Study of the cellular and humoral immune responses to SARS-CoV-2 vaccination

Our understanding of cellular immunity in response to COVID-19 infection or vaccination is limited because of less commonly used techniques. We investigated both the cellular and humoral immune responses before and after the administration of a third dose of the SARS-CoV-2 vaccine among a group of healthcare workers. Cellular immunity was evaluated using the VIDAS interferon-gamma (IFNγ) RUO test, which enables automated measurement of IFNγ levels after stimulating peripheral blood lymphocytes. Booster doses significantly enhanced both cellular and humoral immunity. Concerning cellular response, the booster dose increased the percentage of positive IFNγ release assay (IGRA) results but no difference in IFNγ release was found. The cellular response was not associated with protection against SARS-CoV-2 infection. Interestingly, vaccinated and infected healthcare workers exhibited the highest levels of anti-spike and neutralizing antibodies. In conclusion, the IGRA is a simple method for measuring cellular immune responses after vaccination. However, its usefulness as a complement to the study of humoral responses is yet to be demonstrated in future research.

Current immunoassays and detection of antibodies elicited by Omicron SARS-CoV-2 infection

The present study aimed to determine whether current commercial immunoassays are adequate for detecting anti-Omicron antibodies. We analyzed the anti-SARS-CoV-2 antibody response of 23 unvaccinated individuals 1-2 months after an Omicron infection. All blood samples were tested with a live virus neutralization assay using a clinical Omicron BA.1 strain and four commercial SARS-CoV-2 immunoassays. We assessed three anti-Spike immunoassays (SARS-CoV-2 IgG II Quant [Abbott S], Wantaï anti-SARS-CoV-2 antibody ELISA [Wantaï], Elecsys Anti-SARS-CoV-2 S assay [Roche]) and one anti-Nucleocapsid immunoassay (Abbott SARS-CoV-2 IgG assay [Abbott N]). Omicron neutralizing antibodies were detected in all samples with the live virus neutralization assay. The detection rate of the Abbott S, Wantai, Roche, and Abbott N immunoassays were 65.2%, 69.6%, 86.9%, and 91.3%, respectively. The sensitivities of Abbott S and Wantai immunoassays were significantly lower than that of the live virus neutralization assay (p = 0.004, p = 0.009; Fisher's exact test). Antibody concentrations obtained with anti-S immunoassays were correlated with Omicron neutralizing antibody concentrations. These data provide clinical evidence of the loss of performance of some commercial immunoassays to detect antibodies elicited by Omicron infections. It highlights the need to optimize these assays by adapting antigens to the circulating SARS-CoV-2 strains.

Rat Hepatitis E Virus: Presence in Humans in South-Western France?

Background: Hepatitis E Virus (HEV) is one of the most common causes of hepatitis worldwide, and South-Western France is a high HEV seroprevalence area. While most cases of HEV infection are associated with the species Orthohepevirus-A, several studies have reported a few cases of HEV infections due to Orthohepevirus-C (HEV-C) that usually infects rats. Most of these human cases have occurred in immunocompromised patients. We have screened for the presence of HEV-C in our region. Methods and Results: We tested 224 sera, mostly from immunocompromised patients, for HEV-C RNA using an in-house real time RT-PCR. Liver function tests gave elevated results in 63% of patients: mean ALT was 159 IU/L (normal < 40 IU/L). Anti-HEV IgG (49%) and anti-HEV IgM (9.4%) were frequently present but none of the samples tested positive for HEV-C RNA. Conclusion: HEV-C does not circulate in the human population of South-Western France, despite the high seroprevalence of anti-HEV IgG.

Testing individual and pooled saliva samples for sars-cov-2 nucleic acid: a prospective study

Control of the rapid spread of the SARS-CoV-2 virus requires efficient testing. We collected paired nasopharyngeal swab (NPs) and saliva samples from 303 subjects (52.8% symptomatic) at a drive-through testing center; 18% of whom tested positive. The NPs, salivas and five saliva pools were tested for SARS-CoV-2 RNA using the Aptima™ assay and a laboratory-developed test (LDT) on the Panther-Fusion™ Hologic® platform. The saliva sensitivity was 80% (LDT) and 87.5% (Aptima™) whereas that of NPs was 96.4% in both assays. The pooled saliva sensitivity of 72.7% (LDT) and 75% (Aptima™) was not significantly different of that of individual saliva testing. Saliva specimens appear to be suitable for sensitive non-invasive assays to detect SARS-CoV-2 nucleic acid; pooling them for a single test will improve laboratory throughput.

Analysis of risk factors associated with recurrence of canine babesiosis caused by Babesia gibsoni

Canine babesiosis due to Babesia gibsoni (B. gibsoni) displays severe clinical manifestations. Recurrence of babesiosis after anti-babesial treatment is observable in over 10 % of the patients. The present study ascertains the risk factors and cumulative incidence of recurrence of canine babesiosis. For a sample of 145 dogs diagnosed with acute babesiosis, the following parameters were assessed over a period of 16 weeks: haematological parameters, status of anaemia, platelet count, total WBC count, haemoglobin concentration and RBC count, concurrent haemoparasitism, and secondary immune mediated haemolytic anaemia (IMHA). Patient demographics such as age, breed, sex were also recorded. The potential risk factors were statistically evaluated by the cumulative incidence function and the Kaplan-Meier method. The recurrent infections were observed in 11.8 % of the study sample. The following factors were found to associate with increased risk of recurrence: Rottweiler breed (CIR 21.8 % ± 6.9 %; p < 0.05), secondary IMHA (CIR 28.7 % ± 11.3 %; p < 0.05), RBC counts < 2 × 10⁶/μl on the day of diagnosis (CIR 16 % ± 4.6 %; p < 0.05), and persistent anaemia over 20 days post treatment (CIR 29.14 ± 7.9 %; p < 0.001). Dogs with concurrent haemoparasitic infections were predicted to have a fatal outcome in the survival analysis (disease related mortalities 25 % ± 13 %; p < 0.001). According to the findings, veterinarians need to pay attention to Rottweiler breed, dogs with secondary IMHA, concurrent haemoparasitism, low RBC counts on diagnosis and those with persistent anaemia to reduce the risk of relapse.

Optimized Hepatitis E Virus (HEV) Culture and its Application to Measurements of HEV Infectivity

Hepatitis E virus (HEV) is a major concern in public health worldwide. Infections with HEV genotypes 3, 4, or 7 can lead to chronic hepatitis while genotype 1 infections can trigger severe hepatitis in pregnant women. Infections with all genotypes can worsen chronic liver diseases. As virions are lipid-associated in blood and naked in feces, efficient methods of propagating HEV clinical strains in vitro and evaluating the infectivity of both HEV forms are needed. We evaluated the spread of clinical strains of HEV genotypes 1 (HEV1) and 3 (HEV3) by quantifying viral RNA in culture supernatants and cell lysates. Infectivity was determined by endpoint dilution and calculation of the tissue culture infectious dose 50 (TCID50). An enhanced HEV production could be obtained varying the composition of the medium, including fetal bovine serum (FBS) and dimethylsulfoxide (DMSO) content. This increased TCID50 from 10 to 100-fold and allowed us to quantify HEV1 infectivity. These optimized methods for propagating and measuring HEV infectivity could be applied to health safety processes and will be useful for testing new antiviral drugs.

Evaluation of a polymerase chain reaction-electrospray ionization time-of-flight mass spectrometry for the detection and subtyping of influenza viruses in respiratory specimens

Background

PCR coupled to electrospray ionization mass spectrometry technology (PCR/ESI-TOF-MS) (PLEX-ID system, Abbott Ibis Biosciences) was developed to characterize microbial pathogens.

Objectives

To evaluate the performance of the PLEX-ID flu detection™ kit for detecting Influenza viruses by comparison with the multiplex RespiFinder^® Kit (PathoFinder).

Study design

Acute-phase respiratory samples (n = 293) were analysed for this purpose. A subpopulation of influenza type A positive samples, identified with the RespiFinder^® kit (n = 64), were subtyped with the RealTime ready Inf A/H1N1 Detection Set^® (Roche Molecular Diagnostics) and results were compared to the PLEX-ID Flu Detection™ kit.

Results

274 samples gave concordant results (93.5%, p < 0.0001): 65 influenza A-positive, 18 influenza B-positive and 191 negative samples. Of these, 7 samples were PLEX-ID positive/RespiFinder^® negative (5 influenza A and 2 influenza B) and 12 were PLEX-ID positive/RespiFinder^® negative (10 influenza A and 2 influenza B). PLEX-ID showed one sample as an influenza A and B co-infection while the RespiFinder^® assay showed it to be influenza A-positive. The sensitivity, specificity, positive and negative predictive values of the PLEX-ID™ system were 87.4%, 96.5%, 92.2% and 94.1% respectively. Thirteen of 19 discordant samples available for retesting were investigated further with the Anyplex™II RV16 Detection kit (Seegene): seven were RespiFinder^® concordant, while six were PLEX-ID™ concordant. Subtyping of 61/64 influenza A samples was concordant (95.3%): 55 were H1N1pdm09 and six were non-H1N1pdm09. Three samples gave negative PLEX-ID™ results (one H1N1pdm09 and two non-H1N1pdm09).

Conclusions

PCR/ESI-TOF-MS technology showed good diagnostic performances to detect and subtype influenza viruses.

Performance of a rapid molecular multiplex assay for the detection of influenza and picornaviruses

BACKGROUND

Multiplex assays are a new strategy for diagnosing respiratory infections. These assays are better than those based on cultures or antigen detection, but few data are available for comparing them to monoplex polymerase chain reactions (PCRs). This study evaluated the performance of the Luminex xTAG Respiratory Viral Panel (RVP) Fast assay with reference to 2 real-time PCR assays for detecting type A influenza H1 viruses and human enteroviruses and rhinoviruses.

METHODS

This was an analysis of nasal swab specimens obtained from 590 outpatients suffering from acute respiratory tract disease between September 2009 and February 2010.

RESULTS

The RVP Fast assay performed well in less than 4 h for detecting type A influenza H1 viruses, particularly (H1N1)pdm09, and human entero/rhinoviruses, with 95.2% and 90.05% agreement, respectively, when compared to monoplex real-time PCR assays. This multiplex assay also detected at least 1 virus in 69.3% of the specimens and detected multiple infections in 40 samples.

CONCLUSIONS

The multiplex assay detected clinically important viruses in a single genomic test. It will thus be useful for detecting several viruses causing respiratory tract disorders.

Evaluation of CD83 antigen in the normal mammary epithelium and fibroadenoma human

Abstract #2038

Background: The immune response initiation requests the capture and the presentation of the antigens to the specific lymphocytes. The cells that has this capacity are denominated antigen-presenting cells, and the dendritic cell (DC) is the one that has larger specialization degree for these functions. The DC maturation it is considered essential for the beginning of the immune response. The CD83 antigen is a co-stimulator, member of the immunoglobulin superfamily with 45Kd, and your expression is an important marker of the maturation of DC.&#x2028; Objectives: To analyze the CD83 antigen expression in the human's breast fibroadenoma and in the adjacent breast tissue and to identify the clinical features that can influence this expression.&#x2028; Material and Methods: It is a retrospective study where 29 histopathologic materials of breast fibroadenomas and the adjacent breast tissue, of 28 women in reproductive age, were analyzed. The immunohistochemistry method was used for analysis of the CD83 antigen expression and, subsequently, the cells were counted by light microscopy. A thousand epithelium cells of each case were analyzed (five hundred of the fibroadenoma and five hundred of the adjacent breast tissue) for statistical calculation of the expression or not of the antigen reaction in the cells. We used parametric test (t-Student) for statistical analysis of the results.&#x2028; Results: The CD83 antigen expression positive in the fibroadenoma's cells (365.52 ± 133.13) in relation to the adjacent breast tissue's cells (189.59 ± 140.75) was statistically greater (p &lt;0.001). Several clinical features were analyzed, however, only parity showed influence in the expression of the CD83 antigen in the adjacent mammary tissues, and the positive expression was more evident in nulliparous women (p=0.042).&#x2028; &#x2028; Conclusion: The CD83 antigen expression was statistically greater in the breast fibroadenoma's cells, when compared with the one of the adjacent breast tissue. No clinical variable influenced CD83 expression in the breast's fibroadenoma, however, it was significantly greater in the adjacent normal breast tissue of nulliparous women.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2038.

Association of estrogen receptor gene alpha polymorphisms with postmenopausal mammary density

Abstract #5003

Background: With the human genome studies, knowledge about polymorphisms started raising interest in a variety of fields and, in medicine, the evidence of direct action of polymorphisms on the arising and progression of diseases, disclosing the possibility of using them as disease predisposition markers. Substitutions, insertions or deletions which are transmitted through generations and reach frequencies equal or superior to 1% in the population are named polymorphisms. Knowing that the mammographic pattern is a multifactorial character, the objectives of this study were to evaluate a possible association of clinical characteristics and polymorphisms HaeIII, MspI and XbaI of the estrogen receptor gene alpha with postmenopausal mammary density. Materials and Methods: A prospective evaluation was made of 120 women who were not hormone therapy users and had no clinically or mammographically identified breast lesions. All of them underwent bilateral mammography, and the radiological density was determined by three independent observers, with two subjective evaluations based on the ACR-BIRADS® classification of mammographic patterns, 2003, and one computerized evaluation – the grey-scale histogram tool of the Adobe Photoshop® 7.0 software. Peripheral blood samples were obtained for DNA extraction, performed according to the GFX® Kit protocol from Amersham-Pharmacia. After DNA extraction, PCR-RFLP (Polymerase Chain Reaction - Restriction Fragment Length Polymorphism) was carried out for an analysis of the polymorphisms present in intron 1 (HaeIII and XbaI) and in exon 1 (MspI) of the estrogen receptor gene. Results: There was a high degree of concordance among the observers in the determination of mammary density (Kappa, Pearson and Spearman - p&lt;0.001). The associations of clinical characteristics with mammary density were: age (p=0.04), body mass index (p&lt;0.0001), age at menarche (p=0.02), age at menopause (p=0.120), age at first delivery (p=0.120), parity (p=0.09). The relation between the allele distribution of the polymorphisms and the density was: XbaI (p=0.02), HaeIII (p=0.65), and MspI (p=0.65). Conclusion: Polymorphism XbaI and the clinical factors age, menarche and body mass index showed to be associated with postmenopausal mammary density.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5003.

Seroprevalence of Toxoplasma gondii antibodies in captive elephants (Elephaus maximus maximus) in Sri Lanka

Serum samples collected during August 2003-June 2004 from 45 privately owned captive and 8 elephants from the Pinnawala Elephant Orphanage were tested for the presence of antibodies against Toxoplasma gondii using the direct modified agglutination test (MAT). Antibodies were found in sera of 14 of 45 (32%) privately owned elephants with titers of 1:25 in three, 1:50 in three, 1:100 in three, 1:200 in three, and 1:400 in three elephants. The elephants from Pinnawala Elephant Orphanage were seronegative. This is the first report of T. gondii seroprevalence in elephants in Sri Lanka.

The Arabidopsis pxa1 mutant is defective in an ATP-binding cassette transporter-like protein required for peroxisomal fatty acid beta-oxidation

Peroxisomes are important organelles in plant metabolism, containing all the enzymes required for fatty acid beta-oxidation. More than 20 proteins are required for peroxisomal biogenesis and maintenance. The Arabidopsis pxa1 mutant, originally isolated because it is resistant to the auxin indole-3-butyric acid (IBA), developmentally arrests when germinated without supplemental sucrose, suggesting defects in fatty acid beta-oxidation. Because IBA is converted to the more abundant auxin, indole-3-acetic acid (IAA), in a mechanism that parallels beta-oxidation, the mutant is likely to be IBA resistant because it cannot convert IBA to IAA. Adult pxa1 plants grow slowly compared with wild type, with smaller rosettes, fewer leaves, and shorter inflorescence stems, indicating that PXA1 is important throughout development. We identified the molecular defect in pxa1 using a map-based positional approach. PXA1 encodes a predicted peroxisomal ATP-binding cassette transporter that is 42% identical to the human adrenoleukodystrophy (ALD) protein, which is defective in patients with the demyelinating disorder X-linked ALD. Homology to ALD protein and other human and yeast peroxisomal transporters suggests that PXA1 imports coenzyme A esters of fatty acids and IBA into the peroxisome for beta-oxidation. The pxa1 mutant makes fewer lateral roots than wild type, both in response to IBA and without exogenous hormones, suggesting that the IAA derived from IBA during seedling development promotes lateral root formation.

The Arabidopsis pxa1 mutant is defective in an ATP-binding cassette transporter-like protein required for peroxisomal fatty acid beta-oxidation

Peroxisomes are important organelles in plant metabolism, containing all the enzymes required for fatty acid beta-oxidation. More than 20 proteins are required for peroxisomal biogenesis and maintenance. The Arabidopsis pxa1 mutant, originally isolated because it is resistant to the auxin indole-3-butyric acid (IBA), developmentally arrests when germinated without supplemental sucrose, suggesting defects in fatty acid beta-oxidation. Because IBA is converted to the more abundant auxin, indole-3-acetic acid (IAA), in a mechanism that parallels beta-oxidation, the mutant is likely to be IBA resistant because it cannot convert IBA to IAA. Adult pxa1 plants grow slowly compared with wild type, with smaller rosettes, fewer leaves, and shorter inflorescence stems, indicating that PXA1 is important throughout development. We identified the molecular defect in pxa1 using a map-based positional approach. PXA1 encodes a predicted peroxisomal ATP-binding cassette transporter that is 42% identical to the human adrenoleukodystrophy (ALD) protein, which is defective in patients with the demyelinating disorder X-linked ALD. Homology to ALD protein and other human and yeast peroxisomal transporters suggests that PXA1 imports coenzyme A esters of fatty acids and IBA into the peroxisome for beta-oxidation. The pxa1 mutant makes fewer lateral roots than wild type, both in response to IBA and without exogenous hormones, suggesting that the IAA derived from IBA during seedling development promotes lateral root formation.

Cancer risk related to mammary gland structure and development

The breast undergoes dramatic changes in size, shape, and function in association with growth, reproduction, and post-menopausal regression. Those changes impact women's lifetime breast cancer risk. An early first full-term pregnancy exerts a protective effect, emphasizing the need for understanding the role of reproductive influences on breast development and on cancer initiation and progression, and providing a paradigm for developing preventive strategies based on physiological principles. Even though the cause of breast cancer and the ultimate mechanisms through which an early pregnancy protects from cancer development remain largely unknown, a likely explanation for this protection has been provided by experimental in vivo and in vitro models. These studies have led to the conclusions that cancer initiation requires the interaction of a carcinogen with an undifferentiated and highly proliferating mammary epithelium, whereas differentiation of the mammary gland inhibits carcinogenic initiation. The process of mammary gland differentiation is the result of complex interactions of ovarian, pituitary, and placental hormones, which in turn induce inhibition of cell proliferation, downregulation of estrogen and progesterone receptors, activation of specific genes, such as inhibin, mammary derived growth factor inhibitor and a serpin-like gene, and expression of extracellular matrix proteins in the normal breast. Cell immortalization and transformation are associated with the expression of ferritin H and S100P protein, which serve as markers of cancer initiation. Comparative studies of normal and neoplastic breast development have unraveled similarities with experimental models that validate the extrapolation of findings for testing hypotheses on the initiation and progression of breast cancer.

Cancer risk related to mammary gland structure and development

The breast undergoes dramatic changes in size, shape, and function in association with growth, reproduction, and post-menopausal regression. Those changes impact women's lifetime breast cancer risk. An early first full-term pregnancy exerts a protective effect, emphasizing the need for understanding the role of reproductive influences on breast development and on cancer initiation and progression, and providing a paradigm for developing preventive strategies based on physiological principles. Even though the cause of breast cancer and the ultimate mechanisms through which an early pregnancy protects from cancer development remain largely unknown, a likely explanation for this protection has been provided by experimental in vivo and in vitro models. These studies have led to the conclusions that cancer initiation requires the interaction of a carcinogen with an undifferentiated and highly proliferating mammary epithelium, whereas differentiation of the mammary gland inhibits carcinogenic initiation. The process of mammary gland differentiation is the result of complex interactions of ovarian, pituitary, and placental hormones, which in turn induce inhibition of cell proliferation, downregulation of estrogen and progesterone receptors, activation of specific genes, such as inhibin, mammary derived growth factor inhibitor and a serpin-like gene, and expression of extracellular matrix proteins in the normal breast. Cell immortalization and transformation are associated with the expression of ferritin H and S100P protein, which serve as markers of cancer initiation. Comparative studies of normal and neoplastic breast development have unraveled similarities with experimental models that validate the extrapolation of findings for testing hypotheses on the initiation and progression of breast cancer.

Mutagenicity of kaempferol in V79 cells: the role of cytochromes P450

The flavonol kaempferol is widely found in the diet and is directly mutagenic in some short-term tests, such as the induction of chromosomal aberrations in eukaryotic cells. The presence of exogenous metabolizing systems enhances its mutagenicity. We have evaluated the role of cytochromes P450 in the induction of chromosomal aberrations by kaempferol in V79 cells. The results obtained suggest that there is a time-dependent biotransformation of kaempferol to quercetin, by cytochromes P450, as assessed by high pressure liquid chromatography. Quercetin seems to contribute to the mutagenicity of kaempferol in the presence of microsomal metabolizing systems. On the other hand, the direct induction of chromosomal aberrations by kaempferol does not seem to depend on the production of reactive oxygen species.

Mechanisms of myricetin mutagenicity in V79 cells: involvement of radicalar species

Myricetin is a flavonol that is widely distributed in edible plants and although it has been proved to be genotoxic in bacteria and to induce significant concentration-dependent nuclear DNA degradation concurrent with lipid peroxidation, very little is known about its mechanisms of genotoxicity. In this work we tried to evaluate the role of rat cytochromes P450 in the genotoxicity of myricetin and to study the role that radicalar species may have in its mutagenicity. The results obtained show that the genotoxicity of myricetin as assessed by the induction of chromosomal aberrations is not different in V79 cells lines genetically engineered for the expression of rat cytochromes P450 1A1, 1A2, and 2B1, compared to parental cell lines. We have also been able to show that reactive oxygen species resulting from the autooxidation of myricetin at pH values above neutrality have an important role in its mutagenicity. Therefore, under some conditions, myricetin can act as a prooxidant.

Chemical features of flavonols affecting their genotoxicity. Potential implications in their use as therapeutical agents

Flavonls are natural compounds present in edible plants and possess several biological activities that can be useful in drug design. Conversely some of these compounds have been shown to be genotoxic to prokaryotic and eukaryotic cells. In this study we tried to establish the chemical features responsible for the genotoxicity of flavonols and to study the conditions that can modulate their genotoxicity namely pH, the presence of antioxidants and metabolism. We assessed the induction of revertants in Salmonella typhimurium TA98 and the induction of Chromosomal aberrations in V79 cells by eight different flavonols and one catechin in the presence and in the absence of metabolizing systems. We have also studied the generation of hydroxyl radical by these flavonoids using the deoxyribose degradation assay. The results obtained in this study suggest that flavonols having a free hydroxyl group at position 3 of the C ring, a free hydroxyl group at position 7 of the A ring and a B ring with a catechol or pyrogallol structure, or a structure that after metabolic activation is transformed into a catechol or a pyrogallol, are flavonols whose genotoxicity in eukaryotic cells depends on their autooxidation. These flavonols can autooxidize when the pH value is slightly alkaline, such as in the intestine, and therefore can induce genotoxicity in humans. Given the above mentioned considerations it is necessary to clarify the mechanisms and the conditions that mediate the biological effects of flavonols before considering them as therapeutical agents.

Biological and molecular basis of human breast cancer

Human breast cancer remains the most common malignancy in the American women. The ultimate cure of this disease relies on a better understanding of the mechanisms underlying the initiation and progression of this disease. The neoplastic transformation of HBEC in vitro represents a successful model for obtaining knowledge on the molecular and biological alterations that may contribute to the tumorigenic mechanisms. We have presented here a current understanding of chemically transformed HBEC in the following aspects: 1. Factors affecting the transformation of HBEC such as genetic predisposition and differentiation status and prior immortalization; 2. New targets for studying the mechanism of cell immortalization such as alterations in telomerase activity and differential expression of cell cycle dependent genes as well as others recently isolated through differential cloning such as H-ferritin, and a calcium binding protein; 3. Epigenetic and genetic mechanisms underlying cell transformation; 4. The association of microsatellite instability in specific loci on chromosomes 11, 13, and 16 with the progression of cell transformation; and 5. The application of microcell mediated chromosome transfer technique as an approach to testing the functional role of specific genes whose dysregulation or loss of function may contribute to the ultimate cell transformation. Further efforts in this cell system will be directed to determine the roles of identified molecular changes as well as the mapping/cloning of tumor suppressor or senescence genes such as those that may reside on chromosomes 11 or 17.

Identification of new genes differentially expressed in breast carcinoma cells treated with human chorionic gonadotropin

Human chorionic gonadotropin (hCG) inhibits the growth of human breast epithelial cells MCF-7. Differential display was utilized for analyzing RNA of hCG-treated MCF-7 cells in order to determine whether this effect was mediated by specific gene activation or repression. Three cDNA clones, 19, 29 and 44, were differentially expressed in treated cells. Clone 44, whose sequence matched a gene expressed in dexamethasone-treated T-cell hybridoma, was increased by approximately 4-fold, while clones 19 and 29 were markedly reduced by hCG treatment. These latter ones were considered to be novel genes, since no homology was found in the gene-bank. Our results indicate that hCG influences gene expression in mammary epithelial cells, supporting its potential role in breast cancer prevention and therapy.

Metabolism of galangin by rat cytochromes P450: relevance to the genotoxicity of galangin

The mutagenicity of flavonols seems to depend on the number and position of hydroxyl groups in the B ring. Galangin is a flavonol that does not have any hydroxyl group in the B ring and has been suggested to be a substrate of cytochromes P450 which, through the hydroxylation of the B ring, could metabolise it to more genotoxic products. The present study was undertaken to test this hypothesis. Using high performance liquid chromatography we show that glangin is sequentially transformed to kaempferol and then to quercetin by a mechanism dependent on cytochrome P450 reactions. The metabolites of galangin are responsible for its mutagenicity in Salmonella typhimurium reversion assay and for the induction of chromosomal aberrations in V79 cells.

Involvement of rat cytochrome 1A1 in the biotransformation of kaempferol to quercetin: relevance to the genotoxicity of kaempferol

Kaempferol is a flavonoid widely distributed in edible plants and has been shown to be genotoxic to V79 cells in the absence of external metabolizing systems. The presence of an external metabolizing system, such as rat liver homogenates (S9 mix), leads to an increase in its genotoxicity, which is attributed to its biotransformation to the more genotoxic flavonoid quercetin, via the cytochrome P450 (CYP) mono-oxygenase system. In the present work we investigated the mechanisms of the genotoxicity of kaempferol further. Special attention has been given to the role of CYP in the genotoxicity of this flavonoid. We studied the induction of mutations in Salmonella typhimurium TA98 in the presence and in the absence of S9 mix and the induction of chromosomal aberrations (CAs) and micronuclei (MN) by kaempferol in V79 cells in the presence and in the absence of S9 mix. To evaluate the role of different CYP in the biotransformation of kaempferol we studied the induction of CAs and MN in V79 cells genetically engineered for the expression of rat CYP 1A1, 1A2 and 2B1. In addition we performed CYP inhibition studies using the above-mentioned indicators and high performance liquid chromatography (HPLC) analysis. The results obtained in this work suggest that rat CYP 1A1 is, among the cytochromes studied, the one that plays the major role in the transformation of kaempferol into quercetin. The relevance of these findings to the human situation is discussed.

Tamoxifen down-regulates CD36 messenger RNA levels in normal and neoplastic human breast tissues

Tamoxifen (TAM) exerts a long-term suppressive effect on human breast cancer cell proliferation. To determine whether the effects of TAM are mediated by specific gene activation or repression, normal and tumoral human breast tissues obtained before and during TAM treatment were analyzed by differential display technique. Total RNA for differential display analysis was obtained from breast tissues from two women with the diagnosis of estrogen receptor-positive stage II (T2N1M0) infiltrating ductal carcinoma, made by incisional biopsy, followed by modified radical mastectomy performed after a 30-day treatment with TAM (20 mg/day). One 202-bp cDNA band, AP5-1, was present in normal and tumoral biopsy samples, but was absent in breast tissue obtained during TAM treatment, and was confirmed by Northern hybridization, which showed a 2.7-kb band in both patients. The differentially expressed cDNA fragment showed 99% homology to Homo sapiens CD36 gene, a glycoprotein that acts as a receptor for the extracellular matrix proteins thrombospondin-1, collagen types I and IV, and oxidized low-density lipoprotein. These results indicate that the down-regulation of CD36 induced by TAM might represent alternative or additional mechanisms of action of this drug affecting the functions of thrombospondin-1, which is involved in hematogenous tumor spread, invasion and angiogenesis, and oxidized low-density lipoprotein, playing a role in inhibition of arteriosclerosis. The multiple functions affected by the down-regulation of CD36 by TAM warrant the need for additional studies.

Development and validation of alternative metabolic systems for mutagenicity testing in short-term assays

We present here the results obtained within the framework of an EU funded project aimed to develop and validate alternative metabolic activating systems to be used in short-term mutagenicity assays, in order to reduce the use of laboratory animals for toxicology testing. The activating systems studied were established cell lines (Hep G2, CHEL), genetically engineered V79 cell lines expressing specific rat cytochromes P450, erythrocyte-derived systems, CYP-mimetic chemical systems and plant homogenates. The metabolically competent cell lines were used as indicator cells for genotoxic effects as well as for the preparation of external activating systems using other indicator cells. The following endpoints were used: micronuclei, chromosomal aberrations and sister chromatid exchanges, mutations at the hprt locus, gene mutations in bacteria (Ames test), unscheduled DNA synthesis and DNA breaks detected in the comet assay. All metabolic systems employed activated some promutagens. With some of them, promutagens belonging to many different classes of chemicals were activated to genotoxicants, including carcinogens negative in liver S9-mediated assays. In other cases, the use of the new activating systems allowed the detection of mutagens at much lower substrate concentrations than in liver S9-mediated assays. Therefore, the alternative metabolizing systems, which do not require the use of laboratory animals, have a substantial potential in in vitro toxicology, in the basic genotoxicity testing as well as in the elucidation of activation mechanisms. However, since the data basis is much smaller for the new systems than for the activating systems produced from subcellular liver preparations, the overlapping use of both systems is recommended for the present and near future. For example, liver S9 preparations may be used with some indicator systems (e.g., bacterial mutagenicity), and metabolically competent mammalian cell lines may be used with other indicator systems (e.g., a cytogenetic endpoint) in a battery of basic tests.

Genotoxicity assessment of aromatic amines and amides in genetically engineered V79 cells

A genetically engineered V79 cell line expressing rat CYP1A2 and another cell line expressing rat CYP1A2 as well as endogenous acetyltransferase activity, as well as CYP-deficient parental V79 cell lines, were used to assess the genotoxicity of the aromatic amines and amides 2-aminoanthracene, 2-aminofluorene, 2-acetylaminofluorene, 4-acetylaminofluorene and 2-amino-3-methylimidazo[4,5-f]quinoline, with chromosomal aberrations and sister chromatid exchanges as the end-points. None of the test compounds showed a clear effect on the frequency of chromosomal aberrations in any cell line used. Sister chromatid exchanges, however, were induced by 2-aminoanthracene, 2-aminofluorene and 2-acetylaminofluorene in the CYP1A2-proficient cells, but not in the CYP1A2-deficient cells. The presence of acetyltransferase activity enhanced the effect of 2-aminoanthracene, 2-aminofluorene and 2-acetylaminofluorene. 4-Acetylaminofluorene and 2-amino-3-methylimidazo[4,5-f]quinoline did not induce sister chromatid exchanges in the investigated cell lines. The use of cell lines with defined metabolic capabilities seems to be a valuable tool to study specific metabolic pathways important in the activation of procarcinogens.

Effects of glycolytic and cytoskeletal inhibitors on phagocytic and nitroblue tetrazolium reductive activities of bovine neutrophils

Phagocytic and oxidative metabolic activities of bovine blood neutrophils were determined in the presence of glycolytic (NaF) and cytoskeletal (colchicine, cytochalasin B, and prostaglandin E1) inhibitors. Phagocytosis and post-phagocytic oxidative metabolic activity, measured by nitroblue tetrazolium reduction, were determined using zymosan, Escherichia coli, Staphylococcus aureus, or Streptococcus agalactiae. Sodium fluoride (1.25 microM to 1.25 mM concentrations) did not significantly (P greater than 0.05) inhibit phagocytosis of S aureus and Str agalactiae, whereas phagocytosis of zymosan and E coli was significantly (P less than 0.05) inhibited only at 1.25 mM concentration. Colchicine at 1.25 nM to 1.25 microM concentrations significantly inhibited phagocytosis of zymosan and E coli, but not of S aureus and Str agalactiae. Cytochalasin B at 1.25 nM to 1.25 microM concentrations significantly inhibited phagocytosis of zymosan and all 3 bacteria, whereas prostaglandin E1 was noninhibitory at similar concentrations. Nitroblue tetrazolium reduction, in general, was not significantly affected by NaF and cytoskeletal inhibitors.

Phagocytic and nitroblue tetrazolium reductive properties of mature and immature neutrophils and eosinophils from blood and bone marrow from cows

Functional capabilities of morphologically mature (segmented) and immature granulocytes (neutrophils and eosinophils) from bone marrow from cows were studied and compared with similar activities of segmented granulocytes from blood. Phagocytosis of Escherichia coli and postphagocytic oxidative metabolic stimulation, measured by nitroblue tetrazolium (NBT) reduction, were evaluated simultaneously. Phagocytosis was observed readily in segmented neutrophils, neutrophilic bands, and metamyelocytes and rarely in myelocytes. Phagocytosis was not seen in promyelocytes and myeloblasts. Neutrophilic bands and metamyelocytes were phagocytically less active than were segmented neutrophils. Washed segmented bone marrow neutrophils possessed phagocytic activity similar to that of blood neutrophils, whereas the activity of unwashed segmented bone marrow neutrophils was markedly less than that of blood neutrophils. Reduction of NBT was observed only in blood segmented neutrophils and bone marrow segmented neutrophils; the magnitude of NBT reduction was significantly (P = less than 0.005) less in bone marrow neutrophils than in blood neutrophils. Eosinophils were phagocytically less competent than were neutrophils. The NBT reduction was observed only in eosinophils from blood, but not in eosinophils from bone marrow.

Phagocytic and postphagocytic activities of bovine neutrophils for pure and mixed bacterial cultures

A comparative study of phagocytosis and postphagocytic oxidative metabolic activity of bovine blood neutrophils incubated with pure and mixed cultures of Escherichia coli, Staphylococcus aureus, and Streptococcus agalactiae was preformed. Most neutrophils when incubated with mixed cultures showed preferential phagocytosis for one species and a smaller number phagocytized both species of microorganisms. Percent phagocytosis for E. coli in pure culture was similar to that of Strep. agalactiae in pure culture and higher than that for Staph. aureus in pure culture. Neutrophils incubated with mixed cultures of E. coli and Staph. aureus or E. coli and Strep. agalactiae showed greater than expected phagocytosis of each microorganisms alone and reduced phagocytosis of both microorganisms together. Postphagocytic oxidative metabolic activity of neutrophils, measured by percent nitroblue tetrazolium reduction, did not differ following phagocytosis of these three microorganisms in pure cultures. In comparison, a synergistic effect on nitroblue tetrazolium reductive activity was seen in mixed cultures as evidenced by higher percent nitroblue tetrazolium reduction following phagocytosis of both E. coli and Staph. aureus or E. coli and Strep. agalactiae. These observations indicate that the phagocytic and metabolic activities of neutrophils for bacteria in mixed cultures may not be identical to those in pure cultures.

Phagocytic and nitroblue tetrazolium reductive properties of bovine neutrophils for mammary pathogens

A comparative evaluation of in vitro phagocytic and metabolic activities of freshly isolated bovine blood neutrophils from 26 cows was performed. Degrees of phagocytosis and nitroblue tetrazolium reduction by neutrophils were measured using zymosan, Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, Mycoplasma bovis, Salmonella sp., and Brucella abortus opsonized with fresh bovine serum. Percent phagocytosis and nitroblue tetrazolium reduction by the neutrophils were determined by microscopic evaluation of stained coverslip smears. Individual variation among cows was found in parameters measured, but age was not a contributing factor. Phagocytosis was high (73 to 81%) for E. coli, Salmonella sp., Strep. agalactiae, and zymosan; intermediate (64%) for Staph. aureus; and low (24 to 40%) for M. bovis and B. abortus. Nitroblue tetrazolium reduction was distinctly lower than zymosan (74%) for all microorganisms. Similar percentages (32 to 41%) of nitroblue tetrazolium reduction were observed for E. coli, Staph. aureus, Strep. agalactiae, and M. bovis; intermediate (28%) was obtained for Salmonella sp. and lowest (11%) for B. abortus.