Re-evaluation of pulmonary titanium dioxide nanoparticle distribution using the "relative deposition index": Evidence for clearance through microvasculature

ABSTRACT: BACKGROUND: Translocation of nanoparticles (NP) from the pulmonary airways into other pulmonary compartments or the systemic circulation is controversially discussed in the literature. In a previous study it was shown that titanium dioxide (TiO2) NP were "distributed in four lung compartments (air-filled spaces, epithelium/endothelium, connective tissue, capillary lumen) in correlation with compartment size". It was concluded that particles can move freely between these tissue compartments. To analyze whether the distribution of TiO2 NP in the lungs is really random or shows a preferential targeting we applied a newly developed method for comparing NP distributions. METHODS: Rat lungs exposed to an aerosol containing TiO2 NP were prepared for light and electron microscopy at 1 h and at 24 h after exposure. Numbers of TiO2 NP associated with each compartment were counted using energy filtering transmission electron microscopy. Compartment size was estimated by unbiased stereology from systematically sampled light micrographs. Numbers of particles were related to compartment size using a relative deposition index and chi-squared analysis. RESULTS: Nanoparticle distribution within the four compartments was not random at 1 h or at 24 h after exposure. At 1 h the connective tissue was the preferential target of the particles. At 24 h the NP were preferentially located in the capillary lumen. CONCLUSION: We conclude that TiO2 NP do not move freely between pulmonary tissue compartments, although they can pass from one compartment to another with relative ease. The residence time of NP in each tissue compartment of the respiratory system depends on the compartment and the time after exposure. It is suggested that a small fraction of TiO2 NP are rapidly transported from the airway lumen to the connective tissue and subsequently released into the systemic circulation.

Ultraviolet radiation intensity predicts the relative distribution of dermatomyositis and anti-Mi-2 autoantibodies in women.

OBJECTIVE: Because studies suggest that ultraviolet (UV) radiation modulates the myositis phenotype and Mi-2 autoantigen expression, we conducted a retrospective investigation to determine whether UV radiation may influence the relative prevalence of dermatomyositis and anti-Mi-2 autoantibodies in the US. METHODS: We assessed the relationship between surface UV radiation intensity in the state of residence at the time of onset with the relative prevalence of dermatomyositis and myositis autoantibodies in 380 patients with myositis from referral centers in the US. Myositis autoantibodies were detected by validated immunoprecipitation assays. Surface UV radiation intensity was estimated from UV Index data collected by the US National Weather Service. RESULTS: UV radiation intensity was associated with the relative proportion of patients with dermatomyositis (odds ratio [OR] 2.3, 95% confidence interval [95% CI] 0.9-5.8) and with the proportion of patients expressing anti-Mi-2 autoantibodies (OR 6.0, 95% CI 1.1-34.1). Modeling of these data showed that these associations were confined to women (OR 3.8, 95% CI 1.3-11.0 and OR 17.3, 95% CI 1.8-162.4, respectively) and suggests that sex influences the effects of UV radiation on autoimmune disorders. Significant associations were not observed in men, nor were UV radiation levels related to the presence of antisynthetase or anti-signal recognition particle autoantibodies. CONCLUSION: This first study of the distribution of myositis phenotypes and UV radiation exposure in the US showed that UV radiation may modulate the clinical and immunologic expression of autoimmune disease in women. Further investigation of the mechanisms by which these effects are produced may provide insights into pathogenesis and suggest therapeutic or preventative strategies.

Complex syntax in autistic spectrum disorders: A study with relative clauses

Background The few studies that have evaluated syntax in autism spectrum disorder (ASD) have yielded conflicting findings: some suggest that once matched on mental age, ASD and typically developing controls do not differ for grammar, while others report that morphosyntactic deficits are independent of cognitive skills in ASD. There is a need for a better understanding of syntax in ASD and its relation to, or dissociation from, nonverbal abilities. Aims Syntax in ASD was assessed by evaluating subject and object relative clause comprehension in adolescents and adults diagnosed with ASD with a performance IQ within the normal range, and with or without a history of language delay. Methods & Procedures Twenty-eight participants with ASD (mean age 21.8) and 28 age-matched controls (mean age 22.07) were required to point to a character designated by relative clauses that varied in syntactic complexity. Outcomes & Results Scores indicate that participants with ASD regardless of the language development history perform significantly worse than age-matched controls with object relative clauses. In addition, participants with ASD with a history of language delay (diagnosed with high-functioning autism in the DSM-IV-TR) perform worse on subject relatives than ASD participants without language delay (diagnosed with Asperger syndrome in the DSM-IV-TR), suggesting that these two groups do not have equivalent linguistic abilities. Performance IQ has a positive impact on the success of the task for the population with ASD. Conclusions & Implications This study reveals subtle grammatical difficulties remaining in adult individuals with ASD within normal IQ range as compared with age-matched peers. Even in the absence of a history of language delay in childhood, the results suggest that a slight deficit may nevertheless be present and go undetected by standardized language assessments. Both groups with and without language delay have a similar global performance on relative clause comprehension; however, the study also indicates that the participants with reported language delay show more difficulty with subject relatives than the participants without language delay, suggesting the presence of differences in linguistic abilities between these subgroups of ASD.

Late Cenozoic silicoflagellate biostratigraphy, relative paleotemperature, and distribution of various genera and morphologic subgroups with remarks on noteworthy occurrences at DSDP Leg 86 Holes

A quantitative study of late Cenozoic silicoflagellates from the northwestern Pacific sites of Deep Sea Drilling Project Leg 86 shows a relative paleotemperature (Ts) gradient with lowest values (Ts = 30) in the north. Some new ecostratigraphic relations for the region are indicated, such as the last common occurrence of Dictyocha brevispina at 2.6 - 3.0 m.y. ago during a cool interval. Elements of North Pacific and low-latitude biostratigraphic zonations can be identified, but the mixing of cool- and warm-indicator taxa prompted the definition of the new Miocene Mesocena hexalitha Subzone and Pliocene Distephanus jimlingii Subzone. Scanning-electron microscope study of Leg 86 silicoflagellates was done to determine whether various types of skeletal surface texture are temperature dependent. To conduct the study we organized a new surface-texture descriptive code, which characterizes the apical structure/basal ring/spine sequence using new definitions of the terms crenulate (C), linear (L), nodular (N), reticulate (R), and smooth (S). One new silicoflagellate genus, Caryocha Bukry et Monechi, n. gen., is described and several new combinations are made.

Vertical distribution of relative numbers of the main groups of sound-scattering fishes in the Central Indian Ocean

Findings made in 31 catches with an Isaacs-Kidd midwater trawl in the light (09.00-16.00) and dark (21.00-04.00) periods of a day within a survey area of about 100 sq. miles with approximate center coordinates of 13°S and 78°E have been used to investigate vertical distribution of the main groups of sound-scattering fishes (35 species of the family Myctophidae and 16 species of other families). It has been shown that during daylight hours all fishes sink to depths deeper than 400 m. Data are presented concerning the fish population of night-time sound-scattering layers at depths of 70-150 m and about 400 m and of the daytime ones at depths of about 450 m.