Biomedical subjects

T Ashihara

Publications and source records attributed to T Ashihara.

At least 19 recordsLinked to original sources

PubMed2001

Breakthrough waves during ventricular fibrillation depend on the degree of rotational anisotropy and the boundary conditions: a simulation study.

INTRODUCTION: The left ventricle (LV) and right ventricle (RV) are characterized by specific fiber orientation known as "rotational anisotropy." However, it remains unclear whether the LV and RV are different with regard to the effect of rotational anisotropy on the dynamics of scroll waves during ventricular fibrillation (VF). To resolve this issue, we used a computation-based model to study scroll wave behavior. METHODS AND RESULTS: We composed an environment of simulated three-dimensional ventricular wall slabs, with optional ratios of fiber rotation to wall thickness (0 degrees, 6 degrees, and 12 degrees/mm thickness; LV 10 mm, RV 5 mm), using Luo-Rudy phase I equations. When rotational anisotropy was not incorporated into the LV wall slab (theta endo to approximately theta epi = 0 degrees), most scroll waves rotated around the filaments perpendicular to the tissue surface, with only a few accompanying breakthrough waves. In a twisted LV model (theta endo to approximately theta epi = 60 degrees and 120 degrees), the scroll waves were demonstrated as multiple wavelets scattered spatiotemporally, frequently accompanied by breakthrough waves that were promoted by rotational anisotropy. In a twisted RV model (theta endo to approximately theta epi = 30 degrees and 60 degrees), single scroll waves and/or figure-of-eight reentrant waves appeared, with comparatively few breakthrough waves, regardless of the degree of fiber twist. CONCLUSION: The proportion of electrical effects of rotational anisotropy and tissue boundaries plays an important role in the genesis of breakthrough waves during VF, and the difference in wave propagating patterns and frequency spectrum of the ventricles may arise, in part, from the number of breakthrough waves promoted by rotational anisotropy.

Anisotropy↗

PubMed2001

Electroporation in a model of cardiac defibrillation.

INTRODUCTION: It is known that high-strength shock disrupts the lipid matrix of the myocardial cell membrane and forms reversible aqueous pores across the membrane. This process is known as "electroporation." However, it remains unclear whether electroporation contributes to the mechanism of ventricular defibrillation. The aim of this computer simulation study was to examine the possible role of electroporation in the success of defibrillation shock. METHODS AND RESULTS: Using a modified Luo-Rudy-1 model, we simulated two-dimensional myocardial tissue with a homogeneous bidomain nature and unequal anisotropy ratios. Spiral waves were induced by the S1-S2 method. Next, monophasic defibrillation shocks were delivered externally via two line electrodes. For nonelectroporating tissue, termination of ongoing fibrillation succeeded; however, new spiral waves were initiated, even with high-strength shock (24 V/cm). For electroporating tissue, high-strength shock (24 V/cm) was sufficient to extinguish ongoing fibrillation and did not initiate any new spiral waves. Weak shock (16 to 20 V/cm) also extinguished ongoing fibrillation; however, in contrast to the high-strength shock, new spiral waves were initiated. Success in defibrillation depended on the occurrence of electroporation-mediated anodal-break excitation from the physical anode and the virtual anode. Some excitation wavefronts following electrical shock used a deexcited area with recovered excitability as a pass-through point; therefore, electroporation-mediated anodal-break excitation is necessary to block out the pass-through point, resulting in successful defibrillation. CONCLUSION: The electroporation-mediated anodal-break excitation mechanism may play an important role in electrical defibrillation.

Action Potentials↗

PubMed2001

Acridine orange induces binucleation in chondrocytes.

OBJECTIVE: Although it is well known that binuclear cells commonly appear among the chondrocytes of normal cartilages as well as among neoplastic chondrocytes of chondrosarcomas, the mechanism of binucleation is still unclear. Therefore, this study was undertaken to clarify the mechanism of binucleation in chondrocytes, using primary culture cells of growth plate cartilage. DESIGN: These chondrocytes were exposed to acridine orange (AO) which is a fluorescent dye for differentiating certain DNAs and RNAs in nuclei and cytoplasm, and which inhibits mitosis. After exposure to 0.5 microg/ml AO, for 0, 6, 24, 48, and 96 h, the following parameters were investigated: (1) cell growth rate (GR); (2) frequency of hyperdiploid cells (%HDC) by DNA cytofluorometry; (3) mitotic index (MI); (4) BrdU labeling index (LI); (5) frequency of binuclear cells (%BNC). RESULTS: Compared with the control cells, which were cultured in AO-free medium, the GR was remarkably inhibited at 24 h. MI was also decreased from 6 to 24 h, and LI decreased at 48 h. However, these parameters were recovered at 96 h. The %HDC was increased from 6 to 96 h, and the %BNC was also increased to a maximum of six times that of the control cells at 96 h. DISCUSSION: These results suggested that the binuclear cells observed among the cultured chondrocytes may be formed from G2 arrested cells by amitotic nuclear division, but not by mitosis without cytoplasmic division or cell fusion.

Acridine Orange↗

PubMed2001

DNA cytofluorometric analysis of chondrocytes in human articular cartilages under normal aging or arthritic conditions.

OBJECTIVE: Since most chondrocytes in articular cartilage are in the resting phase (G0) of the cell cycle, it has been difficult to investigate their cell kinetics using 3H-thymidine autoradiography, or immunohistochemistry. In the present study, DNA cytofluorometry, which is useful to analyse the cell kinetics even for such inactive cell populations as in the G0 phase, was applied to human chondrocytes of the articular cartilages under normal aging and pathologic conditions such as osteoarthritis (OA), rheumatoid arthritis (RA), and aseptic necrosis (AN). DESIGN: The human articular cartilages for the study were obtained from autopsy and surgical materials. Fifty joints were used for the study of aging, 54 for the study of OA, 20 for studying RA, and 10 for AN study. The isolated chondrocytes were quickly prepared from fresh articular cartilages, using a combination method of enzymatic digestion with papain and collagenase, followed by mechanical cell separation by churning and homogenization. RESULTS: The DNA histograms obtained by cytofluorometry with propidium-iodide staining showed that most chondrocytes had diploid DNA content (2c) in all cartilages studied, suggesting that they were in the G0 phase. However, there were a few chondrocytes having tetraploid DNA content (4c) in the normally aged articular cartilages, and there were some cells having DNA content between 2c and 4c in the diseased cartilages. The former cells were considered to be G0-phase cells of the 4c chondrocytes, while the latter cells were considered to be in the DNA synthetic (S) phase or G2-phase of the 2c chondrocytes. The frequency of 4c chondrocytes in aged cartilage was significantly increased, compared to that in the young cartilage. In contrast to the normal cartilage, the frequency of S- and G2-phase cells, which was expressed as the S- G2 index, in diseased cartilages (OA, RA and AN) was significantly high (P< 0.0001). In OA cartilage, the S-G2 index was much higher in the severe or moderate stage than in the mild stage, suggesting that the chondrocytes in clusters may actively proliferate. CONCLUSION: These results showed that in normal articular cartilages most chondrocytes are in the G0 phase, while some became 4c polyploid cells, and that these G0-phase chondrocytes had a potential to proliferate under diseased conditions.

Adolescent↗

PubMed2000

Clonal expansion in evolution of chronic hepatitis to hepatocellular carcinoma as seen at an X-chromosome locus.

Clonal analysis has shown that hepatocellular carcinoma arises from a single cell. However, the clonality of precancerous lesions and adjacent nonneoplastic tissues is not clear. We analyzed a human androgen receptor locus to elucidate the clonal state of liver tissues including post-hepatitic lesions associated with hepatocarcinogenesis. The analysis was based on a restriction fragment length polymorphism involving an androgen receptor locus on the X chromosome, taking advantage of physiologic random inactivation by methylation of 1 of 2 X chromosomes in females during embryogenesis. Clonality was assessed in 79 randomly located tissue samples microdissected from noncirrhotic liver, including a total of 40 morphologically normal sites in 4 normal livers and 39 sites from a single HCV-infected liver. In addition, 51 regenerative nodules, 4 areas of adenomatous hyperplasia, and 18 hepatocellular carcinomas were sampled. All samples were obtained from livers involved by various neoplasms. Eight of forty samples (20.0%) from the four normal livers and 20 of the 39 samples (51.3%) from the single HCV-infected liver showed a monoclonal pattern. Moreover, 30 of 51 regenerative nodules (58.9%) showed a monoclonal pattern. No histologic differences were evident between mono- and polyclonal nodules. On the other hand, the 18 carcinomas and 4 areas of adenomatous hyperplasia all were monoclonal. Mean calculated monoclonal areas of normal liver and liver with chronic hepatitis were 1.1 and 3.3 mm(2). Our results suggest that areas representing a single clone of hepatocytes are present in normal liver, and these progressively expand as changes advance from chronic hepatitis to hepatocellular carcinoma.

Aged↗

PubMed2000

A long-term survival case of multiple hepatocellular carcinoma with metachronous lymph node metastasis.

A long-term survival case of multiple hepatocellular carcinoma (HCC) with metachronous metastasis to a lymph node is reported. The patient, a 66-year-old woman, had two primary HCC nodules, one each in the left and right hepatic lobes, which were resected. She developed a lymph node lesion and a secondary HCC 45 and 62 months after the first operation, respectively. She has been well for the 7 years since the first operation despite undergoing hepatic resection for HCC twice as well as lymph node resection. Clonal analysis, based on the methylation pattern of the X chromosome-linked androgen receptor gene, suggested that the two primary tumors were multicentric and that the lymph node lesion had arisen by metastasis from the primary tumor in the right hepatic lobe.

Journal Article↗

PubMed2000

Development of bone canaliculi during bone repair.

We recently found that silver impregnation staining with protargol (silver protein), that is, a modified Bodian method, is useful for histologically identifying the details of bone canaliculi structure, using thin sections of decalcified bone tissues. With this staining method, we conducted the present study to assess the development of bone canaliculi during the process of intramembranous ossification using a fracture-like stimulation model of the rat femur. After making a drill-hole in the cortex of the rat femur, decalcified thin sections were obtained after 3, 5, 7, and 14 days by the standard paraffin-embedding procedure. Silver staining for bone canaliculi was performed using our previously reported technique. The results showed that woven bone covered the fracture surface of the cortex after 5 days, then immature lamellar bone attached to the woven bone after 7 days, and finally the lamellar bone matured and became thick with appositional growth after 14 days. The osteocytes in the woven bone appeared at an early stage of bone repair and developed a few canaliculi that were short and irregularly distributed in the osteoid matrix, while the osteocytes in the lamellar bone at a late stage formed many bone canaliculi that were long and regularly distributed in mature bone matrix. Therefore, we concluded that woven bone osteocytes may be necessary for induction of the lamellar bone osteocytes followed by active appositional growth of the lamellar bone at the early stage of bone repair, and also that both bone tissues could be clearly distinguished from one another based on the pattern of development of bone canaliculi by the osteocytes, as seen with the use of our sensitive staining method.

Animals↗

PubMed2000

Osteoblastic differentiation and P-glycoprotein multidrug resistance in a murine osteosarcoma model.

A recent study of multidrug resistance (MDR) 1 gene transfected osteosarcoma cells found a cause-effect relationship between increased expression of P-glycoprotein (P-gp) and a low aggressive phenotype. However, several experimental and clinical studies have observed contradictory findings in that P-gp expression has been associated with tumour progression. In the present study, we characterized P-gp-positive and P-gp-negative single-cell clones of a murine osteosarcoma, to further investigate the relationship between P-gp expression and changes in cell phenotype. Although these clones were all selected by doxorubicin (DOX) exposure, they were heterogeneous with respect to MDR1 gene expression. The P-gp-positive clones revealed MDR phenotype, whereas the P-gp-negative clones showed no resistance to drugs. Morphological and functional analysis showed that both the P-gp-positive and P-gp-negative clones were more differentiated than the parent cells in terms of enhanced activity of cellular alkaline phosphatase, an increase in well-organized actin stress fibres and enhanced osteogenic activity. Moreover, these subclones all displayed a decrease in malignant potential such as oncogenic activity, tumour growth rate and metastatic ability, regardless of their P-gp status. These results indicate that the observed osteoblastic differentiation and less aggressive phenotype in DOX-selected osteosarcoma cells may not only be explained by the direct effect of P-gp, and accordingly, consideration of the effect of DOX, as well as P-gp, appears to be important.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2000

Photodynamic inactivation with acridine orange on a multidrug-resistant mouse osteosarcoma cell line.

Overcoming multidrug resistance (MDR) is an urgent issue to improve the prognosis of osteosarcoma patients. In this study, we undertook to clarify the effect of photodynamic therapy (PDT) with acridine orange (AO) on the MDR mouse osteosarcoma (MOS / ADR1) cell line, by comparing the outcome with the effect on a chemosensitive osteosarcoma (MOS) cell line. Cultured cells of MOS and MOS / ADR1 cell lines were exposed to AO at various concentrations for various times, followed by long- or short-term (10 or 1 min) illumination with blue light (466.5 nm) for excitation. Living cells were counted by means of the trypan blue exclusion test. The results showed that AO rapidly bound to DNA, RNA and lysosomes of living MOS and MOS / ADR1 cells and also that most tumor cells in both cell lines died rapidly (viability ratio to untreated cells: 1/1000) within 48 h under conditions of continuous or 15-min flash exposure to AO at concentrations above 1.0 microg/ml plus 10-min illumination with blue light. Even after flash exposure to AO at concentrations above 1.0 microg/ml plus 1-min illumination, the viability of MOS/ADR1 cells decreased to a viability ratio of less than 1/ 1000 within 72 h. Based on these results, we concluded that AO with photo-excitation has a strong cytocidal effect, not only on chemosensitive mouse osteosarcoma cells, but also on MDR mouse osteosarcoma cells. These results suggested that photodynamic therapy with AO may be a new approach to treating MDR human osteosarcomas.

Acridine Orange↗

PubMed2000

Total tumor cell elimination with minimum damage to normal tissues in musculoskeletal sarcomas following photodynamic therapy with acridine orange.

Acridine orange (AO) has unique biological actions enabling tumor visualization (fluorovisualization) and a strong cytocidal effect (photodynamic therapy: AO-PDT) under illumination with blue light. Accordingly, in this study, we attempted to develop a new surgical technique for total tumor cell elimination using these photodynamic reactions with AO in a mouse osteosarcoma model. The results showed that local tumor recurrence was significantly inhibited (23%) in the group treated with curettage under fluorovisualization and AO-PDT, compared to that (80%) in the control group treated with curettage alone under ordinary light. Therefore, we concluded that the combination of curettage under fluorovisualization and AO-PDT may be useful for total tumor cell elimination with minimum damage to normal tissue in musculoskeletal sarcomas.

Acridine Orange↗

PubMed2000

Spatial heterogeneity in refractoriness as a proarrhythmic substrate: theoretical evaluation by numerical simulation.

Spatial heterogeneity in the refractoriness of the ventricular myocardium due to a regionally prolonged refractory period has often been observed in patients with cardiovascular disease as the substrate for functional reentrant tachyarrhythmias. The present study sought to determine how functional reentrant activity could occur due to the spatial heterogeneity, using numerical simulation. Spatial heterogeneity in the refractoriness was introduced into a two-dimensional array by the regionally prolonged refractory period expressed as a square cluster. Double stimulation, conducted from a single source, was introduced into 4 types of matrices, which differed in their level of spatial heterogeneity. A pseudoelectrocardiogram was calculated from these matrices. Spiral waves were initiated in all the matrices except for the lowest heterogeneous matrix. A vulnerable window of the coupling interval, which induced spiral waves, was observed and was wider in proportion to the level of the heterogeneity. A higher level of heterogeneity and more limited range of coupling intervals were required to sustain the spiral waves. Furthermore, in the pseudoelectrocardiogram, sustained spiral waves exhibited a waveform like that in torsades de pointes (TdP) and their transformation into ventricular fibrillation (VF). Spatial heterogeneity in refractoriness due to a regionally prolonged refractory period could be a substrate for functional reentrant tachyarrhythmias, possibly including TdP and VF.

Cardiovascular Diseases↗

PubMed2000

Intrinsic resistance to chemotherapeutic agents in murine osteosarcoma cells.

BACKGROUND: There are two general categories of drug resistance: acquired and intrinsic. The mechanisms involved in acquired drug resistance have been extensively studied, and several mechanisms have been described. However, the mechanisms responsible for intrinsic drug resistance have not been elucidated, to our knowledge. The purpose of the present study was to investigate the cytological and biochemical differences between acquired and intrinsic drug resistance in osteosarcoma cells. METHODS: We previously isolated a clonal cell line (MOS/ADR1) to study acquired resistance in osteosarcoma by exposure of parental murine osteosarcoma cells (MOS) to doxorubicin. In the present study, we cloned a new, intrinsically resistant cell line (MOS/IR1) by single-cell culture of MOS cells and we investigated the differences in cell phenotype and the mechanisms of resistance in both of these resistant clones. RESULTS: The MOS/ADR1 and MOS/IR1 cells were sevenfold and fivefold more resistant to doxorubicin than the parental murine osteosarcoma cells. Morphologically, the MOS/ADR1 cell line was composed of polygonal cells, whereas the MOS/IR1 cell line consisted of plump spindle cells with long cytoplasmic processes. The MOS/IR1 cells showed a much lower level of alkaline phosphatase activity than did the MOS/ ADR1 and MOS cells. There were no substantial differences in the cellular DNA content or the doubling time among these three lines. Overexpression of the P-glycoprotein involved in the function of an energy-dependent drug-efflux pump was detected in the MOS/ADR1 cells but not in the MOS/ IR1 cells. After the cells were incubated with doxorubicin for one hour, the two resistant lines had less accumulation of the drug than did the parent line (p < 0.05). The addition of a P-glycoprotein antagonist, verapamil, or the depletion of cellular adenosine triphosphate resulted in a marked increase in the accumulation of doxorubicin in the MOS/ADR1 cells (p < 0.05) but not in the MOS/ IR1 cells. The MOS/ADR1 cells were found to exhibit cross-resistance only to substrates for P-glycoprotein (such as doxorubicin, vincristine, and etoposide), whereas the MOS/IR1 cells were resistant to all of the drugs studied (including cisplatin and methotrexate). The degree of drug resistance in the MOS/IR1 cells was found to be associated with the molecular weight of the drugs (p < 0.05). Permeabilization of the plasma membrane by saponin increased both the accumulation of doxorubicin (p < 0.05) and the cytotoxic activity of this drug in all lines, but the effects were most pronounced in the MOS/IR1 cells. CONCLUSIONS: Taken together, this data suggests that reduced drug accumulation in the MOS/IR1 cells may be due to the effect of decreased permeability of the plasma membrane on the transport of drugs from the extracellular environment into the cytosol of the cell and that this may be the mechanism responsible for intrinsic resistance to multiple drugs in the MOS/IR1 cell line. CLINICAL RELEVANCE: Current drug treatment for human osteosarcoma may include multiple chemotherapeutic agents, such as doxorubicin, cisplatin, and methotrexate. These drugs exhibit different cytotoxic actions and, thus, the mechanisms of resistance to individual drugs vary. Clinical resistance to multidrug chemotherapy may be observed in tumors that recur after repetitive chemotherapy and in previously untreated tumors. In the former group, a tumor cell may express multidrug resistance by combining several different mechanisms due to its exposure to various drugs. In the latter group, however, this is not likely. Decreased intracellular drug accumulation due to reduced permeability of the plasma membrane, found in the MOS/IR1 cells, is one possible mechanism and may explain the intrinsic resistance to multidrug chemotherapy for the treatment of osteosarcoma. Further study regarding the resistance mechanism in the MOS/IR1 cells may help to overcome the intrinsic drug resistance in oste

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

Prognostic value of DNA ploidy response to chemotherapy in human osteosarcomas.

We analyzed the DNA ploidy alterations after preoperative chemotherapy in 30 patients with non-metastatic osteosarcomas of the extremities. All of the patients received intensive chemotherapy with doxorubicin, cisplatin and methotrexate as well as wide tumor resection. DNA ploidy was determined by DNA cytofluorometry using isolated and smeared cells from biopsied and resected tumors after preoperative chemotherapy. The results showed that 12 diploid and nine non-diploid osteosarcomas did not change their ploidy pattern, but nine non-diploid tumors changed to a diploid pattern with the disappearance of the aneuploid cells. The nine patients with altered ploidy tumors had a better histologic response to chemotherapy and a better prognosis than the patients with non-altered tumors especially diploid tumors (P = 0.0138). Therefore, we conclude that a decrease in aneuploid cells after chemotherapy is closely correlated with a good prognosis in half of the cases of aneuploid osteosarcoma. These results also suggest that aneuploid cells are more chemosensitive than diploid cells in human osteosarcomas.

Adolescent↗

PubMed1999

Relationship between chromosomal aberrations by fluorescence in situ hybridization and DNA ploidy by cytofluorometry in osteosarcoma.

An analysis of the chromosomal aberrations and DNA ploidy in the interphase nuclei of seven human osteosacomas was preformed by double-target fluorescence in situ hybridization (FISH) and DNA cytofluorometry. The FISH study of the numerical aberrations in chromosomes 1 and 17 or the structural aberrations in chromosome arm 1p or 17p was carried out by using four locus specific DNA markers, with one pair consisting of 1q12 and 1p36 and the other pair consisting of the 17 cemtromere and 17p13.3. There was no significant differences in the percentage of deletions in chromosome 1 and 17 between osteosarcomas and normal tissues. However, all seven tumors studied had extra copies. Cells with more than three probe signals were regarded as having chromosome polysomy. The percentage of polysomy of chromosome 1 was 20.0-64.0%, and chromosome 17 was 28.0-60.0%. The DNA ploidy patterns of hyperdiploid cells showing a greater DNA content than diploid cells were obtained by DNA cytoflurometry. Five of the seven tumors were non-diploid, and the remaining two were diploid. The percentage of polysomy was correlated with the percentage of hyperdiploid cells in each tumor. Thus, these findings indicated that the DNA ploidy changes were closely correlated with aberrations in the chromosome copy number in osteosarcomas.

Adolescent↗

PubMed1999

Response of DNA ploidy to chemotherapy in primary and metastatic lesions in human osteosarcomas.

Primary and pulmonary metastatic and pulmonary metastatic tumors (two synchronous and seven metachronous metastases) in nine patients with osteosarcomas were studied by DNA cytofluorometry. All patients were treated with both pre and postoperative chemotherapy. The results showed that all five diploid osteosarcomas and three of the four aneuploid tumors did not markedly change their ploidy pattern after preoperative chemotherapy, and had almost the same ploidy patterns as the pulmonary metastatic lesions. Those eight tumors showed poor histologic response and chemoresistance by the doxorubicin binding assay. Only one aneuploid osteosarcoma showing good histologic response and chemosensitivity changed its ploidy pattern to diploid, with the disappearance of aneuploid tumor cells and its synchronous pulmonary metastatic tumor also showed conversion to a diploid pattern with massive tumor necrosis. It is evident that those tumors showing no change in their ploidy pattern after chemotherapy were resistant to the chemotherapy. Therefore, we conclude that regardless of whether the pulmonary metastatic tumors were synchronous or metachronous, they showed the same change in their ploidy pattern as well as their chemosensitivity as the primary human osteosarcoma from which they were derived.

Adolescent↗

PubMed1999

Relationship between P-glycoprotein positivity, doxorubicin binding ability and histologic response to chemotherapy in osteosarcomas.

We previously reported that the doxorubicin binding ability detected by the doxorubicin (adriamycin) binding assay was closely correlated with the chemosensitivity of human osteosarcomas. In this study, we undertook to clarify the relationship between P-glycoprotein positivity (%PPG) and doxorubicin binding ability (%DB) in human osteosarcomas in order to determine which is a more sensitive index of histologic response to chemotherapy. Ten primary osteosarcomas were analyzed by the doxorubicin binding assay and by immunofluorescence to detect cellular P-glycoprotein positivity. Three good responders to chemotherapy containing doxorubicin showed a %DB greater than 90% (average: 96.43%), whereas the seven poor responders had values less than 80% (average: 35.31%). The difference between the two groups was statistically significant (P = 0.0167). However, the average %PPG of the three good responders was 6.73%, whereas the %PPG of the seven poor responders was 14.27%. There was no significant difference in %PPG between the two groups (P = 0.3051). No negative correlation between the %DB and the %PPG of all osteosarcomas (r = 0.536, P = 0.1104) was found, although there was a trend that those tumors with a high %PPG showed a low %DB. These results suggest that osteosarcomas showing a low %DB and %PPG with poor response to chemotherapy, may have multidrug resistance mechanisms other than P-glycoprotein. Therefore, we conclude that doxorubicin binding ability, which reflects all of the doxorubicin-resistant mechanisms, was more sensitive than P-glycoprotein positivity in predicting the chemosensitivity of human osteosarcoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

Prognostic significance of DNA ploidy pattern in osteosarcomas in association with chemotherapy.

In this study, we analysed the DNA ploidy of osteosarcomas at biopsy and attempted to clarify the relationship between DNA ploidy pattern and prognosis. Thirty patients with non-metastatic osteosarcoma of an extremity were studied. All underwent intensive chemotherapy with doxorubicin, cisplatin and methotrexate, in addition to wide tumor resection. DNA ploidy was detected by DNA cytofluorometry, using isolated and smeared cells of biopsied tumor tissue. Twelve tumors showed a diploid ploidy pattern and 18 showed a non-diploid pattern such as aneuploidy (15 tumors) and euploid-polyploidy (3 tumors). The event-free survival rate at 9 years was 63.5% in non-diploid osteosarcoma patients and 13.3% in diploid osteosarcoma patients. There was a statistically significant difference between the two groups (P = 0.0278). These results lead us to conclude that a non-diploid osteosarcoma may be more sensitive to chemotherapy than a diploid tumor.

Adolescent↗

PubMed1999

Cytofluorometric DNA ploidy analysis in giant cell tumor of bone: histologic and prognostic value.

DNA ploidy analysis by DNA cytofluorometry was performed on 41 tumors obtained from 37 patients with primary giant cell tumor of bone (GCT). Histologically, 26 of the tumors from primary or recurrent lesions were evaluated as grade I, and 13 tumors as grade II. Among the 33 primary GCT patients, 4 patients had local recurrence or pulmonary metastasis. The DNA ploidy pattern and the percentage of hyperdiploid cells showing a greater DNA content than diploid cells, were obtained from DNA cytofluorometry. All of the 33 primary tumors were diploid. Of 6 recurrent tumors, 4 were diploid and 2 were euploid-polyploid. One of the two pulmonary metastatic tumors was diploid, but another that demonstrated a malignant transformation to malignant fibrous histiocytoma was aneuploid. The percentage of hyperdiploid cells was significantly different between primary and recurrent tumors (P = 0.0188) and between grade I and grade II tumors (P = 0.0052), while there was no difference between primary tumors in the cases that recurred or metastasized and those that did not. Thus, these data indicate that cell proliferative activity is closely correlated with biological aggressiveness and histological grading, although DNA ploidy is not useful for predicting prognosis.

Adolescent↗