The development of diphenyleneiodonium analogs as GPR3 agonists

G protein-coupled receptor 3 (GPR3) is an orphan receptor potentially involved in many important physiological processes such as drug abuse, neuropathic pain, and anxiety and depression related disorders. Pharmacological studies of GPR3 have been limited due to the restricted number of known agonists and inverse agonists for this constitutively active receptor. In this medicinal chemistry study, we report the discovery of GPR3 agonists based off the diphenyleneiodonium (DPI) scaffold. The most potent full agonist was the 3-trifluoromethoxy analog (32) with an EC50 of 260 nM and 90% efficacy compared to DPI. Investigation of a homology model of GPR3 from multiple sequence alignment resulted in the finding of a binding site rich in potential π-π and π-cation interactions stabilizing DPI-scaffold agonists. MMGBSA free energy analysis showed a good correlation with trends in observed EC50s. DPI analogs retained the same high receptor selectivity for GPR3 over GPR6 and GPR12 as observed with DPI. Collectively, the DPI analog series shows that order of magnitude improvements in potency with the scaffold were attainable; however, attempts to replace the iodonium ion to make the scaffold more druggable failed.

The exploration of aza-quinolines as hematopoietic prostaglandin D synthase (H-PGDS) inhibitors with low brain exposure

GlaxoSmithKline and Astex Pharmaceuticals recently disclosed the discovery of the potent H-PGDS inhibitor GSK2894631A 1a (IC₅₀ = 9.9 nM) as part of a fragment-based drug discovery collaboration with Astex Pharmaceuticals. This molecule exhibited good murine pharmacokinetics, allowing it to be utilized to explore H-PGDS pharmacology in vivo. Yet, with prolonged dosing at higher concentrations, 1a induced CNS toxicity. Looking to attenuate brain penetration in this series, aza-quinolines, were prepared with the intent of increasing polar surface area. Nitrogen substitutions at the 6- and 8-positions of the quinoline were discovered to be tolerated by the enzyme. Subsequent structure activity studies in these aza-quinoline scaffolds led to the identification of 1,8-naphthyridine 1y (IC₅₀ = 9.4 nM) as a potent peripherally restricted H-PGDS inhibitor. Compound 1y is efficacious in four in vivo inflammatory models and exhibits no CNS toxicity.

Updated deterministic radiation transport for future deep space missions

NASA's deterministic transport code HZETRN, and its three-dimensional (3D) counterpart, 3DHZETRN, are being used to characterize the space radiation environment over a wide range of scenarios, including future planned missions to the moon or Mars. Combined with available spaceflight measurements, these tools provide the fundamental input for risk models used to quantify possible astronaut health decrements and satisfy agency limits in support of exploration initiatives. Further research is therefore needed to improve radiation transport and nuclear physics models while at the same time continuing to expand the available measurement database (ground-based and spaceflight) to validate such efforts. In this work, significant updates to the deterministic radiation transport models are presented. Charged muons and pions are fully coupled with the existing solutions developed for neutron and light ion (Z ≤ 2) transport. This update includes the 3D nature of pion production as well as the pion interactions, resulting in further production of energetic nucleons within shielding. Additional updates related to low energy proton recoils in hydrogenous materials and capture/decay processes associated with charged pions at rest are also described. Included in this work is the coupling of single and double-differential cross sections from Geant4 into HZETRN and 3DHZETRN. This enables a direct comparison of deterministic and Monte Carlo transport methodologies using the same nuclear databases for specific interactions. Comparisons between Geant4 and 3DHZETRN are shown and establish that the transport methodologies are in excellent agreement when the same cross sections are used. The deterministic codes are also compared to ISS data, and it is found that the updated 3D procedures are within measurement uncertainty (±5%) at cutoff rigidities below 1 GV, which approaches free space conditions.

Effects of the Serber first step in 3DHZETRN-v2.1

3DHZETRN-v2 includes a detailed three dimensional (3D) treatment of neutron/light-ion transport based on a quasi-elastic/multiple production assumption allowing improved agreement of the neutron/light-ion fluence compared with results of three Monte Carlo (MC) codes in the sense that the variance with respect to the individual MC results is less than the variance among the MC code results. The current numerical methods are no longer the main limitation to HZETRN code development and further changes in the nuclear model are required. In a prior study, an improved quasi-elastic spectrum based on a solution of the transport approximation to nuclear media effects showed promise, but the remaining multiple-production spectrum was based on a database derived from the Ranft model that used Bertini multiplicities. In the present paper, we will implement a more complete Serber first step into the 3DHZETRN-v2 code, but we retain the Bertini-Ranft branching ratios and evaporation multiplicities. It is shown that the new Serber model in the 3HZETRN-v2 code reduces the variance with individual MC codes, which are largely due to nuclear cross section model differences. The code will be available through the software system, OLTARIS, for shield design and validation and provides a basis for personal computer software capable of space shield analysis and optimization.

Berbamine Analogs Exhibit Differential Protective Effects From Aminoglycoside-Induced Hair Cell Death

Hearing loss is the third most common chronic health condition in the United States and largely results from damage to sensory hair cells. Major causes of hair cell damage include aging, noise exposure, and medications such as aminoglycoside antibiotics. Due to their potent antibacterial properties and low cost, aminoglycosides are often used for the treatment of gram-negative bacterial infections, surpassing expensive antibiotics with fewer harmful side effects. However, their use is coupled with permanent hearing loss in over 20% of patients requiring these life-sustaining antibiotics. There are currently no FDA-approved drugs that prevent hearing loss from aminoglycosides. A previous study by our group identified the plant alkaloid berbamine as a strong protectant of zebrafish lateral line hair cells from aminoglycoside damage. This effect is likely due to a block of the mechanotransduction channel, thereby reducing aminoglycoside entry into hair cells. The present study builds on this previous work, investigating 16 synthetic berbamine analogs to determine the core structure underlying their protective mechanisms. We demonstrate that nearly all of these berbamine analogs robustly protect lateral line hair cells from ototoxic damage, with ED₅₀ values nearing 20 nM for the most potent analogs. Of the 16 analogs tested, nine strongly protected hair cells from both neomycin and gentamicin damage, while one conferred strong protection only from gentamicin. These data are consistent with prior research demonstrating that different aminoglycosides activate somewhat distinct mechanisms of damage. Regardless of the mechanism, protection required the entire berbamine scaffold. Phenolic alkylation or acylation with lipophilic groups appeared to improve protection compared to berbamine, implying that these structures may be responsible for mitigating damage. While the majority of analogs confer protection by blocking aminoglycoside uptake, 18% of our analogs also confer protection via an uptake-independent mechanism; these analogs exhibited protection when delivered after aminoglycoside removal. Based on our studies, berbamine analogs represent a promising tool to further understand the pathology of aminoglycoside-induced hearing loss and can serve as lead compounds to develop otoprotective drugs.

Research Note: Delay in sampling influences the profile of phytate in gizzard digesta and ileal digestibility of phosphorus in broilers

The objective of this study was to investigate the effect of different durations of time delay when sampling digesta from the gizzard and ileum of broilers on the degradation of myo-inositol hexakisphosphate (InsP₆) and digestibility of phosphorus (P). There was 1 experimental diet with a supplemental phytase activity of 1,212 phytase units/kg feed, which was provided to birds from day 13 to 18 after hatching. The diet was formulated to provide 6.6 g/kg Ca and 1.9 g/kg nonphytate P and fed to 24 cages of 6 birds. The 24 cages of birds were further randomly divided into 6 subgroups of 4 cages from which the digesta samples in the gizzard and ileum were collected at 0, 5, 10, or 20 min postmortem. The results showed that the concentration of InsP₆ decreased linearly (P = 0.002), InsP₅ decreased quadratically (P = 0.038), and the summation of concentrations of P in InsP_6-4 decreased linearly (P = 0.028) in the gizzard digesta with the increasing delay of sampling. In the ileum, the digestibility of phytate P tended to decrease linearly (P = 0.087), and the digestibility of total P decreased linearly (P = 0.026) with prolonged delay. In conclusion, delay in sampling could alter the measured profile of InsP esters in gizzard digesta probably because of a continued effect of supplemental phytase, while the ileal digestibility of total P could diminish. Therefore, standard sampling procedures should be implemented to minimize variance.

Variation of near surface atmosphere microbial communities at an urban and a suburban site in Philadelphia, PA, USA

Microorganisms are abundant in the near surface atmosphere and make up a significant fraction of organic aerosols with implications on both human health and ecosystem services. Despite their importance, studies investigating biogeographical patterns of the atmospheric microbiome between urban and suburban areas are limited. Urban and suburban locations (including their microbial communities) vary considerably depending on climate, topography, industrial activities, demographics and other socio-economic factors. Hence, we need more location-specific data to make informed decision affecting air quality, human health, and the implication of a changing climate and policy decisions. The objective of this study was to describe how the atmospheric microbiome varies in composition and function between urban and suburban sites. We used high-throughput sequencing to analyze microbial communities collected at different times from PM_2.5 samples collected by active sampling method (using a pump and an impactor) and dust settling of TSP collected by passive sampling method (no pump and no impactor) from an urban and suburban site. We found diverse communities unique in composition at both sites with equivalent functional potential. Taxonomic composition varied significantly with Proteobacteria, Firmicutes, Actinobacteria, Bacteroidetes, and Other phyla in greater relative abundance at the urban site. In contrast, Cyanobacteria, Tenericutes, Fusobacteria, and Deinococcus, were enriched at the suburban site. Community diversity also demonstrated a high degree of temporal variation within site. We identified over one-third of the communities as potentially pathogenic taxa (urban: 47.52% ± 14.40%, suburban: 34.53% ± 14.60%) and determined the majority of organisms come from animal-associated host or are environmental non-specific. Potentially pathogenic taxa and source environments were similar between active- and passive- sampling method results. Our research is novel it adds to the underrepresented set of studies on atmospheric microbial structure and function across land types and is the first to compare suburban and urban atmospheric communities.

The impact of age and feeding length on phytase efficacy during the starter phase of broiler chickens

Phytase is of importance to the poultry industry because of its ability to hydrolyze phytate and release phosphorus (P) for use by poultry. However, the effect of age on phytase efficacy is not fully understood. A total of 864 day-old broiler chicks were used to investigate the effect of age and feeding length on phytase efficacy using growth performance, mineral utilization, and tibia ash as response criteria of evaluation. The experiment was arranged as a 3 × 2 × 2 factorial in a randomized complete block design with 3 diets including; a positive control (PC; 0.4% non-phytate P (nPP)), a negative control (NC; 0.2% nPP) and a NC diet supplemented with phytase at 2,000 FYT/kg; 2 ages (i.e., days 14 and 22); and 2 feeding lengths (i.e., 2 and 5 D) with 8 replicates each. Birds fed the NC had decreased (P < 0.01) body weight gain and feed efficiency compared with birds fed the PC regardless of age or feeding length. Similarly, birds fed the phytase-supplemented diet had improved (P < 0.01) performance as compared to birds fed the NC regardless of age. There were no significant differences in P utilization between birds fed for 2 to 14 D or 22 D and birds fed for 5 D to both ages. However, phytase was more efficacious at day 14 than day 22 when mineral utilization was considered because the super dose of phytase elicited greater response in birds fed the phytase supplemented diet for 2 D until day 14. In contrast, percentage tibia ash improved (P < 0.01) in birds fed phytase supplemented diet for 5 D at both ages as compared with birds fed for 2 D. In conclusion, testing phytase products, even at high doses, for 2 D during the second week in the life cycle of broiler chicks, can be recommended from the results of this study.

Multidrug-resistant tuberculosis care in the United States

BACKGROUND: To examine the utilization of the Tuberculosis (TB) Centers of Excellence (COE) medical consultation service and evaluate how these services were being employed for patients in relation to multidrug-resistant TB (MDR-TB).METHODS: Medical consults are documented in a secure database. The database was queried for MDR-TB consultations over the period 1 January 2013-31 December 2017. All were analyzed to assess provider type, center, setting, year of call, and type of patient (pediatric vs. adult). A subgroup was randomly selected for thematic analysis.RESULTS: The centers received 1560 MDR-TB consultation requests over this period. Providers requesting consults were primarily physicians (55%). The majority of requests were from public health departments (64%) and for adult patients (80%). Four major topic areas emerged: 1) initial management of MDR-TB, 2) MDR-TB longitudinal treatment and complications, 3) management of persons exposed to MDR-TB, and 4) MDR-TB treatment completion.CONCLUSIONS: Analysis of these consultations provides insight into the type of expert advice about MDR-TB that was provided. These findings highlight topics where increased medical training and education may help to improve MDR-TB-related practices.

Influence of age and duration of feeding low-phosphorus diet on phytase efficacy in broiler chickens during the starter phase

A total of 1,408 male broiler chickens were used to evaluate the impact of age and duration of feeding low-phosphorus (P) diet on the efficacy of phytase using growth performance, nutrient utilization, tibia ash, and plasma indices. Diets were formulated with 2 non-phytate P (nPP) concentrations (i.e., 0.20 and 0.40%) and 2 phytase concentrations (i.e., 1,000 and 2,000 FTU/kg) added to the 0.20% nPP diet. Four dietary treatments with 8 replicate cages each were fed to broiler chicks at different ages and for different duration. Specifically, these were days 6 to 8 (12 birds per replicate), 12 to 14, 9 to 14, 20 to 22, or 6 to 22 (8 birds per replicate). Parameters were measured on the last day of each period. Duration of feeding effect was examined by comparing responses of birds fed for 2 or 5 D at day 14 and for 2 or 16 D at day 22; age effect was determined by comparing responses of birds fed for 2 D at age 8, 14 and 22 D post-hatching. Body weight gain and gain-to-feed ratio were increased (P < 0.01) in birds fed diets supplemented with phytase; however, an increase in duration of feeding improved (P < 0.01) feed efficiency with birds fed for 16 D performing better than birds fed for 2 D at day 22. In addition, phytase supplementation improved (P < 0.01) apparent P and calcium digestibility and retention, but the age effect on phytase efficacy was more apparent at day 14 and the duration of feeding effect was evident in birds fed for 2 D due to the increased levels of mineral utilization at that age/duration of feeding as compared with the other groups. The results of this study show that phytase efficacy was at optimum in birds fed low-P diet for 2 D at day 14. This period can be recommended for further bioefficacy studies of phytase.

Development and Testing of in situ Materials for Human Exploration of Mars

Interplanetary space radiation poses a serious health hazard in long-term manned space missions. Natural Martian surface materials are evaluated for their potential use as radiation shields for manned Mars missions. The modified radiation fluences behind various kinds of Martian rocks and regolith are determined by solving the Boltzmann equation using NASA Langley’s HZETRN code along with the 1977 Solar Minimum galactic cosmic ray environmental model. To make structural shielding composite materials from constituents of the Martian atmosphere and from Martian regolith for Martian surface habitats, schemes for synthesizing polyimide from the Martian atmosphere and for processing Martian regolith/polyimide composites are proposed. Theoretical predictions of the shielding properties of these composites are computed to assess their shielding effectiveness. Adding high-performance polymer binders to Martian regolith to enhance the structural properties also enhances the shielding properties of these composites because of the added hydrogenous constituents. Laboratory testing of regolith simulant/polyimide composites is planned in order to validate this prediction and also to measure various structural properties.

Optimizing Ligand Efficiency of Selective Androgen Receptor Modulators (SARMs)

A series of selective androgen receptor modulators (SARMs) containing the 1-(trifluoromethyl)benzyl alcohol core have been optimized for androgen receptor (AR) potency and drug-like properties. We have taken advantage of the lipophilic ligand efficiency (LLE) parameter as a guide to interpret the effect of structural changes on AR activity. Over the course of optimization efforts the LLE increased over 3 log units leading to a SARM 43 with nanomolar potency, good aqueous kinetic solubility (>700 μM), and high oral bioavailability in rats (83%).

Voriconazole exposure and the risk of cutaneous squamous cell carcinoma in allogeneic hematopoietic stem cell transplant patients

BACKGROUND

Voriconazole is a commonly used antifungal medication in allogeneic hematopoietic stem cell transplantation (allo-HSCT) patients. In solid organ transplantation, voriconazole use has been associated with the development of cutaneous squamous cell carcinoma (SCC). We sought to determine if voriconazole use was associated with SCC in patients undergoing allo-HSCT.

METHODS

We retrospectively reviewed consecutive adult patients who underwent allo-HSCT at Mayo Clinic from January 2007 through July 2012. Multivariable Cox models were created to assess the relationship of SCC with two time-dependent voriconazole exposure variables: (i) history of voriconazole exposure (yes/no), and (ii) cumulative days of voriconazole use.

RESULTS

In our cohort of 381 allo-HSCT patients, SCC developed in 26 of 312 patients exposed to voriconazole (25 post-voriconazole) and in 1 of 69 patients who received alternative antifungal agent(s). Cumulative incidence of SCC was estimated to be 19% at 5 years post allo-transplant. Cumulative days of voriconazole use was found to be a risk factor for SCC, and this relationship persisted in a multivariable model using previously identified risk factors as covariates (hazard ratio 1.859 for each 180 days of use, P < 0.001).

CONCLUSION

This is the first study, to our knowledge, to identify cumulative days of voriconazole use as a risk factor for SCC development following allo-HSCT, and may help guide appropriate antifungal use in this patient population.

Oral ribavirin therapy for respiratory syncytial virus infections in moderately to severely immunocompromised patients

BACKGROUND

Respiratory syncytial virus (RSV) infections may be fatal in immunocompromised patients. Aerosolized ribavirin is used for treatment, but it is very costly, teratogenic, and inconvenient. We aimed to assess the outcome of oral ribavirin treatment, with or without intravenous immunoglobulin (IVIG), for RSV infections in moderately to severely immunocompromised patients.

METHODS

Medical records of RSV polymerase chain reaction (PCR)-positive patients during 2011-2013 were reviewed retrospectively. Eligible patients were moderately to severely immunocompromised and received oral ribavirin (600-800 mg twice daily) with or without IVIG (500 mg/kg q 48 h) as per protocol.

RESULTS

Of 96 adults with PCR-proven RSV infection, 34 were moderately to severely immunocompromised and received oral ribavirin treatment. The mean age was 56.2 years (range: 18-90); 21 were male. Underlying conditions were hematologic malignancy with or without hematopoietic stem cell transplant (n = 25), lung transplant (n = 3), or receipt of cytotoxic chemotherapy (n = 11). The presenting symptoms were cough (94%), fever (62%), and dyspnea (59%). The most common radiographic findings were patchy and nodular infiltrates and opacities. Of 34 patients, 31 were hospitalized, with 13 admitted to the intensive care unit and 6 required mechanical ventilation. The median absolute lymphocyte count on presentation was 480 cells/mm(3) . RSV pneumonia developed in 24 patients. The median initial duration of oral ribavirin treatment was 10 days (range: 4-11); 4 patients were re-treated. Of 34 patients, 19 received a mean of 2.7 doses of IVIG. Two patients had adverse reactions to ribavirin (hemolytic anemia and lactic acidosis in 1 patient, and altered mental status in another). No patient died from RSV infection. Three patients died from complications of their underlying illness; all others recovered clinically.

CONCLUSIONS

Oral ribavirin with or without IVIG is a well-tolerated treatment for RSV infection in moderately to severely immunocompromised hosts. Comparative prospective studies should ideally be performed to determine if oral ribavirin is the optimal therapy for RSV infection in this patient population.

The effects of forage particle length and exogenous phytase inclusion on phosphorus digestion and absorption in lactating cows

Accurate estimates of phosphorus (P) availability from feed are needed to allow P requirements to be met with reduced P intake, thus reducing P excretion by livestock. Exogenous phytase supplementation in poultry and swine diets improves bioavailability of P, and limited research suggests that this strategy may have some application in dairy cattle rations. The effects of exogenous phytase and forage particle length on site and extent of P digestion were evaluated with 5 ruminally and ileally cannulated lactating cows (188 ± 35 d in milk). Cows were assigned in a 2 × 2 factorial arrangement of treatments in 2 incomplete Latin squares with four 21-d periods. Diets contained P slightly in excess of National Research Council requirements with all P from feed sources. During the last 4d of each period, total mixed ration, refusals, omasal, ileal, and fecal samples were collected and analyzed for total P, inorganic P (Pi), and phytate (Pp). Total P intake was not influenced by dietary treatments but Pp intake decreased and Pi intake increased with supplemental phytase, suggesting rapid action of the enzyme in the total mixed ration after mixing. Omasal flow of Pi decreased with phytase supplementation, but we observed no effect of diet in ileal flow or small intestinal digestibility of any P fraction. Fecal excretion of total P was slightly higher and Pp excretion was lower for cows receiving diets supplemented with phytase. Milk yield and composition were unaffected by diets. When phytase was added to the mixed ration, dietary Pp was rapidly degraded before intake and total-tract Pp digestion was increased. The lack of effect of phytase supplementation on dietary P utilization was probably because these late-lactation cows had a low P requirement and were fed P-adequate diets.

Effects of dietary supplementation with a protease on the apparent ileal digestibility of the weaned piglet

The effects of an acid-stable protease (RONOZYME ProAct) supplemented to a corn (Zea mays)-soybean (Glycine max) meal-based diet on apparent ileal digestibility (AID) of nutrients were evaluated in 120 weaned piglets (28 d old; 8.17 ± 0.90 kg). Pigs were divided into 2 equal groups and had free access to mash diet containing 0.4% Cr(2)O(3) as indigestible marker [basal diet (Std)] or this diet supplemented with RONOZYME ProAct at 15,000 PROT [the amount of enzyme that releases 1 μmol of pnitroaniline from 1 μM of substrate (Suc-Ala-Ala-Pro-Phe-p-nitroaniline) per min at pH 9.0 and 37°C)/kg (ProA). The ileal content was collected for the digestibility determination after euthanasia of 35 piglets of each group after 14 d of study and 25 piglets of each group after 29 d. Compared to group Std, AID of CP was increased (P < 0.05) after 29 d of treatment in group ProA. The AID of the indispensable AA, Met + Cys, and branched-chain AA was increased (P < 0.05) at the end of the study. In the protease supplemented pigs, the AID of the individual AA was not improved after 14 d of treatment whereas it was increased (P < 0.05) at the end of the experiment for Arg, Asp + Asn, Glu + Gln, His, Ile, Lys, Phe, Thr, Tyr ,and Val. In conclusion, dietary protease supplementation increased AID of AA in piglets.

Characterization of restricted diffusion in uni- and multi-lamellar vesicles using short distance iMQCs

Improved understanding of the entrapment, transport, and release of drugs and small molecules within vesicles is important for drug delivery. Most methods rely on contrast agents or probe molecules; here, we propose a new MRI method to detect signal from water spins with restricted diffusion. This method is based on intermolecular double quantum coherences (iDQCs), which can probe the restricted diffusion characteristics at well-defined and tunable microscopic distance scales. By using an exceedingly short (and previously inaccessible) distance, the iDQC signal arises only from restricted diffusion spins and thereby provides a mechanism to directly image vesicle entrapment, transport, and release. Using uni- and multi-lamellar liposomes and polymersomes, we show how the composition, lamellar structure, vesicle size, and concentration affects the iDQC signal between coupled water spins at very short separation distances. The iDQC signal correlates well with conventional diffusion MRI and a proposed biexponential (multicompartmental) diffusion model. Finally, the iDQC signal was used to monitor dynamic changes in the lamellar structure as temperature-sensitive liposomes released their contents. These short distance iDQCs can probe the amount and diffusion of water entrapped in vesicles, which may be useful to further understand vesicle properties in materials science and drug delivery applications.

Infectious complications among individuals with clinical monoclonal B-cell lymphocytosis (MBL): a cohort study of newly diagnosed cases compared to controls

Although the risk of progression from monoclonal B-cell lymphocytosis (MBL) to chronic lymphocytic leukemia (CLL) has been well characterized, it is unknown whether other common complications associated with CLL, such as increased risk of infection, occurs in individuals with MBL. We used the Mayo CLL database to identify cohorts of individuals with newly diagnosed MBL (n=154) or newly diagnosed CLL (n=174) who resided within 50 miles of Mayo Clinic. A cohort of 689 adult patients seen for a general medical examination who resided within 50 miles of Mayo clinic and who enrolled in a case-control study of non-Hodgkin lymphoma (NHL) was used as a comparison cohort. Hospitalization with infection was more common among individuals with MBL (25/154; 16.2%), and CLL (32/174; 18.4%) than controls (18/689; 2.6%). On pooled multivariable Cox proportional hazards analysis of all 1017 patients (controls, MBL and CLL), male sex (hazards ratio (HR)=2.3; P=0.002), major co-morbid health problems (HR=1.7, P=0.04), the presence of CLL (HR=3.2, P<0.001), treatment for progressive CLL (HR=2.4, P=0.001) and the presence of MBL (HR=3.0, P=0.001) were independently associated with risk of hospitalization for infection. These results suggest the risk of serious infection in clinical MBL is substantially greater than the risk of progression requiring treatment.

THE SELECTIVE ABSORPTION OF POTASSIUM BY ANIMAL CELLS : II. THE CAUSE OF POTASSIUM SELECTION AS INDICATED BY THE ABSORPTION OF RUBIDIUM AND CESIUM

1. Frog muscles perfused with Ringer solution in which potassium chloride has been replaced by an equivalent amount of rubidium or cesium chloride take up rubidium or cesium and incorporate them into the tissue substance in such form as to be retained during a subsequent perfusion with potassium-free Ringer solution, provided the muscles contract during the first perfusion. Retention of rubidium or cesium by a resting muscle does not occur. 2. Rats on synthetic diets, adequate in all respects except that potassium was replaced by an equivalent amount of rubidium or cesium, died after a period varying from 10 to 17 days with characteristic symptoms including tetanic spasms. Muscle, heart, liver, kidney, spleen, and lung tissues were then found to contain significant amounts of rubidium or cesium. The concentration of these metals in the muscle amounted, in some cases, as shown by a spectroscopic estimation, to about half the concentration of potassium normally found in mammallian muscle. 3. The results are regarded as tending to confirm the theory that the peculiarities in the physiological effects of potassium, including the facility with which it is "selected" by living cells in preference to sodium, are related to the electronic structure of the potassium ion as compared with that of similar ions. The possible relationship of the comparative migration velocity, a function of the electronic structure, to physiological effects is suggested.

THE SELECTIVE ABSORPTION OF POTASSIUM BY ANIMAL CELLS : I. CONDITIONS CONTROLLING ABSORPTION AND RETENTION OF POTASSIUM

1. Individual variations in the potassium content of the fresh muscles of frogs are notable even when computed as percentages of the dry solids. The potassium content averaged higher in freshly collected summer frogs than in winter frogs after a period of captivity. 2. Muscles show a loss of from 8 to 15 per cent of their potassium during perfusion with potassium-free Ringer solution but tenaciously hold the remainder. 3. Muscles, stimulated to contract under conditions that do not produce irreversible stages of fatigue, show losses of potassium no greater than those attributable to the presence of a potassium-free medium. 4. A condition favorable to the taking up of potassium probably occurs in a contracting muscle because rubidium and cesium, substances very similar to potassium in chemical and physiological behavior, are absorbed in retainable form by a contracting muscle but not by a resting one.

Tachycardia in adults with cystic fibrosis is associated with normal autonomic function

BACKGROUND

Whether autonomic dysfunction contributes to tachycardia in cystic fibrosis (CF) is unknown.

METHODS

Heart rate variability (HRV) was assessed to determine high frequency power and the low/high frequency power ratio (HF, LF/HF) as markers of vagal and sympathovagal balance, respectively, under spontaneous and controlled breathing (15 breaths per minute (bpm)) conditions in 17 CF and 17 healthy control subjects.

RESULTS

Under spontaneously breathing conditions, the CF group was tachycardic (75.4 ± 11.2 vs 60.2 ± 9.0 br/min P < 0.001) and tachypnoeic (22.6 ± 5.8 vs 13.6 ± 4.1 br/min, P= 0.001) compared with controls. No significant difference in HRV was observed between groups during spontaneous or controlled breathing. Coexistent diabetes mellitus and β(2) agonist use were not associated with altered autonomic control. During controlled breathing, the CF group showed a negative correlation between forced expiratory volume in 1 s (FEV(1)) % predicted and HF power (P= 0.013, r=-0.59) and a positive correlation between FEV(1) % predicted and LF/HF ratio (P= 0.002, r= 0.69) suggesting an exaggerated normal vagal response.

CONCLUSION

CF patients have normal autonomic function.

Optimization of a series of 4,6-bis-anilino-1H-pyrrolo[2,3-d]pyrimidine inhibitors of IGF-1R: elimination of an acid-mediated decomposition pathway

Initial evaluation of a series 4,6-bis-anilino-1H-pyrrolo[2,3-d]pyrimidines revealed a C(1') carboxamide was preferred for sub-micromolar in vitro potency against IGF-1R. Subsequent solution stability studies with 1 revealed a susceptibility toward acid-induced intramolecular cyclization with the C(1') carboxamide. Herein, we describe several successful approaches toward generating both potent and acid-stable inhibitors of IGF-1R within the 4,6-bis-anilino-1H-pyrrolo[2,3-d]pyrimidine template.

Optimization of 4,6-bis-anilino-1H-pyrrolo[2,3-d]pyrimidine IGF-1R tyrosine kinase inhibitors towards JNK selectivity

The SAR of C5' functional groups with terminal basic amines at the C6 aniline of 4,6-bis-anilino-1H-pyrrolo[2,3-d]pyrimidines is reported. Examples demonstrate potent inhibition of IGF-1R with 1000-fold selectivity over JNK1 and 3 in enzymatic assays.

Challenges in pulmonary fibrosis: 7--Novel therapies and lung transplantation

The spectrum of diseases collectively known as pulmonary fibrosis does not have reliable therapeutic options. Many treatment protocols have been the subject of clinical trials, resulting in few significant improvements in outcome. Recently, cellular mechanisms have been the focus of investigations in progenitor cell studies, suggesting an immunomodulatory role for mesenchymal stem cells. The possible role of fibrogenic cytokines and the use of antagonist molecules are promising for future therapies. A range of anti-inflammatory treatments, including macrolide antibiotics, may also hold promise. When medical therapy has been unsuccessful in altering the course of the disease, lung transplantation may offer a significant survival advantage. Improvement in pre-transplant assessment and postoperative care, combined with more effective immunosuppressive regimes, has seen survival rates of 40% after 5 years. New options for therapy will lead to improved survival in coming years.

Randomised placebo controlled trial of non-invasive ventilation for hypercapnia in cystic fibrosis

BACKGROUND

The clinical benefits of domiciliary non-invasive positive pressure ventilation (NIV) have not been established in cystic fibrosis (CF). We studied the effects of nocturnal NIV on quality of life (QoL), functional and physiological outcomes in CF subjects with awake hypercapnia (arterial carbon dioxide pressure PaCO2>45 mm Hg).

METHODS

In a randomised, placebo controlled, crossover study, eight subjects with CF, mean (SD) age 37 (8) years, body mass index 21.1 (2.6) kg/m2, forced expiratory volume in 1 s 35 (8)% predicted and PaCO2 52 (4) mm Hg received 6 weeks of nocturnal (1) air (placebo), (2) oxygen and (3) NIV. The primary outcome measures were CF specific QoL, daytime sleepiness and exertional dyspnoea. Secondary outcome measures were awake and asleep gas exchange, sleep architecture, lung function and peak exercise capacity.

RESULTS

Compared with air, NIV improved the chest symptom score in the CF QoL Questionnaire (mean difference 10; 95% CI 5 to 16; p = 0.002) and the transitional dyspnoea index score (mean difference 3.1; 95% CI 1.2-5.0; p = 0.01). It reduced maximum nocturnal pressure of transcutaneous CO2 (PtcCO2 mean difference -17 mm Hg; 95% CI -7 to -28 mm Hg; p = 0.005) and increased exercise performance on the Modified Shuttle Test (mean difference 83 m; 95% CI 21 to 144 m; p = 0.02). NIV did not improve sleep architecture, lung function or awake PaCO2.

CONCLUSION

6 weeks of nocturnal NIV improves chest symptoms, exertional dyspnoea, nocturnal hypoventilation and peak exercise capacity in adult patients with stable CF with awake hypercapnia. Further studies are required to determine whether or not NIV can improve survival.

Does expiratory flow limitation predict chronic dyspnoea in adults with cystic fibrosis?

Tidal expiratory flow limitation (EFL) may promote dynamic hyperinflation and contribute to chronic dyspnoea. The purpose of this study was to assess the contribution of EFL to chronic dyspnoea in adults with cystic fibrosis (CF). The presence of EFL was determined in 102 adults with stable CF (forced expiratory volume in one second (FEV1) 17.3-91.5% predicted) and 20 age-matched control subjects using the negative expiratory pressure technique. Measurements of inspiratory capacity (IC) and spirometry were performed, and chronic dyspnoea was evaluated using the modified Medical Research Council scale. EFL was present in 34 subjects (33%), with 18 subjects flow limited in the sitting position and 16 subjects flow limited only in the supine position. Flow limitation in the sitting position was associated with older age and lower FEV1 compared with flow-limited supine position and non-flow-limited subjects. A significant reduction in IC accompanied EFL in both the sitting and supine positions. Flow limitation in the sitting position was associated with significantly higher levels of chronic dyspnoea. Ordinal regression analysis indicated that EFL was the best predictor of chronic dyspnoea in a model that included FEV1 % pred. Expiratory flow limitation in cystic fibrosis is associated with reduced forced expiratory volume in one second, older age and dynamic hyperinflation. Expiratory flow limitation significantly contributes to chronic dyspnoea in cystic fibrosis.

Staphylococcus capitis endocarditis due to a transvenous endocardial pacemaker infection: case report and review of Staphylococcus capitis endocarditis

OBJECTIVES

Newer microbiologic methods to determine the species of coagulase-negative staphylococci (CoNS) have evolved which have shown that most endocarditis due to CoNS is caused by Staphylococcus epidermidis, and far fewer by Staphylococcus warneri and Staphylococcus lugdunensis.

METHODS

The recent opportunity to successfully treat a patient with methicillin-resistant Staphylococcus capitis endocarditis secondary to an infected transvenous pacemaker led to a review of the literature relating to S. capitis endocarditis.

RESULTS

Thirteen previously recorded patients were identified. Twelve (86%) patients were male. Ten had endocarditis associated with a native valve, two with prosthetic valves and one with a transvenous pacemaker. Mortality was low in all 14 cases (including this case report) with only two deaths; one in a patient with a native valve and the other with a prosthetic valve. Four of the isolates were methicillin resistant but sensitive to vancomycin, which was used in the treatment of eight patients. Those patients with prosthetic cardiac devices appear to do better when the devices are surgically removed.

CONCLUSIONS

CoNS as a cause of endocarditis appears to be increasing and the current ability to determine the species of these organisms should elicit the epidemiology, clinical characteristics and biomolecular mechanisms involved in the induction of valvular disease.

The prevalence of benign breast disease in women with polycystic ovary syndrome: a review of a 12-year follow-up

A cross-sectional study of benign breast disease (BBD) was conducted to determine the actual prevalence and follow-up importance of BBD among women with polycystic ovary syndrome (PCOS) in conjunction with an ongoing prospective cohort study. The present study involved a subset of the original group of 244 women with a diagnosis of PCOS and 244 control women matched by age and race. A total of 240 women (116 cases and 124 controls) were included in the present analysis. The majority of women in each group were Caucasians (93 and 96%, respectively). The median age was 46 years in the cases and 47 years in the controls. Screening mammography begins at the age of 40 and has been carried out in 69% of cases and 66% of controls since the study began. Family history of breast disease was observed in 27 cases of both the groups (p > 0.05). Neither fibrocystic breast disease, lump thickening, calcification, fibroadenoma, pain, redness, discharge nor hyperplasia showed a significantly higher prevalence rate in cases than in controls. Eleven (9%) women with PCOS and 21 (17%) controls underwent diagnostic or curative surgery (relative risk: 0.56). These results, in contrast to the previously published literature, do not allow us to conclude that there is a higher risk for BBD among women with PCOS, and the proportion of women with a positive family history of breast cancer was significantly greater in women with PCOS compared with controls. Our observation is that having PCOS does not appear to affect surgeons' decisions to remove BBD.

Validation of the HZETRN code for laboratory exposures with 1A GeV iron ions in several targets

A new version of the HZETRN code capable of validation with HZE ions in either the laboratory or the space environment is under development. The computational model consists of the lowest order asymptotic approximation followed by a Neumann series expansion with non-perturbative corrections. The physical description includes energy loss with straggling, nuclear attenuation, nuclear fragmentation with energy dispersion and downshift. Measurements to test the model were performed at the Alternating Gradient Synchrotron and the NASA Space Radiation Laboratory at Brookhaven National Laboratory with iron ions. Surviving beam particles and produced fragments were measured with solid-state detectors. Beam analysis software has been written to relate the computational results to the measured energy loss spectra of the incident ions for rapid validation of modeled target transmission functions.

Computational methods for the HZETRN code

Asymptotic expansion has been used to simplify the transport of high charge and energy ions for broad beam applications in the laboratory and space. The solution of the lowest order asymptotic term is then related to a Green's function for energy loss and straggling coupled to nuclear attenuation providing the lowest order term in a rapidly converging Neumann series for which higher order collisions terms are related to the fragmentation events including energy dispersion and downshift. The first and second Neumann corrections were evaluated numerically as a standard for further analytic approximation. The first Neumann correction is accurately evaluated over the saddle point whose width is determined by the energy dispersion and located at the downshifted ion collision energy. Introduction of the first Neumann correction leads to significant simplification of the second correction term allowing application of the mean value theorem and a second saddle point approximation. The regular dependence of the second correction spectral dependence lends hope to simple approximation to higher corrections. At sufficiently high energy nuclear cross-section variations are small allowing non-perturbative methods to all orders and renormalization of the second corrections allow accurate evaluation of the full Neumann series.

Reduced bone density in cystic fibrosis: F508 mutation is an independent risk factor

The aim of this cross-sectional study was to determine the prevalence and identify determinants of reduced bone mineral density (BMD) in adults with cystic fibrosis (CF). Adults (88) with CF (mean+/-SD age 29.9+/-7.7 yrs; forced expiratory volume in one second (FEV1) 58.2+/-21.5% of the predicted value) were studied. BMD at the lumbar spine (LS) and femoral neck (FN) and body composition were measured using dual-energy X-ray absorptiometry. Blood and urine were analysed for hormones, bone turnover markers, and the cytokines tumour necrosis factor-alpha, and interleukin-6 and -1beta. FEV1 (% pred); CF genotype; malnutrition; history of growth, development or weight gain delays; and corticosteroid use were analysed. BMD Z-scores were -0.58+/-1.30 (mean+/-SD) at the LS and -0.24+/-1.19 at the FN. Z-scores of <-2.0 were found in 17% of subjects. Subjects who were homozygous or heterozygous for the DeltaF508 mutation exhibited significantly lower Z-scores than those with no DeltaF508 allele. Multiple linear regression showed that the DeltaF508 genotype and male sex were independently associated with lower BMD at both sites. Other factors also independently associated with lower BMD included malnutrition, lower 25-hydroxyvitamin D level, lower fat-free mass and lower FEV1 (% pred). In conclusion, reduced bone mineral density in cystic fibrosis is associated with a number of factors, including DeltaF508 genotype, male sex, greater lung disease severity and malnutrition.

The impact of pharmacogenomic factors on steroid dependency in pediatric heart transplant patients using logistic regression analysis

Many pharmacogenomic predictors of drug response are now available, and include both drug metabolism-disposition factors and drug targets. Information on statistical approaches to analyzing large clinical data sets in relation to genetic polymorphisms is limited. The objective of this study was to evaluate whether logistic regression could identify pharmacogenomic predictors of outcome in a large data set in a complex transplant patient population. Seventy pediatric heart transplant patients were studied. Patients were followed for at least 1 yr post-transplantation as outpatients, and weaned from corticosteroids if clinically appropriate. Logistic regression analysis was used to identify the predictors of steroid dependency. The dependent variable was the presence or absence of steroid therapy at 1 yr post-transplantation. The independent variables were the patients' transplant age, gender, MDR1 C3435T and G2677T, CYP3A53B and cytokine polymorphisms. By chi-square test for the MDR1 C3435T polymorphism, 12 of 18 (67%) patients in the CC group were still on prednisone, whereas only 18 of 47 (38%) of the CT/TT group were still receiving prednisone (p = 0.04). For the IL-10 groups, two of 15 patients with the high producer genotype (13.3%) remained on prednisone, in comparison with 16 of 28 patients with the intermediate producer genotype (57.1%) and 15 of 26 patients with the low producer genotype (57.7%, p = 0.01). Logistic regression analysis confirmed MDR1 C3435T (p = 0.021), and IL-10 polymorphisms (intermediate producer genotype p = 0.015; low producer genotype p = 0.013) as independent risk factors for steroid dependency at 1 yr after transplantation. This approach identifies pharmacogenomic factors, which can be studied more extensively in larger data sets, and used in prospective studies to individualize immunosuppressive therapy following solid organ transplantation.

Optimal testing parameters for blood cultures

The effects of volume of blood, number of consecutive cultures, and incubation time on pathogen recovery were evaluated for 37,568 blood cultures tested with the automated BACTEC 9240 instrument (Becton Dickinson Diagnostic Instrument Systems) at a tertiary care center over the period of 12 June 1996 through 12 October 1997. When the results for this study were compared with previous data published for manual broth-based blood culture systems and patient samples obtained in the 1970s and 1980s, the following were found: (1) the percentage increase in pathogen recovery per milliliter of blood is less, (2) more consecutive blood culture sets over a 24-h period are required to detect bloodstream pathogens, and (3) a shorter duration of incubation is required to diagnose bloodstream infections. Guidelines developed in the 1970s and 1980s for processing and culturing blood may require revision.

Deep space environments for human exploration

Mission scenarios outside the Earth's protective magnetic shield are being studied. Included are high usage assets in the near-Earth environment for casual trips, for research, and for commercial/operational platforms, in which career exposures will be multi-mission determined over the astronaut's lifetime. The operational platforms will serve as launching points for deep space exploration missions, characterized by a single long-duration mission during the astronaut's career. The exploration beyond these operational platforms will include missions to planets, asteroids, and planetary satellites. The interplanetary environment is evaluated using convective diffusion theory. Local environments for each celestial body are modeled by using results from the most recent targeted spacecraft, and integrated into the design environments. Design scenarios are then evaluated for these missions. The underlying assumptions in arriving at the model environments and their impact on mission exposures within various shield materials will be discussed.

Uncertainties in estimates of the risks of late effects from space radiation

Methods used to project risks in low-Earth orbit are of questionable merit for exploration missions because of the limited radiobiology data and knowledge of galactic cosmic ray (GCR) heavy ions, which causes estimates of the risk of late effects to be highly uncertain. Risk projections involve a product of many biological and physical factors, each of which has a differential range of uncertainty due to lack of data and knowledge. Using the linear-additivity model for radiation risks, we use Monte-Carlo sampling from subjective uncertainty distributions in each factor to obtain an estimate of the overall uncertainty in risk projections. The resulting methodology is applied to several human space exploration mission scenarios including a deep space outpost and Mars missions of duration of 360, 660, and 1000 days. The major results are the quantification of the uncertainties in current risk estimates, the identification of factors that dominate risk projection uncertainties, and the development of a method to quantify candidate approaches to reduce uncertainties or mitigate risks. The large uncertainties in GCR risk projections lead to probability distributions of risk that mask any potential risk reduction using the "optimization" of shielding materials or configurations. In contrast, the design of shielding optimization approaches for solar particle events and trapped protons can be made at this time and promising technologies can be shown to have merit using our approach. The methods used also make it possible to express risk management objectives in terms of quantitative metrics, e.g., the number of days in space without exceeding a given risk level within well-defined confidence limits.

A space radiation transport method development

Improved spacecraft shield design requires early entry of radiation constraints into the design process to maximize performance and minimize costs. As a result, we have been investigating high-speed computational procedures to allow shield analysis from the preliminary design concepts to the final design. In particular, we will discuss the progress towards a full three-dimensional and computationally efficient deterministic code for which the current HZETRN evaluates the lowest-order asymptotic term. HZETRN is the first deterministic solution to the Boltzmann equation allowing field mapping within the International Space Station (ISS) in tens of minutes using standard finite element method (FEM) geometry common to engineering design practice enabling development of integrated multidisciplinary design optimization methods. A single ray trace in ISS FEM geometry requires 14 ms and severely limits application of Monte Carlo methods to such engineering models. A potential means of improving the Monte Carlo efficiency in coupling to spacecraft geometry is given in terms of re-configurable computing and could be utilized in the final design as verification of the deterministic method optimized design.

A new Mars radiation environment model with visualization

A new model for the radiation environment to be found on the planet Mars due to Galactic Cosmic Rays (OCR) has been developed at the NASA Langley Research Center. Solar modulated primary particles rescaled for Mars conditions are transported through the Martian atmosphere, with temporal properties modeled with variable timescales, down to the surface, with altitude and backscattering patterns taken into account. The Martian atmosphere has been modeled by using the Mars Global Reference Atmospheric Model--version 2001 (Mars-GRAM 2001). The altitude to compute the atmospheric thickness profile has been determined by using a model for the topography based on the data provided by the Mars Orbiter Laser Altimeter (MOLA) instrument on board the Mars Global Surveyor (MGS) spacecraft. The Mars surface composition has been modeled based on averages over the measurements obtained from orbiting spacecraft and at various landing sites, taking into account the possible volatile inventory (e.g., CO2 ice, H2O ice) along with its time variation throughout the Martian year. Particle transport has been performed with the HZETRN heavy ion code. The Mars Radiation Environment Model has been made available worldwide through the Space Ionizing Radiation Effects and Shielding Tools (SIREST) website, a project of NASA Langley Research Center.

Implementation of ALARA radiation protection on the ISS through polyethylene shielding augmentation of the Service Module Crew Quarters

With 5-7 month long duration missions at 51.6 degrees inclination in Low Earth Orbit, the ionizing radiation levels to which International Space Station (ISS) crewmembers are exposed will be the highest planned occupational exposures in the world. Even with the expectation that regulatory dose limits will not be exceeded during a single tour of duty aboard the ISS, the "as low as reasonably achievable" (ALARA) precept requires that radiological risks be minimized when possible through a dose optimization process. Judicious placement of efficient shielding materials in locations where crewmembers sleep, rest, or work is an important means for implementing ALARA for spaceflight. Polyethylene (CnHn) is a relatively inexpensive, stable, and, with a low atomic number, an effective shielding material that has been certified for use aboard the ISS. Several designs for placement of slabs or walls of polyethylene have been evaluated for radiation exposure reduction in the Crew Quarters (CQ) of the Zvezda (Star) Service Module. Optimization of shield designs relies on accurate characterization of the expected primary and secondary particle environment and modeling of the predicted radiobiological responses of critical organs and tissues. Results of the studies shown herein indicate that 20% or more reduction in equivalent dose to the CQ occupant is achievable. These results suggest that shielding design and risk analysis are necessary measures for reducing long-term radiological risks to ISS inhabitants and for meeting legal ALARA requirements. Verification of shield concepts requires results from specific designs to be compared with onboard dosimetry.

Radiation analysis for manned missions to the Jupiter system

An analysis for manned missions targeted to the Jovian system has been performed in the framework of the NASA RASC (Revolutionary Aerospace Systems Concepts) program on Human Exploration beyond Mars. The missions were targeted to the Jupiter satellite Callisto. The mission analysis has been divided into three main phases, namely the interplanetary cruise, the Jupiter orbital insertion, and the surface landing and exploration phases. The interplanetary phase is based on departure from the Earth-Moon L1 point. Interplanetary trajectories based on the use of different propulsion systems have been considered, with resulting overall cruise phase duration varying between two and five years. The Jupiter-approach and the orbital insertion trajectories are considered in detail, with the spacecraft crossing the Jupiter radiation belts and staying around the landing target. In the surface exploration phase the stay on the Callisto surface is considered. The satellite surface composition has been modeled based on the most recent results from the GALILEO spacecraft. In the transport computations the surface backscattering has been duly taken into account. Particle transport has been performed with the HZETRN heavy ion code for hadrons and with an in-house developed transport code for electrons and bremsstrahlung photons. The obtained doses have been compared to dose exposure limits.

New calculations of the atmospheric cosmic radiation field--results for neutron spectra

The propagation of primary cosmic rays through the Earth's atmosphere and the energy spectra of the resulting secondary particles have been calculated using the Monte Carlo transport code FLUKA with several novel auxiliary methods. Solar-modulated primary cosmic ray spectra were determined through an analysis of simultaneous proton and helium measurements made on spacecraft or high-altitude balloon flights. Primary protons and helium ions are generated within the rigidity range of 0.5 GV-20 TV, uniform in cos2theta. For a given location, primaries above the effective angle-dependent geomagnetic cut-off rigidity, and re-entrant albedo protons, are transported through the atmosphere. Helium ions are initially transported using a separate transport code called HEAVY to simulate fragmentation. HEAVY interfaces with FLUKA to provide interaction starting points for each nucleon originating from a helium nucleus. Calculated cosmic ray neutron spectra and consequent dosimetric quantities for locations with a wide range of altitude (atmospheric depth) and geomagnetic cut-off are presented and compared with measurements made on a high-altitude aeroplane. Helium ion propagation using HEAVY and inclusion of re-entrant albedo protons with the incident primary spectra significantly improved the agreement of the calculated cosmic ray neutron spectra with measured spectra. These cosmic ray propagation calculations provide the basis for a new atmospheric ionising radiation (AIR) model for air-crew dosimetry, calculation of effects on microelectronics, production of cosmogenic radionuclides and other uses.

An improved Green's function for ion beam transport

Ion beam transport theory allows testing of material transmission properties in the laboratory environment generated by particle accelerators. This is a necessary step in materials development and evaluation for space use. The approximations used in solving the Boltzmann transport equation for the space setting are often not sufficient for laboratory work and those issues are the main emphasis of the present work. In consequence, an analytic solution of the linear Boltzmann equation is pursued in the form of a Green's function allowing flexibility in application to a broad range of boundary value problems. It has been established that simple solutions can be found for high charge and energy (HZE) ions by ignoring nuclear energy downshifts and dispersion. Such solutions were found to be supported by experimental evidence with HZE ion beams when multiple scattering was added. Lacking from the prior solutions were range and energy straggling and energy downshift with dispersion associated with nuclear events. Recently, we have found global solutions including these effects providing a broader class of HZE ion solutions.

The energy spectrum of cosmic-ray induced neutrons measured on an airplane over a wide range of altitude and latitude

Crews of high-altitude aircraft are exposed to radiation from galactic cosmic rays (GCRs). To help determine such exposures, the Atmospheric Ionizing Radiation Project, an international collaboration of 15 laboratories, made simultaneous radiation measurements with 14 instruments on a NASA ER-2 high-altitude airplane. The primary instrument was a sensitive extended-energy multisphere neutron spectrometer. Its detector responses were calculated for energies up to 100 GeV using the radiation transport code MCNPX 2.5.d with improved nuclear models and including the effects of the airplane structure. New calculations of GCR-induced particle spectra in the atmosphere were used to correct for spectrometer counts produced by protons, pions and light nuclear ions. Neutron spectra were unfolded from the corrected measured count rates using the deconvolution code MAXED 3.1. The results for the measured cosmic-ray neutron spectrum (thermal to >10 GeV), total neutron fluence rate, and neutron dose equivalent and effective dose rates, and their dependence on altitude and geomagnetic cut-off agree well with results from recent calculations of GCR-induced neutron spectra.

Measurement of basal, substrate induced and total P-glycoprotein activity in bronchoalveolar lavage T-cell subsets

BACKGROUND

P-glycoprotein (P-gp) is a member of the ABC transporter superfamily. P-gp activity can be detected by measuring efflux of fluorescent substrates such as rhodamine 123 (R123). Our objectives were to evaluate P-gp activity in T cells freshly isolated from bronchoalveolar lavage (BAL) and to develop a strategy to distinguish between basal, in vitro substrate-induced, and total P-gp activities.

METHODS

Cells were obtained from blood (n = 44) and BAL (n = 34), stained for expression of CD3, CD4, CD8, and CD14, and incubated with R123 (0.13 microM) +/- cyclosporine (5 microM), a specific P-gp inhibitor. P-gp activity was detected as median fluorescence intensity (MFI) and percentage of cells falling below a pre-established cutoff.

RESULTS

BAL T cells displayed significant basal P-gp activity, which was most apparent when measured as percentage below the cutoff. Induced activity (difference between P-gp activity measured after load and efflux) was determined equally well when using the MFI or the percentage below cutoff parameter. Total activity was represented by the efflux parameters (MFI or percentage below cutoff) or by the activity-time area under the curve (AUC) method. The two efflux parameters correlated well but were insensitive to the time-dependent nature of dye efflux. In the AUC method, two samples with identical R123 brightness or percentage below cutoff after dye efflux can have very different total activities, depending on their basal activity. The AUC method was also most sensitive in distinguishing between P-gp activity in peripheral blood and resident lung T cells. Application of this methodology to the comparison of P-gp activity in BAL and peripheral CD8+ T cells best revealed the elevated total P-gp activity in BAL T cells.

CONCLUSIONS

We have systematically evaluated several methodologies for analysis of P-gp activity and arrived at a novel and robust strategy amenable to standardization and evaluation of the effects of P-gp modulators in vivo and in vitro.

Non-invasive ventilation assists chest physiotherapy in adults with acute exacerbations of cystic fibrosis

BACKGROUND

Chest physiotherapy is essential to the management of cystic fibrosis (CF). However, respiratory muscle fatigue and oxygen desaturation during treatment have been reported. The aim of this study was to determine whether non-invasive ventilation (NIV) during chest physiotherapy could prevent these adverse effects in adults with exacerbations of CF.

METHODS

Twenty six patients of mean (SD) age 27 (6) years and forced expiratory volume in 1 second (FEV1) 34 (12)% predicted completed a randomised crossover trial comparing standard treatment (active cycle of breathing technique, ACBT) with ACBT + NIV. Respiratory muscle strength (PImax, PEmax), spirometric parameters, and dyspnoea were measured before and after treatment. Pulse oximetry (SpO2) was recorded during treatment. Sputum production during treatment and 4 and 24 hours after treatment was evaluated.

RESULTS

There was a significant reduction in PImax following standard treatment that was correlated with baseline PImax (r=0.73, p<0.001). PImax was maintained following NIV (mean difference from standard treatment 9.04 cm H2O, 95% confidence interval (CI) 4.25 to 13.83 cm H2O, p=0.006). A significant increase in PEmax was observed following the NIV session (8.04 cm H2O, 95% CI 0.61 to 15.46 cm H2O, p=0.02). The proportion of treatment time with SpO2 < or =90% was correlated with FEV1 (r=-0.65, p<0.001). NIV improved mean SpO2 (p<0.001) and reduced dyspnoea (p=0.02). There were no differences in FEV1, forced vital capacity (FVC) or sputum weight, but FEF(25-75) increased following NIV (p=0.006).

CONCLUSION

Reduced inspiratory muscle strength and oxygen desaturation during chest physiotherapy are associated with inspiratory muscle weakness and severity of lung disease in adults with exacerbations of CF. Addition of NIV improves inspiratory muscle function, oxygen saturation and small airway function and reduces dyspnoea.