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Biomedical subjects

I Bab

Publications and source records attributed to I Bab.

At least 55 records · Page 3Linked to original sources
PubMed1986

Mineralization in in vitro cultures of rabbit marrow stromal cells.

Localized regions of mineralization were found in confluent cultures of rabbit marrow fibroblastic cells. The mineralized tissue developed within clusters of giant fat cells in the spaces between the cells. Investigations with light and electron microscopy demonstrated that in these sites there was some differentiation of the fibroblastic cells in an osteogenic direction, shown by changes to more polygonal shapes, and the synthesis of well-banded collagen similar to that found in bone tissue. Differentiation may be due, in part, to increased cell density in a confined space. Growth of the mineralized tissue was observed in the living cultures with a fluorescence microscope. Electron probe microanalysis confirmed that the mineral formed was hydroxyapatite. Initiating sites of mineralization included membranous vesicular bodies, lipid, and products of cellular degeneration. Once initiated, mineralization appeared to spread rapidly into adjacent collagenous and other structures, suggesting the appearance of a mixture of skeletal-type and dystrophic mineralization.

Animals↗
PubMed1986

Histomorphometric evaluation of reversible heparin-induced osteoporosis in pregnancy.

Transilial bone biopsy confirmed heparin-induced osteopenia in a 23-year-old postpartum patient. Histomorphometric measurements during the reversible stage of bone disease that followed discontinuation of the heparin sodium therapy revealed signs of recovery; these were superimposed on a loose trabecular structure typical of osteoporosis. The histomorphometric evidence of recovery correlated well with signs of clinical improvement. In the majority of patients, heparin therapy during pregnancy is innocuous; however, discontinuation of treatment is recommended at the earliest signs of osteoporosis.

Adult↗
PubMed1985

Hereditary hypophosphatemic rickets with hypercalciuria.

We studied a new hereditary syndrome of hypophosphatemic rickets and hypercalciuria in six affected members of one kindred. In all patients, the manifestations of disease began in early childhood. The characteristic features are rickets, short stature, increased renal phosphate clearance (the ratio between the maximal tubular reabsorption rate for phosphorus and the glomerular filtration rate [TmP/GFR] is 2 to 4 S.D. below the age-related mean), hypercalciuria (8.6 mg of urinary calcium per kilogram of body weight per 24 hours vs. the upper normal value of 4.0), normal serum calcium levels, increased gastrointestinal absorption of calcium and phosphorus, an elevated serum concentration of 1,25-dihydroxyvitamin D (390 +/- 99 pg per milliliter vs. the upper normal value of 110), and suppressed parathyroid function (an immunoreactive parathyroid hormone level of 0.33 +/- 0.1 ng per milliliter and a cyclic AMP level of 1.39 +/- 0.12 nmol per deciliter of glomerular filtrate vs. the lower normal values of 0.3 and 1.5, respectively). Long-term phosphate supplementation as the sole therapy resulted in reversal of all clinical and biochemical abnormalities except the decreased TmP/GFR. We propose that the pivotal defect in this syndrome is a renal phosphate leak resulting in hypophosphatemia with an appropriate elevation of 1,25-dihydroxyvitamin D levels, which causes increased calcium absorption, parathyroid suppression, and hypercalciuria. This syndrome may represent one end of a spectrum of hereditary absorptive hypercalciuria. Our observations support the importance of phosphate as a mediator in controlling 1,25-dihydroxyvitamin D production in human beings.

Calcium↗
PubMed1985

Removal of tibial marrow induces increased formation of bone and cartilage in rat mandibular condyle.

The present paper reports alterations in osteogenesis recorded in mandibular condyles 3-18 days after the removal of marrow tissue from tibial bones. Computerized histomorphometric evaluation of undecalcified condyles revealed a considerable increase in the thickness of condylar cartilage, in particular, the zone of provisional calcification. Measurements of the subcartilaginous trabecular bone suggested an increase in the number of osteoblasts and in their activity. The systemic enhancement of osteogenesis may be initiated by circulating factors released at the affected limb during regeneration of the marrow.

Animals↗
PubMed1985

Calcification of non-collagenous matrix in human gingiva: a light and electron microscopic study.

Tissue samples obtained from human gingiva with soft tissue calcification were processed for light and transmission electron microscopy. The stroma in these specimens revealed numerous foci of calcification in a matrix that consisted of closely packed branching microfibrils, 12 nm in diameter and a maximum of 2.5 micron in length. Calcospherites, 0.25-1.11 micron in diameter, were present within the matrix. They were constructed of needle-like units shown by high resolution electron microscopy and energy dispersive X-ray microanalysis to be apatite. Larger calcified masses were composed of calcospherites which were fused together. Matrix vesicles or other forms of membraneous material could not be found. The relationship between the mineral and non-collagenous microfibrils may suggest a role for the latter in the onset of calcification in this ectopic site.

Amelogenesis Imperfecta↗
PubMed1985

Respiratory failure and multiple fractures in vitamin D-dependent rickets.

A 20-month-old boy presented with multiple fractures and respiratory failure. He was found to have vitamin D-dependent rickets. The rickets did not improve with phosphate, calcium and calciferol. The rickets healed, however, with large doses of 1-alpha-hydroxycholecalciferol. The presentation is unusual and the response to therapy suggests metabolic heterogeneity in vitamin D-dependent rickets.

Bone Resorption↗
PubMed1985

Vitamin D-dependent rickets types I and II. Diagnosis and response to therapy.

The diagnostic value of measuring serum vitamin D metabolites is demonstrated in the present study in which two patients with vitamin D-dependent rickets (VDDR) Types I and II are reported. The patient with sporadic VDDR Type I was severely disabled and unable to walk. Her serum 1,25(OH)2D level was low (32 pg/ml, normal 30 to 60) and she responded dramatically to 1 microgram of 1 alpha-hydroxyvitamin D3 daily. The VDDR Type II patient had an autosomal recessive inheritance and total alopecia. His serum 1,25(OH)2D level was greater than 500 pg/ml, compatible with end-organ refractoriness to 1,25(OH)2D. He did not respond to daily doses of 1 microgram 1 alpha-hydroxyvitamin D3. These cases demonstrate the striking difference in 1,25(OH)2D levels and therapeutic response to 1,25(OH)2D in these two conditions.

Adult↗
PubMed1984

Assessment of an in vivo diffusion chamber method as a quantitative assay for osteogenesis.

The alkaline phosphatase activity and the calcium and phosphorus content of osteogenic tissue formed in vivo following the implantation of diffusion chambers loaded with rabbit bone marrow cells is reported. (In this study the term osteogenic includes osteoblastic and chondroblastic.) Chambers examined 14-70 days after implantation revealed progressive accumulation of mineral. Alkaline phosphatase activity increased until day 30 and declined thereafter. The osteogenic potential of the marrow cells decreased with increasing weight (age) of the cell donor rabbit when measured either as the percentage of chambers containing osteogenic tissue or as the amount of calcium, phosphorus, or alkaline phosphatase activity within the chambers. The results confirm that measurements of these parameters in tissue formed by cells incubated in diffusion chambers in vivo may be used as a method for assay of osteogenesis.

Alkaline Phosphatase↗
PubMed1984

Distribution of fibroblastic colony-forming cells in rabbit bone marrow and assay of their osteogenic potential by an in vivo diffusion chamber method.

Rabbit bone marrow has been separated into core, intermediate, and endosteal cell populations. When plated out in vitro, each of the fractions gave rise to colonies of fibroblastic cells. The colony-forming efficiency increased from the core population by a factor of 4 to a maximum of 3.4 X 10(-6) in the endosteal fraction. The osteogenic potential of each fraction was determined following their implantation in diffusion chambers into host rabbits. Each of the indices of osteogenesis (alkaline phosphatase activity, Ca and P accumulation) were significantly lower in the core population than in the two populations closer to the bone surface. Our results are consistent with the hypothesis that the osteogenic precursor cells of marrow belong to the fibroblast colony-forming cell fraction, and indicate that these cells, although found throughout the marrow, are concentrated close to the bone surface.

Alkaline Phosphatase↗
PubMed1984

A study of a sample of oral cancer in Israel.

A review of data on oral cancer in Israel revealed a lower incidence and a later onset age than in other countries. These data are reviewed and consideration is given to the high prevalence of smoking and the low incidence of alcoholism in Israel.

Adolescent↗
PubMed1984

Incident light microscopy of surfaces of plastic embedded hard tissues.

To eliminate sectioning artefacts, we devised a method for the preparation of surfaces of plastic embedded hard tissues and their examination by incident light fluorescence microscopy. Flat surfaces produced by cutting on a microtome or using a low-speed saw were stained with dyes in aqueous solutions. Best results were obtained in tissues embedded in glycol-methacrylate. This polymer allowed good penetration of the dyes and its optical properties render cutting defects invisible with the present method. The relationship between hard and soft tissues was well preserved and the integrity of the mineralized component maintained. Cellular details and the distinction between osteoid and bone could be clearly/demonstrated. The procedure is simple, rapid and produces good results even in instances when histological sectioning is unsatisfactory.

Animals↗
PubMed1983

Extracellular matrix vesicles in rat bone after parathyroidectomy.

The enzymatic activity of bone matrix vesicles from parathyroidectomized rats was determined and compared to the activity of vesicles from sham operated and normal animals. The vesicles were isolated from the alveolar bone by collagenase digestion and differential centrifugation and further purified on a discontinuous sucrose density gradient. The amount of extractable protein and the activity of alkaline phosphatase, acid phosphatase, and ATPase in the vesicle fractions thus obtained did not differ significantly from the values characteristic of preparations from control rats. It may therefore be suggested that parathyroid hormone depletion and the associated hypocalcemia have no significant effect on the occurrence and phosphatase activity of bone matrix vesicles.

Acid Phosphatase↗
PubMed1983

Primary mineralization in the interface between bone and methyl methacrylate implants in rat mandibles. A correlative light and scanning and transmission electron microscope study.

Self curing polymethylmethacrylate implants were administered into rat mandibular bone. Tissue reaction was studied after different periods with light microscopy and transmission and scanning electron microscopy. Formation of fibrous tissue in the interface between implant and bone was associated with initial bone resorption and followed by the occurrence of primary calcification in a collagen rich matrix after 4-8 weeks. The features of primary mineralization comprised appearance of hydroxyapatite crystals within matrix vesicles and formation of calcospheritic structures. The occurrence of calcifying fronts after the intraosseous administration of polymethylmethacrylate suggests a favourable relationship between bone and the implant material.

Animals↗
PubMed1983

Correlative morphometric and biochemical analysis of purified extracellular matrix vesicles from rat alveolar bone.

Extracellular matrix vesicles were isolated from rat alveolar bone and purified by either gel filtration or discontinuous sucrose density gradient. Morphometric evaluation of electron-micrographs of pellets of purified and nonpurified vesicle fractions was correlated with the activity of vesicular enzymes. A high correlation was found between the percentage of area occupied by vesicles with electron-dense content (electron-dense vesicle fractional area) and the enzymatic activity. Highest enzymatic specific activities and electron-dense vesicle fractional area were recorded in the "light" vesicle-enriched fraction obtained after equilibrium density centrifugation. These parameters revealed lowest values in the "heavy" vesicle-enriched fraction resolved by the same methods. The combined electron-dense and electron-lucent fractional area (vesicular fractional area) was similar in the different purified fractions. It is therefore suggested that the fraction obtained by gel filtration contains both "light" and "heavy" vesicles. Morphometric study is proposed as an additional criterion for the degree of purification of matrix vesicle preparations.

Acid Phosphatase↗
PubMed1983

Primary calcification in remodeling haversian systems following tibial fracture in rats.

Electron micrographs of fracture callus obtained ten days after injury show typical primary matrix vesicle mineralization. In remodeling haversian canals distant from the fracture sites, matrix vesicles and calcifying nodules were observed. The occurrence of these elements was also found to control unfractured tibiae with intramedullary nails but not normal bone. These observations suggest that during haversian remodeling, mineralization after osseous or marrow tissue damage is associated with matrix vesicles.

Animals↗
PubMed1982

Effect of X-ray irradiation on primary mineralization in rat alveolar bone.

The effect of X-ray irradiation on the process of primary mineralization in bone was studied by biochemical and ultrastructural methods. A single dose of 1500R was administered to the head region of rats. The animals were examined immediately after irradiation and 1, 2 and 3 weeks later. Fractions of isolated cells and extracellular matrix vesicles were prepared from the maxillary alveolar bone of irradiated and untreated rats by collagenase digestion and differential centrifugation. The protein content and activities of vesicular phosphatases were determined in both fractions. A continuous decrease in the activity of alkaline phosphatase could be observed in both cell and matrix vesicle fractions during a three-week follow up after irradiation. Acid phosphatase activity decreased only in the vesicle fraction. Transmission electron microscopy of irradiated bone tissue revealed that many matrix vesicles were devoid of intact membranes and apatite crystals. Calcifying nodules were abundant in the matrix without their apparent fusion into larger mineralized structures. It is suggested that irradiation interferes with enzymatic processes associated with primary mineralization.

Alveolar Process↗