[Effect of percutaneous transluminal mitral commissurotomy on pulmonary function and on the pulmonary vasculature]

We evaluated the therapeutic effect of percutaneous transluminal mitral commissurotomy (PTMC) on pulmonary function, and the damage caused to pulmonary vasculature by transient occlusion of the mitral valve during PTMC in patients with mild mitral stenosis. Pulmonary function tests were done and serum thrombomodulin was measured in 6 patients before and after PTMC. The mean pulmonary arterial pressure and mean pulmonary arterial wedge pressure decreased significantly from the control values, and the decreases were proportional to the increase in the area of the mitral valve. VC, %VC, and DLco were in the normal range before and after PTMC but PEFR, FEV1%, FEV1, V50, V25, and V50/V25 were significantly higher after PTMC. Change in the area of the mitral valve correlated with the changes in FEV1% (r = 0.841), in V50 (r = 0.624), and in V25 (r = 0.697). The serum thrombomodulin levels before and after PTMC did not differ. We conclude that pulmonary dysfunction in patients with mild mitral stenosis MS is mainly due to an obstructive ventilatory defect, and that PTMC can correct this dysfunction without damaging the pulmonary vasculature.

A physiological role of interferon (IFN)-beta derived from tumor: tumor growth of a mouse bladder carcinoma line MBT-2 is partially suppressed by autocrine IFN-beta

Although some tumor cells endogenously produce a wide variety of cytokines, their physiological roles remain to be fully understood. In this study, we found that mouse subcutaneous tumor induced by inoculation of bladder tumor MBT-2 cells into syngeneic mice secreted a significant amount of interferon (IFN), whereas the cells exhibited no IFN production in in vitro cell culture. Typing experiment using IFN-specific neutralizing antibodies showed that the tumor-derived IFN was exclusively beta type. Since the MBT-2 tumor tissues were homogenous and not infiltrated by immune cells, MBT-2 cells themselves were considered to be IFN-beta producers. By intraperitoneal injection of neutralizing anti-IFN-beta antibodies into MBT-2 cell-inoculated mice, the tumor growth was substantially precipitated and survival days of the tumor-bearing mice were shortened. As the in vitro cell growth of MBT-2 cells was dose-dependently inhibited by IFN-beta, it was suggested that apparent immunogenicity of MBT-2 tumor is partially mediated by tumor suppression by autocrine IFN-beta.

[Simultaneous ambulatory electrocardiography and pulse oximetry]

We developed a system for 24-hour ambulatory recording of blood oxygenation (SpO2) and electrocardiography (ECG). Using this system, we studied 10 healthy volunteers and 7 patients with chronic pulmonary diseases. The system incorporated a portable pulse oximeter (SM50) manufactured by Fukuda Denshi KK; the first and second channels were used to record ECG data and the third was used to record SpO2 data. An SpO2 sensor (Dispo-sensor D-25; Nellcor Inc.) was applied to the fourth of fifth finger. The SpO2 data (MicrO2; Siemens AG) were digitized and stored in the ambulatory recording device; the ECG was recorded simultaneously. The data were analyzed with a model DMW-9000H analyzer (Fukuda Denshi KK). A custom-designed program was also used, to remove noise errors. In the healty volunteers, SpO2 was at least 90% for the entire 24 hours. In all the patients, SpO2 fell below 90% at rest during the night or after a 15-minute walk. Transient atrial tachycardia was observed in 3 patients, and during the tachycardia the SpO2 was low. The number of extra ventricular beats divided by the total number of beats increased more in the patients than in the healthy volunteers (1.21 +/- 0.89 vs 0.6 +/- 0.3%, p < 0.05). SpO2 did not change significantly in the patients. In outpatients and in patients receiving home health care, the present system facilitates simultaneous diagnosis of respiratory failure an arrhythmias. In patients with chronic pulmonary diseases desaturation may cause transient atrial tachycardia.

Possible role of neurointerventional techniques in the diagnosis of hemifacial spasm

We used neurointerventional techniques to conduct a functional investigation of the artery responsible for hemifacial spasm in a 48-year-old woman. Insertion of a microcatheter into the posterior inferior cerebellar artery stopped the hemifacial spasm immediately and completely. The artery was verified intraoperatively as the vessel compressing the root exit zone of the facial nerve.

Molecular cloning of a functional murine arginine-specific mono-ADP-ribosyltransferase and its expression in lymphoid cells

A protein mono-ADP-ribosyltransferase (ADPRT), anchored in the cell membrane as a glycosylphosphatidylinositol (GPI)-anchored cell-surface enzyme, was recently described on murine cytotoxic T cells (CTL). Expression of this enzyme was shown to exert regulatory functions on CTL proliferation and cytotoxic activity, presumably by modulating activity of the protein tyrosine kinase p56(lck), which is associated with the CTL co-receptor CD8. Here we report on the molecular cloning and expression of this important regulatory enzyme. The ADPRT coding sequence was derived by making use of ADPRT sequence homologies from different vertebrate species. A cDNA fragment of the enzyme coding sequence was generated by reverse transcription polymerase chain reaction (RT-PCR) from murine T-cell lymphoma SL12, which expresses the cell-surface ADPRT. The cDNA fragment was found to share extensive homology with the corresponding sequences of human and rabbit muscle ADPRT. In Northern blot hybridization, this cDNA fragment generates a strong hybridization signal with RNA from murine heart and skeletal muscle. Weak signals are seen with SL12, thymus, and spleen. Therefore, a murine skeletal muscle cDNA library was used to identify and obtain the coding sequence of the ADPRT gene. It is shown that the nucleic acid open reading frame sequence of the murine skeletal muscle gene shares 80.3% and 76.3% homology with the sequences of the human and rabbit muscle genes, respectively. Semiquantitative RT-PCR with intron-spanning primers shows that the ADPRT mRNA is present in lymphoid organs, cytotoxic T cells, and T-cell lines. Transfection of the ADPRT coding sequence into EL4 cells results in expression of the enzyme as a functional GPI-anchored cell-surface protein, able to ADP-ribosylate the arginine analog agmatine as well as cell-surface molecules.

Molecular cloning and characterization of the obg gene of Streptomyces griseus in relation to the onset of morphological differentiation

Morphological differentiation in microorganisms is usually accompanied by a decrease in intracellular GTP pool size, as has been demonstrated in bacillaceae, streptomycetaceae, and yeasts. The obg gene, which codes for a GTP-binding protein belonging to the GTPase superfamily of proteins, was cloned from Streptomyces griseus IFO13189. The gene is located just downstream of the genes for ribosomal proteins L21 and L27, encoded a protein of 478 amino acids (51 kDa), and possessed three consensus motifs which confer GTP-binding ability; Obg protein expressed in Escherichia coli bound GTP, as demonstrated using a UV cross-linking method. Introduction of multiple copies of obg into wild-type S. griseus suppressed aerial mycelium development in cells on solid media. However, no effect on streptomycin production was detected, indicating that Obg is involved in the regulation of the onset of morphological but not physiological differentiation. Multiple copies of obg also suppressed submerged spore formation in liquid culture. Southern hybridization studies indicated that genes homologous to obg exist widely in streptomycetes, and an obg homolog was successfully cloned from S. coelicolor A3(2). We propose that by monitoring the intracellular GTP pool size, the Obg protein is involved in sensing changes in the nutritional environment leading ultimately to morphological differentiation.

Complications and reimplantation of penile implants

BACKGROUND

Complications of penile prosthesis implants can be divided into surgical and mechanical failure. We investigated penile prosthesis implants to clarify the surgical and mechanical complications that have arisen in our clinical experience.

METHODS

In the 11 years between 1984 and 1995, 83 penile prostheses were implanted in 74 patients ranging from 37 to 82 years of age.

RESULTS

Of the 64 malleable and mechanical prostheses, 11 were extracted, including 4 removed because of surgical complications and 2 due to mechanical failure. Of the 19 inflatable prostheses, 6 were removed, including 1 extracted due to surgical complication and 5 extracted due to mechanical failure. Nine reimplantations for 8 patients were performed and all these cases had good results. As a result, 66 out of 74 patients could have coitus after prosthetic surgery.

CONCLUSIONS

Penile prosthetic surgery is an established method of treating organic impotence, however, it should only be considered for selected and well-informed patients to avoid complications and revision surgery.

Association of eosinophil granule major basic protein with atopic cataract

PURPOSE

To investigate the mechanism of atopic cataract development, we examined a tissue-destroying major basic protein, derived from eosinophils, in the anterior capsule of cataractous lenses and the aqueous fluid of atopic dermatitis patients.

METHODS

Major basic protein deposition in anterior capsule tissues was evaluated immunohistochemically using anti-major basic protein monoclonal antibody in three consecutive eyes from three atopic cataract patients and three consecutive eyes from three senile cataract patients. Also, major basic protein concentration in aqueous fluid obtained during cataract surgery was measured by radioimmunoassay in 12 consecutive eyes from 11 atopic cataract patients and 15 consecutive eyes from 15 senile cataract patients.

RESULTS

Immunohistochemical investigation demonstrated lens epithelial major basic protein deposition in all three atopic cataracts but not in any of the senile cataracts. Major basic protein was detected in the aqueous fluid by radioimmunoassay in four of the 12 atopic cataract eyes and ranged in concentration from 11 to 70 ng/ml. No major basic protein was detected in the aqueous fluid of the 15 senile cataract eyes.

CONCLUSION

Major basic protein in anterior capsule tissues and in the aqueous fluid of eyes with atopic cataract may be associated with the pathogenesis of atopic cataract.

Induction of actinorhodin production by rpsL (encoding ribosomal protein S12) mutations that confer streptomycin resistance in Streptomyces lividans and Streptomyces coelicolor A3(2)

A strain of Streptomyces lividans, TK24, was found to produce a pigmented antibiotic, actinorhodin, although S. lividans normally does not produce this antibiotic. Genetic analyses revealed that a streptomycin-resistant mutation str-6 in strain TK24 is responsible for induction of antibiotic synthesis. DNA sequencing showed that str-6 is a point mutation in the rpsL gene encoding ribosomal protein S12, changing Lys-88 to Glu. Gene replacement experiments with the Lys88-->Glu str allele demonstrated unambiguously that the str mutation is alone responsible for the activation of actinorhodin production observed. In contrast, the strA1 mutation, a genetic marker frequently used for crosses, did not restore actinorhodin production and was found to result in an amino acid alteration of Lys-43 to Asn. Induction of actinorhodin production was also detected in strain TK21, which does not harbor the str-6 mutation, when cells were incubated with sufficient streptomycin or tetracycline to reduce the cell's growth rate, and 40 and 3% of streptomycin- or tetracycline-resistant mutants, respectively, derived from strain TK21 produced actinorhodin. Streptomycin-resistant mutations also blocked the inhibitory effects of relA and brgA mutations on antibiotic production, aerial mycelium formation or both. These str mutations changed Lys-88 to Glu or Arg and Arg-86 to His in ribosomal protein S12. The decrease in streptomycin production in relC mutants in Streptomyces griseus could also be abolished completely by introducing streptomycin-resistant mutations, although the impairment in antibiotic production due to bldA (in Streptomyces coelicolor) or afs mutations (in S. griseus) was not eliminated. These results indicate that the onset and extent of secondary metabolism in Streptomyces spp. is significantly controlled by the translational machinery.

Circulating endogenous thrombopoietin, interleukin-3, interleukin-6 and interleukin-11 levels in patients undergoing allogeneic bone marrow transplantation

To elucidate the physiologic role of thrombopoietin (TPO) for hematologic reconstitution following allogeneic bone marrow transplantation (BMT), serum TPO levels as well as interleukin-3 (IL-3), IL-6 and IL-11 were serially measured in 55 samples from 3 patients who underwent allogeneic BMT using an enzyme-linked immunosorbent assay (ELISA). The TPO level was higher in the serum taken during marrow aplasia than in the pretransplant serum. The serum TPO levels and platelet counts showed a strong inverse relationship in all patients examined. We also sequentially measured endogenous serum TPO levels before and within 36 h after platelet transfusions. Endogenous serum TPO levels were inversely correlated with platelet mass following platelet transfusions. Serum levels of IL-3 had no apparent correlation with platelet counts and serum levels of IL-11 remained below the detection levels (31.3 pg/ml) in all samples. Serum levels of IL-6 were high during myeloaplasia and more upregulated in the febrile period. These findings support the view that TPO is the central regulator for megakaryopoiesis in vivo and the rationale for its clinical use after allogeneic BMT.

Crkl is constitutively tyrosine phosphorylated in platelets from chronic myelogenous leukemia patients and inducibly phosphorylated in normal platelets stimulated by thrombopoietin

Platelet functions such as aggregation and clot retraction are often abnormal in chronic mylogenous leukemia (CML) patients. However, the molecular mechanisms of these altered functions are unknown. As expression of the p210bcr-abl oncogene product, a constitutively active tyrosine kinase, is known to have an essential role in the pathogenesis of CML and tyrosine phosphorylation is intimately involved in various aspects of platelet activation, we examined the pattern of protein tyrosine phosphorylation in platelets from 15 CML patients by immunoblotting with a monoclonal antiphosphotyrosine antibody (4G10). Before and after stimulation with thrombin, the only consistent difference between normal and CML platelets was the presence of a tyrosine phosphorylated protein with a relative molecular weight of 39 kD. This tyrosine phosphorylated protein was identified as crid, an SH2, SH3 containing adapter protein. Thus, as previously demonstrated for neutrophils from CML patients, tyrosine phosphorylation of p39crkl persists in mature platelets. No tyrosine phosphorylation of crid was detected following stimulation with thrombin in normal platelets. However, crkl became incorporated into the Triton X-100 insoluble residue following thrombin stimulation in a manner dependent on platelet aggregation. Further, we found that crkl is an endogenous substrate for calpain, a protease that may be involved in postaggregation signaling processes. This suggests that crkl may be involved in the reorganization of the cytoskeleton during normal platelet aggregation and its tyrosine phosphorylation in CML platelets may contribute to the abnormal platelet function in CML patients. Finally, we found that thrombopoietin induces tyrosine phosphorylation of crk1 in normal platelets and FDCP cells genetically engineered to express human c-Mpl. This suggests that crk1 can be phosphorylated by a kinase other than p210bcr-abl and that crk1 may have a role in signaling by thrombopoietin.

Ventromedial hypothalamus suppresses splenic lymphocyte activity through sympathetic innervation

The ventromedial hypothalamic nucleus (VMH) has been proposed to be a locus intimately associated with sympathetic facilitation in peripheral tissues. To investigate a possible role of the VMH in controlling peripheral immune functions, we examined the effects of VMH stimulation on proliferative activity of lymphocytes isolated from the spleen in rats. Electrical stimulation of the VMH (2 s at every 30 s for 30 min) caused a remarkable decrease in the mitogenic response of splenic lymphocytes to Concanavalin A, whereas the stimulation of other hypothalamic regions such as the paraventricular nucleus did not show any significant effects. The suppressive effect of VMH stimulation was not influenced after adrenalectomy, suggesting a minor role of the adrenocortical system. In contrast, pretreatments with a ganglionic blocking agent (chlorisondamine) and a beta-adrenergic receptor antagonist (propranolol) completely reversed the suppressive effect. Surgical severing of the sympathetic nerves entering the spleen also reversed the effect of VMH stimulation. Together with the previous finding that VMH stimulation activates the splenic sympathetic nerves, it is concluded that the VMH suppresses the proliferative activity of splenic lymphocytes through the activation of sympathetic nerves via the beta-adrenergic pathway.

[Bronchiolitis obliterans organizing pneumonia (BOOP) after allogeneic bone marrow transplantation]

We report a patient who underwent allogeneic bone marrow transplantation for ALL. The patient presented low grade fever, cough and dyspnea at day 3 after after bone marrow transplantation. Imaging studies showed bilateral patchy infiltrates on chest X-ray and chest CT. Though treated by antibiotics, chest auscultation recognized marked bilateral inspiratory crackles. Transbronchial lung biopsy performed on day 34 showed bronchiolitis obliterans and an organizing interstitial pneumonia. The patient was treated with methylprednisolone and follow up computed tomography findings improved.

Expression of Salmonella typhimurium rpoS and rpoS-dependent genes in the intracellular environment of eukaryotic cells

Adaptation to the intracellular environment of host cells is crucial for the pathogenesis of Salmonella infections. The alternative sigma factor RpoS is a global regulator of gene expression during starvation and stress conditions and is required for virulence in Salmonella spp. We have used lacZ reporter fusions to rpoS and rpoS-dependent genes to study rpoS regulation after entry of Salmonella typhimurium into macrophages and epithelial cells. The results demonstrate that expression of an rpoS::lacZ translational fusion increases rapidly in S. typhimurium after phagocytosis. Activity of RpoS also increases after bacterial entry into both macrophages and epithelial cells, as demonstrated by the induction of the rpoS-regulated genes katE and spvB. A control rpoS-independent promoter for neomycin resistance does not show significant induction after cell entry. These results demonstrate that the regulatory system mediated by RpoS in S. typhimurium is activated by the intracellular environment of eukaryotic cells.

Major salivary gland lesions: correlation of MR findings with flow cytometric DNA analysis and prognosis

OBJECTIVE

We correlated MR imaging findings with those from flow cytometry and determined prognostic factors of patients with major salivary gland lesions.

SUBJECTS AND METHODS

DNA ploidy (11 aneuploid, 35 diploid lesions) and S-phase fraction (SPF) (12 high-SPF, 28 low-SPF lesions) percentages as determined by flow cytometric technique in 46 major salivary gland lesions were correlated with MR findings and signal-intensity ratios of lesion to muscle on fast spin-echo T2-weighted images, unenhanced spin-echo T1-weighted images, and gadolinium-enhanced fat-suppressed spin-echo T1-weighted images. SPF percentages were correlated with the three signal-intensity ratios by stepwise regression analysis. Prognostic indicators of disease-free survival were assessed with Cox multivariate analysis (range of follow-up, 2-50 months; mean, 16.6 months).

RESULTS

Signal-intensity ratios for all pulse sequences were significantly smaller in aneuploid lesions than in diploid lesions. Incidence of ill-defined margins (p < .001), invasion (p = .014), and hypointensity to the gland on T2-weighted images (p = .047) was significantly higher in aneuploid lesions than in diploid lesions. Of these, signal-intensity ratios on enhanced T1-weighted images were most accurate for predicting aneuploidy. A threshold of 1.55 for signal-intensity ratios on enhanced T1-weighted images yielded the highest accuracy (86%) for aneuploidy. Signal-intensity ratios on T2-weighted images (p = .025) and enhanced T1-weighted images (p < .001) were significantly smaller in high-SPF lesions than in low-SPF lesions. A threshold of 1.73 for signal-intensity ratios on enhanced T1-weighted images yielded 73% accuracy for high-SPF lesions, which was inferior to the prediction possible from ill-defined margins (80% accuracy). Aneuploidy (p = .008), ill-defined margins (p = .036), and signal-intensity ratios on unenhanced T1-weighted images (p = .008), related significantly and negatively to disease-free survival. A signal-intensity ratio of 1.22 or less for unenhanced T1-weighted images indicated a high risk of developing recurrence (100% sensitivity).

CONCLUSION

MR findings and signal-intensity ratios can reflect DNA ploidy and SPF status and can predict prognoses for patients with major salivary gland lesions.

Characterization of the purified cytosolic thymidine kinase from murine ehrlich ascites tumor: interconversion of two different relative molecular weight forms

Cytosolic thymidine kinase was purified 18,000-fold of the homogenate from murine Ehrlich ascites tumor, using the [p-aminophenyl 3' -dTMP]-CH-Sepharose affinity column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme showed a single protein band of molecular weight 26,000. Two different forms, relative molecular weight 50,000 and 70,000, were found by gel filtration, depending on the existence of dithiothreitol, ATP and other nucleotides. These agents also stabilize and stimulate the enzyme activity. The existence of two forms was also manifested by DEAE-Sephacel column chromatography, where the 50,000 form was eluted by 50 mM NaCl and the 70,000 form by 400 mM NaCl.

Serial quantification of minimal residual disease of t(8;21) acute myelogenous leukaemia with RT-competitive PCR assay

The chromosomal translocation (8;21)(q22;q22) in the AML M2 subtype according to the FAB classification, results in the production of a novel fusion gene AML1/ETO. The chimaeric AML1/ETO transcript is useful for the detection of minimal residual disease (MRD). Recently, several studies on the detection of AML1/ETO transcripts in t(8;21) AML have been reported. However, the clinical significance of a small number of AML1/ETO transcripts by a reverse transcription-polymerase chain reaction (RT-PCR) remains to be elucidated. We have developed a novel quantitative RT-competitive PCR assay and evaluated the clinical usefulness of this method by the monitoring of MRD in eight patients with t(8;21) AML. In four patients in first continuous complete remission (CR) the value of MRD was always < 0.1 fg of the competitor dose throughout their courses, whereas in four relapsed patients there was an increase in the value of MRD to > 0.1 fg of the competitor dose before cytogenetic relapse. We conclude that the detection of the presence of cells with AML1/ETO fusion transcripts by our RT-competitive PCR assay may be useful to monitor disease progression and to predict subsequent relapse.

Durable molecular remission in a patient with chronic myelogenous leukemia and host-derived hematopoiesis after allogeneic bone marrow transplantation

A 44-year-old woman with Ph-positive CML was treated with TBI, splenic irradiation, Ara-C, and CY. She then received unmanipulated marrow cells from her HLA-identical brother. GVHD prophylaxis was FK506 and MTX. WBC counts reached 1000/microliter on day 28 when all metaphases of marrow cells showed 46XY. However, on day 42, 46XX was detected in two of 20 metaphases, and the percentage of cells with female karyotype subsequently increased. On day 519, all metaphases showed female karyotype. BCR-ABL mRNA and Philadelphia chromosome were never detected throughout her post-transplant course. Fluorescence in situ hybridization (FISH) revealed complete recovery of host-derived hematopoiesis in the bone marrow, however, mixed T cell chimerism in the peripheral blood. This suggests that the persistence of donor-derived T cells may prevent disease recurrence through graft-versus-leukemia effect. The patient remains in a molecular complete remission with host-derived hematopoiesis 749 days post-transplant.

Changes in descemet membrane and endothelium after corneal epithelial abrasion alone and with photorefractive keratectomy in rabbits

OBJECTIVES

To investigate the effects of epithelial abrasion on the corneal endothelium and Descemet membrane in rabbits and to compare the changes with those after excimer laser photoablation of the cornea.

METHODS

Central epithelial abrasions, 6 mm in diameter, were created by mechanical removal of the cells, and the specimens were examined from 24 hours up to 30 days by transmission electron microscopy. Corneas that were photoablated by an excimer laser and nontreated normal corneas were investigated as controls.

RESULTS

Corneas denuded of epithelium showed massive enlargement of the mitochondria in the endothelium and exhibited a layer of electron-dense fibrillogranular material that had migrated forward through the Descemet membrane. These alterations were similar to the changes observed after photoablation of the cornea by an excimer laser.

CONCLUSION

It was postulated that the extrusion of electron-dense material in the Descemet membrane observed after excimer laser ablation might have occurred primarily not as a result of shock waves, but from destruction of the epithelial integrity.

Isolation of a new superantigen with potent mitogenic activity to murine T cells from Streptococcus pyogenes

A mitogenic substance on murine lymphocytes was detected in the culture supernate of Streptococcus pyogenes type 12 strain. This substance had a molecular weight of 28,000 and pI 9.2, and was designated as S. pyogenes mitogen (SPM). The proliferative response of C3H/HeN spleen cells began at 1 ng ml-1 and reached a maximal response at 100 ng ml-1 of SPM for 4 days culture. Anti-Thy 1.2 mAb and complement-treated spleen cells abrogated the proliferative response to any dose of SPM. Although the anti-major histocompatibility complex class 1 mAbs had no blocking effect on proliferation by SPM, this proliferation was substantially inhibited by the addition of either anti-I-A or anti-I-E mAb, and complete inhibition was produced by the addition of both mAbs. Fixed antigen-presenting cells still induced T cell proliferation by SPM. A significant expansion of T cells bearing V beta 13 T-cell receptor was observed up to 73% among the Thy 1.2+ cells in cultures stimulated with SPM, indicating expansion in a V beta-specific manner. Immunoblotting of IEF-separated proteins showed that anti-streptococcal pyrogenic exotoxin (SPE) C reacted with a protein of pI 6.9 and anti-SPEB did not show any reactivity. SPEA was reported to expand V beta 8.1 and 8.2 bearing murine T cells, and SPM did not. SPM also exhibited potent mitogenic activity on human T cells and V beta 21+ T cells were selectively expanded. These results lead to the conclusion that SPM was neither SPEA, B nor C, but a new protein belonging to a group of streptococcal superantigens with activity on not only human but also murine lymphocytes.

5-Fluorouracil induces apoptotic cell death with G2 phase arrest in human breast cancer grafted in nude mice

Treatment with 5-fluorouracil and its derivatives causes DNA double strand breaks in the S phase, and the subsequent cell death. A 5-Fluorouracil derivative (UFT), that is converted to 5-fluorouracil in vivo, was administered orally at a dose of 18 mg/kg/day to nude mice bearing human breast cancer for 28 consecutive days. The tumors on day 7, 14, 21, and 28 after treatment were examined histopathologically and by flow cytometric cell cycle analysis. UFT treatment achieved remarkable inhibition of tumor growth, and histological examination revealed significantly less mitotic figures and more apoptotic bodies throughout the treated tumors, compared to the controls. Flow cytometric study showed changes in the cell cycle outflow of treated tumor cells, involving reduced numbers of G1 phase cells and increased numbers of S and G2 phase cells, compared to the corresponding controls. The reduced growth of tumors induced by UFT is attributable to a rise in apoptotic cell death as well as a decline in producing daughter cells, i.e. mitotic activity, and 5-fluorouracil may act cytotoxically on cancer cells via apoptosis, followed by arrest at G2 phase.