Biomedical subjects

J K Lin

Publications and source records attributed to J K Lin.

At least 19 recordsLinked to original sources

PubMed2006

Increasing live donor kidney transplantation: a randomized controlled trial of a home-based educational intervention.

With the shortage of deceased donor kidneys and the superior clinical outcomes possible with live donor kidney transplantation (LDKT), more patients should seriously consider LDKT. However, little is known about how best to educate patients and their family members about LDKT. We evaluated the effectiveness of a home-based (HB) educational program in increasing LDKT. Patients were randomized to clinic-based (CB) education alone (CB, n = 69) or CB plus HB education (CB+HB, n = 63). Compared to CB, more patients in the CB+HB group had living donor inquiries (63.8% vs. 82.5%, p = 0.019) and evaluations (34.8% vs. 60.3%, p = 0.005) and LDKTs (30.4% vs. 52.4%, p = 0.013). Assignment to the CB+HB group, White race, more LDKT knowledge, higher willingness to discuss LDKT with others, and fewer LDKT concerns were predictors of having LDKT (p-values < 0.05). Both groups demonstrated an increase in LDKT knowledge after the CB education, but CB+HB led to an additional increase in LDKT knowledge (p < 0.0001) and in willingness to discuss LDKT with others (p < 0.0001), and a decrease in LDKT concerns (p < 0.0001). Results indicate that an HB outreach program is more effective in increasing LDKT rates than CB education alone.

Adult↗

PubMed2001

Suppression of Fas ligand expression on endothelial cells by arsenite through reactive oxygen species.

Chronic exposure to arsenite is associated with vascular disease, such as arteriosclerosis. However, the cellular mechanisms for vascular disease in response to arsenic are not well known. The present study has demonstrated that arsenite not arsenate decreased the Fas ligand (FasL) expression on ECV304 cells through reactive oxygen species. Incubation of ECV304 cells with arsenite decreased the FasL expression and increased the intracellular peroxide levels. In addition, hydrogen peroxide was found to suppress FasL expression in a dose-dependent manner. The antioxidant, N-acetyl-cysteine, blocked the suppression of FasL expression in response to arsenite. These data suggested that arsenite initiates endothelium dysfunction, at least partly, by suppressing the FasL expression through activating reactive oxygen species sensitive endothelial cell signaling.

Acetylcysteine↗

PubMed2001

Suppression of inducible cyclooxygenase and nitric oxide synthase through activation of peroxisome proliferator-activated receptor-gamma by flavonoids in mouse macrophages.

Peroxisome proliferator-activated receptor (PPAR)gamma transcription factor has been implicated in anti-inflammatory response. Of the compounds tested, apigenin, chrysin, and kaempferol significantly stimulated PPAR gamma transcriptional activity in a transient reporter assay. In addition, these three flavonoids strongly enhanced the inhibition of inducible cyclooxygenase and inducible nitric oxide synthase promoter activities in lipopolysaccharide-activated macrophages which contain the PPAR gamma expression plasmids. However, these three flavonoids exhibited weak PPAR gamma agonist activities in an in vitro competitive binding assay. Limited protease digestion of PPAR gamma suggested these three flavonoids produced a conformational change in PPAR gamma and the conformation differs in the receptor bound to BRL49653 versus these three flavonoids. These results suggested that these three flavonoids might act as allosteric effectors and were able to bind to PPAR gamma and activate it, but its binding site might be different from the natural ligand BRL49653.

Animals↗

PubMed2001

Oxidative stress and c-Jun-amino-terminal kinase activation involved in apoptosis of primary astrocytes induced by disulfiram-Cu(2+) complex.

Disulfiram is frequently used in the treatment of alcoholism. In this study, we found that CuCl(2) (1-10 microM), but not other metal ions (Fe(2+), Zn(2+), Pb(2+)), markedly potentiated disulfiram-induced cytotoxicity by 440-fold in primary astrocytes. Thus, the molecular mechanisms of the cytotoxic effects induced by the disulfiram-Cu(2+) complex were explored. The changes in morphology (nuclear condensation and apoptotic body formation) and hypodiploidy of DNA suggested that the disulfiram-Cu(2+) complex induced an apoptotic process. Our studies of the death-signaling pathway reveal that decreased mitochondrial membrane potential, increased free radical production, and depletion of non-protein-thiols (glutathione) were involved. The disulfiram-Cu(2+) complex activated c-Jun-amino-terminal kinase (JNK) and caspase-3 followed by poly (ADP-ribose) polymerase degradation in a time-dependent manner. Moreover, the cellular Cu content was markedly increased and the copper chelator bathocuproine disulfonate abolished all of these cellular events, suggesting that Cu(2+) is essential for death signaling. The antioxidants N-acetylcysteine and vitamin C also inhibited the cytotoxic effect. Thus, we conclude that the disulfiram-Cu(2+) complex induces apoptosis and perhaps necrosis at a late stage mediated by oxidative stress followed by sequential activation of JNK, caspase-3 and poly (ADP-ribose) polymerase degradation. These findings imply that the axonal degeneration and neurotoxicity observed after the chronic administration of disulfiram are perhaps, at least in part, due to the cytotoxic effect of the disulfiram-Cu(2+) complex formed endogenously.

Animals↗

PubMed2001

Griseofulvin potentiates antitumorigenesis effects of nocodazole through induction of apoptosis and G2/M cell cycle arrest in human colorectal cancer cells.

In this study, we demonstrate that apoptosis and G2/M cell cycle arrest were easily induced by treatment with the oral-antifungal agent, griseofulvin (GF). The mechanisms of GF-induced G2/M arrest were characterized as (a) induction of abnormal mitotic spindle formation, (b) elevation of cyclin B1/cdc2 kinase activity and (c) down-regulation of myt-1 protein expression. On the other hand, caspase 3 activation, Bcl-2 hyperphosphorylation and inhibition of the normal function of Bcl-2 associated with Bax were demonstrated to be the mechanisms of GF-induced apoptosis. DNA fragmentation and flow cytometry analyses demonstrated that combined treatment of GF with the cancer chemotherapeutic agent, nocodazole (ND), strongly potentiates the apoptotic effect and arrest of the G2/M cell cycle in 5 types of human cancer cells, but not in normal human keratinocytes (#76 KhGH). The combined treatment of GF and ND triggered the polymerization of purified tubulin in HT 29 but not in #76 KhGH cells. To further confirm these observations, the therapeutic efficacy was further examined in vivo by treating athymic mice bearing COLO 205 tumor xenografts, with GF (50 mg/kg), ND (5 mg/kg) or GF + ND. Combined treatment of GF and ND significantly enhanced the effect of ND, and led to cessation of tumor growth. These results suggest that chemotherapeutic agents (such as ND) administered in the presence of GF might provide a novel therapy for colorectal cancer.

Animals↗

PubMed2001

Carcinoembryonic antigen in monitoring of response to systemic chemotherapy in patients with metastatic colorectal cancer.

The response to chemotherapy of solid tumors is generally assessed by measuring tumors visualized by imaging. However, the response assessment based on imaging is not always feasible because patients often have disease not measurable by imaging, such as diffuse peritoneal dissemination. We evaluated the correlation between the change on imaging and change in CEA levels for assessing chemotherapeutic response of patients with metastatic colorectal cancer. Between July 1993 and August 1999 we retrospectively examined 136 patients with metastatic colorectal carcinoma, all of whom had measurable lesions. Forty patients received oral tegafur-uracil (300 mg/m2/day) plus folinic acid (60 mg/day) for 4 weeks, repeated every 5 weeks, as the firstline treatment. Another 96 patients received either a weekly intravenous bolus injection of 5-fluorouracil (400 mg/m2) plus folinic acid (20 mg/m2), or an intravenous bolus injection of 5-fluorouracil (425 mg/m2) plus folinic acid (20 mg/m2) for 5 consecutive days every month. Responders, based on CEA assessment, were defined as those with a greater than 50% drop in CEA level for more than 4 weeks. The pretreatment CEA levels were elevated beyond the normal cutoff value in 110 (81%) patients. A response rate of 18.4% (95% CI, 11.9-24.9%), including 8 complete remissions and 17 partial remissions, was achieved according to imaging studies. The response rate assessed by CEA was 25% (34/136). Sixteen responders (47%) based on CEA had no remission on imaging. The sensitivity of change in CEA levels in the prediction of true responders and progressive diseases on imaging were 72% and 81%, respectively. In terms of the positive predictive value, change in CEA levels in the prediction of true responders and progressive disease on imaging were 53% and 85%, respectively. Patients with remarkable falls on CEA levels survived significantly longer than nonresponders (P < 0.001, log-rank test). At follow-up of 48 months the median survival for responders and nonresponders assessed by CEA was 28 months and 13 months, respectively. These data suggest that measurement of CEA levels might be helpful in monitoring chemotherapeutic response when imaging study is unsuitable for assessing the response in clinical practice. Furthermore, measurement of CEA levels may be helpful in determining the prognosis of patients with metastatic colorectal cancer receiving chemotherapy.

Adult↗

PubMed2001

Gasless laparoscopy-assisted colorectal surgery.

BACKGROUND: Laparoscopy has gained wide acceptance as a treatment modality in a variety of colonic and rectal disorders. Currently, most laparoscopic procedures are performed using a carbon dioxide (CO2) pneumoperitoneum, which can lead to cardiopulmonary loading and subsequent complications. The object of this study was to assess the feasibility of gasless laparoscopy-assisted colorectal surgery (GLACS) as an alternative method. METHODS: Patients with benign colonic lesions were enrolled in the study. The operative field was exposed with a subcutaneous wire lifting system. A small incision, ~5 cm in length, was made early in the operation. The surgeon operated through the trocar ports and this incision using both laparoscopic and conventional instruments. The cardiopulmonary responses of the patients were monitored continuously during the operation. RESULTS: Fifteen consecutive patients underwent GLACS. In two patients (13.3%), conversion to open surgery was necessary. The exposure and ease of the procedure were acceptable. However, when the patients were stratified into hemicolectomy and sigmoidectomy groups, GLACS scored more favorably in the sigmoidectomy group. There were no operative deaths. One minor complication developed postoperatively. All of the patients recovered uneventfully, with return of bowel function in 2.8 +/- 0.1 days. The mean postoperative hospital stay was 6.4 +/- 0.4 days. The cardiac and pulmonary status of the patients remained stable during the operation. CONCLUSION: Gasless laparoscopy-assisted colorectal surgery is technically feasible; thus, it provides an alternative means for the performance of minimal-access surgery.

Aged↗

PubMed2001

Induction of apoptosis by garcinol and curcumin through cytochrome c release and activation of caspases in human leukemia HL-60 cells.

Garcinol, a polyisoprenylated benzophenone, was purified from Garcinia indica fruit rind. The effects of garcinol and curcumin on cell viability in human leukemia HL-60 cells were investigated. Garcinol and curcumin displayed strong growth inhibitory effects against human leukemia HL-60 cells, with estimated IC(50) values of 9.42 and 19.5 microM, respectively. Garcinol was able to induce apoptosis in a concentration- and time-dependent manner; however, curcumin was less effective. Treatment with garcinol caused induction of caspase-3/CPP32 activity in a dose- and time-dependent manner, but not caspase-1 activity, and induced the degradation of poly(ADP-ribose) polymerase (PARP). Pretreatment with caspase-3 inhibitor inhibited garcinol-induced DNA fragmentation. Treatment with garcinol (20 microM) caused a rapid loss of mitochondrial transmembrane potential, release of mitochondrial cytochrome c into cytosol, and subsequent induction of procaspase-9 processing. The cleavage of D4-GDI, an abundant hematopoietic cell GDP dissociation inhibitor for the Ras-related Rho family GTPases, occurred simultaneously with the activation of caspase-3 but preceded DNA fragmentation and the morphological changes associated with apoptotic cell death. Of these, Bcl-2, Bad, and Bax were studied. The level of expression of Bcl-2 slightly decreased, while the levels of Bad and Bax were dramatically increased in cells treated with garcinol. These results indicate that garcinol allows caspase-activated deoxyribonuclease to enter the nucleus and degrade chromosomal DNA and induces DFF-45 (DNA fragmentation factor) degradation. It is suggested that garcinol-induced apoptosis is triggered by the release of cytochrome c into the cytosol, procaspase-9 processing, activation of caspase-3 and caspase-2, degradation of PARP, and DNA fragmentation caused by the caspase-activated deoxyribonuclease through the digestion of DFF-45. The induction of apoptosis by garcinol may provide a pivotal mechanism for its cancer chemopreventive action.

Antineoplastic Agents↗

PubMed2001

Alternative activation of extracellular signal-regulated protein kinases in curcumin and arsenite-induced HSP70 gene expression in human colorectal carcinoma cells.

We have investigated the regulation mechanism of chemical stress-induced HSP70 gene expression in human colorectal carcinoma cells (COLO205 and HT29). Our data show that chemical treatments including sodium arsenite and curcumin, induced significant synthesis of HSP70 and its mRNA. The induced HSP70 gene expression appears to be increased at the transcriptional level. The increase in HSP70 gene expression by both chemicals is associated with an increase in HSF binding to HSE and induction of HSF1 di- or trimerization. Phosphorylation and activation of extracellular signal-regulated proteins (ERK1/2) were detected in sodium arsenite-treated COLO205 and HT29 cells, and the free radical scavenger N-acetyl-L-cysteine (NAC) was able to inhibit this ERK1/2 activation and HSP70 gene expression. MAPK blockade by the specific MEK1 inhibitor (PD98059) decreased the ability of sodium arsenite to increase HSP70 gene expression in a dose-dependent manner along with dephosphorylation of ERK1/2 proteins. In contrast to arsenite treatment, activation of ERK1/2 was not detected in curcumin-treated colorectal carcinoma cells, and NAC and PD98059 did not show any inhibitory effect on HSP70 gene expression induced by curcumin. Overexpression of a dominant negative mutant of mitogen-activated protein kinase kinase kinase 1 (MEKK1-DN) prevents arsenite-induced ERK1/2 phosphorylation and HSP70 protein synthesis. These results indicated that the ERK signaling pathway can participate in HSP70 gene expression induced by the prooxidant sodium arsenite, but not by the antioxidant curcumin.

Acetylcysteine↗

PubMed2001

Mechanisms of cancer chemoprevention by curcumin.

Curcumin is a major component of the Curcuma species, which is commonly used as a yellow coloring and flavoring agent in foods. Curcumin has shown anti-carcinogenic activity in animals as indicated by its ability to block colon tumor initiation by azoxymethane and skin tumor promotion induced by phorbol ester TPA. Recently, curcumin has been considered by oncologists as a potential third generation cancer chemopreventive agent, and clinical trials using it have been carried out in several laboratories. Curcumin possesses anti-inflammatory activity and is a potent inhibitor of reactive oxygen-generating enzymes, such as lipoxygenase/cyclooxygenase, xanthine dehydrogenase/oxidase and inducible nitric oxide synthase. Curcumin is also a potent inhibitor of protein kinase C, EGF-receptor tyrosine kinase and IkappaB kinase. In addition, curcumin inhibits the activation of NFkappaB and the expression of c-jun, c-fos, c-myc and iNOS. It is proposed that curcumin may suppress tumor promotion by blocking signal transduction pathways in the target cells. Curcumin was first biotransformed to dihydrocurcumin and tetrahydrocurcumin, and these compounds were subsequently convened into monoglucuronide conjugates. The experimental results suggest that curcumin-glucuronide, dihydrocurcumin-glucuronide, tetrahydrocurcumin-glucuronide and tetrahydrocurcumin are major metabolites of curcumin in mice.

Animals↗

PubMed2001

Preservation of anal sphincter function after hemorrhoidectomy under local anesthesia.

BACKGROUND: This is a prospective study designed to confirm a simple, effective method of hemorrhoidectomy that can be accomplished by simple local anesthesia with good preservation of anal sphincter function both clinically and manometrically. METHODS: Eighty consecutive patients with prolapsed mixed hemorrhoids were operated with standard closed hemorrhoidectomy under local anesthesia. Pre- and post-operative assessments of anal continent function and anorectal manometry were performed. Maximal basal pressure (MBP), maximal contraction pressure (MCP), squeeze pressure (SP), rectoanal inhibitory reflex (RAIR), functional length (FL), volumes at the first sensation of rectal fullness (V sense), urge of defecation (V urge), and intolerance (V max.) were measured. The pre-and post-operative data were compared with two tailed paired Student t test. Statistical significance was considered asp-value less than 0.05. RESULTS: All 80 patients were completely followed up and studied. No patient had any degree of anal incontinence before and 6 months after hemorrhoidectomy. There was significant change in V sense and V urge after operation. However, MBP, MCP, SP, FL, RAIR, and V max. remained unchanged. CONCLUSIONS: Standard closed hemorrhoidectomy supplemented with appropriate submucosal dissection under adequate local anesthesia is simple and effective for the treatment of prolapsed hemorrhoids. The function of anal sphincter, both clinically and manometrically, can be well preserved.

Adult↗

PubMed2001

Colorectal cancer in patients 20 years old or less in Taiwan.

BACKGROUND: Colorectal cancer (CRC) is predominantly a disease of the elderly population, but it sometimes occurs in young patients. The diagnosis of CRC in youngsters is often overlooked by physicians or presentation may be delayed. METHODS: With assistance from the cancer registry center of Taipei Veterans General Hospital, we collected data on all types of colorectal malignancy, including carcinoma, adenocarcinoma, or lymphoma in patients aged 20 or younger. All available medical charts and pathologic specimens were reviewed in detail. RESULTS: A total of 28 cases were analyzed. The leading presenting symptom was abdominal pain (92%). The locations of the primary tumors were evenly distributed, and the major histologic type was predominantly adenocarcinoma. However, the proportion of mucinous adenocarcinoma was higher than that in the older population. Most of the cases were advanced (11 tumors were classified as Dukes stage C and another 11 as Dukes stage D). The overall 5-year survival rate was 21%. CONCLUSIONS: Despite the rarity of CRC during the first two decades of life, physicians need to be aware of the possibility and to evaluate suggestive signs and symptoms by colonoscopy or barium enema. Family history of CRC, inflammatory bowel disease, previous polyps, or familial polyposis did not play a crucial role in this group of young patients.

Abdominal Pain↗

PubMed2000

Ketoconazole induces G0/G1 arrest in human colorectal and hepatocellular carcinoma cell lines.

Ketoconazole is an oral-antifungal agent that has been used worldwide in the treatment of some hormone-dependent human cancer. In this study, we demonstrated that ketoconazole (20 microM) induced various types of human cancer cell growth arrest in the G0/G1 phase. Our results revealed that ketoconazole-induced growth arrest was more profound in COLO 205 and Hep G2 (with wild-type p53) than in HT 29 (p53 His(273) mutant) and Hep 3B (with deleted p53) cells. The protein levels of p53, p21/Cip1, and p27/Kip1 were significantly elevated by ketoconazole (10 microM) treatment in COLO 205 but not in HT 29 cells. The ketoconazole-induced G0/G1 phase arrest in COLO 205 cells was attenuated by p53-specific antisense oligodeoxynucleotides (20 microM) treatment. These results suggested that the p53-associated signaling pathway is involved in the regulation of ketoconazole-induced cancer cell growth arrest. By Western blot analysis, we demonstrated that cyclin D3 and CDK4 protein but not other G0/G1 phase regulatory protein levels were decreased by ketoconazole-treatment in both COLO 205 and HT 29 cells. Our study provides the basis of molecular mechanisms for ketoconazole in growth inhibition of human cancer cells and such results may have significant applications for cancer chemotherapy.

Animals↗

PubMed2000

Comparative studies on the suppression of nitric oxide synthase by curcumin and its hydrogenated metabolites through down-regulation of IkappaB kinase and NFkappaB activation in macrophages.

Nitric oxide (NO) plays an important role in inflammation and in the multiple stages of carcinogenesis. In this study, we investigated the inhibitory effects of curcumin and its metabolites, tetrahydrocurcumin, hexahydrocurcumin, and octahydrocurcumin, on the induction of NO synthase (NOS) in RAW 264.7 cells activated with lipopolysaccharide (LPS). Western blotting and northern blotting analyses demonstrated that curcumin strongly reduced 130-kDa protein and 4.5-kb mRNA levels of iNOS in LPS-activated macrophages compared with its metabolites, tetrahydrocurcumin, hexahydrocurcumin, and octahydrocurcumin. Moreover, electrophoretic mobility shift assay (EMSA) experiments indicated that curcumin blocked the LPS-induced binding of nuclear factor-kappaB (NFkappaB), a transcription factor necessary for iNOS induction to its (32)P-labeled double-stranded oligonucleotide probe. The inhibition of NFkappaB activation occurred through the prevention of inhibitor kappaB (IkappaB) degradation. Transient transfection experiments also showed that curcumin inhibited NFkappaB-dependent transcriptional activity. Curcumin blocked the disappearance of inhibitory kappaBalpha (IkappaBalpha) and p65 from the cytosolic fraction, and inhibited the phosphorylation of IkappaBalpha. Furthermore, we showed that curcumin could inhibit the IkappaB kinase 1 (IKK1) and IkappaB kinase 2 (IKK2) activities induced by LPS, but tetrahydrocurcumin, hexahydrocurcumin, and octahydrocurcumin were less active. These results suggest that curcumin may exert its anti-inflammatory and anti-carcinogenic properties by suppressing the activation of NFkappaB through inhibition of IKK activity.

Animals↗

PubMed2000

Activation of transcription factors of nuclear factor kappa B, activator protein-1 and octamer factors in hyperalgesia.

Involvement of c-fos and neuronal nitric oxide synthase (nNOS) in the hyperalgesia induced by complete Freund adjuvant (CFA) has been reported. In this paper, we attempted to investigate whether the transcription factors regulating the gene expression of c-fos and nNOS, including activator protein-1 (AP-1), nuclear factor kappa B (NF-kappa B), and octamer factors (Oct), are activated by CFA during the development of hyperalgesia. The electrophoretic mobility shift assay (EMSA) was used to determine whether there were changes in the transcription factors in the lumbar spinal cord of adult rats following subcutaneous injection of CFA in one hindpaw of the rats. Maximum binding of AP-1, NF-kappa B and Oct was found at 0.5, 1 and 2 h after CFA injection, respectively. These findings suggest that the activation of these transcription factors is pivotal for the expression of c-Fos and nNOS proteins, which reached a peak at 3 and 48 h after CFA injection, respectively. The behavioral testing of hyperalgesia demonstrated that CFA reduced the thresholds for mechanical and thermal algesia, reaching a minimum at 6 h. The thresholds had only partially recovered after 96 h. Based on these findings, we conclude that AP-1, NF-kappa B and Oct are crucial for the expression of c-Fos proteins at an early stage (at 3 h) and for the expression of nNOS at a late stage of hyperalgesia (48 h post-injection) induced by CFA.

Animals↗

PubMed2000

Nitration and hydroxylation of aromatic amino acid and guanine by the air pollutant peroxyacetyl nitrate.

Peroxyacetyl nitrate (PAN) is a common gaseous photochemical compound in polluted air and cigarette smog. The toxicity of PAN has been found to depend on three pathways: (1) its oxidizing property that mimics peroxide or peroxynitrite; (2) its nitrating and hydroxylating properties similar to peroxynitrite; and (3) its acetylating property like acetic anhydride. The present investigations were intended to focus on the reactions of PAN with aromatic amino acids and guanine. When PAN interacted with tyrosine and guanine the major products were 3-nitrotyrosine, 3, 5-dinitrotyrosine, 8-hydroxyguanine and 8-nitroguanine. These compounds have been used as indicators for the presence of peroxynitrite in previous studies. When PAN interacted with phenylalanine, the products were 3-nitrotyrosine, 4-nitrophenylalanine, p-tyrosine, o-tyrosine and m-tyrosine. 5-Hydroxytryptophan is produced from the reaction of PAN with tryptophan. Furthermore, the formation of nitrated tyrosines was also found in the PAN-treated HL-60 cells. A high yield of dityrosine was formed when PAN and peroxynitrite were reacted with tyrosine, probably through free radical oxidation. We also found that peroxynitrite and PAN are similar in their oxidizing activity. From these findings, we suggest that peroxynitrite may be considered as the reactive intermediate of PAN.

Air Pollutants↗

PubMed2000

In vitro relaxation of rabbit and human internal anal sphincter by rutaecarpine, an alkaloid isolated from Evodia rutaecarpa.

Rutaecarpine, a compound extracted from the Chinese medicinal herb Evodia rutaecarpa, has been shown to possess relaxing action on vascular smooth muscle from rat thoracic aorta. The internal anal sphincter is a specialized smooth muscle regulating important anorectal physiology. To investigate the effect and underlying mechanisms of rutaecarpine on internal anal sphincter, muscle strips from rabbit internal anal sphincter were used. The results showed that rutaecarpine (1 x 10(-10) M to 1 x 10(-4) M) produced a concentration-dependent muscular relaxation effect in our preparations, which were precontracted with acetylcholine. This muscular relaxation effect was not affected by treatment with L-N(G)-nitro-arginine methyl ester (a nitric oxide synthase inhibitor), methylene blue (a guanylate cyclase inhibitor), N-ethylmaleimide (an adenylate cyclase inhibitor), or by removal of the mucosa and submucosa tissue. Pretreatment with nifedipine (a calcium channel blocker) or extracellular Ca+2 removal by ethylenediaminetetraacetic acid (EDTA) greatly attenuated the relaxation effect, suggesting that calcium ion might be involved. In experiments using strips from human internal anal sphincter, an even more prominent relaxation effect was shown. It is thus concluded that rutaecarpine caused relaxation on internal anal sphincter from rabbits and human subjects. The relaxation action was not related to NO-cGMP pathway, instead calcium ion might play an important role and shed insight into clinical implications for those anorectal disorders with hyperactive anal tone.

Acetylcholine↗

PubMed2000

Suppression of lipopolysaccharide-induced nuclear factor-kappaB activity by theaflavin-3,3'-digallate from black tea and other polyphenols through down-regulation of IkappaB kinase activity in macrophages.

We investigated the inhibition of IkappaB kinase (IKK) activity in lipopolysaccharide (LPS)-activated murine macrophages (RAW 264.7 cell line) by various polyphenols including (-)-epigallocatechin-3-gallate, theaflavin, a mixture of theaflavin-3 gallate and theaflavin-3'-gallate, theaflavin-3,3'-digallate (TF-3), pyrocyanidin B-3, casuarinin, geraniin, and penta-O-galloyl-beta-D-glucose (5GG). TF-3 inhibited IKK activity in activated macrophages more strongly than did the other polyphenols. TF-3 strongly inhibited both IKK1 and IKK2 activity and prevented the degradation of IkappaBalpha and IkappaBbeta in activated macrophage cells. The results suggested that the inhibition of IKK activity by TF-3 could occur by a direct effect on IKKs or on upstream events in the signal transduction pathway. Furthermore, geraniin, 5GG, and TF-3 all blocked phosphorylation of IKB from the cytosolic fraction, inhibited nuclear factor-kappaB (NFkappaB) activity, and inhibited increases in inducible nitric oxide synthase levels in activated macrophages. These results suggest that TF-3 may exert its anti-inflammatory and cancer chemopreventive actions by suppressing the activation of NFkappaB through inhibition of IKK activity.

Animals↗