Performance of BAC for DBPs precursors' removal for one year with micro-polluted lake water in East-China

Effectiveness of biological activated carbon (BAC) filter in removing disinfection byproducts (DBPs) precursors of micro-polluted lake water for one year was conducted. The formation potential (FP) of DBPs (trihalomethanes (THMs), haloacetic acids (HAAs) and Nitrosamines (NAs)), dissolved organic carbon (DOC), molecular weight (MW) distribution and excitation emission matrix fluorescence (EEM) of dissolved organic material (DOM) in the influent and effluent of BAC were determined. The results indicated that the removal efficiency (RE) of DOC ranged from 42.9-28.3%. Neither virgin GAC nor long-term operated BAC could efficiently dispose of THMs and HAAs precursors (RE from 35.2-18.8%, from 42 to 8.4%, respectively), however, BAC still showed good ability in removal of NAs precursors after a year operation, of which RE just dropped from 81.7-69.6%. There was strong correlation between RE of NAs precursors and DOC with small MW (<0.5 kDa). The removal of HAAs precursors showed relatively close relation to aromatic protein-like components and soluble microbial pollutants (SMPs). Weak direct relationship was found between the water quality parameters and THMs precursors.

Modal analysis and efficient coupling of TE₀₁ mode in small-core THz Bragg fibers

We report a design of low-loss THz Bragg fibers with a core size on the order of wavelength that operates near the cutoff frequency of its TE01 mode. We also propose a broadband Y-type mode converter based on branched rectangular metallic waveguides to facilitate coupling between the TE01 mode of the Bragg fiber and the TEM mode in free space with 60% efficiency. Our fiber holds strong promise to facilitate beam-wave interaction in gyrotron for high-efficiency THz generation.

Factors Affecting the Incidence of Angel Wing in White Roman Geese: Stocking Density and Genetic Selection

The present study investigated stocking density and genetic lines, factors that may alter the severity and incidence of angel wing (AW), in White Roman geese. Geese (n = 384) from two genetically selected lines (normal- winged line, NL, and angel-winged line, AL, respectively) and one commercial line (CL) were raised in four pens. Following common commercial practice, low-stocking-density (LD), medium-stocking-density, and high-stocking-density treatments were respectively administered to 24, 32, and 40 geese per pen at 0 to 3 weeks (1.92 m²/pen) and 4 to 6 weeks (13.2 m²/pen) of age and to 24, 30, and 36 geese at 7 to 14 weeks (20.0 m²/pen) of age. The results revealed that stocking density mainly affected body weight gain in geese younger than 4 weeks, and that geese subjected to LD had a high body weight at 2 weeks of age. However, the effect of stocking density on the severity score of AW (SSAW) and incidence of AW (IAW) did not differ significantly among the treatments. Differences were observed among the genetic stocks; that is, SSAW and IAW were significantly higher in AL than in NL and CL. Genetic selection generally aggravates AW, complicating its elimination. To effectively reduce IAW, stocking density, a suspected causal factor, should be lower than that presently applied commercially.

Selection for Duration of Fertility and Mule Duck White Plumage Colour in a Synthetic Strain of Ducks (Anas platyrhynchos)

A synthetic strain of ducks (Anas platyrhynchos) was developed by introducing genes for long duration of fertility to be used as mother of mule ducklings and a seven-generation selection experiment was conducted to increase the number of fertile eggs after a single artificial insemination (AI) with pooled Muscovy semen. Reciprocal crossbreeding between Brown Tsaiya LRI-2 (with long duration of fertility) and Pekin L-201 (with white plumage mule ducklings) ducks produced the G0. Then G1 were intercrossed to produce G2 and so on for the following generations. Each female duck was inseminated 3 times, at 26, 29, and 32 weeks of age. The eggs were collected for 14 days from day 2 after AI. Individual data regarding the number of incubated eggs (Ie), the number of fertile eggs at candling at day 7 of incubation (F), the total number of dead embryos (M), the maximum duration of fertility (Dm) and the number of hatched mule ducklings (H) with plumage colour were recorded. The selection criterion was the breeding values of the best linear unbiased prediction animal model for F. The results show high percentage of exhibited heterosis in G2 for traits to improve (19.1% for F and 12.9% for H); F with a value of 5.92 (vs 3.74 in the Pekin L-201) was improved in the G2. Heritabilities were found to be low for Ie (h (2) = 0.07±0.03) and M (h (2) = 0.07±0.01), moderately low for Dm (h (2) = 0.13±0.02), of medium values for H (h (2) = 0.20±0.03) and F (h (2) = 0.23±0.03). High and favourable genetic correlations existed between F and Dm (rg = 0.93), between F and H (rg = 0.97) and between Dm and H (rg = 0.90). The selection experiment showed a positive trend for phenotypic values of F (6.38 fertile eggs in G10 of synthetic strain vs 5.59 eggs in G4, and 3.74 eggs in Pekin L-201), with correlated response for increasing H (5.73 ducklings in G10 vs 4.86 in G4, and 3.09 ducklings in Pekin L-201) and maximum duration of the fertile period without increasing the embryo mortality rate. The average predicted genetic response for F was 40% of genetic standard deviation per generation of selection. The mule ducklings' feather colour also was improved. It was concluded that this study provided results for a better understanding of the genetics of the duration of fertility traits in the common female duck bred for mule and that the selection of a synthetic strain was effective method of improvement.

Genomewide Study of Salivary MicroRNAs for Detection of Oral Cancer

MicroRNAs (miRNAs) in human saliva have recently demonstrated to be potential biomarkers for diagnosis purposes. However, lack of well-characterized/matched clinical groups and lack of suitable endogenous control (EC) for salivary extracellular miRNA detection and normalization are among the restrictions of applying salivary-based miRNA biomarker discovery. In the present study, we examined the differential expression pattern of miRNAs among 4 groups of subjects-including patients with oral squamous cell carcinoma (OSCC), patients with OSCC in remission (OSCC-R), patients with oral lichen planus, and healthy controls (HCs)-using a genomewide high-throughput miRNA microarray. First, we systematically screened 10 pooling samples and 34 individual samples of different groups to find a proper EC miRNA. We then investigated the genomewide expression patterns of differentially expressed miRNAs in saliva of different groups using NanoString nCounter miRNA expression assay and real-time quantitative polymerase chain reaction, followed by construction of receiver operating characteristic curves to determine the sensitivity and specificity of the assay. We identified miRNA-191 as a suitable EC miRNA with minimal intergroup and intragroup variability, and we used it for normalization. Of more than 700 miRNAs tested, 13 were identified as being significantly deregulated in saliva of OSCC patients compared to HCs: 11 miRNAs were underexpressed (miRNA-136, miRNA-147, miRNA-1250, miRNA-148a, miRNA-632, miRNA-646, miRNA668, miRNA-877, miRNA-503, miRNA-220a, miRNA-323-5p), and 2 miRNAs were overexpressed (miRNA-24, miRNA-27b). MiRNA-136 was underexpressed in both OSCC vs. HCs and OSCC vs. OSCC-R. MiRNA-27b levels were significantly higher in OSCC patients compared to those found in HCs, patients with OSCC-R, and patients with oral lichen planus and served as a characteristic biomarker of OSCC. Receiver operating characteristic curve analyses showed that miRNA-27b could be a valuable biomarker for distinguishing OSCC patients from the other groups. Our novel findings established a reliable EC miRNA for salivary-based diagnostic and indicate that the salivary miRNA profiles are discriminatory in OSCC patients.

Evaluation of a novel personal nanoparticle sampler

This work investigated the performance in terms of collection efficiency and aspiration efficiency of a personal sampler capable of collecting ultrafine particles (nanoparticles) in the occupational environment. This sampler consists of a cyclone for respirable particle classification, micro-orifice impactor stages with an acceleration nozzle to achieve nanoparticle classification and a backup filter to collect nanoparticles. Collection efficiencies of the cyclone and impactor stages were determined using monodisperse polystyrene latex and silver particles, respectively. Calibration of the cyclone and impactor stages showed 50% cut-off diameters of 3.95 μm and 94.7 nm meeting the design requirements. Aspiration efficiencies of the sampler were tested in a wind tunnel with wind speeds of 0.5, 1.0, and 1.5 m s(-1). The test samplers were mounted on a full size mannequin with three orientations toward the wind direction (0°, 90°, and 180°). Monodisperse oleic acid aerosols tagged with sodium fluorescein in the size range of 2 to 10 μm were used in the test. For particles smaller than 2 μm, the fluorescent polystyrene latex particles were generated by using nebulizers. For comparison of the aspiration efficiency, a NIOSH two-stage personal bioaerosol sampler was also tested. Results showed that the orientation-averaged aspiration efficiency for both samplers was close to the inhalable fraction curve. However, the direction of wind strongly affected the aspiration efficiency. The results also showed that the aspiration efficiency was not affected by the ratio of free-stream velocity to the velocity through the sampler orifice. Our evaluation showed that the current design of the personal sampler met the designed criteria for collecting nanoparticles ≤100 nm in occupational environments.

Aerosolised 5-azacytidine suppresses tumour growth and reprogrammes the epigenome in an orthotopic lung cancer model

BACKGROUND

Epigenetic silencing by promoter methylation and chromatin remodelling affects hundreds of genes and is a causal event for lung cancer. Treatment of patients with low doses of the demethylating agent 5-azacytidine in combination with the histone deacetylase inhibitor entinostat has yielded clinical responses. The subcutaneous dosing route for consecutive days and reduced bioavailability of 5-azacytidine because of inactivation by cytidine deaminase may limit the expansion of epigenetic therapy into Phase III trials. To mitigate these barriers, an aerosol of 5-azacytidine was generated and characterised.

METHODS

The effect of aerosol vs systemic delivery of 5-azacytidine on tumour burden and molecular response of engrafted lung tumours in the nude rat was compared.

RESULTS

Pharmacokinetics revealed major improvement in the half-life of 5-azacytidine in lung tissue with aerosol delivery. Aerosolised 5-azacytidine significantly reduced lung tumour burden and induced global demethylation of the epigenome at one-third of the comparable effective systemic dose. High commonality for demethylation of genes was seen in tumours sampled throughout lung lobes and across treated animals receiving the aerosolised drug.

CONCLUSION

Collectively, these findings show that aerosolised 5-azacytidine targets the lung, effectively reprogrammes the epigenome of tumours, and is a promising approach to combine with other drugs for treating lung cancer.

Biodegradable rapamycin-eluting nano-fiber membrane-covered metal stent placement to reduce fibroblast proliferation in experimental stricture in a canine model

BACKGROUND AND STUDY AIMS

The aim of the current study was to assess whether placement of the biodegradable rapamycin-eluting nano-fiber membrane-covered metal stent is followed by less fibroblast proliferation and tissue hyperplasia compared with bare stents in experimental stricture in a dog model.

METHODS

A total of 80 dog models of stricture were randomly divided into a control group (n = 20, no stent insertion), a bare stent group (BSG, n = 20, 1-week retention), and two drug-eluting stent sub-groups (DESG-1w, n = 20, 1-week retention; DESG-4w, n = 20, 4-week retention). Lower esophageal sphincter (LES) pressure, 5-minute barium height (5-mBH), and cardia diameter were assessed before, immediately after the procedure, and regularly thereafter for 6 months. Five dogs in each group were euthanized for histological examination at each follow-up assessment.

RESULTS

Stent insertion was well tolerated, with similar migration rates (0 % in BSG vs. 7.5 % in DESGs; P = 0.5441). At 6 months, LES pressure and 5-mBH improved in DESG-1w (26.70 ± 5.02 mmHg and 6.50 ± 2.98 cm) and DESG-4w (20.16 ± 5.50 mmHg and 1.54 ± 0.98 cm) compared with BSG (39.94 ± 5.22 mmHg and 11.1 ± 5.46 cm) (P < 0.05), with DESG-4w being more stable than DESG-1w (P < 0.05). The cardia maintained greater patency in the DESGs (7.10 ± 3.09 mm in DESG-1w; 9.16 ± 3.77 mm in DESG-4w) than in the BSG (1.86 ± 2.45 mm; P < 0.05). Reduced peak inflammatory reactions and scarring occurred in DESGs compared with the BSG (P < 0.05), with a better outcome in DESG-4w than in DESG-1w (P < 0.05).

CONCLUSIONS

In this experimental stricture model, rapamycin-eluting stents were more effective than bare stents for the reduction of fibroblast proliferation and tissue hyperplasia after stent placement. Furthermore, 4-week retention of the drug-eluting stent led to a better outcome than 1-week retention.

Nasal deposition in infants and children

BACKGROUND

The variability of particle deposition in infant and child nasal airways is significant due to the airway geometry and breathing rate. Estimation of particle deposition in the nasal airway of this age group is necessary, especially for inhalation drug delivery application. Previous studies on nasal aerosol deposition were focused mostly on adult. A few empirical equations were also developed to calculate nasal deposition in different age groups of children. However, those studies have their limitations. The aim of this study is to find a simple way to calculate the nasal aerosol deposition in all age groups.

METHODS

An in vitro test of micrometer particle deposition in nasal airways for three different ages of infants and children is conducted. An adult nasal replica is also studied as a comparison. Monodisperse oleic acid aerosols ranging in size between 2 and 28 μm are delivered into the replica at the rest condition. This size range covers the deposition efficiency up to around 100%. This study also compares results from our previous deposition tests with a 5-year-old replica.

RESULTS

Nasal deposition of micrometer aerosols in small children and infants is higher than that in adults under equivalent breathing conditions, e.g., sitting awake in this study. Combining the data set of infants, children, and adults, we found the deposition in the nasal airway strongly depends on the particle size and pressure drop. The particle deposition can be calculated based on a single empirical equation in all age groups. The intersubject variability within the same age group was not addressed in this study.

CONCLUSIONS

An empirical equation for all age groups is developed. From this equation, particle deposition efficiency in the nasal airway can best be estimated with input data of particle size and pressure drop of the airway.

Depressed calcium-handling proteins due to endoplasmic reticulum stress and apoptosis in the diabetic heart are attenuated by argirein

Diabetic cardiomyopathy (DC) is a unique disease frequently complicated to diabetes mellitus, manifesting endoplasmic reticulum (ER) stress and depressed calcium-handling proteins. We hypothesized that the abnormal FKBP12.6, SERCA2a, and CASQ2 are consequent to ER stress and apoptosis that are likely due to an entity of inflammation. These abnormalities may be attributed to reactive oxygen species genesis from activated NADPH oxidase which could respond to argirein (AR) through its anti-inflammatory activity. Sprague Dawley rats were randomly divided into six groups. Except the normal group, rats were injected with streptozotocin (STZ; 60 mg/kg, i.p.) once. During weeks 5 to 8 following STZ injection, rats were treated (in milligrams per kilogram per day, i.g.) with aminoguanidine (AMG, 100; an inducible nitric oxide synthase and AGEs inhibitor) or three doses of AR (50, 100, and 200). FKBP12.6, SERCA2a, and CASQ2 and ER stress chaperones Bip and PERK and apoptotic molecules were monitored in vivo and in vitro. Impaired cardiac performance and downregulated FKBP12.6, SERCA2a, and CASQ2 were significant in DC in vivo, and abnormal calcium-handling proteins were also found in high-glucose-incubated myocytes in vitro. ER stress manifested by upregulated Bip and PERK was predominant in association with DNA ladder and upregulated Bax and downregulated BCL-2 in vivo and in vitro. AR is effective to attenuate these abnormalities compared to AMG. Diabetic myocardium has inflammatory entity expressed as ER stress contributing to downregulated calcium-handling proteins. AR has potential in managing DC through attenuating depressed calcium-handling proteins, activated ER stress, and apoptosis in the myocardium.

Determination of in vitro lung solubility and intake-to-dose conversion factor for tritiated lanthanum nickel aluminum alloy

A sample of tritiated lanthanum nickel aluminum alloy (LaNi4.25Al0.75 or LANA.75) similar to that used at the Savannah River Site Tritium Facilities was analyzed to estimate the particle size distribution of this metal tritide powder and the rate at which this material dissolves in the human respiratory tract after it is inhaled. This information is used to calculate the committed effective dose received by a worker after inhaling the material. These doses, which were calculated using the same methodology given in the U.S. Department of Energy Tritium Handbook, are presented as inhalation intake-to-dose conversion factors (DCF). The DCF for this metal tritide was determined to be 9.4 × 10 Sv Bq, which is less than the DCF for tritiated water. Therefore, the radiation worker bioassay programs designed for tritiated water are adequate to monitor for intakes of this material.

Novel active personal nanoparticle sampler for the exposure assessment of nanoparticles in workplaces

A novel active personal nanoparticle sampler (PENS), which enables the collection of both respirable particulate mass (RPM) and nanoparticles (NPs) simultaneously, was developed to meet the critical demand for personal sampling of engineered nanomaterials (ENMs) in workplaces. The PENS consists of a respirable cyclone and a micro-orifice impactor with the cutoff aerodynamic diameter (d(pa50)) of 4 μm and 100 nm, respectively. The micro-orifice impactor has a fixed micro-orifice plate (137 nozzles of 55 μm in the inner diameter) and a rotating, silicone oil-coated Teflon filter substrate at 1 rpm to achieve a uniform particle deposition and avoid solid particle bounce. A final filter is used after the impactor to collect the NPs. Calibration results show that the d(pa50) of the respirable cyclone and the micro-orifice impactor are 3.92 ± 0.22 μm and 101.4 ± 0.1 nm, respectively. The d(pa50) at the loaded micro-Al(2)O(3) mass of 0.36-3.18 mg is shifted to 102.9-101.2 nm, respectively, while it is shifted to 98.9-97.8 nm at the loaded nano-TiO(2) mass of 0.92-1.78 mg, respectively. That is, the shift of d(pa50) due to solid particle loading is small if the PENS is not overloaded. Both NPs and RPM concentrations were found to agree well with those of the IOSH respirable cyclone and MOUDI. By using the present PENS, the collected samples can be further analyzed for chemical species concentrations besides gravimetric analysis to determine the actual exposure concentrations of ENMs in both RPM and NPs fractions in workplaces, which are often influenced by the background or incident pollution sources.

Exhaled aerosol transmission of pandemic and seasonal H1N1 influenza viruses in the ferret

Person-to-person transmission of influenza viruses occurs by contact (direct and fomites) and non-contact (droplet and small particle aerosol) routes, but the quantitative dynamics and relative contributions of these routes are incompletely understood. The transmissibility of influenza strains estimated from secondary attack rates in closed human populations is confounded by large variations in population susceptibilities. An experimental method to phenotype strains for transmissibility in an animal model could provide relative efficiencies of transmission. We developed an experimental method to detect exhaled viral aerosol transmission between unanesthetized infected and susceptible ferrets, measured aerosol particle size and number, and quantified the viral genomic RNA in the exhaled aerosol. During brief 3-hour exposures to exhaled viral aerosols in airflow-controlled chambers, three strains of pandemic 2009 H1N1 strains were frequently transmitted to susceptible ferrets. In contrast one seasonal H1N1 strain was not transmitted in spite of higher levels of viral RNA in the exhaled aerosol. Among three pandemic strains, the two strains causing weight loss and illness in the intranasally infected 'donor' ferrets were transmitted less efficiently from the donor than the strain causing no detectable illness, suggesting that the mucosal inflammatory response may attenuate viable exhaled virus. Although exhaled viral RNA remained constant, transmission efficiency diminished from day 1 to day 5 after donor infection. Thus, aerosol transmission between ferrets may be dependent on at least four characteristics of virus-host relationships including the level of exhaled virus, infectious particle size, mucosal inflammation, and viral replication efficiency in susceptible mucosa.

Aerosol-assisted synthesis of monodisperse single-crystalline α-cristobalite nanospheres

Monodisperse single-crystalline α-cristobalite nanospheres have been synthesized by hydrocarbon-pyrolysis-induced carbon deposition on amorphous silica aerosol nanoparticles, devitrification of the coated silica at high temperature, and subsequent carbon removal by oxidation. The nanosphere size can be well controlled by tuning the size of the colloidal silica precursor. Uniform, high-purity nanocrystalline α-cristobalite is important for catalysis, nanocomposites, advanced polishing, and understanding silica nanotoxicology.

Transmission of aerosolized seasonal H1N1 influenza A to ferrets

Influenza virus is a major cause of morbidity and mortality worldwide, yet little quantitative understanding of transmission is available to guide evidence-based public health practice. Recent studies of influenza non-contact transmission between ferrets and guinea pigs have provided insights into the relative transmission efficiencies of pandemic and seasonal strains, but the infecting dose and subsequent contagion has not been quantified for most strains. In order to measure the aerosol infectious dose for 50% (aID₅₀) of seronegative ferrets, seasonal influenza virus was nebulized into an exposure chamber with controlled airflow limiting inhalation to airborne particles less than 5 µm diameter. Airborne virus was collected by liquid impinger and Teflon filters during nebulization of varying doses of aerosolized virus. Since culturable virus was accurately captured on filters only up to 20 minutes, airborne viral RNA collected during 1-hour exposures was quantified by two assays, a high-throughput RT-PCR/mass spectrometry assay detecting 6 genome segments (Ibis T5000™ Biosensor system) and a standard real time RT-qPCR assay. Using the more sensitive T5000 assay, the aID₅₀ for A/New Caledonia/20/99 (H1N1) was approximately 4 infectious virus particles under the exposure conditions used. Although seroconversion and sustained levels of viral RNA in upper airway secretions suggested established mucosal infection, viral cultures were almost always negative. Thus after inhalation, this seasonal H1N1 virus may replicate less efficiently than H3N2 virus after mucosal deposition and exhibit less contagion after aerosol exposure.

Comparison of deposition in the USP and physical mouth-throat models with solid and liquid particles

BACKGROUND

Experimental deposition was studied using three different mouth-throat models: (1) the standard United States Pharmacopeia induction port (IP), (2) the idealized human mouth and throat replica developed by the University of Alberta (UofA replica), and (3) the conductive rubber mouth-throat cast from a human subject developed by Lovelace Respiratory Research Institute (LRRI cast).

METHODS

Both solid and liquid monodispersed fluorescent particles in the size range of 2-30 μm in diameter were delivered into the devices at flow rates of 15, 30, and 60 L min(-1). For solid particles, the study was conducted with and without grease coating inside the devices to investigate the effects of particle bounce.

CONCLUSIONS

Large amounts of rebounded particles were found for the IP and UofA replica without the coating treatment, while particle bounce was only observed at the large particle size for the LRRI cast. The UofA replica and LRRI cast agreed well for solid particles with coating treatments and liquid particles. The deposition results from this study were also compared to data of in vivo deposition studies from the literature. The deposition efficiencies in the UofA replica and LRRI cast were within the range of in vivo data, which showed a large scatter.

Compositional changes in neurotoxins and their oxidative derivatives from the dinoflagellate, Karenia brevis, in seawater and marine aerosol

The harmful alga, Karenia brevis, produces a suite of polyether neurotoxins, brevetoxins or PbTx, that cause marine animal mortality and neurotoxic shellfish poisoning (NSP). A characteristic of K. brevis blooms is associated airborne toxins that result in severe respiratory problems. This study was undertaken to determine the composition of aerosolized brevetoxins and oxidative derivatives to which beachgoers are exposed during a K. brevis bloom. The suite of brevetoxins and derivatives in seawater is comprised of intra-cellular (IC) and extra-cellular (EC) compounds. We hypothesized that aerosolized compounds are generated primarily from EC, hydrophobic compounds in seawater by bubble-mediated transport. Thus the composition of aerosolized brevetoxins and derivatives, to which beachgoers are exposed, would reflect the EC composition of the source matrix (the local surf zone). Brevetoxins were extracted from water collected along the shore and from marine aerosols along Siesta Beach and Lido Beach in Sarasota, FL, USA, during K. brevis blooms. Water samples were further processed into IC and EC components. The primary brevetoxins observed in water and air included PbTx-1, -2, -3, -PbTx-2-carboxylic acid, and brevenal. Oxidation and/or hydrolysis products of PbTx-1, -2, -3 and -7 were also found in EC water and in aerosol, but not IC.

Dissolution rate and biokinetic model of zirconium tritide particles in rat lungs

Metal tritide has been used for different areas such as research, purification, compression, and storage of tritium. Current radiation protection guidelines for tritium compounds describe the behavior of the metal tritide as the same as that of organically bound tritium. However, the biokinetic behavior of metal tritide varies according to materials. This study evaluated the behavior of zirconium tritide (ZrT) particles in rat lungs. The dissolution rate of the ZrT particles in simulated lung fluid was obtained from a specific setup. The ZrT was classified as type-S material according to its low dissolution rate. The ZrT particles were then instilled into rat lungs. The tritium retention time in different rat organs and tritium clearance from rats was obtained by sacrificing a total of 44 rats in a 6 mo period. A biokinetic model for ZrT particles in rat lungs was developed. The predicted retention curves with various phases of tritium in each organ agreed very well with the experimental data. The result can be used to estimate the human annual limit of intake and derived air concentration of ZrT particles.

Inhalation exposure systems for the development of rodent models of sulfur mustard-induced pulmonary injury

Sulfur mustard (SM) is a chemical threat agent for which its effects have no current treatment. Due to the ease of synthesis and dispersal of this material, the need to develop therapeutics is evident. The present manuscript details the techniques used to develop SM laboratory exposure systems for the development of animal models of pulmonary injury. These models are critical for evaluating SM injury and developing therapeutics against that injury. Iterative trials were conducted to optimize a lung injury model. The resulting pathology was used as a guide, with a goal of effecting homogeneous and diffuse lung injury comparable to that of human injury. Inhalation exposures were conducted by either nose-only inhalation or intubated inhalation. The exposures were conducted to either directly vaporized SM or SM that was nebulized from an ethanol solution. Inhalation of SM by nose-only inhalation resulted in severe nasal epithelial degeneration and minimal lung injury. The reactivity of SM did not permit it to transit past the upper airways to promote lower airway injury. Intratracheal inhalation of SM vapors at a concentration of 5400 mg x min/m(3) resulted in homogeneous lung injury with no nasal degeneration.

Evaluation of MR spectroscopy and diffusion-weighted MRI in detecting bone marrow changes in postmenopausal women with osteoporosis

AIM

To prospectively investigate the role of MR spectroscopy (MRS) and diffusion-weighted magnetic resonance imaging (DWI) in assessing vertebral marrow changes in postmenopausal women with osteoporosis.

MATERIALS AND METHODS

Seventy-eight postmenopausal women (mean age 63.7+/-3.5 years; range 55-81 years), who underwent dual-energy x-ray absorptiometry of the spine, were divided into three bone density groups (24 with normal, 25 with osteopaenic, and 29 with osteoporotic) based on T score. Both MRS and DWI of the L3 vertebral body were performed to calculate the marrow fat content and apparent diffusion coefficient (ADC). The results were compared between three groups and correlated with BMD.

RESULTS

Vertebral marrow fat content was significantly increased in the osteoporotic group (59.97+/-5.78%), when compared with that of the osteopaenic group (53.04+/-7.66%, p=0.001) and the normal bone density group (48.79+/-7.1%, p<0.001). ADC values in the osteoporotic, osteopaenic, and normal bone density groups were 0.39+/-0.02x10(-3)mm(2)/s, 0.41+/-0.02x10(-3)mm(2)/s, and 0.47+/-0.03x10(-3)mm(2)/s, respectively, with statistically significant difference (P<0.001). A statistically significant positive correlation between T scores and ADC existed (r=0.835, p<0.001). The vertebral marrow fat content was negatively correlated to the bone density (r=-0.639, p<0.001) and to marrow ADC (r=-0.554, p<0.001).

CONCLUSION

The postmenopausal women with osteoporosis exhibited a corresponding increase in vertebral marrow fat content as the bone density decreased. Marrow fat content and ADC were related to the bone density. MRS and DWI are helpful in evaluating the bone marrow changes in postmenopausal women.

Upregulated NADPH oxidase contributes to diabetic testicular complication and is relieved by strontium fructose 1,6-diphosphate

Diabetes is frequently associated with declining sexual function resulting from oxidative damage. NADPH oxidase is a major resource of reactive oxygen species (ROS) in the testes and is likely related to an activated endothelin-1 (ET-1) system. An activation of NADPH oxidase-ET-1 pathway was hypothesized in diabetic testopathy. We verified the hypothesis and tested if strontium fructose 1,6-diphosphate (FDP-Sr) could relieve these changes in diabetic testis as compared to testosterone propionate (TP) and sildenafil. Diabetes was produced in male Sprague-Dawley rats 8 weeks after a single injection of streptozotocin (STZ), and interventions with testosterone propionate (TP), sildenafil and FDP-Sr were conducted in the last 4 weeks. Blood glucose, testosterone, follicle stimulating hormone (FSH) , luteinizing hormone (LH) and expressions of NADPH oxidase subunits and the ET system were measured. Decreased insulin, FSH, LH and testosterone in serum were found associating with testicular oxidative stress in STZ-injected rats. Additionally, over-expressions of NADPH oxidase p22, p47, p67 subunits and the ET pathway were significant in the diabetic testis relative to normal and were completely abolished by FDP-Sr. Both TP and sildenafil were not beneficial to diabetic testopathy except serum androgen raised by TP. Activated NADPH oxidase and ET system are significant contributing to testis injury and are responded to FDP-Sr only, against both TP and sildenafil, by restoring the testis function and the hypothalamus-pituitary-testis axis. It is due to its extra-energy supply and an antioxidant activity of FDP-Sr.

Evaluation of IOM personal sampler at different flow rates

The Institute of Occupational Medicine (IOM) personal sampler is usually operated at a flow rate of 2.0 L/min, the rate at which it was designed and calibrated, for sampling the inhalable mass fraction of airborne particles in occupational environments. In an environment of low aerosol concentrations only small amounts of material are collected, and that may not be sufficient for analysis. Recently, a new sampling pump with a flow rate up to 15 L/min became available for personal samplers, with the potential of operating at higher flow rates. The flow rate of a Leland Legacy sampling pump, which operates at high flow rates, was evaluated and calibrated, and its maximum flow was found to be 10.6 L/min. IOM samplers were placed on a mannequin, and sampling was conducted in a large aerosol wind tunnel at wind speeds of 0.56 and 2.22 m/s. Monodisperse aerosols of oleic acid tagged with sodium fluorescein in the size range of 2 to 100 microm were used in the test. The IOM samplers were operated at flow rates of 2.0 and 10.6 L/min. Results showed that the IOM samplers mounted in the front of the mannequin had a higher sampling efficiency than those mounted at the side and back, regardless of the wind speed and flow rate. For the wind speed of 0.56 m/s, the direction-averaged (the average value of all orientations facing the wind direction) sampling efficiency of the samplers operated at 2.0 L/min was slightly higher than that of 10.6 L/min. For the wind speed of 2.22 m/s, the sampling efficiencies at both flow rates were similar for particles < 60 microm. The results also show that the IOM's sampling efficiency at these two different flow rates follows the inhalable mass curve for particles in the size range of 2 to 20 microm. The test results indicate that the IOM sampler can be used at higher flow rates.

Influence of moisture accumulation in inline spacer on delivery of aerosol using metered-dose inhaler during mechanical ventilation

BACKGROUND

A practitioner questioned whether moisture that collected in the ventilator circuit and spacer affected the delivery of aerosol from a pressurized metered-dose inhaler (pMDI). An in vitro model was used to quantify the impact of accumulated humidity in a pMDI spacer and ventilator over time.

METHODS

A ventilator with an adult heated-wire ventilator circuit and humidifier was set to deliver adult settings. An impactor was placed between the endotracheal tube and the test lung to determine drug mass and mass median aerodynamic diameter of the aerosol delivered. An AeroVent pMDI spacer was placed in the inspiratory limb of the ventilator circuit and left in an open position. Eight actuations of HFA albuterol pMDI (720 microg) was administered at 1, 2, and 3 hours after the heater had reached equilibrium at 37 degrees C, and <10 min after turning off the heater/humidifier. The spacer was dried and returned to the heated circuit for additional testing. Samples were analyzed via spectrophotometer. One-way analysis of variance was applied (P<.05).

RESULTS

The delivered drug as a percent of emitted dose (mean+/-SD) was greater at hour one (23+/-2.1%) and with the dry spacer (21.8+/-3.3%) than at hours 2 and 3 or with humidifier off (11.4+/-3.8%, 12.3+/-0.8%, and 12.7+/-0.3%, respectively, P=.002). Mass median aerodynamic diameters with each comparison did not vary between conditions. Delivery efficiency was similar for the dry spacer and the spacer in the humidified circuit for one hour. However, once visible condensate occurred, drug delivery efficiency decreased by approximately 50%.

CONCLUSIONS

Aerosol delivery from a pMDI with spacer during mechanical ventilation was greater with a dry spacer and unchanged for the first hour after initiating heated humidification. Turning off the heated humidifier did not increase drug delivered.

Neonatal lipopolysaccharide exposure delays puberty and alters hypothalamic Kiss1 and Kiss1r mRNA expression in the female rat

Immunological challenge experienced in early life can have long-term programming effects on the hypothalamic-pituitary-adrenal axis that permanently influence the stress response. Similarly, neonatal exposure to immunological stress enhances stress-induced suppression of the hypothalamic-pituitary gonadal (HPG) axis in adulthood, but may also affect earlier development, including the timing of puberty. To investigate the timing of the critical window for this programming of the HPG axis, neonatal female rats were injected with lipopolysaccharide (LPS; 50 microg/kg i.p.) or saline on postnatal days 3 + 5, 7 + 9, or 14 + 16 and monitored for vaginal opening and first vaginal oestrus as markers of puberty. We also investigated the effects of neonatal programming on the development of the expression patterns of kisspeptin (Kiss1) and its receptor (Kiss1r) in hypothalamic sites known to contain kisspeptin-expressing neuronal populations critical to reproductive function: the medial preoptic area (mPOA) and the arcuate nucleus in neonatally-stressed animals. We determined that the critical period for a significant delay in puberty as a result of neonatal LPS exposure is before 7 days of age in the female rat, and demonstrated that Kiss1, but not Kiss1r mRNA, expression in the mPOA is down-regulated in pre-pubertal females. These data suggest that the mPOA population of kisspeptin neurones play a pivotal role in controlling the onset of puberty, and that their function can be affected by neonatal stress.

Recreational exposure to microcystins during algal blooms in two California lakes

We conducted a study of recreational exposure to microcystins among 81 children and adults planning recreational activities on either of three California reservoirs, two with significant, ongoing blooms of toxin-producing cyanobacteria, including Microcystis aeruginosa (Bloom Lakes), and one without a toxin-producing algal bloom (Control Lake). We analyzed water samples for algal taxonomy, microcystin concentrations, and potential respiratory viruses (adenoviruses and enteroviruses). We measured microcystins in personal air samples, nasal swabs, and blood samples. We interviewed study participants for demographic and health symptoms information. We found highly variable microcystin concentrations in Bloom Lakes (<10 microg/L to >500 microg/L); microcystin was not detected in the Control Lake. We did not detect adenoviruses or enteroviruses in any of the lakes. Low microcystin concentrations were found in personal air samples (<0.1 ng/m(3) [limit of detection]-2.89 ng/m(3)) and nasal swabs (<0.1 ng [limit of detection]-5 ng). Microcystin concentrations in the water-soluble fraction of all plasma samples were below the limit of detection (1.0 microg/L). Our findings indicate that recreational activities in water bodies that experience toxin-producing cyanobacterial blooms can generate aerosolized cyanotoxins, making inhalation a potential route of exposure. Future studies should include collecting nasal swabs to assess upper respiratory tract deposition of toxin-containing aerosols droplets.

Numerical simulations investigating the regional and overall deposition efficiency of the human nasal cavity

Numerical simulations have been carried out on a model of the right passageway of an anonymous, adult male's nasal cavity, constructed from magnetic resonance imagery (MRI) scans. Steady, laminar, inspiratory flow was assumed to simulate inhalation. Analysis shows smoothly varying streamlines with a peak in velocity magnitude occurring in the nasal valves and a peak in vorticity magnitude immediately posterior. Dilute, uniform concentrations of inertial (1 microm < or = d(ae) < or = 10 microm) particles were released at the nostril and tracked via a Lagrangian tracking algorithm. Deposition efficiency is shown to increase with particle size and flow rate. Preferential deposition is seen in the anterior third of the nasal cavity for large Stokes number particles. An empirical expression for particle deposition is proposed that incorporates particle size, flow rate, and nose anatomy.

Influence of Impactor Operating Flow Rate on Particle Size Distribution of Four Jet Nebulizers

When a nebulizer is evaluated by the Andersen Cascade Impactor (ACI), the flow rate is generally maintained at 28.3 L/min, as recommended by the manufacturer. However, the nebulizer flow rate that a patient inhales is only around 18 L/min. Because the drive flow of a nebulizer is approximately 6-8 L/min, the nebulized drug is mixed with outside air when delivered. Evaluating impactor performance at the 28.3 L/min flow rate is less than ideal because an additional 10 L/min of outside air is mixed with the drug, thereby affecting the drug size distribution and dose before inhalation and deposition in the human lung. In this study we operated the ACI at an 18.0 L/min flow rate to test whether the effect of the changing ambient humidity was being exaggerated by the 28.3 L/min flow rate. The study was carried out at three different relative humidity levels and two different impactor flow rates with four commercially available nebulizers. The mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD) of the droplets were found to increase when the impactor was operated at a flow rate of 18 L/min compared to that of 28.3 L/min. The higher MMAD and GSD could cause the patient to inhale less of the drug than expected if the nebulizer was evaluated by the ACI at the operating flow rate of 28.3 L/min.

Recreational exposure to low concentrations of microcystins during an algal bloom in a small lake

We measured microcystins in blood from people at risk for swallowing water or inhaling spray while swimming, water skiing, jet skiing, or boating during an algal bloom. We monitored water samples from a small lake as a Microcystis aeruginosa bloom developed. We recruited 97 people planning recreational activities in that lake and seven others who volunteered to recreate in a nearby bloom-free lake. We conducted our field study within a week of finding a 10-μg/L microcystin concentration. We analyzed water, air, and human blood samples for water quality, potential human pathogens, algal taxonomy, and microcystin concentrations. We interviewed study participants for demographic and current health symptom information. Water samples were assayed for potential respiratory viruses (adenoviruses and enteroviruses), but none were detected. We did find low concentrations of Escherichia coli, indicating fecal contamination. We found low levels of microcystins (2 μg/L to 5 μg/L) in the water and (<0.1 ng/m³) in the aerosol samples. Blood levels of microcystins for all participants were below the limit of detection (0.147μg/L). Given this low exposure level, study participants reported no symptom increases following recreational exposure to microcystins. This is the first study to report that water-based recreational activities can expose people to very low concentrations of aerosol-borne microcystins; we recently conducted another field study to assess exposures to higher concentrations of these algal toxins.

The influence of spray properties on intranasal deposition

While numerous devices, formulations, and spray characteristics have been shown to influence nasal deposition efficiency, few studies have attempted to identify which of these interacting factors plays the greatest role in nasal spray deposition. The deposition patterns of solutions with a wide range of surface tensions and viscosities were measured using an MRI-derived nasal cavity replica. The resulting spray plumes had angles between 29 degrees and 80 degrees and contained droplet sizes (D(v50)) from 37-157 microm. Each formulation contained rhodamine 590 as a fluorescent marker for detection. Administration angles of 30 degrees , 40 degrees , or 50 degrees above horizontal were tested to investigate the role of user technique on nasal deposition. The amount of spray deposited within specific regions of the nasal cavity was determined by disassembling the replica and measuring the amount of rhodamine retained in each section. Most of the spray droplets were deposited onto the anterior region of the model, but sprays with small plume angles were capable of reaching the turbinate region with deposition efficiencies approaching 90%. Minimal dependence on droplet size, viscosity, or device was observed. Changes in inspiratory flow rate (0-60 L/min) had no significant effect on turbinate deposition efficiency. Both plume angle and administration angle were found to be important factors in determining deposition efficiency. For administration angles of 40 degrees or 50 degrees , maximal turbinate deposition efficiency (30-50%) occurred with plume angles of 55-65 degrees , whereas a 30 degrees administration angle gave an approximately 75% deposition efficiency for similar plume angles. Deposition efficiencies of approximately 90% could be achieved with plume angles <30 degrees using 30 degrees administration angles. Both the plume angle and administration angle are critical factors in determining deposition efficiency, while many other spray parameters, including particle size, have relatively minor influences on deposition within the nasal cavity.

Particle size distribution and inhalation dose of shower water under selected operating conditions

Showering produces respirable droplets that may serve to deposit pollutants such as trihalomethane decontamination products, heavy metals, inorganic salts, microbes, or cyanoacterial toxins within the respiratory tract. The extent and importance of this route of indoor exposure depend on the physical characteristics of the aerosol as well as the pollutant profile of the source water. The purpose of this study was to characterize shower-generated aerosols as a function of water flow rate, temperature, and bathroom location. Aerosols were generated within a shower stall containing a mannequin to simulate the presence of a human. Using hot water, the mass median diameter (MMD) of the droplets inside the shower and in the bathroom were 6.3-7.5 um and 5.2-6 microm, respectively. Size was independent of water flow rate. The particle concentration inside the shower ranged from 5 to 14 mg/m3. Aerosols generated using cold water were smaller (2.5-3.1 microm) and concentrations were lower (0.02-0.1 mg/m3) inside the shower stall. No aerosols were detected in the bathroom area when cold water was used. The International Commission on Radiological Protection model was used to estimate water deposition in the respiratory tract. For hot water, total deposition ranged from 11 to 14 mg, depending on water flow rate, with approximately 50% of this deposited in the extrathoracic region during assumed mouth breathing, and greater than 86% when nose breathing was assumed. Alveolar deposition was 6-10% and 0.9% assuming oral and nasal breathing, respectively. The consequences deposition of shower water droplets will depend on the nature and extent of any pollutants in the source water.

Selection responses in duration of fertility and its consequences on hatchability in the intergeneric crossbreeding of ducks

1. From 1992 to 2003, selected (S) and control lines (C) of the laying Brown Tsaiya duck (Anas platyrhynchos) were simultaneously maintained under the same standardised conditions of feeding and management. 2. The selection objective was to increase the number of fertile eggs after a single artificial insemination (AI) with pooled Muscovy semen. From generations G1 to G11, 2452 and 2022 female ducks, in S and C lines, respectively, were measured and recorded. In the S line, the percentage selected varied between 20.2 and 34.3% in females and between 7.2 and 20.8% in males. 3. Selection for number of fertile eggs had a correlated effect of increasing the parameter tau of the logistic curves which fitted the daily variations (d 2 to 15) in fertility or hatchability on the basis of eggs set. The differences S-C for the estimates of the times of half maximal fertility and hatchability increased by 0.41 and 0.37 d per generation between G1 and G11, respectively. 4. The highest increases of fertility per day rates after a single AI were observed between d 5 and 11. Moreover, in the selected line, fertility rate was higher than, or equal to, 90% in d 2 from G8. The same tendencies were observed for the changes in the evolution of hatchability on the basis of eggs set. 5. Selection increased fertility and hatchability according to the egg set rates, especially for d 2 to 8 after AI. Hatchability of fertile eggs was not impaired, confirming that selection for one AI per week was possible in this strain of laying ducks.

Evaluation of respirator filters for asbestos fibers

Fiber aerosols are known to have different aerodynamic behaviors than spherical particles and usually carry higher electrostatic charges. We investigated the effects of flow rate and charge status of filter cartridges on the penetration of spherical and fiber aerosols. Four types of test respirator filters were selected: two for passive respirators, one for a powered respirator, and one disposable respirator. Surface charges on respirator filters were determined using a noncontact field electrostatic field meter. Penetration tests were performed for filter cartridges before and after charge neutralization. The surface charge measurements on the respirator filters showed that some filters, including those used in disposable face masks, are charged to enhance the collection efficiency. Only high-efficiency particulate air filters performed consistently for both spherical test aerosols and the three types of asbestos fibers. The surface charge potential of filter cartridges and flow rate did not appear to affect the performance of these filters. In contrast to the high-efficiency filters, the aerosol penetration performance of low-efficiency filters and face masks deteriorated when the charge potential on the filter was removed. Our data also showed that the surface charges decreased in a high-temperature, high-humidity environment and disappeared after 1 week. Deposition of spherical particles and fibers in the charged disposable facemask filter was enhanced. For charged-neutralized, low-efficiency filter cartridges, asbestos fibers may penetrate more than spherical particles with a mean particle size of 0.3 microm diameter.

Evaluation of Nebulizer Performance under Various Humidity Conditions

Jet nebulizers are a drug delivery tool commonly used for treating respiratory diseases. When a nebulizer generates aerosols, the rate at which droplets evaporate depends on humidity conditions around the nebulizer outlet. Because the relative humidity (RH) of the air affects the evaporation rate, the aerosol distribution and drug delivery dose is also affected by RH. Four nebulizers were chosen for comparison in this study: PARI LC Plus (PARI Respiratory Equipment, Inc., Midlothian, VA), SideStream (Medic-Aid Ltd., UK), VixOne (Westmed, Inc., Tucson, AZ), and Micromist (Hudson Respiratory Care Inc., Temecula, CA). Two different formulations were used: albuterol (liquid solution) and budesonide (suspension). Particle distribution (mass median aerodynamic diameter [MMAD] and geometric standard deviation [GSD]), nebulizer efficiency (total efficiency and respirable fraction [RF] efficiency for particles less than 4.7 microm), and dead volume (the amount of solution remaining after nebulization) were compared at the RH of 5%, 50%, and 80%. Our results showed that the MMAD increased (p value varied from <0.001 to 0.016) with the increase in RH, except for with the VixOne unit with albuterol (p = 0.24). The MMAD from the budesonide always appeared higher than from the albuterol. The RF (and thus, the inhalation dose) was lower with a higher RH. Except for the PARI LC Plus with budesonide, the RF decreased approximately 15-27% when the RH rose from 5% to 50%. For the PARI LC Plus nebulizer, the lower dead volume (0.22 mL) with higher residual drugs (62.3% of total drug) was obtained at an RH of 5% comparing the RH of 50% and 80% because of the unit's unique design.

Medical nebulizer performance: effects of cascade impactor temperature

BACKGROUND

During operation of a jet nebulizer, the temperature of the nebulizer outlet could decrease by more than 10 degrees C, depending on the nebulizer type and operating conditions, such as driving flow rate and fill volume. The droplet size distribution generated from the nebulizer can be measured by a cascade impactor. However, when the cascade impactor is operated at ambient room temperature, the droplets could evaporate because of the temperature difference between the nebulizer outlet and the body of the impactor.

METHODS

An 8-stage cascade impactor was used to measure the particle size distribution from 4 different types of jet nebulizer (LC Plus, Side-Stream, VixOne, and Micromist) in 2 temperature conditions: ambient (22 degrees C) and low (10 degrees C). Two different formulations, albuterol (aqueous solution) and budesonide (suspension), were used.

RESULTS

There was a significantly larger (p < 0.05) mass median aerodynamic diameter and smaller respirable fraction for each nebulizer with the impactor at low temperature than with the impactor at ambient temperature. The mass median aerodynamic diameter of the nebulizers with the impactor operating at low temperature appeared 15-130% larger than with the impactor operating at ambient temperature, for both formulations. The respirable fraction also changed from 10% when the impactor was operated at low temperature to 65% when the impactor was operated at ambient temperature.

CONCLUSION

The results provide important information for the use of a cascade impactor to measure the particle-size distribution of nebulizer aerosols.

Intraosseous oral leiomyoma: systematic review and report of one case

OBJECTIVES

The objectives of this study were to report one case of intraosseous oral leiomyoma and to systematically review the English literature.

METHODS

The clinical and radiographic findings of a patient who presented with intraosseous oral leiomyoma were recorded. In addition, 11 references from the English literature that reported 12 patients were reviewed.

RESULTS

Thirteen patients (age range 8 months to 71 years; mean 36 years, median 25 years) were reported to present with intraosseous oral leiomyoma. After excluding one patient whose sex was not reported, there were five female patients (42%) and seven males (58%). The majority of patients presented with either no symptoms or with an asymptomatic swelling. Eleven of 13 lesions occurred in the mandible; the most common site was the posterior of the jaw. Radiographically, intraosseous oral leiomyoma was found to present as either a unilocular or multilocular radiolucency with either well defined or ill defined borders and frequent cortical involvement.

CONCLUSIONS

Intraosseous oral leiomyoma was found to occur in the mandibular posterior region of relatively young patients, with cortical involvement and a slight male gender preference. Surgical excision was the treatment of choice and no recurrence has been encountered.

Dosimetry of metal tritide particles as evaluated by the ICRP 66 model and a biokinetic model from laboratory rats

Internal radiation from inhalation of metal tritide aerosols may present a significant radiation protection problem for nuclear facility workers. Dose was evaluated for three metal tritides: hafnium, titanium, and zirconium. The study included in vitro and in vivo exposures. The inhalation doses for the three materials were calculated by using the ICRP 66 lung model. The doses also were evaluated by a biokinetic model, which was developed according to the results of animal studies. Results showed that the hafnium tritide particles were the most dense but they had a lower dissolution rate and a higher retention rate. Among these three tritides, hafnium was classified as a Type S material according to the ICRP 66 publication, whereas titanium and zirconium ranked between Type M and F materials. The dissolution rate of hafnium tritide appeared to agree well with the in vitro and in vivo studies. The dissolution rates of the other two materials in the in vitro studies were a little higher than those of the in vivo studies. The doses calculated by the ICRP 66 model for all materials were approximately two orders smaller than the doses obtained by the animal studies. This bias was caused by the different intake methods of the ICRP 66 model (inhalation) and in the animal study (instillation). The doses were on the same order while correcting for deposition fractions. The effective doses for hafnium, titanium, and zirconium tritides were 5.43 x 10(-10), 9.05 x 10(-11), and 6.5 x 10(-10) Sv Bq(-1), respectively, according to the animal studies.

Effect of inhaled residual oil fly ash on the electrocardiogram of dogs

Epidemiology studies have found associations between increases in air pollutants and increases in morbidity and mortality from cardiovascular disease. The 1995 finding by Godleski et al. at Harvard that inhalation exposures of dogs to high concentrations of residual oil fly ash (ROFA) caused changes in the ST segment and T waves in the electrocardiogram (ECG) suggested a potential mechanism, and also suggested that inhaled metals might contribute to the effect. We conducted the present study to establish a baseline correspondence to the Godleski et al. findings in preparation for studies of the cardiac effects of specific particle-borne metals. The ROFA used in this study consisted of 45% carbon and 15.5% transition metals by mass. In vitro assays using cultured A549 cells and rat alveolar macrophages demonstrated that the ROFA was biologically active but was not highly cytotoxic. Four 10.5-yr-old beagles were exposed by oral inhalation to 3 mg/m3 of aerosolized ROFA for 3 h/day on 3 consecutive days. During the exposures, ECGs were continuously recorded from leads I, II, III, and V4. ECG data were also collected during three control exposures to clean air, during one of which changes were induced using drugs as a positive control. The ROFA exposures caused no consistent changes in the amplitude of the ST segment, the form or amplitude of the T wave, or arrhythmias. The data suggested a slight slowing of heart rate during exposure. Whether the difference between the present and previous findings resulted from differences in the composition of the two batches of ROFA or differences in methodology could not be determined by the study. This study did not address the cardiac effects of ROFA in subjects having preexisting cardiac susceptibility factors, nor was it a rigorous evaluation of effects on the frequency distribution of heart rate. Our results indicate that healthy dogs can inhale high concentrations of ROFA without changes in cardiac electrophysiology, which are detectable by clinical evaluations.

Particle characteristics and lung deposition patterns in a human airway replica of a dry powder formulation of polylactic acid produced using supercritical fluid technology

Polylactic acid (PLA) powders have been used as vector particles to carry pharmaceutical material. Drugs incorporated in the PLA powder can be retained in the lung for a longer period and may be more effective than free-form drugs. A new formulation of L-PLA dry powder, which was easy to disperse in the air, was produced by using a supercritical technology. The L-PLA powder was characterized in terms of physical particle size and aerodynamic size as generated with a Turbuhaler dry powder inhaler (DPI). Electron microscopy analysis of the particles indicated that they were individual particles in bulk form and became aggregate particles after generation by the Turbuhaler. Aerodynamic particle size analysis using both an Aerodynamic Particle Sizer (APS) aerosol spectrometer and Andersen impactor showed that the aerodynamic size decreased as the flow rate in the Turbuhaler increased from 28.3 to 90 L min(-1). Deposition patterns in the human respiratory tract were estimated using a realistic physical replica of human airways. Deposition of the L-PLA was high (80.8%) in the oral airway at 28.3 L min(-1) and an average of 73.4% at flow rates of 60 and 90 L min(-1). In the lung region, the deposition totaled 7.2% at 28.3 L min(-1), 18.3% at 60 L min(-1), and 17.6% at 90 L min(-1). These deposition patterns were consistent with aerodynamic size measurement, which showed 76 to 86% deposition in the USP/EP (US Pharmacopoeia/European Pharmacopoeia) induction port. As the flow rate increased, fewer aggregates were formed resulting in the smaller aerodynamic particles. As a result, more particles penetrated the oral airways and were available for deposition in the lung. Our results showed that L-PLA particles as manufactured by the supercritical technology could be used in a DPI that does not require the use of carrier particles to facilitate aerosol delivery.

Dose assessment for inhaling hafnium particles based on laboratory rats study

Internal radiation from inhalation of hafnium tritide aerosols may be a significant radiation protection problem encountered by nuclear facility workers. Based on experimental results of the rat intratracheally instilled with hafnium tritide particles and on a self-absorption factor of beta particles determined by a numerical method, a biokinetic model was developed for inhaled particles of hafnium tritide. Results show that lung burdens of the tritide are well represented by a two-component exponential equation; biological half-lives derived for the retention of 3H in lung were 4.9 d and 1,257 d for the short- and long-term clearance, respectively. The tritium clearance rate via urine or feces was described by bi-phase exponential components. At the end of the experiment (180 d after instillation), only approximately 30% of the initial lung burden of 3H had been eliminated, of which approximately 98% was excreted via feces and 2% in urine, but none through exhaled air. Results also showed that a large percentage (70%) of the hafnium tritide initially present in lung still remained in the organ 6 mo after the exposure. The calculation of the radiation dose indicates that the cumulative dose to the lung directly from the tritide particles was approximately 10(6) times the lung dose from the dissolved tritium in the lung region. The committed effective dose to the lung was estimated to be 5.41 x 10(-10) Sv Bq(-1), which is over 99% of that to the whole body. The dose to the liver was 6.00 x 10(-15) Sv Bq(-1). This information will be useful in developing new guidelines for radiation protection purposes.