Infection of Nippostrongylus brasiliensis induces development of mucosal-type but not connective tissue-type mast cells in genetically mast cell-deficient Ws/Ws rats

Ws/Ws rats have a small deletion at the tyrosine kinase domain of the c-kit gene and are deficient in both mucosal mast cells (MMC) and connective tissue-type mast cells (CTMC). The role of the c-kit receptor in the development of MMC and CTMC was investigated by infecting Ws/Ws and control +/+ rats with Nippostrongylus brasiliensis (NB), which induces T-cell-dependent mast cell proliferation. Although mast cells did not develop in the skin of Ws/Ws rats, a significant number of mast cells developed in the jejunum after NB infection. These mast cells had the MMC protease phenotype (rat mast cell protease [RMCP] I-/II+) and lacked heparin because they were not stained with berberine sulfate. Globule leukocytes were also detected in the mucosal epithelium of these rats. However, the number of MMC and the serum concentration of RMCP II in NB-infected Ws/Ws rats were only 13% and 7% of those of NB-infected +/+ rats, respectively. A small number of mast cells also developed in the lung, liver, and mesenteric lymph nodes of Ws/Ws rats after NB infection. Although mast cells in these tissues had the MMC phenotype throughout the observation period, the increased mast cells in the lung and liver of +/+ rats acquired a CTMC-like phenotype and were RMCP I+/II+, berberine sulfate+, and formalin resistant. These results indicate that the need for the stimulus through the c-kit receptor appears to be greater in the development of CTMC in the skin as well as for CTMC-like mast cells in the lung and liver than for the development of MMC.

[Predictive factors for in-hospital mortality and delayed mortality following aneurysmal subarachnoid hemorrhage]

It is important to detect predictive factors for in-hospital and delayed mortality of patients with subarachnoid hemorrhage (SAH) due to ruptured aneurysm. Forty-eight patients with initial bleeding of aneurysmal SAH were referred to our hospital from January 1982 to December 1985. In-hospital mortality was 16.7% (8 to 48), and 15% (6) of forty patients died later during the follow-up period. Using the Kaplan-Meier method we were able to conclude that, cumulatively, there was 70.8% probability that much patients would survive for 10 years. We analysed predictive factors of in-hospital and delayed mortality retrospectively. The most significant predictive factor for in-hospital mortality was SAH grading on admission, and for delayed mortality (29.2%) age on admission was the best predictive factor. In fact, two patients died with cardiac event during the follow-up period. This result suggests that, although the SAH grading on admission was the second most significant factor for delayed mortality, patients who survived in the acute phase had a survival probability similar to those in a normal control group.

Improvement of cardiac function impaired by repeated ischemic arrests in isolated rat hearts

We investigated the effects of coenzyme Q10 and verapamil, either alone or in combination, on cardiac function impaired by repeated ischemic arrests and reperfusion in the isolated rat heart. In the group with a single ischemic arrest, the aortic flow, cardiac output, stroke volume, coronary flow, and heart rate recovered well (72% to 100% of the prearrest values). In the repeated-arrest group, the recovery of aortic flow (24%), cardiac output (30%), stroke volume (40%), or coronary flow (63%) was much poorer than that in the single-arrest group. Pretreatment with coenzyme Q10 given intraperitoneally improved aortic flow, cardiac output, stroke volume, coronary flow, and heart rate. The addition of verapamil to the reperfusion solution also protected the cardiac function with a decrease in heart rate. However, combination therapy with coenzyme Q10 and verapamil further increased the recoveries of aortic flow, cardiac output, stroke volume, and coronary flow to 57%, 61%, 77%, and 84%, respectively, which were better than the values after treatment with coenzyme Q10 or verapamil alone. We, therefore, suggest that treatment with coenzyme Q10 or verapamil, alone or in combination, in addition to St. Thomas' Hospital solution effectively protects cardiac function impaired by repeated ischemic arrests and reperfusion.

Flow characteristics of hepatic tumors at color Doppler sonography: correlation with arteriographic findings

OBJECTIVE

We studied benign and malignant hepatic tumors with color Doppler sonography and arteriography in order to correlate color Doppler flow characteristics with tumor hemodynamics (vascularity, arteriovenous shunting, and portal vein involvement) shown by arteriography. We also evaluated the usefulness of color Doppler flow characteristics in discriminating between tumor types.

SUBJECTS AND METHODS

We performed color Doppler sonography and hepatic arteriography in 58 patients with 72 hepatic lesions larger than 2.0 cm in diameter. Differences in pulsatile flow (peritumoral or intratumoral) and the highest systolic peak flow velocities reached were evaluated on color Doppler sonograms and compared with arteriographic findings.

RESULTS

Color flow sonograms were obtained in 43 of 45 hepatocellular carcinomas, 15 of 16 cholangiocellular carcinomas or hepatic metastases, and six of 11 hemangiomas. Mixed peritumoral and intratumoral pulsatile flow was shown by arteriography in highly vascular tumors. The mean peak systolic flow velocity seen in hepatocellular carcinomas (0.52 m/sec) significantly exceeded the velocity seen in hemangiomas (0.16 m/sec), but not the velocity seen in other malignant hepatic tumors (0.51 m/sec). Six hepatocellular carcinomas, one cholangiocellular carcinoma, and two hepatic metastases with peak systolic flow velocities greater than 0.80 m/sec were each proved arteriographically to have arteriovenous shunting or portal vein involvement.

CONCLUSION

Color Doppler sonography was useful for evaluating hepatic tumor hemodynamics as seen at arteriography, and peak systolic velocity may be useful in differentiating malignant hepatic tumors from hemangiomas.

Elevated serum thymidine kinase activity in patients with acute viral hepatitis

To evaluate the clinical applications of serum thymidine kinase (TK) activity, we compared the results obtained with this parameter with those of other liver function tests in 27 patients with acute viral hepatitis and 16 normal controls. In those in the acute stage, the serum TK activity increased significantly to 55.5 +/- 66.5 U/L. There was no significant correlation between serum TK activity and findings for serum albumin, bilirubin, alkaline phosphatase or r-glutamyl transpeptidase. However, it did correlate significantly well with the serum activity of aspartate aminotransferase (AST) (r = 0.621, P < 0.01), alanine aminotransferase (ALT) (r = 0.551, P < 0.01), and lactate dehydrogenase (LDH) (r = 0.620, P < 0.01). Serum TK activity reached higher than 70 U/L in 8 of 11 patients with hepatitis A; however, no patients with the other types of hepatitis reached such a high level. During the recovery stage, the serum TK activity decreased significantly to 5.9 +/- 1.7 U/L (P < 0.01), and did not correlate with AST, ALT, LDH or other conventional liver function parameters. The data suggest that an elevation of serum TK in patients with acute viral hepatitis results from hepatocellular damage. A marked elevation of serum TK activity may thus provide a marker for acute hepatitis A infection.

[Antitumor activity of navelbine (vinorelbine ditartrate), a new vinca alkaloid analog]

The antitumor activity of navelbine (vinorelbine ditartrate, KW-2307) against murine and human transplantable tumors was compared with those of other vinca alkaloids, vindesine (VDS), vincristine (VCR) or vinblastine (VLB). KW-2307 and VDS increased the life span of mice bearing ascitic tumors (P 388 leukemia, L 1210 leukemia, EL-4 lymphoma, Colon 26, FM 3 A mammary carcinoma and M 5076 sarcoma) slightly more than VCR or VLB. A significant difference was not found in the antitumor activities against 6 murine solid tumors (B 16 melanoma, Colon 26, FM 3 A mammary carcinoma, Lewis lung carcinoma, M 5076 sarcoma and Sarcoma 180). However, a remarkable difference was observed in the antitumor activities against 11 human tumors inoculated into nude mice. The activity of KW-2307 was more than those of other 3 drugs against 4 human non-small cell lung carcinomas (Lu-65, Lu-99, LC-6 and L-27) and 2 stomach carcinomas (St-4 and St-40). KW-2307 and VDS were also effective in inhibiting the growth of 2 human breast carcinomas (MX-1 and Br-10).

Aberrant retrotracheal goiter: report of a case

A case of intrathoracic retrotracheal goiter in a 40-year-old woman is herein described. A computed tomographic scan, magnetic resonance imaging and endoscopical ultrasonography all confirmed the existence of a retrotracheal encapsulated lesion, which was suspected to be aberrant mediastinal goiter. Radioiodine scintigraphy, however, demonstrated little uptake in the mass. A large (7 x 6 x 4 cm), encapsulated adenomatous goiter was then easily removed via a right thoracic approach.

Sympathetic innervation of the young canine heart using antero- and retrograde axonal tracer methods

The present study was performed to determine the origin of cardiac sympathetic postganglionic fibers and to demonstrate their distribution in the heart. Young dogs were used in this study. Wheat germ agglutinin-horseradish peroxidase (WGA-HRP) was injected into various regions of the heart, and cholera toxin B subunit (CTB) and WGA-HRP were injected into the middle cervical ganglion or the stellate ganglion. In our retrograde axonal transport study, a large number of WGA-HRP-labeled cells were observed in the middle cervical and stellate ganglia bilaterally. Only a small number of the labeled cells were observed in the superior cervical ganglia bilaterally. In the anterograde axonal transport study, CTB and WGA-HRP labels showed terminal-like structures in the intrinsic ganglia located in the sinoatrial node, left atrium, and the origin of the ascending aorta. The labeled fibers were also observed around the coronary arteries.

Disposition and metabolism of KW-2149, a novel anticancer agent

KW-2149 is a new derivative of mitomycin C (MMC). The plasma concentrations, distribution, metabolism, and excretion of [3H]-KW-2149 in normal and tumor-bearing mice after i.v. administration of 16.6 mg/kg were investigated. The plasma radioactivity decreased biexponentially after i.v. administration in normal mice. However, the unchanged drug disappeared rapidly, showing a half-life (t1/2) of 9.7 min, which was shorter than MMC's (18 min). The radioactivity was excreted in mouse urine (33%) and feces (58%) within 144 h. High radioactivity was distributed in the gallbladder, liver, kidney, pancreas, and lung at 1 h after i.v. administration to normal mice. The tumor concentration was lower than the plasma or blood concentration. The lowest radioactivity was observed in the brain. The metabolic rate of KW-2149 was very rapid. The methyl sulfide form (M-16), the symmetrical disulfide dimer (M-18), and the albumin conjugate were detected in plasma, which possessed anticellular activity. The specific anticellular activity of these compounds against uterine carcinoma (HeLa S3) was 1/100, 1, and 1/20 respectively, as compared with that of KW-2149.

[Non-radioisotopic reverse transcriptase assay using biotin-11-deoxyuridine-triphosphate and a primer-immobilized microtiter plate: application for detection and identification of isolated retroviruses from HIV-1-seropositive hemophiliac patients]

Non-radioisotopic reverse transcriptase assay (Non-RTA) was successfully applied for detection and identification of the retroviruses isolated from peripheral mononuclear cells from eight HIV-1-seropositive hemophiliac patients. Of 40 samples, 36 (90%) were consistent in detection between Non-RI and RI RTA. Four samples which showed RT activities slightly above the cutoff level of RI RTA were not detected by Non-RI RTA. Non-specific RT-inhibitors in the culture supernatant decreased the sensitivity of Non-RI RTA more significantly than that of RI RTA. It was demonstrated that higher concentrations (> 20%) of fetal calf serum in RPMI-1640 culture medium inhibited the hybridization of poly rA template with immobilized primer, resulting in reducing the sensitivity of Non-RI RTA. Then we identified the isolated retroviruses using specific RT-inhibiting (RTI) antibodies against HIV-1 and HIV-2. HIV-1 RTI antibody specifically inhibited RTs of isolated retroviruses and HIV-1 strain, LAV-1, but not HIV-2 and Rous-associated virus 2 (RVA-2) RT. Conversely, HIV-2 RTI antibody specifically inhibited HIV-2 RT, but not HIV-1 and RAV-2 RT. These findings agreed with previously reported results showing the type-specificity of HIV-1 and -2 RTI antibodies, and suggest the possibility that isolated retroviruses could be identified by these antibodies.

[The surgical treatment for the Stanford type A aortic dissection]

Twenty-nine patients who underwent operation at Shinshu University Hospital for the Stanford type A dissecting aneurysm were analysed. The patients were operated on in the acute stage within 2 weeks after onset. In 13 of these 26 acute cases, the graft replacement of the ascending and arch of the aorta was performed (group A). The patients were operated under a separate perfusion to the brain and the distal anastomosis to the proximal portion of the descending aorta was performed using the method of open distal anastomosis. In other 13 cases, the graft replacement of the ascending aorta was performed (group B). Operative mortality rate was 19% in this series (group A: 23%, group B: 15%). There was no significant difference in their operative mortality of acute stage. And there was also no significant difference in their post operative course of acute stage operations. We concluded that the graft replacement of the ascending and arch of the aorta was better than the graft replacement of the ascending aorta alone for the patients with Stanford type A acute aortic dissection.

[A case of aortic valve stenosis and regurgitation with idiopathic thrombocytopenic purpura]

A patient of aortic valvular disease with idiopathic thrombocytopenic purpura underwent aortic valvular replacement. We report a preventive measure against the intra and postoperative bleeding. The patient was a 67-year-old man. He was diagnosed as aortic valvular stenosis with regurgitation. There was no abnormal data about the coagulation test. Thrombocyte count was 8.2 x 10(4)/mm3, but thrombocytopenic life span had shortened 3.8 days. So, we used gamma-globulin 400 mg/kg/day for 5 days before the day of operation and infused blood platelets on the day of operation. There was no problem intra and postoperative period. On the 14th postoperative day thrombocyte count increased to 22.9 x 10(4)/mm3, and thrombocytopenic life span returned to normal range (7.6 days). But on the 45th day of postoperation, thrombocyte count decreased to 11.0 x 10(4)/mm3. We think that many gamma-globulin medication is a useful method to prevent intra and postoperative bleeding resulting from idiopathic thrombocytopenic purpura.

Elevated interleukin-6 and gamma-globulin during interferon therapy of hepatitis B

A 49-yr-old man with chronic hepatitis B manifested hypergammaglobulinemia, lymphadenopathy, and a high serum interleukin-6 level following treatment with recombinant human alpha-interferon. One month later, when the patient was treated with natural beta-interferon, serum levels of interleukin-6 and gamma-globulin increased again. The serum gamma-globulin decreased to the pretreatment level after discontinuation of interferon therapy. The serum alanine aminotransferase level remained normal for 6 months. In this case, hypergammaglobulinemia and lymphadenopathy, as well as the elevated serum interleukin-6 level, were considered to be signs of highly enhanced humoral immunity related to alpha- and beta-interferon therapy.

[A case of malignant localized visceral pleural mesothelioma]

We experienced malignant localized mesothelioma of which origin was visceral pleura. According to, 1) the preoperative chest X-ray and chest CT which showed extra-pleural sign, 2) the rapid tumor growth, and 3) the result from needle biopsy, we diagnosed malignant localized mesothelioma of which origin was parietal pleura. Surgical treatment was performed, and diagnosed that its origin was visceral pleura. The tumor invaded the lung. It is dangerous to diagnose by means of needle biopsy because of malignant cell implantation. We recommend that firstly the surgical treatment should be carried out for malignant mesothelioma, which needs extended resection for preventing its recurrence.

c-kit Gene was not transcribed in cultured mast cells of mast cell-deficient Wsh/Wsh mice that have a normal number of erythrocytes and a normal c-kit coding region

The Wsh is a mutant allele at the W (c-kit) locus of mice. Mice of Wsh/Wsh genotype have white hairs and black eyes. Although adult C57BL/6-Wsh/Wsh mice were not anemic, they showed a remarkable depletion of mast cells. Most homozygous or double heterozygous mutant mice at the W (c-kit) locus, of which mast-cell depletion was comparable to that of Wsh/Wsh mice, are deficient in germ cells. However, male and female Wsh/Wsh mice have an appreciable number of germ cells in their gonads. We investigated the mechanism of specific depletion of mast cells in Wsh/Wsh mice. Cultured mast cells (CMC) derived from the spleen of Wsh/Wsh mice neither attached to normal (+/+) fibroblasts nor survived in the coculture with +/+ fibroblasts. The c-kit messenger RNA (mRNA) was strongly expressed in +/+ CMC, but not detectable in Wsh/Wsh CMC. Despite the lack of c-kit mRNA in Wsh/Wsh CMC, the c-kit mRNA was normally detectable in the cerebellum and weakly detectable in the testis and spleen of Wsh/Wsh mice. No significant changes were found in the nucleotide sequence of the c-kit transcripts obtained from the cerebellum of Wsh/Wsh mice. Development of mast cells, erythrocytes, and germ cells in Wsh/Wsh mice appeared to be parallel with the magnitude of the c-kit gene expression in each cell type.

In vivo and in vitro antitumor activity of mitomycin C conjugates at 7-N position through a linker containing thiocarbamate bond with CD10 monoclonal antibody

Through a linker containing thiocarbomate bound to the 7-N position of mitomycin C (MMC), conjugates with a monoclonal antibody to CD10 (NL-1) were prepared, and their antitumor activities were examined. All five conjugates, except one, showed in vitro cytotoxicity to two CD10+ lymphoid cell lines superior to MMC. The conjugate displaying the highest cytotoxicity was selected and further tested against three CD10+ and two CD10- lymphoid cell lines in vitro. The conjugate with NL-1 antibody demonstrated higher cytotoxic activity against CD10+ tumor cells than the control conjugate with normal immunoglobulin, while there was no significant difference, when tested against CD10- tumors. The cytotoxic activity of the NL-1 conjugate to CD10+ tumors was significantly blocked by NL-1 antibody. In vivo antitumor activity of the NL-1 conjugate was then tested against a CD10+ tumor transplanted to nude mice, and side effects were recorded. The NL-1 conjugate (4 mg/kg) showed an in vivo antitumor effect similar to MMC (2 mg/kg), which is at nearly maximal tolerable dose; the latter induced decreases in numbers of leukocytes and platelets, while the former did not, suggesting less side effect by the NL-1 conjugate. Since MMC demonstrates a broad spectrum of antitumor activity, the conjugate, as such, may be applicable for the treatment of cancer patients.

Adjuvant radiotherapy after complete resection of thymoma

Seventy patients were studied after undergoing complete resection of thymoma to determine the effect of postoperative adjuvant mediastinal radiotherapy on prognosis, with regard to clinical stage, histological type, and pleural factor. Pleural factor was defined as follows: p0, no adhesion to the mediastinal pleura; p1, fibrous adhesion to the mediastinal pleura without microscopic invasion; and p2, microscopic invasion of the mediastinal pleura. Recurrence of thymoma after complete resection was observed in 13 patients, 12 (92%) with pleural dissemination, 6 (46%) with local recurrence, and 2 (15%) with distant metastasis (types of recurrence are overlapping). In stage I and stage II p0 patients, no recurrence was observed, regardless of mediastinal radiotherapy. Whereas mediastinal irradiation completely prevented recurrence in stage II p1 patients, 4 (36.4%) nonirradiated stage II p1 patients experienced recurrence. In stage II p2 patients, 75% had pleural dissemination even after radiotherapy. A high incidence of recurrence was also observed in stage III, nonirradiated (25%) and irradiated (30%) patients. The results suggest that mediastinal irradiation for stage I and II p0 patients is not always necessary, and that therapy for stage II p1 is essential and also expected to decrease the recurrence rate. On the other hand, in stage II p2 and stage III thymomas, mediastinal irradiation is not sufficient to prevent pleural recurrence even after complete resection. Our classification based on pleural factor is useful for better selection of appropriate postoperative treatment for thymoma patients.

Intrathoracic neurogenic tumors: MR-pathologic correlation

An MR-pathologic correlation of nine intrathoracic neurogenic tumors (three neurofibromas, four schwannomas, and two ganglioneuromas) was performed to characterize their MR appearances. The three types of intrathoracic neurogenic tumor were found to have characteristic appearances on MR images that should be helpful when establishing the differential diagnosis of posterior mediastinal tumors. The MR and histologic features of these tumors are illustrated and described in this essay.

New potent mitomycin derivatives: synthesis and antitumor activity of 7,7-(ethylenedioxy)mitomycins

A series of 6,7-dihydro-7,7-(ethylenedioxy)mitomycins was synthesized and evaluated for antitumor and anticellular activities. These compounds were prepared by basic treatment of 7-methoxymitomycins with ethylene glycol, and were structurally novel mitomycin derivatives containing a masked quinone moiety. 5,6-Enol or 6-chloro derivatives of 6,7-dihydro-7,7-(ethylenedioxy)mitomycins were also prepared and the (allyloxy)carbonyl group at the aziridine nitrogen has proved to be an efficient protecting group in chemical modification of mitomycins. Most of these mitomycin derivatives displayed potent antitumor activity against P388 leukemia in mice and anticellular activity against HeLa S3 cells.

[Results of patients in stage I and II primary lung cancer with curative resection]

We analyzed 91 patients who had curative resection from 1982 to 1989 for stage I and II primary lung cancer. The 5-year survival rates were 71.4% for stage I and 44.7% for stage II. The 5-year survival rates were 86.6% for T 1 N 0 M 0, 47.3% for T 2 N 0 M 0, 56.3% for T 1 N 1 M 0, and 37.9% for T 2 N 1 M 0. There was no cancer death in patients with squamous cell carcinoma of T 1 N 0 M 0. For stage I, tumor diameter was significant factor to influence survival. Although there was a statistically significant difference between stage I and II in patients with adenocarcinoma, there was no significant difference in those with squamous cell carcinoma. Chemotherapy had no significant improvement in survival for stage I and II lung cancer.

Improved patency of an elastomeric vascular graft by hybridization

A newly devised hybrid graft with high antithrombogenicity for small caliber vascular grafts was developed. The design concept was based on the incorporation of a compliant open cell structured graft, autogenous endothelial cells (ECs), and artificial basement membrane. The latter, a gel complex of type I collagen and dermatan sulfate that showed enhanced adhesion and growth of ECs but reduced platelet adhesion, was coated onto a microporous polyurethane graft (internal diameter, 3 mm; length, 4.5 cm), with near-natural compliance. Ten seeded grafts were implanted bilaterally into the carotid arteries of dogs; anticoagulant or antiplatelet therapy was not administered. This hybrid graft showed a marked improvement in patency at 1 month compared with that of simply preclotted grafts (control specimens). This result was explained by the almost complete endothelialization when the graft was implanted, a high degree of adherent strength resistance to shear stress, and a high proliferative potential. Thus, this approach of combining biomechanical and cellular engineering designs may lead to an important functional small caliber graft.

Thin-rim enhancement in Gd-DTPA-enhanced magnetic resonance images of tuberculoma: a new finding of potential differential diagnostic importance

The article describes rim enhancement seen on Gd-DTPA-enhanced magnetic resonance (MR) images of two patients with tuberculoma. Pathologic examination of the surgical specimens disclosed that the peripheral portion of the tuberculoma, which showed contrast enhancement, was composed mainly of a fibrous capsule and epithelioid granulomas and that the central zone, which showed no contrast enhancement, was composed of caseous necrotic material. In a retrospective study of MR images from 20 consecutive cases of surgically proven bronchogenic carcinoma, none showed a thin enhancing rim on postcontrast MR images. Although confirmation of these findings must await further experience, the postcontrast MR findings described here may prove to be of value in distinguishing tuberculoma and possibly other granulomatous lesions from bronchogenic carcinoma.

A novel point mutation in the human insulin gene giving rise to hyperproinsulinemia (proinsulin Kyoto)

We have identified a 65-yr-old nonobese Japanese man with diabetes mellitus, fasting hyperinsulinemia (150-300 pM), and a reduced fasting C-peptide/insulin molar ratio of 2.5-3.0. Fasting hyperinsulinemia was also found in his son and daughter. Analysis of insulin isolated from the serum of the proband and his son by reverse-phase high performance liquid chromatography revealed a minor peak coeluting with human insulin and a major peak of proinsulin-like materials. The insulin gene of the patient was amplified by the polymerase chain reaction and the products were sequenced. A novel point mutation was identified in which guanine was replaced by thymine. The substitution gives rise to a new HindIII recognition site and results in the amino acid replacement of leucine for arginine at position 65. These results indicate that the amino-acid replacement prevents recognition of the C-peptide-A chain dibasic protease and results in an elevation of proinsulin-like materials in the circulation. Furthermore, in this family the proinsulin-like materials is due to a biosynthetic defect, inherited as an autosomal dominant trait. Rapid detection of this mutation can be accomplished by HindIII restriction enzyme mapping of polymerase chain reaction-generated DNA, which enables us to facilitate the diagnosis and screening.

Antitumor quinolones with mammalian topoisomerase II mediated DNA cleavage activity

Ninety quinolones were evaluated to determine whether their ability to induce mammalian topoisomerase II mediated DNA cleavage in vitro correlated with their antitumor activity in vivo. Ten quinolones generated linear DNA at a yield of more than 10% of substrate supercoiled DNA in the mammalian topoisomerase II mediated DNA cleavage assay. All of these compounds showed a significant increase in life span (greater than 20%) in the murine leukemia P388 model. These antitumor quinolones have closely related structures: two halogens at C-6 and C-8; and cyclopropyl at N-1 of quinolone skeleton. In contrast, many analogues of the above quinolones, as well as new quinolones used clinically as an antibacterial drug, did not induce the cleavable complex in vitro or show antitumor activity in vivo. These findings indicate that quinolone derivatives can be a promising new class of antitumor agent targeting mammalian topoisomerase II.