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.