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PubMed1990

Fibroblast growth factor in chick osteogenesis.

In vivo effects of FGF on osteogenesis in the chick embryo were evaluated. Day-11 embryos were injected with FGF followed by radiotracers. 3H-thymidine labelling of osteogenic cells was significantly higher following FGF administration; 3H-proline labelling over bone matrix was greater in the controls. Cartilage cells and matrix were sparsely labelled indicating a low level of metabolic activity. These data provide the first in vivo evidence that FGF stimulates osteogenic cell proliferation, while inhibiting production of bone matrix collagen. A role for FGF in embryonic osteogenesis and in fracture repair is suggested.

Animals↗
PubMed1989

Substitution of serine for alpha 1(I)-glycine 844 in a severe variant of osteogenesis imperfecta minimally destabilizes the triple helix of type I procollagen. The effects of glycine substitutions on thermal stability are either position of amino acid specific.

Recent reports have demonstrated that a series of probands with severe osteogenesis imperfecta had single base mutations in one of the two structural genes for type I procollagen that substituted amino acids with bulkier side chains for glycine residues and decreased the melting temperature of the triple helix. Here we demonstrate that the type I procollagen synthesized by cultured fibroblasts from a proband with a severe form of osteogenesis imperfecta consisted of normal molecules and molecules over-modified by post-translational reactions. The thermal stability of the intact type I collagen was normal as assayed by protease digestion under conditions in which a decrease in thermal stability was previously observed with eight other substitutions for glycine in the alpha 1(I) chain. In contrast, the thermal stability of the one-quarter length B fragment generated by digestion with vertebrate collagenase was decreased by 2-3 degrees C under the same conditions. Nucleotide sequencing of cDNAs and genomic DNA established that the proband had a substitution of A for G in one allele of the pro alpha 1(I) gene that converted the codon for alpha 1-glycine 844 to a codon for serine. The results also established that the alpha 1-serine 844 was the only mutation that could account for the decrease in thermal stability of the collagenase B fragment. There are at least two possible explanations for the failure of the alpha 1-serine 844 substitution to decrease the thermal stability of the collagen molecule whereas eight similar mutations decreased the melting temperature. One possibility is that the effects of glycine substitutions are position specific because not all glycine residues make equivalent contributions to cooperative blocks of the triple helix that unfold in the predenaturation range of temperatures. A second possible explanation is that substitutions of glycine by serine have much less effect on the stability of protein than the substitutions by arginine, cysteine, and aspartate previously studied.

Cell Line↗
PubMedDate not supplied

[Fracture of the mandible in osteogenesis imperfecta. Case report and literature review].

The present paper discusses the etiopathogenesis and the clinical course of osteogenesis imperfecta. Following an outline of the basic principles of treatment in general traumatology, observations made in one own case are described, where a patient with osteogenesis imperfecta had suffered a fracture of the mandible and could be successfully restored to stable function.

Adult↗
PubMed1989

[Reparative osteogenesis after the treatment of multiple fractures of the crural bones using the Ilizarov method].

Repair osteogenesis is associated with a certain pattern of change in bone tissue metabolism: metabolic processes are first enhanced continuously and, reaching a peak, grow weaker. Radioisotopic evidence demonstrates that osteogenesis is concluded within 7 to 8 weeks where the fractures involve no bone displacement, and 9 to 10 weeks where the bones were displaced by fracture.

Adult↗
PubMed1989

[Osteogenesis imperfecta and dentinogenesis imperfecta. Apropos of 4 cases].

Based on four personal cases of osteogenesis imperfecta and dentinogenesis imperfecta, the authors review the semiological elements constituting the syndrome, and assign each case to the Sillence (1979) classification. The author established his classification on clinical criteria and the genetic nature of the various forms of osteogenesis imperfecta, however, the most recent discoveries concerning collagen biochemistry confirm that the condition is without doubt more heterogenous than suggested clinically, thereby better explaining the wide range of mutations encountered.

Child↗
PubMed1986

[Type III osteogenesis imperfecta associated with hypophosphatemic vitamin D-resistant rickets].

In a 7 year old girl presenting with bone deformities, dwarfism, and a history of recurrent fractures osteogenesis imperfecta had been diagnosed at birth. Although she had been hospitalized several times, radiologic signs of rickets remained unnoticed. Laboratory data proved existence of hypophosphatemic vitamin D-resistant type of rickets, which was effectively treated with 1 alpha-hydroxycholecalciferol and phosphorus substitution. The combination of osteogenesis imperfecta type III and hypophosphatemic rickets may be coincident. It proves, however, the necessity to consider the possible simultaneous occurrence of two rare diseases. The therapeutic consequences could be important.

Child↗
PubMed1988

Obstetric management of a fetus with nonlethal osteogenesis imperfecta.

Osteogenesis imperfecta is the common term for a heterogeneous group of heritable disorders of connective tissue with lethal and nonlethal forms. Prenatal diagnosis presents difficult medical and ethical issues. Of concern are the following: 1) the certainty of diagnosis, 2) the severity of disease, 3) the prognosis for survival and ambulation, and 4) the appropriate mode of delivery. A case of nonlethal fetal osteogenesis imperfecta managed by vaginal delivery is discussed.

Adult↗
PubMed1988

[Study of distraction osteogenesis in an animal body submitted to anticancer chemotherapy].

The authors studied distraction osteogenesis in an animal subjected to prolonged anti-mitotic chemotherapy (Methotrexate and Doxorubicin). This chemotherapy decreased osteogenesis (essentially at the expense of external regeneration) though without inhibiting it totally. Distraction bone consolidation is thus possible in the animal, permitting reconstruction of limb segments by mobilization of an axial fragment in accordance with the Ilizarov technique.

Animals↗
PubMed1988

Substitution of cysteine for glycine within the carboxyl-terminal telopeptide of the alpha 1 chain of type I collagen produces mild osteogenesis imperfecta.

We have characterized a mutation that produces mild, dominantly inherited osteogenesis imperfecta. Half of the alpha 1 (I) chains of type I collagen synthesized by cells from an affected individual contain a cysteine residue in the 196-residue carboxyl-terminal cyanogen bromide peptide of the triple-helical domain (Steinmann, B., Nicholls, A., and Pope, F. M. (1986) J. Biol. Chem. 261, 8958-8964). Unexpectedly, sequence determined from a proteolytic fragment of the alpha 1 (I) chain derived from procollagen molecules synthesized in the presence of both [3H]proline and [35S]cysteine indicated that the cysteine is located at the third residue carboxyl-terminal to the triple-helical domain, normally a glycine. The nucleotide sequence of a fragment amplified from genomic DNA confirmed the location of the cysteine residue and showed that the mutation was a single nucleotide change in one COL1A1 allele. This represents a new class of mutations, point mutations outside the triple-helical domain of the chains of type I collagen, that produce the osteogenesis imperfecta phenotype.

Alleles↗
PubMed1988

Role of cartilage canals in osteogenesis and growth of the vertebral centra.

Bone formation in the vertebral centra commences within the centrum and is in this respect analogous to the secondary ossification which occurs in the epiphysis of a long bone. Bone tissue first appears at about the 85 mm C.R. stage and not in the 55 mm C.R. length embryo; at the latter stage blood vessels and calcification alone were observed. The connective tissue cells within the cartilage canal appear to assist osteogenesis by providing osteogenic cells which lay down bone in the walls of the cartilage canal, and provide cells which remove calcified cartilage found at the periphery of the canal; they assist growth by producing an appreciable number of chondrocytes that permit lateral expansion of the centra. Osteogenesis appears to occur in multiple foci within the growth plate of the older embryos and could account for the rapid rate of growth of vertebrae. Bone formation occurs in both mineralised and unmineralised matrix (as seen on the walls of the cartilage canals). The blood vessels within the growing vertebra tend to follow the zone of cartilage hypertrophy.

Cartilage↗
PubMed1988

Non-union of fractures in children who have osteogenesis imperfecta.

Although a fracture rarely fails to unite in a healthy child, non-union is not a rare occurrence in a child who has osteogenesis imperfecta. We identified twelve non-unions in ten patients from a population of fifty-two patients who had osteogenesis imperfecta. The average age of these patients when the diagnosis of non-union was made nine years, and the average age at the time of treatment was 12.5 years. All of the patients had had a decrease in functional ability as a result of the non-union. There were five femoral, four humeral, one radial, one ulnar, and one pubic non-union. Five of the non-unions were hypertrophic, and seven were atrophic. Eight of the nine ununited fractures that were operated on healed after excision of the non-union, intramedullary nailing, and bone-grafting. Three of the non-unions (in two patients) were not operated on, and the one patient in whom surgery failed had an amputation. Non-union was frequently associated with repeated fractures at a progressively deforming site.

Adolescent↗
PubMed1988

A novel mutation causes a perinatal lethal form of osteogenesis imperfecta. An insertion in one alpha 1(I) collagen allele (COL1A1).

We have identified an infant with the perinatal lethal form of osteogenesis imperfecta (type II) whose cells synthesize in equal amounts two different pro alpha 1(I) chains of type I procollagen: one chain is normal in length, the other contains an insertion of approximately 50-70 amino acid residues within the triple helical domain defined by amino acids 123-220. The structure of the insertion is consistent with duplication of an approximately 600-base pair segment in one allele of the alpha 1(I) gene (COL1A1). These cells synthesize normal type I procollagen molecules as well as molecules that contain one or two mutant chains. Unlike type I procollagen molecules synthesized by cells from most other infants with osteogenesis imperfecta type II which contain increased lysyl hydroxylation and hydroxylysyl glycosylation along the triple helical domain, the abnormal molecules synthesized by these cells are not overmodified. The lethal effect of this mutation may result from secretion of about one-quarter the normal amount of normal type I procollagen and secretion of a large amount of a molecule which has a lowered melting temperature, is extended asymmetrically, and which has altered structure in domains important for cross-link formation and bone mineralization.

Adolescent↗
PubMed1987

[Osteogenesis imperfecta treated during growth by intramedullary nailing by the Sofield method. Outcome in adults].

Since 1985 we have used the early surgical treatment of osteogenesis imperfecta described by Sofield, even in the most severe forms of the disease. Twenty-six patients who had reached adult age have been reviewed. Whilst the functional prognosis is relatively favourable in Sillence type I cases, it is not the same for severe type III cases. In these forms, the spine and chest deformities can affect the prognosis for life. The functional state of these patients in adult life is disappointing and many of them subside progressively into the comfort of a wheelchair. Nevertheless, this assessment at the end of growth has confirmed the principles of a surgical approach, even if, at the present time, our attitude is more reserved in severe cases. Very considerable progress in treatment has resulted from telescopic rods. The improvement in prognosis seems now to depend on taking account of the spinal problem in osteogenesis imperfecta. Early surgery on a spine that is, as yet, slightly deformed should be considered in severe forms of the disease.

Adolescent↗
PubMed1986

[Aortic coarctation and osteogenesis imperfecta].

This is the report of a 4 year old patient with osteogenesis imperfecta tarda and aortic coarctation. The resection of the aortic coarctation was performed when the patient was 5 years old. Postoperative recovery and formation of scar tissue presented no problems. Increased operation risk due to osteogenesis imperfecta (White et al., 1983) and possible abnormal formation of scar tissue due to this collagen disorder necessitated detailed preoperative tests of collagen metabolism. We shall discuss the histological and biochemical results of these tests and evaluate the effect of therapy with catechin.

Aorta, Thoracic↗
PubMed1987

Successful aortic valve replacement in osteogenesis imperfecta: with special emphasis on peri-operative management.

Valvular heart disease is a recognized feature of the connective tissue diseases. It occurs to a variable extent in osteogenesis imperfecta and frequently involves the aortic valve. Replacement of the aortic valve, although required, may be complicated by bleeding problems secondary to platelet dysfunction and capillary fragility. A successful aortic valve replacement in a patient with type I osteogenesis imperfecta is described with special reference to hematologic manipulations to control bleeding post-operatively.

Adult↗
PubMed1987

Osteoporosis unmasked by hyperthyroidism in a young man with osteogenesis imperfecta.

A young man presented with a vertebral fracture and generalized osteopenia that was initially attributed to coexisting hyperthyroidism. However, the rarity of fractures in young men with hyperthyroidism and the finding of blue sclerae led to the diagnosis of osteogenesis imperfecta. Since vertebral fractures are uncommon in young men with osteogenesis imperfecta, we postulate that the combined effects of the two disorders contributed to his clinical presentation.

Adult↗
PubMed1986

Clinical variability of osteogenesis imperfecta reflecting molecular heterogeneity: cysteine substitutions in the alpha 1(I) collagen chain producing lethal and mild forms.

We have examined the collagenous proteins extracted from skin and produced by skin fibroblast cultures from the members of a family with mild dominant osteogenesis imperfecta (OI type I). The two affected patients, mother and son, produce two populations of alpha 1(I) chains of type I collagen, one chain being normal, the other containing a cysteine within the triple-helical domain. Both forms can be incorporated into triple-helical molecules with an alpha 2(I) chain. When two mutant alpha (I) chains are incorporated into the same molecule, a disulfide bonded dimer is produced. We have characterized these chains by sodium dodecyl sulfate-gel electrophoresis and CNBr-peptide mapping and by measuring a number of biosynthetic and physical variables. The cysteine was localized to the COOH-terminal peptide alpha (I) CB6. Molecules containing the mutant chains are stable, have a normal denaturation temperature, are secreted normally, and have normal levels of post-translational modification of lysyl residues and intracellular degradation. We have compared and contrasted these observations with those made in a patient with lethal osteogenesis imperfecta in which there was a cysteine substitution in alpha 1(I) CB6 (Steinmann, B., Rao, V. H., Vogel, A., Bruckner, P., Gitzelmann, R., and Byers, P. H. (1984) J. Biol. Chem 259, 11129-11138) and have concluded that the mutation in the present family occurs in the X or Y position of a Gly-X-Y repeating unit of collagen and not in the glycine position shown for the previous patient (Cohn, D. H., Byers, P. H., Steinmann, B, and Gelinas, R. E. (1986) Proc. Natl. Acad. Sci. U. S. A., in press.

Adolescent↗
PubMed1986

Defects in the processing of procollagen to collagen are demonstrable in cultured fibroblasts from patients with the Ehlers-Danlos and osteogenesis imperfecta syndromes.

This is a study of the processing of procollagen to collagen in cultures of skin and tendon fibroblasts. Processing was markedly increased by growing cells for 2-4 days postconfluence and then adding ascorbate to the medium for 2 days prior to labeling with [3H] proline. With this system, more than two-thirds of the pro-alpha chains of type I procollagen in the culture medium, and more than 90% of those in the cell layer, were rapidly processed to pC-alpha, pN-alpha, or alpha chains. Purified, exogenous procollagen was also rapidly processed in cell-free culture medium. The results showed for the first time that exogenous procollagen can be processed in conditioned cell-free medium. The system was then used to compare the processing of procollagen in the medium of normal fibroblasts, cells from one bovine and four human variants of osteogenesis imperfecta, and those from eight human variants of the Ehlers-Danlos syndrome. The cells could be divided into three groups, based on their ability to process type I procollagen: normal, consistently slow, and very slow. The cause of the decreased processing was shown to be associated with either a mutation causing a shortening of an alpha chain or decreased activity of procollagen N-proteinase in cell-free culture medium. Decreased processing of procollagen to collagen occurred with cultured fibroblasts from patients with different forms of both osteogenesis imperfecta and Ehlers-Danlos syndrome. Both of these disease syndromes are associated with abnormalities in the structure or metabolism of procollagen in fibrous connective tissues, bones, and teeth. The results show that defects in the structure, synthesis, or processing of procollagen are readily demonstrated with cultured fibroblasts.

Adolescent↗