Protective Mechanisms of Various Active Substances on Cell DNA Damage and Apoptosis Induced by Deoxynivalenol

Deoxynivalenol (DON) is a secondary metabolite of fungi that is harmful to humans and animals. This study examined the protective effects of natural substances, including resveratrol, quercetin, vitamin E, vitamin C, and microbe-derived antioxidants (MA), on both human gastric mucosal cells (GES-1) and pig small intestinal epithelial cells (IPEC-1) when induced by DON. Cells were incubated with active substances for 3 h and then exposed to DON for 24 h. The oxidative stress index, cell cycle, and apoptosis were measured. As compared to cells treated only with DON, pretreatment with active substances improved the balance of the redox status in cells caused by DON. Specifically, quercetin, vitamin E, vitamin C, and MA showed the potential to alleviate the G2 phase cell cycle arrest effect that was induced by DON in both kinds of cells. It was observed that vitamin E and vitamin C can alleviate DON-induced apoptosis and the G2 phase cycle arrest effect mediated via the ATM-Chk 2-Cdc 25C and ATM-P53 signaling pathways in GES-1 cells. In IPEC-1 cells, vitamin C and MA can alleviate both DON-induced apoptosis and the G2 phase cycle arrest effect via the ATM-Chk 2-Cdc 25C signaling pathway. Different bioactive substances utilize different protective mechanisms against DON in interacting with different cells. The proper addition of vitamin E and vitamin C to food can neutralize the toxic effect of DON, while the addition of vitamin C and MA to animal feed can reduce the harm DON does to animals.

[Pelvic coronal inclination change in adolescent flexible flatfoot surgically treated with arthroereisis]

Objective: To evaluate adolescent pelvic coronal inclination angle change after flatfoot treated with arthroereisis. Method: A case-series study. From June 2018 to September 2020, 25 children with flexible flat foot and pelvic obliquity were included in this retrospective study in Peking University Shenzhen Hospital. There were 17 males and 8 females with a mean age of (11.2±2.2) years (9-15 years). There were 5 cases of unilateral flatfoot and 20 cases of bilateral flatfoot. All of the patients were surgically treated with arthroereisis. Regular follow-up was done in 3 months, 1 and 2 years postoperatively. Weightbearing fluoroscopy of entire lower limb and foot were investigated to measure Meary's angle, calcaneal pitch angle, height difference at ankle and pelvic plane, pelvic inclination and sacrum-iliac distance (F value) on coronal plane. Results: The mean Mearys' angle at 3 month postoperatively was improved when compared with that before the operation (3.1°±1.5° vs 25.9°±4.3°, P<0.001), and it remained at the same level 2 years after the operation (compared with that at 1 year after the operation, P=0.748). The calcaneal pitch angle improved significantly at 3-month follow-up when compared with that before the operation (16.6°±2.4° vs 9.9°±1.5°, P<0.001), and there was no significant change between 1 year and 2 years after operation (P=0.542). The height difference at mortise plane were also reduced at the 3-month follow-up(P<0.001), and it remained at the same level at 1 year and 2 years after the operation (P=0.159). Pelvic height difference decreased dramatically from (12.4±1.7) mm (before operation) to (7.1±1.2) mm(3 month after the operation) (P<0.001), it decreased to (3.6±1.8) mm 1 year after the operation (compared with that at 3 months after the operation, P<0.001), and no further reduction was observed 2 years after the surgery (P=0.483). The pelvic inclination angle and sacrum-iliac distance were also improved at 3-month follow-up when compared with those before the operation (both P<0.001), and they declined further 1 year after the operation(both P<0.05), but the decreasing trend disappeared at the 2-year follow-up (both P>0.05). Conclusion: For adolescent flexible flat foot patients with pelvic obliquity, the coronal inclination and pelvic height discrepancy would partially recovered with correction of flatfoot deformity, but it could not be completely corrected in the mean follow-up period of 2 years after the operation.

[Evaluation of the effect of internet-based dietary self-management on blood pressure in high-risk population of hypertension in Haikou City community]

To explore the effect of Internet+diet self-management intervention technology on the blood pressure control of hypertension high-risk population through the intervention of hypertension high-risk population in Haikou City community, so as to provide scientific evidence for the prevention and treatment of cardiovascular diseases (CVD). The multi-stage cluster sampling method was used, and 295 hypertension high-risk participants were recruited from 15 communities in Haikou City from July to December 2021. The 15 communities were randomly divided into three groups: blank group, traditional group and Internet plus group by random number table method. The blank group referred to the group (99 participants) that did not take special intervention measures but the routine interventions in accordance with the "National Basic Public Health Service Standards (the Third Edition) Health Education Service Standards". On the basis of the blank group, the traditional group (95 participants) was intervened by giving additional traditional methods such as holding lectures and distributing popular science books. The Internet plus group (101 participants) was given additional Internet measures on the basis of the intervention of the traditional group. After 6 months, questionnaires, laboratory biochemical tests, and physical measurements were conducted. SPSS 25.0 software was applied for data analysis. Measurement data that followed normal distribution were statistically described by using mean±standard deviation, analysis of variance was used for inter group comparisons before intervention, analysis of covariance was used for inter group comparisons after intervention, and Bonferroni adjustment was used for pairwise comparisons between groups. Measurement data that did not follow the Normal distribution were represented by M (Q1, Q3). The rank sum test was used for inter group comparison. The k sample Kruskal Wallis single factor ANOVA was used to compare the distribution between different groups. Counting data were described by composition ratio or rate. Under the premise of balanced comparison between groups before intervention, Chi-squared test was used for inter group comparison after intervention, and Bonferroni adjustment method was used for pairwise comparison between groups. The results showed that a total of 295 participants were included, with males accounting for 35.6% (105) and females accounting for 64.4% (190). The age ranged from 55 to 74 years old, with an average age of (64.69±5.73) years. The number of married accounted for 95.6% (282 participants). There were no statistically significant differences in gender, age, family history, education level, occupation, marital status, drinking habits, regular exercise, dietary status, SBP (systolic blood pressure), DBP (diastolic blood pressure), pulse pressure difference, BMI (body mass index), folic acid, and 24-hour urine sodium among the three groups upon enrollment (P values>0.05). After the intervention, the drinking rate was as follows: Internet plus group (29, 28.7%) Collapse

Key Words Collapse

MESH Headings

• Male
• Female
• Humans
• Middle Aged
• Aged
• Blood Pressure
• Self-Management
• Hypertension/epidemiology
• Hypertension/prevention & control
• Cardiovascular Diseases/prevention & control
• Diet
• Sodium
• Internet
• Folic Acid

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Grants

• 81860577 National Natural Science Foundation of China
• 2017YFC0907104 National Key Research and Development Program of China

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Affiliation(s)

L M He Department of Nutrition and Food Hygiene, International School of Public Health and One Health, Hainan Medical University, Haikou 571199, China
Y X Yan Department of Public Health, the First Affiliated Hospital of Hainan Medical University, Haikou 570102, China
C J Zhao Department of Health Statistics, International School of Public Health and One Health, Hainan Medical University, Haikou 571199, China
X L Zhu Department of Public Health, the First Affiliated Hospital of Hainan Medical University, Haikou 570102, China
B F Liang Department of Public Health, the First Affiliated Hospital of Hainan Medical University, Haikou 570102, China
G T Lin Department of Nutrition and Food Hygiene, International School of Public Health and One Health, Hainan Medical University, Haikou 571199, China
J C Chen Immunisation Programme Division, Haikou Centre for Disease Control and Prevention, Haikou 570312, China
F Zhang Department of Nutrition and Food Hygiene, International School of Public Health and One Health, Hainan Medical University, Haikou 571199, China

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Serum metabolic markers and metabolic pathways in rats with metabolomic cecal ligation and puncture-induced sepsis

The aim of this study was to explore the dynamic changes in characteristic serum metabolic markers and pathways during early sepsis in rats. By using cecal ligation and puncture (CLP), we made rat models of sepsis, which were randomly divided into 5 groups with 10 rats in each group: group A, group B, group C, group D, and group E. We collected 2 mL of arterial blood at 0, 6, 12, 24, and 48 hours from rats in group A-E respectively and isolated serum via centrifugation. Next, adopting metabolomics analysis methods, we screened for metabolites from the animal serum with statistically and biologically significant abundance changes, and used the KEGG database to analyze the respective metabolic pathways. In all, our findings reveal that D-glucosamine 6-phosphate, D-glucosamine phosphate, α-D-glucosamine 1-phosphate, D-glucosamine 1-phosphate, and 5-hydroxy isocyanate decline continuously from 12 hours, while L-phenylalanine, (S) -α-amino-β-phenylpropionic acid, 5-methoxy indole acetic acid salt, 5-methoxy indole acetic acid, goose deoxyglycolic acid salt, goose deoxyglycolic acid, and Chen's deoxygenated sugar alcohol started to decrease from 6 hours. Additionally, 3.2,3-Bis-O-(geranyl geranyl)-sn-glycerol- 1-phosphoric acid-L-serine levels rose continuously from 12 hours. We found 13 differentially regulated ions, primarily ones involved in pathways responsible for the metabolism of sugar, amino acids, and lipids, which are related to the disorder of energy metabolism. Our findings mark serum-derived D-glucosamine and its phosphorous derivatives as characteristic metabolic markers of sepsis in rats.

A chimeric protein comprising the glucosyltransferase and cysteine proteinase domains of toxin B and the receptor binding domain of toxin A induces protective immunity against Clostridium difficile infection in mice and hamsters

Clostridium difficile is the major cause of hospital-acquired infectious diarrhea and colitis in developed countries. The pathogenicity of C. difficile is mainly mediated by the release of 2 large potent exotoxins, toxin A (TcdA) and toxin B (TcdB), both of which require neutralization to prevent disease occurrence. We have generated a novel chimeric protein, designated mTcd138, comprised of the glucosyltransferase and cysteine proteinase domains of TcdB and the receptor binding domain of TcdA and expressed it in Bacillus megaterium. To ensure that mTcd138 is atoxic, 2 point mutations were introduced to the glucosyltransferase domain of TcdB, which essentially eliminates toxicity of mTcd138. Parenteral immunizations of mice and hamsters with mTcd138 induced protective antibodies to both toxins and provided protection against infection with the hyper-virulent C. difficile strain UK6.

Screening of single-stranded DNA (ssDNA) aptamers against a zearalenone monoclonal antibody and development of a ssDNA-based enzyme-linked oligonucleotide assay for determination of zearalenone in corn

A hypotoxic immunosorbent assay for the detection of zearalenone (ZEN) was developed, by identifying a single-stranded DNA (ssDNA) aptamer with high specificity and affinity for a ZEN monoclonal antibody (mAb-ZEN). ssDNA aptamers, which could mimic ZEN epitopes, were identified using the modified systematic evolution of ligands by an exponential enrichment (SELEX) technique. The purified mAb-ZEN was coated on microtiter plates as a target recognized by the random oligonucleotide ssDNA library. The binding affinity between the aptamers and mAb-ZEN during each round was measured by the biotin–streptavidin–horseradish peroxidase system. During 15 rounds of screening, an increasing binding affinity was observed. The enriched ssDNA library binding to mAb-ZEN with high affinity was cloned, sequenced, and analyzed. One aptamer (number 46), which displays the highest affinity and specificity for the mAb-ZEN, was used to establish an indirect competition enzyme-linked oligonucleotide assay (ELONA) to measure the ZEN concentration in corn. Under optimal conditions, the regression equation for quantification of ZEN was y = −0.0778x + 0.713 (R2 = 0.9981). The detection limit and IC50 were 0.01 and 0.2 ng/mL, respectively, with a working range of 0.03–2.5 ng/mL. The recovery rates of the spiked samples in the ELONA ranged from 95 to 105%. Aptamers, which can mimic many types of low-weight analytes in agricultural products, could serve as surrogates for the development of hypotoxic, environmentally friendly immunological detection methods.

Histological changes within dental pulps in teeth with moderate-to-severe chronic periodontitis

AIM

To investigate the effect of chronic periodontitis on dental pulps by assessing histological changes in the pulps of teeth with moderate-to-severe periodontitis.

METHODOLOGY

A total of 242 teeth from 162 patients with moderate-to-severe periodontitis were collected, and histological changes in pulps were investigated by staining with haematoxylin and eosin. Baseline data were taken from the patients' records before extraction. The morphologic changes observed in the pulp were classified as degree I, degree II, degree III and degree IV. Statistical analysis of the severity of periodontitis and histological changes with the pulps was applied using the Mann-Whitney U rank sum test, whilst the contingency coefficient was used to analyse the inter-relationship between the severity of periodontitis and histological changes in the pulps.

RESULTS

The inter-relationship between the severity of periodontitis and histological changes in the pulps was 0.274 (P < 0.001), and significant differences existed between teeth with moderate periodontitis and severe periodontitis group (Z = 4.145, P < 0.001). The inter-relationship between attachment loss and histological changes in the pulps was 0.397 (P < 0.001). There were significant differences in the histological changes amongst teeth with various degrees of attachment loss (χ(2) = 33.023, P < 0.001) and amongst teeth in different locations (χ(2) = 23.163, P < 0.001).

CONCLUSIONS

There was a positive association between the severity of periodontitis and histological changes within the pulp. More attachment loss was correlated with pathological changes within the dental pulp.

Simultaneous quantitative determination of multiple mycotoxins in cereal and feedstuff samples by a suspension array immunoassay

Mycotoxins produced by different species of fungi may coexist in single cereal and feedstuff samples, which could become highly toxic for humans and animals. In order to quantify four mycotoxins (zearalenone, fumonisin B1, deoxynivalenol, and aflatoxin B1) in cereal and feedstuff samples simultaneously, a new suspension array immunoassay was developed. Antimycotoxin monoclonal antibodies were conjugated to the surface of different encoding microspheres (19#, 37#, 39#, and 49#), and mycotoxin-protein conjugates were then coupled with biotin. Using streptavidin-phycoerythrin as a signal reporter protein, this direct competition multiple suspension array immunoassay was optimized. The results showed that the detection limits for zearalenone, fumonisin B1, deoxynivalenol, and aflatoxin B1 were 0.51, 6.0, 4.3, and 0.56 ng/mL, respectively, with detection ranges of 0.73-6.8, 11.6-110.3, 8.6-108.1, and 1.1-14.1 ng/mL, respectively. For the detection of the spiked samples, the recovery rates were between 92.3% and 115.5%. This method also shows a good correlation coefficient (r = 0.99, P < 0.01) with liquid chromatography-tandem mass spectrometry in the detection of toxins in commercial cereal and feedstuff samples. This suspension array immunoassay was high-throughput and accurate for the rapid quantitative detection of multiple mycotoxins in commercial cereal and feedstuff samples.

Rapid simultaneous quantification of zearalenone and fumonisin B1 in corn and wheat by lateral flow dual immunoassay

A lateral flow dual immunoassay (LFDIA) was developed for rapid quantitative detection of zearalenone (ZEN) and fumonisin B1 (FB1) in corn and wheat samples on a single test strip. Two test lines and the control line on the nitrocellulose membrane were coated with ZEN and FB1 conjugates and goat anti-mouse IgG, respectively. Colloidal gold nanoparticles were conjugated with monoclonal antibodies against ZEN or FB1. The intensity of the test lines was analyzed by a photometric strip reader to determine the concentrations of ZEN and FB1 based on the calibration curves of known concentrations versus intensity readings. Test parameters such as types of buffers, ratio of the two gold-labeled antibodies, and dilution of the sample extracts and the gold-labeled antibodies were optimized. The detection limit was 0.35 and 5.23 ng/mL for ZEN and FB1, respectively, and the corresponding detection ranges were 0.94-7.52 and 9.34-100.45 ng/mL, respectively. Spiked and natural samples were analyzed using both LFDIA and liquid chromatography-tandem mass spectrometry. The two methods had a good correlation (R(2) = 0.96). The dual quantitative LFDIA is sensitive, rapid, and easy-to-use for on-site testing of a large number of samples.

Novel chemiluminescence immunoassay for the determination of zearalenone in food samples using gold nanoparticles labeled with streptavidin-horseradish peroxidase

A novel highly sensitive chemiluminescence immunoassay (CLIA) was developed to detect zearalenone in food samples by using both biotinylated zearalenone conjugates and gold (Au) nanoparticles labeled with streptavidin-horseradish peroxidase for signal amplification. Biotinylated zearalenone-ovalbumin conjugates and Au nanoparticles labeled with streptavidin-horseradish peroxidase were synthesized separately. The concentrations of immunoreagents and the reaction times of these immunoreagents were optimized to improve the performances of analytical methods. For the CLIA based on biotinylated zearalenone conjugates and Au nanoparticles labeled with streptavidin-horseradish peroxidase, the limit of detection was 0.008 ng/mL and the IC50 was 0.11 ng/mL. The linear working range was 0.02-0.51 ng/mL. The cross-reactivities with the zearalenone analogues (α-zearalanol, zearalanone, α-zearalenol, β-zearalanol, and β-zearalenol) were 32, 17, 12, 0.3, and 0.1%, respectively. The recovery rates in spiked food samples were 97-117%, and the intraday and interday relative standard deviations were both <10%. Parallel analysis of natural food samples showed a good correlation between this novel CLIA and liquid chromatography-tandem mass spectrometry. This method provides a rapid, accurate, and highly sensitive method to determine levels of zearalenone in food samples.

[Lysogenic infection of a Shiga toxin 2-converting bacteriophage changes host gene expression, enhances host acid resistance and motility]

Shiga toxin 2 (Stx2)-converting bacteriophages can infect and lysogenize other bacteria in vivo and in vitro, and, thus, contribute to a genotypic heterogeneity of infected host. However, the global transcription patterns accompanying the lysogenic infection of E. coli host have not been clearly resolved. In this study, gene expression profiles of Stx2 phage phi Min27(delta stx::cat) converted and native E. coli MG1655 hosts were compared using microarray assay. The phi Min27(delta stx::cat) conversion had a direct effect on the global expression of bacterial host genes as 166 genes were found to be differentially expressed (104 up-regulated and 62 downregulated). These genes were predominantly responsible for bacterial central metabolism, transport and transcription. It was shown that in addition to the down-regulation of genes involved in synthesis of thiamine and protein transporters, expression of genes associated with bacterial energy production (e.g., fadABDEHIJL, aceK, and acnA) was also suppressed. Conversely, most up-regulated genes were transport genes, flagellar synthesis genes (fliDESTZ), and acid resistance genes (e.g., gadEW, hdeABD, and adiY). Futhermore, conversion of phi Min27(delta stx::cat) was shown to change physiological properties of the host cell. In comparison with the uninfected cells the converted bacteria host had increased acid tolerance and promoted swimming motility on a semisolid agar surface.

Upconversion luminescence of CdTe nanocrystals by use of near-infrared femtosecond laser excitation

We study the steady-state and time-resolved luminescent properties of CdTe nanocrystals by one- and two-photon excitation with a femtosecond laser. We observe that 1208 nm excitation causes a shift of the emission peak of about 20 nm to the infrared compared with 400 nm laser excitation. It is found that upconversion luminescence is composed of a photoinduced trapping and a band edge excitonic state and produces the observation of biexponential decay kinetics. We conclude that the redshift of the emission peak is caused by the relative change in luminescence intensity between excitonic and trapping states.

DNA immunization against very virulent infectious bursal disease virus with VP2-4-3 gene and chicken IL-6 gene

The present study was to investigate the feasibility and efficiency of the DNA vaccine to protect chickens against very virulent infectious bursal disease virus (vvIBDV) infection. A plasmid DNA carrying VP2-4-3 genes of vvIBDV SH95 and a plasmid DNA carrying chicken interleukin-6 (ChIL-6) genes were constructed and designated as pALTER-MAX-VP2-4-3 and pALTER-MAX-ChIL-6 respectively. Several DNA vaccination experiments were performed: 1-week-old chickens were intramuscularly injected with only plasmid pcDNA3-VP2, pALTER-MAX-VP2-4-3 or mixture with pALTER-MAX-ChIL-6. The chickens at 4 weeks old were orally inoculated with vvIBDV SH95. The results showed that immunization with the mixture of pALTER-MAX-VP2-4-3 and pALTER-MAX-ChIL-6 three times conferred protection for 90% of chickens. Enzyme-linked immunosorbent assay (ELISA) antibody titres in chickens immunized together with pALTER-MAX-ChIL-6 were higher than those immunized simply with plasmid pcDNA3-VP2 or pALTER-MAX-VP2-4-3. IBDV was not detected in the bursa of the protected chickens at 8 days after challenge by RT-PCR. The results indicate that protection against vvIBDV can be achieved by using the VP2-4-3 gene of vvIBDV as a DNA vaccine. Furthermore, the simultaneous injection of ChIL-6 plasmid significantly increased the protection after challenge with the very virulent strain.

The role of central arginine vasopressin in corticotropin releasing hormone-induced fever in rats

The purpose of the present study was to investigate the role of central arginine vasopressin (AVP) in corticotropin releasing hormone (CRH) induced fever in the rat. Guide cannulae were inserted into the third ventricle and placed over the ventral septal area (VSA). The content of arginine vasopressin in the VSA of the brain was determined by radioimmunoassay. Colon temperature was monitored in lightly restrained rats by insertion of a catheter mounted thermistor probe 5 cm in the rectum. The results demonstrated that intracerebroventricular (icv) injection of CRH increased AVP level in the VSA and the colonic temperature of the rats. Microinjection of AVP V(1) antagonist into the VSA 10 min before CRH administration significantly enhanced CRH-induced febrile response, while AVP V(1) antagonist itself did not have a significant effect on the colonic temperature. Furthermore, injection of AVP into the VSA 5 min before CRH administration (icv) suppressed the fever evoked by CRH. These findings suggest that CRH is an important factor that stimulates the release of AVP in the VSA during fever, and endogenous AVP in the VSA has an antipyretic action on the CRH-induced fever.

Novel methods for chemiluminescent detection of reporter enzymes

Chemiluminescent reporter gene assays provide highly sensitive, quantitative detection in simple, rapid assay formats for detection of reporter enzymes that are widely employed in gene expression studies. Chemiluminescent detection methodologies typically provide up to 100-1000x higher sensitivities than may be achieved with fluorescent or colorimetric enzyme substrates. The variety of chemiluminescent 1,2-dioxetane substrates available enable assay versatility, allowing optimization of assay formats with the available instrumentation, and are ideal for use in gene expression assays performed in both biomedical and pharmaceutical research. In addition, 1,2,-dioxetane chemistries can be multiplexed with luciferase detection reagents for dual detection of multiple enzymes in a single sample. These assays are amenable to automation with a broad range of instrumentation for high throughput compound screening.

Intestinal cell kinase (ICK) localizes to the crypt region and requires a dual phosphorylation site found in map kinases

Identification of key regulatory kinases in the intestinal epithelium are useful to understand the molecular mechanisms that underlie proliferation and differentiation in cells found in this compartment. We used the polymerase chain reaction (PCR) to amplify the catalytic kinase domain of serine-threonine kinases by employing degenerate primers and then screened an intestinal crypt cDNA library to clone and sequence the open reading frame of a novel serine-threonine kinase. This was then further characterized by Northern blot analysis and RNA in situ hybridization. This kinase, designated intestinal cell kinase, harbors a dual phosphorylation site found in mitogen-activating protein (MAP) kinases that is important for kinase activity.

Transforming growth factor-alpha enhances cyclin D1 transcription through the binding of early growth response protein to a cis-regulatory element in the cyclin D1 promoter

Cyclin D1 is a critical oncogene involved in the regulation of progression through the G1 phase of the cell cycle, thereby contributing to cell proliferation. This is mediated through interaction of cyclin D1 with its catalytic partners, the cyclin-dependent kinases, and the subsequent phosphorylation of the retinoblastoma protein. Cyclin D1, in turn, is regulated by mitogenic stimuli. We demonstrate that transforming growth factor-alpha (TGFalpha) induces cyclin D1 mRNA in esophageal squamous epithelial cells, and this appears to correlate with increased cyclin D1 protein expression and cyclin-dependent kinase 6 activity. The induction of cyclin D1 transcription by TGFalpha is mediated in part through the induction of the early growth response protein (Egr-1) and its subsequent binding of Egr-1 to a cis-regulatory region spanning nucleotides -144 to -104 of the cyclin D1 promoter. The Egr-1 binding activity to the cyclin D1 promoter appears to require de novo protein synthesis and is not influenced by Sp1 binding to overlapping Sp1 motifs. Taken together, these data provide evidence that TGFalpha enhances cyclin D1 transcription through the induction of Egr-1 binding to a cis-regulatory region in the cyclin D1 promoter. This has important mechanistic implications into the transcriptional regulation of cyclin D1 by an essential proproliferative growth factor and cell cycle progression.

Ki-ras and p53 mutations in pancreatic ductal adenocarcinoma

Pancreatic adenocarcinoma involves activation of the Ki-ras oncogene, inactivation of the p53 tumor suppressor gene, and dysregulation of growth factors and perhaps metastasis genes. Ki-ras oncogene point mutations are known to be involved in pancreatic oncogenesis. The p53 tumor suppressor gene product plays a critical role in cell cycle regulation and also functions as a nuclear transcription factor. Point mutations in the p53 gene have been observed in a variety of malignancies. We determined the frequency of p53 protein overexpression and p53 point mutations in the conserved and nonconserved domains in pancreatic cancers as well as the coincidence of Ki-ras mutation in pancreatic ductal adenocarcinoma. Genomic DNA was isolated from 20 frozen pancreatic adenocarcinomas (14 primary, six metastases) along with six specimens of control pancreatic tissue and screened by single-strand conformation polymorphism (SSCP) analysis followed by direct genomic sequencing of SSCP variants. SSCP analysis was accomplished by incorporating 32P-dCTP in 12 separate polymerase chain (PCR) amplifications covering the p53 coding exons 2-11. All mobility shifts on SSCP were subjected to direct genomic sequencing by the modified dideoxy method. Immunoperoxidase (IP) staining was also done with a p53 monoclonal antibody. Ki-ras codon 12 mutational analysis was accomplished by incorporating 32P-dCTP by polymerase chain reaction amplification utilizing mismatched primers, which create a BstN1 restriction endonuclease site spanning codon 12; the products were digested by BstN1. Polyacrylamide gel electrophoresis allowed distinction between wild-type and mutant Ki-ras. p53 mutations were found in 5 of 20 pancreatic cancers (three of 14 primary tumors, two of six metastatic tumors). Point mutations were observed in three of 14 primary tumors, and one of six metastases, while a 2-base pair duplication resulting in a premature stop codon in exon 5 was found in one metastatic tumor. Point mutations were noted in conserved domains (exons 4, 5, 8) and in the nonconserved domain (exon 10). IP staining revealed that eight of 14 of the primary tumors and two of six metastases exhibited moderate to strong nuclear staining (> 30%), while no nuclear staining was evident in the controls. Ki-ras codon 12 mutations were found in 14 of 20 (70%) pancreatic cancers (nine of 14 primary tumors, five of six metastatic tumors) and none of the six controls. Fifty percent of the primary pancreatic tumors demonstrated moderate to strong nuclear staining. Extensive genetic analysis demonstrated mutations in 30% of the pancreatic cancers. One cancer had a nonsense mutation not detected by IP. Seven of 19 (37%) pancreatic cancers exhibited both Ki-ras point mutation and p53 protein overexpression or mutation. Both genetic analysis and IP are required to characterize all p53 mutations in pancreatic cancer. Ki-ras codon 12 mutations and p53 protein overexpression are important steps in pancreatic oncogenesis.

WT1 induces expression of insulin-like growth factor 2 in Wilms' tumor cells

The Wilms' tumor suppressor gene WT1 encodes a zinc finger transcription factor, whose expression inhibits the growth of the RM1 Wilms' tumor cell line. Transient transfection of WT1 constructs into 3T3 or 293 cells results in transcriptional repression of a number of cotransfected promoters containing the early growth response gene 1 consensus sequence. We now show that WT1 has properties of a transcriptional activator in RM1 cells, an effect that may be associated with the presence of a mutated p53 gene in these cells. Stable transfection of wild-type WT1 into RM1 cells results in induction of endogenous insulin-like growth factor 2 (IGF2) but not of other previously postulated WT1-target genes. The induction of IGF2 is dramatically enhanced by WT1 mutants encoding an altered transactivation domain. We conclude that IGF2 is a potentially physiological target gene for WT1 and that its induction may contribute to the growth-stimulating effects of WT1 variants.

Mating-type suppression of the DNA-repair defect of the yeast rad6 delta mutation requires the activity of genes in the RAD52 epistasis group

The RAD6 gene of Saccharomyces cerevisiae is required for post-replication repair of UV-damaged DNA, UV mutagenesis, and sporulation. Here, we show that the radiation sensitivity of a MATa rad6 delta strain can be suppressed by the MAT alpha 2 gene carried on a multicopy plasmid. The a1-alpha 2 suppression is specific to the RAD6 pathway, as mutations in genes required for nucleotide excision repair or for recombinational repair do not show such mating-type suppression. The a1-alpha 2 suppression of the rad6 delta mutation requires the activity of the RAD52 group of genes, suggesting that suppression occurs by channelling of post-replication gaps present in the rad6 delta mutant into the RAD52 recombinational repair pathway. The a1-alpha 2 repressor could mediate this suppression via an enhancement in the expression, or the activity, of recombination genes.

Mutational analysis of the carboxy-terminal portion of p53 using both yeast and mammalian cell assays in vivo

Increasing evidence indicates that p53 is a transcriptional trans-activator through its sequence-specific DNA binding domain. Tumor-derived p53 mutations disrupt the trans-activation ability mainly due to loss of its sequence-specific DNA binding. Using both yeast and mammalian cell assays, the effect of p53 mutations in the carboxy terminal portion was investigated in order to address how p53 mutations outside of the DNA binding domain affect p53 function. The p53 cDNA in the carboxy-terminus was randomly mutagenized by error-prone polymerase chain reactions and the amplified cDNA was screened for the ability to trans-activate using a yeast assay. Four p53 mutations, including two missense and two nonsense mutations located in the carboxy-terminal oligomerization domain, were further analysed for trans-activation, cell cycle arrest and colony formation in a human osteosarcoma cell line, Saos-2. These functional properties of p53 were disrupted by the missense mutations. Surprisingly, one of the nonsense mutations disrupts the trans-activation function and the ability to G1 arrest but shows a strong inhibition of colony formation. These results confirm that mutations in the oligomerization domain can inactivate p53 function and also indicate that p53-mediated cell growth inhibition does not necessarily depend on the ability to arrest cell cycle.

Germ-line p53 mutations in 15 families with Li-Fraumeni syndrome

Germ-line mutations of the tumor-suppressor gene p53 have been observed in some families with the Li-Fraumeni syndrome (LFS), a familial cancer syndrome in which affected relatives develop a diverse set of early-onset malignancies including breast carcinoma, sarcomas, and brain tumors. The analysis of the p53 gene in LFS families has been limited, in most studies to date, to the region between exon 5 and exon 9. In order to determine the frequency and distribution of germ-line p53 mutations in LFS, we sequenced the 10 coding exons of the p53 gene in lymphocytes and fibroblast cell lines derived from 15 families with the syndrome. Germ-line mutations were observed in eight families. Six mutations were missense mutations located between exons 5 and 8. One mutation was a nonsense mutation in exon 6, and one mutation was a splicing mutation in intron 4, generating aberrant shorter p53 RNA(s). In three families, a mutation of the p53 gene was observed in the fibroblast cell line derived from the proband. However, the mutation was not found in affected relatives in two families and in the blood from the one individual, indicating that the mutation probably occurred during cell culture in vitro. In four families, no mutation was observed. This study indicates that germ-line p53 mutations in LFS are mostly located between exons 5 and 8 and that approximately 50% of patients with LFS have no germ-line mutations in the coding region of the p53 gene.(ABSTRACT TRUNCATED AT 250 WORDS)

MTS-1 (CDKN2) tumor suppressor gene deletions are a frequent event in esophagus squamous cancer and pancreatic adenocarcinoma cell lines

MTS-1 is a candidate tumor suppressor gene on chromosome 9p21-22, a region frequently observed to have loss of heterozygosity in esophagus squamous cell carcinomas and pancreatic ductal adenocarcinomas. In order to determine whether MTS-1 sequences are deleted or mutated in cell lines derived from these cancers, we performed PCR amplification of MTS-1 exons 1 and 2. In this fashion, we found that 67% of esophagus squamous cancer cell lines have deletions of both exons 1 and 2, and 50% of pancreatic cancer cell lines have similar deletions. Furthermore, an additional 30% of pancreatic cancer cell lines harbored point mutations or microdeletions based on DNA sequencing. MTS-1 encodes p16, an inhibitor of cyclin-dependent kinase 4 (cdk4) which complexes with cyclin D1. Our data suggest that MTS-1 deletions and mutations may play an important role in the molecular pathogenesis of esophagus squamous cell and pancreatic cancers.

Identification of a human rasGAP-related protein containing calmodulin-binding motifs

Conversion of active GTP-bound Ras to its inactive GDP-bound form is catalyzed by GTPase-activating proteins (GAPs). Two mammalian Ras-specific GAPs, p120GAP and neurofibromin, the product of the NF1 tumor suppressor gene, have been previously described. We report here the identification of a new human cDNA clone, IQGAP1, which predicts a 1657-amino acid protein that displays extensive sequence similarity to the catalytic domain of all previously reported RasGAPs. IQGAP1 is most closely related to the Schizosaccharomyces pombe RasGAP-like protein, Sar1. Sequence similarity to IQGAP1 is seen throughout the entire Sar1 protein. The N-terminal half of IQGAP1, which does not overlap with Sar1, contains six copies of a unique amino acid motif, as well as four so-called IQ motifs. The latter motifs are found in several proteins, including conventional and unconventional myosins, and mediate the interaction with calmodulin and calmodulin-related proteins. Thus, IQGAP1 appears to represent a novel RasGAP-like protein that may link Ras signaling to some calmodulin-mediated process.

Germline mutations of the p53 tumor suppressor gene in children with osteosarcoma

PURPOSE

We investigated the possibility that a significant proportion of children with osteosarcoma harbor germline mutations of the p53 tumor suppressor gene and, therefore, this subgroup of pediatric cancer patients should be considered for large-scale predictive testing.

PATIENTS AND METHODS

Genomic DNA extracted from peripheral-blood leukocytes from 235 unselected children with osteosarcoma from 33 institutions were screened for the presence of germline p53 mutations using constant denaturant gel electrophoresis (CDGE). Exons 5 through 8 were evaluated in all patients and exon 2 and exon 9 were analyzed in 59 and 95 patients, respectively. Those samples that showed aberrant migration on CDGE were sequenced or analyzed by restriction enzyme digestion of polymerase chain reaction (PCR) products to confirm the nature of the gene alteration.

RESULTS

In 18 samples, CDGE showed fragments of the p53 gene with altered electrophoretic mobilities compared with wild-type p53. DNA sequencing showed that 11 samples had an identical, previously described polymorphism. The other seven contained heterozygous p53 mutations located in exon 5 (n = 3), exon 6 (n = 1), exon 7 (n = 1), and exon 8 (n = 2). Six alterations were missense mutations and one was a nonsense mutation. Three of these patients had first-degree relatives with cancer. One of these three kindreds had a family history consistent with Li-Fraumeni syndrome (LFS).

CONCLUSION

We identified germline p53 mutations in seven of 235 (3.0%) children with osteosarcoma. Four of these mutations were found in patients who did not have first-degree relatives with cancer. Although genetic transmission of the altered p53 gene could not be tested in this survey because of how it was designed, it is possible that predictive testing for p53 mutations could identify unaffected relatives of gene carriers who also have a high risk for the development of cancer. This study provides evidence for the importance of considering children with osteosarcoma for predictive testing for germline p53 mutations.

Screening patients for heterozygous p53 mutations using a functional assay in yeast

Inherited mutations of the p53 gene significantly increase the risk of developing diverse malignancies, and germline p53 mutations can be detected by assaying the transcriptional activity of the p53 protein in mammalian cells. Here we describe a method starting with lymphocytes that allows detection of germline p53 mutations by 'functional' analysis of p53 protein expressed in Saccharomyces cerevisiae. The p53 PCR products are directly cloned into yeast expression vectors in vivo and subsequently tested for transcriptional activity in a simple growth assay. This technique, functional analysis of separated alleles in yeast (FASAY), requires only a few steps, can be automated readily and should permit screening for germline or somatic heterozygous mutations in any gene whose function can be monitored in yeast.