Combined X-ray diffraction and absorption tomography using a conical shell beam

We combine diffraction and absorption tomography by raster scanning samples through a hollow cone of pseudo monochromatic X-rays with a mean energy of 58.4 keV. A single image intensifier takes 90x90 (x,y) snapshots during the scan. We demonstrate a proof-of-principle of our technique using a heterogeneous three-dimensional (x,y,z) phantom (90x90x170 mm³) comprised of different material phases, i.e., copper and sodium chlorate. Each snapshot enables the simultaneous measurement of absorption contrast and diffracted flux. The axial resolution was ~1 mm along the (x,y) orthogonal scan directions and ~7 mm along the z-axis. The tomosynthesis of diffracted flux measurements enable the calculation of d-spacing values with ~0.1 Å full width at half maximum (FWHM) at ~2 Å. Thus the identified materials may be color-coded in the absorption optical sections. Characterization of specific material phases is of particular interest in security screening for the identification of narcotics and a wide range of homemade explosives concealed within complex "everyday objects." Other potential application areas include process control and biological imaging.

Confocal energy-dispersive X-ray diffraction tomography employing a conical shell beam

We introduce a new high-energy X-ray diffraction tomography technique for volumetric materials characterization. In this method, a conical shell beam is raster scanned through the samples. A central aperture optically couples the diffracted flux from the samples onto a pixelated energy-resolving detector. Snapshot measurements taken during the scan enable the construction of depth-resolved dark-field section images. The calculation of d-spacing values enables the mapping of material phase in a volumetric image. We demonstrate our technique using five ~15 mm thick, axially separated samples placed within a polymer tray of the type used routinely in airport security stations. Our method has broad analytical utility due to scalability in both scan size and X-ray energy. Additional application areas include medical diagnostics, materials science, and process control.

Depth resolved snapshot energy-dispersive X-ray diffraction using a conical shell beam

We demonstrate a novel imaging architecture to collect range encoded diffraction patterns from overlapping samples in a single conical shell projection. The patterns were measured in the dark area encompassed by the beam via a centrally positioned aperture optically coupled to a pixelated energy-resolving detector. We show that a single exposure measurement of 0.3 mAs enables d-spacing values to be calculated. The axial positions of the samples were not required and the resultant measurements were robust in the presence of crystallographic textures. Our results demonstrate rapid volumetric materials characterization and the potential for a direct imaging method, which is of great relevance to applications in medicine, non-destructive testing and security screening.

X-ray absorption tomography employing a conical shell beam

We demonstrate depth-resolved absorption imaging by scanning an object through a conical shell of X-rays. We measure ring shaped projections and apply tomosynthesis to extract optical sections at different axial focal plane positions. Three-dimensional objects have been imaged to validate our theoretical treatment. The novel principle of our method is scalable with respect to both scan size and X-ray energy. A driver for this work is to complement previously reported methods concerning the measurement of diffracted X-rays for structural analysis. The prospect of employing conical shell beams to combine both absorption and diffraction modalities would provide enhanced analytical utility and has many potential applications in security screening, process control and diagnostic imaging.

The micro-architecture of human cancellous bone from fracture neck of femur patients in relation to the structural integrity and fracture toughness of the tissue

Osteoporosis is clinically assessed from bone mineral density measurements using dual energy X-ray absorption (DXA). However, these measurements do not always provide an accurate fracture prediction, arguably because DXA does not grapple with ‘bone quality’, which is a combined result of microarchitecture, texture, bone tissue properties, past loading history, material chemistry and bone physiology in reaction to disease. Studies addressing bone quality are comparatively few if one considers the potential importance of this factor. They suffer due to low number of human osteoporotic specimens, use of animal proxies and/or the lack of differentiation between confounding parameters such as gender and state of diseased bone. The present study considers bone samples donated from patients (n = 37) who suffered a femoral neck fracture and in this very well defined cohort we have produced in previous work fracture toughness measurements (FT) which quantify its ability to resist crack growth which reflects directly the structural integrity of the cancellous bone tissue. We investigated correlations between BV/TV and other microarchitectural parameters; we examined effects that may suggest differences in bone remodelling between males and females and compared the relationships with the FT properties. The data crucially has shown that TbTh, TbSp, SMI and TbN may provide a proxy or surrogate for BV/TV. Correlations between FT critical stress intensity values and microarchitecture parameters (BV/TV, BS/TV, TbN, BS/BV and SMI) for osteoporotic cancellous tissue were observed and are for the first time reported in this study. Overall, this study has not only highlighted that the fracture model based upon BMD could potentially be improved with inclusion of other microarchitecture parameters, but has also given us clear clues as to which of them are more influential in this role.

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first time ever study to relate microarchitecture to the fracture toughness of cancellous bone from the femoral head of FNF victims

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reduction in bone mass relates to a reduction in the number of trabeculae and trabecular thickness and an increase in trabeculae spacing

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bone loss observed appears to be a consequence of thinning of the trabeculae in males and perforation of the trabeculae in females

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study hints that TbTh, TbSp, SMI and TbN may provide a proxy or surrogate for BV/TV

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fracture models can be improved by including microarchitecture, BMD and the bone mineral quality of osteoporotic cancellous bone

X-ray diffraction from bone employing annular and semi-annular beams

There is a compelling need for accurate, low cost diagnostics to identify osteo-tissues that are associated with a high risk of fracture within an individual. To satisfy this requirement the quantification of bone characteristics such as 'bone quality' need to exceed that provided currently by densitometry. Bone mineral chemistry and microstructure can be determined from coherent x-ray scatter signatures of bone specimens. Therefore, if these signatures can be measured, in vivo, to an appropriate accuracy it should be possible by extending terms within a fracture risk model to improve fracture risk prediction.In this preliminary study we present an examination of a new x-ray diffraction technique that employs hollow annular and semi-annular beams to measure aspects of 'bone quality'. We present diffractograms obtained with our approach from ex vivo bone specimens at Mo Kα and W Kα energies. Primary data is parameterized to provide estimates of bone characteristics and to indicate the precision with which these can be determined.

Energy-dispersive X-ray diffraction using an annular beam

We demonstrate material phase identification by measuring polychromatic diffraction spots from samples at least 20 mm in diameter and up to 10 mm thick with an energy resolving point detector. Within our method an annular X-ray beam in the form of a conical shell is incident with its symmetry axis normal to an extended polycrystalline sample. The detector is configured to receive diffracted flux transmitted through the sample and is positioned on the symmetry axis of the annular beam. We present the experiment data from a range of different materials and demonstrate the acquisition of useful data with sub-second collection times of 0.5 s; equating to 0.15 mAs. Our technique should be highly relevant in fields that demand rapid analytical methods such as medicine, security screening and non-destructive testing.

Bioactive natural products from fungicolous Hawaiian isolates: secondary metabolites from a Phialemoniopsis sp

Chemical investigations of two fungal isolates initially identified as members of the genus Phialemonium are described. Both isolates were obtained as colonists of other fungi collected on the island of Hawaii and were later assigned as P. curvatum. However, P. curvatum has recently been reclassified as a member of a new genus (Phialemoniopsis) and renamed as Phialemoniopsis curvata. Studies of solid–substrate fermentation cultures of one of these isolates afforded an oxirapentyn analogue and destruxin A₄ as major components, while analysis of the second strain led to the isolation of several simple aromatic metabolites and a compound of mixed biogenetic origin called gabusectin that had previously been reported only in a patent. Structures were assigned mainly by detailed nuclear magnetic resonance and mass spectrometry analysis, and those of two of the major components were confirmed by X-ray crystallography. This report constitutes the first description of secondary metabolites from a member of the genus Phialemoniopsis.

Diplodiatoxin, chaetoglobosins, and diplonine associated with a field outbreak of Stenocarpella ear rot in Illinois

Stenocarpella maydis causes a fungal dry-rot of maize ears and is associated with diplodiosis, a neuromycotoxicosis in cattle grazing harvested maize fields in southern Africa and Argentina. There have been no reports of Stenocarpella metabolites in maize crop residues. Chemical investigations of S. maydis-infected grain from ears exhibiting different levels of ear rot severity following a 2010 field outbreak of Stenocarpella ear rot in Illinois led to the detection of diplodiatoxin and chaetoglobosins M and O as major components in the ethyl acetate extracts by LC-MS. Following post-harvest moist incubation of the S. maydis-infected grain, the amounts of each compound increased (approx. tenfold) and chaetoglobosin K was detected as a dominant toxin. In separate (1)H NMR-based analyses, the neurotoxin diplonine was detected as a minor component in methanol extracts of S. maydis-infected grain as well as cultures of S. maydis isolates from Midwest corn. Proline betaine (=stachydrine) and glycine betaine were also detected in these extracts as major components. This constitutes the first report of chaetoglobosin M, chaetoglobosin O, proline betaine, or glycine betaine from S. maydis, and the first record of diplodiatoxin, diplonine, proline betaine, glycine betaine, or chaetoglobosins M, O, or K being associated with a natural field outreak of S. maydis ear rot.

Renal calculi in wild Eurasian otters (Lutra lutra) in England

Macroscopic renal calculi were seen in 50 of 492 (10.2 per cent) wild Eurasian otters found dead in England from 1988 to 2007. Forty-eight adults and two subadults were affected. Calculi were present in 15.7 per cent (31 of 197) of adult males and 12.7 per cent (17 of 134) of adult females. There was an increase in prevalence in the study population over time; no calculi were found in 73 otters examined between 1988 and 1996, but in most subsequent years they were observed with increased frequency. Calculi occurred in both kidneys but were more common in the right kidney. They varied greatly in shape and size; larger calculi were mostly seen in the calyces while the smallest ones were commonly found in the renal medulla. Calculi from 45 cases were examined by x-ray diffraction analysis; in 43 (96 per cent), they were composed solely of ammonium acid urate. Affected otters had heavier adrenal glands relative to their body size than unaffected otters (P<0.001). There was no significant association between body condition index and the presence of calculi (P>0.05). Many otters had fresh bite wounds consistent with intraspecific aggression. The proportion bitten increased over time and this coincided with the increased prevalence of renal calculi.

Bioactive metabolites from Stenocarpella maydis, a stalk and ear rot pathogen of maize

Stenocarpella maydis is a fungal pathogen of major importance that causes a dry-rot of maize ears and is associated with a neuromycotoxicosis in cattle grazing harvested maize fields in southern Africa and Argentina. In an effort to investigate the potential roles of S. maydis metabolites in the fungal disease cycle, ethyl acetate extracts of solid-substrate fermentations of several S. maydis isolates from maize grown in the United States were found to exhibit significant phytotoxic, antifungal, and antiinsectan activity. Chemical investigations of extracts of S. maydis isolates from Illinois and Nebraska led to the isolation or detection of the known metabolites diplodiatoxin, chaetoglobosins K and L, and (all-E)-trideca-4,6,10,12-tetraene-2,8-diol as major components. A culture of Stenocarpella macrospora from maize grown in Zambia produced diplosporin and chaetoglobosins K and L as major components that were isolated. Diplodiatoxin produced significant lesions in a maize leaf puncture wound assay. Diplosporin and chaetoglobosin K displayed moderate antiinsectan activity in dietary assays against the fall armyworm Spodoptera frugiperda, while chaetoglobosin K exhibited significant antifungal activity against Aspergillus flavus and Fusarium verticillioides. Using LC-ESIMS and (1)H NMR data, diplodiatoxin was detected as a major component in S. maydis-rotted grain, stalks, and stalk residues. This constitutes the first report of chaetoglobosins K and L from S. maydis, of (all-E)-trideca-4,6,10,12-tetraene-2,8-diol from Stenocarpella, and the first reported detection of diplodiatoxin, or any other Stenocarpella metabolite, in diseased maize seeds and stalk tissues.

Acremonium zeae, a protective endophyte of maize, produces dihydroresorcylide and 7-hydroxydihydroresorcylides

Acremonium zeae has been characterized as a protective endophyte of maize and displays antifungal activity against other fungi. Pyrrocidines A and B were discovered to be the metabolites accounting for this activity. During a population survey of A. zeae isolates from maize seeds produced in nine states to determine their ability to produce pyrrocidines, another metabolite of A. zeae, unrelated to the pyrrocidines, was found to have widespread occurrence (105 of 154 isolates) and to be produced in amounts comparable to the pyrrocidines. Further chemical studies of fermentation extracts of an A. zeae isolate (NRRL 45893) from maize led to the identification of a new compound, dihydroresorcylide, the saturated analogue of cis-resorcylide. Also identified were the two diastereomers of 7-hydroxydihydroresorcylide. Dihydroresorcylide and pyrrocidines A and B were detected by LC-APCI-MS in symptomatic maize kernels from ears that were wound-inoculated in the milk stage with A. zeae NRRL 34559.

Model fitting in two dimensions to small angle diffraction patterns from soft tissue

In our research programme small angle x-ray scattering (SAXS) is used to provide information on the axial arrangement of collagen molecules as well as data about the state of other components of the extra cellular matrix (ECM) in human tissues. Derivation of parameters to describe and simplify the data is required for much of the SAXS patterns analysis. A method is presented here to achieve function fitting to collagen diffraction peaks along with a representation of the underlying diffuse scatter. A simple model was used which proved reliable in fitting a variety of 2D diffraction patterns. The logarithm of the scatter intensity over the area of the scatter image was taken to reduce the range and improve fitting accuracy. Our model was then used to fit the log data. The model consisted of a radial exponential diffuse scatter component added to a specified number of Gaussian peaks. In 2D the peak model is toroidal, each component being rotated about a common specified centre. Initial search parameters from a 1D averaged sector were supplied to the iterative 2D fitting routine. With the aid of data weighting and basic wavelet filtering, successful and reliable fitting of a specified 2D model to real data is achievable. The process is easily automated. Multiple SAXS patterns can be fitted without operator intervention. As described the model is simple enough to converge rapidly and yet allows image data to be parameterized to a form suitable for extracting the requisite information. The fitting method is flexible enough to be extended to achieve a more comprehensive and complex pattern fitting in two dimensions if this turns out to be necessary. It is our intention to implement orientation distribution functions in the near future by including an angular scaling factor.

A preliminary study of breast cancer diagnosis using laboratory based small angle x-ray scattering

Breast tissue collected from tumour samples and normal tissue from bi-lateral mastectomy procedures were examined using small angle x-ray scattering. Previous work has indicated that breast tissue disease diagnosis could be performed using small angle x-ray scattering (SAXS) from a synchrotron radiation source. The technique would be more useful to health services if it could be made to work using a conventional x-ray source. Consistent and reliable differences in x-ray scatter distributions were observed between samples from normal and tumour tissue samples using the laboratory based 'SAXSess' system. Albeit from a small number of samples, a sensitivity of 100% was obtained. This result encourages us to pursue the implementation of SAXS as a laboratory based diagnosis technique.

Determination of depth-dependent diffraction data: a new approach

A direct method for determining powder diffraction data at specific depths from angle-dependent diffraction data is described. The method is non-destructive and only traditional data collections, where the angle of incidence is varied, are required. These angle-dependent spectra are transformed to give diffraction data arising from different depths, which may then be exploited using any conventional method. This is a novel approach as traditional methods are forced to tolerate the inherent depth averaging of grazing-angle diffraction, or only examine specific structural characteristics. In order to obtain depth-dependent X-ray diffraction data, a Fredholm integral equation of the first kind is solved using regularization techniques. The method has been validated by the generation of pseudo-experimental data having known depth profiles and solving the Fredholm integral equation to recover the solution. The method has also been applied to experimental data from a number of thin film systems.

X-ray refraction effects: application to the imaging of biological tissues

The purpose of this study was to explore the potential of refraction contrast X-ray imaging of biological tissues. Images of dissected mouse lungs, heart, liver and legs were produced using the medical beamline at the Elettra Synchrotron at Trieste, Italy. The technique used was diffraction enhanced imaging. This utilizes a silicon crystal positioned between the tissue sample and the detector to separate refracted X-rays from transmitted and scattered radiation by Bragg diffraction. The contrast in the images produced is related to changes in the X-ray refractive index of the tissues, resulting in remarkable clarity compared with conventional X-ray images based on absorption effects. These changes were greatest at the boundaries between different tissues, giving a marked edge enhancement effect and three-dimensional appearance to the images. The technique provides a way of imaging a property of biological tissues not yet exploited, and further studies are planned to identify specific applications in medical imaging.

Effect of foot balance on the intra-articular pressure in the distal interphalangeal joint in vitro

REASONS FOR PERFORMING STUDY

Increased joint pressure has been implicated in the progression of osteoarthritis.

HYPOTHESIS

That intra-articular pressure in the distal interphalangeal joint (DIP) is significantly higher in legs loaded with heel up (HU), low heel (TU), lateral side up (LU) and medial side up (MU) imbalance compared to the balanced position.

METHODS

Twelve elbow down limbs were compressed in a hydraulic loading jig and DIP pressure measured.

RESULTS

Elevating the heels by 5 degrees significantly increased DIP pressure. After 5 ml of contrast was injected into the joint, heel elevation caused a greater increase in DIP pressure and heel lowering decreased DIP pressure. Silicone rubber castings were taken of 20 DIP whilst under load. The articular contact area was localised on the dorsal aspect in the HU position, palmar aspect in the TU position and towards the elevated side with lateromedial imbalance.

CONCLUSIONS

Altered foot orientation, which could result from trimming and shoeing, therefore influences intra-articular pressure in the DIP and the articular contact area.

POTENTIAL CLINICAL RELEVANCE

The results support the view that a balanced foot is the ideal and that the elevated heels may be detrimental to long term viability of the DIP joint.

An X-ray diffraction study of the effects of heat treatment on bone mineral microstructure

A series of human cortical bone specimens has been heated to temperatures up to 1200 degrees C and the mineral content examined in detail by X-ray diffraction. Line profile analysis of the diffraction data has been undertaken to characterise the microstructural (crystallite size and microstrain) features of the mineral at each temperature. Individual profile fitting of several maxima from each diffractogram has also provided precise lattice parameters of the apatite at each temperature. The apatite did not show any significant decomposition over the temperature range although CaO was increasingly formed at temperatures above 600 degrees C. Both finite crystallite size and microstrain contributed significantly to the diffraction peak broadening below 600 degrees C. When heated to > 800 degrees C, the small, rod-like mineral crystallites changed from a highly anisotropically strained state to one with significantly larger equidimensional crystals possessing little microstrain. The findings are discussed in the context of graft bone substitutes and surgical heating of bone.

Breast cancer diagnosis using scattered X-rays

Small-angle X-ray diffraction data has been collected from 99 ;core-cut' breast tissue specimens representing a number of different pathologies. Data in the range 75-1390 A have been compared with controls from patients with no breast disease. Bessel functions and Bragg maxima resulting from the fibrillar structure of collagen have been identified. The Bragg maxima indexed onto a 649 A lattice. Systematic differences in the intensities and D-spacings between the collagen of malignant, benign and normal tissue groups have been clearly demonstrated and quantified. These differences appear to be due to a significantly lower structural order within the malignant tissues. Possible explanations for this are discussed and the potential for utilizing this observation in cancer diagnosis is considered.

Pediatric sledding injuries in Pennsylvania

OBJECTIVE

To describe the frequency, characteristics, and circumstances of pediatric sledding-associated injuries and to assess the validity of published risk factors and prevention measures for these injuries.

METHODS

A retrospective, descriptive study of patients admitted to the 25 accredited trauma centers in Pennsylvania.

RESULTS

Two hundred twenty-six patients were admitted for sledding-related injuries. Sixty-nine percent were male. The mean ICU LOS was 1.2 days (SD = 3), and the mean hospital LOS was 7 days (SD = 7.2). Ninety-eight percent were discharged alive. Forty-seven percent of the ISS scores were classified as moderate (ISS 7-15). There was almost no correlation between age and ISS (r = 0.06), but there was moderate correlation between ISS and length of ICU stay (r = 0.47). Hitting trees and stationary objects (n = 121) was the most common circumstance of injury. Patients struck by moving vehicles (n = 16) had the highest proportion of head (30%) and chest (15%) injuries, the highest mortality rate (33%), the highest median ISS score (20) and the highest mean ICU LOS (6.4 days) compared to patients who hit stationary objects or fell.

CONCLUSIONS

Among children admitted to Pennsylvania trauma centers, most sledding injuries were of a mild and moderate severity and required an average of a week's hospitalization. Most children were injured from collision with stationary objects, supporting the precaution against sledding in areas with obstacles. The high mortality rate from motor vehicle/sled collisions justifies the prohibition against sledding in areas with moving vehicles.

Intra- and interobserver variability in interpretation of DMSA scans using a set of standardized criteria

A set of criteria was developed to standardize assessment of DMSA renal scintigraphy which were performed to evaluate children for acute pyelonephritis and renal scarring. This study was undertaken to assess intra- and interobserver variability in the interpretation of DMSA renal scintigraphy using these criteria. Renal contours and parenchyma were assessed in three zones. Contours were assessed as normal or abnormal and parenchymal defects were evaluated in terms of character, shape and degree in three regions (upper and lower pole and midzone). Two nuclear medicine physicians blindly reviewed 57 DMSA scintigraphy on two occasions each. Disagreement of each observer's evaluation of the same scintigraphy on two different occasions was described as intraobserver variability, and the comparison between readings by each of the two observers was described as interobserver variability. High levels of intra- (95.9% and 90.6% respectively, p < 0.05) and interobserver agreement (84.4%, p < 0.05) were demonstrated. There were minor differences in inconsistencies between the two kidneys or different kidney zones. We conclude that standardization of criteria resulted in higher intra- and interobserver consistency in interpretation of DMSA scintigraphy.

Disability from bicycle-related injuries in children

Bicycle crashes are a major cause of injuries in childhood. The goal of this study was to determine the long-term disabilities caused by bicycle-related injuries, and to clarify the long-term treatment priorities of injured children. Hospital records of 372 children (ages 2-15 yr, median 9 yr; 232 boys and 140 girls) admitted with bicycle-related injuries from 1979 through 1986 provided clinical information, social service visits, in-hospital and outpatient rehabilitative interventions, and physical status at discharge. More complete evaluations were made by contacting parents by telephone (82 children), and by personal interview and physical examinations (27). Head injuries predominated (69.1%). Twelve (3.2%) died, all from major head injuries. Four suffered permanent severe impairment from cervical spinal injuries and head injuries and remain institutionalized (1.4%). One third had a persistent disability noted at the time of discharge in the medical record (33.6%), reported by telephone interview (31.7%), or confirmed by physical examination (37.0%). Still, only 11.0% received physical therapy consultations during hospitalization, and 22.8% received social service assistance. Only 39.0% were seen by a surgeon or pediatrician after discharge, and few (7.3%) received outpatient physical therapy. Cognitive or behavior changes were noted in 31.7%, many noting changes in school performance (worse in 20.7%), behavior (13.4%), and sleep, particularly nightmares (34.1%). Recurrent injuries occurred in 52 children (14.4%), of whom ten (2.8%) required further hospital admission. Bicycle-related injuries cause significant short- and long-term disabilities among children.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of adenoidectomy for recurrent otitis media in children previously treated with tympanostomy-tube placement. Results of parallel randomized and nonrandomized trials

We studied the efficacy of adenoidectomy in 213 children who had received tympanostomy-tube placement because of persistent and/or recurrent otitis media and had again developed otitis media after tubal extrusion. Ninety-nine of the children were assigned randomly to either an adenoidectomy group or a control group; in a separate trial, 114 children whose parents withheld consent for randomization were assigned according to parental preference. In both trials, control group outcomes appeared to have been biased favorably by the withdrawal of certain severely affected subjects from control status to receive adenoidectomy. Nonetheless, in both trials, adenoidectomy group outcomes were more favorable than control group outcomes during the first 2 follow-up years. Statistically significant differences were found mainly in the randomized trial, where during the first and second years, respectively, adenoidectomy subjects had 47% and 37% less time with otitis media than control subjects and 28% and 35% fewer suppurative (acute) episodes than control subjects. We conclude that adenoidectomy is warranted on an individualized basis for children who develop recurrent otitis media after extrusion of tympanostomy tubes.

Status of scrap (recyclable) dental amalgams as environmental health hazards or toxic substances

This article presents information garnered after an investigation by the Environmental Protection Agency in 1987 of dentists and others who had sold scrap dental amalgam to refiners who had "arranged for the disposal or treatment ... of hazardous substances," and were responsible for adverse consequences associated with their subsequent management and refining. Information about the health hazard status of scrap dental amalgams was obtained by: interviews with toxicologists, review of published lists of toxic and hazardous materials, and survey of biomedical publications (1977 through 1987) concerning toxicity or health hazards associated with dental amalgams. The conclusions were that scrap dental amalgam is not: a waste substance to be disposed of, but is a product of commercial value; identified or regulated by the Environmental Protection Agency, the Occupational Safety and Health Administration, the Department of Transportation, the Food and Drug Administration, the National Institute of Occupational Safety and Health, the US Public Health Service, or the Centers for Disease Control as an environmental health hazard or toxic substance; identified by toxicologists and persons responsible for solid waste regulation as a toxic substance or environmental health hazard; nor proved by scientific study to be toxic or hazardous in the manner and form in which it is collected and stored by dentists and subsequently sold to metal refiners.

Variation in repeat rates between 18 radiology departments

A comprehensive analysis of repeat rates has been obtained from an observational study of radiological practice in diagnostic X-ray departments throughout Wales. Interdepartmental and intradepartmental repeat rates are investigated for chest, abdomen, pelvis, sinus, lumbar spine, cervical spine and intravenous pyelographic examinations. The confounding effects upon observed repeat rates of trainee practitioners and automatic exposure control devices are also considered. The overall proportions of total film cost and patient exposure attributable to repeat radiographs are estimated to be 10% and 14% respectively.

X-ray field collimation in diagnostic radiology

A comprehensive study of radiographic practice within radiodiagnostic departments throughout Wales is currently being carried out under the auspices of the College of Radiographers and the Royal College of Radiologists. This paper reports on collimation practices observed in more than 2000 individual patient radiographs involving seven types of examination. Film dimensions are compared to those of the X-ray field and the unnecessary irradiation of radiosensitive organs consequent upon inappropriate collimation is considered. The suitability of film sizes frequently chosen for particular projections is also examined.

Physical maturity and outcome of pregnancy in primiparas younger than 16 years of age

The association of complications and adverse outcomes of early teenage pregnancy with physical growth maturation of mothers was studied in subjects identified from review of medical records in a Pittsburgh obstetrical hospital from 1970 through 1977. Five groups were used to categorize the subjects: (1) 449 primiparas younger than 16 years of age, (2) 347 primiparas 20 to 24 years of age, pair-matched with subjects in group 1 by race, hospital service status, sex of infant, trimester of first prenatal visit, and year of delivery within 5 years, (3) 139 group 1 mothers at the time of their second delivery, (4) 104 group 1 primiparas whose postmenarcheal age was less than or equal to 2.6 years at delivery, and (5) 108 group 1 primiparas whose postmenarcheal age was greater than or equal to 4.1 years at delivery. Subjects in groups 1 and 2, first and second pregnancies of subjects in group 3, and subjects in groups 4 and 5 were compared for prepregnancy weight and height, weight gain during pregnancy, complications of pregnancy, birth weight and gestational age of infant, and perinatal morbidity and mortality. Although primiparas younger than 16 years of age had not achieved mature height and weight, no relationship between mother's physical growth maturation and adverse pregnancy course or outcome was demonstrated.

School performance characteristics preceding onset of smoking in high school students

The cigarette smoking status of 1,442 high school students was determined by questionnaire. Of the respondents (smoking and nonsmoking), 60% had been enrolled in the same school system during elementary school. Thus, records were available of school absence, grades, achievement tests, and IQ tests during elementary school, prior to the time when the smokers had commenced the practice. Smoking in high school was significantly related to high absence rates, low achievement test scores, and low grade point averages during elementary school years, prior to the onset of smoking. The IQ was not significantly different in the third grade among pupils who became smokers in high school and those who did not, but sixth-grade IQ scores were significantly lower in students who later identified themselves as smokers. Although smokers demonstrated these characteristics prior to beginning smoking, the differences were not large enough to predict which elementary school students would become high school smokers. The findings support the view that smoking and these school-related characteristics may both be part of a "smoker life-style."

Neonatal characteristics of maltreated infants and children

We compared selected neonatal characteristics of 40 children who were abused and neglected (34) or who failed to thrive (six) and 40 nonabused, thriving children individually matched by hospital of birth, gender, mother's welfare status, race, and age at which abuse or failure to thrive was manifested. The populations were preponderantly lower-class, black, and male. The following characteristics were overrepresented in the study population: birth order second or later, low birth weight, admitted to neonatal intensive care unit, and discharged from hospital after mother. The higher incidence of full-term infants who were small for gestational age for the study population (20%) than for the control population (3%) was of borderline significance. The lower distribution of birth weights in relation to expected birth weights for the full-term study subjects, however, was highly significant.

A community medicine clerkship on the Navajo Indian reservation

An elective clerkship in community medicine for medical students has been conducted for 16 years on the Navajo Indian reservation. An important part of the clerkship is a project in which most students select a health problem which they investigate using epidemiological methods of assessment and for which they seek a solution. The requisites for the projects are that real health problems are involved, scientifically sound methods are used, usable information is provided, and data collection can be completed within the clerkship tenure. Topics for the projects are selected jointly by the students and the faculty members from several general subject areas; this allows the work of individual students to be carried out as independent subprojects of larger projects, and this, in turn, produces more information about and has more impact on the problems addressed. Other clerkship objectives also are achieved through investigative projects that may involve students in planning, organization, and evaluation of health care and in public health practice.

Efficacy of tonsillectomy for recurrent throat infection in severely affected children. Results of parallel randomized and nonrandomized clinical trials

We studied the efficacy of tonsillectomy, or tonsillectomy with adenoidectomy, in 187 children severely affected with recurrent throat infection. Ninety-one of the children were assigned randomly to either surgical or nonsurgical treatment groups, and 96 were assigned according to parental preference. In both the randomized and nonrandomized trials, the effects of tonsillectomy and of tonsillectomy with adenoidectomy were similar. By various measures, the incidence of throat infection during the first two years of follow-up was significantly lower (P less than or equal to 0.05) in the surgical groups than in the corresponding nonsurgical groups. Third-year differences, although in most cases not significant, also consistently favored the surgical groups. On the other hand, in each follow-up year many subjects in the nonsurgical groups had fewer than three episodes of infection, and most episodes among subjects in the nonsurgical groups were mild. Of the 95 subjects treated with surgery, 13 (14 per cent) had surgery-related complications, all of which were readily managed or self-limited. These results warrant the election of tonsillectomy for children meeting the trials' stringent eligibility criteria, but also provide support for nonsurgical management. Treatment for such children must therefore be individualized.

Lack of efficacy of a decongestant-antihistamine combination for otitis media with effusion ("secretory" otitis media) in children. Results of a double-blind, randomized trial

In a double-blind, randomized trial of 553 infants and children who had otitis media with effusion ("secretory" otitis media), we compared the efficacy of a four-week course of an oral decongestant-antihistamine combination (pseudoephedrine hydrochloride, 4 mg per kilogram of body weight per day, and chlorpheniramine maleate, 0.35 mg per kilogram per day) with that of placebo. Among patients with initially unilateral disease, resolution of middle-ear effusion occurred at four weeks in 38 per cent of those treated with placebo and 34 per cent of those treated with drug (P = 0.74). Among patients with initially bilateral disease the corresponding proportions were 19 and 21 per cent, respectively (P = 0.67). Side effects were reported more often among drug-treated than placebo-treated patients. Decongestant-antihistamine combinations do not appear to be indicated for the treatment of otitis media with effusion in infants and children.

Racial differences in intraocular tension and glaucoma surgery

A total of 4678 persons participated in an Allegheny County, Pennsylvania glaucoma screening program in 1977. Black participants had higher mean intraocular pressures, more frequent pathologic disc changes and more new cases of glaucoma discovered than a sample of white participants matched for sex and age. The same year, in a younger population of 2127 health center employees, the higher prevalence of pathologic disc changes was confirmed, although differences in mean intraocular pressures were variable. Blacks accounted for 23% of hospitalizations for chronic open-angle glaucoma during a three-year period (1975-1977) in 10 Pennsylvania counties, rather than the expected 6.3%. Among those hospitalized for open-angle glaucoma or having anterior chamber surgery, blacks were younger than whites.

Injuries in high school physical education classes

Suburban high school pupils participating in physical education classes sustained 3.6 injuries per 100 participants per year that were noted on official school accident reports, and 5.4 injuries per 100 for which pupils visited the school nurse. These latter injuries were minor. The official school accident reports indicated that injuries occurred at approximately equal rates in boys and girls; most were due to accidents that did not involve another participant or a piece of sports equipment, and, although usually not severe, were referred by the school nurse for further evaluation or treatment in some cases. Sprains were the most common type of injury and the ankle was the most commonly injured area. No particular set of conditions was identified wherein preventive measures could be taken to decrease the injury rate.

Efficacy of adenoidectomy in recurrent otitis media. Historical overview and preliminary results from a randomized, controlled trial

Adenoidectomy is well established as a procedure for treating children with recurrent or persistent otitis media. Many physicians also believe that when adenoidectomy is undertaken for otitis media, tonsillectomy also should be done routinely. Thus otitis media serves as the justification for a substantial proportion of the tonsil and adenoid operations carried out on children. Nonetheless, evidence supporting the efficacy of adenoidectomy, or tonsillectomy and adenoidectomy (T&A), for otitis media is scant and inconclusive. Only six prospective studies have been reported, and in all but two of them, the combination of adenoidectomy with tonsillectomy, rather than adenoidectomy alone, was tested. The results were contradictory, perhaps because of all the studies contained flaws in design or methodology or both. Whether adenoidectomy or T&A are efficacious remains entirely uncertain. We are attempting to address the question currently in a prospective study in which children considered at high risk for otitis media are entered into a randomized, controlled clinical trial of adenoidectomy. The trial is complicated by the need to take adequate account of subject variables such as age, sex, adenoid size, and the presence or absence of allergy, and of the important treatment variables of concomitant myringotomy with tympanostomy tube insertion. Outcome measurements employed in the trial include the number of episodes per year of acute otitis media, the persistence of middle ear effusion, and the frequency of subsequent myringotomy. Data thus far collected in the study are not sufficient to reach a conclusion for or against the efficacy of adenoidectomy for otitis media, but it is apparent that adenoidectomy by no means eliminates the problem.

Acute rheumatic fever and rheumatic heart disease on the Navajo reservation, 1962-77

The occurrence of acute rheumatic fever (ARF) and rheumatic heart disease (RHD) among Navajos was ascertained for the period from 1962 through 1977 by means of hospital discharge diagnoses and patients' charts. The annualized attack rate for ARF was 12.4 per 100,000 population, with no clear evidence of an overall secular trend. The proportion of recurrences (19.6 percent) and clinical features were similar to those reported elsewhere, but no seasonal variation in attack rates was noted. Between 1962-71 and 1972-77, the age of RHD patients increased, suggesting few newly diagnosed cases and the aging of known patients. A streptococcal disease control program was instituted in many Navajo elementary schools before 1975. In the program, throat cultures were performed routinely for some asymptomatic children and for all symptomatic children. During the subsequent 3 years, ARF rates declined from 13.5 to 8.2 per 100,000 in areas covered by the program, while in the noncovered areas the rates showed little change-9.5 to 10.1 per 100,000.

Age, sex, and season of onset of juvenile diabetes in different geographic areas

Age, sex, and estimated time of onset of insulin-dependent diabetes were determined for children in Pittsburgh (N = 673), Gainesville (N = 976), Galveston (n = 741), and Melbourne (N = 851). The US cities had a decrease in new cases during the summer and peak incidence in January through April. In Melbourne, monthly trends were reversed: there were more cases during May through August. In US cities, but not in Melbourne, children less than 6 years old showed a greater variation by season than children 6 years old and older. Observations of the same fall and winter onset (in different calendar months) of insulin-dependent diabetes in Australia and the United States, and exaggeration of seasonal differences in young US children, suggest that onset of insulin-dependent diabetes is associated with seasonally varying viral diseases. Mumps and rubella infections do not seem to be responsible for much of the seasonal variation. Seasonal peaks of mumps and rubella are later than those observed for insulin-dependent diabetes, and immunization with live mumps and rubella viruses has not been associated with changes in incidence of insulin-dependent diabetes. An increase in disease incidence in boys over girls below age 6 years and in girls over boys at ages 6 through 11 years was consistently observed but not explained.

History of recurrent sore throat as an indication for tonsillectomy. Predictive limitations of histories that are undocumented

As part of a prospective study of indications for tonsillectomy and adenoidectomy, we followed closely 65 children with histories of recurrent throat infection that seemed impressive (at least seven episodes in one year, five in each of two consecutive years or three in each of three consecutive years), but lacked documentation. During the first year of observation, only 11 children (17 per cent) had episodes of throat infection with clinical features and patterns of frequency conforming to those described in their presenting histories. Of the remaining 54 children, 43 (80 per cent) experienced no, one or two observed episodes each, and most of the episodes were mild. We conclude that undocumented histories of recurrent throat infection do not validly forecast subsequent experience and hence do not constitute an adequate basis for subjecting children to tonsillectomy.