Biomedical subjects

M Kuroda

Publications and source records attributed to M Kuroda.

624 records · Page 35Linked to original sources

PubMedDate not supplied

Effects of amiloride derivatives on the thermosensitivity of an adriamycin-resistant strain of Ehrlich ascites tumor cells.

We investigated the effects of amiloride and its derivative MH-12-43 on the thermosensitivity of adriamycin-resistant cells. Effects of hyperthermia at 42 degrees C were enhanced by 0.5 mM amiloride and 0.05 mM MH-12-43, which resulted in no decrease in survival rate by the treatment at 37 degrees C for 120 min. Therefore, the combination of hyperthermia and amiloride derivatives was effective in the adriamycin-resistant cells as well as wild type cells. Further, since the survival rates by the treatment with 0.05 mM MH-12-43 were markedly lower than those with 0.5 mM amiloride from hyperthermia at 42 degrees C, MH-12-43 might be more effective than amiloride.

Amiloride↗

PubMedDate not supplied

Sensitivity of anticancer drugs in NIH3T3' cells transfected with oncogenes accompanied by pSV2neo vector.

NIH3T3 cells and NIH3T3 cell lines, which were transfected with several oncogenes accompanied by pSV2neo vector, were observed for their survival rate when treated with commonly used anticancer drugs. The survival rates in the cell line transfected with the pSV2neo vector only did not differ significantly from that of parental NIH3T3 cells against bleomycin, nimustine and adriamycin, but it was significantly more resistant to cisplatin and more sensitive to mitomycin C. Therefore, the survival rate in each transfectant was compared with that in the pSV2neo transfectant. The Val-12, v-Ha-ras, v-int-2, v-erbB or v-abl transfectants accompanied by pSV2neo vector were significantly more sensitive to cisplatin than transfection with pSV2neo vector only. The Val-12, v-Ha-ras, v-int-2 and v-abl transfectants were significantly more sensitive, and the v-erbB transfectant more resistant to bleomycin than the pSV2neo transfectant. The v-int-2, v-erbB, frg, v-raf and v-myc transfectants were more sensitive, and the v-Ha-ras transfectant more resistant to nimustine than the pSV2neo transfectant. The N-ras, v-Ha-ras, v-sis, v-int, v-abl and v-myc transfectants were significantly more sensitive to adriamycin than the pSV2neo transfectant. The v-sis and v-int-2 transfectants were more sensitive, and the c-Ki-ras, Val-12, v-erbB and the v-src transfectants more resistant to mitomycin C than the pSV2neo transfectant. Thus there was no relationship between the drug sensitivity and the location of oncogenes, but the transfection was associated with either increased or decreased sensitivity to a number of commonly used anticancer drugs. Therefore, it may be important to take into consideration or overexpression of oncogenes in cancer chemotherapy.

3T3 Cells↗

PubMedDate not supplied

Effect of cepharanthin and hyperthermia on the intracellular accumulation of adriamycin in the NIH3T3 cell lines transfected with oncogenes accompanied with pSV2neo vector.

The influence of several oncogenes on drug resistance has recently been show by transfection studies. Therefore, we investigated the influence of transfection on adriamycin (ADR) in cell line transfected with several oncogenes accompanied with pSV2neo vector. There were differences in both the intracellular accumulation of ADR and its sensitivity among the transfectants used in this study. There was a good correlation with the intracellular accumulation of ADR and its sensitivity (r = 0.76, P = 0.002). Further, there were no differences in the ADR efflux among the ras-family transfectants. Therefore, the changes in ADR sensitivity may be due to changes in ADR influx. On the other hand, the ADR accumulation showed an increase of 1.14-1.29 fold by the treatment of 10 micrograms/ml CEP. Moreover, the ADR accumulation showed an increase of 1.29-3.11 fold by hyperthermia at 42 degrees C. There was no significant difference in the ADR accumulation at 42 degrees C among the transfectants, suggesting that the influence on the ADR accumulation may be counteracted by hypethermia at 42 degrees C.

3T3 Cells↗

PubMedDate not supplied

FK506 completely inhibits adriamycin efflux in the adriamycin-resistant strain of Ehrlich ascites tumor cells.

Adriamycin (ADR) is frequently used in the clinical treatment of cancer. ADR resistance is one of the most serious problems in cancer chemotherapy. Several factors have been demonstrated to be related to ADR resistance. Among these factors, the influx of ADR into cells and the efflux of ADR out of cells are important aspects of its effectiveness. In this study, we investigated the influence of FK506 on the ADR accumulation and retention in the ADR-resistant strain of Ehrlich tumor cells. The ADR accumulation in the ADR--resistant strain was about 40% of that of wild EAT cells. The addition of 50 muM FK506 inhibited the efflux of ADR completely. ADR accumulation with the addition of 50 muM FK-506 to the ADR-resistant strain was about 80% of that found in the wild strain. Thus, it was suggested that the increase in ADR accumulation by the ADR resistant strain by about 40%, when 50 muM FK-506 was added might be due to complete inhibition of ADR efflux by P-glycoprotein, that the decrease of about 20% in ADR accumulation of the ADR-resistant strain compared to that in parent cells might be caused by problems with ADR influx. Therefore, it is necessary that the mechanisms which cause the decrease of ADR influx in the ADR -resistant strain be clarified.

Animals↗

PubMedDate not supplied

Influence of cell membrane potential, and selectivity of the Na+/H+ exchanger and Cl-/HCO3- exchanger on the intracellular accumulation of adriamycin.

Intracellular accumulation of adriamycin (ADR) has been reported to be influenced by cell membrane potential. We first evaluated intracellular accumulation of ADR and 3,3'-(di-n-hexyl)-2,2'-oxacarbocyanine iodide (NK-2280), an indicator of cell membrane potential, and found a good correlation between ADR and NK-2280 intracellular accumulation in several cell lines. This suggests that ADR accumulation may be influenced by cell membrane potential or the mechanisms of NK-2280 accumulation may be similar to those of ADR accumulation. Next, we observed the influence of the NA+/H+ exchanger and Cl-/HCO3- exchanger on the intracellular accumulation of ADR and NK-2280, and found that ADR accumulation decreased with increasing concentrations of 3,5-diamino-6-chloro-N-(diaminomethylene)pyrazinecarboxamide (amiloride), an inhibitor of the Na+/H+ exchanger, and 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS), an inhibitor of the Cl-/HCO3- exchanger, however, NK-2280 accumulation was increased by amiloride, and decreased by DIDS. The increased accumulation of NK-2280 induced by amiloride may be due to the increased cell membrane potential caused by the inhibition of H+ ion efflux and NA+ ion influx due to the inhibition of the Na+/H+ exchanger. The decreased accumulation of NK-2280 may be also due to the decreased cell membrane potential caused by the inhibition of Cl- ion efflux due to the inhibition of the Cl-/HCO3- exchanger by DIDS. However, the decreased rate caused by DIDS was greater than the increased rate caused by amiloride. Therefore, it is suggested that the decreased accumulation of NK-2280 by DIDS may be influenced by other factors apart from cell membrane potential. These results suggest that the Cl-/HCO3- exchanger may be related to both ADR accumulation, and NK-2280 accumulation, and that the Na+/H+ exchanger may be related to ADR accumulation, but not NK-2280. This suggests that the Cl-/HCO3- exchanger is of low selectivity.

3T3 Cells↗

PubMedDate not supplied

Anatomic considerations for sciatic nerve block in the popliteal fossa through the lateral approach.

BACKGROUND AND OBJECTIVES: The disadvantage of the classic posterior approach to block of the sciatic nerve at the knee level (popliteal nerve block [PNB]) is the need to position a patient in the prone position for performance of the block. In this study on cadavers, a lateral approach to the popliteal nerve in the supine position was investigated, and some anatomic considerations of relevance to popliteal nerve block were addressed. METHODS: In 19 cadaver right legs, the lateral approach to PNB was simulated with a needle, introduced in the groove between the biceps femoris and vastus lateralis muscles 7 cm above the knee, at either 30 degrees or 60 degrees relative to the horizontal plane, and 1 mL of dye solution was injected through the needle. After dissection of the popliteal fossa, the position of the solidified bolus of dye in relation to the popliteal nerve was determined. Additionally, the dye was injected into the popliteal nerve sheath, and the spread of the dye and continuity of the sheaths were determined. RESULTS: In 10 legs, the lateral approach was attempted at a 30 degrees angle and in 9 legs at a 60 degrees angle. The solidified injectates at 30 degrees were closely distributed anterolaterally to the nerve, while injectates at 60 degrees tended to be further from the nerve and scattered along its posterolateral aspect (P = .02). The dye injected into the nerve sheaths traveled 5 to 10 cm within the sheath, surrounding both main divisions of the popliteal nerve, the tibial and the common peroneal nerve. CONCLUSION: A lateral approach to the popliteal nerve with insertion of the needle at a 30 degrees angle relative to the horizontal plane results in predictable approximation of the needle tip to the popliteal nerve. The results also suggest the existence of a continuous neural sheath encompassing the popliteal nerve and its main branches. This may have clinical implications similar to those in perivascular neuronal block.

Dissection↗

PubMedDate not supplied

Thermosensitivity and thermotolerance in the adriamycin-resistant strain of Ehrlich ascites tumor cells.

The acquisition of resistance to anticancer drugs is an important problem in cancer chemotherapy. Ehrlich ascites tumor cells (wild type EAT cells) were grown in a medium containing 1 microgram/ml adriamycin (ADR) (ADR-resistant strain) and the cells that proliferated were established in our laboratory. Intracellular ADR accumulation and the killing effect of ADR in the ADR-resistant strain were markedly reduced compared with those of the wild type EAT cells. In this study, we initially observed thermosensitivity in both strains and found no difference in the thermosensitivity. These findings demonstrated that hyperthermic treatment was effective in the ADR-resistant strain as well as in the wild type EAT cells. On the other hand, thermotolerance is an important problem in the hyperthermic treatment of cancer. We next observed the thermotolerance of both strains and found that the thermotolerance in the ADR-resistant strain was greater than that in the wild type EAT cells, but the thermotolerance was almost restored within 24 hours. Furthermore, we investigated the influence of thermotolerance on the intracellular accumulation and killing effects of ADR in the wild type EAT cells. There was no difference in the intracellular ADR accumulation and the killing effect of ADR between non-thermoresistant cells and thermoresistant cells. These results suggested that hyperthermia was effective in the ADR-resistant cells either alone or combination with ADR.

Animals↗

PubMedDate not supplied

Influence of cepharanthin on the intracellular accumulation of adriamycin in normal liver cells and spleen cells of mice in vitro and in vivo.

Cepharanthin enhances the cytotoxicity of adriamycin by inhibiting its efflux incorporated into cancer cells. Therefore, it may also enhance accumulation of adriamycin, and then enhance toxicity by adriamycin in normal cells as well as in cancer cells. In this study, we first examined influence of cepharanthin on the accumulation of adriamycin in normal liver cells or spleen cells in vitro and in vivo. Cepharanthin lowered the accumulation of adriamycin in liver cells, in both in vitro and in vivo. In spleen cells, it enhanced adriamycin accumulation slightly in vitro, but did not affect that in vivo. Further, cepharanthin lowered the amount of adriamycin in plasma. This suggests that decreased levels of adriamycin in plasma may be one of factors in the decrease of adriamycin accumulation in liver cells. On the other hand, cepharanthin enhanced the NK 2280 accumulation used for an indicator of cell membrane potential for 60-100 minutes in liver cells, but did not change that in spleen cells. These suggest that the cell membrane potential may not affect the adriamycin accumulation in both cells since adriamycin accumulation increases with increasing accumulation of NK-2280. Moreover, no change in adriamycin efflux of liver cells was demonstrated by the treatment of cepharanthin. This indicates that the decrease in adriamycin accumulation in liver cells may not be due to the inhibition of adriamycin efflux. In conclusion, cepharanthin enhances adriamycin accumulation in cancer cells, but lowers its accumulation in normal liver cells and does not affect that in spleen cells. Therefore, cepharanthin may be useful in cancer chemotherapy.

Alkaloids↗

PubMedDate not supplied

Cervical carcinoma: dynamic MR imaging with a turbo-FLASH technique.

The purpose of this study was to evaluate the characteristic findings of cervical carcinoma in dynamic MR imaging with a turbo-FLASH technique and to investigate the cause of the hyperintense rim surrounding the tumor on dynamic MR images by comparing them with the pathological findings in the resected specimens. Sixty consecutive patients with cervical carcinoma were included in this study. Dynamic MR imaging was performed with the rapid administration of Gd-DTPA using the turbo-FLASH technique. After dynamic MR imaging, T1-weighted spin echo (SE) images were obtained. Dynamic patterns of the lesions were investigated from images acquired in the early and late phases of dynamic MR imaging. The causes of the hyperintense rim were investigated by comparing dynamic MR images with the pathological findings. Most of the cervical carcinomas showed higher signal intensity than normal cervical stroma in the early phase of dynamic MR imaging. The pathological findings of the hyperintense rim on dynamic MR images differed according to the time of appearance of the hyperintense rim. Dynamic MR imaging with the turbo-FLASH technique, which shows high contrast between the lesion and normal cervical stroma, should be performed before obtaining contrast-enhanced T1-weighted SE images in patients with cervical carcinoma.

Adult↗

PubMedDate not supplied

Influence of extracellular ion concentration on the intracellular accumulation of adriamycin.

The cytotoxic action of adriamycin is influenced by its intracellular accumulation. Therefore, it is important to clarify the mechanisms of adriamycin influx and efflux. In the present study, the influence of the extracellular KCl and Ca2+ concentration, the extracellular pH and the presence of NaHC03 on the ADR accumulation was investigated in order to study the mechanisms in ADR accumulation influenced by ions. The extracellular KCl concentration did not affect the intracellular ADR accumulation. This suggests the cell membrane potential does not affect the ADR accumulation since it is influenced by the KCl concentration. The intracellular intensity of fluorescence of Fluo3, an indicator of Ca2+, increased between 0 and 20 mM of the extracellular concentration of Ca2+ ion. However, the ADR accumulation did not change between 0 and 20 mM of the extracellular concentration of Ca2+. This indicates that the extracellular concentration of Ca2+ does not affect the ADR accumulation under physiological conditions since 20 mM of Ca2+ is beyond normal physiological conditions. Further, the intracellular fluorescence of Fluo3 decreased as increasing the extracellular pH. In contrast, the ADR accumulation increased as increasing the extracellular pH. These suggest that the ADR accumulation increases as decreasing the intracellular Ca2+ as changing the extracellular pH. In wild type strain, the ADR accumulation did not change by the extracellular pH in the absence of NaHCO3, but increased as increasing the extracellular pH in the presence of NaHCO3. This suggests that the ADR accumulation in the wild type strain is influenced by NaHCO3 but the extracellular pH. In the ADR-resistant strain, the ADR accumulation decreased as increasing the extracellular pH regardless of NaHCO3. However, the accumulation of ADR increased as increasing the extracellular pH when the adjustment of pH was carried out with 1N HCl. This suggests that Cl- may play an important role in the ADR influx in the ADR-resistant strain.

Aniline Compounds↗

PubMedDate not supplied

Influence of cepharanthin and hyperthermia on the intracellular accumulation of adriamycin and Fluo3, an indicator of Ca2+.

In the present study, the mechanism involved in the enhancement of adriamycin (ADR) accumulation by cepharanthin (CEP) and hyperthermia were examined. The accumulation of ADR and Fluo3 (an indicator of Ca2+) was increased by treatment with CEP. This suggests that ADR accumulation may increase due to increased influx of Ca2+. The ADR accumulation increased with increasing the KCl concentration in the presence of CEP when the KCl concentration was over 200 mM. This demonstrates that ADR accumulation increases with treatment with CEP and increasing the KCl concentration after the cell membrane potential reaches 0. ADR accumulation did not change with the extracellular pH in the absence of NaHCO3. CEP increased the ADR accumulation with increasing extracellular pH, regardless of NaHCO3. This suggests that CEP may affect the H+ flux, and consequently increase ADR accumulation regardless of NaHCO3. Further, it increased with increasing extracellular pH in the presence of NaHCO3, regardless of CEP. It is thought that the interaction between H+ and HCO3- may cause increased ADR accumulation. ADR accumulation was decreased by DIDS and amiloride at 37 degrees C. ADR accumulation in the presence of amiloride at 45 degrees C was increased compared with that at 37 degrees C. However, the accumulation combined with amiloride and hyperthermia was lower than with treatment with ADR only at 37 degrees C. This indicates that ADR accumulation is decreased by amiloride and increased by hyperthermia. ADR accumulation is further decreased by DIDS at 45 degrees C compared with 37 degrees C. This suggests that the H+ flux in hyperthermia is influenced by Cl-/HCO3- exchanger but not Na+/H+ exchanger.

Alkaloids↗

PubMedDate not supplied

MR appearance of endometrial carcinoma and mucinous cystadenoma in a postmenopausal patient treated with tamoxifen for breast cancer.

We present a case of endometrial carcinoma accompanied with mucinous cystadenoma in a 70-year-old postmenopausal woman treated with tamoxifen for breast cancer demonstrated by MR imaging. Tamoxifen therapy (20 mg/day) had been carried out for more than 11 years since the surgical procedure for the primary tumor. MR images showed a markedly enlarged uterus containing endometrial carcinoma, cystic atrophy of the endometrium, and a right adnexal mass with multicystic components of various signal intensities.

Aged↗