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This manuscript considers certain aspects of mineral deposition in bone and other vertebrate calcifying tissues in order to examine physical, chemical, and biological factors important in the mineralization process. The paper in a discussion format principally presents a new data and the formulation of concepts based on such data as well as a summary of background material as necessary review. Mineralization is found to occur at spatially independent sites throughout the organic extracellular tissue matrices. Matrix vesicles and collagen fibrils each may serve as independent nucleation centers for mineral with vesicle mineralization being local and collagen mineralization dominating the tissues as a whole. Collagen fibril organization is suggested to be such that hole zones are aligned in three dimensions, creating extensive channels for mineral accommodation. Nucleation occurs initially in hole zones and crystal growth leads to the development of plate-like mineral particles whose orientation, disposition, and sizes within fibrils are detailed. Effects of diffusion, crystallinity, and critical nucleation and growth events are described with respect to their influence on mineral deposition in bulk and local regions of tissue matrices.
Anat Rec 1991 Aug
PMID:A contribution with review to the description of mineralization of bone and other calcified tissues in vivo. 192 50

Experimental agents administered systemically are costly and often toxic to animals. An in vivo technique has been developed whereby a surgical window in the alveolar bone allows selected areas of the rat incisor enamel organ and underlying enamel to be exposed to various drugs, radiolabeled molecules, and molecular weight markers. Sherman rats weighing 100 gm were anesthetized and the inferior surface of each hemimandible was surgically exposed. A slow-speed dental hand drill was used to drill a small hole through the alveolar bone overlying the secretion or maturation zones of the enamel organ. The wound was closed and during recovery the mechanical trauma to the underlying tissue moved away from the hole due to the continuous eruption of the tooth. Two to 5 days later the hole was reexposed and microinjections of 3H-proline, 125I-salmon calcitonin, vinblastine sulphate, and normal saline (as control) were administered through the hole with a micromanipulator and a microliter syringe. Radioautographic detection of 3H-proline incorporation in secretory ameloblasts and enamel at 10 minutes, 30 minutes, 1 hour, 4 hours, 1 day, and 2 days after microinjection was identical to that obtained previously by systemic injection. Two hours after microinjection of vinblastine sulphate the cellular response was again identical to that following systemic injection; 125I-salmon calcitonin (M.W. approximately 3,600D) was used as a molecular weight marker and was seen to diffuse into the enamel of the maturation zone at 10 minutes after microinjection. This study has demonstrated the feasibility of this new technique for experimentation on rat incisor enamel organs.
Anat Rec 1984 Dec
PMID:In vivo experimentation on rat incisor enamel organs through a surgical window. 639 23

Incubation of skin in 2 N sodium bromide allows separation of dermal and epidermal layers leaving an intact basal lamina covering the dermal portion. Examination of the surface of the dermis by SEM shows cells migrating through the basal lamina. By scanning and transmission electron microscopy, these cells have the characteristics of lymphocytes. The migrating lymphocytes produce a sequence of basal lamina deformations including dome formation, effacement of corrugations, and central fenestrations with hole formation allowing lymphocyte passage. Following passage there is reestablishment of a relatively smooth basal lamina in the crater base, effacement of the crater rim, and finally reformation of basal lamina corrugations. This deformability of the basal lamina supports the hypothesis that basal lamina is thixotropic. This study is the first demonstration in three dimensions of lymphocyte traffic across the basal lamina, an important component of skin-associated lymphoid tissue (SALT).
Anat Rec 1984 Mar
PMID:Migration of lymphocytes through the cutaneous basal lamina in normal skin: an ultrastructural study. 672 Dec 30

To establish the mode of fertilization in a marsupial, a morphological investigation was made of the gametes of the South American grey short-tailed opossum. Monodelphis domestica, at the time of fertilization in vivo and in vitro. Oestrus was induced in females by the introduction of an unfamiliar male. To obtain oocytes recently fertilized in vivo, females were killed 18-24 hours after the first mating and the region of the oviduct containing eggs excised and fixed. Unfertilized mature oocytes were recovered from ovarian follicles 15-18 hours after first mating and fertilized in vitro with cauda epididymal spermatozoa in a modified MEM medium supplemented with bovine serum albumin at 37 degrees C in 5% CO2 in air. Following sperm-egg binding and fertilization, oocytes were fixed and prepared for light and electron microscopy. Spermatozoa unpaired prior to fertilization in vivo and in vitro and single spermatozoa bound to the zona surface by their plasmalemma overlying the acrosome on the dorsal face of the sperm head. The acrosome reaction was only observed at the zona surface (suggesting that it may be induced by zona components) and involved a vesiculation of sperm plasma and acrosomal membranes over the main body of the acrosome but not over the narrow, marginal region which persisted after the acrosome reaction was complete. Sperm penetration of the zona pellucida caused a large breach in the zona and the dispersal of perivitelline material. The fusion of the spermatozoon with the oolemma occurred first over the marginal acrosomal region and was accompanied by a fertilization cone which protruded through the zona penetration hole. Activation of the egg was characterized by the release of material from vesicles in the peripheral cytoplasm and extrusion of the second polar body. The mode of fertilization in Monodelphis was compared with what is known in other marsupials (New World and Australian) and eutherian (placental) mammals. It was concluded that the general features of the acrosome reaction and sperm-egg fusion may be essentially similar in both groups and that an evolutionary schism did not occur following the development of the eutherian mode of fertilization.
Anat Rec 1993 Sep
PMID:Ultrastructural characteristics of in vivo and in vitro fertilization in the grey short-tailed opossum, Monodelphis domestica. 821 40

A carpus valgus deformity was diagnosed in a five-week-old Brown Swiss calf. The 45 degrees deformity was caused by the malaligned healing of a fracture of the left metacarpus after birth trauma. The deviation improved to 25 degrees after being treated with a semicircular lateral periosteotomy above the distal physis of the radius. A complete correction was made by means of a wedge osteotomy five months after the first treatment. A 20 degrees wedge of bone was removed. The metacarpus was stabilised with a seven-hole dynamic compression plate which was removed 12 weeks later. Thirty months later the calf was sold as a pregnant heifer at an auction of breeding cattle.
Vet Rec 1995 Sep 02
PMID:Angular limb deformity in a calf treated by periosteotomy and wedge osteotomy. 853 16

The periosteum contains osteoprogenitors that differentiate to osteoblasts in bone growth or repair. Our previous studies suggested the hypothesis that the physical contact of the periosteum with the bone matrix is requisite for the differentiation of osteoblasts. To test the hypothesis, the present study was designed to investigate how the contact between the periosteum and the bone matrix influences the osteoblastic differentiation of periosteal cells with establishing a new experimental model in vivo. Differentiation of osteoblasts was assessed by gene expression of type I collagen, osteocalcin and bone sialoprotein using in situ hybridization. A barrier was designed to prevent periosteal cells from contacting the bone matrix using the membrane filter. The membrane filter was inserted surgically between the surface of rat parietal bone and the periosteum after being punched out with pin holes. Periosteal cells were allowed to contact with the bone surface only through the pin holes. The pin hole was filled with cells derived from the periosteum 1 week after inserting the filter. Differentiation of osteoblasts in week 2 and noticeable bone formation in week 3 were identified on the bone surface only under the pin hole but not under the filter. The present study demonstrated that the physical contact with the bone matrix promotes osteoblastic differentiation of periosteum-derived cells in vivo.
Anat Rec 2001 09 01
PMID:Osteoblastic differentiation of periosteum-derived cells is promoted by the physical contact with the bone matrix in vivo. 1150 73

To elucidate the effects of enamel matrix derivative (EMD: Emdogain) on bone regeneration in rat femurs after drill-hole injury, defects in bone were filled with either EMD or its carrier, PGA, as control. On postoperative days 4 to 28, dissected femurs were examined by means of various morphological approaches. In both experimental groups, formation of trabecular bone, which was immunostained for bone sialoproteins (BSP), had occurred in the medullary cavities at cylindrical bone defects on Day 7 postoperatively. Cuboidal osteoblasts were clearly observed on these newly-formed BSP-positive bone trabeculae. On Days 7 and 14, many multinucleated giant cells, which strongly expressed cathepsin K, had appeared on these bone trabeculae, indicating active bone remodeling. In these bone trabeculae, Ca and P weight % and Ca/P ratio were similar to those of cortical bone, and there was no significant difference between the PGA- and EMD-applied groups. Bone volume fraction of newly-formed bone trabeculae on Day 7 postoperatively was significantly higher in the EMD-applied group than in the PGA-applied controls. Because of active bone remodeling and the marked decrease of bone volume, on Days 14 and 28 postoperatively, however, there was no longer a significant difference in trabecular bone volume fraction between the experimental groups. Our results suggest that EMD possesses an osteo-promotive effect on bone and medullary regeneration during wound healing of injured long bones.
Anat Rec 2001 12 01
PMID:Porcine enamel matrix derivative enhances trabecular bone regeneration during wound healing of injured rat femur. 1174 98

We examined atomic force microscopy (AFM) and lateral force microscopy (LFM) images of human, avian, reptilian, amphibian, and piscine erythrocytes to determine whether the general pattern of erythrocyte membrane architecture has been largely conserved in the course of phylogenetic evolution or relatively minor modifications have taken place. The general pattern of the cell surface structure is indeed very similar among the phyla examined. The surface features include a number of blebs or globular structures and hole-like depressions. Such features are particularly clear in fish (Heteropneustes sp.), in which globular blebs are arranged in tiers around the depressions. The same pattern is found in the other phyla, although the sizes of the blebs and depressions vary. The depressions are approximately 340 and approximately 100 nm in diameter in chickens and fish, respectively, and are smaller in other phyla. The images of human erythrocytes presented here show holes more clearly than the images obtained by Zhang et al. (Scanning Electron Microsc., 1995; 9:981-989), who showed for the first time the highly uneven surface of these cells. The globules range in size from approximately 50-150 nm in diameter. These nanostructures have a width of approximately 333-1,000 atoms, assuming that the average dimension of an atom is 1.5 A. The size range of the holes is approximately 40-432 nm (equivalent to a width of approximately 266-2880 atoms). LFM images, which take into account the lateral component of the force, represent the variation of surface friction (roughness) on the erythrocyte surface. This is very clear in the toad images, which show well-ordered strata that have not been revealed in ordinary AFM images.
Anat Rec A Discov Mol Cell Evol Biol 2004 Jul
PMID:Atomic force microscopic studies on erythrocytes from an evolutionary perspective. 1522 8

Binary mixtures of the molecular glass former 2-picoline in oligostyrene, in which the dielectric response of 2-picoline exhibits a particularly broad distribution of correlation times, are investigated by nonresonant dielectric hole-burning (NDHB) spectroscopy and the results are compared with NDHB in neat systems, in particular, glycerol. It turns out that in both substance classes spectral selectivity is achieved, which indicates that dynamics is heterogeneous, i.e., slow and fast responses coexist in the material. However, in binary systems the position of the spectral modifications is completely determined by the spectral density of the pump field, and thus shifts linearly with burn frequency as expected, also at pump frequencies around the alpha-relaxation maximum. It is shown that in binary systems the lifetime tau(rec) of the spectral modifications is determined by the burn frequency omega(p) and exceeds its inverse by about one order of magnitude, indicating long-lived dynamic heterogeneity. The data are described in terms of a previously suggested model of dynamically selective heating, which was extended to include intrinsic nonexponential relaxation. It turns out that the spectral broadening in binary mixtures is not only due to pronounced dynamic heterogeneity, but partially also due to intrinsic broadening of the relaxation function.
 ...
PMID:Nonresonant dielectric hole burning in neat and binary organic glass formers. 1597 95

The synthesis and characterization of octavinylsilsesquioxane (OVS)-based nanocomposite dendrimers with luminescent and charge transport properties are reported. The nanocomposite dendrimers were prepared in high yield using mild Heck chemistry of mono-haloaromatic compounds with the peripheral vinylsilane groups of OVS. Attachment of 2-naphthalene, 2-(9,9-dimethyl)fluorene, and 2-(4-phenyl)-5-(1-naphthyl)-1,3,4-oxadiazole resulted in materials with blue-violet emission (360-380 nm) and photo-luminescent quantum efficiencies (PLQEs) from 1 to 26%. Blue-green emission was observed for attachment of 1-pyrene, 9-anthracene, and N1-(4-phenyl)-N1,N4,N4-triphenylbenzene-1,4-diamine with PLQEs ranging from 23 to 50%. Despite the planar characteristics of the organic dendrons, the nanocomposite dendrimers are completely amorphous and have high glass transition temperatures (Tg) ranging from 115 to 186 degrees C with decomposition temperatures (Td) exceeding 450 degrees C. Matrix-assisted laser desorption ionization-time of flight shows that unlike traditional Heck chemistry, haloaromatic compounds are adding twice across the vinylsilane groups. Finally, organic light emitting diodes using the aromatic amine-based dendrimer as hole injection layers show 55% improvement in device efficiency over traditional materials (5.16 vs. 3.24 cd A(-1)) with brightness levels exceeding 40,000 cd m(-2).
Chem Rec 2006
PMID:Silsesquioxane-based nanocomposite dendrimers with photo-luminescent and charge transport properties. 1679 8


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