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Biomedical subjects

A Asai

Publications and source records attributed to A Asai.

At least 127 records · Page 7Linked to original sources
PubMed1994

Radiation therapy combined with radiosensitizing agents for cerebral glioblastoma in adults.

We analyzed our treatment results of 71 operated patients with cerebral glioblastoma treated by conventional external radiation therapy (mean dose 60.2 Gy) combined with radiosensitizing agents. More than 50% reduction of tumor volume was obtained in 20 patients (28.2%). A response rate of at least 40% was obtained in patients treated with combined ACNU-vincristine-nicardipine, ACNU-5FU-hydroxyurea, or cisplatin alone. The combination of ACNU and vincristine with or without nicardipine resulted in significantly longer survival. The median survival in this group was 101.1 weeks and the two-year survival rate was 45.9%; these results were significantly better than those achieved with other ACNU combinations or other combinations without ACNU. In the analysis of survival, factors correlated to longer survival were a patient age of younger than 45 years, wide resection of the tumor, a good postoperative performance status (KS > or = 70%), a radiation dose of 68-72 Gy, small postoperative tumor remnants (< 20 cm3), no visible tumor after radiation therapy, and the administration of adjuvant chemotherapy. Maximum resection of the tumor and localized irradiation with a dose of 70 Gy combined with ACNU and vincristine appears to be the most effective treatment at present.

Adolescent↗
PubMed1994

Negative effects of wild-type p53 and s-Myc on cellular growth and tumorigenicity of glioma cells. Implication of the tumor suppressor genes for gene therapy.

Human (U251, U87, U343) and rat glioma cell lines (C6, 9L) were examined by the reverse transcriptase-polymerase chain reaction and subsequent nucleotide sequencing analysis to see whether they express wild type (wt)-p53 or mutated form (mut)-p53 messages. Results showed that U87, U343, and C6 cells expressed wt-p53 messages whereas U251 and 9L cells expressed mut-p53 messages. All these cell lines were transfected with wt-p53 cDNA or the s-myc gene linked to the mouse mammary tumor virus (MMTV) promoter. Of several G418-resistant clones obtained from each transfection, a few expressed the s-Myc or wt-p53 proteins. Independent of mutations in the intrinsic p53 gene, the cellular growth in vitro and tumorigenicity in nude mice of these clones were drastically suppressed, the extent of suppression being correlated with the expression level of the transfected gene. Flow-cytometric analysis demonstrated that both p53 and s-Myc arrested the cell cycle at the G1/S boundary. These data suggest that these genes having negative effects on tumor cell proliferation could be used in gene therapy of gliomas, which are caused by alteration of the p53 gene or by some other genetic change.

Animals↗
PubMed1994

Intra-operative radiation therapy for malignant brain tumors: rationale, method, and treatment results of cerebral glioblastomas.

In radiation therapy for malignant brain tumours, the dose of radiation that can be safely delivered to a tumour is limited by the radiation tolerance of the adjacent normal brain tissue. Among various radiation modalities to produce local tumour eradication without unacceptable complications, we chose a large, single irradiation dose during the operation (intra-operative radiation therapy, IORT). In contrast to X-ray or Cobalt-60 gamma ray irradiation, IORT with a high-energy electron beam delivered by the Shimadzu 20 MeV betatron provides acceptable dose homogeneity with rapid fall-off of the radiation dose beyond the treatment volume. Thus, IORT has the advantage of precise demarcation of the target volume, minimum damage to surrounding normal tissues, and a high absorbed target dose (15-25 Gy in 5-10 min). On the basis of our experience with 170 patients treated by IORT, we established the treatment indications and method in patients with malignant brain tumours. IORT with a dose of 15-25 Gy was delivered to widely resected tumours followed by external radiation therapy. No acute or subacute complications were observed. Treatment results of 30 patients with glioblastoma treated by IORT (mean 18.3 Gy) combined with external radiation therapy (mean 58.5 Gy) resulted in a median survival of 119 weeks and a 2-year survival rate of 61%.

Adolescent↗
PubMed1994

New treatment protocol by intra-operative radiation therapy for metastatic brain tumours.

In patients with brain metastasis from lung cancer, we have been able to control local recurrence in approximately 80% of cases. But many of them tend to show brain atrophy with mental deterioration developing a few months after whole brain radiation. To prevent brain atrophy, we have attempted treating patients, whose metastasis was diagnosed as single, by intra-operative radiotherapy (IOR) alone following surgical resection. Among 43 patients, 19 patients who had no metastases other than the brain metastases, were chosen as subjects for active treatment (surgical resection+IOR). Their 1-year survival rate was 75%. Fourteen out of 27 patients with brain metastases from lung cancer received active treatment and their 1-year survival rate was 74%. This result was not inferior to our result of 71 patients who received surgical resection and whole brain irradiation. When no preventive whole brain irradiation was performed, patients were observed every 8 weeks by CT scan in order to ascertain tumour recurrence limited to the treated site or appearance of any new metastatic lesion remote from the treated site. Among all 43 patients, local recurrence was recognized in 7 cases and remote recurrence was observed in 7 cases. Within 6 months, local and remote recurrence was found in 3 cases each. These results were almost the same as those for the usual therapy (surgery plus whole brain irradiation). If such a new lesion is detected, additional radiation can be performed with the possibility of achieving complete remission.

Adult↗
PubMed1994

Differential effect of duocarmycin A and its novel derivative DU-86 on DNA strand breaks in HeLa S3 cells.

Duocarmycin A (DUMA) and DU-86, a semisynthetic derivative of duocarmycins (DUMs) and a possible active form of KW-2189, both showed potent cell growth-inhibitory and cell-killing activities against human uterine cervix carcinoma HeLa S3 cells. Both drugs showed similar profiles of inhibition of macromolecular synthesis and influence on cell-cycle distribution. Namely, they inhibited [3H]thymidine uptake at lower concentrations than [3H]uridine or [3H]leucine uptake, suggesting that the inhibition of DNA synthesis is the primary site of their actions. Furthermore, they induced the accumulation of cells in early S phase. However, a significant difference was observed between these drugs in terms of DNA-fragmentation activity against HeLa S3 cells by using two independent methods, pulse-field gel electrophoresis and alkaline elution. DNA fragmentation was insignificant in the cells treated with DU-86, in contrast to the cells treated with DUMA. The analysis of DNA adducts in the cells revealed that DU-86 alkylated adenine quite selectively, while DUMA alkylated both adenine and guanine. These results suggest that the pyrrolidone ring of DUMA is responsible for its adduct formation with guanine and the subsequent DNA-fragmentation and inhibition of DNA synthesis, while DU-86 alkylated adenine and inhibited DNA synthesis through mechanisms other than DNA-fragmentation.

Adenine↗
PubMed1994

Prevention of delayed vasospasm by an endothelin ETA receptor antagonist, BQ-123: change of ETA receptor mRNA expression in a canine subarachnoid hemorrhage model.

The authors investigated the roles of endothelin (ET)-1 and the ETA receptor in the pathogenesis of delayed cerebral vasospasm following subarachnoid hemorrhage (SAH). A study was made of the preventive effect of a novel ETA receptor antagonist, BQ-123, on vasospasm and the expression of the ETA receptor messenger ribonucleic acid (mRNA) using a canine two-hemorrhage SAH model. Continuous intrathecal administration of BQ-123 (5 x 10(-6) mol/day) prevented narrowing of the basilar artery on Day 7 after SAH in 97.6% of cases in the study group versus 70.7% of cases in the control group (p < 0.05). While expression of the mRNA-coding ETA receptor was not detected in the control animals, it markedly increased on Day 3 after SAH and was also detected on Day 7. The results suggest that endothelin-1 and the ETA receptor participate in the pathogenesis of delayed cerebral vasospasm following SAH.

Animals↗
PubMed1994

Modulation of tumor immunogenicity of rat glioma cells by s-Myc expression: eradication of rat gliomas in vivo.

The Myc family proteins represented by c-Myc are thought to play a crucial role in cellular proliferation, differentiation, transformation, and apoptosis. In this study, we demonstrated the novel role for a Myc family protein in elicitation of immunogenic phenotypes in tumor cells. Injection of rat 9L or C6 glioma cells, together with the s-myc gene linked to the cytomegalovirus promoter, completely prevented formation of both brain tumors and s.c. tumors derived from the parental glioma cells. However, introduction of the s-myc gene had no inhibitory effect on development of B104-derived neuroblastoma. In addition, unlike the s-myc gene, injection of the c-myc or wild type p53 (wt-p53) gene together with glioma cells did not modulate the tumor immunogenicity and resulted in formation of gliomas in the animals. These findings suggest that s-Myc expression may stimulate the presentation of a tumor antigen common to 9L and C6 cells to T lymphocytes and augment the activity of the host immune system, resulting in prevention of glioma formation in vivo. This success in tumor eradication indicates the possibility of application of the s-myc gene for gene therapy of human brain tumors.

Animals↗
PubMed1994

The s-Myc protein having the ability to induce apoptosis is selectively expressed in rat embryo chondrocytes.

Gene transfection experiments demonstrated that over-expression of the s-myc gene under the control of a human metallothionein promoter induced apoptosis in cells such as rat and human glioma cells. In contrast to c-Myc-mediated apoptosis requiring withdrawal of serum growth factors, s-myc expression induced apoptosis in glioma cells in the presence of 10% fetal calf serum. Whereas, s-Myc-mediated apoptosis was suppressed in proportion to the increase of bcl-2 expression as seen in c-Myc mediated apoptosis. The s-myc gene was expressed in rat embryo cells being committed to differentiate to hypertrophic chondrocytes which undergo programmed cell death. CAT assay demonstrated that in the NH2-terminal region, the s-Myc protein contains a domain structure required for expression of transactivation activity that is approximately six times higher than that of c-Myc. Therefore, these findings strongly suggest that s-Myc may play an important role in transcription regulation of a set of genes whose expression induces programmed cell death in vitro and in vivo.

3T3 Cells↗
PubMed1993

Restriction endonuclease recognition and southern hybridization of bromodeoxyuridine-substituted genomic DNA.

Human glioma cell lines exposed to various concentrations of bromodeoxyuridine (BrdUrd) were studied to determine the effect of BrdUrd substitution on restriction endonuclease recognition and Southern hybridization of genomic DNA. BrdUrd substitution had no effect on the recognition of restriction endonucleases. When the exposure to BrdUrd was 2h or less and the BrdUrd substitution rate was less than 40%, there was no difference in the density of hybridized bands after Southern hybridization using human non-recombinant complementary DNA as a probe. Hybridization was suppressed significantly by exposures longer than 24 h or BrdUrd substitution rates greater than 40%. These results suggest that the BrdUrd substitution rate and the exposure time to BrdUrd influence the hybridization reaction by a DNA probe. Brief exposure (up to 2 h) to BrdUrd does not influence restriction endonuclease recognition or Southern hybridization of genomic DNA.

Base Sequence↗
PubMed1993

Bile duct atresia following extended right hepatectomy because of a tumor.

A 19 month old male infant with a mesenchymal hamartoma of the liver underwent an extended right hepatectomy. Serum bilirubin gradually rose until 3 months after the surgery, and obstructive jaundice and acholic stools were manifested at 6 months. Percutaneous transhepatic cholangio-drainage was performed. Cholangiography showed dilation of the intrahepatic bile duct of the residual lateral segment and complete obstruction of the extrahepatic bile duct. A second operation for reconstruction of the biliary tract was performed 10 months after the first surgery. No aspect of an extrahepatic biliary tract was found. Histological inspection of a surgical specimen of remnant tissue revealed only cicatricial connective tissue without any biliary structures. The clinical course has been uneventful for 18 months since the second surgery. The cause of bile duct atresia in this case is strongly suggested to be an ischemic change due to devascularization of the extrahepatic biliary tract following hepatic resection because of a tumor. To prevent this kind of complication, hepatico-enterostomy should be performed close to the cut surface of the liver.

Biliary Atresia↗
PubMed1993

A case of biliary stricture caused by cavernous transformation of the portal vein.

A case is reported of extrahepatic obstruction of the portal vein with the unusual complication of obstructive jaundice that resulted from compression of the common bile duct caused by cavernous transformation of the varicose network. It is surgically impossible to repair choledochal stenosis resulting from enlarged varices in the vicinity of the common bile duct. In this case, internal drainage from the biliary duct to the duodenum using a silastic tube and a reservoir implanted in the subcutaneous space successfully eliminated the jaundice.

Adolescent↗
PubMed1993

Successful treatment of recurrent malignant germ cell tumors: report of two cases.

We report two patients with recurrent malignant germ cell tumors who were successfully treated with radiation therapy and cisplatin combination chemotherapy. Patient 1, who had a suprasellar mixed yolk sac tumor, had been free of tumor for 3.5 years after cisplatin/vinblastine/bleomycin combination chemotherapy alone but showed a recurrent tumor in the pineal region. In Patient 2, who had a pineal alpha-fetoprotein-producing tumor, recurrent tumors appeared in the lateral ventricle 3 years after the tumor was controlled by radiation and cisplatin/vinblastine/bleomycin therapy. They were treated successfully again by radiation therapy, followed by cisplatin and etoposide combination therapy, and they have been free of tumor for 5.5 and 7 years after recurrence, respectively. The total dose of cisplatin in both patients exceeded 1,000 mg/m2, which would have contributed to the control of the recurrent tumors. Anterior pituitary dysfunction observed in Patient 1 did not improve, even after tumor disappearance by chemotherapy, suggesting severe damage to the neurohypophysis by direct invasion of the tumor.

Adolescent↗
PubMed1992

Cell kinetic analysis of human brain tumors by in situ double labelling with bromodeoxyuridine and iododeoxyuridine.

Fifty-seven patients with brain tumors (29 gliomas, 23 meningiomas, 5 miscellaneous) received infusions of intravenous iododeoxyuridine (IUdR) and bromodeoxyuridine (BUdR) 1-5 hr apart shortly before tumor removal. Excised tumor specimens were stained sequentially for BUdR and IUdR. The percentage of BUdR-labelled cells was determined to establish the labelling index (LI), or S-phase fraction, and the ratio of cells labelled only with IUdR to cells labelled with BUdR or with BUdR and IUdR was determined to calculate the duration of S-phase (Ts) and the potential doubling time (Tp) of each tumor. The BUdR LIs varied from less than 1% to 20%, reflecting the malignancy of each tumor. Despite the difference in LIs, however, Ts was fairly uniform (mean +/- SD, 8.7 +/- 2.0 hr). Tp varied from 2 days to more than 1 month and correlated closely with the BUdR LIs (Tp = 23/LI0.93; r2 = 0.91). Double-labelling studies with IUdR and BUdR allow the S-phase fraction, Ts and Tp to be determined from a single biopsy specimen and thus provide more useful information on the growth characteristics of individual tumors than can be obtained by single-labelling studies with BUdR.

Brain Neoplasms↗
PubMed1992

Predicting the recurrence of ependymomas from the bromodeoxyuridine labeling index.

The usefulness of histopathological grading in predicting the prognosis of patients with ependymomas is controversial. To clarify the discrepancy between the histological malignancy and the prognosis of these tumors, we estimated the proliferative potential of 32 intracranial and intraspinal ependymomas and correlated the findings with the clinical behavior. Each patient received an intraoperative infusion of bromodeoxyuridine (BUdR, 200 mg/m2 i.v.) before tumor removal; the BUdR labeling index (LI), or percentage of BUdR-labeled cells, was determined immunohistochemically in excised specimens. The mean BUdR LI (+/- SD) of intracranial malignant ependymomas was 4.1 +/- 2.8%. Nonmalignant intracranial and intraspinal ependymomas and subependymomas had mean LIs of 1.5 +/- 0.9%, 1.1 +/- 0.3%, and less than 1%, respectively. Overall, 44% of the tumors recurred. There were no statistically significant differences in the recurrence rates of intracranial and intraspinal ependymomas, including subependymomas (43% and 44%, respectively), or of intracranial ependymomas with LIs greater than 1.0% and less than 1.0% (67% and 44%, respectively). However, the early recurrence rate (within 24 months after treatment) of tumors with LIs greater than 1.0% was higher than that of tumors with LIs of less than 1.0% (100% vs. 25%, P less than 0.05). The BUdR LI also showed a statistically significant inverse correlation with the time to recurrence. These findings indicate that BUdR LI reflects the proliferative potential of individual ependymomas and can be used to help predict the recurrence and estimate the prognosis of these tumors.

Adolescent↗
PubMed1992

Surgical decompression for symptomatic Chiari II malformation in neonates with myelomeningocele.

Between January, 1981, and July, 1991, 17 infants under 1 month of age were admitted to The Hospital for Sick Children with the signs and symptoms of a Chiari II malformation. These patients' presentation included swallowing difficulty (71%), stridor (59%), apneic spells (29%), aspiration (12%), weakness of cry (18%), and arm weakness (53%). Decompression of the Chiari II malformation was performed in all patients, with a time interval between onset of symptoms and surgery ranging from 1 to 121 days. Fifteen patients (88%) remain alive, all of whom have shown a complete recovery. The mean follow-up period in this group of patients was 65 months. Two patients died, one due to respiratory arrest 8 months after decompression and the other because of shunt infection and peritonitis 7 years after decompression. These results support the concept that compressive forces, rather than a primary intrinsic disorder of the brain-stem nuclei, play a crucial etiological role in the development of a symptomatic Chiari II malformation. Early recognition of the symptoms of Chiari II malformation should be followed by immediate decompressive laminectomy in order to promote a prompt and full neurological recovery.

Arnold-Chiari Malformation↗
PubMed1992

Unusual cases of benign stricture of the biliary tract.

Three patients, i.e., two adults and one child, with unusual benign stricture of the extrahepatic biliary duct are reported. Case 1 is a 63-year-old male with obstructive jaundice caused by a sclerotic vascular ring formed by the right hepatic artery and its branch. Case 2 is an 18-year-old male with obstructive jaundice due to stricture of the common bile duct caused by compression of enlarged collateral varicose veins, so-called cavernous transformation following extrahepatic obstruction of the portal vein. Case 3 is a 19-month-old boy complicated with biliary obstruction resulting from ischemic changes of the biliary duct at 10 months after extended right hepatectomy for mesenchymal hamartoma of the liver. The definitive diagnosis was made on the basis of imaging evaluations and the surgical findings. They have been free of jaundice and have shown an uneventful clinical course after the surgical interventions.

Adolescent↗
PubMed1992

A case of femoral hernia in a child.

A 9-year-old boy with a painless reducible swelling in the right groin was admitted to our hospital. The diagnosis of a right external inguinal hernia was made, but no inguinal hernial sac was found at operation. On further examination, the diagnosis of femoral hernia was confirmed. Radical operation for the femoral hernia was performed using McVay's procedure, and there has been no recurrence since the operation. In the Japanese literature, 25 cases of femoral hernias have been reported in children aged 1 month-9 year (average age, 4 years). The sex ratio of M:F was 2:3. Eleven cases were on the right side, 7 were on the left, and 5 were bilateral. The rate of irreducible femoral hernia was 48% (12/25 cases). Femoral hernias in children are very rare and often misdiagnosed as inguinal hernias. Correct diagnosis was made in only three cases (12%). Careful examination and awareness of the possibility of femoral hernia in children are very important when dealing with groin swelling in children.

Child↗