Osteogenesis imperfecta type I Is a mild, dominantly inherited, connective tissue disorder characterized by bone fragility. Mutations in type I collagen account for all known cases. In Mov-13 mice, integration of a murine retrovirus within the first Intron of the al(I) collagen gene results in a null allele blocked at the level of transcription. This study demonstrates that mutant mice heterozygous for the null allele are a model of osteogenesis Imperfecta type I. A defect in type I collagen production is associated with dominant-acting morphological and functional defects in mineralized and nonmineralized connective tissue and with progressive hearing loss. The model provides an opportunity to investigate the effect of a reduced amount of type I collagen on the structure and integrity of extracellular matrix. It also may represent a system in which therapeutic strategies to strengthen connective tissue can be developed.The Mov-13 strain was generated by exposing mouse embryos to Moloney murine leukemia virus. Genetic and molecular evidence indicated that a single copy of the provirus integrated into the first intron of the al(I) collagen gene (13,14). The proviral insert is associated with a change in chromatin conformation and de novo methylation ofthe gene, and it prevents initiation of transcription (15-17). Mice homozygous for the null mutation die in utero because of failure of the vascular system (18). However, heterozygous Mov-13 mice (referred to in this paper simply as Mov-13 mice) do not display an obvious mutant phenotype. Given the nature of the mutation harbored by Mov-13 mice, it was hypothesized that they would serve as a model of 01-I. In the present report we have undertaken a detailed biochemical and functional analysis of Mov-13 mice to determine if this were the case.Osteogenesis imperfecta type I (O0-I) is a mild disorder characterized by bone fracture without deformity, blue sclerae, normal or near normal stature, and autosomal dominant inheritance (1, 2). The incidence is estimated to be 1 of 20,000 live births, and males and females are affected equally. Osteopenia is associated with an increased rate of long-bone fracture upon ambulation. For reasons not well understood, fracture frequency decreases dramatically at puberty and during young adult life but increases once again in late middle age (3). Progressive hearing loss, often beginning in the second or third decade, is a feature of this disease in about half of the families (4). The proportion of O0-I patients with significant hearing loss rises steadily into middle age despite the general decline in fracture frequency. Conductive or mixed (conductive and sensorineural) hearing loss is more common in dominant OI than sensorineural hearing loss alone. Dentinogenesis imperfecta is observed in a small subset of the patient population (5).All O0-I cases to date have been associated with mutations in the extracellular matrix molecule type I collagen (6). There is evidence that both null alleles and structural mutations can produc...

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Summary Trigger finger is one of the most common causes of disability and pain in the hand. Current surgical techniques for trigger finger release fall short in that they are performed blindly with trauma to, or require incision of, the palmar fascia, which can be a source of significant and long-lasting morbidity. Retrograde endoscopic release of the A1 pulley was performed through a single incision at the proximal digital crease in cadaveric specimens. The fingers were then dissected to assess for completeness of release and inspected for injury to nearby structures. Complete release of the A1 pulley was noted in 16 of 16 fingers. No significant injuries to the A2 pulley and flexor tendon were found, and no injuries to the digital nerves or vasculature occurred. The described technique, as demonstrated in cadaveric specimens, is a feasible alternative approach in the treatment of trigger finger. The technique allows complete visualization of A1 pulley release through a single palmar fascia sparing incision.