Comparative pulmonary toxicity assessment of single-wall carbon nanotubes in rats.

The aim of this study was to evaluate the acute lung toxicity of intratracheally instilled single-wall carbon nanotubes (SWCNT) in rats. The lungs of rats were instilled either with 1 or 5 mg/kg of the following control or particle types: (1) SWCNT, (2) quartz particles (positive control), (3) carbonyl iron particles (negative control), (4) phosphate-buffered saline (PBS) + 1% Tween 80, or (5) graphite particles (lung tissue studies only). Following exposures, the lungs of PBS and particle-exposed rats were assessed using bronchoalveolar lavage (BAL) fluid biomarkers and cell proliferation methods, and by histopathological evaluation of lung tissue at 24 h, 1 week, 1 month, and 3 months postinstillation. Exposures to high-dose (5 mg/kg) SWCNT produced mortality in ~15% of the SWCNT-instilled rats within 24 h postinstillation. This mortality resulted from mechanical blockage of the upper airways by the instillate and was not due to inherent pulmonary toxicity of the instilled SWCNT particulate. Exposures to quartz particles produced significant increases versus controls in pulmonary inflammation, cytotoxicity, and lung cell parenchymal cell proliferation indices. Exposures to SWCNT produced transient inflammatory and cell injury effects. Results from the lung histopathology component of the study indicated that pulmonary exposures to quartz particles (5 mg/kg) produced dose-dependent inflammatory responses, concomitant with foamy alveolar macrophage accumulation and lung tissue thickening at the sites of normal particle deposition. Pulmonary exposures to carbonyl iron or graphite particles produced no significant adverse effects. Pulmonary exposures to SWCNT in rats produced a non-dose-dependent series of multifocal granulomas, which were evidence of a foreign tissue body reaction and were nonuniform in distribution and not progressive beyond 1 month postexposure (pe). The observation of SWCNT-induced multifocal granulomas is inconsistent with the following: (1) lack of lung toxicity by assessing lavage parameters, (2) lack of lung toxicity by measuring cell proliferation parameters, (3) an apparent lack of a dose response relationship, (4) nonuniform distribution of lesions, (5) the paradigm of dust-related lung toxicity effects, (6) possible regression of effects over time. In addition, the results of two recent exposure assessment studies indicate very low aerosol SWCNT exposures at the workplace. Thus, the physiological relevance of these findings should ultimately be determined by conducting an inhalation toxicity study.

The tropical African latrine blowfly, Chrysomya putoria (Wiedemann).

The status of the tropical African latrine blowfly Chrysomya putoria (Wiedemann, 1830) is recognized as distinct from the sub-tropical African blowfly C.chloropyga (Wiedemann, 1818) (Diptera: Calliphoridae). The biology of C.putoria in laboratory culture is described briefly with emphasis on the differences in development found in three strains of this species from Tanzania, Liberia and Brazil. All three strains were reproductively compatible and there was no evidence of F1 hybrid sterility or hybrid breakdown in subsequent generations. Larval development was significantly faster in the Brazilian strain than in the strain from Tanzania. Sexual maturity was significantly faster in adults of the Liberian and Brazilian strains compared to that found in the strain from Tanzania. This latter strain was affected by the source of protein available as adult food. These differences between strains did not appear to be due to selection in laboratory culture, but rather evidence of the evolution of physiological divergence within a species occupying different geographical regions.

Old world blowflies in the new world.

Human activity, particularly migration and the export of live animals, can provide vehicles for the dispersal of many parasites and their vectors. These movements, often overlooked until too late, provide potential for epidemic outbreaks and can profoundly alter accepted ideas on the geographic distribution and epidemiological status of particular species. In this review, Brian Laurence discusses the recent rapid spread of blowflies into the americas; these conspicious green flies transport a variety of gastro-intestinal pathogens between their favoured environments of latrines and exposed food, and some species are important parasites of flesh wounds, causing cutaneous myiasis.

Absolute configuration of mosquito oviposition attractant pheromone, 6-acetoxy-5-hexadecanolide.

6-Acetoxy-5-hexadecanolide (Ia) in the oviposition attractant pheromone released from egg apical droplets of the mosquitoCulex pipiens fatigans Wied. is shown to be the (-)-(5R,6S)- enantiomer. Identification was by chromatography of the 6-trifluoroacetoxy derivatives of the natural pheromone and of the synthetic (-)-(5R,6S)- (Ib) and (+)-(5S,6R)- (IIb) enantiomers on a capillary column having a chiral stationary phase comprising a derivative of (1S,3S)-chrysanthemic acid. The synthetic (-)-(5R,6S)- enantiomer (Ia) attracted oviposition of four fold more mosquito egg rafts than the control (P < 0.01) whereas for the (5S,6R)- enantiomer (IIa) there was no statistically significant oviposition attraction.

Incorporation of radioactive precursors into filarial larvae of Brugia developing in susceptible and refractory mosquitoes.

The incorporation of tritiated precursors injected into mosquito hosts parasitized by developing filarial larvae of Brugia patei has been studied by autoradiography in 2 species of mosquito, Aedes togoi in which filarial development was normal and Anopheles labranchiae atroparvus in which filarial development was abnormal. In both mosquito hosts there was significant incorporation into 4--5-day-old developing larvae of uridine and amino acids (isoleucine, leucine, valine, arginine, lysine, cystine, methionine, phenylalanine, tyrosine, tryptophan, histidine, and proline), although lower incorporation of methionine, tyrosine, and tryptophan was found during abnormal development. No incorporation of thymidine, hydroxytryptophan, dopa, or carbohydrate was found at this stage of larval development. Some incorporation of glucose and dopa was found in or around earlier stages of development in An. l. atroparvus. Mosquito flight muscle showed lower incorporation of glucose, but not of amino acids, around the site of filarial parasite development. The flight muscle of An. l. atroparvus showed a higher level of incorporation of lysine compared to that in A. togoi and higher levels of lysine and valine were found in the abnormally developing filarial larvae in the refractory mosquito.