A Study of Morphological Characteristics of Lung Fissures and Trachea in the Indian Population

Tracheal length and lung anatomy have been rarely studied; however, the anatomy of the lung has been shown to vary significantly. Moreover, the surgery regarding trachea are few, and hence the surgeons do not have extensive experience in the trachea.

Objective: We aimed to study the variations of the lung anatomy and the relation between tracheal length and body height in the Indian population.

Materials and methods: This is an observational study to observe the tracheal length in relation to body height and sex and gross morphological anatomy of the lung in 70 cadavers. The data was collected from the forensic department of Bangalore Medical College and Research Institute (BMCRI), and further analysis was done at Kidwai Memorial Institute of Oncology.

Results: Deviation from normal lung morphology was seen in 37.86% of the specimens studied. The tracheal length (average, 9.97 cm) correlated with the body length (average, 147.02 cm) with a Pearson coefficient of 0.806 (p value=0.001)

Conclusion: The study of lung fissure morphology guides clinicians in understanding and planning lung disease treatment, especially lobectomy/segmentectomy surgeries. The information of the average length of the trachea with respect to body height in a given ethnicity will help during endotracheal intubation and tracheal surgical planning.

Ischemia-modified albumin levels in overt and subclinical hypothyroidism

BACKGROUND

Free radical-mediated oxidative stress (OS) has been implicated in the pathogenesis of thyroid disorders. The ischemia-modified albumin (IMA) has been proposed as a marker of protein oxidative damage, which has been found to reflect hypoxic stress.

AIM

Our aim was to evaluate IMA, malondialdehyde (MDA), and reduced glutathione (GSH) levels in patients with overt hypothyroidism (OHT) and subclinical hypothyroidism (SHT) in comparison to euthyroid controls.

SUBJECTS AND METHODS

Albumin, IMA, IMA/albumin ratio, MDA, GSH, total cholesterol (TC), triglycerides (TG), HDL-Cholesterol were assessed in 105 subjects grouped into OHT, SHT patients, and euthyroid controls with 35 subjects in each group.

RESULTS

MDA and IMA levels were significantly elevated while the GSH concentrations were significantly lower in OHT and SHT patients compared to controls (p < 0.01). When IMA values were normalized for albumin concentrations, the IMA/albumin ratio was also significantly elevated in both patient groups compared to controls (p < 0.01). These changes were more pronounced in the OHT group when compared to SHT group. In OHT group, thyroid-stimulating hormone (TSH) levels showed significant positive correlation with MDA (r = 0.470, p = 0.004), IMA (r = 0.530, p = 0.001), and IMA/albumin ratio (r = 0.525, p = 0.001). Both IMA (r = -0.342, p = 0.041), IMA/albumin ratio (r = -0.378, p = 0.023) showed significant negative correlation with GSH in OHT patients. No significant correlation between variables was, however, observed in SHT group.

CONCLUSIONS

Increase of MDA and IMA levels with decreased antioxidant status indicate the presence of OS in hypothyroid patients, which was more pronounced in OHT patients. Elevated levels of IMA can be a clinically useful marker of protein oxidative damage and OS in hypothyroidism.

Atypical femoral shaft fracture in a patient with non-metastatic prostate cancer on zoledronic acid therapy: effect of therapy or coincidence?

There have been recent concerns of atypical non-spinal fractures in patients with osteoporosis who are on long-term bisphosphonate therapy. These fractures are less commonly reported in cancer patients on zoledronic acid therapy, where it is used in higher doses as compared to patients with osteoporosis. We report the case of a 70-year-old man with non-metastatic prostate cancer who was on androgen deprivation therapy following bilateral orchiectomy. He was on bone protection with intravenous zoledronic acid 4 mg monthly for a period of two years. He presented with spontaneous acute right mid-thigh pain. Radiograph of the right femur showed an atypical femoral shaft fracture, which was treated with intramedullary nailing and teriparatide. This case report raises concerns of atypical fractures in cancer patients who receive high doses of zoledronic acid. Patients receiving bisphosphonates who present with thigh or groin pain must undergo radiographic examination of the femur to rule out atypical femoral fractures.

CXCL13 activation of c-Myc induces RANK ligand expression in stromal/preosteoblast cells in the oral squamous cell carcinoma tumor-bone microenvironment

CXC chemokine ligand-13 (CXCL13) has been implicated in oral squamous cell carcinoma (OSCC) tumor progression and osteolysis. The tumor necrosis factor family member RANKL (receptor activator of NF-κB ligand), a critical bone resorbing osteoclastogenic factor, has an important role in cancer invasion of bone/osteolysis. Here, we show high-level expression of CXCL13 in primary human OSCC tumor specimens; however, human bone marrow-derived stromal (SAKA-T) and murine preosteoblast (MC3T3-E1) cells produce at very low level. Recombinant CXCL13 (0-15 ng/ml) dose dependently induced CXCR5 expression in SAKA-T and MC3T3-E1 cells. Conditioned media obtained from OSCC cell lines increased the RANKL expression and an antibody against the CXCL13 specific receptor, CXCR5 markedly decreased RANKL expression in these cells. Furthermore, CXCL13 increased hRANKL-Luc promoter activity. Superarray screening identified c-Myc and NFATc3 transcription factors upregulated in CXCL13-stimulated SAKA-T cells. Immunohistochemical analysis of OSCC tumors that developed in athymic mice demonstrated RANKL and NFATc3 expression in tumor and osteoblast cells, however, showed p-c-Myc expression specific to osteoblastic cells at the tumor-bone interface. We further identified NFATc3 expression, but not c-Myc activation in primary human OSCC tumor specimens compared with adjacent normal tissue. Also, CXCL13 significantly increased p-ERK1/2 in SAKA-T and MC3T3-E1 cells. siRNA suppression of c-Myc expression markedly decreased CXCL13-induced RANKL and NFATc3 expression in preosteoblast cells. Chromatin-immuno precipitation assay confirmed p-c-Myc binding to the hRANKL promoter region. In summary, c-Myc activation through CXCL13-CXCR5 signaling axis stimulates RANKL expression in stromal/preosteoblast cells. Thus, our results implicate CXCL13 as a potential therapeutic target to prevent OSCC invasion of bone/osteolysis.

Transgenic mice with OIP-1/hSca overexpression targeted to the osteoclast lineage develop an osteopetrosis bone phenotype

Regulatory mechanisms operative in bone-resorbing osteoclasts are complex. We previously defined the Ly-6 gene family member OIP-1/hSca as an inhibitor of osteoclastogenesis in vitro; however, a role in skeletal development is unknown. In this study, we developed transgenic mice with OIP-1/hSca expression targeted to the osteoclast lineage that develop an osteopetrotic bone phenotype. Humeri from OIP-1 mice showed a significant increase in bone mineral density and bone mineral content. microCT analysis showed increased trabecular thickness and bone volume. OIP-1 mice have dense sclerotic cortical bone with absence of spongiosa and inadequate formation of marrow spaces compared to wild-type mice. Moreover, complete inhibition of osteoclasts and marrow cavities in calvaria suggests defective bone resorption in these mice. OIP-1 mouse bone marrow cultures demonstrated a significant decrease (41%) in osteoclast progenitors and inhibition (39%) of osteoclast differentiation/bone resorption. Western blot analysis further demonstrated suppression of TRAF-2, c-Fos, p-c-Jun, and NFATc1 levels in RANKL-stimulated osteoclast precursors derived from OIP-1 mice. Therefore, OIP-1 is an important physiological inhibitor of osteoclastogenesis and may have therapeutic value against bone loss in vivo.

Etiologic factors in Paget’s disease of bone

Paget's disease of bone is a chronic focal skeletal disorder characterized by increased bone resorption by the osteoclasts. Paramyxoviral gene products have been detected in pagetic osteoclasts. Paget's disease is an autosomal dominant trait with genetic heterogeneity. Several mutations in the ubiquitin-associated (UBA) domain of sequestosome 1 (SQSTM1/p62) have been identified in patients with Paget's disease. Similarly, mutations in the valosin-containing protein (VCP) gene have been shown to cause inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia. In addition, gene polymorphisms and enhanced levels of cytokine/growth factors associated with Paget's disease have been identified. However, the etiologic factors in Paget's disease remain elusive. A cause and effect relationship for the paramyxoviral infection and SQSTM1/ p62 gene mutations responsible for pagetic osteoclast development and disease severity are unclear. This article will highlight the etiologic factors involved in the pathogenesis of Paget's disease.

An immunogenicity study of a newly introduced purified vero cell rabies vaccine (Abhayrab) manufactured in India

Purified Vero cell culture rabies vaccine "Abhayrab" manufactured by Human Biologicals Institute, Ooty, India was subjected for immunogenicity studies. Pre-exposure study was undertaken on 60 healthy volunteers (Group I) with vaccination on days 0, 7 and 21. A group of 75 patients of category II (Group II), 67 of category III (Group III) were given post-exposure prophylaxis and 88 patients of category III were administered with rabies immunoglobulins (Group IV) along with post-exposure prophylaxis as per World Health Organization (WHO) recommendations with a booster on day 90. The volunteers and patients vaccinated showed very few adverse side effects. The blood samples collected from volunteers (Group I) on days 14, 35 and 365 and patients (Group II-IV) on days 14, 30, 90 and 365 showed geometric mean titres (GMT) of >0.5 IU/ml. The study indicated new rabies vaccine manufactured in India was found to be safe and immunogenic.

Occurrence of Tobacco streak virus on Peanut (Arachis hypogaea) in India

A virus disease of peanut (groundnut, Arachis hypogaea L.), characterized by necrosis of the stem and terminal leaflets followed by death, caused severe crop losses in Andhra Pradesh, India during the rainy season of the year 2000. The disease was referred to as peanut stem necrosis disease (PSND). Cowpea (Vigna unguiculata, cv. C-152) and Phaseolus vulgaris (cv. Topcrop) were found to be suitable for propagating the virus. In laboratory inoculation tests, the virus was found to infect a large number of plants. In laboratory tests, the virus was transmitted by the thrips Frankliniella schultzei. Virus particles were purified by differential centrifugation and sucrose density gradient centrifugation from infected cowpea plants and were used to elicit the production of a rabbit polyclonal antiserum with high titer. Extracts of infected plants reacted with antiserum to Tobacco streak virus (TSV). Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins extracted from purified virus particles showed them to contain a major protein of 28 kDa and a minor, though prominent, protein of 57 kDa. Gel electrophoresis of RNA extracted from virus particles resolved it into four species with estimated sizes of 3.7, 3.1, 2.2, and 0.9 kb. Complementary DNA (cDNA) was made using as template a sample of the 2.2-kb RNA 3 and as primer an oligonucleotide complementary to sequence in RNA 3 of TSV. Following second strand synthesis, the cDNA was cloned in pBluescript and the nucleotide sequence was obtained for 868 nt of the cDNA. The sequence was 88.4% identical to the sequence in RNA 3 of TSV (strain WC). The results indicate that the causal agent of PSND is TSV. The same virus also was found to cause sunflower necrosis, an economically important disease in India. Studies on the epidemiology of PSND and the identification of virus-resistant peanut genotypes have been initiated to devise strategies to control PSND.

Osteoclast-stimulating factor interacts with the spinal muscular atrophy gene product to stimulate osteoclast formation

We have recently identified and cloned an intracellular peptide termed osteoclast-stimulating factor (OSF) that increases osteoclast (OCL) formation and bone resorption through a cellular signal transduction cascade, possibly through its interaction with c-Src or related family members. To further identify participants in the OSF signaling cascade, we used yeast two-hybrid screening with Saccharomyces cerevisiae, and we found that the 40-kDa spinal muscular atrophy disease-determining gene product, survival motor neuron (SMN), interacts with the OSF-Src homology 3 domain. Reverse transcription-polymerase chain reaction analysis of SMN mRNA expression in cells of the OCL lineage demonstrates that expression of the exon 7 splice variant of SMN is restricted to mature OCLs, whereas the unspliced transcript was expressed in OCL precursors as well as mature OCLs. Treatment of murine bone marrow cultures with conditioned media (5% (v/v)) from 293 cells transiently expressing the SMN cDNA significantly increased OCL formation, compared with treatment with conditioned media from mock-transfected cells. Furthermore, OCL-stimulatory activity by OSF or SMN was abolished by antisense constructs to SMN or OSF, respectively. These data confirm the participation of SMN in the OSF-enhanced expression of an OCL stimulator. OSF-SMN interaction may provide more insights into novel cellular signaling mechanisms that may play an important role in congenital bone fractures associated with type I spinal muscular atrophy disease.

Osteoclasts formed by measles virus-infected osteoclast precursors from hCD46 transgenic mice express characteristics of pagetic osteoclasts

Pagetic osteoclasts (OCLs) are abnormal in size and contain paramyxoviral-like nuclear inclusions that cross-react with antibodies to measles virus (MV). However, the role that MV infection plays in Paget's disease is unknown, because no animal model of Paget's disease is available. Therefore, we targeted a cellular MV receptor, human CD46 (hCD46), to cells in the OCL lineage in transgenic mice using the mouse tartrate-resistant acid phosphatase (TRAP) gene promoter. In vitro infection of OCL precursors from hCD46 transgenic mice with MV significantly increased OCL formation in bone marrow cultures. The numbers of TRAP-positive mononuclear cells and CFU-GM, the earliest identifiable OCL precursor, were also significantly increased. MV-infected OCLs formed from hCD46 marrow were increased in size, contained markedly increased numbers of nuclei, and had increased bone-resorbing capacity per OCL compared with OCLs formed from marrow of nontransgenic littermates. Furthermore, IL-6 and 24-hydroxylase messenger RNA expression levels were increased in MV-infected hCD46 transgenic mouse bone marrow cultures. Treatment of MV-infected hCD46 marrow cultures with a neutralizing antibody to IL-6 blocked the increased OCL formation seen in these cultures. These data demonstrate that MV infection of OCL precursors results in OCLs that have many features of pagetic OCLs, that the enhanced OCL formation is in part mediated by increased IL-6 expression induced by MV infection, and suggest that the hCD46 transgenic mouse may be a useful model for examining the effects of MV infection on OCL formation in vivo.

Aflatoxins B1 in different grades of chillies (Capsicum annum L.) in India as determined by indirect competitive-ELISA

Samples of the three grades of chilli pod (grades 1 to 3) were collected during surveys in 1998 and 1999 from the principal market yards and cold storage facilities of the major chilli-growing areas of Andhra Pradesh (AP), India. Chilli powders were collected from different supermarkets in Hyderabad, AP. They were analysed for aflatoxin B1 (AFB1) content by an indirect competitive ELISA. To avoid the influence of interfering substances present in chilli extracts, it was necessary to prepare the aflatoxin standards in methanol extracts of chillies free from aflatoxins. For nine representative samples there was good agreement between ELISA and HPLC estimations of AFB1 and the results suggested that the ELISA procedure adopted was dependable. Of the 182 chilli samples tested, 59% of the samples were contaminated with AFB1 and 18% contained the toxin at non-permissible levels. The highest AFB1 concentration of 969 microg/kg was found in one sample representing grade 3. Overall the maximum percentage of chilli pods showing AFB1 levels higher than 30 microg/kg (non-permissible levels) was in grade 3. Chilli pods stored in refrigerated rooms showed the lowest proportion of samples containing aflatoxin. Nearly 9% of the chilli powders sold in supermarkets contained non-permissible aflatoxin levels. This report highlights the importance of using grade 1 chilli pods to minimize aflatoxin contamination.

Paget's disease of bone: a disease of the osteoclast

Paget's disease is a chronic focal disease of the skeleton that affects up to 2-3% of the population over the age of 60 years. There is a genetic predisposition for Paget's disease, with one predisposition locus identified on chromosome 18q-21-22. Osteoclasts and osteoclast precursors from Paget's patients are abnormal and appear hyperresponsive to 1,25(OH)2D3 and RANK ligand and contain paramyxoviral transcripts (Fig. 1). The basis for the abnormalities detected in Paget's disease and the role that the paramyxoviruses may play in this disease are still unclear.

A new molecular role for iron in regulation of cell cycling and differentiation of HL-60 human leukemia cells: iron is required for transcription of p21(WAF1/CIP1) in cells induced by phorbol myristate acetate

To investigate the role of iron in hematopoiesis, we studied effects of iron deprivation on PMA-induced monocyte/macrophage differentiation in HL-60 cells. Iron deprivation induced by desferrioxamine (DF) blocked PMA-induced differentiation and induced S-phase arrest and apoptosis in up to 60% of cells. Apoptosis was not related to a decrease of bcl-2 or to c-myc overexpression. In the presence of DF, PMA-induced upregulation of the cyclin dependent kinase inhibitor (CDKI), p21(WAF1/CIP1), was blocked and its expression could be restored in the presence of DF by supplementation with ferric citrate. Furthermore, ferrioxamine (iron saturated DF) did not block induction of p21(WAF1/CIP1) indicating that the changes were not due to a nonspecific toxic effect of DF. Similarly, hydroxyurea, an inhibitor of ribonucleotide reductase, did not block p21 expression. p21(WAF1/CIP1) antisense oligonucleotides caused cell cycle alterations similar to DF and p21 overexpression overcame effects of iron deprivation on both cell cycling and differentiation. Therefore, p21 is a key target for the effects of iron deprivation on HL-60 cell cycling and differentiation. Nuclear run-on transcription assays and p21 mRNA half-life studies indicated that iron was required to support transcriptional activation of p21(WAF1/CIP1) after a PMA stimulus. By contrast, iron deprivation did not inhibit expression of a second CDKI, p27(KIP1). These data demonstrate a new role for iron during monocyte/macrophage differentiation. A key role of iron is to allow induction of p21(WAF1/CIP1) in response to a differentiation stimulus subsequently blocking cells at the G(1)/S cell cycle interface and preventing premature apoptosis. This effect of iron is independent of its requirement in supporting the activity of the enzyme, ribonucleotide reductase. Because of the central role of p21(WAF1/CIP1) as regulator of the G(1)/S cell cycle checkpoint this requirement for iron to support p21 expression represents an important mechanism by which iron may modulate hematopoietic cell growth and differentiation. Published 2001 Wiley-Liss, Inc.

Production of polyclonal antibodies against ochratoxin A and its detection in chilies by ELISA

Polyclonal antibodies were produced for Ochratoxin A (OA) by injecting OA-bovine serum albumin (BSA) conjugate subcutaneously at multiple sites into a New Zealand White inbred rabbit. Antiserum could be used at a dilution exceeding 1:100 000 in an indirect competitive enzyme-linked immunosorbent assay (ELISA), and detected OA concentrations up to 0.1 ng/mL. The 50% inhibition binding (I(50)) of OA was 5 ng/mL. Antibodies did not react with ochratoxin B, coumarin, 4-hydroxycoumarin, L-phenylalanine, and aflatoxin B1. OA contamination in chilies (Capsicum annum L.) collected from commercial markets and cold storage units was determined. The mean recoveries from OA-free chilies spiked with 1 to100 microg of OA per kg of chili sample were 90-110% with a standard deviation of <10%. Of 100 chili samples tested, 26 were found to contain over 10 microg/kg of OA. In 12 samples the OA concentration varied from 10 to 30 microg/kg, in 10 samples from 30 to 50 microg/kg, in 3 samples from 50 to100 microg/kg, and in one sample it was 120 microg/kg. This is the first record in India of OA in chilies, a major component of cooked foods in this country, and it is noteworthy that OA contamination exceeded the permissible limit for human consumption of less than 20 microg/kg in over 26% of the market samples tested.

Primary hypertrophic colonopathy

We report a 45-year-old man and a 60-year-old woman who presented with features of intermittent intestinal obstruction. Barium enema revealed narrowing at the pelvic-rectal junction in the man, and from the pelvic colon to the anal verge in the woman. Histology of the resected sections showed marked hypertrophy of the muscularis propria in both cases, with normal mucosa, submucosa and myenteric plexus. Both patients are asymptomatic at 4 years' and 2 years' follow up. This entity of primary hypertrophic colonopathy may be a variant of primary visceral myopathy.

Enhanced RANK ligand expression and responsivity of bone marrow cells in Paget's disease of bone

Paget's disease is characterized by highly localized areas of increased osteoclast (OCL) activity. This suggests that the microenvironment in pagetic lesions is highly osteoclastogenic, or that OCL precursors in these lesions are hyperresponsive to osteoclastogenic factors (or both). To examine these possibilities, we compared RANK ligand (RANKL) mRNA expression in a marrow stromal cell line developed from a pagetic lesion (PSV10) with that in a normal stromal cell line (Saka), and expression in marrow samples from affected bones of Paget's patients with that in normal marrow. RANKL mRNA was increased in PSV10 cells and pagetic marrow compared with Saka cells and normal marrow, and was also increased in marrow from affected bones compared with uninvolved bones from Paget's patients. Furthermore, pagetic marrow cells formed OCLs at much lower RANKL concentrations than did normal marrow. Anti-IL-6 decreased the RANKL responsivity of pagetic marrow to normal levels, whereas addition of IL-6 to normal marrow enhanced RANKL responsivity. Thus, RANKL expression and responsivity is increased in pagetic lesions, in part mediated by IL-6. These data suggest that the combination of enhanced expression of RANKL in affected bones and increased RANKL sensitivity of pagetic OCL precursors may contribute to the elevated numbers of OCLs in Paget's disease.

Osteoclasts expressing the measles virus nucleocapsid gene display a pagetic phenotype

Osteoclasts (OCLs) in Paget's disease are markedly increased in number and size, have increased numbers of nuclei per multinucleated cell, and demonstrate increased resorption capacity and increased sensitivity to 1,25-(OH)(2)D(3), the active form of vitamin D. These cells also contain nuclear inclusions, reminiscent of those seen in paramyxovirus-infected cells, which cross-react with antibodies to measles virus nucleocapsid (MVNP) antigen. To elucidate the role of MV in the abnormal OCL phenotype of Paget's disease, we transduced normal OCL precursors with retroviral vectors expressing MVNP and the MV matrix (MVM) genes. The transduced cells were then cultured with 1,25-(OH)(2)D(3) for14 or 21 days to induce formation of OCL-like multinucleated cells. The MVNP-transduced cells formed increased numbers of multinucleated cells, which contained many more nuclei and had increased resorption capacity compared with multinucleated cells derived from empty vector-transduced (EV-transduced) and MVM-transduced or normal bone marrow cells. Furthermore, MVNP-transduced cells showed increased sensitivity to 1, 25-(OH)(2)D(3), and formed OCLs at concentrations of 1, 25-(OH)(2)D(3) that were 1 log lower than that required for normal, EV-transduced, or MVM-transduced cells. These results demonstrate that expression of the MVNP gene in normal OCL precursors stimulates OCL formation and induces OCLs that express a phenotype similar to that of pagetic OCLs. These results support a potential pathophysiologic role for MV infection in the abnormal OCL activity and morphology that are characteristic of pagetic OCLs.

1,25-Dihydroxyvitamin D3 hypersensitivity of osteoclast precursors from patients with Paget's disease

Our previous studies suggested that increased osteoclast formation and activity in Paget's disease may be related in part to increased responsiveness of highly purified osteoclast precursors to 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]. However, the basis for this enhanced sensitivity to 1,25-(OH)2D3 is unclear. To address this question, we examined 24-hydroxylase and 1,25-(OH)2D3 receptor (VDR) messenger RNA (mRNA) expression during human osteoclast differentiation from normal subjects and patients with Paget's disease in response to 1,25-(OH)2D3 as well as VDR content and affinity. Reverse-transcription polymerase chain reaction (RT-PCR) analysis of granulocyte-macrophage colony-forming unit (GM-CFU), the earliest identifiable osteoclast precursor, derived from patients with Paget's disease demonstrated 24-hydroxylase mRNA expression in response to 1,25-(OH)2D3 was induced at concentrations of 1,25-(OH)2D3 that were at least one log less than that required for normal GM-CFU. VDR mRNA and VDR protein were detected in both immature and more differentiated osteoclast precursors, as well as in osteoclast-like multinucleated cells (MNCs). However, VDR expression was lower in MNCs than the mononuclear precursor cells. Osteoclast precursors and MNCs from patients with Paget's disease had levels of VDR expression similar to those of normal subjects but showed increased VDR affinity for 1,25-(OH)2D3. Because the effects of 1,25-(OH)2D3 are in part mediated by induction of expression of RANK ligand on marrow stromal cells, which in turn stimulates osteoclast formation, we examined expression of RANK ligand mRNA by marrow stromal cell lines derived from patients with Paget's disease and normal subjects in response to 1,25-(OH)2D3. RT-PCR analysis showed no difference in sensitivity of marrow stromal cells to 1,25-(OH)2D3 from normal subjects or patients with Paget's disease although the Paget's stromal cells expressed increased basal levels of RANK ligand mRNA. These results show that VDR protein is expressed in early and more differentiated osteoclast precursors, that expression levels of VDR decline with osteoclast differentiation, and that 1,25-(OH)2D3 has direct effects on osteoclast precursors. The enhanced sensitivity to 1,25-(OH)2D3 is an intrinsic property of osteoclast precursors from patients with Paget's disease that distinguishes them from normal osteoclast precursors. Furthermore, our results suggest that an increased affinity of VDR for 1,25-(OH)2D3 may be responsible for the enhanced 1,25-(OH)2D3 sensitivity of osteoclast precursors in patients with Paget's disease compared with normal subjects.

Production and characterization of monoclonal antibodies for aflatoxin B1

Hybridomas that secreted antibodies for aflatoxin B1 were selected using two immunization protocols referred to as A and B. Protocol A is a standard immunization method and resulted in the selection of only two clones that produced monoclonal antibodies against aflatoxin B1. In protocol B a unique immunization schedule which resulted in the generation of 10 hybridomas is described. Of the 10, one antibody was highly specific to B1, four antibodies reacted equally strongly with B1, G1 and weakly with B2. Another four reacted strongly with B1 and weakly with B2 and G1. One clone reacted equally strongly with B1, G1 and B2. Interestingly all the 10 antibodies showed little or no cross-reaction with G2.

Measles virus nucleocapsid transcript expression is not restricted to the osteoclast lineage in patients with Paget's disease of bone

Abundant evidence supports a viral etiology for Paget's disease of bone (PD), however, an infectious virus has not been isolated from PD patients. Thus, it is unclear how the virus is maintained for the many years that the disease persists in patients. We considered if a primitive multipotential hematopoietic stem cell (HSC), which is self-renewing, passes the virus to its differentiated progeny and serves as a reservoir for the pathogen. If a primitive stem cell harbored measles virus (MV), then other hematopoietic lineages derived from this stem cell in PD patients should also express MV transcripts. Therefore, because the human hematopoietic stem cell has not been clearly identified or isolated in large numbers, we isolated RNA from highly purified erythroid and multipotential hematopoietic progenitors that are the precursors for erythroid, granulocyte, megakaryocyte and macrophages (CFU-GEMM), and used RT-PCR to determine if MV nucleocapsid transcripts were present. MV transcripts were detected in PD patients in early erythroid (BFU-E) and more primitive multipotential myeloid progenitors (CFU-GEMM). Nonhematopoietic stromal cells from PD patients did not express MV transcripts. The expression of MV transcripts in erythroid progenitors was further confirmed by in situ hybridization using antisense riboprobes to MV nucleocapsid transcripts. Thus, our findings suggest that the pluripotent HSCs may be a potential reservoir for the virus. We propose that when HSCs, which contain MV, divide they produce a second HSC that serves as a reservoir for the virus and also transmit the virus to their more differentiated progeny in the erythroid and myeloid lineages. This mechanism would permit a defective virus to persist in HSCs of PD patients for many years, since HSCs are usually in G0 phase, and then be transmitted to more differentiated cells. This model further suggests that a mature complete virus that affects cell function could only act pathogenetically in the osteoclast lineage, which offers a permissive milieu.

Cell biology of Paget's disease

Paget's disease is characterized by markedly increased osteoclast formation and bone resorption followed by excessive new bone formation. Osteoclasts in Paget's disease are increased both in number and size, contain paramyxoviral-like nuclear inclusions, and can have up to 100 nuclei per cell. Marrow culture studies have identified several abnormalities in osteoclast formation in Paget's disease. Osteoclast-like multinucleated cells formed more rapidly in marrow cultures from patients with Paget's disease, produced increased levels of interleukin-6 (IL-6), and expressed high levels of IL-6 receptors compared to normals. IL-6 levels were also increased in bone marrow and peripheral blood of patients with Paget's disease. In addition, osteoclast precursors from patients with Paget's disease are hyperresponsive to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and calcitonin. The increased sensitivity of osteoclast precursors to 1,25(OH)2D3 is mediated through the vitamin D receptor (VDR), since 24-hydroxylase activity is also up-regulated at concentrations of 1,25(OH)2D3 that are one log less than that needed to induce 24-hydroxylase activity in osteoclast precursors from normals. However, VDR numbers and affinity for 1,25(OH)2D3 do not differ in osteoclast precursors from Paget's patients compared to those from normals. Synergistic interactions between cytokines such as IL-6 and 1,25(OH)2D3 also cannot explain the enhanced sensitivity of osteoclast precursors from patients with Paget's disease to 1,25(OH)2D3. Interestingly, coculture studies of osteoclast precursors and cells from the marrow microenvironment of patients with Paget's disease and normals have demonstrated that the marrow microenvironment is more osteoclastogenic than normal. Thus, studies of the cell biology of osteoclasts in Paget's disease have demonstrated an increased rate of osteoclast formation and abnormalities in both osteoclast precursors and the marrow microenvironment. Enhanced IL-6 production by osteoclasts in Paget's disease may further amplify the increased osteoclast formation already ongoing in the pagetic lesion, and may explain the increased bone turnover at uninvolved sites distant from the pagetic lesion.

Identification of human asparaginyl endopeptidase (legumain) as an inhibitor of osteoclast formation and bone resorption

We screened a human osteoclast (OCL) cDNA expression library for OCL inhibitory factors and identified a clone that blocked both human and murine OCL formation and bone resorption by more than 60%. This clone was identical to human legumain, a cysteine endopeptidase. Legumain significantly inhibited OCL-like multinucleated cell formation induced by 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) and parathyroid hormone-related protein (PTHrP) in mouse and human bone marrow cultures, and bone resorption in the fetal rat long bone assay in a dose-dependent manner. Legumain was detected in freshly isolated marrow plasma from normal donors and conditioned media from human marrow cultures. Furthermore, treatment of human marrow cultures with an antibody to legumain induced OCL formation to levels that were as high as those induced by 1,25-(OH)(2)D(3). Implantation in nude mice of 293 cells transfected with the legumain cDNA and constitutively expressing high levels of the protein significantly reduced hypercalcemia induced by PTHrP by about 50%, and significantly inhibited the increase in OCL surface and in OCL number expressed per mm(2) bone area and per mm bone surface induced by PTHrP. These results suggest that legumain may be a physiologic local regulator of OCL activity that can negatively modulate OCL formation and activity.

Intracellular fragmentation of bone resorption products by reactive oxygen species generated by osteoclastic tartrate-resistant acid phosphatase

Tartrate-resistant acid phosphatase (TRAP) is highly expressed in bone-resorbing osteoclasts and activated macrophages. It has been suggested that a redox-active iron in the binuclear iron center of TRAP could have the capacity to react with hydrogen peroxide to produce highly destructive reactive oxygen species (ROS). Here we show that TRAP can generate ROS in vitro and that cells over-expressing TRAP produce higher amounts of intracellular ROS than their parent cells. We further demonstrate that these ROS can be targeted to destroy collagen and other proteins. In resorbing osteoclasts, TRAP was found in transcytotic vesicles transporting matrix degradation products through the cell, suggesting that TRAP-facilitated fragmentation of endocytosed material takes place in a specific cellular compartment. These results suggest that bone matrix degradation occurs not only extracellularly in the resorption lacunae but also intracellularly in the transcytotic vesicles. We propose that proteins containing redox-active iron could represent a novel mechanism of physiological fragmentation of organic molecules. This mechanism could be important in tissue remodeling and as a defense mechanism of phagocytosing cells.

Characterization of immortalized osteoclast precursors developed from mice transgenic for both bcl-X(L) and simian virus 40 large T antigen

We recently developed an immortalized osteoclast (OCL) precursor cell line that forms large numbers of OCLs. This cell line was derived from mice doubly transgenic for bcl-X(L) and large T antigen that was targeted to cells in the OCL lineage (bcl-X(L)/Tag cells). We have now characterized these cells in terms of their surface and enzymatic phenotype, responsiveness to osteotropic factors, and differentiation potential. The bcl-X(L)/Tag cells expressed interleukin-1 receptors 1 and 2, gelatinase B (MMP9), as well as Mac-1, CD16/CD32 (Fcgamma receptors), CD45.2 (common leukocyte marker), CD86 (costimulatory molecule expressed on B cells, follicular dendritic cells, and thymic epithelium), major histocompatibility complex I, and nonspecific esterase when cocultured with MC3T3E1 cells. However, they did not express the antigens for F4/80 (mature macrophage/dendritic cell marker) by immunostaining. Treatment of bcl-X(L)/Tag cells, cocultured with MC3T3E 1 cells, with the combination of 1,25-dihydroxyvitamin D3 and dexamethasone induced high levels of OCL formation. The bcl-X(L)/Tag cells formed large numbers of OCLs when cultured with RANK ligand and macrophage colony-stimulating factor in the absence of feeder cells. In the absence of RANK ligand and a feeder cell layer, 100% of the cells differentiated into F4/80-positive cells. However, neither PTH nor PTH-related protein enhanced OCL formation by bcl-X(L)/Tag cells even when they were cocultured with primary osteoblasts, suggesting that they differ from primary mouse bone marrow cells in their responsiveness to PTH/PTH-related protein. Thus, bcl-X(L)/Tag cells have many of the properties of primary mouse OCL precursors and should be very useful for studies of OCL differentiation and divergence of OCL precursors from the macrophage lineage.

Annexin II increases osteoclast formation by stimulating the proliferation of osteoclast precursors in human marrow cultures

Annexin II (AXII), a calcium-dependent phospholipid-binding protein, has been recently found to be an osteoclast (OCL) stimulatory factor that is also secreted by OCLs. In vitro studies showed that AXII induced OCL formation and bone resorption. However, the mechanism of action by which AXII acts as a soluble extracellular protein to induce OCL formation is unknown. In this paper, we demonstrate that AXII gene expression is upregulated by 1,25-dihydroxyvitamin D3 [1, 25-(OH)2D3] and that addition of AXII significantly increased OCL-like multinucleated cell formation. Time-course studies suggested that AXII acted on the proliferative stage of OCL precursors and that AXII increased thymidine incorporation in OCL precursors. Moreover, AXII enhanced the growth of CFU-GM, the earliest identifiable OCL precursor, when bone marrow cultures were treated with low concentrations of GM-CSF. This capacity of AXII to induce OCL precursor proliferation was due to induction of GM-CSF expression, because the addition of neutralizing antibodies to GM-CSF blocked the stimulatory effect of AXII on OCL formation. RT-PCR analysis using RNA from highly purified subpopulations of marrow cells demonstrated that T cells, especially CD4(+) T cells, produced GM-CSF in response to AXII. Furthermore, FACS(R) analysis of T-cell subpopulations treated with fluorescein-labeled AXII suggested that the CD4(+), but not CD8(+), subpopulation of T cells express an AXII receptor. Taken together, these data suggest that AXII stimulates OCL formation by activating T cells through a putative receptor to secrete GM-CSF. GM-CSF then expands the OCL precursor pool to enhance OCL formation.

Cloning and identification of human Sca as a novel inhibitor of osteoclast formation and bone resorption

Increased osteoclast activity is responsible for the enhanced bone destruction in postmenopausal osteoporosis, Paget's disease, bone metastasis, and hypercalcemia of malignancy. However, the number of known inhibitory factors that block osteoclast formation and bone resorption are limited. Therefore, we used an expression-cloning approach to identify novel factors produced by osteoclasts that inhibit osteoclast activity. A candidate clone was identified and isolated from a human osteoclast-like multinucleated cell (MNC) cDNA library, named osteoclast inhibitory peptide-1 (OIP-1), and the cDNA sequence was determined. This sequence matched that of the recently identified human stem cell antigen, was structurally similar to the mouse Ly-6 gene family, and the sequence predicted it was a glycosyl phosphatidyl inositol (GPI)-anchored protein that had a cleavable COOH-terminal peptide. Western blot analysis of conditioned media from 293 cells transfected with the OIP-1 cDNA clone confirmed that OIP-1 was released into the media as a membrane-bound GPI-linked protein. Interestingly, both recombinant OIP-1 expressed in Escherichia coli (which does not have GPI linker) and OIP-1 expressed by mammalian cells significantly reduced osteoclast-like MNC formation induced by 1,25-dihydroxyvitamin D3 or PTH-related protein in mouse and human bone marrow cultures, and inhibited 45Ca release from prelabeled bone in fetal rat organ cultures. In contrast, recombinant OIP-1 did not inhibit the growth of a variety of other cell types. These data indicate that OIP-1 is a novel, specific inhibitor of osteoclast formation and bone resorption.

Control of osteoclast differentiation

The osteoclast is the primary bone-resorbing cell and is derived from the monocyte/macrophage lineage. Bipotent osteoclast precursors, which can form both osteoclasts and monocyte-macrophages, proliferate and differentiate to become unipotent post-mitotic committed osteoclast precursors. These post-mitotic committed precursors fuse to form the multinucleated osteoclast, which is then activated to resorb bone. A variety of soluble and membrane-bound factors play a critical role in regulating osteoclast formation, including growth factors, systemic hormones, and cells in the marrow microenvironment, such as osteoblasts and marrow stromal cells. Cell-to-cell interactions are important in both the formation and activity of the osteoclast. Recent molecular biological studies have identified transcription factors, such as c-fos and PU.1, which are required for osteoclast differentiation. In this review, we discuss the phenotypic changes that are induced as the cells mature from bipotent early precursors to mature osteoclasts; factors that have been identified that are involved in this process; and the role of marrow stromal cells and osteoblasts in osteoclast differentiation.

Immortalization of osteoclast precursors by targeting Bcl -XL and Simian virus 40 large T antigen to the osteoclast lineage in transgenic mice

Cellular and molecular characterization of osteoclasts (OCL) has been extremely difficult since OCL are rare cells, and are difficult to isolate in large numbers. We used the tartrate-resistant acid phosphatase promoter to target the bcl-XL and/or Simian Virus 40 large T antigen (Tag) genes to cells in the OCL lineage in transgenic mice as a means of immortalizing OCL precursors. Immunocytochemical studies confirmed that we had targeted Bcl-XL and/or Tag to OCL, and transformed and mitotic OCL were readily apparent in bones from both Tag and bcl-XL/Tag mice. OCL formation in primary bone marrow cultures from bcl-XL, Tag, or bcl-XL/Tag mice was twofold greater compared with that of nontransgenic littermates. Bone marrow cells from bcl-XL/Tag mice, but not from singly transgenic bcl-XL or Tag mice, have survived in continuous culture for more than a year. These cells form high numbers of bone-resorbing OCL when cultured using standard conditions for inducing OCL formation, with approximately 50% of the mononuclear cells incorporated into OCL. The OCL that form express calcitonin receptors and contract in response to calcitonin. Studies examining the proliferative capacity and the resistance of OCL precursors from these transgenic mice to apoptosis demonstrated that the increased numbers of OCL precursors in marrow from bcl-XL/Tag mice was due to their increased survival rather than an increased proliferative capacity compared with Tag, bcl-XL, or normal mice. Histomorphometric studies of bones from bcl-XL/Tag mice also confirmed that there were increased numbers of OCL precursors (TRAP + mononuclear cells) present in vivo. These data demonstrate that by targeting both bcl-XL and Tag to cells in the OCL lineage, we have immortalized OCL precursors that form bone-resorbing OCL with an efficiency that is 300-500 times greater than that of normal marrow.

Cadherin-6 mediates the heterotypic interactions between the hemopoietic osteoclast cell lineage and stromal cells in a murine model of osteoclast differentiation

Osteoclasts are multinucleated cells of hemopoietic origin that are responsible for bone resorption during physiological bone remodeling and in a variety of bone diseases. Osteoclast development requires direct heterotypic cell-cell interactions of the hemopoietic osteoclast precursors with the neighboring osteoblast/stromal cells. However, the molecular mechanisms underlying these heterotypic interactions are poorly understood. We isolated cadherin-6 isoform, denoted cadherin-6/2 from a cDNA library of human osteoclast-like cells. The isolated cadherin-6/2 is 3,423 bp in size consisting of an open reading frame of 2,115 bp, which encodes 705 amino acids. This isoform lacks 85 amino acids between positions 333 and 418 and contains 9 different amino acids in the extracellular domain compared with the previously described cadherin-6. The human osteoclast-like cells also expressed another isoform denoted cadherin-6/1 together with the cadherin-6. Introduction of cadherin-6/2 into L-cells that showed no cell-cell contact caused evident morphological changes accompanied with tight cell-cell association, indicating the cadherin-6/2 we isolated here is functional. Moreover, expression of dominant-negative or antisense cadherin-6/2 construct in bone marrow-derived mouse stromal ST2 cells, which express only cadherin-6/2, markedly impaired their ability to support osteoclast formation in a mouse coculture model of osteoclastogenesis. Our results suggest that cadherin-6 may be a contributory molecule to the heterotypic interactions between the hemopoietic osteoclast cell lineage and osteoblast/bone marrow stromal cells required for the osteoclast differentiation. Since both osteoclasts and osteoblasts/bone marrow stromal cells are the primary cells controlling physiological bone remodeling, expression of cadherin-6 isoforms in these two cell types of different origin suggests a critical role of these molecules in the relationship of osteoclast precursors and cells of osteoblastic lineage within the bone microenvironment.

IL-6 mediates the effects of IL-1 or TNF, but not PTHrP or 1,25(OH)2D3, on osteoclast-like cell formation in normal human bone marrow cultures

A potent interleukin-6 (IL-6) antagonist (Sant 5), which binds tightly to the IL-6alpha receptor but has impaired gp130 heterodimerization, has been developed recently by site-directed mutagenesis of human IL-6. We report here that Sant 5 inhibits IL-6-stimulated osteoclast-like multinucleated cell (MNC) formation in human marrow cultures but also inhibits the stimulatory effects of IL-1 or tumor necrosis factor alpha (TNF-alpha in these cultures. We further show that a neutralizing antibody to IL-6 also inhibits the stimulatory effects of IL-1 or TNF-alpha in these cultures. In contrast, Sant 5 had no effect on parathyroid hormone related protein (PTHrP) or 1,25-dihydroxyvitamin D3 stimulated MNC formation in human marrow cultures. Transfection of a human marrow stromal cell line, which normally induces osteoclast formation through production of IL-6, with the Sant 5 cDNA driven by a cytomegalovirus (CMV) promoter blocked the capacity of these cells to stimulate osteoclast-like cell formation. These Sant 5 transfected cells and conditioned media from these cells also inhibited the stimulatory effects of the parent cell line on MNC formation. These data suggest that IL-6 mediates the effects of IL-1 and TNF on human osteoclast formation, but in contrast to murine systems, does not mediate the effects of PTHrP. These data further demonstrate that stromal cells transfected with the Sant 5 cDNA can constitutively produce high levels of the IL-6 antagonist and inhibit osteoclast formation in vitro.

Analysis of DNA binding proteins associated with hemin-induced transcriptional inhibition. The hemin response element binding protein is a heterogeneous complex that includes the Ku protein

Hemin inhibits transcription of the tartrate resistant acid phosphatase (TRAP) gene. Using deletion mutagenesis of the mouse TRAP 5'-flanking region, we previously identified a 27-bp DNA segment containing a central GAGGC tandem repeat sequence (the hemin response element [HRE]), which bound nuclear proteins (hemin response element binding proteins [HREBPs]) from hemin-treated cells and appeared to be responsible for mediating transcriptional inhibition in response to hemin. We now have used affinity binding to HRE-derivatized beads to identify four HREBP components with apparent molecular masses of 133-, 90-, 80-, and 37-kD, respectively. The 80- and 90-kD components correspond to the p70 and p80/86 subunits of Ku antigen (KuAg) as documented by partial amino acid microsequencing of tryptic digests and immunologic reactivity. Based on reactivity of the HREBP gel shift band with antibodies to the redox factor protein (ref1) in shift Western experiments, it is shown that the 37-kD component represents ref1. The 133-kD component appeared to be a unique protein. KuAg participation in HREBP complexes was specific as it was present in HREBPs bound to HRE microcircles. Results of depletion/reconstitution experiments suggested that KuAg does not bind alone or directly to HRE DNA, but does so only in conjunction with the 133- and/or 37-kD proteins. We conclude that HREBP is a heterogeneous complex composed of KuAg, ref1, and a unique 133-kD protein. We speculate that the role of heme may be to promote interactions among these components, thereby facilitating HRE binding and downregulation of hemin responsive genes.

Further characterization of the murine collagenase (type IVB) gene promoter and analysis of mRNA expression in murine tissues

The collagenase B type IV (Col4B) gene is highly expressed in the osteoclast, the primary bone-resorbing cell. However, factors that regulate expression of the Col4B gene are not well characterized. A murine P1 genomic clone containing a 94 kb sequence insert which contains the Col4B gene was isolated. A 4 kb EcoR1 DNA fragment containing the 5' flanking sequence of the gene was further subcloned and restriction mapped. Putative transcription factors such as SRY, Lyf-1, and GATA1 and 2, binding motifs were identified by sequence analysis in this promoter region. Enhancer and suppressor regions were mapped by transient expression of Col4B gene promoter deletion mutant-luciferase reporter gene constructs in HepG2 cells. Col4B mRNA expression in different murine tissues was analyzed by reverse transcription-polymerase chain reaction and demonstrated high levels of expression in bone, clavaria, spleen and thymus. This promoter provides a valuable tool for targeting gene expression to the osteoclast.

Smoking and the human vertebral column: a review of the impact of cigarette use on vertebral bone metabolism and spinal fusion

Chronic cigarette consumption has significant adverse effects on the human spinal column. Multiple mechanisms induced by tobacco use lead to less strong, less healthy, mineral-deficient vertebrae with reduced bone blood supply and fewer and less functional bone-forming cells among chronic smokers. Compared to nonsmokers, chronic smokers develop advanced bony degradation, are more likely to suffer from spinal column degenerative disease, and seem more susceptible to traumatic vertebral injury. Spinal fusion procedures in chronic smokers are less often clinically and radiographically successful, compared to similar procedures performed among nonsmokers for definitive biological, physiological, and mechanical reasons.

Detection of measles virus nucleocapsid transcripts in circulating blood cells from patients with Paget disease

Paget disease of bone is characterized by abnormalities in all phases of bone remodeling, but the fundamental cellular abnormality resides in the osteoclast (OCL). Osteoclasts in bone involved by Paget disease contain viral-like nuclear and cytoplasmic inclusions that react with antibodies directed against paramyxovirus nucleocapsid proteins, such as measles virus, respiratory syncytial virus, or canine distemper virus. However, the identity of the virus or the mechanisms responsible for its persistence or pathologic role in Paget disease is unclear. Furthermore, although Paget disease persists for many years, it remains a highly localized process with new lesions rarely if ever developing in previously unaffected bones. Since osteoclasts are formed by fusion of mononuclear precursors derived from colony forming unit-granulocyte macrophage (CFU-GM), the granulocyte-macrophage progenitor, we used reverse transcriptase polymerase chain reaction (RT-PCR) analysis to determine if CFU-GM, more differentiated osteoclast precursors, and peripheral blood cells derived from CFU-GM express measles virus nucleocapsid (MV-N) transcripts. We found that osteoclast precursors, as well as peripheral blood mononuclear cells, express MV transcripts in 9 of 13 patients. Sequence analysis of the PCR amplified products confirmed nucleotide identity of MV-N transcripts expressed in peripheral blood and bone marrow-derived cells from the same patient. In contrast, MV-N transcripts were not detected in OCL precursors or the peripheral blood from 10 normal subjects. In situ hybridization studies using 35S-labeled antisense riboprobes to MV-N transcripts further confirmed the expression of MV transcripts in these cells. Sequence analysis of the PCR amplified product from one of these patients also identified a novel mutation that converted lysine441 to glutamic acid441 in the MV-N transcript. These data demonstrate that OCL precursors and circulating peripheral blood cells also express MV transcripts in patients with Paget disease and suggest that the pagetic marrow microenvironment plays a critical role in maintaining the highly localized nature of the lesions in Paget disease.

Inhibition of tartrate-resistant acid phosphatase gene expression by hemin and protoporphyrin IX. Identification of a hemin-responsive inhibitor of transcription

Tartrate-resistant acid phosphatase (TRAP) is an iron-containing protein encoded by the same gene that codes for uteroferrin, a placental iron transport protein. In human peripheral mononuclear cells, TRAP expression is inhibited by both hemin (ferric protoporphyrin IX) and protoporphyrin IX. Nuclear run-on assays confirmed that this inhibition occurs at the level of gene transcription. Previous studies with mTRAP deletion mutants showed that the hemin effect was dependent on repressor activity in the mTRAP 5'-flanking region at -1846 bp to -1240 bp relative to ATG (Reddy et al, J Bone Mineral Res 10:601, 1995). We now report that gel shift assays showed a DNA binding protein in nuclear extracts of hemin-treated cells termed hemin response element binding protein (HREBP). Additional studies have localized the HREBP binding region in the mTRAP 5'-flanking DNA to a 27-bp sequence at -1815 to -1789 bp relative to ATG. A tandem repeat sequence, GAGGC;GAGGC, contained within this DNA segment, was shown to be involved in binding of HREBP. Highly homologous sequences are present in the 5'-flanking region of the hTRAP gene. Binding of HREBP to the mTRAP DNA sequence was inhibited by anti-HAP1 antibodies, indicating homology between the hemin-responsive factor and the yeast heme-dependent transcription factor, HAP1. A 607-bp segment of the mTRAP 5'-flanking region containing the candidate hemin response element and surrounding sequences conferred hemin regulation on the viral SV40 promoter. Southwestern blotting experiments probing nuclear extracts of hemin-treated U937 cells with the 27-bp binding sequence showed two protein bands at 37 and 133 kD representing candidate HREBPs. A GENINFO search showed several other mammalian genes with tandem GAGGC motifs in noncoding regions, providing the possibility that additional genes may also be regulated by hemin at the level of transcription. These studies provide the first description of a novel iron/hemin-responsive transcriptional regulatory mechanism in mammalian cells.

Water escape performance of adult RCS dystrophic and congenic rats: a functional and histomorphometric study

The dystrophic Royal College of Surgeons (RCS) rat undergoes photoreceptor degeneration due to a hereditary defect in the retinal pigment epithelium. The congenic rat remains unaffected. Although the retinal degeneration is well characterized, few functional studies of this strain are available. We wished to compare the visual function of congenic and dystrophic RCS rats using a water escape paradigm that tested their ability to find a submersed, randomly placed platform using a light source as a clue. Three different behavioral experiments were sequentially performed on all animals: Experiment 1--The Light and Platform test measured the time to swim from the center of the pool to a platform located under a light clue. Each animal was given 10 trials. Experiment 2--The No Light with Platform test was performed as above except no light clue was used. Experiment 3--The Light and No Platform test was performed with a light clue but without a platform. The animal was allowed to swim for 2 min. All trials were videotaped. After the final experiment, the animals were sacrificed and a histomorphometric analysis of their retinas were performed. Expt. 1--The time to find the platform using light as a clue was greater for the dystrophic than for the congenic rats. Expt. 2--In the absence of light clue, there was no significant difference in performance between the congenic and dystrophic animals. Expt. 3--In the absence of a platform, a significantly greater amount of time was spent in the area indicated by the light clue by the congenic animals as compared to the dystrophic. Morphometric analysis revealed a mean number of 133 photoreceptor nuclear profiles/90 microns of retina for congenic rats as compared to 0.14 for dystrophic rats. This simplified version of the Morris water maze permits quantitative evaluation of visually-guided behavior in an important model of retinal degeneration.

Targeting simian virus 40 T antigen to the osteoclast in transgenic mice causes osteoclast tumors and transformation and apoptosis of osteoclasts

Osteoclasts are terminally differentiated cells that express tartrate-resistant acid phosphatase (TRAP) at a higher level than other normal cells. Therefore, in an attempt to develop immortalized osteoclasts, we produced two lines of transgenic mice in which expression of the simian virus 40 T antigen oncogene was targeted to osteoclasts using the TRAP gene promoter. Osteoclasts were increased in number in bones from both lines. More than 50% of them appeared morphologically transformed, 2-5% were mitotic, but, unexpectedly, 5% were apoptotic. Osteoclast tumors were observed occasionally in one line of mice (line 4), and sheets of TRAP-positive cells (tumorlets) developed in most mice in both lines. Although cells isolated from these tumorlets formed multinucleated TRAP-positive cells that resorbed bone in vitro, to date we have been unable to develop an immortalized osteoclast cell line from them. Osteoclasts from one line (line 5) had reduced ruffled border formation and a higher level of T-antigen expression than osteoclasts in the other line (line 4), and these features were associated with the presence of osteopetrosis. However, osteoclasts from these osteopetrotic mice and from line 4 mice resorbed bone normally when the mice were treated with interleukin-1. These findings indicate that T antigen can be targeted to osteoclasts in transgenic mice and causes osteoclast transformation, tumors, mitosis, and apoptosis. When T antigen is expressed at high levels, functional impairment of osteoclasts can be detected. Furthermore, these results suggest that T antigen is insufficient on its own to immortalize cells in the osteoclast lineage.

Characterization of the osteoclast vacuolar H(+)-ATPase B-subunit

During bone resorption, osteoclasts acidify the extracellular bone resorbing compartment via a vacuolar H(+)-ATPase (V-ATPase), which resides in the ruffled-border membrane. In an effort to characterize the composition of the osteoclast V-ATPase catalytic domain, we have isolated a cDNA clone that encodes the V-ATPase B-subunit from a cDNA library constructed from highly purified chicken osteoclasts. Comparison of the predicted amino-acid sequence with the published sequences of isoforms of V-ATPase B-subunits from other sources revealed that the chicken osteoclast B-subunit is brain type and not kidney type. Furthermore, only clones encoding the brain type isoform of subunit B could be generated by PCR from a cDNA library prepared from human osteoclastoma osteoclast-like cells. Northern blot analysis revealed that two B-subunit mRNAs, approx. 1.7 and 3.5 kb in length, are expressed in chicken bone marrow mono-nuclear cells, brain and kidney, although the relative amounts of these two transcripts were different in each tissue. In brain, the 3.5-kb mRNA was predominantly expressed. In bone marrow cells, the levels of the 1.7-kb mRNA were higher than in other tissues and expression of this message was increased by 1,25-dihydroxyvitamin D-3, suggesting that this mRNA is specifically upregulated during osteoclast differentiation.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone marrow mononuclear cells from patients with Paget's disease contain measles virus nucleocapsid messenger ribonucleic acid that has mutations in a specific region of the sequence

Ultrastructural, immunocytochemical, and in situ hybridization studies have suggested that paramyxoviruses, such as measles virus (MV), are present in Pagetic osteoclasts and may contribute to the abnormality in osteoclast function. However, little additional information is known about potential viruses present in Pagetic osteoclasts. As there are increased numbers of osteoclast precursors among the marrow mononuclear cells of Paget's patients, we used the reverse transcriptase-polymerase chain reaction to amplify the nucleocapsid sequence of MV from freshly isolated bone marrow-derived mononuclear cells to examine the potential role of these viruses in cells in the osteoclast lineage. We detected MV nucleocapsid transcripts in 5 of 6 individual Paget's patients' marrow samples. MV transcripts were not detected in marrow samples from 10 normal subjects. Sequence analysis of the PCR products revealed that 1 patient had the same sequence as the Edmonston strain of MV. The remaining 4 patients had point mutations clustered between position 1360-1371 base pairs. Two of the patients exhibited identical mutations at this region. In total, 3 different point mutations were identified that resulted in amino acid substitutions. These data show that 1) unlike those from normal subjects, marrow mononuclear cells from Paget's patients express MV nucleocapsid messenger ribonucleic acid; and 2) mutations of a specific region of the MV nucleocapsid gene were present in 4 of 5 patients and suggest a persistent MV infection in Pagetic osteoclast precursors. These data further suggest that osteoclasts are infected by fusion with infected precursors.

Characterization of the 5'-flanking region of the human tartrate-resistant acid phosphatase (TRAP) gene

Tartrate-resistant acid phosphatase (TRAP) is expressed at high levels in osteoclasts and may play an important role in the bone resorptive process. However, factors regulating human TRAP gene expression have not been clearly defined. Therefore, we isolated a genomic clone (CL-9) for TRAP containing a 14-kb insert. A restriction map was generated for this insert, and a 2.6-kb ApaI fragment containing the 5'-flanking region was subcloned. Sequence analysis of this fragment revealed the presence of candidate transcription factor-binding sequences for H-APF-1, SP1, GATA2, and the c-Myc proto-oncogene. PCR analysis of RNA isolated from human osteoclastomas and pagetic bone revealed a 276-bp intron at -1 bp to -276 bp relative to the ATG and a transcript originating from this intron. Rapid amplification of the 5' end of the human TRAP mRNA by PCR indicated the presence of a 93-bp untranslated region 5' from the intron. Promoter activity was detected in the DNA fragment from +1 bp to -1903 bp relative to the ATG initiation codon, which drove the transient expression of a luciferase reporter gene when transfected into HRE H9 rabbit endometrial cells. Comparison of the human TRAP 5'-flanking region with mouse TRAP and uteroferrin revealed 41% and 47% homology, respectively. This suggests that regulation of human TRAP gene expression may differ from that for the murine TRAP gene.

Development and characterization of a human marrow stromal cell line that enhances osteoclast-like cell formation

We established a human bone marrow stromal cell line (Saka) by infecting marrow adherent cells from semisolid marrow cultures with a recombinant simian virus-40 (SV40) virus. The cells expressed SV40 large tumor antigen, had a fibroblast-like shape, and expressed fibronectin and vimentin. They did not contain detectable alkaline phosphatase activity; express myeloid, lymphoid, or factor VIII-associated antigens; or develop adipocyte-like characteristics with dexamethasone treatment. Polymerase chain reaction analysis of Saka cell RNA detected expression of messenger RNAs for interleukin-6 (IL-6), IL-1 beta, granulocyte-macrophage colony-stimulating factor, macrophage colony-stimulating factor, stem cell factor, and the 1,25-dihydroxyvitamin D3 receptor. Coculture of Saka cells with human marrow mononuclear cells enhanced formation of osteoclast-like multinucleated cells (MNC) in long term human bone marrow cultures. These MNC expressed calcitonin receptors and formed resorption lacunae on dentine. In contrast, coculture of marrow mononuclear cells with other SV40-transformed human marrow stromal cell lines did not increase MNC formation. Conditioned medium from Saka cells or coculture of bone marrow and Saka cells separated by a Millipore membrane did not enhance MNC formation. Addition of a neutralizing antibody to IL-6 or IL-1 beta blocked the effects of Saka cells on MNC formation. These results suggest that marrow stromal cells enhance osteoclast formation in part through direct cell to cell contact and production of IL-6 and/or IL-1 beta.

Characterization of the mouse tartrate-resistant acid phosphatase (TRAP) gene promoter

Tartrate-resistant acid phosphatase (TRAP) is an iron-binding protein that is highly expressed in osteoclasts. To characterize the regulation of TRAP gene expression, progressive 5' and 3' deletions of a 1.8 kb fragment containing the 5'-flanking sequence were fused to a luciferase reporter gene. Two nonoverlapping regions of this 1.8 kb fragment had promoter activity. The upstream promoter (P1) was located within the region from -881 bp to -463 bp relative to the ATG, while the downstream promoter (P2) was located between -363 bp to -1 bp in a region we have previously shown to be an intron in transcripts originating from the upstream promoter. A putative repressor region for the P2 promoter at -1846 bp to -1240 bp and a putative enhancer region at -962 bp to -881 bp relative to the ATG were identified. PCR analysis of promoter-specific transcription of the TRAP gene in various murine tissues showed that both promoters were active in several tissues. Transferrin-bound iron increased P1 promoter activity 2.5-fold and hemin decreased P1 promoter activity, but neither had any effect on P2 activity. These data show that the transcriptional regulation of the TRAP gene is complex and that iron may play a key role in TRAP gene regulation.

Cloning and identification of annexin II as an autocrine/paracrine factor that increases osteoclast formation and bone resorption

Autocrine products of osteoclasts such as interleukin-6 may play an important role in normal osteoclast formation and activity. To identify novel stimulatory factors for osteoclasts, we have prepared a mammalian cDNA expression library generated from highly purified human osteoclast-like multinucleated cells (MNC) formed in long term bone marrow cultures and screened this library for autocrine factors that enhance MNC formation. A candidate clone which stimulated MNC formation was isolated. Sequence analysis showed that this cDNA encoded annexin II (AXII). Purified recombinant AXII significantly increased MNC formation in human bone marrow cultures in the absence of 1,25-(OH)2 vitamin D3 and enhanced MNC formation in mouse bone marrow cultures treated with 10(-9) M 1,25-(OH)2 vitamin D3. The enhanced MNC formation in murine marrow cultures resulted in increased bone resorption. Treatment of fetal rat long bones with AXII and 1,25-(OH)2 vitamin D3 significantly increased bone resorption compared to 1,25-(OH)2 vitamin D3 alone. Reverse transcriptase polymerase chain reaction analysis demonstrated that AXII mRNA was expressed at high levels in RNA isolated from highly purified giant cells from osteoclastomas, human osteoclast-like MNC, and pagetic bone. Western blot analysis of conditioned media collected from human marrow cultures showed that AXII was present in the media. Furthermore, approximately 50% of total AXII produced by cells transfected with AXII cDNA was present in the conditioned media. These data suggest that the AXII is an autocrine factor that enhances osteoclast formation and bone resorption and demonstrate a previous unknown function for AXII.

Interleukin-6 antisense deoxyoligonucleotides inhibit bone resorption by giant cells from human giant cell tumors of bone

The effects of antisense constructs to IL-6 on the bone-resorbing capacity of purified giant cells from giant cell tumors of bone were examined to further define the role of IL-6 in human osteoclastic bone resorption. In addition, we wanted to determine the utility of antisense constructs to cytokines produced by osteoclasts as probes to identify the molecular events responsible for the bone-resorptive process. Giant cells were cultured on sperm whale dentin for 24 h in the presence of fluoresceinated antisense or scrambled antisense deoxyoligonucleotides complementary to IL-6 mRNA. The giant cells actively incorporated these oligonucleotides, as evidenced by their intense fluorescence. The number of resorptive lacunae formed and the area of the dentin resorbed were significantly decreased in cultures of giant cells treated with antisense IL-6 constructs compared with control cultures treated with scrambled antisense constructs to IL-6 (60 +/- 13 versus 12 +/- 6 lacunae and 1.2 +/- 0.3 versus 0.26 +/- 0.1 x 10(5) microns2). IL-6 levels in conditioned media from giant cell cultures treated with IL-6 antisense constructs were fourfold lower than those in control media obtained from giant cells treated with scrambled antisense constructs to IL-6. These data confirm the capacity of IL-6 antisense oligomers to block IL-6 production by these cells. These observations show that IL-6 plays an important role in the bone-resorptive process of human osteoclasts and suggest that antisense constructs to cytokines produced by bone cells may be useful for determining the molecular events occurring during bone resorption.

Transcriptional regulation of the tartrate-resistant acid phosphatase (TRAP) gene by iron

Tartrate-resistant acid phosphatase (TRAP) was first identified in cells from patients with hairy cell leukaemia. Subsequently, it has been found in other leukaemias, B-lymphoblastoid cell lines, osteoclasts and subsets of normal lymphocytes, macrophages, and granulocytes. Recent data indicate that TRAP and porcine uteroferrin, a placental iron-transport protein, represent a single gene product. However, the intracellular role of TRAP is unknown. We used a full-length human placental TRAP cDNA probe to examine TRAP expression in human peripheral mononuclear cells (PMCs). TRAP mRNA increased 50-75-fold after 24 h in unstimulated PMC cultures. Cell-fractionation experiments indicated that monocytes were the main cell population accounting for increased TRAP mRNA transcripts, and this was confirmed by histochemical staining for TRAP enzyme activity. Because expression of other iron-binding and -transport proteins is controlled by iron availability, we examined the role of iron in regulating TRAP expression. Increase of TRAP mRNA transcripts in PMCs was inhibited by 50 microM desferrioxamine, a potent iron chelator. The 5' flanking region of the TRAP gene was cloned from a mouse genomic library. In preliminary transient transfection experiments, it was determined that the 5'-flanking region of the TRAP gene contained iron-responsive elements. Therefore, a series of stably transfected HRE H9 cell lines was developed bearing genetic constructs containing various segments of the murine TRAP 5' promoter region driving a luciferase reporter gene. Treatment of transfectants with 100 micrograms/ml iron-saturated human transferrin (FeTF) was performed to assess iron responsiveness of the constructs. Constructs containing a full-length TRAP promoter (comprising base pairs -1846 to +2) responded to FeTF with a 4-5-fold increase of luciferase activity whereas constructs containing only base pairs -363 to +2 of the TRAP promoter did not respond. Constructs containing 1240 or 881 bp of the TRAP promoter gave only a 1.5- to 2-fold increase of luciferase activity with FeTF. In all cases, increase of luciferase activity was blocked by desferrioxamine. Cells transfected with another luciferase construct driven by a simian virus 40 promoter did not show any increase of luciferase activity with FeTF. These data indicate that expression of TRAP is regulated by iron and that this regulation is exerted at the level of gene transcription. The transfection experiments also suggest that the region of the TRAP 5'-flanking sequence between base pairs -1846 and -1240 contains an iron regulatory element.