Biomedical subjects

J K Chen

Publications and source records attributed to J K Chen.

At least 19 recordsLinked to original sources

PubMed2004

Multi-resolution image fusion technique and its application to forensic science.

Image fusion is a process of combining two or more images into an image. It can extract features from source images, and provide more information than one image can. Multi-resolution analysis plays an important role in image processing, it provides a technique to decompose an image and extract information from coarse to fine scales. In some practical forensic examinations (such as the cartridge image check), we cannot obtain all information from just one image; on the contrary, we need information from images with difference light sources (or light ways). In this paper, we apply an image fusion method based on multi-resolution analysis to forensic science. Synthetic and real images (such as images from closed-up photography and flash photography) are used to show the capability of the multi-resolution image fusion technique.

Crime↗

PubMed2003

Genetic diversity in the northernmost Oryza rufipogon populations estimated by SSR markers.

To estimate genetic diversity of the residual northern populations of Oryza rufipogon, a total of 232 individuals from six populations were analyzed using microsatellites (SSRs). The O. rufipogon populations with different status included three from Dongxiang (Jiangxi Province) and three from Chaling (Hunan Province) in China. The 23 rice SSR primer pairs selected from the RiceGenes Database detected a total of 115 alleles, indicating that all the SSR loci were polymorphic in this study. The total gene diversity was 0.919 in the six O. rufipogon populations, and the Donxiang populations showed higher diversity than the Chaling populations. More significant genetic differentiation and less gene flow were found among the Dongxiang populations than those from Chaling. The two putative introgressed populations showed relatively high genetic variation. One in situ conserved population from Dongxiang had the lowest level of genetic diversity. The re-introduced population from Chaling restored about 90% of the genetic variation, compared with the original source population. It is concluded from these results that a relatively high level of genetic variation resided in the northern O. rufipogon populations and continued efforts of conservation of these populations are needed; and that the conservation of some Chaling and Dongxiang populations has been effective in preventing gene flow from cultivated rice. Introgression of cultivated rice demonstrated significant impacts on genetic variability of the O. rufipogon populations, and should be carefully considered in conserving this wild rice. This study also suggested that re-introduction to its original habitats is an effective approach to restore O. rufipogon populations.

Base Sequence↗

PubMed2003

Visualizing caveolin-1 and HDL in cholesterol-loaded aortic endothelial cells.

Caveolae are vesicular invaginations of the plasma membranes that regulate signal transduction and transcytosis, as well as cellular cholesterol homeostasis. Our previous studies indicated that the removal of cholesterol from aortic endothelial cells and smooth muscle cells in the presence of HDL is associated with plasmalemmal invaginations and plasmalemmal vesicles. The goal of the present study was to investigate the location and distribution of caveolin-1, the main structural protein component of caveolae, in cholesterol-loaded aortic endothelial cells after HDL incubation. Confocal microscopic analysis demonstrated that the caveolin-1 appeared to colocalize with HDL-fluorescein 1,1'-dioctadecyl 3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) conjugates on the cell surface. No free HDL-DiI conjugates were revealed in the cytoplasm. Immunoelectron microscopy further demonstrated that caveolin-1 gold (15 nm) conjugates colocalized with HDL gold (10 nm) conjugates in the plasmalemmal invaginations. These morphological results indicated that caveolae are the major membrane domains facilitating the transport of excess cholesterol to HDL on the cell surface of aortic endothelial cells.

Animals↗

PubMed2003

Ex vivo gene therapy in autologous bone marrow stromal stem cells for tissue-engineered maxillofacial bone regeneration.

This study examines the clinical relevance of tissue engineering integrating gene therapy and polymer science to bone regeneration. Bilateral maxillary defects (3 x 1.2 cm(2)) in 20 miniature swine were bridged with a bioresorbable internal splint. Constructs were created using ex vivo adenovirus bone morphogenetic protein (BMP)-2-mediated gene transfer to the expanded bone marrow mesenchymal stem cells (MSCs) 7 days before implantation. Controls were performed using adenovirus beta-galactosidase. The BMP-2 cell/construct displayed white solid bone formation after 3 months. Meanwhile, the hematoxylin and eosin and Von Kossa stains demonstrated exhibited mature woven bone with good mineralization. Additionally, three-dimensional computer tomography imaging revealed a nearly complete infraorbital rim repair. Quantitative analysis demonstrated a significant difference (P<0.001) in bone formation. Finally, biomechanical testing revealed no statistically significant difference in the maximal compressive strength of new bone formed by BMP-2 cell constructs and the normal maxilla. The data evidenced de novo bone formation capable of sustaining axial compressive loads. The measurement results showed that ex vivo replication defective adenovirus-mediated human BMP-2 gene transfer to MSCs enhances autologous bone formation in the repair of maxillary defects.

Adenoviridae↗

PubMed2001

Beneficial effects of astringinin, a resveratrol analogue, on the ischemia and reperfusion damage in rat heart.

Oxidative stress plays an important role in the pathogenesis of myocardial ischemia and infarction. Antioxidants might then be beneficial in the prevention of these diseases. Astringinin (3,3',4',5-tetrahydroxystilbene), a resveratrol (3,4',5-trihydroxystilbene) analogue with considerably higher antioxidative activity and free radical scavenging capacity, was introduced to examine its cardioprotective effects in ischemia or ischemia-reperfusion (I/R) rats. In the present study, the left main coronary artery was occluded by the following procedures: (i) 30 min occlusion, (ii) 5 min occlusion followed by 30 min reperfusion, and (iii) 4 h occlusion. Animals were infused with and without astringinin before coronary artery occlusion. Mortality, and the severity of ischemia- and I/R-induced arrhythmias were compared. Pretreatment of astringinin dramatically reduced the incidence and duration of ventricular tachycardia (VT) and ventricular fibrillation (VF) during either ischemia or I/R period. Astringinin at 2.5 x 10(-5) and 2.5 x 10(-4) g/kg completely prevented the mortality of animals during ischemia or I/R. During the same period, astringinin pretreatment also increased nitric oxide (NO) and decreased lactate dehydrogenase (LDH) levels in the carotid blood. In animals subjected to 4 h coronary occlusion, the cardiac infarct size (expressed as a percentage of occluded zone) was reduced from 44.4 + or - 4.1% to 19.1 + or - 2.4% by astringinin (2.5 x 10(-4) g/kg). We conclude that, astringinin is a potent antiarrhythmic agent with cardioprotective activity in ischemic and ischemic-reperfused rat heart. The beneficial effects of astringinin in the ischemic and ischemic-reperfused hearts may be correlated with its antioxidant activity and upregulation of NO production.

Animals↗

PubMed2001

Detection of DNA strand breaks, DNA-protein crosslinks, and telomerase activity in nickel-transformed BALB/c-3T3 cells.

Although nickel compounds are known carcinogens, the underlying carcinogenic mechanisms are not fully understood. The objective of this research was to determine if the genotoxic lesions of DNA strand breaks and DNA-protein crosslinks are present in nickel-transformed BALB/c-3T3 cells, and to further elucidate the potential carcinogenesis of insoluble and soluble nickel compounds through telomerase activity in nickel-transformed BALB/c-3T3 cell lines. DNA strand breaks, DNA-protein crosslinks and telomerase activity were investigated by single cell gel electrophoresis (comet assay), (125)I-postlabelling techniques, and the TRAP-silver staining assay, respectively. Results showed that both DNA strand breaks and DNA-protein crosslinks were present in nickel-transformed BALB/c-3T3 cells. However, the highest levels of DNA strand breaks and DNA-protein crosslinks were found in insoluble crystalline NiS-transformed cells and high levels of DNA strand breaks and DNA-protein crosslinks were also found in the transformed cells induced by two water-soluble NiCl(2) and NiSO(4) at moderate concentrations of cytotoxicity. These data suggest that these two genetic endpoints are useful biomarkers and are associated with cell transformation and carcinogensis of insoluble and soluble nickel compounds. Also, we found that the crystalline NiS- and NiCl(2)-transformed cells possessed a high telomerase activity. A weak telomerase was found in NiSO(4)-transformed cells. The results seem to indicate that in addition to crystalline NiS, some water-soluble nickel compounds such as NiCl(2) are also highly carcinogenic. These results may partly explain the cell transformation and relative carcinogenic potency of insoluble crystalline NiS, soluble NiCl(2), and NiSO(4).

3T3 Cells↗

PubMed2001

Margulis' theory on division of labour in cells revisited.

Division of labour is a marked feature of multicellular organisms. Margulis proposed that the ancestors of metazoans had only one microtubule organizing center (MTOC), so they could not move and divide simultaneously. Selection for simultaneous movement and cell division had driven the division of labour between cells. However, no evidence or explanation for this assumption was provided. Why could the unicellular ancestors not have multiple MTOCs? The gain and loss of three possible strategies are discussed. It was found that the advantage of one or two MTOC per cell is environment-dependent. Unicellular organisms with only one MTOC per cell are favored only in resource-limited environments without strong predatory pressure. If division of labour occurring in a bicellular organism just makes simultaneous movement and cell division possible, the possibility of its fixation by natural selection is very low because a somatic cell performing the function of an MTOC is obviously wasting resources. Evolutionary biologists should search for other selective forces for division of labour in cells.

Cell Division↗

PubMed2001

New frontiers in diagnostic imaging in concussive head injury.

Concussed athletes may have documented incapacitating postconcussive symptoms, neuropsychological deficits, and consequent important changes in their lives and sport, yet the majority of neuroimaging attempts reveal few findings to account for these signs and symptoms. In this paper, we explore new techniques in the neuroimaging of concussion including diffusion-weighted magnetic resonance imaging and functional brain imaging technology.

Athletic Injuries↗

PubMed2001

Cytochrome p450 epoxygenase metabolism of arachidonic acid inhibits apoptosis.

The ubiquitous cytochrome P450 hemoproteins play important functional roles in the metabolism and detoxification of foreign chemicals. However, other than established roles in cholesterol catabolism and steroid hormone biosynthesis, their cellular and/or organ physiological functions remain to be fully characterized. Here we show that the cytochrome P450 epoxygenase arachidonic acid metabolite 14,15-epoxyeicosatrienoic acid (14,15-EET) inhibits apoptosis induced by serum withdrawal, H(2)O(2), etoposide, or excess free arachidonic acid (AA), as determined by DNA laddering, Hoechst staining, and fluorescein isothiocyanate-labeled annexin V binding. In the stable transfectants (BM3 cells) expressing a mutant bacterial P450 AA epoxygenase, F87V BM3, which was genetically engineered to metabolize arachidonic acid only to 14,15-EET, AA did not induce apoptosis and protected against agonist-induced apoptosis. Ceramide assays demonstrated increased AA-induced ceramide production within 1 h and elevated ceramide levels for up to 48 h, the longest time tested, in empty-vector-transfected cells (Vector cells) but not in BM3 cells. Inhibition of cytochrome P450 activity by 17-octadecynoic acid restored AA-induced ceramide production in BM3 cells. Exogenous C2-ceramide markedly increased apoptosis in quiescent Vector cells as well as BM3 cells, and apoptosis was prevented by pretreatment of Vector cells with exogenous 14,15-EET and by pretreatment of BM3 cells with AA. The ceramide synthase inhibitor fumonisin B1 did not affect AA-induced ceramide production and apoptosis; in contrast, these effects of AA were blocked by the neutral sphingomyelinase inhibitor scyphostatin. The pan-caspase inhibitor Z-VAD-fmk had no effect on AA-induced ceramide generation but abolished AA-induced apoptosis. The antiapoptotic effects of 14,15-EET were blocked by two mechanistically and structurally distinct phosphatidylinositol-3 (PI-3) kinase inhibitors, wortmannin and LY294002, but not by the specific mitogen-activated protein kinase kinase inhibitor PD98059. Immunoprecipitation followed by an in vitro kinase assay revealed activation of Akt kinase within 10 min after 14,15-EET addition, which was completely abolished by either wortmannin or LY294002 pretreatment. In summary, the present studies demonstrated that 14,15-EET inhibits apoptosis by activation of a PI-3 kinase-Akt signaling pathway. Furthermore, cytochrome P450 epoxygenase promotes cell survival both by production of 14,15-EET and by metabolism of unesterified AA, thereby preventing activation of the neutral sphingomyelinase pathway and proapoptotic ceramide formation.

Animals↗

PubMed2001

Angiotensin IV induces tyrosine phosphorylation of focal adhesion kinase and paxillin in proximal tubule cells.

Angiotensin IV (ANG IV), the COOH-terminal hexapeptide fragment of angiotensin II (ANG II), binds to specific sites in the kidney, distinct from type 1 (AT(1)) and type 2 (AT(2)) receptors and designated type 4 (AT(4)) receptors. We determined signaling pathways for ANG IV in a proximal tubular cell line, LLC-PK(1)/Cl(4). In these cells, we found no specific binding of [(125)I]-ANG II. In contrast, ANG IV dose dependently competed for [(125)I]-labeled ANG IV binding, with no displacement by either ANG II, the AT(1) receptor antagonist losartan, or the AT(2) antagonist PD-123319. Saturation binding indicated the presence of AT(4) receptors of high affinity [dissociation constant (K(d)) = 1.4 nM]. ANG IV did not affect cAMP or cGMP production and did not increase cytosolic calcium concentration in these cells. In contrast, immunoprecipitation and immunoblotting studies revealed that ANG IV caused dose-dependent tyrosine phosphorylation of p125-focal adhesion kinase (p125-FAK) and p68-paxillin within 2 min, with maximal stimulation at 30 min. ANG IV-stimulated tyrosine phosphorylation of p125-FAK and paxillin was not affected by pretreatment with either losartan or PD-123319, and ANG II (10(-7) M) did not induce protein tyrosine phosphorylation. Our results indicate that LLC-PK(1)/Cl(4) cells express ANG IV receptors, which we demonstrate for the first time are linked to tyrosine phosphorylation of focal adhesion-associated proteins. This suggests that ANG IV, a product of ANG II metabolism, may regulate function of the focal adhesion complex in proximal tubule cells.

Angiotensin II↗

PubMed2001

Dmrt1 expression is regulated by follicle-stimulating hormone and phorbol esters in postnatal Sertoli cells.

Dmrt1 is a recently described gene that is expressed exclusively in the testis and is required for postnatal testis differentiation. Here we describe the expression of Dmrt1 in postnatal rat testis and Sertoli cells. RNase protection analysis was used to examine Dmrt1 messenger RNA (mRNA) levels in intact testis during postnatal development and in primary cultures of Sertoli cells under various culture conditions. We show that Dmrt1 mRNA levels rise significantly beginning approximately 10 days after birth and remain elevated until after the third postnatal week. Thereafter, mRNA levels drop coincident with the proliferation of germ cells in the testis. In freshly isolated Sertoli cells, Dmrt1 mRNA levels were robust but decreased significantly when the cells were placed in culture for 24 h. Treatment of Sertoli cells with either FSH or 8-bromo-cAMP resulted in a significant rise in Dmrt1 mRNA levels. This cAMP response was sensitive to treatment with the transcriptional inhibitor actinomycin D but not to the translational inhibitor cycloheximide. The cAMP-dependent rise in Dmrt1 mRNA also required activation of protein kinase A, as mRNA induction was sensitive to the inhibitor H89. Studies also show that Dmrt1 expression was inhibited by phorbol esters (PMA) but only modestly effected by serum.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2000

Effects of oncogenic mutations in Smoothened and Patched can be reversed by cyclopamine.

Basal cell carcinoma, medulloblastoma, rhabdomyosarcoma and other human tumours are associated with mutations that activate the proto-oncogene Smoothened (SMO) or that inactivate the tumour suppressor Patched (PTCH). Smoothened and Patched mediate the cellular response to the Hedgehog (Hh) secreted protein signal, and oncogenic mutations affecting these proteins cause excess activity of the Hh response pathway. Here we show that the plant-derived teratogen cyclopamine, which inhibits the Hh response, is a potential 'mechanism-based' therapeutic agent for treatment of these tumours. We show that cyclopamine or synthetic derivatives with improved potency block activation of the Hh response pathway and abnormal cell growth associated with both types of oncogenic mutation. Our results also indicate that cyclopamine may act by influencing the balance between active and inactive forms of Smoothened.

3T3 Cells↗

PubMed2000

Cardioprotective effect of resveratrol, a natural antioxidant derived from grapes.

BACKGROUND: The major objective of the present study was to examine the cardioprotective effect of resveratrol, an antioxidant presents in red wines, in the rat after ischemia and ischemia-reperfusion (I-R). METHODS: The left main coronary artery was occluded for 30 or 5 min followed by a 30-min reperfusion in anesthetized rats. Animals were preinfused with and without resveratrol before occlusion and the severity of ischemia- and I-R-induced arrhythmias and mortality were compared. RESULTS: Resveratrol pretreatment had no effect on ischemia-induced arrhythmias nor on mortality. In contrast, a dramatic protective effects were observed against I-R-induced arrhythmias and mortality. Resveratrol pretreatment both reduced the incidence and duration of ventricular tachycardia (VT) and ventricular fibrillation (VF). During the same period, resveratrol pretreatment also increased nitric oxide (NO) and decreased lactate dehydrogenase levels in the carotid blood. CONCLUSIONS: Resveratrol is a potent antiarrhythmic agent with cardioprotective properties in I-R rats. The cardioprotective effects of resveratrol in the I-R rats may be correlated with its antioxidant activity and upregulation of NO production.

Analysis of Variance↗

PubMed2000

Reconstruction of damaged corneas by transplantation of autologous limbal epithelial cells.

BACKGROUND: Stevens-Johnson syndrome, ocular pemphigoid, and thermal or chemical burns can cause scarring and opacification of the cornea and loss of vision. Transplantation of epithelial cells from the limbus of the contralateral cornea can restore useful vision. However, this procedure requires a large limbal graft from the healthy eye and is not possible in patients who have bilateral lesions. METHODS: We took specimens of limbal epithelial cells from the healthy contralateral eyes of six patients with severe unilateral corneal disease. The epithelial cells were cultured and expanded on amniotic membrane. The amniotic membrane, together with the sheet of limbal epithelial cells, was transplanted to the denuded corneal surface of the damaged eye after superficial keratectomy to remove fibrovascular ingrowth. The mean (+/-SD) follow-up period was 15+/-2 months. RESULTS: Complete reepithelialization of the corneal surface occurred within two to four days of transplantation in all six eyes receiving transplants. By one month, the ocular surface was covered with corneal epithelium, and the clarity of the cornea was improved. In five of the six eyes receiving transplants (83 percent), the mean visual acuity improved from 20/112 to 20/45. In one patient with a chemical burn who had total opacification of the cornea, the acuity improved from the ability to count fingers at 40 cm to 20/200. No patient had recurrent neovascularization or inflammation in the transplanted area during the follow-up period. CONCLUSIONS: Transplantation of autologous limbal epithelial cells cultured on amniotic membrane is a simple and effective method of reconstructing the corneal surface and restoring useful vision in patients with unilateral deficiency of limbal epithelial cells.

Adult↗

PubMed2000

Overexpression of C-terminal Src kinase blocks 14, 15-epoxyeicosatrienoic acid-induced tyrosine phosphorylation and mitogenesis.

We have previously reported that 14,15-epoxyeicosatrienoic acid (14, 15-EET) is a potent mitogen for the renal epithelial cell line, LLCPKcl4. This mitogenic effect is dependent upon activation of a protein-tyrosine kinase cascade that results in activation of mitogen-activated protein kinase and phosphatidylinositol 3-kinase. Because of suggestive evidence that 14,15-EET also activated Src in these cells, we stably transfected LLCPKcl4 with an expression construct of the C-terminal Src kinase (CSK), which inhibits Src family kinase activity. In vitro Src kinase activity assays confirmed that in empty vector-transfected cells (Vector cells), 14, 15-EET increased Src kinase activity, while in clones overexpressing CSK mRNA and immunoreactive protein (CSK cells), 14,15-EET-induced activation of Src was almost completely blocked (94% inhibition). Of interest, epidermal growth factor (EGF) and fetal bovine serum (FBS) also increased Src activity in Vector cells, but not in CSK cells, further confirming the ability of CSK overexpression to prevent Src activation. CSK cells failed to increase [(3)H]thymidine incorporation in response to exogenous 14,15-EET. In contrast, both EGF and FBS significantly increased [(3)H]thymidine incorporation in CSK cells. Immunoprecipitation with anti-phosphotyrosine antibodies and immunoblotting with an antibody against extracellular signal-regulated kinase (ERK) indicated that in CSK cells, 14,15-EET failed to activate ERK1 and ERK2; however, EGF- and FBS-induced activation of ERKs was not different from that seen in Vector cells. In Vector cells, the 14,15-EET-stimulated tyrosine phosphorylation of ERKs was blocked by pretreatment with 1 microm PP2, a selective inhibitor of Src kinases. The present study demonstrates that 14, 15-EET exerts its mitogenic effects predominantly through a Src kinase-mediated pathway, which is the most upstream signaling step determined to date in the 14,15-EET-activated tyrosine kinase cascade in renal epithelial cells.

8,11,14-Eicosatrienoic Acid↗

PubMed2000

Role of chronic exercise in decreasing oxidized LDL-potentiated platelet activation by enhancing platelet-derived no release and bioactivity in rats.

This study investigates how chronic exercise affects Ox-LDL mediated-platelet activation. Five-week-old male Wistar rats were assigned to either control or trained groups. Trained rats were treadmill-trained for 10 weeks after familiarization. The following measurements were taken in both control and trained groups: plasma lipid profile, oxidation of LDL, platelet adhesiveness, aggregability, cGMP contents, plasma and platelet-NO metabolite (nitrite plus nitrate) levels, and urinary 8-iso-prostaglandin F2alpha (8-iso-PG F2alpha) levels. Based on those measurements, major findings in this study can be summarized as follows: 1) the trained group prolonged the lag time of isolated LDL subjected to copper-induced in vitro oxidation significantly longer than the control group; 2) although having higher plasma and platelet derived-NO metabolite levels, the trained group had lower urinary excretion of 8-iso-PGF2alpha than the control group; 3) the trained group had a lower platelet adhesiveness and aggregability and higher platelet derived-NO metabolite and cGMP productions than the control group; 4) the trained group had a lower Ox-LDL-potentiated platelet adhesiveness and aggregability and Ox-LDL-attenuated NO metabolite and cGMP productions in platelet than the control group; and 5) treating the platelet with L-arginine inhibited Ox-LDL-potentiated platelet activation in both control and trained groups. Results in this study demonstrate that amounts of preformed lipid peroxides decrease while NO production (which acts as an antioxidant) is significantly increased after chronic exercise. Moreover, exercise training decreases Ox-LDL-potentiated platelet activation most likely by enhancing platelet-derived NO release and bioactivity.

Animals↗

PubMed2000

Expression of bone sialoprotein in mineralized tissues of tooth and bone and in buccal-pouch carcinomas of Syrian golden hamsters.

The expression of bone sialoprotein (BSP) is normally restricted to mineralized connective tissues of bones and teeth where it has been associated with mineral crystal formation. However, recent studies have revealed ectopic expression of BSP in various lesions, including oral and extraoral carcinomas, in which it has been associated with the formation of microcrystalline deposits and the metastasis of cancer cells to bone. To develop a model to study the induction of BSP in carcinoma development, BSP expression in squamous-cell carcinomas induced by chemical carcinogen in the hamster cheek-pouch epithelium was investigated. Hamster BSP cDNA was first isolated and characterized, then used to prepare probes for Northern and in situ hybridization. The protein sequence of hamster BSP displayed 86% amino acid identity with a consensus mammalian BSP sequence and retained polyglutamate sequences, the RGD sequence and sites of phosphorylation, glycosylation and sulphation. The tissue-specific expression of hamster BSP mRNA and protein was confirmed by in situ hybridization and immunolocalization in developing tissues. Squamous-cell carcinomas induced in the buccal pouches of 5-week-old male Syrian golden hamsters treated with chemical carcinogen had BSP mRNA and BSP in the proliferating neoplastic epithelium. In contrast, neither BSP mRNA nor the protein could be detected in the stroma within which islands of the transformed tissue had formed. Thus, the hamster cheek pouch is a well-characterized model that can be used to study the induced expression of BSP in association with the development of squamous-cell carcinomas.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2000

Effects of metabolites of benzo(a)pyrene on unschedule DNA synthesis in BALB/3T3 cell line.

In order to explore the damage from metabolites of benzo(a)pyrene on DNA of mammalian cells, the effects of four metabolites of benzo(a)pyrene (anti-BPDE, syn-BPDE, 3-OH-BP and 9-OH-BP) on synthesis of DNA and unschedule DNA synthesis (UDS) in BALB/3T3 cells were assayed, by methods of single-labeling and double-labeling. The results showed that all of the four agents were able to increase the synthesis of DNA, but only three of them (apart from syn-BPDE) induced UDS in BALB/3T3 cells. The above indicates that the metabolites of benzo(a)pyrene are able to damage DNA in BALB/3T3 cells, and that this effect may be relative to the sterical structure of metabolites of benzo(a)pyrene.

3T3 Cells↗