Biomedical subjects

G Vujicić

Publications and source records attributed to G Vujicić.

5 recordsLinked to original sources

PubMed1991

Distribution of structural and trace elements in human temporal bone.

This study was undertaken to evaluate a systematic analysis of mineral and trace elements of individual functionally determined parts of adult temporal bone. Marked differences were observed in basic structural elements (Ca, P, Mg, and Zn) among different bone regions. The more so, molar Ca/P ratio was significantly different in various regions, being highest in the hammer and vestibular regions. Taxonomic analysis revealed specific differences in the mineral ratio between the two petrous bone regions believed to develop from various embryonal bases. According to results, the observed differences in mineral trace element composition of particular regions of human temporal bone might be explained by their developmental specificities and functional adaptation.

Adult↗

PubMed1991

Holographic analysis of the human pelvis.

Twelve fresh human pelves with preserved lumbar spines, hip joints, and ligaments, were tested by double-exposure and sandwich-hologram interferometry. During physiologic loadings (50-300 N), the pelvis moved as a whole downward and backward. Iliac wings exhibited marked undulation, except for the central part, which showed minor deformations. The sacrum moved downward and rotated forward over an axis 5-9 cm below the promontorium. Removal of the sacroiliac interosseous ligaments eliminated all joint movements and caused a tighter contact between articular surfaces. Removal of the sacrotuberous and sacrospinous ligaments had no influence on the pelvic behavior. The magnitudes of deformations as well as their underlying mineral contents were unequally distributed between the two pelvic sides. These results indicate that the sacroiliac interosseous ligaments are the main determinant of sacral movement. Asymmetric load transmittance to the hip joints might be responsible for the mineral content differences between the pelvic sides.

Adult↗

PubMed1989

Effects of parathyroidectomy on tissue calcium, phosphorus, magnesium, and copper concentrations in aluminum-loaded uremic rats.

Rats were subjected to a two-stage 5/6 nephrectomy and treated with Al for 2 and 4 wk with a cumulative dose of 4.2 and 8.4 mg of Al, respectively. Other animals were parathyrectomized (PTx) and loaded with 8.4 mg of Al for 4 wk. Total Al, Ca, P, Mg, and Cu contents were analyzed in the liver, kidney, and bone by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that Al given to growing uremic rats significantly increased the content of Al in the liver, kidney, and bone. Moreover, Al treatment increased the liver and kidney Ca levels and decreased the Ca and P values in bone. Previous parathyroidectomy significantly reduced Al accumulation within organs and changes in the Ca and P levels in the bone, liver, and kidney. The result was not influenced by different degrees of renal failure.

Aluminum↗

PubMed1986

The influence of 1 alpha,25- and 24(R),25-dihydroxyvitamin D3 on bone constituents during early mineralization in the rat.

The influence of vitamin D metabolites on intramuscular implants of bone matrix in rachitic rats was investigated. Recipient rats with rickets were injected daily with 1 alpha,25(OH)2D3,24(R),25(OH)2D3 or a combination of both metabolites. The presence of 1 alpha,25(OH)2D3 increased significantly the alkaline phosphatase activity, and slightly increased the activity of acid phosphatase. 24(R),25(OH)2D3 had no effect on the activity of the measured enzymes. The results of inductively coupled plasma emission spectrometric determination of bone elements revealed that: (a) 1 alpha,25(OH)2D3 stimulated the incorporation of magnesium and decreased the phosphorus content of bone implants when compared with rats given both vitamin D metabolites; (b) 1 alpha,25(OH)2D3 as well as 24(R),25(OH)2D3 had antagonistic effects on bone carbonate content. The values for 1 alpha,25(OH)2D3 treated animals were significantly higher, and 24(R),25(OH)2D3 treated rats had a significantly lower carbonate content of implants when compared to the controls. Time-dependent CO2-liberation diagrams indicated a differently bound bone carbonate in 1 alpha,25(OH)2D3 treated rats; (c) when plotted against time, the diagrams for both the values for zinc and the activity distribution of the measured enzymes had a similar appearance, indicating zinc incorporation into bone enzymes during early mineralization. It is concluded that 24(R),25(OH)2D3 should not be compared to 1,25(OH)2D3 on the basis of the same effects, since other effects of 24(R),25(OH)2D3 on the developing bone exist, opposite to those of 1,25(OH)2D3; and these could be important for protecting bone from different agents and in determining the nature of early mineral deposited.

24,25-Dihydroxyvitamin D 3↗

PubMed1985

1a,25-Dihydroxyvitamin D3 stimulates alkaline phosphatase activity and inhibits soft-tissue proliferation in implants of bone matrix.

To test the importance of vitamin D metabolites on intramuscular implants of demineralized bone, four-month-old rats were given either 1a,25-(OH)2D3 or 24R,25-(OH)2D3, or a combination of both metabolites, and sacrificed at intervals ranging from five to 35 days after implantation. Histologically there was a reduced ingrowth of mesenchymal cells into the implanted matrix cylinders in the presence of 1a,25-(OH)2D3; the reduction was followed by decreased total DNA and protein values until the 16th experimental day. At 35 days postimplantation, the quantity of new bone was the same in all treated groups. However, 1a,25-(OH)2D3 increased the alkaline phosphatase activity 60%-110% (depending on the denominator used). The metabolite 24R,25-(OH)2R3 had no effect on cell growth or the alkaline phosphatase activity. These results provide evidence for the inhibitory effect of 1a,25-(OH)2D3 on mesenchymal cell growth and its stimulatory effect on osteoblasts, which are responsible for increased alkaline phosphatase activity and new bone formation in vivo.

24,25-Dihydroxyvitamin D 3↗