Hepatitis C transmission between spouses

To examine inter-spouse transmission as one of the potential routes of infection for hepatitis C virus (HCV), 121 patients with HCV-related chronic liver disease who tested positive for antibodies to HCV (anti-HCV) and their spouses were studied. Of these, 21 (17.4%) patients had spouses with anti-HCV. In 12 couples, the HCV genotype matched (type II: 10 couples, type III: two couples). The genotype differed in six couples. One patient was positive for anti-HCV, but negative for HCV-RNA, while the spouse was positive for both. The remaining two couples were only positive for anti-HCV. Genetic heterogeneity in the hypervariable region 1 of HCV was analysed in 11 couples with matched genotypes. In two couples, no mutation was recognized in the putative E2/NS1 genes using the heteroduplex method. The present study provides evidence to verify household transmission of HCV between patients and their spouses. These results suggest that inter-spouse transmission may be a potential route of transmission of HCV infection. However, other environmental factors (e.g. the duration of the marriage) cannot be ignored.

[Investigation for VP4 region of coxsackie virus A16 RNA sequence from hand-foot-mouth disease patients at eastern district of Shizuoka prefecture in 1995]

In 1995 an investigation was made for VP4 regions of coxsackie virus A16 (CA16) RNA sequence from hand-foot-mouth disease patients in eastern district of Shizuoka Prefecture. Subjects were seven patients who were diagnosed as hand-foot-mouth disease due to CA16 at the Ohashi Pediatric Clinic in Susono City. Throat swabs of patients were extracted to RNA. Extracted RNA were assayed by reverse transcription polymerase chain reaction that primers corresponded to VP4 resion of enteroviruses. PCR products were marked by dye-deoxy terminator methods and assayed by direct sequence methods. RNA sequences were classified into two types. Type 1 were three cases, and type 2 were four. The homology was 90.8% between type 1 and type 2. All cases of sixty-nine amino acids were the same as prototype strain. We concluded that the two type strains of CA16 were prevalented in eastern district of Shizuoka Prefecture in 1995. It was at the same time and was widely noted in the eastern district.

Increase of protein tyrosine phosphorylation in rat retina after ischemia-reperfusion injury

PURPOSE

This study was conducted to examine the effect of retinal ischemia-reperfusion injury on protein tyrosine phosphorylation, the production of angiogenic growth factors, and the activation of signal proteins in tyrosine kinase pathways.

METHODS

Ischemia-reperfusion injury was induced in rats by compression of the optic nerve for 2 hours. The rats were killed, and the retinas were collected at 0, 1, 6, 24, 48, 96, or 168 hours of reperfusion. Tyrosine phosphorylation of proteins in the retina was examined by Western blot analysis and immunohistochemistry. Angiogenic growth factors and their receptors, such as basic fibroblast growth factor (bFGF) and Flg, vascular endothelial growth factor (VEGF) and Flk-1, platelet-derived growth factor (PDGF)-B chain and PDGF-beta receptor, and five intracellular signal proteins (phosphatidylinositol 3-kinase [PI3K], phospholipase C gamma [PLC gamma], C-Src, SHC, and mitogen-activated protein kinase [MAPK]) were examined by Western blot analysis.

RESULTS

Protein tyrosine phosphorylation increased after ischemia-reperfusion injury, reaching a peak at 48 hours of reperfusion. Increased staining of tyrosine-phosphorylated proteins in the inner retina were evident on immunohistochemical examination. The amount of bFGF decreased after injury, but the amounts of VEGF and PDGF-B chain increased. Tyrosine phosphorylation of PLC gamma, SHC, and MAPK was increased at 48 hours of reperfusion, and tyrosine phosphorylation of PDGF-beta receptor and PI3K was increased at 168 hours of reperfusion.

CONCLUSIONS

Ischemia-reperfusion injury in the rat retina leads to activation of the tyrosine kinase pathway, increasing the amounts of angiogenic growth factors. The resultant activation of signal proteins PLC gamma, SHC, MAPK, PI3K, and PDGF-beta receptor may play an important role in ischemia-induced retinal changes such as cell proliferation.

Monoclonal antibody against lymphocyte function-associated antigen 1 inhibits the formation of primary biliary cirrhosis-like lesions induced by murine graft-versus-host reaction

Interaction between intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function-associated antigen 1 (LFA-1) might be involved in the pathogenesis of liver diseases. We investigated whether monoclonal antibodies (mAbs) against these two adhesion molecules could inhibit the formation of primary biliary cirrhosis (PBC)-like lesions in an animal model using graft-versus-host reaction (GVHR) with major histocompatibility complex class II disparity. PBC-like hepatic lesions such as cellular infiltration of portal area and nonsupprative destructive cholangitis (NSDC) were generated by injecting spleen T cells of C57BL/6 (B6) mice into (B6. C-H-2bm12 X B6) F1 mice. In the liver of these mice, increased number of LFA-1-positive cells and enhanced expression of ICAM-1 on sinusoidal endothelial cells and bile duct epithelial cells were observed immunohistochemically, when compared with F1 mice without GVHR. Hepatic lesions of these mAb-treated mice were almost completely inhibited in these mice compared with GVHR mice. Furthermore, we studied to determine which anti-LFA-1 mAb or anti-ICAM-1 mAb was essential to inhibit the hepatic lesions. Mice solely treated with anti-LFA-1 mAb showed significant inhibition of hepatic lesions, whereas treatment with anti-ICAM-1 mAb could not inhibit the lesions. Despite the inhibition of hepatic lesions, induction of GVHR and production of antimitochondrial antibodies were not impaired in mAb-treated mice. We conclude that LFA-1 mediates cell infiltration into the liver in this murine model of GVHR and suggest a possible therapeutic role of mAbs to this adhesion molecule in selective autoimmune liver diseases.

Monoclonal antibody against lymphocyte function-associated antigen 1 inhibits the formation of primary biliary cirrhosis-like lesions induced by murine graft-versus-host reaction

Interaction between intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function-associated antigen 1 (LFA-1) might be involved in the pathogenesis of liver diseases. We investigated whether monoclonal antibodies (mAbs) against these two adhesion molecules could inhibit the formation of primary biliary cirrhosis (PBC)-like lesions in an animal model using graft-versus-host reaction (GVHR) with major histocompatibility complex class II disparity. PBC-like hepatic lesions such as cellular infiltration of portal area and nonsupprative destructive cholangitis (NSDC) were generated by injecting spleen T cells of C57BL/6 (B6) mice into (B6. C-H-2bm12 X B6) F1 mice. In the liver of these mice, increased number of LFA-1-positive cells and enhanced expression of ICAM-1 on sinusoidal endothelial cells and bile duct epithelial cells were observed immunohistochemically, when compared with F1 mice without GVHR. Hepatic lesions of these mAb-treated mice were almost completely inhibited in these mice compared with GVHR mice. Furthermore, we studied to determine which anti-LFA-1 mAb or anti-ICAM-1 mAb was essential to inhibit the hepatic lesions. Mice solely treated with anti-LFA-1 mAb showed significant inhibition of hepatic lesions, whereas treatment with anti-ICAM-1 mAb could not inhibit the lesions. Despite the inhibition of hepatic lesions, induction of GVHR and production of antimitochondrial antibodies were not impaired in mAb-treated mice. We conclude that LFA-1 mediates cell infiltration into the liver in this murine model of GVHR and suggest a possible therapeutic role of mAbs to this adhesion molecule in selective autoimmune liver diseases.

99mTc tetrofosmin uptake in lung cancer. A case report

This case report describes a 71-year-old man with a lung tumor in the posterior inferior segment of the right lung, detected on a screening chest radiograph. The patient underwent myocardial imaging with 99mTc tetrofosmin and 201Tl, using single photon emission CT (SPECT), and the tumor showed intense focal uptake of the radiotracer. This observation supports the recent suggestion that 99mTc tetrofosmin may be useful for oncologic imaging of lung carcinoma, and further studies may be warranted.

Expandable metallic stents for tracheobronchial stenoses in esophageal cancer

BACKGROUND

Tracheobronchial stenosis in patients with esophageal cancer can be life threatening. Few reports have discussed use of expandable metallic stents for central airway stenoses in patients with esophageal cancer.

METHODS

Twelve patients with esophageal cancer underwent placement of expandable metallic stents for respiratory distress caused by tracheobronchial stricture. Single or double metallic stents were placed in the stenotic airways under fluoroscopic guidance. Improvement in respiratory symptoms and clinical outcome were assessed.

RESULTS

Most stenoses were located in the trachea or the left main bronchus. From one to four expandable metallic stents were placed in each stricture site, with immediate relief of respiratory symptoms in 8 patients. One patient with tracheomalacia in alive 3 years after stent placement and another is alive 6 months after stent insertion. The other 10 patients lived from 10 to 70 days (mean; survival, 35 days) after stent placement. Death was due to progression of disease.

CONCLUSIONS

Although metallic stents are useful for relieving respiratory distress in patients with advanced esophageal cancer, additional therapies should be considered.

Bidirectional transport of cholesterol between gallbladder epithelial cells and model bile

Lipids in hepatic bile may be modified by the gallbladder epithelium. The purpose of this study was to demonstrate a bidirectional exchange of cholesterol between biliary lipid carriers and gallbladder epithelial cells and to determine the factors regulating this cholesterol transfer. Gallbladder epithelial cells were cultured to confluent monolayers, their membranes were labeled with endogenously synthesized [14C]cholesterol, and the cells were incubated with model bile introduced into the apical membrane compartment. Similarly, model bile with different lipid composition containing [3H]cholesterol was incubated with the unlabeled monolayers. We found that cholesterol in the apical membrane bilayer of the epithelial cells exchanged readily with that in bile, but only in the presence of bile salts. The rate of exchange is dependent on the concentration and species of bile salts. The net gain of cholesterol (absorption) or net loss of cholesterol (cytotoxicity) exhibited by the epithelial cells was regulated by the thermodynamic stability of cholesterol and the detergent effect of mixed micelles in bile. It is also possible that the physicochemical composition of lipids in bile may modify the cellular function of the gallbladder epithelium.

Lack of rearranged Tpr-met mRNA expression in human gastric cancer cell lines and gastric mucosa and carcinoma

The met protooncogene was activated by a rearrangement involving the fusion of tpr (1q25) and met (7q21-31) gene sequence in a human osteosarcoma cell line (HOS) incubated in vitro with N-methyl-N-nitro-N-nitrosoguanidine (MNNG). We examined the expression of tpr-met mRNA by means of the reverse transcription-nested polymerase chain reaction (RT-nested PCR) in human two gastric cell lines (MKN-1 and MKN-45), T-cell acute lymphocytic leukemia cell line (MOLT-4), and in gastric tissue samples including normal mucosa, intestinal metaplasia and carcinoma from three surgical specimens. A DNA fragment of 88-bp was amplified in MKN-1 and MOLT-4, 96-bp in MKN-45 and of 58-bp in all nine tissue samples including gastric carcinomas. The amplified DNA sequences were not homologous with the rearranged tpr-met gene. Our study indicated that rearranged tpr-met mRNA is not expressed either in human gastric carcinoma cell lines or in gastric mucosa and carcinoma.

Bleeding from gastric antral vascular ectasia in marrow transplant patients

BACKGROUND

Gastric antral vascular ectasia (GAVE) leads to blood loss in the disorders of "watermelon stomach" and portal gastropathy, but is not a commonly recognized complication of marrow transplantation.

METHODS

GAVE was diagnosed when capillary ectasia, focal capillary thromboses, and fibromuscular hyperplasia were identified in antral mucosal biopsy specimens. Marrow transplant patients bleeding from GAVE were reviewed to ascertain common variables in their pretransplant, posttransplant, and bleeding course.

RESULTS

Six patients developed bleeding due to GAVE. The onset of bleeding was 18 to 94 days after transplant and required an average of 37 U of blood (range, 2 to 130 U). Two patients stopped bleeding after restoration of platelet counts. Two patients had surgical antral resections; both died of multiorgan failure after surgery. Two patients had successful endoscopic laser ablation of vascular lesions and survived. Factors possibly associated with GAVE included male gender, VOD of the liver, oral busulfan as part of the conditioning regimen, and growth factor use after transplant.

CONCLUSIONS

GAVE was a cause of gastric bleeding in six patients with marrow transplant patients. Restoration of platelet counts and endoscopic laser photocoagulation are the therapies of choice for ongoing bleeding in these patients.

Cosmetic reconstruction after mastoidectomy for the transpetrosal-presigmoid approach: technical note

OBJECTIVE

We describe the technique of cosmetic reconstruction after mastoidectomy in the transpetrosal-presigmoid approach for petroclival lesions.

TECHNIQUES

This technique involves raising a single temporo-occipital bone flap and cosmetic mastoidectomy, removing the mastoid bone fragments (by means of a rongeur instead of an air drill) for later reconstruction. Replacement of the bone fragments mixed with fibrin glue enables tamponade against the dura to be achieved without a fat graft.

RESULTS

Computed tomographic scans and plain cranial films taken a few years later showed successful reconstruction of the mastoid bone with a good appearance of the retromastoid area in seven patients who underwent this procedure. The only complication was infection in one patient from cerebrospinal fluid leakage from the wound.

CONCLUSION

We have developed a simple and easy technique of cosmetic reconstruction after the transpetrosal-presigmoid approach.

A new wound healing model of retinal pigment epithelial cells in sheet culture

PURPOSE

To evaluate some RPE cell functions, such as wound healing, in a preparation more similar to in situ conditions, we developed a method to obtain and culture retinal pigment epithelial (RPE) cells as a sheet. And we assessed the effects of fetal bovine serum (FBS) on the rate of RPE wound healing.

METHODS

We prepared RPE sheet cultures by incubating rat eyes in 0.1% proteinase K for 13 min, peeling away the neural retina-RPE complex, and then incubating the tissue for 1 h to promote spontaneous separation of the RPE sheet from the retina. After several days of incubation, the cultured sheets of RPE cells were examined by phase-contrast microscopy, scanning and transmission electron microscopy and immunocytochemistry. We made round defects 1 mm in diameter in cultured RPE sheets and estimated the rate of wound closure in media with different concentrations of FBS (0 to 10%).

RESULTS

The RPE cells cultured in sheets retained their in situ features, including microvilli, tight junctions and gap junctions, and the distribution of actin and cytokeratin filaments. A wound was noted to close with restoration of a polygonal configuration. The rate of wound closure depended on serum concentration in the culture medium; when supplemented with 10% fetal bovine serum, wound closure was complete in approximately 40 h.

CONCLUSIONS

The RPE sheet-culture technique we developed thus provides a suitable model for studying such RPE cell functions as wound healing or phagocytosis.

The superficial brachial flap

A new flap raised on the inner medial upper arm to the anterior forearm surface to cover soft-tissue defects has been described. The blood supply to this flap comes from the superficial brachial artery. The presence of this vessel permits safely transferring arm skin as on island or free flap. This vessel was present in 25% of our series of 64 angiographic investigations and 10 cadaver dissections. Some earlier reports confirm that this vessel averaged 22.8% finding. The superficial brachial flap has been used as a pedicled or free flap to cover various defects in 8 patients and the results have been excellent. There were no complications or loss of overlying skin. Furthermore, no functional impairment or sensory disturbance occurred. Raising this flap is a relatively simple procedure, as the superficial brachial artery runs superficially in the subcutaneous layer.

Surgical treatment for patients with pulmonary metastases after resection of primary colorectal carcinoma

BACKGROUND

The optimum treatment for patients with pulmonary metastases from colorectal carcinoma is still controversial.

METHODS

To evaluate the results of pulmonary resection in 22 patients with pulmonary metastases after resection of primary colorectal carcinoma, patients' characteristics were examined retrospectively. Eighteen patients had a solitary metastatic lesion and four had two lesions.

RESULTS

Postthoracotomy recurrence occurred in 17 of the 22 patients (77.3%), and showed no correlation with the type of pulmonary resection. In 11 patients with a solitary lesion of less than 3.0 cm in greatest dimension, the 3- and 5-year postthoracotomy survival rates (PTSR) were 71.6% and 36.8%, respectively. Six of these patients received two or more thoracotomies for pulmonary recurrence. The 3-year PTSR for seven patients with a solitary lesion greater than or equal to 3.0 cm was 19.0%, and for the four patients with two lesions, 25.0%. A significant difference was noted in the survival rate according to both number and size of the metastatic lesions (P < 0.05).

CONCLUSIONS

The number and size of metastatic lesions appear to be important prognostic determinants. Repeated thoracotomy can prolong survival for selected patients.

Does the cell wall skeleton from Bacille Calmette-Guérin directly induce interferon-gamma, independent of interleukin-12?

Interleukin-12 (IL-12), known to be a strong inducer of interferon-gamma (IFN-gamma), plays a vital role in activating the immune surveillance system against intracellular pathogens and malignant tumors. The authors have found that cancer patients showing marked IFN-gamma induction after inoculation with BCG-CWS (the cell wall skeleton from Bacille Calmette-Guérin) have a good prognosis. The present study was undertaken to determine whether the level of IL-12 is increased prior to, or along with, IFN-gamma induction in the serum of patients inoculated with BCG-CWS. Unexpectedly, we found no detectable amount of IL-12 in the serum throughout the entire time course. This suggests that a novel IFN-gamma inducing factor (IGIF) or another unknown IFN-gamma inducer may be working in place of IL-12 in the BCG-CWS system.

Evaluation of a new solution containing trehalose for twenty-hour canine lung preservation

We examined the efficacy of two new preservation solutions containing trehalose--an extracellular type (ET-K) of solution and an intracellular type (IT-K) of solution--in relation to that of Euro-Collins (EC) solution in 20-h canine lung preservation. Canine lungs were flushed with one of the three solutions (n = 5 for each solution) after pretreatment with PGE1 (20 micrograms/kg) and were stored for 20 h at 4 degrees C. The left lungs were transplanted and evaluated to 6 h post transplant. In the ET-K group, the arterial oxygen tension after reperfusion was significantly higher than in the IT-K and EC groups. The pulmonary vascular resistance, wet/dry weight ratio, and histological evaluation of each transplanted lung in the ET-K group were also better than in the IT-K and EC groups. This indicates that ET-K solution is useful for 20-h preservation of canine lung grafts.

Cytokine effects on phagocytosis of rod outer segments by retinal pigment epithelial cells of normal and dystrophic rats

PURPOSE

Phagocytosis of rod outer segments (ROS) is an important function of retinal pigment epithelial (RPE) cells. Since the details of the process are not fully known, we studied effects of cytokines produced by RPE and photoreceptor cells on phagocytosis of ROS by rat RPE cells.

METHODS

RPE cells were isolated and cultivated from two strains of rats: Sprague-Dawley (SD) rats with normal phagocytosis and Royal College of Surgeons (RCS) rats, which have genetic deficiencies in ROS phagocytosis. A double immunofluorescence staining technique was used to study the effects in vitro of several cytokines on phagocytosis of ROS.

RESULTS

We found that transforming growth factor beta-1 (TGF-beta 1) had dose-dependent effects on RPE cells of both strains of rat: at a concentration of 10 ng/ml, TGF-beta 1 significantly (p < 0.01) reduced total ROS (to 74% of control in SD rats and to 51% of control in RCS rats), reduced bound ROS (to 56% of control in SD rats and to 48% in RCS rats), and increased the ratio of ingested ROS to total ROS (to 140% in SD rats but not significantly in RCS rats). Treatment of medium with anti-TGF-beta 1 antibody before incubation of RPE cells of SD rats with TGF-beta 1 decreased the magnitude of these effects. The cytokine acidic fibroblast growth factor (aFGF, 10 ng/ml) affected RPE cells of SD rats only, decreasing ROS ingested to 56% of control and the ratio of ingested ROS to total ROS to 64% of control. We also examined effects of basic fibroblast growth factor and insulin-like growth factor. None of the cytokines tested increased ingestion of ROS by RPE cells of RCS rats.

CONCLUSIONS

Our results suggest that TGF-beta 1 and aFGF have roles in regulating ROS phagocytosis by normal and dystrophic RPE cells in the rat.

Relationship of HIV-1 envelope V2 and V3 sequences of the primary isolates to the viral phenotype

We examined the relationship between the amino acid sequences of the V2 and V3 regions of the envelope protein and the biological properties of ten human immunodeficiency virus type 1 (HIV-1) primary isolates. The infectivity, cytopathic effect (CPE), and syncytium forming activity of these primary isolates were tested against three T cell lines (CEM, MT2, and MOLT4/CL.8 cells), CD8-depleted peripheral blood mononuclear cells (PBMC), and primary monocyte-derived macrophages (MDM) from seronegative donors. In addition to the viral groups which had the syncytium inducing/T-cell line tropic (SI/TT) phenotype or non-syncytium inducing/non-T cell line tropic (NSI/NT) phenotype (including the NSI/macrophage tropic (NSI/MT) phenotype), there was a group of viruses that infected one or two T cell lines and PBMC but could not mediate syncytium formation. We therefore classified this group of viruses as a non-syncytium inducing/partial T-cell line tropic (NSI/pTT) virus. To investigate the relationship between these viral phenotypes and the sequence variability of the V2 and V3 regions of the envelope, we cloned the viral gene segment and sequenced the individual isolates. The sequence data suggested that the SI/TT type changes in the V3 sequence alone mediate a partial T cell line tropism and mild cytopathic effect and that an isolate became more virulent (SI/TT phenotype) if there were additional changes in the V2 or other regions. On the other hand, sequence changes in the V2 region alone could not mediate phenotypic changes but some additional changes in the other variable regions (for example, V3) might be required for the phenotypic changes in combination with changes in V2. These findings also suggested that amino acid changes in both the V2 and V3 region are required for the development of virulent variants of HIV-1 that outgrow during advanced stages of the disease.

Melanogenesis, biosynthetic phenotype of fibronectin and collagen, and migrating activity in cloned B16 mouse melanoma cells

Three clones, melanotic (M3), amelanotic (A4 and A7) cells were isolated from B16 F10 mouse melanoma cell line. These clones exhibited different biosynthetic activities of fibronectin and collagen: A4 clone showed relatively active synthesis of both collagen and fibronectin, and A7 clone exhibited most active fibronectin synthesis, whereas no significant synthesis of these molecules was observed in M3 clone. No significant difference in growth rate was observed in these three clones. Migrating activities measured by basement membrane matrix-coated dishes were greater in A7 clone than in A4 and M3 clones. Messenger RNA levels of collagen and fibronectin paralleled collagen and fibronectin synthesis in these clones whereas tyrosinase mRNA level was unaltered between melanotic (M3) and amelanotic (A4 and A7) cells. These results indicate that B16 melanoma cells have heterogeneous cell populations consisting of different biosynthetic and metastatic properties. These clones may provide good tools for studying the relationship between the phenotypes of melanogenesis biosynthesis of extracellular macromolecules and migrating activity of melanoma cells.

Human tumor rejection antigens MAGE

Characterization of the MAGE genes has facilitated a molecular approach to identification of the genes encoding tumor-rejection antigens expressed on human cancer cells. MAGE proteins are normal tissue antigens compartmentalized in testicular cells that play an important role in the early phase of spermatogenesis. MAGE-1, -2, -3, -4, and -6 genes are preferentially expressed in many different cancers at both the mRNA and protein levels. More than half of human cancers of various histologic type express at least one of these MAGE genes. Demethylation induces MAGE antigens in cells, suggesting that MAGE genes are important developmentally regulated genes under methylating control. Thus, genetic instability in cells causing loss of this methylating control could result in the preferential expression of MAGE genes in cancer cells. Therefore, MAGE gene products may be appropriate target molecules for development of new cancer vaccine.

[Studies on reversing effect of multidrug resistance by dipyridamole. I. modulation of epirubicin-induced effects on cell proliferation and cell cycle by dipyridamole]

Dipyridamole, a nucleoside membrane transport inhibitor, enhanced the cytotoxicity of epirubicin for mouse leukemia P388 cells by a factor of 1.8-fold and that for 30-fold doxorubicin-resistant sublines of P388 cells (P388/DOX) by a factor of 6.5-fold. This interaction was shown to be truly synergistic by DNA histogram and median effect analysis. The dipyridamole enhancement of the cytotoxicity of epirubioin was a dose-dependent effect; it was greatest when cells were exposed to dipyridamole before treatment with epirubicin. In cell cycle experiments, 1-5 microM dipyridamole increased the accumulation of G2 + M phase produced by the treatment with 0.5-1 microM epirubicin. Dipyridamole, however, did not appear to alter the patterns of DNA histogram in sensitive cells. These results suggest that the increase of the accumulation of G2 + M phase in resistant cells is an important factor for the interaction between epirubicin and dipyridamole.

[Studies on reversing effect of multidrug resistance by dipyridamole. II. Inhibition of epirubicin efflux from resistant cells by dipyridamole and its pharmacological effect]

We have previously reported that dipyridamole increases the cytotoxicity of epirubicin and alters the cell cycle in doxorubicin-resistant (P388/DOX) cells, increasing the accumulation of G2/M phase by blocking the cell cycle. In cultured cells, dipyridamole increased dose-dependently the intracellular accumulation of epirubicin in the resistant cells. Simultaneous exposure of the resistant cells to epirubicin and 100 microM dipyridamole resulted in a 4.2-fold increase in proportion to the control level of epirubicin after 60 min. Dipyridamole inhibited the enhanced efflux of epirubicin in doxorubicin-resistant cells. However, dipyridamole had no effect on both the influx and efflux of epirubicin in doxorubicin-sensitive cells. In mice, lethal and bone marrow toxicity induced by epirubicin were potentiated by administration of high-dose of dipyridamole. In addition, in vivo results also demonstrated that dipyridamole in combination with epirubicin produced a significant reversal of the in vivo antitumor activity of epirubicin in mice bearing P388/DOX cells. These data imply the enhancement effects of dipyridamole on the efficacy and toxicity of epirubicin.