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Biomedical subjects

A L Frank

Publications and source records attributed to A L Frank.

At least 37 records · Page 2Linked to original sources
PubMed1997

Influenza virus infections in infants.

BACKGROUND: Universal immunization of children with live attenuated cold recombinant vaccine has been proposed. The renewed recommendation for maternal immunization with influenza vaccine should increase the amount of antibody transmitted to the infant and postpone the need for active immunization. This study examines the risk of influenza during the first year of life to provide information about the time to initiate active immunization. METHODS: Infants followed from birth to 1 year of age in the Houston Family Study were monitored weekly for influenza virus infection. Serum specimens were tested for evidence of infection at 4-month intervals. RESULTS: One-third of 209 infants were infected during the first year; most of the infections occurred during the second 6 months of life. Only 26 of 69 infections were detected before 6 months of age compared with 43 afterward. More striking was the concentration of serious illnesses in the latter half of the first year; 8 of 9 otitis media episodes and 9 of 11 lower respiratory tract illnesses occurred in the older infants. CONCLUSIONS: The combination of increased maternal antibody titers that should result from influenza immunization and the lesser risk of influenza in the first 6 months of life allows initiation of active immunization of children after 6 months of age.

Antibodies, Viral↗
PubMed1997

Unexpected opportunities: incidental findings detected during impairment evaluations for coal workers' pneumoconiosis.

Coal workers' pneumoconiosis impairment evaluations for 374 miners, predominantly from eastern Kentucky, were conducted by our department between January 1, 1989, and June 30, 1992. During a review of the cases, potentially significant findings not directly related to any detected pneumoconiosis were recorded. Sixty-five (17.4%) of the men had blood pressure > or = 150 mm Hg systolic or > or = 90 mm Hg diastolic during one measurement. Of 89 workers who had a previous diagnosis of hypertension and were being treated, 40 (44.9%) had an elevated blood pressure measurement. Twelve cases of incidental, previously undetected chest radiograph findings warranted follow-up; 9 of these were isolated pulmonary nodules. In addition, three patients were immediately referred for evaluation and treatment of conditions newly diagnosed during the examination--one for unstable angina pectoris, one for congestive heart failure, and one for recent cerebrovascular accident. These cases illustrate that physicians doing impairment evaluations, even if they are not the patient's treating physician, have the opportunity and responsibility to intervene and reduce morbidity and mortality.

Adult↗
PubMed1996

Kaolinosis in a cotton mill worker.

A 62-year-old white male employed for 43 years in the polishing room of a cotton textile mill was admitted to a tertiary care center with progressive dyspnea and productive cough that had not responded to therapy for tuberculosis. In spite of aggressive antibiotic therapy and respiratory support, the patient died as a consequence of respiratory failure. Small rounded and irregular opacities had been noted on the chest radiograph. Review of job-site spirometry demonstrated a worsening restrictive pattern over a 4-year period prior to his death. Additional occupational history revealed long-term exposure to kaolin in the polishing room, and pathologic examination of lung tissue confirmed extensive fibrosis and substantial quantities of kaolin. Kaolinosis is a disease typically found among individuals involved in mining or processing this material rather than in user industries. This case illustrates the importance of obtaining a complete occupational history in reaching a diagnosis. The clinicopathologic aspects of kaolinosis are also reviewed.

Fatal Outcome↗
PubMed1996

In-flight radiation measurements on STS-60.

A joint investigation between the United States and Russia to study the radiation environment inside the Space Shuttle flight STS-60 was carried out as part of the Shuttle-Mir Science Program (Phase 1). This is the first direct comparison of a number of different dosimetric measurement techniques between the two countries. STS-60 was launched on 3 February 1994 in a nearly circular 57 degrees x 353 km orbit with five U.S. astronauts and one Russian cosmonaut for 8.3 days. A variety of instruments provided crew radiation exposure, absorbed doses at fixed locations, neutron fluence and dose equivalent, linear energy transfer (LET) spectra of trapped and galactic cosmic radiation, and energy spectra and angular distribution of trapped protons. In general, there is good agreement between the U.S. and Russian measurements. The AP8 Min trapped proton model predicts an average of 1.8 times the measured absorbed dose. The average quality factor determined from measured lineal energy, y, spectra using a tissue equivalent proportional counter (TEPC), is in good agreement with that derived from the high temperature peak in the 6LiF thermoluminescent detectors (TLDs). The radiation exposure in the mid-deck locker from neutrons below 1 MeV was 2.53 +/- 1.33 microSv/day. The absorbed dose rates measured using a tissue equivalent proportional counter, were 171.1 +/- 0.4 and 127.4 +/- 0.4 microGy/day for trapped particles and galactic cosmic rays, respectively. The combined dose rate of 298.5 +/- 0.82 microGy/day is about a factor of 1.4 higher than that measured using TLDs. The westward longitude drift of the South Atlantic Anomaly (SAA) is estimated to be 0.22 +/- 0.02 degrees/y. We evaluated the effects of spacecraft attitudes on TEPC dose rates due to the highly anisotropic low-earth orbit proton environment. Changes in spacecraft attitude resulted in dose-rate variations by factors of up to 2 at the location of the TEPC.

Atlantic Ocean↗
PubMed1996

Intercomparison of radiation measurements on STS-63.

A joint NASA Russia study of the radiation environment inside the Space Shuttle was performed on STS-63. This was the second flight under the Shuttle-Mir Science Program (Phase 1). The Shuttle was launched on 2 February 1995, in a 51.65 degrees inclination orbit and landed at Kennedy Space Center on 11 February 1995, for a total flight duration of 8.27 days. The Shuttle carried a complement of both passive and active detectors distributed throughout the Shuttle volume. The crew exposure varied from 1962 to 2790 microGy with an average of 2265.8 microGy or 273.98 microGy/day. Crew exposures varied by a factor of 1.4, which is higher than usual for STS mission. The flight altitude varied from 314 to 395 km and provided a unique opportunity to obtain dose variation with altitude. Measurements of the average east-west dose variation were made using two active solid state detectors. The dose rate in the Spacehab locker, measured using a tissue equivalent proportional counter (TEPC), was 413.3 microGy/day, consistent with measurements made using thermoluminescent detectors (TLDs) in the same locker. The average quality factor was 2.33, and although it was higher than model calculations, it was consistent with values derived from high temperature peaks in TLDs. The dose rate due to galactic cosmic radiation was 110.6 microGy/day and agreed with model calculations. The dose rate from trapped particles was 302.7 microGy/day, nearly a factor of 2 lower than the prediction of the AP8 model. The neutrons in the intermediate energy range of 1-20 MeV contributed 13 microGy/day and 156 microSv/day, respectively. Analysis of data from the charged particle spectrometer has not yet been completed.

Atlantic Ocean↗
PubMed1996

Secondary particle contribution to LET spectra on LDEF.

Four experiments utilizing passive detectors (P0006, P0004, A0015, M0004) were flown on LDEF to study the radiation environment. These experiments have been summarized in a companion paper (Benton et al., 1996). One of the experimental goals was to measure LET spectra at different locations and shielding depths with plastic nuclear track detectors (PNTD). It was found that the LET spectra extended well above the LET cutoff imposed by the geomagnetic field on GCR particle penetration into LEO. The high LET particles detected were mostly short-range (range < 2000 m), indicating that they were secondaries produced locally within the PNTD. The presence of these high LET particle fluences is important for the determination of dose equivalent because of the high Quality Factors (Q) involved. A relatively small fraction of particle fluence can contribute a large fraction of dose equivalent. Short-range, inelastic secondary particles produced by trapped protons in the South Atlantic Anomaly (SAA) were found to be a major contributor to the LET spectra above 100 keV/micrometer. The LET spectra were found to extend beyond the approximately 137 keV/micrometer relativistic GCR Fe peak to over 1000 keV/micrometer. The high LET tail of the LET spectra was measured in CR-39 and polycarbonate PNTDs using different techniques. GCR made a relatively modest contribution to the LET spectra as compared to the contributions from short-range secondary particles and stopping protons. LET spectra intercomparisons were made between LDEF measurements and exposures to 154 MeV accelerated proton beams. The similarities support the role of nuclear interactions by trapped protons as the major source of secondary particles in the PNTDs. Also techniques were employed to reduce the range cutoff for detection of the short-range secondaries to approximately 1 micrometer, so that essentially all secondary particles were included in the LET spectra. This has allowed a more realistic assessment of secondary contribution to dose equivalent. Comparisons of measured and calculated LET spectra have been made that demonstrate the need for more accurate modeling of secondary particles in radiation transport codes. Comparisons include preliminary calculations in which attempts have been made to include secondary particles.

Atlantic Ocean↗
PubMed1996

LET spectra measurements on LDEF: variations with shielding and location.

LET spectra measurements made with passive plastic nuclear track detectors (PNTDs) were found to depend on detector orientation, shielding and experiment location. LET spectra were measured at several locations on LDEF as part of the P0006 LETSME experiment (Benton and Parnell, 1984), the P0004 Seeds in Space experiment (Parks and Alston, 1984), the A00l5 Free Flyer Biostacks and the M0004 Fiber Optics Data Link experiment (Taylor, 1984). Locations included the east, west and Earth sides of the LDEF satellite. The LET spectra measured with PNTDs deviated significantly from calculations, especially for high LET particles (LET infinity H2O > or = 100 keV/micrometer). At high LETs, short-range inelastic secondary particles produced by trapped proton interactions with the nuclei of the detector were found to be the principal contributor to LET spectra. At lower LETs, the spectra appeared to be due to short-range, inelastic and stopping primary protons, with primary GCR particles making a smaller contribution. The dependence of LET spectra on detector orientation and shielding was studied using the four orthogonal stacks in the P0006 experiment. Both measurements of total track density and LET spectra showed a greater number of particles arriving from the direction of space than from Earth. Measurements of LET spectra in CR-39 PNTD on the east (leading) and west (trailing) sides of LDEF showed a higher rate of production at the west side. This was caused by a larger flux of trapped protons on the west side as predicted by the east/west trapped proton anisotropy in the South Atlantic Anomaly (SAA). Track density measured in CR-39 PNTDs increased as a function of shielding depth in the detector stack. A similar measurement made in a thick stack of CR-39 interspersed with layers of Al and exposed to 154 MeV protons at a ground-based accelerator showed a similar result, indicating that a significant fraction of the particle events counted were from secondaries and that the total cross-section for production of proton-induced secondaries increased as the energy of primary protons attenuated. Little change was seen in either total differential or integral LET spectra as a function of shielding depth, indicating that the increase in cross section with decreasing proton energy affected mostly the shorter range secondary components. Similarity in the slopes of LET spectra from ground-based proton exposures and the A00l5 LET spectra showed that modeling of a monoenergetic proton beam transported through a 1-D geometry was a useful first step in modeling the production of secondary particles by trapped protons in the SAA.

Atlantic Ocean↗
PubMed1996

Absorbed dose measurements on LDEF and comparisons with predictions.

The radiation environment on LDEF was monitored by cumulative absorbed dose measurements made with TLDs at different locations and shielding depths. The TLDs were included in four experiments: A0015(a) Biostack, P0004 Seeds in Space and P0006 Linear Energy Transfer Spectrum Measurements at the trailing edge (west side) of the satellite; M0004 Fiber Optics Data Link at the leading edge (east side); and A0015(b) Biostack at the Earth side. The shielding depths varied between 0.48 and 15.4 g/cm2, Al equivalent. Both the directional dependence of trapped protons incident on the satellite and the shielding thickness were reflected in absorbed dose values. The trapped proton anisotropy was measured by TLDs at the east and west sides of LDEF. At the east side doses ranged from 2.10 to 2.58 Gy under shielding of 2.90 to 1.37 g/cm2 (M0004) while on the west side doses ranged from 2.66 to 6.48 Gy under shielding of 15.4 to 0.48 g/cm2 (P0006). The west side doses were more than a factor of two higher, where the vertical shielding thicknesses to space were equal. Other west side doses of 3.04 to 4.49 Gy under shielding of 11.7 to 3.85 g/cm2 (A0015(a)) and 2.91 to 6.64 Gy under shielding of 11.1 to 0.48 g/cm2 (P0004) generally agreed with the P0006 results. The Earth side doses of 2.41 to 3.93 Gy under shielding of 10.0 to 1.66 g cm2 (A0015(b)) were intermediate between the east side and west side doses. Calculations utilizing a model of trapped proton spectra were performed by Watts et al. (1993) and comparisons of dose measurement and calculations may be found in a companion paper (Armstrong et al., 1996).

Aluminum↗
PubMed1996

Neutron fluences and dose equivalents measured with passive detectors on LDEF.

Neutron fluences were measured on LDEF in the low energy (< 1 MeV) and high energy (> 1 MeV) ranges. The low energy detectors used the 6Li(n,alpha)T reaction with Gd foil absorbers to separate thermal (< 0.2 eV) and resonance (0.2 eV-1 MeV) neutron response. High energy detectors contained sets of fission foils (181Ta, 209Bi, 232Th, 238U) with different neutron energy thresholds. The measured neutron fluences together with predicted spectral shapes were used to estimate neutron dose equivalents. The detectors were located in the A0015 and P0006 experiments at the west and Earth sides of LDEF under shielding varying from 1 to 19 g/cm2. Dose equivalent rates varied from 0.8 to 3.3 microSv/d for the low energy neutrons and from 160 to 390 microSv/d for the high energy neutrons. This compares with TLD measured absorbed dose rates in the range of 1000-3000 microGy/d near these locations and demonstrates that high energy neutrons contribute a significant fraction of the total dose equivalent in LEO. Comparisons between measurements and calculations were made for high energy neutrons based on fission fragment tracks generated by fission foils at different shielding depths. A simple 1-D slab geometry was used in the calculations. Agreement between measurements and calculations depended on both shielding depth and threshold energy of the fission foils. Differences increased as both shielding and threshold energy increased. The modeled proton/neutron spectra appeared deficient at high energies. A 3-D model of the experiments is needed to help resolve the differences.

Extraterrestrial Environment↗
PubMed1996

Particle directionality and trapped proton fluences on LDEF.

Directionality of incident space radiation is a significant factor in spacecraft shielding and astronaut dosimetry in low Earth orbit (LEO). Particle directionality of GCR and trapped protons were measured on LDEF with plastic nuclear track detectors (PNTD) from the P0006 west-side experiment. This experiment consisted of a thick detector stack and is described more fully in a companion article (Benton et al., 1996). The anisotropy of the trapped protons produced maximum intensity for protons arriving from the west. The fluences of the eastward directed trapped protons have been measured by selection of the particles on the basis of range in the PNTDs. The measured fluences are compared with the model calculations of Armstrong and Colborn (1993).

Anisotropy↗
PubMed1996

Causation, impairment, disability: an analysis of coal workers' pneumoconiosis evaluations.

The relation of exposure, impairment, and awarded disability in coal dust disease cases is often unclear. Surveillance data from large mining populations has demonstrated a decline in pulmonary function associated with coal dust exposure, even in miners with normal roentgenographs, though the frequency with which this results in impairment is not well defined. This study examines a more specific group, 374 disability claimants, for whom evaluation data is less extensive. In this group, several pulmonary function variables declined in association with years mining, even after controlling for roentgenograph status and smoking. This was particularly seen among underground miners, although the declines were small and of marginal statistical significance. Awards were evaluated for 203 resolved cases. Among 59 with completely normal roentgenographs and pulmonary function tests (PFTs), 38 (64%) received some disability award. These findings support development of a more rational impairment/disability system for those with potential coal dust disease.

Adult↗
PubMed1996

Scientific and ethical aspects of human monitoring.

Screening and monitoring activities have their place in the prevention of workplace and environmental disease and injury. Testing, while still relatively nonspecific at this time, can be appropriately used in such prevention activities. Unfortunately, such information can be misused or even put to malevolent purpose, and this complicates the moral and ethical aspects of such testing. With advances in molecular biology, one can anticipate more refined and individualized testing in the future.

Bioethics↗
PubMed1996

Influenza vaccination of children during acute asthma exacerbation and concurrent prednisone therapy.

OBJECTIVES: The influenza vaccination rate is very low among children with moderate to severe asthma. This may be partly because of poor patient motivation and failure to visit clinics for vaccination. Another important factor may be health care providers' deferral of vaccination because of concern about the efficacy and safety of influenza vaccination during asthma exacerbations and concurrent prednisone therapy. We therefore examined the safety and immunogenicity of influenza vaccination during acute asthma exacerbation with concomitant prednisone therapy. SETTING: A pediatric allergy and pulmonology clinic and a pediatric emergency department. DESIGN: Children (n = 109) with a known diagnosis of asthma 6 months to 18 years of age were recruited. All participating patients, 59 without asthma symptoms (no prednisone, control group) and 50 with acute asthma exacerbation requiring prednisone burst therapy (prednisone group) received trivalent subvirion influenza vaccine. Fifteen children in the control group and 12 in the prednisone group received a booster dose according to American Academy of Pediatrics guidelines. Serum antibody titers to influenza A/Beijing/32/92 (H3N2), influenza A/Texas/36/91 (H1N1), and influenza B/Panama/45/90 were measured before and 2 weeks after vaccination. Adverse effects noted within 48 hours after vaccine dose were ascertained during the follow-up visit. RESULTS: The antibody response was analyzed by comparing mean postvaccine titers, the percentage of patients achieving protective antibody levels (> or = 5log2), and the percentage of patients achieving rises in titers of 2log2 or greater. Antibody responses to influenza A/Beijing/32/92 (H3N2) and influenza A/Texas/36/91 (H1N1) in the prednisone-treated and control groups were not different. A significantly better response to the influenza B/Panama/45/90 antigen was seen in the prednisone group for all three parameters. Children who received a booster dose and the subgroup of children with low prevaccination titers (< or = 3log2) showed similar patterns. Adverse effects, including asthma exacerbation, local swelling at the injection site, fever, rash, and headache, were not different in the two groups. CONCLUSIONS: Influenza vaccination can be given safely and effectively to asthmatic children regardless of asthma symptoms or concurrent prednisone therapy when necessary. Vaccination of all moderate to severe asthmatic patients visiting clinics or emergency departments would improve the overall vaccination rate significantly.

Antibodies, Viral↗
PubMed1995

A Green's function method for heavy ion beam transport.

The use of Green's function has played a fundamental role in transport calculations for high-charge high-energy (HZE) ions. Two recent developments have greatly advanced the practical aspects of implementation of these methods. The first was the formulation of a closed-form solution as a multiple fragmentation perturbation series. The second was the effective summation of the closed-form solution through nonperturbative techniques. The nonperturbative methods have been recently extended to an inhomogeneous, two-layer transport media to simulate the lead scattering foil present in the Lawrence Berkeley Laboratories (LBL) biomedical beam line used for cancer therapy. Such inhomogeneous codes are necessary for astronaut shielding in space. The transport codes utilize the Langley Research Center atomic and nuclear database. Transport code and database evaluation are performed by comparison with experiments performed at the LBL Bevalac facility using 670 A MeV 20Ne and 600 A MeV 56Fe ion beams. The comparison with a time-of-flight and delta E detector measurement for the 20Ne beam and the plastic nuclear track detectors for 56Fe show agreement up to 35%-40% in water and aluminium targets, respectively.

Aluminum↗
PubMed1995

A study of the radiation environment on board the Space Shuttle flight STS-57.

A joint NASA-Russian study of the radiation environment inside a SPACEHAB 2 locker on Space Shuttle flight STS-57 was conducted. The Shuttle flew in a nearly circular orbit of 28.5 degrees inclination and 462 km altitude. The locker carried a charged particle spectrometer, a tissue equivalent proportional counter (TEPC), and two area passive detectors consisting of combined NASA plastic nuclear track detectors (PNTDs) and thermoluminescent detectors (TLDs), and Russian nuclear emulsions, PNTDs and TLDs. All the detector systems were shielded by the same Shuttle mass distribution. This makes possible a direct comparison of the various dose measurement techniques. In addition, measurements of the neutron energy spectrum were made using the proton recoil technique. The results show good agreement between the integral LET spectrum of the combined galactic and trapped particles using the tissue equivalent proportional counter and track detectors between about 15 keV/micrometers and 200 keV/micrometers. The LET spectrum determined from nuclear emulsions was systematically lower by about 50%, possibly due to emulsion fading. The results show that the TEPC measured an absorbed dose 20% higher than the TLDs, due primarily to an increased TEPC response to neutrons and a low sensitivity of TLDs to high LET particles under normal processing techniques. There is a significant flux of high energy neutrons that is currently not taken into consideration in dose equivalent calculations. The results of the analysis of the spectrometer data will be reported separately.

Cosmic Radiation↗
PubMed1995

Medical and public health approaches to asbestos disease.

Asbestos is known to cause a wide range of nonmalignant and malignant disease among occupationally and environmentally exposed individuals. Lung cancer and mesothelioma are of special importance. X-rays are evaluated utilizing the ILO classification, and the clinical signs and symptoms of many chronic lung diseases may occur. The fibrous nature of asbestos appears to be important, and fiber size plays a role in carcinogenic outcome. Because of the significant legal and public health implications of exposure, it appears that purposeful obfuscation of asbestos science has taken place. There are also worldwide efforts to shift patterns of use and manufacturing, leading to a wider dissemination of death and disease, especially when coupled with spreading tobacco usage.

Asbestosis↗
PubMed1995

Extracanal invasive resorption: an update.

Although it has been discussed since 1920, the entity of extracanal invasive resorption (EIR) remains misunderstood from a nomenclature, diagnostic, and treatment standpoint. At least 10 terms for it have been published in the dental literature. The key to diagnosis is that the pulp canal space has not been invaded by the resorption. Therefore, the pulp will respond to vitality testing. From a treatment standpoint, a differentiation must be made between the three types of EIR--intraosseous, crestal, or supraosseous. The latter condition may not require endodontic treatment, whereas it is necessary for the other two conditions. Regardless of the EIR's site, its successful treatment requires the debridement and obliteration of the external portal of entry and the resorptive defect.

Dental Pulp Cavity↗