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1.
Ir J Psychol Med ; 33(4): 217-224, 2016 Dec.
Article in English | MEDLINE | ID: mdl-30115154

ABSTRACT

OBJECTIVES: Stress control (SC), a brief psycho-education course, was implemented to increase access to psychological therapies in line with Northern Irish mental health service statutory drivers. The first aim of this study was to gauge the efficacy of SC in a robust manner with clinical significance testing. The second aim was to assess whether demographics traditionally 'hard-to-reach' - males, younger adults and those from deprived areas - accessed SC. The third aim was to elucidate what prompted their access and the experiences of attendees at SC. METHODS: Attendees at SC were 170 adults over six iterations of the course. Pre- and post-questionnaires included the Depression Anxiety Stress Scales - 21, captured demographic details and qualitative feedback, which was subject to a mixed-methods analysis. RESULTS: SC attendees reported significant decreases on depression, anxiety and stress sub-scales post-intervention. Moreover, 38.71% (n=36) of attendees who completed SC exhibited clinically significant improvement afterwards on one or more sub-scale. Attendance figures for males, younger adults and those classified as socioeconomically deprived were modest. Patterns within the data suggested prospective success for targeting these cohorts. CONCLUSIONS: SC attracted people in need of mental healthcare input and affected quantifiable change within those people's lives, while satisfying statutory demands for service delivery in an accessible community context. Recommendations to increase engagement with those traditionally 'hard-to-reach' for psychological services are provided, which, if implemented, have the potential to achieve further compliance with Northern Irish mental health statutory drivers.

2.
Leukemia ; 17(2): 390-400, 2003 Feb.
Article in English | MEDLINE | ID: mdl-12592339

ABSTRACT

Neutrophils and monocytes/macrophages are derived from common progenitors, but exhibit markedly different lifespans. Differentiated neutrophils are short-lived and die rapidly by apoptosis, while monocytic cells are longer-lived. In this report we used the HL-60 cell line as a model system to identify differences in apoptotic pathways which might account for the differing lifespans of granulocytic vs monocytic cells. We observed that induction of granulocytic differentiation by retinoic acid led to robust activation of the executioner protease caspase-3, and early onset of apoptosis. By contrast, caspase-3 was not appreciably activated during phorbol 12-myristate 13-acetate (PMA)-induced monocytic differentiation, and apoptosis was delayed in these cells. Since the activation of caspase-3 is inhibited by members of the inhibitor of apoptosis (IAP) and Bcl-2 protein families, we investigated the expression of anti-apoptotic members of these families. Induction of monocytic differentiation led to marked upregulation of the IAP protein XIAP, as well as the Bcl-2 family member Bcl-X(L). During granulocytic differentiation the levels of XIAP progressively declined, while Bcl-X(L) levels remained unchanged. A different IAP protein, survivin, was downregulated during differentiation along either lineage, as was expression of Bcl-2. The upregulation of Bcl-X(L) during monocytic differentiation coincided with phosphorylation/activation of STAT3, a known activator of bcl-X gene transcription. Moreover, Bcl-X(L) upregulation was dependent on MEK/ERK signaling. Upregulation of XIAP proceeded in a MEK/ERK-independent fashion. Treatment with antisense Bcl-X(L) or XIAP oligonucleotides resulted in significant loss of viability in cells differentiating along the monocytic lineage. Together, these findings indicate that the levels of XIAP and Bcl-X(L) are regulated by distinct pathways during monocytic differentiation, and that upregulation of these proteins contributes to the increased longevity of cells in the monocytic lineage.


Subject(s)
Apoptosis/physiology , Cell Differentiation/physiology , Cell Survival/physiology , Granulocytes/cytology , Monocytes/cytology , Proteins/metabolism , Proto-Oncogene Proteins c-bcl-2/metabolism , Apoptosis/drug effects , Caspase 3 , Caspases/metabolism , Cell Differentiation/drug effects , Cell Survival/drug effects , Enzyme Activation , HL-60 Cells , Homeostasis , Humans , Kinetics , Phorbol Esters/pharmacology , Proto-Oncogene Proteins c-bcl-2/genetics , Time Factors , Tretinoin/pharmacology , X-Linked Inhibitor of Apoptosis Protein , Zinc Fingers , bcl-X Protein
3.
Blood Cells Mol Dis ; 26(4): 320-30, 2000 Aug.
Article in English | MEDLINE | ID: mdl-11042034

ABSTRACT

Granulocyte colony-stimulating factor (G-CSF) is a cytokine critical for proliferation and differentiation of granulocytic precursors and neutrophil functions that has previously been demonstrated to activate Stat3 and Stat5, two members of the signal transducer and activator of transcription (STAT) protein family. Stat3 has been identified to be critical for G-CSF receptor (G-CSFR)-mediated signaling for granulocyte differentiation. Stat5 activation has been mapped to the proximal portion of the cytosolic region of the G-CSFR. However, delineation and mapping of the specific Stat5 isoforms activated by G-CSF in myeloid cells have not been reported. In this study, we demonstrated that G-CSF activated a Stat5 complex in human myeloid cells containing three isoforms of Stat5: Stat5A, Stat5B, and Stat5 p80. Activation of Stat5A and Stat5B maps to the proliferation-specific domain of the G-CSFR, whereas Stat5 p80 is recruited by phosphotyrosine-704 within the region of G-CSFR required for differentiation. G-CSF-activated Stat5A/B, but not Stat5 p80, formed a heterodimer with Stat3. The Stat5A/B-Stat3 heterodimer can bind to specific DNA sequences preferred by both Stat3 and Stat5. These findings are consistent with the possibility that Stat5 p80 contributes to G-CSF-induced myeloid differentiation.


Subject(s)
DNA-Binding Proteins/drug effects , Granulocyte Colony-Stimulating Factor/pharmacology , Milk Proteins , Myeloid Cells/drug effects , Trans-Activators/drug effects , Amino Acid Sequence , Binding Sites/genetics , DNA/metabolism , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Humans , Myeloid Cells/cytology , Myeloid Cells/metabolism , Phosphotyrosine/genetics , Phosphotyrosine/metabolism , Protein Binding/drug effects , Protein Isoforms/drug effects , Protein Isoforms/genetics , Protein Isoforms/metabolism , Receptors, Granulocyte Colony-Stimulating Factor/genetics , Receptors, Granulocyte Colony-Stimulating Factor/metabolism , STAT5 Transcription Factor , Trans-Activators/genetics , Trans-Activators/metabolism , Tumor Suppressor Proteins , U937 Cells
4.
Shock ; 13(6): 441-5, 2000 Jun.
Article in English | MEDLINE | ID: mdl-10847630

ABSTRACT

Inducible nitric oxide synthase (iNOS) can be coexpressed with acute phase reactants in hepatocytes; however, it is unknown if NO can regulate the acute phase response. We tested the hypothesis that iNOS-derived nitric oxide (NO) attenuates the acute phase response by inhibiting IL-6-enhanced Stat3 DNA-binding activity and type II acute phase mRNA expression. iNOS was overexpressed in cultured rat hepatocytes via transduction with a replication defective adenovirus containing cDNA for human iNOS (AdiNOS), and Stat3 DNA-binding activity was determined by electrophoretic mobility shift assay (EMSA). EMSAs demonstrated that AdiNOS inhibits IL-6-induced Stat3 activation and that this inhibition is reversible in the presence of the NOS inhibitor N(G)-monomethyl-L-arginine (L-NMA). The induction of beta-fibrinogen mRNA by IL-6, a Stat3 dependent process, is attenuated in AdiNOS-transduced cells and partially reversed by L-NMA. Thus, iNOS overexpression suppresses IL-6-induced Stat3 activation and type II acute phase mRNA expression in cultured hepatocytes. This suppression may represent a mechanism by which NO down-regulates the acute phase response.


Subject(s)
Acute-Phase Reaction/genetics , DNA-Binding Proteins/metabolism , Gene Expression Regulation/drug effects , Interleukin-6/antagonists & inhibitors , Nitric Oxide Synthase/physiology , Nitric Oxide/pharmacology , RNA, Messenger/biosynthesis , Trans-Activators/metabolism , Animals , Cells, Cultured , Enzyme Inhibitors/pharmacology , Fibrinogen/genetics , Humans , Liver/drug effects , Liver/metabolism , Male , Nitrates/metabolism , Nitric Oxide Synthase/genetics , Nitric Oxide Synthase/metabolism , Nitric Oxide Synthase Type II , Nitrites/metabolism , Phosphorylation , Protein Processing, Post-Translational , RNA, Messenger/genetics , Rats , Rats, Sprague-Dawley , Recombinant Fusion Proteins/metabolism , STAT3 Transcription Factor , Transfection , omega-N-Methylarginine/pharmacology
5.
Mol Med ; 5(1): 11-20, 1999 Jan.
Article in English | MEDLINE | ID: mdl-10072444

ABSTRACT

BACKGROUND: In the setting of familial melanoma, the presence of atypical nevi, which are the precursors of melanoma, is associated with a nearly 100% risk of developing primary melanoma by age 70. In patients with sporadic melanoma, it is estimated that 40-60% of melanomas develop in contiguous association with atypical nevi. Currently, the only way to prevent atypical nevi from progressing to melanoma is to monitor and excise them as soon as they exhibit changes in their clinical features. Activation of the transcription factor, Stat3, has been linked to abnormal cell growth and transformation as well as to interferon alpha (IFN-alpha)-mediated growth suppression in vitro. MATERIALS AND METHODS: To determine whether IFN-alpha, used for adjuvant therapy of high-risk, resected melanoma, induces changes in Stat3 in atypical nevi, patients with a clinical history of melanoma who have multiple atypical nevi were treated for 3 months with low-dose IFN-alpha. Thereupon, the new technology of microscopic spectral imaging and biochemical assays such as electrophoretic mobility shift assays (EMSAs) and immunoblot analysis were used for the study of atypical nevi, obtained before and after IFN-alpha treatment. RESULTS: The results of the investigations provided evidence that, as a result of systemic IFN-alpha treatment, Stat1 and Stat3, which are constitutively activated in melanoma precursor lesions, lose their ability to bind DNA, and as shown in the case of Stat3, become dephosphorylated. CONCLUSIONS: Unlike primary and metastatic melanomas, melanoma precursor lesions cannot be established as cell cultures. Thus, the only way to explore pathways and treatment regimens that might help prevent progression to melanoma is within the context of a melanoma precursor lesion study conducted prospectively. The findings presented here suggest that down-regulation of the transcription factors Stat1 and Stat3 by systemic IFN-alpha treatment may represent a potential pathway to prevent the activation of gene(s) whose expression may be required for atypical nevus cells to progress to melanoma.


Subject(s)
DNA-Binding Proteins/antagonists & inhibitors , Interferon-alpha/therapeutic use , Melanoma/metabolism , Melanoma/therapy , Precancerous Conditions/metabolism , Precancerous Conditions/therapy , Skin Neoplasms/metabolism , Skin Neoplasms/therapy , Trans-Activators/antagonists & inhibitors , Aged , DNA, Neoplasm/metabolism , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Down-Regulation , Humans , Immunohistochemistry , In Vitro Techniques , Interferon alpha-2 , Melanoma/genetics , Phosphorylation , Precancerous Conditions/genetics , Recombinant Proteins , STAT1 Transcription Factor , STAT3 Transcription Factor , Skin Neoplasms/genetics , Trans-Activators/genetics , Trans-Activators/metabolism
6.
Blood ; 93(1): 15-24, 1999 Jan 01.
Article in English | MEDLINE | ID: mdl-9864141

ABSTRACT

Stat3 is essential for early embryonic development and for myeloid differentiation induced by the cytokines granulocyte colony-stimulating factor (G-CSF) and interleukin-6 (IL-6). Two isoforms of Stat3 have been identified, (p92) and beta (p83), which have distinct transcriptional and biological functions. Activation of both Stat3 and Stat3beta requires the distal cytoplasmic domain of the G-CSFR, which contains four Tyr at positions 704, 729, 744, and 764. The studies reported here were undertaken to determine which, if any, of these tyrosine residues participated in Stat3/beta recruitment and activation. We showed that Stat3 and Stat3beta were affinity purified using phosphopeptides containing Y704 and Y744 but not by nonphosphorylated peptide analogues or by phosphopeptides containing Y729 and Y764. Complementary results were obtained in studies examining the ability of these peptides to destabilize and inhibit DNA binding of activated Stat3. Both Y704 and Y744 contributed to optimal activation of Stat3/beta in M1 murine myeloid leukemia cells containing wild-type and Y-to-F mutant G-CSFR constructs. Carboxy-terminal to Y704 at the +3 position is Gln; YXXQ represents a consensus Stat3 recruitment and activation motif. Y744 is followed at the +3 position by Cys (C); YXXC, represents a novel motif implicated in the recruitment and activation of Stat3. Modeling of the SH2 domain of Stat3 based on homologous SH2 domains of known structure revealed polar residues whose side chains contact the +3 position. This substitution may confer specificity for the Y704- and Y744-based ligands by allowing H-bond formation between the binding surface and the Gln or Cys found at the respective +3 position.


Subject(s)
DNA-Binding Proteins/metabolism , Receptors, Granulocyte Colony-Stimulating Factor/metabolism , Trans-Activators/metabolism , Amino Acid Sequence , Amino Acid Substitution/genetics , Animals , Binding, Competitive/genetics , Cell Line , DNA-Binding Proteins/antagonists & inhibitors , DNA-Binding Proteins/isolation & purification , Granulocyte Colony-Stimulating Factor/physiology , Humans , Mice , Molecular Sequence Data , Mutagenesis, Site-Directed , Peptide Fragments/biosynthesis , Peptide Fragments/genetics , Phosphopeptides/isolation & purification , Phosphopeptides/metabolism , Phosphopeptides/pharmacology , Protein Binding/drug effects , Receptors, Granulocyte Colony-Stimulating Factor/biosynthesis , Receptors, Granulocyte Colony-Stimulating Factor/genetics , STAT3 Transcription Factor , Signal Transduction , Trans-Activators/antagonists & inhibitors , Trans-Activators/isolation & purification , Tumor Cells, Cultured , Tyrosine/genetics , Tyrosine/metabolism
7.
J Immunol ; 160(12): 6056-61, 1998 Jun 15.
Article in English | MEDLINE | ID: mdl-9637522

ABSTRACT

Kupffer cells were the principal source of IL-6 produced in the livers of mice following i.v. inoculation of Listeria monocytogenes. IL-6 mRNA expression and the production of IL-6 were reduced drastically within the nonparenchymal liver cell population derived from mice rendered Kupffer cell depleted by pretreatment with liposome-encapsulated dichloromethylene diphosphonate. A sharp increase in the appearance of activated STAT3 occurred in extracts of purified hepatocytes derived from normal mice infected i.v. with Listeria. Remarkably, the kinetics of this increase overlapped IL-6 mRNA expression by Kupffer cells; each peaked at approximately 30 min postinfection. No increase in STAT3 activation was observed in IL-6-deficient or Kupffer cell-depleted animals. The results of these experiments indicate that the synthesis of IL-6 and the activation of STAT3 within hepatocytes are critical functions of Kupffer cells occurring very early during the course of systemic listerial infections.


Subject(s)
Acute-Phase Proteins/metabolism , DNA-Binding Proteins/metabolism , Interleukin-6/biosynthesis , Kupffer Cells/metabolism , Listeriosis/immunology , Liver/metabolism , Trans-Activators/metabolism , Animals , Female , Interleukin-6/genetics , Kupffer Cells/microbiology , Liver/microbiology , Mice , Mice, Inbred C57BL , STAT1 Transcription Factor , STAT3 Transcription Factor
8.
J Immunol ; 158(12): 5744-50, 1997 Jun 15.
Article in English | MEDLINE | ID: mdl-9190924

ABSTRACT

IL-7, a cytokine produced by bone marrow and thymic stroma, is a growth factor for B and T lymphocytes very early in their development. The IL-7R is a heterodimer of an alpha-chain that specifically binds IL-7 and the common gamma-chain, gamma(c), which is also a component of the receptors for IL-2, IL-4, IL-9, and IL-15. IL-7 has also been hypothesized to play a role in the differentiation of gammadelta T cells, which is supported by the recent findings that mice deficient in the alpha-chain of the IL-7R (IL-7R alpha -/-) or IL-7 (IL-7 -/-) have a complete absence of gammadelta T cells, but not alphabeta T cells. We show in this work that Vgamma4 and Vgamma6 TCR genes are rearranged, and sterile Vgamma4 and Vgamma6 TCR-gamma transcripts are expressed in IL-7R alpha -/- thymocytes, but these TCR-gamma genes, and Vgamma5, are not transcribed in thymocytes from IL-7R alpha -/- mice. RAG-1 and RAG-2 genes are transcriptionally active in fetal and adult IL-7R alpha -/- thymocytes. The IL-7-inducible transcription factor, STAT5, is not active in the fetal thymus of IL-7R alpha -/- compared with IL-7R alpha +/+ mice. These data point to a specific role for IL-7/IL-7R signaling in regulating the transcriptional activity, possibly mediated by STAT5, of the rearranged TCR-gamma complex during development of gammadelta T cells, and point to mechanistic differences in the regulation of rearrangement of Vgamma4 and Vgamma6 genes vs Vgamma5.


Subject(s)
Gene Rearrangement, gamma-Chain T-Cell Antigen Receptor/genetics , Interleukin-7 , Milk Proteins , Receptors, Interleukin/deficiency , Transcription, Genetic , Animals , DNA-Binding Proteins/analysis , Female , Male , Mice , Mice, Inbred C57BL , Mice, Mutant Strains , Receptors, Antigen, T-Cell, gamma-delta/analysis , STAT5 Transcription Factor , Trans-Activators/analysis
9.
Blood ; 88(7): 2442-9, 1996 Oct 01.
Article in English | MEDLINE | ID: mdl-8839834

ABSTRACT

Granulocyte colony-stimulating factor (G-CSF) is the cytokine critical for directing neutrophilic granulocyte differentiation. Acute myelogenous leukemia (AML) cells, which frequently arise from this lineage, respond aberrantly to G-CSF by proliferating without differentiating. The basis for this abnormal responses is unknown. In the present study, we investigated whether G-CSF signaling in immature normal and leukemic human myeloid cells diverges at the level of activation of signal transducers and activators of transcription (STAT) proteins. We compared the profile of STAT proteins activated in G-CSF-stimulated immature normal and leukemic human myeloid cells. G-CSF activated Stat3 alpha in all AML cell lines examined except HL60 and in three of six uncultured AML patient samples. In normal human CD34+ bone marrow cells and HL60 cells, both reported to differentiate in response to G-CSF, G-CSF did not activate Stat3 alpha; rather, it activated only an 83 kD form of Stat3 that proved to be the human homologue of a short form of Stat3, Stat3 beta. Because the transcriptional activity of Stat3 beta is distinct from Stat3 alpha, these results suggest that the balance of the two Stat3 isoforms in myeloid cells may influence the cellular pattern of gene activation and consequently the ability of these cells to differentiate in response to G-CSF.


Subject(s)
DNA-Binding Proteins/metabolism , Gene Expression Regulation, Leukemic/drug effects , Granulocyte Colony-Stimulating Factor/pharmacology , Hematopoietic Stem Cells/drug effects , Leukemia, Myeloid/metabolism , Neoplasm Proteins/metabolism , Neoplastic Stem Cells/drug effects , Trans-Activators/metabolism , Acute Disease , Amino Acid Sequence , Base Sequence , Cell Differentiation/drug effects , Hematopoietic Stem Cells/metabolism , Humans , Leukemia, Myeloid/pathology , Molecular Sequence Data , Neoplastic Stem Cells/metabolism , STAT3 Transcription Factor , Signal Transduction/drug effects , Transcriptional Activation , Tumor Cells, Cultured
10.
Blood ; 86(12): 4409-16, 1995 Dec 15.
Article in English | MEDLINE | ID: mdl-8541528

ABSTRACT

Binding of granulocyte colony-stimulating factor (G-CSF) to normal myeloid cells activates the protein tyrosine kinases Lyn and Syk and results in the immediate early upregulation of G-CSF receptor (R) mRNA. In our studies of the signaling pathways activated by G-CSF that are coupled to proliferation and differentiation of myeloid cells, we examined whether G-CSF activated a latent transcription factor belonging to the STAT protein family. Electrophoretic mobility shift assays (EMSAs) of nuclear extracts from G-CSF-stimulated human myeloid cells showed the rapid activation of a DNA-binding protein that bound to the high-affinity serum-inducible element (hSIE) and migrated with mobility similar to serum inducible factor (SIF)-A (Stat3 homodimer). The G-CSF-stimulated SIF-A complex (G-SIF-A) did not bind to duplex oligonucleotides used to purify and characterize other Stat proteins (Stat1-6). In addition, antibodies raised against Stat1-6 failed to supershift the G-SIF-A complex or interfere with its formation. Based on its binding to the hSIE and lack of antigenic cross-reactivity with other known STAT proteins that bind to this element, it is likely that G-SIF-A is composed of a distinct member of the STAT protein family. EMSAs of whole-cell extracts prepared from cell lines containing full-length and truncated mutants of the G-CSFR showed that activation of G-SIF-A did not correlate with proliferation; rather, optimal activation requires the distal half of the cytosolic domain of the G-CSFR that is essential for differentiation. Activation of G-SIF-A, therefore, may be an early G-CSFR-coupled event that is critical for myeloid maturation.


Subject(s)
B-Lymphocytes/drug effects , DNA-Binding Proteins/metabolism , Gene Expression Regulation/drug effects , Granulocyte Colony-Stimulating Factor/pharmacology , Hematopoietic Stem Cells/drug effects , Neutrophils/drug effects , Signal Transduction/physiology , Trans-Activators/metabolism , Base Sequence , Cell Differentiation/drug effects , Cell Line , Cells, Cultured , DNA-Binding Proteins/isolation & purification , Enzyme Precursors/metabolism , Humans , Interferon-gamma/pharmacology , Intracellular Signaling Peptides and Proteins , Macromolecular Substances , Molecular Sequence Data , Protein Binding , Protein-Tyrosine Kinases/metabolism , Recombinant Proteins/pharmacology , Syk Kinase , Trans-Activators/isolation & purification , Transcription, Genetic/drug effects , src-Family Kinases/metabolism
11.
J Biosoc Sci ; 18(2): 169-77, 1986 Apr.
Article in English | MEDLINE | ID: mdl-3700449
12.
Am J Epidemiol ; 119(4): 473-86, 1984 Apr.
Article in English | MEDLINE | ID: mdl-6711537

ABSTRACT

A case-control study, carried out in the Mount Gambier region of South Australia, investigated the relationship between mothers' antenatal drinking water source and malformations in offspring. It was prompted by earlier descriptive findings of a statistically significant, and localized, increase in the perinatal mortality rate in Mount Gambier, due principally to congenital malformations affecting the central nervous system and multiple organ systems. Available for statistical analysis were 218 case-control pairs, from the period 1951-1979, individually matched by hospital, maternal age (+/- 2 years), parity and date of birth (+/- 1 month). Compared with women who drank only rainwater during their pregnancy (relative risk (RR) = 1.0), women who consumed principally groundwater had a statistically significant increase in risk of bearing a malformed child (RR = 2.8). Statistically significant risk increases occurred specifically for malformations of the central nervous system and musculoskeletal system. Reanalysis of the data by estimated water nitrate concentration demonstrated a nearly threefold increase in risk for women who drank water containing 5-15 ppm of nitrate, and a fourfold increase in risk for those consuming greater than 15 ppm of nitrate. A seasonal gradient in risk was evident among groundwater consumers, ranging from 0.9 for babies conceived in winter, 3.0 in autumn, to 7.0 and 6.3 for spring and summer conceptions, respectively. Linear logistic regression analysis, controlling for risk factors not accounted for in the study design, showed that maternal water supply, infant's sex, and mother's area of residence all contributed significantly to the risk of malformation. These results are discussed in relation to previous experimental and human descriptive studies, suggesting a plausible mechanism for nitrate-induced teratogenesis.


Subject(s)
Abnormalities, Drug-Induced/epidemiology , Nitrates/analysis , Water Pollutants, Chemical/adverse effects , Water Pollutants/adverse effects , Water Supply , Abnormalities, Drug-Induced/etiology , Adult , Australia , Female , Humans , Infant, Newborn , Male , Maternal Age , Nitrates/adverse effects , Parity , Pregnancy , Regression Analysis , Retrospective Studies , Risk , Rural Population , Seasons , Sex Factors , Water Supply/analysis
18.
Mutat Res ; 28(3): 405-20, 1975 Jun.
Article in English | MEDLINE | ID: mdl-806014

ABSTRACT

140 Organophosphorus compounds (OP's) have been tested for mutagenic activity in bacteria, principally by using two specially constructed sets of tester strains of the bacteria Salmonella typhimurium and Escherichia coli. It was found that 20% gave positive mutagenic responses and that this group of chemicals produce base subsitutions rather than frame-shift mutations. In most cases the DNA repair genes exrA+ and recA+ were required for mutagenic activity. Seven compounds were further tested in Drosophila melanogaster for the ability to induce recessive lethal mutations. In some of these cases the doses administered to the flies had to be very low due to the highly toxic nature of the compounds. To over-come this problem, the accumulation of recessive lethal mutations was measured in populations which were continually exposed to the compounds over a period of some 18 months. During this time the populations developed increased resistance to the compound and so the dose administered could gradually be increased. Six of the compounds were mutagenic. Of the compounds tested in both systems, those showing mutagenic activity in bacteria were also mutagenic in Drosophila, those not mutagenic in bacteria were not mutagenic in Drosophila.


Subject(s)
Drosophila melanogaster/drug effects , Escherichia coli/drug effects , Mutagens , Organophosphorus Compounds/pharmacology , Salmonella typhimurium/drug effects , Animals , DNA Repair , DNA Replication , Drosophila melanogaster/metabolism , Escherichia coli/metabolism , Female , Genes, Lethal , Genes, Recessive , Male , Mutation , Salmonella typhimurium/metabolism , Time Factors
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