Evaluation of Colletotrichum gloeosporioides for Biological Control of Miconia calvescens in Hawaii.

Miconia calvescens (Melastomataceae), from the Neotropics, is a noxious forest weed in Hawaii. We evaluated an isolate of Colletotrichum gloeosporioides that causes leaf spots on Miconia spp. in Brazil for its potential in biological control. Hawaii has no native Melastomataceae genera but does have members of 12 introduced genera. Following Wapshere's centrifugal phylogenetic method (2), eight species of Melastomataceae genera in Hawaii were inoculated in addition to Miconia spp. Naturalized and native Hawaiian members of the order Myrtales also were inoculated to determine host specificity, including Terminalia catappa (Combretaceae); Cuphea hysopifolia and C. ignea (Lythraceae); Arthrostema ciliatum, Clidemia hirta, Dissotis rotundifolia, Heterocentron subtriplinervium, Medinilla scortechenii, Melastoma candidum, Pterolepsis glomerata, and Tibouchina herbaceae (Melastomataceae); Eucalyptus grandis, Eucalyptus microcorys, Eugenia reinwardtiana, Eugenia uniflora, Leptospermum laevigatum, Melaleuca quinquenervia, Metrosideros polymorpha, Psidium guajava, and Syzgium malaccanse (Myrtaceae); Fuchsia magellanica and Oenothera stricta (Onagraceae); and Wikstroemia oahuensis and W. uva-ursi (Thymelaeaceae). All M. calvescens plants were grown from seed collected in Hawaii. Other test plants were grown from seeds or cuttings in artificial potting medium in a greenhouse. Plants had 6 to 8 mature leaves when inoculated. C. gloeosporioides was cultured on 10% potato dextrose agar supplemented with plain agar (35 g/liter) and incubated under constant fluorescent illumination at 20°C. Conidia were harvested by flooding 10-to 14-day-old cultures with sterile tap water, followed by light scraping with a scalpel. Conidial suspensions were adjusted to 106 conidia per ml and applied to both leaf surfaces with a hand-held sprayer. Inoculated plants were kept at 100% relative humidity and 16 to 25°C for 48 h. Four replicate plants and one plant of M. calvescens per species were inoculated. Plants were observed for symptom development for up to 6 weeks. The entire test was repeated once. Lesions were visible after 7 to 10 days. Young lesions had chlorotic halos and expanded in a roughly circular pattern to diameters of 5 to 10 mm. Mature lesions developed necrotic centers, coalesced, and became dry and brittle with age, resulting in extensive leaf necrosis. Defoliation of moderately to severely infected leaves occurred ≈ 30 days after inoculation. With the exception of M. calvescens, C. gloeosporioides did not produce visible symptoms on test plants. The failure of Clidemia hirta, the taxonomic species most closely related to M. calvescens, to become symptomatic was particularly significant relative to the centrifugal phylogenetic concept. The results demonstrate that our pathogen (VIC 19306) is distinct from C. gloeosporioides f. sp. clidemiae (1), which did not infect M. calvescens. We designate our pathogen C. gloeosporioides f. sp. miconiae. Voucher specimens (VIC 19306, Sana, RJ, 24.II.1998, and R. W. Barreto) and cultures are maintained at the Departamento de Fitopatologia, Universidade Federal de Viçosa MG, Brazil. References: (1) E. E. Trujillo et al. Plant Dis. 70:974, 1986. (2) A. J. Wapshere. Ann. Appl. Biol. 77:201, 1974.

Anabolic steroid use by male and female middle school students.

BACKGROUND: The prevalence of anabolic steroid use by high school and college students has been reported in the literature. However, rumors persist regarding the use of steroids by younger populations. OBJECTIVE: To assess the extent of steroid use by male and female middle school students and to explore their attitudes and perceptions about these drugs. Methods. A confidential self-report questionnaire was administered to 466 male and 499 female students between 9 and 13 years of age (mean +/- SD, 11.4 +/- 0.9 years) in 5th, 6th, and 7th grades from four public middle schools in Massachusetts. The number of students reporting steroid use and differences between users' and nonusers' underlying attitudes and perceptions about these drugs were evaluated. RESULTS: The response rate was 82% (965/1175 eligible). Results indicated that 2.7% of all middle school students reported using steroids; 2.6% were males and 2.8% were females. When steroid users were compared with nonusers, 47% versus 43% thought that steroids make muscles bigger; 58% versus 31% thought that steroids make muscles stronger; 31% versus 11% thought that steroids improve athletic performance; 23% versus 13% thought that steroids make one look better; 23% versus 9% knew someone their own age who currently took steroids; 38% versus 4% were asked by someone to take steroids; 54% versus 91% thought that steroids were bad for them; and 35% versus 2% indicated that they would take steroids in the future. Additional analyses determined steroid user involvement in sports and activities. CONCLUSION: The results of this study suggest that the problem of illicit steroid use extends to children and young adolescents and that a segment of this population is mindful of the potential physiologic effects of steroids. This information will be useful to pediatricians, sport authorities, and school teachers whose guidance will become increasingly more important as steroid educational interventions for male and female middle school students are developed.

Influence of exposure patterns of nitrogen dioxide and modifications by ozone on susceptibility to bacterial infectious disease in mice.

The nitrogen dioxide (NO2) diurnal cycle found in urban communities usually consists of a low basal concentration upon which are superimposed higher concentration peaks or spikes of short duration. Various components of this environmental exposure mode were examined to assess effects of urban exposure profiles on susceptibility to infectious pulmonary disease. Mice were exposed to NO2 peaks of 4.5 ppm for 1, 3.5, or 7 h, challenged with Streptococcus sp. either immediately or 18 h postexposure, and then observed for mortality. When the streptococcal challenges were immediately after NO2 exposure, the mortality rate was directly related to the length of peak exposure, whether or not a basal exposure was used, and all peak lengths significantly increased mortality. When the challenge was delayed for 18 h after the peak exposure, spiked exposures of 3.5 and 7 h increased mortality to the same degree. If a 1-h peak exposure to 4.5 ppm was superimposed twice daily upon a continuous basal NO2 concentration of 1.5 ppm, there was a suggestive trend toward increased mortality near the end of the second week of exposure when challenge occurred immediately after the morning spike. Studies were also conducted to examine interactions with ozone (O3) and NO2, since urban air typically contains both of these oxidants. Using various combinations of basal and spiked exposure levels of NO2 and O3, synergistic results were obtained for streptococcal-induced mortality.

Evaluating the toxicity of urban patterns of oxidant gases. II. Effects in mice from chronic exposure to nitrogen dioxide.

The study reported herein evaluates the influence of a chronic exposure to an urban pattern of NO2 (continuous baseline exposure of 0.2 ppm, on which were superimposed two 1-h spikes of 0.8 ppm NO2, 5 d/wk) as compared to the baseline exposure to determine the contribution of the spikes to toxicity. Mice were exposed for up to 52 wk with interim examinations. Multivariate analysis of variance revealed a statistically significant treatment effect on infectivity (p = 0.05) and pulmonary function (p = 0.03) parameters. Infectivity mortality of mice in the spiked exposure regimen was significantly greater than that in either the NO2-background-exposed mice or in control mice. Four of the pulmonary function variables exhibited the greatest differences among the treatment groups: end expiratory volume, vital capacity, respiratory-system compliance, and multiple-breath nitrogen washout. Results from the pulmonary-function analyses indicate that the spiked exposures to 0.8 ppm NO2 may have induced a subtle lesion. The chronic study results indicate that the presence of spikes of NO2 is contributing significantly to effects on antibacterial lung defenses and pulmonary function of mice.

Effects of cadmium inhalation on mitochondrial enzymes in rat tissues.

Pulmonary and extrapulmonary effects from a 2-h inhalation exposure to cadmium (850 micrograms Cd/m3) were studied in male rats. The effect of this chemical on mitochondrial enzyme activity in the lung, liver, kidney, and testis were investigated immediately after exposure and at 48, 144, and 336 h postexposure. In all tissues studied, mitochondrial citrate synthase activity was significantly increased immediately after the cessation of the exposure. This activity level began to decrease at 48 h postexposure. Succinic dehydrogenase activity was significantly decreased in the lungs and kidney at all periods tested, but increased activity was seen in the liver and testis. Cytochrome c oxidase activity in lungs and testis mitochondria was inhibited at all time periods studied. In the liver and kidney this activity was significantly increased immediately after the exposure ceased, and then a significant reduction began to appear at 48 h postexposure. This study demonstrates that inhaled cadmium, after deposition in the lungs, may alter various enzyme activities in other organs.

Effect of ozone on serum lipids and lipoproteins in the rat.

Exposure of male rats to 0 (air), 1, 1.75, and 3 ppm ozone (O3) 5 hr/day for a total of 10 days resulted in a positive linear relationship between ozone concentration and the concentrations of serum total lipoprotein free cholesterol (FCh) and high-density lipoprotein total cholesterol (HDL-Ch). The latter response was reflected in both its free (HDL-FCh) and esterified (HDL-ChE) components. On the other hand, serum triglycerides (TG) showed a marked decreasing linear trend with increasing ozone concentration. As judged by decreased body weights with no accompanying differences in feed consumption, apparent metabolic rate increased as ozone concentration increased. In another experiment, male rats were exposed 5 hr/day to either air or 1 ppm O3 for a total of 15 days. Groups of animals from each exposure were sampled at times ranging from immediately after to 44 hr postexposure. In agreement with the concentration response study, effects of O3 included increases in serum total cholesterol (Ch), HDL-Ch and HDL-FCh, and a decrease in TG. In addition, the degree of effects appeared to be maintained over the 44-hr period and to be greater than that observed at 1 ppm O3 in the concentration-response study.

Influence of ozone on pentobarbital pharmacokinetics in mice.

Previous studies have indicated that acute exposure to ambient concentrations of ozone (O3) as low as 196 micrograms/m3 (0.1 ppm) increases pentobarbital (PEN)-induced sleeping time in female mice. To elucidate potential mechanisms involved, additional studies were performed. A 3 h exposure to 9800 micrograms O3/m3 (5 ppm) did not affect brain concentrations of PEN at time of awakening, even though sleeping time was increased. Exposure for 3 h to 9800 micrograms O3/m3 (5 ppm) did not alter the pattern of brain or plasma metabolites of PEN. Pentobarbital clearance followed first-order kinetics with a one-compartment model. Mice exposed to 9800 micrograms O3/m3 (5 ppm) for 3 h had a 106% increase in the plasma half-life of pentobarbital; at 1960 micrograms O3/m3 (1 ppm) for 3 h, a 71% increase was observed. It therefore appears possible that PEN-induced sleeping time might be increased due to an decrease in hepatic metabolism of PEN.

Alterations in macrophage functions by environmental chemicals.

The establishment of infectious diseases is rarely entirely attributed to a single entity, but instead is the result of a primary stress and one or more secondary factors that interfere with homeostasis and the ability of the host to cope with the primary etiologic assault. Any environmental chemical that can suppress the normal functioning of the host's body defenses would be expected to increase the risk of the host to such diseases. Within the lung, the alveolar macrophages are the crucial elements responsible for defending the body against such airborne viable agents. The effects of inhaled gases and particulates on these defense cells are a major concern of the environmental health scientist since such chemicals have the capability of adversely affecting the integrity and functioning of these pulmonary defense cells. The objective of this report is to provide an overview that will improve our understanding of how a variety of environmental chemicals can alter the biochemical, physiological and immunological functioning of these cells.

A comparison of biochemical effects of nitrogen dioxide, ozone, and their combination in mouse lung.

Swiss Webster mice were exposed to either 4.8 ppm (9024 microgram/m3) nitrogen dioxide (NO2), 0.45 ppm (882 microgram/m3) ozone (O3), or their combination intermittently (8 hr daily) for 7 days, and the effects were studied in the lung by a series of physical and biochemical parameters, including lung weight, DNA and protein contents, oxygen consumption, sulfhydryl metabolism, and activities of NADPH generating enzymes. The results show that exposure to NO2 caused relatively smaller changes than O3, and that the effect of each gas alone under the conditions of exposure was not significant for most of the parameters tested. However, when the two gases were combined, the exposure caused changes that were greater and significant. Statistical analysis of the data shows that the effects of combined exposure were more than additive, i.e., they might be synergistic. The observations suggest that intermittent exposure to NO2 or O3 alone at the concentration used may not cause significant alterations in lung metabolism, but when the two gases are combined the alterations may become significant.

Oxidant-induced enhanced sensitivity to infection in animal models and their extrapolations to man.

Animal studies have provided the toxicologist with useful and scientifically sound information indicating that exposure to oxidant gases can alter the functioning of the host's normal pulmonary defense system, resulting in an increased risk to infectious disease. Since the basic mechanisms of action of the human and the animal pulmonary defenses are similar, it is reasonable to relate these animal's biological responses to human exposures. This paper examines the possibility of quantitatively extrapolating such animal dose-response data to humans.

The changing role of animal toxicology in support of regulatory decisions.

The Clean Air Act is the basic U.S. Federal law for controlling air pollution. Under Sections 108 and 109, primary (health) national ambient air quality standards (NAAQS) can be set for pollutants which are ubiquitous in the ambient air. The standard-setting process includes a comprehensive summary of scientific information on effects and controls in criteria and control techniques, and the selection of an appropriate standard which, in the judgment of the Administrator, protects the health of normal and susceptible subpopulations with an adequate margin of safety. Determining the adequacy of existing NAAQS or establishing new standards requires that the scientific information base be evaluated to assess pollutant effects on public health. Improvements in this process can be accomplished not only through new health effects research, but also through improved use of currently available data. The commonality joining these two efforts is in the area of extrapolation modeling, which is the topic of this paper. Extrapolation modeling involves determining the effective dose delivered to the target organ of several species and the sensitivity of the target organ to that dose so that effective pollutant concentrations can be estimated across species. This in turn allows greater utilization of the results from animals in making judgments about the effects in man from exposure to a given pollutant.

A solid-phase radioimmunoassay for detection of antibodies against Mycoplasma pneumoniae.

A solid-phase radioimmunoassay (RIA) for the detection of Mycoplasma pneumoniae antibodies is described. This method uses M. pneumoniae organisms grown in microtiter plate wells as a solid-phase antigen that is economical and easy to prepare. Results obtained from our studies indicate this RIA method is highly sensitive and reproducible. This is a more specific assay than the popular complement fixation (CF) method because the glycolipid haptens employed in the CF test are not unique to M. pneumoniae. Data on 34 serum samples from 12 patients indicate the applicability of this diagnostic method for clinical use. In addition, this method measures the immunoglobulin class-specific antibody activities which may be important in differentiating recent and past infections.

Pulmonary function in normal and elastase-treated hamsters exposed to a complex mixture of olefin-ozone-sulfur dioxide reaction products.

An elastase-induced emphysema model was utilized to determine if hamsters with preexisting lung disease were more susceptible to lung damage from air pollutant exposure. Male golden hamsters, divided into two treatment groups, were given a single intratracheal injection of either 6 units of porcine pancreatic elastase (EMP) or buffer (CNT). After a 4-week recovery period, equal numbers of each group were exposed 23 hr/day X 28 day to filtered air (AIR) or to the complex by-products from a dark phase reaction mixture of trans-2-butene, ozone, and sulfur dioxide (MIX). Lung function measurements on the elastase-treated groups showed changes consistent with mild emphysema. There were no significant differences in lung volumes or lung compliance between the AIR- and MIX-exposed animals. However, the nitrogen washout slope decreased (P less than 0.05), and the diffusing capacity for carbon monoxide increased (P less than 0.05) in both the CNT and EMP hamsters exposed to the MIX. The change in diffusing capacity was greater (P less than 0.05) in normal hamsters than in hamsters with emphysema, and it is hypothesized that animals with impaired lung function had a decreased ability to respond to a pulmonary insult from the mix.