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PubMed2003

Causal attributions of Ghanaian industrial workers for accident occurrence: miners and non-miners perspective.

PROBLEM: Reports from the accident literature indicate that accident rates tend to vary with type of occupation. The mining industry has been recorded as the most dangerous with a high disabling injury rate. This observation has been attributed to the extremely stressful conditions under which miners work. Besides, the intimidating work environment in the mines has been insinuated to invoke a sense of helplessness, fatalism and hence defensive causal attributions for accident occurrences. METHOD: This study compared causal attributions between accident victims in Ghana's mining industry with their counterparts in textile factories. T values and Chi-square were employed to test for statistically significant differences between the two groups of accident victims. RESULTS: Findings indicate that there is no difference between the causal attributions for miners and non-miners. IMPACT ON INDUSTRY: Accident frequency and occupational type have no impact on causal attributions.

Accidents, Occupational↗
PubMed1997

Composition of cartilagenous tissue with mineralized and non-mineralized zones formed in vitro.

We have previously shown that cartilagenous tissue with both non-mineralized and mineralized zones can be formed by chondrocytes which have been selectively isolated from the deep zone of bovine articular cartilage. In this study, we quantitate proteoglycan and collagen content, calcification, tissue thickness and cellularity over a 10 week culture period in order to study matrix accumulation and tissue formation. The cartilagenous tissue cellularity and proteoglycan and collagen accumulation continued up to 8 weeks and this was paralleled by an increase in tissue thickness. The amount of mineral in the tissue as well as the amount of collagen, in contrast to proteoglycan, was still increasing at 10 weeks. At the end of week 10, the amount of glycosaminoglycan and collagen as a percentage of dry weight of the tissue were 11.0 +/- 0.6% and 14.8 +/- 0.1%, respectively, compared with 10.5 +/- 1.2% and 35.1 +/- 5.8% for the in vitro deep articular cartilage. The amount of calcium as a percentage of dry weight of the cartilagenous tissue was 8.1 +/- 0.7% which was similar to the in vivo cartilage (9.1 +/- 1.6%). This data suggests that 8 weeks of culture may be necessary before the cartilagenous tissue is suitable for use as a transplant.

Animals↗
PubMed1995

Correlation of total-body bone mineral content determined by dual-energy X-ray absorptiometry with bone mineral density determined by peripheral quantitative computed tomography.

RATIONALE AND OBJECTIVES: We sought to determine the value of peripheral quantitative computed tomography (pQCT) in measuring bone mineral density. METHODS: In 50 healthy, eugonodal premenopausal women, we correlated measurements of total bone mineral content (BMCTB), made with dual-energy X-ray absorptiometry (DXA), and bone mineral density, determined by pQCT. RESULTS: The partial correlations, adjusted for weight and age, between BMCTB and cortical bone density, total bone density, and trabecular bone density were .71 (p < .0001), .63 (p < .0001), and .32 (p < .05), respectively. CONCLUSION: These results and the advantages of pQCT--providing precise bone density determinations for trabecular and compact bone separately, having a high spatial resolution that allows a "compartmental" analysis of bone structure, having a low coefficient of variation, and having a minimal radiation dose (< 5 mrem)--confirm the adequacy of using this method for bone mass studies.

Absorptiometry, Photon↗
PubMed1996

The serum protein alpha2-HS glycoprotein/fetuin inhibits apatite formation in vitro and in mineralizing calvaria cells. A possible role in mineralization and calcium homeostasis.

We present data suggesting a function of alpha2-HS glycoproteins/fetuins in serum and in mineralization, namely interference with calcium salt precipitation. Fetuins occur in high serum concentration during fetal life. They accumulate in bones and teeth as a major fraction of noncollagenous bone proteins. The expression pattern in fetal mice confirms that fetuin is predominantly made in the liver and is accumulated in the mineralized matrix of bones. We arrived at a hypothesis on the molecular basis of fetuin function in bones using primary rat calvaria osteoblast cultures and salt precipitation assays. Our results indicate that fetuins inhibit apatite formation both in cell culture and in the test tube. This inhibitory effect is mediated by acidic amino acids clustering in cystatin-like domain D1. Fetuins account for roughly half of the capacity of serum to inhibit salt precipitation. We propose that fetuins inhibit phase separation in serum and modulate apatite formation during mineralization.

Animals↗
PubMed2002

Soy isoflavones: no effects on bone mineral content and bone mineral density in healthy, menstruating young adult women after one year.

BACKGROUND: The effects of isoflavone-enriched soy protein on human bone mineral content (mass) and density in healthy, menstruating young adult females have not been examined in a comparative prospective investigation. Peri- and post-menopausal women have been reported to show beneficial effects of isoflavones on bone measurements. Therefore, young women may also be able to improve their accrual of peak bone mineral content (BMC) and bone mineral density (BMD) during the early adult years of bone consolidation with an isoflavone-enriched diet. OBJECTIVES: In this controlled, double-blind intervention, we tested the hypothesis that an isoflavone-rich soy protein diet increases BMC and BMD in young adult females over a period of one year in comparison to a control group receiving soy protein that has isoflavones removed. DESIGN: Young healthy women of any ethnic background, 21 to 25 years of age, were divided into two groups, placebo (n = 13) and supplement (n = 15). The soy protein supplement was enriched with isoflavones ( approximately 90 mg of total isoflavones/day), whereas the control protein diet was isoflavone-deficient, even though it contained the same amount of soy protein and other ingredients as the isoflavone-rich diet. Dual-energy x-ray absorptiometric (DXA) measurements of BMC and BMD were made at baseline and at 6 and 12 months. DXA estimates of body composition, including fat mass and lean body mass, were generated from whole-body BMC measurements. BMI was calculated as weight (kg) over height (m) squared. Physical activity was assessed, and three-day dietary records were taken at entry (baseline) and at 6 and 12 months. RESULTS: No changes in BMD after 12 months were found in either the isoflavone-treated (treatment) group or the isoflavone-deficient (control) group. Other variables also remained essentially constant over the 12-month period, including normal menstrual patterns in both the treatment and control groups. CONCLUSIONS: The isoflavone-rich soy preparation had no effects on BMC and BMD over a 12-month period in young healthy adult females with normal menses. An isoflavone-rich supplement appears to have little or no effect on bone in young adult women with normal ovarian function, at least over this 12-month study period.

Absorptiometry, Photon↗
PubMed1992

Effects of dietary protein deficiency on mineral metabolism and bone mineral density.

The effects of dietary protein restriction on mineral and bone metabolism are uncharacterized. We studied growing rats fed a diet low in protein (5%) for 4, 6, and 8 wks (n = 10 animals/group) and compared them with animals pair-fed with a protein-replete (18%) diet. The low-protein diet rapidly induced a profound hypocalciuria that persisted for greater than or equal to 8 wk. Serum calcium and phosphorus concentrations were not affected but serum total and free 25-dihydroxyvitamin D concentrations as well as gastrointestinal calcium absorption were lower in the low-protein animals. Skeletal dimensions were reduced in the protein-deprived rats but there were no significant differences in bone mineral content between control and low-protein animals at 4, 6, and 8 wks. Hence, dietary protein deprivation resulted in slower growth but bone mineral density was maintained when there was a marked reduction in urinary calcium excretion.

Animals↗
PubMed1994

Uncritical use of bone mineral density in absorptiometry may lead to size-related artifacts in the identification of bone mineral determinants.

Epidemiological studies of bone mineral determinants rely heavily on measurements made with absorptiometric techniques such as single-photon absorptiometry and dual-energy x-ray absorptiometry. In general, absorptiometric data are expressed as areal densities (bone mineral density, BMD), obtained by dividing bone mineral content (BMC) by bone area or width (BA, BW). This size correction assumes that BMC and BA (BW) are directly proportional to one another, such that a 1% change in BA (BW) is matched by a 1% change in BMC. This is rarely the case, and the exact relationship depends on the population group, skeletal site, body size, instrumentation, and scanning conditions. Size adjustment determined by using predefined indexes, such as BMD and body mass index (BMI, wt/ht2), may fail to correct BMC fully for bone and body size, and may lead to spurious associations with other size-related variables such as calcium intake, energy expenditure, and grip strength. A general approach to size adjustment is described, in which BA (BW), weight, and height are incorporated in all regression models of BMC. Although BMD plays a valuable role in fracture-risk assessment and clinical management, we advocate that its use in epidemiological research be discontinued.

Absorptiometry, Photon↗
PubMed2006

Co-operative mineralization and protein self-assembly in amelogenesis: silica mineralization and assembly of recombinant amelogenins in vitro.

An amorphous silica mineralization technique was used to produce inorganic/protein composites to elucidate the structure and mechanism of formation of amelogenin assemblies, which may play an important role in regulating enamel structure during the initial stages of amelogenesis. Full-length recombinant amelogenins from mouse (rM179) and pig (rP172) were investigated along with key degradation products (rM166 and native P148) lacking the hydrophilic C terminus found in parent molecules. The resulting products were examined using transmission electron microscopy and/or small-angle X-ray scattering. Using protein concentrations of 0.1-3 mg ml-1, large monodisperse spheres of remarkably similar mean diameters were observed using rM179 (124+/-4 nm) and rP172 (126+/-7 nm). These spheres also exhibited 'internal structure', comprising nearly spherical monodisperse particles of approximately 20 nm in diameter. In the presence of rM166, P148, and bovine serum albumin (control), large unstructured and randomly shaped particles (250-1000 nm) were observed. Without added protein, large dense spherical particles of silica (mean approximately 500 nm) lacking internal structure were produced. These findings demonstrate that full-length amelogenins have the ability to form higher-order structures, whereas amelogenins that lack the hydrophilic C terminus do not. The results also suggest that full-length amelogenin can guide the formation of organized mineralized structures through co-operative interactions between assembling protein and forming mineral.

Amelogenesis↗
PubMedDate not supplied

Effect of underground working on vitamin D levels and bone mineral densities in coal miners: a controlled study.

The aim of this study was to determine the effect of underground working on 25-hydroxyvitamin D (25-OHD) levels and bone mineral density (BMD) values in coal miners. Fifty coal miners working underground and 50 surface workers as controls, matched for age and body mass index, from Zonguldak, Turkey, were recruited to the study. Levels of 25-OHD, biochemical bone markers, and lumbar spine and femur BMD values were measured in all study participants. Lumbar spine and femur BMD values were significantly higher in underground workers compared with surface workers, but there was no significant difference in 25-OHD levels between the two groups. Duration of underground working, age, 25-OHD levels, cigarette consumption and dietary calcium intake were not correlated with BMD values. Underground physical working does not seem to be a significant risk factor for low 25-OHD levels or low BMD values.

Adult↗
PubMed1999

A six-year longitudinal study of the relationship of physical activity to bone mineral accrual in growing children: the university of Saskatchewan bone mineral accrual study.

To investigate the influence of physical activity on bone mineral accrual during the adolescent years, we analyzed 6 years of data from 53 girls and 60 boys. Physical activity, dietary intakes, and anthropometry were measured every 6 months and dual-energy X-ray absorptiometry scans of the total body (TB), lumbar spine (LS), and proximal femur (Hologic 2000, array mode) were collected annually. Distance and velocity curves for height and bone mineral content (BMC) were fitted for each child at several skeletal sites using a cubic spline procedure, from which ages at peak height velocity (PHV) and peak BMC velocity (PBMCV) were identified. A mean age- and gender-specific standardized activity (Z) score was calculated for each subject based on multiple yearly activity assessments collected up until age of PHV. This score was used to identify active (top quartile), average (middle 2 quartiles), or inactive (bottom quartile) groups. Two-way analysis of covariance, with height and weight at PHV controlled for, demonstrated significant physical activity and gender main effects (but no interaction) for PBMCV, for BMC accrued for 2 years around peak velocity, and for BMC at 1 year post-PBMCV for the TB and femoral neck and for physical activity but not gender at the LS (all p < 0.05). Controlling for maturational and size differences between groups, we noted a 9% and 17% greater TB BMC for active boys and girls, respectively, over their inactive peers 1 year after the age of PBMCV. We also estimated that, on average, 26% of adult TB bone mineral was accrued during the 2 years around PBMCV.

Absorptiometry, Photon↗
PubMed2000

Bone mineral metabolism, bone mineral density, and body composition in patients with chronic pancreatitis and pancreatic exocrine insufficiency.

BACKGROUND: Calcium and vitamin D homeostasis seem to be abnormal in patients with exocrine pancreatic dysfunction resulting from cystic fibrosis. Only a few studies have evaluated and described bone mineral metabolism in patients with chronic pancreatitis and pancreatic insufficiency. METHODS: Thirty-two patients with chronic pancreatitis and residual exocrine pancreatic function (group 1) and 26 patients with pancreatic exocrine insufficiency (i.e., meal-stimulated intraduodenal lipase <10% of lowest normal range and steatorrhea) (group 2) were studied. Serum levels of total calcium, phosphate, 25 (OH)D, 1.25(OH)2D, alkaline phosphatase, and parathyroid hormone were measured. Bone mineral density (BMD), bone mineral content (BMC), lean body mass (LBM), and fat mass (FM) were measured using a dual-energy X-ray absorptiometry (DXA) scanner. RESULTS: Alcohol was a causative factor in 79% of the patients. Fifty-six percent in group 1 and 69% in group 2 had Z-scores of the BMD < -1. The mean Z-score was -1.16 +/- 1.29 in group 1 and -1.32 +/- 0.90 in group 2. The mean Z-score of the BMC was -1.02 +/- 1.17 vs -1.39 +/- 0.987. In both groups mean 25 (OH)D and mean 1.25(OH)2D were below reference range. Plasma concentrations of albumin-corrected calcium, alkaline phosphatase, and parathyroid hormone were in the upper range of the reference range. Mean Z-scores of LBM were -0.69 +/- 1.34 in group 1 vs -1.01 +/- 1.12 in group 2 and Z-scores of FM were -0.27 +/- 1.70 in group 1 vs -0.95 +/- 1.01 in group 2 (p <0.05). CONCLUSION: Patients with chronic pancreatitis, in particular patients with advanced disease and steatorrhea, are at risk of developing significant bone loss. Despite normal body mass index the patients are characterized by loss of lean body mass and fat mass. The present study shows that these patients have decreased serum levels of vitamin D metabolites and low bone mass.

Adult↗
PubMed2005

Effect of prepubertal ovariohysterectomy on bone mineral density and bone mineral content in puppies.

In this study, dual energy X-ray absorptiometry (DXA) was performed on the calcaneus (CAL) and accessory carpal bone (ACB) of early-age neutered (n = 11) and sham-operated puppies (n = 10) to investigate changes in bone mineral density (BMD) and bone mineral content (BMC) over time. Prepubertal ovariohysterectomy and sham surgery were performed at 10 weeks, while BMD and BMC were measured at 12, 16, 20 and 24 weeks of age. BMD and BMC of CAL and ACB of ovariohysterectomised puppies were found to be higher. The differences between the groups were statistically unimportant; however, the fourth measurement of the ACB showed a significant (P < 0.05) difference. Sexually intact puppies weighed less than gonadectomised puppies in all measurements. Because of the positive correlations between body weight and bone mineral density, BMD and BMC of early-age neutered puppies were found to be higher. These results suggest that BMD and BMC are not affected by prepubertal ovariohysterectomy until six months of age in mixed-breed puppies.

Animals↗
PubMed1997

Biochemical bone markers, bone mineral content, and bone mineral density in rats with experimental nephrotic syndrome.

The human nephrotic syndrome (NS) is accompanied by important alterations of mineral and bone metabolism. The purpose of the present study was to examine bone metabolism in rats with experimental NS and normal creatinine clearance, and to evaluate the reversibility of this alteration. NS was induced by three injections of puromycin aminonucleoside (PAN) on days 0, 21, and 35 (10, 5, and 5 mg/100 g body weight, respectively). The biochemical markers of bone formation (osteocalcin and alkaline phosphatase) and bone resorption (hydroxyproline and pyridinoline), bone mineral content (BMC), and bone mineral density (BMD), determined by dual-energy x-ray absorptiometry (DEXA), were studied on days 0, 7, 14, 28, 42, 56, 84, and 112. Proteinuria was present throughout the study. Hypoproteinemia was seen on days 7, 28, 42, and 56, returning to control values on days 84 and 112. In serum, osteocalcin (OC) concentration increased (p < 0.001), and alkaline phosphatase (ALP) decreased (p = 0.002). In urine, hydroxyproline increased (p < 0.001), but urinary pyridinoline was not different from the control group throughout the study. Increased serum parathyroid hormone concentration and decreased levels of 25-hydroxy and 1,25-dihydroxyvitamin D were found from day 7. During the intense proteinuria, bone resorption predominates and decreased BMC and BMD ensues in PAN-nephrotic rats. PAN-nephrotic rats showed low BMC and BMD compared to control group (p < 0.001). At the end of the study, when proteinuria persisted but total serum protein returned to control values, the biochemical bone markers, BMC, and BMD returned to normal. In conclusion, PAN-nephrotic rats had reversible bone alterations that were related to the magnitude of proteinuria and the concentration of total serum protein.

Alkaline Phosphatase↗
PubMed1999

German uranium miner study--pathological and molecular genetic findings. German Uranium Miner Study, Research Group Pathology.

Uranium miners of the former Wismut company in Germany form the largest cohort of workers exposed to (222)Rn and dust in the world. The German Uranium Miner Study, Research Group Pathology, is evaluating the central pathology archive of the Wismut company. The main tasks of our study are pathological-anatomical and molecular genetic investigations of 28,975 autopsy cases and the evaluation of mining pollutants in the lungs by neutron activation analysis. As part of an observer agreement study, lung tumors are classified according to the WHO/IASLC classification and nontumorigenic lung disorders are registered. Lung tumors were analyzed for the presence of a proposed radon-specific mutation in the TP53 gene (formerly known as p53). Interim results are: (a) In the years 1957 to 1965, a high rate (69%) of small cell carcinomas was found which had declined to 34% by 1990. (b) The percentage of the deceased who suffered from silicosis is not higher in the group of lung tumors than in other tumor groups or the nontumor group. (c) The hypothesis of a radon-characteristic hotspot mutation in the TP53 tumor suppressor gene is not supported by our investigations. (d) Neutron activation analysis demonstrates that uranium, arsenic, chromium, cobalt and antimony can be found in tissue samples from the miners even when they had stopped working more than 20 years before death.

Genes, p53↗
PubMed1999

Measurements of bone mineral density. Mineral density in metabolic bone disease.

Bone metabolism and thus bone remodelling and bone mineral content are profoundly influenced by many hormonal and metabolic factors. This review presents the state of the art procedures for bone mineral absorptiometry and examines the interactions of endocrine and metabolic diseases and bone mineral content. Preventive and therapeutic modalities of osteoporosis are discussed in this context.

Bone Density↗
PubMed2000

[Bone mineral density and bone mineral content variations in various communities].

OBJECTIVE: To study the bone mineral density (DMO) and the bone mineral concentration (CMO) in lumbar spine (L2 and L4) by dual-energy x-ray absorptiometry with a lunar DPX (DEXA) in a children sample of the community of Madrid; to relate the values obtained with the age, sex and pubertal development; and to compare the values of DMO found with the publications of other autonomous communities. MATERIALS AND METHODS: 351 children, 184 boys and 167 girls selected at random in our environment. The age range oscillated between 6 months and 20 years. Grouped in intervals of a year according to the sex; and in accordance with the pubertal development. The bone mineral content was measured by dual-energy x-ray absorptiometry with a lunar DPX in the lumbar spine at level of L2-L4. The statistic analysis has been accomplished with the SPSS version 6.0.1. They have been obtained the average and deviation standard for each group from studied age, and also according to pubertal development; the DMO and CMO of the boys and girls have been compared by groups of age; the DMO and CMO within each sex between a group of age and the immediately superior have been compared through an analysis of the variance; the effect that the age has on the DMO and the CMO has been evaluated and finally through multivariant analysis techniques the regression models have been estimated between the age and the DMO, and the age with the CMO. CONCLUSION: The DMO shows variations between the various communities and even in different samples of a same community, in Carrascosa study the DMO is highest, expressed in SD score, in many several groups of age studied with respect to our values and with the values of Moreno et al and Armadá et al; the values of DMO in our study are greater than the ones found by Moreno et al and Armadá et al; the first four years and the adolescence are the periods of maximum increase of the DMO, but it also increases in an oscillatory way in the intermediate stages; the girls present some highest levels of DMO in the groups of age of 12-13 and 14-15 years, probably in relationship to a most precocious beginning of the puberty; and finally the regression line of the DMO as compared to the age for both sexes are parallel and have equal court point, what means that they are coincident.

Absorptiometry, Photon↗
PubMed1999

An overview of vertebrate mineralization with emphasis on collagen-mineral interaction.

The nucleation, growth, and development of mineral crystals through their interaction principally with collagen in normal bone and calcifying tendon have been elaborated by applying a number of different techniques for analysis of the inorganic and organic constituents of these tissues. The methods have included conventional and high voltage electron microscopy, electron diffraction, microscopic tomography and 3D image reconstruction, and atomic force microscopy. This summary presents results of these studies that have now characterized the size, shape, and aspects of the chemical nature of the crystals as well as their orientation, alignment, location, and distribution with respect to collagen. These data have provided the means for understanding more completely the formation and strength of the collagen-mineral composite present in most vertebrate calcifying tissues and, from that information, a basis for the adaptation of such tissues under mechanical constraints. In the context of the latter point, other data are given showing effects on collagen in bone cell cultures subjected to the unloading parameters of spaceflight. Implications of these results may be particularly relevant to explaining loss of bone by humans and other vertebrate animals during missions in space, during situations of extended fracture healing, long-term bedrest, physical immobilization, and related conditions. In a broader sense, the data speak to the response of bone and mineralized vertebrate tissues to changes in gravitational loading and applied mechanical forces in general.

Animals↗
PubMedDate not supplied

Diseases of uranium miners and other underground miners exposed to radon.

Excess lung cancer has been demonstrated in many groups of underground miners exposed to radon, including uranium miners and those mining other substances in radon-contaminated mines. In the United States, most underground uranium mines had shut down by the late 1980s, but occupational exposure to radon progeny remains a concern for many other types of underground miners and other underground workers. Worldwide, uranium mining continues, with documented production in Canada, South Africa and other African countries, and Australia. Thus, radon in underground mines remains a significant occupational hazard as the end of the twentieth century approaches.

Humans↗