Leaf metallome preserved over 50 million years.

Large-scale Synchrotron Rapid Scanning X-ray Fluorescence (SRS-XRF) elemental mapping and X-ray absorption spectroscopy are applied here to fossil leaf material from the 50 Mya Green River Formation (USA) in order to improve our understanding of the chemistry of fossilized plant remains. SRS-XRF of fossilized animals has previously shown that bioaccumulated trace metals and sulfur compounds may be preserved in their original distributions and these elements can also act as biomarkers for specific biosynthetic pathways. Similar spatially resolved chemical data for fossilized plants is sparsely represented in the literature despite the multitude of other chemical studies performed. Here, synchrotron data from multiple specimens consistently show that fossil leaves possess chemical inventories consisting of organometallic and organosulfur compounds that: (1) map discretely within the fossils, (2) resolve fine scale biological structures, and (3) are distinct from embedding sedimentary matrices. Additionally, the chemical distributions in fossil leaves are directly comparable to those of extant leaves. This evidence strongly suggests that a significant fraction of the chemical inventory of the examined fossil leaf material is derived from the living organisms and that original bioaccumulated elements have been preserved in situ for 50 million years. Chemical information of this kind has so far been unknown for fossilized plants and could for the first time allow the metallome of extinct flora to be studied.

Trace metals as biomarkers for eumelanin pigment in the fossil record.

Well-preserved fossils of pivotal early bird and nonavian theropod species have provided unequivocal evidence for feathers and/or downlike integuments. Recent studies have reconstructed color on the basis of melanosome structure; however, the chemistry of these proposed melanosomes has remained unknown. We applied synchrotron x-ray techniques to several fossil and extant organisms, including Confuciusornis sanctus, in order to map and characterize possible chemical residues of melanin pigments. Results show that trace metals, such as copper, are present in fossils as organometallic compounds most likely derived from original eumelanin. The distribution of these compounds provides a long-lived biomarker of melanin presence and density within a range of fossilized organisms. Metal zoning patterns may be preserved long after melanosome structures have been destroyed.

Infrared mapping resolves soft tissue preservation in 50 million year-old reptile skin.

Non-destructive Fourier Transform InfraRed (FTIR) mapping of Eocene aged fossil reptile skin shows that biological control on the distribution of endogenous organic components within fossilized soft tissue can be resolved. Mapped organic functional units within this approximately 50 Myr old specimen from the Green River Formation (USA) include amide and sulphur compounds. These compounds are most probably derived from the original beta keratin present in the skin because fossil leaf- and other non-skin-derived organic matter from the same geological formation do not show intense amide or thiol absorption bands. Maps and spectra from the fossil are directly comparable to extant reptile skin. Furthermore, infrared results are corroborated by several additional quantitative methods including Synchrotron Rapid Scanning X-Ray Fluorescence (SRS-XRF) and Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS). All results combine to clearly show that the organic compound inventory of the fossil skin is different from the embedding sedimentary matrix and fossil plant material. A new taphonomic model involving ternary complexation between keratin-derived organic molecules, divalent trace metals and silicate surfaces is presented to explain the survival of the observed compounds. X-ray diffraction shows that suitable minerals for complex formation are present. Previously, this study would only have been possible with major destructive sampling. Non-destructive FTIR imaging methods are thus shown to be a valuable tool for understanding the taphonomy of high-fidelity preservation, and furthermore, may provide insight into the biochemistry of extinct organisms.

Femur strength index predicts hip fracture independent of bone density and hip axis length.

INTRODUCTION: Proximal femoral bone strength is not only a function of femoral bone mineral density (BMD), but also a function of the spatial distribution of bone mass intrinsic in structural geometric properties such as diameter, area, length, and angle of the femoral neck. Recent advancements in bone density measurement include software that can automatically calculate a variety of femoral structural variables that may be related to hip fracture risk. The purpose of this study was to compare femoral bone density, structure, and strength assessments obtained from dual-energy X-ray absorbtiometry (DXA) measurements in a group of women with and without hip fracture. METHODS: DXA measurements of the proximal femur were obtained from 2,506 women 50 years of age or older, 365 with prior hip fracture and 2,141 controls. In addition to the conventional densitometry measurements, structural variables were determined using the Hip Strength Analysis program, including hip axis length (HAL), cross-sectional moment of inertia (CSMI), and the femur strength index (FSI) calculated as the ratio of estimated compressive yield strength of the femoral neck to the expected compressive stress of a fall on the greater trochanter. RESULTS: Femoral neck BMD was significantly lower and HAL significantly higher in the fracture group compared with controls. Mean CSMI was not significantly different between fracture patients and controls after adjustment for BMD and HAL. FSI, after adjustment for T score and HAL, was significantly lower in the fracture group, consistent with a reduced capacity to withstand a fall without fracturing a hip. CONCLUSION: We conclude that BMD, HAL, and FSI are significant independent predictors of hip fracture.

Evaluation of differences between fan-beam and pencil-beam densitometers.

We compared the bone and body composition results in vivo on two bone densitometers using fan-beam geometry (EXPERT and PRODIGY) with those using pencil-beam geometry (DPX). Measurements were made on large groups of adults ranging in weight from about 50 to 120 kg. Both spine and femur neck BMD on the fan-beam densitometers averaged within 1% of the pencil-beam results, and there was no magnitude dependence of the results by Bland-Altman analysis. Total body BMC and BMD on the PRODIGY and DPX were congruent, but on the EXPERT, BMC was about 2% lower and BMD 2% higher than corresponding values on the DPX. Soft-tissue composition was closely congruent for the PRODIGY and DPX; the comparable EXPERT-DPX differences showed greater scatter but no significant magnitude dependence. The smaller fan-angle of the PRODIGY (4 degrees ) probably contributed to its better congruence to pencil-beam results compared with the EXPERT (12 degrees ).

Bilateral measurement of femoral bone mineral density.

Both femora were measured on 61 normal adults using dual X-ray absorptiometry (DXA). In a subset of 31 subjects, each femur was scanned once using the conventional leg-positioning device supplied with the densitometer, and once using a new positioning device and software that allowed both legs to be measured simultaneously. In another subgroup (n = 30), subjects were measured three times using the new dual-femur approach to better assess precision error. The data were analyzed for differences owing to the different positioning devices and for differences between right and left sides. The correlation between results with the old and new positioners was high (r > 0.99, standard error of the estimate [SEE] = 0.01-0.02 g/cm(2)). There was no significant difference in the average bone mineral density (BMD) values between the old and new positioner. The precision errors for each femur alone with the dual-femur approach were similar to those reported for the single-femur scans (1 to 2%), but the precision errors for the combined femora were reduced by 30% as expected. The correlation between right and left sides was high (r = 0.94-0.96), and the SEE in predicting one side from the other was moderate for total, trochanteric, and femoral neck BMD (0.05, 0. 05, and 0.06 g/cm(2), respectively). These SEE equate to about 0.5 standard deviation in terms of T-score. Differences in many individual cases between the right and left sides were significantly greater than the precision error. The new dual-femur software and leg positioner allows rapid measurement and analysis of both femora, thereby eliminating the uncertainty between sides.

Bone density of the spine and femur in adult white females.

We measured bone mineral density (BMD in g/cm(2)) of the spine (L2-L4) and femur (four regions) in 1472 and 1487 cases, respectively, of ambulatory white women ages 20-79 years in the USA. A DPX densitometer was used in a mobile setting. The BMD values for women up to 69 years corresponded closely with published values for the USA, the UK, and northern Europe; our values were somewhat lower than those from other studies only in women over 70 years. The USA data were combined with data from Europe to give reference curves on about 12,000 subjects. Decreases of BMD with age in women below 50 years were much smaller than in older women (0.2% versus 0.6-1.0% per year). Femoral bone decreased from the neck region, but not the trochanter with age; the decrease of total femur BMD with age was due to loss from the former region. Loss of bone mineral content (BMC in g) from the femur neck and total femur region did not accelerate until after age 50 years, much like the spine. The apparent decrease of BMD in these regions that begins about age 40 actually is due to an increase of bone area. About 20% of USA women aged 50-79 years had BMD levels for the lumbar spine, or for the femur neck, more than -2.5 SD below the average values in young adult women 20-39 years old. Body weight had several times more impact on BMD than height, and in fact, a change of 1 kg in postmenopausal women was commensurate with the effect of a 1-year change in age. Subjects in the lowest quartile of body weight had T-scores that were 1 SD below those in the highest quartile.

A comparison of dual-energy X-ray absorptiometry and somatometrics for determining body fat in rhesus macaques.

OBJECTIVE: Various approaches have been used to assess fat and fat distribution in nonhuman primates, including measurements of body weight, body dimensions, and estimates derived from these, such as body mass index. Methods such as tritiated water dilution and dual-energy X-ray absorptiometry (DXA) have also been used. The aim of the present study was to evaluate and compare DXA measurements and somatometrics. RESEARCH METHODS AND PROCEDURES: Body composition of 15 adult male rhesus macaques was measured by DXA and somatometrics at four time-points over a 4-year period. Additionally, DXA precision and somatometric variability were analyzed by repeated measurements of the same subjects. RESULTS: DXA estimates of body fat were positively correlated with body weight, body mass index, body circumferences, and abdominal skinfold thicknesses. DXA assessments of soft tissue composition were precise, with coefficients of variation below 3.3% for all compartments analyzed. The majority of the observed variability in somatometrics was explained by subject variance, rather than by inter- or intraobserver variability, or by observer experience level. DISCUSSION: We conclude that noninvasive DXA technology provides precise estimates of nonhuman primate body composition that correlate well with the traditional somatometric measures used in primate studies.

Accuracy of imaging the menisci on an in-office, dedicated, magnetic resonance imaging extremity system.

Magnetic resonance imaging effectively defines and characterizes musculoskeletal pathologic lesions, particularly meniscal tears. Most studies comparing the efficacy of magnetic resonance imaging and arthroscopic evaluation have been performed on high-field (1.5-T) systems. The effectiveness of a low-field (0.2-T), dedicated, extremity magnetic resonance imaging device in diagnosing meniscal tears was studied prospectively on 35 patients with knee symptoms who subsequently had arthroscopic evaluation. Magnetic resonance imaging examinations were performed before surgery and were read by an experienced radiologist who was blinded to the results of the arthroscopic evaluations. Specificity was 100% for both the medial and lateral menisci. Sensitivity was 86% for the medial menisci, 89% for the lateral menisci, and 87% for both. Accuracy was 91% for the medial menisci, 97% for the lateral menisci, and 94% overall. The positive predictive values were 100% for the medial menisci, 100% for the lateral menisci, and 100% for both. The negative predictive values were 81% for the medial menisci, 96% for the lateral menisci, and 91% for both. The low-field magnetic resonance imaging system provided specificity and sensitivity that were equal to or better than previous reports with high-field systems. In particular, this low-field system eliminated the problem of false-positive results that has been found in some studies using high-field systems.

Age changes of spine density in posterior-anterior and lateral projections in normal women.

Bone mineral density (BMD) was measured in 353 healthy white women using dual-energy X-ray absorptiometry (DXA). Measurements were made of both the posterior-anterior (PA) and lateral spine, as well as the proximal femur (neck and Ward's triangle). From age 50 to 80 years, the BMD of the PA spine and femur neck BMD had an 18% diminution (0.6%/year), and BMD of the lateral spine showed about a 35-40% decline (1.4%/year). The Ward's triangle region of the femur was not quite as decreased (30% or 1.1%/year). The BMD decrease associated with aging did not differ as much among sites when expressed relative to the intrapopulation variation rather than as a percentage. The Z-score for PA spine and femur neck BMD (-1.1) was significantly different than that for lateral spine BMD (-1.6); Ward's triangle was intermediate (-1.3), i.e., the lateral spine still showed the highest sensitivity to aging. However, the ability to detect age changes in an individual subject can be increased only if the precision error for lateral spine BMD is not increased to a greater extent than the sensitivity.

Effect of tamoxifen on lumbar spine bone mineral density in postmenopausal women after 5 years.

BACKGROUND: Because adjuvant tamoxifen citrate is given to women with early-stage breast cancer for long periods, it is important to know how it affects risk factors for osteoporotic bone fractures, particularly since rates of bone fracture increase rapidly with age in postmenopausal women. In a 2-year randomized placebo-controlled toxicity study in 140 subjects, we demonstrated that tamoxifen was associated with preservation of bone mineral density (BMD), a major risk factor for fractures, in the lumbar spine. METHODS: Five years after entry on this study we reexamined 62 of the original subjects with lumbar spine BMD and serum osteocalcin measurements. These were women available for study because they had not suffered major illnesses and had continued to receive (1) tamoxifen or (2) the no-tamoxifen regimen that they had originally been randomized to receive for the entire 5 years. RESULTS: For lumbar spine BMD at baseline, the 30 subjects in the long-term tamoxifen group and the 32 subjects in the long-term no-tamoxifen group were not significantly different (P = .26). During the first 2 years of follow-up, the 30 subjects in the long-term tamoxifen group showed the same BMD pattern as the entire 70-patient tamoxifen cohort, and similarly the 32 subjects in the long-term no-tamoxifen group showed the same pattern as the entire 70-patient cohort who received placebo. Five-year mean BMD measurements for each long-term follow-up group showed no significant changes from their respective 2-year levels. However, 5-year BMD measurements between the two groups differed (tamoxifen group, +0.8%; placebo group, -0.7%) (P = .06), and the mean regression lines for the changes in BMD over 5 years differed significantly between the two groups (P = .0005). Adjustment for differences in body mass index, reported exercise, and calcium supplementation between these two groups did not change these results. Osteocalcin levels, also comparable at baseline in the two groups, were significantly lower in tamoxifen-treated subjects at 5 years (P = .0005). CONCLUSIONS: While remodeling of bone may be lower, resorption of lumbar spine bone mineral is also lower, and tamoxifen preserves BMD in the lumbar spine over 5 years of treatment in postmenopausal women. Over longer periods, this preservation of BMD might be expected to be associated with lower fracture rates.

Normalization of spine densitometry.

We investigated several transformations of bone mineral content (BMC) and area density (BMD), in particular volumetric density (BMAD), to ascertain the influence on (1) body size dependence, (2) diagnostic sensitivity, and (3) precision. These transformations were examined in a group of 657 normal postmenopausal women and 327 women with osteoporotic fracture. First, expression of results as BMAD removed some of the slight dependence on body size; 21% of the variation in BMC and 15% of the variation i BMD were associated with body weight, but only 8% with BMAD. Second, the Z scores compared with those for age-matched controls for BMD and BMC were -1.85 and -1.71, respectively; the Z score for BMAD was -1.64. Third, the precision error for BMC was reduced by expressing results as BMD (1.1 versus 0.5%); BMAD degraded precision slightly (0.7%). BMD appeared to be the optimal expression for bone densitometry because it provided the best diagnostic sensitivity and lowest precision error; there was a minimal influence of body size on BMD results. This study also showed that osteoporotic women, even in the first postmenopausal decade, had low spine BMD, small vertebral area, and low body weight. Such women may be particularly at risk of crush fracture.

A comparison of single photon and dual X-ray absorptiometry of the forearm in children and adults.

We compared single photon absorptiometry (SPA) to dual x-ray absorptiometry (DXA) for determination of bone mineral content (BMC), bone mineral density (BMD), and bone width (BW) of the forearm. The SPA and DXA measurements were done on the same subjects, using Lunar densitometers. The measurements were performed over the proximal radius (1/3 shaft) of the nondominant arm in 285 healthy, Caucasian females and males, ages 9-53. Correlation, linear, and split regression analyses for all subjects, and for subgroups (adults and children), were performed to compare SPA and DXA measurements. Corresponding measurements performed on two densitometers were highly correlated: r = 0.987, 0.975, and 0.943 for BMC, BMD, and BW, respectively. The corresponding measurements were also very similar in value, ranging from 0.9% to 4.1% difference, although they were different statistically. Correlations dropped slightly when subjects were separated into adult and children subgroups, and therefore, split regression analysis was performed resulting in R2 (adjusted) values of 97.6%, 95.5%, and 89.0% for BMC, BMD, and BW, respectively. Because the group indicator was statistically significant (p < 0.001) only for the BMC measurements but not for BMD and BW, linear regression of the whole sample was done as well. The difference in fitted values between the two regression methods was insignificant; therefore, we concluded that linear regression was sufficient for description of the relationship between SPA and DXA measurements. The precision study showed that the DXA had better reproducibility than SPA. The DXA precision in vivo (CV%) for BMC, BMD, and BW was 1.06, 0.83, and 0.95, respectively; and the SPA precision for same variables was 2.08, 2.12, and 0.95, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of tamoxifen on bone mineral density in postmenopausal women with breast cancer.

BACKGROUND AND METHODS: Tamoxifen, a synthetic antiestrogen, increases disease-free and overall survival when used as adjuvant therapy for primary breast cancer. Because it is given for long periods, it is important to know whether tamoxifen affects the skeleton, particularly since it is used extensively in postmenopausal women who are at risk for osteoporosis. Using photon absorptiometry, we studied the effects of tamoxifen on the bone mineral density of the lumbar spine and radius and on biochemical measures of bone metabolism in 140 postmenopausal women with axillary-node-negative breast cancer, in a two-year randomized, double-blind, placebo-controlled trial. RESULTS: In the women given tamoxifen, the mean bone mineral density of the lumbar spine increased by 0.61 percent per year, whereas in those given placebo it decreased by 1.00 percent per year (P less than 0.001). Radial bone mineral density decreased to the same extent in both groups. In a subgroup randomly selected from each group, serum osteocalcin and alkaline phosphatase concentrations decreased significantly in women given tamoxifen (P less than 0.001 for each variable), whereas serum parathyroid hormone and 1,25-dihydroxyvitamin D concentrations did not change significantly in either group. CONCLUSIONS: In postmenopausal women, treatment with tamoxifen is associated with preservation of the bone mineral density of the lumbar spine. Whether this favorable effect on bone mineral density is accompanied by a decrease in the risk of fractures remains to be determined.

DEXA measurement of spine density in the lateral projection. I: Methodology.

Bone mineral content and bone mineral density (BMC in g and BMD in g/cm2) were measured using dual-energy X-ray absorptiometry (DEXA). DEXA scans in the lateral decubitus position required about 12 minutes for the L2-L4 sequence at 0.75 mA (dose 5 mrem) and 4 minutes at 4.75 mA (7 mrem). The former scans were done with the Lunar DPX densitometer and the latter with the Lunar DPX-L. One test of the algorithms used for measurement is the equality of BMC in both AP and lateral projections. BMC in the lateral projection averaged about 1% lower than in the AP projection in phantoms and for L2 + L3 in 8 subjects, but the difference was not significant. Additional tests were done on the effects of tissue thickness and position from the tabletop. There was little or no influence of tissue thickness from 18 to 30 cm on BMD results, but there was a small influence of thickness below 18 cm (0.01 g/cm2; P = 0.01) and of distance from the tabletop at extremes of positioning (0.02 g/cm2; P = 0.06). The precision in vivo was similar for both 4- and 12-minute scans; the standard deviation of repeat measurements was about 0.02 g/cm2, which was about 2% relative to the mean BMD for a region within the vertebral body. The latter region included half the BMC of the body, or 24% of the entire vertebra. Results of 4-minute scans on the DPX and 12-minute scans on the DPX-L in 9 subjects were highly correlated (r = 0.98; P less than 0.001).

Bone densitometry of excised vertebrae; anatomical relationships.

Bone mineral density (BMD) was determined in 32 excised vertebrae using three methods: (1) dual-energy quantitative computed tomography (QCT), (2) dual-photon absorptiometry (DPA) with 153-Gd in an anteriorposterior projection and (3) scanning slit X-ray absorptiometry (SSXA) in both AP and lateral projections. The QCT region-of-interest in the anterior vertebral body had a lower density than that of the total trabecular portion of the body, but was highly correlated to this larger region (r = 0.96; SEE = 8 mg/cm3). The anterior QCT region also correlated moderately with BMD from DPA (r = 0.77; SEE = 18 mg/cm3). Measurements of the vertebral body in lateral projection were less well correlated (r = 0.5-0.7) to QCT densities. Both the anterior QCT region (r = 0.81; SEE = 18 mg/cm3) and the BMD from DPA (r = 0.86; SEE = 16 mg/cm3) and the BMD from DPA (r = 0.86; SEE = 16 mg/cm3) were similarly predictive of density of the integral vertebral body. Differences among densitometric methods on the spine depend on the projection used and the region examined.

Bone density in premenopausal women: effects of age, dietary intake, physical activity, smoking, and birth-control pills.

The effects of age, calcium, smoking, and physical activity on appendicular and axial bone mineral density (BMD) were evaluated in a 2-y study of 200-300 healthy young women aged 20-39 y. There was no cross-sectional change of BMD with age or longitudinal change with bone loss. No effect of birth-control pills on BMD was seen. There also was no association of calcium intake with BMD and/or with BMD changes. Current calcium intake was not a significant influence on BMD in this age group. Daily activity had no effect on BMD and there was no apparent additive interaction of activity and calcium intake on BMD. Smokers had significantly lower spine BMD and a tendency for lower BMD at other sites. Body weight was a better predictor of BMD than was any other factor. There was no association of BMD or BMD changes with both urinary calcium and hydroxyproline normalized for creatinine.

Interrelationships among bone densitometry sites in normal young women.

Interrelations among skeletal sites were examined in a population of up to 300 normal young white women aged 20-40 years. Measurements were done on the radius shaft, ultradistal radius, and ultradistal ulna using single-photon absorptiometry (SPA) and on the lumbar spine, proximal humerus, and proximal femur using dual-photon-absorptiometry (DPA). Because of the narrow range of intrapopulation variance in these normal young women, the intercorrelations among skeletal sites were not very high; the average correlation (r) was 0.43 for bone mineral content (BMC) and 0.45 for bone mineral density (BMD). The results at any one site predicted values at other sites with a standard error of estimate (SEE) of approximately 11% for BMD and 17% for BMC. Even in this relatively homogeneous sample, measurements at a single skeletal site could not be extrapolated to indicate skeletal status at other sites. BMC, and to a lesser extent BMD, were influenced by body size much as has been observed in both men and postmenopausal women. Bone results are preferably expressed as BMD, because (a) intrapopulation variability is lower (10% versus 15% for the lumbar spine), (b) intercorrelations among skeletal sites, and even among adjacent vertebrae, are higher for BMD, and (c) the influence of body size on BMD is lower (the average r for weight and BMD was 0.26 versus 0.33 for BMC).

Skeletal and body-composition effects of anorexia nervosa.

Eleven female patients (aged 18-46 y) with anorexia nervosa were measured by use of dual-photon absorptiometry for 1) bone mineral content (BMC, in g) and bone mineral density (BMD, in g/cm2) of the total skeleton and its regions, 2) BMD of the lumbar spine and the proximal femur, and 3) total body soft-tissue composition. The patients weighed 44.4 kg, approximately 15 kg less than normal peers (n = 22). The fat mass (3.35 kg) and content of soft tissue (7.8%) were four and three times lower (p less than 0.001) respectively, than those in normal women (15.1 kg and 26%, respectively). The total skeleton mineral (1921 g) was approximately 25% less than that of young normal women. The BMC as a fraction of the lean tissue mass was approximately 4.9% in the patients and 5.9% in normal women. Total body and femoral BMD averaged only 10% and 13% lower than those of normal women, respectively; however, spinal BMD was particularly reduced (approximately 25%, p less than 0.001).