25[deg]C-grown control plants, the chilling treatment caused symptoms of leaf chlorosis and suppression of leaf growth. The 25[deg]C-grown FAD7 transgenic plants conferred alleviation of these chilling-induced symptoms. A reductions of the chilling injury similar to that of the FAD7 transformants was also observed in the 15[deg]C-preincubated control plants. These results indicate that the increased TA production during chilling acclimation is one of the prerequisites for the normal leaf development at low, nonfreezing temperatures.

Enhanced secretion and impaired natriuretic action of atrial natriuretic peptide in response to hypertonic saline infusion in patients with essential hypertension.

To clarify the natriuretic action of endogenous atrial natriuretic peptide (ANP) in patients with essential hypertension (EHT), we examined the relationship between ANP release and urinary sodium excretion in response to hypertonic saline infusion. Plasma ANP levels increased from 13.3 +/- 2.0 pg/ml to 37.0 +/- 3.0 pg/ml in patients with EHT and from 9.2 +/- 1.5 pg/ml to 21.1 +/- 4.0 pg/ml in normal subjects after the infusion. The area under the curve (AUC) of plasma ANP response was significantly higher in patients with EHT than in normal subjects (P < 0.05). There was a significant positive correlation between AUC and urinary sodium excretion in both groups (P < 0.01). However, the ratio of urinary sodium excretion to AUC was significantly lower in patients with EHT than in normal subjects (P < 0.01). These results suggest that impaired natriuretic response to endogenous ANP is one of the factors responsible for the development of EHT and that enhanced secretion of ANP in response to hypertonic saline infusion is a compensatory mechanism to the impaired natriuretic action of ANP in patients with EHT.

[Comparison of buprenorphine and fentanyl for postoperative pain relief by continuous epidural infusion].

This study examined analgesic efficacy and adverse effects of buprenorphine and fentanyl for the postoperative pain relief by continuous epidural infusion. Fifty patients after upper or lower abdominal surgeries were assigned to two groups and buprenorphine and fentanyl were epidurally administered postoperatively. Buprenorphine (B) group received bolus injection of B 0.1mg + saline 8 ml and continuous infusion of B 0.8 mg+saline 92 ml (2 ml.h-1). Fentanyl group received bolus injection of F 0.1 mg+saline 6 ml and continuous infusion of F 0.6 mg+saline 84 ml (2 ml.h-1). There was no significant difference between the two groups in the analgesic efficacy, which became lower from 2 to 12 hours postoperatively. However, compared with buprenorphine group, the incidence of nausea or vomiting and dizziness was significantly less in the fentanyl group (11 vs. 4 cases and 7 vs. 1 cases). These results imply that the major site of action of epidurally administered fentanyl is the spinal cord. In contrast, analgesic effect of epidural buprenorphine appears to be enhanced by the supraspinal action. We conclude that fentanyl is superior to buprenorphine for postoperative pain relief by continuous epidural infusion.