The E3L gene of vaccinia virus encodes an inhibitor of the interferon-induced, double-stranded RNA-dependent protein kinase

A vaccinia virus-encoded double-stranded RNA-binding protein, p25, has been previously implicated in inhibition of the interferon-induced, double-stranded RNA-activated protein kinase. In this study, we have identified the vaccinia viral gene (WR strain) that encodes p25. Amino acid sequence analysis of a chymotryptic fragment of p25 revealed a close match to the vaccinia virus (Copenhagen strain) E3L gene. The WR strain E3L gene was cloned and expressed either in COS-1 cells or in rabbit reticulocyte lysates in vitro. A M(r) 25,000 polypeptide that could bind to poly(rI).poly(rC)-agarose and that reacted with p25-specific antiserum was produced in each case. In addition, COS cells expressing E3L gene products inhibited activation of the double-stranded RNA-activated protein kinase in extracts from interferon-treated cells. Removal of E3L-encoded products by adsorption with anti-p25 antiserum resulted in loss of kinase inhibitory activity. These results demonstrate that the vaccinia virus E3L gene encodes p25 and that the products of the E3L gene have kinase inhibitory activity. Comparison of the deduced amino acid sequence of the E3L gene products with the protein sequence data base revealed a region closely related to the human interferon-induced, double-stranded RNA-activated protein kinase.

Transformation of chicken cells by the gene encoding the catalytic subunit of PI 3-kinase

The avian sarcoma virus 16 (ASV 16) is a retrovirus that induces hemangiosarcomas in chickens. Analysis of the ASV 16 genome revealed that it encodes an oncogene that is derived from the cellular gene for the catalytic subunit of phosphoinositide 3-kinase (PI 3-kinase). The gene is referred to as v-p3k, and like its cellular counterpart c-p3k, it is a potent transforming gene in cultured chicken embryo fibroblasts (CEFs). The products of the viral and cellular p3k genes have PI 3-kinase activity. CEFs transformed with either gene showed elevated levels of phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate and activation of Akt kinase.

The E3L and K3L vaccinia virus gene products stimulate translation through inhibition of the double-stranded RNA-dependent protein kinase by different mechanisms

Vaccinia virus has evolved multiple mechanisms to counteract the interferon-induced antiviral host cell response. Recently, two vaccinia virus gene products were shown to interfere with the activity of the double-stranded RNA-dependent protein kinase (PKR): the K3L gene product and the E3L gene product. We have evaluated the efficiency by which these gene products inhibit PKR and whether they act in a synergistic manner. The effects of the two vaccinia virus gene products were compared in an in vivo system in which translation of a reporter gene (dihydrofolate reductase or eukaryotic translation initiation factor 2 alpha [eIF-2 alpha]) was inhibited because of the localized activation of PKR. In this system, the E3L gene product, and to a lesser extent the K3L gene product, potentiated translation of the reporter gene and inhibited eIF-2 alpha phosphorylation. Analysis in vitro demonstrated that the E3L gene product inhibited PKR approximately 50- to 100-fold more efficiently than the K3L gene product. However, further studies demonstrated that the mechanism of action of these two inhibitors was different. Whereas the E3L inhibitor interfered with the binding of the kinase to double-stranded RNA, the K3L inhibitor did not. We propose that the K3L inhibitor acts through its homology to eIF-2 alpha to interfere with the interaction of eIF-2 alpha with PKR. The two inhibitors did not display a synergistic effect on translation or eIF-2 alpha phosphorylation. In addition, neither K3L nor E3L expression detectably altered cellular protein synthesis.

Effects of naturally occurring prenylated flavonoids on enzymes metabolizing arachidonic acid: cyclooxygenases and lipoxygenases

Prenylated flavonoids are chemical entities having an isoprenyl, a geranyl, a 1,1-dimethylallyl, and/or a lavandulyl moiety as part of their flavonoid backbone structure. In this study, the effects of 19 naturally occurring prenylated flavonoids, isolated from medicinal plants, on cyclooxygenase (COX)-1 and COX-2 and on 5-lipoxygenase (5-LOX) and 12-LOX were investigated using [14C]arachidonic acid as a substrate. The homogenates of bovine platelets and polymorphonuclear leukocytes were used as COX-1, 12-LOX, and 5-LOX enzyme sources; the homogenate of aspirin-pretreated lipopolysaccharide-induced RAW 264.7 cells was used for the COX-2 enzyme source. Among the 19 prenylated flavonoids, morusin, kuwanon C, sanggenon B, sanggenon D and kazinol B inhibited COX-2 activity (ic(50) = 73-100 microM), but the potencies were far less than that of NS-398 (ic(50) = 2.9 microM). In contrast, many prenylated flavonoids, such as kuraridin, kuwanon C and sophoraisoflavanone A, inhibited COX-1 activity. Of the COX-1 inhibiting prenylated flavonoids, kuraridin, kurarinone, and sophoraflavanone G, all having a C-8 lavandulyl moiety, showed potent activity (ic(50) = 0.1 to 1 microM) comparable to that of indomethacin (ic(50) = 0.7 microM). Most of the prenylated flavonoids tested inhibited 5-LOX activity with ic(50) values ranging from 0.09 to 100 microM. Of these, only kuwanon C, papyriflavonol A and sophoraflavanone G showed inhibitory activity against 12-LOX at low concentration ranges (ic(50) = 19-69 microM) comparable to that of NDGA (ic(50) = 2.6 microM). Our results suggest that the position and the nature of the prenyl substitution greatly influence in vitro biological activities of these molecules.

TAR RNA-binding protein is an inhibitor of the interferon-induced protein kinase PKR

A cDNA encoding a double-stranded-RNA (dsRNA)-binding protein was isolated by screening a HeLa cell cDNA expression library for proteins that bind the HIV-1 Rev-responsive-element RNA. The cDNA encoded a protein that was identical to TRBP, the previously reported cellular protein that binds the transactivation response element (TAR) RNA of human immunodeficiency virus type 1. TRBP inhibited phosphorylation of the interferon-induced ribosome-associated protein kinase PKR and of the eukaryotic translation initiation factor eIF-2 alpha in a transient-expression system in which the translation of a reporter gene was inhibited by the localized activation of PKR. TRBP expression in HeLa cells complemented the growth and protein-synthesis defect of a vaccinia virus mutant lacking the expression of the dsRNA-binding protein E3L. These results implicate TRBP as a cellular regulatory protein that binds RNAs containing specific secondary structure(s) to mediate the inhibition of PKR activation and stimulate translation in a localized manner.

Purification and characterization of extracellular phospholipase A2 from human synovial fluid in rheumatoid arthritis

Extracellular phospholipase A2 was purified about 1.7 X 10(5) fold to near homogeneity from human synovial fluid of rheumatoid arthritis by sequential use of column chromatographies on heparin-Sepharose, butyl-Toyopearl, and reversed-phase HPLC. The final preparation showed a single band on SDS-polyacrylamide gel electrophoresis, and its molecular mass was estimated to be approximately 13,700 daltons. The purified enzyme had a pH optimum of 9.0 and required Ca2+ for maximum activity. It hydrolyzed phosphatidyl-ethanolamine more effectively than phosphatidylserine and phosphatidylcholine. These properties were similar to those of an extracellular phospholipase A2 detected in the peritoneal cavity of caseinate-treated rats.

Identification of a conserved motif that is necessary for binding of the vaccinia virus E3L gene products to double-stranded RNA

The E3L gene of vaccinia virus encodes the double-stranded (ds) RNA binding proteins p20 and p25 that exhibit inhibitory activity for the IFN-induced, P1/elF-2 alpha protein kinase. A region in the E3L encoded proteins (residues 156-180) shares a high degree of similarity with several proteins that bind double-helical RNA including the P1/elF-1 alpha kinase, bacterial and yeast RNase III, and a human transactivator response element/Rev response element binding protein. In this study, mutants of E3L proteins were constructed in order to determine the region of the proteins required for dsRNA binding and kinase inhibitory activity. Our data indicate that both the region necessary for dsRNA binding and for kinase inhibitory activity are located at the carboxyl terminus of the protein. The E3L proteins with 7 amino acids deleted from the carboxyl terminus (184-190) could bind to dsRNA, but with lower affinity than could the full-length protein. This protein did not detectably inhibit kinase in vitro. Deletion of 26 amino acids from the carboxyl terminus of the E3L proteins (165-190) abolished dsRNA binding activity and kinase inhibitory activity. In addition, mutations at amino acid 164, 167, or 174 severely inhibited binding to dsRNA. On the other hand, deletion of 83 amino acids from the amino terminus did not affect the proteins' ability to bind dsRNA or inhibit kinase. These results suggest that a region of sequence between amino acids 164 and 183 is necessary for E3L proteins' dsRNA binding activity. This region lies within the homologous domain that the E3L proteins share with other dsRNA binding proteins.

A new class of COX-2 inhibitor, rutaecarpine from Evodia rutaecarpa

OBJECTIVE AND DESIGN

We investigated the effect of a new class of COX-2 inhibitor, rutaecarpine, on the production of PGD2 in bone marrow derived mast cells (BMMC) and PGE2 in COX-2 transfected HEK293 cells. Inflammation was induced by lambda-carrageenan in male Splague-Dawley (SD) rats.

MATERIAL

Rutaecarpine (8,13-Dihydroindolo[2',3':3,4]pyridol[2,1-b]quinazolin -5(7H)-one) was isolated from the fruits of Evodia rutaecarpa. BMMC were cultured with WEHI-3 conditioned medium. c-Kit ligand and IL-10 were obtained by their expression in baculovirus.

METHODS

The generation of PGD2 and PGE2 were determined by their assay kit. COX-1 and COX-2 protein and mRNA expression was determined by BMMC in the presence of KL, LPS and IL-10.

TREATMENT

Rutaecarpine and indomethacin dissolved in 0.1% carboxymethyl cellulose was administered intraperitoneally and, 1 h later, lambda-carrageenan solution was injected to right hind paw of rats. Paw volumes were measured using plethysmometer 5 h after lambda-carrageenan injection.

RESULTS

Rutaecarpine inhibited COX-2 and COX-1 dependent phases of PGD2 generation in BMMC in a concentration-dependent manner with an IC50 of 0.28 microM and 8.7 microM, respectively. It inhibited COX-2-dependent conversion of exogenous arachidonic acid to PGE2 in a dose-dependent manner by the COX-2-transfected HEK293 cells. However, rutaecarpine inhibited neither PLA2 and COX-1 activity nor COX-2 protein and mRNA expression up to the concentration of 30 microM in BMMC, indicating that rutaecarpine directly inhibited COX-2 activity. Furthermore, rutaecarpine showed in vivo anti-inflammatory activity on rat lambda-carrageenan induced paw edema by intraperitoneal administration.

CONCLUSION

Anti-inflammatory activity of Evodia rutaecarpa could be attributed at least in part by inhibition of COS-2.

CTA collateral status and response to recanalization in patients with acute ischemic stroke

BACKGROUND AND PURPOSE

Collateral status at baseline is an independent determinant of clinical outcome among patients with acute ischemic stroke. We sought to identify whether the association between recanalization after intra-arterial acute stroke therapy and favorable clinical response is modified by the presence of good collateral flow assessed on baseline CTA.

MATERIALS AND METHODS

Data are from the Keimyung Stroke Registry, a prospective cohort study of patients with acute ischemic stroke from Daegu, South Korea. Patients with M1 segment MCA with or without intracranial ICA occlusions on baseline CTA from May 2004 to July 2009 who also had baseline MR imaging were included. Two readers blinded to all clinical information assessed baseline and follow-up imaging. Leptomeningeal collaterals on baseline CTA were assessed by consensus by use of the regional leptomeningeal score.

RESULTS

Among 84 patients (mean age, 65.2 ± 13.2 years; median NIHSS score, 14; interquartile range, 8.5), median time from stroke onset to initial MR imaging was 164 minutes. TICI 2b-3 recanalization was achieved in 38.1% of patients and mRS 0-2 at 90 days in 35.8% of patients. In a multivariable model, the interaction between collateral status and recanalization was significant. Only patients with intermediate or good collaterals who recanalized showed a statistically significant association with good clinical outcome (rate ratio = 3.8; 95% CI, 1.2-12.1). Patients with good and intermediate collaterals who did not achieve recanalization and patients with poor collaterals, even if they achieved recanalization, did not do well.

CONCLUSIONS

Patients with good or intermediate collaterals on CTA benefit from intra-arterial therapy, whereas patients with poor collaterals do not benefit from treatment.

Characterization of a vaccinia virus-encoded double-stranded RNA-binding protein that may be involved in inhibition of the double-stranded RNA-dependent protein kinase

The work described in this article identifies a vaccinia virus-encoded protein that may be involved in inhibition of the interferon-induced, double-stranded RNA-dependent protein kinase. Extracts prepared from vaccinia virus (WR strain)-infected cells contain an inhibitor of this kinase. Inhibition was reduced in extracts from which dsRNA-binding proteins had been removed by preadsorption to poly(rI).poly(rC)-Sepharose, suggesting that a dsRNA-binding protein may be involved in kinase inhibition. A single major virus-specific polypeptide of Mr = 25,000 (p25) bound to the poly(rI).poly(rC)-Sepharose. p25 was synthesized in a coupled in vitro transcription/translation system programmed with vaccinia cores, indicating that it is a vaccinia-encoded protein. Synthesis of p25 was detected at early times, by 2 hr post infection, peaked at 5 hours postinfection, and decreased during the late phase of virus replication. In the presence of cytosine arabinoside p25 synthesis did not decrease at late times postinfection. Kinase inhibitory activity accumulated with similar kinetics to p25, both in the presence and absence of cytosine arabinoside. Kinase inhibitory activity copurified with p25, through gel filtration, and Cibacron blue-affinity chromatography. Removal of p25 by precipitation with antiserum to p25 decreased kinase inhibitory activity in extracts prepared from vaccinia virus-infected cells. These results suggest that p25 may be necessary for the specific kinase inhibitory activity detected in vaccinia virus-infected cells.

Cerebral infarction in chronic meningitis: a comparison of tuberculous meningitis and cryptococcal meningitis

Twenty-eight patients with cerebral infarction secondary to chronic meningitis were retrospectively identified at our institution over a period of 5 years. They accounted for 47% (17/36) of tuberculous meningitis (TBM) and 32% (11/34) of cryptococcal meningitis cases. Single infarctions were found in 15 patients and multiple infarctions in 13. The distribution of single infarctions was: basal ganglia 7; internal capsule 3; thalamus 1; cerebellum 1; and cortical infarct 3. Therapeutic outcomes at 3 months were determined using a modified Barthel INDEX: At follow-up of 3 months or more, 10 had good outcomes while the other 18 had poor outcomes. The 18 with poor outcomes included six who died, and 12 who had severe neurological sequelae. TBM and cryptococcal meningitis shared similar clinical features, both being frequently associated with other neurological complications, including hydrocephalus, cranial nerve palsy, and seizures in our patients. However, extracranial involvement, such as spinal and pulmonary involvement, was more commonly found in TBM patients. Cerebral infarction can occur in both the acute stage and later stages of treatment. Mortality and morbidity are high, and early diagnosis and appropriate antimicrobial treatment are essential. If hydrocephalus is demonstrated, early ventricular decompression is needed to prevent further cerebral ischaemia.

Rescue of vaccinia virus lacking the E3L gene by mutants of E3L

Vaccinia virus with the E3L gene deleted was able to replicate in RK-13 but not HeLa cells. This host range phenotype could be complemented by an E3L gene expressed transiently from a plasmid. Analysis of mutants of E3L indicates that the ability to complement deletion of E3L correlates with the ability of mutated proteins to bind double-stranded RNA but not with their ability to migrate to the nucleus.

Purification and characterization of extracellular phospholipase A2 from peritoneal cavity of caseinate-treated rat

Peritoneal exudate produced in rat injected with caseinate contained extracellular phospholipase A2. The activity required Ca2+ ion and had a pH optimum of 9 (Chang, H.W., Kudo, I., Hara, S., Karasawa, K., & Inoue, K. (1986) J. Biochem. 100, 1099-1101). This phospholipase A2 was purified about 14,000-fold to near homogeneity by the sequential use of column chromatography on Sephadex G-75, Toyopearl HW-65, and TSK ODS-120T reverse-phase HPLC. The final preparation showed a single protein band on SDS-polyacrylamide gel electrophoresis, and its molecular weight was estimated to be approximately 13,500. The enzyme hydrolyzed phosphatidylethanolamine (PE) and phosphatidylserine (PS) more effectively than phosphatidylcholine (PC). When 1-acyl-2-[1-14C]inoleoyl-sn-glycero-3-phospholipids were used as a substrate, the apparent Km values were 0.027 mM with PE, 0.032 mM with PS, and 0.1 mM with PC, and the Vmax values were 105 mumol/min/mg with PE, 71 mumol/min/mg with PC. The enzyme activity was inhibited by p-bromophenacyl bromide, dithiothreitol, and mepacrine. The amino acid sequence of the NH2-terminal portion and the amino acid composition of the purified enzyme were determined. They were different from those of rat pancreatic phospholipase A2, but very similar to those of phospholipase A2 secreted from rat platelets.

Effects of prenylated flavonoids and biflavonoids on lipopolysaccharide-induced nitric oxide production from the mouse macrophage cell line RAW 264.7

Certain flavonoid derivatives possess anti-inflammatory activity in vitro and in vivo. Besides their antioxidative properties and effects on the arachidonic acid metabolism including cyclooxygenase/lipoxygenase inhibition, some flavones and flavonols were previously found to show inhibitory activity on nitric oxide production by inducible nitric oxide synthase (iNOS; NOS type 2) through suppression of iNOS induction. As part of our continuing investigations, the effects of unique and minor flavonoids (prenylated flavonoids and biflavonoids) on nitric oxide production from lipopolysaccharide-induced macrophage cell line (RAW 264.7) were evaluated in order to establish their inhibitory activity on NO production and correlate this action with their in vivo anti-inflammatory potential. Among the derivatives tested, prenylated compounds including morusin, kuwanon C, and sanggenon D and biflavonoids such as bilobetin and ginkgetin were found to inhibit NO production from lipopolysaccharide (LPS)-induced RAW 264.7 cells at > 10 microM. Inhibition of nitric oxide production was mediated by suppression of iNOS enzyme induction but not by direct inhibition of iNOS enzyme activity. An exception was echinoisoflavanone that inhibited iNOS enzyme activity (IC50 = 83 microM) and suppressed iNOS enzyme induction as well. While most prenylated derivatives showed cytotoxicity to RAW cells at 10-100 microM, all biflavonoids tested were not cytotoxic. Since nitric oxide (NO) produced by inducible NO synthase (iNOS) plays an important role in inflammatory disorders, inhibition of NO production by these flavonoids may contribute, at least in part, to their anti-inflammatory and immunoregulating potential in vivo.

Dynamic properties of isolated acetylcholine receptor proteins: release of calcium ions caused by acetylcholine binding

Interaction of Ca and acetylcholine (AcCh) ions with purified acetylcholine receptor (AcChR) from Torpedo californica and Electrophorus electricus has been investigated in view of these ions' role proposed in bioelectricity. Spectrophotometric Ca titration using murexide as an indicator and an ultrafiltration method with 45Ca show that AcChR proteins have a high binding capacity for Ca ions. Per macromolecule of 260,000 daltons, up to 60 Ca ions can be bound with at least three Ca dissociation constants. A linear inhibition of AcCh binding to AcChR by Ca was observed in the 0.1-1 mM Ca range, indicating competition of AcCh and Ca for AcChR. The addition of AcCh to a Ca-AcChR solution at 1.2 mM Ca causes release of four to six bound Ca ions from AcChR when a maximum of two AcCh ions are bound per 260,000 dalton macromolecule. The subsequent addition of alpha-bungarotoxin causes reuptake of up to six Ca ions by AcChR. These results suggest that the neural activator AcCh and the inhibitor alpha-bungarotoxin induce opposing shifts between different conformational states of isolated AcChR.

Amentoflavone, a plant biflavone: a new potential anti-inflammatory agent

Biflavonoid is one of unique classes of naturally-occurring bioflavonoids. Certain biflavonoids including amentoflavone were previously reported to have inhibitory effect on the group II phospholipase A2 activity. Amentoflavone was also found to inhibit cyclooxygenase from guinea-pig epidermis without affecting lipoxygenase. In this study, anti-inflammatory and analgesic activities of amentoflavone were evaluated. When amentoflavone was administered intraperitoneally, it showed a potent anti-inflammatory activity as determined by amelioration of croton-oil induced mouse ear edema. It also showed a potent anti-inflammatory activity in the rat carrageenan paw edema model (ED50 = 42 mg/kg) compared to the activity of prednisolone (35 mg/kg) and indomethacin (10 mg/kg). However, amentoflavone did not show a significant inhibitory activity against rat adjuvant-induced arthritis, a chronic inflammatory model. In addition, amentoflavone was found to possess a potent analgesic activity in the acetic acid writhing test (ED50 = 9.6 mg/kg) compared to the activity of indomethacin (3.8 mg/kg). These results suggest that amentoflavone may be a potential lead for a new type of anti-inflammatory agents having dual inhibitory activity of group II phospholipase A2 and cyclooxygenase.

Suppression of mouse lymphocyte proliferation in vitro by naturally-occurring biflavonoids

In a continuing effort to investigate biological activities of flavonoids, nine biflavonoids, isolated from three plant sources were evaluated for their suppressive effects on mouse lymphocyte proliferation. The biflavonoids tested were amentoflavone, bilobetin, ginkgetin, isoginkgetin, sciadopitysin, ochnaflavone, 4'-O-methylochnaflavone, cryptomerin B and isocryptomerin. At 10 uM, several biflavonoids such as ginkgetin, isoginkgetin, ochnaflavone, cryptomerin B and isocryptomerin showed the suppressive activity against lymphocyte proliferation induced by Con A or LPS. Apigenin (flavone) and quercetin (flavonol) were suppressive against Con A-induced lymphocyte proliferation, but not against LPS-induced lymphocyte proliferation at the same concentration range. Biflavonoids were found to be irreversible inhibitors of lymphocyte proliferation. This is the first report describing the suppressive effects of naturally-occurring biflavonoids against lymphocyte proliferation.

The catalytic subunit of phosphoinositide 3-kinase: requirements for oncogenicity

The retroviral oncogene p3k (v-p3k) of avian sarcoma virus 16 (ASV16) codes for the catalytic subunit of phosphoinositide (PI) 3-kinase, p110alpha. The v-P3k protein is oncogenic in vivo and in vitro; its cellular counterpart, c-P3k, lacks oncogenicity. Fusion of viral Gag sequences to the amino terminus of c-P3k activates the transforming potential. Activation can also be achieved by the addition of a myristylation signal to the amino terminus or of a farnesylation signal to the carboxyl terminus of c-P3k. A mutated myristylation signal was equally effective; it also caused a strong increase in the kinase activity of P3k. Mutations that inactivate lipid kinase activity abolish oncogenicity. The transforming activity of P3k is correlated with the ability to induce activating phosphorylation in Akt. Point mutations and amino-terminal deletions recorded in v-P3k were shown to be irrelevant to the activation of oncogenic potential. Interactions of P3k with the regulatory subunit of PI 3-kinase, p85, or with Ras are not required for transformation. These results support the conclusion that the oncogenicity of P3k depends on constitutive lipid kinase activity. Akt is an important and probably essential downstream component of the oncogenic signal from P3k.

The prognostic factors of cryptococcal meningitis in HIV-negative patients

Seventy-one patients with cryptococcal meningitis, 46 males and 25 females, aged 15-83 years, were included in this study. Their initial clinical manifestations, cerebrospinal fluid (CSF) features, and therapeutic results were analysed. Patients were treated with three different regimens: amphotericin B, fluconazole, and combination therapy. Based on the therapeutic results, the 71 patients were also divided into cured, improved, and failed groups. For statistical comparison, the clinical manifestations and CSF features, were compared according to therapeutic outcome. There was no statistical difference in outcome among the three different antifungal regimens. However, patients treated with fluconazole required 36% fewer days of hospitalization compared with those receiving amphotericin B. Significant prognostic factors, included low CSF glucose, high CSF lactate, high CSF cryptococcal antigen titre (> or = 1:1024), initial level of consciousness, the presence of seizure, hydrocephalus, and central nervous system vasculitis. Multiple logistic regression analysis showed that only initial level of consciousness, and CSF antigen titre were strongly associated with therapeutic failure after other potentially confounding factors were adjusted for. Because some of the prognostic factors in cryptococcal meningitis can be corrected, early diagnosis, early use of appropriate antifungal treatment, and the correction of the underlying metabolic derangements are important in management.

Vitexicarpin, a flavonoid from the fruits of Vitex rotundifolia, inhibits mouse lymphocyte proliferation and growth of cell lines in vitro

Certain flavonoids having a C-2,3-double bond were reported to show an inhibitory activity against T-lymphocyte proliferation, but not against B-lymphocyte proliferation in vitro. In the course of these studies, vitexicarpin (3',5-dihydroxy-3,4',6,7-tetramethoxyflavone) isolated from the fruits of Vitex rotundifolia was found to show potent inhibition against lymphocyte proliferation. Vitexicarpin inhibited T-lymphocyte proliferation as well as B-lymphocyte proliferation at > 0.1 microM. IC50's were approximately 0.7 microM both for T- and B-cell proliferation. The inhibitory activity of vitexicarpin was reversible. Vitexicarpin also inhibited the growth of certain cancer cell lines, EL-4 and P815.9 (IC50 = 0.25-0.3 microM). These results suggest that vitexicarpin may be a potential therapeutic agent involved in inflammatory/immunoregulatory disorders such as rheumatoid arthritis and lymphomas.

Atrial size reduction as a predictor of the success of radiofrequency maze procedure for chronic atrial fibrillation in patients undergoing concomitant valvular surgery

INTRODUCTION

Previous studies showed that the surgical maze procedure can restore sinus rhythm and atrial transport function in patients with chronic atrial fibrillation (AF). However, no previous studies discussed the association of atrial size reduction and the success of sinus conversion by the radiofrequency (RF) maze procedure for chronic AF.

METHODS AND RESULTS

A total of 119 chronic AF patients undergoing valvular operations were included in this study. Sixty-one patients received RF and cryoablation to create lesions in both atria to simulate the surgical maze II or III procedure (RF maze II or RF maze III; 13 patients, group 1) or a modified maze pattern (RF maze "IV"; 48 patients, group 2). The other 58 patients who underwent valvular operations alone without the maze procedure served as control (group 3). At 3-month follow-up after operation, sinus rhythm was restored in 73%, 81%, and 11% of patients in groups 1, 2 and 3, respectively. Preoperative left and right atrial sizes were not statistically significant predictors of sinus conversion by the RF maze procedure. However, as a result of postoperative reduction of atrial sizes, postoperative left atrial diameter was significantly smaller in patients who had sinus conversion by the RF maze procedure than in patients who did not regain sinus rhythm (45.0+/-7.0 mm vs 51.0+/-8.0 mm; P = 0.03). Postoperative right atrial area of patients who had sinus conversion by the RF maze procedure also was significantly smaller than that of patients who did not regain sinus rhythm (18.1+/-4.4 cm2 vs 28.5+/-8.2 cm2; P = 0.008).

CONCLUSION

Atrial size reduction appears to predict the success of sinus conversion with the RF maze procedure used in conjunction with valvular surgery.

Effects of naturally occurring flavonoids on mitogen-induced lymphocyte proliferation and mixed lymphocyte culture

In this investigation, 34 structurally different flavonoids including derivatives of chalcone, flavanone, flavan-3-ol, flavone, flavonol, and their glycosides were evaluated for in vitro suppression of mitogen-induced lymphocyte proliferation and mixed lymphocyte culture from mouse spleen. Flavonoids, mainly derivatives of flavone and flavonol, clearly demonstrated the suppressive effects on lymphocyte proliferation at higher than 10(-6) M depending on the structures of flavonoid molecules, although their suppressive activities were less than that of cyclosporin A or prednisolone. Various glycosidic substitutions to A- and/or C-ring of the flavonoid aglycones were found to eliminate the suppressive activities of their aglycones, regardless of sugar compositions and positions of substitutions. In concanavalin A-induced lymphocyte proliferation, derivatives of flavone and flavonol having 2,3-unsaturation and at least 1 hydroxyl group showed the suppressive activity. In lipopolysaccharide-induced lymphocyte proliferation, only myricetin was active among flavonoids tested at the concentrations up to 10(-5) M. In mixed lymphocyte culture, some derivatives of flavone and flavonol with 2,3-unsaturation were active and especially flavone derivatives showed the higher suppressive activities than those of the flavonol derivatives.