A field study on malaria prevalence in southeastern Laos by polymerase chain reaction assay

A detection survey for malaria infection by routine microscopy and polymerase chain reaction (PCR) assay was conducted on 336 inhabitants of two villages in Khammouane Province, Lao People's Democratic Republic (Lao PDR), in July 1997. Malaria infection was demonstrated in 58 (17.3%) subjects by microscopy and in 117 (34.8%) by PCR assay. Specimens positive by both methods were frequent in young villagers, suggesting the presence of many subclinical infections in older persons. The most common species of malaria parasite was Plasmodium falciparum (82.9%). Polymerase chain reaction assay detected mixed infections with 2-4 species in 27 specimens (23.1%). The results demonstrate that there are many subclinical malaria infections with low parasite level and infection with all four human malaria species in Lao PDR.

Role of granuloma in the immunopathogenesis of Crohn's disease

Inflammatory bowel diseases (ulcerative colitis and Crohn's disease) are chronic long-lasting inflammatory diseases with yet unknown etiology. Recent advancement revealed that both diseases are associated with genetic predisposition and environmental factors such as luminal microorganisms and antigens. Crohn's disease is associated with histopathologic features such as granuloma formation and longitudinal ulceration. In this article we describe the role of granuloma in the immunopathogenesis of Crohn's disease. Granuloma of Crohn's disease may play crucial roles as antigen-presenting cites to memory type T cells, which leads to activation and proliferation of T cells. Antigens presented at granuloma may be closely related to the disease.

NaCl-activated nucleoside diphosphate kinase from extremely halophilic archaeon, Halobacterium salinarum, maintains native conformation without salt

Enzymes from extremely halophilic archaea are readily denatured in the absence of a high salt concentration. However, we have observed here that a nucleoside diphosphate kinase prepared from Halobacterium salinarum was active and stable in the absence of salt, though it has the amino acid composition characteristic of halophilic enzymes. Recombinant nucleoside diphosphate kinase expressed in Escherichia coli requires salt for activation in vitro, but once it acquires the proper folding, it no longer requires the presence of salts for its activity and stability.

Fluid shear stress-induced cyclooxygenase-2 expression is mediated by C/EBP beta, cAMP-response element-binding protein, and AP-1 in osteoblastic MC3T3-E1 cells

Mechanical loading is crucial for maintenance of bone integrity and architecture, and prostaglandins are an important mediator of mechanosensing. Cyclooxygenase-2 (COX-2), an inducible isoform of prostaglandin G/H synthase, is induced by mechanical loading-derived fluid shear stress in bone-forming cells such as osteoblasts and osteocytes. In this study, we investigated transcription factor and transcriptional regulatory elements responsible for the shear stress-induced COX-2 expression in osteoblastic MC3T3-E1 cells. When the cells were transfected with luciferase-reporter plasmids including the 5'-flanking region of the murine cox-2 gene, the fluid shear stress increased the luciferase activities, consistent with the induction of COX-2 mRNA and protein expression. Deletion analysis of the promoter region revealed that the shear stress-induced luciferase responses were regulated by two regions, -172 to -100 base pair (bp) and -79 to -46 bp, of the cox-2 promoter, in which putative cis-elements of C/EBP beta, AP-1, cAMP-response element-binding protein (CREB), and E box are included. Mutation of sites of C/EBP beta, AP-1, and/or cAMP-response element decreased the shear stress-induced luciferase activities, whereas mutation of the E box did not affect the responses. In an electrophoretic mobility shift assay, shear stress enhanced nuclear extract binding to double-stranded oligonucleotide probes containing C/EBP beta and AP-1-binding motifs, and the bands of the complexes were supershifted by the addition of antibody specific for each regulator. Although the binding activity of CREB toward its probe was unaffected by shear stress, the phosphorylation of CREB was enhanced by the stress. These data suggest that C/EBP beta, AP-1, and CREB play crucial roles in the shear stress-induced cox-2 expression in osteoblasts.

[Mechanism and management of drug-induced eating disorder]

Eating disorders induced by drugs, especially anorexia, nausea and vomiting are frequently reported as side effects of many available drugs. Since such disorders can affect patients' quality of life, suitable treatment plans based on the mechanisms of their induction are warranted. Eating disorders induced by drugs can be classified according to the mechanism of their induction into disorders resulting from: 1) gastrointestinal mucosal injury; nonsteroidal antiinflammatory drugs, antibiotics, etc. 2) chemical stimulation of the central nervous system; anticancer drugs, morphine, digitalis, etc. 3) non-specific symptoms following other systemic side effects; drug-induced depression, liver derangement, etc. This review addresses the aforementioned points and the best countermeasures that should be tried for successful control of these disorders.

Differential expression of human beta-defensin 2 in keratinized and non-keratinized oral epithelial lesions; immunohistochemistry and in situ hybridization

Human beta-defensin(hBD)-2, an antimicrobial peptide, is produced by various epithelial cells. Because hBD-2 expression in the oral epithelium has not been assessed, we investigated its localization in normal oral epithelium and epithelial lesions. hBD-2 expression was studied using immunohistochemistry and in situ hybridization on formalin-fixed, paraffin-embedded tissue sections from 30 cases of squamous cell carcinoma and 6 cases of leukoplakia. Immunostaining for hBD-2 was more intense in hyperkeratinized than in ortho- or non-keratinized epithelium. In contrast, signals for hBD-2 mRNA were frequently stronger in non-keratinized epithelium than in hyper- or ortho-keratinized epithelium. The results suggest that keratinization in oral epithelium plays an important role in the biological function of hBD-2 both at the mRNA level and in the retention of the peptide in the epithelium.

IgG subclasses of anti Saccharomyces cerevisiae antibody in inflammatory bowel disease

Elevation of serum anti Saccharomyces cerevisiae antibody (ASCA) has been reported in patients with Crohn's disease. We analysed the subclasses of Immunoglobulin (Ig) G reaction in ASCA in sera from patients with inflammatory bowel disease, healthy controls, and patients with intestinal Behçet's disease. Serum samples were obtained from 29 patients with Crohn's disease, 30 patients with ulcerative colitis, 7 patients with intestinal Behçet's disease, and 12 healthy controls. Serum IgG subclasses IgG1, IgG2, IgG3, and IgG4 of ASCA were analysed using ELISA. IgG4 ASCA was significantly increased in patients with inflammatory bowel disease. In patients with intestinal Behçet's disease, IgG1, IgG3, and IgG4 ASCA were increased. Differential responses, in terms of subclasses in ASCA, were found in patients with inflammatory bowel disease and patients with intestinal Behçet's disease, which may represent different pathophysiologies of these intestinal inflammatory diseases.

Factors affecting short-term and long-term stabilities of proteins

Proteins are marginally stable and, hence, are readily denatured by various stresses encountered in solution, or in the frozen or dried states. Various additives are known to minimize damage and enhance the stability of proteins. This review discusses the current knowledge of the mechanisms by which these additives stabilize proteins against acute stresses, and also the various factors to be considered for long-term storage of proteins in solution.

Expression, purification, and characterization of the active immunoglobulin-like domain of human granulocyte-colony-stimulating factor receptor in Escherichia coli

We succeeded in the expression, purification, and refolding of the immunoglobulin-like (Ig) domain of human granulocyte-colony-stimulating factor (G-CSF) receptor with amino-terminal His-tag in Escherichia coli. The refolded Ig domain bound to a G-CSF affinity column and could be eluted with free G-CSF as a receptor-ligand complex, demonstrating that the Ig domain has the information necessary for binding its ligand, G-CSF. The eluted His-Ig/G-CSF complex could be separated from excess G-CSF by Ni-NTA column chromatography. The yield of this active recombinant His-Ig protein is about 0.72 mg per liter of culture. Its small size and the ease of production make this receptor fragment a useful reagent for the structural analysis of its complex with G-CSF.

Functional annotation of a full-length mouse cDNA collection

The RIKEN Mouse Gene Encyclopaedia Project, a systematic approach to determining the full coding potential of the mouse genome, involves collection and sequencing of full-length complementary DNAs and physical mapping of the corresponding genes to the mouse genome. We organized an international functional annotation meeting (FANTOM) to annotate the first 21,076 cDNAs to be analysed in this project. Here we describe the first RIKEN clone collection, which is one of the largest described for any organism. Analysis of these cDNAs extends known gene families and identifies new ones.

Asn to Lys mutations at three sites which are N-glycosylated in the mammalian protein decrease the aggregation of Escherichia coli-derived erythropoietin

Erythropoietin (EPO) derived from Escherichia coli is unstable to elevated temperature and tends to aggregate with time, making it unsuitable for high-resolution structure analysis. The mammalian EPO contains about 40% carbohydrate, which makes this protein more stable and less prone to aggregate than non-glycosylated E.coli-derived EPO, but makes it unsuitable for high-resolution analysis owing to its size and flexibility. In an attempt to decrease the aggregation of E.coli-derived EPO, the three asparagine residues at positions 24, 38 and 83 were mutated to lysine residues. In the native protein, these residues are the sites of N-linked glycosylation, which suggests that they should be located on the surface of the protein and should not be involved in interactions in the hydrophobic protein core. Therefore, the substitution of basic amino acids for these neutral asparagine residues is not expected to affect the protein structure, but should increase the isoelectric point of the protein and its net positive charge, decreasing its tendency to aggregate at or below neutral pH due to electrostatic interactions. No apparent alterations in receptor binding, as determined by both cell-surface receptor competition assay and in vitro receptor dimerization experiments, were observed when these mutations were introduced into the EPO sequence. However, this mutant protein displayed a significant increase in stability to heat treatment and to storage, relative to the wild-type molecule. This resulted in a greater number of observable cross peaks in the mutant EPO in 2D NOESY experiments. However, the mutant was similar to the wild-type in stability when urea was used as a denaturant. This indicates that the introduced mutations resulted in a decrease in aggregation with heating or with prolonged incubation at ambient temperature, without changing the conformational stability or the receptor binding affinity of the mutant protein. This approach of placing charged residues at sites where N-glycosylation occurs in vivo could be applied to other systems as well.

Expression of gene for EIIIA- and EIIIB- fibronectin, fetal types of fibronectin, during gastric ulcer healing in rats

Fibronectin (FN) is important for wound healing via cell proliferation, adhesion, differentiation, and matrix formation. Fetal types of FN mRNA, which include the region of EIIIA or EIIIB, are well expressed during embryonic development and wound healing. This study was done to investigate the mRNA expression of full-length FN, EIIIA- and EIIIB-FN, and the localization of FN in the gastric tissues during ulcer healing with northern blot analysis and immunohistochemical technique. Gastric ulcers in rats were produced by acetic acid. EIIIA- and EIIIB-FN mRNA were not detected in normal gastric tissues, but were expressed in the ulcerated tissues throughout the healing phase. However, on day 60 (in the scarred phase), the EIIIA- and EIIIB-FN mRNA had disappeared. The levels of full-length FN mRNA were increased from day 3 to 32 compared with the control levels, and decreased to the control levels on day 60. Full-length FN was predominantly localized at the mesenchyme around the infiltrating inflammatory cells in the granulation tissues and the basement membranes of the nonproliferating epithelial cells, which were regenerated at the ulcer margin. Thus, fetal gene transcripts of FN suggest the important role of fetal FN in gastric ulcer healing, mainly via the migration of mesenchymal and epithelial cells.

Trehalose 6,6'-dimycolate (cord factor) of Mycobacterium tuberculosis induces foreign-body- and hypersensitivity-type granulomas in mice

Granulomatous inflammation is characterized morphologically by a compact organized collection of macrophages and their derivatives. It is classified as either a hypersensitivity type or a foreign-body type. Lipid components of the Mycobacterium tuberculosis cell wall participate in the pathogenesis of infection. Strains of M. tuberculosis have cord factor (trehalose 6,6'-dimycolate [TDM]) on their surface. To clarify host responses to TDM, including immunogenicity and pathogenicity, we have analyzed the footpad reaction, histopathology, and cytokine profiles of experimental granulomatous lesions in immunized and unimmunized mice challenged with TDM. In the present study, we have demonstrated for the first time that TDM can induce both foreign-body-type (nonimmune) and hypersensitivity-type (immune) granulomas by acting as a nonspecific irritant and T-cell-dependent antigen. Immunized mice challenged with TDM developed more severe lesions than unimmunized mice. At the active lesion, we found monocyte chemotactic, proinflammatory, and immunoregulatory cytokines. The level was enhanced in immunized mice challenged with TDM. This result implies that both nonimmune and immune mechanisms participate in granulomatous inflammation induced by mycobacterial infection. Taken together with a previous report, this study shows that TDM is a pleiotropic molecule against the host and plays an important role in the pathogenesis of tuberculosis.

Expression and purification of cytokine receptor homology domain of human granulocyte-colony-stimulating factor receptor fusion protein in Escherichia coli

Direct expression of the cytokine receptor homology (CRH) domain of granulocyte-colony-stimulating factor (G-CSF) receptor is lethal to Escherichia coli. For the efficient and stable production of an active CRH domain in E. coli, we fused the CRH domain with different proteins, such as maltose-binding protein (MalE), glutathione S-transferase, and thioredoxin (Trx). Among these, Trx appeared to be the best in terms of the protein expression level, purification efficiency by affinity chromatography, and binding activity to its ligand, G-CSF. The yield of active Trx-CRH fusion protein increased about 200-fold compared to that of previously reported MalE-CRH fusion.

[Morphological investigation of H. pylori and its culture method]

H. pylori plays important roles in the pathogenesis of active gastritis, peptic ulcer, and gastric cancer. Culture of H. pylori from suspicious materials is one of gold standard methods for the diagnosis of its infection. H. pylori has two types of morphological manifestation, spiral (mobile) and coccoid (immobile) forms. Morphological conversion from spiral to coccoid form and its reversion may be important role in its pathophysiology including bacterial properties, pathogenicity, and etiology. However, the mechanism and significance of such transformation of H. pylori have remained unknown. In this chapter, we introduce the conventional and new culture methods of H. pylori and review the current knowledge regarding both two types of morphological manifestation and pathophysiological significance of such transformation.

Gene expression analysis in colorectal cancer using practical DNA array filter

PURPOSE

We examined the usability of a newly developed, compact-sized DNA array filter for studying the gene expression pattern of individual colorectal cancer.

METHODS

Complementary DNA probes were prepared from mRNA extracted from colonic cancer specimens and adjacent normal mucosa and then were labeled with chemiluminescence. These labeled probes were allowed to bind to the gene fragments on the filter. A specialized scanning charge-coupled device camera measured the intensity of each chemiluminescent spot, which is an indicator of the degree to which a specific gene is expressed. Gene expression image was quantified into intensity of signals by using computer software.

RESULTS

Characteristic gene expression patterns were obtained from the colonic cancer cell line, RPMI4788, and the leukemia cell line, HL60, by using this compact-sized DNA array filter in the preliminary experiment. Up-regulation of nm23, TIMP1, VEGF, and cyclin E and down-regulation of some tumor suppressor genes (p53, TOSO, and SIVA), beta-catenin, and metallothionein were observed in colonic cancer specimen when compared with those of normal mucosa.

CONCLUSIONS

We have obtained unique gene expression patterns from colorectal cancer and normal tissue by using a newly developed compact-sized DNA array filter system. Collecting, storing, and analyzing of gene expression data from many samples of colorectal cancer will enable us to identify distinct subsets of patients based on molecular characteristics in the near future.

In situ generation of nitric oxide by myenteric neurons but not by mononuclear cells of the human colon

1. Production of nitric oxide (NO) is implicated in the pathogenesis of inflammatory bowel disease. However, the cells responsible for the production of NO in situ in the human colon remain unknown. 2. Surgical samples from 12 patients with ulcerative colitis, eight patients with Crohn's disease and 10 controls were studied. Possible generation of NO was visualized by reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase activity in human colon. Immunohistological staining for various NO synthase (NOS) isoforms (endothelial, neuronal and inducible), nitrotyrosine and interleukin-2 was also performed. 3. Reduced NADPH diaphorase activity was not found in lamina propria mononuclear cells, but was found in colonic epithelium, endothelium and myenteric neurons and their processes. 4. The NADPH-diaphorase activity positive processes were significantly less common in colon from patients with Crohn's disease compared with control colon. 5. Endothelial NOS was constitutively expressed on colonic endothelium. 6. Neuronal NOS was constitutively expressed on myenteric neurons. 7. Expression of inducible NOS (iNOS) was increased in the epithelium and endothelium of the colon of patients with ulcerative colitis. 8. No correlation was found between expression of iNOS and NADPH diaphorase activity. 9. Nitrotyrosine was expressed by lamina propria leucocytes, but not by epithelium. 10. Interleukin-2 was expressed on both leucocytes and myenteric neurons. 11. Colonic epithelium, endothelium and myenteric neurons synthesize NO. Myenteric neurons were principally responsible for NO production and NO may act as a neurotransmitter in the enteric nervous system.

Overexpression of co-stimulatory molecules in peripheral mononuclear cells of Helicobacter pylori-positive peptic ulcer patients: possible difference in host responsiveness compared with non-ulcer patients

BACKGROUND/AIM

Helicobacter pylori is the principal cause of gastritis and peptic ulcer disease. However, H. pylori-positive patients do not always have peptic ulcer. This study was carried out in order to determine the difference in host immune reaction to H. pylori between patients with peptic ulcer and those without.

METHODS

Ten H. pylori-positive patients with peptic ulcer, 10 H. pylori-positive non-ulcer patients, and 10 healthy volunteers were examined for expression of surface molecules in peripheral blood mononuclear cells. The surface molecules were stained with immunofluorescence-labelled specific antibodies and analysed by flow cytometry.

RESULTS

More mononuclear cells expressed molecules ICAM-1, VLA-4, Leu-M3 in H. pylori-positive ulcer patients than in non-ulcer patients and healthy volunteers. There were also more cells expressing CD28, SLe(x), CD4, HLA-DR, and NU-B2 in H. pylori-positive ulcer patients than in non-ulcer patients and healthy volunteers. There were fewer cells expressing CD8 in H. pylori-positive ulcer patients than in non-ulcer patients and healthy volunteers.

CONCLUSION

H. pylori infection may cause immunological reactions which are reflected in peripheral mononuclear cells. However, the activity and characteristics of peripheral mononuclear cells, in terms of expression of adhesion molecules, may differ between ulcer and non-ulcer patients who are infected with H. pylori.

Arterial remodeling influences the development of intimal hyperplasia after stent implantation

OBJECTIVES

We examined whether preinterventional arterial remodeling influenced the interventional results after stenting.

BACKGROUND

Arterial remodeling is seen in atherosclerotic lesions, and it may play an important role in the early stage of atherosclerosis.

METHODS

We examined 113 lesions that underwent elective stenting using tubular slotted stents under intravascular ultrasound guidance. The lesions were divided into three groups--adequate, intermediate and inadequate remodeling group--according to preinterventional arterial remodeling. The patients were subjected to coronary angiography and intravascular ultrasound evaluation on average 6.4 months after stenting.

RESULTS

At baseline and immediately after stenting, there were no differences in quantitative angiographic analysis among remodeling groups. However, the plaque cross-sectional area (CSA) in the minimal lumen CSA at preintervention and intimal hyperplasia CSA at follow-up were significantly larger in the adequate remodeling group than in the inadequate remodeling group. The restenosis rate of stenting for the lesions with inadequate arterial remodeling was very low (9.4%). A significant positive correlation was found between preinterventional plaque CSA and intimal hyperplasia CSA at follow-up (r = 0.47, p < 0.0001). Moreover, remodeling index significantly correlated with relative intimal hyperplasia CSA (r = 0.28, p < 0.01).

CONCLUSIONS

Preinterventional arterial remodeling influenced the development of intimal hyperplasia after stenting.

Decreased anti-Saccharomyces cerevisiae antibody titer by mesalazine in patients with Crohn's disease

BACKGROUND

Saccharomyces cerevisiae may contribute to the pathophysiology of Crohn's disease. We determined serum anti-Saccharomyces cerevisiae antibody (ASCA) levels in patients with inflammatory bowel disease.

METHODS AND RESULTS

Immunoglobulin G (IgG) ASCA was measured by using an ELISA in serum samples from 19 patients with ulcerative colitis, 18 patients with Crohn's disease and 7 healthy controls. The ASCA level was significantly higher in patients with ulcerative colitis and patients with Crohn's disease than in controls, and was significantly higher in patients with Crohn's disease compared with patients with ulcerative colitis. Age, gender, disease activity, extent of disease and small bowel involvement each did not affect ASCA levels. The use of elemental or polymeric diet therapy for Crohn's disease and administration of corticosteroids to patients with inflammatory bowel disease also did not affect ASCA levels. The ASCA titer was significantly lower in patients with Crohn's disease taking mesalazine than in those not taking it, although, serum IgG levels did not differ between these two groups, which might imply a suppression of IgG production by mesalazine at the intestinal level.

CONCLUSIONS

The finding of increased serum ASCA titers in patients with inflammatory bowel disease suggests that Saccharomyces cerevisiae may play a role in the pathophysiology of this condition.

Stabilization of human recombinant erythropoietin through interactions with the highly branched N-glycans

Human erythropoietin (EPO) produced in Chinese hamster ovary cells (CHO-EPO) is a hydrophobic protein stabilized by the highly branched complex-type N-glycans. To characterize the stabilizing effect of the N-glycans, the properties of enzymatically N-glycan-modified CHO-EPO species were compared spectrophotometrically. CD and fluorescence spectra following the protein unfolding induced by guanidine hydrochloride or pH revealed that the inner regions including the galactose residues of the N-glycans stabilize the protein conformation. The decrease in the conformational stability caused by enzymatic trimming of the N-glycans was associated with the exposure of the hydrophobic protein surface areas accessible to 1-anilino-8-naphthalenesulfonic acid (ANS) binding. Further, the ANS binding and heat denaturation of Escherichia coli-expressed EPO (nonglycosylated EPO) were depressed in dilute solutions (1 mM or so) of free N-glycans of the complex type. These results, together with the finding that the N-glycans of CHO-EPO make little contact with the aromatic amino acid residues exposed on the protein surface, indicate that the inner regions including the galactose residues of the intramolecular N-glycans stabilize the protein conformation by clinging to the hydrophobic protein surface areas mainly made up of nonaromatic hydrocarbon groups.

Cytoprotective effect of rabeprazole against ethanol-induced gastric mucosal damage: possible involvement of nitric oxide

The cytoprotective effect of rabeprazole, a new proton pump inhibitor, against ethanol-induced gastric mucosal damage was investigated in rats. Rats received intraperitoneal injections of rabeprazole once only or once daily for 3 days. Subsequently, the rats were given 1 ml of absolute ethanol by oral intubation. Some rats given rabeprazole were treated with N-omega-nitro-L-arginine methyl ester (L-NAME) or indomethacin. Repeated administration of rabeprazole significantly inhibited ethanol-induced gastric mucosal damage, although single administration of this drug did not. Pretreatment with L-NAME abolished the cytoprotective effect of rabeprazole. This inhibitory effect of L-NAME was reversed by L-arginine but not by D-arginine. Pretreatment with indomethacin did not influence the cytoprotective effect of rabeprazole. These results suggest that repeated intraperitoneal administration of rabeprazole has a cytoprotective effect against ethanol-induced gastric mucosal damage and that this effect may be mediated via nitric oxide but not via prostaglandins.

[Acquired pendular nystagmus associated with the lesion of tegmentum mesencephali in a patient with probable multiple sclerosis]

A 42-year old woman was admitted to our hospital because of sudden onset of dizziness and oscillopsia. Neurologic examination revealed horizontal, binocular pendular nystagmus, which increase their amplitude on left lateral gaze. She also showed that mild right blephaloptosis, right facial spasms, increased tendon reflexes and positive pathological reflexes of four limbs and mild chorea-like movement of both feet. MRI showed an abnormal high intensity area on a T2weighted and proton density images located at the right tegmentum mesencephali. She was diagnosed as clinically probable multiple sclerosis according to the Poser's criteria. The nystagmus was suppressed by clonazepam and diazepam. To our knowledge, it is a first report of acquired pendular nystagmus associated with the lesion of tegmentum mesencephali. We speculate that the involvement of the tract of paramedian pontine reticular formation causes the nystagmus and the dysfunction of GABAnergic neurons might play an important role of the nystagmus.

Direct stimulation of osteoclastic bone resorption by bone morphogenetic protein (BMP)-2 and expression of BMP receptors in mature osteoclasts

Bone morphogenetic proteins (BMPs) play an important role in various kinds of pattern formation and organogenesis during vertebrate development. In the skeleton, BMPs induce the differentiation of cells of chondrocytic and osteoblastic cell lineage and enhance their function. However, the action of BMPs on osteoclastic bone resorption, a process essential for pathophysiological bone development and regeneration, is still controversial. In this study, we examine the direct effect of BMPs on osteoclastic bone-resorbing activity in a culture of highly purified rabbit mature osteoclasts. BMP-2 caused a dose- and time-dependent increase in bone resorption pits excavated by the isolated osteoclasts. BMP-4 also stimulated osteoclastic bone resorption. The increase in osteoclastic bone resorption induced by BMP-2 was abolished by the simultaneous addition of follistatin, a BMP/activin binding protein that negates their biological activity. Just as it increased bone resorption, BMP-2 also elevated the messenger RNA expressions of cathepsin K and carbonic anhydrase II, which are key enzymes for the degradation of organic and inorganic bone matrices, respectively. Type IA and II BMP receptors (BMPRs), and their downstream signal transduction molecules, Smad1 and Smad5, were expressed in isolated osteoclasts as well as in osteoblastic cells, whereas type IB BMPR was undetectable. BMPs directly stimulate mature osteoclast function probably mediated by BMPR-IA and BMPR-II and their downstream molecules expressed in osteoclasts. The results presented here expand our understanding of the multifunctional roles of BMPs in bone development.