Fe-oxide concretions formed by interacting carbonate and acidic waters on Earth and Mars.

Spherical Fe-oxide concretions on Earth, especially in Utah, USA, have been investigated as an analog of hematite spherules found in Meridiani Planum on Mars to support interpretations of water-rock interactions in early Mars. Although several formation mechanisms have been proposed for the Fe-oxide concretions on Earth, it is still unclear whether these mechanisms are viable because a precise formation process and precursor of the concretions are missing. This paper presents evidence that Fe-oxide concretions in Utah and newly found Fe-oxide concretions in Mongolia had spherical calcite concretions as precursors. Different formation stages of calcite and Fe-oxide concretions observed, both in Utah and Mongolia, indicate that calcite concretions initially formed within eolian sandstone strata and were dissolved by infiltrating Fe-rich acidic waters to form spherical FeO(OH) crusts due to pH buffering. The similarity between these Fe-oxide concretions on Earth and the hematite spherule occurrences in Meridiani Planum, combined with evidence of acid sulfate water influences on Mars, suggest that the hematite spherules also formed from dissolution of preexisting carbonate spherules possibly formed under a dense carbon dioxide early martian atmosphere.

A Paleoarchean coastal hydrothermal field inhabited by diverse microbial communities: the Strelley Pool Formation, Pilbara Craton, Western Australia.

The 3.4-Ga Strelley Pool Formation (SPF) at the informally named 'Waterfall Locality' in the Goldsworthy greenstone belt of the Pilbara Craton, Western Australia, provides deeper insights into ancient, shallow subaqueous to possibly subaerial ecosystems. Outcrops at this locality contain a thin (<3 m) unit of carbonaceous and non-carbonaceous cherts and silicified sandstones that were deposited in a shallow-water coastal environment, with hydrothermal activities, consistent with the previous studies. Carbonaceous, sulfide-rich massive black cherts with coniform structures up to 3 cm high are characterized by diverse rare earth elements (REE) signatures including enrichment of light [light rare earth elements (LREE)] or middle rare earth elements and by enrichment of heavy metals represented by Zn. The massive black cherts were likely deposited by mixing of hydrothermal and non-hydrothermal fluids. Coniform structures in the cherts are characterized by diffuse laminae composed of sulfide particles, suggesting that unlike stromatolites, they were formed dominantly through physico-chemical processes related to hydrothermal activity. The cherts yield microfossils identical to previously described carbonaceous films, small and large spheres, and lenticular microfossils. In addition, new morphological types such as clusters composed of large carbonaceous spheroids (20-40 µm across each) with fluffy or foam-like envelope are identified. Finely laminated carbonaceous cherts are devoid of heavy metals and characterized by the enrichment of LREE. This chert locally contains conical to domal structures characterized by truncation of laminae and trapping of detrital grains and is interpreted as siliceous stromatolite formed by very early or contemporaneous silicification of biomats with the contribution of silica-rich hydrothermal fluids. Biological affinities of described microfossils and microbes constructing siliceous stromatolites are under investigation. However, this study emphasizes how diverse the microbial community in Paleoarchean coastal hydrothermal environment was. We propose the diversity is at least partially due to the availability of various energy sources in this depositional environment including reducing chemicals and sunlight.

Combining FIB milling and conventional Argon ion milling techniques to prepare high-quality site-specific TEM samples for quantitative EELS analysis of oxygen in molten iron.

This paper reports a procedure to combine the focused ion beam micro-sampling method with conventional Ar-milling to prepare high-quality site-specific transmission electron microscopy cross-section samples. The advantage is to enable chemical and structural evaluations of oxygen dissolved in a molten iron sample to be made after quenching and recovery from high-pressure experiments in a laser-heated diamond anvil cell. The evaluations were performed by using electron energy-loss spectroscopy and high-resolution transmission electron microscopy. The high signal to noise ratios of electron energy-loss spectroscopy core-loss spectra from the transmission electron microscopy thin foil, re-thinned down to 40 nm in thickness by conventional Argon ion milling, provided us with oxygen quantitative analyses of the quenched molten iron phase. In addition, we could obtain lattice-fringe images using high-resolution transmission electron microscopy. The electron energy-loss spectroscopy analysis of oxygen in Fe(0.94)O has been carried out with a relative accuracy of 2%, using an analytical procedure proposed for foils thinner than 80 nm. Oxygen K-edge energy-loss near-edge structure also allows us to identify the specific phase that results from quenching and its electronic structure by the technique of fingerprinting of the spectrum with reference spectra in the Fe-O system.

The redox state of the mantle during and just after core formation.

Siderophile elements are depleted in the Earth's mantle, relative to chondritic meteorites, as a result of equilibration with core-forming Fe-rich metal. Measurements of metal-silicate partition coefficients show that mantle depletions of slightly siderophile elements (e.g. Cr, V) must have occurred at more reducing conditions than those inferred from the current mantle FeO content. This implies that the oxidation state (i.e. FeO content) of the mantle increased with time as accretion proceeded. The oxygen fugacity of the present-day upper mantle is several orders of magnitude higher than the level imposed by equilibrium with core-forming Fe metal. This results from an increase in the Fe2O3 content of the mantle that probably occurred in the first 1Ga of the Earth's history. Here we explore fractionation mechanisms that could have caused mantle FeO and Fe2O3 contents to increase while the oxidation state of accreting material remained constant (homogeneous accretion). Using measured metal-silicate partition coefficients for O and Si, we have modelled core-mantle equilibration in a magma ocean that became progressively deeper as accretion proceeded. The model indicates that the mantle would have become gradually oxidized as a result of Si entering the core. However, the increase in mantle FeO content and oxygen fugacity is limited by the fact that O also partitions into the core at high temperatures, which lowers the FeO content of the mantle. (Mg,Fe)(Al,Si)O3 perovskite, the dominant lower mantle mineral, has a strong affinity for Fe2O3 even in the presence of metallic Fe. As the upper mantle would have been poor in Fe2O3 during core formation, FeO would have disproportionated to produce Fe2O3 (in perovskite) and Fe metal. Loss of some disproportionated Fe metal to the core would have enriched the remaining mantle in Fe2O3 and, if the entire mantle was then homogenized, the oxygen fugacity of the upper mantle would have been raised to its present-day level.

Osteopontin in gingival crevicular fluid.

Osteopontin (OPN) is a major glycosylated phosphoprotein in bone matrix and is produced by several cells including osteoblasts, osteoclasts and macrophages. OPN levels increase in active sites of bone metabolism. Recently, several bone-related proteins were identified in gingival crevicular fluid (GCF) to seek markers of alveolar bone resorption in periodontal disease. In this study, we investigated the existence of OPN in GCF and the correlation between OPN level in GCF and probing depth (PD) of sampling sites in 98 periodontitis patients and 35 healthy subjects. An immunoblotting analysis using 10% polyacrylamide gel showed that two forms of OPN with molecular masses of 54 and 66 kDa and several degraded fragments were detected in most GCF samples from diseased sites (PD > 4 mm). In GCF samples from healthy sites (PD < or = 3 mm), only one form (54 kDa) was observed, but any degraded fragments were not detected. When OPN amounts in GCF samples were determined by ELISA, a weak. but significant correlation was observed between OPN amount in GCF and PD (r=0.32, p=0.0013). These results demonstrate that OPN exists in GCF and that OPN level in GCF increases with the progression of periodontal disease.

Nifedipine induces gingival overgrowth in rats through a reduction in collagen phagocytosis by gingival fibroblasts.

BACKGROUND: Nifedipine is used as a long-acting vasodilator, and a primary side effect is the induction of gingival overgrowth, which is characterized by an accumulation of collagenous components within the gingival connective tissue. To elucidate the mechanisms of nifedipine-induced gingival overgrowth, we investigated the effect of nifedipine on Type I collagen metabolism in the gingiva of rats. METHODS: Twenty-day-old rats were fed a powdered diet containing or lacking nifedipine for 3 to 55 days. Immunohistochemical analysis with anti-Type I collagen antibody was employed to examine the density of Type I collagen in the gingival connective tissue. Total RNAs were isolated from mandibular molar gingiva on days 0, 3, 15, 30, and 55, and reverse transcription polymerase chain reaction was performed to investigate the mRNA levels of Type I collagen. In addition, we performed a flow cytometric analysis with collagen-coated latex beads and cultured fibroblasts derived from rat gingiva to measure collagen phagocytosis. RESULTS: Immunohistochemical analysis revealed that Type I collagen was more prevalent in the connective tissue of nifedipine-treated gingiva than in controls on day 55. In the nifedipine-treated group, the expression of Type I collagen mRNA gradually decreased to 1.5% on day 55 compared to day 0. In the control group, Type I collagen mRNA also decreased to 32%; however, mRNA expression was significantly lower in the nifedipine-treated group than in the controls. When the rate of phagocytic cells derived from nifedipine-treated gingiva and controls was represented as the mean +/- SE of the percentage from 3 different experiments, the values were as follows: on day 15, 13.5 +/- 2.1% and 15.0 +/- 1.5%; on day 30, 12.2 +/- 4.3% and 34.5 +/- 6.7% in the nifedipine-treated and the control group, respectively, indicating that phagocytic cells were considerably fewer in the nifedipine-treated gingiva on day 30. This finding demonstrates that the decrease in phagocytosis caused by nifedipine appeared before the detection of severe macroscopic gingival overgrowth. CONCLUSION: These findings suggest that the decrease in collagen degradation due to lower phagocytosis is closely associated with the increase in Type I collagen accumulation in nifedipine-treated rat gingiva.

Mast cells are not involved in the development of cyclosporin A-induced gingival hyperplasia: a study with mast cell-deficient mice.

BACKGROUND: A previous study suggested that mast cells (MC) are involved in the development of cyclosporin A-induced gingival hyperplasia, since an increased number of MC were observed in the tissue sections of enlarged gingiva. To determine the role of MC in gingival hyperplasia, an MC-deficient mouse model was used in the current study. METHODS: MC-deficient mice (WBB6F1xW/Wv) and their littermates (+/+) were fed sucrose-containing diets supplemented with or without varying concentrations (300, 400, 500, 600 mg) of cyclosporin A/kg of diet. After 30 days, the mice were sacrificed and the degree of gingival hyperplasia was evaluated by the appearance of the gingiva. Tissue MC were stained with toluidine blue to confirm the presence or absence of MC in the enlarged gingiva. RESULTS: Both W/Wv and +/+ mice, when fed with 600 mg cyclosporin A/kg diet for 30 days, exhibited a similar degree of gingival hyperplasia, while other test mice or control mice did not. Toluidine blue staining of the tissue sections confirmed the presence of MC in the enlarged gingiva of the +/+ mice, but not the W/Wv mice. CONCLUSIONS: These results indicate that mast cells are not necessary in the development of cyclosporin A-induced gingival hyperplasia, and that the increased number of MC observed in the enlarged gingiva may be a secondary effect of gingival hyperplasia. We also conclude that a study of mice lacking certain molecules or cells would be quite useful in determining the molecules or cell types responsible for the pathogenesis of drug-induced gingival hyperplasia.

FtsH recognizes proteins with unfolded structure and hydrolyzes the carboxyl side of hydrophobic residues.

FtsH of Escherichia coli is an essential membrane-integrated ATP-dependent protease. We cloned a gene for an FtsH homolog (T. FtsH) from Thermus thermophilus HB8, expressed it in E. coli, and purified the expressed protein. ATPase activity of T.FtsH was activated by proteins with unfolded structure ( alpha-casein and pepsin), and T.FtsH digested these proteins in an ATP-, Zn(2+)-dependent manner. alpha-Lactalbumin was digested by T.FtsH when it was largely unfolded, but not in its native form. Analysis of the proteolytic products revealed that, in most cases, T.FtsH cleaved the C-terminal side of hydrophobic residues and produced a characteristic set of small peptides (<30 kDa) without releasing a large intermediate. Thus, T.FtsH recognizes the unfolded structure of the proteins and progressively digests them at the expense of ATP. A soluble domain of T.FtsH, which lacked the N-terminal two transmembrane helices, was also prepared but was found to retain neither ATPase nor protease activities. Thus, the membrane segment appeared to be indispensable for these activities of T.FtsH.

Cyclosporin A decreases the degradation of type I collagen in rat gingival overgrowth.

Cyclosporin A (CsA) is used as an immunosuppressive agent and its prominent side effect is the induction of fibrous gingival overgrowth. The purpose of this study was to investigate the effect of CsA on the type I collagen metabolism in the gingiva of rats fed a powdered diet either containing or lacking CsA. Immunohistochemical analysis revealed that type I collagen was more prevalent in the connective tissue of CsA-treated gingiva than in those of control rats on days 15, 30, and 55 after the start of feeding. Total RNAs were isolated from mandibular molar gingiva on days 0, 3, 8, 15, 30, and 55. Quantitative analysis of mRNA by reverse transcriptase-polymerase chain reaction revealed that the CsA-treated groups showed a gradual decrease in expression of type I collagen and collagenase mRNAs, 0.4% and 18.0% on day 55 compared with those on day 0, respectively. In the control groups, type I collagen and collagenase mRNAs also decreased to 19.7% and 63.0%, respectively, however, both mRNA expressions were significantly lower in the CsA-treated group than in the controls. An electron microscopic analysis of fibroblasts was performed to count the number of cells with collagen fibrils in the cytoplasm, a marker of phagocytosis of collagen by fibroblasts. The collagen fibrils were detected in 4.7% +/- 2.7% and 24.3% +/- 13.7% of fibroblasts in the overgrown gingiva treated with CsA rat for 8 days and 30 days, but in 57.0% +/- 5.3% and 81.3% +/- 9.2% of fibroblasts in the each control group gingiva, respectively. Furthermore, in vitro analysis was performed to measure the phagocytosis of cultured fibroblasts by flow cytometry using collagen-coated latex beads. Fibroblasts isolated from CsA-treated gingiva on day 8 and day 30 contained 5.7% +/- 0.6% and 9.9% +/- 1.5% phagocytic cells, whereas control fibroblasts contained 50.3% +/- 5.5% and 33.3% +/- 4.9% phagocytic cells, respectively. The inhibition rate of phagocytic activity was similar between in vivo and in vitro assays. These findings suggest that the decrease of the collagen degradation due to the lower phagocytosis and the lower collagenase mRNA expression are closely associated with the increase of type I collagen accumulation in CsA-treated rat gingiva.

Chemotactic response of periodontal ligament cells decreases with donor age: association with reduced expression of c-fos.

OBJECTIVE: To understand the effects of aging on cellular motility of human periodontal ligament (PDL) cells, and to determine the possible link between cell proliferation and migration in relation to cellular aging. MATERIALS AND METHODS: The chemotactic response of PDL cells from three juvenile and four older donors were compared. Then, migrated or unmigrated cells were examined for their cell cycle by morphological and immunocytochemical procedures. Finally, migrated or unmigrated cells were examined for the expression of c-fos and c-myc by in situhybridization. RESULTS: PDL cells from older donors showed lower chemotaxis compared with the cells from juvenile donors (P < 0.05). Cells undergoing migration were found not to be in the S- or M-phase of the cell cycle. However, all migrated cells were found to express c-fos, while many of the cells which did not migrate were found not to express c-fos. CONCLUSIONS: Cellular motility of PDL cells decreases with donor age as well as cell proliferation. Since the cells reaching senescence fail to express c-fos, the mechanisms linked to cellular senescence may be a possible underlying mechanism for low migration seen in the older cells.

DNA-binding properties of the overexpressed recombinant estrogen receptor alpha.

Estrogen receptor alpha was overexpressed in COS-7 cells by transformation of an expression vector with the full length open reading frame of the receptor alpha. The nuclear estradiol-receptor complex and the soluble receptor from the COS-7 cells were cross-linked with an estrogen response element (ERE), which was substituted with 5-bromo-2'-deoxyuridine (BrdUVRE), as the receptor dimers by UV irradiation. In gel retardation analysis, the specific bindings of both nuclear and soluble receptors to ERE were decreased with increasing of KCl concentration compared with 0.1 M KCl. The ionic interactions of both receptors with ERE are thought to be similar.

Linearity of the Faraday-rotation-type ac magnetic-field sensor with a ferrimagnetic or ferromagnetic rotator film.

We analyze the linearity and modulation depth of ac magnetic-field sensors or current sensors, using a ferrimagnetic or ferromagnetic film as the Faraday rotator and employing the detection of only the zeroth-order optical diffraction component from the rotator. It is theoretically shown that for this class of sensor the condition of a constant modulation depth and that of a constant ratio error give an identical series of curves for the relationship between Faraday rotation angle Θ and polarizer/analyzer relative angle Φ. We give some numerical examples to demonstrate the usefulness of the result with reference to a rare-earth iron garnet film as the rotator.

Expression of the hepatocyte growth factor gene during chick limb development.

It has been shown that mirror-image duplications of the zeugopodia and digits are formed when MRC-5 fibroblasts producing hepatocyte growth factor (HGF) are applied to the anterior region of the chick limb bud (Yonei et al. [1993] Dev. Biol. 160:246-253). To evaluate the role of HGF in limb development, we observed the expression pattern of the HGF gene using in situ hybridization. The HGF gene was expressed in the mesoderm of the limb bud and in the central core region of mandibular arch and maxillary processes at stages 17 to 24. When both wing and leg buds begin to extend distally, the HGF gene is expressed in the mesenchymal cells, but not in the ectodermal cells and somites. Concomitant with establishment of the apical ectodermal ridge, distal mesenchymal cells of the limb bud express the HGF gene intensely with a gradient higher in the distal region. The HGF expression is later confined to the ventral and subapical mesenchyme of the limb bud, although no signal is detectable in the apical and non-ridge ectoderm. However, signal for the c-met proto-oncogene encoding the HGF receptor is not detectable in the limb bud at stages 17 to 24. These results suggest that HGF produced in the limb mesoderm may be involved in initial induction and maintenance of the apical ectoderm during limb development.

Gradient-index rod lens made by a double ion-exchange process.

Gradient-index rod lenses with a parabolic-index profile have been fabricated by a double Na-Ag ion-exchange process, and their optical characteristics have been evaluated. The numerical aperture and minimum focused spot diameter of the 2-mm diam rod lens were 0.58 and 2.5 microm for lambda = 0.63 microm, respectively. Because of the high diffusing rate for Ag ions, this technique offers the possibility of making large-sized (larger than 10 mm-diam) rod lenses for photographic uses.

130-km-long fault location for single-mode optical fiber using 1.55-microm Q-switched Er(3+):glass laser.

An optical-time-domain reflectometer has been constructed with a 1.55-microm Er(3+):glass laser, a TeO(2) acousto-optical directional coupler, and a cooled Ge P-I-N photodiode. With it, a maximum detectable fault-location length of 130 km for single-mode optical fiber has been successfully achieved at a 1.55microm wavelength.

Optical glass wave plates.

Permanent birefringence in excess of 300 nm/cm can be thermomechanically induced in the borosilicate optical glass ARG-2, making it an attractive alternative to natural crystalline quartz and mica for large-aperture wave-plate requirements in laser systems investigating inertial confinement fusion. The technique for fabricating glass wave plates is presented, including a detailed optical characterization of the uniformity of birefringence induced in glass plates. A comparison with other natural and synthetic candidate materials is made, and production scale-up problems are discussed.