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Biomedical subjects

E Canalis

Publications and source records attributed to E Canalis.

At least 163 records · Page 9Linked to original sources
PubMed1985

Characterization of the effect of insulin on collagen synthesis in fetal rat bone.

We characterized the effect of insulin on collagen synthesis in 21-day-old fetal rat calvaria maintained in organ culture. All experiments were done in the presence of 100 mg/dl glucose and 3 mM phosphate, which were found to be optimal concentrations for insulin responsiveness. All concentrations of insulin tested (1 nM to 1 microM) increased the percentage of collagen being synthesized in the central bone, whereas only high concentrations of hormone (100 nM to 1 microM) increased the percentage of collagen being synthesized in periosteum. Insulin at 3 nM increased the labeling of type I collagen in the central bone, but did not alter the labeling of type I or III collagen in the periosteum. Proinsulin was approximately 10-100 times less effective than insulin in stimulating collagen synthesis, whereas porcine relaxin and C-peptide were ineffective. Insulin did not enhance the deposition of newly synthesized collagen in the bone by a mechanism that involved decreasing the degradation of collagen. To determine whether insulin enhanced collagen synthesis by increasing the replication of collagen-synthesizing cells, we tested the effect of insulin in the presence of hydroxyurea, a DNA synthesis inhibitor. Hydroxyurea at 1 mM had little effect on collagen synthesis in control cultures or those treated with 1 or 10 nM insulin. However, hydroxyurea blunted the stimulation of collagen synthesis that occurred at higher concentrations of insulin. These experiments suggest that insulin at physiological levels appears to increase bone collagen synthesis by a direct effect on the osteoblast, whereas insulin at high concentrations has an additional action to increase the replication of collagen-synthesizing cells.

Animals↗
PubMed1985

Effect of sodium vanadate on deoxyribonucleic acid and protein syntheses in cultured rat calvariae.

Sodium vanadate, an agent known to have multiple cellular actions, was studied for its effects on aspects of bone formation in cultures of 21-day-old fetal rat calvariae. Vanadate (0.1-10 microM) stimulated the incorporation of [3H] thymidine into acid-insoluble residues (DNA); the effect appeared after 3 h and was sustained for 96 h. Vanadate increased the bone DNA content and mitotic index. Treatment with vanadate at 10 microM for 24 h or at 0.3-1 microM for 96 h increased the incorporation of [3H]proline into collagenase-digestible protein (CDP), but the effect was not specific for collagen; vanadate also increased the labeling of noncollagen protein (NCP). Vanadate increased the incorporation of [3H]proline into type I collagen without affecting other collagen types. Vanadate (100 microM) caused a marked and irreversible inhibitory effect on the labeling of DNA, CDP, and NCP. Treatment with vanadate at multiple doses for 3-96 h did not stimulate alkaline phosphatase activity, but this enzyme was inhibited in bones exposed to 1 mM vanadate for 24 h or 10 microM vanadate for 96 h. The stimulatory effect on DNA labeling was primarily observed in the periosteum, while that on CDP labeling was seen only in the periosteum-free bone. These studies indicate that sodium vanadate stimulates bone DNA, collagen, and NCP syntheses in vitro, although high doses of vanadate have an irreversible inhibitory effect.

1-Methyl-3-isobutylxanthine↗
PubMed1985

Effect of growth factors on bone cell replication and differentiation.

Bone formation is a process regulated by effects on bone cell replication and on differentiated function, which is primarily represented by changes in bone collagen synthesis. The effects of hormones on bone formation have been reviewed extensively, and this article describes the effects of systemic and local growth factors. Systemic growth factors, such as epidermal growth factor and fibroblast growth factor, stimulate cell replication in skeletal and nonskeletal tissues but inhibit differentiated function; platelet-derived growth factor stimulates cell replication and generalized protein synthesis by differentiated cells. The only systemic factor that simultaneously stimulates bone cell replication and differentiation is insulinlike growth factor, or somatomedin. The growth of skeletal and nonskeletal tissues also appears to be regulated by locally synthesized factors. Bone contains an autologous bone-derived growth factor that stimulates bone collagen and DNA synthesis, while cartilage contains a somatomedinlike peptide that stimulates cartilage growth. Other noncollagenous bone proteins, such as osteonectin and osteocalcin, might have a role in mineralization, but, as yet, they have not been reported to have a definite effect on bone formation. Bone also contains prostaglandins and local regulators of bone resorption, while the macrophage, an osteoclast-related cell, releases peptides that stimulate bone formation in vitro. In conclusion, bone formation is a complex process regulated not only by hormones but also by systemic and local growth factors.

Animals↗
PubMed1985

Effect of partially purified bone morphogenetic protein on DNA synthesis and cell replication in calvarial and fibroblast cultures.

The effects of bone morphogenetic protein (BMP), a molecule extracted from demineralized bone, were observed in organ cultures of 21-day fetal rat calvariae. The effects of BMP on cell replication in cultures of normal rat kidney (NRK) fibroblasts were studied for comparison. At concentrations of 0.1-10 micrograms/ml for periods of 24-96 hours, BMP stimulated the incorporation of 3H-thymidine into acid-insoluble residues (DNA) in calvariae by 25%-159%, and at 1-10 micrograms/ml it increased bone DNA content by 20%-23%. BMP at 1 micrograms/ml also increased the number of calvarial mitoses after colcemid arrest by 1.5-1.8-fold. The effect of BMP on calvarial DNA synthesis was observed in the periosteal bone. In contrast to its effects on DNA synthesis, BMP did not stimulate the incorporation of 3H-proline into collagenase-digestible and noncollagen protein and did not alter calvarial alkaline phosphatase activity. BMP at 1-10 micrograms/ml caused a marked increase in 3H-thymidine incorporation into DNA in cultured NRK fibroblasts and increased DNA content and cell number by 1.5-2-fold. These studies indicate that BMP stimulates DNA synthesis and cell replication in calvarial and fibroblast cultures but does not stimulate postdifferentiated bone cells in incubated calvariae.

Alkaline Phosphatase↗
PubMed1984

Effect of cartilage-derived factor on DNA and protein synthesis in cultured rat calvariae.

Cartilage-derived factor (CDF), a peptide closely related to the somatomedins, was studied for its effects on bone formation by examining the synthesis of DNA, collagen, and noncollagen protein in 24-96 h cultures of 21-day fetal rat calvariae. After 24 h of treatment, CDF at concentrations of 0.3-30 micrograms/ml caused a dose-dependent stimulation of the incorporation of 3H-thymidine into DNA by 12-59%. The effect appeared and was maximal after 12 h, and was sustained for 96 h. CDF also increased the bone DNA content by 30-60%. After 24 h of treatment, CDF at 10-30 micrograms/ml had a small stimulatory effect on the incorporation of 3H-proline into collagenase-digestible protein (CDP) and noncollagen protein (NCP). The effect on the labeling of CDP and NCP was sustained for 96 h. Cortisol decreased the stimulatory effect of CDF on DNA labeling but cortisol and CDF had an additive effect on the incorporation of 3H-proline into CDP. The CDF stimulatory effect on the labeling of DNA, CDP, and NCP was seen in both the periosteum and periosteum-free calvaria. These studies indicate that CDF stimulates bone DNA, collagen, and noncollagen protein synthesis in vitro and may be a local regulator of bone growth.

Animals↗
PubMed1984

Effect of cortisol on periosteal and nonperiosteal collagen and DNA synthesis in cultured rat calvariae.

The effects of cortisol on bone formation are complex and may be modulated by the presence of periosteal cells or by factors released by the periosteal tissue. To test these possibilities, cortisol was examined for its effects on the incorporation of 3H-proline into collagenase-digestible protein (CDP) and noncollagen protein (NCP), on DNA synthesis and on alkaline phosphatase activity in intact and in the periosteum and nonperiosteal bone of dissected calvariae from 21-day-old fetal rats. After 24 h of treatment, cortisol increased the incorporation of 3H-proline into CDP in intact bones and in the nonperiosteal bone of calvariae dissected after the culture. Cortisol inhibited the incorporation of 3H-thymidine into calvarial DNA but it caused a small increase in nonperiosteal DNA content. Cortisol did not affect the incorporation of 3H-proline into CDP in calvariae dissected prior to the culture if the periosteum and nonperiosteal central bone were incubated separately; the stimulatory effect was observed only if the two tissues were cultured in the same vial and were in contact. In contrast, cortisol stimulated alkaline phosphatase activity in the central nonperiosteal bone of calvariae dissected before or after the culture. After 72-96 h of treatment, cortisol inhibited the labeling of CDP, NCP, and DNA and the DNA content in intact bones and in both periosteal and nonperiosteal central bone of calvariae dissected after the culture. In contrast, when the periosteum was removed before the incubation, these inhibitory effects were observed in the periosteum and not in the nonperiosteal bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1983

Effect of hormones and growth factors on alkaline phosphatase activity and collagen synthesis in cultured rat calvariae.

Studies on the direct effects of hormones and growth factors on bone alkaline phosphatase have been limited to parathyroid hormone (PTH) and 1,25 dihydroxyvitamin D3 [1,25(OH)2D3] and have not been compared to other parameters of bone formation. Insulin, PTH, 1,25(OH)2D3, epidermal and fibroblast growth factors (EGF, FGF) were examined for their effects on alkaline phosphatase activity and type I, [alpha 1 (I)]2 alpha 2, collagen synthesis in cultures of 21-day fetal rat calvariae. After 24 hr and 96 hr of treatment, insulin increased whereas PTH, 1,25(OH)2D3, EGF and FGF inhibited calvarial alkaline phosphatase activity and the incorporation of 3H-proline into collagenase-digestible protein and type I collagen. The agents tested did not affect the release of alkaline phosphatase into the culture medium. Although type I collagen was the only collagen detected, a small amount of another collagen might have been also synthesized. The hormonal effects on alkaline phosphatase activity and type I collagen synthesis were of greater magnitude after 96 hr than after 24 hr of continuous exposure to the agents tested and the two parameters correlated well (r = 0.88 after 96 hr and r = 0.97 after 24 hr of treatment. These studies indicate that insulin increases bone alkaline phosphatase activity and type I collagen synthesis in calvariae whereas PTH, 1,25(OH)2D3, EGF and FGF have an inhibitory effect. The results suggest that these agents affect osteoblastic function.

Alkaline Phosphatase↗
PubMed1983

Tuberous sclerosis and associated pleuropulmonary lesions.

Tuberous sclerosis (TS) is a rare disease of the nervous system, being characterized by seizures, mental retardation and adenoma sebaceum. Concomitant pleuropulmonary lesions and spontaneous pneumothorax are extremely rare during the evolution of this disease. To date, only 19 cases of TS and spontaneous pneumothorax have been described in the literature. Here we present a case of TS and associated pleuropulmonary lesions with spontaneous pneumothorax in a 29-year-old female patient. Clinical, roentgenographic and histological aspects of this disease are commented upon.

Adult↗
PubMed1983

Effect of glucocorticoids on type I collagen synthesis, alkaline phosphatase activity, and deoxyribonucleic acid content in cultured rat calvariae.

Glucocorticoid-induced osteoporosis is believed to be caused by increased bone resorption and decreased bone formation. However, the direct effects of glucocorticoids on bone formation are, as yet, not fully understood. Cortisol, corticosterone, and dexamethasone were examined for their effects on alkaline phosphatase activity, the incorporation of [3H]proline into type I collagen, DNA content, and mitotic index in intact 21-day-old fetal rat calvariae. After 24 h of treatment, cortisol at 1-100 nM increased the incorporation of [3H]proline into type I collagen, whereas at 1-10 microM, cortisol inhibited type I collagen labeling. After 96 h, cortisol (0.1-10 microM) had an inhibitory effect on type I collagen labeling and alkaline phosphatase activity. Cortisol had a small, not dose dependent, and transient stimulatory effect on alkaline phosphatase which appeared after 12-24 h of exposure, whereas the inhibitory effect was dose related, it appeared and was near-maximal after 48 h of continuous treatment with cortisol. Corticosterone and dexamethasone had an effect similar to that of cortisol on type I collagen synthesis and alkaline phosphatase activity. None of the steroids tested affected the release of the enzyme into the culture medium. Cortisol, corticosterone, and dexamethasone did not alter calvarial DNA content after 24 h of treatment, but after 96, concentrations of 1 nM to 10 microM were inhibitory. The decrease in DNA appeared after 48 h of exposure to 100 nM cortisol and was maximal after 72 h. Histological sections showed a marked and generalized decrease in the number of mitoses after colcemid arrest in calvariae treated with 100 nM cortisol, corticosterone, or dexamethasone for 96 h. These studies indicate that glucocorticoids have a dual effect on type I collagen synthesis and alkaline phosphatase activity in cultured calvariae: a transient stimulatory effect after short term treatment and an inhibitory one after long term exposure. The latter is related to a generalized decrease in cell population.

Adrenal Cortex Hormones↗
PubMed1982

Effect of bone-derived growth factor on DNA, RNA, and proteoglycan synthesis in cultures of rabbit costal chondrocytes.

Calvariae and chondrocytes in culture have been reported to release growth factors which stimulate bone and cartilage growth respectively. In the present studies, we examined the effects of bone-derived growth factor (BDGF) on DNA, RNA and proteoglycan synthesis in cultured rabbit chondrocytes. Two partially purified fractions of BDGF were tested, one with an approximate molecular weight (MW) of 20-30,000 and with greater activity on calvarial DNA labeling (BDGF I) and another with an approximate MW 6-13,000 and greater activity on bone collagen labeling (BDGF II). Both fractions had a similar effect and increased the incorporation of -3H-uridine into acid insoluble residues in chondrocytes and the incorporation of 35SO4(2-), 3H-glucosamine and 3H-serine into proteoglycans. However, BDGF II had a greater stimulatory effect on the incorporation of 3H-thymidine than BDGF I. These findings suggest that factor(s) released by bone cells are capable of stimulating cartilage metabolism and growth.

Animals↗
PubMed1982

A more specific, liquid-chromatographic method for free cortisol in urine.

Currently used assays for urinary cortisol reportedly overestimate it, owing to cross-reacting substances. We describe here a method for separating and measuring by liquid chromatography cortisol extracted from urine. The method is specific for cortisol and as little as 5 ng per sample can be measured. Mean analytical recovery of added cortisol was 98.8% (SD 6.1%) and the coefficients of variation ranged from 3.1 to 4.7% (within-day) and from 7.1 to 14% (between-day). Mean (and SD) urinary excretion of cortisol for 45 normal men and women was 20.1 (SD 7.6) micrograms/24 h; for 29 children it was 14.1 (SD 6.0) micrograms/24 h. Results by radioimmunoassay were 1.4- to 4.3-fold greater than by this method, and results of the two assays did not correlate well (r = 0.59, p less than 0.01). We consider the present method to be a practical and specific assay for three cortisol in urine.

Adolescent↗