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PubMed2006

Evaluation of fetal bone structure and mineralization in IGF-I deficient mice using synchrotron radiation microtomography and Fourier transform infrared spectroscopy.

The role of insulin like growth factor-I (IGF-I) during pre-natal development has not been evaluated in detail. However, the high degree of growth retardation and peri-natal mortality in IGF-I deficient mouse models indicates that it plays a critical role during this time. Techniques to assess the structure and quality of bone in small animal fetuses could be beneficial in better understanding its role in bone metabolism and skeletal development. Synchrotron microtomography (SR-microCT) and Fourier transform infrared spectroscopy (FTIR) may provide methods to visualize and quantify differences in the structure and mineral density of bone in small animal fetuses. Tibia and spine from IGF-I deficient and wildtype fetal mice (18th day gestation) were imaged using SR-microCT. Three-dimensional structural indices and the degree of mineralization were determined for each sample. Mineralization was also assessed using FTIR and von Kossa staining. Bone volume was systematically lower in IGF-I -/- animals (tibia: -15%, p<0.05) while both sites were found to have a more rod-like architecture (24%, p<0.05; 113%, p<0.01) and lower trabecular separation (-16%, p<0.05; -21%, p<0.05). These structural results were mostly consistent with those seen in adult models of IGF-I deficiency. The degree of mineralization as measured by SR-microCT was higher in the IGF-I tibial metaphysis (11.7%, p<0.0001), while FTIR of the whole bone showed mineralization to be lower in the knockout group (-11%, p<0.05). Interestingly, von Kossa staining revealed no mineral content in the IGF-I -/- spinal ossification center while SR-microCT clearly indicated the presence of highly attenuating components, if somewhat lower in IGF-I -/- animals (-2.2%, p<0.05). This indicates that IGF-I deficiency is linked to subtle differences in the mineral environment and mineralization progression. The advantages unique to SR-microCT allow for 3D visualization and quantification of pre-natal bone microstructure and mineral density in mice which was not previously possible.

Animals↗
PubMed2006

In vitro effects of singular or combined anti-oxidative vitamins and/or minerals on tilapia (Oreochromis hybrids) peripheral blood monocyte-derived, anterior kidney-derived, and spleen-derived macrophages.

The present study was to determine the in vitro effects of singular or combined anti-oxidative vitamins (A, C, and E) and/or minerals (Se, Zn, Cu, Mn, and Fe) on the immune functions of tilapia, Oreochromis hybrids, peripheral blood monocyte-derived, anterior kidney-derived, and spleen-derived macrophages. An optimal dose of vitamins and minerals increased cell viability and lysozyme activity. On the other hand, the above activities decreased at the high doses of combined vitamins (A+C+E group, each 300 microg mL(-1)) or single mineral (Se, Zn, Cu, Mn, and Fe groups, each 200, 800 or 1000 microg mL(-1)). Combining two of the aforementioned vitamins (A+C, A+E, and C+E groups, each 100 microg mL(-1)) was able to prolong cell viable time up to 72 h compared with singular vitamin addition. Before or after adding vitamins or minerals during infection, addition of vitamins decreased the percentage of dead cells and a greater effect was observed for mineral (each 40 or 80 microg mL(-1)) and vitamin (each 100 microg mL(-1)) combinations. A low dose of vitamins increased nitric oxide production and decreased superoxide production, but high dose of vitamins decreased superoxide and nitric oxide productions. Furthermore, minerals also decreased nitric oxide production at concentrations of 40, 80, 200, 800 or 1000 microg mL(-1). The threshold concentrations for cell death by necrosis and/or apoptosis were >1000 and >800 microg mL(-1) for vitamins and minerals, respectively. In conclusion, appropriate concentration of vitamins or minerals can increase tilapia macrophage immunity; nevertheless, extreme concentrations of vitamins or minerals are lethal to cells.

Animals↗
PubMedDate not supplied

Molecular regulation of milk trace mineral homeostasis.

The regulation of milk trace mineral homeostasis requires the temporal integration of three main processes, (A) mineral uptake into the secretory mammary epithelial cell (MEC); followed by (B) mineral secretion from MEC into the alveoli lumen of the mammary gland for sequestration in milk; and then (C) milk release in response to suckling. Trace mineral requirements of term infants are generally met by exclusive breast-feeding through about the first 6 months of life and although milk zinc (Zn), iron (Fe), and copper (Cu) concentrations are relatively refractory to maternal trace mineral status, they normally decline throughout lactation. Recently, Zn-, Fe- and Cu-specific transporters have been identified that regulate trace element uptake and efflux in various cell types; however, there is currently little information available regarding the processes through which the mammary gland regulates milk trace mineral transport. The homology of trace mineral transporters between species permits the utilization of rodent models to examine the regulation of mammary gland mineral transport. Therefore, we have used the lactating rat to determine changes in mammary gland Zn, Fe and Cu transporter expression and localization that occur throughout lactation and in response to maternal trace mineral deficiency in hope of elucidating some of the changes which occur during mammary gland trace element homeostasis and also may be occurring in lactating women.

Animals↗
PubMed1995

Combined therapy with estrogen and etidronate has an additive effect on bone mineral density in the hip and vertebrae: four-year randomized study.

BACKGROUND: Administration of estrogen or etidronate has been shown to increase bone mineral density in postmenopausal women. This 4-year, prospective, randomized study was carried out to monitor any added beneficial effect on bone mineral density when hormone-replacement therapy (HRT) was combined with etidronate. PATIENTS AND METHODS: Fifty-eight early postmenopausal women attending metabolic bone disease outpatient clinics were randomly allocated into four treatment groups and monitored for up to 4 years. All patients received 1.0 g/d of elemental calcium. In addition, group 1 received percutaneously administered HRT (n = 15); group 2, intermittent cyclical etidronate (ICE) (n = 14); group 3, HRT and ICE (n = 15); and group 4, calcium alone (n = 14). The bone mineral density (measured by dual-energy x-ray absorptiometry), biochemical variables of bone turnover, including bone-specific alkaline phosphatase, and urinary hydroxyproline:creatinine ratios were measured before treatment and at 2 and 4 years after treatment. RESULTS: In patients who received the combined therapy, bone mineral density was increased in the vertebrae by 10.9% (P < 0.001) and in the femora by 7.25% (P < 0.001) at 4 years. For patients treated with ICE, the increase was 6.79% (P < 0.001) and 1.20% (P < 0.05), and with HRT, 6.78% (P < 0.001) and 4.01% (P < 0.01) in the vertebrae and femora, respectively. The group treated with calcium alone lost 3.81% (P < 0.01) and 4.96% (P < 0.01) of bone mineral density in vertebrae and femora. Patients who received no specific therapy lost 8.58% (P < 0.01) from vertebrae, and 7.83% (P < 0.01) from the femora over 4 years. Patients who received combined therapy had significantly higher bone mineral density in both vertebrae (P < 0.05) and femora (P < 0.01), in comparison to patients who were treated with HRT, or ICE, alone. Three of 9 patients (33%) in the ICE group developed osteomalacia, as shown by bone histomorphometry, whereas in women who received combined HRT and ICE therapies, none of the 11 patients tested had evidence of bone mineralization defects. CONCLUSION: This 4-year, prospective, randomized study in early postmenopausal women showed an additive effect of ICE and HRT on the bone mineral density in both vertebrae and the hip. Furthermore, the combined therapy prevented the occurrence of osteomalacia associated with etidronate. This is the first study to demonstrate the effects of etidronate in early postmenopausal women, and the additive beneficial effects of HRT and ICE on bone mineral density.

Absorptiometry, Photon↗
PubMed1997

Bone mineral changes in young women with hypothalamic amenorrhea treated with oral contraceptives, medroxyprogesterone, or placebo over 12 months.

OBJECTIVES: The objectives of this study were to assess (1) whether treatment with oral contraceptives, in comparison with medroxyprogesterone and placebo, improved bone mineral in women with hypothalamic amenorrhea and (2) whether treatment with medroxyprogesterone, in comparison with placebo, improved bone mineral in women with hypothalamic oligomenorrhea. STUDY DESIGN: The study was a randomized, controlled clinical trial. Twenty-four white women, aged 14 to 28 years, with hypothalamic amenorrhea or oligomenorrhea were prospectively enrolled for a 12-month intervention period. Amenorrheic subjects were randomized to receive oral contraceptives, medroxyprogesterone, or placebo. Oligomenorrheic subjects were randomized to receive medroxyprogesterone or placebo. Bone mineral was measured by dual-energy x-ray absorptiometry at baseline and at 6 and 12 months. RESULTS: In amenorrheic subjects spine and total body bone mineral measurements at 12 months were greater in the oral contraceptive group than in the medroxyprogesterone and placebo groups when baseline bone mineral measurements, body weight, and age were controlled for (p < or = 0.05). There were no differences in hip bone mineral calcium and bone mineral density measurements at 12 months among the three groups. In oligomenorrheic subjects there was no detectable improvement in bone mineral associated with medroxyprogesterone use. CONCLUSIONS: This study supports the hypothesis that oral contraceptive use in women with hypothalamic amenorrhea will improve lumbar spine and total body bone mineral.

Adolescent↗
PubMed1998

Hip motion and moments during gait relate directly to proximal femoral bone mineral density in patients with hip osteoarthritis.

The present study examined the loads at the hip joint during gait and the bone mineral density of the proximal femur in 25 patients with end-stage hip osteoarthritis. Dual energy X-ray absorptiometry was used to determine the bone mineral density of the greater trochanter, femoral neck and Ward's triangle of the osteoarthritic group. The bone mineral density was normalized for the patient's age, gender, weight and ethnic origin (Z score). Gait analysis was used to determine the external hip joint moments and motion during walking for the osteoarthritic group and a control group of 21 normal subjects. The gait parameters of the osteoarthritic group which were significantly diminished compared to the normal group (p < 0.001) accounted for as much as 42% (p < 0.001) of the variation in the normalized bone mineral density. Specifically, the dynamic sagittal plane hip motion during gait (maximum flexion minus maximum extension) and peak external rotation and adduction moments were significantly correlated with greater trochanter (R = 0.429-0.648, p = 0.032-0.0001) and Ward's triangle (R = 0.418-0.532, p = 0.038-0.006) normalized bone mineral density while the adduction moment was also significantly correlated with the femoral neck normalized bone mineral density (R = 0.5394, p = 0.005). The normalized bone mineral density of the femoral neck and Ward's triangle was elevated while that of the greater trochanter was decreased as compared to normal reference values. The significant correlation between the hip joint moments during gait and femoral bone mineral density indicate that hip joint loads need to be included when explaining local variation in bone mineral density in hip osteoarthritis.

Absorptiometry, Photon↗
PubMed1994

Influences on skeletal mineralization in children and adolescents: evidence for varying effects of sexual maturation and physical activity.

OBJECTIVE: To establish rates of skeletal mineralization in children and adolescents, and to identify factors that influence these rates. DESIGN: Three-year observational study. SETTING: University hospital. SUBJECTS: Ninety white children, aged 6 to 14 years. MEASUREMENTS: Bone mineral density of the radius, spine, and hip was measured at baseline and 3 years later. Physical activity was assessed by questionnaires at 6-month intervals and dietary calcium intake by diet diary 1 day per month for 36 months. Sexual maturation (Tanner stage) was determined by an endocrinologist at 6-month intervals, as necessary to classify children as prepubertal, peripubertal, or postpubertal. RESULTS: Skeletal mineralization accelerated markedly at puberty in the spine (0.077 vs 0.027 gm/cm2 per year, peripubertal vs prepubertal) and greater trochanter (0.050 vs 0.027 gm/cm2 per year), less markedly in the femoral neck (0.047 vs 0.030 gm/cm2 per year), and only slightly in the radius. Nearly one third (15 gm) of the total skeletal mineral in the lumbar spine of adult women (approximately 52 gm) was accumulated in the 3 years around the onset of puberty. Increases in height and weight were the strongest correlates of skeletal mineralization: weight changes were more strongly correlated with trabecular bone sites and changes in height with cortical bone sites. Increases in calf muscle area were strongly associated with mineralization, particularly in peripubertal children, and physical activity was associated with more rapid mineralization in prepubertal children. CONCLUSIONS: Puberty has varying effects on skeletal mineralization depending on skeletal site; trabecular bone is apparently more sensitive to changing hormone concentrations. Physical activity and normal growth are also positively associated with skeletal mineralization, also depending on skeletal site and sexual maturation.

Adolescent↗
PubMed2002

Mineralization of a sorbed polycyclic aromatic hydrocarbon in two soils using catalyzed hydrogen peroxide.

Hydrogen peroxide (H2O2) catalyzed by soluble iron or naturally occurring soil minerals, (i.e., modified Fenton's reagent) was investigated as a basis for mineralizing sorbed and NAPL-phase benzo[a]pyrene (BaP), a hydrophobic and toxic polycyclic aromatic hydrocarbon, in two soils of different complexity. 14C-Benzo[a]pyrene was added to silica sand and a silt loam soil, and mineralization was investigated using three-level central composite rotatable experimental designs. The effects of H2O2 concentration, slurry volume, and iron(II) amendment were investigated in the silica sand systems. In a Palouse loess silt loam soil, the variables included H2O2 concentration, slurry volume, and pH, with H2O2 catalyzed by naturally occurring iron oxyhydroxides. Regression equations generated from the data were used to develop three-dimensional response surfaces describing BaP mineralization. Based on the recovery of 14C-CO2, 70% BaP mineralization was achieved in the sand within 24 h using 15 M H2O2 and an iron(II) concentration of 6.6 mM with a slurry volume of 0.3 x the field capacity of the sand. For the silt loam soil, 85% mineralization of BaP was observed using 15 M H2O2, no iron amendment, and a slurry volume of 20 x the soil field capacity. The balance of the radiolabeled carbon remained as unreacted BaP in the soil fraction. Gas-purge measurements over 5 d confirmed negligible desorption under nontreatment conditions. However, oxidation reactions were complete within 24 h and promoted up to 85% BaP mineralization, documenting that the natural rate of desorption/dissolution did not control the rate of oxidation and mineralization of the BaP. The results show that catalyzed H2O2 has the ability to rapidly mineralize sorbed/NAPL-phase BaP and that partitioning, which is often the rate-limiting factor in soil remediation, does not appear to limit the rate of vigorous Fenton-like treatment.

Crystallization↗
PubMed1998

Bone mineralization status measured by dual energy radiographic densitometry in preterm infants fed commercial formulas.

We have studied the effect of two preterm commercial infant formulas with different calcium and phosphorus contents on the mineral balance and bone mineralization of 30 preterm infants at 1 month of age. Bone mineralization was measured by dual energy X-ray densitometry. The formula supplying a higher content of calcium and phosphorus promoted higher mineral retention (P<0.01) as well as higher bone mineral content (1.556 vs. 1.073 g, P<0.01) and bone mineral density (0.458 vs. 0.424 g/cm2, P<0.05), approaching values of the control group, which comprised a cohort of 15 preterm newborns whose gestational age was 4 weeks older than the subjects selected to be fed with the formulas. The intake of calcium correlated with retention (r=0.69); the phosphorus intake also correlated with phosphorus retention (r=0.95). Intakes of calcium and phosphorus correlated with the bone mineral content (r=0.65) and with bone mineral density (r=0.49). We conclude that formulas for preterm infants should not have a calcium content lower than 120 mg/100 kcal and should have a calcium/phosphorus ratio of about 2 to promote adequate bone mineralization.

Absorptiometry, Photon↗
PubMed1998

Bone mineralization in preterm infants.

In preterm neonates a large skeletal mineral deficit builds up between birth and 40 wk postconception. During the phase of catch-up growth between 40 and 60 wk postconception there is a catch-up in peripheral skeletal mineralization, so that by the age of 1 y the skeletal mineral content is similar in preterm and term infants, despite the former being smaller, a finding that has been replicated for lumbar spinal mineralization. Later follow-up studies suggest that this catch-up persists and mineralization remains appropriate for body size. However, given the continuing abnormal growth experience of former preterm individuals, it would still be important to examine their bone mineralization in early adulthood. A number of interventions can improve perinatal bone mineralization, but few studies examine their long-term effectiveness. One such study has suggested that a relatively poor mineral diet in this period is, counterintuitively, associated with a later advantage in skeletal mineralization. If this finding is repeatable, then it could result in a major change in nutrition strategy in the neonatal period.

Aging↗
PubMed1998

Determination of bone mineral density in the third lumbar vertebral body using photon absorptiometry techniques.

Dual-photon absorptiometry and triple-energy X-ray absorptiometry were used to investigate the total bone mineral content and density as well as the trabecular bone mineral density in the third lumbar vertebral body. Both anteroposterior (AP) and lateral (LAT) measurements were performed. By combining the two projections it was found that the mean trabecular bone mineral density for all 202 subjects included in the study was 52% (SD +/- 20%) of the total bone mineral density in the third lumbar vertebral body. The mean trabecular bone mineral density as a fraction of the total vertebral body bone mineral density decreased as a function of age. The relative annual change in this fraction differed between males and females. It was also found that neither trabecular nor total bone mineral density differed significantly between male and female subjects aged 25-35 years, and bone mineral density (BMD), expressed in g/cm3, showed no correlation to subject height, body weight or body mass index (BMI). Male and female individuals showed different rates of change of trabecular bone mineral density with age.

Absorptiometry, Photon↗
PubMed1997

Mineral induction by immobilized phosphoproteins.

Dentin phosphoproteins are thought to have a primary role in the deposition of mineral on the collagen of dentin. In this study we determined the type of binding between collagen and phosphoproteins necessary for mineral formation onto collagen fibrils and whether the phosphate esters are required. Bovine dentin phosphophoryn or phosvitin from egg yolk were immobilized on reconstituted skin type I collagen fibrils by adsorption or by covalent cross-linking. In some samples the ester phosphate was removed from the covalently cross-linked phosphoproteins by treatment with acid phosphatase. All samples were incubated at 37 degrees C in metastable solutions that do not spontaneously precipitate. Reconstituted collagen fibrils alone did not induce mineral formation. The phosphoproteins adsorbed to the collagen fibrils desorbed when the mineralization medium was added, and mineral was not induced. The mineral induced by the cross-linked phosphoproteins was apatite, and the crystals were confined to the surface of the collagen fibrils. With decreasing medium saturation the time required for mineral induction increased. The interfacial tensions calculated for apatite formation by either phosphoprotein cross-linked to collagen were about the same as that for phosphatidic acid liposomes and hydroxyapatite. This similarity in values indicates that the nucleation potential of these highly phosphorylated surfaces is about the same. It is concluded that phosphoproteins must be irreversibly bound to collagen fibrils for the mineralization of the collagen network in solutions that do not spontaneously precipitate. The phosphate esters of phosphoproteins are required for mineral induction, and the carboxylate groups are not sufficient.

Acid Phosphatase↗
PubMed1999

Added value of bone mineral density in hip fracture risk scores.

Hip fractures constitute a major health problem. For effective prevention, high-risk groups need to be identified. The objective here was to develop hip fracture risk scores while assessing the added value of bone mineral density relative to more conventional risk indicators. We prospectively followed during 4 years a cohort of 5208 persons (2193 men) aged 55 years and over from the Rotterdam Study, a population-based cohort study conducted in the Netherlands. Risk scores for hip fracture were constructed using several conventional risk indicators requiring interview and anthropometry only, and bone mineral density. During follow-up, 50 persons (14 men) suffered hip fracture. Hip fracture risk was independently determined by age, gender, height, the use of a walking aid, cigarette smoking, and either bone mineral density or weight. We developed two risk scores, with and without bone mineral density. The observed 4-year risk ranged from 3/3389 (0.1%) to 17/169 (10.1%) for the lowest and highest category of the score including bone mineral density, respectively. For the score without bone mineral density, these risks were 8/3117 (0.3%) and 16/144 (11.1%), respectively. The area under the receiver operating characteristic curve indicating discriminatory power was 0.88 for the risk score including, and 0.83 for the score excluding, bone mineral density (p for difference = 0.04). In conclusion, risk scores with and without bone mineral density measurement can be used for hip fracture risk assessment in elderly persons. While the score with bone mineral density has a modestly better performance, the score requiring interview and anthropometry only may be especially useful in primary care settings.

Aged↗
PubMed1998

Bone mineral changes during pregnancy and lactation: a longitudinal cohort study.

1. The influence of pregnancy, lactation and weaning on bone mineral density in healthy women was investigated during a 2 year prospective study of 59 pregnant and lactating women from the 18th week of gestation. 2. Bone mineral density was measured by dual energy X-ray absorptiometry at the non-dominant radius ultra distally and more proximally in the 18th and 37th weeks of gestation, and 0, 3, 6, 12 and 18 months after delivery. Measurements of bone mineral density of the lumbar spine, the proximal femur and the whole body were performed at all dates after delivery. 3. Reappearance of menstruation after delivery averaged 6.1 months; mean lactating period was 8.7 months. During pregnancy and lactation bone mineral density tended to decrease, but different measuring sites showed different patterns of bone mineral density changes. The reduction in the ultra distal radius during pregnancy amounted to 2%, and no further changes were observed here during lactation. After delivery, reduction in mean bone mineral density was most pronounced in the spine (5.2% in 3 months), but the fall in bone mass tended to revert after resumption of menstruation. Bone mineral density was still reduced by 3.3% after 12 months in women with menstruation resumption later than 8 months after delivery. No significant reduction was observed 18 months after delivery. No association with calcium intake, weight changes or initial bone mineral density was observed. High calcium intake did not protect against bone mineral loss in the spine and the femur. 4. Thus it can be concluded that bone loss during pregnancy and lactation took place mainly from the trabecular skeleton. Resumption of menstruation tended to result in a regain of bone mass towards baseline.

Absorptiometry, Photon↗
PubMed2003

Photochemical degradation and mineralization of 4-chlorophenol.

INTENTION, GOAL, SCOPE, BACKGROUND: Since the intermediate products of some compounds can be more toxic and/or refractory than the original compund itself, the development of innovative oxidation technologies which are capable of transforming such compounds into harmless end products, is gaining more importance every day. Advanced oxidation processes are one of these technologies. However, it is necessary to optimize the reaction conditions for these technologies in order to be cost-effective. OBJECTIVE: The main objectives of this study were to see if complete mineralization of 4-chlorophenol with AOPs was possible using low pressure mercury vapour lamps, to make a comparison of different AOPs, to observe the effect of the existence of other ions on degradation efficiency and to optimize reaction conditions. METHODS: In this study, photochemical advanced oxidation processes (AOPs) utilizing the combinations of UV, UV/H2O2 and UV/H2O2/Fe2+ (photo-Fenton process) were investigated in labscale experiments for the degradation and mineralization of 4-chlorophenol. Evaluations were based on the reduction of 4-chlorophenol and total organic carbon. The major parameters investigated were the initial 4-chlorophenol concentration, pH, hydrogen peroxide and iron doses and the effect of the presence of radical scavengers. RESULTS AND DISCUSSION: It was observed that the 4-chlorophenol degradation efficiency decreased with increasing concentration and was independent of the initial solution pH in the UV process. 4-chlorophenol oxidation efficiency for an initial concentration of 100 mgl(-1) was around 89% after 300 min of irradiation in the UV process and no mineralization was achieved. The efficiency increased to > 99% with the UV/H2O2 process in 60 min of irradiation, although mineralization efficiency was still around 75% after 300 min of reaction time. Although the H2O2/4-CP molar ratio was kept constant, increasing initial 4-chlorophenol concentration decreased the treatment efficiency. It was observed that basic pHs were favourable in the UV/H2O2 process. The results showed that the photo-Fenton process was the most effective treatment process under acidic conditions. Complete disappearance of 100 mgl(-1) of 4-chlorophenol was achieved in 2.5 min and almost complete mineralization (96%) was also possible after only 45 min of irradiation. The efficiency was negatively affected from H2O2 in the UV/H2O2 process and Fe2+ in the photo-Fenton process over a certain concentration. The highest negative effect was observed with solutions containing PO4 triple ions. Required reaction times for complete disappearance of 100 mgl(-1) 4-chlorophenol increased from 2.5 min for an ion-free solution to 30 min for solutions containing 100 mgl(-1) PO4 triple ion and from 45 min to more than 240 min for complete mineralization. The photodegradation of 4-chlorophenol was found to follow the first-order law. CONCLUSION: The results of this study showed that UV irradiation alone can degrade 4-CP, although at very slow rates, but cannot mineralize the compound. The addition of hydrogen peroxide to the system, the so-called UV/H2O2 process, significantly enhances the 4-CP degradation rate, but still requires relatively long reaction periods for complete mineralization. The photo-Fenton process, the combination of homogeneous systems of UV/H2O2/Fe2+ compounds, produces the highest photochemical elimination rate of 4-CP and complete mineralization is possible to achieve in quite shorter reaction periods when compared with the UV/H2O2 process. RECOMMENDATIONS AND OUTLOOK: It is more cost effective to use these processes for only purposes such as toxicity reduction, enhancement of biodegradability, decolorization and micropollutant removal. However the most important point is the optimization of the reaction conditions for the process of concern. In such a case, AOPs can be used in combination with a biological treatment systems as a pre- or post treatment unit providing the cheapest treatment option. The AOP applied, for instance, can be used for toxicity reduction and the biological unit for chemical oxygen demand (COD) removal.

Chlorophenols↗
PubMed2001

Changes in phospholipid extractability and composition accompany mineralization of chicken growth plate cartilage matrix vesicles.

Matrix vesicles are lipid bilayer-enclosed structures that initiate extracellular mineral formation. Little attention has been given to how newly formed mineral interacts with the lipid constituents and then emerges from the lumen. To explore whether specific lipids bind to the incipient mineral and if breakdown of the membrane is involved, we analyzed changes in lipid composition and extractability during vesicle-induced calcification. Isolated matrix vesicles were incubated in synthetic cartilage lymph to induce mineral formation. At various times, samples of the lipids were taken for analysis, extracted both before and after demineralization to remove deposited mineral. Phosphatidylserine and phosphatidylinositol both rapidly disappeared from extracts made before decalcification, indicating rapid degradation. However, extracts made after demineralization revealed that phosphatidylserine had become complexed with newly forming mineral. Concomitantly, its levels actually increased, apparently by base-exchange with phosphatidylethanolamine. Though partially complexed with the mineral, phosphatidylinositol was nevertheless rapidly broken down. Sphingomyelin and phosphatidylethanolamine also underwent rapid breakdown, but phosphatidylcholine was degraded more slowly, all accompanied by a buildup of free fatty acids. The data indicate that phosphatidylserine forms complexes that accompany mineral formation, while degradation of other membrane phospholipids apparently enables egress of crystalline mineral from the vesicle lumen.

Animals↗
PubMed2003

Brief bone morphogenetic protein 2 treatment of glucocorticoid-inhibited MC3T3-E1 osteoblasts rescues commitment-associated cell cycle and mineralization without alteration of Runx2.

Glucocorticoids (GCs) inhibit bone formation in vivo. In MC3T3-E1 osteoblasts, chronic administration of 1 microm dexamethasone (DEX) starting at confluency results in >98% inhibition of bone morphogenetic protein 2 (BMP-2) expression and apatite mineral deposition. Here, it is shown that brief exposure to recombinant human BMP-2 (rhBMP-2), as short as 6 h, is sufficient to induce irreversible commitment to mineralization in DEX-treated cultures. RhBMP-2 dose dependently rescued mineralization but not collagen accumulation in DEX-inhibited cultures. The selective restoration of mineralization was evident in the higher mineral to matrix ratios of DEX/rhBMP-2 co-treated cultures compared with control. We tested the involvement of the runt-related transcription factor 2 (Runx2) in the DEX inhibition and rhBMP-2 rescue of mineralization. Surprisingly, DEX did not decrease Runx2 DNA binding activity, transactivation, or association with the endogenous osteocalcin gene promoter. Furthermore, the rhBMP-2 rescue did not involve Runx2 stimulation, suggesting an important role for factors other than Runx2 in BMP-2 action. Finally, we studied the differentiation-related cell cycle, which persists during commitment to mineralization in untreated cultures, but is inhibited along with mineralization in DEX-treated cultures. Although both rhBMP-2 alone and DEX alone were antimitogenic, rhBMP-2 stimulated this cell cycle in DEX-inhibited cultures. In conclusion, brief rhBMP-2 treatment restores mineralization in DEX-inhibited MC3T3-E1 osteoblasts via a mechanism different from Runx2 stimulation. This restoration may be functionally related to the accompanying rescue of the differentiation-related cell cycle. The efficacy of short term BMP-2 treatment supports the potential of short-lived BMP vectors for skeletal therapy in both traditional and gene therapeutic approaches.

Alkaline Phosphatase↗
PubMed2006

Comparison of microbial pyrene and benzo[a]pyrene mineralization in liquid medium, soil slurry, and soil.

The microbial degradation of 14C-pyrene and 14C-benzo[a]pyrene by a bacterial mixed culture was studied within a mixture of the PAHs phenanthrene, anthracene, pyrene, fluoranthene, and benzo[a]pyrene as sole carbon source in the different culture systems: (i) liquid medium, (ii) soil slurry (surface and grinding influence), and (iii) soil. The fate of these two labeled compounds was followed in these systems with an emphasis on mineralization to carbon dioxide, extractability, and adsorption to humic materials and formation of unextractable residual. Mineralization showed the most obvious differences: soil slurries achieved the best results both concerning the extent of mineralization and the time required. The highest extent of pyrene mineralization (54% within 21 days) was observed in soil slurries; in liquid media, pyrene mineralization was slower, but reached approximately the same extent (54% in 150 days); in soils, mineralization reached only 36% of added pyrene after 160 days. Benzo[a]pyrene was mineralized in a mixture of PAHs in soil slurries to an extent of 34% within 70 days, whereas mineralization in liquid medium and soil occurred in the range of 5% (70 days). Mineralization of benzo[a]pyrene in sand slurries was lower compared to soil slurries (19% in sand slurries vs. 32% in soil slurries within 50 days).

Adsorption↗