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Biomedical subjects

E Bonucci

Publications and source records attributed to E Bonucci.

At least 91 records · Page 5Linked to original sources
PubMed1989

Experimental aluminum intoxication and parathormone: effects on the mineralization process.

In order to study the effect of aluminum intoxication on bone and bone cells in normal animals and its relationship with hyperparathyroidism, and so to obtain further data on a pathogenetic role of this condition in inducing osteomalacia in uremic patients, 31 rats divided in four groups were injected intraperitoneally for 11 weeks with: Al (75.6 mg); Al-PTH (Al = 75.6 mg + PTH = 200 USP during the last week); C (saline solution), and C-PTH (saline solution + PTH = 200 USP during the last week). Al injection induced a consistent increase in the element in serum and tibia. PTH administration further enhanced Al content in tibia. The trabecular bone surfaces of Al-administered rats were stained by aluminon; the endosteal borders of their compact bone were always negative. Rib histomorphometry showed absence of osteomalacia in Al group and increase in osteoid in Al-PTH group, with development of mild osteomalacia. In these groups osteoclasts were less numerous than in controls. Dynamic bone parameters showed no separation of double tetracycline labels in trabecular bone of both Al-administered groups. Cortical bone was only slightly affected by treatment. All these data indicate that Al alone, in the quantity administered, does not induce osteomalacia in normal rats and that PTH, although given for a few days, enhances Al content in bone and induces osteoid increment. The reduction of tetracycline labels in all Al-treated animals is due to reduction of calcification and formation rate, which might be an index of osteoblast inhibition. The decrease in the number of osteoclasts suggests that Al might inhibit their formation.

Aluminum↗
PubMed1989

Bone aluminum content in predialysis chronic renal failure and its relation with secondary hyperparathyroidism and 1,25(OH)2D3 treatment.

32 patients with slowly evolving predialysis chronic renal failure, who were not exposed to aluminum-containing antacids, were studied. A low aluminum intake was considered a useful condition to examine the bone deposition of the element as dependent variable, not interfering with PTH secretion and bone metabolism. Iliac bone biopsies for bone aluminum content and histomorphometric and histodynamic evaluations were taken. Serum aluminum, creatinine, calcium, phosphate, iPTH, osteocalcin (BGP), alkaline phosphatase (AP), 25-OHD3 and 1,25(OH)2D3 were also measured. 16 of the patients were on long-term treatment with 1,25(OH)2D3 (0.25 micrograms daily) for prevention and treatment of secondary hyperparathyroidism. Bone aluminum content of all patients showed a strong positive correlation with BGP and iPTH (p less than 0.001) while the correlation with serum creatinine was not significant. Multiregression analysis has singled out BGP as the most predictive variable of bone aluminum content (r2 = 0.419). The patients receiving 1,25(OH)2D3 had lower iPTH (p less than 0.01), lower bone aluminum content (p less than 0.05) and increased mineral apposition rate (p less than 0.05) compared to the untreated group. The results suggest that treatment with 1,25(OH)2D3 for long-term suppression of secondary hyperparathyroidism does not enhance aluminum accumulation in bone. The finding of lower bone aluminum together with increased mineral apposition rate, seems to indicate that 1,25(OH)2D3 is able to induce an osteoid mineralization process more selective against aluminum incorporation in bone than in case of more severe hyperparathyroidism and 1,25(OH)2D3 deficiency. At least in the present condition of low aluminum intake, 1,25(OH)2D3 may be considered to have protective effects on bone from aluminum deposition.

Adult↗
PubMed1988

Immunohistochemical localization of osteonectin in developing human and calf bone using monoclonal antibodies.

Osteonectin was immunolocalized in human fetal and calf neonatal developing bone using newly developed monoclonal antibodies. The protein was localized to the cytoplasm of osteoblasts and young osteocytes. In bone matrix, strong reactivity was found in newly laid down osteoid. Bone matrix immunoreactivity was enhanced by pretreatment of sections with proteases, possibly because of an unmasking of epitopes engaged in protein-protein interactions. Osteonectin immunoreactivity was also found in preosteoblasts in all types of human fetal osteogenesis (membranous, endochondral, subperiosteal, and mantellar (Meckel's cartilage) ossification), and in some chondrocytes of metaphyseal growth plate, possibly modulating towards an osteoblastic phenotype.

Alkaline Phosphatase↗
PubMed1988

Alkaline phosphatase positive precursors of adipocytes in the human bone marrow.

Developing fat cells in the bone marrow of leukaemic patients treated with chemotherapy were found to be endowed with membrane-bound alkaline phosphatase. Since alkaline phosphatase is a cytochemical marker of 'reticular' cells, this observation provides cytochemical evidence that reticular cells may convert to adipocytes when marrow cellularity abruptly decreases.

Acute Disease↗
PubMed1988

The ultrastructure of the organic phase associated with the inorganic substance in calcified tissues.

An organic phase is closely associated with the mineral substance is all calcified matrices, where it can be demonstrated as crystal-bound proteins by biochemical methods and as crystal ghosts by electron microscopy. Interest in crystal ghosts derives chiefly from the observation that they have the same shape, arrangement, and orientation as inorganic crystallites, which suggests they may have a role in their formation. Histochemically, crystal ghosts of epiphyseal cartilage react with colloidal iron (pH 2.0), acidic phosphotungstic acid, ruthenium red, and a number of cations including calcium, barium, magnesium, lanthanum, strontium, and terbium chloride. Their reactivity is removed by methylation and only incompletely restored by saponification. Moreover, the crystal ghosts located at the periphery of the calcified areas contain vic-glycol groups, as shown by their reactivity with periodic acid-silver nitrate and periodic acid-thiosemicarbazide-osmium. All these reactions show that the crystal ghosts of epiphyseal cartilage contain acidic, probably sulfate groups and, at least initially, vic-glycol groups. Their reactivity decreases as the calcification process is completed. Although the available data are not sufficient to allow a full understanding of the nature and function of these structures, they seem to play an important role in calcification. The hypothesis is presented that crystal ghosts are preformed in calcifying matrices and are activated by the unmasking of the reactive groups in their polymeric molecule; the unmasked groups then link up with inorganic ions in such a way to form organic-inorganic structures the inorganic ions of which are arranged in an apatitelike configuration and the filamentlike shape of which is the same as that of the polymeric molecule.

Animals↗
PubMed1988

Improved bone morphology by normalizing serum magnesium in chronically hemodialyzed patients.

The dialysate magnesium concentration (dMg) was reduced from 1 to 0.5 mEq/l in a group of patients on chronic hemodialysis (RDT). Serum parameters and bone biopsy findings were evaluated before and after a 1-year period on the lower dMg. All patients were receiving only calcium carbonate before and during the study period. Serum magnesium (sMg) decreased significantly and fell in the normal range with low dMg, whereas the other serum parameters did not change significantly except serum phosphorous which increased, still remaining within the normal limits. Furthermore, a significant reduction of the osteomalacia pattern (evaluated by osteoid volume, osteoid surface and osteoid thickness index) was observed in all patients after 1 year on dMg of 0.5 mEq/l, whereas there was no significant variation in bone resorption patterns (resorption surface and osteoclasts). Therefore, normal sMg is recommended in RDT patients, by arranging their dMg according to individual need, in the hypothesis that high bone Mg content, attributed to hypermagnesemia, could interfere with the mineralization process.

Adult↗
PubMed1988

Aluminum bone content in dialysis osteodystrophy with secondary hyperparathyroidism.

To assess whether parathyroid hormone (PTH) has any effect on bone aluminium (A1) accumulation, we evaluated the relationship between bone quantitative histomorphometry and bone A1 content in 25 dialysis patients with clinical features of secondary hyperparathyroidism. By means of bone biopsy, patients were classified as showing predominant hyperparathyroidism in 17 cases and mixed lesions in 8. The A1 burden was low, judging from the dialysate A1 and the oral A1 assumption. Bone A1 content and serum A1 levels were higher than normal in both groups, particularly so in the patients with predominant hyperparathyroidism. Significant positive correlations were found between bone indexes of hyperparathyroidism and bone A1 content. Moreover, bone and serum A1 concentrations were directly related. Aluminium staining appeared faintly positive only in a minority of bone samples, and was mainly localized at the neutral bone surfaces. We conclude that in dialysis osteodystrophies with features of secondary hyperparathyroidism and in a clinical setting characterized by low-grade A1 burden, PTH may favour A1 accumulation into the bone.

Adult↗
PubMed1987

Is there a calcification factor common to all calcifying matrices?

This paper reviews the principal morphological findings pertinent to the early phases of the calcification process and explores the possibility that there may be a calcification factor common to all calcifying matrices. Three structures have a main role in calcification: collagen fibrils, matrix vesicles, and crystal ghosts. Only crystal ghosts are present in all calcified tissues, so that only they can be taken into consideration as a common calcification factor. They are organic molecules which have the same morphology as that of the inorganic structures present in the calcified matrix, which means that they can be considered as templates for those structures. Early calcification might be initiated by the binding of calcium and phosphate ions to the unmasked reactive groups of the crystal ghosts which are probably contained not only in the matrix, but also in the "holes" of the collagen fibrils and in matrix vesicles. The available data suggest that crystal ghosts share many of the properties of "crystal bound proteins". The involvement of alkaline phosphatase in their composition may account for their calcium- and phosphate-binding activity.

Bone Matrix↗
PubMed1987

Expression of tartrate-resistant acid phosphatase in bone marrow macrophages.

Bone marrow macrophages were found to express tartrate-resistant acid phosphatase (TRAP) under pathological conditions. In chronic granulocytic leukemia and metastatic carcinoma in the bone marrow this phenomenon was striking, all or almost all of the marrow macrophages being reactive. In other conditions, such as hypertransfusion or chemotherapy-induced marrow aplasia, the phenomenon did occur but was clearly a minor one. These observations indicate that tissue macrophages may become TRAP positive under the effect of unknown stimuli operating in certain pathological conditions. The results further suggest that the synthesis of the isoenzyme of acid phosphatase resistant to tartrate inhibition is a marker of macrophage activation rather than of differentiation towards particular subsets of the mononuclear phagocyte system.

Acid Phosphatase↗
PubMed1987

Exogenous calcitonin protects against renal bone disease in rats with early renal failure.

Chronic renal failure was induced in four groups of male Sprague-Dawley rats by unilateral nephrectomy followed by removal of the outer poles and cautery of the remnant kidney. The four groups of animals received isocaloric diets with normal (groups 1 and 4) or low (groups 2 and 3) phosphate contents and variable amounts of calcium. In addition, rats in group 4 were given salmon calcitonin. After 90-160 days the 4 groups of rats had developed comparable levels of chronic renal failure. The serum phosphate values were significantly lower in rats on low phosphate intake than in those on normal phosphate diet. Bone histology was evaluated on tibiae, lumbar vertebrae and ribs. The rats kept on low phosphate diet (groups 2 and 3) had significantly lower frequency of osteomalacia and bone resorption than those fed a normal phosphate diet. Rats treated with calcitonin (group 4) had the lowest frequency of osteomalacia and virtually no association with bone resorption, despite normal phosphate intake. The serum levels of parathyroid hormone were not significantly different in rats in groups 1 and 4 as compared to controls. Serum 1,25-dihydroxycholecalciferol levels were significantly lower in group 1 than in controls and were significantly higher in group 4 than in group 1. These data show that calcitonin effectively prevents bone lesions in rats with early chronic renal failure.

Animals↗
PubMed1987

Relationship between serum vitamin D metabolites and dietary intake of phosphate in patients with early renal failure.

Serum vitamin D metabolites and their relationship with dietary intake of phosphate were evaluated in 41 adult patients with early renal failure (glomerular filtration rate [GFR] 50 +/- 12 ml/min). On free diet, mean serum levels of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] were reduced and were a function of GFR and dietary intake of phosphate (beta-weight coefficients were 0.69 and -0.49, respectively). Serum levels of 24, 25(OH)2D3 were comparable to controls and were significantly correlated with serum 25(OH)D3 concentrations only. After 29 +/- 2 months of phosphate restricted (700 mg), calcium supplemented (1,300-1,800 mg) diet, serum phosphate and parathyroid hormone (PTH) levels were unchanged and serum calcium, 1,25(OH)2D3 and 24,25(OH)2D3 concentrations significantly increased in those patients whose GFR did not change. On the other hand, serum PTH increased and serum vitamin D metabolites remained persistently low in those patients whose GFR declined to 12 +/- 5 ml/min. A retrospective analysis of bone histology in 234 patients with chronic renal failure showed that in early renal failure (GFR 75-31 ml/min) the prevalence of osteomalacia and bone resorption was reduced by phosphate restriction (12 vs. 33%, p less than 0.05, and 12 vs. 28%, p = not significant, respectively). In advanced renal failure (GFR 30-10 ml/min), phosphate restriction reduced the prevalence of osteoclastic bone disease (17 vs. 61%, p less than 0.001), but did not change that of osteomalacia (35 vs. 32%, not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Adult osteopetrosis: study of two brothers.

Bone biopsies from 2 adult cases of benign osteopetrosis have been studied histologically and under the electron microscope. The most important findings were a high degree of osteosclerosis, narrowing and fibrosis of medullary spaces, and the presence of abundant uncalcified osteoid tissue with an osteomalacia-like appearance. The osteoclasts were not numerous. All of them lacked the brush border and many showed wide cytoplasmic vacuoles containing amorphous and filamentous material. This picture, which is not different from that found in cases of fetal osteopetrosis, has not been modified by ethydronate therapy.

Biopsy↗
PubMed1986

Biochemical and immunohistochemical evidence that in cartilage an alkaline phosphatase is a Ca2+-binding glycoprotein.

A glycoprotein that exhibits alkaline phosphatase activity and binds Ca2+ with high affinity has been extracted and purified from cartilage matrix vesicles by fast protein liquid chromatography. Antibodies against this glycoprotein were used to analyze its distribution in chondrocytes and in the matrix of calcifying cartilage. Under the light microscope, using immunoperoxidase or immunofluorescence techniques, the glycoprotein is localized in chondrocytes of the resting zone. At this level, the extracellular matrix does not show any reaction. In the cartilage plate, between the proliferating and the hypertrophic region, a weak immune reactivity is seen in the cytoplasm, whereas in the intercolumnar matrix the collagen fibers appear clearly stained. Stained granular structures, distributed with a pattern similar to that of matrix vesicles, are also visible. Calcified matrix is the most stained area. These results were confirmed under the electron microscope using both immunoperoxidase and protein A-gold techniques. In parallel studies, enzyme activity was also analyzed by histochemical methods. Whereas resting cartilage, the intercellular matrix of the resting zone, and calcified matrix do not exhibit any enzyme activity, the zones of maturing and hypertrophic chondrocytes are highly reactive. Some weak reactivity is also shown by chondrocytes of the resting zone. The observation that this glycoprotein (which binds Ca2+ and has alkaline phosphatase activity) is synthesized in chondrocytes and is exported to the extracellular matrix at the time when calcification begins, suggests that it plays a specific role in the process of calcification.

Alkaline Phosphatase↗
PubMed1986

Some histochemical observations on Gaucher cells.

Plastic-embedded bone marrow biopsies from four patients with Gaucher's disease have been studied histochemically. Concanavalin A (ConA) was found to bind to cytoplasmic inclusions of Gaucher cells; the binding was prevented by lipid extraction or beta-glucosidase digestion. This suggests that glucocerebrosides stored in Gaucher cells are responsible for ConA binding; ConA staining combined with lipid extraction and beta-glucosidase digestion tests may be taken as a tool for the demonstration of Gaucher's cerebrosides of possible practical importance in diagnosis and investigation of Gaucher's disease. An excess of vic-glycol groups with respect to ConA binding-sugar residues and not extractable by lipid solvents are demonstrable in Gaucher cells. Vic-glycols appear to be regularly arranged at the electron microscopy level within Gaucher cell lysosomes along typical Gaucher "tubules", where some kind of interaction between lipid and protein should occur. Acid phosphatase might be one protein species involved in such interaction.

Acid Phosphatase↗