Activation of the ras-mitogen-activated protein kinase pathway and phosphorylation of ets-2 at position threonine 72 in human ovarian cancer cell lines

The activation status of the ras pathway was studied in eight ovarian tumor cell lines. Three biochemical parameters indicative of ras activation were tested: (a) the ratio of the ras-GTP:ras-GDP complex; (b) the activity of mitogen-activated protein kinases p42/p44; and (c) ets-2 phosphorylation at position threonine 72, a mitogen-activated protein kinase phosphorylation site in vivo. Four of the ovarian tumor cell lines had an activated ras pathway by these three parameters, whereas only one of these contained a mutated ras gene. In addition, ras/ets-2 responsive genes such as the urokinase plasminogen activator (uPA) were activated in these four cell lines. Transient transfection assays indicated that the compound ets-AP1 oncogene responsive enhancer present in the uPA gene was the target of ras signaling in ovarian tumor cells and that the combination of activated ras and ets-2 could superactivate the uPA enhancer element. Coexpression of the dominant-negative ras-Asn17 cDNA gene abrogated activity of this uPA element in ovarian tumor cells. These data indicate that ets-2 is a nuclear target of ras action in ovarian tumor cell lines and that ras signaling pathways may be activated in ovarian cancer by mechanisms independent of direct genetic damage to ras genes.

Probing the active site of cytochrome P450 2B1: metabolism of 7-alkoxycoumarins by the wild type and five site-directed mutants

A series of 7-alkoxycoumarins (chain length of 1-7 carbon atoms) was utilized as active site probes of purified Escherichia coli-expressed cytochrome P450 2B1 wild type and five site-directed mutants (I114V, F206L, V363A, V363L, and G478S). The production of 7-hydroxycoumarin, the O-dealkylation product, by the wild-type enzyme exhibited a rank order of C2 > C4 > C3 > C1 > C5 > C6 = C7. The pattern observed for the P450 I114V mutant was similar to that of the wild-type enzyme, whereas with F206L and G478S mutants, the rate of O-dealkylation was low with all the compounds. In contrast, with V363A, the highest rate of product formation was observed with 7-butoxycoumarin. The V363L mutant preferentially catalyzed the O-dealkylation of 7-methoxy- and 7-ethoxycoumarin, and a further increase in the length of the alkyl chain led to a marked decrease in product formation. The stoichiometry of 7-butoxycoumarin oxidation by V363L suggested that products other than 7-hydroxycoumarin were also formed. HPLC and GC-EIMS analyses revealed that P450 2B1 V363L produced 7-(3-hydroxybutoxy)coumarin and 7-(4-hydroxybutoxy)coumarin as major oxidation products, while the V363A mutant mainly catalyzed the O-dealkylation of 7-butoxycoumarin. Docking of alkoxycoumarins into the active site of a P450 2B1 homology model confirmed the importance of the studied residues in substrate dealkylation and explained the formation of novel 7-butoxycoumarin products by the V363L mutant.

Oxytocin: a paracrine hormone in the regulation of parturition?

The role of oxytocin in parturition is controversial. When considered as an endocrine hormone, the balance of evidence suggests that oxytocin has little involvement in the initiation of labour. However, recent research has demonstrated synthesis of mRNA encoding oxytocin within the pregnant human uterus. This article reviews the hypothesis that oxytocin is an important paracrine (or autocrine) hormone with respect to the control of myometrial contractility in late gestation. Experimental data are provided from humans when possible and from studies using the rat as an experimental model. The processing of oxytocin prohormones in uterine tissues is reviewed and the presence and possible role of carboxy-extended forms of oxytocin in late gestational tissues of rats are discussed. The regulation of oxytocin and its receptor, particularly by oestrogen and progesterone, is reviewed. The inter-relationship between oxytocin and prostaglandins is discussed. Finally, the metabolism of oxytocin within intrauterine tissues and the recent development of specific antagonistic analogues to oxytocin are considered. It is concluded that further clarification of this paracrine system within intrauterine tissues during late gestation could lead to more successful strategies for preventing or arresting preterm labour in women.

Oltipraz chemoprevention trial in Qidong, People's Republic of China: modulation of serum aflatoxin albumin adduct biomarkers

In 1995, 234 adults from Qidong, People's Republic of China, were enrolled and followed in a Phase IIa 4-methyl-5-(N-2-pyrazinyl)-1,2-dithiole-3-thione (oltipraz) chemoprevention trial. Residents of this area are at high risk for development of hepatocellular carcinoma, in part due to consumption of aflatoxin-contaminated foods. The intervention was a randomized, placebo-controlled, double-blind study. Elements of the study design and clinical outcomes have been recently published (Jacobson et al, Cancer Epidemiol. Biomark. Prev., 6: 257-265, 1997). The primary objective was to conduct a preliminary assessment of the ability of oltipraz to modulate levels of a validated biomarker of aflatoxin exposure and of the risk of hepatocellular carcinoma by determining levels of aflatoxin-albumin adducts in sera. Healthy eligible individuals were randomized into three arms to receive p.o. 125 mg of oltipraz daily, 500 mg of oltipraz weekly, or placebo for 8 weeks. There were no consistent changes in biomarker levels in the placebo arm over the 16-week observation period, nor was any apparent effect observed in the arm receiving 125 mg of oltipraz each day. However, individuals receiving 500 mg of oltipraz once a week for 8 weeks showed a triphasic response to oltipraz. No effect was observed during the 1st month of the intervention, whereas a significant (P = 0.001) diminution in adduct levels was observed during the 2nd month of active intervention and during the lst month of follow-up. A partial rebound in adduct levels toward baseline values was observed during the 2nd month postintervention. Linear regression models up to week 13 confirmed a significant (P = 0.008) weekly decline of biomarker levels in the group receiving 500 mg of oltipraz once a week. However, despite these effects relative to baseline values within the 500-mg weekly arm, there were no statistically significant differences in biomarker trajectories between treatment arms. The genotype for glutathione S-transferase M1, an oltipraz-inducible isoform involved in the detoxification of aflatoxin B1, did not appear to affect either baseline levels or rates of decline in the biomarker. A follow-up Phase IIb trial with a longer intervention period will be necessary to determine the full extent to which aflatoxin biomarker burden can be reduced and whether diminution of biomarkers can be sustained over the long term.

Expression of p16 induces transcriptional downregulation of the RB gene

The RB and p16(INK4A) tumor suppressor genes function in the same pathway of cell cycle control. Previous evidence indicates that the p16(INK4A) gene is transcriptionally repressed by the RB gene product, pRB. In this study using human ovarian cancer cell lines, we found that RB protein and mRNA were expressed at higher levels in cell lines lacking p16 than in those with normal p16. Since this suggests a potential role of p16 in regulating the cellular level of pRB, we studied the effect of wild-type p16(INK4A) on expression of the RB gene. Introduction of p16(INK4A), carried by an adenovirus vector, into p16-negative cell lines dramatically decreased expression of RB protein and mRNA. Nuclei run-off assays demonstrated that p16 expression induced transcriptional downregulation of the RB gene. These results indicate that expression of RB is inversely regulated by p16. The findings reveal a new dimension of pRB-p16 interaction and should have implications for p16(INK4A)-mediated gene therapy.

Cell-specific regulation of transcription of the malic enzyme gene: characterization of cis-acting elements that modulate nuclear T3 receptor activity

Stimulation of malic enzyme transcription by triiodothyronine (T3) is robust (> 60-fold) in chick embryo hepatocytes, weak (5-fold) in chick embryo fibroblasts that stably overexpress the nuclear T3 receptor-alpha, and still weaker (1-fold) in chick embryo fibroblasts which contain nuclear T3 receptor levels that are similar to those of chick embryo hepatocytes. Using DNase I hypersensitivity, functional transfection, and in vitro DNA-binding analyses, four cis-acting elements were identified in the malic enzyme 5'-flanking DNA that conferred differences in nuclear T3 receptor activity between chick embryo hepatocytes and chick embryo fibroblasts. These cell-specific regulatory elements are located at -3895/-3890, -3761/-3744, -3703/-3686, and -3474/-2715 bp and overlap with DNase I hypersensitive sites that are observed in chromatin of chick embryo hepatocytes. Each element enhances T3 responsiveness of the malic enzyme promoter in chick embryo hepatocytes but has no effect on T3 responsiveness in chick embryo fibroblasts. Three of the cell-specific regulatory elements flank a previously identified DNA fragment (-3889 to -3769 bp; Hodnett et al., Arch. Biochem. Biophys. 334, 309-324, 1996) that contains one major and four minor T3 response elements. The cell-specific regulatory element at -3703/-3686 bp binds to the liver-enriched factor, CCAAT/enhancer-binding protein-alpha, whereas cell-specific regulatory elements at -3895/-3890 and -3761/-3744 bp bind proteins of unknown identity. While the cell-specific regulatory element at -3761/-3744 bp contains sequences that resemble binding sites for CCAAT/enhancer-binding protein, activator protein-1, cyclic AMP response element binding protein, and NF-1, none of these proteins appear to bind to this DNA fragment. These data suggest that cell-specific differences in T3 responsiveness of the malic enzyme gene are mediated in large part by nonreceptor proteins that augment the transcriptional activity of the nuclear T3 receptor in hepatocytes.

Stoichiometry of 7-ethoxycoumarin metabolism by cytochrome P450 2B1 wild-type and five active-site mutants

Recombinant P450 2B1 wild-type and the active-site mutants I114V, F206L, V363A, V363L, and G478S were purified and studied. The efficiency of coupling of reducing equivalents to 7-hydroxycoumarin formation was decreased for all the mutants except I114V. Uncoupling to H2O was increased for F206L, V363A, and G478S, decreased for V363L, and unchanged for I114V. Uncoupling to H2O2 was increased for V363L and decreased for I114V, F206L, and V363A. The findings from this study provide firm biochemical evidence that residues 206, 363, and 478 comprise part of the substrate binding site of P450 2B1.

Metabolism of oxytocin in rat uterus and placenta in late gestation

Concentrations of oxytocin (OT) peptide increase in rat uterine tissues at the time of parturition. We have measured the rate of OT metabolism in these tissues in late gestation to determine whether a decrease in OT catabolism is responsible for the increase in OT concentrations. Uterine and placental tissues were obtained from groups of rats at Days 16, 19, 21, 21.5, 22, and after delivery of the first pup. Delivery usually occurs in the early afternoon of Day 22. Some animals were treated with the estrogen receptor blocker tamoxifen, which will delay parturition by approximately 24 h. Cytosolic and microsomal preparations obtained using ultracentrifugation were incubated with radiolabeled OT. Metabolites were separated using HPLC, and enzyme kinetic parameters were calculated. OT was actively metabolized in both uterine and placental tissues. Total oxytocinase activity was similar in the two tissues. In uterine tissues, activity was greater in the cytosolic fractions. In placenta, activity was evenly distributed between the cytosolic and microsomal fractions. The cytosolic fractions of each tissue contained predominantly post-proline endopeptidase activity, whereas the microsomes contained predominantly aminopeptidase activity. There was a slight trend to decreasing oxytocinase activity with advancing gestation in both subcellular fractions, but this was statistically significant only in the microsomal fraction. The maximal decline in activity was only 25-50%. Tamoxifen treatment had no effect on oxytocinase activity. We conclude that rat uterine and placental tissues contain post-proline endopeptidase and aminopeptidase activities that metabolize OT. It is doubtful that changes in these activities are major factors in regulating the increase in OT concentrations measured in rat intrauterine tissues at the time of parturition.

Cytochrome P450 metabolites of arachidonic acid: rapid incorporation and hydration of 14,15-epoxyeicosatrienoic acid in arterial smooth muscle cells

Arachidonic acid is converted to epoxyeicosatrienoic acids (EETs) by cytochrome P450 monooxygenases. EETs produce arterial vasodilatation, and recent evidence suggests that they are endothelium-derived hyperpolarizing factors. In porcine coronary arteries contracted with a thromboxane mimetic agent, we find that relaxation is rapidly initiated by exposure to 14,15-EET. The relaxation slowly increases in magnitude, resulting in a response which is sustained for more than 10 min. Cultured porcine aortic smooth muscle cells rapidly take up [3H]14,15-EET. After 3 min, radioactivity is present in neutral lipids, phosphatidylcholine, and phosphatidylinositol. The cells also convert 14,15-EET to 14,15-dihydroxyeicosatrienoic acid (14,15-DHET), and some DHET is detected in the medium after only 1 min of incubation. Like 14,15-EET, 14,15-DHET produces relaxation of the contracted coronary artery rings. These findings suggest that the incorporation into phospholipids and conversion to 14,15-DHET can occur at a rate that is fast enough to modulate the vasorelaxation produced by 14,15-EET.

Cloning and sequence analysis ofAlcaligenes faecalis nifHDK gene cluster

Total DNA ofAlcaligenes faeculis was probed with both the nifH and nifHD sequences fromK. pneumoniae.One positive band of about 4. 6 kb was discovered. This nifH homologous fragment was cloned into the vector pBluescript SK(+) to construct the recombinant plasmid pBZ1. The inserted fragment in pBZl was analyzed by physical mapping and was further subcloned for sequencing. It was found that thisA. faecalis nifHDK homology possessed a typical Sigma(54)-dependent promoter region with upstream activator sequence (UAS) and A-T rich region. The nifH and nifD ORFs were 888 and 1 476 bp long respectively. The GC contents of these two genes were about 61.6% and 60.0%. The intergenic regions of nifH-nifD and nifn-nifK were 101 and 105 bp respectively. There were separate SD sequences upstream of all the three genes. The deduced amino acid sequences of the nifH gene product (the Feprotein) and the nifD gene product (the Mo-Fe-protein) were also highly homologous to other nitrogen-fixing bacteria, especially in those conserved motif. TheA. faeculis sequence has the highest similarity to that ofA. uinelandii.

7-spirobenzocyclohexyl derivatives of naltrexone, oxymorphone, and hydromorphone as selective opioid receptor ligands

On the basis of previous structure-activity studies of the highly potent and selective delta-opioid receptor antagonist naltrindole (1) and the spiroindanyl analogues 2 and 3, we have synthesized epimeric pairs of spirobenzocyclohexyl derivatives of naltrexone, oxymorphone, and hydromorphone (4-9). Pharmacologic evaluation in smooth muscle assays has revealed that the oxymorphone derivatives (6, 7) are delta-selective agonists and possess receptor binding profiles that are consistent with their agonist activity. It is proposed that the spirobenzocyclohexyl group of 6 and 7 orients its benzene moiety orthogonally with respect to the C ring of the opiate in a manner similar to that of the spiroindanyl analogue 3. It is suggested that this orthogonal orientation serves as an "address" to facilitate activation of delta receptors. The finding that the hydromorphone analogues (8, 9) were full mu agonists and exhibited only partial delta agonist activity suggests that the 14-hydroxyl group also contributes to the delta agonist activity. The naltrexone derivatives (4, 5) were mu-selective antagonists and exhibited relatively weak delta antagonist activity. However, the binding data indicated a very high-affinity delta-selective binding profile that was not consistent with the pharmacology. This study illustrates the differential contributions of the delta "address" to agonist and antagonist activity and supports the idea of different recognition sites for interaction of agonist and antagonist ligands with delta-opioid receptors.

Bronchial tuberculosis. Cytologic diagnosis of fiberoptic bronchoscopic brushings

OBJECTIVE

To determine the cytomorphologic features of bronchial tuberculosis on fiberoptic bronchoscopic brushings and its diagnostic value.

STUDY DESIGN

Seven hundred forty-six bronchoscopic examinations were retrospectively studied. The patients' macroscopic findings made by fiberoptic bronchoscopic examination, as well as brush cytologic and biopsy findings, were reviewed.

RESULTS

Of 746 bronchoscopic brushing specimens, 23 were diagnosed as endobronchial tuberculosis by cytomorphology; that accounted for about 3.1% of cases. The same or a similar diagnosis was made for both specimen types in 16 of the specimen pairs. Acid-fast stain showed that only one brushing was positive (4.3%); all the biopsy specimens were negative. Epithelioid cell granulomas and/or caseous necrosis were found in 23 cases of brush smears, while tuberculous granulomas accounted for 16 bronchial biopsies. Seven were nonspecific chronic bronchitis or normal bronchial mucosa.

CONCLUSION

The cytomorphologic alterations of tuberculosis are suitable for diagnosing bronchial tuberculosis on fiberoptic bronchoscopic brushings. Its sensitivity for defining bronchial tuberculosis is not lower than that of bronchial histologic biopsies or bacteriologic examination.

Synthetic-peptide-based enzyme-linked immunosorbent assay for screening human serum or plasma for antibodies to human immunodeficiency virus type 1 and type 2

A synthetic-peptide-based enzyme-linked immunosorbent assay (EIA) capable of screening for antibodies to both human immunodeficiency virus type 1 (HIV-1) and HIV-2 has been developed for use in blood banks and diagnostic laboratories. Microtiter wells are coated with two synthetic peptides, one corresponding to the highly conserved envelope region of HIV-1 and another corresponding to the conserved envelope region of HIV-2. Overall, sensitivity was 100% in 303 individuals diagnosed with AIDS and 96 individuals diagnosed with AIDS-related complex, 14.8% in a study of 500 high-risk group members, 99.9% in 600 EIA repeatedly reactive (RR)-HIV-1 Western blot (WB)-positive repository specimens, and 100% for 222 geographically diverse HIV-1 specimens and 216 confirmed HIV-2-positive specimens evaluated. The specificity was determined to be 99.72% for a total of 13,004 serum and plasma samples from random volunteer donors evaluated across five blood banks. Forty donors who were found to be EIA RR-WB indeterminate but nonreactive on the United Biomedical, Inc., test (UBI HIV 1/2 EIA) were prospectively followed as an additional measure of specificity. None of the 40 low-risk cases evolved into a positive WB pattern at follow-up. The sensitivity and specificity of this new assay are comparable to those of other Food and Drug Administration-licensed HIV-1 and HIV-1-HIV-2 assays that are currently available in the United States. The UBI HIV 1/2 EIA affords laboratories another choice in the detection of antibodies for HIV-1 and HIV-2 with a test based on an alternative antigen format.

Potentiation of endothelium-dependent relaxation by epoxyeicosatrienoic acids

Epoxyeicosatrienoic acids (EETs) are potent endothelium-derived vasodilators formed from cytochrome P-450 metabolism of arachidonic acid. EETs and their diol products (DHETs) are also avidly taken up by endothelial cells and incorporated into phospholipids that participate in signal transduction. To investigate the possible functional significance of EET and DHET incorporation into cell lipids, we examined the capacity of EETs and DHETs to relax porcine coronary arterial rings and determined responses to bradykinin (which potently activates endothelial phospholipases) before and after incubating the rings with these eicosanoids. 14,15-EET and 11,12-EET (5 mumol/L) produced 75 +/- 9% and 52 +/- 4% relaxation, respectively, of U46619-contracted rings, whereas 8,9-EET and 5,6-EET did not produce significant relaxation. The corresponding DHET regioisomers produced comparable relaxation responses. Preincubation with 14,15-EET, 11,12-EET, 14,15-DHET, and 11,12-DHET augmented the magnitude and duration of bradykinin-induced relaxation, whereas endothelium-independent relaxations to aprikalim and sodium nitroprusside were not potentiated. Pretreatment with 2 mumol/L triacsin C (an inhibitor of acyl coenzyme A synthases) inhibited [3H]14,15-EET incorporation into endothelial phospholipids and blocked 11,12-EET- and 14,15-DHET-induced potentiation of relaxation to bradykinin. Exposure of [3H]14,15-EET-labeled endothelial cells to the Ca2+ ionophore A23187 (2 mumol/L) resulted in a 4-fold increased release of EET and DHET into the medium. We conclude that incorporation of EETs and DHETs into cell lipids results in potentiation of bradykinin-induced relaxation in porcine coronary arteries, providing the first evidence that incorporated EETs and DHETs are capable of modulating vascular function.

Effects of RU486 on estrogen, progesterone, oxytocin, and their receptors in the rat uterus during late gestation

Oxytocin (OT) and its receptor (OTR) are synthesized in the endometrium and myometrium of the pregnant rat during late gestation. Both are regulated by estrogen and progesterone (P4), and tissue concentrations of both increase markedly before parturition. The P4 antagonist RU486 will induce parturition in the rat. The purpose of the present studies was to investigate changes in OT and OTR messenger RNA (mRNA) and peptide synthesis within the pregnant rat uterus during RU486-induced parturition. Pregnant rats were given a single injection of RU486 (2.5 mg/rat in oil) on day 15 of pregnancy (normal delivery occurs on day 22). Control animals received injections of oil only. Groups of animals (n = 5 in each group) were euthanized at 0, 6, 12, 24, and 48 h after injection and during labor (immediately after delivery of the first pup). Maternal serum estradiol (E2), P4 and uterine OT, and PGE2 concentrations were measured by RIA. Prostaglandin F2alpha and estrogen receptor levels were measured by enzyme immunoassay (EIA). OTR and P4 receptor (PR) were measured using radioligand-binding assays. OT, OTR, and estrogen receptor mRNAs were measured with ribonuclease protection assays. The average time to delivery, after RU486 injection, was 27.0 +/- 1.2 h. Serum E2 and P4 levels were increased slightly, but significantly, at 24 h after RU486. In controls, OT mRNA increased significantly, and this increase was blocked in the RU486 treatment group. OTR mRNA levels increased within 6 h of RU486 and remained elevated until delivery. OTR peptide was increased by 12 h. PGE2 and PGF2alpha were increased 3-fold and 16-fold, respectively, but not until after the increase in OTR had occurred. We conclude that the mechanism of action of RU486 is to inhibit the P4 suppression of OTR synthesis, allowing increased expression of OTR, which may directly stimulate myometrial contractions or act indirectly through increased synthesis of PGs.

Lysophosphatidylcholine stimulates activator protein 1 and the c-Jun N-terminal kinase activity

Lysophosphatidylcholine (lyso-PC), a natural lipid generated through the action of phospholipase A2 on membrane phosphatidylcholine, has been implicated in atherogenesis and the inflammatory process. In vitro studies have established a role for lyso-PC in modulation of gene expression and other cellular responses including differentiation and proliferation. There is also evidence that lyso-PC may act as an intracellular second messenger transducing signals elicited from membrane-associated receptors. The mechanisms behind the diverse activities of lyso-PC are poorly understood. We report, in this study, that treatment of cultured cells with exogenous lyso-PC, at nontoxic concentrations, potently induced activator protein-1 (AP-1) DNA binding and transcriptional activity independent of well known AP-1 activators, protein kinase C or mitogen-activated protein kinases ERK1 and ERK2. Lyso-PC also activated the c-Jun N-terminal kinase (JNK/SAPK), a recently characterized member of the mitogen-activated protein kinase family, known to activate AP-1. The stimulated JNK and AP-1 activities probably mediate or contribute to some bioactive effects of lyso-PC.

Cross-cultural consensus in personality judgments

Building on recent research demonstrating consensus and accuracy in interpersonal perception based on minimal information, the present studies examined American and Chinese participants' within- and cross-cultural judgments. In Study 1, the authors used the zero-acquaintance paradigm in the People's Republic of China and found consensus on all personality dimensions. In Study 2, Chinese and American participants judged each other on the basis of photographs, and consensus was found among Americans' judgments of Chinese and Chinese participants' judgments of Americans. Further, by correlating target effects based on within-culture zero-acquaintance judgments and cross-cultural photographic judgments, the authors found agreement in the judgments of individuals by members of their own culture and the other culture for both Chinese and Americans.

Evolution of risk behaviors over 2 years among a cohort of urban African American adolescents

OBJECTIVE

To examine the evolution of risk behaviors over 2 years among a community-based cohort of low-income African American preadolescents and young adolescents enrolled in a randomized trial of an acquired immunodeficiency syndrome risk reduction intervention.

DESIGN

Longitudinal, community-based cohort.

SETTING

Nine recreation centers serving 3 public housing developments.

SUBJECTS

Three hundred eighty-three African American youths aged 9 through 15 years at baseline.

INTERVENTIONS

Frequency distributions, chi 2 analyses, and regression analyses regarding 10 risk behaviors were conducted. To assess whether a specific risk behavior or its protective (nonrisk) behavioral analogue, composing a risk-nonrisk behavioral complex (eg, was sexually active and was sexually abstinent or used drugs and refrained from drugs), was stable over time, kappa values were determined for the 10 risk-nonrisk behavioral complexes.

MAIN OUTCOME MEASURES

Instrument assessing risk/ behaviors administered at baseline and every 6 months aurally and visually via talking computer.

RESULTS

The prevalence of sexual intercourse, cigarette smoking, alcohol consumption, and drug use increased notably over time. Drug use increased from a 6-month cumulative prevalence of 7% at baseline to 27% at the 24-month follow-up (P < .001). Cumulatively over the 2-year study interval, 81% of youths had engaged in fighting, 58% had engaged in sexual intercourse, and from 33% to 40% had engaged in truancy, knife or bat carrying or both, alcohol consumption, drug use, and cigarette smoking. All of the risk-nonrisk behavioral complexes except weapon carrying were stable during the semiannual assessment intervals. Fighting (kappa = 0.22, P < .01), sexual intercourse (kappa = 0.33, P < .001), alcohol consumption (kappa = 0.21, P < .001), and unprotected sexual intercourse (kappa = 0.34, P < .05) were stable for 2 years. Six risk-nonrisk behavioral complexes were stable for the 2-year interval among youths aged 13 through 15 years at baseline, while only 2 risk-nonrisk behavioral complexes were stable among younger youths. The intervention seemed to affect the stability of 4 risk behaviors: truancy, drug use, unprotected sexual intercourse, and, possibly, fighting. For unprotected sexual intercourse, this intervention effect seemed to be due to stabilization of nonparticipation in risky behavior. Intervention youths were less likely to adopt a risk behavior (ie, engage in it for > or = 2 risk assessment periods) than control youths, but they were not less likely to experiment with a risk behavior.

CONCLUSIONS

There is evidence that although the prevalence of risk behaviors does change with age, most risk-nonrisk behavioral complexes seem to be relatively stable over time and stability may increase with time. Risk reduction interventions seem to decrease risk adoption, stabilize nonrisk behaviors, and possibly destabilize risk behavior.

Oltipraz chemoprevention trial in Qidong, People's Republic of China: study design and clinical outcomes

In 1995, 234 adults from Qidong, Jiangsu Province, People's Republic of China, where hepatocellular carcinoma is the leading cause of cancer deaths and exposure to dietary aflatoxins is widespread, were enrolled and followed in a Phase II chemoprevention trial. The goals of the study were to define a dose and schedule of oltipraz for reducing levels of validated aflatoxin biomarkers and to characterize dose-limiting toxicities. Healthy eligible individuals, including those infected with hepatitis B virus, were randomized to receive either 125 mg of oltipraz daily, 500 mg of oltipraz weekly, or placebo. Blood and urine specimens were collected to monitor toxicities and evaluate biomarkers over the 8-week intervention period and subsequent 8-week follow-up period. Unique trial aspects included a synchronous follow-up schedule, daily observed administration of all medications, timely international data transference, and use of biomarkers as outcomes. One hundred thirty-two participants took their medications without interruptions, approximately 77% contributed all nine urine samples, and 78% contributed all seven blood samples. Fifty-one participants (21.8%) reported clinical adverse events. An extremity syndrome, developing soon after the start of treatment, was the only event that occurred more frequently (P = 0.002) among the active groups (18.4 and 14.1% of the daily 125 and weekly 500 mg arms, respectively) compared with placebo (2.5%). The oltipraz arms did not differ in symptom type or severity, and there were no indications of exacerbated drug intolerance among the few participants infected with hepatitis B virus. The good compliance with an intense follow-up schedule shows that chemoprevention trials with biomarker end points may be conducted in such populations.

[Indirect UV detection of short chain carboxylic acids in oil field water by high performance capillary zone electrophoresis]

Short chain carboxylic acids are the major aqueous organic species in oil field water. It is considered that they play an important role in the geochemical evolution of second porosity in oil reservoir. In this paper, short chain carboxylic acid anions were analyzed by HP(3D)CE high performance capillary electrophoresis system (Hewlett-Packard, Germany) with a buffer system of dinitrobenzoic acid-hexadecyltrimethyl ammonium bromide (CTAB). The influence of buffer pH and the concentrations of electrolyte, surfactant and methanol on the seperation of short chain carboxylic acids have been studied. The results showed that the best separation of short chain carboxylic acids could be done with the buffer of 10mmol/L dinitrobenzoic acid, 0.5mmol/L CTAB and 5% methanol at pH=9. Separations were performed in a 50cm x 50microm i.d. fused silica capillary (effective length 48.5cm) at 25 degrees C. A negative potential of 30kV was used for each experiment. Sample was introduced into the capillary by pressure at 50kPa for 10s. Indirect UV detection was operated at 254nm and reference wavelength at 380nm for all experiments. Negative peak was changed into positive one by exchanging between detection wavelength and reference wavelength. Capillary was rinsed for 10min with 0.1mol/L sodium hydroxide and buffer solution before each run. Oil field water was injected directly after filtered through 0.45microm membrane. The result was satisfactory.

Cross-cultural consensus in personality judgments

Building on recent research demonstrating consensus and accuracy in interpersonal perception based on minimal information, the present studies examined American and Chinese participants' within- and cross-cultural judgments. In Study 1, the authors used the zero-acquaintance paradigm in the People's Republic of China and found consensus on all personality dimensions. In Study 2, Chinese and American participants judged each other on the basis of photographs, and consensus was found among Americans' judgments of Chinese and Chinese participants' judgments of Americans. Further, by correlating target effects based on within-culture zero-acquaintance judgments and cross-cultural photographic judgments, the authors found agreement in the judgments of individuals by members of their own culture and the other culture for both Chinese and Americans.

[Clinical significance of galactose oxidase-Schiff reaction in the detection of carcinoma and precancerous lesions of large intestine]

OBJECTIVE

To study the clinical value of galactose oxidase-Schiff (GO-S) reaction to test carcinoma and precancerous lesions of large intestine.

METHODS

127 patients who had symptoms and signs of digestive tract diseases and 10 normal controls were studied, with their samples of rectum mucus smears stained. The histological sections of 73 cases of carcinoma and precancerous lesions of large intestine were stained with GO-S reaction.

RESULTS

The positive rates of GO-S reaction in carcinoma and precancerous lesions of large intestine were over 80%. The specificity and sensitivity of GO-S reaction to detect carcinoma and precancerous lesions of large intestine were 98% and 86%, respectively. The positive predictive value was 90%.

CONCLUSION

GO-S reaction, being satisfactory and sensitive marker of carcinoma and precancerous lesions of large intestine, can be used for screening and general survey of these lesions.

Differential responses of Aplysia siphon motor neurons and interneurons to tail and mantle stimuli: implications for behavioral response specificity

1. Tail shock and mantle shock elicit different forms of siphon responses in Aplysia (flaring and backward bending vs. constriction and forward bending, respectively). Moreover, training with these two unconditioned stimuli (USs) in US-alone or classical conditioning paradigms differentially modifies the direction of the response to a siphon tap subsequently presented. As a first step toward addressing neural mechanisms underlying this response specificity, we systematically mapped the central siphon withdrawal circuit to determine which motor neurons and interneurons are differentially engaged by, and potentially modified by, tail and mantle USs. We utilized semi-intact preparations consisting of the intact mantle organs (including the gill and siphon), the tail, and the abdominal and circumesophageal ganglia. USs were delivered either cutaneously through silver wires implanted in the tail and mantle or via suction electrodes to the tail and branchial nerves. 2. We found that one class of central siphon motor neurons, the LFSB cells, was preferentially activated by tail USs, whereas other siphon motor neurons, the LBs cells and RDs cells, were preferentially activated by mantle USs. These motor neurons thus appear to be the final common path for the differential siphon movements to these USs. In addition, because activation of these cells can elicit neuromuscular facilitation and thereby enhance siphon movements, this differential activation may contribute to behavioral response specificity by imposing a specific response bias. 3. L29 interneurons, which both mediate and modulate the siphon withdrawal response, responded preferentially and exhibited synaptic facilitation selectively in response to tail shock USs. In contrast, L34 and the interneuron II network did not show differential activation. Facilitation at L29-LFSB connections following training with tail shock may contribute to tail-directed siphon responses to siphon tap and may thus be an additional mechanism contributing to behavioral response specificity. Possibly, facilitation at other L29 connections could also enhance its modulatory capabilities. 4. The generation of specific response topographies thus appears to involve the coordinate regulation of diverse neuronal elements and multiple mechanisms, which may contribute to different aspects of learning.

Dithionite-supported hydroxylation of palmitic acid by cytochrome P450BM-3

The ability of dithionite, an inexpensive reducing agent routinely used to produce the ferrous-carbonyl form of P450, to support P450BM-3-catalyzed hydroxylation of palmitate was studied. The hydroxylation products in the presence of dithionite were 15, 14, and 13-hydroxyhexadecanoate, with relative distributions similar to those observed with NADPH. The hydroxylation reaction was carried out in two separate steps, anaerobic reduction and subsequent oxidation of P450BM-3 by oxygen bubbling. The reduction step was much slower than the oxidation step, thus limiting the overall rate of hydroxylation. Upon addition of dithionite, the reductase domain of P450BM-3 seemed to be reduced before significant reduction of the heme domain occurred. The discovery of new reducing agents for P450-catalyzed reaction raises the possibility of replacing NADPH in specialty chemical hydroxylation catalyzed by P450s, especially catalytically self-sufficient P450s, such as P450BM-3 or recombinant fusion proteins of P450 covalently linked to a reductase.

Polarization-independent all-fiber isolator based on asymmetric fiber tapers

Nonreciprocal intensity transmission in optical fibers can be realized by use of an asymmetric fiber taper. A few-mode fiber taper-based nonreciprocal component is designed, and its nonreciprocal transmission characteristics are demonstrated. This structure can be employed to build polarization-independent all-fiber isolators or fiber-optic sensors.