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Biomedical subjects

D Deutsch

Publications and source records attributed to D Deutsch.

At least 73 records · Page 4Linked to original sources
PubMed1984

Changes in size, morphology and weight of human anterior teeth during the fetal period.

The changes in size and weight of the calcified portions of the crowns of deciduous anterior teeth (maxillary and mandibular central and lateral incisors and canines) in human fetuses aged 5-10 months were studied. Relating the weight and size of each tooth to fetal age provided quantitative information on the rate of crown development in each of these teeth. There is a good correlation between crown height and fetal age. At the corresponding ages the length of the maxillary central incisor is greater than that of the maxillary lateral incisor which is greater than that of the maxillary canine. A similar pattern is found in the mandibular teeth. Generally, with the exception of a few mandibular central incisors, no type of anterior tooth crown has reached its final length before birth.

Female↗
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

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

Neutral peptidase activities in matrix vesicles from bovine fetal alveolar bone and dog osteosarcoma.

Extracellular matrix vesicles from bovine fetal alveolar bone and from a dog osteosarcoma were isolated by differential centrifugation and then fractionated on a discontinuous sucrose density gradient. The fractions were examined by electron microscopy and were analyzed for protein, alkaline phosphatase, aminotripeptidase, and four different beta-naphthylamidase activities. The low-density peak of enzyme activities was shown by electron microscopy to be much more homogeneous than the crude matrix vesicle fraction. Two major peaks of protein and enzyme activities were present, one in the high and one in the low density layers. There was good correlation between the activities of alkaline phosphatase and the various peptidases in the fractions from the sucrose density gradient. These results indicate a coexistence of peptidase and alkaline phosphatase in matrix vesicles. On the other hand, there was generally no correlation between the peptidase and alkaline phosphatase activities in vesicular specimens from bovine liver obtained in the same way. Most of the peptidase activity and about half of the alkaline phosphatase activity were solubilized from bone matrix vesicles by detergents. The extracted alkaline phosphatase and alanyl beta-naphthylamidase activities were separated from each other on a DEAE-cellulose column.

Alkaline Phosphatase↗
PubMed1983

The octave illusion in relation to handedness and familial handedness background.

The octave illusion is produced by a dichotic sequence of tones that alternate in frequency between 400 and 800 Hz, such that when the right ear receives 400 Hz the left ear receives 800 Hz; and vice versa. Most listeners obtain the illusion of a single high tone in one ear alternating with a single low tone in the other ear. Further, most right-handers hear the high tone on the right and low tone on the left. The present study examined localization patterns in this illusion as a function of handedness and also of familial handedness background. The effect of handedness was highly significant: the tendency to hear the high tone on the right and the low tone on the left was lower among mixed handers and left-handers than among right-handers. The effect of familial handedness background was also highly significant: the tendency to hear the high tone on the right and the low tone on the left was lower among those with a sinistral familial background than among those with a purely dextral familial background. These findings are discussed in relation to the hypothesis that perception of the illusion serves as a reflection of the direction of cerebral dominance in most individuals.

Adult↗
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↗
PubMed1982

Occurrence of actin-like protein in extracellular matrix vesicles.

Preliminary indications of the occurrence of actin and myosin in crude matrix vesicle preparations have been reported previously. In the present study extracellular matrix vesicles from rat alveolar bone were isolated. They were further purified by a sucrose density gradient. SDS-polyacrylamide gel electrophoresis of the purified vesicles revealed the presence of a polypeptide with a molecular weight of 43 K daltons and with electrophoretic mobility identical to that of blood platelet actin. The limited proteolysis of both 43 K dalton vesicular polypeptide and actin by Staphylococcus aureus-V8-protease revealed three fragments with identical electrophoretic mobility. In addition, the vesicular preparations inhibited the activity of DNase I, a property typical of actin monomers. Filamentous material extracted from matrix vesicles showed ultrastructuraL features of F-actin. Reaction of this material with heavy meromyosin resulted in arrowhead formation, which is characteristic of acto-heavy meromyosin. The occurrence of actin in extracellular matrix vesicles may account for their budding from the osteoblastic plasma membrane, their possible motility in the matrix, and maintenance of the spherical shape.

Actins↗
PubMed1982

Fluoride deposition in the bones of rats determined by fluoride and X-ray diffraction analysis.

Rats were given drinking water containing up to 300 parts/10(6) F and the conversion of hydroxyapatite to fluoridated apatite was estimated chemically and by X-ray diffraction. The differences of the mean fluoride uptakes from the very different concentrations of fluoride given were significant. Prolonged washing of the bones with demineralized water released 5-10 per cent from the fluoride uptake. Formation of fluoridated apatite was evident by decreases in the a parameter of the hydroxyapatite phase. In the washed bones, there was no appreciable transformations in the a parameters. The co-existence of Mg-containing beta-Ca3(PO4)2 with the apatite phase was detected in heated bone samples. The amount of beta-Ca3(PO4)2, its dependence on the age of the bones and its Mg content are interdependent.

Animals↗
PubMed1982

Development of enamel in human fetal teeth.

The present study concerns enamel development in human fetal teeth. Chemical analysis and the appearance of developing enamel from maxillary and mandibular central and lateral incisors of human fetuses aged from five to nine mo distinguished two main stages during this period of development. The first stage corresponded to the production of forming enamel, which was soft, translucent, and partially mineralized, and the second to the maturation or secondary mineralization of enamel. The enamel at this stage appeared opaque when dried. The transition of forming enamel to maturing enamel was accompanied by a decrease in protein concentration, a distinct change in amino-acid composition, and a rise in the concentration of calcium and phosphate. Ultraviolet and chloronaphthalene inhibition studies revealed that the third and final stage in enamel development, the mature hard enamel, was generally absent, but was found in a very small percentage of maxillary and mandibular central incisors from nine- and ten-month-old fetuses, at the incisal tip. In both maxillary and mandibular canine teeth, only the forming stage in enamel development was observed during the fetal period. Further studies relating the length of each zone in enamel to fetal age provided information relative to the timing and rate of enamel development in each tooth.

Amelogenesis↗
PubMed1981

Purification and further characterization of isolated matrix vesicles from rat alveolar bone.

Extracellular matrix vesicles from rat alveolar bone were isolated by collagenase digestion and differential centrifugation. Further purification was performed by discontinuous sucrose density gradient centrifugation. Control tissues, kidney and liver, were processed according to the same procedures. Sucrose density gradient centrifugation of bone matrix vesicles revealed two peaks of enzymatic activity: "light" and "heavy" vesicle-enriched fractions. Electron micrographs revealed a higher degree of purification of the "light" rather than the "heavy" vesicle-enriched fraction. This coincided with the high levels of enzymatic activity detected in this fraction. Preparations obtained from kidney and liver had significantly lower levels of activity of alkaline phosphatase and ATPase as compared to the bone matrix vesicle fractions. There were also differences in the positions of enzyme activity peaks in the sucrose gradient fractions from the three tissues studied. Electron microscopic examination of kidney and liver fractions revealed structures larger than the purified bone matrix vesicles. In addition no electron-dense material was found within organelles from kidney and liver and they were studded with numerous ribosomes. Our observations indicate that the present method of isolation and purification yields fractions of matrix vesicles which are specific to bone and are significantly different from those obtained from kidney and liver.

Acid Phosphatase↗