The hypothalamic-pituitary-testicular axis and the testicular function are modulated after silver nanoparticle exposure.

Silver nanoparticles (AgNPs) are widely used in industrial and medical applications and humans may be exposed through different routes, increasing the risk of toxicity. We investigated the transcript expression of genes involved in the regulation of the hypothalamic-pituitary-testicular (HPT) axis and the parameters associated with sperm functionality after prepubertal exposure. AgNPs modulated the transcript expression of genes involved in the control of the HPT axis and spermatogenesis in the groups treated with lower doses, while the functional parameters related to sperm and puberty were affected in the groups administered higher doses. These results suggest that the HPT axis is disrupted by AgNPs during the prepubertal and pubertal periods, which are highly susceptible windows for the endocrine-disrupting chemical activity.

Prepubertal exposure to commercial formulation of the herbicide glyphosate alters testosterone levels and testicular morphology.

Glyphosate is a herbicide widely used to kill weeds both in agricultural and non-agricultural landscapes. Its reproductive toxicity is related to the inhibition of a StAR protein and an aromatase enzyme, which causes an in vitro reduction in testosterone and estradiol synthesis. Studies in vivo about this herbicide effects in prepubertal Wistar rats reproductive development were not performed at this moment. Evaluations included the progression of puberty, body development, the hormonal production of testosterone, estradiol and corticosterone, and the morphology of the testis. Results showed that the herbicide (1) significantly changed the progression of puberty in a dose-dependent manner; (2) reduced the testosterone production, in semineferous tubules' morphology, decreased significantly the epithelium height (P < 0.001; control = 85.8 +/- 2.8 microm; 5 mg/kg = 71.9 +/- 5.3 microm; 50 mg/kg = 69.1 +/- 1.7 microm; 250 mg/kg = 65.2 +/- 1.3 microm) and increased the luminal diameter (P < 0.01; control = 94.0 +/- 5.7 microm; 5 mg/kg = 116.6 +/- 6.6 microm; 50 mg/kg = 114.3 +/- 3.1 microm; 250 mg/kg = 130.3 +/- 4.8 microm); (4) no difference in tubular diameter was observed; and (5) relative to the controls, no differences in serum corticosterone or estradiol levels were detected, but the concentrations of testosterone serum were lower in all treated groups (P < 0.001; control = 154.5 +/- 12.9 ng/dL; 5 mg/kg = 108.6 +/- 19.6 ng/dL; 50 mg/dL = 84.5 +/- 12.2 ng/dL; 250 mg/kg = 76.9 +/- 14.2 ng/dL). These results suggest that commercial formulation of glyphosate is a potent endocrine disruptor in vivo, causing disturbances in the reproductive development of rats when the exposure was performed during the puberty period.

Follicular dynamics in heifers during pre-pubertal and pubertal period kept under two levels of dietary energy intake.

The objective of this study was to characterize follicular dynamics in pre-pubertal, pubertal and post-pubertal periods, as well as the effect of high-energy intake on follicular development and age at puberty in heifers. Thirty-one Nelore (Bos indicus) heifers, 6 months old, were randomly assigned to receive two different diets: one of low (GI) and other of high dietary energy intake (GII). Animals were evaluated in relation to body weight gain by being weighed every 21 days. Heifers were evaluated every other day by real-time linear ultrasonography to characterize ovarian structures development from weaning to post-pubertal period. Blood samples were collected to determine plasmatic concentrations of progesterone by RIA method. The ovulation was determined when progesterone concentrations were >1 ng/mL in three consecutive samples, and by ultrasound images of corpus luteum; and oestrous behaviour in some animals. Age at puberty differed among heifers of GII (17.00 +/- 0.46 months) compared with heifers of GI (19.87 +/- 0.47 months; p < or = 0.05). Maximum size of the dominant follicles at pre-pubertal period was greater in GII heifers than in GI (10.52 +/- 0.33 and 9.76 +/- 0.15 mm, respectively; p < or = 0.05). As heifers approached first ovulation time, size of dominant follicle increased (11.75 +/- 0.37 mm for GI and 12.52 +/- 0.91 mm for GII; p < or = 0.05). Body weight at puberty was not different in both groups (302.33 +/- 27.31 kg for GI and 326.19 +/- 27.78 kg for GII heifers; p > 0.05). We conclude that animals receiving high dietary energy intake attained the puberty earlier and the development of follicles were different than in low dietary energy intake.

Structure and conformational properties of diacetyl sulfide in the gaseous and condensed phases explored by gas electron diffraction, single-crystal X-ray diffraction, vibrational spectroscopy, and quantum chemical calculations.

On the evidence of the electron diffraction pattern of the vapor, of the IR spectrum of the matrix-isolated molecule, and of quantum chemical calculations, the diacetyl sulfide molecule, CH3C(O)SC(O)CH3, adopts a planar heavy-atom skeleton with the [sp,ap] conformation. Other conformations contribute little (<1%) to the population of the gaseous molecules at normal temperatures. Salient structural parameters (r(a) structure, distances (in A), angles (in deg), and 3sigma uncertainties in parentheses) were as follows: r(C=O) 1.198(2)/1.196(2), r(C-S) 1.787(3)/1.808(3), r(C-C) 1.483(4)/1.472(4), angleC-S-C 108.8(9), angleS-C=O 125.7(6)/115.1(6), and angleS-C-C 121.1(7)/111.2(7). The structure of a single crystal at 150 K [monoclinic, P2(1)/n, a = 4.2230(7) A, b = 11.2105(17) A, c = 12.332(2) A, beta = 94.544(16) degrees] also reveals planar molecules with the same conformation and dimensions close to those of the gaseous molecule. Changes in the vibrational spectra of the compound accompanying the transition from the vapor to the condensed phases are attributed not to the presence of more than one conformer but to differences in the local environment of the two carbonyl groups. The properties deduced are compared with those of other compounds of the type CH3C(O)XC(O)CH3 (X = CH2, NH, or O).

Preparation and conformational properties of the perfluoro diether CF(3)OCF(2)OCF(2)C(O)F, a model molecule to study properties of perfluoro polyethers.

The compound CF(3)OCF(2)OCF(2)C(O)F was prepared by oxidation of hexafluoropropene with molecular oxygen in the gas-phase using CF(3)OF as initiator. (13)C NMR, FTIR, Raman, UV-vis, and mass spectra were obtained and interpreted. The theoretical structure studies were performed by the calculation of the potential energy surfaces, using the results obtained for a smaller related molecule, CF(3)OCF(2)C(O)F, as a starting point. A high degree of conformational flexibility of this compound is evidenced by the values of several conformations, varying within the range of 1 kcal/mol. Theoretical calculations predict chain conformations as the most stable molecular forms, as expected from the presence of the anomeric effect. The experimental fundamental vibrational modes are compared with those obtained theoretically, using ab initio and density functional theory methods, HF/6-31+G and B3LYP/6-31+G, respectively. The density of the compound at ambient temperature (delta = 1.7(1) g/mL), its melting point (mp = -140(5) degrees C), its boiling point (bp = 14.5 (1) degrees C), and the relation between its vapor pressure and the absolute temperature (ln P = 13.699 - 2023.4/T) were also determined.

Matrix photochemistry of syn-(chlorocarbonyl)sulfenyl bromide, syn-ClC(O)SBr: precursor to the novel species anti-ClC(O)SBr, syn-BrC(O)SCl, and BrSCl.

The vapor of (chlorocarbonyl)sulfenyl bromide, ClC(O)SBr, was isolated in solid Ar, Kr, N(2), and Ar doped with 5% CO at 15 K, and the matrix was subsequently irradiated with broad-band UV--visible light (200 < or = lambda < or = 800 nm), the changes being followed by reference to the IR spectrum of the matrix. The initial spectrum showed the vapor of ClC(O)SBr to consist of more than 99% of the syn form (with the C==O bond syn with respect to the S--Br bond) in equilibrium with less than 1% of the anti conformer. Irradiation caused various changes to occur. First, conformational randomization took place, leading to a roughly equimolar mixture of the two rotamers, and so affording the first spectroscopic characterization of an anti-ClC(O)S-containing compound. Simultaneously, the novel constitutional isomer syn-BrC(O)SCl was also formed. Continued photolysis resulted in the decay of all these species while revealing a third reaction channel, leading to the elimination of CO and the formation of the new triatomic sulfur halide BrSCl. The assignment of the IR bands to the different products was made on the basis of the usual criteria, taking account (i) of the effects of the naturally occurring isotopic pairs (35)Cl/(37)Cl and (79)Br/(81)Br, (ii) of the vibrational properties of related molecules, and (iii) of the properties predicted for the relevant molecules by quantum chemical calculations.

Effect of the mass media in promoting calls to the Cancer Information Service.

The Cancer Information Service is a toll-free telephone inquiry service that provides information about cancer and related resources to the public, patients and their families, and health-care providers. The service was created in 1975 to provide rapid access to the latest information about cancer, to address specific population needs, and to bridge gaps between cancer research and application. This article reviews a variety of ways in which the mass media have been used to promote calls to the Cancer Information Service. Conclusions are drawn about the usefulness of media promotion in the past, and recommendations are suggested for future media promotion of the service.

Promoting smoking cessation in the United States: effect of public service announcements on the Cancer Information Service telephone line.

BACKGROUND: Although many smokers report making attempts to quit, few seek help or are successful in their attempts. Some of the barriers to seeking help can be overcome by a telephone counseling and information service like that offered by the Cancer Information Service of the National Cancer Institute. This service has been promoted by antismoking public service announcements produced by the Office on Smoking and Health, Centers for Disease Control, Public Health Service, U.S. Department of Health and Human Services. PURPOSE: We determined whether such nationally televised public service announcements were associated with increased use of the Cancer Information Service. We assessed the importance of specifically promoting the telephone line and identified the characteristics of the individuals who responded to such promotion. METHODS: We combined the frequency-of-call data from the Cancer Information Service with the data on the frequency and reach of the television spots. RESULTS: During this 5-year study (1983-1987), the Cancer Information Service received a notably disproportionate number of calls in 3 specific months (August 1983, January 1985, and January 1987). In each case, more than 20% of all calls in that year were received in that month (expected percentage = 8% if the calls had been evenly distributed). These peak periods were associated with the showing of the three public service announcements that mentioned the telephone number of the Cancer Information Service. These promotions were particularly effective in increasing the percentage of callers who were male, who were under the age of 40 years, or who had received a high school education or less. CONCLUSIONS: Television is an effective medium for supporting antismoking goals by motivating more smokers to seek help to quit. IMPLICATIONS: It is important to identify whether the aid offered by the Cancer Information Service hotline is effective in helping the caller to quit. Future work must concentrate on the most effective strategies for using this initial contact to provide aid to prevent relapse, thus maximizing the potential impact of the public service announcement campaigns.

National programs for smoking cessation.

The smoking cessation effort has made tremendous progress since the 1964 Report of the Surgeon General described the health hazards of smoking. The impact of these efforts on smoking is particularly impressive when the current smoking level is compared with levels of smoking projected from trends apparent before that 1964 report, levels that might have been reached if there had been no national stop-smoking campaign. Because of the campaign, an estimated 35 million Americans were nonsmokers in 1985 who would otherwise have been smokers. If these figures are projected to the year 2000, the campaign will have postponed more than 2 million deaths. Therefore, reducing the prevalence of smoking in adults from about 40% in 1964 to 29% in 1987 can be considered a tremendous public health achievement. Among those who did take up smoking, there is also reason for some optimism. By 1987, more than 38 million Americans had quit smoking; this figure represents nearly half of all living adults who ever smoked. The 1990 Report of the Surgeon General gave a positive message to the 50 million Americans who continue to smoke by describing the health benefits of quitting for all the major smoking-related diseases.

Past lessons and new uses of the mass media in reducing tobacco consumption.

A review of mass media response to the smoking issue over the past 25 years reveals that sustained involvement of the broadcast and print media has served significantly to heighten public awareness and reduce smoking rates in the total U.S. population. Public service advertising has been an integral part of the smoking control movement from its outset, but today's intensely competitive media environment has forced health promoters to look beyond public service announcements in the development of total communication programs. Media advocacy--using the media to sharpen public awareness and mold public policy to serve the public interest, a technique derived from political campaigns--is emerging as a powerful tool in the smoking control movement. Its emphasis is on changing the entire social context of tobacco use in America, rather than the smoking behavior of people. Because media advocates' success pivots on their access to the media, they must be able both to create news and to react quickly to breaking news and unexpected events. The opportunistic, risk-taking nature of media advocacy requires that most efforts be waged at the State and local levels. An increasing number of State health departments and other organizations are using paid advertising to improve the frequency and reach of nonsmoking messages. Research verifies that paid media campaigns increase the target audience's exposure to smoking control messages, but planning and making efficient media purchases require sophistication and, of course, the necessary funds. Irrefutable medical evidence linking smoking to disease and addiction, combined with the powerful social force of the nonsmokers' rights movement, offer hope that a smoke-free society is an achievable goal. Success,however, will only be realized if tobacco control activists make use of the full range of mass media technologies to sustain and nourish this momentum.