Human AML cells in NOD/SCID mice: engraftment potential and gene expression

Most cases of human acute myeloid leukemia (AML) engraft in irradiated non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice. Intravenous transfer of as few as 10(5) human AML cells resulted in engraftment. Cases with poor prognosis clinical features, including FLT3 mutations, tended to engraft efficiently. Nevertheless, AML cells obtained from patients at relapse did not engraft more efficiently than cells obtained from the same patients at initial diagnosis. One passage of human AML cells in NOD/SCID mice did not appear to select for increased virulence, as measured by serial transplantation efficiency. Finally, cDNA microarray analyses indicated that approximately 95% of genes were expressed at similar levels in human AML cells immunopurified after growth in mice, as compared to cells assessed directly from patients. Thus, the growth of human AML cells in NOD/SCID mice could yield large numbers of human AML cells for direct experimental use and could also function as a renewable, potentially unlimited source of leukemia cells, via serial transplantation.

Soluble Fas gene therapy protects against Fas-mediated apoptosis of hepatocytes but not the lethal effects of Fas-induced TNF-alpha production by Kupffer cells

The elevation of soluble Fas (sFas) in the sera of patients with liver disease suggests a role for sFas in the disease process; whether it is protective or not is controversial. To determine the effects of sFas on Fas-induced liver apoptosis, we manipulated mice to produce sFas by transfecting them in vivo with different amounts of an adenovirus that produces mouse sFas driven by the CMV promoter (AdsFas). Fas-mediated apoptosis was induced by administration of anti-mouse Fas (Jo2; 10 microg/mouse) one week later. The administration of AdsFas (10(3), 10(7), or 10(9) pfu/mouse), which was associated with only minimal side-effects, resulted in a significant reduction in the liver transaminase levels and mortality of the mice on challenge with Jo2, as compared to control mice treated with AdLacZ. However, the protective effect of AdsFas was not complete. The possibility that Jo2-induction of TNF-alpha in the Kupffer cells of the liver contributes to the pathology was therefore tested. Although administration of soluble TNF receptor (sTNFRI) alone did not protect the mice from the lethal effects of Jo2, administration of sTNFRI (200 microg/mouse) after infection with AdsFas (10(9) pfu/mouse) resulted in 100% survival of the mice on challenge with Jo2. To confirm that the production of TNF-alpha by Kupffer cells produce the lethal effects of Jo2 that remained after treatment with AdsFas, these cells were selectively ablated by treatment of the mice with gadolinium chloride prior to challenge with Jo2. This treatment greatly reduced early mortality and hepatocellular damage as well as TNF-alpha production 6 h after injection of Jo2. These results indicate that: (1) AdsFas prevents Jo2-induced apoptosis of hepatocytes; (2) In addition to mediating Fas-mediated apoptosis of hepatocytes, Jo2 can separately induce TNF-alpha production by Kupffer cells resulting in early mortality, and (3) Optimal protection from Jo2-induced mortality can be achieved by protection of liver cells by pretreatment with both AdsFas and sTNFRI.

Mechanisms of the induction of apoptosis in human hepatoma cells by tumour necrosis factor-alpha

Tumour necrosis factor alpha (TNF-alpha) at 20 ng/ml induced apoptosis in human hepatoma cells in vitro. The effect of TNF-alpha-induced apoptosis was exacerbated by the hypoxanthine-xanthine oxidase (HX/XO) system and cycloheximide (CHX), but alleviated by superoxide dismutase (SOD), suggesting that TNF-alpha-induced apoptosis may be due to oxidative stress, and independent of protein synthesis. TNF-alpha elevated free Ca(2+)concentration, triggered lipid peroxidation and decreased the expression of bcl-2 protein. The findings suggest that TNF-alpha-induced apoptosis may be involved in stimulating Ca(2+)-dependent endonuclease activity and increasing membrane lipid peroxidation. Bcl-2 may play a pivotal role in serving as a Ca(2+)regulator or antioxidant, preventing lipid peroxidation in the process.

[Accurate diagnosis of stages of hepatic fibrosis by measuring levels of serum hyaluronic acid, procollagen type III, and collagen type IV]

OBJECTIVE

To study the accurate diagnosis of various stages of hepatic fibrosis by measuring serum hyaluronic acid (HA), procollagen type III (PC III), and collagen type IV (CIV).

METHODS

The concentrations of serum HA, PC III, CIV in 253 patients with chronic liver disease were measured by radioimmunoassay. Liver biopsies were performed in all of the patients at the same time. According to the results of liver pathological diagnosis, we assessed the ability of serum HA, PC III and CIV to identify correctly patients with hepatic fibrosis (staging >or=S(2)) or cirrhosis (S(4)).

RESULTS

The cutoff value of HA, PC III and C IV to identify correctly patients with hepatic fibrosis was 90 microg/L, 90 microg/L, 75 microg/L respectively. The sensitivity (Se) was 80.4%, 82%, 63.1%; the specificity (Spe) was 70.2%, 60.8%, 83.8%; the positive prediction value (PPV) was 86.7%, 83.5%, 90.4%; the negative prediction value (NPV) was 59.8%, 58.4%, 48.4%, respectively. The cutoff value to identify patients with cirrhosis was: HA 210 microg/L, Se 96.2%, Spe 85.3%, PPV 65.4%, NPV 98.8%; PC III 150 microg/L, Se 76.4%, Spe 68.7%, PPV 40.4%, NPV 91.3%; C IV 90 microg/L, Se 80%, Spe 75.8%, PPV 47.8%, NPV 93.2%, respectively.

CONCLUSIONS

The determination of serum HA, PC III and C IV can make relatively accurate diagnosis to various stages of hepatic fibrosis. HA is the best for diagnosis of liver cirrhosis.

Taraxastane-type triterpenoids from Saussurea petrovii

Two taraxastane triterpenoids, i.e. taraxast-20-ene-3beta,30-diol (1) and 20alpha,21alpha-epoxy-taraxastane-3beta,22alpha-diol (2), as well as four known triterpenes taraxast-20(30)ene-3beta,21alpha-diol (3), taraxast-20(30)-ene-3beta-ol (4), taraxast-20-ene-3beta-ol (5) and taraxastane-3beta,20alpha-diol (6) were isolated from the Chinese medicinal plant Saussurea petrovii. Their structures were elucidated by spectroscopic methods. These compounds, especially 1 and 2, exhibit significant antitumor and antibacterial activity.

[Thymoma-report of 166 patients]

OBJECTIVE

To discuss the characteristics of operation and the prognosis of 166 patients with thymoma.

METHODS

166 thymoma patients were treated from February 1985 to February 2000. By Masaoka staging system, there were 102 (61.4%) stage I, 28 (16.9%) stage II, 24 (14.5%) stage III, 12 (7.2%) stage IV a and 0 stage IV b lesions. The relation between stage and survival rate was analyzed.

RESULTS

One (0.6%) patient died of the operation. 137 (82.5%) patients underwent radical operation. Thirty patients were lost to follow-up. With the life table method, the 10-year survival rate was 56.8%, with 79.8% for stage I, 51.6% for stage II, 33.5% for stage III and 0% for stage IV patients.

CONCLUSION

Diagnosis of thymoma still depends on both clinical and pathological findings, which are correlated with stage. The principal treatment is to resect the tumor as completely as possible so as to relieve the symptoms and prolong the life of the patient.

[Fang Chengpei and Zheng's laryngology]

The relationship between Fang Chengpei, a famous physician of the Xin'an school of traditional Chinese medicine and a master of traditional Chinese folk arts of the Qing Dynasty, and successors of Zheng's laryngology of Xin'an was even closer than that between his close relatives and friends. Zheng Meijian imparted laryngological medical skills to Fang, made a preface to Shou Yi Mi Lu (Secret Records of Medical Skills)--a secret document handed down in Fang-family, gave directions to and held discussions with Fang on the doctrine on five elements' motion and six kinds of natural factors. Fang participated in naming, prefacing, and revising Chong Lou Yu Yue (A Jade Key to Laryngeal Diseases) in which three secret recipes for laryngeal diseases that had been handed down in Fang's family were included. Together with Zheng Shufu, he wrote Chong Lou Yu Yue Xu Pian (Continuation of A Jade Key to Laryngeal Diseases). After Fang had passed away, many of his belongings were left in Zhengs' house, including medical documents, calligraphy, music scores, medical instruments, etc. Fang made a great contribution to the academic development of Zheng's Laryngology.

Steady-state and pre-steady-state kinetic analysis of Mycobacterium tuberculosis pantothenate synthetase

Pantothenate synthetase (EC 6.3.2.1), encoded by the panC gene, catalyzes the essential ATP-dependent condensation of D-pantoate and beta-alanine to form pantothenate in bacteria, yeast and plants. Pantothenate synthetase from Mycobacterium tuberculosis was expressed in E. coli, purified to homogeneity, and found to be a homodimer with a subunit molecular mass of 33 kDa. Initial velocity, product, and dead-end inhibition studies showed the kinetic mechanism of pantothenate synthetase to be Bi Uni Uni Bi Ping Pong, with ATP binding followed by D-pantoate binding, release of PP(i), binding of beta-alanine, followed by the release of pantothenate and AMP. Michaelis constants were 0.13, 0.8, and 2.6 mM for D-pantoate, beta-alanine, and ATP, respectively, and the turnover number, k(cat), was 3.4 s(-1). The formation of pantoyl adenylate, suggested as a key intermediate by the kinetic mechanism, was confirmed by (31)P NMR spectroscopy of [(18)O]AMP produced from (18)O transfer using [carboxyl-(18)O]pantoate. Single-turnover reactions for the formation of pyrophosphate and pantothenate were determined using rapid quench techniques, and indicated that the two half-reactions occurred with maximum rates of 1.3 +/- 0.3 and 2.6 +/- 0.3 s(-)(1), respectively, consistent with pantoyl adenylate being a kinetically competent intermediate in the pantothenate synthetase reaction. These data also suggest that both half-reactions are partially rate-limiting. Reverse isotope exchange of [(14)C]-beta-alanine into pantothenate in the presence of AMP was observed, indicating the reversible formation of the pantoyl adenylate intermediate from products.

The novel function of a short region K253xRxxxD259 conserved in the exonuclease domain of hyperthermostable DNA polymerase I from Pyrococcus horikoshii

The DNA polymerase gene of the hyperthermophile Pyrococcus horikoshii was successfully overexpressed after removing an intein. The importance of an amino acid sequence around a highly conserved Asp was studied by site-directed mutagenesis. The results indicated that Lys253, Arg255, and Asp259 form a novel functional motif, K253xRxxxD259 (outside known motifs Exo I, II, and III), that is important not only for exonuclease activity but also for polymerizing activity, confirming functional interdependence between the polymerase and exonuclease domains. The short loop region, K253G254R255, probably contributes to binding to DNA substrates. Moreover, the negative charge and the side-chain length of D259 might play a supporting role in coordinating the conserved Mg2+ to the correct position at the active center in the exonuclease domain.

Divergent immune responses in male and female mice after trauma-hemorrhage: dimorphic alterations in T lymphocyte steroidogenic enzyme activities

Immune responses are suppressed in males, but not in proestrous females, after trauma-hemorrhage. Testosterone and 17beta-estradiol appear to be responsible for divergent immune effects. There is considerable evidence to suggest sex steroid hormone involvement in immune functions. As formation of active steroid depends on the activity of androgen- and estrogen-synthesizing enzymes, expression and activity of 5alpha-reductase, aromatase, and 3beta- and 17beta- hydroxysteroid dehydrogenases were determined in spleen and T lymphocytes of male and proestrous female mice after trauma-hemorrhage. All of the enzymes were present in spleen, specifically in T lymphocytes. 5alpha-Reductase expression and activity increased in male T lymphocytes, whereas aromatase activity, but not expression, increased in female T lymphocytes. Increased 5alpha-reductase activity in male T lymphocytes is immunosuppressive because of increased 5alpha-dihydrotestosterone synthesis, whereas in females increased aromatase activity triggering 17beta-estradiol synthesis is immunoprotective. This study also demonstrates the importance of 17beta-hydroxysteroid dehydrogenase oxidative and reductive functions. The immunoprotection of proestrous females is associated with enhanced reductase function of the enzyme. In males, decreased expression of oxidative isomer type IV, which impairs catabolism of 5alpha-dihydrotestosterone, probably augments immunosuppression. This study provides evidence for the involvement of intracrine sex steroid synthesis in gender dimorphic immune responses after trauma-hemorrhage.

Fast repair of the radical cations of dCMP and poly C by quercetin and rutin

The effects of quercetin and rutin on the repair of the radical cations of dCMP and poly C were studied using the technique of pulse radiolysis. The radical cations of dCMP and poly C were formed by the reaction of dCMP and poly C with SO( 4)(-). After pulse irradiation of nitrogen-saturated aqueous solutions containing dCMP, 20 mM K(2)S(2)O(8), 200 mM t-BuOH and either rutin or quercetin, the initially formed radical cation of dCMP, detected spectrophotometrically, rapidly decayed with the concurrent formation of the phenoxyl radical of rutin or quercetin within 8-40 micros. The repair efficiencies of the tested compounds towards the poly C radical cation were also determined using the same procedure. The results indicate that dCMP and poly C radical cations can be rapidly repaired by quercetin and rutin. The rate constants of the repair reactions were determined to be 4.3-8.8x10(8) M/s and 1.5-3.6x10(8) M/s for dCMP and poly C radical cations, respectively. Together with findings from our previous studies, the present results demonstrate that non-enzymatic fast repair may be a universal form of repair involving phenolic antioxidants.

[Expression and significance of extracellular matrix and cell adhesion molecule in bronchiolo-alveolar carcinoma]

BACKGROUND

To study the expressing features and significance of extracellular matrix(ECM)-laminin(LN),collagen IV(Coll IV),fibronectin(FN) and cell adhesion molecule(A-CAM) in the three subtypes of the bronchiolo-alveolar carcinoma(BAC) and conventional pulmonary adenocarcinoma(CPA).

METHODS

Using immunohistochemical LSAB technique,the distribution and expression of ECM and A-CAM were examined in 50 cases of BAC(including 14 mucinous,22 nonmucinous and 14 sclerosing) and 6 of CPA.

RESULTS

LN,Coll IV and FN in the basement membrane were stained as uninterrupted narrow line in the mucinous BAC and the pulmonary parenchyma adjacent to the carcinoma. In the nonmucinous BAC,ECM showed as irregular tram-track like double layers. The peripheral areas of the sclerosing BAC was virtually identical in staining pattern to the nonmucinous,and the central areas,which showed disrupted or absent in the basement membrane surrounding the glands embedded in the fibrous stroma,was similar to that of CPA. The frequency of A-CAM expression in BAC and CPA was 60%(30/50) and 83% (5/6) respectively, with no significant correlation found(P>0.05). The percentage of A-CAM in three BAC subtypes was 43%(6/14),55%(12/22) and 86%(12/14),which appeared as increased tendency. There was a significant difference between the mucinous and sclerosing BAC(P<0.05),while the sclerosing BAC was close to CPA.

CONCLUSIONS

On the basis of the distribution and expression of ECM and A-CAM,BAC should be taken as a subtype of CPA. The mucinous BAC may be a real BAC. Perhaps there is some differentiation correlation among three subtypes of BAC and CPA.

Exposure to westernization and dieting: a cross-cultural study

OBJECTIVES

The study aimed to establish whether an index of exposure to westernization would predict dieting behavior over and above the predictors of body mass index (BMI) and social influences. The study also sought to compare dieting behaviors among adolescents from three different cultural backgrounds.

METHOD

A total of 100 females from Beijing, China, 60 females of Chinese heritage living in Sydney, Australia, and 100 female Australians of no Chinese background were assessed. The exposure to westernization index incorporated the country of birth, the predominant language spoken at home, the country of birth of one's parents, and the country of residence.

RESULTS

Exposure to westernization was found to be a significant predictor of dieting status. The westernization index remained an important predictor when BMI and social influences to diet were taken into account. Interestingly, the Chinese Australian girls dieted the least, although the Chinese girls living in China perceived more influence from their peers to diet, despite their lower BMI.

CONCLUSION

The exposure to westernization index provides a useful assessment of important influences on dieting in adolescent females.

SeO(2) induces apoptosis with down-regulation of Bcl-2 and up-regulation of P53 expression in both immortal human hepatic cell line and hepatoma cell line

An immortal human hepatic cell line HL-7702 and human hepatoma cell line SMMC-7721 were treated with 3-30 microM SeO(2). SeO(2) at 30 microM markedly inhibited cell proliferation and viability, and prompted apoptosis of both normal hepatic and hepatoma cells after 48h treatment. SeO(2) could also down-regulate the Bcl-2 level, greatly in HL-7702 and slightly in SMMC-7721 cells, but up-regulate wild type P53 level a little in HL-7702 and significantly in SMMC-7721 cells. The Bcl-2/P53 value was closely correlated with the apoptotic rate as well as SeO(2) concentrations.

Identification of active site residues in E. coli ketopantoate reductase by mutagenesis and chemical rescue

Ketopantoate reductase (EC 1.1.1.169) catalyzes the NADPH-dependent reduction of alpha-ketopantoate to D-(-)-pantoate in the biosynthesis of pantothenate. The pH dependence of V and V/K for the E. coli enzyme suggests the involvement of a general acid/base in the catalytic mechanism. To identify residues involved in catalysis and substrate binding, we mutated the following six strictly conserved residues to Ala: Lys72, Lys176, Glu210, Glu240, Asp248, and Glu256. Of these, the K176A and E256A mutant enzymes showed 233- and 42-fold decreases in V(max), and 336- and 63-fold increases in the K(m) value of ketopantoate, respectively, while the other mutants exhibited WT kinetic properties. The V(max) for the K176A and E256A mutant enzymes was markedly increased, up to 25% and 75% of the wild-type level, by exogenously added primary amines and formate, respectively. The rescue efficiencies for the K176A and E256A mutant enzymes were dependent on the molecular volume of rescue agents, as anticipated for a finite active site volume. The protonated form of the amine is responsible for recovery of activity, suggesting that Lys176 functions as a general acid in catalysis of ketopantoate reduction. The rescue efficiencies for the K176A mutant by primary amines were independent of the pK(a) value of the rescue agents (Bronsted coefficient, alpha = -0.004 +/-0.008). Insensitivity to acid strength suggests that the chemical reaction is not rate-limiting, consistent with (a) the catalytic efficiency of the wild-type enzyme (k(cat)/K(m) = 2x10(6) M(-1) s(-1) and (b) the small primary deuterium kinetic isotope effects, (D)V = 1.3 and (D)V/K = 1.5, observed for the wild-type enzyme. Larger primary deuterium isotope effects on V and V/K were observed for the K176A mutant ((D)V = 3.0, (D)V/K = 3.7) but decreased nearly to WT values as the concentration of ethylamine was increased. The nearly WT activity of the E256A mutant in the presence of formate argues for an important role for this residue in substrate binding. The double mutant (K176A/E256A) has no detectable ketopantoate reductase activity. These results indicate that Lys176 and Glu256 of the E. coli ketopantoate reductase are active site residues, and we propose specific roles for each in binding ketopantoate and catalysis.

[Hostility behavior as risk factor of coronary heart disease]

OBJECTIVE

To explore the relationships between hostility, and the risks of coronary-prone behavior and the clusters of unhealthy behaviors in individuals with different levels of hostility.

METHODS

A cross-sectional study was carried out among 1 010 male employees from two factories in Beijing Capital Steel and Iron Company in 1997. Data on major risks of cardiovascular, other social-demographic factors and levels of hostility by Cook-Medley Scales were collected.

RESULTS

Body mass index, amounts of cigarette smoking and alcohol drinking were significantly increased (P < 0.01) with a characteristic of reduced social support from one's colleagues, when individual's level of hostility increased. In addition, less years of education, higher prevalence of other chronic diseases (P < 0.05) and clustering of various unhealthy behaviors were found related to the increase of individual's hostility. The odds ratio in the group with highest hostility was 2.37 times higher than in the lowest one, after confounding effects from age, blood pressure, education level, status of chronic disease and social support being adjusted. No significant differences on both systolic and diastolic blood pressures among groups with different levels of hostility were discovered.

CONCLUSION

The association between hostility, coronary-prone risk behavior and cluster of unhealthy behaviors suggested that hostility might increase the risk of coronary heart diseases through affecting individual's behavior.

XPD/ERCC2 polymorphisms and risk of head and neck cancer: a case-control analysis

DNA repair capacity is central in maintaining normal cellular functions. Variants of several DNA repair genes,including the nucleotide excision repair gene XPD, have been described recently. Because we previously reported that patients with squamous cell carcinoma of the head and neck (SCCHN) had lower DNA repair capacity than healthy controls, we hypothesized that inherited polymorphisms of XPD may contribute to genetic susceptibility to SCCHN, a tobacco-related cancer. To test this hypothesis, we conducted a hospital-based case-control study of 189 SCCHN patients and 496 cancer-free controls who were frequency-matched on age, gender and smoking status. All subjects were non-Hispanic whites. Two XPD polymorphisms (C22541A and A35931C) were typed using the restriction enzymes TfiI and PstI, respectively. Multivariate logistic regression analysis was performed to calculate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). In the controls, the frequencies of the variant 22541A and 35931C alleles were 44.7% and 33.8%, respectively. The frequency of the 22541A homozygous genotype (22541AA) was lower in cases (15.9%) than in controls (20.4%) but was not associated with risk (adjusted OR = 0.90; 95% CI = 0.52-1. 56) for SCCHN. The frequency of the 35931C homozygous genotype (35931CC) was higher in cases (16.4%) than in controls (11.5%) and associated with a borderline increased risk (adjusted OR = 1.55; 95% CI = 0.96-2.52) for SCCHN. The risk was higher in older subjects (OR = 2.22; 95% CI = 1.03-4.80), current smokers (OR = 1.83; 95% CI = 0.79-4.27) and current drinkers (OR = 2.59; 95% CI = 1.25-5.34) in the stratification analysis. These results suggest a gene-environment interaction, but this did not reach statistical significance. The findings are limited due to the relatively small numbers in the subgroups and need to be verified by further investigations.

Vinylogous amide analogues of diaminopimelic acid (DAP) as inhibitors of enzymes involved in bacterial lysine biosynthesis

[reaction: see text] Vinylogous amides 5 and 6 have been synthesized from L-propargyl glycine and tested against diaminopimelate (DAP) enzymes involved in bacterial lysine biosynthesis. Both are reversible inhibitors of DAP D-dehydrogenase and DAP epimerase with IC(50) values in the 500 microM range. Compound 5 shows competitive inhibition against the L-dihydrodipicolinate (DHDP) reductase with a K(i) value of 32 microM, which is comparable to the planar dipicolinate 16 (K(i) = 26 microM), the best known inhibitor of the enzyme.

Barrier-to-autointegration factor (BAF) bridges DNA in a discrete, higher-order nucleoprotein complex

Barrier-to-autointegration factor (BAF) is a highly conserved cellular protein that was identified by its activity in protecting retroviral DNA against autointegration. We show that BAF has the property of bridging double-stranded DNA in a highly ordered nucleoprotein complex. Whereas BAF protein alone is a dimer in solution, upon binding DNA, BAF forms a dodecamer with DNA bound at multiple discrete sites in the complex. The interactions between BAF and DNA are entirely nonspecific with respect to DNA sequence. The dual interaction of BAF with DNA and LAP2, a protein associated with the nuclear lamina, suggests a role for LAP2 in chromosome organization. Consistent with this idea, RNA interference experiments with Caenorhabditis elegans reveal a defect in mitosis.

[The relationship between the levels of serum fibrosis marks and morphometric quantitative measurement of hepatic histological fibrosis]

OBJECTIVE

To study the relationship between the levels of serum fibrosis marks hyaluronic acid (HA), procollagen type III (PCIII), collagen type IV (CIV) and the degree of hepatic fibrosis, and the clinical significance of HA, PCIII, CIV in the diagnosis of hepatic fibrosis to the chronic viral hepatitis.

METHODS

The concentrations of serum HA, PCIII, CIV in 151 patients with chronic viral hepatitis were measured by radioimmunoassay. Liver biopsies were performed in all of the patients at the same time. Morphometric quantitative measurements of hepatic fibrosis were performed in 4mum sections stained with masson stain using a fully automated image-analysis system.

RESULTS

The levels of serum HA, PCIII, CIV were all increased steadily with the progression of hepatic fibrosis, and the highest levels were in stage 4. They were all positively correlated with staging of the liver pathology and morphometric measurement of hepatic fibrosis (P<0.001). The coefficient value (r) with staging were 0.694, 0.493, 0.552 (P<0.001), respectively and with morphometric measurement of hepatic fibrosis were 0.715, 0.596, 0.537 (P<0.001), respectively.

CONCLUSION

The levels of serum HA, PCIII, CIV are in concert with the degree of hepatic fibrosis, and the determination of these marks may be valuable for diagnosing hepatic fibrosis.

Fast repair of dAMP radical anions by phenylpropanoid glycosides and their analogs

Repair effect on 2'-deoxyadenosine-5'-monophosphate (dAMP) radical anions by phenylpropanoid glycosides (PPGs) and their analogs, isolated from Chinese folk medicinal herb, was studied using pulse radiolysis technique. The radical anion of dAMP was formed by the reaction of hydrated electron with dAMP. On pulse irradiation of nitrogen-saturated dAMP aqueous solution containing 0.2 M t-BuOH and one of PPGs or their analogs, the transient absorption spectrum of the radical anion of dAMP decayed with the formation of that of the radical anion of PPGs or their analogs within several decades of microseconds after electron pulse irradiation. The results indicated that dAMP radical anions can be repaired by PPGs or their analogs. The rate constants of the repair reactions were deduced to be 1.6-4.5 x 10(8) M(-1) s(-1).

Kinetic and mechanistic analysis of the E. coli panE-encoded ketopantoate reductase

Ketopantoate reductase (EC 1.1.1.169) catalyzes the NADPH-dependent reduction of alpha-ketopantoate to form D-(-)-pantoate in the pantothenate/coenzyme A biosynthetic pathway. The enzyme encoded by the panE gene from E. coli K12 was overexpressed and purified to homogeneity. The native enzyme exists in solution as a monomer with a molecular mass of 34 000 Da. The steady-state initial velocity and product inhibition patterns are consistent with an ordered sequential kinetic mechanism in which NADPH binding is followed by ketopantoate binding, and pantoate release precedes NADP(+) release. The pH dependence of the kinetic parameters V and V/K for substrates in both the forward and reverse reactions suggests the involvement of a single general acid/base in the catalytic mechanism. An enzyme group exhibiting a pK value of 8.4 +/- 0.2 functions as a general acid in the direction of the ketopantoate reduction, while an enzyme group exhibiting a pK value of 7.8 +/- 0.2 serves as a general base in the direction of pantoate oxidation. The stereospecific transfer of the pro-S hydrogen atom of NADPH to the C-2 position of ketopantoate was demonstrated by (1)H NMR spectroscopy. Primary deuterium kinetic isotope effects of 1.3 and 1.5 on V(for) and V/K(NADPH), respectively, and 2.1 and 1.3 on V(rev) and V/K(HP), respectively, suggest that hydride transfer is not rate-limiting in catalysis. Solvent kinetic isotope effects of 1.3 on both V(for) and V/K(KP), and 1.4 and 1.5 on V(rev) and V/K(HP), respectively, support this conclusion. The apparent equilibrium constant, K(eq)', of 676 at pH 7.5 and the standard free energy change, DeltaG, of -14 kcal/mol suggest that ketopantoate reductase reaction is very favorable in the physiologically important direction of pantoate formation.

A survey on knowledge and skills in the early diagnosis of leprosy in general health services at different levels in Shandong Province, The People's Republic of China

In the late phase of a leprosy control programme, problems arise with regard to the early detection and treatment of a small number of new incident cases. We describe a study in the province of Shandong, People's Republic of China, on the knowledge and skills regarding leprosy of general health service staff, including rural doctors, paramedical doctors at township level, doctors from county general and provincial hospitals and dermatologists. The results showed that there is a continuing need for suitable training programmes for medical staff in the general health services. Most dermatologists had good levels of knowledge and skills and more than 80% of new cases have been diagnosed in skin clinics in this province since 1990. Their participation in early diagnosis and training of staff should be strengthened.

Hydrogen peroxide-induced apoptosis in human hepatoma cells is mediated by CD95(APO-1/Fas) receptor/ligand system and may involve activation of wild-type p53

Reactive oxygen species (ROS) play an important role in cell death induced by many different stimuli. Direct exposure of human hepatoma cell line SMMC-7221 to hydrogen peroxide (H2O2) can induce apoptosis characterized by morphological evidence and fragmentation of DNA assayed by terminal deoxynucleotidyl transferase assay (TUNEL assay). Analysis of flow cytometry indicated that H2O2 can decrease the level of CD95(APO-1/Fas), and it is confirmed that H2O2 can also activate the differential expression of some specific gene such as p53 by means of RT-PCR technique. The results indicated that CD95 signal transduction system may be involved in the H2O2-induced apoptosis, and can regulate some specific genes associated with apoptosis in transcription and translation levels such as p53.

Polymorphisms of DNA repair gene XRCC1 in squamous cell carcinoma of the head and neck

Because reduced DNA repair capacity (phenotype) has been suggested as a risk factor for squamous cell carcinoma of the head and neck (SCCHN), newly-identified DNA repair gene polymorphisms (genotype) may also be implicated in risk. To test this hypothesis, we conducted a case-control study of 203 SCCHN patients and 424 control subjects (matched for age, sex and ethnicity) to investigate the role of two XRCC1 polymorphisms (XRCC1 26304 T and XRCC1 28152 A, respectively) in SCCHN. Multivariate logistic regression analysis was performed to calculate the adjusted odds ratio (OR) and 95% confidence interval (CI). A total of 180 cases (88.7%) and 363 controls (85.6%) lacked the XRCC1 26304 T allele [adjusted OR = 1.34 (CI, 0.80-2.25)]. Lack of this polymorphism was a significant risk factor specifically for cancers of the oral cavity and pharynx [adjusted OR = 2.46 (CI, 1.22-4.97)]. Thirty-two cases (15.8%) and 46 controls (10.8%) were homozygous for the XRCC1 28152 A allele [adjusted OR = 1.59 (CI, 0.97-2.61) for all cases, and 1.41 (CI, 0. 80-2.48) for oral and pharyngeal cancer only]. Furthermore, when the two genotypes were combined into a three-level model of risk, a polymorphism-polymorphism interaction of increasing risk (trend test, P = 0.049) was evident: OR = 1.0 for those with neither risk genotype (referent group), adjusted OR = 1.51 (CI, 0.87-2.61) for those with either risk genotype, and 2.02 (CI, 1.00-4.05) for those with both risk genotypes. For oral and pharyngeal cancer, this trend was even more pronounced with the adjusted OR = 2.68 (CI, 1.28-5.61) for those with either risk genotype, and 3.22 (CI, 1.33-7.81) for those with both risk genotypes. The findings support the hypothesis that a polymorphic XRCC1 DNA repair gene contributes to risk of developing SCCHN.

Fast repair of hydroxy radical purine deoxynucleotide adducts by phenylpropanoid glycosides and their derivatives from Chinese herbs

DNA damaged by oxygen radicals has been implicated as a causative event in a number of degenerative diseases, including cancer and aging. So it is very significant to look for ways in which either oxygen radicals are scavenged prior to DNA damage or damaged DNA is repaired to supplement the cells' inadequate repair capacity. The repair activities and reaction mechanism of phenylpropanoid glycosides (PPGs) and their derivatives, isolated from Chinese folk medicinal herbs, towards both dGMP-OH* adducts and dAMP-OH* adducts were studied with the pulse radiolytic technique. On pulse irradiation of nitrous oxide saturated 2 mM dGMP or dAMP aqueous solution containing one of the PPGs or their derivatives, the transient absorption spectra of the hydroxyl adduct of dGMP or dAMP decayed with the formation of that of phenoxyl radicals of PPGs or their derivatives within several decades of microseconds after electron pulse irradiation. The result indicated that dGMP or dAMP hydroxyl adducts can be repaired by PPGs or their derivatives. The rate constants of the repair reactions were deduced to be 0.641-1.28 x 10(9) M(-1) s(-1) for dGMP-OH* and 0.2-0.491 x 10(9) M(-1) s(-1) for dAMP-OH*, which positively correlated to the number of phenolic hydroxyl groups in the glycoside structure. A deeper understanding of this new repair mechanism may help researchers to design strategies to prevent and/or intervene more effectively in free radical related diseases.

Fast repair of deoxynucleotide radical cations by phenylpropanoid glycosides (PPGs) and their analogs

The repair effects on deoxynucleotide radical cations of phenylpropanoid glycosides (PPGs) and their analogs, isolated from a Chinese folk medicinal herb, were studied using the pulse radiolysis technique. The radical cations of deoxynucleotides were formed by the reaction of SO4*- with deoxynucleotides. On pulse irradiation of a nitrogen saturated deoxynucleotide aqueous solution containing 20 mM K2S2O8, 200 mM t-BuOH and one of the PPGs or their analogs, the transient absorption spectra of the radical cations of nucleotide decayed with the formation of those of the radical cation of PPGs or their analogs within several tens of microseconds after electron pulse irradiation. The result indicates that deoxynucleotide radical cations can be repaired by PPGs or their analogs. The rate constants of the repair reactions were determined to be 0.48-1.1 x 10(9), 0.64-1.80 x 10(9) and 2.12-4.4 x 10(9) M(-1) s(-1) for dAMP, dGMP and dCMP radical cations respectively. It is obvious that the rate constants of the repair reaction depend on the number of phenolic hydroxyl groups contained in the PPGs and their analogs. A deeper understanding of this new repair mechanism will undoubtedly help researchers design strategies to prevent and/or intervene more effective in free radical related diseases.

Interleukin-2 expression by a subpopulation of primary T cells is linked to enhanced memory/effector function

Single cell studies have identified intraclonal heterogeneity of cytokine production by activated T cells. To investigate implications of cytokine heterogeneity for cell fate, an interleukin (IL)-2 promoter-green fluorescent protein (GFP) reporter transgenic model was developed to track IL-2+ and IL-2- T cells during differentiation from naive precursors. Antigen-activated IL-2+ and IL-2- cells had comparable proliferative capacities in primary responses. However, T cells that expressed IL-2 in primary responses demonstrated enhanced antigenic sensitivity and increased expression of effector cytokines in secondary responses in vitro and in vivo. Thus, heterogeneity of activation during a primary response translates into heterogeneous secondary responses, in which enhanced memory/effector function is linked to cells that previously exceeded an activation threshold associated with IL-2 gene transcription.

Technology evaluation: GEM-92, Hybridon Inc

Hybridon is developing GEM-92, a second generation, orally administered antisense oligonucleotide directed against the gag gene in HIV-1 mRNA, as a potential treatment for HIV-1 infection and AIDS 11973841. It is a follow-up compound to GEM-91, which was discontinued due to dose-limiting toxicities [256660]. GEM-92 is undergoing phase I trials in the UK, in approximately 13 healthy volunteers. Hybridon intends to administer a single oral dose at one of three dose levels, while a fourth group will receive a single intravenous dose, in order to determine differences between oral and intravenous administration [263095]. GEM-92 has demonstrated significant inhibition of HIV-1 replication in various cell culture systems, and increased stability in comparison with GEM-91 [219621]. Hybridon has been issued two US patents; US-05652355 and US-05652356, claiming chemically advanced mixed backbone oligonucleotides [257135].

[Influence of radiation on the blood-brain barrier and optimum time of chemotherapy]

OBJECTIVE

A pilot study of the destructive effects of radiation on the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB) were carried out on 29 patients.

METHODS

(1) First BBB with localized and limited brain tumors was examined by 99mTc-GH imaging count/pixel, data was obtained from the unirradiated, irradiated, and tumor areas of before and after radiotherapy of 20-40 Gy respectively. (2) The BCSFB was studied quantitatively by observing the effect of methotrexate (MTX) permeation into the CSF before, during, and after brain irradiated after i.v. injection of MTX.

RESULTS

(1) the BBB in the unirradiated area outside the radiation portal was not changed, (2) the degree of destructive effect on the BBB in the irradiated normal area and on the BCSFB were directly proportional to radiation doses.

CONCLUSIONS

When the permeation of BBB and BCSFB irradiated, was enhanced the degree of destructive effect were enhanced proportionally with irradiation doses. It was that the BBB irradiated can be recovered at least partially after irradiation of 3 weeks proved. After a dose of 20 Gy irradiation, the BCSFB would gradually open. As compared with the pre-radiation data, the permeability of MTX increased by 1.05-1.3 times. So, it was advisable to give chemotherapy after 20 Gy irradiation.

Human immunodeficiency virus-1 infection requires pertussis toxin sensitive G-protein-coupled signalling and mediates cAMP downregulation

The human immunodeficiency virus-1 (HIV-1) utilises CD4 and certain beta-chemokine receptors, mainly CCR-5 and CXCR4, for attachment and virus entry into T-lymphocytes and monocytes/macrophages. CD4 and beta-chemokine receptors participate in intracellular signalling via protein tyrosine kinases and G-protein-coupled signalling. The factors which influence HIV-1 replication and the intracellular signalling mechanisms elicited by the virus are not well understood. In this study, it was demonstrated that exposure of peripheral blood lymphocytes (PBLs) to a T-cell tropic strain of HIV-1 evokes signal(s) which results in downregulation of intracellular cAMP. In addition, pre-incubation of PBLs with the Gi-protein inhibitor Pertussis toxin mediated a significant inhibition of HIV-1 replication. These data strongly suggest that HIV-1 employs CD4 receptors and Gi-coupled proteins for entry into target cells and that productive HIV-1 infection is dependent on an active signalling event.

Chemokines in infection and inflammatory disease--the Royal Society of Medicine

This well-organized meeting covered many clinical and academic areas related to chemokines and their receptors. Speakers from both sides of the Atlantic attended, including distinguished scientists and clinicians from both academic and pharmaceutical institutions. Although the meeting did not reveal sensational research data, it provided a forum in which attendees could express their views, using their research results as confirmation. Currently, the pathogenic and therapeutic roles of chemokines, and in particular their receptors, are clearer, although they are still not fully understood in HIV/AIDS and inflammatory diseases, such as rheumatoid arthritis and asthma. Progress will only be made with further research in order to reveal the importance and therapeutic value of these molecules. In this sense, the meeting provided good food for thought, with suggestions of possible targets and the discussion of various applications of research findings.

Technology evaluation: HIVAC-1e

Bristol-Myers Squibb is developing a vaccine, HIVAC-1e, comprised of a recombinant vaccinia virus expressing the HIV-1 gp160 envelope glycoprotein. The vaccine has potential for the treatment of HIV and other viral infections and has entered phase I trials [135333]. In an initial phase I trial, 11 vaccinia-naïve volunteers were vaccinated with HIVAC-1e, followed by a booster with baculovirus-derived gp160 (VaxSyn). Two weeks after boosting, all 11 volunteers developed HIV-1 specific IgG, with titers of 1:40 to 1:1280 [195287]. Using the same strategy in 29 vaccinia-naïve volunteers, priming with HIVAC-1e was demonstrated as a key determinant of the epitope specificity and magnitude of antibody responses to gp160 [195278].

Role of superoxide anion on the proliferation and c-Ha-ras or p53 expression in prostate cancer cell line PC3

The purpose of this study was to investigate the role of superoxide anion (02-*) in the regulation of p53 or c-Ha-ras expression and proliferation in the prostate cancer cell line PC3. Cell proliferation was tested by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in the presence of O2-*, basic fibroblast growth factor (bFGF) or their combination. p53 or C-Ha-ras expression in the cells treated with O2-* was assayed by fluorescence in situ hybridization (FISH). The proliferation was significantly inhibited by O2-* in a concentration-dependent manner ranging from 9 to 36 micromol/l nicotinamide adenine dinucleotid (NADH) combined with 2-8 micromol/l N-methylphenazonium methyl sulfate (PMS). Enhancement of proliferation by 2 ng/ml bFGF was significantly inhibited by O2-*. Although O2-* was not able to alter c-Ha-ras gene expression, O2-* at the concentrations of 18 micromol/l NADH and 4 micromol/l PMS upregulated the expression of p53. O2-* may modulate proliferation and gene expression in PC3 cells.

Solution structure of the His12 --> Cys mutant of the N-terminal zinc binding domain of HIV-1 integrase complexed to cadmium

The solution structure of His12 --> Cys mutant of the N-terminal zinc binding domain (residues 1-55; IN(1-55)) of HIV-1 integrase complexed to cadmium has been solved by multidimensional heteronuclear NMR spectroscopy. The overall structure is very similar to that of the wild-type N-terminal domain complexed to zinc. In contrast to the wild-type domain, however, which exists in two interconverting conformational states arising from different modes of coordination of the two histidine side chains to the metal, the cadmium complex of the His12 --> Cys mutant exists in only a single form at low pH. The conformation of the polypeptide chain encompassing residues 10-18 is intermediate between the two forms of the wild-type complex.

Structural symmetry: the three-dimensional structure of Haemophilus influenzae diaminopimelate epimerase

The Haemophilus influenzae diaminopimelate epimerase was cloned, expressed, purified, and crystallized in the C2221 space group (a = 102.1 A, b = 115.4 A, c = 66.3 A, alpha = beta = gamma = 90 degrees). The three-dimensional structure was solved to 2.7 A using a single Pt derivative and the Se-Met-substituted enzyme to a conventional R factor of 19.0% (Rfree = 24.2%). The 274 amino acid enzyme consists of two structurally homologous domains, each containing eight beta-strands and two alpha-helices. Diaminopimelate epimerase is a representative of the PLP-independent amino acid racemases, for which no structure has yet been determined and substantial evidence exists supporting the role of two cysteine residues as the catalytic acid and base. Cys73 of the amino terminal domain is found in disulfide linkage, at the domain interface, with Cys217 of the carboxy terminal domain, and we suggest that these two cysteine residues in the reduced, active enzyme function as the acid and base in the mechanism.

Solution structure of the cellular factor BAF responsible for protecting retroviral DNA from autointegration

The solution structure of the human barrier-to-autointegration factor, BAF, a 21,000 Mr dimer, has been solved by NMR, including extensive use of dipolar couplings which provide a priori long range structural information. BAF is a highly evolutionarily conserved DNA binding protein that is responsible for inhibiting autointegration of retroviral DNA, thereby promoting integration of retroviral DNA into the host chromosome. BAF is largely helical, and each subunit is composed of five helices. The dimer is elongated in shape and the dimer interface comprises principally hydrophobic contacts supplemented by a single salt bridge. Despite the absence of any sequence similarity to any other known protein family, the topology of helices 3-5 is similar to that of a number of DNA binding proteins, with helices 4 and 5 constituting a helix-turn-helix motif. A model for the interaction of BAF with DNA that is consistent with structural and mutagenesis data is proposed.

Mechanisms of isoniazid resistance in Mycobacterium tuberculosis: enzymatic characterization of enoyl reductase mutants identified in isoniazid-resistant clinical isolates

Mutants in the structural gene of the inhA-encoded NADH-dependent 2-trans enoyl-acyl carrier protein reductase were identified from isoniazid-resistant clinical isolates of Mycobacterium tuberculosis. Recombinant InhA proteins with defined single amino acid replacements were expressed in Escherichia coli and purified to homogeneity. Steady-state kinetic parameters for wild type (WT) and I16T, I21V, I47T, and I95P mutants of the enoyl reductase were measured spectrophotometrically. NADH binding to WT and I16T, I21V, I47T, S94A, and I95P mutant reductases were determined by fluorescence spectroscopy and demonstrated that all mutant enzymes had reduced NADH affinity and that NADH binding to all mutants was cooperative as compared with the hyperbolic binding of NADH to the WT enzyme. Since KatG-produced electrophilic derivatives of isoniazid have been suggested to inactivate the enoyl reductase-NADH complex, the kinetics of inactivation for the WT and I21V and I95P mutants was determined. Both mutations resulted in significantly increased values for the apparent first-order rate constant of inactivation.

Hydrolysis of N-succinyl-L,L-diaminopimelic acid by the Haemophilus influenzae dapE-encoded desuccinylase: metal activation, solvent isotope effects, and kinetic mechanism

Hydrolysis of N-succinyl-L,L-diaminopimelic acid by the dapE-encoded desuccinylase is required for the bacterial synthesis of lysine and meso-diaminopimelic acid. We have investigated the catalytic mechanism of the recombinant enzyme from Haemophilus influenzae. The desuccinylase was overexpressed in Escherichia coli and purified to homogeneity. Steady-state kinetic experiments verified that the enzyme is metal-dependent, with a Km for N-succinyl-L,L-diaminopimelic acid of 1.3 mM and a turnover number of 200 s-1 in the presence of zinc. The maximal velocity was independent of pH above 7 but decreased with a slope of 1 below pH 7. The pH dependence of V/K was bell-shaped with apparent pKs of 6.5 and 8.3. Both L,L- and D,L-diaminopimelic acid were competitive inhibitors of the substrate, but d,d-diaminopimelic acid was not. Solvent kinetic isotope effect studies yielded inverse isotope effects, with values for D2OV/K of 0.62 and D2OV of 0.78. Determination of metal stoichiometry by ICP-AES indicated one tightly bound metal ion, while sequence homologies suggest the presence of two metal binding sites. On the basis of these observations, we propose a chemical mechanism for this metalloenzyme, which has a number of important structurally defined homologues.

[The study of changes of basement membrane in gingivae of adult periodontitis]

The major components of basement membrane including laminin and type IV collagen were studied by immunohistochemistry in 20 gingival specimens from patients with moderate to severe adult periodontitis and 10 normal gingival specimens combing with electron microscopic and PAS analysis. The results showed that laminin and type IV collagen were both present and stained with a continuous liner pattern in oral sulcular epithelium of the normal gingivae, while the pocket epithelial alterations of the periodontitis occurred, which included thinning, interruption, partial or complete absence of basement membrane involving one or more rete pegs and fragmentations. All these alterations may play an important role in the pathogenesis of adult periodontitis.

[An experimental research of recombinant human epidermal growth factor on corneal wound healing]

OBJECTIVE

To investigate the effects of recombinant human epidermal growth factor (rhEGF) eye drops on corneal wound healing.

METHODS

Twenty-four white rabbits were randomly divided into 4 groups, 6 rabbits 12 eyes each. Anterior keratectomy of 8 mm in diameter and 1/3 cornea in thickness was performed on each eye. Each of the following concentrations of rhEGF: 1, 10, 100 microg/ml eye drops or normal saline (control) was applied four times daily for a week respectively for one group. The wound area was determined by computer imaging analysis.

RESULTS

The mean epithelial healing rate of rhEGF 1, 10, 100 microg/ml groups was 9.31, 9.96, 9.31 mm(2)/day respectively, significantly greater than 8.11 mm(2)/day of the control group. The action of rhEGF of 10 microg/ml was somewhat better than that of 1 or 100 microg/ml, and no significant difference was noticed among the three rhEGF groups. Moderate inflammation and corneal neovascularization were induced in the rhEGF 100 microg/ml treated group.

CONCLUSION

rhEGF 1 - 10 microg/ml can accelerate corneal wound healing in the rabbit with no adverse side-effects. It may be used to treat serious corneal trauma and ulcer clinically.

[Determination of Ni and Pd in white karat gold jewellery by the EDXRF extrapolate-regression method]

The EDXRF extrapolate-regression method described in this paper combines regression method with the fundamental formula of fluorescence intensity. The contents of Ni and Pd in white karat gold jewellery were calculated theoretically according to the spectrum of the sample. The content of gold was deternined without standards. The precision was 0.1% and the deviation was 0.3% compared with AA.

Three-dimensional structure of Escherichia coli dihydrodipicolinate reductase in complex with NADH and the inhibitor 2,6-pyridinedicarboxylate

Dihydrodipicolinate reductase catalyzes the NAD(P)H-dependent reduction of the alpha,beta-unsaturated cyclic imine dihydrodipicolinate to form the cyclic imine tetrahydrodipicolinate. The enzyme is a component of the biosynthetic pathway that leads to diaminopimelate and lysine in bacteria and higher plants. Because these pathways are unique to microorganisms and plants, they may represent attractive targets for new antimicrobial or herbicidal compounds. The three-dimensional structure of the ternary complex of Escherichia coli dihydrodipicolinate reductase with NADH and the inhibitor 2,6-pyridinedicarboxylate has been solved using a combination of molecular replacement and noncrystallographic symmetry averaging procedures and refined against 2.6 A resolution data to a crystallographic R-factor of 21.4% (Rfree is 29.7%). The native enzyme is a 120 000 molecular weight tetramer of identical subunits. The refined crystallographic model contains a tetramer, three molecules of NADH, three molecules of inhibitor, one phosphate ion, and 186 water molecules per asymmetric unit. Each subunit consists of two domains connected by two flexible hinge regions. While three of the four subunits of the tetramer have a closed conformation, in which the nicotinamide ring of the cofactor bound to the N-terminal domain and the reducible carbon of the substrate bound to the substrate binding domain are about 3.5 A away, the fourth subunit is unliganded and shows an open conformation, suggesting that the enzyme undergoes a major conformational change upon binding of both substrates. The residues involved in binding of the inhibitor and the residues involved in catalysis have been identified on the basis of the three-dimensional structure. Site-directed mutants have been used to further characterize the role of these residues in binding and catalysis. A chemical mechanism for the enzyme, based on these and previously reported data, is proposed.

Differentiation of human gastric adenocarcinoma cell line MGc80-3 induced by verbascoside

Verbascoside is a natural antioxidant extracted from Pedicularis striata Pall (Jueyehesen). After being treated with 20 mumol/l verbascoside, the growth curve and mitotic index of human gastric adenocarcinoma MGc80-3 cells decreased remarkably, cell doubling time was delayed, the cellular growth inhibitory rate amounted to 53.2%, cell surface charge assayed by cell electrophoresis obviously changed, the electrophoresis rate dropped from 3.51 microns/s/v/cm to 2.74, i.e., the percent of retardation reached 28.4%. There was a 75% decrease of the tumorigenicity for the treated cells compared with the untreated cells inoculated subcutaneously in BALB/C nude mice. Scanning electron microscopy revealed that the microvilli on the surface of treated cells had been reduced obviously. It confirmed that verbascoside, similar to DMSO, could reverse MGc80-3 cells' malignant phenotypic characteristics and induced redifferentiation of MGc80-3 cells.

In vitro effects of prostaglandin E2 or indomethacin on the proliferation of lymphokine-activated killer cells and their cytotoxicity against bladder tumor cells in patients with bladder cancer

PURPOSE

To investigate the combined effects of interleukin-2 (IL-2) with either prostaglandin E2 (PGE2) or indomethacin (IM) on the proliferation and cytolysis of bladder tumor cells by lymphokine-activated killer (LAK) cells in patients with bladder cancer.

METHODS

LAK cell proliferation was assayed in the presence of various concentrations of either PGE2 or IM by cell counting. Bladder cancer cell lines BIU-87, EJ and bladder tumor cells (BTC) from the patients were cultured as target cells, and the cytotoxicity of LAK cells was determined by 3-(4.5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In addition, PGE2 in samples of conditioned medium from bladder cancer cells or peripheral blood mononuclear cells (PBMC) as well as plasma from 21 patients with bladder cancer and 20 healthy donors were determined by radioimmunoassay (RIA).

RESULTS

The proliferation of LAK cells induced by IL-2 was inhibited by PGE2 (0.05 to 5 ng/mL) in concentration-dependent manner. The enhanced growth of LAK cells was observed at certain concentrations of IM (100-400 ng/mL) from 48 to 96 h. Pretreatment of LAK cells with IM (200 ng/mL) significantly enhanced cytotoxicity against BIU-87, EJ cells, or BTC. More PGE2 was present in conditioned medium from BIU-87 cells than in the conditioned medium from PBMC.

CONCLUSIONS

These studies indicate that LAK cell proliferation induced by IL-2 in patients with bladder cancer is inhibited by PGE2 produced by PBMC and bladder cancer cells. This inhibition can be overcome by IM, which may be of use in immunotherapy of bladder cancer.

Repair effect of phenylpropanoid glycosides on thymine radical anion induced by pulse radiolysis

Repair effects on thymine radical anion by six phenylpropanoid glycosides (PPGs), isolated from Pedicularis species, were studied using pulse radiolysis method. The thymine radical anion was produced by the reaction of hydrated electron with thymine. PPGs were added into the thymine solution saturated with N(2). Kinetic analysis showed that transient absorption spectrum of thymine radical anion formed at first, and then after several microseconds of pulse radiolysis changed to that of PPG radical anion. The evidence indicated that thymine radical anion was repaired through one-electron transfer between the radical anion and PPG. Electrophilic phenyl-substituted unsaturated carboxylic group containing in PPGs' structure was able to capture electron from thymine radical anion before it undergo reversible protonation. The reaction rate constants of electron transfer from thymine radical anion to PPGs were within 1.16-2.29 x 10(9) dm(3) mol(-1) s(-1).

The effects of CD3, CD4 and CD28 signaling on lymphocytes during human immunodeficiency virus-1 infection

We investigated the effects of early human immunodeficiency virus-1 infection (HIV-1) on CD4- and CD28-mediated co-signaling of the T cell receptor (TCR)/CD3 complex in peripheral blood lymphocytes (PBL). CD4 ligation either alone or in conjunction with TCR occupancy resulted in abrogated signaling shown by impaired co-association of the tyrosine kinase ZAP-70 with the CD3-zeta chains in virally infected PBL. In addition, down-regulation of CD4-associated TCR signaling resulted in diminished tyrosine phosphorylation of mitogen-activated protein kinase (MAPK), a serine threonine kinase which is critically involved in the regulation of transcription factors. Furthermore, these aberrant CD4-driven signals rendered HIV-1-infected PBL susceptible to activation-induced cell death. By contrast, cross-linking of the TCR/CD3 complex with the CD28 receptor improved tyrosine phosphorylation of MAPK and salvaged infected PBL from activation-induced cell death. Our data demonstrate the importance of appropriate CD3, CD4 and CD28 co-stimulatory function to prevent apoptosis. The CD4-mediated signaling defects of the TCR could contribute to the loss of immunocompetent cells during HIV-1 infection via activation-induced cell death, whereas stimulation through the CD28 pathway could reverse these detrimental effects.

Solution structure of the N-terminal zinc binding domain of HIV-1 integrase

The solution structure of the N-terminal zinc binding domain (residues 1-55; IN1-55) of HIV-1 integrase has been solved by NMR spectroscopy. IN1-55 is dimeric, and each monomer comprises four helices with the zinc tetrahedrally coordinated to His 12, His 16, Cys 40 and Cys 43. IN1-55 exists in two interconverting conformational states that differ with regard to the coordination of the two histidine side chains to zinc. The different histidine arrangements are associated with large conformational differences in the polypeptide backbone (residues 9-18) around the coordinating histidines. The dimer interface is predominantly hydrophobic and is formed by the packing of the N-terminal end of helix 1, and helices 3 and 4. The monomer fold is remarkably similar to that of a number of helical DNA binding proteins containing a helix-turn-helix (HTH) motif with helices 2 and 3 of IN1-55 corresponding to the HTH motif. In contrast to the DNA binding proteins where the second helix of the HTH motif is employed for DNA recognition, IN1-55 uses this helix for dimerization.

[The free radicals and nickel carcinogenesis]

The relationship between free radicals and the carcinogenesis of nickel and its compounds was summarized. Ni(II) could enhance the production of free radicals mainly in three pathways: Fenton reaction, enhancing lipid peroxidation and decreasing cellular antioxidantive defense system. Thus free radacals lead cell carcinogenesis. It suggested that the carcinogenesis of Ni(II) was mainly related to the effect of free radicals.

IFN-gamma production from human Th1 cells is controlled by Raf kinase

Raf kinase is an important intracellular mediator in T cell signalling and may be crucial for the proliferation of this inflammatory cell. In order to elucidate its effect on cytokine production by human T cells in response to T cell receptor activation, experiments were carried out on human T cell clones using antisense (AS) oligodeoxynucleotides (ODN) to inhibit the expression of Raf kinase. AS ODN to Raf were shown to have a significant effect on a human Th1-like T cell clone, inhibiting antiCD3-induced IFN-gamma secretion by 76%, whereas no inhibitory effect was observed on IL-5 or IL-4 production by a Th2-like clone. IL-2 secretion from both clones was also not affected by the Raf AS ODN. In all cases, a reduction in Raf kinase within the cell was demonstrated by Western blot. Our results clearly demonstrate the importance of Raf kinase in the production of IFN-gamma from Th1 cells, but also show the lack of effect of this intracellular mediator on cytokine (IL-5, IL-4) release from Th2 cells.