An immunocytochemical analysis of torn rotator cuff tendon taken at the time of repair.

During rotator cuff repairs, it is recommended that the hypovascular tissue edge be resected. To investigate rotator cuff tendon histopathology, we performed immunohistochemistry on 8 surgical and 6 cadaveric specimens. Hoechst nuclear stain and standard hematoxylin-eosin were used for morphologic analysis. Antibody to human von Willebrand factor tagged with fluorescein isothiocyanate, conjugated, was used to visualize vascularity, and antibody to human procollagen type I tagged with Cy3 was used to visualize new procollagen synthesis. There were no significant differences in the vascularity of surgical specimens sectioned near the tear site (<2.5 mm from tear margin) and matched cadaveric controls. However, sections taken 2.5 to 5 mm away from the tear demonstrated more vessels than those taken from either control or surgical specimens within 2.5 mm of the tear (P <.001). There were no differences in nuclear distribution patterns or in procollagen production and distribution between surgical specimens from sites near the tear or away from the tear. On the basis of morphologic architecture, these data suggest that minimal debridement of tendon edges only is required to maximize healing of the rotator cuff tendon at the time of repair.

Familial Blomstrand chondrodysplasia with advanced skeletal maturation: further delineation.

We report on two sibs with a rare lethal chondrodysplasia born to a non-consanguineous couple. The hallmarks of this affection, also called Blomstrand chondrodysplasia, are short limbs, polyhydramnios, hydrops fetalis, facial anomalies, increased bone density, and a remarkable advance in skeletal maturation. We describe the radiologic and pathologic manifestations in these two cases. This recurrence affecting a male and a female fetus, born to the same couple, suggests autosomal recessive inheritance.

Abnormal collagen cross-linking in the cartilage of a diastrophic dysplasia patient.

The abnormal organization of the cartilage collagen in diastrophic dysplasia is not generally reflected in the levels of the major stabilizing cross-link, hydroxylysyl-pyridinoline. However, in one case there was a marked decrease in the pyridinoline concomitant with the appearance of two unknown components in the cross-link region of the chromatogram. A decrease in cross-linking of this magnitude could lead to mechanically weakened cartilage. Insufficient material was available to characterize these unknown components. The disorganization of cartilage in some cases of diastrophic dysplasia could therefore be due to post-translational modifications, including defective cross-linking.

Non-collagenous protein screening in the human chondrodysplasias: link proteins, cartilage oligomeric matrix protein (COMP), and fibromodulin.

A gel-electrophoretic screening for link proteins, cartilage oligomeric matrix protein (COMP), and fibromodulin abnormalities was performed in fetuses, newborn infants, and children with various types of chondrodysplasia. Microdissected freeze-dried sections of upper tibial growth cartilage were extracted with 4M guanidinium chloride in the presence of proteolysis inhibitors. After dialysis against 8M urea, the extracts were submitted to stepwise ion-exchange chromatography to separate the large proteoglycans (aggrecans) from the other components. The latter were analyzed by gel electrophoresis, electrotransferred onto nitrocellulose membranes, and reacted with specific antibodies. Control samples from individuals with apparently normal growth were analyzed in the same runs. Two link protein bands with abnormal electrophoretic migration were found in a sporadic case of spondylometaphyseal dysplasia, Kozlowski type. Three link protein bands with the same migration as in the control samples were found in thanatophoric dysplasia, homozygous achondroplasia, achondrogenesis type II, hypochondrogenesis, Goldblatt syndrome, Desbuquois dysplasia, pseudoachondroplasia, and diastrophic dysplasia. In several pathologic cases with normal electrophoretic pattern of the link proteins, small link protein fragments appeared after reduction. The gel electrophoretic pattern of COMP was studied in thanatophoric dysplasia, diastrophic dysplasia, homozygous achondroplasia, fibrochondrogenesis, hypochondrogenesis, Goldblatt syndrome, and Kniest dysplasia. In all these cases the pattern was the same as in the control samples. The main band of fibromodulin had a normal migration rate in fibrochondrogenesis, Desbuquois dysplasia, Kniest dysplasia, and pseudoachondroplasia. It was delayed in diastrophic dysplasia.

Achondrogenesis type IB (Fraccaro): study of collagen in the tissue and in chondrocytes cultured in agarose.

A lethal chondrodysplasia characterized by extreme micromelia was diagnosed by ultrasound examination in two sibs whose nonconsanguineous parents were healthy. Radiographic and histopathologic data indicated that the two foetuses (18 and 21 weeks old) had achondrogenesis type IB (Fraccaro). Quantitation of total collagen extractable from dried cartilage samples demonstrated a 50% decrease when compared to an age-related control. This decrease was essentially related to type II collagen. Nevertheless, the alpha chains and the CB peptides of type II collagen had a normal electrophoretic mobility. A significant amount of collagen type I was also detected. The electrophoretic pattern of collagens type IX and XI did not differ significantly from control sample. The extracellular matrix elaborated by patient chondrocytes cultured in agarose for 10-12 days, contained less collagen type II than normal cells. Labelling with 14C-proline of cultured cells showed the presence of procollagen and type II collagen chains with a normal electrophoretic mobility, but an alpha 2(I) chain was detectable in the patient material, indicating the presence of collagen type I which supported the tissue findings. The significance of the type II collagen reduction in the patient's cartilage is unclear but it is unlikely to be the primary defect in achondrogenesis type I.

The epidermal growth factor-like domain of the large proteoglycans from articular cartilage (aggrecans). Estimate of content at different ages and in osteoarthritis.

Sequencing of cDNA clones has shown that the carboxy terminal domain of the core protein of large proteoglycans (aggrecans) from human cartilage contains an epidermal growth factor-like (EGF-like) domain which is alternatively spliced. In a previous study it was found that the domain of the translated protein can be recognized by polyclonal antibodies to mouse EGF. A competitive enzyme-linked immunoabsorbent (ELISA) assay has been developed to evaluate the EGF-like domain content of aggrecans at various ages and in osteoarthritis. Fetal aggrecans digested with protease free chondroitinase ABC were adsorbed on polyvinyl chloride microtiter plates followed by blocking with bovine serum albumin and goat serum. Mixtures of known amounts of protein of digested aggrecans and constant amounts of anti-mouse EGF antibodies were incubated and added to plates. The second antibody was peroxidase-conjugate F(ab')2. Fetal, newborn and child aggrecan proteins have a higher content of EGF-like domain than aggrecan proteins from cartilage of older humans. Three areas of cartilages from osteoarthritic joints were separated: cartilages with normal macroscopic appearance, erosion border cartilage and osteophytic cartilage. Values derived from these samples were compared with values derived from nonosteoarthritic aged humans. The content of aggrecans from osteoarthritic cartilage with normal macroscopic appearance was similar to or slightly lower than the latter. The aggrecans from osteophytes had a higher EGF-like domain content. The aggrecans from the erosion border had a variable content, close to noneroded cartilages, to osteophytes or in between the values obtained for noneroded cartilages and for osteophytes. Variations in the amount of newly synthesized aggrecans, in the proteolysis of the carboxy terminal domain of aggrecans and in the alternating splicing of the EGF-like domain might explain the results shown here.

Multiple epiphyseal dysplasia, Fairbank type: morphologic and biochemical study of cartilage.

We have performed histochemical, immunohistochemical, electron microscopic, and biochemical studies on the upper tibial cartilage from a case of multiple epiphyseal dysplasia, Fairbank type. Most chondrocytes had intracytoplasmic inclusions which took the stains for proteins and were resistant to microbial collagenase digestion. The electron microscopic study showed that the inclusions are dilatations of the rough endoplasmic reticulum containing a material with alternately wide electron dense and electron lucent layers. Both in optical and in electron microscopy the inclusions fixed antibodies against the core protein of the large cartilage proteoglycans (aggrecans). They didn't stain with antibodies against type II collagen. The gel electrophoretic pattern of the large proteoglycans was different from normal controls. The morphologic and biochemical alterations found in multiple epiphyseal dysplasia are similar to those already described in pseudoachondroplasia (Stanescu et al.: Eur J Pediatr 138:121-225, 1982; Stanescu et al.: J Bone Joint Surg 66A:817-836, 1984). However, the inclusions are smaller and the growth cartilage much less disorganized in multiple epiphyseal dysplasia. The similarity of morphologic and biochemical abnormalities strongly suggests that the two diseases have a similar pathogenesis and belong to the same bone dysplasia family.

Early lesions of the articular surface in a strain of mice with very high incidence of spontaneous osteoarthritic-like lesions.

Our study was designed to see if the lesions of the articular surface represent an early event in the development of some types of articular degeneration. We examined the ultrastructural appearance of the articular surface labelled in vitro with cationized ferritin in several age groups of a substrain of C57BL/6 mice that develop a high incidence of osteoarthritic-like lesions. We found that as early as the age of 2 1/2 months the articular femoral and patellar surfaces presented abnormalities that became more severe with age. Alterations of the articular surface is a precocious event in this type of osteoarthritic-like degeneration.

Type II collagen defect in two sibs with the Goldblatt syndrome, a chondrodysplasia with dentinogenesis imperfecta, and joint laxity.

We report on a syndrome of spondylo-epimetaphyseal dysplasia, dentinogenesis imperfecta, and ligamentous hyperextensibility in two sibs born to nonconsanguineous parents. This chondrodysplasia was characterized by severe shortness of stature and an osteoporosis without fractures. Electron microscopic examination of the cartilage documented large vacuoles of dilated rough endoplasmic reticulum within the cytoplasm of chondrocytes. Gel electrophoresis of pepsin-soluble collagen extracted from cartilage demonstrated the presence of type II collagen chains with an abnormal mobility. Prolyl and lysyl hydroxylations were slightly increased. The abnormal molecules melted at a higher temperature than the normal ones. CNBr peptide mapping of type II collagen showed an altered electrophoretic migration of peptides CB 11, CB 8, and CB 10,5 whereas CB 9,7 looked normal. In addition, two small non-collagenous proteins isolated from cartilage were not found in an age-matched control individual but were detected in a normal newborn infant. The quantitation of proline-labelled collagen synthesized by dermal fibroblasts demonstrated a 50% reduction of total collagen. This decrease essentially affected the amount of extracellular type I collagen, which was secreted less efficiently than in control cells. Nevertheless, type I collagen chains behaved normally on 5% polyacrylamide gels. The reduced mRNA levels of alpha 1I and alpha 2I chains might reflect either a transcriptional defect or a decreased stability of mRNA transcripts. We suggest that the association of both pathological chondrocytes producing altered collagen type II and decreased synthesis of type I could be responsible for this peculiar phenotype. The overmodification of alpha 1II CNBr peptides is consistent with the presence of a single-base substitution in the COL2A1 gene. Whether there is a direct causal relationship between the type II collagen defect and the underexpression of type I collagen will require clarification.

The gene for hereditary multiple exostoses does not map to the Langer-Giedion region (8q23-q24).

Hereditary multiple exostoses is a dominantly inherited skeletal disorder which alters enchondral bone during growth and is characterised by exostoses of the juxta-epiphyseal regions. Using polymorphic DNA probes, we have been able to exclude the disease gene from close proximity to the 8q24.1 region where a dominant syndrome with multiple exostoses, the trichorhinophalangeal syndrome type II (TRP II, Langer-Giedion syndrome, MIM 15025), has been previously localised (pairwise linkage Z = -8.96 at theta = 0 with probe L48 at locus D8S51). Multipoint linkage analysis using probes L48, L24, and L1 consistently excluded the HME gene from a large area of the distal long arm of chromosome 8, spanning the smallest region of overlap assigned to the TRP II gene. These studies support the clinical view that HME and TRP II are distinct entities.

Variability in the G3 domain content of bovine aggrecan from cartilage extracts and chondrocyte cultures.

The content of the globular domains G1, G2 and G3 on the core protein of high-density (A1D1) aggrecan isolated from newborn and mature bovine cartilage and from cultures of bovine chondrocytes was examined. Quantitation based on the 220 nm absorbance of tryptic marker peptides from each domain isolated by reversed-phase HPLC showed that while the content of G1 and G2 was essentially the same for all samples, the content of G3 varied markedly. The molar yield of G3 and G1 marker peptides indicated that approximately 55% of the G1-bearing aggrecan from immature cartilage carried the G3 domain, while for mature cartilage this figure was markedly reduced, at about 35%. Aggrecan prepared from the cell layer matrix of calf chondrocyte cultures had an apparent G3 content similar to newborn cartilage (55%), whereas aggrecan prepared from the medium of these cultures had a markedly higher G3 content, at about 80%. The high content of G3 in cell medium samples compared to cartilage extracts was supported by electron microscopic analysis of A1D1 preparations. The G3 content of the two subpopulations of aggrecan present in mature cartilage and separable by flat bed agarose gel electrophoresis was also determined at about 45% (Band I) and 20% (Band II) respectively. These results are discussed in terms of the likely origin of the marked variability in the G3 domain content of aggrecan.

Lethal short limb dwarfism with dysmorphic face, omphalocele and severe ossification defect: Piepkorn syndrome or severe "boomerang dysplasia"?

The authors report a case of lethal neonatal dwarfism characterized by striking micromelia, fused rudimentary and supernumerary digits, large, soft head, pronounced hypertelorism, protruding eyes set laterally, enormous omphalocele and severe deficiency of tubular bone and spine ossification. Histologic examination showed lack of ossification of the cartilaginous anlage of many tubular bones. The cartilage had irregularly distributed chondrocytes. The matrix contained hypocellular and degenerated areas with scattered large chondrocytes. In a few bones a very disorganized growth cartilage was present. The case is similar to that described by Piepkorn et al. (1977) and may represent a severe form of "boomerang dysplasia" (Kozlowski et al., 1981; Tenconi et al., 1983; Kozlowski et al., 1985; Winship et al., 1990).

Desbuquois syndrome.

Three patients with short stature, joint laxity, and peculiar pelvic radiology are described. The first case is similar to those described by Desbuquois et al., with deviation of digitis and supernumerary metacarpal bones. The other two children are less severely affected and are compared with others reported in literature. The authors suggest the homogeneity of the Desbuquois syndrome in spite of the variability of expression.

Prenatal diagnosis of lethal osteogenesis imperfecta in twin pregnancy.

Lethal osteogenesis imperfecta was diagnosed at 27 weeks amenorrea in one fetus of a bichorial twin pregnancy. Sonographic findings included: short-limb dwarfism, hypotrophy and hypoechoic bones. The affected fetus was so translucent that only the normal fetus could be seen on plain in utero radiography. The affected fetus died immediately after birth. Postmortem radiography and histology were typical of lethal osteogenesis imperfecta of type IIA. Aids to the etiological diagnosis of in utero dwarfism are presented. Sonographic features correlated with neonatal death are described.

Metaphyseal anadysplasia: a metaphyseal dysplasia of early onset with radiological regression and benign course.

We report on 4 boys (including 2 maternally related first cousins) with a metaphyseal dysplasia of early onset and regressive evolution. Diagnosis is possible in the first months. Distal metaphyses of long bones are very irregular. Femoral necks seem hypoplastic and the edges of the metaphyses are almost vertical; femoral shaft is bowed. Those anomalies disappear after 2 years. The main manifestations are slight shortness and a light varus deformity of the lower limbs. Stature is not affected. The upper tibial growth cartilage, studied in one case, showed wide proliferative and hypertrophic zones with an unusual appearance of the last hypertrophic cells and an abnormal zone of cartilage calcification and resorption. The name "metaphyseal anadysplasia" is suggested for this early and regressive disorder. We are aware of other forms of regressive metaphyseal dysplasia which deserve further delineation. Therefore infants whose radiological changes of metaphyseal dysplasia do not fall into one of the well-defined types should be followed and prediction of the adult height should not be made on the basis of the findings on the initial examination.

Nucleolysis of the rabbit intervertebral disc using chondroitinase ABC.

The nucleolytic action of chondroitinase ABC was studied by the use of rabbit lumbar intervertebral discs. The injection of one unit of enzyme results in necrosis of the nucleus pulposus. Radiologic, histologic, and biochemical changes were evident in discs studied 2 days after injection, and consistent nucleolysis was seen in those studied after 6 days. These results show that chondroitinase ABC deserves further evaluation as a possible chemonucleolytic enzyme.

Morphological and biochemical studies of a mouse mutant (fro/fro) with bone fragility.

The mutation fragilitas ossium (fro) was discovered in a random-bred stock of mice during an experiment aimed at detecting recessive lethal mutations after treatment of the postmeiotic germ cells of male mice with tris (1-aziridinyl)phosphine sulphide. The affected mice were moderately runted and had deformities in all four limbs. The radiological and histological findings indicate that the mutant is similar to human osteogenesis imperfecta. The ash content of long bones was lower in the mutant. A defect of type I collagen could not be detected. The electrophoretic patterns of alpha bands of type I and V collagen and CB derived peptides of type I collagen from bone and skin showed no abnormalities. The total collagen synthesis and secretion in cultures of dermal fibroblasts, as well as the gel electrophoresis of procollagen and collagen chains synthesized, and of their CB peptides, were the same as those found in the controls. The percentage of type I and type V collagen synthesized was similar; that of type III was lower in the mutants. Bone osteonectin was found to be decreased by 30% and bone sialoprotein by 5%. The mRNA level for osteonectin was decreased in the fibroblasts of the mutant by about 50%. Whether the defective expression of the osteonectin in fro/fro mice is due to a mutation in the gene itself or its regulatory site(s), or is secondary to other factors remains to be established. The fro/fro mouse may represent a model for some forms of human bone fragility without collagen abnormalities.

Immunological detection of the EGF-like domain of the core proteins of large proteoglycans from human and baboon cartilage.

Recent data from the literature have shown that cDNA clones for the carboxyterminal domain of the core protein of large proteoglycan monomers from human cartilage contain an EGF-like domain, which appears to undergo alternative splicing. In the present study we have found that articular proteoglycans from human and baboon separated on agarose flat-bed gels and blotted onto nitrocellulose react with a rabbit antiserum to mouse EGF. In addition both forms of the proteoglycans (band I and band II) seen on these gels are reactive. Reactivity is seen with proteoglycans extracted from human articular cartilage of various ages (fetal, newborn, young and aged) and with proteoglycans extracted from cartilage of thanatophoric dysplasia and homozygous achondroplasia. Reactivity is dependent on prior digestion of the nitrocellulose blot with Chase ABC, suggesting masking of epitope by chondroitin sulfate. Reactivity of the EGF antiserum with cartilage proteoglycan core protein was also demonstrated in an ELISA system with core protein as coating antigen. The reactivity appears to reside in a tryptic peptide generated from Chase/keratanase digested core protein. The immunoreactive species migrates as a 68 KDa species on gradient gels. Immunological detection and quantitative analysis of the EGF-like domain could be useful for analysis of various proteoglycan samples.