Thirteen new peptaibols with antimicrobial activities from Trichoderma sp / 中国天然药物

From the fungus Trichoderma sp., we isolated seven novel 18-residue peptaibols, neoatroviridins E-K (1-7), and six new 14-residue peptaibols, harzianins NPDG J-O (8-13). Additionally, four previously characterized 18-residue peptaibols neoatroviridins A-D (14-17) were also identified. The structural configurations of the newly identified peptaibols (1-13) were determined by comprehensive nuclear magnetic resonance (NMR) and high-resolution electrospray ionization tandem mass spectrometry (HR-ESI-MS/MS) data. Their absolute configurations were further determined using Marfey's method. Notably, compounds 12 and 13 represent the first 14-residue peptaibols containing an acidic amino acid residue. In antimicrobial assessments, all 18-residue peptaibols (1-7, 14-17) exhibited moderate inhibitory activities against Staphylococcus aureus 209P, with minimum inhibitory concentration (MIC) values ranging from 8-32 μg·mL-1. Moreover, compound 9 exhibited moderate inhibitory effect on Candida albicans FIM709, with a MIC value of 16 μg·mL-1.

Biotransformation of α-asarone by Alternaria longipes CGMCC 3.2875 / 中国天然药物

Biotransformation of α-asarone by Alternaria longipes CGMCC 3.2875 yielded two pairs of new neolignans, (+) (7S, 8S, 7'S, 8'R) iso-magnosalicin (1a)/(-) (7R, 8R, 7'R, 8'S) iso-magnosalicin (1b) and (+) (7R, 8R, 7'S, 8'R) magnosalicin (2a)/(-) (7S, 8S, 7'R, 8'S) magnosalicin (2b), and four known metabolites, (±) acoraminol A (3), (±) acoraminol B (4), asaraldehyde (5), and 2, 4, 5-trimethoxybenzoic acid (6). Their structures, including absolute configurations, were determined by extensive analysis of NMR spectra, X-ray crystallography, and quantum chemical ECD calculations. The cytotoxic activity and Aβ

Study on metabolic dynamics,metabolic enzyme phenotype and species difference of hepatic and intestinal microsome of psoralidin / 中国中药杂志

This study aims to investigate metabolic activities of psoralidin in human liver microsomes( HLM) and intestinal microsomes( HIM),and to identify cytochrome P450 enzymes( CYPs) and UDP-glucuronosyl transferases( UGTs) involved in psoralidin metabolism as well as species differences in the in vitro metabolism of psoralen. First,after incubation serial of psoralidin solutions with nicotinamide adenine dinucleotide phosphate( NADPH) or uridine 5'-diphosphate-glucuronic acid( UDPGA)-supplemented HLM or HIM,two oxidic products( M1 and M2) and two conjugated glucuronides( G1 and G2) were produced in HLM-mediated incubation system,while only M1 and G1 were detected in HIM-supplemented system. The CLintfor M1 in HLM and HIM were 104. 3,and57. 6 μL·min~(-1)·mg~(-1),respectively,while those for G1 were 543. 3,and 75. 9 μL·min~(-1)·mg~(-1),respectively. Furthermore,reaction phenotyping was performed to identify the main contributors to psoralidin metabolism after incubation of psoralidin with NADPH-supplemented twelve CYP isozymes( or UDPGA-supplemented twelve UGT enzymes),respectively. The results showed that CYP1 A1( 39. 5 μL·min~(-1)·mg~(-1)),CYP2 C8( 88. 0 μL·min~(-1)·mg~(-1)),CYP2 C19( 166. 7 μL·min~(-1)·mg~(-1)),and CYP2 D6( 9. 1 μL·min~(-1)·mg~(-1)) were identified as the main CYP isoforms for M1,whereas CYP2 C19( 42. 0 μL·min~(-1)·mg~(-1)) participated more in producing M2. In addition,UGT1 A1( 1 184. 4 μL·min~(-1)·mg~(-1)),UGT1 A7( 922. 8 μL·min~(-1)·mg~(-1)),UGT1 A8( 133. 0 μL·min~(-1)·mg~(-1)),UGT1 A9( 348. 6 μL·min~(-1)·mg~(-1)) and UGT2 B7( 118. 7 μL·min~(-1)·mg~(-1)) played important roles in the generation of G1,while UGT1 A9( 111. 3 μL·min~(-1)·mg~(-1)) was regarded as the key UGT isozyme for G2. Moreover,different concentrations of psoralidin were incubated with monkey liver microsomes( MkLM),rat liver microsomes( RLM),mice liver microsomes( MLM),dog liver microsomes( DLM) and mini-pig liver microsomes( MpLM),respectively. The obtained CLintwere used to evaluate the species differences.Phase Ⅰ metabolism and glucuronidation of psoralidinby liver microsomes showed significant species differences. In general,psoralidin underwent efficient hepatic and intestinal metabolisms. CYP1 A1,CYP2 C8,CYP2 C19,CYP2 D6 and UGT1 A1,UGT1 A7,UGT1 A8,UGT1 A9,UGT2 B7 were identified as the main contributors responsible for phase Ⅰ metabolism and glucuronidation,respectively. Rat and mini-pig were considered as the appropriate model animals to investigate phase Ⅰ metabolism and glucuronidation,respectively.

A pair of new tirucallane triterpenoid epimers from the stems of Picrasma quassioides / 中国天然药物

A pair of new tirucallane triterpenoid epimers, picraquassins M and N (1> and 2), were isolated from the stems of Picrasma quassioides (D. Don) Benn. Their structures were determined based on comprehensive spectroscopic and X-ray crystallographic analyses. In addition, their AChE inhibitory activity, cytotoxicity against five human tumour cell lines (SW480, MCF-7, HepG2, Hela, and PANC-1), and antimicrobial activity against two bacteria (Staphylococcus. aureus 209P and Escherichia coli ATCC0111) and two fungi (Candida albicans FIM709 and Aspergillus niger R330) were evaluated.

Two new ursane-type nortriterpenes from Lonicera macranthoides and their iNOS-inhibitory activities / 中国天然药物

The flower buds of Lonicera macranthoides (Shan Yin-Hua), represent an important traditional Chinese medicine and food ingredient. A phytochemical investigation of the 70% EtOH extract of the flower buds of L. macranthoides resulted in the isolation of 12 triterpenoids (1-12), including two new ursane-type nortriterpenes, 2α, 24-dihydroxy-23-nor-ursolic acid (1) and 2α, 4α-dihydroxy-23-nor-ursolic acid (2). Their structures were established by multiple spectroscopic methods and comparison with literature data. All isolated compounds were evaluated for their anti-inflammatory effects in LPS-activated RAW264.7 cells. Compounds 1 and 2 exhibited inhibitory effects on iNOS at the concentration of 30 μmol·L.

Research progress on influence of intestinal microflora on peripheral immune organs in mice / 中国免疫学杂志

The study found that the presence of intestinal microbiota is not only important for the metabolism of essential nutrients in the body, but also plays a key role in the development of the body′s immune system in recent years. Partial microbiota, through natural selection and co-evolution with the host, forms symbiotic relationships with host microbes that are inseparable from host physiology in mice. Symbiotic flora affects the formation of the body′s immune system by affecting innate and adaptive immunity and the development of various regulatory mechanisms. The destruction of the microbial ecosystem in the intestine can lead to the occurrence of many diseases,especially those related to the immune system. Peripheral immune organs always receive a number of immune cells colonized by antigen stimulation. So,the intestinal flora plays an important role in maintaining the function of immune cells. This article will investigates the effects of mouse-related intestinal flora on peripheral immune organ function.

Simultaneous determination of cordycepin and 2'-deoxyadenosine in Cordyceps genus by online SPE-HPLC / 中国中药杂志

An online SPE-HPLC method for simultaneous determination of cordycepin (3'-deoxyadenosine) and 2'-deoxyadenosine in Cordyceps genus (C. sinensis,C. militaris,Hirsutella sinensis and C. sobolifera) was developed. The samples were enriched on a ZORBAX SB-AQ (4.6 mm×12.5 mm,5 μm) column with isocratic elution by 9% methanol solution. The separation of analytes was performed on a ZORBAX SB-AQ (4.6 mm×150 mm,5 μm) column with gradient elution by 0.1% formic acid solution and methanol (91∶9). The flow rate was 1.0 mL•min⁻¹. Column temperature was 40 ℃ and detection wavelength was 260 nm. This method has been applied for analysis of different Cordyceps genus. The 2'-deoxyadenosine was detected in C. sinensis,Hirsutella sinensis and C. sobolifera. The cordycepin was detected in C. militaris. In summary,the cordycepin chromatographic peak from C. sinensis in some past reports may be the 2'-deoxyadenosine chromatographic peak or the mixture peak of 2'-deoxyadenosine and cordycepin in which 2'-deoxyadenosine content was higher than cordycepin. The developed method is suitable for analysis of cordycepin and 2'-deoxyadenosine in Cordyceps genus.

Phytochemistry and pharmacology of Allii Macrostemonis Bulbus, a traditional Chinese medicine / 中国天然药物

Allii Macrostemonis Bulbus (Xiebai in Chinese), as a famous traditional Chinese medicine, has great medicinal and dietary values since ancient times. In China, the dry bulbs of Allium macrostemon and Allium chinense are both used as its original plants. Pharmacological studies have revealed that both of them could increase plasminogen activator activity and prolong the effect of coagulation to achieve antiplatelet aggregation which validates their traditional uses for the treatment of thoracic obstruction and cardialgia in clinics. Besides, several other significant activities, including lipid-lowering, anti-atherosclerosis, antitumor, antispasmodic, antibacterial, antioxidant, and insecticidal activities, have already been reported. The volatile oils, nitrogenous compounds, and steroidal saponins are the major beneficial compounds. Among them, steroidal saponins are considered as the characteristic constituents. In this review, the current information concerning the phytochemistry and pharmacology of Allii Macrostemonis Bulbus is summarized comprehensively. In addition, several research future perspectives are presented, especially the mechanism of bioactive components and fraction from the bulbs of Allium macrostemon and Allium chinense.

Two new polyesters from wetland soil-derived fungus Talaromyces flavus / 中国中药杂志

Two new polyesters, talapolyesters G-H (1-2) were isolated from the wetland soil-derived fungus Talaromyces flavus BYD07-13, and their structures were determined by NMR and MS spectroscopic data. The absolute configurations of the residues were determined by alkaline hydrolysis. The cytotoxicity against five tumor cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW480) of 1-2 was examined.

Lignans isolated from stems of Sambucus williamsii and their proliferation effects on UMR106 cells / 中国中药杂志

The present study aims to investigate the lignan constituents from Sambucus williamsii and their proliferation effects on osteoblast-like UMR106 cells. Seven compounds were isolated and purified by macroporous resin D101, silica gel, Sephadex LH-20, Toyopearl HW-40, ODS column chromatographies and Preparative HPLC(C-18). Their structures were elucidated by spectroscopic methods as threo-guaiacylglycerol-beta-0-4'-conifery ether (1), lirioresinol A (2), 1-hydroxypinoresinol (3), 5-methoxybalanophonin (4), balanophonin (5), 5-methoxy-trans-dihydrodehydrodiconiferyl alcohol (6), and p-hydroxybenzaldehyde (7). Compounds 3-7 were obtained from this genus for the first time. The proliferation effects of all isolated compounds on osteoblast-like UMR106 cells were determined. Compounds 1-7 (1 x 10(-12)-1 x 10(-7) mol x L(-1)) increased UMR106 cell proliferation to some extent.

A new lignan glycoside from Forsythia suspensa / 中国天然药物

Phytochemical investigation on Forsythia suspensa (Thunb.) Vahl afforded ten compounds, including five lignan glycosides and five phenylethanoid glycosides. The compounds were isolated by using HP-20 macroporous resin, silica gel, octadecyl silica gel (ODS), size exclusion chromatography resin HW-40 chromatography, and preparative HPLC. The structures were established through application of extensive spectroscopic methods, including ESI-MS, 1D-and 2D-NMR spectroscopy. They were identified as forsythialanside E (1), 8'-hydroxypinoresinol-4'-O-β-D-glucoside (2), 8'-hydroxypinoresinol (3), lariciresinol-4'-O-β-D-glucoside (4), lariciresinol-4-O-β-D-glucoside (5), forsythoside H (6), forsythoside I (7), forsythoside F (8), plantainoside B (9), and plantainoside A (10). Compound 1 was a new lignan glycoside.

Anti-inflammatory effects of Reduning Injection on lipopolysaccharide-induced acute lung injury of rats / 中国结合医学杂志

<p><b>OBJECTIVE</b>To evaluate the protective effects of Reduning Injection (, RDN), a patent Chinese medicine, on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats and its underlying mechanisms of action.</p><p><b>METHODS</b>Sixty male Sprague-Dawley rats were randomly divided into 6 groups, including normal control, model, dexamethasone (DEX, 5 mg/kg), RDN-H (720 mg/kg), RDN-M (360 mg/kg) and RDN-L (180 mg/kg) groups, with 10 rats in each group. Rats were challenged with intravenous injection of LPS 1 h after intraperitoneal treatment with RDN or DEX. At 6 h after LPS challenge, lung tissues and bronchoalveolar lavage fluid (BALF) were collected, and the number of inflammatory cells was determined. The right lungs were collected for histopathologic examination, measurement of gene and protein expressions, superoxide dismutase (SOD) and myeloperoxidase (MPO) activities.</p><p><b>RESULTS</b>In vivo pretreatment of RDN (360, 720 mg/kg) significantly reduced the weight of wet to dry (W/D) ratio of lung, protein content in BALF, and led to remarkable attenuation of LPS-induced histopathological changes in the lungs. Meanwhile, RDN enormously decreased BALF total inflammatory cells, especially neutrophil and macrophage cell numbers. Moreover, RDN increased SOD activity, inhibited MPO activity, alleviated LPS-induced tumor neurosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) expression in lung tissues. Furthermore, RDN (720 mg/kg) efficiently weakened nuclear factorkappa B (NF-κB) gene and protein expression.</p><p><b>CONCLUSION</b>Anti-inflammatory effects of RDN was demonstrated to be preventing pulmonary neutrophil infiltration, lowering MPO activity, TNF-α and iNOS gene expression by inhibiting NF-κB activity in LPS-induced ALI.</p>

Study on antipyretic effect of Reduning injection on lipopolysaccharide-induced fever rats / 中国中药杂志

To observe the antipyretic effect of Reduning injection (RDN) on lipopolysaccharide (LPS)-induced fever rats and its impact on centric fever medium. Rats were randomly divided into the blank control group, the model group, the Metamizole group, and high and low-dose RDN groups. Except for the blank control group, all of the rats were injected intraperitoneally with LPS (80 microg x kg(-1)) to observe their body temperature changes. The double-antibody sandwich ELSIA method was adopted to determine cAMP content in hypothalamus and MPO in lung tissues of fever peak rats. The high-dose RDN group can obviously reduce the temperature rise in fever rats, and cAMP and MPO content in hypothalamus. RDN showed significant antipyretic effect, which may be related with the reduction of cAMP content in hypothalamus and MPO in lung tissues.

Determination of theacrine in rat plasma by RP-HPLC / 中国中药杂志

<p><b>OBJECTIVE</b>To establish a method for the determination of theacrine in rat plasma after ig. administration of theacrine.</p><p><b>METHOD</b>Blood sample was taken timely from the eyes canthus of rats. Plasma was isolated and the protein was precipitated by ethyl acetate. Then the plasma concentration of theacrine was determined with RP-HPLC. Caffeine was used as the internal standard. The chromatographic conditions were as follows: Phenomenex Luna C18 (4.6 mm x 250 mm, 5 microm) at 25 degrees C, a mixture of methanol-water (25: 75) as the mobile phase, at the flow rate of 1.0 mL x min(-1) and the detection wavelength of 290 nm.</p><p><b>RESULT</b>The linear range of theacrine was 0.5-100 mg x L(-1) (R2 = 0.998 9). The lower limit of quantification was 0.5 mg x L(-1). The intra-day RSD was 1.49% 4.40% and inter-day RSD was 0.80% -10.27%. The average extraction recoveries of theacrine were 90.3% -95.8% at concentrations of 0.5, 5.0, 50 mg x L(-1). The main pharmacokinetic parameters after ig. administration of theacrine at concentration of 30 mg x kg(-1) were as follow: C(max) (35.45 +/- 30 2.68) mg x L(-1), t(max) (0.51 +/- 0.13) h, t1/2 (3.13 +/- 1.37) h, AUC(0-infinity) (2.65.39 +/- 94.71) mg x L(-1) x h.</p><p><b>CONCLUSION</b>The method has been confirmed to be simple, stable, reproducible and with high specificity, and can be used for the pharmacokinetic study of theacrine in rats.</p>

Beneficial effects of oolong tea consumption on diet-induced overweight and obese subjects / 中国结合医学杂志

<p><b>OBJECTIVE</b>To determine the anti-obesity effects of oolong tea on diet-induced overweight or obesity.</p><p><b>METHODS</b>A total of 8 g of oolong tea a day for 6 weeks was ingested by 102 diet-induced overweight or obese subjects. The body fat level of the subjects was determined at the same time by taking body weight, height and waist measurements. The thickness of the subcutaneous fat layer was also determined on the abdomen 3 cm to the right of the navel by the ultrasonic echo method. On the other hand, effects of oolong tea ingestion on plasma triglyceride (TG) and total cholesterol (TC) were determined. Inhibitions of pancreatic lipase by oolong tea extract and catechins in vitro were also determined.</p><p><b>RESULTS</b>A total of 70% of the severely obese subjects did show a decrease of more than 1 kg in body weight, including 22% who lost more than 3 kg. Similarly, 64% of the obese subjects and 66% of the overweight subjects lost more than 1 kg during the experiment, and the subcutaneous fat content decreased in 12% of the subjects. The correlation between weight loss and subcutaneous fat decrease in men (r=0.055) was obviously lower than that in women (r=0.440, P<0.01). Body weight loss was signifificantly related to the decrease of the waist size in men (r=0.730, P<0.01) and women (r=0.480, P<0.01). Also, the correlation between subcutaneous fat reduction and decreased waist size was signifificant in women (r=0.554, P<0.01), but not in men (r=0.050, P>0.05). Moreover, the plasma levels of TG and TC of the subjects with hyperlipidemia were remarkably decreased after ingesting oolong tea for 6 weeks. In vitro assays for the inhibition of pancreatic lipase by oolong tea extract and catechins suggest that the mechanism for oolong tea to prevent hyperlipidemia may be related to the regulative action of oolong tea catechins in lipoprotein activity.</p><p><b>CONCLUSIONS</b>Oolong tea could decrease body fat content and reduce body weight through improving lipid metabolism. Chronic consumption of oolong tea may prevent against obesity.</p>

CDR3 spectratyping and clonal expansion of peripheral blood T cells in a patient with beta-mediterranean anaemia following peripheral blood stem cell transplantation / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the CDR3 spectratyping and clonal expansion of T cells in the peripheral blood mononuclear cells (PBMCs) of patients with beta-mediterranean anemia patient undergoing allogeneic peripheral blood stem cell (PBSC) transplantation.</p><p><b>METHODS</b>The total RNA was isolated from the PBMCs of a nine-year-old boy with beta-mediterranean anemia before and after PBSC transplantation, and at the time of occurrence of graft-versus-host disease (GVHD). The CDR3 length was analyzed using immunoscope technique, and the characteristics of the T cell receptor (TCR) on the T cells with clonal expansion were examined by gene sequencing.</p><p><b>RESULTS</b>The 24 TCR BV CDR3 repertoire showed Gaussian distribution in the PBMCs isolated before the transplantation, and some of the TCR BV family CDR3 showed skewing in the PBMCs isolated 23 days after transplantation and at the onset of GVHD (28 days after transplantation), suggesting the clonal expansion of the donor PBSCs.</p><p><b>CONCLUSION</b>The host PBMCs show muti-clonal expansion 23 days after PBSC transplantation, and in the stage of GVHD, some of the TCR BV family T cells show significant monoclonal expansion. Analysis of TCR CDR3 spectratyping and the molecular characteristics of specific TCR may help evaluate the immune reconstitution following the transplantation and indicate specific treatment for potential GVHD.</p>

Determination of plasma protein binding rate of methyl protodioscin with ultrafiltration / 中国中药杂志

<p><b>OBJECTIVE</b>To study the plasma protein binding rate of methyl protodioscin.</p><p><b>METHOD</b>The ultrafiltration was employed to determine the plasma protein binding rate of methyl protodioscin. The plasma concentrations of methyl protodioscin were measured by HPLC-MS-MS.</p><p><b>RESULT</b>The plasma protein binding rate of methyl protodioscin with rat plasma at the concentration of 20.0, 100 and 200 microg x mL(-1) were (94.6 +/- 0.16)%, (91.6 +/- 0.35)% and (86.10 +/- 0.60)%, respectively, while the plasma protein binding rate of methyl protodioscin with normal human plasma at the above concentrations were (82.11 +/- 5.12)%, (84.54 +/- 0.32)% and (88.52 +/- 1.02)%, respectively.</p><p><b>CONCLUSION</b>The binding rate of methyl protodioscin with plasma protein is high.</p>

Progress on the studies of cyclic lipopeptides / 药学学报

Cyclic lipopeptide, also named as acylpeptide, which was characteristic with novel structures, was paid more attention in the recent years. Cyclic lipopeptide showed various bioactivities including antibacterial, anti-tumor, anti-inflammatory, etc. Cyclic lipopeptide originated mainly from the second metabolites of microorganism, such as Cyanobacterium, Bacterium, Actinomyces, etc. The bacteria included the genus of Bacillus and Pseudomonas. In this account, the review has been made on the development of cyclic lipopeptide.

Protective effects of Guangdong Liangcha grandes on restraint stress-induced liver damage in mice / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the effect of Guangdong Liangcha Keli on restraint stress-induced liver damage in mice.</p><p><b>METHOD</b>Thirty-five male C57BL/6J mice of 7 weeks old were divided into 5 groups randomly with 7 mice in each group: normal group, restraint stress group, 250 mg kg(-1) Vitamin C, Guangdong Liangcha Keli 500 mg kg(-1) and 250 mg kg(-1). After 18 hr restraint stress, the ALT acitivity in plasma, MDA level in plasma and liver, GSH content, GSH-PX and GST activities, NO level and ORAC value in liver were determined.</p><p><b>RESULT</b>Compared with restraint model group, Guangdong Liangcha Keli could markedly reduce ALT activity (92.75 +/- 1.91 vs 39.29 +/- 2.56, 32.69 +/- 1.46) U L(-1), and protect the liver damage induced by oxidative stress. In addition, Guangdong Liangcha Keli could effectively increase the ORAC value, GSH content, GSH-PX activity and GST activity and reduce the MDA level and NO level in liver.</p><p><b>CONCLUSION</b>Oral treatment of Guangdong Liangcha Keli is found to reduce restraint stress-induced liver damage in terms of above mentioned biochemical parameters, and these protective effects may be related to its free radical scavenging activity and lipid peroxidation inhibitory effects.</p>

Expression of recombination-activating genes and T cell receptor gene recombination in the human T cell leukemia cell line / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Recent studies have suggested that mature T cells can change their specificity through reexpression of recombination-activating genes (RAG) and RAG-mediated V(D)J recombination. This process is named receptor revision and has been observed in mature peripheral T cells from transgenic mice and human donors. However, whether thebreceptor revision in mature T cells is a random or orientated process remains poorly understood. Here we used the Jurkathuman T cell line, which represents a mature stage of T cell development, as a model to investigate the regulation of Tcell receptor (TCR) gene recombination.</p><p><b>METHODS</b>TCR Dbeta-Jbeta signal joint T cell receptor excision DNA circles (sjTRECs) were determined by nested and seminested PCR. Double-strand DNA breaks at recombination signal sequences (RSSs) in the TCRVbeta chain locus were detected by ligation-mediated-PCR. Further analysis of the complementarity-determining region 3 (CDR3) size of the TCRVbeta chain was examined by the TCR GeneScan technique.</p><p><b>RESULTS</b>RAG1, RAG2, and three crucial components of the nonhomologous DNA end-joining (NHEJ) pathway were readily detected in Jurkat. Characteristics of junctional diversity of Dbeta2-Jbeta2 signal joints and ds RSS breaks associated with the Dbeta2 5' and Dbeta 2 3' sites were detected in DNA from Jurkat cells. CDR3 size and the gene sequences of the TCRVbeta chain did not change during cell proliferation.</p><p><b>CONCLUSIONS</b>RAG1 and RAG2 and ongoing TCR gene recombination are coexpressed in Jurkat cells, but the ongoing recombination process may not play a role in modification of the TCR repertoire.However, the results suggest that Jurkat could be used as a model for studying the regulation of RAGs and V(D)J recombination and as a "special" model of the coexistence of TCR gene rearrangements and "negative" receptor revision.</p>