Peripheral quantitative computed tomography (pQCT) is useful for monitoring bone mineral density of the patients who receive hormone replacement therapy

OBJECTIVE

A forearm fracture (Colles' fracture) is often the first sign of osteoporosis and should alert the patient and physician to the possibility of underlying skeletal fragility. Therefore, the establishment of a more accurate and reliable method for the measurement of bone mineral density (BMD) at the distal radius would be beneficial for the patients who suffer from osteoporosis. The objective of the present study was to evaluate the usefulness of peripheral quantitative computed tomography (pQCT) to assess the change of BMD at the distal radius in early postmenopausal women who receive hormone replacement therapy (HRT).

METHODS

Twenty healthy early postmenopausal women who were diagnosed as osteoporosis or osteopenia were randomized to either HRT or placebo treatment. We analyzed BMD of the distal radius by pQCT, lumbar spine by dual-energy X-ray absorptiometry (DXA) and the biochemical markers of bone turn over (osteocalcin, deoxypyridinoline) every 6 months.

RESULTS

The placebo group showed a significant decrease from the baseline in the trabecular BMD of the radius at 12 months (7.4+/-2.5%) (p<0.05), whereas the HRT group showed a slight increase (0.7+/-2.2%). The changes in the trabecular BMD of the radius between the HRT and placebo groups were statistically different at 12 months (p<0.05). On the other hand, in the cortical BMD of the radius, no significant differences were seen between the changes of bone densities in the HRT and control groups after 1 year of treatment. pQCT could detect a significant loss of BMD of the radius in early postmenopausal women after 1 year and HRT prevented its loss.

CONCLUSION

Our preliminary clinical trial showed that pQCT might be useful for the early detection of bone loss in early postmenopausal women and for the monitoring BMD of the patients who receive HRT.

Tribochemical Reaction Dynamics of Phosphoric Ester Lubricant Additive by Using a Hybrid Tight-Binding Quantum Chemical Molecular Dynamics Method

To study the atomistic behavior of the phosphoric ester molecule on the nascent Fe surface under boundary lubrication conditions, we adopted a hybrid tight-binding quantum chemical molecular dynamics method. First, we investigated chemical interactions between phosphoric ester and the nascent Fe surface. Phosphoric ester was shown to interact with the nascent Fe surface, forming both covalent and ionic bonds. Formation and dissociation dynamics of covalent bonds during tribochemical reaction was clearly observed during the simulation. The effect of friction condition on the tribochemical reaction dynamics was then studied, and it was indicated that friction would influence the formation and the dissociation of covalent bonds. By using a hybrid tight-binding quantum chemical molecular dynamics method, we obtained insights on initial tribochemical reaction processes for the formation of tribofilm from the phosphoric ester molecule on the nascent Fe surface.

Transient Cardiomyopathy in a Patient with Congenital Contractural Arachnodactyly (Beals Syndrome)

We report on an infant with Beals syndrome (congenital contractural arachnodactyly [CCA], MIM 121050) with transient cardiomyopathy showing ballon-like dilatation of the left ventricle that was similar to noncompaction. The patients father and two of his brothers were also found to have CCA without cardiovascular complications. CCA, which is caused by a mutation of the gene for fibrillin 2 protein is similar to Marfan syndrome (MIM 154700), which is caused by a mutation of fibrillin 1 but produces a life-threatening cardiovascular complications. This is the first report of CCA with transient cardiomyopathy. We discuss the mechanism of the spontaneous improvement of cardiomyopathy in this case on the basis of expression of the responsible gene.

Brain white matter changes during treatment of a child for acute lymphoblastic leukemia

A 13-year old boy with acute lymphoblastic leukemia had bilateral paresis of the upper extremities and aphasia 1 week after high dose methotrexate and triple intrathecal therapy (methotrexate, cytarabin, hydrocortisone). The stroke-like neurological symptoms disappeared on the third day. T2-weighted magnetic resonance imaging showed hyperintensities of white matter on the second day. Despite resolution of the neurological symptoms, magnetic resonance images were still abnormal 3 years after the attack. Methotrexate has been considered to be responsible for ischemic damage to oligodendroglial cells, resulting in demyelination. The changes are occasionally prolonged without persistent neurologic symptoms.

"Promoter Array" Studies Identify Cohorts of Genes Directly Regulated by Methylation, Copy Number Change, or Transcription Factor Binding in Human Cancer Cells

DNA microarrays of promoter sequences have been developed in order to identify the profile of genes bound and activated by DNA regulatory proteins such as the transcription factors c-Jun and ATF2 as well as DNA-modifying methylases. The arrays contain 3083 unique human promoter sequences from +500 to -1000 nts from the transcription start site. Cisplatin-induced DNA damage rapidly leads to specific activation of the Jun kinase pathway leading to increased phosphorylation of c-Jun and ATF2-DNA complexes at hundreds of sites within 3 hours. Using three statistical criteria, approximately 269 most commonly phosphorylated c-Jun/ATF2-DNA complexes were identified and representative cases were verified by qPCR measurement of ChIP-captured DNA. Expression was correlated at the mRNA and protein levels. The largest functional cohort was 24 genes of known DNA repair function, most of which exhibited increased protein expression indicated coordinate gene regulation. In addition, cell lines of prostate cancer exhibit stable methylation or copy number changes that reflect the alterations of the corresponding primary tumors. 504 (18.5%) promoters showed differential hybridization between immortalized control prostate epithelial and cancer cell lines. Among candidate hypermethylated genes in cancer-derived lines, eight had previously been observed in prostate cancer, and 13 were previously determined methylation targets in other cancers. The vast majority of genes that appear to be both differentially methylated and differentially regulated between prostate epithelial and cancer cell lines are novel methylation targets, including PAK6, RAD50, TLX3, PIR51, MAP2K5, INSR, FBN1, GG2-1, representing a rich new source of candidate genes to study the role of DNA methylation in prostate tumors. Earlier studies using prototype promoter arrays examine approximately 7% of the proximal regulatory sequences while the current gene regulatory events surveyed here occur on a large scale and may rapidly effect the coordinated expression of a large number of genes.

T-cell dynamics of inflammatory skin diseases

The migration of memory T-cells to sites of inflammation is a multistep process controlled by an array of specific receptor-ligand pairs. Chemokines and their receptors represent a central paradigm of the molecular basis of the skin-homing of T-cells. Although CCR4 and CCR10 are both associated with conventionally defined skin-homing T-cells, the association is not necessarily perfect. Interaction between E-selectin and its ligand may represent more specific targets for therapeutic intervention. Although fucosyl transferase?VII is essential for generating E-selectin ligands necessary for T-cell homing to skin, fucosyltransferase-IV, another fucosyltransferase expressed to a significant degree in T-cells, can also generate E-selectin ligands. The induction and upregulation of both enzymes can be co-ordinately regulated depending on their state of activation and differentiation and the cytokine milieu. The dynamic balance between the two enzymes is a major check point for the regulation of skin-homing T-cell differentiation. Polarized T-cells regulate their adhesions on a minute-to-minute basis depending on the cytokine environment. Soluble adhesion molecules found to be increased in chronic inflammatory skin diseases may serve to limit the duration or magnitude of T-cell recruitment. In addition to T-cells migrating from the circulation, T-cells indigenously residing in the tissue itself, such as skin-resident T-cells, would also be responsible for tissue damage. It should also be appreciated that T-cell recruitment to the skin is critical for host defense and that no definitive means exist to distinguish protective regulatory T-cells from pathogenic T-cells.

Role of bone marrow cells in the healing process of mouse experimental glomerulonephritis

Recent studies have shown bone marrow (BM) cells to differentiate into a variety of cell types and to thereby participate in the reconstitution of damaged organs. In the present study, we examined the extent to which BM-derived cells are incorporated into glomeruli during recovery from experimentally induced nephritis. To investigate the localization of BM cells in glomeruli, chimeric mice were prepared by transplanting BM cells from green fluorescent protein (GFP) transgenic mice into wild-type mice. Five weeks later, glomerulonephritis was induced by intravenous injection of Habu snake venom. Groups of mice were then killed every few days for 42 d, and harvested kidney samples were subjected to immunohistochemical and immunoelectron microscopic analyses with the aim of detecting the presence of GFP(+) cells within glomeruli. Chimeric animals injected with Habu venom developed proliferative glomerulonephritis within 1-3 d. The lesion gradually subsided and the glomerular structure returned to normal within 42 d. Consistent with the disease course, large numbers of GFP(+) cells were present within glomeruli on d 1-3, but most had disappeared by d 7. Nevertheless, some GFP(+) cells did remain within glomeruli showing mesangial proliferative changes, and were found to express thrombomodulin (TM), a specific endothelial cell marker. These GFP-TM-double-positive cells accounted for a mean of 1.31-2.24% of the total glomerular nuclei from d 7 through d 42, levels that remained stable for at least 12 mo. It thus appears that BM cells can give rise to endothelial cells that participate in the remodeling of glomeruli.

Mechanisms of platinum drug resistance

Platinum-based drugs are among the most active anticancer agents available and are used widely for the treatment of a variety of human solid tumors. Although patients show high response rates to platinum drugs, most patients develop resistance to these drugs during treatment. Because the acquisition of resistance is a major obstacle to the clinical use of platinum drugs, the processes by which cells develop such resistance are of great interest and efforts have been made to overcome this problem. Both mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) cascades are involved in resistance to these drugs, and clinical trials of some small-molecule inhibitors of the MAPK and PI3K-Akt cascades to overcome resistance to platinum drugs are ongoing.

Animal models for atopic dermatitis: are they relevant to human disease?

Over the last decade, animal models of atopic dermatitis (AD) have received increasing attention. They include NC/Nga mice, a hapten-induced mouse model, and transgenic and knockout mouse models. Although the pathogenesis of skin inflammation elicited in these models and that in AD are not quite the same, it is pertinent to ask what these animal models really tell us about the pathogenesis and possible therapies for the disease. NC/Nga mice may yield information relevant to the dissection of the crucial components of the pathophysiology of AD rather than the assessment of potentially therapeutic agents for its treatment. A hapten-induced mouse model created by repeated application of 2,4,6-trinitrochlorobenzene (TNCB) is a simple and reproducible one. This model offers several advantages over others: by changing hapten and the mouse strain used, various types of chronic inflammation, probably reflecting heterogeneity in clinical presentation of AD, can be induced; this model is also of enormous value in its high reproducibility as well as the ease of quantitative assessment by measuring ear thickness. Among various transgenic and knockout mouse models, the IL-18-transgenic mouse is one of the closest available mouse models of human AD, although the onset of the AD-like lesions in the IL-18-transgenic mice is such a late event. Although these mice all have significant disadvantages, it is important to review the current literature on the models in the hope that one may identify useful areas for investigation.

Evaluation of ejectors using the venturi effect for a continuous positive airway pressure system without compressed air

The purpose of this study is to perform a test in the application of the existing ejectors with the continuous positive airway pressure (CPAP) system without compressed air. Four types of ejector (jet mixer, the former and new puritan nebulizer and the deluxe nebulizer) for blending oxygen and room air by the Venturi effect were tested. A decrease of mixed gas flow and an increase of oxygen concentration were observed according to the increase of positive pressure in all systems. The former puritan nebulizer and deluxe nebulizer were found to be unavailable for the CPAP system for high oxygen concentration and low mixed gas flow for the increase of positive pressure. In the system, however, with the new puritan nebulizer and jet mixer, a sufficient mixed gas flow and an appropriate oxygen concentration could be supplied at an adequate positive pressure. The CPAP system using only oxygen was judged as possibly giving availability.

Identification of promoters bound by c-Jun/ATF2 during rapid large-scale gene activation following genotoxic stress

The NH2-terminal Jun kinases (JNKs) function in diverse roles through phosphorylation and activation of AP-1 components including ATF2 and c-Jun. However, the genes that mediate these processes are poorly understood. A model phenotype characterized by rapid activation of Jun kinase and enhanced DNA repair following cisplatin treatment was examined using chromatin immunoprecipitation with antibodies against ATF2 and c-Jun or their phosphorylated forms and hybridization to promoter arrays. Following genotoxic stress, we identified 269 genes whose promoters are bound upon phosphorylation of ATF2 and c-Jun. Binding did not occur following treatment with transplatin or the JNK inhibitor SP600125 or JNK-specific siRNA. Of 89 known DNA repair genes represented on the array, 23 are specifically activated by cisplatin treatment within 3-6 hr. Thus, the genotoxic stress response occurs at least partly via activation of ATF2 and c-Jun, leading to large-scale coordinate gene expression dominated by genes of DNA repair.

Case of Henoch-Schoenlein Purpura with Rare Complications: Necrosis of the Small Intestine, Neurological Symptoms, and Pericardial Tamponade

A case of Henoch-Schönlein purpura (HSP) with necrosis of the small intestine, neurological symptoms, and pericardial tamponade after frequent recurrence is described. Neurological symptoms were controlled well with steroid pulse therapy, and pericardial tamponade was treated successfully with pericardiocentesis and steroid pulse therapy. To treat necrosis of the small intestine, the necrotic tissue was excised and artificial anuses were constructed. Five months later, the small intestine was anastomosed in a curative operation. Periodic administration of coagulation factor XIII was required from the onset of symptoms until curative surgery, but the activity of this factor returned to normal levels after surgery operation. We report a case of Henoch-Schönlein purpura with extremely rare complications: necrosis of the small intestine, neurological symptoms, and pericardial tamponade.

Clinical Aspects of Infant Leukemia-Experiences of a Single Institution of Japan: High Level of Serum Immunoglobulin M in Infant Leukemia

The prognosis and clinical and biological characteristics of infant leukemia differ from those of leukemia in children 1 year or older. We reviewed the charts of patients younger than 1 year in whom leukemia was diagnosed from January 1981 through December 2003 at our institution. Fourteen infants had leukemia, 6 had acute lymphoblastic leukemia (ALL), and 8 had acute myeloid leukemia (AML). The age of patients at diagnosis ranged from 2 to 11 months. Five of 8 AML patients presented with cutaneous manifestations, such as erythema and nodules, at diagnosis. Central nervous system (CNS) involvement was seen in 1 AML patient at diagnosis. Hyperleukocytosis of more than 50 x 10(9)/L was seen in 4 of 6 ALL patients and in 4 of 8 AML patients at diagnosis. All ALL patients showed a morphological diagnosis of L1 using the French-America-British classification system. For patients with AML, the morphological diagnoses were M0 for 1 patient, M2 for 1 patient, M4 for 2 patients (1 with eosinophilia), M5b for 2 patients, and M7 for 2 patients. One patient showing M7 morphology had Down syndrome. Surface markers were examined in 5 of 6 ALL patients and all AML patients. Five ALL patients showed a B-cell precursor immunophenotype. Two of 5 patients with ALL had CD10-positive leukemic cells and 3 of 5 patients with ALL had CD10-negative leukemic cells. All AML patients were positive for CD13 or CD33 or both. Three of 5 patients with ALL showed abnormal chromosomes related to 11q. Six of 7 patients with AML showed abnormal karyotypes. MLL gene rearrangements were seen in 3 (2 ALL, 1 AML) of 5 (2 ALL, 3 AML) patients. Serum immunoglobulin M levels were increased in 9 of 14 patients. Complete remission (CR) was achieved in all infants with ALL. Three patients relapsed and then died of the original disease. One of these 3 patients died after cord blood transplantation. Three ALL patients are alive without leukemia. CR was achieved in 6 of 8 AML patients. Four of 6 patients are alive without leukemia. Infant leukemia patients in our institution had some special features. CNS involvement at diagnosis was seen in only 1 patient and serum IgM levels were higher than those in children whose leukemia was diagnosed at 1 to 10 years of age.

Simultaneous analysis of phospholipid in rabbit bronchoalveolar lavage fluid by liquid chromatography/mass spectrometry

A method was developed to separate and simultaneously quantitate phosphatidylglycerol (PG), phosphatidylinositol (PI), phosphatidylethanolamine (PE), phosphatidylcholine (PC), sphingomyelin (SM) and lysophosphatidylcholine (LPC) in rabbit bronchoalveolar lavage fluid (BALF) by liquid chromatography/mass spectrometry (LC/MS). This method consisted of a simple liquid-liquid extraction procedure, separation of phospholipid classes on silica gel column by gradient mode, and detection of mass spectrometry with electrospray ionization (ESI). The precision, accuracy and recovery ranged from 1.6 to 7.6%, -0.8 to +14.7% and 69.3 to 90.0%, respectively. This method was applied to compare the content and the composition of phospholipid classes in BALF collected from inflammation-model and control rabbit. The ratio of LPC concentration to PC significantly increased in inflammation-model BALF compared with control BALF.

Inhibition of phosphorylation of a forkhead transcription factor sensitizes human ovarian cancer cells to cisplatin

The Forkhead family transcription factor FKHRL1 is an inducer of apoptosis in its unphosphorylated form and was recently reported to be a substrate of Akt kinase. We studied the roles of FKHRL1 in both cisplatin-resistant Caov-3 (a papillary adenocarcinoma cell line) and cisplatin-sensitive A2780 human ovarian cancer cell lines. Treatment of Caov-3 cells but not A2780 cells with cisplatin transiently stimulated the phosphorylation of FKHRL1. Transfection experiments revealed that a kinase inactive-mutant of Akt or a triple mutant (TM) of FKHRL1, in which all three of the putative Akt phosphorylation sites were converted to alanine, was unable to phosphorylate the FKHRL1 protein in cells treated with cisplatin. Because the phosphorylated form of FKHRL1 is known to be localized in the cytoplasm, we examined whether cisplatin-induced phosphorylation of FKHRL1 might have an effect on the subcellular distribution of FKHRL1. Cisplatin induced the localization of FKHRL1 in the cytoplasm in Caov-3 cells but not in A2790 cells. Moreover, cisplatin induced the association of 14-3-3 protein with phosphorylated-FKHRL1 in Caov-3 cells but not in A2790 cells. Because the unphosphorylated form of FKHRL1 binds the Fas ligand promoter, thereby inducing apoptosis, we further examined the effect of the phosphorylation status of FKHRL1 on the activity of the Fas ligand promoter in the presence of cisplatin. Transfection with the kinase-inactive mutant of Akt or TM of FKHRL1 induced the activity of the Fas ligand promoter in Caov-3 cells. Moreover, exogenous expression of TM of FKHRL1 in Caov-3 cells decreased the cell viability after treatment with cisplatin. Our findings suggest that cisplatin causes the phosphorylation of FKHRL1 via a phosphatidylinositol 3-kinase/Akt cascade, and inhibition of this cascade sensitizes ovarian cancer cells to cisplatin.

Recipient non-hematopoietic bone marrow cells in the intestinal graft after fetal small intestinal transplantation

We examined whether non-hematopoietic BM cells can migrate into the intestinal graft after fetal small intestinal transplantation (FSITx). Fetal small intestine from donor C57BL/6 mice was transplanted into the rectus abdominis of recipient C57BL/6 mice with only green fluorescent protein (GFP) BM cells (syngeneic FSITx). Intestinal grafts were harvested on days 5, 10, and 30 after FSITx and stained immunohistochemically using anti-CD45 antibody (a marker for hematopoietic BM cells). Although there were no GFP-positive cells identified in the epithelium of the graft intestinal villi, there were a few cells positive for both GFP and CD45 in the lamina propria on day 5 after FSITx, and many present on days 10 and 30. In some grafts there were only cells that were GFP positive/CD45 negative (i.e., non-hematopoietic BM cells) found in the lamina propria on days 10 and 30. These data indicate that non-hematopoietic BM cells as well as hematopoietic BM cells can migrate from the recipient's bone marrow, suggesting that recipient mesenchymal stem cells may be strongly implicated in graft regeneration and development after FSITx.

Establishment of Modified Retroviral Vector Targeting X-Linked Severe Combined Immunodeficiency

Gene therapy targeting hematopoietic stem cells has been proposed as a potential therapy for numerous genetic disorders affecting hematopoiesis. Moloney murine leukemia retroviral vectors are now widely used for clinical gene transfer into hematopoietic progenitors and progeny. However, maintaining expression of therapeutic genes inserted via moloney murine leukemia virus (MoMLV)-based vectors has proven to be more difficult than previously expected. In this study, an MND-IL-2R vector containing IL-2Rc gamma cDNA to treat X-linked severe combined immunodeficiency (X-SCID) was constructed from an MND vector that was modified by substituting the myeloproliferative sarcoma virus (MPSV) enhancer for that of MoMLV, deleting the negative control region located in the long terminal repeat (LTR) as an enhancer, and replacing the primer binding site (PBS) of MoMLV with the PBS of the endogenous murine retrovirus dl587rev. This vector was transduced into human CD34 + progenitor cells with comparable efficiency to that of the MoMLV-based vector. The use of this newly created vector may be advantageous for gene therapy of X-SCID.

Syntheses of Potential Metabolites of a Potent .KAPPA.-Opioid Receptor Agonist, TRK-820

Chemical syntheses of three kinds of potential metabolites of TRK-820, a potent kappa-opioid receptor agonist, were described. One of the potential metabolites 2, 17-N-dealkylated TRK-820, was synthesized starting from noroxycodone through 8 steps in 21% total yield. Glucuronidation of intermediate 10 and compound 1, the free base of TRK-820, was carried out stereoselectively to give 3-O-beta-D-glucuronides 15 and 16 in good yields, respectively. Syntheses of potential conjugated metabolites 3 and 4 were accomplished through 10 steps and 2 steps in 11% and 43% total yields, respectively. Among the potential metabolites of TRK-820, compounds 2 and 4 were identified as metabolites in human hepatocytes. The results of pharmacological studies of compounds 2, 3, and 4 are described.

In Vitro Differentiation from Naive to Mature E-Selectin Binding CD4 T Cells: Acquisition of Skin-Homing Properties Occurs Independently of Cutaneous Lymphocyte Antigen Expression

We previously showed that skin-homing CD4 T cells in peripheral blood can be subdivided into three populations on the basis of the expression pattern of the cutaneous lymphocyte Ag (CLA) and fucosyltransferase VII (FucT-VII): FucT-VII(+)CLA(-), FucT-VII(+)CLA(+), and FucT-VII(-)CLA(+). In view of the known late appearance of CLA during T cell differentiation, T cells programmed to attain skin-homing properties may start to generate E-selectin-binding epitopes at early stages of differentiation before induction of CLA expression. To this end, the in vitro differentiation from naive to CLA(+) memory T cells was followed after activation with anti-CD3 mAb. Here we demonstrate that naive skin-homing CD4 T cell precursors undergo a linear differentiation process from the FucT-VII(+)CLA(-) phenotype to the FucT-VII(+)CLA(+) phenotype and eventually to the FucT-VII(-)CLA(+) phenotype. The appearance of the FucT-VII(+)CLA(-) subset coincided with or could be immediately followed by the generation of E-selectin binding epitopes, and even after E-selectin-binding epitopes were no longer detectable, CLA remained expressed for prolonged periods of time, suggesting that induction of functional E-selectin ligands depends primarily on the expression of FucT-VII, but not CLA. Immunofluorescence and confocal microscopy studies of these T cells confirm that most E-selectin ligands were found independently of CLA expression.

Egr1 signaling in prostate cancer

Egr1 is a multifunctional transcription factor regulating a remarkable spectrum of cellular responses from survival to apoptosis, growth to growth arrest, differentiation to transformation, senescence as well as memory and learning effects. In prostate cancer, Egr1 levels are constitutively high and closely linked to cancer development and progression. This zinc-finger protein is a short-lived, immediate early growth response gene known to be induced by a large number of extracellular stimuli such as irradiation (all wavelengths tested), hypoxia, hyperoxia, chemotherapy agents, and more. Therefore the target genes that Egr1 regulates in prostate cancer cells play an important role in generating many of the cellular responses that characterize these cells. After Egr1 binds to its binding sites on gene promoters, specificity of response is determined by whether Egr1 transcriptionally up- or downregulates the target genes. Expression microarray analyses combined with binding data promise new ways to identify stage specific cancer markers, to aid in patient risk assessment and in therapeutic choices.

Cardiomyocyte regeneration from circulating bone marrow cells in mice

We investigated the role of circulating bone marrow cells (BMC) in cardiomyocyte regeneration. BMC, isolated from transgenic mice expressing enhanced green fluorescent protein (GFP), were transplanted into lethally irradiated C57BL6 mice. Five weeks after bone marrow transplantation (BMT), flow cytometric analysis for GFP-positive cells confirmed reconstitution of transplanted bone marrow. Bone marrow transplant mice subsequently underwent left coronary artery ligation (myocardial infarction) or sham-operation, and were killed at 1 mo or 3 mo after operation. Infarct size was similar in bone marrow transplant mice at 1 mo (47.1 +/- 5.9%) and at 3 mo (45.3 +/- 7.8%), and echocardiography at 2 and 8 wk revealed decreasing left ventricular function. In infarcted heart, GFP-positive cells that expressed desmin and troponin T-C were identified by confocal microscopy. GFP and troponin T-C double-positive cells were predominantly in the peri-infarcted region (1 mo, 365 +/- 45 cells/50 sections; 3 mo: 458 +/- 100 cells/50 sections; p < 0.05 versus noninfarct, infarct, and sham-operated regions). Furthermore, BMC mobilization and differentiation into cardiomyocytes was found to be complete within 1 mo after myocardial infarction. These results demonstrate that circulating BMC undergo mobilization and differentiation in cardiac cells after myocardial infarction. Future studies are required to determine the molecular signaling mechanisms responsible for this phenomenon.