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Query: UMLS:C0205700 (ash)
 15,125 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mutagenicity of refuse leachate from a municipal incinerator was studied by liquid rec-assay and Ames assay. Volatile components were found to be negative, and nonvolatile components positive, in the Ames assay and the leachate was found to have DNA-damaging capacity in the liquid rec-assay with S-9 mix. PAHs derived from tobacco ash and carbonyl compounds generated by the putrefaction of foods were confirmed to be main contributors to DNA-damaging capacity and mutagenicity in refuse leachate.
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PMID:The mutagenicity of refuse leachate from a municipal incinerator. 249 17

A safe, non-invasive method for the accurate measurement of bone mineral content in the third metacarpal bone of the horse is described. The technique involves scanning the bone with a single photon beam from an Americium-241 source. Data were obtained from the excised metacarpal bones from both forelimbs of 50 normal and seven lame horses. Measurements were made in vivo on eight normal and seven lame horses and on one experimental horse with osteopenia induced by partial weightlessness in a flotation tank. In the normal horses bone mineral content altered with age, particularly in the first six months of life. There were also differences according to the site of scanning on the metacarpus. The contribution of the splint bones to the total bone mineral content was less than 2 per cent distal to the mid-point of the metacarpus, but in the proximal shaft it increased to 12 per cent. No significant differences were noted either between right and left limbs, or between male and female animals. A reduction in bone mineral content was demonstrated in the affected leg of horses with chronic lameness and with osteopenia induced by weightlessness. The bone mineral content (g/cm) correlated well with the ash content (mg/100 mg dry bone weight), the specific gravity and the apparent transverse velocity of ultrasound (m/sec) through the bone. A measure of bone mineral density (g/cm3) was calculated from the bone mineral content and cross sectional area of the bone to overcome the individual differences in size of the metacarpus.
Vet Rec 1986 May 03
PMID:Single photon absorptiometry for the measurement of bone mineral content in horses. 371 34

Arbitrary age limits and offal weights are often used to classify meat and offals from 'bobby' calves as 'immature' and hence unfit for human consumption. Such age limits were not scientifically validated in a comparative study of the ante mortem characteristics, and the physical characteristics of the carcases and offals of groups of Jersey calves aged one, five, 14 and 21 days. The quality characteristics of muscle (pH and water-holding capacity) did not change with increasing age, and the changes in chemical composition (water, protein, fat and ash) were minimal, particularly between the five-day-old and 21-day-old groups. Small changes in muscle colour measured objectively were not detectable visually.
Vet Rec 1993 May 29
PMID:Characteristics of the carcases and meat of slaughtered calves as indicators of 'immaturity'. 833 16

The pathological alterations of enamel structure in the teeth of wild boars from fluoride polluted areas in N-Bohemia (Czech Republic) and S-Saxony (Germany) were studied on a macroscopic and a microscopic level. Mandibular bone fluoride concentration (mg F(-)/kg, dry wt; mean +/-SD, individuals <24 months of age) in the specimens from N-Bohemia (754.3+/-149.6) and S-Saxony (490.8+/-135.1) was significantly higher than that of controls (free of dental fluorosis), originating from the western part of Germany (304.7+/-91.0). Fluoride content in bulk enamel (mg F(-)/kg, ash wt) of fluorotic permanent teeth from N-Bohemia (382.1+/-165.2) and S-Saxony (125.0+/-38.3) was likewise significantly increased over that of non-fluorotic control teeth from W-Germany (33.6+/-26.7). Macroscopically, fluorosed wild boar enamel exhibited opacity and discoloration of varying extent, accentuated perikymata as well as hypoplastic and posteruptive surface defects. Microradiographic and scanning electron microscopic analyses revealed enamel subsurface hypomineralization, accentuated Retzius lines and occurrence of broad, hypomineralized incremental bands of abnormal structure underlying hypoplastic enamel surface defects. The presence of zones of aprismatic enamel was associated with these bands. Incremental bands with altered enamel structure and enamel surface hypoplasias, both denoting a severe disturbance during the secretory stage of amelogenesis, have previously been observed in rodents following acute parenteral fluoride dosing. It is concluded that in the chronically fluoride exposed wild boars periods of especially elevated plasma fluoride levels exerted an acute toxic effect on the secretory ameloblasts. A feature not previously reported from fluorosed enamel was the occurrence of canal-like structures that originated at the broad incremental bands and extended into the external enamel. The presence of these canals presumably results from a delay in the resumption of secretory activity by groups of ameloblasts following a fluoride insult. Based on experimental evidence in domestic pigs and in sheep, the overall subsurface hypomineralization of fluorosed wild boar enamel is attributed to a disturbance of enamel maturation. The distribution of fluorotic enamel changes within the dentition of the wild boars could be related to the developmental sequence of tooth formation in the species. Teeth whose crown formation took place prenatally (deciduous teeth) or largely pre-weaning (permanent first molars) exhibited no or only moderate fluorotic enamel alterations. Based on the extension of enamel surface hypoplasias along the coronoapical axes of the tooth crowns, the timing of excess fluoride exposure that caused a marked disruption of enamel matrix secretion was estimated in specimens with a known date of death. The results indicate that the wild boars had been exposed to a particularly severe fluoride impact during autumn and winter of their first year of life.
Anat Rec 2000 05 01
PMID:Disturbed enamel formation in wild boars (Sus scrofa L.) from fluoride polluted areas in Central Europe. 1076 Jul 39

The artiodactyl (mule deer) calcaneus was examined for structural and material features that represent regional differences in cortical bone modeling and remodeling activities. Cortical thickness, resorption and formation surfaces, mineral content (percent ash), and microstructure were quantified between and within skeletally immature and mature bones. These features were examined to see if they are consistent with predictions of Frost's Mechanostat paradigm of mechanically induced bone adaptation in a maturing "tension/compression" bone (Frost, 1990a,b, Anat Rec 226:403-413, 414-422). Consistent with Frost's hypothesis that surface modeling activities differ between the "compression" (cranial) and "tension" (caudal) cortices, the elliptical cross-section of the calcaneal diaphysis becomes more elongated in the direction of bending as a result of preferential (> 95%) increase in thickness of the compression cortex. Regional differences in mineral content and population densities of new remodeling events (NREs = resorption spaces plus newly forming secondary osteons) support Frost's hypothesis that intracortical remodeling activities differ between the opposing cortices: 1.) in immature and mature bones, the compression cortex had attained a level of mineralization averaging 8.9 and 6.8% greater (P < 0.001), respectively, than that of the tension cortex, and 2.) there are on average 350 to 400% greater population densities of NREs in the tension cortices of both age groups (P < 0.0003). No significant differences in cortical thickness, mineral content, porosity, or NREs were found between medial and lateral cortices of the skeletally mature bones, suggesting that no modeling or remodeling differences exist along a theoretical neutral axis. However, in mature bones these cortices differed considerably in secondary osteon cross-sectional area and population density. Consistent with Frost's hypothesis, remodeling in the compression cortex produced bone with microstructural organization that differs from the tension cortex. However, the increased remodeling activity of the tension cortex does not appear to be related to a postulated low-strain environment. Although most findings are consistent with predictions of Frost's Mechanostat paradigm, there are several notable inconsistencies. Additional studies are needed to elucidate the nature of the mechanisms that govern the modeling and remodeling activities that produce and maintain normal bone. It is proposed that the artiodactyl calcaneus will provide a useful experimental model for these studies.
Anat Rec 2001 06 01
PMID:Modeling and remodeling in a developing artiodactyl calcaneus: a model for evaluating Frost's Mechanostat hypothesis and its corollaries. 1136 Feb 34

Even though the cranial vault functions as protection for the brain and as a support structure for facial and masticatory functions, little is known about its mechanical properties or their variations. The cranial vault bone is interesting because of its maintenance in spite of low functional strains, and because calvarial bone cells are often used in cell culture studies. We measured thickness, density, and ash weight, and ultrasonically determined elastic properties throughout the cortices of 10 human parietal bones. The results are unique for studies of the cranial vault because: 1) measurements focused specifically on the cortical components, 2) the orientations of the axes of maximum stiffness were determined before measurement of elastic properties, and 3) two related measurements (bone density and percent ash weight) were compared. Results showed that the periosteal cortical plate (outer table) and the endosteal cortical plate (inner table) had significant differences in material properties. The outer table was on average thicker, denser, and stiffer than the inner table, which had a higher ash weight percentage. Within each table there were significant differences in thicknesses, ash weight percentages, and E(2)/E(3) anisotropies among sites. Few sites on either table had significant orientations of the axes of maximum stiffness. Despite this apparent randomness in orientation, almost all sites exhibited anisotropies equivalent to other parts of the skeleton.
Anat Rec 2002 Sep 01
PMID:Material properties of the inner and outer cortical tables of the human parietal bone. 1220 60

Although there is extensive documentation in the literature regarding the importance of trabecular bone for proximal femoral integrity and fracture resistance, there remain gaps in our understanding of the basic mineral changes that may occur in trabecular bone attributable to aging. It is unclear what age-related changes take place in the trabecular bone of the proximal femur, a common fracture site in the elderly. It has been suggested that some explanation for conflicting reports on cancellous bone may be found at a microscopic level. The goal of this study was to document age-related changes in micromineralization in the proximal femur of Caucasian females using backscattered electron imaging technology. Proximal femurs were obtained from 11 young and 11 elderly females. Sections of bone from the superior and inferior neck and superior and inferior trochanter were analyzed in a scanning electron microscope using the backscatter technique to determine ash percent. Mean ash percent did not change with age in any of the four regions (P > 0.05). However, while the mean ash percent did not change, there was a dramatic increase in variability elderly age group and loss of mineral heterogeneity. This indicates that there are subpopulations with higher or lower ash percents than the mean in the elderly study group in this investigation. While variance changed dramatically, variance within individuals did not change significantly with age (P > 0.05). The results of this study suggest that changes in micromineralization may occur within an individual, adding a possible new dimension to our understanding of fracture risk in the elderly. Future studies should examine a longer population base to confirm this observation.
Anat Rec A Discov Mol Cell Evol Biol 2004 Dec
PMID:Age-related mineralization heterogeneity changes in trabecular bone of the proximal femur. 1538 75

Experimental models are needed for resolving relative influences of genetic, epigenetic, and nonheritable functionally induced (extragenetic) factors in the emergence of developmental adaptations in limb bones of larger mammals. We examined regional/ontogenetic morphologic variations in sheep calcanei, which exhibit marked heterogeneity in structural and material organization by skeletal maturity. Cross-sections and lateral radiographs of an ontogenetic series of domesticated sheep calcanei (fetal to adult) were examined for variations in biomechanically important structural (cortical thickness and trabecular architecture) and material (percent ash and predominant collagen fiber orientation) characteristics. Results showed delayed development of variations in cortical thickness and collagen fiber orientation, which correlate with extragenetic factors, including compression/tension strains of habitual bending in respective dorsal/plantar cortices and load-related thresholds for modeling/remodeling activities. In contrast, the appearance of trabecular arches in utero suggests strong genetic/epigenetic influences. These stark spatial/temporal variations in sheep calcanei provide a compelling model for investigating causal mechanisms that mediate this construction. In view of these findings, it is also suggested that the conventional distinction between genetic and epigenetic factors in limb bone development be expanded into three categories: genetic, epigenetic, and extragenetic factors.
Anat Rec (Hoboken) 2007 Mar
PMID:Ontogenetic structural and material variations in ovine calcanei: a model for interpreting bone adaptation. 1752 44

Recent evidence has shown that mice deficient in the NPY Y2 receptor have an increase in trabecular bone volume as well as cortical bone mass due to increased osteoblast activity. However, the mechanical phenotype of Y2 -/- bone has not yet been assessed. Thus, the aim of the present study was to examine the effect of Y2 deletion on murine cortical bone structural behavior, as well as to assess the material and geometric contributions to that behavior. The results of this study indicate that Y2 -/- mice on a 129 SV x Balb/c background strain are smaller in body mass and have smaller bones than wild-type controls. As expected based on smaller bone cross-sectional properties, cortical bone structural strength was lower in -/- animals. Surprisingly, the structural stiffness of -/- bones was comparable to that of +/+ bones despite their smaller cross-sectional geometry. Comparable structural stiffness appeared to be achieved by means of an elevated effective shear modulus, which was associated with a small, but statistically significant, higher ash content in Y2 -/- bones. These data represent the first comprehensive characterization of the effect of Y2 deletion on cortical bone structural and material behavior to date.
Anat Rec (Hoboken) 2008 Jan
PMID:Effect of y2 receptor deletion on whole bone structural behavior in mice. 1808 6

The objective of this study was to examine the effects of production (the number and weight of pigs produced over a lifetime) on the physical and mechanical properties of the metacarpals of cull sows, the prevalence of osteochondrosis and conformation traits. Metacarpals (n=79) and forelimbs (n=36) from cull sows were collected at slaughter. Bones were CT scanned for cross-sectional area and moment of inertia. Cylindrical sections from the diaphysis were used for mechanical testing and for calculating bone strength indices. The value of elastic (Young's) modulus, dry bone ash percentage, apparent bone density and bone mineral density did not decrease with the parity of the sows. Osteochondrosis was found in all the sows. The most severe lesions were in the medial condyle of the humerus and the anconeal process of the ulna. No relationship was found between lameness and joint pathology.
Vet Rec 2010 Feb 27
PMID:Survey of cull sow bone and joint integrity in the Moorepark Research Farm herd. 2019 Feb 17


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