[Effect of overexpression of integrin β2 on clinical prognosis in triple negative breast cancer]

Objective: To investigate the clinical significance of the expression of integrin β2 (ITGB2) and tumor infiltrating dendritic cells CD80 and CD86 in triple negative breast cancer (TNBC). Methods: The expression levels of ITGB2 and MHC-1 in MDA-MB-231 cells and TNBC tissues were detected by Western bolt and RT-PCR, and the expressions of ITGB2, CD80 and CD86 in TNBC tissues were detected by immunohistochemistry. Results: 1.The expression level of ITGB2 in TNBC cell line (1.67±0.38) was higher than that in MCF-10A cell line (1.06±0.38), and the expression level of MHC-1 molecules in TNBC cell line (0.64±0.20) was lower than that in MCF-10A cell line (1.02±0.21). The difference was statistically significant (P=0.036 and 0.020, respectively). 2.The expression level of ITGB2 in TNBC tissues (1.55±0.47) was significantly higher than that in normal breast tissues (1.04±0.31). 3. Immunohistochemistry showed that the expression level of ITGB2 in TNBC tissues (3.31±2.29) was significantly higher than that in paracancerous tissues (1.20±1.19). Combined with clinicopathological data, it was suggested that the expression of ITGB2 was correlated with tumor stage (P=0.038), histological grade (P=0.022), lymph node metastasis (P=0.019), ki67 expression (P=0.000) and total survival (P=0.003). 4. Immunohistochemistry showed that the expression of CD80 and CD86 in TNBC tissues (3.07±1.57, 3.93±1.64) was significantly lower than those in paracancerous tissues (4.63±2.92 vs 5.23±2.85) (P=0.032 and 0.027). Conclusion: The high expression of ITGB2 in triple negative breast cancer affects the prognosis of patients.

[Effect of high expression of type Ⅰ collagen α1 chain protein on the prognosis of triple negative breast cancer]

Objective: To investigate the expression of type Ⅰ collagen α1 chain protein (COL1A1) in triple negative breast cancer (TNBC), and its relationship with clinicopathological features and prognosis of TNBC. Methods: A total of 148 TNBC specimens were collected from the Affiliated Cancer Hospital of Xinjiang Medical University from 2013 to 2015. The mRNA expression of COL1A1 was detected by fluorescence quantitative RT-PCR and the protein expression of COL1A1 was detected by Western blot. The expression of COL1A1 and α-smooth muscle actin (α-SMA) in TNBC were detected by immunohistochemistry. The relationship between the expression of COL1A1 and clinicopathological parameters and prognosis of TNBC patients was analyzed. Results: The mRNA and protein expression of COL1A1 in MDA-MB-231 cells were 1.696±0.486 and 0.550±0.088, respectively, which were higher than those in MCF-10A cells (1.020±0.231 and 0.350±0.083, P=0.032, P=0.046). The mRNA and protein expression of COL1A1 in TNBC tissues were 1.632 ±0.598 and 0.733 ±0.068, respectively, which were higher than those in paracancerous tissues (1.041±0.316 and 0.612±0.016, P=0.003, P=0.039). The high expression rates of COL1A1 and α-SMA in TNBC tissues were 35.8% and 56.7% respectively, which were higher than those in paracancerous tissues (16.7% and 30.0%, P=0.041, P=0.037). The expression of COL1A1 was correlated with tumor size, TNM stage, lymph node metastasis, vascular invasion and α-SMA expression (all P<0.05). The median survival time in COL1A1 high expression group was 64 months, which was lower than that in low expression group (73 months, P<0.05). Multivariate analysis of Cox proportional hazard regression model showed that COL1A1 expression was an independent influencing factor for the survival of TNBC patients (HR=3.952, P=0.004). Conclusion: The high expression of COL1A1 in TNBC is an independent prognostic factor of TNBC patients.

[Qualitative research on factors of HIV testing among men who have sex with men in China based on Blued]

Objective: To understand the cognition and attitudes of men who have sex with men (MSM) towards HIV testing and explore in-depth reasons preventing them from testing. Methods: The function of "opinion" in Blued, a gay geo-social networking application (GSN), was adopted to collect qualitative data of ideas and attitudes towards HIV testing of the users between December 2017 and January 2018. The data was analyzed based on grounded theory approach. Results: 28 269 Blued users participated in the activity and 1 977 posted comments. Four key themes were identified, i.e. no/low risk of contracting HIV, stigmatization of HIV testing, long-term relationship and conventional impediments of HIV testing. Conclusion: The cognition and attitudes of the target population derived from the analysis of "opinion" function in Blued, such as the stigmatization of the behavior of HIV testing influencing the attitude of HIV testing, could help researchers build a more accurate detection and promotion strategy instead of a very general intervention on the public.

[Analysis of lymph node jump metastasis in papillary thyroid carcinoma]

Objective:To summarize the metastatic feature of lateral neck lymph node metastasis in papillary thyroid carcinoma.Method:Clinical and pathological data were collected from 301 patients who were first diagnosed as PTC in our hospital. These patients were divided into positive and negative status of lateral cervical lymph nodes and lymph node jump metastasis. Chi-square test and Logistic regression analysis were used to evaluate the relationship between lateral cervical lymph node status and clinicopathology.Result:Tumor size over 2cm, Unilateral thyroid gland contains multiple foci,multiple foci, capsular invasion, ultrasound feature of PTC,the main foci located in the isthmus and the pole of gland, trachea/parathyroid lymph nodes positive were associated with the lymph node jump metastasis in papillary thyroid(P<0.05).Conclusion:Multiple foci in single gland, multifocal foci, calcification and the primary tumor involving the superior pole and middle of the thyroid gland are independent influencing factors for skip lateral lymph node metastasis in PTC(P<0.05).

Soil phosphorus loss in tile drainage water from long-term conventional- and non-tillage soils of Ontario with and without compost addition

Recent ascertainment of tile drainage a predominant pathway of soil phosphorus (P) loss, along with the rise in concentration of soluble P in the Lake Erie, has led to a need to re-examine the impacts of agricultural practices. A three-year on-farm study was conducted to assess P loss in tile drainage water under long-term conventional- (CT) and non-tillage (NT) as influenced by yard waste leaf compost (LC) application in a Brookston clay loam soil. The effects of LC addition on soil P loss in tile drainage water varied depending on P forms and tillage systems. Under CT, dissolved reactive P (DRP) loss with LC addition over the study period was 765g P ha^-1, 2.9 times higher than CT without LC application, due to both a 50% increase in tile drainage flow volume and a 165% increase in DRP concentration. Under NT, DRP loss in tile drainage water with LC addition was 1447gPha^-1, 5.3 times greater than that for NT without LC application; this was solely caused by a 564% increase in DRP concentration. However, particulate P loads in tile drainage water with LC application remained unchanged, relative to non-LC application, regardless of tillage systems. Consequently, LC addition led to an increase in total P loads in tile drainage water by 57 and 69% under CT and NT, respectively. The results indicate that LC application may become an environmental concern due to increased DRP loss, particularly under NT.

[Risk Factors for central lymph node metastasis in 1 988 papillary thyroid microcarcinoma patients]

Objective:To determine the risk factors that increase the neck central lymph node metastasis in papillary thyroid microcarcinoma(PTMC). Method:In this retrospective study,clinical and pathologic data were collected from patients who were first diagnosed as PTMC at the Xinjiang Medical University affiliated Tumor Hospital from January 2010 to March 2016. Chi-square test and multivariate logistic regression analysis were used to identify the risk factors of the neck central lymph node metastasis. Result:Of all 1988 patients,34.9% had the neck central lymph node metastasis. Age<45 years（P<0.05）,male（P<0.05),multifocality（P<0.05）,bilaterality（P<0.05）,tumor size >5 mm（P<0.05）,capsular invasion（P<0.05）or extrathyroidal extension（P<0.05）were significantly correlated with the neck central lymph node metastasis. Multivariate logistic regression analysis indicated that male, age <45 years, tumor size >5 mm,capsular invasion,extrathyroidal extension were independently correlated with the neck central lymph node metastasis. For patients with a solitary primary tumor, tumor location was independently correlated with the neck central lymph node metastasis.Unifocal tumor location in the lower third of the thyroid lobe was associated with the highest risk of the neck central lymph node metastasis(46.8%)(P<0.05).Multifocal tumor location was not associated with the neck central lymph node metastasis(P>0.05). Conclusion:More aggressive treatment or more frequent follow-up could be considered for patients with unfavorable features(male gender, age <45 years,tumor size >5 mm,capsular invasion,extrathyroidal extension,unifocal tumor location in the lower third of the thyroid lobe), as these patients may be at an increased risk for the neck central lymph node metastasis.

Identifying crosstalk of mTOR signaling pathway of lobular breast carcinomas

BACKGROUND

Invasive lobular carcinoma (ILC) and its variants represent 5% to 15% of all invasive breast cancers diagnoses annually. AS a serine/threonine kinase, mammalian target of rapamycin (mTOR) is often a downstream effector of PI3K/Akt (phosphatidyl inositol 3-kinase/protein kinase B) signaling pathway in breasts and many types of cancer cells. Therefore, agents that target mTOR in direct or indirect manner are being developed in anti-cancer therapy.

AIM

In this study, our objective here was to explore more crosstalk pathway with mTOR signaling pathway.

MATERIALS AND METHODS

We collected pathways data from published database, then based on bioinformatics methods we analyzed the significant pathways in the database, additionally, the crosstalk pathways were also analyzed which were defined as those pathways which have the overlapping genes with each other.

RESULTS

As we expected, the results showed that Notch signaling pathway (hsa04330), Regulation of autophagy (hsa04140), and Adipocytokine signaling pathway (hsa04920) were linked to mTOR signaling pathway. All of them have been demonstrated participate in breast cancer progression.

CONCLUSIONS

We obtained some key pathways that crosstalked with mTOR signaling pathway, we hope our study could provide novel therapeutic approaches for breast cancer.

Investigation on gene transfer from genetically modified corn (Zea mays L.) plants to soil bacteria

Knowledge about the prevalence and diversity of antibiotic resistance genes in soil bacteria communities is required to evaluate the possibility and ecological consequences of the transfer of these genes carried by genetically modified (GM) plants to soil bacteria. The neomycin phosphotransferase gene (nptII) conferring resistance to kanamycin and neomycin is one of the antibiotic resistance genes commonly present in GM plants. In this study, we investigated kanamycin-resistant (Km(R)) and neomycin-resistant (Nm(R)) soil bacterial populations in a 3-year field trial using a commercial GM corn (Zea mays L.) carrying the nptII gene and its near isogenic line. The results showed that a portion (2.3 - 15.6 %) of cultivable soil bacteria was naturally resistant to kanamycin or neomycin. However, no significant difference in the population level of Km(R) or Nm(R) soil bacteria was observed between the GM and non-GM corn fields. The nptII gene was not detected in any of the total 3000 Km(R) or Nm(R) isolates screened by PCR. Further, total soil bacterial cells were collected through Nycodenz gradient centrifugation and bacterial community DNA was subjected to PCR. Detection limit was about 500 cells per gram of fresh soil. Our study suggests that the nptII gene was relatively rare in the soil bacterial populations and there was no evidence of gene transfer from a GM corn plant to soil bacteria based on the data from total soil bacterial communities.

Estimating dissolved reactive phosphorus concentration in surface runoff water from major Ontario soils

Phosphorus (P) loss from agricultural land in surface runoff can contribute to eutrophication of surface water. This study was conducted to evaluate a range of environmental and agronomic soil P tests as indicators of potential soil surface runoff dissolved reactive P (DRP) losses from Ontario soils. The soil samples (0- to 20-cm depth) were collected from six soil series in Ontario, with 10 sites each to provide a wide range of soil test P (STP) values. Rainfall simulation studies were conducted following the USEPA National P Research Project protocol. The average DRP concentration (DRP30) in runoff water collected over 30 min after the start of runoff increased (p < 0.001) in either a linear or curvilinear manner with increases in levels of various STPs and estimates of degree of soil P saturation (DPS). Among the 16 measurements of STPs and DPSs assessed, DPS(M3) 2 (Mehlich-3 P/[Mehlich-3 Al + Fe]) (r2 = 0.90), DPS(M3)-3 (Mehlich-3 P/Mehlich-3 Al) (r2 = 0.89), and water-extractable P (WEP) (r2 = 0.89) had the strongest overall relationship with runoff DRP30 across all six soil series. The DPS(M3)-2 and DPS(M3)-3 were equally accurate in predicting runoff DRP30 loss. However, DPS(M3)-3 was preferred as its prediction of DRP30 was soil pH insensitive and simpler in analytical procedure, ifa DPS approach is adopted.

Evaluation of detection methods for genetically modified traits in genotypes resistant to European corn borer and herbicides

Detection of genetically modified (GM) traits in corn (Zea mays L.) is urgently needed for preservation of genetic identity and marketing GM products. A laboratory study was conducted to evaluate the efficiency, accuracy, and reliability of different analytical methods to detect GM traits in corn. Samples with known fractions of GM concentrations (Bacillus thuringiensis [Bt], Liberty Link [LL] and stacked [Bt/LL] genes) from commercial seed companies and those derived from yellow kernels in a white corn ear, outcrossed by pollen of neighboring Bt hybrid, were tested by lateral flow quick test kits and by enzyme-linked immunosorbent assay (ELISA)-based test strips purchased from different companies. Liberty Link hybrids are resistant to glufosinate (Liberty or Basta) herbicides, whereas Bt corn is developed for the control of European corn borer (Ostrinia nubilalis). Selected samples of GM concentrations were also tested in a commercial laboratory using DNA-based polymerase chain reaction (PCR) test. The results demonstrated that qualitative lateral flow quick tests could detect samples containing 1% or higher Bt and 2% or higher LL concentrations within the recommended time limit of the test. Faint test lines for samples containing 0.5 to 1% Bt or 1 to 2% LL concentrations appeared if samples remained in the test cup overnight. ELISA test strips detected the Bt content semiquantitatively in the range of 0.5 to 2.0%. Grain samples derived from non-Bt corn outcrossed by neighboring Bt pollen had usually lower GM concentrations than commercial GM seed samples. Both ELISA- and DNA-based PCR tests distinguished samples with GM concentrations between 0.1 to 0.5%, but the precision of quantification at this range was very low and results were highly inconsistent.

Comparative analysis of PAH:DNA adducts formed in lung of mice exposed to neat coal tar and soils contaminated with coal tar

7H-Benzo[c]fluorene (benzo[c]fluorene) is a major DNA adduct forming component of coal tar in lung of mice. The present study evaluated the types of PAH:DNA adducts formed from different neat coal tar samples and soils contaminated with coal tar. Mice were fed diets containing coal tar either neat or as a contaminant in an environmental soil sample for 14 days, and the types of chemical:DNA adducts formed in lung were evaluated using 32P-postlabeling and HPLC analysis. Three major DNA adducts derived respectively from benzo[b]fluoranthene (B[b]F), benzo[a]pyrene (B[a]P), and benzo[c]fluorene were detected in three of the four neat coal tar samples evaluated. In contrast, only a single major DNA adduct derived from benzo[c]fluorene was observed with the remaining tar sample. Ingestion of coal tar contaminated soil resulted in DNA adducts primarily derived from benzo[c]fluorene and B[b]F; a B[a]P derived DNA adduct was not detected. The DNA adducts derived from benzo[c]fluorene and B[b]F but not B[a]P were also observed with animals fed methylene chloride extracts of three of these soils but not the one designated A1000H soil. However, the extract of A1000H resulted in a B[a]P:DNA adduct being detected along with adducts formed from B[b]F and benzo[c]fluorene. The selective formation of the benzo[c]fluorene:DNA adduct with coal tar contaminated soils indicates that the in vivo systemic bioavailability and/or metabolism of benzo[c]fluorene is relatively high when compared to other DNA adducting hydrocarbons within coal tar. Benzo[c]fluorene may play a critical role in the potential of contaminated soil to induce a toxicological response in animals.

[Construction of human pLXSN-CD80 retrovirus vector and expression in CHO and PA317 cells]

CD80, a molecule on the antigen presenting cells, provide costimulation signals for T cell activation and play a key role in tumor immune. Based on our previous work of human CD80 full length cDNA cloning, a retrovirus expression vector pLXSN-CD80 was constructed. CD80 expression cells were selected by G418 from pLXSN-CD80 transfected PA317 and CHO cells by calcium phosphate. Expression, distribution and molecular weight (MW) of CD80 were measured by RIA, FACs and western blot. pLXSN-CD80 transfected CHO cells expressed relatively high level of CD80 protein (approximately the same as Raji cells) with an apparent MW of 40 kD. In the presence of G418 or not, pLXSN-CD80 transfected PA317 and CHO cells maintained CD80 expression for five months of passage. The results indicate that our construct is potent for experimental use in gene therapy.

IL-10 and trichosanthin inhibited surface molecule expression of antigen processing cells and T-cell proliferation

AIM

To study immunoinhibitory effects and preliminary mechanism of IL-10 and trichosanthin.

METHODS

Surface molecule expression on antigen processing cells (APC) was stained with fluorescence and analyzed by FACScan. B7-1 mRNA expression was detected with nested RT-PCR.

RESULTS

IL-10 2 mg.L-1 and trichosanthin 10 mg.L-1 inhibited B7-1 molecule expression. By contrast, they had not the same effects on ICAM-1. IL-10 and trichosanthin down-regulated LFA-1 expression, but had no regulatory effect on CD40. IL-10 and trichosanthin dramatically inhibited T-cell proliferation and IL-2 production. B7-1 mRNA expression was undetectable in APC treated with IL-10 and trichosanthin.

CONCLUSION

IL-10 and trichosanthin inhibit surface molecule expression on APC. They exert multiple immunoinhibitory effects.

Active site of trichosanthin acting as a ribosome-inactivating protein

AIM

To localize the active site of ribosome inactivation of trichosanthin (Tri), a Chinese herb protein.

METHODS

Hydroxylamine was used to specifically cleave the unique Asn-Gly peptide bond of Tri. Preparative SDS-polyacrylamide gel electrophoresis was applied to get 2 cleaved fragments, HATf1 and HATf2. Western blotting was used to determine the different epitopes of Tri and screen the antibodies. A cell-free system, rabbit reticulocyte lysate, was introduced to quantitate the inhibitory activity of Tri and its fragments on protein biosynthesis.

RESULTS

HATf1 and HATf2 were separated with the purity of 96.9% and 80.5% respectively. HATf1, like intact Tri, retained the inhibitory activity on protein biosynthesis. The mAb No 14 and No 16 against Tri showed different immunoreactivities with 2 fragments and were selected as representatives in further blocking tests. The mAb No 14 hindered the activities of Tri and HATf1, whereas the mAb No 16 did not.

CONCLUSION

The active site of Tri responsible for inhibitory activity on protein biosynthesis was on the HATf1 side near the junction of two portions.

The effects of hydrogen peroxide on DNA repair activities

Oxygen free radicals generated by H2O2 are involved in the multistage carcinogenic process; mechanisms include carcinogen activation, oxidative DNA damage, and tumor promotion. In this study, we have evaluated another potential mechanism of H2O2 in carcinogenesis--modulation of DNA repair activities. Preexposure of human peripheral mononuclear leukocytes to H2O2 significantly inhibited DNA repair activities in response to damage induced by N-methyl-N'-nitro-N-nitrosoguanidine, measured as unscheduled DNA synthesis. The responses to H2O2 were compared in four healthy human subjects with two sample preparations on different days. Results from multivariate general linear models showed that H2O2 significantly inhibited DNA repair in a dose-dependent manner after adjustment for between- and within-subject variabilities. There was an estimate of 5.0 units (dpm/5 x 10(5) cells) decrease in induced unscheduled DNA synthesis per unit (microM) increase of H2O2 treatment. Furthermore, there was substantial variability in DNA repair activities for the same individual sampled on different days regardless of H2O2 dose level. Results from this study suggest that H2O2 not only can induce DNA damage, but also have suppressive effects on DNA repair.

Trichosanthin, an initiator of the alternative complement activation pathway

Trichosanthin (TCS), a protein purified from the plant Trichosanthes Kirilowii Maxim, activates normal human serum complement via the alternative pathway, as shown by TCS-induced C3 conversion in normal serum and its prevention by depletion of factor B, but not with the addition of EGTA. Injection of TCS to BALB/c mice consumed the complement alternative pathway (APC) activity in serum, implying in vivo activation of the alternative pathway by TCS. Elevation of peripheral blood leucocyte count as well as protein exudation and neutrophil accumulation in the peritoneal cavities could be induced by peritoneal injection of TCS. The main effect of complement activation by TCS was demonstrated to be induction of neutrophil accumulation.

Transcriptional activation of cytochrome P450 2B1/2 genes in rat liver by diallyl sulfide, a compound derived from garlic

Previous work in our laboratory demonstrated that cytochrome P450 2B1 in rat liver was induced, but P450 2E1 was inhibited and inactivated, by diallyl sulfide (DAS), a compound derived from garlic. Such a selective effect on P450 enzymes is of considerable interest toward the understanding of dietary effects on xenobiotic metabolism. In the present study, the mechanism of P450 2B1 induction by DAS was investigated. Following a single dose of DAS (200 mg/kg body weight, ig), liver microsomal pentoxyresorufin dealkylase (PORd) activity, a representative activity of P450 2B1, was induced 3-, 16-, 26-, and 43-fold at 6, 12, 18, and 24 h after the treatment, respectively. A corresponding increase in the level of P450 2B1/2 protein was observed by immunoblot analysis. The level of P450 2B1/2 mRNA in rat liver also increased markedly, reaching a maximum at 12 h after the DAS treatment. Hybridization with the isozyme-specific oligonucleotide probes revealed that the mRNA levels of both P450s 2B1 and 2B2 were induced. In contrast, the level of P450 2E1 mRNA in the liver of DAS-treated rats was not changed. The results of nuclear run-on assay revealed that the transcriptional rate of P450 2B1/2 genes in the rat liver increased 13-fold at 6 h after DAS administration and returned to the control value at 24 h. The transcription of P450 2B1/2 genes was blocked completely by alpha-amanitin, an inhibitor of RNA polymerase II. These results clearly demonstrate that the induction of P450 2B1/2 in rat liver by DAS is mainly due to transcriptional activation. In the DAS-treated rats, P450 2B1/2 mRNA was also markedly induced in the stomach and duodenum. The maximal induction was found at 12 h after the treatment while the levels of P450 2B1/2 mRNA increased 66-fold in the duodenum and 23-fold in the stomach. DAS treatment, however, did not change the levels of P450 2B1/2 mRNA in the lung and nasal mucosa.

Induction of liver microsomal cytochrome P-450 2B1 by dimethyl diphenyl bicarboxylate in rats

Dimethyl diphenyl bicarboxylate (dimethyl-4,4'-dimethyloxy-5,6,5',6'-dimethylene-dioxy-di phe nyl-2,2'- bicarboxylate, DDB), a synthetic mimic of the natural product schizandrin C, is used in China as a hepatoprotective agent to improve the liver functions of patients with hepatitis or under cancer chemotherapy. In this study, we investigated the effects of DDB on liver microsomal drug-metabolizing enzymes. When male Sprague-Dawley rats were treated with a daily intragastric dose of DDB (200 mg.kg-1) for 3 d, the microsomal pentoxyresorufin dealkylase activity and P-450 2B1 protein levels were markedly increased. The fold increase was lower than that by phenobarbital (75 mg.kg-1, ip once daily x 3 d). The level of P-450 2B1 mRNA was elevated by DDB but the magnitude of the elevation was much less than that caused by phenobarbital. DDB also increased the rates of testosterone hydroxylation at positions 16 beta, 16 alpha, 6 beta, and 2 beta as well as the rate of ethoxyresorufin dealkylation, suggesting moderate increases in the levels of P-450 3A and P-450 1A1 in addition to the huge increase in P-450 2B1. The level of glutathione S-transferase was also slightly increased, but the levels of P-450 2E1 and NAD(P)H: quinone oxidoreductase were not changed. The results indicate that DDB is an inducer of P-450 2B1.

Electron microscopic appearance of the chronic Campylobacter jejuni enteritis of mice

Campylobacter jejuni is a major cause of human enteritis which mimics the inflammatory bowel disease (IBD). In this study, microstructural changes on the surfaces of the murine gastrointestinal tract persistently colonized by Campylobacter jejuni, strain GJ-S131, were investigated by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results revealed that the appearance of the gastrointestinal mucosa in both BALB/C and KM mice resembled that in human with inflammatory bowel disease. Under SEM, the mucosa of the jejunum and ileum, with broken or distorted villi had a "worm eaten" look; crypts were irregular in shape and size, and the mucosa showed atrophy, especially in the colon. Epithelial junctions demonstrated furrows, clefts or deep crevasses, with exudates containing a large number of leukocytes. Cytologic appearances were characterized by microvilli dysplasia and/or atrophy, patchy erosions or necrosis and pelade-like appearance due to absence of microvilli, which were similar to the findings under TEM.

Metabolism of carcinogenic nitrosamines by rat nasal mucosa and the effect of diallyl sulfide

Rat nasal cavity is one of the target organs for carcinogenesis induced by N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). The present work investigated the metabolism of these nitrosamines by rat nasal microsomes, as well as the possible modulating factors. Microsomes prepared from rat nasal mucosa were efficient in metabolizing these nitrosamines. In general, the metabolism of the nitrosamines was slightly higher in 9-week-old rats than in 4-week-old animals, and there was no sex-related difference. Fasting of rats for 48 h, which is known to induce hepatic cytochrome P450IIE1 and NDMA metabolism, did not increase the nasal metabolism of NDMA, NDEA, or NNK. Pretreatment of rats with acetone, another inducer of hepatic P450IIE1, did not increase the metabolism of NDMA. Furthermore, it decreased the nasal metabolism of NDEA and NNK. Immunoinhibition studies suggest that, in the nasal mucosa, P450IIE1 is only partially responsible for the oxidation of NDMA and other P450 isozymes are responsible for the metabolism of NDEA. A single p.o. pretreatment of male rats with diallyl sulfide (DAS), a component of garlic oil, caused a significant decrease in the oxidative metabolism of NDEA and NNK in rat nasal mucosa. Whereas the nasal metabolism of NDMA was reduced by DAS pretreatment, there was no change in the amount of the nasal microsomal proteins immunoreactive with the antibodies against P450IIE1. The inhibitory effect of DAS on the nasal oxidative metabolism of NDMA, NDEA, and NNK was also observed in experiments in vitro. The results demonstrate the ability of nasal mucosa to metabolically activate these nitrosamines and the inhibition of this process by DAS, suggesting that DAS may be effective in inhibiting the related nasal tumorigenesis.

Roles of pituitary hormones in the regulation of hepatic cytochrome P450IIE1 in rats and mice

Cytochrome P450IIE1 (P450IIE1) is responsible for the metabolic activation of N-nitrosodimethylamine (NDMA), a potent environmental carcinogen. This P450 enzyme displays a high-affinity NDMA demethylase (NDMAd) activity and is known to be induced by fasting and acetone administration. In the present work, the effects of pituitary hormones on the regulation of P450IIE1 in the liver were investigated and compared in rats and mice. There was no difference in liver microsomal NDMAd activity (nmol/min/mg protein) in rats in the intact (0.38 +/- 0.12), sham-operated (0.44 +/- 0.06), and hypophysectomized (0.52 +/- 0.04) groups. However, hypophysectomy caused a 2-fold increase in hepatic P450IIE1 protein levels as determined by immunoblot analysis. The P450IIE1 mRNA level in hypophysectomized rat was also significantly increased. The levels of blood ketone bodies (acetone, acetoacetate, and beta-hydroxybutyrate) were not different in the intact, sham-operated, and hypophysectomized groups, suggesting that ketone bodies are not involved in the induction of P450IIE1 protein and its mRNA by hypophysectomy. The discrepancy between the NDMAd activity and the increased P450IIE1 protein in rat liver by hypophysectomy can be partially explained by the lower hepatic NADPH-P450 reductase activity (50% that of the control) in the hypophysectomized rats. Upon the induction of liver NDMAd activity by fasting and acetone, hypophysectomy attenuated the effect of acetone but abolished the effect of fasting completely. Nevertheless, fasting still caused a 3-fold increase in the liver P450IIE1 mRNA level. An involvement of pituitary hormones in the regulation of liver microsomal P450IIE1 in mouse, however, was not observed. There was no difference in constitutive NDMAd activity between genetically growth hormone-deficient (lit/lit) mice and their phenotypically normal heterozygotes (lit/+). Fasting for 48 h caused 1.5- to 2-fold induction and acetone caused 2- to 3-fold induction, in both groups. The above changes in enzyme activity were due to the changes of P450IIE1 levels as verified by the immunoblot analysis. In male BALB/c mice, neither the hepatic NDMAd activity nor the P450IIE1 protein level was altered by hypophysectomy. The effects of acetone on the liver NDMAd activity were also similar in hypophysectomized and sham-operated mice. The results suggest that pituitary hormones are important in the regulation of the expression and activity of hepatic P450IIE1 in rats but not in the mouse strains investigated.