Evidence for a protein synthesis-dependent and -independent TNF alpha cytolytic mechanism

The analysis of the effect of the protein synthesis inhibitors emetine (EM) or actinomycin D (ACT-D) on the TNF alpha-mediated cytolysis of L929 target cells demonstrates a biphasic, concentration (10(-12)-10(-4) M)-dependent curve indicative of two cytolytic mechanisms operative in L929 cells. One TNF alpha cytolytic mechanism is dependent on protein synthesis in the target cells, while the other cytolytic mechanism is protein synthesis independent. Both TNF alpha cytolytic mechanisms cause apoptosis (fragmentation of DNA) as shown by the TNF alpha-mediated release of tritiated thymidine, Apoptag, and DAPI staining, in the presence or absence of EM or ACT-D. The two cytolytic mechanisms are also similar in their requirement for lipoxygenase enzymes as shown by the ability of nordihydroguaiaretic acid (10(-6)-10(-5) M) and ketoconazole (4 x 10(-6)-2 x 10(-5) M) to block TNF alpha-mediated lysis of the target cells. However, the two cytolytic mechanisms differ in their requirement for the production of oxygen free radicals. The oxygen free radical scavengers, dimethylsulphoxide (0.2-0.4 M) and glutathione (2 x 10(-6)-10(-5) M) block the TNF alpha-mediated cytolysis of target cells in the absence of protein synthesis inhibitors, but not in the presence of EM or ACT-D.

Trends in risk behaviors for HIV infection among U.S. high school students, 1989-1991

The objective of this study was to examine trends in rates of self-reported HIV-related instruction and behaviors among high school students in the United States. Self-administered questionnaires were completed by three independent, multistage national probability samples of public and private school students in grades 9 through 12 who were surveyed in the spring of 1989, 1990, and 1991, respectively. Controlling for demographic characteristics, we used logistic regression to test for trends from 1989 to 1991. From 1989 to 1991, the proportion of students who had received HIV instruction in school significantly increased from 53.7% in 1989 to 83.3% in 1991. At the same time, the proportion of students engaging in selected sexual behaviors generally decreased. We found significant declines in the proportion of students who had engaged in sexual intercourse (58.5% in 1989 to 54.1% in 1991), had two or more sex partners during their lifetime (40.1% in 1989 to 35.2% in 1991), and had four or more lifetime sex partners (23.6% in 1989 to 18.7% in 1991). School-based HIV instruction, which is reaching greater numbers of U.S. students, may be contributing to the decline in reported risk behavior. However, because the current level of HIV-related behavior is still too high, risk-reduction efforts for adolescents should be maintained and strengthened.

Youth risk behavior surveillance--United States, 1993

Priority health risk behaviors that contribute to the leading causes of mortality, morbidity, and social problems among youth and adults often are established during youth, extend into adulthood, and are interrelated. The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health risk behaviors among youth and youth adults: behaviors that contribute to unintentional and intentional injuries, tobacco use, alcohol and other drug use, sexual behaviors, dietary behaviors, and physical activity. The YRBSS includes a national, school-based survey conducted by CDC and state and local school-based surveys conducted by state and local education agencies. This report summarizes results from the national survey, 24 state surveys, and nine local surveys conducted among high school students during February through May 1993. In the United States, 72% of all deaths among school-age youth and young adults are from four causes: motor vehicle crashes, other intentional injuries, homicide, and suicide. Results from the 1993 YRBSS suggest many high school students practice behaviors that may increase their likelihood of death from these four causes: 19.1% rarely or never use a safety belt, 35.3% had ridden during the 30 days preceding the survey with a driver who had been drinking alcohol, 22.1% had carried a weapon during the 30 days preceding the survey, 80.9% ever drank alcohol, 32.8% ever used marijuana, and 8.6% had attempted suicide during the 12 months preceding the survey. Substantial morbidity and social problems among adolescents also result from unintended pregnancies and sexually transmitted diseases including HIV infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Receptor binding profile suggests multiple mechanisms of action are responsible for ibogaine's putative anti-addictive activity

The indole alkaloid ibogaine (NIH 10567, Endabuse) is currently being examined for its potential utility in the treatment of cocaine and opioid addiction. However, a clearly defined molecular mechanism of action for ibogaine's putative anti-addictive properties has not been delineated. Radioligand binding assays targeting over 50 distinct neurotransmitter receptors, ion channels, and select second messenger systems were employed to establish a broad in vitro pharmacological profile for ibogaine. These studies revealed that ibogaine interacted with a wide variety of receptors at concentrations of 1-100 microM. These included the mu, delta, kappa, opiate, 5HT2, 5HT3, and muscarinic1 and 2 receptors, and the dopamine, norepinephrine, and serotonin uptake sites. In addition, ibogaine interacted with N-methyl-D-aspartic acid (NMDA) associated ion and sodium ion channels as determined by the inhibition of [3H]MK-801 and [3H]bactrachotoxin A 20-alpha-benzoate binding (BTX-B), respectively. This broad spectrum of activity may in part be responsible for ibogaine's putative anti-addictive activity.

Youth risk behavior surveillance--United States, 1993

PROBLEM/CONDITION

Priority health risk behaviors that contribute to the leading causes of mortality, morbidity, and social problems among youth and adults often are established during youth, extend into adulthood, and are interrelated.

REPORTING PERIOD

February through May 1993.

DESCRIPTION OF SYSTEM

The Youth Risk Behavior Surveillance System (YRBSS) monitors six categories of priority health risk behaviors among youth and young adults: behaviors that contribute to unintentional and intentional injuries, tobacco use, alcohol and other drug use, sexual behaviors, dietary behaviors, and physical activity. The YRBSS includes a national, school-based survey conducted by CDC and state and local school-based surveys conducted by state and local education agencies. This report summarizes results from the national survey, 24 state surveys, and nine local surveys conducted among high school students during February through May 1993.

RESULTS AND INTERPRETATION

In the United States, 72% of all deaths among school-age youth and young adults are from four causes: motor vehicle crashes, other unintentional injuries, homicide, and suicide. Results from the 1993 YRBSS suggest that many high school students practice behaviors that may increase their likelihood of death from these four causes: 19.1% rarely or never used a safety belt, 35.3% had ridden with a driver who had been drinking alcohol during the 30 days preceding the survey, 22.1% had carried a weapon during the 30 days preceding the survey, 80.9% ever drank alcohol, 32.8% ever used marijuana, and 8.6% had attempted suicide during the 12 months preceding the survey. Substantial morbidity and social problems among adolescents also result from unintended pregnancies and sexually transmitted diseases, including human immunodeficiency virus (HIV) infection. YRBSS results indicate that in 1993, 53.0% of high school students had had sexual intercourse, 52.8% of sexually active students had used a condom during last sexual intercourse, and 1.4% ever injected an illegal drug. Among adults, 67% of all deaths are from three causes: heart disease, cancer, and stroke. In 1993, many high school students practiced behaviors that may increase the risk for these health problems: 30.5% of high school students had smoked cigarettes during the 30 days preceding the survey, only 15.4% had eaten five or more servings of fruits and vegetables during the day preceding the survey, and only 34.3% had attended physical education class daily.

ACTIONS TAKEN

YRBSS data are being used nationwide by health and education officials to improve school health policies and programs designed to reduce risks associated with the leading causes of mortality and morbidity. At the national level, YRBSS data are being used to measure progress toward achieving 26 national health objectives and one of eight National Education Goals.

Reliability of the Youth Risk Behavior Survey Questionnaire

The Centers for Disease Control and Prevention's Youth Risk Behavior Survey (YRBS) has been used on a biennial basis since 1990 to measure health risk behaviors of high school students nationwide. The YRBS measures behaviors related to intentional and unintentional injury, tobacco use, alcohol and other drug use, sexual activity, diet, and physical activity. The authors present the results from a test-retest reliability study of the YRBS, conducted by administering the YRBS questionnaire to 1,679 students in grades 7 through 12 on two occasions 14 days apart. The authors computed a kappa statistic for each of 53 self-report items and compared group prevalence estimates across the two testing occasions. Kappas ranged from 14.5% to 91.1%; 71.7% of the items were rated as having "substantial" or higher reliability (kappa = 61-100%). No significant differences were found between the prevalence estimates at time 1 and time 2. Responses of seventh grade students were less consistent than those of students in higher grades, indicating that the YRBS is best suited for students in grade 8 and above. Except for a few suspect items, students appeared to report personal health risk behaviors reliably over time. Reliability and validity issues in health behavior assessment also are discussed.

Substance use and HIV-related sexual behaviors among US high school students: are they related?

OBJECTIVES

This study was undertaken to examine whether use of alcohol, cigarettes, marijuana, cocaine, and other illicit drugs is related to the likelihood of sexual behaviors that increase risk for human immunodeficiency virus (HIV) infection among youth.

METHODS

The 1990 national Youth Risk Behavior Survey was used to collect self-reported information about a broad range of health risk behaviors from a representative sample of 11,631 high school students in the United States.

RESULTS

Students who reported no substance use were least likely to report having had sexual intercourse, having had four or more sex partners, and not having used a condom at last sexual intercourse. Adjusted for age, sex, and race/ethnicity, odds ratios for each of these sexual risk behaviors were greatest among students who had used marijuana, cocaine, or other illicit drugs. Students who had used only alcohol or cigarettes had smaller but still significant increases in the likelihood of having had sexual intercourse and of having had four or more sex partners.

CONCLUSIONS

HIV prevention programs for youth should recognize that substance use may be an important indicator of risk for HIV infection and acquired immunodeficiency syndrome through its association with unsafe sexual behaviors.

Preventing HIV infection among adolescents: evaluation of a school-based education program

BACKGROUND

This article reports the results of the impact of a school-based HIV prevention intervention on students' knowledge, attitudes, and behavior related to HIV infection.

METHODS

Seventeen schools within six Colorado school districts were assigned to either intervention or comparison conditions. Students in 10 schools received a 15-session, skills-based HIV prevention curriculum implemented by trained teachers. A total of 2,844 students completed at least one survey during the study period; surveys were matched using demographic questions, yielding a cohort of 979 students who had baseline and 6-month follow-up data.

RESULTS

Intervention students exhibited greater knowledge about HIV and greater intent to engage in safer sexual practices than the comparison students. Among sexually active students at the 6-month follow-up, intervention students reported fewer sexual partners within the past 2 months, greater frequency of using condoms, and greater intentions to engage in sex less frequently and to use a condom when having sex. Intervention students were also more likely to believe that teens their age who engage in HIV risk behaviors are vulnerable to infection. The intervention neither delayed the onset nor decreased the frequency of sexual intercourse and the frequency of alcohol and other drug use before sex by the 6-month follow-up assessment.

CONCLUSIONS

The results suggest that skills-based risk reduction programs can have an effect on student behavior. Among sexually active students, evidence suggests that school-based interventions can reduce behavior associated with risk of HIV infection.

GTP-dependent binding of the antiproliferative agent didemnin to elongation factor 1 alpha

The marine natural product, didemnin B, is a 7-amino acid, cyclic depsipeptide that inhibits G1 cell cycle progression at nanomolar concentrations by undefined mechanisms. It has been reported to exhibit immunosuppressive activities in animals and is undergoing clinical trials as a potential antineoplastic drug. In addition, at higher concentrations, didemnin B has been shown to inhibit in vivo and in vitro protein synthesis. However, the mechanisms by which inhibition is achieved are unknown. To investigate didemnin's various modes of action, an affinity column was synthesized and used to purify didemnin-binding proteins. The major retained protein was the 49-kDa guanine nucleotide-binding elongation factor, EF-1 alpha, which was identified by peptide sequence analysis. Moreover, didemnin binds EF-1 alpha only in the presence of GTP but does not inhibit the GTPase activity of EF-1 alpha. Therefore, EF-1 alpha is likely to be the intracellular target responsible for didemnin B's ability to inhibit protein synthesis. Furthermore, this specificity of didemnin affinity for the GTP-bound conformation of a guanine nucleotide-binding protein with homology to the Ras superfamily suggests a possible mode of action for didemnin's antiproliferative activity.

Changes in HIV-related information sources, instruction, knowledge, and behaviors among US high school students, 1989 and 1990

OBJECTIVES

Few data have been available among adolescents to determine behavioral changes that may prevent human immunodeficiency virus (HIV) infection. This analysis examines changes in the prevalence of self-reported HIV-related information sources, instruction, knowledge, and behaviors among high school students in the United States.

METHODS

Two independent, multistage national probability samples of students in grades 9 through 12 were surveyed in 1989 (n = 8098) and 1990 (n = 11,631) with self-administered, anonymous questionnaires that included similar items.

RESULTS

Compared with students surveyed in 1989, a significantly greater proportion of students surveyed in 1990 had received HIV instruction in school. Significant decreases were found in the proportion of White and female students who reported having had sexual intercourse, in the proportion of White students reporting two or more lifetime sex partners, and in the proportion of 15- and 16-year-olds, White students, and female students who reported having had four or more lifetime sex partners. For both years, students who had a greater level of HIV knowledge were less likely to have had multiple lifetime sex partners or to have injected illicit drugs.

CONCLUSIONS

The findings suggest that school-based HIV education and knowledge may be contributing factors in reducing certain risk behaviors that can lead to HIV transmission among secondary school youth.

Dietary tannins from cowpeas and tea transiently alter apparent calcium absorption but not absorption and utilization of protein in rats

Tannins reportedly alter absorption and utilization of protein and minerals. The present study investigated the effect of tannins extracted from 'Mississippi Silver' cowpeas and black tea when incorporated into nutritionally balanced diets. Condensed tannins were incorporated into the diet of weanling male Sprague-Dawley rats at 0.0, 0.0057, 0.0171 and 0.057 g/100 g diet for 28 d. Ingestion of tannin from cowpeas or tea did not change significantly growth rate, protein efficiency ratio, apparent protein digestibility, nitrogen excretion, relative liver weight, or nitrogen concentration of liver. During d 11-18, apparent calcium absorption was lower in rats fed the medium and high levels of cowpea tannin and in those fed all levels of tea tannin compared with the control group. By wk 4, no differences were observed in apparent calcium absorption among treatment groups. Apparent magnesium absorption was not affected by dietary treatment, nor was femur content of calcium or magnesium. We conclude that at the levels of condensed tannins fed, a short-term reduction of apparent calcium absorption occurred; however, by wk 4 calcium absorption was comparable to that of the control group. The acute change that occurred in apparent calcium absorption did not influence bone calcium content.

Shared T cell-defined antigens on independently derived tumors

We report that a subset of tumors independently derived from a cloned line of contact-inhibited, non-tumorigenic murine fetal fibroblasts confer cross-protective immunity against each other in vivo. Concordant with the in vivo cross-protection, cytolytic T cell clones from mice immunized with one of these tumor lines specifically lyse the three other lines in the same set but do not cross-react with either the nontumorigenic parental line or another similarly derived tumor line representing a different antigenic profile. This and other recent evidence for shared expression of tumor rejection Ag contrasts with the antigenic diversity previously described for chemical- and radiation-induced tumors. In the interpretation of such data it is essential to distinguish between Ag expressed in association with the transformation process and Ag induced by random mutation of already transformed cells.

Shared T cell-defined antigens on independently derived tumors

We report that a subset of tumors independently derived from a cloned line of contact-inhibited, non-tumorigenic murine fetal fibroblasts confer cross-protective immunity against each other in vivo. Concordant with the in vivo cross-protection, cytolytic T cell clones from mice immunized with one of these tumor lines specifically lyse the three other lines in the same set but do not cross-react with either the nontumorigenic parental line or another similarly derived tumor line representing a different antigenic profile. This and other recent evidence for shared expression of tumor rejection Ag contrasts with the antigenic diversity previously described for chemical- and radiation-induced tumors. In the interpretation of such data it is essential to distinguish between Ag expressed in association with the transformation process and Ag induced by random mutation of already transformed cells.

Interferon alfa activates a lytic mechanism in ovarian and cervical carcinoma cells

OBJECTIVE

Our purpose was to examine the in vitro cytolytic potential of interferon alfa for human cervical and ovarian carcinoma cell lines.

STUDY DESIGN

The lytic potential of interferon alfa alone and in the presence the protein synthesis inhibitors actinomycin D and emetine was determined in the human cervical carcinoma cell lines ME-180, MS751, SiHa, HT-3, and C-33A and the ovarian carcinoma cell lines Caov-3, NIH:OVCAR-3, SK-OV-3 carcinoma cell lines by means of an 18-hour chromium 51 release assay.

RESULTS

Exposure of these cell lines to interferon alfa alone did not result in lysis. Similarly, when cells were simultaneously exposed to interferon alfa and either actinomycin D or emetine there was no additional increase in lysis above that seen with actinomycin D or emetine alone. Pretreatment of cells with interferon alfa (10(3), 10(4), or 10(5) U/ml) followed by protein synthesis inhibition by actinomycin D or emetine resulted in a synergistic increase in lysis.

CONCLUSION

The ability to reveal the lytic potential of interferon alfa when protein synthesis is subsequently inhibited could have practical applications for the treatment of gynecologic malignancies.

Interferon-alpha (IFN alpha) induces a cytolytic mechanism in ovarian carcinoma cells through a protein kinase C-dependent pathway

We have recently shown that IFN alpha induces a cytolytic mechanism in human ovarian carcinoma cell lines which is revealed when protein synthesis is subsequently inhibited. In order to determine whether the cytolytic activity induced by IFN alpha was activated through a pathway involving the activation of PKC, the human ovarian carcinoma cell line Caov-3 was exposed to phorbol 12-myristate 13-acetate (PMA). Under conditions where PMA activates PKC, PMA mimicked IFN alpha in its ability to induce a cytolytic mechanism. In contrast, under conditions where PMA depletes PKC, PMA not only did not induce cytolytic activity, but it prevented IFN alpha from inducing cytolytic activity. To further investigate the involvement of PKC in the signaling of cytolytic activity by IFN alpha, the ability of the protein kinase inhibitors, staurosporine, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine dihydrochloride (H7), N-[2-(methylamino) ethyl]-5-isoquinolinesulfonamide dihydrochloride (H8), and N-(2-guanidinoethyl)-5-isoquinolinesulfonamide dihydrochloride (HA1004) to block the induction of cytolytic activity by IFN alpha was determined. The fact that H7, H8, and staurosporine, but not HA1004, blocked the induction of cytolytic activity by IFN alpha provides additional evidence of the involvement of PKC in this activity. Taken together these results indicate that the cytolytic activity induced by IFN alpha is induced through apathway that involves the activation of PKC.

Attenuation of AMPA-induced neurotoxicity by a calpain inhibitor

The effects of a membrane-permeable inhibitor of calpain, Cbz-Val-Phe-H, were examined in an in vitro model of neurotoxicity. Cerebellar slices from young rats were treated with the glutamate receptor agonist, amino-3-hydroxy-5-methyl-4-isoazole propionic acid (AMPA), and cytotoxicity was quantified using conventional histological techniques. Slices treated with AMPA exhibited damage to 83.0% of cerebellar Purkinje cells. In contrast, only 23.6% of Purkinje cells were damaged in slices treated with Cbz-Val-Phe-H and AMPA. These findings indicate that calcium-activated proteolysis is a critical event in AMPA-induced toxicity, and provide evidence that calpain inhibitors are capable of attenuating this form of excitotoxic damage in the central nervous system.

Divergent effects of taxol on tumor necrosis factor-α-mediated cytolysis of ovarian carcinoma cells

OBJECTIVE

Our objective was to study the combined effect of taxol and tumor necrosis factor-alpha on the cytolysis of human ovarian carcinoma cell lines, because taxol has been shown to be active against ovarian carcinoma and has also been shown to increase tumor necrosis factor-alpha release from macrophages.

STUDY DESIGN

The combined effect of taxol and tumor necrosis factor-alpha on the cell lines Caov-3, SK-OV-3, NIH:OVCAR-3, and A2780, which are sensitive to the cytolytic effect of tumor necrosis factor-alpha in the presence of inhibitors of protein synthesis, was investigated with a 24-hour chromium 51 release assay.

RESULTS

At therapeutic concentrations taxol caused a significant increase in tumor necrosis factor-alpha-mediated cytolysis of Caov-3 and A2780 (p < or = 0.05). By contrast, taxol caused a decrease in the tumor necrosis factor-alpha-mediated cytolysis of SK-OV-3 and NIH:OVCAR-3 (p < or = 0.01).

CONCLUSION

These results suggest that ovarian carcinomas have a heterogeneous response to the chemotherapeutic effect of taxol.

Effects of radiation on TNF alpha-mediated cytolysis of cell lines derived from cervical carcinomas

The effect of radiation, a primary mode of treatment for cervical malignancies, on the tumor necrosis alpha (TNF alpha)-mediated cytolysis of five cell lines derived from human cervical carcinoma cell lines (C-33 A, ME-180, HT-3, MS751, and SiHa) was analyzed. Results of this analysis showed that all of the cell lines were resistant to the cytolytic effects of TNF alpha. Although resistant when protein synthesis proceeds normally, ME-180, HT-3, MS751, and SiHa cells were sensitive to TNF alpha-mediated cytolysis in the presence of protein synthesis inhibitors. The cytolytic response of these cells to radiation was heterogeneous, with C-33 A cells being the most radiosensitive and SiHa cells being the least radiosensitive. The cell lines ME-180, MS751, and HT-3 were intermediate in their sensitivities to radiation. Because radiation is known to inhibit protein synthesis, the ability of radiation to enhance TNF alpha cytolytic activity was examined. The cell lines with intermediate sensitivities to radiation (ME-180, HT-3, and MS751) demonstrated statistically significant synergistic increases in cytolysis when exposed to TNF alpha in combination with radiation. Neither the radioresistant SiHa cell line nor the radiosensitive C-33 A cell line displayed increased cytolysis with increasing concentrations of TNF alpha at any dose of radiation. Possible mechanisms which may explain the synergy in ME-180, HT-3, and MS751 cells and lack of synergy in C-33 A and SiHa cells by TNF alpha and radiation are discussed.

The effects of cyclosporin A on the lysis of ovarian cancer cells by cisplatin or adriamycin

The major limitation to curative therapy for ovarian cancer is the development of drug resistance. Cyclosporin A (CsA), an immunosuppressive agent that has been used extensively in organ transplantation, also has been shown to decrease the resistance of cancer cells to some chemotherapeutic agents. Since cisplatin (CDDP) is the most common drug used for the treatment of ovarian cancer, we evaluated the potential of CsA to decrease resistance to CDDP in ovarian cancer cells selected for resistance to CDDP (A2780-CDDP). Although CsA significantly increased the sensitivity of A2780-CDDP cells to cytolysis by CDDP it did not increase CDDP sensitivity in the CDDP-sensitive parent cells (A2780), that is, CsA did not decrease basal resistance to CDDP. Both A2780-CDDP and A2780 are sensitive to cytolysis by Adriamycin (ADR). CsA significantly decreased the basal resistance of both cell lines to ADR. Interestingly, the effect of the protein synthesis inhibitors, emetine and cycloheximide, was similar to that of CsA, suggesting that CsA decreased selected resistance to CDDP and decreased basal resistance to ADR by affecting a protein synthesis-dependent resistance mechanism(s). In contrast to CsA and protein synthesis inhibitors, buthionine sulfoximine, an inhibitor of glutathione synthesis, decreased basal resistance of both cell lines to cytolysis by CDDP but not ADR, while verapamil, an inhibitor of P-glycoprotein, had no effect on cytolysis in either cell line. These results suggest that CsA may not decrease resistance to CDDP or ADR-mediated cytolysis by reducing glutathione or by inhibiting P-glycoprotein.