Protection against Dimethylnitrosamine Toxicity by Pregnenolone-16α-Carbonitrile

SINCE the discovery of the hepatotoxic¹ and carcinogenic² effect of dimethylnitrosamine (DMN), the significance of various nitroso-compounds as potential carcinogens in man has aroused increasing attention^3–8, especially since the demonstration of the endogenous production of nitrosocarcinogens from dietary amines or amides and sodium nitrite^9–15. Cellular damage resulting from exposure to nitrosamines has been attributed to unidentified metabolite(s) which alkylate nucleic acids, rather than to the parent compounds themselves^16–18 and certain agents (for example, aminoacetonitrile^19–21, polycyclic aromatic hydrocarbons^22,23, protein-free diet^24,25) which inhibit the metabolic degradation of DMN were subsequently found to reduce its acute toxicity and hepatocarcinogenicity.     

The prevalence and correlates of DSM-IV disorders in the Iraq Mental Health Survey (IMHS)

Data on the prevalence and correlates of anxiety, mood, behavioral, and substance disorders are presented from a 2007-8 national survey of the Iraq population, the Iraq Mental Health Survey (IMHS). The IMHS was carried out by the Iraq Ministry of Health in collaboration with the Iraq Ministry of Planning and the World Health Organization (WHO) World Mental Health (WMH) Survey Initiative. Interviews were administered to a probability sample of Iraqi household residents by trained lay interviewers. The WHO Composite International Diagnostic interview (CIDI) was used to assess DSM-IV disorders. The response rate was 95.2%. The estimated lifetime prevalence of any disorder was 18.8%. Cohort analysis documented significantly increasing lifetime prevalence of most disorders across generations. This was most pronounced for panic disorder and post-traumatic stress disorder, with lifetime-to-date prevalence 5.4-5.3 times as high at comparable ages in the youngest (ages 18-34) as oldest (ages 65+) cohorts. Anxiety disorders were the most common class of disorders (13.8%) and major depressive disorder (MDD) the most common disorder (7.2%). Twelve-month prevalence of any disorder was 13.6%, with 42.1% of cases classified mild, 36.0% moderate, and 21.9% serious. The disorders most often classified serious were bipolar disorder (76.9%) and substance-related disorders (54.9%). Socio-demographic correlates were generally consistent with international epidemiological surveys, with the two exceptions of no significant gender differences in mood disorders and positive correlations of anxiety and mood disorders with education. Only 2.2% of IMHS respondents reported receiving treatment for emotional problems in the 12 months before interview, including 23.7% of those with serious, 9.2% with moderate, and 5.3% with mild disorders and 0.9% of other respondents. Most healthcare treatment, which was roughly equally distributed between the general medical and specialty sectors, was of low intensity. Further analyses of barriers to seeking treatment are needed to inform government efforts to expand the detection and treatment of mental disorders     

Improved Method for Axenizing Blepharisma by Means of Antibiotics

Synopsis.
A simplified method for obtaining axenic cultures of Blepharisma involves the use of penicillin, streptomycin, and tetracycline. Cytologic examination disclosed no significant effect of these antibiotics on the structure of the ciliates.     

Relationship between reflectance spectra of host plant surfaces and visual detection of host fruit by Rhagoletis pomonella flies

ABSTRACT. Within host trees, male and female Rhagoletis pomonella (Walsh) flies locate visually individual fruit of apple and hawthorn, which are sites of mating and oviposition. By measuring the diffuse reflectance spectra of both fruit and foliage and by using artificially pigmented natural fruit and artificial fruit mimics, we show that fruit hue is not as important in R. pomonella fruit detection as is intensity contrast of dark fruit against a bright background of light transmitted through foliage or skylight. In discussing the fruit detection system of R. pomonella , we compare it to that of vertebrate fruit consumers and seed dispersers.     

Air-surface exchange measurement in heterogeneous regions: extending tower observations with spatial structure observed from small aircraft

Strategies to assess long-term atmosphere-ecosystem exchange of CO₂ and H₂O must deal not only with time trends but also with spatial variability. Flux towers efficiently measure time trends, but only at discrete sites, always limited in number. Representativeness of these sites and the causes of spatial variation between sites are difficult to investigate from tower data alone. Such issues are better addressed with flux measurements from moving vehicles, particularly aircraft. Recent technological advancements in aircraft and instrumentation now allow mobile flux measurement with enhanced precision, greater ease, and lower cost. Results are presented which illustrate the importance of spatial variability, and some suggestions are given for assessment of flux-tower representativeness. Unfortunately, airborne observations of the kind presented here are practical only during a part of the daylight hours in brief intensive field campaigns. Extrapolation of spatial-structure information derived from these measurements to night-time or to long-term averages thus remains problematic. For the foreseeable future this extrapolation will require models that faithfully simulate both space and time characteristics of H₂O and CO₂ exchange. The development and validation of such models will be greatly enhanced by the increased availability of measurements from moving vehicles, which record spatial as well as temporal structure.     

Courtship, spermatophores and eggs of the Mexican Achoque, Ambystoma (Bathysiredon) dumerili (Dugés)

Detailed reproductive data on this salamander endemic to Lake Patzcuaro, Michoacan, are reported for the first time, and were obtained from a laboratory colony. This species is relatively easy to culture in the laboratory, and it should be useful in experimental zoological studies. The courtship resembles closely that of Ambystoma tigrinum. Four matings resulted in deposition of 9 to 16 spermatophores. The large (10 to 28 mm in diameter) spermatophores are topped by an undetachable cap of seminal fluid (2times3 mm). Females apparently removed some seminal fluid from each of several caps. About one day after courtship each female laid eggs, 290 to 1120 per female per spawning; the total complement per year is probably 300 to 1700 depending on the size of the female. The relatively small (2.0–2.2 mm vitellus) and lightly pigmented eggs were attached to the substrate in long strands, in single file.     

Secondary production of Chironomidae (Diptera) in a north temperate stream

SUMMARY 1. Secondary production of chironomids (Diptera: Chironomidae) in a third-order northern Indiana stream was estimated using species-specific, and in most cases cohort-specific, life-history data from the field.
2. Chironomid life-history patterns were diverse, ranging from one to four generations per year in addition to asynchronous development. Cohort production intervals (CPI) for all taxa ranged from 56 to 266 days. CPI for cohorts of conspecifics differed up to 3-fold.
3. Annual secondary production was estimated using the instantaneous growth method or the size—frequency method depending on whether cohorts were distinguishable or not. Total annual chironomid production was 29 700 mg dry mass m⁻², which is the highest value reported for chironomids from a north temperate stream.
4. Eighty per cent of the total chironomid production was attributed to five species: Diamesa nivoriunda (33.9%), Cricotopus bicinctus (16.6%), Pagastia sp. (10.2%), C. trifascia (9.7%) and Orthodadius obumbratus (9.6%).
5. The annual P:B ratio ranged from 4.7 to 21.9. Thus, high secondary production was due to high mean annual standing stocks and not to rapid biomass turnover.