In vitro tetracycline labelling and bone cell survival in human trabecular bone explants

Results are presented which document the feasibility and utility of human trabecular bone explants for in vitro bone research. This approach is advantageous because it allows bone cells to maintain their natural orientation on the endosteal surface, and keeps surrounding marrow intact--thus retaining the immediate local microenvironment. In addition, bone cells are not exposed to transient, but sometimes harsh, isolation procedures. Data are presented which show greater initial bone cell numbers from younger donors and the change in these numbers over culture periods up to 21 days. A technique is presented which achieves single and double tetracycline label incorporation into the mineralizing front of bone explants in vitro using a pulse-chase methodology.

New epiphyseal stippling syndrome with osteoclastic hyperplasia

We present a lethal skeletal dysplasia characterized radiographically by severe stippling of the lower spine and long bones and periosteal cloaking. In contrast to the normal morphology of the epiphyses and growth plates, the marrow was filled with loose fibrous tissue containing numerous large multinucleated osteoclasts which were associated with Howship's lacunae on the endosteal surface. We suggest the term "Pacman dysplasia" to describe this unusual histologic change that characterizes this new bone dysplasia.

Spondylo-meta-epiphyseal dysplasia (SMED), short limb-hand type: a congenital familial skeletal dysplasia with distinctive features and histopathology

We report on a "new" severe short-limb bone dysplasia which can be labeled descriptively a spondylo-meta-epiphyseal dysplasia. The 3 patients were born to 2 unrelated Sepharadic Jewish families and a Puerto Rican family. Clinical abnormalities include small stature with short limbs including short hands, a short nose with wide nasal bridge and wide nostrils, a long philtrum, ocular hypertelorism, retro/micrognathia, and a narrow chest. Radiological abnormalities include platyspondyly, short tubular bones with very abnormal metaphyses and epiphyses beyond early infancy, short ribs, and a typical evolution of bony changes over time. Chondroosseous morphology and ultrastructure document sparse matrix and degenerating chondrocytes surrounded by dense amorphous material in the 1 patient studied. Consanguinity is present in 1 family. In addition to the described patient, 2 other short-limb sibs, who did not survive infancy, were born into this family. Even in the absence of any photographic or radiologic documentation of these other 2 infants, autosomal recessive mode of inheritance seems probable.

Bone remodelling in the presence of chondrosarcoma: histomorphometry

Accurate knowledge of tissue changes near bone tumors can contribute to a better understanding of tumor behavior. We have used tumor ultrastructure and quantitative bone histomorphometry to evaluate local bone/tumor features associated with a low grade chondrosarcoma in a 39-year-old male. Three noninvolved sites and two sites near the tumor in the proximal femur were studied with bone morphometry. Bone near the tumor showed increased percent osteoid surface, percent osteoid volume and fraction of osteoid surface lined by osteoblasts compared to distant noninvolved sites. Both the number of osteoblasts and mean individual osteoblast size were significantly increased compared to noninvolved sites. Osteoclast number and percent osteoclast surface were also increased near the tumor. Ultrastructural studies of tumor tissue revealed two types of tissue: synthetic mesenchymal cells and cartilage tissue. Results indicate increased bone formation and resorption near the tumor. These local bone changes may possibly reflect responses to local tumor factors and depend on the extent of the tumor.

Spondylometaphyseal dysplasia, Sedaghatian type

In 1980 Sedaghatian described an Iranian infant who died shortly after birth. At autopsy, he was found to have subacute myocarditis, cortical necrosis of kidneys, and adrenal and pulmonary hemorrhage. His skeletal abnormalities included mild rhizomelic shortness of his limbs and platyspondylyl and "laciness" of the iliac wings. In 1987 Optiz et al. described another Iranian infant with a similar perinatal course and roentgenograms. This infant was born to first cousins, suggesting an autosomal recessive single gene defect. We report our findings of another infant with a lethal course.

An amino acid substitution (Gly853-->Glu) in the collagen alpha 1(II) chain produces hypochondrogenesis

The spondyloepiphyseal dysplasia subclassification of bone dysplasias includes achondrogenesis, hypochondrogenesis, and spondyloepiphyseal dysplasia congenita. The phenotypic expression of these disorders ranges from mild to perinatal lethal forms. We report the detection and partial characterization of a defect in type II collagen in a perinatal lethal form of hypochondrogenesis. Electrophoresis in sodium dodecyl sulfate-polyacrylamide of CB peptides (where CB represents cyanogen bromide) from type II collagen of the diseased cartilage showed a doublet band for peptide alpha 1(II)CB10 and evidence for post-translational overmodification of the major peptides (CB8, CB10, and CB11) seen as a retarded electrophoretic mobility. Peptide CB10 was digested by endoproteinase Asp-N; and on reverse-phase high pressure liquid chromatography, fragments of abnormal mobility were noted. Sequence analysis of a unique peptide D12 revealed a single amino acid substitution (Gly-->Glu) at position 853 of the triple helical domain. This was confirmed by sequence analysis of amplified COL2A1 cDNA, which revealed a single nucleotide substitution (GGA-->GAA) in 5 of 10 clones. Electron micrographs of the diseased cartilage showed a sparse extracellular matrix and chondrocytes containing dilated rough endoplasmic reticulum, which suggested impaired assembly and secretion of the mutant protein. This case further documents the molecular basis of the spondyloepiphyseal dysplasia spectrum of chondrodysplasias as mutations in COL2A1.

Bone response to invading tumors with spindle cell components: a report of findings in two patients

Two case studies are presented in which quantitative bone histomorphometry is used to analyze bone changes in adult patients with diagnosed spindle cell sarcoma. Three tumor-involved sites and one noninvolved site from the iliac crest of patient 1 were evaluated. In the involved sites the percentage trabecular bone volume (11.0%) and the number of osteoblasts (0.6 cell/mm2) were significantly reduced, osteoid volume was significantly increased (8.1%), and woven osteoid was present. The total eroded surface (6.8%) was also significantly increased. In the noninvolved site the number of osteoblasts was decreased and both the percentage eroded and percentage osteoclast surfaces were increased. In the femoral epicondyle specimen from patient 2 the number of osteoblasts was 27.0 cells/mm2, percentage osteoid volume was 18.4%, percentage osteoid surface was 62.9%, and osteoid thickness was 20.0 microns. In tumor-involved sites in both patients indices of active bone resorption were similar and normal. These two case studies indicate that (1) distinctive morphologic changes occur in bone invaded by spindle cell sarcoma, and that (2) changes affect bone formation to a greater extent than bone resorption. Bone alterations are probably local in nature and related to the extent and duration of tumor invasion and the influence of local tumor factor(s).

Lack of effect of ovariectomy on divalent cation regulation of skeletal adenylate cyclase

Both estrogen and androgen have been reported to attenuate cyclic AMP responses to parathyroid hormone stimulation in cultured bone cells. The present study examines the effect of in vivo estrogen deficiency on skeletal adenylate cyclase (AC) activity. The AC activity was compared in bone membranes prepared from normal female guinea pigs and from age-matched guinea pigs 3 weeks after ovariectomy. Histomorphometric analysis of femoral specimens from the ovariectomized guinea pigs demonstrated significant decreases in percentage bone volume, the percentage eroded surfaces and osteoclast numbers, and increased osteoid thickness, compared with the normal controls. No differences were found in basal AC activity, the ability of bone AC to be stimulated by parathyroid hormone (bPTH(1-34)) or isoproterenol, or in the regulation of AC activity by calcium and magnesium. We conclude that bone AC is not a direct target for estrogen effects on bone cells and that the reported effects of sex steroids on cAMP levels in bone cells probably act via an indirect mechanism.

Adaptations of Goldner's Masson trichrome stain for the study of undecalcified plastic embedded bone

Specialized adaptations for application of Goldner's Masson trichrome stain to plastic embedded undecalcified bone specimens are presented. This stain can be used successfully on methyl-glycol methacrylate, glycol methacrylate and Spurr embedded bones. The stain affords the advantage of good cellular staining due to the hematoxylin component with concomitant sharp discrimination of mature bone matrix which stains green, immature new bone matrix which stains red, and calcified cartilage which stains very pale green. Use of red filters during photomicrography aids in bone-osteoid discrimination in black and white photographs.

Antagonism of airway reactivity induced by ovalbumin antigen in guinea pigs by 5-amino-4-imidazolecarboxamide riboside

The effect of 5-amino-4-imidazolecarboxamide riboside (AICA riboside), a modulator of purine metabolism, was studied on antigen-induced bronchospasm in ovalbumin (OA)-sensitized guinea pigs. In separate experiments, sodium cromoglycate (SCG) and terbutaline were used to compare their effectiveness with that of AICA riboside (wt/vol). AICA riboside and SCG were administered as an aerosol daily for a minimum of 2 weeks before OA aerosol challenge. Terbutaline, as an aerosol, was administered once 5 minutes before OA challenge. Airway reactivity was determined through the use of a whole-body plethysmography by monitoring specific airway resistance (SRaw). OA aerosol challenge of 0.05%, 0.1%, and 0.25% (wt/vol), administered for a period of 1 minute, increased SRaw. Each of the three agents attenuated the effect of OA on SRaw, although terbutaline demonstrated more consistency and potency as compared to either AICA riboside or SCG. However, at moderate degrees of OA challenge, AICA riboside appeared to be as effective as either agent. Although the mechanism of action of AICA riboside remains uncertain, it may have therapeutic benefit in the treatment of asthma or allergic diseases.

Inhibition by AICA riboside of gluconeogenesis in isolated rat hepatocytes

5-Amino-4-imidazolecarboxamide (AICA) riboside, the nucleoside corresponding to AICA ribotide (AICAR or ZMP), an intermediate of the de novo pathway of purine biosynthesis, was found to exert a dose-dependent inhibition on gluconeogenesis in isolated rat hepatocytes. Production of glucose from lactate-pyruvate mixtures was half-maximally inhibited by approximately 100 microM and completely suppressed by 500 microM AICA riboside. AICA riboside also inhibited the production of glucose from all other gluconeogenic precursors investigated, i.e., fructose, dihydroxyacetone, and L-proline. Measurements of intermediates of the glycolytic-gluconeogenic pathway showed that AICA riboside provoked elevations of triose phosphates and fructose-1,6-bisphosphate and decreases in fructose-6-phosphate and glucose-6-phosphate. The effects of AICA riboside persisted when the cells were washed 10 min after its addition but were suppressed by 5-iodotubercidin, an inhibitor of adenosine kinase. AICA riboside provoked a dose-dependent buildup of normally undetectable Z nucleotides. After 20 min of incubation with 500 microM AICA riboside, ZMP, ZTP, and ZDP reached 3, 0.3, and 0.1 mumol/g cells, respectively. Concentrations of ATP were not significantly modified by addition of up to 500 microM AICA riboside when the cells were incubated with lactate-pyruvate but decreased with fructose or dihydroxyacetone. The activity of rat liver fructose-1,6-bisphosphatase was inhibited by ZMP with an apparent Ki of 370 microM. It is concluded that AICA riboside exerts a suppressive effect on gluconeogenesis because it provokes an accumulation of ZMP, which inhibits fructose-1,6-bisphosphatase.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone and the immune system

There are several lines of evidence which provide support for an important relationship between immune cells and bone. Clinical studies of immunodeficiency syndromes have shown that abnormalities in bone shape are evident on x-rays, and peculiarities in the structure of the growth plate have been identified by histopathology. Studies of bone histology, and quantitation of cellular abnormalities, are scarce. Abnormalities in bone turnover, have, however, been identified in the nude mouse model. Many lines of evidence derived from in vitro bone studies have shown that lymphokines and monokines can influence bone formation and bone resorption. Some clinical studies of postmenopausal osteoporosis have indicated the possible presence of immune cell changes in this condition. Although several hypotheses have been formed regarding the exact mechanisms of the effect of immune cytokine on bone, this is clearly a very large area of study and there is a need for additional carefully controlled experiments with special emphasis on bone cells and bone matrix, especially in the human. As knowledge progresses regarding immunology and hematology, a clearer understanding of the lineages of the osteoblast and osteoclast will emerge and we will better understand how specialized bone cells interact with and react to their immune cell neighbors in the bone marrow and to immune system signals. These findings will have especially important implications for the local bone loss seen in rheumatoid arthritis, periodontal disease, and chronic osteomyelitis.

The effects of fluoride on bone

Fluoride has often been used as a treatment for osteoporosis, a metabolic bone disease of considerable importance in the elderly population. The techniques currently used to monitor a patient's response to fluoride are outlined. New findings concerning (1) a mechanism for interaction of fluoride with osteoblasts (via mitogenic signals or growth factors); (2) toxicity and carcinogenesis; (3) recent clinical trial data; and (4) the importance of dosage, administration regimens, and side effects in an effective fluoride treatment protocol are reviewed. Some recent clinical data challenge the efficacy of fluoride in the treatment of postmenopausal osteoporosis. Because of the implications of these recent studies with respect to fracture incidence during fluoride therapy, fluoride cannot be recommended at this time for general use in the treatment of osteoporosis.

Methotrexate inhibits neutrophil function by stimulating adenosine release from connective tissue cells

Although commonly used to control a variety of inflammatory diseases, the mechanism of action of a low dose of methotrexate remains a mystery. Methotrexate accumulates intracellularly where it may interfere with purine metabolism. Therefore, we determined whether a 48-hr pretreatment with methotrexate affected adenosine release from [14C]adenine-labeled human fibroblasts and umbilical vein endothelial cells. Methotrexate significantly increased adenosine release by fibroblasts from 4 +/- 1% to 31 +/- 6% of total purine released (EC50, 1 nM) and by endothelial cells from 24 +/- 4% to 42 +/- 7%. Methotrexate-enhanced adenosine release from fibroblasts was further increased to 51 +/- 4% (EC50, 6 nM) and from endothelial cells was increased to 58 +/- 5% of total purine released by exposure to stimulated (fMet-Leu-Phe at 0.1 microM) neutrophils. The effect of methotrexate on adenosine release was not due to cytotoxicity since cells treated with maximal concentrations of methotrexate took up [14C]adenine and released 14C-labeled purine (a measure of cell injury) in a manner identical to control cells. Methotrexate treatment of fibroblasts dramatically inhibited adherence to fibroblasts by both unstimulated neutrophils (IC50, 9 nM) and stimulated neutrophils (IC50, 13 nM). Methotrexate treatment inhibited neutrophil adherence by enhancing adenosine release from fibroblasts since digestion of extracellular adenosine by added adenosine deaminase completely abrogated the effect of methotrexate on neutrophil adherence without, itself, affecting adherence. One hypothesis that explains the effect of methotrexate on adenosine release is that, by inhibition of 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) transformylase, methotrexate induces the accumulation of AICAR, the nucleoside precursor of which (5-aminoimidazole-4-carboxamide ribonucleoside referred to hereafter as acadesine) has previously been shown to cause adenosine release from ischemic cardiac tissue. We found that acadesine also promotes adenosine release from and inhibits neutrophil adherence to connective tissue cells. The observation that the antiinflammatory actions of methotrexate are due to the capacity of methotrexate to induce adenosine release may form the basis for the development of an additional class of antiinflammatory drugs.

Transplantation of vascularized composite mandibular allografts in young cynomolgus monkeys

In the search for donor tissue for massive craniofacial defects, the transplantation of somatic tissue allografts was explored. Four young, out-bred cynomolgus monkeys were the recipients of orthotopic hemimandibular allotransplants from nonrelated cynomolgus monkeys. The transplant consisted of one-half of the mandible with attached muscle, skin, and mucosa. Cyclosporine 15 mg/kg/day was given subcutaneously each day. The 4 monkeys were observed for 13, 27, 63, and 65 days, respectively. All transplants showed primary wound healing and hair growth. The 2 longest survivors chewed, ate a normal diet, and gained weight. Two allografts showed severe rejection signs at 2 to 3 weeks, and the monkeys were euthanized. One monkey had a second episode of rejection that could not be reversed, and it was killed. The fourth monkey died of undetermined causes.

Application of stains-all for demarcation of cement lines in methacrylate embedded bone

Cement lines provide a record of sites of past remodeling buried in the matrix of bone. A method is reported for application of Stains-all, a cationic carbocyanine dye, for demarcation of cement lines in bone. The method, which is simple, works well for both glycol methacrylate and methyl methacrylate undemineralized embedments and produces good concomitant staining of cytoplasm and nuclei of osteoblasts, osteoclasts and marrow cells.

Perinatal lethal hypophosphatasia; clinical, radiologic and morphologic findings

Clinical, radiographic and morphologic analysis of nineteen cases of perinatal (lethal) hypophosphatasia was performed. Three families each had two affected offspring. All of the patients had lethal short limb dwarfism with very soft calvaria. Other clinical findings included polyhydramnios, blue sclerae and spurs in the mid-portion of the forearms and lower legs. Considerable variability was found in the skeletal radiographs. In addition to the well known radiographic features such as generalized decrease in the size of ossified bones with some bones not ossified at all, other changes observed included: 1) marked variability in the amount of bone ossification; 2) variability between patients as to which bones were most severely affected; 3) unusually dense, round, flattened, butterfly shaped; and sagittally clefted vertebral bodies; 4) variability in femoral shape including "chromosome" like, "campomelic" like, and shortening with or without metaphyseal cupping or irregularities; 5) osteochondral projections (Bowdler spurs) of the midshaft of the fibula and ulna. Recognition of the marked clinical and radiographic variability in this autosomal recessive lethal skeletal dysplasia is important for accurate genetic counseling and prenatal diagnosis.

Quantitative histology of cartilage vascular canals in the human rib. Findings in normal neonates and children and in achondrogenesis II-hypochondrogenesis

Knowledge of the structure of cartilage vascular canals is important for a more thorough understanding of the development of cartilage and the growth plate in the human neonate and growing child. We have studied the costochondral junction of 6 normal neonates and 12 normal children (age 4 months-16 years) and utilised quantitative histomorphometry to define the percentage tissue area occupied by canals and the number of canals/mm2. Both percentage canal area and the number of canals/mm2 were significantly greater in newborn vs. older children (percentage area: 0.42 +/- 0.15 (mean +/- S.E.M.) vs. 0.08 +/- 0.04, P = 0.003; number/mm2: 0.2 +/- 0.09 vs. 0.04 +/- 0.02, P = 0.02). Eight newborn patients with achondrogenesis II-hypochondrogenesis were also studied. Both percentage canal area and number were significantly elevated above normal (percentage area: 5.22 +/- 1.01, P less than 0.001; number/mm2: 1.45 +/- 0.26, P less than 0.001). Results presented here demonstrate that: (i) quantitative differences in vascular canal area and numbers occur during development; (ii) 10-fold increases in vascular canal area and number are present in achondrogenesis II-hypochondrogenesis. Data from normal subjects will provide normative values against which vascular abnormalities in other skeletal dysplasias can be compared.

Alteration of purine metabolism by AICA-riboside in human B lymphoblasts

The effect of 5-amino-4-imidazole-carboximide (AI-CA)-riboside on different pathways of purine metabolism (biosynthesis de novo, salvage pathways, adenosine metabolism, ATP catabolism) was studied in human B lymphoblasts (WI-L2). AICA-Riboside markedly decreased intracellular levels of 5-phosphoribosyl-1-pyrophosphate and in consequence affected purine biosynthesis de novo and purine salvage pathways. AICA-riboside inhibited incorporation of glycine into purine nucleotides, but when formate was used as the precursor of purine biosynthesis de novo, a biphasic effect was observed. The incorporation of formate into purine nucleotides was increased by AICA-riboside at concentrations up to 2 mM but decreased at higher concentrations. Salvage of the purine bases adenine, hypoxanthine, and guanine was markedly inhibited and utilization of extracellular adenosine in B lymphoblasts was reduced by AICA-riboside. AICA-riboside increased ribose 1-phosphate concentrations and increased degradation of prelabeled ATP. No effect on the intracellular levels of orthophosphate was found. Proliferation of WI-L2 lymphoblasts was only slightly affected at concentrations of AICA-riboside below 500 microM but markedly inhibited by higher concentrations.

Selective adenosine release from human B but not T lymphoid cell line

Intracellular adenosine formation and release to extracellular space was studied in WI-L2-B and SupT1-T lymphoblasts under conditions which induce or do not induce ATP catabolism. Under induced conditions, B lymphoblasts but not T lymphoblasts, release significant amounts of adenosine, which are markedly elevated by adenosine deaminase inhibitors. In T lymphoblasts, under induced conditions, only simultaneous inhibition of both adenosine deaminase activity and adenosine kinase activities resulted in small amounts of adenosine release. Under noninduced conditions, neither B nor T lymphoblasts release adenosine, even in the presence of both adenosine deaminase or adenosine kinase inhibitors. Comparison of B and T cell's enzyme activities involved in adenosine metabolism showed similar activity of AMP deaminase, but the activities of AMP-5'-nucleotidase, adenosine kinase and adenosine deaminase differ significantly. B lymphoblasts release adenosine because of their combination of enzyme activities which produce or utilize adenosine (high AMP-5'-nucleotidase and relatively low adenosine kinase and adenosine deaminase activities). Accelerated ATP degradation in B lymphoblasts proceeds not only via AMP deamination, but also via AMP dephosphorylation into adenosine but its less efficient intracellular utilization results in the release of adenosine from these cells. In contrast, T lymphoblasts release far less adenosine, because they contain relatively low AMP-5'-nucleotidase and high adenosine kinase and adenosine deaminase activities. In T lymphoblasts, AMP formed during ATP degradation is not readily dephosphorylated to adenosine but mainly deaminated to IMP by AMP deaminase. Any adenosine formed intracellularly in T lymphoblasts is likely to be efficiently salvaged back to AMP by an active adenosine kinase. In general, these results may suggest that adenosine can be produced only by selective cells (adenosine producers) whereas other cells with enzyme combination similar to SupT1-T lymphoblasts can not produce significant amounts of adenosine even in stress conditions.

Calcospherite (calcification nodule) size in the short rib polydactyly syndromes

The short rib polydactyly syndromes (SRP) are lethal neonatal skeletal dysplasias with a narrow chest, short limbs, and other abnormalities. Type II (Majewski) short rib polydactyly can be distinguished from the Type I/III (Saldino-Noonan) type on the basis of radiographic and histologic changes. Our previous transmission electron microscopic studies suggested unusual patterns of cartilage calcification in these syndromes. We evaluate calcification in the present study using scanning electron microscopy and quantitative morphometry of calcification regions digested to expose calcospherite nodules (calcification nodules), distinctive morphologic structures which form during cartilage calcification. Mean calcospherite area of the Majewski Type II SRP (3.5 +/- 0.24 x 10(-6) mm2 (3) (mean +/- sem (n) did not differ from normal control means (3.1 +/- 0.5 x 10(-6) mm2, (3)). The mean area for Type I/III, however, was significantly larger than both the control and Type II means (8.9 +/- 1.16 x 10(-6) mm2 (7), p = .001). This difference in calcospherite size adds a further differentiating feature between these two dysplasias.

Geleophysic dysplasia: a storage disorder affecting the skin, bone, liver, heart, and trachea

Geleophysic dysplasia is characterized by typical facies ("happy natured"), small hands and feet, short stature, hepatomegaly, and progressive cardiac disease. We describe five patients (two of whom are siblings) with this disorder and document its variable expressivity. The facies were strikingly similar with small nose, anteverted nostrils, broad nasal bridge, and long thin upper lip with flat and long philtrum. Behavior, development, and intelligence were normal. Growth delay was noticed during infancy, and the two patients who completed normal puberty had marked short stature (140 and 150 cm), with relatively lean body habitus. The hands and feet were small, with short, plump tubular bones and broad proximal phalanges, associated with marked limitation in motion of fingers and wrists. The liver was enlarged after the age of 3 years. Two patients had mild mitral and tricuspid valve stenosis and one had severe aortic stenosis. The most severely affected child died at 3 1/2 years of age of airway obstruction as a result of progressive tracheal narrowing. Lysosomal storage vacuoles were found in skin epithelial cells from three patients whose skin was examined, and in the tracheal mucosa, liver, cartilage and macrophages of the child who died. The basic defect of this autosomal recessive lysosomal storage disease remains to be determined.