Thermal behaviors during lithium diffusion in Li0.4WO3 bronze studied by elastic and quasi-elastic neutron scattering.

Polycrystalline Li0.4WO3 bronze has been synthesized by solid state reaction carried out in a silica tube at 10-7 MPa and 973 K. The sample is characterized by temperature-dependent neutron elastic and quasielastic scatterings. The room-temperature neutron powder data Rietveld refinement confirmed the space group Im3̄ along with lithium occupancy found predominantly at the 6b crystallographic site. Upon increasing temperature above 300 K lithium at 6b site decreases and at 2a site increases, suggesting Li+ cation diffusion between these two sites demonstrated by quasielastic neutron scattering as well. The lattice thermal expansion anomaly is observed between 380 K and 450 K, which is explained in terms of lithium dynamic disorder (non-equilibrium) as complemented by elastic and quasielastic neutron scatterings. DFT calculations with different lithium distributions at two different crystallographic sites guide to understand the lattice expansion anomaly. The lattice thermal expansion is modeled using Grüneisen first-order approximation, where the Debye-Einstein-Anharmonicity approach provides the temperature-dependent vibrational energy. The DFT-calculated phonon density of states and bulk modulus help extract the characteristic Debye and Einstein frequencies.

Histomorphometric and microarchitectural analysis of bone in metastatic breast cancer patients.

BACKGROUND: Despite widespread use of repeated doses of potent bone-targeting agents (BTA) in oncology patients, relatively little is known about their in vivo effects on bone homeostasis, bone quality, and bone architecture. Traditionally bone quality has been assessed using a trans-iliac bone biopsy with a 7 mm "Bordier" core needle. We examined the feasibility of using a 2 mm "Jamshidi™" core needle as a more practical and less invasive technique. METHODS: Patients with metastatic breast cancer on BTAs were divided according to the extent of bone metastases. They were given 2 courses of tetracycline labeling and then underwent a posterior trans-iliac trephine biopsy and bone marrow aspirate. Samples were analyzed for the extent of tumor invasion and parameters of bone turnover and bone formation by histomorphometry. RESULTS: Twelve patients were accrued, 1 had no bone metastases, 3 had limited bone metastases (LSM) (<3 lesions) and 7 had extensive bone metastases (ESM) (>3 lesions). Most of the primary tumors were estrogen receptor (ER)/progesterone receptor (PR) positive. The procedure was well tolerated. The sample quality was sufficient to analyze bone trabecular structure and bone turnover by histomorphometry in 11 out of 12 patients. There was a good correlation between imaging data and morphometric analysis of tumor invasion. Patients with no evidence or minimal bone metastases had no evidence of tumor invasion. Most had suppressed bone turnover and no detectable bone formation when treated with BTA. In contrast, 6 out of 7 patients with extensive bone invasion by imaging and evidence of tumor cells in the marrow had intense osteoclastic activity as measured by the number of osteoclasts. Of these 7 patients with ESM, 6 were treated with BTA with 5 showing resistance to BTA as demonstrated by the high number of osteoclasts present. 3 of these 6 patients had active bone formation. Based on osteoblast activity and bone formation, 3 out of 6 patients with ESM responded to BTA compared to all 3 with LSM. Compared to untreated patients, all patients treated with BTA showed a trend towards suppression of bone formation, as measured by tetracycline labelling. There was also a trend towards a significant difference between ESM and LSM treated with BTA, highly suggestive of resistance although limited by the small sample size. DISCUSSION: Our results indicate that trans-iliac bone biopsy using a 2 mm trephine shows excellent correlation between imaging assessment of tumor invasion and tumor burden by morphometric analysis of bone tissues. In addition, our approach provides additional mechanistic information on therapeutic response to BTA supporting the current clinical understanding that the majority of patients with extensive bone involvement eventually fail to suppress bone turnover (Petrut B, et al. 2008). This suggests that antiresorptive therapies become less effective as disease progresses.

KLi2RE(BO3)2 (RE = Dy, Ho, Er, Tm, Yb, and Y): Structural, Spectroscopic, And Thermogravimetric Studies on a Series of Mixed-Alkali Rare-Earth Orthoborates.

We report a detailed structural, spectroscopic, and thermogravimetric investigation of a new series of mixed-alkali rare-earth orthoborates KLi2RE(BO3)2 (RE = Dy, Ho, Er, Tm, Yb, and Y). Single crystals were directly prepared by a flux method as well as mechanically separated from the polycrystalline powder obtained from the conventional solid-state reactions. All KLi2RE(BO3)2 members are isotypic and crystallize in the space group P21/n. The novel structure type is comprised of [RE2(BO3)4O4]14- anionic clusters where the edge-sharing REO7 pentagonal bipyramids are connected by BO3 groups and both K+ and Li+ cations are located at the interstitial voids of the 3D network. The metric parameters and crystal structural features obtained from the single-crystal data are in excellent agreement with those refined from the powder data. The change of the lattice parameters and unit cell volumes can be explained in terms of the lanthanide contraction effect. A comparison between KLi2RE(BO3)2 and other rare-earth borates with similar chemical compositions indicates that the sum of the ionic radii of the alkali-metal cations governs the symmetry of the crystals. Diffuse reflectance UV-vis spectra display the characteristic absorption behaviors of the RE3+ cations and the fundamental absorption edge. Both the Tauc's and derivation of absorption spectrum fitting (DASF) methods were used to identify the magnitude and type of bandgap, respectively, which are compared with those obtained from density functional theory (DFT) calculations. The calculated phonon density of states and the vibrational frequency at the gamma point help explain the Fourier transform infrared and Raman spectra of KLi2RE(BO3)2. The incongruent melting behavior and the thermal stability of each member of the KLi2RE(BO3)2 series were also studied by thermogravimetric analyses.

Plasmodium chabaudi-infected mice spleen response to synthesized silver nanoparticles from Indigofera oblongifolia extract.

Malaria is a worldwide serious-threatening infectious disease caused by Plasmodium and the parasite resistance to antimalarial drugs has confirmed a significant obstacle to novel therapeutic antimalarial drugs. In this article, we assessed the antioxidant and anti-inflammatory activity of nanoparticles prepared from Indigofera oblongifolia extract (AgNPs) against the infection with Plasmodium chabaudi caused in mice spleen. AgNPs could significantly suppress the parasitaemia caused by the parasite to approximately 98% on day 7 postinfection with P. chabaudi and could improve the histopathological induced spleen damage. Also, AgNPs were able to increase the capsule thickness of the infected mice spleen. In addition, the AgNPs functioned as an antioxidant agent that affects the change in glutathione, nitric oxide and catalase levels in the spleen. Moreover spleen IL1ß, IL-6 and TNF-α-mRNA expression was regulated by AgNPs administration to the infected mice. These results indicated the anti-oxidant and the anti-inflammatory protective role of AgNPs against P. chabaudi-induced spleen injury.

Comparison between Outcomes of Endoscopic Sinus Surgery and Surgical Excision in Case of Rhinosporiodiosis.

Rhinosporiodiosis is a chronic granulomatous infection of the mucus membranes caused by Rhino sporidium seeberi that manifest as vascular friable polyps and arise in the nasal mucosa. The mode of infection is probably trans-epithelial penetration. Rhinosporiodiosis is endemic in India, Pakistan and Srilanka. It occurs sporadically in the United States of America. The aim of this study was to compare betweenthe outcomes of endoscopic sinus surgery andsurgical excision in rhinosporiodiosis. The cross sectional comparative study was conducted among 40 patients with rhinosporiodiosis from January 2018 to April 2019 in the department of Otolaryngology and Head-neck surgery of Mymensingh Medical College Hospital, Bangladesh. All the patients were following up to 6 month after surgery. Most of them are male 24(60.0%) and female are 16(40.0%). Age of the patients in this study was (Mean±SD) 34.8±13.5 years. More than half of the patients had rhinosporiodiosis in the inferior turbinate (25, 62.5%) followed by 8(20.0%) in nasal septum and 7(17.5%) in the nasal floor. Endoscopic Sinus Surgery was done purposively among 20 patients and surgical excision was done purposively among another 20 patients. At the time of operation no complication occurs in case of endoscopic sinus surgery but in case of surgical excision small of amount bleeding was present. All the patients were followed up to 6 month after surgery. No recurrence was found in patients with endoscopic sinus surgery but 7(35.0%) patients who underwent surgical excision had recurrence of rhinosporiodiosis at follow up after six months of surgery. Chi-square test showed that the incidence of recurrence after 6 months of surgery was significantly lower in endoscopic sinus surgery (p=0.004). The study results concluded that endoscopic sinus surgery is better option for rhinosporiodiosis.

Microbial fuel cell performance of graphitic carbon functionalized porous polysiloxane based ceramic membranes.

Proton-conducting porous ceramic membranes were synthesized via a polymer-derived ceramic route and probed in a microbial fuel cell (MFC). Their chemical compositions were altered by adding carbon allotropes including graphene oxide (GO) and multiwall carbon nanotubes into a polysiloxane matrix as filler materials. Physical characteristics of the synthesized membranes such as porosity, hydrophilicity, mechanical stability, ion exchange capacity, and oxygen mass transfer coefficient were determined to investigate the best membrane material for further testing in MFCs. The ion exchange capacity of the membrane increased drastically after adding 0.5 wt% of GO at an increment of 9 fold with respect to that of the non-modified ceramic membrane, while the oxygen mass transfer coefficient of the membrane decreased by 52.6%. The MFC operated with this membrane exhibited a maximum power density of 7.23 W m-3 with a coulombic efficiency of 28.8%, which was significantly higher than the value obtained using polymeric Nafion membrane. Hence, out of all membranes tested in this study the GO-modified polysiloxane based ceramic membranes are found to have a potential to replace Nafion membranes in pilot scale MFCs.

Structural, vibrational and electronic properties of SnMBO4 (M = Al, Ga): a predictive hybrid DFT study.

We propose two new members of the mullite-type family, SnAlBO4 and SnGaBO4, and carry out an in-depth study of their crystal properties using the hybrid method PW1PW. Both are isostructural to PbMBO4 (M = Fe, Mn, Al, Ga), which show axial negative linear compressibility (ANLC), among other interesting features. We find that, although Sn2+ is susceptible of being oxidized by oxygen, a suitable range of experimental parameters exists in which the compounds could be synthesized. We observe absence of ANLC below 20 GPa and explain it by the small space occupied by the lone electron pairs, as indicated by the small length of the corresponding Liebau Density Vectors. In agreement with this fact, the structures present a low number of negative mode-Grüneisen parameters, which may also suggest lack of negative thermal expansion. The electronic properties show a remarkable anisotropic behaviour, with a strong dependence of the absorption spectra on light polarization direction.

Free-standing supercapacitors from Kraft lignin nanofibers with remarkable volumetric energy density.

We have discovered a very simple method to address the challenge associated with the low volumetric energy density of free-standing carbon nanofiber electrodes for supercapacitors by electrospinning Kraft lignin in the presence of an oxidizing salt (NaNO3) and subsequent carbonization in a reducing atmosphere. The presence of the oxidative salt decreases the diameter of the resulting carbon nanofibers doubling their packing density from 0.51 to 1.03 mg cm-2 and hence doubling the volumetric energy density. At the same time, the oxidative NaNO3 salt eletrospun and carbonized together with lignin dissolved in NaOH acts as a template to increase the microporosity, thus contributing to a good gravimetric energy density. By simply adjusting the process parameters (amount of oxidizing/reducing agent), the gravimetric and volumetric energy density of the resulting lignin free-standing carbon nanofiber electrodes can be carefully tailored to fit specific power to energy demands. The areal capacitance increased from 147 mF cm-2 in the absence of NaNO3 to 350 mF cm-2 with NaNO3 translating into a volumetric energy density increase from 949 µW h cm-3 without NaNO3 to 2245 µW h cm-3 with NaNO3. Meanwhile, the gravimetric capacitance also increased from 151 F g-1 without to 192 F g-1 with NaNO3.

Nanoporous gold functionalized with praseodymia-titania mixed oxides as a stable catalyst for the water-gas shift reaction.

Dealloyed nanoporous metals hold great promise in the field of heterogeneous catalysis; however their tendency to coarsen at elevated temperatures or under catalytic reaction conditions sometimes limit further applications. Here, we report on a highly stable nanoporous gold catalyst (npAu) functionalized with praseodymia-titania mixed oxides as synthesized by a sol-gel method. Specifically, we used aberration-corrected transmission electron microscopy to study the morphology and the interface between the oxide deposits and the npAu substrate at the atomic level. Based on electron energy loss spectroscopy (EELS), it is concluded that Pr-TiOx mixed oxides form a solid solution. Flow reactor tests reveal that the Pr-TiOx functionalized nanoporous gold is not only highly active but also very stable for the water gas shift reaction in a large temperature range (180-400 °C). Our results demonstrate the potential of engineering the compositions of oxides coatings on npAu for advanced functional systems.

PHOSPHO1 is essential for normal bone fracture healing: An Animal Study.

OBJECTIVES: Bone fracture healing is regulated by a series of complex physicochemical and biochemical processes. One of these processes is bone mineralization, which is vital for normal bone development. Phosphatase, orphan 1 (PHOSPHO1), a skeletal tissue-specific phosphatase, has been shown to be involved in the mineralization of the extracellular matrix and to maintain the structural integrity of bone. In this study, we examined how PHOSPHO1 deficiency might affect the healing and quality of fracture callus in mice. METHODS: Tibial fractures were created and then stabilized in control wild-type (WT) and Phospho1-/- mice (n = 16 for each group; mixed gender, each group carrying equal number of male and female mice) at eight weeks of age. Fractures were allowed to heal for four weeks and then the mice were euthanized and their tibias analyzed using radiographs, micro-CT (µCT), histology, histomorphometry and three-point bending tests. RESULTS: The µCT and radiographic analyses revealed a mild reduction of bone volume in Phospho1-/- callus, although it was not statistically significant. An increase in trabecular number and a decrease in trabecular thickness and separation were observed in Phospho1-/- callus in comparison with the WT callus. Histomorphometric analyses showed that there was a marked increase of osteoid volume over bone volume in the Phospho1-/- callus. The three-point bending test showed that Phospho1-/- fractured bone had more of an elastic characteristic than the WT bone. CONCLUSION: Our work suggests that PHOSPHO1 plays an integral role during bone fracture repair and may be a therapeutic target to improve the fracture healing process.Cite this article: M. W. Morcos, H. Al-Jallad, J. Li, C. Farquharson, J. L. Millán, R. C. Hamdy, M. Murshed. PHOSPHO1 is essential for normal bone fracture healing: An Animal Study. Bone Joint Res 2018;7:397-405. DOI: 10.1302/2046-3758.76.BJR-2017-0140.R2.

Role of Matrix Gla protein in midface development: Recent advances.

Craniofacial development is a delicate process that involves complex interactions among cells of multiple developmental origins, their migration, proliferation, and differentiation. Tissue morphogenesis of the craniofacial skeleton depends on genetic and environmental factors, and on specific signaling pathways, which are still not well understood. Developmental defects of the midface caused by the absence, delays, or premature fusion of nasal and maxillary prominences vary in severity; leading to clefts, hypoplasias, and midline expansion. In the current review, we focus on the importance of the chondrocranium in craniofacial growth and how its impaired development leads to midface hypoplasia. More importantly, we reported how Matrix Gla protein (MGP), a potent inhibitor of extracellular matrix mineralization, facilitates midface development by preventing ectopic calcification of the nasal septum. In fact, MGP may act as a common link in multiple developmental pathologies all showing midface hypoplasia caused by abnormal cartilage calcification. This brief review discusses the gap in knowledge in the field, raises pertinent questions, which remain unanswered, and sheds light on the future research directions.

Steam reforming of methanol over oxide decorated nanoporous gold catalysts: a combined in situ FTIR and flow reactor study.

Methanol as a green and renewable resource can be used to generate hydrogen by reforming, i.e., its catalytic oxidation with water. In combination with a fuel cell this hydrogen can be converted into electrical energy, a favorable concept, in particular for mobile applications. Its realization requires the development of novel types of structured catalysts, applicable in small scale reactor designs. Here, three different types of such catalysts were investigated for the steam reforming of methanol (SRM). Oxides such as TiO2 and CeO2 and mixtures thereof (Ce1Ti2Ox) were deposited inside a bulk nanoporous gold (npAu) material using wet chemical impregnation procedures. Transmission electron and scanning electron microscopy reveal oxide nanoparticles (1-2 nm in size) abundantly covering the strongly curved surface of the nanoporous gold host (ligaments and pores on the order of 40 nm in size). These catalysts were investigated in a laboratory scaled flow reactor. First conversion of methanol was detected at 200 °C. The measured turn over frequency at 300 °C of the CeOx/npAu catalyst was 0.06 s-1. Parallel investigation by in situ infrared spectroscopy (DRIFTS) reveals that the activation of water and the formation of OHads are the key to the activity/selectivity of the catalysts. While all catalysts generate sufficient OHads to prevent complete dehydrogenation of methanol to CO, only the most active catalysts (e.g., CeOx/npAu) show direct reaction with formic acid and its decomposition to CO2 and H2. The combination of flow reactor studies and in operando DRIFTS, thus, opens the door to further development of this type of catalyst.

Cholinergic regulation of bone.

Bone remodeling is regulated by the two branches of the autonomic nervous system: the adrenergic and the cholinergic branches. Adrenergic activity favors bone loss, whereas cholinergic activity has been recently shown to favor bone mass accrual. In vitro studies have reported that cholinergic activity induces proliferation and differentiation of bone cells. In vivo studies have shown that the inhibition of cholinergic activity favors bone loss, whereas its stimulation favors bone mass accrual. Clinical studies have shown that bone density is associated with the function of many cholinergic-regulated tissues such as the hypothalamus, salivary glands, lacrimal glands and langerhans cells, suggesting a common mechanism of control. Altogether, these observations and linked findings are of great significance since they improve our understanding of bone physiology. These discoveries have been successfully used recently to investigate new promising therapies for bone diseases based on cholinergic stimulation. Here, we review the current understanding of the cholinergic activity and its association with bone health.

Local regulation of tooth mineralization by sphingomyelin phosphodiesterase 3.

Sphingomyelin phosphodiesterase 3 (Smpd3) encodes a membrane-bound enzyme that cleaves sphingomyelin to generate several bioactive metabolites. A recessive mutation called fragilitas ossium (fro) in the Smpd3 gene leads to impaired mineralization of bone and tooth extracellular matrix (ECM) in fro/fro mice. In teeth from fro/fro mice at various neonatal ages, radiography and light and electron microscopy showed delayed mantle dentin mineralization and a consequent delay in enamel formation as compared with that in control +/fro mice. These tooth abnormalities progressively improved with time. Immunohistochemistry showed expression of SMPD3 by dentin-forming odontoblasts. SMPD3 deficiency, however, did not affect the differentiation of these cells, as shown by osterix and dentin sialophosphoprotein expression. Using a transgenic mouse rescue model (fro/fro; Col1a1-Smpd3) in which Smpd3 expression is driven by a murine Col1a1 promoter fragment active in osteoblasts and odontoblasts, we demonstrate a complete correction of the tooth mineralization delays. In conclusion, analysis of these data demonstrates that Smpd3 expression in odontoblasts is required for tooth mineralization.

Histomorphometric and microarchitectural analyses using the 2 mm bone marrow trephine in metastatic breast cancer patients-preliminary results.

BACKGROUND: Bone-targeted agents are widely used for the treatment of osteoporosis, the prevention of cancer-therapy induced bone loss, and for reducing the risk of skeletal related events in patients with metastatic disease. Despite widespread use, relatively little is known about the in vivo effect of these agents on bone homeostasis, bone quality, and bone architecture in humans. Traditionally bone quality has been assessed using a transiliac bone biopsy with a 7 mm "Bordier" core needle. We examined the possibility of using a 2 mm "Jamshidi" core needle as a more practical and less invasive method to assess bone turnover and potentially other tumor effects. METHODS: A pilot study on the feasibility of assessing bone quality and microarchitecture and tumor invasion using a 2 mm bone marrow trephine was conducted. Patients underwent a posterior trans-iliac trephine biopsy and bone marrow aspirate. Samples were analyzed for bone microarchitecture, bone density, and histomorphometry. The study plan was to accrue three patients with advanced breast cancer to assess the feasibility of the study before enrolling more patients. RESULTS: The procedure was well tolerated. The sample quality was excellent to analyze bone trabecular microarchitecture using both microCT and histomorphometry. Intense osteoclastic activity was observed in a patient with extensive tumor burden in bone despite intravenous bisphosphonate therapy. DISCUSSION: Given the success of this study for assessing bone microarchitecture, bone density, and histomorphometry assessment using a 2 mm needle the study will be expanded beyond these initial three patients for longitudinal assessment of bone-targeted therapy.

Src family kinase/abl inhibitor dasatinib suppresses proliferation and enhances differentiation of osteoblasts.

Dasatinib, a dual Src family kinase and Abl inhibitor, is being tested clinically for the treatment of prostate cancer bone metastasis. Bidirectional interactions between osteoblasts and prostate cancer cells are critical in the progression of prostate cancer in bone, but the effect of dasatinib on osteoblasts is unknown. We found that dasatinib inhibited proliferation of primary mouse osteoblasts isolated from mouse calvaria and the immortalized MC3T3-E1 cell line. In calvarial osteoblasts from Col-luc transgenic mice carrying osteoblast-specific Col1alpha1 promoter reporter, luciferase activity was inhibited. Dasatinib also inhibited fibroblast growth factor-2-induced osteoblast proliferation, but strongly promoted osteoblast differentiation, as reflected by stimulation of alkaline phosphatase activity, osteocalcin secretion and osteoblast mineralization. To determine how dasatinib blocks proliferative signaling in osteoblasts, we analyzed the expression of a panel of tyrosine kinases, including Src, Lyn, Fyn, Yes and Abl, in osteoblasts. In the Src family kinases, only Src was activated at a high level. Abl was expressed at a low level in osteoblasts. Phosphorylation of Src-Y419 or Abl-Y245 was inhibited by dasatinib treatment. Knockdown of either Src or Abl by lenti-shRNA in osteoblasts enhances osteoblast differentiation, suggesting that dasatinib enhances osteoblast differentiation through inhibition of both Src and Abl.

Kinetics of methane-ethane gas replacement in clathrate-hydrates studied by time-resolved neutron diffraction and Raman spectroscopy.

The kinetics of CH(4)-C(2)H(6) replacement in gas hydrates has been studied by in situ neutron diffraction and Raman spectroscopy. Deuterated ethane structure type I (C(2)H(6) sI) hydrates were transformed in a closed volume into methane-ethane mixed structure type II (CH(4)-C(2)H(6) sII) hydrates at 5 MPa and various temperatures in the vicinity of 0 degrees C while followed by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. The role of available surface area of the sI starting material on the formation kinetics of sII hydrates was studied. Ex situ Raman spectroscopic investigations were carried out to crosscheck the gas composition and the distribution of the gas species over the cages as a function of structure type and compared to the in situ neutron results. Raman micromapping on single hydrate grains showed compositional and structural gradients between the surface and core of the transformed hydrates. Moreover, the observed methane-ethane ratio is very far from the one expected for a formation from a constantly equilibrated gas phase. The results also prove that gas replacement in CH(4)-C(2)H(6) hydrates is a regrowth process involving the nucleation of new crystallites commencing at the surface of the parent C(2)H(6) sI hydrate with a progressively shrinking core of unreacted material. The time-resolved neutron diffraction results clearly indicate an increasing diffusion limitation of the exchange process. This diffusion limitation leads to a progressive slowing down of the exchange reaction and is likely to be responsible for the incomplete exchange of the gases.

Kinetic studies of methane-ethane mixed gas hydrates by neutron diffraction and Raman spectroscopy.

In situ formations of CH(4)-C(2)H(6) mixed gas hydrates were made using high flux neutron diffraction at 270 K and 5 MPa. For this purpose, a feed gas composition of CH(4) and C(2)H(6) (95 mol% CH(4)) was employed. The rates of transformation of spherical grains of deuterated ice Ih into hydrates were measured by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. Phase fractions of the crystalline constituents were obtained from Rietveld refinements. A concomitant formation of structure type I (sI) and structure type II (sII) hydrates were observed soon after the gas pressure was applied. The initial fast formation of sII hydrate reached its maximum volume and started declining very slowly. The formation of sI hydrate followed a sigmoid growth kinetics that slowed down due to diffusion limitation. This observation has been interpreted in terms of a kinetically favored nucleation of the sII hydrate along with a slow transformation into sI. Both powder diffraction and Raman spectroscopic results suggest that a C(2)H(6)-rich sII hydrate was formed at the early part of the clathration, which slowly decreased to approximately 3% after a reaction of 158 days as confirmed by synchrotron XRD. The final persistence of a small portion of sII hydrate points to a miscibility gap between CH(4)-rich sI and C(2)H(6)-rich sII hydrates.

Matrix Gla protein inhibition of tooth mineralization.

Extracellular matrix (ECM) mineralization is regulated by mineral ion availability, proteins, and other molecular determinants. To investigate protein regulation of mineralization in tooth dentin and cementum, and in alveolar bone, we expressed matrix Gla protein (MGP) ectopically in bones and teeth in mice, using an osteoblast/odontoblast-specific 2.3-kb Col1a1 promoter. Mandibles were analyzed by radiography, micro-computed tomography, light microscopy, histomorphometry, and transmission electron microscopy. While bone and tooth ECMs were established in the Col1a1-Mgp mice, extensive hypomineralization was observed, with values of unmineralized ECM from four- to eight-fold higher in dentin and alveolar bone when compared with that in wild-type tissues. Mineralization was virtually absent in tooth root dentin and cellular cementum, while crown dentin showed "breakthrough" areas of mineralization. Acellular cementum was lacking in Col1a1-Mgp teeth, and unmineralized osteodentin formed within the pulp. These results strengthen the view that bone and tooth mineralization is critically regulated by mineralization inhibitors.

Cartilage formation and calcification in arteries of mice lacking matrix Gla protein.

Matrix Gla protein (MGP/Mgp) is a protein expressed predominantly by vascular smooth muscle cells (VSMCs) and by chondrocytes. Transgenic mice lacking Mgp die 1-3 months after birth due to calcification of elastic fibers and rupture of large elastic arteries such as the aorta. Here, we report on cartilage formation that commonly occurs in calcified arteries of Mgp-/- mice. Using histology, von Kossa staining, immunohistochemistry, and Western blotting, together with examination of cellular markers for VSMCs and extracellular matrix markers for cartilage, we provide evidence for cell transformation from VSMC to chondrocyte in the arterial media in the absence of Mgp. At 2 weeks of age in the aorta of Mgp-/- mice, VSMCs lose immunostaining for smooth muscle alpha-actin concomitant with the appearance of cartilage molecules as shown by immunohistochemical staining and Western blotting for aggrecan, link protein, and type II collagen. These data provide evidence that the absence of Mgp, and/or calcification of the ECM, in the arterial media can trigger chondrocyte differentiation and cartilage formation in blood vessels.