Transxiphoid approach for intracardiac repair using video-assisted cardioscopy

Video-assisted cardioscopy (VAC) is a novel tool for providing clear visualization of small intracardiac structures and achieving complete repair in minimally invasive surgery. Between July 1999 and July 2000, 12 patients with atrial septal defect and ventricular septal defect underwent surgical repair using a combined procedure with the transxiphoid approach and VAC in our institution. The mean skin incision was 5.4 cm, and the postoperative courses of all the patients were uneventful without any complications. The mean hospital stay was 8.3 days and 1 patient (8.3%) needed blood products. Our experience showed the technical feasibility and acceptable surgical results of transxiphoid approach using a VAC.

Expression of 74-kDa histidine decarboxylase protein in a macrophage-like cell line RAW 264.7 and inhibition by dexamethasone

Stimulation of RAW 264.7 cells with the Ca(2+)-ATPase inhibitor thapsigargin increased histamine production. Immunoblot analyses revealed that thapsigargin increased the expression of 74-kDa histidine decarboxylase protein although rat mast cell line RBL-2H3 cells express both 74- and 53-kDa histidine decarboxylase proteins. The inhibition of histamine production by the mitogen-activated protein kinase-extracellular signal-regulated kinase kinase (MEK) inhibitors PD98059 (2'-amino-3'-methoxyflavone) and U0126 (1,4-diamino-2,3-dicyano-1,4-bis(2-aminophenylthio)butadiene) and by the p38 mitogen-activated protein (MAP) kinase inhibitor SB203580 (4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole) was correlated with the inhibition of the expression of thapsigargin-induced 74-kDa histidine decarboxylase protein. The synthetic glucocorticoid dexamethasone inhibited thapsigargin-induced histamine production and 74-kDa histidine decarboxylase protein expression. The thapsigargin-induced activation of p42/p44 MAP kinase and p38 MAP kinase was also inhibited by dexamethasone. These findings indicate that the induction of histamine production by thapsigargin in RAW 264.7 cells is due to the increased expression of 74-kDa histidine decarboxylase protein and that dexamethasone inhibits thapsigargin-induced histidine decarboxylase protein expression and histamine production via inhibition of MAP kinase activation.

Measurement of B(0)(d)-B_(0)(d) mixing rate from the time evolution of dilepton events at the upsilon(4S)

We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations.

Anti-tumor promoting activity of bufadienolides from Kalanchoe pinnata and K. daigremontiana x tubiflora

Five bufadienolides (1-5) isolated from the leaves of Kalanchoe pinnata and K. daigremontiana x tubiflora (Crassulaceae) were examined for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation in Raji cells induced by the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate. All bufadienolides showed inhibitory activity, and bryophyllin A (1) exhibited the most marked inhibition (IC50 = 0.4 microM) among the tested compounds. Bryophyllin C (2), a reduction analogue of 1, and bersaldegenin-3-acetate (3) lacking the orthoacetate moiety were less active. These results strongly suggest that bufadienolides are potential cancer chemopreventive agents.

Experimental study of small arterial anastomosis with gelatin-resorcin-formaldehyde glue and collagen sheet

In cardiovascular surgery, the manual continuous suture has often been used for microvascular anastomosis, but the luminal irregularity often causes thrombotic stenosis in the anastomosis sites. The purpose of this study was to examine the feasibility of the combined use of gelatin-resorcin-formaldehyde (GRF) glue and a collagen sheet for the anastomosis of small arteries 3 to 4 mm in diameter in experimental animals. End-to-end anastomoses of the carotid and femoral arteries of mongrel dogs were carried out with the combined use of GRF glue and collagen sheet. The physical strength of the anastomosis, the histopathologic condition of the vassels, and the absorptivity and the inflammatory response of the glue were evaluated. The physical strength of the anastomosis sites was good and their flexibility optimal, the smooth luminal surface appeared excellent for preventing thrombotic stenosis in all follow-up periods, and the glue was absorbed almost completely within 12 weeks postoperatively. The combined use of GRF glue and collagen sheet would be feasible for the anastomosis of small arteries 3 to 4 mm in diameter and could substitute for the conventional suture method.

Photodynamic antisense regulation of human cervical carcinoma cell growth using psoralen-conjugated oligo(nucleoside phosphorothioate)

The antisense strategy has been applied to regulate gene expression in a sequence specific manner, which enables suppression of the proliferation of cancer cells and exploration of the functions of unknown genes. In order to generalize and to enhance the ability of the strategy, functionalization of antisense DNAs was done using a photo-crosslinking reagent, 4,5',8-trimethylpsoralen, and the possibility of photodynamic antisense regulation of gene expression was examined. Psoralen-conjugated oligo(nucleoside phosphorothioate)s (Ps-S-oligo) were prepared and used to inhibit the proliferation of human cervical carcinoma cells. Upon UVA irradiation of Ps-S-oligo treated cells, Ps-S-oligo complementary to the initiation codon region (Ps-P-As) of HPV18-E6*-mRNA of human cervical carcinoma cells inhibited drastically the cell growth (IC(50)=16 nM). In contrast, Ps-S-oligo with mismatched sequences and scrambled one showed lesser inhibitory effects than Ps-P-As. These results showed that the inhibition by Ps-S-oligo was dependent on (a) sequence, (b) UVA irradiation, (c) concentration and (d) cell line. The amount of intact HPV18-E6*-mRNA was decreased in a sequence dependent manner, indicating that the antiproliferative effect of Ps-P-As was an antisense manner. The psoralen-conjugated antisense DNA has significant potential to regulate gene expression, which may provide useful information to explore the novel gene regulating reagents.

Conserved smooth muscle contractility and blood pressure increase in response to high-salt diet in mice lacking the beta3 subunit of the voltage-dependent calcium channel

Voltage-dependent calcium channels are crucially important for calcium influx and the following smooth muscle contraction. Beta subunits of these channels are known to modify calcium currents through pore-forming alpha subunits. Among the four reported independent beta subunits, the beta3 subunit is expressed in smooth muscle cells and thought to compose L-type calcium channels in the tissue. To determine the role of the beta3 subunit in the cardiovascular system, we have analyzed beta3-null mice. Electrophysiological examinations proved the existence of dihydropyridine (DHP)-sensitive. L-type calcium channels in the smooth muscle cells. Beta3-null mice show no apparent changes in smooth muscle contraction and sensitivity to DHP, and normal blood pressure when they are raised on a normal diet, but the 13 subunit deficient mice show elevated blood pressure in response to a high-salt diet, with significant reductions in plasma catecholamine concentrations. Our finding strongly suggests a close relationship between voltage-dependent channels and high blood pressure.

Measurement of the CP violation parameter sin2 phi(1) in B(0)(d) meson decays

We present a measurement of the standard model CP violation parameter sin2 phi(1) (also known as sin2beta) based on a 10.5 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) collider. One neutral B meson is reconstructed in the J/psiK(S), psi(2S)K(S), chi(c1)K(S), eta(c)K(S), J/psiK(L), or J/psipi(0) CP-eigenstate decay channel and the flavor of the accompanying B meson is identified from its charged particle decay products. From the asymmetry in the distribution of the time interval between the two B-meson decay points, we determine sin2 phi(1) = 0.58(+0.32)(-0.34)(stat)+0.09-0.10(syst).

Ligands for peroxisome proliferator-activated receptors alpha and gamma inhibit chemically induced colitis and formation of aberrant crypt foci in rats

The biological role of the peroxisome proliferator-activated receptors (PPARs) in various diseases, including inflammation and cancer, has been highlighted recently. Although PPARgamma ligands have been found to inhibit mammary carcinogenesis in rodents, the effects on colon tumorigenesis are controversial. In the present study, three different experiments were conducted to investigate the modifying effects of PPARs ligands (PPARalpha and PPARgamma) on colitis and an early phase of colitis-related colon carcinogenesis in male F344 rats. In the first experiment, gastric gavage of troglitazone (PPARgamma ligand, 10 or 100 mg/kg body weight) or bezafibrate (PPARalpha ligand, 10 or 100 mg/kg body weight) inhibited colitis induced by dextran sodium sulfate (DSS) and lowered trefoil factor-2 content in colonic mucosa. In the second experiment, dietary administration (0.01 or 0.05% in diet) of troglitazone and bezafibrate for 4 weeks significantly reduced azoxymethane (AOM, two weekly s.c. injections, 20 mg/kg body weight)-induced formation of aberrant crypts foci, which are precursor lesions for colon carcinoma. In the third experiment, dietary administration (0.01% in diet for 6 weeks) of pioglitazone (PPARgamma ligand), troglitazone, and bezafibrate effectively suppressed DSS/AOM-induced ACF. Administration of both ligands significantly reduced cell proliferation activity in colonic mucosa exposed to DSS and AOM. Our results suggest that synthetic PPARs ligands (PPARalpha and PPARgamma) can inhibit the early stages of colon tumorigenesis with or without colitis.

Novel adhesion prevention membrane based on a bioresorbable copoly(ester-ether) comprised of poly-L-lactide and Pluronic: in vitro and in vivo evaluations

Block copolymers consisting of poly(L-lactide) (PLLA) and poly(oxyethylene-co-oxypropylene), with various compositions, were synthesized and characterized in vitro and in vivo for their application as postoperative adhesion prevention membranes. It was found that the flexibility and degradability of the cast films of the block copolymers grew with increasing Pluronic F68 [PN; poly(oxyethylene-co-oxypropylene] composition. The receding contact angle of the copolymer films against water became lower than that of the PLLA film, because the surface was predominantly covered with more hydrophilic PN segments in a wet state. This surface property significantly affects the cell attachment property of the copolymer films, and the fibroblasts cultured on the films exhibit a spheroid-like morphology. The copolymer films subcutaneously implanted in the back of rats induced milder tissue responses compared with PLLA homopolymers, because of the increased surface hydrophilicity in the former. In vivo evaluation using a uterus horn model in rats revealed that the performance of these copolymer films as an adhesion-prevention membrane is comparable to that of a conventionally utilized membrane of oxidized regenerated cellulose. These results indicate that the copolymer films are biocompatible materials with controllable mechanical properties and biodegradability as adhesion-prevention membranes.

In vitro absorption and metabolism of a citrus chemopreventive agent, auraptene, and its modifying effects on xenobiotic enzyme activities in mouse livers

We previously reported that auraptene (7-geranyloxycoumarin, AUR), widely occurring in citrus fruit, is a structurally novel type of effective cancer-preventive agent, as manifested in several rodent models. However, its bio-availability and metabolism in biological systems have yet to be investigated. In the present study, we examined the chemical stability of AUR at pH 1.57 and 37 degrees C (as a stomach digestion model) and observed its stoichiometric conversion to umbelliferone [7-hydroxycoumarin, UMB; half-life (t1/2) = 15 h; 7-ethoxycoumarin (ETC) was stable for 24 h]. Differentiated Caco-2 cells, a human colorectal adenocarcinoma cell line, were used as a small intestine model. ETC permeated the basolateral (portal vein) side of Caco-2 cells in a time-dependent manner; AUR slightly permeated the cells, but with an intracellular accumulation. Epoxyauraptene and UMB were detected when AUR was treated with the rat liver S-9 mixture. ETC was also converted to UMB, but its t1/2 of two hours was much shorter than that of AUR (> 24 h). This suggests that AUR, bearing a geranyloxyl side chain, is a relatively metabolism-resistant substrate for cytochrome P-450 enzymes and, thus, is stable in the liver compared with ETC. Oral administration of AUR by gavage at 50-200 mg/kg body wt dose dependently induced glutathione S-transferase (GST) activity in mouse livers without affecting cytochrome P-450 activity. Using 10 coumarin-related compounds, we found that only those coumarins having a 7-alkyloxyl group induced GST, but not cytochrome P-450, activity. The present study presumes that AUR accumulates in the epithelial cells of the small intestine and then gradually permeates into the portal vein. Stable localizability of AUR in the colon and liver may be associated with the induction of GST activity, which is important as the action mechanism for suppression of rodent chemical carcinogenesis.

Changes in T-cell receptor subsets after cardiac surgery in children

T cells are divided into two subsets, alphabeta and gammadelta, according to the T-cell receptor (TCR) expressed. Recent findings indicate that gammadelta T cells serve as the first defense against microbial pathogens, and represent a link between innate and acquired immunity. We conducted a study to investigate the changes in circulating TCR subsets after cardiac surgery in children. Blood samples from 24 children who underwent cardiac surgery with cardiopulmonary bypass (CPB) were collected serially to analyze TCR subsets by flow cytometry. The alphabeta T cells reached a nadir on postoperative day (POD) 1, but recovered to pre-CPB levels on POD 3. On the other hand, the gammadelta T cells decreased after CPB and did not recover to pre-CPB levels even after POD 7. The alphabeta/gammadelta T-cell ratio was increased after POD 3. In children, gammadelta T cells recover more slowly than alphabeta T cells after cardiac surgery. These changes in TCR subsets may contribute to postoperative immunosuppression.

[On the educational benefits of biological sciences in space]

Experimental results in Space Sciences are getting accumulated. It may be advisable for the educational activities of our society that we inform young people, not only of each experimental result, but also of a variety of novel views of life and the world introduced by the researches in Biological Sciences in Space. We are going to provide a data-base including elementary words and concepts in these fields.

Suppression of a squamous cell carcinoma (SCC)-related serpin, SCC antigen, inhibits tumor growth with increased intratumor infiltration of natural killer cells

Squamous cell carcinoma (SCC) antigen (SCCA), a member of the ovalbumin serine proteinase inhibitor family, serves as a circulating marker of squamous cell carcinoma (SC). One of the SCCAs, SCCA1, has been suggested to play a role in the attenuation of apoptosis in vitro and in the augmentation of tumor growth in vivo. In the present study, the infection of a SCC cell line (SKG IIIa) with recombinant retrovirus that expressed the antisense SCCA mRNA suppressed expression of SCCA in vitro. Local administration of this retrovirus into tumors by inoculation in nude mice suppressed tumor growth. Treatment of tumor tissue in vivo is also associated with increased numbers of apoptotic tumor cells and large mononuclear cells in the tumor. To test the possible role of SCCA in the infiltration of large mononuclear cells, we analyzed the effect of SCCA1 on migration of natural killer (NK) cells induced by monocyte-chemoattractant protein-1 in vitro. SCCA1 suppressed migration of NK cells completely, and this inhibitory effect was lost by mutation of the reactive site loop of SCCA1. These results suggest that antisense SCCA may suppress the growth of SCC in vivo not only by the augmentation of intracellular apoptosis but also by the increased infiltration of NK cells into the tumor.

Light irradiation induces fragmentation of the plasmodium, a novel photomorphogenesis in the true slime mold Physarum polycephalum: action spectra and evidence for involvement of the phytochrome

A new photomorphogenesis was found in the plasmodium of the true slime mold Physarum polycephalum: the plasmodium broke temporarily into equal-sized spherical pieces, each containing about eight nuclei, about 5 h after irradiation with light. Action spectroscopic study showed that UVA, blue and far-red lights were effective, while red light inhibited the far-red-induced fragmentation. Difference absorption spectra of both the living plasmodium and the plasmodial homogenate after alternate irradiation with far-red and red light gave two extremes at 750 and 680 nm, which agreed with those for the induction and inhibition of the fragmentation, respectively. A kinetic model similar to that of phytochrome action explained quantitatively the fluence rate-response curves of the fragmentation. Our results indicate that one of the photoreceptors for the plasmodial fragmentation is a phytochrome.

Squamous cell carcinoma antigen suppresses radiation-induced cell death

Previous study has demonstrated that squamous cell carcinoma antigen (SCCA) 1 attenuates apoptosis induced by TNF alpha, NK cell or anticancer drug. In this study, we have examined the effect of SCCA2, which is highly homologous to SCCA1, but has different target specificity, against radiation-induced apoptosis, together with that of SCCA1. We demonstrated that cell death induced by radiation treatment was remarkably suppressed not only in SCCA1 cDNA-transfected cells, but also in SCCA2 cDNA-transfected cells. In these transfectants, caspase 3 activity and the expression of activated caspase 9 after radiation treatment were suppressed. Furthermore, the expression level of phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) was suppressed compared to that of the control cells. The expression level of upstream stimulator of p38 MAPK, phosphorylated MKK3/MKK6, was also suppressed in the radiation-treated cells. Thus, both SCCA1 and SCCA2 may contribute to survival of the squamous cells from radiation-induced apoptosis by regulating p38 MAPK pathway.

Pulmonary atresia, ventricular septal defect, and coronary-pulmonary artery fistula

We report 2 patients with pulmonary atresia, ventricular septal defect, and coronary-pulmonary fistula. The fistula originated from the left anterior descending artery in 1 patient, and from the right coronary artery in the other. Both patients survived staged correction in which right ventricular outflow was reconstructed with autologous fistula tissue. One patient with pulmonary hypertension suddenly died 9 months after surgery. Twenty-four patients with pulmonary atresia, ventricular septal defect, and coronary-pulmonary fistula have been reported previously.

Nondenaturing two-dimensional electrophoretic analysis of loop-sheet polymerization of serpin, squamous cell carcinoma antigen-2

Two homologous serine proteinase inhibitors (serpins), squamous cell carcinoma (SCC) antigen-1 and -2 were separated by nondenaturing two-dimensional electrophoresis combined with immunostaining to acquire further information on these proteins under physiological conditions. Polymers of SCC antigen-2 were detected in cytosolic extracts prepared from tumor tissues. The polymer formation of SCC antigen-2 was apparently decreased and the SCC antigen-2-synthetic peptide binary complexes were newly formed by the addition of synthetic peptide with sequences corresponding to residues from P14 to P2 in the reactive center loop of SCC antigen-2. On the other hand, the incubation with synthetic peptides having the sequence of the reactive center loop of SCC antigen-1 or antithrombin had no effect on polymerization of SCC antigen-2. These data suggest that the polymerization of SCC antigen-2 may occur spontaneously in vivo by the loop-sheet mechanism of serpin.

Apoptosis induced by 1'-acetoxychavicol acetate in Ehrlich ascites tumor cells is associated with modulation of polyamine metabolism and caspase-3 activation

The efficacy of the antitumor activity of 1'-acetoxychavicol acetate (ACA), reported to be a suppressor of chemically induced carcinogenesis, was evaluated in Ehrlich ascites tumor cells. ACA treatment resulted in changes in morphology and a dose-dependent suppression of cell viability. Apoptosis, characterized by nuclear condensation, membrane blebbing, cell shrinkage and a significant induction of caspase-3-like protease activity at 8 h in a time-course study were observed. Formation of apoptotic bodies was preceded by lowering of intracellular polyamines, particularly putrescine, and both dose- and time-dependent inhibitory and activation effect by ACA on ornithine decarboxylase (ODC) and spermidine/spermine N(1)-acetyltransferase (SSAT), respectively. Administration of exogenous polyamines prevented ACA-induced apoptosis represented by a reduction in the number of apoptotic bodies and also caused reduction in the induced caspase-3-like protease activity at 8 h. These findings suggest that the anticarcinogenic effects of ACA might be partly due to perturbation of the polyamine metabolic pathway and triggering of caspase-3-like activity, which result in apoptosis.

Effect of electrolyzed water on wound healing

Electrolyzed water accelerated the healing of full-thickness cutaneous wounds in rats, but only anode chamber water (acid pH or neutralized) was effective. Hypochlorous acid (HOCl), also produced by electrolysis, was ineffective, suggesting that these types of electrolyzed water enhance wound healing by a mechanism unrelated to the well-known antibacterial action of HOCl. One possibility is that reactive oxygen species, shown to be electron spin resonance spectra present in anode chamber water, might trigger early wound healing through fibroblast migration and proliferation.

Nitric oxide synthase is induced in tumor promoter-sensitive, but not tumor promoter-resistant, JB6 mouse epidermal cells cocultured with interferon-gamma-stimulated RAW 264.7 cells: the role of tumor necrosis factor-alpha

Expression of inducible nitric oxide synthase (iNOS) has been reported to be involved in certain organs of potential tumorigenesis, including the stomach and colon. The mechanisms for iNOS expression in epithelial cells, however, are not fully understood. In the present study, we investigated the role of macrophages in epithelial iNOS expression by coculturing a stimulated murine macrophage-like cell line, RAW 264.7, with either tumor promoter-sensitive (P+) or promoter-resistant (P-) JB6 murine epidermal cells. After monoculture, treatment of RAW 264.7 cells with IFN-gamma for 24 h generated a large amount of nitrite (NO2-), as reported previously, whereas no increase in NO2- concentration was observed in the IFN-gamma-treated P+ or P-subclones. Interestingly, when IFN-gamma-treated RAW 264.7 cells were cocultured with P+ but not P- cells, we observed a marked increase in NO2- concentration (30.8+/-3.6 microM), which significantly exceeded (P < 0.01) the sum of the concentrations (20.0+/-2.3 microM) added from each cell line monoculture. Western blotting analysis revealed that, after coculture, iNOS protein was up-regulated 55-fold more than the control in JB6 P+ but not in P- cells. IFN-gamma-treated RAW 264.7 cells secreted proinflammatory cytokines, including tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta. The addition of IFN-gamma-treated RAW 264.7 cell-conditioned media to P+ subclones led to a significant enhancement of NO2- formation that was diminished by the TNF-alpha-specific but not IL-1beta-specific antibody. When combined with IFN-gamma, the recombinant TNF-alpha (1-100 ng/ml) enhanced NO2- formation in JB6 P+ cells, whereas IL-1beta (1-100 ng/ml) did not. These results led us to conclude that IFN-gamma-treated RAW 264.7 cells release TNF-alpha to induce iNOS expression in promoter-sensitive JB6 cells. Thus, we propose the hypothesis that macrophages stimulate neoplastic cells with TNF-alpha via a paracrine loop to induce epithelial iNOS protein expression.

Characterization of fission yeast cohesin: essential anaphase proteolysis of Rad21 phosphorylated in the S phase

Cohesin complex acts in the formation and maintenance of sister chromatid cohesion during and after S phase. Budding yeast Scc1p/Mcd1p, an essential subunit, is cleaved and dissociates from chromosomes in anaphase, leading to sister chromatid separation. Most cohesin in higher eukaryotes, in contrast, is dissociated from chromosomes well before anaphase. The universal role of cohesin during anaphase thus remains to be determined. We report here initial characterization of four putative cohesin subunits, Psm1, Psm3, Rad21, and Psc3, in fission yeast. They are essential for sister chromatid cohesion. Immunoprecipitation demonstrates stable complex formation of Rad21 with Psm1 and Psm3 but not with Psc3. Chromatin immunoprecipitation shows that cohesin subunits are enriched in broad centromere regions and that the level of centromere-associated Rad21 did not change from metaphase to anaphase, very different from budding yeast. In contrast, Rad21 containing similar cleavage sites to those of Scc1p/Mcd1p is cleaved specifically in anaphase. This cleavage is essential, although the amount of cleaved product is very small (<5%). Mis4, another sister chromatid cohesion protein, plays an essential role for loading Rad21 on chromatin. A simple model is presented to explain the specific behavior of fission yeast cohesin and why only a tiny fraction of Rad21 is sufficient to be cleaved for normal anaphase.

Apoptosis after butyrate-induced differentiation in retinoblastoma cell line Y-79

PURPOSE

To study the fate of Y-79 human retinoblastoma cells after induction of differentiation.

METHODS

Y-79 cells were cultured in a synthetic medium and were induced to neuronal differentiation by butyrate treatment. Neurofilaments, p53, and DNA-synthesizing nuclei labeled with 5-bromodeoxyuridine were immunostained, and apoptotic cells were labeled by in situ DNA nick end labeling (TUNEL). We combined these immunostaining and labeling methods to determine whether the cells expressed these markers at the same time. DNA fragmentation and p53 levels were also determined by electrophoresis.

RESULTS

Y-79 cells proliferated in the synthetic medium. After butyrate treatment, they extended protrusions and increased neurofilament immunoreactivity. The differentiated features were striking on day 7. Thereafter, differentiated cells decreased and apoptotic cells increased. DNA synthesis was detected in the cells expressing immunoreactivity for neurofilaments or p53. At day 7, most of the cells with p53-positive nuclei were alive and neurofilament-positive. However at day 10, the p53-positive cells were apoptotic and neurofilament-positive apoptotic cells accumulated.

CONCLUSIONS

We conclude that the Y-79 cells express p53 and undergo apoptosis after neuronal differentiation. There could be a p53-dependent apoptotic pathway in butyrate-induced differentiated Y-79 cells due to the inability to regulate cell cycling.