Selection and determination of specific and protective antigens of Mycobacterium tuberculosis

OBJECTIVE

To select and identify the specific and protective antigens of Mycobacterium tuberculosis (M. tuberculosis) for searching a new approach to diagnose and treat tuberculosis.

METHODS

Extract and culture filtrates of M. tuberculosis were obtained by ultrasonic treatment and millipore membrane filtration, respectively. The protein samples were tested with monoclonal antibody (MAb) and patient sera. The proteins showing positive reaction were sequenced on Beckman/LF 3200/peptide amino acid sequencer.

RESULTS

Proteins of M. tuberculosis with molecular weight of 31 ku and 30 ku showed positive results when reacted with anti-M. tuberculosis MAb and sera of tuberculosis patients, but not with normal mouse serum and healthy human sera. N-terminal sequences of the 31 ku and 30 ku antigen were Ala Glu Val Asp Trp Leu Val Phe Ala Val and Phe Ser Arg Pro Gly Leu Pro Val Glu Try respectively.

CONCLUSION

31 ku and 30 ku proteins of M. tuberculosis are immune protective proteins. They play important or dominant roles in determination of immunorecognization.

[Effects of acute mild and moderate hypoxia on human short memory]

OBJECTIVE

To investigate the effects of acute mild and moderate hypoxia on human short memory.

METHOD

Tests of pattern memory, scanning memory, continuous recognition memory and space memory were conducted on 18 healthy young male subjects during exposure to 300 m (control), 2800 m, 3600 m and 4400 m altitude in hypobaric chamber.

RESULT

Compared to control group, only the performance of continous recognition memory decreased significantly after exposure to 2800 in for 1 h(P < 0. 05); total reaction time in all tests increased significantly (P < 0.0 1) and performance decreased after exposure to 3600 in for 1 h, but the error rates in memory scanning and space memory test were unchanged (P > 0.05); during exposure to 4400 in performance of all tests decreased further to about 90.4%, 93.7%, 83.3% and 80.7% of the control values (P < 0.01), respectively,and error rate increased significantly too (P < 0.05).

CONCLUSION

Performance of human short memory decreased after exposure to acute mild and moderate hypoxia for 1 h, and these effects were aggravated with the increase of altitude. Characteristic and threshold of the effect on the various performance tests were different, but increase of reaction time was the first to appear in all cases.

Molecular mechanisms of drug resistance in Mycobacterium tuberculosis clinical isolates

OBJECTIVE

To study the molecular mechanisms of drug resistance in Mycobacterium (M). tuberculosis, to evaluate the value of the beta subunit of RNA polymerase (rpoB), the ribosomal siz protein (rpsL), 16Sr RNA (rrs), catalase-peroxidase gene (katG) genes, and inhA regulatory sequence as genetic markers for rifampin (RFP), streptomycin (SM), isoniazid (INH) resistance, and to develop new methods for detecting the drug resistance.

METHOD

The rpoB, rpsL, rrs, katG genes, and inhA regulatory sequence in 85 M. tuberculosis isolates were analyzed with polymerase chain reaction (PCR), PCR-single-stranded conformation polymorphism analyses (SSCP), PCR-nucleotide sequence analyses (NS) and PCR-restriction fragment length polymorphism (RFLP).

RESULTS

The sensitivity of amplifying the drug-resistant genes with PCR was 1-10 pg DNA. Twenty-eight drug-sensitive strains had no alterations in the rpoB, rpsL, rrs, katG genes, and inhA regulatory sequences. 93.3% of 45 M. tuberculosis RFP-resistant (RFPr) isolates had rpoB mutations. Codon 531 and 526 of the rpoB are the most common sites of nucleotide substitutions. 72.5% of 40 SM-resistant (SMr) isolates had an identical mutation at codon 43 of the rpsL gene. No isolates had a mutation at codon 88 of the rpsL. Only 7.5% of these SMr isolates had A-to-C transversions at position 513 of the rrs gene. Of 34 INH-resistant (INHr) isolates, 11.8% had complete katG deletions, 55.9% had mutations in the selected region of katG. Only 8.8% had alterations in the inhA regulatory sequences. 60.9% of RFPr, INHr, and SMr isolates had mutations in genetic markers for these drug resistance.

CONCLUSIONS

Most drug resistance in M. tuberculosis was due to simple mutations occurring in chromosomally encoded genes. Alterations in rpoB, rpsL and katG gene may be the important mechanism of M. tuberculosis resistance to RFP, SM, and INH. PCR, PCR-SSCP, PCR-NS, and PCR-RFLP are going to become the simple, rapid and reliable diagnostic tests for drug resistance in M. tuberculosis.

Targeted disruption of Smad3 reveals an essential role in transforming growth factor beta-mediated signal transduction

The Smads are a family of nine related proteins which function as signaling intermediates for the transforming growth factor beta (TGF-beta) superfamily of ligands. To discern the in vivo functions of one of these Smads, Smad3, we generated mice harboring a targeted disruption of this gene. Smad3 null mice, although smaller than wild-type littermates, are viable, survive to adulthood, and exhibit an early phenotype of forelimb malformation. To study the cellular functions of Smad3, we generated Smad3 null mouse embryonic fibroblasts (MEFs) and dermal fibroblasts. We demonstrate that null MEFs have lost the ability to form Smad-containing DNA binding complexes and are unable to induce transcription from the TGF-beta-responsive promoter construct, p3TP-lux. Using the primary dermal fibroblasts, we also demonstrate that Smad3 is integral for induction of endogenous plasminogen activator inhibitor 1. We subsequently demonstrate that Smad3 null MEFs are partially resistant to TGF-beta's antiproliferative effect, thus firmly establishing a role for Smad3 in TGF-beta-mediated growth inhibition. We next examined cells in which Smad3 is most highly expressed, specifically cells of immune origin. Although no specific developmental defect was detected in the immune system of the Smad3 null mice, a functional defect was observed in the ability of TGF-beta to inhibit the proliferation of splenocytes activated by specific stimuli. In addition, primary splenocytes display defects in TGF-beta-mediated repression of cytokine production. These data, taken together, establish a role for Smad3 in mediating the antiproliferative effects of TGF-beta and implicate Smad3 as a potential effector for TGF-beta in modulating immune system function.

[The 38,000 protein of Mycobacterium tuberculosis is overexpressed in Escherichia coli]

OBJECTIVE

To obtain recombinant 38,000 protein in large quantities and to study its immunologic characteristics by stable expression of the gene encoding for 38,000 antigen of Mycobacterium tuberculosis in E. coli.

METHODS

Expression plasmid was constructed with DNA recombinant technique. Positive clones were screened using double digestion and polymerase chain reaction. Recombinant plasmid was transformed into E. coli. Then E. coli carrying recombinant plasmid were induced. The expression of 38,000 antigen was identified by SDS-polyacrylamid gel electrophoresis (PAGE) and immunoblotting. Stained gel was scanned to detect expression level of recombinant antigen.

RESULTS

Gel stained with coomassie blue G-250 showed that the induced E. coli carrying recombinant plasmid can produce 38,000 protein at high level. Gel scan showed that 38,000 antigen expression in E. coli was about 36% - 40% of total cellular protein. The recombinant 38,000 antigen existed mostly in inclusion bodies. The recombinant antigen can react with antibodies: serum of pulmonary tuberculosis patients and the goats immuned with Mycobacterium tuberculosis.

CONCLUSIONS

Constructed recombinant E. coli can overproduce 38,000 antigen of Mycobacterium tuberculosis. Inclusion bodies are easy to purify and can protect the recombinant antigen from protease, on the other hand, it has not biological activity unless the denatured protein is accurately folded.

A novel superoxide dismutase-based trap for peroxynitrite used to detect entry of peroxynitrite into erythrocyte ghosts

Peroxynitrite (ONOO-) is a relatively stable oxidant produced by activated macrophages and neutrophils. To detect peroxynitrite, a novel human superoxide dismutase (SOD) trap was developed by substituting a tyrosine near the copper in the active site. The copper can catalyze nitration of this tyrosine by peroxynitrite. The nitrated tyrosine can serve as a reporter for peroxynitrite by measuring the extent of nitration with Western blots developed with a nitrotyrosine antibody. The new SOD mutant differs from bovine SOD whose sole tyrosine is far removed from the active site. Nitration of bovine SOD was second-order with respect to SOD concentration, whereas nitration of the new mutant SODs followed first-order kinetics with respect to peroxynitrite. The tyrosine SODs were used to assess whether peroxynitrite crosses erythrocyte membranes through the band 3 anion exchange protein. Tyrosine-containing SOD entrapped within normal human erythrocyte ghosts became nitrated in proportion to peroxynitrite concentration. The band 3 anion exchange protein inhibitors, phenyl isothiocyanate (PITC) and 4, 4'-diisothiocyanatostilbene-2,2'-disulfonate (DIDS), inhibited up to 90% of the nitration. The erythrocyte membrane proteins, spectrin, band 3 anion exchange protein, and proteins 4.1 and 4.2, were also nitrated. Nitration of erythrocyte membrane proteins was also inhibited by PITC and DIDS. These data suggest that the band 3 anion exchange protein is the major route for the entry of peroxynitrite into erythrocytes. The ability of peroxynitrite to cross cell membranes can contribute to its toxicity by allowing access to intracellular target molecules.

[A clinical study on vaccine of Mycobacterium vaccae in treating pulmonary tuberculosis]

OBJECTIVE

To study the effect of vaccine of Mycobacterium vaccae on cell-mediated immunity and on treating patients with pulmonary tuberculosis.

METHODS

Seventy cases of pulmonary tuberculosis with smear positive and initial treatment were classified randomly into group I (35 cases) and group II (35 cases), receiving 2HRZS/4HR and 2HRZS/4HR plus vaccine of Mycobacterium vaccae regimens respectively. Thirty-one multi-drug resistant pulmonary tuberculosis cases were classified into group III, receiving 4 - 6 sensitive antituberculous drugs and vaccine of Mycobacterium vaccae. Improvement of clinical symptoms, resolution of pulmonary lesions, negative conversion of sputum and changes of immunological functions were observed.

RESULTS

No significant difference in improvement of symptoms was found in group I and group II (P > 0.05), and the improvement rate of clinical symptoms in group III was found more than 50%. X-ray resolution rates in 4th month were 83% and 89%, and cavity reducing rates 40% and 50% respectively in group I and group II, and no significant differences were found (P > 0.05). X-ray resolution rate was 29%, cavity reducing rate 7% and no deteriorated case was found in group III. Sputum negative conversion rates in 1st, 2nd, 3rd and 4th month were 23%, 51%, 83% and 97% respectively in group I, while 31%, 77%, 89% and 100% in group II, and 3%, 16%, 29% and 32% in group III. Significant difference was found between group I and group II in sputum negative conversion rate in 2nd month after treatment (P < 0.05). After treatment, values of lymphocyte transformation test (LTT), CD(3), CD(4) and CD(4)/CD(8) of the above 3 groups were all higher than that before the treatment (P < 0.05), level of tumor necrosis factor decreased in group II and IL-2, IL-6 increased in group III.

CONCLUSIONS

Vaccine of Mycobacterium vaccae is a good immunotherapy preparation, which promotes sputum negative conversion and activation of cell-mediated immunity.

[The relationship of insulin resistance and the pathogenesis and perinatal outcome of pregnancy induced hypertension]

OBJECTIVE

To study the insulin resistance in the pathogenesis of pregnancy induced hypertension (PIH), and its relationship to perinatal outcome.

METHODS

In 111 PIH and 155 control group, the concentration of C peptide and insulin of maternal blood samples before and after 32 gestational weeks, and fetal blood samples just after delivery was determined. Fetal outcomes were assessed by the neonatal weight at delivery, Apgar scores and the quality and quantity of amniotic fluid.

RESULTS

The maternal concentration of C peptide and insulin in PIH was higher than that of control group (P < 0.05, or P < 0.01). In PIH group, the maternal concentration of C peptide and insulin in the subgroup of adverse perinatal outcomes tended to be higher than that in the subgroup of good perinatal outcomes; but in control group, there was no significantly difference between these two subgroups.

CONCLUSIONS

Insulin resistance may be one of the factors which couse PIH, and it has significant relationship with advese perinatal outcomes.

[Effect of Salvia Miltiorrhiza injection on umbilical artery hemodynamics during fetal distress in ewe]

OBJECTIVE

To study the effect of Salvia Miltiorrhiza injection (SMI) on umbilical artery hemodynamics during fetal distress in ewe.

METHODS

Intrauterine surgery were performed at 116-125 gestational days in 3 pregnancy sheep for insertion of vascular catheters at abdominal aorta from femoral artery and for implantation of a electromagnetic flowmetre probe around umbilical artery. Gelatin microsphere injection to abdominal aorta through vascular catheter for obstruction of placental-fetal circulation. 2 ml of SMI was used 6 times(2 times each sheep), and the signs of umbilical artery blood flow and wave forms of fetal abdominal aorta blood pressure were recorded before and after injections of gelatin microsphere or SMI. The fast Fourier translation (FFT) was used to turn signs in time domain into powers spectral of input impedance in frequency domain for resistance and characteristic impedance of umbilical artery.

RESULTS

After the SMI was injected into fetal abdominal aorta, the resistance of umbilical artery was significantly reduced (P < 0.05), and the changes of resistance was significantly relative with the resistance before SMI injected (r = -0.85, P < 0.001). But there were no significantly different impedance between before and after SMI treatment (P > 0.05).

CONCLUSIONS

The SMI to fetal abdominal aorta can decrease umbilical artery blood flow resistance and the changes of resistance was significantly relative to that before SMI treatment.

[Study on the karyotype and recurrence risk of malformed newborns]

OBJECTIVE

To survey the karyotype and recurrence risk of malformed newborns.

METHODS

Karyotypes of 104 malformed newborns were analyzed using G-banding. All cases were devided into two groups depending on their karyotypes: Group 1 with normal karyotype (n = 51) and group 2 with abnormal (n = 53). Clinical data were compared between malformed groups and control. Women who had the second babies after delivering a malformed (n = 20) were included in the statistics of recurrence risk.

RESULTS

(1) Of 104 cases, 53 had abnormal karyotype (50.96%). They were trisomy 21, trisomy 18, 45X, 1q+ and 5p+ (n = 41, 9, 1, 1, 1, seperately). (2) Within group 2, women's mean delivery age was elder, while premature delivery rate was higher than that of control (P < 0.01, 0.05). In group 1, the proportion of women with abnormal pregnancy history increased as compared with control (P < 0.05). The rate of fetal distress, poly/oligohydramnios and small for gestational age (SGA) of two malformed groups was higher apparently than that of control. The birth weight of two malformed groups declined obviously. (3) Within 20 second babies being born after their malformed siblings, 6 were malformed too. The total recurrence rate was 30%.

CONCLUSION

(1) Abnormal karyotype is an important cause of congenital malformations; (2) The age pregnant women abnormal pregnancy history, IUGR and poly/oligohydramnios all may be the high risk factors of congenital malformations; (3) The recurrence rate of malformations rises after the first malformed newborn's birth.

[A study of maternal and fetal peroxidation in elderly primigravidea]

OBJECTIVE

To analyze the rlationship between the age of pregnant women and maternal and fetal peroxidation.

METHODS

Pregnant 164 women in their third trimester were collected and divided into 3 groups according to maternal ages: in group 1, maternal age less than 35, n = 71; group 2, maternal age 35-39, n = 63; group 3, 40 or over, n = 30. All the women had no other high risk factors. Maternal and umbilical blood samples were drawn during delivery, and the concentration of superoxide enzyme (SOD) and Lipid peroxidate produce (LPO) were determined.

RESULTS

There were no significant differences in neonatal Apgar scores, birth weight, and the volume and quality of amniotic fluid among the 3 groups, but the cesarean scetion rate increased along with maternal age. The fetal SOD concentration was significantly higher than that in maternal serum, but the LPO level was lower. There was significant correlation between maternal age and maternal serum SOD and LPO levels (r1 = 0.15, P < 0.05; r2 = 0.2299, P < 0.01). The maternal LPO levels in group 2 and 3 were significantly higher than that in group1 (P < 0.05), and the concentration of SOD in group 3 was significantly lower than that in group 1 (P < 0.05).

CONCLUSION

The activity and concentration of free radicals were higher in mother than that in fetus, and the ability of anti-oxidation was lower in mother. The maternal age is associated with SOD and LPO levels during pregnancy.

[Studies on mutation of rifampicin-resistant genes in M. tuberculosis]

OBJECTIVE

To understand mutation of rifampicin-resistant genes in M. tuberculosis clinical isolates, and to develop a new method for detecting drug resistance.

METHOD

Analyzing the rpoB genes in 50 M. tuberculosis clinical isolates with polymerase chain reaction-single-stranded conformation polymorphism (PCR-SS-CP) and PCR-direct sequencing(PCR-DS) techniques. M. tuberculosis strain H37Rv was used as control.

RESULT

Of 3 drug-sensitive isolates and 2 non-rifampicin-resistant isolates selected, only 1 drug-sensitive isolate with abnormal rpoB SSCP profile had TCG-->TTG mutation at codon 531. Of 45 rifampicin-resistant isolates, 35 isolates with abnormal SSCP profiles had mutations in rpoB sequences, in which 14 isolates displayed TCG-->TTG or TGG or TAC mutations at codon 531, 14 had CAC-->TAC or GAC or CCC or CTC or GTC mutations at codon 526, 2 had GAC-->GTC or TAC mutations at codon 516, 2 had two point mutations, and 3 had different rpoB sequences from that of M. tuberculosis.

CONCLUSION

Resistance to rifampicin in most M. tuberculosis isolates is due to the mutations on the genes encoding the RNA polymerase subunit (rpoB). PCR-SSCP and PCR-DS techniques might become simple, rapid and reliable diagnostic tests for rifampicin resistance in clinical isolates.

Functional replacement of the mouse E2A gene with a human HEB cDNA

The mammalian E2A, HEB, and E2-2 genes encode a unique class of basic helix-loop-helix (bHLH) transcription factors that are evolutionarily conserved and essential for embryonic and postnatal development. While the structural and functional similarities among the gene products are well demonstrated, it is not clear why deletion of E2A, but not HEB or E2-2, leads to a complete arrest in B-lymphocyte development. To understand the molecular basis of the functional specificity between E2A and HEB/E2-2 in mammalian development, we generated and tested a panel of E2A knockin mutations including subtle mutations in the E12 and E47 exons and substitution of both E12 and E47 exons with a human HEB cDNA. We find that the alternatively spliced E12 and E47 bHLH proteins of the E2A gene play similar and additive roles in supporting B lymphopoiesis. Further, we find that HEB driven by the endogenous E2A promoter can functionally replace E2A in supporting B-cell commitment and differentiation toward completion. Finally, the postnatal lethality associated with E2A disruption is fully rescued by the addition of HEB. This study suggests that the functional divergence among E12, E47, and HEB in different cell types is partially defined by the context of gene expression.

Synthesis of novel oximes of 2-aryl-6-methoxy-3,4-dihydronaphthalene and their evaluation as inhibitors of 17 alpha-hydroxylase-C17,20-lyase (P450 17)

The synthesis and biological evaluation of oximes of 2-aryl-6-methoxy-3,4-dihydronaphthalene (7a, 7b, 14a, 14b) as nonsteroidal inhibitors of 17 alpha-hydroxylase-C17,20-lyase (P450 17, CYP 17) is described. The target compounds were synthesized and identified by 1H NMR and MS. The preparation of the key intermediates 5a and 5b was accomplished by coupling 4a and 4b with 1 (2-hydroxy-6-methoxy-3,4-dihydronaphthalene-2-trifluoromethanesulfonate) using the palladium complex Pd(PPh3)4 as catalyst. Hydrolysis of 5a and 5b in THF-HCl solution at room temperature gave the corresponding keto compounds 6a and 6b. The other important intermediates--the substituted (E)-2-methyl-ene-1-tetralones 10a and 10b--were obtained by condensation of 1-tetralone with the corresponding aromatic aldehydes (9a and 9b). Hydrogenation (H2), followed by reduction (NaBH4), and subsequent hydrolysis and elimination led to the keto compounds 13a and 13b. The title compounds, the oximes 7a, 7b and 14a, 14b were formed by reaction of hydroxylamine hydrochloride with the corresponding keto compounds. Using a microsomal fraction of human testicular enzyme, 7a, 7b, 14a, and 14b inhibited the target enzyme only marginally.

High incidence of T-cell tumors in E2A-null mice and E2A/Id1 double-knockout mice

The basic-helix-loop-helix (bHLH) proteins encoded by the E2A gene are broadly expressed transcription regulators which function through binding to the E-box enhancer sequences. The DNA binding activities of E2A proteins are directly inhibited upon dimerization with the Id1 gene product. It has been shown that disruption of the E2A gene leads to a complete block in B-lymphocyte development and a high frequency of neonatal death. We report here that nearly half of the surviving E2A-null mice develop acute T-cell lymphoma between 3 to 10 months of age. We further show that disruption of the Id1 gene improves the chance of postnatal survival of E2A-null mice, indicating that Id1 is a canonical negative regulator of E2A and that the unbalanced ratio of E2A to Id1 may contribute to the postnatal death of the E2A-null mice. However, the E2A/Id1 double-knockout mice still develop T-cell tumors once they reach the age of 3 months. This result suggests that E2A may be essential for maintaining the homeostasis of T lymphocytes during their constant renewal in adult life.

[Study on the molecular mechanism of multi-drug resistance in clinical isolates of Mycobacterium tuberculosis]

OBJECTIVE

To study the molecular mechanism of multi-drug resistance in M. Tuberculosis, and to develop a new method for detecting genes related with multi-drug resistance.

METHOD

The ropB, rpsL, katG genes and inhA regulatory sequence in clinical isolates of M. tuberculosis were analyzed with PCR and PCR-SSCP techniques.

RESULT

The sensitivity of amplifing the drug-resistant genes with PCR was 1-10 pg DNA. Of the 20 multiple resistant strains with reduced sensitivity to streptomycin, rifampin and isoniazid, 90% showed mutations in more than two genetic markers associated with resistance to each of these three drugs, 10% revealed only mutations in rpoB gene.

CONCLUSION

Multi-drug resistance in M. tuberculosis could be caused by an accumulation of mutations in chromosomal genes encoding drug targets or an alteration at a single multiple resistance locus. PCR and PCR-SSCP techniques might become simple, rapid and reliable diagnostic tests for multi-drug resistance.

Synthesis of Z- and E-1-methyl-2-(1-hydroximinoethyl)-6-methoxy-3,4-dihydronaphthalene and evaluation as inhibitors of 17 alpha-hydroxylase-C17,20-lyase (P450 17)

The synthesis and biological evaluation of Z- and E-1-methyl-2-(1-hydroximinoethyl)-6-methoxy-3,4-dihydro-naphtha len e (Z-1 and E-1) as nonsteroidal inhibitors of 17 alpha-hydroxylase-C17,20-lyase (P450 17, CYP 17) is described. Z-1 and E-1 were separated by column chromatography and identified by 1H NMR. The synthesis of the key compound 3 was accomplished by a new reaction acetylating the 1-methyl-6-methoxy-3,4-dihydronaphthalene compound 2 under Friedel-Crafts conditions. Compound 2 was obtained from the 1-tetralone via Wittig reaction. Using a microsomal fraction of human testicular enzyme, Z-1 and E-1 inhibited the target enzyme only marginally.

Decreased zinc affinity of amyotrophic lateral sclerosis-associated superoxide dismutase mutants leads to enhanced catalysis of tyrosine nitration by peroxynitrite

Mutations to Cu/Zn superoxide dismutase (SOD) linked to familial amyotrophic lateral sclerosis (ALS) enhance an unknown toxic reaction that leads to the selective degeneration of motor neurons. However, the question of how >50 different missense mutations produce a common toxic phenotype remains perplexing. We found that the zinc affinity of four ALS-associated SOD mutants was decreased up to 30-fold compared to wild-type SOD but that both mutants and wild-type SOD retained copper with similar affinity. Neurofilament-L (NF-L), one of the most abundant proteins in motor neurons, bound multiple zinc atoms with sufficient affinity to potentially remove zinc from both wild-type and mutant SOD while having a lower affinity for copper. The loss of zinc from wild-type SOD approximately doubled its efficiency for catalyzing peroxynitrite-mediated tyrosine nitration, suggesting that one gained function by SOD in ALS may be an indirect consequence of zinc loss. Nitration of protein-bound tyrosines is a permanent modification that can adversely affect protein function. Thus, the toxicity of ALS-associated SOD mutants may be related to enhanced catalysis of protein nitration subsequent to zinc loss. By acting as a high-capacity zinc sink, NF-L could foster the formation of zinc-deficient SOD within motor neurons.

Analysis of the role of E2A-encoded proteins in insulin gene transcription

Pancreatic beta-cell type-specific transcription of the insulin gene is mediated, in part, by factors in the basic helix-loop-helix (bHLH) family that act on a site within the insulin enhancer, termed the E1-box. Expression from this element is regulated by a heteromeric protein complex containing ubiquitous (i.e. the E2A- and HEB-encoded proteins) and islet-enriched members of the bHLH family. Recent studies indicate that the E2A- and HEB-encoded proteins contain a transactivation domain, termed AD2, that functions more efficiently in transfected beta-cell lines. In the present report, we extend this observation by demonstrating that expression of full-length E2A proteins (E47, E12, and E2/5) activates insulin E element-directed transcription in a beta-cell line-selective manner. Stimulation required functional interactions with other key insulin gene transcription factors, including its islet bHLH partner as well as those that act on the RIPE3b1 and RIPE3a2 elements of the insulin gene enhancer. The conserved AD2 domain in the E2A proteins was essential in this process. The effect of the E2A- and HEB-encoded proteins on insulin gene expression was also analyzed in mice lacking a functional E2A or HEB gene. There was no apparent difference in insulin production between wild type, heterozygote, and homozygous mutant E2A or HEB mice. These results suggest that neither the E2A- or HEB-encoded proteins are essential for insulin transcription and that one factor can substitute for the other to impart normal insulin E1 activator function in mutant animals.

[Alkaloid production of cultured coptis cells by two-stage suspension-culture]

In this study the asexual cell line H292 induced and selected from Coptis gulinensis had rapid growth rate and could stably produce alkaloids. By the one-stage method, after the cell suspensions were cultured on the same medium for six weeks, the increased dry and fresh weights of the cells were 20.96 g/L and 174.92 g/L respectively. The content of the total alkaloids in the cells was 14.79 mg/g cell dw. Per litter liquid medium could provide 323 mg alkaloid. In contrast, the cells were cultured by two-stage method. After having been cultured on the medium which contributed to the growth of the cells for three weeks, the cells were transferred to the medium which contributed to the production of the alkaloid and cultured for three weeks. Six weeks later, the dry and fresh weights of the cells were 16.72 g/L and 127.44 g/L, respectively. The biomass was lower than that by one-stage method, but the content of the total alkaloids was as high as 31.76 mg/g cell dw, which was much more than that by one-stage method. In addition, the content of the alkaloid in the medium was 25.31 mg/L. Per litter liquid medium could provide 556 mg alkaloid. The total yield of alkaloid obtained by two-stage method was 1.72 times than that by one-stage method.

[Detection of M. tuberculosis streptomycin-resistant gene]

OBJECTIVE

To observe the mutations of rpsL gene in M. tuberculosis streptomycin-resistant isolates, and to develop a new method for detecting drug resistance.

METHOD

Detecting the rpsL genes with PCR-SSCP and analyzing their codons 43 by PCR-RFLP.

RESULTS

Strain H37Rv was used as a control. In 22 M. tuberculosis clinical isolates, the rpsL PCR fragments from 5 drug-susceptible isolates had no differences in the SSCP profiles with strain H37Rv, and were restricted by Mbo II. 11 of the 13 streptomycin-resistant isolates showed apparent differences in the SSCP profiles and were not digested with Mbo II. 1 of the 4 other drug-resistant isolates also had apparent SSCP differences and was not digested by Mbo II.

CONCLUSIONS

The results suggested that the rpsL gene mutation was frequently observed in M. tuberculosis streptomycin-resistant isolates, and usually situated at codon 43, PCR-SSCP and PCR-RFLP might become a simple, rapid and reliable diagnostic test for drug resistance.

[Application of PCR-SSCP technique in detection of rpoB gene mutation in rifampin-resistant Mycobacterium tuberculosis]

OBJECTIVE

To evaluate rpoB gene mutation in rifampin-resistant Mycobacterium tuberculosis and its relationship with rifampin resistance.

METHODS

Forty clinical isolates of Mycobacterium tuberculosis were analyzed by PCR-SSCP technique, with H37Rv reference strains as control group.

RESULTS

The sensitivity of amplication products of 411bp and 258bp were found to be 5 pg/microliters, 500 organisms per milliliter and 1 pg/microliter, 500 organisms per milliliter respectively. rpoB gene belongs to genus specificity. Characteristics of SSCP graph of 258bp fragment: Ten sensitive strains were the same as H37 Rv. Thirty strains of rifampin-resistant or multidrug resistance, including rifampin, were different from H37Rv except for three strains. Positive rate was 90%, while specificity 100%.

CONCLUSIONS

Results showed that PCR-SSCP technique could detect rPOB gene mutation, which might associate with rifampin resistance and be helpful to rapid detection and research of rifampin-resistant Mycobacterium tuberculosis.