Protective effects of Hibiscus tiliaceus L. methanolic extract to V79 cells against cytotoxicity and genotoxicity induced by hydrogen peroxide and tert-butyl-hydroperoxide

Plants of the genus Hibiscus thrives produce a diversity of molecules with bioactive properties. In a previous study of Hibiscus tiliaceus L. methanolic extract (HME) using bacteria and yeast, as test media, it has been shown that HME strongly inhibited the mutagenic action of H₂O₂ or tert-butyl-hydroperoxide (t-BHP). Here, our interest is to evaluate the genotoxicity and the antigenotoxic/antimutagenic properties of HME using oxidative challenge with H₂O₂ and t-BHP in V79 cells. We determined cytotoxicity using clonal survival assay; evaluated DNA damage using the comet assay and the micronucleus test in binucleated cells besides of the lipid peroxidation degree and the reduced glutathione content. We examined the ability of HME in quenching hydroxyl radical by means of a HPLC-based method utilizing the hypoxanthine/xanthine oxidase assay. At concentrations ranging from 0.001 to 0.1 mg/mL, HME was not cytotoxic, genotoxic or mutagenic. Treatment with non-cytotoxic concentrations of HME increased cell survival after H₂O₂ and t-BHP exposure and prevented DNA damage. The pre-treatment with HME also was able to decrease the mutagenic effect of these genotoxins, evaluated using the micronucleus test. HME prevented the increase in lipid peroxidation and decrease in GSH content in response to the oxidative challenge. Therefore, the ability in preventing against H₂O₂- and t-BHP-induced GSH depletion and lipid peroxidation was probably a major contribution to the cytoprotective effects. Moreover, HME acts as a hydroxyl radical scavenger. In summary, HME did not have a harmful or inhibitory effect on the growth of V79 cells and presented antioxidant activity, consequently, both antigenotoxic and antimutagenic effects against oxidative DNA damage.     

Maritime health: a case for preventing influenza on the high seas

For decades cruise ships have been recognized as foci for diarrheal illness. More recently influenza has been added to the list of diseases for which people on cruise ships are at risk. Influenza is a business risk involving cruise ship operating and litigation costs and travelers' loss in value. Immunizing the crews could be one way to prevent introduction and spread of influenza on cruise ships. A cost-effectiveness analysis for vaccination of crews on cruise ships was conducted showing that it is not only cost-effective but it is cost savings.     

BDNF regulates the expression of fragile X mental retardation protein mRNA in the hippocampus

Both fragile X mental retardation protein (FMRP) and brain-derived neurotrophic factor (BDNF) are implicated in the maturation of neurons and in the higher cognitive functions. We have investigated whether FMRP and BDNF are reciprocally regulated in neurons. Exposure of cultured hippocampal neurons to BDNF, but not to NT-3, reduced FMR1 mRNA levels to 84.8% of control at 4 h and the levels were back to baseline by 24 h or 4 days. Furthermore, expression of FMR1 mRNA was reduced (82.4% of control) in vivo in the hippocampus of transgenic mice overexpressing TrkB receptors, and a small but significant (5.1%) decrease was also detected in FMRP protein levels. In contrast, the expression patterns of BDNF and TrkB mRNAs were not altered in FMRP-deficient mice compared to wild-type mice. Our data provide evidence that BDNF via TrkB signaling decreases FMRP expression and suggest a role for FMRP in BDNF-induced synaptic plasticity.     

Crystal methamphetamine and ecstasy differ in relation to unsafe sex among young gay men

OBJECTIVE: Poly-substance use in gay social ('club') settings is common. Recent studies suggest a link between 'club' drug use and sexual risk behaviours. In this qualitative study, we compare and contrast two 'club' drugs: crystal methamphetamine and ecstasy (MDMA). METHODS: Life history interviews were conducted with 12 HIV seroconverters and 12 age-matched controls recruited from a prospective cohort study of young gay and bisexual men in Vancouver, British Columbia. Textual data concerning illicit substance use and unsafe sex were analyzed using NUDIST software. RESULTS: Most men related a substantial knowledge of and experience with crystal and ecstasy. Both drugs had attributes that enhanced gay socialization and were used in the same venues. Crystal was used to remain awake and increase energy. Ecstasy was used to induce euphoria and group connectedness. However, unlike ecstasy, crystal was associated with a distinct pattern of sexual arousal that frequently included unprotected (sometimes group) sex, was more likely to be used regularly by HIV-positive men, and was reportedly highly addictive and problematic. CONCLUSION: Crystal and ecstasy are used in the same social venues but differ markedly in relation to sexual risk behaviour.     

Relationship between steady-state and induced gamma activity to motion

When a moving stimulus is presented at a specific temporal frequency, both steady-state responses and induced gamma activity may be elicited in the electroencephalogram. The electroencephalogram was recorded when study participants viewed random dot kinematograms under three conditions: coherent motion, incoherent motion and stationary. Dot position was changed at a rate of 9.3 Hz in the coherent and incoherent conditions. Induced power at 40 Hz was increased during coherent motion compared with the other conditions. In contrast, the steady-state response at 9.3 Hz showed a trend for increased power during the incoherent condition. These results suggest that steady-state responses to moving stimuli reflect sensory activation, while the induced gamma activity indexes perceptual processes.     

Acculturation as a predictor of the onset of sexual intercourse among Hispanic and white teens

OBJECTIVE: To investigate ethnic differences in onset of sexual intercourse among Hispanic/Mexican American and white adolescents based on acculturation. DESIGN/METHODS: Preprogram survey data from 7270 Hispanic or white teens in 7th to 12th grade involved in the Arizona Abstinence-Only Education Program were used to predict the probability of onset of sexual intercourse based on age, sex, family structure, program location, religiosity, free school lunch, grades, rural residence, acculturation, and ethnicity. Specific attention was given to the influence of acculturation among Hispanic teens. The primary language spoken by the respondents (English, Spanish, or both) was used as a proxy measure for acculturation. RESULTS: Hispanic youth were at a greater risk for experiencing onset of intercourse than white youth, while controlling for all other predictors (odds ratio [OR], 1.40 [95% confidence interval (CI), 1.21-1.63]). This risk was amplified for highly acculturated Hispanic teens (OR, 1.69 [95% CI, 1.43-1.99]). However, less acculturated Hispanic youth were actually less likely to have experienced first intercourse than white youth (OR, 0.59 [95% CI, 0.42-0.82]), English-speaking Hispanic youth (OR, 0.35 [95% CI, 0.25-0.49]), or bilingual Hispanic youth (OR, 0.45 [95% CI, 0.31-0.64]). CONCLUSIONS: Low acculturation emerges as a significant protective factor while controlling for other social and cultural factors, in spite of the increased risk of initiating sexual intercourse for Hispanic teens overall. Hispanic Spanish speakers were least likely to have initiated intercourse, while Hispanic English speakers were the most likely.     

Central administration of transforming growth factor-alpha and neuregulin-1 suppress active behaviors and cause weight loss in hamsters

Transforming growth factor-alpha (TGF-alpha) is a candidate output signal of the hypothalamic circadian pacemaker. TGF-alpha is expressed in the suprachiasmatic nucleus (SCN) of rats, hamsters, and rhesus macaques [A. Kramer, F.C. Yang, P. Snodgrass, X. Li, T.E. Scammell, F.C. Davis and C.J. Weitz, Regulation of daily locomotor activity and sleep by hypothalamic EGF receptor signaling, Science, 294 (2001) 2511-5., X. Li, N. Sankrithi and F.C. Davis, Transforming growth factor-alpha is expressed in astrocytes of the suprachiasmatic nucleus in hamster: role of glial cells in circadian clocks, Neuroreport, 13 (2002) 2143-7., Y.J. Ma, M.E. Costa and S.R. Ojeda, Developmental expression of the genes encoding transforming growth factor alpha and its receptor in the hypothalamus of female rhesus macaques, Neuroendocrinology, 60 (1994) 346-59., Y.J. Ma, M.P. Junier, M.E. Costa and S.R. Ojeda, Transforming growth factor-alpha gene expression in the hypothalamus is developmentally regulated and linked to sexual maturation, Neuron, 9 (1992) 657-70.]. TGF-alpha reversibly inhibits wheel-running activity during long-term infusions into the third ventricle of hamsters (2 weeks, intracerebroventricular or ICV) [A. Kramer, F.C. Yang, P. Snodgrass, X. Li, T.E. Scammell, F.C. Davis and C.J. Weitz, Regulation of daily locomotor activity and sleep by hypothalamic EGF receptor signaling, Science, 294 (2001) 2511-5.], and this effect appears to be mediated by the epidermal growth factor receptor (EGFR or ErbB-1) [A. Kramer, F.C. Yang, P. Snodgrass, X. Li, T.E. Scammell, F.C. Davis and C.J. Weitz, Regulation of daily locomotor activity and sleep by hypothalamic EGF receptor signaling, Science, 294 (2001) 2511-5.]. Here, we demonstrate that this inhibitory effect is not restricted to wheel-running behavior or to mediation by the EGFR. Using direct observation, we found the effects of long-term TGF-alpha infusion (ICV, 12 microl/day, 3.3 microM) to be more general than previously reported. Other active behaviors such as grooming and feeding were reversibly inhibited and hamsters showed dramatic weight loss as a result of reduced feeding (34% of body weight over 19 days). TGF-alpha did not disrupt a non-behavioral rhythm, the rhythm in pineal melatonin. Wheel-running activity was also inhibited by another epidermal growth factor-like (EGF-like) peptide, neuregulin (NRG-1), that binds to different ErbB receptors. Like TGF-alpha, NRG-1 caused a significant weight loss. We also show that an acute injection of TGF-alpha inhibits activity (ICV, 5 microl, 3.3 microM over 2 min), with inhibition and recovery occurring over a few hours. Although the results are consistent with the proposed [A. Kramer, F.C. Yang, P. Snodgrass, X. Li, T.E. Scammell, F.C. Davis and C.J. Weitz, Regulation of daily locomotor activity and sleep by hypothalamic EGF receptor signaling, Science, 294 (2001) 2511-5.] role for EGF-like peptides in the daily regulation of activity, the actions of these peptides might also contribute to the behavioral etiology of diseases in which EGF-like peptides are expressed.     

The emergence of Lyme disease

Since its identification nearly 30 years ago, Lyme disease has continued to spread, and there have been increasing numbers of cases in the northeastern and north central US. The Lyme disease agent, Borrelia burgdorferi, causes infection by migration through tissues, adhesion to host cells, and evasion of immune clearance. Both innate and adaptive immune responses, especially macrophage- and antibody-mediated killing, are required for optimal control of the infection and spirochetal eradication. Ecological conditions favorable to the disease, and the challenge of prevention, predict that Lyme disease will be a continuing public health concern.