A synthetic antagonist for the peroxisome proliferator-activated receptor gamma inhibits adipocyte differentiation

While searching for natural ligands for the peroxisome proliferator-activated receptor (PPAR) gamma, we identified a synthetic compound that binds to this receptor. Bisphenol A diglycidyl ether (BADGE) is a ligand for PPARgamma with a K(d(app)) of 100 microM. This compound has no apparent ability to activate the transcriptional activity of PPARgamma; however, BADGE can antagonize the ability of agonist ligands such as rosiglitazone to activate the transcriptional and adipogenic action of this receptor. BADGE also specifically blocks the ability of natural adipogenic cell lines such as 3T3-L1 and 3T3-F442A cells to undergo hormone-mediated cell differentiation. These results provide the first pharmacological evidence that PPARgamma activity is required for the hormonally induced differentiation of adipogenic cells.

A new approach for evaluation of left ventricular diastolic function: spatial and temporal analysis of left ventricular filling flow propagation by color M-mode Doppler echocardiography

OBJECTIVES

To evaluate left ventricular diastolic function and differentiate the pseudonormalized transmitral flow pattern from the normal pattern, the propagation of left ventricular early filling flow was assessed quantitatively using color M-mode Doppler echocardiography.

BACKGROUND

Because the propagation of left ventricular early filling flow is disturbed in the left ventricle with impaired relaxation, quantification of such alterations should provide useful indexes for the evaluation of left ventricular diastolic function.

METHODS

Study subjects were classified into three groups according to the ratio of early to late transmitral flow velocity (E/A ratio) and left ventricular ejection fraction: 29 subjects with an ejection fraction > or = 60% (control group); 34 with an ejection fraction < 60% and E/A ratio < 1 (group I); and 25 with ejection fraction < 60% and E/A ratio > or = 1 (group II). The propagation of peak early filling flow was visualized by changing the first aliasing limit of the color Doppler signals. The rate of propagation of peak early filling flow velocity was defined as the distance/time ratio between two sampling points: the point of the maximal velocity around the mitral orifice and the point in the mid-left ventricle at which the velocity decreased to 70% of its initial value. High fidelity manometer-tipped measurement was performed in 40 randomly selected subjects.

RESULTS

The rate of propagation decreased in groups I and II compared with that in the control group (33.8 +/- 13.8 [mean +/- SD] and 30.0 +/- 8.6 vs. 74.3 +/- 17.4 cm/s, p < 0.001, respectively) and correlated inversely with the time constant of left ventricular isovolumetric relaxation and the minimal first derivative of left ventricular pressure (peak negative dP/dt) (r = 0.82 and r = 0.72, respectively).

CONCLUSIONS

Spatial and temporal analysis of filling flow propagation by color M-mode Doppler echocardiography was free of pseudonormalization and correlated well with the invasive variables of left ventricular relaxation.

The complete nucleotide sequence of the mitochondrial genome of sugar beet (Beta vulgaris L.) reveals a novel gene for tRNA(Cys)(GCA)

We determined the complete nucleotide sequence of the mitochondrial genome of an angiosperm, sugar beet (Beta vulgaris cv TK81-O). The 368 799 bp genome contains 29 protein, five rRNA and 25 tRNA genes, most of which are also shared by the mitochondrial genome of Arabidopsis thaliana, the only other completely sequenced angiosperm mitochondrial genome. However, four genes identified here (namely rps13, trnF-GAA, ccb577 and trnC2-GCA) are missing in Arabidopsis mitochondria. In addition, four genes found in Arabidopsis (ccb228, rpl2, rpl16 and trnY2-GUA) are entirely absent in sugar beet or present only in severely truncated form. Introns, duplicated sequences, additional reading frames and inserted foreign sequences (chloroplast, nuclear and plasmid DNA sequences) contribute significantly to the overall size of the sugar beet mitochondrial genome. Nevertheless, 55.6% of the genome has no obvious features of information. We identified a novel tRNA(Cys) gene (trnC2-GCA) which shows no sequence homology with any tRNA(Cys) genes reported so far in higher plants. Intriguingly, this tRNA gene is actually transcribed into a mature tRNA, whereas the native tRNA(Cys) gene (trnC1-GCA) is most likely a pseudogene.

Saccharomyces cerevisiae- and Candida albicans-derived mannan induced production of tumor necrosis factor alpha by human monocytes in a CD14- and Toll-like receptor 4-dependent manner

The cytokine-inducing activities of fungal polysaccharides were examined in human monocytes in culture, with special reference to CD14 and Toll-like receptors (TLRs). Tumor necrosis factor alpha (TNF-alpha) production by monocytes was markedly induced in a dose-dependent manner upon stimulation with cell walls from Candida albicans and mannan from Saccharomyces cerevisiae and C. albicans, although relatively high concentrations (10 to 100 microg/ml) of stimulants were required for activation as compared with the reference lipopolysaccharide (LPS) (1 to 10 ng/ml). The yeast form C. albicans and its mannan and cell wall fractions exhibited higher TNF-alpha production than respective preparations from the hyphal form. Only slight TNF-alpha production was induced by the S. cerevisiae glucan. The TNF-alpha production triggered by reference LPS and purified fungal mannans required the presence of LPS-binding protein (LBP), and these responses were inhibited by anti-CD14 and anti-TLR4 antibodies, but not by anti-TLR2 antibody. In contrast to the activity of LPS, the activity of purified S. cerevisiae mannan was not inhibited by polymyxin B. These findings suggested that the mannan-LBP complex is recognized by CD14 on monocytes and that signaling through TLR4 leads to the production of proinflammatory cytokines in a manner similar to that induced by LPS.

Predominance of canine parvovirus (CPV) in unvaccinated cat populations and emergence of new antigenic types of CPVs in cats

Serological, sequence, and in vitro host range analyses of feline parvovirus (FPV) isolates in Vietnam and Taiwan revealed that more than 80% of the isolates were of the canine parvovirus (CPV) type, rather than feline panleukopenia virus (FPLV). Although parvovirus isolates from three Vietnamese leopard cats were genetically related to CPV type 2a or 2b, they had a natural mutation of VP2 residue 300 Gly to an Asp, resulting in remarkable changes in their antigenic properties. These results indicated the possibility that CPV-2a/2b-type viruses can spread in cats more efficiently than conventional FPLV under natural conditions and that CPV-2a/2b viruses are further evolving in cats.

Structure and expression of a novel member, FGF-16, on the fibroblast growth factor family

We have isolated cDNA encoding a novel member (207 amino acids) of the FGF family from the rat heart by homology-based polymerase chain reaction. As this protein is the 16th documented member of the FGF family, we tentatively term it FGF-16. Among FGF family members, FGF-16 is most similar (73% amino acid identity) to FGF-9. We have also determined the structure of human FGF-16 with high amino acid sequence identity (98.6%) to rat FGF-16. Although the predicted FGF-16 amino acid sequence lacks a typical signal sequence, recombinant rat FGF-16 was efficiently secreted by Sf9 insect cells infected with recombinant baculovirus containing the cDNA. FGF-16 mRNA was predominantly expressed in the rat heart among the adult major tissues examined. The expression profile of FGF-16 mRNA was quite different from those of other members of the FGF family. In rat embryos, FGF-16 mRNA was predominantly expressed in the brown adipose tissue. However, the expression decreased greatly after birth. These results indicate that FGF-16 in embryos might play a role in development of the brown adipose tissue.

FGF-20, a novel neurotrophic factor, preferentially expressed in the substantia nigra pars compacta of rat brain

We have isolated cDNA encoding a novel FGF (212 amino acids) from rat brain. Because this is the 20th documented member of the FGF family, we tentatively term it FGF-20. Among FGF family members, FGF-20 is most similar to FGF-9 and FGF-16 (70 and 62% amino acid identity, respectively). Human FGF-20 gene was found in the human genomic sequence mapped to the 8p21.3-p22 region. Human FGF-20 is highly identical to rat FGF-20 (95% amino acid identity). FGF-20 mRNA was preferentially expressed in rat brain among the adult major tissues examined. The localization of FGF-20 mRNA in rat brain was also examined by in situ hybridization. FGF-20 mRNA was preferentially expressed in the substantia nigra pars compacta. To examine the biological activity of FGF-20, recombinant rat FGF-20 was produced by insect cells infected with recombinant baculovirus containing rat FGF-20 cDNA. Recombinant rat FGF-20 enhanced the survival of midbrain dopaminergic neurons. The present results indicate that FGF-20 is a novel neurotrophic factor preferentially expressed in the substantia nigra pars compacta of rat brain.

Non-invasive ultrasonic measurement of the elastic properties of the human abdominal aorta

A new echo tracking device linked to real time ultrasonic B mode equipment was developed to measure non-invasively the elastic properties of the human abdominal aorta. Pulsatile diameter change and mean diameter of the abdominal aorta were measured in 61 subjects with this ultrasonic device. Strain and pressure-strain elastic modulus Ep were calculated from pulsatile diameter change, diameter, and pulse pressure obtained by the auscultatory method. Strain significantly decreased with age; 0.076(0.024) (mean(SD)) in group 1 (20 young adults below the age of 35 years); 0.048(0.024) in group 2 (21 middle aged subjects between the ages of 35 and 60 years); and 0.030(0.010) in group 3 (20 elderly subjects over the age of 60 years). Ep values were 0.99(0.34) X 10(5), 1.55(0.68) X 10(5), and 3.80(2.05) X 10(5) N X m-2 in groups 1, 2, and 3 respectively. Ep in group 3 was significantly higher than in groups 1 and 2. The regression equation relating Ep to age was Ep = (-0.72 + 0.058 X age) X 10(5) N X m-2 (r = 0.73). The Ep value and its age related increase agreed with the findings in postmortem arteries. The elastic properties of the abdominal aorta could, therefore, be determined non-invasively by this ultrasonic method.

Establishment of a feline T-lymphoblastoid cell line highly sensitive for replication of feline immunodeficiency virus

Interleukin-2 dependent feline T-lymphoblastoid cells designated as MYA-1 cells were established. The cells were free from exogenous retroviruses and sensitive for replication of feline immunodeficiency virus (FIV). FIV can grow more efficiently in MYA-1 cells than in feline primary peripheral blood mononuclear cells. This line of cells will be useful not only for isolation and propagation of FIV, but also for further investigation of properties of FIV.

Mixed-histologic-type submucosal invasive gastric cancer as a risk factor for lymph node metastasis: feasibility of endoscopic submucosal dissection

BACKGROUND AND STUDY AIMS

The clinicopathologic features of gastric cancers containing a mixture of differentiated-type and undifferentiated-type components remain uninvestigated. We evaluated the risk of lymph node metastasis and the feasibility of endoscopic submucosal dissection (ESD) for the treatment of mixed-histologic-type gastric cancers.

PATIENT AND METHODS

We histologically classified 376 cases of gastric cancer with submucosal invasion into four types (differentiated type, differentiated-type-predominant mixed type, undifferentiated-type-predominant mixed type, and undifferentiated type) and studied the clinicopathologic relations of each type to lymph node metastasis. Lymphatic invasion was evaluated by D2-40 immunostaining.

RESULTS

The overall prevalence of lymph node metastasis in gastric cancer with submucosal invasion was 16.5% (62/376). The prevalence of lymph node metastasis was 36.5% (23/63) in undifferentiated-type-predominant mixed type, which was significantly higher than those in the other three types (P < 0.001 vs. differentiated type, P = 0.013 vs. differentiated-type-predominant mixed type, and P = 0.003 vs. undifferentiated type). Lymphatic invasion, a depth of invasion of 500 microm or more from the lower margin of the muscularis mucosae (SM2), tumor size above 30 mm, and undifferentiated-type-predominant mixed histologic type were independent risk factors for lymph node metastasis. Submucosal cancers without these four risk factors were free of lymph node metastasis (0/41; 95 % confidence interval 0%-8.6%).

CONCLUSIONS

Undifferentiated-type-predominant mixed-type gastric cancer with submucosal invasion carries a high risk of lymph node metastasis. ESD can be indicated for gastric cancer with submucosal invasion provided that the following conditions indicating a low risk of metastasis are met: a depth of invasion of no more than 500 microm or more from the lower margin of the muscularis mucosae (SM1), no lymphatic invasion, a tumor size of no more than 30 mm, and a proportion of undifferentiated components below 50%.

Prevalence of Arcobacter species in retail meats and antimicrobial susceptibility of the isolates in Japan

A survey was conducted to examine the prevalence of Arcobacter species among meat samples and to investigate the antimicrobial susceptibility of the isolates in Japan. In 1998 and 1999, samples of beef (n=90), pork (n=100) and chicken meat (n=100) were purchased from seven retail shops. Arcobacter species were isolated from 2.2%, 7.0% and 23.0% of beef, pork and chicken meat samples, respectively. The rate of isolations in chicken meats was shown to be significantly higher than those of beef and pork. Species-specific polymerase chain reaction (PCR) demonstrated that the most dominant Arcobacter species was Arcobacter butzleri among the isolates examined. Multiple contaminations with different Arcobacter species were observed in 5% of the chicken samples. Almost all the strains tested showed resistance to vancomycin (100%) and methicillin (97.5%). Strains resistant to cephalothin, sulfamethoxazole-trimethoprim, nalidixic acid and chloramphenicol were detected at the rate of 81.1%, 67.2%, 53.5% and 24.6%, respectively. All Arcobacter strains examined were susceptible to ampicillin, tetracycline, streptomycin and kanamycin.

High prevalence of the CagA-positive Helicobacter pylori strains in Japanese asymptomatic patients and gastric cancer patients

BACKGROUND

Several studies have shown that infection of Helicobacter pylori strains possessing cagA is associated with atrophic gastritis and gastric cancers.

METHOD

In 58 pairs of early gastric cancer patients and sex- and age-matched controls, isolated H. pylori strains were tested for possession of cagA. The presence of atrophic gastritis was also examined.

RESULTS

Proportions of cagA-positive strains were 100% in cancer patients and 92.3% in controls. Atrophic gastritis was seen in 96.7% and 95.8% of cancer and control patients in whom cagA-positive strains (NS) were detected. However, it was seen in only 20% of H. pylori-negative control patients (P < 0.01).

CONCLUSIONS

The present results do not suggest any specific association between cagA-positive strains and gastric cancer. However, frequent prevalence of cagA-positive strains might be associated with the high incidence of atrophic gastritis in Japanese populations.

Synthesis and antitumor activity of novel dolastatin 10 analogs

Dolastatin 10 (1) is a potent antineoplastic pentapeptide. Novel dolastatin 10 analogs each modified at one of the constituent amino acid derivatives, were synthesized and their antitumor activity was evaluated against P388 leukemia in mice. The structural requirements for antitumor activity are discussed. Some of the analogs, 31c, 35c, 38b, and 50c showed excellent activity in vivo. Highly active 50c, which lacks the thiazole group of 1, was selected for further development as an antitumor agent.

Molecular and phylogenetic analyses of the haemagglutinin (H) proteins of field isolates of canine distemper virus from naturally infected dogs

We isolated three strains of canine distemper virus (CDV)--the Ueno, Hamamatsu, and Yanaka strains--from dogs in Japan and analysed the molecular properties of their haemagglutinin (H) proteins. Immunoprecipitation of all three strains with a monoclonal antibody revealed H proteins with molecular masses of 84 kDa, which differs from the molecular mass (78 kDa) of the H protein of the Onderstepoort vaccine strain. However, after tunicamycin treatment immunoprecipitation identified H proteins of identical molecular mass (68 kDa) for all three field isolates and the vaccine strain. Sequence analysis showed nine potential sites for asparagine-linked glycosylation in the H proteins of the new isolates, in contrast to four in the H protein of the Onderstepoort strain. Thus, variation in glycosylation of the H proteins of the isolates and the vaccine strain may cause differences in antigenicity of the viruses. Sequences of the H genes showed that the new Japanese isolates have 99% identity with each other, 95% with other European and American isolates (from seals, a German dog, a ferret and large felids) and 90% with the vaccine strain. Phylogenetically, the new Japanese isolates form one cluster which is separate from recent European or American isolates, all of which are distinct from vaccine strains.

Antitumor activity of TZT-1027, a novel dolastatin 10 derivative

Dolastatin 10, a pentapeptide isolated from the marine mollusk Dolabella auricularia, has antitumor activity. TZT-1027, a dolastatin 10 derivative, is a newly synthesized antitumor compound. We evaluated its antitumor activity against a variety of transplantable tumors in mice. Intermittent injections of TZT-1027 were more effective than single or repeated injections in mice with P388 leukemia and B16 melanoma. Consequently, TZT-1027 shows schedule dependency. TZT-1027 was effective against P388 leukemia not only when administered i.p., but also when given i.v. However, although TZT-1027 given i.v. was active against murine solid tumors, TZT-1027 administered i.p. was ineffective against all the tumors tested with the exception of colon 26 adenocarcinoma. The i.v. injection of TZT-1027 at a dose of 2.0 mg/kg remarkably inhibited the growth of three murine solid tumors; colon 26 adenocarcinoma, B16 melanoma and M5076 sarcoma, with T/C values of less than 6%. The antitumor activities of TZT-1027 against these tumors were superior or comparable to those of the reference agents; dolastatin 10, cisplatin, vincristine, 5-fluorouracil (5-FU) and E7010. In experiments with drug-resistant P388 leukemia, TZT-1027 showed good activity against cisplatin-resistant P388 and moderate activity against vincristine- and 5-fluorouracil-resistant P388, but no activity against adriamycin-resistant P388. TZT-1027 was also effective against human xenografts, that is, tumor regression was observed in mice bearing MX-1 breast and LX-1 lung carcinomas. TZT-1027 at 10 microM almost completely inhibited the assembly of porcine brain microtubules. Therefore, its mechanism of antitumor action seems to be, at least in part, ascribable to the inhibition of microtubule assembly. Because of its good preclinical activity, TZT-1027 has been entered into phase I clinical trials.

Characterization of a haemolytic factor from Candida albicans

The culture supernatant of Candida albicans promoted the disruption of human red blood cells (RBCs). The haemolytic activity was detected in a sugar-rich fraction (about 200 kDa) from Sephacryl S-100 chromatography. As the haemolytic activity was adsorbed by concanavalin A-Sepharose, the haemolytic factor may be a mannoprotein. The activity was inactivated by periodate oxidation, indicating that the sugar moiety of the mannoprotein played an important role in the haemolysis. The structure of the sugar moiety of the mannoprotein was identified as a cell-wall mannan by 1H-NMR analysis, and purified C. albicans mannan promoted the disruption of RBCs. The binding of mannan to RBCs was demonstrated by flow cytometric analysis and was inhibited by the addition of band 3 protein inhibitor, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). The haemolysis caused by mannan was inhibited by DIDS, SITS (4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid) and bis(sulfosuccinimidyl) suberate, but not by pyridoxal 5-phosphate. These results indicated that a mannoprotein released from C. albicans bound to the band 3 protein on RBCs, thereby promoting their disruption.

Protective effect of N-acetyl chitohexaose on Listeria monocytogenes infection in mice

A water-soluble oligosaccharide, N-acetyl chitohexaose (NACOS-6) was able to enhance the protecting effect of BALB/c male mice against Listeria monocytogenes infection, when administered intraperitoneally 24 hr before the challenge with this microbe. Significant decrease in number of microbes within the peritoneal cavity, spleen, and liver from the mice of NACOS-6-administered group was not observed 1 day after the infection but 4 days after the infection. Administration of NACOS-6 enhanced the delayed-type hypersensitivity response against sheep red blood cells (SRBC) or heat-killed L. monocytogenes. Splenic T lymphocytes from mice administered NACOS-6 released macrophage activating factor (MAF). These results suggested that NACOS-6 was also able to elevate the function of cellular immunity. Macrophages treated with a combination of NACOS-6 and the culture supernatant of splenic T lymphocytes from mice administered NACOS-6, "NACOS-6 sup," were found to exert a fairly strong growth-inhibitory effect on L. monocytogenes. Interferon-gamma (IFN-gamma) and interleukin 2 (IL-2) were able to enhance the growth-inhibitory effect on L. monocytogenes by the NACOS-6-treated macrophages.

Prevention of vertical transmission of Neospora caninum in BALB/c mice by recombinant vaccinia virus carrying NcSRS2 gene

Neospora caninum infection is the major cause of bovine abortion. To develop a vaccine against N. caninum infection, recombinant vaccinia viruses carrying NcSRS2 and NcSAG1 genes (vv/Nc-p43 and vv/Nc-p36, respectively) were constructed and were tested in a mouse model. Vaccination of dams with vv/Nc-p43 appeared to confer effective protection against vertical transmission to offspring, though that with vv/Nc-p36 only provided partial protection. Moreover, the vv/Nc-p43 vaccination provoked cellular immune responses and antibody production against N. caninum. In conclusion, it is expected that vv/Nc-p43 can be used as an effective live vaccine to prevent vertical transmission of N. caninum in natural hosts.

The cytoplasmic male-sterile type and normal type mitochondrial genomes of sugar beet share the same complement of genes of known function but differ in the content of expressed ORFs

The complete nucleotide sequence (501,020 bp) of the mitochondrial genome from cytoplasmic male-sterile (CMS) sugar beet was determined. This enabled us to compare the sequence with that previously published for the mitochondrial genome of normal, male-fertile sugar beet. The comparison revealed that the two genomes have the same complement of genes of known function. The rRNA and tRNA genes encoded in the CMS mitochondrial genome share 100% sequence identity with their respective counterparts in the normal genome. We found a total of 24 single nucleotide substitutions in 11 protein genes encoded by the CMS mitochondrial genome. However, none of these seems to be responsible for male sterility. In addition, several other ORFs were found to be actively transcribed in sugar beet mitochondria. Among these, Norf246 was observed to be present in the normal mitochondrial genome but absent from the CMS genome. However, it seems unlikely that the loss of Norf246 is causally related to the expression of CMS, because previous studies on mitochondrial translation products failed to detect the product of this ORF. Conversely, the CMS genome contains four transcribed ORFs (Satp6presequence, Scox2-2 , Sorf324 and Sorf119) which are missing from the normal genome. These ORFs, which are potential candidates for CMS genes, were shown to be generated by mitochondrial genome rearrangements.

Surgical management of the recurrence and regrowth of craniopharyngiomas

Object. The authors performed a retrospective analysis of a consecutive series of craniopharyngiomas and their recurrences, which were managed with surgery alone.

Methods. In the past 20 years, 37 consecutive patients with craniopharyngiomas underwent surgery without adjuvant radiotherapy. During that period there was a consistent strategy that surgical management was the first choice of treatment whenever possible.

Of these 37 patients, 11 experienced tumor recurrence (29.7%) during the mean follow-up period of 11.1 years. Of these 11 patients, seven experienced recurrence after neuroimaging-confirmed total removal, and four patients experienced recurrence after partial or incomplete removal. In these 11 patients, surgical removal was performed 17 times. Using a proper surgical approach (mainly a basal interhemispheric approach) and meticulous microsurgical techniques, total removal of the recurrent tumor was achieved in nine surgeries (52.9). The mortality and morbidity rates associated with these 17 surgeries were 0% and 9.1%, respectively. In most cases, visual function was preserved or improved and intellectual performance was also preserved.

Conclusions. Recurrence of craniopharyngioma can be safely managed by using meticulous contemporary microsurgical techniques without additional radiotherapy. The role of surgery and adjuvant radiotherapy for craniopharyngiomas may vary in the future, depending on innovations in treatment and technology. Nevertheless, surgery can be still a major therapeutic option in the management of recurrent craniopharyngiomas.

Comparison between in vivo mutagenicity and carcinogenicity in multiple organs by benzo[a]pyrene in the lacZ transgenic mouse (Muta Mouse)

To evaluate whether the in vivo mutagenicity test system using the lacZ transgenic mice (Muta Mouse) may be applied to carcinogenesis studies, both the in vivo mutagenicity and carcinogenicity of benzo[a]pyrene (BP) was tested in mice under the same administration conditions. The eleven organs of the mice on the 14th day after the final oral administration of BP at a dose of 125 mg kg(-1) day(-1) or corn oil for 5 consecutive days were tested for in vivo mutation by the positive-selection method. The data show that the colon had the highest lacZ mutant frequency (37-fold increase over the spontaneous frequency), followed by the ileum > forestomach > bone marrow, spleen > glandular stomach > liver, lung > kidney and heart. No significant mutations were found in the brain. These results may suggest that, in general, the organs with rapidly proliferative tissues have a marked increase in vivo mutant frequencies under the conditions of this experimental design. The forestomach and lymphatic organs including the spleen (malignant lymphoma) were the main target organs for BP carcinogenesis by 5 daily oral doses of 75 and 125 mg kg(-1) day(-1). These results suggest that the mutation results from the transgenic assay with BP reflect the carcinogenicity of BP in the mouse. They also indicate, however, that the magnitude of the in vivo lacZ mutant frequencies induced by BP in different organs did not fully correlate with the target organs for carcinogenicity.