A sex-linked defect in the cross-linking of collagen and elastin associated with the mottled locus in mice.

A genetic abnormality in collagen and elastin cross-linking resembling experimental lathyrism has been identified in mice. The defect is an X-linked trait, attributed to the mottled locus which also influences coat color. The affected mice have aneurysms of the aorta and its branches, weak skin, and bone deformities in a spectrum of severity varying with the alleles at the mottled locus. A defect in the cross-linking of collagen was demonstrated in the skin of the affected animals by a marked increase in collagen extractability and a reduced proportion of cross-linked components in the extracted collagen. A decrease in lysine-derived aldehyde levels was found in both skin collagen and aortic elastin similar to that found in lathyritic tissue. Furthermore the in vitro formation of lysine-derived aldehyde was reduced. Thus the cause of the connective tissue abnormalities in these mice appears to be a defect in cross-link formation due to an impairment in aldehyde formation.

Fibrillin-1 in human cartilage: developmental expression and formation of special banded fibers.

The molecular basis for Marfan's syndrome (MS), a heritable disorder of connective tissue, is now known to reside in mutations in FBN1, the gene for fibrillin-1. Classic phenotypic manifestations of MS include several skeletal abnormalities associated primarily with overgrowth of long bones. As a first step towards understanding how mutations in FBN1 result in skeletal abnormalities, the developmental expression of fibrillin-1 (Fib-1) in human skeletal tissues is documented using immunohistochemistry and monoclonal antibodies demonstrated here to be specific for Fib-1. At around 10-11 weeks of fetal gestation, Fib-1 is limited in tissue distribution to the loose connective tissue surrounding skeletal muscle and tendon in developing limbs. By 16 weeks, Fib-1 is widely expressed in developing limbs and digits, especially in the perichondrium, but it is apparently absent within cartilage matrix. Fib-1 appears as a loose meshwork of fibers within cartilage matrix by 20 weeks of fetal gestation. Until early adolescence, Fib-1 forms loose bundles of microfibrils within cartilage. However, by late adolescence, broad banded fibers composed of Fib-1 are found accumulated pericellularly within cartilage. Because these fibers can be extracted from cartilage using dissociative conditions, we postulate that they are laterally packed and crosslinked microfibrils. On the basis of these findings, we suggest that the growth-regulating function of Fib-1 may reside persistently within the perichondrium. In addition, the accumulation of special laterally crosslinked Fib-1 microfibrils around chondrocytes during late adolescence suggests that growth-regulating activities may also be performed by Fib-1 at these sites.

Biosynthesis and processing of collagens in different cartilaginous tissues.

The distribution, structure, and biosynthesis of various collagen types have been studied in growth and structural cartilage from young rabbits. The major collagen of cartilage is alpha 1(II); however, all cartilage matrix also contains 1 alpha, 2 alpha, 3 alpha (Type Cm), as well as a high molecular weight disulfide-linked collagen (Type M). Cartilage fragments in organ culture demonstrate synthesis of precursors of collagen alpha chains and processing to their final forms. Although Type Cm collagen is present in the same proportion in the matrix of growth and structural cartilage, in vitro radiolabeling of rabbit cartilage showed that only growth cartilage is capable of actively synthesizing Type Cm, except in the newborn period when synthesis of Type Cm does occur in structural cartilage. A low molecular weight collagen (designated G collagen) is synthesized in vitro by growth cartilage but not by structural or articular cartilage. Preferential distribution of these minor collagens in growth cartilage suggests a role in development during normal cartilage growth.

Abnormality of cartilage collagen in a patient with unclassified chondrodystrophy.

We have described a previously unrecognized chondrodystrophy characterized by short-limbed dwarfism, blue sclera, severe cardiopulmonary problems, and failure of postnatal growth. The first of two siblings thus affected died at age 6 months following attempted correction of an atrial septal defect. Growth plate cartilage from multiple sites obtained at autopsy showed a marked abnormality of architecture on the light microscopic level. Biochemical studies demonstrated an absence of normal alpha 1(II) collagen in costochondral junction growth plate cartilage and an appearance of the major collagen in a band which comigrates on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with 3 alpha collagen. Cartilage extracted from structural rib appeared to be normal.

Recent developments in latency and recombination of Aujeszky's disease (pseudorabies) virus.

Latency is a characteristic and fascinating part of the biology of alphaherpesvirinae, including ADV. Tissue explanation, blot hybridization, in situ hybridization and more recently PCR are the experimental methods used to demonstrate that latent infections consistently occur in ganglionic neurons and, at a lower level, in tonsillar and possibly other cells. In vivo reactivation of ADV, resulting in shedding of virulent ADV, has been demonstrated experimentally following administration of high doses of corticosteriods. To determine the influence of vaccination with currently used gene deleted vaccines on field virus latency load, it is essential to use quantitative latency detection methods. We have developed chemiluminescence-based quantitative PCR assays specific for gG and gE, and are currently using these to determine field virus latency loads in tissues of pigs vaccinated with one of several gene deleted vaccines. Recombination between ADV strains has been demonstrated both in vitro and in vivo and has raised concerns about the generation of gene deleted virulent ADV strains. Recent studies in a mouse model have shown that high concentrations of both strains have to be present at the same anatomical site for recombination to take place. This led to the conclusion that ongoing ADV eradication programs, based upon the use of gene deleted vaccines and differential serological testing, are not likely to be threatened by recombination between virulent ADV and gene deleted vaccine strains.

Vaccine genotype and route of administration affect pseudorabies field virus latency load after challenge.

The influence of vaccine genotype and route of administration on the efficacy of pseudorabies virus (PRV) vaccines against virulent PRV challenge was evaluated in a controlled experiment using five genotypically distinct modified live vaccines (MLVs) for PRV. Several of these MLVs share deletions in specific genes, however, each has its deletion in a different locus within that gene. Pigs were vaccinated with each vaccine, either via the intramuscular or intranasal route, and subsequently challenged with a highly virulent PRV field strain. During a 2-week period following challenge with virulent PRV, each of the vaccine strains used in this study was evaluated for its effectiveness in the reduction of clinical signs, prevention of growth retardation and virulent virus shedding. One month after challenge, tissues were collected and analyzed for virulent PRV latency load by a recently developed method for the electrochemiluminescent quantitation of latent herpesvirus DNA in animal tissues after PCR amplification. It was determined that all vaccination protocols provided protection against clinical signs resulting from field virus challenge and reduced both field virus shedding and latency load after field virus challenge. Our results indicated that vaccine efficacy was significantly influenced by the modified live vaccine strain and route of administration. Compared to unvaccinated pigs, vaccination reduced field virus latency load in trigeminal ganglia, but significant differences were found between vaccines and routes of administration. We conclude that vaccine genotype plays a role in the effectiveness of PRV MLVs.

Cerebellar dysplasia and unilateral cataract in Marinesco-Sjögren syndrome.

The classic features of Marinesco-Sjögren syndrome include bilateral cataracts, cerebellar ataxia, and mental deficiency with an autosomal recessive inheritance pattern. Weakness and a variety of other characteristics are present inconsistently. A limited number of neuroimaging studies have indicated that cerebellar hypoplasia is the most common finding. We report a patient with near normal intelligence, unilateral cataract, and the previously unreported magnetic resonance imaging findings of cerebellar dysplasia, arachnoid cyst, and absent septum pellucidum. A review of the literature suggests significant heterogeneity in the Marinesco-Sjögren syndrome.

The 'chef's hat' appearance of the femoral head in cleidocranial dysplasia.

Cleidocranial dysplasia (CCD) is inherited as an autosomal dominant disorder characterised by failure of membranous ossification. The condition is due to a mutation of the cbfa1 gene on chromosome 6 which has a role in the development of osteoblasts from the mesenchymal cells. In their growing years, these patients have an unusual shape of the femoral head reminiscent of a 'chef's hat'. In order to confirm the consistency of this sign, we have reviewed the radiographs of 28 patients with CCD. All except three had this appearance. The sign was also seen in patients with coxa vara associated with a variety of other conditions. The chef's hat sign may occur secondary to the particular mechanical environment created by coxa vara as well as abnormal cellular function in patients with CCD. Although coxa vara has some influence on the shape of the femoral head, it is not entirely responsible for its morphology since it was present in only six of the 28 patients with CCD.

Viral infections of the feline urinary tract.

The exact cause of hematuria, dysuria, and urethral obstruction remains unknown in a large percentage of naturally occurring cases of feline lower urinary tract disease (FLUTD). One attractive hypothesis implicates viruses as the cause of some idiopathic forms of FLUTD; supporting this hypothesis is the fact that a gamma herpesvirus, a calicivirus, and a retrovirus have been isolated from urine and tissues obtained from cats with this type of disease. Although the clinical course and laboratory findings of cats with idiopathic FLUTD are suggestive of an infectious cause, the question of whether viruses have a pathologic role in some forms of naturally acquired FLUTDs has not been completely answered.

The radiological analysis of pes cavus deformity in Charcot Marie Tooth disease.

Charcot Marie Tooth (CMT) is a progressive hereditary peripheral neuropathy. The most prevalent subtype is CMT-1A, wherein patients develop a characteristic cavovarus deformity. We have reviewed a series of standing lateral foot radiographs of patients with foot deformity due to CMT, and found that the hind foot of these patients is in dorsiflexion, not equinus, and that the apparent equinus is due to plantar flexion of the forefoot on the midfoot, and actually represents a cavus deformity.

Strategies of hip management in neuromuscular disorders: Duchenne Muscular Dystrophy, Spinal Muscular Atrophy, Charcot-Marie-Tooth Disease and Arthrogryposis Multiplex Congenita.

Joint contractures, subluxation and dislocation are common problem in children with neuromuscular disorders. Medical, surgical and rehabilitative approaches can be used to maintain patient function and comfort. Contracture release, hip dysplasia correction and procedures to address or prevent hip subluxation or dislocation, are not always necessary since patients can be asymptomatic and surgical treatment will not always be successful in maintaining a reduced hip. In fact, controversy surrounds the management of hip disorder in children with Duchenne Muscular Dystrophy, Spinal Muscular Atrophy, Charcot-Marie-Tooth Disease and Arthrogryposis Multiplex Congenita. Patients with neuromuscular disorders also frequently develop a progressive scoliosis with pelvic obliquity which may affect sitting balance and become painful. Most subluxations and dislocations have the tendency to occur on the high side of a tilted pelvis. Spinal stabilisation is sometimes necessary to improve the pelvic tilt and to prevent further increase. The present article provides an overview of the current strategies of hip management in neuromuscular disorders.

Ethical requirements that must be met before the introduction of new procedures.

For orthopaedic care of patients to continue to improve, new approaches, both diagnostic and therapeutic, must be continually developed. To verify that a new approach actually provides improved outcomes, these innovations must be subjected to rigorous scientific study. However, because outcomes of clinical interventions only can be studied in human subjects, these studies must not only meet scientific criteria, they also must meet strict ethical criteria. The Declaration of Helsinki, a document prepared by the World Medical Association that originally was written in 1964, revised substantially in 1975, and most recently revised in 1996, provides guidelines for such studies. In addition to satisfying ethical requirements, clinical investigators also face various complex issues that must be dealt with in the performance of clinical research studies. One of the most difficult issues is the conflict between a physician's concern for the well-being of his or her patients and the need for protocol driven trials. No matter how enthusiastic surgeons may be about a new therapeutic approach, they must recognize that they are responsible to scientifically validate their innovative approach with a well controlled clinical trial using valid functional outcome measures.

Advantage of early spinal stabilization and fusion in patients with Duchenne muscular dystrophy.

Segmental instrumentation and fusion of spinal deformity in patients with Duchenne muscular dystrophy yields good correction and provides firm internal stabilization that allows rapid mobilization of patients following surgery. When surgery to stabilize spinal deformity is done in younger patients in whom pulmonary function is better and curves are milder, complication rate and length of hospital stay are diminished, correction and balance are improved, and patients rapidly return to their normal life-style. We no longer routinely attempt orthotic treatment of these curvatures, but advise stabilization of the collapsing spine surgically with segmental instrumentation and fusion when scoliosis reaches 30-40 degrees.

The Risser sign: a critical analysis.

Orthopedic surgeons commonly use the Risser sign to estimate skeletal maturity; however, the data presented in the orthopedic literature supporting the accuracy of the Risser sign in estimating skeletal maturity do not stand up to critical statistical analysis. The Risser sign is less accurate than chronologic age as a predictor of skeletal age and should not be used as a substitute for a hand and wrist radiograph in most cases. The Risser sign is also no better a predictor of scoliosis progression than is chronologic age.

Early mobilization of adolescent scoliosis patients following Wisconsin interspinous segmental instrumentation as an adjunct to Harrington distraction instrumentation. Preliminary report.

This is a preliminary report of the authors' first 40 patients treated by posterior spinal fusion with Wisconsin interspinous segmental instrumentation (WISSI) with a minimum 18-month follow-up period. No major complications because of the instrumentation were encountered. The patients were allowed to sit in a chair on the second or third postoperative day. Early elimination of postoperative casts resulted in an increased rate of problems with fixation and led to reintroduction of a postoperative orthosis, but not the body cast. Some fixation problems may have been related to technical errors and use of the earlier one-button technique. In two patients who had hook dislodgement, the WISSI maintained spinal correction thereby demonstrating its stabilizing effect.

Preliminary report: the role of short-leg, tone-reducing casts as an adjunct to physical therapy of patients with cerebral palsy.

In the past two years, we have used specially constructed, short-leg casts as an adjunct to the therapy program for 99 patients with cerebral palsy. The casts provide tone reduction and increased stability, while allowing mobility, and have been useful in initiating weight-bearing activities and improvement of gait pattern.

Electromyographic and force patterns of cerebral palsy patients with windblown hip deformity.

The electromyographic activity and the forces around the hip were measured in resting, neutral, and 25 degrees abduction in 13 individuals with spastic quadriplegia and windblown deformity. A direct correlation was found between abduction force and myoelectric activity of the abductors. In the adducted hip, there was sustained activity of the adductors while the activity in the abductors was minimal in all positions. In the abducted hip, there was electrical activity in both abductors and adductors in all positions except 25 degrees abduction when only the adductors were active. The results suggest that early detection of potentially progressive windblown hips in children with cerebral palsy may be achieved by careful assessment of hip range of motion, recognition of spasticity in abductors, and the presence of a "pseudo-Galleazzi sign."

Cloning, nucleotide sequence, and regulation of the Bacillus subtilis gpr gene, which codes for the protease that initiates degradation of small, acid-soluble proteins during spore germination.

The gpr gene, which codes for the protease that initiates degradation of small, acid-soluble proteins during spore germination, has been cloned from Bacillus megaterium and Bacillus subtilis, and its nucleotide sequence has been determined. Use of a translational gpr-lacZ fusion showed that the B. subtilis gpr gene was expressed primarily, if not exclusively, in the forespore compartment of the sporulating cell, with expression taking place approximately 1 h before expression of glucose dehydrogenase and ssp genes. gpr-lacZ expression was abolished in spoIIAC (sigF) and spoIIIE mutants but was reduced only approximately 50% in a spoIIIG (sigG) mutant. However, the kinetics of the initial approximately 50% of gpr-lacZ expression were unaltered in a spoIIIG mutant. The in vivo transcription start site of gpr has been identified and found to be identical to the in vitro start site on this gene with either E sigma F or E sigma G. Induction of sigma G synthesis in vivo turned on gpr-lacZ expression in parallel with synthesis of glucose dehydrogenase. These data are consistent with gpr transcription during sporulation first by E sigma F and then by E sigma G.